1 // SPDX-License-Identifier: GPL-2.0-only
3 * Generic HDLC support routines for Linux
4 * Point-to-point protocol support
6 * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
9 #include <linux/errno.h>
10 #include <linux/hdlc.h>
11 #include <linux/if_arp.h>
12 #include <linux/inetdevice.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/pkt_sched.h>
17 #include <linux/poll.h>
18 #include <linux/skbuff.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
22 #define DEBUG_CP 0 /* also bytes# to dump */
24 #define DEBUG_HARD_HEADER 0
26 #define HDLC_ADDR_ALLSTATIONS 0xFF
27 #define HDLC_CTRL_UI 0x03
29 #define PID_LCP 0xC021
31 #define PID_IPCP 0x8021
32 #define PID_IPV6 0x0057
33 #define PID_IPV6CP 0x8057
35 enum {IDX_LCP = 0, IDX_IPCP, IDX_IPV6CP, IDX_COUNT};
36 enum {CP_CONF_REQ = 1, CP_CONF_ACK, CP_CONF_NAK, CP_CONF_REJ, CP_TERM_REQ,
37 CP_TERM_ACK, CP_CODE_REJ, LCP_PROTO_REJ, LCP_ECHO_REQ, LCP_ECHO_REPLY,
38 LCP_DISC_REQ, CP_CODES};
40 static const char *const code_names[CP_CODES] = {
41 "0", "ConfReq", "ConfAck", "ConfNak", "ConfRej", "TermReq",
42 "TermAck", "CodeRej", "ProtoRej", "EchoReq", "EchoReply", "Discard"
44 static char debug_buffer[64 + 3 * DEBUG_CP];
47 enum {LCP_OPTION_MRU = 1, LCP_OPTION_ACCM, LCP_OPTION_MAGIC = 5};
63 struct net_device *dev;
64 struct timer_list timer;
65 unsigned long timeout;
66 u16 pid; /* protocol ID */
68 u8 cr_id; /* ID of last Configuration-Request */
73 struct proto protos[IDX_COUNT];
75 unsigned long last_pong;
76 unsigned int req_timeout, cr_retries, term_retries;
77 unsigned int keepalive_interval, keepalive_timeout;
78 u8 seq; /* local sequence number for requests */
79 u8 echo_id; /* ID of last Echo-Request (LCP) */
82 enum {CLOSED = 0, STOPPED, STOPPING, REQ_SENT, ACK_RECV, ACK_SENT, OPENED,
83 STATES, STATE_MASK = 0xF};
84 enum {START = 0, STOP, TO_GOOD, TO_BAD, RCR_GOOD, RCR_BAD, RCA, RCN, RTR, RTA,
85 RUC, RXJ_GOOD, RXJ_BAD, EVENTS};
86 enum {INV = 0x10, IRC = 0x20, ZRC = 0x40, SCR = 0x80, SCA = 0x100,
87 SCN = 0x200, STR = 0x400, STA = 0x800, SCJ = 0x1000};
90 static const char *const state_names[STATES] = {
91 "Closed", "Stopped", "Stopping", "ReqSent", "AckRecv", "AckSent",
94 static const char *const event_names[EVENTS] = {
95 "Start", "Stop", "TO+", "TO-", "RCR+", "RCR-", "RCA", "RCN",
96 "RTR", "RTA", "RUC", "RXJ+", "RXJ-"
100 static struct sk_buff_head tx_queue; /* used when holding the spin lock */
102 static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr);
104 static inline struct ppp* get_ppp(struct net_device *dev)
106 return (struct ppp *)dev_to_hdlc(dev)->state;
109 static inline struct proto* get_proto(struct net_device *dev, u16 pid)
111 struct ppp *ppp = get_ppp(dev);
115 return &ppp->protos[IDX_LCP];
117 return &ppp->protos[IDX_IPCP];
119 return &ppp->protos[IDX_IPV6CP];
125 static inline const char* proto_name(u16 pid)
139 static __be16 ppp_type_trans(struct sk_buff *skb, struct net_device *dev)
141 struct hdlc_header *data = (struct hdlc_header*)skb->data;
143 if (skb->len < sizeof(struct hdlc_header))
144 return htons(ETH_P_HDLC);
145 if (data->address != HDLC_ADDR_ALLSTATIONS ||
146 data->control != HDLC_CTRL_UI)
147 return htons(ETH_P_HDLC);
149 switch (data->protocol) {
