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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* SCTP kernel implementation
  * (C) Copyright IBM Corp. 2001, 2004
  * Copyright (c) 1999-2000 Cisco, Inc.
  * Copyright (c) 1999-2001 Motorola, Inc.
  * Copyright (c) 2001-2002 Intel Corp.
  * Copyright (c) 2002      Nokia Corp.
  *
  * This is part of the SCTP Linux Kernel Implementation.
  *
  * These are the state functions for the state machine.
  *
  * Please send any bug reports or fixes you make to the
  * email address(es):
  *    lksctp developers <linux-sctp@vger.kernel.org>
  *
  * Written or modified by:
  *    La Monte H.P. Yarroll <piggy@acm.org>
  *    Karl Knutson          <karl@athena.chicago.il.us>
  *    Mathew Kotowsky       <kotowsky@sctp.org>
  *    Sridhar Samudrala     <samudrala@us.ibm.com>
  *    Jon Grimm             <jgrimm@us.ibm.com>
  *    Hui Huang         <hui.huang@nokia.com>
  *    Dajiang Zhang         <dajiang.zhang@nokia.com>
  *    Daisy Chang       <daisyc@us.ibm.com>
  *    Ardelle Fan       <ardelle.fan@intel.com>
  *    Ryan Layer        <rmlayer@us.ibm.com>
  *    Kevin Gao         <kevin.gao@intel.com>
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/net.h>
 #include <linux/inet.h>
 #include <linux/slab.h>
 #include <net/sock.h>
 #include <net/inet_ecn.h>
 #include <linux/skbuff.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
 #include <net/sctp/structs.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/sctp.h>
 
 static struct sctp_packet *sctp_abort_pkt_new(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     const void *payload, size_t paylen);
 static int sctp_eat_data(const struct sctp_association *asoc,
              struct sctp_chunk *chunk,
              struct sctp_cmd_seq *commands);
 static struct sctp_packet *sctp_ootb_pkt_new(
                     struct net *net,
                     const struct sctp_association *asoc,
                     const struct sctp_chunk *chunk);
 static void sctp_send_stale_cookie_err(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const struct sctp_chunk *chunk,
                        struct sctp_cmd_seq *commands,
                        struct sctp_chunk *err_chunk);
 static enum sctp_disposition sctp_sf_do_5_2_6_stale(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 static enum sctp_disposition sctp_sf_shut_8_4_5(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 static enum sctp_disposition sctp_sf_tabort_8_4_8(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 static enum sctp_disposition sctp_sf_new_encap_port(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk);
 
 static enum sctp_disposition sctp_stop_t1_and_abort(
                     struct net *net,
                     struct sctp_cmd_seq *commands,
                     __be16 error, int sk_err,
                     const struct sctp_association *asoc,
                     struct sctp_transport *transport);
 
 static enum sctp_disposition sctp_sf_abort_violation(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     void *arg,
                     struct sctp_cmd_seq *commands,
                     const __u8 *payload,
                     const size_t paylen);
 
 static enum sctp_disposition sctp_sf_violation_chunklen(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 
 static enum sctp_disposition sctp_sf_violation_paramlen(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg, void *ext,
                     struct sctp_cmd_seq *commands);
 
 static enum sctp_disposition sctp_sf_violation_ctsn(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 
 static enum sctp_disposition sctp_sf_violation_chunk(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 
 static enum sctp_ierror sctp_sf_authenticate(
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk);
 
 static enum sctp_disposition __sctp_sf_do_9_1_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands);
 
 static enum sctp_disposition
 __sctp_sf_do_9_2_reshutack(struct net *net, const struct sctp_endpoint *ep,
                const struct sctp_association *asoc,
                const union sctp_subtype type, void *arg,
                struct sctp_cmd_seq *commands);
 
 /* Small helper function that checks if the chunk length
  * is of the appropriate length.  The 'required_length' argument
  * is set to be the size of a specific chunk we are testing.
  * Return Values:  true  = Valid length
  *         false = Invalid length
  *
  */
 static inline bool sctp_chunk_length_valid(struct sctp_chunk *chunk,
                        __u16 required_length)
 {
     __u16 chunk_length = ntohs(chunk->chunk_hdr->length);
 
     /* Previously already marked? */
     if (unlikely(chunk->pdiscard))
         return false;
     if (unlikely(chunk_length < required_length))
         return false;
 
     return true;
 }
 
 /* Check for format error in an ABORT chunk */
 static inline bool sctp_err_chunk_valid(struct sctp_chunk *chunk)
 {
     struct sctp_errhdr *err;
 
     sctp_walk_errors(err, chunk->chunk_hdr);
 
     return (void *)err == (void *)chunk->chunk_end;
 }
 
 /**********************************************************
  * These are the state functions for handling chunk events.
  **********************************************************/
 
 /*
  * Process the final SHUTDOWN COMPLETE.
  *
  * Section: 4 (C) (diagram), 9.2
  * Upon reception of the SHUTDOWN COMPLETE chunk the endpoint will verify
  * that it is in SHUTDOWN-ACK-SENT state, if it is not the chunk should be
  * discarded. If the endpoint is in the SHUTDOWN-ACK-SENT state the endpoint
  * should stop the T2-shutdown timer and remove all knowledge of the
  * association (and thus the association enters the CLOSED state).
  *
  * Verification Tag: 8.5.1(C), sctpimpguide 2.41.
  * C) Rules for packet carrying SHUTDOWN COMPLETE:
  * ...
  * - The receiver of a SHUTDOWN COMPLETE shall accept the packet
  *   if the Verification Tag field of the packet matches its own tag and
  *   the T bit is not set
  *   OR
  *   it is set to its peer's tag and the T bit is set in the Chunk
  *   Flags.
  *   Otherwise, the receiver MUST silently discard the packet
  *   and take no further action.  An endpoint MUST ignore the
  *   SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_4_C(struct net *net,
                      const struct sctp_endpoint *ep,
                      const struct sctp_association *asoc,
                      const union sctp_subtype type,
                      void *arg, struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_ulpevent *ev;
 
     if (!sctp_vtag_verify_either(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* RFC 2960 6.10 Bundling
      *
      * An endpoint MUST NOT bundle INIT, INIT ACK or
      * SHUTDOWN COMPLETE with any other chunks.
      */
     if (!chunk->singleton)
         return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the SHUTDOWN_COMPLETE chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* RFC 2960 10.2 SCTP-to-ULP
      *
      * H) SHUTDOWN COMPLETE notification
      *
      * When SCTP completes the shutdown procedures (section 9.2) this
      * notification is passed to the upper layer.
      */
     ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP,
                          0, 0, 0, NULL, GFP_ATOMIC);
     if (ev)
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(ev));
 
     /* Upon reception of the SHUTDOWN COMPLETE chunk the endpoint
      * will verify that it is in SHUTDOWN-ACK-SENT state, if it is
      * not the chunk should be discarded. If the endpoint is in
      * the SHUTDOWN-ACK-SENT state the endpoint should stop the
      * T2-shutdown timer and remove all knowledge of the
      * association (and thus the association enters the CLOSED
      * state).
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_CLOSED));
 
     SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
 
     return SCTP_DISPOSITION_DELETE_TCB;
 }
 
 /*
  * Respond to a normal INIT chunk.
  * We are the side that is being asked for an association.
  *
  * Section: 5.1 Normal Establishment of an Association, B
  * B) "Z" shall respond immediately with an INIT ACK chunk.  The
  *    destination IP address of the INIT ACK MUST be set to the source
  *    IP address of the INIT to which this INIT ACK is responding.  In
  *    the response, besides filling in other parameters, "Z" must set the
  *    Verification Tag field to Tag_A, and also provide its own
  *    Verification Tag (Tag_Z) in the Initiate Tag field.
  *
  * Verification Tag: Must be 0.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_1B_init(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg, *repl, *err_chunk;
     struct sctp_unrecognized_param *unk_param;
     struct sctp_association *new_asoc;
     struct sctp_packet *packet;
     int len;
 
     /* 6.10 Bundling
      * An endpoint MUST NOT bundle INIT, INIT ACK or
      * SHUTDOWN COMPLETE with any other chunks.
      *
      * IG Section 2.11.2
      * Furthermore, we require that the receiver of an INIT chunk MUST
      * enforce these rules by silently discarding an arriving packet
      * with an INIT chunk that is bundled with other chunks.
      */
     if (!chunk->singleton)
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the INIT chunk has a valid length.
      * Normally, this would cause an ABORT with a Protocol Violation
      * error, but since we don't have an association, we'll
      * just discard the packet.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_init_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* If the packet is an OOTB packet which is temporarily on the
      * control endpoint, respond with an ABORT.
      */
     if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
         SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
     }
 
     /* 3.1 A packet containing an INIT chunk MUST have a zero Verification
      * Tag.
      */
     if (chunk->sctp_hdr->vtag != 0)
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
 
     /* If the INIT is coming toward a closing socket, we'll send back
      * and ABORT.  Essentially, this catches the race of INIT being
      * backloged to the socket at the same time as the user issues close().
      * Since the socket and all its associations are going away, we
      * can treat this OOTB
      */
     if (sctp_sstate(ep->base.sk, CLOSING))
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
 
     /* Verify the INIT chunk before processing it. */
     err_chunk = NULL;
     if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
                   (struct sctp_init_chunk *)chunk->chunk_hdr, chunk,
                   &err_chunk)) {
         /* This chunk contains fatal error. It is to be discarded.
          * Send an ABORT, with causes if there is any.
          */
         if (err_chunk) {
             packet = sctp_abort_pkt_new(net, ep, asoc, arg,
                     (__u8 *)(err_chunk->chunk_hdr) +
                     sizeof(struct sctp_chunkhdr),
                     ntohs(err_chunk->chunk_hdr->length) -
                     sizeof(struct sctp_chunkhdr));
 
             sctp_chunk_free(err_chunk);
 
             if (packet) {
                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
                         SCTP_PACKET(packet));
                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
                 return SCTP_DISPOSITION_CONSUME;
             } else {
                 return SCTP_DISPOSITION_NOMEM;
             }
         } else {
             return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
                             commands);
         }
     }
 
     /* Grab the INIT header.  */
     chunk->subh.init_hdr = (struct sctp_inithdr *)chunk->skb->data;
 
     /* Tag the variable length parameters.  */
     chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr));
 
     new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
     if (!new_asoc)
         goto nomem;
 
     /* Update socket peer label if first association. */
     if (security_sctp_assoc_request(new_asoc, chunk->skb)) {
         sctp_association_free(new_asoc);
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
                          sctp_scope(sctp_source(chunk)),
                          GFP_ATOMIC) < 0)
         goto nomem_init;
 
     /* The call, sctp_process_init(), can fail on memory allocation.  */
     if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
                    (struct sctp_init_chunk *)chunk->chunk_hdr,
                    GFP_ATOMIC))
         goto nomem_init;
 
     /* B) "Z" shall respond immediately with an INIT ACK chunk.  */
 
     /* If there are errors need to be reported for unknown parameters,
      * make sure to reserve enough room in the INIT ACK for them.
      */
     len = 0;
     if (err_chunk)
         len = ntohs(err_chunk->chunk_hdr->length) -
               sizeof(struct sctp_chunkhdr);
 
     repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
     if (!repl)
         goto nomem_init;
 
     /* If there are errors need to be reported for unknown parameters,
      * include them in the outgoing INIT ACK as "Unrecognized parameter"
      * parameter.
      */
     if (err_chunk) {
         /* Get the "Unrecognized parameter" parameter(s) out of the
          * ERROR chunk generated by sctp_verify_init(). Since the
          * error cause code for "unknown parameter" and the
          * "Unrecognized parameter" type is the same, we can
          * construct the parameters in INIT ACK by copying the
          * ERROR causes over.
          */
         unk_param = (struct sctp_unrecognized_param *)
                 ((__u8 *)(err_chunk->chunk_hdr) +
                 sizeof(struct sctp_chunkhdr));
         /* Replace the cause code with the "Unrecognized parameter"
          * parameter type.
          */
         sctp_addto_chunk(repl, len, unk_param);
         sctp_chunk_free(err_chunk);
     }
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
 
     /*
      * Note:  After sending out INIT ACK with the State Cookie parameter,
      * "Z" MUST NOT allocate any resources, nor keep any states for the
      * new association.  Otherwise, "Z" will be vulnerable to resource
      * attacks.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
 
     return SCTP_DISPOSITION_DELETE_TCB;
 
 nomem_init:
     sctp_association_free(new_asoc);
 nomem:
     if (err_chunk)
         sctp_chunk_free(err_chunk);
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Respond to a normal INIT ACK chunk.
  * We are the side that is initiating the association.
  *
  * Section: 5.1 Normal Establishment of an Association, C
  * C) Upon reception of the INIT ACK from "Z", "A" shall stop the T1-init
  *    timer and leave COOKIE-WAIT state. "A" shall then send the State
  *    Cookie received in the INIT ACK chunk in a COOKIE ECHO chunk, start
  *    the T1-cookie timer, and enter the COOKIE-ECHOED state.
  *
  *    Note: The COOKIE ECHO chunk can be bundled with any pending outbound
  *    DATA chunks, but it MUST be the first chunk in the packet and
  *    until the COOKIE ACK is returned the sender MUST NOT send any
  *    other packets to the peer.
  *
  * Verification Tag: 3.3.3
  *   If the value of the Initiate Tag in a received INIT ACK chunk is
  *   found to be 0, the receiver MUST treat it as an error and close the
  *   association by transmitting an ABORT.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_1C_ack(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg,
                       struct sctp_cmd_seq *commands)
 {
     struct sctp_init_chunk *initchunk;
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *err_chunk;
     struct sctp_packet *packet;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* 6.10 Bundling
      * An endpoint MUST NOT bundle INIT, INIT ACK or
      * SHUTDOWN COMPLETE with any other chunks.
      */
     if (!chunk->singleton)
         return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the INIT-ACK chunk has a valid length */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_initack_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
     /* Grab the INIT header.  */
     chunk->subh.init_hdr = (struct sctp_inithdr *)chunk->skb->data;
 
     /* Verify the INIT chunk before processing it. */
     err_chunk = NULL;
     if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
                   (struct sctp_init_chunk *)chunk->chunk_hdr, chunk,
                   &err_chunk)) {
 
         enum sctp_error error = SCTP_ERROR_NO_RESOURCE;
 
         /* This chunk contains fatal error. It is to be discarded.
          * Send an ABORT, with causes.  If there are no causes,
          * then there wasn't enough memory.  Just terminate
          * the association.
          */
         if (err_chunk) {
             packet = sctp_abort_pkt_new(net, ep, asoc, arg,
                     (__u8 *)(err_chunk->chunk_hdr) +
                     sizeof(struct sctp_chunkhdr),
                     ntohs(err_chunk->chunk_hdr->length) -
                     sizeof(struct sctp_chunkhdr));
 
             sctp_chunk_free(err_chunk);
 
             if (packet) {
                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
                         SCTP_PACKET(packet));
                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
                 error = SCTP_ERROR_INV_PARAM;
             }
         }
 
         /* SCTP-AUTH, Section 6.3:
          *    It should be noted that if the receiver wants to tear
          *    down an association in an authenticated way only, the
          *    handling of malformed packets should not result in
          *    tearing down the association.
          *
          * This means that if we only want to abort associations
          * in an authenticated way (i.e AUTH+ABORT), then we
          * can't destroy this association just because the packet
          * was malformed.
          */
         if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
             return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED,
                         asoc, chunk->transport);
     }
 
     /* Tag the variable length parameters.  Note that we never
      * convert the parameters in an INIT chunk.
      */
     chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr));
 
     initchunk = (struct sctp_init_chunk *)chunk->chunk_hdr;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_PEER_INIT,
             SCTP_PEER_INIT(initchunk));
 
     /* Reset init error count upon receipt of INIT-ACK.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
 
     /* 5.1 C) "A" shall stop the T1-init timer and leave
      * COOKIE-WAIT state.  "A" shall then ... start the T1-cookie
      * timer, and enter the COOKIE-ECHOED state.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_COOKIE_ECHOED));
 
     /* SCTP-AUTH: generate the association shared keys so that
      * we can potentially sign the COOKIE-ECHO.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_SHKEY, SCTP_NULL());
 
     /* 5.1 C) "A" shall then send the State Cookie received in the
      * INIT ACK chunk in a COOKIE ECHO chunk, ...
      */
     /* If there is any errors to report, send the ERROR chunk generated
      * for unknown parameters as well.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_GEN_COOKIE_ECHO,
             SCTP_CHUNK(err_chunk));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,
                    const struct sctp_association *asoc)
 {
     struct sctp_chunk auth;
 
     if (!chunk->auth_chunk)
         return true;
 
     /* SCTP-AUTH:  auth_chunk pointer is only set when the cookie-echo
      * is supposed to be authenticated and we have to do delayed
      * authentication.  We've just recreated the association using
      * the information in the cookie and now it's much easier to
      * do the authentication.
      */
 
     /* Make sure that we and the peer are AUTH capable */
     if (!net->sctp.auth_enable || !asoc->peer.auth_capable)
         return false;
 
     /* set-up our fake chunk so that we can process it */
     auth.skb = chunk->auth_chunk;
     auth.asoc = chunk->asoc;
     auth.sctp_hdr = chunk->sctp_hdr;
     auth.chunk_hdr = (struct sctp_chunkhdr *)
                 skb_push(chunk->auth_chunk,
                      sizeof(struct sctp_chunkhdr));
     skb_pull(chunk->auth_chunk, sizeof(struct sctp_chunkhdr));
     auth.transport = chunk->transport;
 
     return sctp_sf_authenticate(asoc, &auth) == SCTP_IERROR_NO_ERROR;
 }
 
 /*
  * Respond to a normal COOKIE ECHO chunk.
  * We are the side that is being asked for an association.
  *
  * Section: 5.1 Normal Establishment of an Association, D
  * D) Upon reception of the COOKIE ECHO chunk, Endpoint "Z" will reply
  *    with a COOKIE ACK chunk after building a TCB and moving to
  *    the ESTABLISHED state. A COOKIE ACK chunk may be bundled with
  *    any pending DATA chunks (and/or SACK chunks), but the COOKIE ACK
  *    chunk MUST be the first chunk in the packet.
  *
  *   IMPLEMENTATION NOTE: An implementation may choose to send the
  *   Communication Up notification to the SCTP user upon reception
  *   of a valid COOKIE ECHO chunk.
  *
  * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules
  * D) Rules for packet carrying a COOKIE ECHO
  *
  * - When sending a COOKIE ECHO, the endpoint MUST use the value of the
  *   Initial Tag received in the INIT ACK.
  *
  * - The receiver of a COOKIE ECHO follows the procedures in Section 5.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
                      const struct sctp_endpoint *ep,
                      const struct sctp_association *asoc,
                      const union sctp_subtype type,
                      void *arg,
                      struct sctp_cmd_seq *commands)
 {
     struct sctp_ulpevent *ev, *ai_ev = NULL, *auth_ev = NULL;
     struct sctp_association *new_asoc;
     struct sctp_init_chunk *peer_init;
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *err_chk_p;
     struct sctp_chunk *repl;
     struct sock *sk;
     int error = 0;
 
     if (asoc && !sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* If the packet is an OOTB packet which is temporarily on the
      * control endpoint, respond with an ABORT.
      */
     if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
         SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
     }
 
     /* Make sure that the COOKIE_ECHO chunk has a valid length.
      * In this case, we check that we have enough for at least a
      * chunk header.  More detailed verification is done
      * in sctp_unpack_cookie().
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* If the endpoint is not listening or if the number of associations
      * on the TCP-style socket exceed the max backlog, respond with an
      * ABORT.
      */
     sk = ep->base.sk;
     if (!sctp_sstate(sk, LISTENING) ||
         (sctp_style(sk, TCP) && sk_acceptq_is_full(sk)))
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
 
     /* "Decode" the chunk.  We have no optional parameters so we
      * are in good shape.
      */
     chunk->subh.cookie_hdr =
         (struct sctp_signed_cookie *)chunk->skb->data;
     if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
                      sizeof(struct sctp_chunkhdr)))
         goto nomem;
 
     /* 5.1 D) Upon reception of the COOKIE ECHO chunk, Endpoint
      * "Z" will reply with a COOKIE ACK chunk after building a TCB
      * and moving to the ESTABLISHED state.
      */
     new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error,
                       &err_chk_p);
 
     /* FIXME:
      * If the re-build failed, what is the proper error path
      * from here?
      *
      * [We should abort the association. --piggy]
      */
     if (!new_asoc) {
         /* FIXME: Several errors are possible.  A bad cookie should
          * be silently discarded, but think about logging it too.
          */
         switch (error) {
         case -SCTP_IERROR_NOMEM:
             goto nomem;
 
         case -SCTP_IERROR_STALE_COOKIE:
             sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands,
                            err_chk_p);
             return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
         case -SCTP_IERROR_BAD_SIG:
         default:
             return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
         }
     }
 
     if (security_sctp_assoc_request(new_asoc, chunk->head_skb ?: chunk->skb)) {
         sctp_association_free(new_asoc);
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     /* Delay state machine commands until later.
      *
      * Re-build the bind address for the association is done in
      * the sctp_unpack_cookie() already.
      */
     /* This is a brand-new association, so these are not yet side
      * effects--it is safe to run them here.
      */
     peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
 
     if (!sctp_process_init(new_asoc, chunk,
                    &chunk->subh.cookie_hdr->c.peer_addr,
                    peer_init, GFP_ATOMIC))
         goto nomem_init;
 
     /* SCTP-AUTH:  Now that we've populate required fields in
      * sctp_process_init, set up the association shared keys as
      * necessary so that we can potentially authenticate the ACK
      */
     error = sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC);
     if (error)
         goto nomem_init;
 
     if (!sctp_auth_chunk_verify(net, chunk, new_asoc)) {
         sctp_association_free(new_asoc);
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     repl = sctp_make_cookie_ack(new_asoc, chunk);
     if (!repl)
         goto nomem_init;
 
