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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Generic HDLC support routines for Linux
0004  * Point-to-point protocol support
0005  *
0006  * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
0007  */
0008 
0009 #include <linux/errno.h>
0010 #include <linux/hdlc.h>
0011 #include <linux/if_arp.h>
0012 #include <linux/inetdevice.h>
0013 #include <linux/init.h>
0014 #include <linux/kernel.h>
0015 #include <linux/module.h>
0016 #include <linux/pkt_sched.h>
0017 #include <linux/poll.h>
0018 #include <linux/skbuff.h>
0019 #include <linux/slab.h>
0020 #include <linux/spinlock.h>
0021 
0022 #define DEBUG_CP        0 /* also bytes# to dump */
0023 #define DEBUG_STATE     0
0024 #define DEBUG_HARD_HEADER   0
0025 
0026 #define HDLC_ADDR_ALLSTATIONS   0xFF
0027 #define HDLC_CTRL_UI        0x03
0028 
0029 #define PID_LCP         0xC021
0030 #define PID_IP          0x0021
0031 #define PID_IPCP        0x8021
0032 #define PID_IPV6        0x0057
0033 #define PID_IPV6CP      0x8057
0034 
0035 enum {IDX_LCP = 0, IDX_IPCP, IDX_IPV6CP, IDX_COUNT};
0036 enum {CP_CONF_REQ = 1, CP_CONF_ACK, CP_CONF_NAK, CP_CONF_REJ, CP_TERM_REQ,
0037       CP_TERM_ACK, CP_CODE_REJ, LCP_PROTO_REJ, LCP_ECHO_REQ, LCP_ECHO_REPLY,
0038       LCP_DISC_REQ, CP_CODES};
0039 #if DEBUG_CP
0040 static const char *const code_names[CP_CODES] = {
0041     "0", "ConfReq", "ConfAck", "ConfNak", "ConfRej", "TermReq",
0042     "TermAck", "CodeRej", "ProtoRej", "EchoReq", "EchoReply", "Discard"
0043 };
0044 
0045 static char debug_buffer[64 + 3 * DEBUG_CP];
0046 #endif
0047 
0048 enum {LCP_OPTION_MRU = 1, LCP_OPTION_ACCM, LCP_OPTION_MAGIC = 5};
0049 
0050 struct hdlc_header {
0051     u8 address;
0052     u8 control;
0053     __be16 protocol;
0054 };
0055 
0056 struct cp_header {
0057     u8 code;
0058     u8 id;
0059     __be16 len;
0060 };
0061 
0062 struct proto {
0063     struct net_device *dev;
0064     struct timer_list timer;
0065     unsigned long timeout;
0066     u16 pid;        /* protocol ID */
0067     u8 state;
0068     u8 cr_id;       /* ID of last Configuration-Request */
0069     u8 restart_counter;
0070 };
0071 
0072 struct ppp {
0073     struct proto protos[IDX_COUNT];
0074     spinlock_t lock;
0075     unsigned long last_pong;
0076     unsigned int req_timeout, cr_retries, term_retries;
0077     unsigned int keepalive_interval, keepalive_timeout;
0078     u8 seq;         /* local sequence number for requests */
0079     u8 echo_id;     /* ID of last Echo-Request (LCP) */
0080 };
0081 
0082 enum {CLOSED = 0, STOPPED, STOPPING, REQ_SENT, ACK_RECV, ACK_SENT, OPENED,
0083       STATES, STATE_MASK = 0xF};
0084 enum {START = 0, STOP, TO_GOOD, TO_BAD, RCR_GOOD, RCR_BAD, RCA, RCN, RTR, RTA,
0085       RUC, RXJ_GOOD, RXJ_BAD, EVENTS};
0086 enum {INV = 0x10, IRC = 0x20, ZRC = 0x40, SCR = 0x80, SCA = 0x100,
0087       SCN = 0x200, STR = 0x400, STA = 0x800, SCJ = 0x1000};