150 case cpu_to_be16(PID_IP):
151 skb_pull(skb, sizeof(struct hdlc_header));
152 return htons(ETH_P_IP);
154 case cpu_to_be16(PID_IPV6):
155 skb_pull(skb, sizeof(struct hdlc_header));
156 return htons(ETH_P_IPV6);
159 return htons(ETH_P_HDLC);
164 static int ppp_hard_header(struct sk_buff *skb, struct net_device *dev,
165 u16 type, const void *daddr, const void *saddr,
168 struct hdlc_header *data;
169 #if DEBUG_HARD_HEADER
170 printk(KERN_DEBUG "%s: ppp_hard_header() called\n", dev->name);
173 skb_push(skb, sizeof(struct hdlc_header));
174 data = (struct hdlc_header*)skb->data;
176 data->address = HDLC_ADDR_ALLSTATIONS;
177 data->control = HDLC_CTRL_UI;
180 data->protocol = htons(PID_IP);
183 data->protocol = htons(PID_IPV6);
188 data->protocol = htons(type);
190 default: /* unknown protocol */
193 return sizeof(struct hdlc_header);
197 static void ppp_tx_flush(void)
200 while ((skb = skb_dequeue(&tx_queue)) != NULL)
204 static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,
205 u8 id, unsigned int len, const void *data)
208 struct cp_header *cp;
209 unsigned int magic_len = 0;
217 if (pid == PID_LCP && (code == LCP_ECHO_REQ || code == LCP_ECHO_REPLY))
218 magic_len = sizeof(magic);
220 skb = dev_alloc_skb(sizeof(struct hdlc_header) +
221 sizeof(struct cp_header) + magic_len + len);
223 netdev_warn(dev, "out of memory in ppp_tx_cp()\n");
226 skb_reserve(skb, sizeof(struct hdlc_header));
228 cp = skb_put(skb, sizeof(struct cp_header));
231 cp->len = htons(sizeof(struct cp_header) + magic_len + len);
234 skb_put_data(skb, &magic, magic_len);
236 skb_put_data(skb, data, len);
239 BUG_ON(code >= CP_CODES);
242 for (i = 0; i < min_t(unsigned int, magic_len + len, DEBUG_CP); i++) {
243 sprintf(ptr, " %02X", skb->data[sizeof(struct cp_header) + i]);
246 printk(KERN_DEBUG "%s: TX %s [%s id 0x%X]%s\n", dev->name,
247 proto_name(pid), code_names[code], id, debug_buffer);
250 ppp_hard_header(skb, dev, pid, NULL, NULL, 0);
252 skb->priority = TC_PRIO_CONTROL;
254 skb_reset_network_header(skb);
255 skb_queue_tail(&tx_queue, skb);
259 /* State transition table (compare STD-51)
261 TO+ = Timeout with counter > 0 irc = Initialize-Restart-Count
262 TO- = Timeout with counter expired zrc = Zero-Restart-Count
264 RCR+ = Receive-Configure-Request (Good) scr = Send-Configure-Request
265 RCR- = Receive-Configure-Request (Bad)
266 RCA = Receive-Configure-Ack sca = Send-Configure-Ack
267 RCN = Receive-Configure-Nak/Rej scn = Send-Configure-Nak/Rej
269 RTR = Receive-Terminate-Request str = Send-Terminate-Request
270 RTA = Receive-Terminate-Ack sta = Send-Terminate-Ack
272 RUC = Receive-Unknown-Code scj = Send-Code-Reject
273 RXJ+ = Receive-Code-Reject (permitted)
274 or Receive-Protocol-Reject
275 RXJ- = Receive-Code-Reject (catastrophic)
276 or Receive-Protocol-Reject
278 static int cp_table[EVENTS][STATES] = {
279 /* CLOSED STOPPED STOPPING REQ_SENT ACK_RECV ACK_SENT OPENED
281 {IRC|SCR|3, INV , INV , INV , INV , INV , INV }, /* START */
282 { INV , 0 , 0 , 0 , 0 , 0 , 0 }, /* STOP */
283 { INV , INV ,STR|2, SCR|3 ,SCR|3, SCR|5 , INV }, /* TO+ */
284 { INV , INV , 1 , 1 , 1 , 1 , INV }, /* TO- */
285 { STA|0 ,IRC|SCR|SCA|5, 2 , SCA|5 ,SCA|6, SCA|5 ,SCR|SCA|5}, /* RCR+ */