     /* RFC 2960 5.1 Normal Establishment of an Association
      *
      * D) IMPLEMENTATION NOTE: An implementation may choose to
      * send the Communication Up notification to the SCTP user
      * upon reception of a valid COOKIE ECHO chunk.
      */
     ev = sctp_ulpevent_make_assoc_change(new_asoc, 0, SCTP_COMM_UP, 0,
                          new_asoc->c.sinit_num_ostreams,
                          new_asoc->c.sinit_max_instreams,
                          NULL, GFP_ATOMIC);
     if (!ev)
         goto nomem_ev;
 
     /* Sockets API Draft Section 5.3.1.6
      * When a peer sends a Adaptation Layer Indication parameter , SCTP
      * delivers this notification to inform the application that of the
      * peers requested adaptation layer.
      */
     if (new_asoc->peer.adaptation_ind) {
         ai_ev = sctp_ulpevent_make_adaptation_indication(new_asoc,
                                 GFP_ATOMIC);
         if (!ai_ev)
             goto nomem_aiev;
     }
 
     if (!new_asoc->peer.auth_capable) {
         auth_ev = sctp_ulpevent_make_authkey(new_asoc, 0,
                              SCTP_AUTH_NO_AUTH,
                              GFP_ATOMIC);
         if (!auth_ev)
             goto nomem_authev;
     }
 
     /* Add all the state machine commands now since we've created
      * everything.  This way we don't introduce memory corruptions
      * during side-effect processing and correctly count established
      * associations.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_ESTABLISHED));
     SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
     SCTP_INC_STATS(net, SCTP_MIB_PASSIVEESTABS);
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
 
     if (new_asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
 
     /* This will send the COOKIE ACK */
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
 
     /* Queue the ASSOC_CHANGE event */
     sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
 
     /* Send up the Adaptation Layer Indication event */
     if (ai_ev)
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(ai_ev));
 
     if (auth_ev)
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(auth_ev));
 
     return SCTP_DISPOSITION_CONSUME;
 
 nomem_authev:
     sctp_ulpevent_free(ai_ev);
 nomem_aiev:
     sctp_ulpevent_free(ev);
 nomem_ev:
     sctp_chunk_free(repl);
 nomem_init:
     sctp_association_free(new_asoc);
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Respond to a normal COOKIE ACK chunk.
  * We are the side that is asking for an association.
  *
  * RFC 2960 5.1 Normal Establishment of an Association
  *
  * E) Upon reception of the COOKIE ACK, endpoint "A" will move from the
  *    COOKIE-ECHOED state to the ESTABLISHED state, stopping the T1-cookie
  *    timer. It may also notify its ULP about the successful
  *    establishment of the association with a Communication Up
  *    notification (see Section 10).
  *
  * Verification Tag:
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_1E_ca(struct net *net,
                      const struct sctp_endpoint *ep,
                      const struct sctp_association *asoc,
                      const union sctp_subtype type,
                      void *arg,
                      struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_ulpevent *ev;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Set peer label for connection. */
     if (security_sctp_assoc_established((struct sctp_association *)asoc,
                         chunk->head_skb ?: chunk->skb))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Verify that the chunk length for the COOKIE-ACK is OK.
      * If we don't do this, any bundled chunks may be junked.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* Reset init error count upon receipt of COOKIE-ACK,
      * to avoid problems with the management of this
      * counter in stale cookie situations when a transition back
      * from the COOKIE-ECHOED state to the COOKIE-WAIT
      * state is performed.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
 
     /* RFC 2960 5.1 Normal Establishment of an Association
      *
      * E) Upon reception of the COOKIE ACK, endpoint "A" will move
      * from the COOKIE-ECHOED state to the ESTABLISHED state,
      * stopping the T1-cookie timer.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_ESTABLISHED));
     SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
     SCTP_INC_STATS(net, SCTP_MIB_ACTIVEESTABS);
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
     if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
 
     /* It may also notify its ULP about the successful
      * establishment of the association with a Communication Up
      * notification (see Section 10).
      */
     ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP,
                          0, asoc->c.sinit_num_ostreams,
                          asoc->c.sinit_max_instreams,
                          NULL, GFP_ATOMIC);
 
     if (!ev)
         goto nomem;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
 
     /* Sockets API Draft Section 5.3.1.6
      * When a peer sends a Adaptation Layer Indication parameter , SCTP
      * delivers this notification to inform the application that of the
      * peers requested adaptation layer.
      */
     if (asoc->peer.adaptation_ind) {
         ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
         if (!ev)
             goto nomem;
 
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(ev));
     }
 
     if (!asoc->peer.auth_capable) {
         ev = sctp_ulpevent_make_authkey(asoc, 0, SCTP_AUTH_NO_AUTH,
                         GFP_ATOMIC);
         if (!ev)
             goto nomem;
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(ev));
     }
 
     return SCTP_DISPOSITION_CONSUME;
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /* Generate and sendout a heartbeat packet.  */
 static enum sctp_disposition sctp_sf_heartbeat(
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_transport *transport = (struct sctp_transport *) arg;
     struct sctp_chunk *reply;
 
     /* Send a heartbeat to our peer.  */
     reply = sctp_make_heartbeat(asoc, transport, 0);
     if (!reply)
         return SCTP_DISPOSITION_NOMEM;
 
     /* Set rto_pending indicating that an RTT measurement
      * is started with this heartbeat chunk.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_RTO_PENDING,
             SCTP_TRANSPORT(transport));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* Generate a HEARTBEAT packet on the given transport.  */
 enum sctp_disposition sctp_sf_sendbeat_8_3(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_transport *transport = (struct sctp_transport *) arg;
 
     if (asoc->overall_error_count >= asoc->max_retrans) {
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_DISPOSITION_DELETE_TCB;
     }
 
     /* Section 3.3.5.
      * The Sender-specific Heartbeat Info field should normally include
      * information about the sender's current time when this HEARTBEAT
      * chunk is sent and the destination transport address to which this
      * HEARTBEAT is sent (see Section 8.3).
      */
 
     if (transport->param_flags & SPP_HB_ENABLE) {
         if (SCTP_DISPOSITION_NOMEM ==
                 sctp_sf_heartbeat(ep, asoc, type, arg,
                           commands))
             return SCTP_DISPOSITION_NOMEM;
 
         /* Set transport error counter and association error counter
          * when sending heartbeat.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT,
                 SCTP_TRANSPORT(transport));
     }
     sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_IDLE,
             SCTP_TRANSPORT(transport));
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMER_UPDATE,
             SCTP_TRANSPORT(transport));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* resend asoc strreset_chunk.  */
 enum sctp_disposition sctp_sf_send_reconf(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg,
                       struct sctp_cmd_seq *commands)
 {
     struct sctp_transport *transport = arg;
 
     if (asoc->overall_error_count >= asoc->max_retrans) {
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_DISPOSITION_DELETE_TCB;
     }
 
     sctp_chunk_hold(asoc->strreset_chunk);
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
             SCTP_CHUNK(asoc->strreset_chunk));
     sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* send hb chunk with padding for PLPMUTD.  */
 enum sctp_disposition sctp_sf_send_probe(struct net *net,
                      const struct sctp_endpoint *ep,
                      const struct sctp_association *asoc,
                      const union sctp_subtype type,
                      void *arg,
                      struct sctp_cmd_seq *commands)
 {
     struct sctp_transport *transport = (struct sctp_transport *)arg;
     struct sctp_chunk *reply;
 
     if (!sctp_transport_pl_enabled(transport))
         return SCTP_DISPOSITION_CONSUME;
 
     sctp_transport_pl_send(transport);
     reply = sctp_make_heartbeat(asoc, transport, transport->pl.probe_size);
     if (!reply)
         return SCTP_DISPOSITION_NOMEM;
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
     sctp_add_cmd_sf(commands, SCTP_CMD_PROBE_TIMER_UPDATE,
             SCTP_TRANSPORT(transport));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Process an heartbeat request.
  *
  * Section: 8.3 Path Heartbeat
  * The receiver of the HEARTBEAT should immediately respond with a
  * HEARTBEAT ACK that contains the Heartbeat Information field copied
  * from the received HEARTBEAT chunk.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  * When receiving an SCTP packet, the endpoint MUST ensure that the
  * value in the Verification Tag field of the received SCTP packet
  * matches its own Tag. If the received Verification Tag value does not
  * match the receiver's own tag value, the receiver shall silently
  * discard the packet and shall not process it any further except for
  * those cases listed in Section 8.5.1 below.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_beat_8_3(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg, struct sctp_cmd_seq *commands)
 {
     struct sctp_paramhdr *param_hdr;
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *reply;
     size_t paylen = 0;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the HEARTBEAT chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk,
                      sizeof(struct sctp_heartbeat_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* 8.3 The receiver of the HEARTBEAT should immediately
      * respond with a HEARTBEAT ACK that contains the Heartbeat
      * Information field copied from the received HEARTBEAT chunk.
      */
     chunk->subh.hb_hdr = (struct sctp_heartbeathdr *)chunk->skb->data;
     param_hdr = (struct sctp_paramhdr *)chunk->subh.hb_hdr;
     paylen = ntohs(chunk->chunk_hdr->length) - sizeof(struct sctp_chunkhdr);
 
     if (ntohs(param_hdr->length) > paylen)
         return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
                           param_hdr, commands);
 
     if (!pskb_pull(chunk->skb, paylen))
         goto nomem;
 
     reply = sctp_make_heartbeat_ack(asoc, chunk, param_hdr, paylen);
     if (!reply)
         goto nomem;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Process the returning HEARTBEAT ACK.
  *
  * Section: 8.3 Path Heartbeat
  * Upon the receipt of the HEARTBEAT ACK, the sender of the HEARTBEAT
  * should clear the error counter of the destination transport
  * address to which the HEARTBEAT was sent, and mark the destination
  * transport address as active if it is not so marked. The endpoint may
  * optionally report to the upper layer when an inactive destination
  * address is marked as active due to the reception of the latest
  * HEARTBEAT ACK. The receiver of the HEARTBEAT ACK must also
  * clear the association overall error count as well (as defined
  * in section 8.1).
  *
  * The receiver of the HEARTBEAT ACK should also perform an RTT
  * measurement for that destination transport address using the time
  * value carried in the HEARTBEAT ACK chunk.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_backbeat_8_3(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_sender_hb_info *hbinfo;
     struct sctp_chunk *chunk = arg;
     struct sctp_transport *link;
     unsigned long max_interval;
     union sctp_addr from_addr;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the HEARTBEAT-ACK chunk has a valid length.  */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr) +
                         sizeof(*hbinfo)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     hbinfo = (struct sctp_sender_hb_info *)chunk->skb->data;
     /* Make sure that the length of the parameter is what we expect */
     if (ntohs(hbinfo->param_hdr.length) != sizeof(*hbinfo))
         return SCTP_DISPOSITION_DISCARD;
 
     from_addr = hbinfo->daddr;
     link = sctp_assoc_lookup_paddr(asoc, &from_addr);
 
     /* This should never happen, but lets log it if so.  */
     if (unlikely(!link)) {
         if (from_addr.sa.sa_family == AF_INET6) {
             net_warn_ratelimited("%s association %p could not find address %pI6\n",
                          __func__,
                          asoc,
                          &from_addr.v6.sin6_addr);
         } else {
             net_warn_ratelimited("%s association %p could not find address %pI4\n",
                          __func__,
                          asoc,
                          &from_addr.v4.sin_addr.s_addr);
         }
         return SCTP_DISPOSITION_DISCARD;
     }
 
     /* Validate the 64-bit random nonce. */
     if (hbinfo->hb_nonce != link->hb_nonce)
         return SCTP_DISPOSITION_DISCARD;
 
     if (hbinfo->probe_size) {
         if (hbinfo->probe_size != link->pl.probe_size ||
             !sctp_transport_pl_enabled(link))
             return SCTP_DISPOSITION_DISCARD;
 
         if (sctp_transport_pl_recv(link))
             return SCTP_DISPOSITION_CONSUME;
 
         return sctp_sf_send_probe(net, ep, asoc, type, link, commands);
     }
 
     max_interval = link->hbinterval + link->rto;
 
     /* Check if the timestamp looks valid.  */
     if (time_after(hbinfo->sent_at, jiffies) ||
         time_after(jiffies, hbinfo->sent_at + max_interval)) {
         pr_debug("%s: HEARTBEAT ACK with invalid timestamp received "
              "for transport:%p\n", __func__, link);
 
         return SCTP_DISPOSITION_DISCARD;
     }
 
     /* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of
      * the HEARTBEAT should clear the error counter of the
      * destination transport address to which the HEARTBEAT was
      * sent and mark the destination transport address as active if
      * it is not so marked.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_ON, SCTP_TRANSPORT(link));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* Helper function to send out an abort for the restart
  * condition.
  */
 static int sctp_sf_send_restart_abort(struct net *net, union sctp_addr *ssa,
                       struct sctp_chunk *init,
                       struct sctp_cmd_seq *commands)
 {
     struct sctp_af *af = sctp_get_af_specific(ssa->v4.sin_family);
     union sctp_addr_param *addrparm;
     struct sctp_errhdr *errhdr;
     char buffer[sizeof(*errhdr) + sizeof(*addrparm)];
     struct sctp_endpoint *ep;
     struct sctp_packet *pkt;
     int len;
 
     /* Build the error on the stack.   We are way to malloc crazy
      * throughout the code today.
      */
     errhdr = (struct sctp_errhdr *)buffer;
     addrparm = (union sctp_addr_param *)errhdr->variable;
 
     /* Copy into a parm format. */
     len = af->to_addr_param(ssa, addrparm);
     len += sizeof(*errhdr);
 
     errhdr->cause = SCTP_ERROR_RESTART;
     errhdr->length = htons(len);
 
     /* Assign to the control socket. */
     ep = sctp_sk(net->sctp.ctl_sock)->ep;
 
     /* Association is NULL since this may be a restart attack and we
      * want to send back the attacker's vtag.
      */
     pkt = sctp_abort_pkt_new(net, ep, NULL, init, errhdr, len);
 
     if (!pkt)
         goto out;
     sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(pkt));
 
     SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 
     /* Discard the rest of the inbound packet. */
     sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
 
 out:
     /* Even if there is no memory, treat as a failure so
      * the packet will get dropped.
      */
     return 0;
 }
 
 static bool list_has_sctp_addr(const struct list_head *list,
                    union sctp_addr *ipaddr)
 {
     struct sctp_transport *addr;
 
     list_for_each_entry(addr, list, transports) {
         if (sctp_cmp_addr_exact(ipaddr, &addr->ipaddr))
             return true;
     }
 
     return false;
 }
 /* A restart is occurring, check to make sure no new addresses
  * are being added as we may be under a takeover attack.
  */
 static int sctp_sf_check_restart_addrs(const struct sctp_association *new_asoc,
                        const struct sctp_association *asoc,
                        struct sctp_chunk *init,
                        struct sctp_cmd_seq *commands)
 {
     struct net *net = new_asoc->base.net;
     struct sctp_transport *new_addr;
     int ret = 1;
 
     /* Implementor's Guide - Section 5.2.2
      * ...
      * Before responding the endpoint MUST check to see if the
      * unexpected INIT adds new addresses to the association. If new
      * addresses are added to the association, the endpoint MUST respond
      * with an ABORT..
      */
 
     /* Search through all current addresses and make sure
      * we aren't adding any new ones.
      */
     list_for_each_entry(new_addr, &new_asoc->peer.transport_addr_list,
                 transports) {
         if (!list_has_sctp_addr(&asoc->peer.transport_addr_list,
                     &new_addr->ipaddr)) {
             sctp_sf_send_restart_abort(net, &new_addr->ipaddr, init,
                            commands);
             ret = 0;
             break;
         }
     }
 
     /* Return success if all addresses were found. */
     return ret;
 }
 
 /* Populate the verification/tie tags based on overlapping INIT
  * scenario.
  *
  * Note: Do not use in CLOSED or SHUTDOWN-ACK-SENT state.
  */
 static void sctp_tietags_populate(struct sctp_association *new_asoc,
                   const struct sctp_association *asoc)
 {
     switch (asoc->state) {
 
     /* 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State */
 
     case SCTP_STATE_COOKIE_WAIT:
         new_asoc->c.my_vtag     = asoc->c.my_vtag;
         new_asoc->c.my_ttag     = asoc->c.my_vtag;
         new_asoc->c.peer_ttag   = 0;
         break;
 
     case SCTP_STATE_COOKIE_ECHOED:
         new_asoc->c.my_vtag     = asoc->c.my_vtag;
         new_asoc->c.my_ttag     = asoc->c.my_vtag;
         new_asoc->c.peer_ttag   = asoc->c.peer_vtag;
         break;
 
     /* 5.2.2 Unexpected INIT in States Other than CLOSED, COOKIE-ECHOED,
      * COOKIE-WAIT and SHUTDOWN-ACK-SENT
      */
     default:
         new_asoc->c.my_ttag   = asoc->c.my_vtag;
         new_asoc->c.peer_ttag = asoc->c.peer_vtag;
         break;
     }
 
     /* Other parameters for the endpoint SHOULD be copied from the
      * existing parameters of the association (e.g. number of
      * outbound streams) into the INIT ACK and cookie.
      */
     new_asoc->rwnd                  = asoc->rwnd;
     new_asoc->c.sinit_num_ostreams  = asoc->c.sinit_num_ostreams;
     new_asoc->c.sinit_max_instreams = asoc->c.sinit_max_instreams;
     new_asoc->c.initial_tsn         = asoc->c.initial_tsn;
 }
 
 /*
  * Compare vtag/tietag values to determine unexpected COOKIE-ECHO
  * handling action.
  *
  * RFC 2960 5.2.4 Handle a COOKIE ECHO when a TCB exists.
  *
  * Returns value representing action to be taken.   These action values
  * correspond to Action/Description values in RFC 2960, Table 2.
  */
 static char sctp_tietags_compare(struct sctp_association *new_asoc,
                  const struct sctp_association *asoc)
 {
     /* In this case, the peer may have restarted.  */
     if ((asoc->c.my_vtag != new_asoc->c.my_vtag) &&
         (asoc->c.peer_vtag != new_asoc->c.peer_vtag) &&
         (asoc->c.my_vtag == new_asoc->c.my_ttag) &&
         (asoc->c.peer_vtag == new_asoc->c.peer_ttag))
         return 'A';
 
     /* Collision case B. */
     if ((asoc->c.my_vtag == new_asoc->c.my_vtag) &&
         ((asoc->c.peer_vtag != new_asoc->c.peer_vtag) ||
          (0 == asoc->c.peer_vtag))) {
         return 'B';
     }
 
     /* Collision case D. */
     if ((asoc->c.my_vtag == new_asoc->c.my_vtag) &&
         (asoc->c.peer_vtag == new_asoc->c.peer_vtag))
         return 'D';
 
     /* Collision case C. */
     if ((asoc->c.my_vtag != new_asoc->c.my_vtag) &&
         (asoc->c.peer_vtag == new_asoc->c.peer_vtag) &&
         (0 == new_asoc->c.my_ttag) &&
         (0 == new_asoc->c.peer_ttag))
         return 'C';
 
     /* No match to any of the special cases; discard this packet. */
     return 'E';
 }
 
 /* Common helper routine for both duplicate and simultaneous INIT
  * chunk handling.
  */
 static enum sctp_disposition sctp_sf_do_unexpected_init(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg, *repl, *err_chunk;
     struct sctp_unrecognized_param *unk_param;
     struct sctp_association *new_asoc;
     enum sctp_disposition retval;
     struct sctp_packet *packet;
     int len;
 
     /* 6.10 Bundling
      * An endpoint MUST NOT bundle INIT, INIT ACK or
      * SHUTDOWN COMPLETE with any other chunks.
      *
      * IG Section 2.11.2
      * Furthermore, we require that the receiver of an INIT chunk MUST
      * enforce these rules by silently discarding an arriving packet
      * with an INIT chunk that is bundled with other chunks.
      */
     if (!chunk->singleton)
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the INIT chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_init_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* 3.1 A packet containing an INIT chunk MUST have a zero Verification
      * Tag.
      */
     if (chunk->sctp_hdr->vtag != 0)
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
 
     if (SCTP_INPUT_CB(chunk->skb)->encap_port != chunk->transport->encap_port)
         return sctp_sf_new_encap_port(net, ep, asoc, type, arg, commands);
 
     /* Grab the INIT header.  */
     chunk->subh.init_hdr = (struct sctp_inithdr *)chunk->skb->data;
 
     /* Tag the variable length parameters.  */
     chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr));
 
     /* Verify the INIT chunk before processing it. */
     err_chunk = NULL;
     if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
                   (struct sctp_init_chunk *)chunk->chunk_hdr, chunk,
                   &err_chunk)) {
         /* This chunk contains fatal error. It is to be discarded.
          * Send an ABORT, with causes if there is any.
          */
         if (err_chunk) {
             packet = sctp_abort_pkt_new(net, ep, asoc, arg,
                     (__u8 *)(err_chunk->chunk_hdr) +
                     sizeof(struct sctp_chunkhdr),
                     ntohs(err_chunk->chunk_hdr->length) -
                     sizeof(struct sctp_chunkhdr));
 
             if (packet) {
                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
                         SCTP_PACKET(packet));
                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
                 retval = SCTP_DISPOSITION_CONSUME;
             } else {
                 retval = SCTP_DISPOSITION_NOMEM;
             }
             goto cleanup;
         } else {
             return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
                             commands);
         }
     }
 
     /*
      * Other parameters for the endpoint SHOULD be copied from the
      * existing parameters of the association (e.g. number of
      * outbound streams) into the INIT ACK and cookie.
      * FIXME:  We are copying parameters from the endpoint not the
      * association.
      */
     new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
     if (!new_asoc)
         goto nomem;
 
     /* Update socket peer label if first association. */
     if (security_sctp_assoc_request(new_asoc, chunk->skb)) {
         sctp_association_free(new_asoc);
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
                 sctp_scope(sctp_source(chunk)), GFP_ATOMIC) < 0)
         goto nomem;
 
