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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
  * Copyright (c) 1999-2000 Cisco, Inc.
  * Copyright (c) 1999-2001 Motorola, Inc.
  * Copyright (c) 2001-2003 International Business Machines, Corp.
  * Copyright (c) 2001 Intel Corp.
  * Copyright (c) 2001 Nokia, Inc.
  * Copyright (c) 2001 La Monte H.P. Yarroll
  *
  * This file is part of the SCTP kernel implementation
  *
  * These functions handle all input from the IP layer into SCTP.
  *
  * 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>
  *    Xingang Guo <xingang.guo@intel.com>
  *    Jon Grimm <jgrimm@us.ibm.com>
  *    Hui Huang <hui.huang@nokia.com>
  *    Daisy Chang <daisyc@us.ibm.com>
  *    Sridhar Samudrala <sri@us.ibm.com>
  *    Ardelle Fan <ardelle.fan@intel.com>
  */
 
 #include <linux/types.h>
 #include <linux/list.h> /* For struct list_head */
 #include <linux/socket.h>
 #include <linux/ip.h>
 #include <linux/time.h> /* For struct timeval */
 #include <linux/slab.h>
 #include <net/ip.h>
 #include <net/icmp.h>
 #include <net/snmp.h>
 #include <net/sock.h>
 #include <net/xfrm.h>
 #include <net/sctp/sctp.h>
 #include <net/sctp/sm.h>
 #include <net/sctp/checksum.h>
 #include <net/net_namespace.h>
 #include <linux/rhashtable.h>
 #include <net/sock_reuseport.h>
 
 /* Forward declarations for internal helpers. */
 static int sctp_rcv_ootb(struct sk_buff *);
 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
                       struct sk_buff *skb,
                       const union sctp_addr *paddr,
                       const union sctp_addr *laddr,
                       struct sctp_transport **transportp);
 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
                     struct net *net, struct sk_buff *skb,
                     const union sctp_addr *laddr,
                     const union sctp_addr *daddr);
 static struct sctp_association *__sctp_lookup_association(
                     struct net *net,
                     const union sctp_addr *local,
                     const union sctp_addr *peer,
                     struct sctp_transport **pt);
 
 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
 
 
 /* Calculate the SCTP checksum of an SCTP packet.  */
 static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
 {
     struct sctphdr *sh = sctp_hdr(skb);
     __le32 cmp = sh->checksum;
     __le32 val = sctp_compute_cksum(skb, 0);
 
     if (val != cmp) {
         /* CRC failure, dump it. */
         __SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
         return -1;
     }
     return 0;
 }
 
 /*
  * This is the routine which IP calls when receiving an SCTP packet.
  */
 int sctp_rcv(struct sk_buff *skb)
 {
     struct sock *sk;
     struct sctp_association *asoc;
     struct sctp_endpoint *ep = NULL;
     struct sctp_ep_common *rcvr;
     struct sctp_transport *transport = NULL;
     struct sctp_chunk *chunk;
     union sctp_addr src;
     union sctp_addr dest;
     int bound_dev_if;
     int family;
     struct sctp_af *af;
     struct net *net = dev_net(skb->dev);
     bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb);
 
     if (skb->pkt_type != PACKET_HOST)
         goto discard_it;
 
     __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
 
     /* If packet is too small to contain a single chunk, let's not
      * waste time on it anymore.
      */
     if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) +
                skb_transport_offset(skb))
         goto discard_it;
 
     /* If the packet is fragmented and we need to do crc checking,
      * it's better to just linearize it otherwise crc computing
      * takes longer.
      */
     if ((!is_gso && skb_linearize(skb)) ||
         !pskb_may_pull(skb, sizeof(struct sctphdr)))
         goto discard_it;
 
     /* Pull up the IP header. */
     __skb_pull(skb, skb_transport_offset(skb));
 
     skb->csum_valid = 0; /* Previous value not applicable */
     if (skb_csum_unnecessary(skb))
         __skb_decr_checksum_unnecessary(skb);
     else if (!sctp_checksum_disable &&
          !is_gso &&
          sctp_rcv_checksum(net, skb) < 0)
         goto discard_it;
     skb->csum_valid = 1;
 
     __skb_pull(skb, sizeof(struct sctphdr));
 
     family = ipver2af(ip_hdr(skb)->version);
     af = sctp_get_af_specific(family);
     if (unlikely(!af))
         goto discard_it;
     SCTP_INPUT_CB(skb)->af = af;
 
     /* Initialize local addresses for lookups. */
     af->from_skb(&src, skb, 1);
     af->from_skb(&dest, skb, 0);
 
     /* If the packet is to or from a non-unicast address,
      * silently discard the packet.
      *
      * This is not clearly defined in the RFC except in section
      * 8.4 - OOTB handling.  However, based on the book "Stream Control
      * Transmission Protocol" 2.1, "It is important to note that the
      * IP address of an SCTP transport address must be a routable
      * unicast address.  In other words, IP multicast addresses and
      * IP broadcast addresses cannot be used in an SCTP transport
      * address."
      */
     if (!af->addr_valid(&src, NULL, skb) ||
         !af->addr_valid(&dest, NULL, skb))
         goto discard_it;
 
     asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
 
     if (!asoc)
         ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src);
 