0088 
0089 #if DEBUG_STATE
0090 static const char *const state_names[STATES] = {
0091     "Closed", "Stopped", "Stopping", "ReqSent", "AckRecv", "AckSent",
0092     "Opened"
0093 };
0094 
0095 static const char *const event_names[EVENTS] = {
0096     "Start", "Stop", "TO+", "TO-", "RCR+", "RCR-", "RCA", "RCN",
0097     "RTR", "RTA", "RUC", "RXJ+", "RXJ-"
0098 };
0099 #endif
0100 
0101 static struct sk_buff_head tx_queue; /* used when holding the spin lock */
0102 
0103 static int ppp_ioctl(struct net_device *dev, struct if_settings *ifs);
0104 
0105 static inline struct ppp *get_ppp(struct net_device *dev)
0106 {
0107     return (struct ppp *)dev_to_hdlc(dev)->state;
0108 }
0109 
0110 static inline struct proto *get_proto(struct net_device *dev, u16 pid)
0111 {
0112     struct ppp *ppp = get_ppp(dev);
0113 
0114     switch (pid) {
0115     case PID_LCP:
0116         return &ppp->protos[IDX_LCP];
0117     case PID_IPCP:
0118         return &ppp->protos[IDX_IPCP];
0119     case PID_IPV6CP:
0120         return &ppp->protos[IDX_IPV6CP];
0121     default:
0122         return NULL;
0123     }
0124 }
0125 
0126 static inline const char *proto_name(u16 pid)
0127 {
0128     switch (pid) {
0129     case PID_LCP:
0130         return "LCP";
0131     case PID_IPCP:
0132         return "IPCP";
0133     case PID_IPV6CP:
0134         return "IPV6CP";
0135     default:
0136         return NULL;
0137     }
0138 }
0139 
0140 static __be16 ppp_type_trans(struct sk_buff *skb, struct net_device *dev)
0141 {
0142     struct hdlc_header *data = (struct hdlc_header *)skb->data;
0143 
0144     if (skb->len < sizeof(struct hdlc_header))
0145         return htons(ETH_P_HDLC);
0146     if (data->address != HDLC_ADDR_ALLSTATIONS ||
0147         data->control != HDLC_CTRL_UI)
0148         return htons(ETH_P_HDLC);
0149 
0150     switch (data->protocol) {
0151     case cpu_to_be16(PID_IP):
0152         skb_pull(skb, sizeof(struct hdlc_header));
0153         return htons(ETH_P_IP);
0154 
0155     case cpu_to_be16(PID_IPV6):
0156         skb_pull(skb, sizeof(struct hdlc_header));
0157         return htons(ETH_P_IPV6);
0158 
0159     default:
0160         return htons(ETH_P_HDLC);
0161     }
0162 }
0163 
0164 static int ppp_hard_header(struct sk_buff *skb, struct net_device *dev,
0165                u16 type, const void *daddr, const void *saddr,
0166                unsigned int len)
0167 {
0168     struct hdlc_header *data;
0169 #if DEBUG_HARD_HEADER
0170     printk(KERN_DEBUG "%s: ppp_hard_header() called\n", dev->name);
0171 #endif
0172 
0173     skb_push(skb, sizeof(struct hdlc_header));
0174     data = (struct hdlc_header *)skb->data;
0175 
0176     data->address = HDLC_ADDR_ALLSTATIONS;
0177     data->control = HDLC_CTRL_UI;
0178     switch (type) {
0179     case ETH_P_IP:
0180         data->protocol = htons(PID_IP);
0181         break;
0182     case ETH_P_IPV6:
0183         data->protocol = htons(PID_IPV6);
0184         break;
0185     case PID_LCP:
0186     case PID_IPCP:
0187     case PID_IPV6CP:
0188         data->protocol = htons(type);
0189         break;
0190     default:        /* unknown protocol */
0191         data->protocol = 0;
0192     }
0193     return sizeof(struct hdlc_header);
0194 }
0195 
0196 static void ppp_tx_flush(void)
0197 {
0198     struct sk_buff *skb;
0199 
0200     while ((skb = skb_dequeue(&tx_queue)) != NULL)
0201         dev_queue_xmit(skb);
0202 }
0203 
0204 static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,
0205               u8 id, unsigned int len, const void *data)
0206 {
0207     struct sk_buff *skb;
0208     struct cp_header *cp;
0209     unsigned int magic_len = 0;
0210     static u32 magic;
0211 
0212 #if DEBUG_CP
0213     int i;
0214     char *ptr;
0215 #endif
0216 
0217     if (pid == PID_LCP && (code == LCP_ECHO_REQ || code == LCP_ECHO_REPLY))
0218         magic_len = sizeof(magic);
0219 
0220     skb = dev_alloc_skb(sizeof(struct hdlc_header) +
0221                 sizeof(struct cp_header) + magic_len + len);
0222     if (!skb)
0223         return;
0224 
0225     skb_reserve(skb, sizeof(struct hdlc_header));
0226 
0227     cp = skb_put(skb, sizeof(struct cp_header));
0228     cp->code = code;
0229     cp->id = id;
0230     cp->len = htons(sizeof(struct cp_header) + magic_len + len);
0231 
0232     if (magic_len)
0233         skb_put_data(skb, &magic, magic_len);
0234     if (len)
0235         skb_put_data(skb, data, len);
0236 
0237 #if DEBUG_CP
0238     BUG_ON(code >= CP_CODES);
0239     ptr = debug_buffer;
0240     *ptr = '\x0';
0241     for (i = 0; i < min_t(unsigned int, magic_len + len, DEBUG_CP); i++) {
0242         sprintf(ptr, " %02X", skb->data[sizeof(struct cp_header) + i]);
0243         ptr += strlen(ptr);
0244     }
0245     printk(KERN_DEBUG "%s: TX %s [%s id 0x%X]%s\n", dev->name,
0246            proto_name(pid), code_names[code], id, debug_buffer);
0247 #endif
0248 
0249     ppp_hard_header(skb, dev, pid, NULL, NULL, 0);
0250 
0251     skb->priority = TC_PRIO_CONTROL;
0252     skb->dev = dev;
0253     skb->protocol = htons(ETH_P_HDLC);
0254     skb_reset_network_header(skb);
0255     skb_queue_tail(&tx_queue, skb);
0256 }
0257 
0258 /* State transition table (compare STD-51)
0259    Events                                   Actions
0260    TO+  = Timeout with counter > 0          irc = Initialize-Restart-Count
0261    TO-  = Timeout with counter expired      zrc = Zero-Restart-Count
0262 
0263    RCR+ = Receive-Configure-Request (Good)  scr = Send-Configure-Request
0264    RCR- = Receive-Configure-Request (Bad)
0265    RCA  = Receive-Configure-Ack             sca = Send-Configure-Ack
0266    RCN  = Receive-Configure-Nak/Rej         scn = Send-Configure-Nak/Rej
0267 
0268    RTR  = Receive-Terminate-Request         str = Send-Terminate-Request