     /* In the outbound INIT ACK the endpoint MUST copy its current
      * Verification Tag and Peers Verification tag into a reserved
      * place (local tie-tag and per tie-tag) within the state cookie.
      */
     if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
                    (struct sctp_init_chunk *)chunk->chunk_hdr,
                    GFP_ATOMIC))
         goto nomem;
 
     /* Make sure no new addresses are being added during the
      * restart.   Do not do this check for COOKIE-WAIT state,
      * since there are no peer addresses to check against.
      * Upon return an ABORT will have been sent if needed.
      */
     if (!sctp_state(asoc, COOKIE_WAIT)) {
         if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk,
                          commands)) {
             retval = SCTP_DISPOSITION_CONSUME;
             goto nomem_retval;
         }
     }
 
     sctp_tietags_populate(new_asoc, asoc);
 
     /* B) "Z" shall respond immediately with an INIT ACK chunk.  */
 
     /* If there are errors need to be reported for unknown parameters,
      * make sure to reserve enough room in the INIT ACK for them.
      */
     len = 0;
     if (err_chunk) {
         len = ntohs(err_chunk->chunk_hdr->length) -
               sizeof(struct sctp_chunkhdr);
     }
 
     repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
     if (!repl)
         goto nomem;
 
     /* If there are errors need to be reported for unknown parameters,
      * include them in the outgoing INIT ACK as "Unrecognized parameter"
      * parameter.
      */
     if (err_chunk) {
         /* Get the "Unrecognized parameter" parameter(s) out of the
          * ERROR chunk generated by sctp_verify_init(). Since the
          * error cause code for "unknown parameter" and the
          * "Unrecognized parameter" type is the same, we can
          * construct the parameters in INIT ACK by copying the
          * ERROR causes over.
          */
         unk_param = (struct sctp_unrecognized_param *)
                 ((__u8 *)(err_chunk->chunk_hdr) +
                 sizeof(struct sctp_chunkhdr));
         /* Replace the cause code with the "Unrecognized parameter"
          * parameter type.
          */
         sctp_addto_chunk(repl, len, unk_param);
     }
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
 
     /*
      * Note: After sending out INIT ACK with the State Cookie parameter,
      * "Z" MUST NOT allocate any resources for this new association.
      * Otherwise, "Z" will be vulnerable to resource attacks.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
     retval = SCTP_DISPOSITION_CONSUME;
 
     return retval;
 
 nomem:
     retval = SCTP_DISPOSITION_NOMEM;
 nomem_retval:
     if (new_asoc)
         sctp_association_free(new_asoc);
 cleanup:
     if (err_chunk)
         sctp_chunk_free(err_chunk);
     return retval;
 }
 
 /*
  * Handle simultaneous INIT.
  * This means we started an INIT and then we got an INIT request from
  * our peer.
  *
  * Section: 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State (Item B)
  * This usually indicates an initialization collision, i.e., each
  * endpoint is attempting, at about the same time, to establish an
  * association with the other endpoint.
  *
  * Upon receipt of an INIT in the COOKIE-WAIT or COOKIE-ECHOED state, an
  * endpoint MUST respond with an INIT ACK using the same parameters it
  * sent in its original INIT chunk (including its Verification Tag,
  * unchanged). These original parameters are combined with those from the
  * newly received INIT chunk. The endpoint shall also generate a State
  * Cookie with the INIT ACK. The endpoint uses the parameters sent in its
  * INIT to calculate the State Cookie.
  *
  * After that, the endpoint MUST NOT change its state, the T1-init
  * timer shall be left running and the corresponding TCB MUST NOT be
  * destroyed. The normal procedures for handling State Cookies when
  * a TCB exists will resolve the duplicate INITs to a single association.
  *
  * For an endpoint that is in the COOKIE-ECHOED state it MUST populate
  * its Tie-Tags with the Tag information of itself and its peer (see
  * section 5.2.2 for a description of the Tie-Tags).
  *
  * Verification Tag: Not explicit, but an INIT can not have a valid
  * verification tag, so we skip the check.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_2_1_siminit(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* Call helper to do the real work for both simultaneous and
      * duplicate INIT chunk handling.
      */
     return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Handle duplicated INIT messages.  These are usually delayed
  * restransmissions.
  *
  * Section: 5.2.2 Unexpected INIT in States Other than CLOSED,
  * COOKIE-ECHOED and COOKIE-WAIT
  *
  * Unless otherwise stated, upon reception of an unexpected INIT for
  * this association, the endpoint shall generate an INIT ACK with a
  * State Cookie.  In the outbound INIT ACK the endpoint MUST copy its
  * current Verification Tag and peer's Verification Tag into a reserved
  * place within the state cookie.  We shall refer to these locations as
  * the Peer's-Tie-Tag and the Local-Tie-Tag.  The outbound SCTP packet
  * containing this INIT ACK MUST carry a Verification Tag value equal to
  * the Initiation Tag found in the unexpected INIT.  And the INIT ACK
  * MUST contain a new Initiation Tag (randomly generated see Section
  * 5.3.1).  Other parameters for the endpoint SHOULD be copied from the
  * existing parameters of the association (e.g. number of outbound
  * streams) into the INIT ACK and cookie.
  *
  * After sending out the INIT ACK, the endpoint shall take no further
  * actions, i.e., the existing association, including its current state,
  * and the corresponding TCB MUST NOT be changed.
  *
  * Note: Only when a TCB exists and the association is not in a COOKIE-
  * WAIT state are the Tie-Tags populated.  For a normal association INIT
  * (i.e. the endpoint is in a COOKIE-WAIT state), the Tie-Tags MUST be
  * set to 0 (indicating that no previous TCB existed).  The INIT ACK and
  * State Cookie are populated as specified in section 5.2.1.
  *
  * Verification Tag: Not specified, but an INIT has no way of knowing
  * what the verification tag could be, so we ignore it.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_2_2_dupinit(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* Call helper to do the real work for both simultaneous and
      * duplicate INIT chunk handling.
      */
     return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands);
 }
 
 
 /*
  * Unexpected INIT-ACK handler.
  *
  * Section 5.2.3
  * If an INIT ACK received by an endpoint in any state other than the
  * COOKIE-WAIT state, the endpoint should discard the INIT ACK chunk.
  * An unexpected INIT ACK usually indicates the processing of an old or
  * duplicated INIT chunk.
 */
 enum sctp_disposition sctp_sf_do_5_2_3_initack(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* Per the above section, we'll discard the chunk if we have an
      * endpoint.  If this is an OOTB INIT-ACK, treat it as such.
      */
     if (ep == sctp_sk(net->sctp.ctl_sock)->ep)
         return sctp_sf_ootb(net, ep, asoc, type, arg, commands);
     else
         return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
 }
 
 static int sctp_sf_do_assoc_update(struct sctp_association *asoc,
                    struct sctp_association *new,
                    struct sctp_cmd_seq *cmds)
 {
     struct net *net = asoc->base.net;
     struct sctp_chunk *abort;
 
     if (!sctp_assoc_update(asoc, new))
         return 0;
 
     abort = sctp_make_abort(asoc, NULL, sizeof(struct sctp_errhdr));
     if (abort) {
         sctp_init_cause(abort, SCTP_ERROR_RSRC_LOW, 0);
         sctp_add_cmd_sf(cmds, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
     }
     sctp_add_cmd_sf(cmds, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED));
     sctp_add_cmd_sf(cmds, SCTP_CMD_ASSOC_FAILED,
             SCTP_PERR(SCTP_ERROR_RSRC_LOW));
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
 
     return -ENOMEM;
 }
 
 /* Unexpected COOKIE-ECHO handler for peer restart (Table 2, action 'A')
  *
  * Section 5.2.4
  *  A)  In this case, the peer may have restarted.
  */
 static enum sctp_disposition sctp_sf_do_dupcook_a(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     struct sctp_cmd_seq *commands,
                     struct sctp_association *new_asoc)
 {
     struct sctp_init_chunk *peer_init;
     enum sctp_disposition disposition;
     struct sctp_ulpevent *ev;
     struct sctp_chunk *repl;
     struct sctp_chunk *err;
 
     /* new_asoc is a brand-new association, so these are not yet
      * side effects--it is safe to run them here.
      */
     peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
 
     if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
                    GFP_ATOMIC))
         goto nomem;
 
     if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
         goto nomem;
 
     if (!sctp_auth_chunk_verify(net, chunk, new_asoc))
         return SCTP_DISPOSITION_DISCARD;
 
     /* Make sure no new addresses are being added during the
      * restart.  Though this is a pretty complicated attack
      * since you'd have to get inside the cookie.
      */
     if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk, commands))
         return SCTP_DISPOSITION_CONSUME;
 
     /* If the endpoint is in the SHUTDOWN-ACK-SENT state and recognizes
      * the peer has restarted (Action A), it MUST NOT setup a new
      * association but instead resend the SHUTDOWN ACK and send an ERROR
      * chunk with a "Cookie Received while Shutting Down" error cause to
      * its peer.
     */
     if (sctp_state(asoc, SHUTDOWN_ACK_SENT)) {
         disposition = __sctp_sf_do_9_2_reshutack(net, ep, asoc,
                              SCTP_ST_CHUNK(chunk->chunk_hdr->type),
                              chunk, commands);
         if (SCTP_DISPOSITION_NOMEM == disposition)
             goto nomem;
 
         err = sctp_make_op_error(asoc, chunk,
                      SCTP_ERROR_COOKIE_IN_SHUTDOWN,
                      NULL, 0, 0);
         if (err)
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(err));
 
         return SCTP_DISPOSITION_CONSUME;
     }
 
     /* For now, stop pending T3-rtx and SACK timers, fail any unsent/unacked
      * data. Consider the optional choice of resending of this data.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL());
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
     sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_OUTQUEUE, SCTP_NULL());
 
     /* Stop pending T4-rto timer, teardown ASCONF queue, ASCONF-ACK queue
      * and ASCONF-ACK cache.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
     sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_ASCONF_QUEUE, SCTP_NULL());
 
     /* Update the content of current association. */
     if (sctp_sf_do_assoc_update((struct sctp_association *)asoc, new_asoc, commands))
         goto nomem;
 
     repl = sctp_make_cookie_ack(asoc, chunk);
     if (!repl)
         goto nomem;
 
     /* Report association restart to upper layer. */
     ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_RESTART, 0,
                          asoc->c.sinit_num_ostreams,
                          asoc->c.sinit_max_instreams,
                          NULL, GFP_ATOMIC);
     if (!ev)
         goto nomem_ev;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
     if ((sctp_state(asoc, SHUTDOWN_PENDING) ||
          sctp_state(asoc, SHUTDOWN_SENT)) &&
         (sctp_sstate(asoc->base.sk, CLOSING) ||
          sock_flag(asoc->base.sk, SOCK_DEAD))) {
         /* If the socket has been closed by user, don't
          * transition to ESTABLISHED. Instead trigger SHUTDOWN
          * bundled with COOKIE_ACK.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
         return sctp_sf_do_9_2_start_shutdown(net, ep, asoc,
                              SCTP_ST_CHUNK(0), repl,
                              commands);
     } else {
         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
                 SCTP_STATE(SCTP_STATE_ESTABLISHED));
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
     }
     return SCTP_DISPOSITION_CONSUME;
 
 nomem_ev:
     sctp_chunk_free(repl);
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'B')
  *
  * Section 5.2.4
  *   B) In this case, both sides may be attempting to start an association
  *      at about the same time but the peer endpoint started its INIT
  *      after responding to the local endpoint's INIT
  */
 /* This case represents an initialization collision.  */
 static enum sctp_disposition sctp_sf_do_dupcook_b(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     struct sctp_cmd_seq *commands,
                     struct sctp_association *new_asoc)
 {
     struct sctp_init_chunk *peer_init;
     struct sctp_chunk *repl;
 
     /* new_asoc is a brand-new association, so these are not yet
      * side effects--it is safe to run them here.
      */
     peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
     if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
                    GFP_ATOMIC))
         goto nomem;
 
     if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
         goto nomem;
 
     if (!sctp_auth_chunk_verify(net, chunk, new_asoc))
         return SCTP_DISPOSITION_DISCARD;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_ESTABLISHED));
     if (asoc->state < SCTP_STATE_ESTABLISHED)
         SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
 
     /* Update the content of current association.  */
     if (sctp_sf_do_assoc_update((struct sctp_association *)asoc, new_asoc, commands))
         goto nomem;
 
     repl = sctp_make_cookie_ack(asoc, chunk);
     if (!repl)
         goto nomem;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
 
     /* RFC 2960 5.1 Normal Establishment of an Association
      *
      * D) IMPLEMENTATION NOTE: An implementation may choose to
      * send the Communication Up notification to the SCTP user
      * upon reception of a valid COOKIE ECHO chunk.
      *
      * Sadly, this needs to be implemented as a side-effect, because
      * we are not guaranteed to have set the association id of the real
      * association and so these notifications need to be delayed until
      * the association id is allocated.
      */
 
     sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_CHANGE, SCTP_U8(SCTP_COMM_UP));
 
     /* Sockets API Draft Section 5.3.1.6
      * When a peer sends a Adaptation Layer Indication parameter , SCTP
      * delivers this notification to inform the application that of the
      * peers requested adaptation layer.
      *
      * This also needs to be done as a side effect for the same reason as
      * above.
      */
     if (asoc->peer.adaptation_ind)
         sctp_add_cmd_sf(commands, SCTP_CMD_ADAPTATION_IND, SCTP_NULL());
 
     if (!asoc->peer.auth_capable)
         sctp_add_cmd_sf(commands, SCTP_CMD_PEER_NO_AUTH, SCTP_NULL());
 
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'C')
  *
  * Section 5.2.4
  *  C) In this case, the local endpoint's cookie has arrived late.
  *     Before it arrived, the local endpoint sent an INIT and received an
  *     INIT-ACK and finally sent a COOKIE ECHO with the peer's same tag
  *     but a new tag of its own.
  */
 /* This case represents an initialization collision.  */
 static enum sctp_disposition sctp_sf_do_dupcook_c(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     struct sctp_cmd_seq *commands,
                     struct sctp_association *new_asoc)
 {
     /* The cookie should be silently discarded.
      * The endpoint SHOULD NOT change states and should leave
      * any timers running.
      */
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /* Unexpected COOKIE-ECHO handler lost chunk (Table 2, action 'D')
  *
  * Section 5.2.4
  *
  * D) When both local and remote tags match the endpoint should always
  *    enter the ESTABLISHED state, if it has not already done so.
  */
 /* This case represents an initialization collision.  */
 static enum sctp_disposition sctp_sf_do_dupcook_d(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     struct sctp_cmd_seq *commands,
                     struct sctp_association *new_asoc)
 {
     struct sctp_ulpevent *ev = NULL, *ai_ev = NULL, *auth_ev = NULL;
     struct sctp_chunk *repl;
 
     /* Clarification from Implementor's Guide:
      * D) When both local and remote tags match the endpoint should
      * enter the ESTABLISHED state, if it is in the COOKIE-ECHOED state.
      * It should stop any cookie timer that may be running and send
      * a COOKIE ACK.
      */
 
     if (!sctp_auth_chunk_verify(net, chunk, asoc))
         return SCTP_DISPOSITION_DISCARD;
 
     /* Don't accidentally move back into established state. */
     if (asoc->state < SCTP_STATE_ESTABLISHED) {
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
                 SCTP_STATE(SCTP_STATE_ESTABLISHED));
         SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START,
                 SCTP_NULL());
 
         /* RFC 2960 5.1 Normal Establishment of an Association
          *
          * D) IMPLEMENTATION NOTE: An implementation may choose
          * to send the Communication Up notification to the
          * SCTP user upon reception of a valid COOKIE
          * ECHO chunk.
          */
         ev = sctp_ulpevent_make_assoc_change(asoc, 0,
                          SCTP_COMM_UP, 0,
                          asoc->c.sinit_num_ostreams,
                          asoc->c.sinit_max_instreams,
                          NULL, GFP_ATOMIC);
         if (!ev)
             goto nomem;
 
         /* Sockets API Draft Section 5.3.1.6
          * When a peer sends a Adaptation Layer Indication parameter,
          * SCTP delivers this notification to inform the application
          * that of the peers requested adaptation layer.
          */
         if (asoc->peer.adaptation_ind) {
             ai_ev = sctp_ulpevent_make_adaptation_indication(asoc,
                                  GFP_ATOMIC);
             if (!ai_ev)
                 goto nomem;
 
         }
 
         if (!asoc->peer.auth_capable) {
             auth_ev = sctp_ulpevent_make_authkey(asoc, 0,
                                  SCTP_AUTH_NO_AUTH,
                                  GFP_ATOMIC);
             if (!auth_ev)
                 goto nomem;
         }
     }
 
     repl = sctp_make_cookie_ack(asoc, chunk);
     if (!repl)
         goto nomem;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
 
     if (ev)
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(ev));
     if (ai_ev)
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                     SCTP_ULPEVENT(ai_ev));
     if (auth_ev)
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(auth_ev));
 
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     if (auth_ev)
         sctp_ulpevent_free(auth_ev);
     if (ai_ev)
         sctp_ulpevent_free(ai_ev);
     if (ev)
         sctp_ulpevent_free(ev);
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Handle a duplicate COOKIE-ECHO.  This usually means a cookie-carrying
  * chunk was retransmitted and then delayed in the network.
  *
  * Section: 5.2.4 Handle a COOKIE ECHO when a TCB exists
  *
  * Verification Tag: None.  Do cookie validation.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_5_2_4_dupcook(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_association *new_asoc;
     struct sctp_chunk *chunk = arg;
     enum sctp_disposition retval;
     struct sctp_chunk *err_chk_p;
     int error = 0;
     char action;
 
     /* Make sure that the chunk has a valid length from the protocol
      * perspective.  In this case check to make sure we have at least
      * enough for the chunk header.  Cookie length verification is
      * done later.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) {
         if (!sctp_vtag_verify(chunk, asoc))
             asoc = NULL;
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands);
     }
 
     /* "Decode" the chunk.  We have no optional parameters so we
      * are in good shape.
      */
     chunk->subh.cookie_hdr = (struct sctp_signed_cookie *)chunk->skb->data;
     if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
                     sizeof(struct sctp_chunkhdr)))
         goto nomem;
 
     /* In RFC 2960 5.2.4 3, if both Verification Tags in the State Cookie
      * of a duplicate COOKIE ECHO match the Verification Tags of the
      * current association, consider the State Cookie valid even if
      * the lifespan is exceeded.
      */
     new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error,
                       &err_chk_p);
 
     /* FIXME:
      * If the re-build failed, what is the proper error path
      * from here?
      *
      * [We should abort the association. --piggy]
      */
     if (!new_asoc) {
         /* FIXME: Several errors are possible.  A bad cookie should
          * be silently discarded, but think about logging it too.
          */
         switch (error) {
         case -SCTP_IERROR_NOMEM:
             goto nomem;
 
         case -SCTP_IERROR_STALE_COOKIE:
             sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands,
                            err_chk_p);
             return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
         case -SCTP_IERROR_BAD_SIG:
         default:
             return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
         }
     }
 
     /* Update socket peer label if first association. */
     if (security_sctp_assoc_request(new_asoc, chunk->head_skb ?: chunk->skb)) {
         sctp_association_free(new_asoc);
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     /* Set temp so that it won't be added into hashtable */
     new_asoc->temp = 1;
 
     /* Compare the tie_tag in cookie with the verification tag of
      * current association.
      */
     action = sctp_tietags_compare(new_asoc, asoc);
 
     switch (action) {
     case 'A': /* Association restart. */
         retval = sctp_sf_do_dupcook_a(net, ep, asoc, chunk, commands,
                           new_asoc);
         break;
 
     case 'B': /* Collision case B. */
         retval = sctp_sf_do_dupcook_b(net, ep, asoc, chunk, commands,
                           new_asoc);
         break;
 
     case 'C': /* Collision case C. */
         retval = sctp_sf_do_dupcook_c(net, ep, asoc, chunk, commands,
                           new_asoc);
         break;
 
     case 'D': /* Collision case D. */
         retval = sctp_sf_do_dupcook_d(net, ep, asoc, chunk, commands,
                           new_asoc);
         break;
 
     default: /* Discard packet for all others. */
         retval = sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
         break;
     }
 
     /* Delete the temporary new association. */
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC, SCTP_ASOC(new_asoc));
     sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
 
     /* Restore association pointer to provide SCTP command interpreter
      * with a valid context in case it needs to manipulate
      * the queues */
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC,
              SCTP_ASOC((struct sctp_association *)asoc));
 
     return retval;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Process an ABORT.  (SHUTDOWN-PENDING state)
  *
  * See sctp_sf_do_9_1_abort().
  */
 enum sctp_disposition sctp_sf_shutdown_pending_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (!sctp_vtag_verify_either(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the ABORT chunk has a valid length.
      * Since this is an ABORT chunk, we have to discard it
      * because of the following text:
      * RFC 2960, Section 3.3.7
      *    If an endpoint receives an ABORT with a format error or for an
      *    association that doesn't exist, it MUST silently discard it.
      * Because the length is "invalid", we can't really discard just
      * as we do not know its true length.  So, to be safe, discard the
      * packet.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* ADD-IP: Special case for ABORT chunks
      * F4)  One special consideration is that ABORT Chunks arriving
      * destined to the IP address being deleted MUST be
      * ignored (see Section 5.3.1 for further details).
      */
     if (SCTP_ADDR_DEL ==
             sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (!sctp_err_chunk_valid(chunk))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Process an ABORT.  (SHUTDOWN-SENT state)
  *
  * See sctp_sf_do_9_1_abort().
  */
 enum sctp_disposition sctp_sf_shutdown_sent_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (!sctp_vtag_verify_either(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the ABORT chunk has a valid length.
      * Since this is an ABORT chunk, we have to discard it
      * because of the following text:
      * RFC 2960, Section 3.3.7
      *    If an endpoint receives an ABORT with a format error or for an
      *    association that doesn't exist, it MUST silently discard it.
      * Because the length is "invalid", we can't really discard just
      * as we do not know its true length.  So, to be safe, discard the
      * packet.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* ADD-IP: Special case for ABORT chunks
      * F4)  One special consideration is that ABORT Chunks arriving
      * destined to the IP address being deleted MUST be
      * ignored (see Section 5.3.1 for further details).
      */
     if (SCTP_ADDR_DEL ==
             sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (!sctp_err_chunk_valid(chunk))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Stop the T2-shutdown timer. */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     /* Stop the T5-shutdown guard timer.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
 
     return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Process an ABORT.  (SHUTDOWN-ACK-SENT state)
  *
  * See sctp_sf_do_9_1_abort().
  */
 enum sctp_disposition sctp_sf_shutdown_ack_sent_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* The same T2 timer, so we should be able to use
      * common function with the SHUTDOWN-SENT state.
      */
     return sctp_sf_shutdown_sent_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Handle an Error received in COOKIE_ECHOED state.
  *
  * Only handle the error type of stale COOKIE Error, the other errors will
  * be ignored.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_cookie_echoed_err(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_errhdr *err;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the ERROR chunk has a valid length.
      * The parameter walking depends on this as well.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_operr_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* Process the error here */
     /* FUTURE FIXME:  When PR-SCTP related and other optional
      * parms are emitted, this will have to change to handle multiple
      * errors.
      */
     sctp_walk_errors(err, chunk->chunk_hdr) {
         if (SCTP_ERROR_STALE_COOKIE == err->cause)
             return sctp_sf_do_5_2_6_stale(net, ep, asoc, type,
                             arg, commands);
     }
 