     /* Retrieve the common input handling substructure. */
     rcvr = asoc ? &asoc->base : &ep->base;
     sk = rcvr->sk;
 
     /*
      * If a frame arrives on an interface and the receiving socket is
      * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
      */
     bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
     if (bound_dev_if && (bound_dev_if != af->skb_iif(skb))) {
         if (transport) {
             sctp_transport_put(transport);
             asoc = NULL;
             transport = NULL;
         } else {
             sctp_endpoint_put(ep);
             ep = NULL;
         }
         sk = net->sctp.ctl_sock;
         ep = sctp_sk(sk)->ep;
         sctp_endpoint_hold(ep);
         rcvr = &ep->base;
     }
 
     /*
      * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
      * An SCTP packet is called an "out of the blue" (OOTB)
      * packet if it is correctly formed, i.e., passed the
      * receiver's checksum check, but the receiver is not
      * able to identify the association to which this
      * packet belongs.
      */
     if (!asoc) {
         if (sctp_rcv_ootb(skb)) {
             __SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
             goto discard_release;
         }
     }
 
     if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
         goto discard_release;
     nf_reset_ct(skb);
 
     if (sk_filter(sk, skb))
         goto discard_release;
 
     /* Create an SCTP packet structure. */
     chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
     if (!chunk)
         goto discard_release;
     SCTP_INPUT_CB(skb)->chunk = chunk;
 
     /* Remember what endpoint is to handle this packet. */
     chunk->rcvr = rcvr;
 
     /* Remember the SCTP header. */
     chunk->sctp_hdr = sctp_hdr(skb);
 
     /* Set the source and destination addresses of the incoming chunk.  */
     sctp_init_addrs(chunk, &src, &dest);
 
     /* Remember where we came from.  */
     chunk->transport = transport;
 
     /* Acquire access to the sock lock. Note: We are safe from other
      * bottom halves on this lock, but a user may be in the lock too,
      * so check if it is busy.
      */
     bh_lock_sock(sk);
 
     if (sk != rcvr->sk) {
         /* Our cached sk is different from the rcvr->sk.  This is
          * because migrate()/accept() may have moved the association
          * to a new socket and released all the sockets.  So now we
          * are holding a lock on the old socket while the user may
          * be doing something with the new socket.  Switch our veiw
          * of the current sk.
          */
         bh_unlock_sock(sk);
         sk = rcvr->sk;
         bh_lock_sock(sk);
     }
 
     if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
         if (sctp_add_backlog(sk, skb)) {
             bh_unlock_sock(sk);
             sctp_chunk_free(chunk);
             skb = NULL; /* sctp_chunk_free already freed the skb */
             goto discard_release;
         }
         __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG);
     } else {
         __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ);
         sctp_inq_push(&chunk->rcvr->inqueue, chunk);
     }
 
     bh_unlock_sock(sk);
 
     /* Release the asoc/ep ref we took in the lookup calls. */
     if (transport)
         sctp_transport_put(transport);
     else
         sctp_endpoint_put(ep);
 
     return 0;
 
 discard_it:
     __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
     kfree_skb(skb);
     return 0;
 
 discard_release:
     /* Release the asoc/ep ref we took in the lookup calls. */
     if (transport)
         sctp_transport_put(transport);
     else
         sctp_endpoint_put(ep);
 
     goto discard_it;
 }
 
 /* Process the backlog queue of the socket.  Every skb on
  * the backlog holds a ref on an association or endpoint.
  * We hold this ref throughout the state machine to make
  * sure that the structure we need is still around.
  */
 int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 {
     struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
     struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
     struct sctp_transport *t = chunk->transport;
     struct sctp_ep_common *rcvr = NULL;
     int backloged = 0;
 
     rcvr = chunk->rcvr;
 
     /* If the rcvr is dead then the association or endpoint
      * has been deleted and we can safely drop the chunk
      * and refs that we are holding.
      */
     if (rcvr->dead) {
         sctp_chunk_free(chunk);
         goto done;
     }
 
     if (unlikely(rcvr->sk != sk)) {
         /* In this case, the association moved from one socket to
          * another.  We are currently sitting on the backlog of the
          * old socket, so we need to move.
          * However, since we are here in the process context we
          * need to take make sure that the user doesn't own
          * the new socket when we process the packet.
          * If the new socket is user-owned, queue the chunk to the
          * backlog of the new socket without dropping any refs.
          * Otherwise, we can safely push the chunk on the inqueue.
          */
 
         sk = rcvr->sk;
         local_bh_disable();
         bh_lock_sock(sk);
 
         if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
             if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
                 sctp_chunk_free(chunk);
             else
                 backloged = 1;
         } else
             sctp_inq_push(inqueue, chunk);
 
         bh_unlock_sock(sk);
         local_bh_enable();
 
