xref: /linux/drivers/net/wan/hdlc_ppp.c (revision 8f7aa3d3c7323f4ca2768a9e74ebbe359c4f8f88)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Generic HDLC support routines for Linux
4  * Point-to-point protocol support
5  *
6  * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
7  */
8 
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>
21 
22 #define DEBUG_CP		0 /* also bytes# to dump */
23 #define DEBUG_STATE		0
24 #define DEBUG_HARD_HEADER	0
25 
26 #define HDLC_ADDR_ALLSTATIONS	0xFF
27 #define HDLC_CTRL_UI		0x03
28 
29 #define PID_LCP			0xC021
30 #define PID_IP			0x0021
31 #define PID_IPCP		0x8021
32 #define PID_IPV6		0x0057
33 #define PID_IPV6CP		0x8057
34 
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};
39 #if DEBUG_CP
40 static const char *const code_names[CP_CODES] = {
41 	"0", "ConfReq", "ConfAck", "ConfNak", "ConfRej", "TermReq",
42 	"TermAck", "CodeRej", "ProtoRej", "EchoReq", "EchoReply", "Discard"
43 };
44 
45 static char debug_buffer[64 + 3 * DEBUG_CP];
46 #endif
47 
48 enum {LCP_OPTION_MRU = 1, LCP_OPTION_ACCM, LCP_OPTION_MAGIC = 5};
49 
50 struct hdlc_header {
51 	u8 address;
52 	u8 control;
53 	__be16 protocol;
54 };
55 
56 struct cp_header {
57 	u8 code;
58 	u8 id;
59 	__be16 len;
60 };
61 
62 struct proto {
63 	struct net_device *dev;
64 	struct timer_list timer;
65 	unsigned long timeout;
66 	u16 pid;		/* protocol ID */
67 	u8 state;
68 	u8 cr_id;		/* ID of last Configuration-Request */
69 	u8 restart_counter;
70 };
71 
72 struct ppp {
73 	struct proto protos[IDX_COUNT];
74 	spinlock_t lock;
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) */
80 };
81 
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};
88 
89 #if DEBUG_STATE
90 static const char *const state_names[STATES] = {
91 	"Closed", "Stopped", "Stopping", "ReqSent", "AckRecv", "AckSent",
92 	"Opened"
93 };
94 
95 static const char *const event_names[EVENTS] = {
96 	"Start", "Stop", "TO+", "TO-", "RCR+", "RCR-", "RCA", "RCN",
97 	"RTR", "RTA", "RUC", "RXJ+", "RXJ-"
98 };
99 #endif
100 
101 static struct sk_buff_head tx_queue; /* used when holding the spin lock */
102 
103 static int ppp_ioctl(struct net_device *dev, struct if_settings *ifs);
104 
105 static inline struct ppp *get_ppp(struct net_device *dev)
106 {
107 	return (struct ppp *)dev_to_hdlc(dev)->state;
108 }
109 
110 static inline struct proto *get_proto(struct net_device *dev, u16 pid)
111 {
112 	struct ppp *ppp = get_ppp(dev);
113 
114 	switch (pid) {
115 	case PID_LCP:
116 		return &ppp->protos[IDX_LCP];
117 	case PID_IPCP:
118 		return &ppp->protos[IDX_IPCP];
119 	case PID_IPV6CP:
120 		return &ppp->protos[IDX_IPV6CP];
121 	default:
122 		return NULL;
123 	}
124 }
125 
126 static inline const char *proto_name(u16 pid)
127 {
128 	switch (pid) {
129 	case PID_IPCP:
130 		return "IPCP";
131 	case PID_IPV6CP:
132 		return "IPV6CP";
133 	default:
134 		return "LCP";
135 	}
136 }
137 
138 static __be16 ppp_type_trans(struct sk_buff *skb, struct net_device *dev)
139 {