     /* It is possible to have malformed error causes, and that
      * will cause us to end the walk early.  However, since
      * we are discarding the packet, there should be no adverse
      * affects.
      */
     return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Handle a Stale COOKIE Error
  *
  * Section: 5.2.6 Handle Stale COOKIE Error
  * If the association is in the COOKIE-ECHOED state, the endpoint may elect
  * one of the following three alternatives.
  * ...
  * 3) Send a new INIT chunk to the endpoint, adding a Cookie
  *    Preservative parameter requesting an extension to the lifetime of
  *    the State Cookie. When calculating the time extension, an
  *    implementation SHOULD use the RTT information measured based on the
  *    previous COOKIE ECHO / ERROR exchange, and should add no more
  *    than 1 second beyond the measured RTT, due to long State Cookie
  *    lifetimes making the endpoint more subject to a replay attack.
  *
  * Verification Tag:  Not explicit, but safe to ignore.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 static enum sctp_disposition sctp_sf_do_5_2_6_stale(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     int attempts = asoc->init_err_counter + 1;
     struct sctp_chunk *chunk = arg, *reply;
     struct sctp_cookie_preserve_param bht;
     struct sctp_bind_addr *bp;
     struct sctp_errhdr *err;
     u32 stale;
 
     if (attempts > asoc->max_init_attempts) {
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
                 SCTP_PERR(SCTP_ERROR_STALE_COOKIE));
         return SCTP_DISPOSITION_DELETE_TCB;
     }
 
     err = (struct sctp_errhdr *)(chunk->skb->data);
 
     /* When calculating the time extension, an implementation
      * SHOULD use the RTT information measured based on the
      * previous COOKIE ECHO / ERROR exchange, and should add no
      * more than 1 second beyond the measured RTT, due to long
      * State Cookie lifetimes making the endpoint more subject to
      * a replay attack.
      * Measure of Staleness's unit is usec. (1/1000000 sec)
      * Suggested Cookie Life-span Increment's unit is msec.
      * (1/1000 sec)
      * In general, if you use the suggested cookie life, the value
      * found in the field of measure of staleness should be doubled
      * to give ample time to retransmit the new cookie and thus
      * yield a higher probability of success on the reattempt.
      */
     stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err)));
     stale = (stale * 2) / 1000;
 
     bht.param_hdr.type = SCTP_PARAM_COOKIE_PRESERVATIVE;
     bht.param_hdr.length = htons(sizeof(bht));
     bht.lifespan_increment = htonl(stale);
 
     /* Build that new INIT chunk.  */
     bp = (struct sctp_bind_addr *) &asoc->base.bind_addr;
     reply = sctp_make_init(asoc, bp, GFP_ATOMIC, sizeof(bht));
     if (!reply)
         goto nomem;
 
     sctp_addto_chunk(reply, sizeof(bht), &bht);
 
     /* Clear peer's init_tag cached in assoc as we are sending a new INIT */
     sctp_add_cmd_sf(commands, SCTP_CMD_CLEAR_INIT_TAG, SCTP_NULL());
 
     /* Stop pending T3-rtx and heartbeat timers */
     sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL());
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
 
     /* Delete non-primary peer ip addresses since we are transitioning
      * back to the COOKIE-WAIT state
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_DEL_NON_PRIMARY, SCTP_NULL());
 
     /* If we've sent any data bundled with COOKIE-ECHO we will need to
      * resend
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_T1_RETRAN,
             SCTP_TRANSPORT(asoc->peer.primary_path));
 
     /* Cast away the const modifier, as we want to just
      * rerun it through as a sideffect.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_INC, SCTP_NULL());
 
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_COOKIE_WAIT));
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
 
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Process an ABORT.
  *
  * Section: 9.1
  * After checking the Verification Tag, the receiving endpoint shall
  * remove the association from its record, and shall report the
  * termination to its upper layer.
  *
  * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules
  * B) Rules for packet carrying ABORT:
  *
  *  - The endpoint shall always fill in the Verification Tag field of the
  *    outbound packet with the destination endpoint's tag value if it
  *    is known.
  *
  *  - If the ABORT is sent in response to an OOTB packet, the endpoint
  *    MUST follow the procedure described in Section 8.4.
  *
  *  - The receiver MUST accept the packet if the Verification Tag
  *    matches either its own tag, OR the tag of its peer. Otherwise, the
  *    receiver MUST silently discard the packet and take no further
  *    action.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_9_1_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (!sctp_vtag_verify_either(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the ABORT chunk has a valid length.
      * Since this is an ABORT chunk, we have to discard it
      * because of the following text:
      * RFC 2960, Section 3.3.7
      *    If an endpoint receives an ABORT with a format error or for an
      *    association that doesn't exist, it MUST silently discard it.
      * Because the length is "invalid", we can't really discard just
      * as we do not know its true length.  So, to be safe, discard the
      * packet.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* ADD-IP: Special case for ABORT chunks
      * F4)  One special consideration is that ABORT Chunks arriving
      * destined to the IP address being deleted MUST be
      * ignored (see Section 5.3.1 for further details).
      */
     if (SCTP_ADDR_DEL ==
             sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (!sctp_err_chunk_valid(chunk))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
 }
 
 static enum sctp_disposition __sctp_sf_do_9_1_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     __be16 error = SCTP_ERROR_NO_ERROR;
     struct sctp_chunk *chunk = arg;
     unsigned int len;
 
     /* See if we have an error cause code in the chunk.  */
     len = ntohs(chunk->chunk_hdr->length);
     if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr))
         error = ((struct sctp_errhdr *)chunk->skb->data)->cause;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNRESET));
     /* ASSOC_FAILED will DELETE_TCB. */
     sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(error));
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
 
     return SCTP_DISPOSITION_ABORT;
 }
 
 /*
  * Process an ABORT.  (COOKIE-WAIT state)
  *
  * See sctp_sf_do_9_1_abort() above.
  */
 enum sctp_disposition sctp_sf_cookie_wait_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     __be16 error = SCTP_ERROR_NO_ERROR;
     struct sctp_chunk *chunk = arg;
     unsigned int len;
 
     if (!sctp_vtag_verify_either(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the ABORT chunk has a valid length.
      * Since this is an ABORT chunk, we have to discard it
      * because of the following text:
      * RFC 2960, Section 3.3.7
      *    If an endpoint receives an ABORT with a format error or for an
      *    association that doesn't exist, it MUST silently discard it.
      * Because the length is "invalid", we can't really discard just
      * as we do not know its true length.  So, to be safe, discard the
      * packet.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* See if we have an error cause code in the chunk.  */
     len = ntohs(chunk->chunk_hdr->length);
     if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr))
         error = ((struct sctp_errhdr *)chunk->skb->data)->cause;
 
     return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED, asoc,
                       chunk->transport);
 }
 
 /*
  * Process an incoming ICMP as an ABORT.  (COOKIE-WAIT state)
  */
 enum sctp_disposition sctp_sf_cookie_wait_icmp_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     return sctp_stop_t1_and_abort(net, commands, SCTP_ERROR_NO_ERROR,
                       ENOPROTOOPT, asoc,
                       (struct sctp_transport *)arg);
 }
 
 /*
  * Process an ABORT.  (COOKIE-ECHOED state)
  */
 enum sctp_disposition sctp_sf_cookie_echoed_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* There is a single T1 timer, so we should be able to use
      * common function with the COOKIE-WAIT state.
      */
     return sctp_sf_cookie_wait_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Stop T1 timer and abort association with "INIT failed".
  *
  * This is common code called by several sctp_sf_*_abort() functions above.
  */
 static enum sctp_disposition sctp_stop_t1_and_abort(
                     struct net *net,
                     struct sctp_cmd_seq *commands,
                     __be16 error, int sk_err,
                     const struct sctp_association *asoc,
                     struct sctp_transport *transport)
 {
     pr_debug("%s: ABORT received (INIT)\n", __func__);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_CLOSED));
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(sk_err));
     /* CMD_INIT_FAILED will DELETE_TCB. */
     sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
             SCTP_PERR(error));
 
     return SCTP_DISPOSITION_ABORT;
 }
 
 /*
  * sctp_sf_do_9_2_shut
  *
  * Section: 9.2
  * Upon the reception of the SHUTDOWN, the peer endpoint shall
  *  - enter the SHUTDOWN-RECEIVED state,
  *
  *  - stop accepting new data from its SCTP user
  *
  *  - verify, by checking the Cumulative TSN Ack field of the chunk,
  *    that all its outstanding DATA chunks have been received by the
  *    SHUTDOWN sender.
  *
  * Once an endpoint as reached the SHUTDOWN-RECEIVED state it MUST NOT
  * send a SHUTDOWN in response to a ULP request. And should discard
  * subsequent SHUTDOWN chunks.
  *
  * If there are still outstanding DATA chunks left, the SHUTDOWN
  * receiver shall continue to follow normal data transmission
  * procedures defined in Section 6 until all outstanding DATA chunks
  * are acknowledged; however, the SHUTDOWN receiver MUST NOT accept
  * new data from its SCTP user.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_9_2_shutdown(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     enum sctp_disposition disposition;
     struct sctp_chunk *chunk = arg;
     struct sctp_shutdownhdr *sdh;
     struct sctp_ulpevent *ev;
     __u32 ctsn;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the SHUTDOWN chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* Convert the elaborate header.  */
     sdh = (struct sctp_shutdownhdr *)chunk->skb->data;
     skb_pull(chunk->skb, sizeof(*sdh));
     chunk->subh.shutdown_hdr = sdh;
     ctsn = ntohl(sdh->cum_tsn_ack);
 
     if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
         pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
              asoc->ctsn_ack_point);
 
         return SCTP_DISPOSITION_DISCARD;
     }
 
     /* If Cumulative TSN Ack beyond the max tsn currently
      * send, terminating the association and respond to the
      * sender with an ABORT.
      */
     if (!TSN_lt(ctsn, asoc->next_tsn))
         return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
 
     /* API 5.3.1.5 SCTP_SHUTDOWN_EVENT
      * When a peer sends a SHUTDOWN, SCTP delivers this notification to
      * inform the application that it should cease sending data.
      */
     ev = sctp_ulpevent_make_shutdown_event(asoc, 0, GFP_ATOMIC);
     if (!ev) {
         disposition = SCTP_DISPOSITION_NOMEM;
         goto out;
     }
     sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
 
     /* Upon the reception of the SHUTDOWN, the peer endpoint shall
      *  - enter the SHUTDOWN-RECEIVED state,
      *  - stop accepting new data from its SCTP user
      *
      * [This is implicit in the new state.]
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_SHUTDOWN_RECEIVED));
     disposition = SCTP_DISPOSITION_CONSUME;
 
     if (sctp_outq_is_empty(&asoc->outqueue)) {
         disposition = sctp_sf_do_9_2_shutdown_ack(net, ep, asoc, type,
                               arg, commands);
     }
 
     if (SCTP_DISPOSITION_NOMEM == disposition)
         goto out;
 
     /*  - verify, by checking the Cumulative TSN Ack field of the
      *    chunk, that all its outstanding DATA chunks have been
      *    received by the SHUTDOWN sender.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
             SCTP_BE32(chunk->subh.shutdown_hdr->cum_tsn_ack));
 
 out:
     return disposition;
 }
 
 /*
  * sctp_sf_do_9_2_shut_ctsn
  *
  * Once an endpoint has reached the SHUTDOWN-RECEIVED state,
  * it MUST NOT send a SHUTDOWN in response to a ULP request.
  * The Cumulative TSN Ack of the received SHUTDOWN chunk
  * MUST be processed.
  */
 enum sctp_disposition sctp_sf_do_9_2_shut_ctsn(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_shutdownhdr *sdh;
     __u32 ctsn;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the SHUTDOWN chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     sdh = (struct sctp_shutdownhdr *)chunk->skb->data;
     ctsn = ntohl(sdh->cum_tsn_ack);
 
     if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
         pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
              asoc->ctsn_ack_point);
 
         return SCTP_DISPOSITION_DISCARD;
     }
 
     /* If Cumulative TSN Ack beyond the max tsn currently
      * send, terminating the association and respond to the
      * sender with an ABORT.
      */
     if (!TSN_lt(ctsn, asoc->next_tsn))
         return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
 
     /* verify, by checking the Cumulative TSN Ack field of the
      * chunk, that all its outstanding DATA chunks have been
      * received by the SHUTDOWN sender.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
             SCTP_BE32(sdh->cum_tsn_ack));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* RFC 2960 9.2
  * If an endpoint is in SHUTDOWN-ACK-SENT state and receives an INIT chunk
  * (e.g., if the SHUTDOWN COMPLETE was lost) with source and destination
  * transport addresses (either in the IP addresses or in the INIT chunk)
  * that belong to this association, it should discard the INIT chunk and
  * retransmit the SHUTDOWN ACK chunk.
  */
 static enum sctp_disposition
 __sctp_sf_do_9_2_reshutack(struct net *net, const struct sctp_endpoint *ep,
                const struct sctp_association *asoc,
                const union sctp_subtype type, void *arg,
                struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *reply;
 
     /* Make sure that the chunk has a valid length */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* Since we are not going to really process this INIT, there
      * is no point in verifying chunk boundaries.  Just generate
      * the SHUTDOWN ACK.
      */
     reply = sctp_make_shutdown_ack(asoc, chunk);
     if (NULL == reply)
         goto nomem;
 
     /* Set the transport for the SHUTDOWN ACK chunk and the timeout for
      * the T2-SHUTDOWN timer.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
 
     /* and restart the T2-shutdown timer. */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
 
     return SCTP_DISPOSITION_CONSUME;
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 enum sctp_disposition
 sctp_sf_do_9_2_reshutack(struct net *net, const struct sctp_endpoint *ep,
              const struct sctp_association *asoc,
              const union sctp_subtype type, void *arg,
              struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (!chunk->singleton)
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_init_chunk)))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (chunk->sctp_hdr->vtag != 0)
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
 
     return __sctp_sf_do_9_2_reshutack(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * sctp_sf_do_ecn_cwr
  *
  * Section:  Appendix A: Explicit Congestion Notification
  *
  * CWR:
  *
  * RFC 2481 details a specific bit for a sender to send in the header of
  * its next outbound TCP segment to indicate to its peer that it has
  * reduced its congestion window.  This is termed the CWR bit.  For
  * SCTP the same indication is made by including the CWR chunk.
  * This chunk contains one data element, i.e. the TSN number that
  * was sent in the ECNE chunk.  This element represents the lowest
  * TSN number in the datagram that was originally marked with the
  * CE bit.
  *
  * Verification Tag: 8.5 Verification Tag [Normal verification]
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_ecn_cwr(struct net *net,
                      const struct sctp_endpoint *ep,
                      const struct sctp_association *asoc,
                      const union sctp_subtype type,
                      void *arg,
                      struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_cwrhdr *cwr;
     u32 lowest_tsn;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_ecne_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     cwr = (struct sctp_cwrhdr *)chunk->skb->data;
     skb_pull(chunk->skb, sizeof(*cwr));
 
     lowest_tsn = ntohl(cwr->lowest_tsn);
 
     /* Does this CWR ack the last sent congestion notification? */
     if (TSN_lte(asoc->last_ecne_tsn, lowest_tsn)) {
         /* Stop sending ECNE. */
         sctp_add_cmd_sf(commands,
                 SCTP_CMD_ECN_CWR,
                 SCTP_U32(lowest_tsn));
     }
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * sctp_sf_do_ecne
  *
  * Section:  Appendix A: Explicit Congestion Notification
  *
  * ECN-Echo
  *
  * RFC 2481 details a specific bit for a receiver to send back in its
  * TCP acknowledgements to notify the sender of the Congestion
  * Experienced (CE) bit having arrived from the network.  For SCTP this
  * same indication is made by including the ECNE chunk.  This chunk
  * contains one data element, i.e. the lowest TSN associated with the IP
  * datagram marked with the CE bit.....
  *
  * Verification Tag: 8.5 Verification Tag [Normal verification]
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_ecne(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg, struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_ecnehdr *ecne;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_ecne_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     ecne = (struct sctp_ecnehdr *)chunk->skb->data;
     skb_pull(chunk->skb, sizeof(*ecne));
 
     /* If this is a newer ECNE than the last CWR packet we sent out */
     sctp_add_cmd_sf(commands, SCTP_CMD_ECN_ECNE,
             SCTP_U32(ntohl(ecne->lowest_tsn)));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Section: 6.2  Acknowledgement on Reception of DATA Chunks
  *
  * The SCTP endpoint MUST always acknowledge the reception of each valid
  * DATA chunk.
  *
  * The guidelines on delayed acknowledgement algorithm specified in
  * Section 4.2 of [RFC2581] SHOULD be followed. Specifically, an
  * acknowledgement SHOULD be generated for at least every second packet
  * (not every second DATA chunk) received, and SHOULD be generated within
  * 200 ms of the arrival of any unacknowledged DATA chunk. In some
  * situations it may be beneficial for an SCTP transmitter to be more
  * conservative than the algorithms detailed in this document allow.
  * However, an SCTP transmitter MUST NOT be more aggressive than the
  * following algorithms allow.
  *
  * A SCTP receiver MUST NOT generate more than one SACK for every
  * incoming packet, other than to update the offered window as the
  * receiving application consumes new data.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_eat_data_6_2(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     union sctp_arg force = SCTP_NOFORCE();
     struct sctp_chunk *chunk = arg;
     int error;
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     if (!sctp_chunk_length_valid(chunk, sctp_datachk_len(&asoc->stream)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     error = sctp_eat_data(asoc, chunk, commands);
     switch (error) {
     case SCTP_IERROR_NO_ERROR:
         break;
     case SCTP_IERROR_HIGH_TSN:
     case SCTP_IERROR_BAD_STREAM:
         SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
         goto discard_noforce;
     case SCTP_IERROR_DUP_TSN:
     case SCTP_IERROR_IGNORE_TSN:
         SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
         goto discard_force;
     case SCTP_IERROR_NO_DATA:
         return SCTP_DISPOSITION_ABORT;
     case SCTP_IERROR_PROTO_VIOLATION:
         return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
                            (u8 *)chunk->subh.data_hdr,
                            sctp_datahdr_len(&asoc->stream));
     default:
         BUG();
     }
 
     if (chunk->chunk_hdr->flags & SCTP_DATA_SACK_IMM)
         force = SCTP_FORCE();
 
     if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
     }
 
     /* If this is the last chunk in a packet, we need to count it
      * toward sack generation.  Note that we need to SACK every
      * OTHER packet containing data chunks, EVEN IF WE DISCARD
      * THEM.  We elect to NOT generate SACK's if the chunk fails
      * the verification tag test.
      *
      * RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks
      *
      * The SCTP endpoint MUST always acknowledge the reception of
      * each valid DATA chunk.
      *
      * The guidelines on delayed acknowledgement algorithm
      * specified in  Section 4.2 of [RFC2581] SHOULD be followed.
      * Specifically, an acknowledgement SHOULD be generated for at
      * least every second packet (not every second DATA chunk)
      * received, and SHOULD be generated within 200 ms of the
      * arrival of any unacknowledged DATA chunk.  In some
      * situations it may be beneficial for an SCTP transmitter to
      * be more conservative than the algorithms detailed in this
      * document allow. However, an SCTP transmitter MUST NOT be
      * more aggressive than the following algorithms allow.
      */
     if (chunk->end_of_packet)
         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
 
     return SCTP_DISPOSITION_CONSUME;
 
 discard_force:
     /* RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks
      *
      * When a packet arrives with duplicate DATA chunk(s) and with
      * no new DATA chunk(s), the endpoint MUST immediately send a
      * SACK with no delay.  If a packet arrives with duplicate
      * DATA chunk(s) bundled with new DATA chunks, the endpoint
      * MAY immediately send a SACK.  Normally receipt of duplicate
      * DATA chunks will occur when the original SACK chunk was lost
      * and the peer's RTO has expired.  The duplicate TSN number(s)
      * SHOULD be reported in the SACK as duplicate.
      */
     /* In our case, we split the MAY SACK advice up whether or not
      * the last chunk is a duplicate.'
      */
     if (chunk->end_of_packet)
         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
     return SCTP_DISPOSITION_DISCARD;
 
 discard_noforce:
     if (chunk->end_of_packet)
         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
 