         /* If the chunk was backloged again, don't drop refs */
         if (backloged)
             return 0;
     } else {
         if (!sctp_newsk_ready(sk)) {
             if (!sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
                 return 0;
             sctp_chunk_free(chunk);
         } else {
             sctp_inq_push(inqueue, chunk);
         }
     }
 
 done:
     /* Release the refs we took in sctp_add_backlog */
     if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
         sctp_transport_put(t);
     else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
         sctp_endpoint_put(sctp_ep(rcvr));
     else
         BUG();
 
     return 0;
 }
 
 static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
 {
     struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
     struct sctp_transport *t = chunk->transport;
     struct sctp_ep_common *rcvr = chunk->rcvr;
     int ret;
 
     ret = sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
     if (!ret) {
         /* Hold the assoc/ep while hanging on the backlog queue.
          * This way, we know structures we need will not disappear
          * from us
          */
         if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
             sctp_transport_hold(t);
         else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
             sctp_endpoint_hold(sctp_ep(rcvr));
         else
             BUG();
     }
     return ret;
 
 }
 
 /* Handle icmp frag needed error. */
 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
                struct sctp_transport *t, __u32 pmtu)
 {
     if (!t ||
         (t->pathmtu <= pmtu &&
          t->pl.probe_size + sctp_transport_pl_hlen(t) <= pmtu))
         return;
 
     if (sock_owned_by_user(sk)) {
         atomic_set(&t->mtu_info, pmtu);
         asoc->pmtu_pending = 1;
         t->pmtu_pending = 1;
         return;
     }
 
     if (!(t->param_flags & SPP_PMTUD_ENABLE))
         /* We can't allow retransmitting in such case, as the
          * retransmission would be sized just as before, and thus we
          * would get another icmp, and retransmit again.
          */
         return;
 
     /* Update transports view of the MTU. Return if no update was needed.
      * If an update wasn't needed/possible, it also doesn't make sense to
      * try to retransmit now.
      */
     if (!sctp_transport_update_pmtu(t, pmtu))
         return;
 
     /* Update association pmtu. */
     sctp_assoc_sync_pmtu(asoc);
 
     /* Retransmit with the new pmtu setting. */
     sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 }
 
 void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
             struct sk_buff *skb)
 {
     struct dst_entry *dst;
 
     if (sock_owned_by_user(sk) || !t)
         return;
     dst = sctp_transport_dst_check(t);
     if (dst)
         dst->ops->redirect(dst, sk, skb);
 }
 
 /*
  * SCTP Implementer's Guide, 2.37 ICMP handling procedures
  *
  * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
  *        or a "Protocol Unreachable" treat this message as an abort
  *        with the T bit set.
  *
  * This function sends an event to the state machine, which will abort the
  * association.
  *
  */
 void sctp_icmp_proto_unreachable(struct sock *sk,
                struct sctp_association *asoc,
                struct sctp_transport *t)
 {
     if (sock_owned_by_user(sk)) {
         if (timer_pending(&t->proto_unreach_timer))
             return;
         else {
             if (!mod_timer(&t->proto_unreach_timer,
                         jiffies + (HZ/20)))
                 sctp_transport_hold(t);
         }
     } else {
         struct net *net = sock_net(sk);
 
         pr_debug("%s: unrecognized next header type "
              "encountered!\n", __func__);
 
         if (del_timer(&t->proto_unreach_timer))
             sctp_transport_put(t);
 
         sctp_do_sm(net, SCTP_EVENT_T_OTHER,
                SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
                asoc->state, asoc->ep, asoc, t,
                GFP_ATOMIC);
     }
 }
 
 /* Common lookup code for icmp/icmpv6 error handler. */
 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
                  struct sctphdr *sctphdr,
                  struct sctp_association **app,
                  struct sctp_transport **tpp)
 {
     struct sctp_init_chunk *chunkhdr, _chunkhdr;
     union sctp_addr saddr;
     union sctp_addr daddr;
     struct sctp_af *af;
     struct sock *sk = NULL;
     struct sctp_association *asoc;
     struct sctp_transport *transport = NULL;
     __u32 vtag = ntohl(sctphdr->vtag);
 
     *app = NULL; *tpp = NULL;
 
     af = sctp_get_af_specific(family);
     if (unlikely(!af)) {
         return NULL;
     }
 
     /* Initialize local addresses for lookups. */
     af->from_skb(&saddr, skb, 1);
     af->from_skb(&daddr, skb, 0);
 
     /* Look for an association that matches the incoming ICMP error
      * packet.
      */
     asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
     if (!asoc)
         return NULL;
 
     sk = asoc->base.sk;
 