140 	struct hdlc_header *data = (struct hdlc_header *)skb->data;
141 
142 	if (skb->len < sizeof(struct hdlc_header))
143 		return htons(ETH_P_HDLC);
144 	if (data->address != HDLC_ADDR_ALLSTATIONS ||
145 	    data->control != HDLC_CTRL_UI)
146 		return htons(ETH_P_HDLC);
147 
148 	switch (data->protocol) {
149 	case cpu_to_be16(PID_IP):
150 		skb_pull(skb, sizeof(struct hdlc_header));
151 		return htons(ETH_P_IP);
152 
153 	case cpu_to_be16(PID_IPV6):
154 		skb_pull(skb, sizeof(struct hdlc_header));
155 		return htons(ETH_P_IPV6);
156 
157 	default:
158 		return htons(ETH_P_HDLC);
159 	}
160 }
161 
162 static int ppp_hard_header(struct sk_buff *skb, struct net_device *dev,
163 			   u16 type, const void *daddr, const void *saddr,
164 			   unsigned int len)
165 {
166 	struct hdlc_header *data;
167 #if DEBUG_HARD_HEADER
168 	printk(KERN_DEBUG "%s: ppp_hard_header() called\n", dev->name);
169 #endif
170 
171 	skb_push(skb, sizeof(struct hdlc_header));
172 	data = (struct hdlc_header *)skb->data;
173 
174 	data->address = HDLC_ADDR_ALLSTATIONS;
175 	data->control = HDLC_CTRL_UI;
176 	switch (type) {
177 	case ETH_P_IP:
178 		data->protocol = htons(PID_IP);
179 		break;
180 	case ETH_P_IPV6:
181 		data->protocol = htons(PID_IPV6);
182 		break;
183 	case PID_LCP:
184 	case PID_IPCP:
185 	case PID_IPV6CP:
186 		data->protocol = htons(type);
187 		break;
188 	default:		/* unknown protocol */
189 		data->protocol = 0;
190 	}
191 	return sizeof(struct hdlc_header);
192 }
193 
194 static void ppp_tx_flush(void)
195 {
196 	struct sk_buff *skb;
197 
198 	while ((skb = skb_dequeue(&tx_queue)) != NULL)
199 		dev_queue_xmit(skb);
200 }
201 
202 static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,
203 		      u8 id, unsigned int len, const void *data)
204 {
205 	struct sk_buff *skb;
206 	struct cp_header *cp;
207 	unsigned int magic_len = 0;
208 	static u32 magic;
209 
210 #if DEBUG_CP
211 	int i;
212 	char *ptr;
213 #endif
214 
215 	if (pid == PID_LCP && (code == LCP_ECHO_REQ || code == LCP_ECHO_REPLY))
216 		magic_len = sizeof(magic);
217 
218 	skb = dev_alloc_skb(sizeof(struct hdlc_header) +
219 			    sizeof(struct cp_header) + magic_len + len);
220 	if (!skb)
221 		return;
222 
223 	skb_reserve(skb, sizeof(struct hdlc_header));
224 
225 	cp = skb_put(skb, sizeof(struct cp_header));
226 	cp->code = code;
227 	cp->id = id;
228 	cp->len = htons(sizeof(struct cp_header) + magic_len + len);
229 
230 	if (magic_len)
231 		skb_put_data(skb, &magic, magic_len);
232 	if (len)
233 		skb_put_data(skb, data, len);
234 
235 #if DEBUG_CP
236 	BUG_ON(code >= CP_CODES);
237 	ptr = debug_buffer;
238 	*ptr = '\x0';
239 	for (i = 0; i < min_t(unsigned int, magic_len + len, DEBUG_CP); i++) {
240 		sprintf(ptr, " %02X", skb->data[sizeof(struct cp_header) + i]);
241 		ptr += strlen(ptr);
242 	}
243 	printk(KERN_DEBUG "%s: TX %s [%s id 0x%X]%s\n", dev->name,
244 	       proto_name(pid), code_names[code], id, debug_buffer);
245 #endif
246 
247 	ppp_hard_header(skb, dev, pid, NULL, NULL, 0);