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /*
  * sctp_sf_eat_data_fast_4_4
  *
  * Section: 4 (4)
  * (4) In SHUTDOWN-SENT state the endpoint MUST acknowledge any received
  *    DATA chunks without delay.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_eat_data_fast_4_4(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     int error;
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     if (!sctp_chunk_length_valid(chunk, sctp_datachk_len(&asoc->stream)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     error = sctp_eat_data(asoc, chunk, commands);
     switch (error) {
     case SCTP_IERROR_NO_ERROR:
     case SCTP_IERROR_HIGH_TSN:
     case SCTP_IERROR_DUP_TSN:
     case SCTP_IERROR_IGNORE_TSN:
     case SCTP_IERROR_BAD_STREAM:
         break;
     case SCTP_IERROR_NO_DATA:
         return SCTP_DISPOSITION_ABORT;
     case SCTP_IERROR_PROTO_VIOLATION:
         return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
                            (u8 *)chunk->subh.data_hdr,
                            sctp_datahdr_len(&asoc->stream));
     default:
         BUG();
     }
 
     /* Go a head and force a SACK, since we are shutting down. */
 
     /* Implementor's Guide.
      *
      * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
      * respond to each received packet containing one or more DATA chunk(s)
      * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer
      */
     if (chunk->end_of_packet) {
         /* We must delay the chunk creation since the cumulative
          * TSN has not been updated yet.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL());
         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
     }
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Section: 6.2  Processing a Received SACK
  * D) Any time a SACK arrives, the endpoint performs the following:
  *
  *     i) If Cumulative TSN Ack is less than the Cumulative TSN Ack Point,
  *     then drop the SACK.   Since Cumulative TSN Ack is monotonically
  *     increasing, a SACK whose Cumulative TSN Ack is less than the
  *     Cumulative TSN Ack Point indicates an out-of-order SACK.
  *
  *     ii) Set rwnd equal to the newly received a_rwnd minus the number
  *     of bytes still outstanding after processing the Cumulative TSN Ack
  *     and the Gap Ack Blocks.
  *
  *     iii) If the SACK is missing a TSN that was previously
  *     acknowledged via a Gap Ack Block (e.g., the data receiver
  *     reneged on the data), then mark the corresponding DATA chunk
  *     as available for retransmit:  Mark it as missing for fast
  *     retransmit as described in Section 7.2.4 and if no retransmit
  *     timer is running for the destination address to which the DATA
  *     chunk was originally transmitted, then T3-rtx is started for
  *     that destination address.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_eat_sack_6_2(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_sackhdr *sackh;
     __u32 ctsn;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the SACK chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_sack_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* Pull the SACK chunk from the data buffer */
     sackh = sctp_sm_pull_sack(chunk);
     /* Was this a bogus SACK? */
     if (!sackh)
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     chunk->subh.sack_hdr = sackh;
     ctsn = ntohl(sackh->cum_tsn_ack);
 
     /* If Cumulative TSN Ack beyond the max tsn currently
      * send, terminating the association and respond to the
      * sender with an ABORT.
      */
     if (TSN_lte(asoc->next_tsn, ctsn))
         return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
 
     trace_sctp_probe(ep, asoc, chunk);
 
     /* i) If Cumulative TSN Ack is less than the Cumulative TSN
      *     Ack Point, then drop the SACK.  Since Cumulative TSN
      *     Ack is monotonically increasing, a SACK whose
      *     Cumulative TSN Ack is less than the Cumulative TSN Ack
      *     Point indicates an out-of-order SACK.
      */
     if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
         pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
              asoc->ctsn_ack_point);
 
         return SCTP_DISPOSITION_DISCARD;
     }
 
     /* Return this SACK for further processing.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK, SCTP_CHUNK(chunk));
 
     /* Note: We do the rest of the work on the PROCESS_SACK
      * sideeffect.
      */
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Generate an ABORT in response to a packet.
  *
  * Section: 8.4 Handle "Out of the blue" Packets, sctpimpguide 2.41
  *
  * 8) The receiver should respond to the sender of the OOTB packet with
  *    an ABORT.  When sending the ABORT, the receiver of the OOTB packet
  *    MUST fill in the Verification Tag field of the outbound packet
  *    with the value found in the Verification Tag field of the OOTB
  *    packet and set the T-bit in the Chunk Flags to indicate that the
  *    Verification Tag is reflected.  After sending this ABORT, the
  *    receiver of the OOTB packet shall discard the OOTB packet and take
  *    no further action.
  *
  * Verification Tag:
  *
  * The return value is the disposition of the chunk.
 */
 static enum sctp_disposition sctp_sf_tabort_8_4_8(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_packet *packet = NULL;
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *abort;
 
     packet = sctp_ootb_pkt_new(net, asoc, chunk);
     if (!packet)
         return SCTP_DISPOSITION_NOMEM;
 
     /* Make an ABORT. The T bit will be set if the asoc
      * is NULL.
      */
     abort = sctp_make_abort(asoc, chunk, 0);
     if (!abort) {
         sctp_ootb_pkt_free(packet);
         return SCTP_DISPOSITION_NOMEM;
     }
 
     /* Reflect vtag if T-Bit is set */
     if (sctp_test_T_bit(abort))
         packet->vtag = ntohl(chunk->sctp_hdr->vtag);
 
     /* Set the skb to the belonging sock for accounting.  */
     abort->skb->sk = ep->base.sk;
 
     sctp_packet_append_chunk(packet, abort);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet));
 
     SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 
     sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* Handling of SCTP Packets Containing an INIT Chunk Matching an
  * Existing Associations when the UDP encap port is incorrect.
  *
  * From Section 4 at draft-tuexen-tsvwg-sctp-udp-encaps-cons-03.
  */
 static enum sctp_disposition sctp_sf_new_encap_port(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_packet *packet = NULL;
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *abort;
 
     packet = sctp_ootb_pkt_new(net, asoc, chunk);
     if (!packet)
         return SCTP_DISPOSITION_NOMEM;
 
     abort = sctp_make_new_encap_port(asoc, chunk);
     if (!abort) {
         sctp_ootb_pkt_free(packet);
         return SCTP_DISPOSITION_NOMEM;
     }
 
     abort->skb->sk = ep->base.sk;
 
     sctp_packet_append_chunk(packet, abort);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
             SCTP_PACKET(packet));
 
     SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 
     sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Received an ERROR chunk from peer.  Generate SCTP_REMOTE_ERROR
  * event as ULP notification for each cause included in the chunk.
  *
  * API 5.3.1.3 - SCTP_REMOTE_ERROR
  *
  * The return value is the disposition of the chunk.
 */
 enum sctp_disposition sctp_sf_operr_notify(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_errhdr *err;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the ERROR chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_operr_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
     sctp_walk_errors(err, chunk->chunk_hdr);
     if ((void *)err != (void *)chunk->chunk_end)
         return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
                           (void *)err, commands);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_OPERR,
             SCTP_CHUNK(chunk));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Process an inbound SHUTDOWN ACK.
  *
  * From Section 9.2:
  * Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall
  * stop the T2-shutdown timer, send a SHUTDOWN COMPLETE chunk to its
  * peer, and remove all record of the association.
  *
  * The return value is the disposition.
  */
 enum sctp_disposition sctp_sf_do_9_2_final(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *reply;
     struct sctp_ulpevent *ev;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
     /* 10.2 H) SHUTDOWN COMPLETE notification
      *
      * When SCTP completes the shutdown procedures (section 9.2) this
      * notification is passed to the upper layer.
      */
     ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP,
                          0, 0, 0, NULL, GFP_ATOMIC);
     if (!ev)
         goto nomem;
 
     /* ...send a SHUTDOWN COMPLETE chunk to its peer, */
     reply = sctp_make_shutdown_complete(asoc, chunk);
     if (!reply)
         goto nomem_chunk;
 
     /* Do all the commands now (after allocation), so that we
      * have consistent state if memory allocation fails
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
 
     /* Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall
      * stop the T2-shutdown timer,
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_CLOSED));
     SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
 
     /* ...and remove all record of the association. */
     sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
     return SCTP_DISPOSITION_DELETE_TCB;
 
 nomem_chunk:
     sctp_ulpevent_free(ev);
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * RFC 2960, 8.4 - Handle "Out of the blue" Packets, sctpimpguide 2.41.
  *
  * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
  *    respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
  *    When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
  *    packet must fill in the Verification Tag field of the outbound
  *    packet with the Verification Tag received in the SHUTDOWN ACK and
  *    set the T-bit in the Chunk Flags to indicate that the Verification
  *    Tag is reflected.
  *
  * 8) The receiver should respond to the sender of the OOTB packet with
  *    an ABORT.  When sending the ABORT, the receiver of the OOTB packet
  *    MUST fill in the Verification Tag field of the outbound packet
  *    with the value found in the Verification Tag field of the OOTB
  *    packet and set the T-bit in the Chunk Flags to indicate that the
  *    Verification Tag is reflected.  After sending this ABORT, the
  *    receiver of the OOTB packet shall discard the OOTB packet and take
  *    no further action.
  */
 enum sctp_disposition sctp_sf_ootb(struct net *net,
                    const struct sctp_endpoint *ep,
                    const struct sctp_association *asoc,
                    const union sctp_subtype type,
                    void *arg, struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sk_buff *skb = chunk->skb;
     struct sctp_chunkhdr *ch;
     struct sctp_errhdr *err;
     int ootb_cookie_ack = 0;
     int ootb_shut_ack = 0;
     __u8 *ch_end;
 
     SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
 
     if (asoc && !sctp_vtag_verify(chunk, asoc))
         asoc = NULL;
 
     ch = (struct sctp_chunkhdr *)chunk->chunk_hdr;
     do {
         /* Report violation if the chunk is less then minimal */
         if (ntohs(ch->length) < sizeof(*ch))
             return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
         /* Report violation if chunk len overflows */
         ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
         if (ch_end > skb_tail_pointer(skb))
             return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
         /* Now that we know we at least have a chunk header,
          * do things that are type appropriate.
          */
         if (SCTP_CID_SHUTDOWN_ACK == ch->type)
             ootb_shut_ack = 1;
 
         /* RFC 2960, Section 3.3.7
          *   Moreover, under any circumstances, an endpoint that
          *   receives an ABORT  MUST NOT respond to that ABORT by
          *   sending an ABORT of its own.
          */
         if (SCTP_CID_ABORT == ch->type)
             return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
         /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
          * or a COOKIE ACK the SCTP Packet should be silently
          * discarded.
          */
 
         if (SCTP_CID_COOKIE_ACK == ch->type)
             ootb_cookie_ack = 1;
 
         if (SCTP_CID_ERROR == ch->type) {
             sctp_walk_errors(err, ch) {
                 if (SCTP_ERROR_STALE_COOKIE == err->cause) {
                     ootb_cookie_ack = 1;
                     break;
                 }
             }
         }
 
         ch = (struct sctp_chunkhdr *)ch_end;
     } while (ch_end < skb_tail_pointer(skb));
 
     if (ootb_shut_ack)
         return sctp_sf_shut_8_4_5(net, ep, asoc, type, arg, commands);
     else if (ootb_cookie_ack)
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     else
         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Handle an "Out of the blue" SHUTDOWN ACK.
  *
  * Section: 8.4 5, sctpimpguide 2.41.
  *
  * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
  *    respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
  *    When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
  *    packet must fill in the Verification Tag field of the outbound
  *    packet with the Verification Tag received in the SHUTDOWN ACK and
  *    set the T-bit in the Chunk Flags to indicate that the Verification
  *    Tag is reflected.
  *
  * Inputs
  * (endpoint, asoc, type, arg, commands)
  *
  * Outputs
  * (enum sctp_disposition)
  *
  * The return value is the disposition of the chunk.
  */
 static enum sctp_disposition sctp_sf_shut_8_4_5(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_packet *packet = NULL;
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *shut;
 
     packet = sctp_ootb_pkt_new(net, asoc, chunk);
     if (!packet)
         return SCTP_DISPOSITION_NOMEM;
 
     /* Make an SHUTDOWN_COMPLETE.
      * The T bit will be set if the asoc is NULL.
      */
     shut = sctp_make_shutdown_complete(asoc, chunk);
     if (!shut) {
         sctp_ootb_pkt_free(packet);
         return SCTP_DISPOSITION_NOMEM;
     }
 
     /* Reflect vtag if T-Bit is set */
     if (sctp_test_T_bit(shut))
         packet->vtag = ntohl(chunk->sctp_hdr->vtag);
 
     /* Set the skb to the belonging sock for accounting.  */
     shut->skb->sk = ep->base.sk;
 
     sctp_packet_append_chunk(packet, shut);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
             SCTP_PACKET(packet));
 
     SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 
     /* We need to discard the rest of the packet to prevent
      * potential boomming attacks from additional bundled chunks.
      * This is documented in SCTP Threats ID.
      */
     return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Handle SHUTDOWN ACK in COOKIE_ECHOED or COOKIE_WAIT state.
  *
  * Verification Tag:  8.5.1 E) Rules for packet carrying a SHUTDOWN ACK
  *   If the receiver is in COOKIE-ECHOED or COOKIE-WAIT state the
  *   procedures in section 8.4 SHOULD be followed, in other words it
  *   should be treated as an Out Of The Blue packet.
  *   [This means that we do NOT check the Verification Tag on these
  *   chunks. --piggy ]
  *
  */
 enum sctp_disposition sctp_sf_do_8_5_1_E_sa(struct net *net,
                         const struct sctp_endpoint *ep,
                         const struct sctp_association *asoc,
                         const union sctp_subtype type,
                         void *arg,
                         struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (!sctp_vtag_verify(chunk, asoc))
         asoc = NULL;
 
     /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* Although we do have an association in this case, it corresponds
      * to a restarted association. So the packet is treated as an OOTB
      * packet and the state function that handles OOTB SHUTDOWN_ACK is
      * called with a NULL association.
      */
     SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
 
     return sctp_sf_shut_8_4_5(net, ep, NULL, type, arg, commands);
 }
 
 /* ADDIP Section 4.2 Upon reception of an ASCONF Chunk.  */
 enum sctp_disposition sctp_sf_do_asconf(struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_paramhdr *err_param = NULL;
     struct sctp_chunk *asconf_ack = NULL;
     struct sctp_chunk *chunk = arg;
     struct sctp_addiphdr *hdr;
     __u32 serial;
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     /* Make sure that the ASCONF ADDIP chunk has a valid length.  */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_addip_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* ADD-IP: Section 4.1.1
      * This chunk MUST be sent in an authenticated way by using
      * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk
      * is received unauthenticated it MUST be silently discarded as
      * described in [I-D.ietf-tsvwg-sctp-auth].
      */
     if (!asoc->peer.asconf_capable ||
         (!net->sctp.addip_noauth && !chunk->auth))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     hdr = (struct sctp_addiphdr *)chunk->skb->data;
     serial = ntohl(hdr->serial);
 
     /* Verify the ASCONF chunk before processing it. */
     if (!sctp_verify_asconf(asoc, chunk, true, &err_param))
         return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
                           (void *)err_param, commands);
 
     /* ADDIP 5.2 E1) Compare the value of the serial number to the value
      * the endpoint stored in a new association variable
      * 'Peer-Serial-Number'.
      */
     if (serial == asoc->peer.addip_serial + 1) {
         /* If this is the first instance of ASCONF in the packet,
          * we can clean our old ASCONF-ACKs.
          */
         if (!chunk->has_asconf)
             sctp_assoc_clean_asconf_ack_cache(asoc);
 
         /* ADDIP 5.2 E4) When the Sequence Number matches the next one
          * expected, process the ASCONF as described below and after
          * processing the ASCONF Chunk, append an ASCONF-ACK Chunk to
          * the response packet and cache a copy of it (in the event it
          * later needs to be retransmitted).
          *
          * Essentially, do V1-V5.
          */
         asconf_ack = sctp_process_asconf((struct sctp_association *)
                          asoc, chunk);
         if (!asconf_ack)
             return SCTP_DISPOSITION_NOMEM;
     } else if (serial < asoc->peer.addip_serial + 1) {
         /* ADDIP 5.2 E2)
          * If the value found in the Sequence Number is less than the
          * ('Peer- Sequence-Number' + 1), simply skip to the next
          * ASCONF, and include in the outbound response packet
          * any previously cached ASCONF-ACK response that was
          * sent and saved that matches the Sequence Number of the
          * ASCONF.  Note: It is possible that no cached ASCONF-ACK
          * Chunk exists.  This will occur when an older ASCONF
          * arrives out of order.  In such a case, the receiver
          * should skip the ASCONF Chunk and not include ASCONF-ACK
          * Chunk for that chunk.
          */
         asconf_ack = sctp_assoc_lookup_asconf_ack(asoc, hdr->serial);
         if (!asconf_ack)
             return SCTP_DISPOSITION_DISCARD;
 
         /* Reset the transport so that we select the correct one
          * this time around.  This is to make sure that we don't
          * accidentally use a stale transport that's been removed.
          */
         asconf_ack->transport = NULL;
     } else {
         /* ADDIP 5.2 E5) Otherwise, the ASCONF Chunk is discarded since
          * it must be either a stale packet or from an attacker.
          */
         return SCTP_DISPOSITION_DISCARD;
     }
 
     /* ADDIP 5.2 E6)  The destination address of the SCTP packet
      * containing the ASCONF-ACK Chunks MUST be the source address of
      * the SCTP packet that held the ASCONF Chunks.
      *
      * To do this properly, we'll set the destination address of the chunk
      * and at the transmit time, will try look up the transport to use.
      * Since ASCONFs may be bundled, the correct transport may not be
      * created until we process the entire packet, thus this workaround.
      */
     asconf_ack->dest = chunk->source;
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack));
     if (asoc->new_transport) {
         sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands);
         ((struct sctp_association *)asoc)->new_transport = NULL;
     }
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 static enum sctp_disposition sctp_send_next_asconf(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     struct sctp_association *asoc,
                     const union sctp_subtype type,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *asconf;
     struct list_head *entry;
 
     if (list_empty(&asoc->addip_chunk_list))
         return SCTP_DISPOSITION_CONSUME;
 
     entry = asoc->addip_chunk_list.next;
     asconf = list_entry(entry, struct sctp_chunk, list);
 
     list_del_init(entry);
     sctp_chunk_hold(asconf);
     asoc->addip_last_asconf = asconf;
 
     return sctp_sf_do_prm_asconf(net, ep, asoc, type, asconf, commands);
 }
 
 /*
  * ADDIP Section 4.3 General rules for address manipulation
  * When building TLV parameters for the ASCONF Chunk that will add or
  * delete IP addresses the D0 to D13 rules should be applied:
  */
 enum sctp_disposition sctp_sf_do_asconf_ack(struct net *net,
                         const struct sctp_endpoint *ep,
                         const struct sctp_association *asoc,
                         const union sctp_subtype type,
                         void *arg,
                         struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *last_asconf = asoc->addip_last_asconf;
     struct sctp_paramhdr *err_param = NULL;
     struct sctp_chunk *asconf_ack = arg;
     struct sctp_addiphdr *addip_hdr;
     __u32 sent_serial, rcvd_serial;
     struct sctp_chunk *abort;
 
     if (!sctp_vtag_verify(asconf_ack, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     /* Make sure that the ADDIP chunk has a valid length.  */
     if (!sctp_chunk_length_valid(asconf_ack,
                      sizeof(struct sctp_addip_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     /* ADD-IP, Section 4.1.2:
      * This chunk MUST be sent in an authenticated way by using
      * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk
      * is received unauthenticated it MUST be silently discarded as
      * described in [I-D.ietf-tsvwg-sctp-auth].
      */
     if (!asoc->peer.asconf_capable ||
         (!net->sctp.addip_noauth && !asconf_ack->auth))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     addip_hdr = (struct sctp_addiphdr *)asconf_ack->skb->data;
     rcvd_serial = ntohl(addip_hdr->serial);
 
     /* Verify the ASCONF-ACK chunk before processing it. */
     if (!sctp_verify_asconf(asoc, asconf_ack, false, &err_param))
         return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
                (void *)err_param, commands);
 
     if (last_asconf) {
         addip_hdr = (struct sctp_addiphdr *)last_asconf->subh.addip_hdr;
         sent_serial = ntohl(addip_hdr->serial);
     } else {
         sent_serial = asoc->addip_serial - 1;
     }
 
     /* D0) If an endpoint receives an ASCONF-ACK that is greater than or
      * equal to the next serial number to be used but no ASCONF chunk is
      * outstanding the endpoint MUST ABORT the association. Note that a
      * sequence number is greater than if it is no more than 2^^31-1
      * larger than the current sequence number (using serial arithmetic).
      */
     if (ADDIP_SERIAL_gte(rcvd_serial, sent_serial + 1) &&
         !(asoc->addip_last_asconf)) {
         abort = sctp_make_abort(asoc, asconf_ack,
                     sizeof(struct sctp_errhdr));
         if (abort) {
             sctp_init_cause(abort, SCTP_ERROR_ASCONF_ACK, 0);
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(abort));
         }
         /* We are going to ABORT, so we might as well stop
          * processing the rest of the chunks in the packet.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
         sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ECONNABORTED));
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_ASCONF_ACK));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_DISPOSITION_ABORT;
     }
 
     if ((rcvd_serial == sent_serial) && asoc->addip_last_asconf) {
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
 
         if (!sctp_process_asconf_ack((struct sctp_association *)asoc,
                          asconf_ack))
             return sctp_send_next_asconf(net, ep,
                     (struct sctp_association *)asoc,
                             type, commands);
 
         abort = sctp_make_abort(asoc, asconf_ack,
                     sizeof(struct sctp_errhdr));
         if (abort) {
             sctp_init_cause(abort, SCTP_ERROR_RSRC_LOW, 0);
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(abort));
         }
         /* We are going to ABORT, so we might as well stop
          * processing the rest of the chunks in the packet.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ECONNABORTED));
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_ASCONF_ACK));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_DISPOSITION_ABORT;
     }
 