     /* RFC 4960, Appendix C. ICMP Handling
      *
      * ICMP6) An implementation MUST validate that the Verification Tag
      * contained in the ICMP message matches the Verification Tag of
      * the peer.  If the Verification Tag is not 0 and does NOT
      * match, discard the ICMP message.  If it is 0 and the ICMP
      * message contains enough bytes to verify that the chunk type is
      * an INIT chunk and that the Initiate Tag matches the tag of the
      * peer, continue with ICMP7.  If the ICMP message is too short
      * or the chunk type or the Initiate Tag does not match, silently
      * discard the packet.
      */
     if (vtag == 0) {
         /* chunk header + first 4 octects of init header */
         chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
                           sizeof(struct sctphdr),
                           sizeof(struct sctp_chunkhdr) +
                           sizeof(__be32), &_chunkhdr);
         if (!chunkhdr ||
             chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
             ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
             goto out;
 
     } else if (vtag != asoc->c.peer_vtag) {
         goto out;
     }
 
     bh_lock_sock(sk);
 
     /* If too many ICMPs get dropped on busy
      * servers this needs to be solved differently.
      */
     if (sock_owned_by_user(sk))
         __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
 
     *app = asoc;
     *tpp = transport;
     return sk;
 
 out:
     sctp_transport_put(transport);
     return NULL;
 }
 
 /* Common cleanup code for icmp/icmpv6 error handler. */
 void sctp_err_finish(struct sock *sk, struct sctp_transport *t)
     __releases(&((__sk)->sk_lock.slock))
 {
     bh_unlock_sock(sk);
     sctp_transport_put(t);
 }
 
 static void sctp_v4_err_handle(struct sctp_transport *t, struct sk_buff *skb,
                    __u8 type, __u8 code, __u32 info)
 {
     struct sctp_association *asoc = t->asoc;
     struct sock *sk = asoc->base.sk;
     int err = 0;
 
     switch (type) {
     case ICMP_PARAMETERPROB:
         err = EPROTO;
         break;
     case ICMP_DEST_UNREACH:
         if (code > NR_ICMP_UNREACH)
             return;
         if (code == ICMP_FRAG_NEEDED) {
             sctp_icmp_frag_needed(sk, asoc, t, SCTP_TRUNC4(info));
             return;
         }
         if (code == ICMP_PROT_UNREACH) {
             sctp_icmp_proto_unreachable(sk, asoc, t);
             return;
         }
         err = icmp_err_convert[code].errno;
         break;
     case ICMP_TIME_EXCEEDED:
         if (code == ICMP_EXC_FRAGTIME)
             return;
 
         err = EHOSTUNREACH;
         break;
     case ICMP_REDIRECT:
         sctp_icmp_redirect(sk, t, skb);
         return;
     default:
         return;
     }
     if (!sock_owned_by_user(sk) && inet_sk(sk)->recverr) {
         sk->sk_err = err;
         sk_error_report(sk);
     } else {  /* Only an error on timeout */
         sk->sk_err_soft = err;
     }
 }
 
 /*
  * This routine is called by the ICMP module when it gets some
  * sort of error condition.  If err < 0 then the socket should
  * be closed and the error returned to the user.  If err > 0
  * it's just the icmp type << 8 | icmp code.  After adjustment
  * header points to the first 8 bytes of the sctp header.  We need
  * to find the appropriate port.
  *
  * The locking strategy used here is very "optimistic". When
  * someone else accesses the socket the ICMP is just dropped
  * and for some paths there is no check at all.
  * A more general error queue to queue errors for later handling
  * is probably better.
  *
  */
 int sctp_v4_err(struct sk_buff *skb, __u32 info)
 {
     const struct iphdr *iph = (const struct iphdr *)skb->data;
     const int type = icmp_hdr(skb)->type;
     const int code = icmp_hdr(skb)->code;
     struct net *net = dev_net(skb->dev);
     struct sctp_transport *transport;
     struct sctp_association *asoc;
     __u16 saveip, savesctp;
     struct sock *sk;
 
     /* Fix up skb to look at the embedded net header. */
     saveip = skb->network_header;
     savesctp = skb->transport_header;
     skb_reset_network_header(skb);
     skb_set_transport_header(skb, iph->ihl * 4);
     sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
     /* Put back, the original values. */
     skb->network_header = saveip;
     skb->transport_header = savesctp;
     if (!sk) {
         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
         return -ENOENT;
     }
 
     sctp_v4_err_handle(transport, skb, type, code, info);
     sctp_err_finish(sk, transport);
 
     return 0;
 }
 
 int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb)
 {
     struct net *net = dev_net(skb->dev);
     struct sctp_association *asoc;
     struct sctp_transport *t;
     struct icmphdr *hdr;
     __u32 info = 0;
 
     skb->transport_header += sizeof(struct udphdr);
     sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &t);
     if (!sk) {
         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
         return -ENOENT;
     }
 