0269    RTA  = Receive-Terminate-Ack             sta = Send-Terminate-Ack
0270 
0271    RUC  = Receive-Unknown-Code              scj = Send-Code-Reject
0272    RXJ+ = Receive-Code-Reject (permitted)
0273        or Receive-Protocol-Reject
0274    RXJ- = Receive-Code-Reject (catastrophic)
0275        or Receive-Protocol-Reject
0276 */
0277 static int cp_table[EVENTS][STATES] = {
0278     /* CLOSED     STOPPED STOPPING REQ_SENT ACK_RECV ACK_SENT OPENED
0279          0           1         2       3       4      5          6    */
0280     {IRC|SCR|3,     INV     , INV ,   INV   , INV ,  INV    ,   INV   }, /* START */
0281     {   INV   ,      0      ,  0  ,    0    ,  0  ,   0     ,    0    }, /* STOP */
0282     {   INV   ,     INV     ,STR|2,  SCR|3  ,SCR|3,  SCR|5  ,   INV   }, /* TO+ */
0283     {   INV   ,     INV     ,  1  ,    1    ,  1  ,    1    ,   INV   }, /* TO- */
0284     {  STA|0  ,IRC|SCR|SCA|5,  2  ,  SCA|5  ,SCA|6,  SCA|5  ,SCR|SCA|5}, /* RCR+ */
0285     {  STA|0  ,IRC|SCR|SCN|3,  2  ,  SCN|3  ,SCN|4,  SCN|3  ,SCR|SCN|3}, /* RCR- */
0286     {  STA|0  ,    STA|1    ,  2  ,  IRC|4  ,SCR|3,    6    , SCR|3   }, /* RCA */
0287     {  STA|0  ,    STA|1    ,  2  ,IRC|SCR|3,SCR|3,IRC|SCR|5, SCR|3   }, /* RCN */
0288     {  STA|0  ,    STA|1    ,STA|2,  STA|3  ,STA|3,  STA|3  ,ZRC|STA|2}, /* RTR */
0289     {    0    ,      1      ,  1  ,    3    ,  3  ,    5    ,  SCR|3  }, /* RTA */
0290     {  SCJ|0  ,    SCJ|1    ,SCJ|2,  SCJ|3  ,SCJ|4,  SCJ|5  ,  SCJ|6  }, /* RUC */
0291     {    0    ,      1      ,  2  ,    3    ,  3  ,    5    ,    6    }, /* RXJ+ */
0292     {    0    ,      1      ,  1  ,    1    ,  1  ,    1    ,IRC|STR|2}, /* RXJ- */
0293 };
0294 
0295 /* SCA: RCR+ must supply id, len and data
0296    SCN: RCR- must supply code, id, len and data
0297    STA: RTR must supply id
0298    SCJ: RUC must supply CP packet len and data */
0299 static void ppp_cp_event(struct net_device *dev, u16 pid, u16 event, u8 code,
0300              u8 id, unsigned int len, const void *data)
0301 {
0302     int old_state, action;
0303     struct ppp *ppp = get_ppp(dev);
0304     struct proto *proto = get_proto(dev, pid);
0305 
0306     old_state = proto->state;
0307     BUG_ON(old_state >= STATES);
0308     BUG_ON(event >= EVENTS);
0309 
0310 #if DEBUG_STATE
0311     printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) %s ...\n", dev->name,
0312            proto_name(pid), event_names[event], state_names[proto->state]);
0313 #endif
0314 
0315     action = cp_table[event][old_state];
0316 
0317     proto->state = action & STATE_MASK;
0318     if (action & (SCR | STR)) /* set Configure-Req/Terminate-Req timer */
0319         mod_timer(&proto->timer, proto->timeout =
0320               jiffies + ppp->req_timeout * HZ);
0321     if (action & ZRC)
0322         proto->restart_counter = 0;
0323     if (action & IRC)
0324         proto->restart_counter = (proto->state == STOPPING) ?