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /* RE-CONFIG Section 5.2 Upon reception of an RECONF Chunk. */
 enum sctp_disposition sctp_sf_do_reconf(struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_paramhdr *err_param = NULL;
     struct sctp_chunk *chunk = arg;
     struct sctp_reconf_chunk *hdr;
     union sctp_params param;
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     /* Make sure that the RECONF chunk has a valid length.  */
     if (!sctp_chunk_length_valid(chunk, sizeof(*hdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     if (!sctp_verify_reconf(asoc, chunk, &err_param))
         return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
                           (void *)err_param, commands);
 
     hdr = (struct sctp_reconf_chunk *)chunk->chunk_hdr;
     sctp_walk_params(param, hdr, params) {
         struct sctp_chunk *reply = NULL;
         struct sctp_ulpevent *ev = NULL;
 
         if (param.p->type == SCTP_PARAM_RESET_OUT_REQUEST)
             reply = sctp_process_strreset_outreq(
                 (struct sctp_association *)asoc, param, &ev);
         else if (param.p->type == SCTP_PARAM_RESET_IN_REQUEST)
             reply = sctp_process_strreset_inreq(
                 (struct sctp_association *)asoc, param, &ev);
         else if (param.p->type == SCTP_PARAM_RESET_TSN_REQUEST)
             reply = sctp_process_strreset_tsnreq(
                 (struct sctp_association *)asoc, param, &ev);
         else if (param.p->type == SCTP_PARAM_RESET_ADD_OUT_STREAMS)
             reply = sctp_process_strreset_addstrm_out(
                 (struct sctp_association *)asoc, param, &ev);
         else if (param.p->type == SCTP_PARAM_RESET_ADD_IN_STREAMS)
             reply = sctp_process_strreset_addstrm_in(
                 (struct sctp_association *)asoc, param, &ev);
         else if (param.p->type == SCTP_PARAM_RESET_RESPONSE)
             reply = sctp_process_strreset_resp(
                 (struct sctp_association *)asoc, param, &ev);
 
         if (ev)
             sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                     SCTP_ULPEVENT(ev));
 
         if (reply)
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(reply));
     }
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * PR-SCTP Section 3.6 Receiver Side Implementation of PR-SCTP
  *
  * When a FORWARD TSN chunk arrives, the data receiver MUST first update
  * its cumulative TSN point to the value carried in the FORWARD TSN
  * chunk, and then MUST further advance its cumulative TSN point locally
  * if possible.
  * After the above processing, the data receiver MUST stop reporting any
  * missing TSNs earlier than or equal to the new cumulative TSN point.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_eat_fwd_tsn(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg,
                       struct sctp_cmd_seq *commands)
 {
     struct sctp_fwdtsn_hdr *fwdtsn_hdr;
     struct sctp_chunk *chunk = arg;
     __u16 len;
     __u32 tsn;
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     if (!asoc->peer.prsctp_capable)
         return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the FORWARD_TSN chunk has valid length.  */
     if (!sctp_chunk_length_valid(chunk, sctp_ftsnchk_len(&asoc->stream)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data;
     chunk->subh.fwdtsn_hdr = fwdtsn_hdr;
     len = ntohs(chunk->chunk_hdr->length);
     len -= sizeof(struct sctp_chunkhdr);
     skb_pull(chunk->skb, len);
 
     tsn = ntohl(fwdtsn_hdr->new_cum_tsn);
     pr_debug("%s: TSN 0x%x\n", __func__, tsn);
 
     /* The TSN is too high--silently discard the chunk and count on it
      * getting retransmitted later.
      */
     if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0)
         goto discard_noforce;
 
     if (!asoc->stream.si->validate_ftsn(chunk))
         goto discard_noforce;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn));
     if (len > sctp_ftsnhdr_len(&asoc->stream))
         sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN,
                 SCTP_CHUNK(chunk));
 
     /* Count this as receiving DATA. */
     if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
     }
 
     /* FIXME: For now send a SACK, but DATA processing may
      * send another.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_NOFORCE());
 
     return SCTP_DISPOSITION_CONSUME;
 
 discard_noforce:
     return SCTP_DISPOSITION_DISCARD;
 }
 
 enum sctp_disposition sctp_sf_eat_fwd_tsn_fast(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_fwdtsn_hdr *fwdtsn_hdr;
     struct sctp_chunk *chunk = arg;
     __u16 len;
     __u32 tsn;
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     if (!asoc->peer.prsctp_capable)
         return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the FORWARD_TSN chunk has a valid length.  */
     if (!sctp_chunk_length_valid(chunk, sctp_ftsnchk_len(&asoc->stream)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data;
     chunk->subh.fwdtsn_hdr = fwdtsn_hdr;
     len = ntohs(chunk->chunk_hdr->length);
     len -= sizeof(struct sctp_chunkhdr);
     skb_pull(chunk->skb, len);
 
     tsn = ntohl(fwdtsn_hdr->new_cum_tsn);
     pr_debug("%s: TSN 0x%x\n", __func__, tsn);
 
     /* The TSN is too high--silently discard the chunk and count on it
      * getting retransmitted later.
      */
     if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0)
         goto gen_shutdown;
 
     if (!asoc->stream.si->validate_ftsn(chunk))
         goto gen_shutdown;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn));
     if (len > sctp_ftsnhdr_len(&asoc->stream))
         sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN,
                 SCTP_CHUNK(chunk));
 
     /* Go a head and force a SACK, since we are shutting down. */
 gen_shutdown:
     /* Implementor's Guide.
      *
      * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
      * respond to each received packet containing one or more DATA chunk(s)
      * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL());
     sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * SCTP-AUTH Section 6.3 Receiving authenticated chunks
  *
  *    The receiver MUST use the HMAC algorithm indicated in the HMAC
  *    Identifier field.  If this algorithm was not specified by the
  *    receiver in the HMAC-ALGO parameter in the INIT or INIT-ACK chunk
  *    during association setup, the AUTH chunk and all chunks after it MUST
  *    be discarded and an ERROR chunk SHOULD be sent with the error cause
  *    defined in Section 4.1.
  *
  *    If an endpoint with no shared key receives a Shared Key Identifier
  *    other than 0, it MUST silently discard all authenticated chunks.  If
  *    the endpoint has at least one endpoint pair shared key for the peer,
  *    it MUST use the key specified by the Shared Key Identifier if a
  *    key has been configured for that Shared Key Identifier.  If no
  *    endpoint pair shared key has been configured for that Shared Key
  *    Identifier, all authenticated chunks MUST be silently discarded.
  *
  * Verification Tag:  8.5 Verification Tag [Normal verification]
  *
  * The return value is the disposition of the chunk.
  */
 static enum sctp_ierror sctp_sf_authenticate(
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk)
 {
     struct sctp_shared_key *sh_key = NULL;
     struct sctp_authhdr *auth_hdr;
     __u8 *save_digest, *digest;
     struct sctp_hmac *hmac;
     unsigned int sig_len;
     __u16 key_id;
 
     /* Pull in the auth header, so we can do some more verification */
     auth_hdr = (struct sctp_authhdr *)chunk->skb->data;
     chunk->subh.auth_hdr = auth_hdr;
     skb_pull(chunk->skb, sizeof(*auth_hdr));
 
     /* Make sure that we support the HMAC algorithm from the auth
      * chunk.
      */
     if (!sctp_auth_asoc_verify_hmac_id(asoc, auth_hdr->hmac_id))
         return SCTP_IERROR_AUTH_BAD_HMAC;
 
     /* Make sure that the provided shared key identifier has been
      * configured
      */
     key_id = ntohs(auth_hdr->shkey_id);
     if (key_id != asoc->active_key_id) {
         sh_key = sctp_auth_get_shkey(asoc, key_id);
         if (!sh_key)
             return SCTP_IERROR_AUTH_BAD_KEYID;
     }
 
     /* Make sure that the length of the signature matches what
      * we expect.
      */
     sig_len = ntohs(chunk->chunk_hdr->length) -
           sizeof(struct sctp_auth_chunk);
     hmac = sctp_auth_get_hmac(ntohs(auth_hdr->hmac_id));
     if (sig_len != hmac->hmac_len)
         return SCTP_IERROR_PROTO_VIOLATION;
 
     /* Now that we've done validation checks, we can compute and
      * verify the hmac.  The steps involved are:
      *  1. Save the digest from the chunk.
      *  2. Zero out the digest in the chunk.
      *  3. Compute the new digest
      *  4. Compare saved and new digests.
      */
     digest = auth_hdr->hmac;
     skb_pull(chunk->skb, sig_len);
 
     save_digest = kmemdup(digest, sig_len, GFP_ATOMIC);
     if (!save_digest)
         goto nomem;
 
     memset(digest, 0, sig_len);
 
     sctp_auth_calculate_hmac(asoc, chunk->skb,
                  (struct sctp_auth_chunk *)chunk->chunk_hdr,
                  sh_key, GFP_ATOMIC);
 
     /* Discard the packet if the digests do not match */
     if (memcmp(save_digest, digest, sig_len)) {
         kfree(save_digest);
         return SCTP_IERROR_BAD_SIG;
     }
 
     kfree(save_digest);
     chunk->auth = 1;
 
     return SCTP_IERROR_NO_ERROR;
 nomem:
     return SCTP_IERROR_NOMEM;
 }
 
 enum sctp_disposition sctp_sf_eat_auth(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg, struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_authhdr *auth_hdr;
     struct sctp_chunk *err_chunk;
     enum sctp_ierror error;
 
     /* Make sure that the peer has AUTH capable */
     if (!asoc->peer.auth_capable)
         return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
 
     if (!sctp_vtag_verify(chunk, asoc)) {
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
                 SCTP_NULL());
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     }
 
     /* Make sure that the AUTH chunk has valid length.  */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_auth_chunk)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     auth_hdr = (struct sctp_authhdr *)chunk->skb->data;
     error = sctp_sf_authenticate(asoc, chunk);
     switch (error) {
     case SCTP_IERROR_AUTH_BAD_HMAC:
         /* Generate the ERROR chunk and discard the rest
          * of the packet
          */
         err_chunk = sctp_make_op_error(asoc, chunk,
                            SCTP_ERROR_UNSUP_HMAC,
                            &auth_hdr->hmac_id,
                            sizeof(__u16), 0);
         if (err_chunk) {
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(err_chunk));
         }
         fallthrough;
     case SCTP_IERROR_AUTH_BAD_KEYID:
     case SCTP_IERROR_BAD_SIG:
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     case SCTP_IERROR_PROTO_VIOLATION:
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     case SCTP_IERROR_NOMEM:
         return SCTP_DISPOSITION_NOMEM;
 
     default:            /* Prevent gcc warnings */
         break;
     }
 
     if (asoc->active_key_id != ntohs(auth_hdr->shkey_id)) {
         struct sctp_ulpevent *ev;
 
         ev = sctp_ulpevent_make_authkey(asoc, ntohs(auth_hdr->shkey_id),
                     SCTP_AUTH_NEW_KEY, GFP_ATOMIC);
 
         if (!ev)
             return -ENOMEM;
 
         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
                 SCTP_ULPEVENT(ev));
     }
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Process an unknown chunk.
  *
  * Section: 3.2. Also, 2.1 in the implementor's guide.
  *
  * Chunk Types are encoded such that the highest-order two bits specify
  * the action that must be taken if the processing endpoint does not
  * recognize the Chunk Type.
  *
  * 00 - Stop processing this SCTP packet and discard it, do not process
  *      any further chunks within it.
  *
  * 01 - Stop processing this SCTP packet and discard it, do not process
  *      any further chunks within it, and report the unrecognized
  *      chunk in an 'Unrecognized Chunk Type'.
  *
  * 10 - Skip this chunk and continue processing.
  *
  * 11 - Skip this chunk and continue processing, but report in an ERROR
  *      Chunk using the 'Unrecognized Chunk Type' cause of error.
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_unk_chunk(struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *unk_chunk = arg;
     struct sctp_chunk *err_chunk;
     struct sctp_chunkhdr *hdr;
 
     pr_debug("%s: processing unknown chunk id:%d\n", __func__, type.chunk);
 
     if (!sctp_vtag_verify(unk_chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the chunk has a valid length.
      * Since we don't know the chunk type, we use a general
      * chunkhdr structure to make a comparison.
      */
     if (!sctp_chunk_length_valid(unk_chunk, sizeof(*hdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     switch (type.chunk & SCTP_CID_ACTION_MASK) {
     case SCTP_CID_ACTION_DISCARD:
         /* Discard the packet.  */
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
     case SCTP_CID_ACTION_DISCARD_ERR:
         /* Generate an ERROR chunk as response. */
         hdr = unk_chunk->chunk_hdr;
         err_chunk = sctp_make_op_error(asoc, unk_chunk,
                            SCTP_ERROR_UNKNOWN_CHUNK, hdr,
                            SCTP_PAD4(ntohs(hdr->length)),
                            0);
         if (err_chunk) {
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(err_chunk));
         }
 
         /* Discard the packet.  */
         sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
         return SCTP_DISPOSITION_CONSUME;
     case SCTP_CID_ACTION_SKIP:
         /* Skip the chunk.  */
         return SCTP_DISPOSITION_DISCARD;
     case SCTP_CID_ACTION_SKIP_ERR:
         /* Generate an ERROR chunk as response. */
         hdr = unk_chunk->chunk_hdr;
         err_chunk = sctp_make_op_error(asoc, unk_chunk,
                            SCTP_ERROR_UNKNOWN_CHUNK, hdr,
                            SCTP_PAD4(ntohs(hdr->length)),
                            0);
         if (err_chunk) {
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(err_chunk));
         }
         /* Skip the chunk.  */
         return SCTP_DISPOSITION_CONSUME;
     default:
         break;
     }
 
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /*
  * Discard the chunk.
  *
  * Section: 0.2, 5.2.3, 5.2.5, 5.2.6, 6.0, 8.4.6, 8.5.1c, 9.2
  * [Too numerous to mention...]
  * Verification Tag: No verification needed.
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_discard_chunk(struct net *net,
                         const struct sctp_endpoint *ep,
                         const struct sctp_association *asoc,
                         const union sctp_subtype type,
                         void *arg,
                         struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (asoc && !sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the chunk has a valid length.
      * Since we don't know the chunk type, we use a general
      * chunkhdr structure to make a comparison.
      */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     pr_debug("%s: chunk:%d is discarded\n", __func__, type.chunk);
 
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /*
  * Discard the whole packet.
  *
  * Section: 8.4 2)
  *
  * 2) If the OOTB packet contains an ABORT chunk, the receiver MUST
  *    silently discard the OOTB packet and take no further action.
  *
  * Verification Tag: No verification necessary
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_pdiscard(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg, struct sctp_cmd_seq *commands)
 {
     SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
     sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 
 /*
  * The other end is violating protocol.
  *
  * Section: Not specified
  * Verification Tag: Not specified
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (asoc, reply_msg, msg_up, timers, counters)
  *
  * We simply tag the chunk as a violation.  The state machine will log
  * the violation and continue.
  */
 enum sctp_disposition sctp_sf_violation(struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     if (!sctp_vtag_verify(chunk, asoc))
         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
     /* Make sure that the chunk has a valid length. */
     if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
                           commands);
 
     return SCTP_DISPOSITION_VIOLATION;
 }
 
 /*
  * Common function to handle a protocol violation.
  */
 static enum sctp_disposition sctp_sf_abort_violation(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     void *arg,
                     struct sctp_cmd_seq *commands,
                     const __u8 *payload,
                     const size_t paylen)
 {
     struct sctp_packet *packet = NULL;
     struct sctp_chunk *chunk =  arg;
     struct sctp_chunk *abort = NULL;
 
     /* SCTP-AUTH, Section 6.3:
      *    It should be noted that if the receiver wants to tear
      *    down an association in an authenticated way only, the
      *    handling of malformed packets should not result in
      *    tearing down the association.
      *
      * This means that if we only want to abort associations
      * in an authenticated way (i.e AUTH+ABORT), then we
      * can't destroy this association just because the packet
      * was malformed.
      */
     if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
         goto discard;
 
     /* Make the abort chunk. */
     abort = sctp_make_abort_violation(asoc, chunk, payload, paylen);
     if (!abort)
         goto nomem;
 
     if (asoc) {
         /* Treat INIT-ACK as a special case during COOKIE-WAIT. */
         if (chunk->chunk_hdr->type == SCTP_CID_INIT_ACK &&
             !asoc->peer.i.init_tag) {
             struct sctp_initack_chunk *initack;
 
             initack = (struct sctp_initack_chunk *)chunk->chunk_hdr;
             if (!sctp_chunk_length_valid(chunk, sizeof(*initack)))
                 abort->chunk_hdr->flags |= SCTP_CHUNK_FLAG_T;
             else {
                 unsigned int inittag;
 
                 inittag = ntohl(initack->init_hdr.init_tag);
                 sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_INITTAG,
                         SCTP_U32(inittag));
             }
         }
 
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
         SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 
         if (asoc->state <= SCTP_STATE_COOKIE_ECHOED) {
             sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                     SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
             sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                     SCTP_ERROR(ECONNREFUSED));
             sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
                     SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
         } else {
             sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                     SCTP_ERROR(ECONNABORTED));
             sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                     SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
             SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         }
     } else {
         packet = sctp_ootb_pkt_new(net, asoc, chunk);
 
         if (!packet)
             goto nomem_pkt;
 
         if (sctp_test_T_bit(abort))
             packet->vtag = ntohl(chunk->sctp_hdr->vtag);
 
         abort->skb->sk = ep->base.sk;
 
         sctp_packet_append_chunk(packet, abort);
 
         sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
             SCTP_PACKET(packet));
 
         SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
     }
 
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
 
 discard:
     sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
     return SCTP_DISPOSITION_ABORT;
 
 nomem_pkt:
     sctp_chunk_free(abort);
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Handle a protocol violation when the chunk length is invalid.
  * "Invalid" length is identified as smaller than the minimal length a
  * given chunk can be.  For example, a SACK chunk has invalid length
  * if its length is set to be smaller than the size of struct sctp_sack_chunk.
  *
  * We inform the other end by sending an ABORT with a Protocol Violation
  * error code.
  *
  * Section: Not specified
  * Verification Tag:  Nothing to do
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * Outputs
  * (reply_msg, msg_up, counters)
  *
  * Generate an  ABORT chunk and terminate the association.
  */
 static enum sctp_disposition sctp_sf_violation_chunklen(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     static const char err_str[] = "The following chunk had invalid length:";
 
     return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
                        sizeof(err_str));
 }
 
 /*
  * Handle a protocol violation when the parameter length is invalid.
  * If the length is smaller than the minimum length of a given parameter,
  * or accumulated length in multi parameters exceeds the end of the chunk,
  * the length is considered as invalid.
  */
 static enum sctp_disposition sctp_sf_violation_paramlen(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg, void *ext,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_paramhdr *param = ext;
     struct sctp_chunk *abort = NULL;
     struct sctp_chunk *chunk = arg;
 
     if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
         goto discard;
 
     /* Make the abort chunk. */
     abort = sctp_make_violation_paramlen(asoc, chunk, param);
     if (!abort)
         goto nomem;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
     SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
             SCTP_ERROR(ECONNABORTED));
     sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
             SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
 
 discard:
     sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
     return SCTP_DISPOSITION_ABORT;
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /* Handle a protocol violation when the peer trying to advance the
  * cumulative tsn ack to a point beyond the max tsn currently sent.
  *
  * We inform the other end by sending an ABORT with a Protocol Violation
  * error code.
  */
 static enum sctp_disposition sctp_sf_violation_ctsn(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     static const char err_str[] = "The cumulative tsn ack beyond the max tsn currently sent:";
 
     return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
                        sizeof(err_str));
 }
 
 /* Handle protocol violation of an invalid chunk bundling.  For example,
  * when we have an association and we receive bundled INIT-ACK, or
  * SHUTDOWN-COMPLETE, our peer is clearly violating the "MUST NOT bundle"
  * statement from the specs.  Additionally, there might be an attacker
  * on the path and we may not want to continue this communication.
  */
 static enum sctp_disposition sctp_sf_violation_chunk(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     static const char err_str[] = "The following chunk violates protocol:";
 
     return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
                        sizeof(err_str));
 }
 /***************************************************************************
  * These are the state functions for handling primitive (Section 10) events.
  ***************************************************************************/
 /*
  * sctp_sf_do_prm_asoc
  *
  * Section: 10.1 ULP-to-SCTP
  * B) Associate
  *
  * Format: ASSOCIATE(local SCTP instance name, destination transport addr,
  * outbound stream count)
  * -> association id [,destination transport addr list] [,outbound stream
  * count]
  *
  * This primitive allows the upper layer to initiate an association to a
  * specific peer endpoint.
  *
  * The peer endpoint shall be specified by one of the transport addresses
  * which defines the endpoint (see Section 1.4).  If the local SCTP
  * instance has not been initialized, the ASSOCIATE is considered an
  * error.
  * [This is not relevant for the kernel implementation since we do all
  * initialization at boot time.  It we hadn't initialized we wouldn't
  * get anywhere near this code.]
  *
  * An association id, which is a local handle to the SCTP association,
  * will be returned on successful establishment of the association. If
  * SCTP is not able to open an SCTP association with the peer endpoint,
  * an error is returned.
  * [In the kernel implementation, the struct sctp_association needs to
  * be created BEFORE causing this primitive to run.]
  *
  * Other association parameters may be returned, including the
  * complete destination transport addresses of the peer as well as the
  * outbound stream count of the local endpoint. One of the transport
  * address from the returned destination addresses will be selected by
  * the local endpoint as default primary path for sending SCTP packets
  * to this peer.  The returned "destination transport addr list" can
  * be used by the ULP to change the default primary path or to force
  * sending a packet to a specific transport address.  [All of this
  * stuff happens when the INIT ACK arrives.  This is a NON-BLOCKING
  * function.]
  *
  * Mandatory attributes:
  *
  * o local SCTP instance name - obtained from the INITIALIZE operation.
  *   [This is the argument asoc.]
  * o destination transport addr - specified as one of the transport
  * addresses of the peer endpoint with which the association is to be
  * established.
  *  [This is asoc->peer.active_path.]
  * o outbound stream count - the number of outbound streams the ULP
  * would like to open towards this peer endpoint.
  * [BUG: This is not currently implemented.]
  * Optional attributes:
  *
  * None.
  *
  * The return value is a disposition.
  */
 enum sctp_disposition sctp_sf_do_prm_asoc(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg,
                       struct sctp_cmd_seq *commands)
 {
     struct sctp_association *my_asoc;
     struct sctp_chunk *repl;
 