     skb->transport_header -= sizeof(struct udphdr);
     hdr = (struct icmphdr *)(skb_network_header(skb) - sizeof(struct icmphdr));
     if (hdr->type == ICMP_REDIRECT) {
         /* can't be handled without outer iphdr known, leave it to udp_err */
         sctp_err_finish(sk, t);
         return 0;
     }
     if (hdr->type == ICMP_DEST_UNREACH && hdr->code == ICMP_FRAG_NEEDED)
         info = ntohs(hdr->un.frag.mtu);
     sctp_v4_err_handle(t, skb, hdr->type, hdr->code, info);
 
     sctp_err_finish(sk, t);
     return 1;
 }
 
 /*
  * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
  *
  * This function scans all the chunks in the OOTB packet to determine if
  * the packet should be discarded right away.  If a response might be needed
  * for this packet, or, if further processing is possible, the packet will
  * be queued to a proper inqueue for the next phase of handling.
  *
  * Output:
  * Return 0 - If further processing is needed.
  * Return 1 - If the packet can be discarded right away.
  */
 static int sctp_rcv_ootb(struct sk_buff *skb)
 {
     struct sctp_chunkhdr *ch, _ch;
     int ch_end, offset = 0;
 
     /* Scan through all the chunks in the packet.  */
     do {
         /* Make sure we have at least the header there */
         if (offset + sizeof(_ch) > skb->len)
             break;
 
         ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch);
 
         /* Break out if chunk length is less then minimal. */
         if (!ch || ntohs(ch->length) < sizeof(_ch))
             break;
 
         ch_end = offset + SCTP_PAD4(ntohs(ch->length));
         if (ch_end > skb->len)
             break;
 
         /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
          * receiver MUST silently discard the OOTB packet and take no
          * further action.
          */
         if (SCTP_CID_ABORT == ch->type)
             goto discard;
 
         /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
          * chunk, the receiver should silently discard the packet
          * and take no further action.
          */
         if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
             goto discard;
 
         /* RFC 4460, 2.11.2
          * This will discard packets with INIT chunk bundled as
          * subsequent chunks in the packet.  When INIT is first,
          * the normal INIT processing will discard the chunk.
          */
         if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
             goto discard;
 
         offset = ch_end;
     } while (ch_end < skb->len);
 
     return 0;
 
 discard:
     return 1;
 }
 
 /* Insert endpoint into the hash table.  */
 static int __sctp_hash_endpoint(struct sctp_endpoint *ep)
 {
     struct sock *sk = ep->base.sk;
     struct net *net = sock_net(sk);
     struct sctp_hashbucket *head;
 
     ep->hashent = sctp_ep_hashfn(net, ep->base.bind_addr.port);
     head = &sctp_ep_hashtable[ep->hashent];
 
     if (sk->sk_reuseport) {
         bool any = sctp_is_ep_boundall(sk);
         struct sctp_endpoint *ep2;
         struct list_head *list;
         int cnt = 0, err = 1;
 
         list_for_each(list, &ep->base.bind_addr.address_list)
             cnt++;
 
         sctp_for_each_hentry(ep2, &head->chain) {
             struct sock *sk2 = ep2->base.sk;
 
             if (!net_eq(sock_net(sk2), net) || sk2 == sk ||
                 !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) ||
                 !sk2->sk_reuseport)
                 continue;
 
             err = sctp_bind_addrs_check(sctp_sk(sk2),
                             sctp_sk(sk), cnt);
             if (!err) {
                 err = reuseport_add_sock(sk, sk2, any);
                 if (err)
                     return err;
                 break;
             } else if (err < 0) {
                 return err;
             }
         }
 
         if (err) {
             err = reuseport_alloc(sk, any);
             if (err)
                 return err;
         }
     }
 
     write_lock(&head->lock);
     hlist_add_head(&ep->node, &head->chain);
     write_unlock(&head->lock);
     return 0;
 }
 
 /* Add an endpoint to the hash. Local BH-safe. */
 int sctp_hash_endpoint(struct sctp_endpoint *ep)
 {
     int err;
 
     local_bh_disable();
     err = __sctp_hash_endpoint(ep);
     local_bh_enable();
 
     return err;
 }
 
 /* Remove endpoint from the hash table.  */
 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
 {
     struct sock *sk = ep->base.sk;
     struct sctp_hashbucket *head;
 
     ep->hashent = sctp_ep_hashfn(sock_net(sk), ep->base.bind_addr.port);
 
     head = &sctp_ep_hashtable[ep->hashent];
 
     if (rcu_access_pointer(sk->sk_reuseport_cb))
         reuseport_detach_sock(sk);
 
     write_lock(&head->lock);
     hlist_del_init(&ep->node);
     write_unlock(&head->lock);
 }
 
 /* Remove endpoint from the hash.  Local BH-safe. */
 void sctp_unhash_endpoint(struct sctp_endpoint *ep)
 {
     local_bh_disable();
     __sctp_unhash_endpoint(ep);
     local_bh_enable();
 }
 
 static inline __u32 sctp_hashfn(const struct net *net, __be16 lport,
                 const union sctp_addr *paddr, __u32 seed)
 {
     __u32 addr;
 
     if (paddr->sa.sa_family == AF_INET6)
         addr = jhash(&paddr->v6.sin6_addr, 16, seed);
     else
         addr = (__force __u32)paddr->v4.sin_addr.s_addr;
 
     return  jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
                  (__force __u32)lport, net_hash_mix(net), seed);
 }
 