0325             ppp->term_retries : ppp->cr_retries;
0326 
0327     if (action & SCR)   /* send Configure-Request */
0328         ppp_tx_cp(dev, pid, CP_CONF_REQ, proto->cr_id = ++ppp->seq,
0329               0, NULL);
0330     if (action & SCA)   /* send Configure-Ack */
0331         ppp_tx_cp(dev, pid, CP_CONF_ACK, id, len, data);
0332     if (action & SCN)   /* send Configure-Nak/Reject */
0333         ppp_tx_cp(dev, pid, code, id, len, data);
0334     if (action & STR)   /* send Terminate-Request */
0335         ppp_tx_cp(dev, pid, CP_TERM_REQ, ++ppp->seq, 0, NULL);
0336     if (action & STA)   /* send Terminate-Ack */
0337         ppp_tx_cp(dev, pid, CP_TERM_ACK, id, 0, NULL);
0338     if (action & SCJ)   /* send Code-Reject */
0339         ppp_tx_cp(dev, pid, CP_CODE_REJ, ++ppp->seq, len, data);
0340 
0341     if (old_state != OPENED && proto->state == OPENED) {
0342         netdev_info(dev, "%s up\n", proto_name(pid));
0343         if (pid == PID_LCP) {
0344             netif_dormant_off(dev);
0345             ppp_cp_event(dev, PID_IPCP, START, 0, 0, 0, NULL);
0346             ppp_cp_event(dev, PID_IPV6CP, START, 0, 0, 0, NULL);
0347             ppp->last_pong = jiffies;
0348             mod_timer(&proto->timer, proto->timeout =
0349                   jiffies + ppp->keepalive_interval * HZ);
0350         }
0351     }
0352     if (old_state == OPENED && proto->state != OPENED) {
0353         netdev_info(dev, "%s down\n", proto_name(pid));
0354         if (pid == PID_LCP) {
0355             netif_dormant_on(dev);
0356             ppp_cp_event(dev, PID_IPCP, STOP, 0, 0, 0, NULL);
0357             ppp_cp_event(dev, PID_IPV6CP, STOP, 0, 0, 0, NULL);
0358         }
0359     }
0360     if (old_state != CLOSED && proto->state == CLOSED)
0361         del_timer(&proto->timer);
0362 
0363 #if DEBUG_STATE
0364     printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) ... %s\n", dev->name,
0365            proto_name(pid), event_names[event], state_names[proto->state]);
0366 #endif
0367 }
0368 
0369 static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id,
0370                 unsigned int req_len, const u8 *data)
0371 {
0372     static u8 const valid_accm[6] = { LCP_OPTION_ACCM, 6, 0, 0, 0, 0 };
0373     const u8 *opt;
0374     u8 *out;
0375     unsigned int len = req_len, nak_len = 0, rej_len = 0;
0376 
0377     out = kmalloc(len, GFP_ATOMIC);
0378     if (!out) {
0379         dev->stats.rx_dropped++;
0380         return; /* out of memory, ignore CR packet */
0381     }
0382 
0383     for (opt = data; len; len -= opt[1], opt += opt[1]) {
0384         if (len < 2 || opt[1] < 2 || len < opt[1])
0385             goto err_out;
0386 
0387         if (pid == PID_LCP)
0388             switch (opt[0]) {
0389             case LCP_OPTION_MRU:
0390                 continue; /* MRU always OK and > 1500 bytes? */
0391 
0392             case LCP_OPTION_ACCM: /* async control character map */
0393                 if (opt[1] < sizeof(valid_accm))
0394                     goto err_out;
0395                 if (!memcmp(opt, valid_accm,
0396                         sizeof(valid_accm)))
0397                     continue;
0398                 if (!rej_len) { /* NAK it */
0399                     memcpy(out + nak_len, valid_accm,
0400                            sizeof(valid_accm));
0401                     nak_len += sizeof(valid_accm);
0402                     continue;
0403                 }
0404                 break;
0405             case LCP_OPTION_MAGIC:
0406                 if (len < 6)
0407                     goto err_out;
0408                 if (opt[1] != 6 || (!opt[2] && !opt[3] &&
0409                             !opt[4] && !opt[5]))
0410                     break; /* reject invalid magic number */
0411                 continue;
0412             }
0413         /* reject this option */
0414         memcpy(out + rej_len, opt, opt[1]);
0415         rej_len += opt[1];
0416     }
0417 
0418     if (rej_len)
0419         ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_REJ, id, rej_len, out);
0420     else if (nak_len)
0421         ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_NAK, id, nak_len, out);
0422     else
0423         ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data);
0424 
0425     kfree(out);
0426     return;
0427 
0428 err_out:
0429     dev->stats.rx_errors++;
0430     kfree(out);
0431 }
0432 
0433 static int ppp_rx(struct sk_buff *skb)
0434 {
0435     struct hdlc_header *hdr = (struct hdlc_header *)skb->data;
0436     struct net_device *dev = skb->dev;
0437     struct ppp *ppp = get_ppp(dev);
0438     struct proto *proto;
0439     struct cp_header *cp;
0440     unsigned long flags;
0441     unsigned int len;
0442     u16 pid;
0443 #if DEBUG_CP
0444     int i;
0445     char *ptr;
0446 #endif
0447 
0448     spin_lock_irqsave(&ppp->lock, flags);
0449     /* Check HDLC header */
0450     if (skb->len < sizeof(struct hdlc_header))
0451         goto rx_error;
0452     cp = skb_pull(skb, sizeof(struct hdlc_header));
0453     if (hdr->address != HDLC_ADDR_ALLSTATIONS ||
0454         hdr->control != HDLC_CTRL_UI)
0455         goto rx_error;
0456 
0457     pid = ntohs(hdr->protocol);
0458     proto = get_proto(dev, pid);
0459     if (!proto) {
0460         if (ppp->protos[IDX_LCP].state == OPENED)
0461             ppp_tx_cp(dev, PID_LCP, LCP_PROTO_REJ,
0462                   ++ppp->seq, skb->len + 2, &hdr->protocol);
0463         goto rx_error;
0464     }
0465 
0466     len = ntohs(cp->len);
0467     if (len < sizeof(struct cp_header) /* no complete CP header? */ ||
0468         skb->len < len /* truncated packet? */)
0469         goto rx_error;
0470     skb_pull(skb, sizeof(struct cp_header));
0471     len -= sizeof(struct cp_header);
0472 
0473     /* HDLC and CP headers stripped from skb */
0474 #if DEBUG_CP
0475     if (cp->code < CP_CODES)
0476         sprintf(debug_buffer, "[%s id 0x%X]", code_names[cp->code],
0477             cp->id);
0478     else
0479         sprintf(debug_buffer, "[code %u id 0x%X]", cp->code, cp->id);
0480     ptr = debug_buffer + strlen(debug_buffer);
0481     for (i = 0; i < min_t(unsigned int, len, DEBUG_CP); i++) {
0482         sprintf(ptr, " %02X", skb->data[i]);
0483         ptr += strlen(ptr);
0484     }
0485     printk(KERN_DEBUG "%s: RX %s %s\n", dev->name, proto_name(pid),
0486            debug_buffer);
0487 #endif
0488 
0489     /* LCP only */
0490     if (pid == PID_LCP)
0491         switch (cp->code) {
0492         case LCP_PROTO_REJ:
0493             pid = ntohs(*(__be16 *)skb->data);
0494             if (pid == PID_LCP || pid == PID_IPCP ||
0495                 pid == PID_IPV6CP)
0496                 ppp_cp_event(dev, pid, RXJ_BAD, 0, 0,
0497                          0, NULL);
0498             goto out;
0499 
0500         case LCP_ECHO_REQ: /* send Echo-Reply */
0501             if (len >= 4 && proto->state == OPENED)
0502                 ppp_tx_cp(dev, PID_LCP, LCP_ECHO_REPLY,