     /* The comment below says that we enter COOKIE-WAIT AFTER
      * sending the INIT, but that doesn't actually work in our
      * implementation...
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_COOKIE_WAIT));
 
     /* RFC 2960 5.1 Normal Establishment of an Association
      *
      * A) "A" first sends an INIT chunk to "Z".  In the INIT, "A"
      * must provide its Verification Tag (Tag_A) in the Initiate
      * Tag field.  Tag_A SHOULD be a random number in the range of
      * 1 to 4294967295 (see 5.3.1 for Tag value selection). ...
      */
 
     repl = sctp_make_init(asoc, &asoc->base.bind_addr, GFP_ATOMIC, 0);
     if (!repl)
         goto nomem;
 
     /* Choose transport for INIT. */
     sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
             SCTP_CHUNK(repl));
 
     /* Cast away the const modifier, as we want to just
      * rerun it through as a sideffect.
      */
     my_asoc = (struct sctp_association *)asoc;
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(my_asoc));
 
     /* After sending the INIT, "A" starts the T1-init timer and
      * enters the COOKIE-WAIT state.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Process the SEND primitive.
  *
  * Section: 10.1 ULP-to-SCTP
  * E) Send
  *
  * Format: SEND(association id, buffer address, byte count [,context]
  *         [,stream id] [,life time] [,destination transport address]
  *         [,unorder flag] [,no-bundle flag] [,payload protocol-id] )
  * -> result
  *
  * This is the main method to send user data via SCTP.
  *
  * Mandatory attributes:
  *
  *  o association id - local handle to the SCTP association
  *
  *  o buffer address - the location where the user message to be
  *    transmitted is stored;
  *
  *  o byte count - The size of the user data in number of bytes;
  *
  * Optional attributes:
  *
  *  o context - an optional 32 bit integer that will be carried in the
  *    sending failure notification to the ULP if the transportation of
  *    this User Message fails.
  *
  *  o stream id - to indicate which stream to send the data on. If not
  *    specified, stream 0 will be used.
  *
  *  o life time - specifies the life time of the user data. The user data
  *    will not be sent by SCTP after the life time expires. This
  *    parameter can be used to avoid efforts to transmit stale
  *    user messages. SCTP notifies the ULP if the data cannot be
  *    initiated to transport (i.e. sent to the destination via SCTP's
  *    send primitive) within the life time variable. However, the
  *    user data will be transmitted if SCTP has attempted to transmit a
  *    chunk before the life time expired.
  *
  *  o destination transport address - specified as one of the destination
  *    transport addresses of the peer endpoint to which this packet
  *    should be sent. Whenever possible, SCTP should use this destination
  *    transport address for sending the packets, instead of the current
  *    primary path.
  *
  *  o unorder flag - this flag, if present, indicates that the user
  *    would like the data delivered in an unordered fashion to the peer
  *    (i.e., the U flag is set to 1 on all DATA chunks carrying this
  *    message).
  *
  *  o no-bundle flag - instructs SCTP not to bundle this user data with
  *    other outbound DATA chunks. SCTP MAY still bundle even when
  *    this flag is present, when faced with network congestion.
  *
  *  o payload protocol-id - A 32 bit unsigned integer that is to be
  *    passed to the peer indicating the type of payload protocol data
  *    being transmitted. This value is passed as opaque data by SCTP.
  *
  * The return value is the disposition.
  */
 enum sctp_disposition sctp_sf_do_prm_send(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg,
                       struct sctp_cmd_seq *commands)
 {
     struct sctp_datamsg *msg = arg;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SEND_MSG, SCTP_DATAMSG(msg));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Process the SHUTDOWN primitive.
  *
  * Section: 10.1:
  * C) Shutdown
  *
  * Format: SHUTDOWN(association id)
  * -> result
  *
  * Gracefully closes an association. Any locally queued user data
  * will be delivered to the peer. The association will be terminated only
  * after the peer acknowledges all the SCTP packets sent.  A success code
  * will be returned on successful termination of the association. If
  * attempting to terminate the association results in a failure, an error
  * code shall be returned.
  *
  * Mandatory attributes:
  *
  *  o association id - local handle to the SCTP association
  *
  * Optional attributes:
  *
  * None.
  *
  * The return value is the disposition.
  */
 enum sctp_disposition sctp_sf_do_9_2_prm_shutdown(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     enum sctp_disposition disposition;
 
     /* From 9.2 Shutdown of an Association
      * Upon receipt of the SHUTDOWN primitive from its upper
      * layer, the endpoint enters SHUTDOWN-PENDING state and
      * remains there until all outstanding data has been
      * acknowledged by its peer. The endpoint accepts no new data
      * from its upper layer, but retransmits data to the far end
      * if necessary to fill gaps.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING));
 
     disposition = SCTP_DISPOSITION_CONSUME;
     if (sctp_outq_is_empty(&asoc->outqueue)) {
         disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type,
                                 arg, commands);
     }
 
     return disposition;
 }
 
 /*
  * Process the ABORT primitive.
  *
  * Section: 10.1:
  * C) Abort
  *
  * Format: Abort(association id [, cause code])
  * -> result
  *
  * Ungracefully closes an association. Any locally queued user data
  * will be discarded and an ABORT chunk is sent to the peer.  A success code
  * will be returned on successful abortion of the association. If
  * attempting to abort the association results in a failure, an error
  * code shall be returned.
  *
  * Mandatory attributes:
  *
  *  o association id - local handle to the SCTP association
  *
  * Optional attributes:
  *
  *  o cause code - reason of the abort to be passed to the peer
  *
  * None.
  *
  * The return value is the disposition.
  */
 enum sctp_disposition sctp_sf_do_9_1_prm_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* From 9.1 Abort of an Association
      * Upon receipt of the ABORT primitive from its upper
      * layer, the endpoint enters CLOSED state and
      * discard all outstanding data has been
      * acknowledged by its peer. The endpoint accepts no new data
      * from its upper layer, but retransmits data to the far end
      * if necessary to fill gaps.
      */
     struct sctp_chunk *abort = arg;
 
     if (abort)
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
 
     /* Even if we can't send the ABORT due to low memory delete the
      * TCB.  This is a departure from our typical NOMEM handling.
      */
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
             SCTP_ERROR(ECONNABORTED));
     /* Delete the established association. */
     sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
             SCTP_PERR(SCTP_ERROR_USER_ABORT));
 
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
 
     return SCTP_DISPOSITION_ABORT;
 }
 
 /* We tried an illegal operation on an association which is closed.  */
 enum sctp_disposition sctp_sf_error_closed(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR, SCTP_ERROR(-EINVAL));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* We tried an illegal operation on an association which is shutting
  * down.
  */
 enum sctp_disposition sctp_sf_error_shutdown(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR,
             SCTP_ERROR(-ESHUTDOWN));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * sctp_cookie_wait_prm_shutdown
  *
  * Section: 4 Note: 2
  * Verification Tag:
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explicitly address this issue, but is the route through the
  * state table when someone issues a shutdown while in COOKIE_WAIT state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_cookie_wait_prm_shutdown(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_CLOSED));
 
     SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
 
     sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
 
     return SCTP_DISPOSITION_DELETE_TCB;
 }
 
 /*
  * sctp_cookie_echoed_prm_shutdown
  *
  * Section: 4 Note: 2
  * Verification Tag:
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explicitly address this issue, but is the route through the
  * state table when someone issues a shutdown while in COOKIE_ECHOED state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_cookie_echoed_prm_shutdown(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* There is a single T1 timer, so we should be able to use
      * common function with the COOKIE-WAIT state.
      */
     return sctp_sf_cookie_wait_prm_shutdown(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * sctp_sf_cookie_wait_prm_abort
  *
  * Section: 4 Note: 2
  * Verification Tag:
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explicitly address this issue, but is the route through the
  * state table when someone issues an abort while in COOKIE_WAIT state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_cookie_wait_prm_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *abort = arg;
 
     /* Stop T1-init timer */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
 
     if (abort)
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
 
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_CLOSED));
 
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
 
     /* Even if we can't send the ABORT due to low memory delete the
      * TCB.  This is a departure from our typical NOMEM handling.
      */
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
             SCTP_ERROR(ECONNREFUSED));
     /* Delete the established association. */
     sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
             SCTP_PERR(SCTP_ERROR_USER_ABORT));
 
     return SCTP_DISPOSITION_ABORT;
 }
 
 /*
  * sctp_sf_cookie_echoed_prm_abort
  *
  * Section: 4 Note: 3
  * Verification Tag:
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explcitly address this issue, but is the route through the
  * state table when someone issues an abort while in COOKIE_ECHOED state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_cookie_echoed_prm_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* There is a single T1 timer, so we should be able to use
      * common function with the COOKIE-WAIT state.
      */
     return sctp_sf_cookie_wait_prm_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * sctp_sf_shutdown_pending_prm_abort
  *
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explicitly address this issue, but is the route through the
  * state table when someone issues an abort while in SHUTDOWN-PENDING state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_shutdown_pending_prm_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* Stop the T5-shutdown guard timer.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
 
     return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * sctp_sf_shutdown_sent_prm_abort
  *
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explicitly address this issue, but is the route through the
  * state table when someone issues an abort while in SHUTDOWN-SENT state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_shutdown_sent_prm_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* Stop the T2-shutdown timer.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     /* Stop the T5-shutdown guard timer.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
 
     return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * sctp_sf_cookie_echoed_prm_abort
  *
  * Inputs
  * (endpoint, asoc)
  *
  * The RFC does not explcitly address this issue, but is the route through the
  * state table when someone issues an abort while in COOKIE_ECHOED state.
  *
  * Outputs
  * (timers)
  */
 enum sctp_disposition sctp_sf_shutdown_ack_sent_prm_abort(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     /* The same T2 timer, so we should be able to use
      * common function with the SHUTDOWN-SENT state.
      */
     return sctp_sf_shutdown_sent_prm_abort(net, ep, asoc, type, arg, commands);
 }
 
 /*
  * Process the REQUESTHEARTBEAT primitive
  *
  * 10.1 ULP-to-SCTP
  * J) Request Heartbeat
  *
  * Format: REQUESTHEARTBEAT(association id, destination transport address)
  *
  * -> result
  *
  * Instructs the local endpoint to perform a HeartBeat on the specified
  * destination transport address of the given association. The returned
  * result should indicate whether the transmission of the HEARTBEAT
  * chunk to the destination address is successful.
  *
  * Mandatory attributes:
  *
  * o association id - local handle to the SCTP association
  *
  * o destination transport address - the transport address of the
  *   association on which a heartbeat should be issued.
  */
 enum sctp_disposition sctp_sf_do_prm_requestheartbeat(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type,
                       (struct sctp_transport *)arg, commands))
         return SCTP_DISPOSITION_NOMEM;
 
     /*
      * RFC 2960 (bis), section 8.3
      *
      *    D) Request an on-demand HEARTBEAT on a specific destination
      *    transport address of a given association.
      *
      *    The endpoint should increment the respective error  counter of
      *    the destination transport address each time a HEARTBEAT is sent
      *    to that address and not acknowledged within one RTO.
      *
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT,
             SCTP_TRANSPORT(arg));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * ADDIP Section 4.1 ASCONF Chunk Procedures
  * When an endpoint has an ASCONF signaled change to be sent to the
  * remote endpoint it should do A1 to A9
  */
 enum sctp_disposition sctp_sf_do_prm_asconf(struct net *net,
                         const struct sctp_endpoint *ep,
                         const struct sctp_association *asoc,
                         const union sctp_subtype type,
                         void *arg,
                         struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk));
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* RE-CONFIG Section 5.1 RECONF Chunk Procedures */
 enum sctp_disposition sctp_sf_do_prm_reconf(struct net *net,
                         const struct sctp_endpoint *ep,
                         const struct sctp_association *asoc,
                         const union sctp_subtype type,
                         void *arg,
                         struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk));
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Ignore the primitive event
  *
  * The return value is the disposition of the primitive.
  */
 enum sctp_disposition sctp_sf_ignore_primitive(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     pr_debug("%s: primitive type:%d is ignored\n", __func__,
          type.primitive);
 
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /***************************************************************************
  * These are the state functions for the OTHER events.
  ***************************************************************************/
 
 /*
  * When the SCTP stack has no more user data to send or retransmit, this
  * notification is given to the user. Also, at the time when a user app
  * subscribes to this event, if there is no data to be sent or
  * retransmit, the stack will immediately send up this notification.
  */
 enum sctp_disposition sctp_sf_do_no_pending_tsn(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_ulpevent *event;
 
     event = sctp_ulpevent_make_sender_dry_event(asoc, GFP_ATOMIC);
     if (!event)
         return SCTP_DISPOSITION_NOMEM;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(event));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Start the shutdown negotiation.
  *
  * From Section 9.2:
  * Once all its outstanding data has been acknowledged, the endpoint
  * shall send a SHUTDOWN chunk to its peer including in the Cumulative
  * TSN Ack field the last sequential TSN it has received from the peer.
  * It shall then start the T2-shutdown timer and enter the SHUTDOWN-SENT
  * state. If the timer expires, the endpoint must re-send the SHUTDOWN
  * with the updated last sequential TSN received from its peer.
  *
  * The return value is the disposition.
  */
 enum sctp_disposition sctp_sf_do_9_2_start_shutdown(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *reply;
 
     /* Once all its outstanding data has been acknowledged, the
      * endpoint shall send a SHUTDOWN chunk to its peer including
      * in the Cumulative TSN Ack field the last sequential TSN it
      * has received from the peer.
      */
     reply = sctp_make_shutdown(asoc, arg);
     if (!reply)
         goto nomem;
 
     /* Set the transport for the SHUTDOWN chunk and the timeout for the
      * T2-shutdown timer.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
 
     /* It shall then start the T2-shutdown timer */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     /* RFC 4960 Section 9.2
      * The sender of the SHUTDOWN MAY also start an overall guard timer
      * 'T5-shutdown-guard' to bound the overall time for shutdown sequence.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
 
     if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
 
     /* and enter the SHUTDOWN-SENT state.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_SHUTDOWN_SENT));
 
     /* sctp-implguide 2.10 Issues with Heartbeating and failover
      *
      * HEARTBEAT ... is discontinued after sending either SHUTDOWN
      * or SHUTDOWN-ACK.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
 
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Generate a SHUTDOWN ACK now that everything is SACK'd.
  *
  * From Section 9.2:
  *
  * If it has no more outstanding DATA chunks, the SHUTDOWN receiver
  * shall send a SHUTDOWN ACK and start a T2-shutdown timer of its own,
  * entering the SHUTDOWN-ACK-SENT state. If the timer expires, the
  * endpoint must re-send the SHUTDOWN ACK.
  *
  * The return value is the disposition.
  */
 enum sctp_disposition sctp_sf_do_9_2_shutdown_ack(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = arg;
     struct sctp_chunk *reply;
 
     /* There are 2 ways of getting here:
      *    1) called in response to a SHUTDOWN chunk
      *    2) called when SCTP_EVENT_NO_PENDING_TSN event is issued.
      *
      * For the case (2), the arg parameter is set to NULL.  We need
      * to check that we have a chunk before accessing it's fields.
      */
     if (chunk) {
         if (!sctp_vtag_verify(chunk, asoc))
             return sctp_sf_pdiscard(net, ep, asoc, type, arg,
                         commands);
 
         /* Make sure that the SHUTDOWN chunk has a valid length. */
         if (!sctp_chunk_length_valid(
                 chunk, sizeof(struct sctp_shutdown_chunk)))
             return sctp_sf_violation_chunklen(net, ep, asoc, type,
                               arg, commands);
     }
 
     /* If it has no more outstanding DATA chunks, the SHUTDOWN receiver
      * shall send a SHUTDOWN ACK ...
      */
     reply = sctp_make_shutdown_ack(asoc, chunk);
     if (!reply)
         goto nomem;
 
     /* Set the transport for the SHUTDOWN ACK chunk and the timeout for
      * the T2-shutdown timer.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
 
     /* and start/restart a T2-shutdown timer of its own, */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
 
     if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
 
     /* Enter the SHUTDOWN-ACK-SENT state.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_SHUTDOWN_ACK_SENT));
 
     /* sctp-implguide 2.10 Issues with Heartbeating and failover
      *
      * HEARTBEAT ... is discontinued after sending either SHUTDOWN
      * or SHUTDOWN-ACK.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
 
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * Ignore the event defined as other
  *
  * The return value is the disposition of the event.
  */
 enum sctp_disposition sctp_sf_ignore_other(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     pr_debug("%s: the event other type:%d is ignored\n",
          __func__, type.other);
 
     return SCTP_DISPOSITION_DISCARD;
 }
 
 /************************************************************
  * These are the state functions for handling timeout events.
  ************************************************************/
 
 /*
  * RTX Timeout
  *
  * Section: 6.3.3 Handle T3-rtx Expiration
  *
  * Whenever the retransmission timer T3-rtx expires for a destination
  * address, do the following:
  * [See below]
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     struct sctp_transport *transport = arg;
 
     SCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS);
 
     if (asoc->overall_error_count >= asoc->max_retrans) {
         if (asoc->peer.zero_window_announced &&
             asoc->state == SCTP_STATE_SHUTDOWN_PENDING) {
             /*
              * We are here likely because the receiver had its rwnd
              * closed for a while and we have not been able to
              * transmit the locally queued data within the maximum
              * retransmission attempts limit.  Start the T5
              * shutdown guard timer to give the receiver one last
              * chance and some additional time to recover before
              * aborting.
              */
             sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START_ONCE,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
         } else {
             sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                     SCTP_ERROR(ETIMEDOUT));
             /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
             sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                     SCTP_PERR(SCTP_ERROR_NO_ERROR));
             SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
             SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
             return SCTP_DISPOSITION_DELETE_TCB;
         }
     }
 
     /* E1) For the destination address for which the timer
      * expires, adjust its ssthresh with rules defined in Section
      * 7.2.3 and set the cwnd <- MTU.
      */
 
     /* E2) For the destination address for which the timer
      * expires, set RTO <- RTO * 2 ("back off the timer").  The
      * maximum value discussed in rule C7 above (RTO.max) may be
      * used to provide an upper bound to this doubling operation.
      */
 
     /* E3) Determine how many of the earliest (i.e., lowest TSN)
      * outstanding DATA chunks for the address for which the
      * T3-rtx has expired will fit into a single packet, subject
      * to the MTU constraint for the path corresponding to the
      * destination transport address to which the retransmission
      * is being sent (this may be different from the address for
      * which the timer expires [see Section 6.4]).  Call this
      * value K. Bundle and retransmit those K DATA chunks in a
      * single packet to the destination endpoint.
      *
      * Note: Any DATA chunks that were sent to the address for
      * which the T3-rtx timer expired but did not fit in one MTU
      * (rule E3 above), should be marked for retransmission and
      * sent as soon as cwnd allows (normally when a SACK arrives).
      */
 
     /* Do some failure management (Section 8.2). */
     sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport));
 
     /* NB: Rules E4 and F1 are implicit in R1.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_RETRAN, SCTP_TRANSPORT(transport));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * Generate delayed SACK on timeout
  *
  * Section: 6.2  Acknowledgement on Reception of DATA Chunks
  *
  * The guidelines on delayed acknowledgement algorithm specified in
  * Section 4.2 of [RFC2581] SHOULD be followed.  Specifically, an
  * acknowledgement SHOULD be generated for at least every second packet
  * (not every second DATA chunk) received, and SHOULD be generated
  * within 200 ms of the arrival of any unacknowledged DATA chunk.  In
  * some situations it may be beneficial for an SCTP transmitter to be
  * more conservative than the algorithms detailed in this document
  * allow. However, an SCTP transmitter MUST NOT be more aggressive than
  * the following algorithms allow.
  */
 enum sctp_disposition sctp_sf_do_6_2_sack(struct net *net,
                       const struct sctp_endpoint *ep,
                       const struct sctp_association *asoc,
                       const union sctp_subtype type,
                       void *arg,
                       struct sctp_cmd_seq *commands)
 {
     SCTP_INC_STATS(net, SCTP_MIB_DELAY_SACK_EXPIREDS);
     sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * sctp_sf_t1_init_timer_expire
  *
  * Section: 4 Note: 2
  * Verification Tag:
  * Inputs
  * (endpoint, asoc)
  *
  *  RFC 2960 Section 4 Notes
  *  2) If the T1-init timer expires, the endpoint MUST retransmit INIT
  *     and re-start the T1-init timer without changing state.  This MUST
  *     be repeated up to 'Max.Init.Retransmits' times.  After that, the
  *     endpoint MUST abort the initialization process and report the
  *     error to SCTP user.
  *
  * Outputs
  * (timers, events)
  *
  */
 enum sctp_disposition sctp_sf_t1_init_timer_expire(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     int attempts = asoc->init_err_counter + 1;
     struct sctp_chunk *repl = NULL;
     struct sctp_bind_addr *bp;
 
     pr_debug("%s: timer T1 expired (INIT)\n", __func__);
 
     SCTP_INC_STATS(net, SCTP_MIB_T1_INIT_EXPIREDS);
 
     if (attempts <= asoc->max_init_attempts) {
         bp = (struct sctp_bind_addr *) &asoc->base.bind_addr;
         repl = sctp_make_init(asoc, bp, GFP_ATOMIC, 0);
         if (!repl)
             return SCTP_DISPOSITION_NOMEM;
 
         /* Choose transport for INIT. */
         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
                 SCTP_CHUNK(repl));
 
         /* Issue a sideeffect to do the needed accounting. */
         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_RESTART,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
 
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
     } else {
         pr_debug("%s: giving up on INIT, attempts:%d "
              "max_init_attempts:%d\n", __func__, attempts,
              asoc->max_init_attempts);
 