 /* Look up an endpoint. */
 static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
                     struct net *net, struct sk_buff *skb,
                     const union sctp_addr *laddr,
                     const union sctp_addr *paddr)
 {
     struct sctp_hashbucket *head;
     struct sctp_endpoint *ep;
     struct sock *sk;
     __be16 lport;
     int hash;
 
     lport = laddr->v4.sin_port;
     hash = sctp_ep_hashfn(net, ntohs(lport));
     head = &sctp_ep_hashtable[hash];
     read_lock(&head->lock);
     sctp_for_each_hentry(ep, &head->chain) {
         if (sctp_endpoint_is_match(ep, net, laddr))
             goto hit;
     }
 
     ep = sctp_sk(net->sctp.ctl_sock)->ep;
 
 hit:
     sk = ep->base.sk;
     if (sk->sk_reuseport) {
         __u32 phash = sctp_hashfn(net, lport, paddr, 0);
 
         sk = reuseport_select_sock(sk, phash, skb,
                        sizeof(struct sctphdr));
         if (sk)
             ep = sctp_sk(sk)->ep;
     }
     sctp_endpoint_hold(ep);
     read_unlock(&head->lock);
     return ep;
 }
 
 /* rhashtable for transport */
 struct sctp_hash_cmp_arg {
     const union sctp_addr   *paddr;
     const struct net    *net;
     __be16          lport;
 };
 
 static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
                 const void *ptr)
 {
     struct sctp_transport *t = (struct sctp_transport *)ptr;
     const struct sctp_hash_cmp_arg *x = arg->key;
     int err = 1;
 
     if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
         return err;
     if (!sctp_transport_hold(t))
         return err;
 
     if (!net_eq(t->asoc->base.net, x->net))
         goto out;
     if (x->lport != htons(t->asoc->base.bind_addr.port))
         goto out;
 
     err = 0;
 out:
     sctp_transport_put(t);
     return err;
 }
 
 static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
 {
     const struct sctp_transport *t = data;
 
     return sctp_hashfn(t->asoc->base.net,
                htons(t->asoc->base.bind_addr.port),
                &t->ipaddr, seed);
 }
 
 static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed)
 {
     const struct sctp_hash_cmp_arg *x = data;
 
     return sctp_hashfn(x->net, x->lport, x->paddr, seed);
 }
 
 static const struct rhashtable_params sctp_hash_params = {
     .head_offset        = offsetof(struct sctp_transport, node),
     .hashfn         = sctp_hash_key,
     .obj_hashfn     = sctp_hash_obj,
     .obj_cmpfn      = sctp_hash_cmp,
     .automatic_shrinking    = true,
 };
 
 int sctp_transport_hashtable_init(void)
 {
     return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params);
 }
 
 void sctp_transport_hashtable_destroy(void)
 {
     rhltable_destroy(&sctp_transport_hashtable);
 }
 
 int sctp_hash_transport(struct sctp_transport *t)
 {
     struct sctp_transport *transport;
     struct rhlist_head *tmp, *list;
     struct sctp_hash_cmp_arg arg;
     int err;
 
     if (t->asoc->temp)
         return 0;
 
     arg.net   = t->asoc->base.net;
     arg.paddr = &t->ipaddr;
     arg.lport = htons(t->asoc->base.bind_addr.port);
 
     rcu_read_lock();
     list = rhltable_lookup(&sctp_transport_hashtable, &arg,
                    sctp_hash_params);
 
     rhl_for_each_entry_rcu(transport, tmp, list, node)
         if (transport->asoc->ep == t->asoc->ep) {
             rcu_read_unlock();
             return -EEXIST;
         }
     rcu_read_unlock();
 
     err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
                   &t->node, sctp_hash_params);
     if (err)
         pr_err_once("insert transport fail, errno %d\n", err);
 
     return err;
 }
 
 void sctp_unhash_transport(struct sctp_transport *t)
 {
     if (t->asoc->temp)
         return;
 
     rhltable_remove(&sctp_transport_hashtable, &t->node,
             sctp_hash_params);
 }
 