286 { STA|0 ,IRC|SCR|SCN|3, 2 , SCN|3 ,SCN|4, SCN|3 ,SCR|SCN|3}, /* RCR- */
287 { STA|0 , STA|1 , 2 , IRC|4 ,SCR|3, 6 , SCR|3 }, /* RCA */
288 { STA|0 , STA|1 , 2 ,IRC|SCR|3,SCR|3,IRC|SCR|5, SCR|3 }, /* RCN */
289 { STA|0 , STA|1 ,STA|2, STA|3 ,STA|3, STA|3 ,ZRC|STA|2}, /* RTR */
290 { 0 , 1 , 1 , 3 , 3 , 5 , SCR|3 }, /* RTA */
291 { SCJ|0 , SCJ|1 ,SCJ|2, SCJ|3 ,SCJ|4, SCJ|5 , SCJ|6 }, /* RUC */
292 { 0 , 1 , 2 , 3 , 3 , 5 , 6 }, /* RXJ+ */
293 { 0 , 1 , 1 , 1 , 1 , 1 ,IRC|STR|2}, /* RXJ- */
297 /* SCA: RCR+ must supply id, len and data
298 SCN: RCR- must supply code, id, len and data
299 STA: RTR must supply id
300 SCJ: RUC must supply CP packet len and data */
301 static void ppp_cp_event(struct net_device *dev, u16 pid, u16 event, u8 code,
302 u8 id, unsigned int len, const void *data)
304 int old_state, action;
305 struct ppp *ppp = get_ppp(dev);
306 struct proto *proto = get_proto(dev, pid);
308 old_state = proto->state;
309 BUG_ON(old_state >= STATES);
310 BUG_ON(event >= EVENTS);
313 printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) %s ...\n", dev->name,
314 proto_name(pid), event_names[event], state_names[proto->state]);
317 action = cp_table[event][old_state];
319 proto->state = action & STATE_MASK;
320 if (action & (SCR | STR)) /* set Configure-Req/Terminate-Req timer */
321 mod_timer(&proto->timer, proto->timeout =
322 jiffies + ppp->req_timeout * HZ);
324 proto->restart_counter = 0;
326 proto->restart_counter = (proto->state == STOPPING) ?
327 ppp->term_retries : ppp->cr_retries;
329 if (action & SCR) /* send Configure-Request */
330 ppp_tx_cp(dev, pid, CP_CONF_REQ, proto->cr_id = ++ppp->seq,
332 if (action & SCA) /* send Configure-Ack */
333 ppp_tx_cp(dev, pid, CP_CONF_ACK, id, len, data);
334 if (action & SCN) /* send Configure-Nak/Reject */
335 ppp_tx_cp(dev, pid, code, id, len, data);
336 if (action & STR) /* send Terminate-Request */
337 ppp_tx_cp(dev, pid, CP_TERM_REQ, ++ppp->seq, 0, NULL);
338 if (action & STA) /* send Terminate-Ack */
339 ppp_tx_cp(dev, pid, CP_TERM_ACK, id, 0, NULL);
340 if (action & SCJ) /* send Code-Reject */
341 ppp_tx_cp(dev, pid, CP_CODE_REJ, ++ppp->seq, len, data);
343 if (old_state != OPENED && proto->state == OPENED) {
344 netdev_info(dev, "%s up\n", proto_name(pid));
345 if (pid == PID_LCP) {
346 netif_dormant_off(dev);
347 ppp_cp_event(dev, PID_IPCP, START, 0, 0, 0, NULL);
348 ppp_cp_event(dev, PID_IPV6CP, START, 0, 0, 0, NULL);
349 ppp->last_pong = jiffies;
350 mod_timer(&proto->timer, proto->timeout =
351 jiffies + ppp->keepalive_interval * HZ);
354 if (old_state == OPENED && proto->state != OPENED) {
355 netdev_info(dev, "%s down\n", proto_name(pid));
356 if (pid == PID_LCP) {
357 netif_dormant_on(dev);
358 ppp_cp_event(dev, PID_IPCP, STOP, 0, 0, 0, NULL);
359 ppp_cp_event(dev, PID_IPV6CP, STOP, 0, 0, 0, NULL);
362 if (old_state != CLOSED && proto->state == CLOSED)
363 del_timer(&proto->timer);
366 printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) ... %s\n", dev->name,
367 proto_name(pid), event_names[event], state_names[proto->state]);
372 static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id,
373 unsigned int req_len, const u8 *data)
375 static u8 const valid_accm[6] = { LCP_OPTION_ACCM, 6, 0, 0, 0, 0 };