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
         return SCTP_DISPOSITION_DELETE_TCB;
     }
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /*
  * sctp_sf_t1_cookie_timer_expire
  *
  * Section: 4 Note: 2
  * Verification Tag:
  * Inputs
  * (endpoint, asoc)
  *
  *  RFC 2960 Section 4 Notes
  *  3) If the T1-cookie timer expires, the endpoint MUST retransmit
  *     COOKIE ECHO and re-start the T1-cookie timer without changing
  *     state.  This MUST be repeated up to 'Max.Init.Retransmits' times.
  *     After that, the endpoint MUST abort the initialization process and
  *     report the error to SCTP user.
  *
  * Outputs
  * (timers, events)
  *
  */
 enum sctp_disposition sctp_sf_t1_cookie_timer_expire(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     int attempts = asoc->init_err_counter + 1;
     struct sctp_chunk *repl = NULL;
 
     pr_debug("%s: timer T1 expired (COOKIE-ECHO)\n", __func__);
 
     SCTP_INC_STATS(net, SCTP_MIB_T1_COOKIE_EXPIREDS);
 
     if (attempts <= asoc->max_init_attempts) {
         repl = sctp_make_cookie_echo(asoc, NULL);
         if (!repl)
             return SCTP_DISPOSITION_NOMEM;
 
         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
                 SCTP_CHUNK(repl));
         /* Issue a sideeffect to do the needed accounting. */
         sctp_add_cmd_sf(commands, SCTP_CMD_COOKIEECHO_RESTART,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
 
         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
     } else {
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
         return SCTP_DISPOSITION_DELETE_TCB;
     }
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* RFC2960 9.2 If the timer expires, the endpoint must re-send the SHUTDOWN
  * with the updated last sequential TSN received from its peer.
  *
  * An endpoint should limit the number of retransmission of the
  * SHUTDOWN chunk to the protocol parameter 'Association.Max.Retrans'.
  * If this threshold is exceeded the endpoint should destroy the TCB and
  * MUST report the peer endpoint unreachable to the upper layer (and
  * thus the association enters the CLOSED state).  The reception of any
  * packet from its peer (i.e. as the peer sends all of its queued DATA
  * chunks) should clear the endpoint's retransmission count and restart
  * the T2-Shutdown timer,  giving its peer ample opportunity to transmit
  * all of its queued DATA chunks that have not yet been sent.
  */
 enum sctp_disposition sctp_sf_t2_timer_expire(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *reply = NULL;
 
     pr_debug("%s: timer T2 expired\n", __func__);
 
     SCTP_INC_STATS(net, SCTP_MIB_T2_SHUTDOWN_EXPIREDS);
 
     ((struct sctp_association *)asoc)->shutdown_retries++;
 
     if (asoc->overall_error_count >= asoc->max_retrans) {
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         /* Note:  CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_DISPOSITION_DELETE_TCB;
     }
 
     switch (asoc->state) {
     case SCTP_STATE_SHUTDOWN_SENT:
         reply = sctp_make_shutdown(asoc, NULL);
         break;
 
     case SCTP_STATE_SHUTDOWN_ACK_SENT:
         reply = sctp_make_shutdown_ack(asoc, NULL);
         break;
 
     default:
         BUG();
         break;
     }
 
     if (!reply)
         goto nomem;
 
     /* Do some failure management (Section 8.2).
      * If we remove the transport an SHUTDOWN was last sent to, don't
      * do failure management.
      */
     if (asoc->shutdown_last_sent_to)
         sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
                 SCTP_TRANSPORT(asoc->shutdown_last_sent_to));
 
     /* Set the transport for the SHUTDOWN/ACK chunk and the timeout for
      * the T2-shutdown timer.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
 
     /* Restart the T2-shutdown timer.  */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
     return SCTP_DISPOSITION_CONSUME;
 
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /*
  * ADDIP Section 4.1 ASCONF Chunk Procedures
  * If the T4 RTO timer expires the endpoint should do B1 to B5
  */
 enum sctp_disposition sctp_sf_t4_timer_expire(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *chunk = asoc->addip_last_asconf;
     struct sctp_transport *transport = chunk->transport;
 
     SCTP_INC_STATS(net, SCTP_MIB_T4_RTO_EXPIREDS);
 
     /* ADDIP 4.1 B1) Increment the error counters and perform path failure
      * detection on the appropriate destination address as defined in
      * RFC2960 [5] section 8.1 and 8.2.
      */
     if (transport)
         sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
                 SCTP_TRANSPORT(transport));
 
     /* Reconfig T4 timer and transport. */
     sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk));
 
     /* ADDIP 4.1 B2) Increment the association error counters and perform
      * endpoint failure detection on the association as defined in
      * RFC2960 [5] section 8.1 and 8.2.
      * association error counter is incremented in SCTP_CMD_STRIKE.
      */
     if (asoc->overall_error_count >= asoc->max_retrans) {
         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                 SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ETIMEDOUT));
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_DISPOSITION_ABORT;
     }
 
     /* ADDIP 4.1 B3) Back-off the destination address RTO value to which
      * the ASCONF chunk was sent by doubling the RTO timer value.
      * This is done in SCTP_CMD_STRIKE.
      */
 
     /* ADDIP 4.1 B4) Re-transmit the ASCONF Chunk last sent and if possible
      * choose an alternate destination address (please refer to RFC2960
      * [5] section 6.4.1). An endpoint MUST NOT add new parameters to this
      * chunk, it MUST be the same (including its serial number) as the last
      * ASCONF sent.
      */
     sctp_chunk_hold(asoc->addip_last_asconf);
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
             SCTP_CHUNK(asoc->addip_last_asconf));
 
     /* ADDIP 4.1 B5) Restart the T-4 RTO timer. Note that if a different
      * destination is selected, then the RTO used will be that of the new
      * destination address.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
             SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /* sctpimpguide-05 Section 2.12.2
  * The sender of the SHUTDOWN MAY also start an overall guard timer
  * 'T5-shutdown-guard' to bound the overall time for shutdown sequence.
  * At the expiration of this timer the sender SHOULD abort the association
  * by sending an ABORT chunk.
  */
 enum sctp_disposition sctp_sf_t5_timer_expire(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     struct sctp_chunk *reply = NULL;
 
     pr_debug("%s: timer T5 expired\n", __func__);
 
     SCTP_INC_STATS(net, SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS);
 
     reply = sctp_make_abort(asoc, NULL, 0);
     if (!reply)
         goto nomem;
 
     sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
     sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
             SCTP_ERROR(ETIMEDOUT));
     sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
             SCTP_PERR(SCTP_ERROR_NO_ERROR));
 
     SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
     SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
 
     return SCTP_DISPOSITION_DELETE_TCB;
 nomem:
     return SCTP_DISPOSITION_NOMEM;
 }
 
 /* Handle expiration of AUTOCLOSE timer.  When the autoclose timer expires,
  * the association is automatically closed by starting the shutdown process.
  * The work that needs to be done is same as when SHUTDOWN is initiated by
  * the user.  So this routine looks same as sctp_sf_do_9_2_prm_shutdown().
  */
 enum sctp_disposition sctp_sf_autoclose_timer_expire(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     const union sctp_subtype type,
                     void *arg,
                     struct sctp_cmd_seq *commands)
 {
     enum sctp_disposition disposition;
 
     SCTP_INC_STATS(net, SCTP_MIB_AUTOCLOSE_EXPIREDS);
 
     /* From 9.2 Shutdown of an Association
      * Upon receipt of the SHUTDOWN primitive from its upper
      * layer, the endpoint enters SHUTDOWN-PENDING state and
      * remains there until all outstanding data has been
      * acknowledged by its peer. The endpoint accepts no new data
      * from its upper layer, but retransmits data to the far end
      * if necessary to fill gaps.
      */
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING));
 
     disposition = SCTP_DISPOSITION_CONSUME;
     if (sctp_outq_is_empty(&asoc->outqueue)) {
         disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type,
                                 NULL, commands);
     }
 
     return disposition;
 }
 
 /*****************************************************************************
  * These are sa state functions which could apply to all types of events.
  ****************************************************************************/
 
 /*
  * This table entry is not implemented.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_not_impl(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg, struct sctp_cmd_seq *commands)
 {
     return SCTP_DISPOSITION_NOT_IMPL;
 }
 
 /*
  * This table entry represents a bug.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_bug(struct net *net,
                   const struct sctp_endpoint *ep,
                   const struct sctp_association *asoc,
                   const union sctp_subtype type,
                   void *arg, struct sctp_cmd_seq *commands)
 {
     return SCTP_DISPOSITION_BUG;
 }
 
 /*
  * This table entry represents the firing of a timer in the wrong state.
  * Since timer deletion cannot be guaranteed a timer 'may' end up firing
  * when the association is in the wrong state.   This event should
  * be ignored, so as to prevent any rearming of the timer.
  *
  * Inputs
  * (endpoint, asoc, chunk)
  *
  * The return value is the disposition of the chunk.
  */
 enum sctp_disposition sctp_sf_timer_ignore(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const union sctp_subtype type,
                        void *arg,
                        struct sctp_cmd_seq *commands)
 {
     pr_debug("%s: timer %d ignored\n", __func__, type.chunk);
 
     return SCTP_DISPOSITION_CONSUME;
 }
 
 /********************************************************************
  * 2nd Level Abstractions
  ********************************************************************/
 
 /* Pull the SACK chunk based on the SACK header. */
 static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk)
 {
     struct sctp_sackhdr *sack;
     __u16 num_dup_tsns;
     unsigned int len;
     __u16 num_blocks;
 
     /* Protect ourselves from reading too far into
      * the skb from a bogus sender.
      */
     sack = (struct sctp_sackhdr *) chunk->skb->data;
 
     num_blocks = ntohs(sack->num_gap_ack_blocks);
     num_dup_tsns = ntohs(sack->num_dup_tsns);
     len = sizeof(struct sctp_sackhdr);
     len += (num_blocks + num_dup_tsns) * sizeof(__u32);
     if (len > chunk->skb->len)
         return NULL;
 
     skb_pull(chunk->skb, len);
 
     return sack;
 }
 
 /* Create an ABORT packet to be sent as a response, with the specified
  * error causes.
  */
 static struct sctp_packet *sctp_abort_pkt_new(
                     struct net *net,
                     const struct sctp_endpoint *ep,
                     const struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     const void *payload, size_t paylen)
 {
     struct sctp_packet *packet;
     struct sctp_chunk *abort;
 
     packet = sctp_ootb_pkt_new(net, asoc, chunk);
 
     if (packet) {
         /* Make an ABORT.
          * The T bit will be set if the asoc is NULL.
          */
         abort = sctp_make_abort(asoc, chunk, paylen);
         if (!abort) {
             sctp_ootb_pkt_free(packet);
             return NULL;
         }
 
         /* Reflect vtag if T-Bit is set */
         if (sctp_test_T_bit(abort))
             packet->vtag = ntohl(chunk->sctp_hdr->vtag);
 
         /* Add specified error causes, i.e., payload, to the
          * end of the chunk.
          */
         sctp_addto_chunk(abort, paylen, payload);
 
         /* Set the skb to the belonging sock for accounting.  */
         abort->skb->sk = ep->base.sk;
 
         sctp_packet_append_chunk(packet, abort);
 
     }
 
     return packet;
 }
 
 /* Allocate a packet for responding in the OOTB conditions.  */
 static struct sctp_packet *sctp_ootb_pkt_new(
                     struct net *net,
                     const struct sctp_association *asoc,
                     const struct sctp_chunk *chunk)
 {
     struct sctp_transport *transport;
     struct sctp_packet *packet;
     __u16 sport, dport;
     __u32 vtag;
 
     /* Get the source and destination port from the inbound packet.  */
     sport = ntohs(chunk->sctp_hdr->dest);
     dport = ntohs(chunk->sctp_hdr->source);
 
     /* The V-tag is going to be the same as the inbound packet if no
      * association exists, otherwise, use the peer's vtag.
      */
     if (asoc) {
         /* Special case the INIT-ACK as there is no peer's vtag
          * yet.
          */
         switch (chunk->chunk_hdr->type) {
         case SCTP_CID_INIT:
         case SCTP_CID_INIT_ACK:
         {
             struct sctp_initack_chunk *initack;
 
             initack = (struct sctp_initack_chunk *)chunk->chunk_hdr;
             vtag = ntohl(initack->init_hdr.init_tag);
             break;
         }
         default:
             vtag = asoc->peer.i.init_tag;
             break;
         }
     } else {
         /* Special case the INIT and stale COOKIE_ECHO as there is no
          * vtag yet.
          */
         switch (chunk->chunk_hdr->type) {
         case SCTP_CID_INIT:
         {
             struct sctp_init_chunk *init;
 
             init = (struct sctp_init_chunk *)chunk->chunk_hdr;
             vtag = ntohl(init->init_hdr.init_tag);
             break;
         }
         default:
             vtag = ntohl(chunk->sctp_hdr->vtag);
             break;
         }
     }
 
     /* Make a transport for the bucket, Eliza... */
     transport = sctp_transport_new(net, sctp_source(chunk), GFP_ATOMIC);
     if (!transport)
         goto nomem;
 
     transport->encap_port = SCTP_INPUT_CB(chunk->skb)->encap_port;
 
     /* Cache a route for the transport with the chunk's destination as
      * the source address.
      */
     sctp_transport_route(transport, (union sctp_addr *)&chunk->dest,
                  sctp_sk(net->sctp.ctl_sock));
 
     packet = &transport->packet;
     sctp_packet_init(packet, transport, sport, dport);
     sctp_packet_config(packet, vtag, 0);
 
     return packet;
 
 nomem:
     return NULL;
 }
 
 /* Free the packet allocated earlier for responding in the OOTB condition.  */
 void sctp_ootb_pkt_free(struct sctp_packet *packet)
 {
     sctp_transport_free(packet->transport);
 }
 
 /* Send a stale cookie error when a invalid COOKIE ECHO chunk is found  */
 static void sctp_send_stale_cookie_err(struct net *net,
                        const struct sctp_endpoint *ep,
                        const struct sctp_association *asoc,
                        const struct sctp_chunk *chunk,
                        struct sctp_cmd_seq *commands,
                        struct sctp_chunk *err_chunk)
 {
     struct sctp_packet *packet;
 
     if (err_chunk) {
         packet = sctp_ootb_pkt_new(net, asoc, chunk);
         if (packet) {
             struct sctp_signed_cookie *cookie;
 
             /* Override the OOTB vtag from the cookie. */
             cookie = chunk->subh.cookie_hdr;
             packet->vtag = cookie->c.peer_vtag;
 
             /* Set the skb to the belonging sock for accounting. */
             err_chunk->skb->sk = ep->base.sk;
             sctp_packet_append_chunk(packet, err_chunk);
             sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
                     SCTP_PACKET(packet));
             SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
         } else
             sctp_chunk_free (err_chunk);
     }
 }
 
 
 /* Process a data chunk */
 static int sctp_eat_data(const struct sctp_association *asoc,
              struct sctp_chunk *chunk,
              struct sctp_cmd_seq *commands)
 {
     struct sctp_tsnmap *map = (struct sctp_tsnmap *)&asoc->peer.tsn_map;
     struct sock *sk = asoc->base.sk;
     struct net *net = sock_net(sk);
     struct sctp_datahdr *data_hdr;
     struct sctp_chunk *err;
     enum sctp_verb deliver;
     size_t datalen;
     __u32 tsn;
     int tmp;
 
     data_hdr = (struct sctp_datahdr *)chunk->skb->data;
     chunk->subh.data_hdr = data_hdr;
     skb_pull(chunk->skb, sctp_datahdr_len(&asoc->stream));
 
     tsn = ntohl(data_hdr->tsn);
     pr_debug("%s: TSN 0x%x\n", __func__, tsn);
 
     /* ASSERT:  Now skb->data is really the user data.  */
 
     /* Process ECN based congestion.
      *
      * Since the chunk structure is reused for all chunks within
      * a packet, we use ecn_ce_done to track if we've already
      * done CE processing for this packet.
      *
      * We need to do ECN processing even if we plan to discard the
      * chunk later.
      */
 
     if (asoc->peer.ecn_capable && !chunk->ecn_ce_done) {
         struct sctp_af *af = SCTP_INPUT_CB(chunk->skb)->af;
         chunk->ecn_ce_done = 1;
 
         if (af->is_ce(sctp_gso_headskb(chunk->skb))) {
             /* Do real work as side effect. */
             sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE,
                     SCTP_U32(tsn));
         }
     }
 
     tmp = sctp_tsnmap_check(&asoc->peer.tsn_map, tsn);
     if (tmp < 0) {
         /* The TSN is too high--silently discard the chunk and
          * count on it getting retransmitted later.
          */
         if (chunk->asoc)
             chunk->asoc->stats.outofseqtsns++;
         return SCTP_IERROR_HIGH_TSN;
     } else if (tmp > 0) {
         /* This is a duplicate.  Record it.  */
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_DUP, SCTP_U32(tsn));
         return SCTP_IERROR_DUP_TSN;
     }
 
     /* This is a new TSN.  */
 
     /* Discard if there is no room in the receive window.
      * Actually, allow a little bit of overflow (up to a MTU).
      */
     datalen = ntohs(chunk->chunk_hdr->length);
     datalen -= sctp_datachk_len(&asoc->stream);
 
     deliver = SCTP_CMD_CHUNK_ULP;
 
     /* Think about partial delivery. */
     if ((datalen >= asoc->rwnd) && (!asoc->ulpq.pd_mode)) {
 
         /* Even if we don't accept this chunk there is
          * memory pressure.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_PART_DELIVER, SCTP_NULL());
     }
 
     /* Spill over rwnd a little bit.  Note: While allowed, this spill over
      * seems a bit troublesome in that frag_point varies based on
      * PMTU.  In cases, such as loopback, this might be a rather
      * large spill over.
      */
     if ((!chunk->data_accepted) && (!asoc->rwnd || asoc->rwnd_over ||
         (datalen > asoc->rwnd + asoc->frag_point))) {
 
         /* If this is the next TSN, consider reneging to make
          * room.   Note: Playing nice with a confused sender.  A
          * malicious sender can still eat up all our buffer
          * space and in the future we may want to detect and
          * do more drastic reneging.
          */
         if (sctp_tsnmap_has_gap(map) &&
             (sctp_tsnmap_get_ctsn(map) + 1) == tsn) {
             pr_debug("%s: reneging for tsn:%u\n", __func__, tsn);
             deliver = SCTP_CMD_RENEGE;
         } else {
             pr_debug("%s: discard tsn:%u len:%zu, rwnd:%d\n",
                  __func__, tsn, datalen, asoc->rwnd);
 
             return SCTP_IERROR_IGNORE_TSN;
         }
     }
 
     /*
      * Also try to renege to limit our memory usage in the event that
      * we are under memory pressure
      * If we can't renege, don't worry about it, the sk_rmem_schedule
      * in sctp_ulpevent_make_rcvmsg will drop the frame if we grow our
      * memory usage too much
      */
     if (sk_under_memory_pressure(sk)) {
         if (sctp_tsnmap_has_gap(map) &&
             (sctp_tsnmap_get_ctsn(map) + 1) == tsn) {
             pr_debug("%s: under pressure, reneging for tsn:%u\n",
                  __func__, tsn);
             deliver = SCTP_CMD_RENEGE;
         }
     }
 
     /*
      * Section 3.3.10.9 No User Data (9)
      *
      * Cause of error
      * ---------------
      * No User Data:  This error cause is returned to the originator of a
      * DATA chunk if a received DATA chunk has no user data.
      */
     if (unlikely(0 == datalen)) {
         err = sctp_make_abort_no_data(asoc, chunk, tsn);
         if (err) {
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(err));
         }
         /* We are going to ABORT, so we might as well stop
          * processing the rest of the chunks in the packet.
          */
         sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
                 SCTP_ERROR(ECONNABORTED));
         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
                 SCTP_PERR(SCTP_ERROR_NO_DATA));
         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
         return SCTP_IERROR_NO_DATA;
     }
 
     chunk->data_accepted = 1;
 
     /* Note: Some chunks may get overcounted (if we drop) or overcounted
      * if we renege and the chunk arrives again.
      */
     if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) {
         SCTP_INC_STATS(net, SCTP_MIB_INUNORDERCHUNKS);
         if (chunk->asoc)
             chunk->asoc->stats.iuodchunks++;
     } else {
         SCTP_INC_STATS(net, SCTP_MIB_INORDERCHUNKS);
         if (chunk->asoc)
             chunk->asoc->stats.iodchunks++;
     }
 
     /* RFC 2960 6.5 Stream Identifier and Stream Sequence Number
      *
      * If an endpoint receive a DATA chunk with an invalid stream
      * identifier, it shall acknowledge the reception of the DATA chunk
      * following the normal procedure, immediately send an ERROR chunk
      * with cause set to "Invalid Stream Identifier" (See Section 3.3.10)
      * and discard the DATA chunk.
      */
     if (ntohs(data_hdr->stream) >= asoc->stream.incnt) {
         /* Mark tsn as received even though we drop it */
         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_TSN, SCTP_U32(tsn));
 
         err = sctp_make_op_error(asoc, chunk, SCTP_ERROR_INV_STRM,
                      &data_hdr->stream,
                      sizeof(data_hdr->stream),
                      sizeof(u16));
         if (err)
             sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                     SCTP_CHUNK(err));
         return SCTP_IERROR_BAD_STREAM;
     }
 
     /* Check to see if the SSN is possible for this TSN.
      * The biggest gap we can record is 4K wide.  Since SSNs wrap
      * at an unsigned short, there is no way that an SSN can
      * wrap and for a valid TSN.  We can simply check if the current
      * SSN is smaller then the next expected one.  If it is, it wrapped
      * and is invalid.
      */
     if (!asoc->stream.si->validate_data(chunk))
         return SCTP_IERROR_PROTO_VIOLATION;
 
     /* Send the data up to the user.  Note:  Schedule  the
      * SCTP_CMD_CHUNK_ULP cmd before the SCTP_CMD_GEN_SACK, as the SACK
      * chunk needs the updated rwnd.
      */
     sctp_add_cmd_sf(commands, deliver, SCTP_CHUNK(chunk));
 
     return SCTP_IERROR_NO_ERROR;
 }