 /* return a transport with holding it */
 struct sctp_transport *sctp_addrs_lookup_transport(
                 struct net *net,
                 const union sctp_addr *laddr,
                 const union sctp_addr *paddr)
 {
     struct rhlist_head *tmp, *list;
     struct sctp_transport *t;
     struct sctp_hash_cmp_arg arg = {
         .paddr = paddr,
         .net   = net,
         .lport = laddr->v4.sin_port,
     };
 
     list = rhltable_lookup(&sctp_transport_hashtable, &arg,
                    sctp_hash_params);
 
     rhl_for_each_entry_rcu(t, tmp, list, node) {
         if (!sctp_transport_hold(t))
             continue;
 
         if (sctp_bind_addr_match(&t->asoc->base.bind_addr,
                      laddr, sctp_sk(t->asoc->base.sk)))
             return t;
         sctp_transport_put(t);
     }
 
     return NULL;
 }
 
 /* return a transport without holding it, as it's only used under sock lock */
 struct sctp_transport *sctp_epaddr_lookup_transport(
                 const struct sctp_endpoint *ep,
                 const union sctp_addr *paddr)
 {
     struct rhlist_head *tmp, *list;
     struct sctp_transport *t;
     struct sctp_hash_cmp_arg arg = {
         .paddr = paddr,
         .net   = ep->base.net,
         .lport = htons(ep->base.bind_addr.port),
     };
 
     list = rhltable_lookup(&sctp_transport_hashtable, &arg,
                    sctp_hash_params);
 
     rhl_for_each_entry_rcu(t, tmp, list, node)
         if (ep == t->asoc->ep)
             return t;
 
     return NULL;
 }
 
 /* Look up an association. */
 static struct sctp_association *__sctp_lookup_association(
                     struct net *net,
                     const union sctp_addr *local,
                     const union sctp_addr *peer,
                     struct sctp_transport **pt)
 {
     struct sctp_transport *t;
     struct sctp_association *asoc = NULL;
 
     t = sctp_addrs_lookup_transport(net, local, peer);
     if (!t)
         goto out;
 
     asoc = t->asoc;
     *pt = t;
 
 out:
     return asoc;
 }
 
 /* Look up an association. protected by RCU read lock */
 static
 struct sctp_association *sctp_lookup_association(struct net *net,
                          const union sctp_addr *laddr,
                          const union sctp_addr *paddr,
                          struct sctp_transport **transportp)
 {
     struct sctp_association *asoc;
 
     rcu_read_lock();
     asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
     rcu_read_unlock();
 
     return asoc;
 }
 
 /* Is there an association matching the given local and peer addresses? */
 bool sctp_has_association(struct net *net,
               const union sctp_addr *laddr,
               const union sctp_addr *paddr)
 {
     struct sctp_transport *transport;
 
     if (sctp_lookup_association(net, laddr, paddr, &transport)) {
         sctp_transport_put(transport);
         return true;
     }
 
     return false;
 }
 
 /*
  * SCTP Implementors Guide, 2.18 Handling of address
  * parameters within the INIT or INIT-ACK.
  *
  * D) When searching for a matching TCB upon reception of an INIT
  *    or INIT-ACK chunk the receiver SHOULD use not only the
  *    source address of the packet (containing the INIT or
  *    INIT-ACK) but the receiver SHOULD also use all valid
  *    address parameters contained within the chunk.
  *
  * 2.18.3 Solution description
  *
  * This new text clearly specifies to an implementor the need
  * to look within the INIT or INIT-ACK. Any implementation that
  * does not do this, may not be able to establish associations
  * in certain circumstances.
  *
  */
 static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
     struct sk_buff *skb,
     const union sctp_addr *laddr, struct sctp_transport **transportp)
 {
     struct sctp_association *asoc;
     union sctp_addr addr;
     union sctp_addr *paddr = &addr;
     struct sctphdr *sh = sctp_hdr(skb);
     union sctp_params params;
     struct sctp_init_chunk *init;
     struct sctp_af *af;
 
     /*
      * This code will NOT touch anything inside the chunk--it is
      * strictly READ-ONLY.
      *
      * RFC 2960 3  SCTP packet Format
      *
      * Multiple chunks can be bundled into one SCTP packet up to
      * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
      * COMPLETE chunks.  These chunks MUST NOT be bundled with any
      * other chunk in a packet.  See Section 6.10 for more details
      * on chunk bundling.
      */
 
     /* Find the start of the TLVs and the end of the chunk.  This is
      * the region we search for address parameters.
      */
     init = (struct sctp_init_chunk *)skb->data;
 
     /* Walk the parameters looking for embedded addresses. */
     sctp_walk_params(params, init, init_hdr.params) {
 
         /* Note: Ignoring hostname addresses. */
         af = sctp_get_af_specific(param_type2af(params.p->type));
         if (!af)
             continue;
 
         if (!af->from_addr_param(paddr, params.addr, sh->source, 0))
             continue;
 
         asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
         if (asoc)
             return asoc;
     }
 
     return NULL;
 }
 
 /* ADD-IP, Section 5.2
  * When an endpoint receives an ASCONF Chunk from the remote peer
  * special procedures may be needed to identify the association the
  * ASCONF Chunk is associated with. To properly find the association
  * the following procedures SHOULD be followed:
  *
  * D2) If the association is not found, use the address found in the
  * Address Parameter TLV combined with the port number found in the
  * SCTP common header. If found proceed to rule D4.
  *
  * D2-ext) If more than one ASCONF Chunks are packed together, use the
  * address found in the ASCONF Address Parameter TLV of each of the
  * subsequent ASCONF Chunks. If found, proceed to rule D4.
  */
 static struct sctp_association *__sctp_rcv_asconf_lookup(
                     struct net *net,
                     struct sctp_chunkhdr *ch,
                     const union sctp_addr *laddr,
                     __be16 peer_port,
                     struct sctp_transport **transportp)
 {
     struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch;
     struct sctp_af *af;
     union sctp_addr_param *param;
     union sctp_addr paddr;
 
     if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr))
         return NULL;
 