378 unsigned int len = req_len, nak_len = 0, rej_len = 0;
380 if (!(out = kmalloc(len, GFP_ATOMIC))) {
381 dev->stats.rx_dropped++;
382 return; /* out of memory, ignore CR packet */
385 for (opt = data; len; len -= opt[1], opt += opt[1]) {
386 if (len < 2 || len < opt[1]) {
387 dev->stats.rx_errors++;
389 return; /* bad packet, drop silently */
395 continue; /* MRU always OK and > 1500 bytes? */
397 case LCP_OPTION_ACCM: /* async control character map */
398 if (!memcmp(opt, valid_accm,
401 if (!rej_len) { /* NAK it */
402 memcpy(out + nak_len, valid_accm,
404 nak_len += sizeof(valid_accm);
408 case LCP_OPTION_MAGIC:
409 if (opt[1] != 6 || (!opt[2] && !opt[3] &&
411 break; /* reject invalid magic number */
414 /* reject this option */
415 memcpy(out + rej_len, opt, opt[1]);
420 ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_REJ, id, rej_len, out);
422 ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_NAK, id, nak_len, out);
424 ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data);
429 static int ppp_rx(struct sk_buff *skb)
431 struct hdlc_header *hdr = (struct hdlc_header*)skb->data;
432 struct net_device *dev = skb->dev;
433 struct ppp *ppp = get_ppp(dev);
435 struct cp_header *cp;
444 spin_lock_irqsave(&ppp->lock, flags);
445 /* Check HDLC header */
446 if (skb->len < sizeof(struct hdlc_header))
448 cp = skb_pull(skb, sizeof(struct hdlc_header));
449 if (hdr->address != HDLC_ADDR_ALLSTATIONS ||
450 hdr->control != HDLC_CTRL_UI)
453 pid = ntohs(hdr->protocol);
454 proto = get_proto(dev, pid);
456 if (ppp->protos[IDX_LCP].state == OPENED)
457 ppp_tx_cp(dev, PID_LCP, LCP_PROTO_REJ,
458 ++ppp->seq, skb->len + 2, &hdr->protocol);
462 len = ntohs(cp->len);
463 if (len < sizeof(struct cp_header) /* no complete CP header? */ ||
464 skb->len < len /* truncated packet? */)
466 skb_pull(skb, sizeof(struct cp_header));
467 len -= sizeof(struct cp_header);
469 /* HDLC and CP headers stripped from skb */
471 if (cp->code < CP_CODES)
472 sprintf(debug_buffer, "[%s id 0x%X]", code_names[cp->code],
475 sprintf(debug_buffer, "[code %u id 0x%X]", cp->code, cp->id);
476 ptr = debug_buffer + strlen(debug_buffer);
477 for (i = 0; i < min_t(unsigned int, len, DEBUG_CP); i++) {
478 sprintf(ptr, " %02X", skb->data[i]);
481 printk(KERN_DEBUG "%s: RX %s %s\n", dev->name, proto_name(pid),
489 pid = ntohs(*(__be16*)skb->data);
490 if (pid == PID_LCP || pid == PID_IPCP ||
492 ppp_cp_event(dev, pid, RXJ_BAD, 0, 0,
496 case LCP_ECHO_REQ: /* send Echo-Reply */
497 if (len >= 4 && proto->state == OPENED)
498 ppp_tx_cp(dev, PID_LCP, LCP_ECHO_REPLY,
499 cp->id, len - 4, skb->data + 4);
503 if (cp->id == ppp->echo_id)
504 ppp->last_pong = jiffies;
507 case LCP_DISC_REQ: /* discard */
511 /* LCP, IPCP and IPV6CP */
514 ppp_cp_parse_cr(dev, pid, cp->id, len, skb->data);
518 if (cp->id == proto->cr_id)
519 ppp_cp_event(dev, pid, RCA, 0, 0, 0, NULL);
524 if (cp->id == proto->cr_id)
525 ppp_cp_event(dev, pid, RCN, 0, 0, 0, NULL);
529 ppp_cp_event(dev, pid, RTR, 0, cp->id, 0, NULL);
533 ppp_cp_event(dev, pid, RTA, 0, 0, 0, NULL);
537 ppp_cp_event(dev, pid, RXJ_BAD, 0, 0, 0, NULL);
541 len += sizeof(struct cp_header);
544 ppp_cp_event(dev, pid, RUC, 0, 0, len, cp);
550 dev->stats.rx_errors++;