0503                       cp->id, len - 4, skb->data + 4);
0504             goto out;
0505 
0506         case LCP_ECHO_REPLY:
0507             if (cp->id == ppp->echo_id)
0508                 ppp->last_pong = jiffies;
0509             goto out;
0510 
0511         case LCP_DISC_REQ: /* discard */
0512             goto out;
0513         }
0514 
0515     /* LCP, IPCP and IPV6CP */
0516     switch (cp->code) {
0517     case CP_CONF_REQ:
0518         ppp_cp_parse_cr(dev, pid, cp->id, len, skb->data);
0519         break;
0520 
0521     case CP_CONF_ACK:
0522         if (cp->id == proto->cr_id)
0523             ppp_cp_event(dev, pid, RCA, 0, 0, 0, NULL);
0524         break;
0525 
0526     case CP_CONF_REJ:
0527     case CP_CONF_NAK:
0528         if (cp->id == proto->cr_id)
0529             ppp_cp_event(dev, pid, RCN, 0, 0, 0, NULL);
0530         break;
0531 
0532     case CP_TERM_REQ:
0533         ppp_cp_event(dev, pid, RTR, 0, cp->id, 0, NULL);
0534         break;
0535 
0536     case CP_TERM_ACK:
0537         ppp_cp_event(dev, pid, RTA, 0, 0, 0, NULL);
0538         break;
0539 
0540     case CP_CODE_REJ:
0541         ppp_cp_event(dev, pid, RXJ_BAD, 0, 0, 0, NULL);
0542         break;
0543 
0544     default:
0545         len += sizeof(struct cp_header);
0546         if (len > dev->mtu)
0547             len = dev->mtu;
0548         ppp_cp_event(dev, pid, RUC, 0, 0, len, cp);
0549         break;
0550     }
0551     goto out;
0552 
0553 rx_error:
0554     dev->stats.rx_errors++;
0555 out:
0556     spin_unlock_irqrestore(&ppp->lock, flags);
0557     dev_kfree_skb_any(skb);
0558     ppp_tx_flush();
0559     return NET_RX_DROP;
0560 }
0561 
0562 static void ppp_timer(struct timer_list *t)
0563 {
0564     struct proto *proto = from_timer(proto, t, timer);
0565     struct ppp *ppp = get_ppp(proto->dev);
0566     unsigned long flags;
0567 
0568     spin_lock_irqsave(&ppp->lock, flags);
0569     /* mod_timer could be called after we entered this function but
0570      * before we got the lock.
0571      */
0572     if (timer_pending(&proto->timer)) {
0573         spin_unlock_irqrestore(&ppp->lock, flags);
0574         return;
0575     }
0576     switch (proto->state) {
0577     case STOPPING:
0578     case REQ_SENT:
0579     case ACK_RECV:
0580     case ACK_SENT:
0581         if (proto->restart_counter) {
0582             ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
0583                      0, NULL);
0584             proto->restart_counter--;
0585         } else if (netif_carrier_ok(proto->dev))
0586             ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
0587                      0, NULL);
0588         else
0589             ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
0590                      0, NULL);
0591         break;
0592 
0593     case OPENED:
0594         if (proto->pid != PID_LCP)
0595             break;
0596         if (time_after(jiffies, ppp->last_pong +
0597                    ppp->keepalive_timeout * HZ)) {
0598             netdev_info(proto->dev, "Link down\n");
0599             ppp_cp_event(proto->dev, PID_LCP, STOP, 0, 0, 0, NULL);
0600             ppp_cp_event(proto->dev, PID_LCP, START, 0, 0, 0, NULL);
0601         } else {    /* send keep-alive packet */
0602             ppp->echo_id = ++ppp->seq;
0603             ppp_tx_cp(proto->dev, PID_LCP, LCP_ECHO_REQ,
0604                   ppp->echo_id, 0, NULL);
0605             proto->timer.expires = jiffies +
0606                 ppp->keepalive_interval * HZ;
0607             add_timer(&proto->timer);