     /* Skip over the ADDIP header and find the Address parameter */
     param = (union sctp_addr_param *)(asconf + 1);
 
     af = sctp_get_af_specific(param_type2af(param->p.type));
     if (unlikely(!af))
         return NULL;
 
     if (!af->from_addr_param(&paddr, param, peer_port, 0))
         return NULL;
 
     return __sctp_lookup_association(net, laddr, &paddr, transportp);
 }
 
 
 /* SCTP-AUTH, Section 6.3:
 *    If the receiver does not find a STCB for a packet containing an AUTH
 *    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
 *    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
 *    association.
 *
 * This means that any chunks that can help us identify the association need
 * to be looked at to find this association.
 */
 static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
                       struct sk_buff *skb,
                       const union sctp_addr *laddr,
                       struct sctp_transport **transportp)
 {
     struct sctp_association *asoc = NULL;
     struct sctp_chunkhdr *ch;
     int have_auth = 0;
     unsigned int chunk_num = 1;
     __u8 *ch_end;
 
     /* Walk through the chunks looking for AUTH or ASCONF chunks
      * to help us find the association.
      */
     ch = (struct sctp_chunkhdr *)skb->data;
     do {
         /* Break out if chunk length is less then minimal. */
         if (ntohs(ch->length) < sizeof(*ch))
             break;
 
         ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
         if (ch_end > skb_tail_pointer(skb))
             break;
 
         switch (ch->type) {
         case SCTP_CID_AUTH:
             have_auth = chunk_num;
             break;
 
         case SCTP_CID_COOKIE_ECHO:
             /* If a packet arrives containing an AUTH chunk as
              * a first chunk, a COOKIE-ECHO chunk as the second
              * chunk, and possibly more chunks after them, and
              * the receiver does not have an STCB for that
              * packet, then authentication is based on
              * the contents of the COOKIE- ECHO chunk.
              */
             if (have_auth == 1 && chunk_num == 2)
                 return NULL;
             break;
 
         case SCTP_CID_ASCONF:
             if (have_auth || net->sctp.addip_noauth)
                 asoc = __sctp_rcv_asconf_lookup(
                         net, ch, laddr,
                         sctp_hdr(skb)->source,
                         transportp);
             break;
         default:
             break;
         }
 
         if (asoc)
             break;
 
         ch = (struct sctp_chunkhdr *)ch_end;
         chunk_num++;
     } while (ch_end + sizeof(*ch) < skb_tail_pointer(skb));
 
     return asoc;
 }
 
 /*
  * There are circumstances when we need to look inside the SCTP packet
  * for information to help us find the association.   Examples
  * include looking inside of INIT/INIT-ACK chunks or after the AUTH
  * chunks.
  */
 static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
                       struct sk_buff *skb,
                       const union sctp_addr *laddr,
                       struct sctp_transport **transportp)
 {
     struct sctp_chunkhdr *ch;
 
     /* We do not allow GSO frames here as we need to linearize and
      * then cannot guarantee frame boundaries. This shouldn't be an
      * issue as packets hitting this are mostly INIT or INIT-ACK and
      * those cannot be on GSO-style anyway.
      */
     if (skb_is_gso(skb) && skb_is_gso_sctp(skb))
         return NULL;
 
     ch = (struct sctp_chunkhdr *)skb->data;
 
     /* The code below will attempt to walk the chunk and extract
      * parameter information.  Before we do that, we need to verify
      * that the chunk length doesn't cause overflow.  Otherwise, we'll
      * walk off the end.
      */
     if (SCTP_PAD4(ntohs(ch->length)) > skb->len)
         return NULL;
 
     /* If this is INIT/INIT-ACK look inside the chunk too. */
     if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
         return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
 
     return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
 }
 
 /* Lookup an association for an inbound skb. */
 static struct sctp_association *__sctp_rcv_lookup(struct net *net,
                       struct sk_buff *skb,
                       const union sctp_addr *paddr,
                       const union sctp_addr *laddr,
                       struct sctp_transport **transportp)
 {
     struct sctp_association *asoc;
 
     asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
     if (asoc)
         goto out;
 
     /* Further lookup for INIT/INIT-ACK packets.
      * SCTP Implementors Guide, 2.18 Handling of address
      * parameters within the INIT or INIT-ACK.
      */
     asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
     if (asoc)
         goto out;
 
     if (paddr->sa.sa_family == AF_INET)
         pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n",
              &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port),
              &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port));
     else
         pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n",
              &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port),
              &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port));
 
 out:
     return asoc;
 }

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