552 spin_unlock_irqrestore(&ppp->lock, flags);
553 dev_kfree_skb_any(skb);
558 static void ppp_timer(struct timer_list *t)
560 struct proto *proto = from_timer(proto, t, timer);
561 struct ppp *ppp = get_ppp(proto->dev);
564 spin_lock_irqsave(&ppp->lock, flags);
565 switch (proto->state) {
570 if (proto->restart_counter) {
571 ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
573 proto->restart_counter--;
574 } else if (netif_carrier_ok(proto->dev))
575 ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
578 ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
583 if (proto->pid != PID_LCP)
585 if (time_after(jiffies, ppp->last_pong +
586 ppp->keepalive_timeout * HZ)) {
587 netdev_info(proto->dev, "Link down\n");
588 ppp_cp_event(proto->dev, PID_LCP, STOP, 0, 0, 0, NULL);
589 ppp_cp_event(proto->dev, PID_LCP, START, 0, 0, 0, NULL);
590 } else { /* send keep-alive packet */
591 ppp->echo_id = ++ppp->seq;
592 ppp_tx_cp(proto->dev, PID_LCP, LCP_ECHO_REQ,
593 ppp->echo_id, 0, NULL);
594 proto->timer.expires = jiffies +
595 ppp->keepalive_interval * HZ;
596 add_timer(&proto->timer);
600 spin_unlock_irqrestore(&ppp->lock, flags);
605 static void ppp_start(struct net_device *dev)
607 struct ppp *ppp = get_ppp(dev);
610 for (i = 0; i < IDX_COUNT; i++) {
611 struct proto *proto = &ppp->protos[i];
613 timer_setup(&proto->timer, ppp_timer, 0);
614 proto->state = CLOSED;
616 ppp->protos[IDX_LCP].pid = PID_LCP;
617 ppp->protos[IDX_IPCP].pid = PID_IPCP;
618 ppp->protos[IDX_IPV6CP].pid = PID_IPV6CP;
620 ppp_cp_event(dev, PID_LCP, START, 0, 0, 0, NULL);
623 static void ppp_stop(struct net_device *dev)
625 ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
628 static void ppp_close(struct net_device *dev)
633 static struct hdlc_proto proto = {
637 .type_trans = ppp_type_trans,
640 .module = THIS_MODULE,
643 static const struct header_ops ppp_header_ops = {
644 .create = ppp_hard_header,
647 static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr)
649 hdlc_device *hdlc = dev_to_hdlc(dev);
653 switch (ifr->ifr_settings.type) {
655 if (dev_to_hdlc(dev)->proto != &proto)
657 ifr->ifr_settings.type = IF_PROTO_PPP;
658 return 0; /* return protocol only, no settable parameters */
661 if (!capable(CAP_NET_ADMIN))
664 if (dev->flags & IFF_UP)
667 /* no settable parameters */
669 result = hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
673 result = attach_hdlc_protocol(dev, &proto, sizeof(struct ppp));
678 spin_lock_init(&ppp->lock);
679 ppp->req_timeout = 2;
680 ppp->cr_retries = 10;
681 ppp->term_retries = 2;
682 ppp->keepalive_interval = 10;
683 ppp->keepalive_timeout = 60;
685 dev->hard_header_len = sizeof(struct hdlc_header);
686 dev->header_ops = &ppp_header_ops;
687 dev->type = ARPHRD_PPP;
688 call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
689 netif_dormant_on(dev);
697 static int __init mod_init(void)
699 skb_queue_head_init(&tx_queue);
700 register_hdlc_protocol(&proto);
704 static void __exit mod_exit(void)
706 unregister_hdlc_protocol(&proto);
710 module_init(mod_init);
711 module_exit(mod_exit);
713 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
714 MODULE_DESCRIPTION("PPP protocol support for generic HDLC");
715 MODULE_LICENSE("GPL v2");