0608         }
0609         break;
0610     }
0611     spin_unlock_irqrestore(&ppp->lock, flags);
0612     ppp_tx_flush();
0613 }
0614 
0615 static void ppp_start(struct net_device *dev)
0616 {
0617     struct ppp *ppp = get_ppp(dev);
0618     int i;
0619 
0620     for (i = 0; i < IDX_COUNT; i++) {
0621         struct proto *proto = &ppp->protos[i];
0622 
0623         proto->dev = dev;
0624         timer_setup(&proto->timer, ppp_timer, 0);
0625         proto->state = CLOSED;
0626     }
0627     ppp->protos[IDX_LCP].pid = PID_LCP;
0628     ppp->protos[IDX_IPCP].pid = PID_IPCP;
0629     ppp->protos[IDX_IPV6CP].pid = PID_IPV6CP;
0630 
0631     ppp_cp_event(dev, PID_LCP, START, 0, 0, 0, NULL);
0632 }
0633 
0634 static void ppp_stop(struct net_device *dev)
0635 {
0636     ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
0637 }
0638 
0639 static void ppp_close(struct net_device *dev)
0640 {
0641     ppp_tx_flush();
0642 }
0643 
0644 static struct hdlc_proto proto = {
0645     .start      = ppp_start,
0646     .stop       = ppp_stop,
0647     .close      = ppp_close,
0648     .type_trans = ppp_type_trans,
0649     .ioctl      = ppp_ioctl,
0650     .netif_rx   = ppp_rx,
0651     .module     = THIS_MODULE,
0652 };
0653 
0654 static const struct header_ops ppp_header_ops = {
0655     .create = ppp_hard_header,
0656 };
0657 
0658 static int ppp_ioctl(struct net_device *dev, struct if_settings *ifs)
0659 {
0660     hdlc_device *hdlc = dev_to_hdlc(dev);
0661     struct ppp *ppp;
0662     int result;
0663 
0664     switch (ifs->type) {
0665     case IF_GET_PROTO:
0666         if (dev_to_hdlc(dev)->proto != &proto)
0667             return -EINVAL;
0668         ifs->type = IF_PROTO_PPP;
0669         return 0; /* return protocol only, no settable parameters */
0670 
0671     case IF_PROTO_PPP:
0672         if (!capable(CAP_NET_ADMIN))
0673             return -EPERM;
0674 
0675         if (dev->flags & IFF_UP)
0676             return -EBUSY;
0677 
0678         /* no settable parameters */
0679 
0680         result = hdlc->attach(dev, ENCODING_NRZ,
0681                       PARITY_CRC16_PR1_CCITT);
0682         if (result)
0683             return result;
0684 
0685         result = attach_hdlc_protocol(dev, &proto, sizeof(struct ppp));
0686         if (result)
0687             return result;
0688 
0689         ppp = get_ppp(dev);
0690         spin_lock_init(&ppp->lock);
0691         ppp->req_timeout = 2;
0692         ppp->cr_retries = 10;
0693         ppp->term_retries = 2;
0694         ppp->keepalive_interval = 10;
0695         ppp->keepalive_timeout = 60;
0696 
0697         dev->hard_header_len = sizeof(struct hdlc_header);
0698         dev->header_ops = &ppp_header_ops;
0699         dev->type = ARPHRD_PPP;
0700         call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
0701         netif_dormant_on(dev);
0702         return 0;
0703     }
0704 
0705     return -EINVAL;
0706 }
0707 
0708 static int __init hdlc_ppp_init(void)
0709 {
0710     skb_queue_head_init(&tx_queue);
0711     register_hdlc_protocol(&proto);
0712     return 0;
0713 }
0714 
0715 static void __exit hdlc_ppp_exit(void)
0716 {
0717     unregister_hdlc_protocol(&proto);
0718 }
0719 
0720 module_init(hdlc_ppp_init);
0721 module_exit(hdlc_ppp_exit);
0722 
0723 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
0724 MODULE_DESCRIPTION("PPP protocol support for generic HDLC");
0725 MODULE_LICENSE("GPL v2");
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