248 
249 	skb->priority = TC_PRIO_CONTROL;
250 	skb->dev = dev;
251 	skb->protocol = htons(ETH_P_HDLC);
252 	skb_reset_network_header(skb);
253 	skb_queue_tail(&tx_queue, skb);
254 }
255 
256 /* State transition table (compare STD-51)
257    Events                                   Actions
258    TO+  = Timeout with counter > 0          irc = Initialize-Restart-Count
259    TO-  = Timeout with counter expired      zrc = Zero-Restart-Count
260 
261    RCR+ = Receive-Configure-Request (Good)  scr = Send-Configure-Request
262    RCR- = Receive-Configure-Request (Bad)
263    RCA  = Receive-Configure-Ack             sca = Send-Configure-Ack
264    RCN  = Receive-Configure-Nak/Rej         scn = Send-Configure-Nak/Rej
265 
266    RTR  = Receive-Terminate-Request         str = Send-Terminate-Request
267    RTA  = Receive-Terminate-Ack             sta = Send-Terminate-Ack
268 
269    RUC  = Receive-Unknown-Code              scj = Send-Code-Reject
270    RXJ+ = Receive-Code-Reject (permitted)
271        or Receive-Protocol-Reject
272    RXJ- = Receive-Code-Reject (catastrophic)
273        or Receive-Protocol-Reject
274 */
275 static int cp_table[EVENTS][STATES] = {
276 	/* CLOSED     STOPPED STOPPING REQ_SENT ACK_RECV ACK_SENT OPENED
277 	     0           1         2       3       4      5          6    */
278 	{IRC|SCR|3,     INV     , INV ,   INV   , INV ,  INV    ,   INV   }, /* START */
279 	{   INV   ,      0      ,  0  ,    0    ,  0  ,   0     ,    0    }, /* STOP */
280 	{   INV   ,     INV     ,STR|2,  SCR|3  ,SCR|3,  SCR|5  ,   INV   }, /* TO+ */
281 	{   INV   ,     INV     ,  1  ,    1    ,  1  ,    1    ,   INV   }, /* TO- */
282 	{  STA|0  ,IRC|SCR|SCA|5,  2  ,  SCA|5  ,SCA|6,  SCA|5  ,SCR|SCA|5}, /* RCR+ */
283 	{  STA|0  ,IRC|SCR|SCN|3,  2  ,  SCN|3  ,SCN|4,  SCN|3  ,SCR|SCN|3}, /* RCR- */
284 	{  STA|0  ,    STA|1    ,  2  ,  IRC|4  ,SCR|3,    6    , SCR|3   }, /* RCA */
285 	{  STA|0  ,    STA|1    ,  2  ,IRC|SCR|3,SCR|3,IRC|SCR|5, SCR|3   }, /* RCN */
286 	{  STA|0  ,    STA|1    ,STA|2,  STA|3  ,STA|3,  STA|3  ,ZRC|STA|2}, /* RTR */
287 	{    0    ,      1      ,  1  ,    3    ,  3  ,    5    ,  SCR|3  }, /* RTA */
288 	{  SCJ|0  ,    SCJ|1    ,SCJ|2,  SCJ|3  ,SCJ|4,  SCJ|5  ,  SCJ|6  }, /* RUC */
289 	{    0    ,      1      ,  2  ,    3    ,  3  ,    5    ,    6    }, /* RXJ+ */
290 	{    0    ,      1      ,  1  ,    1    ,  1  ,    1    ,IRC|STR|2}, /* RXJ- */
291 };
292 
293 /* SCA: RCR+ must supply id, len and data
294    SCN: RCR- must supply code, id, len and data
295    STA: RTR must supply id
296    SCJ: RUC must supply CP packet len and data */
297 static void ppp_cp_event(struct net_device *dev, u16 pid, u16 event, u8 code,
298 			 u8 id, unsigned int len, const void *data)
299 {
300 	int old_state, action;
301 	struct ppp *ppp = get_ppp(dev);
302 	struct proto *proto = get_proto(dev, pid);
303 
304 	old_state = proto->state;
305 	BUG_ON(old_state >= STATES);
306 	BUG_ON(event >= EVENTS);
307 
308 #if DEBUG_STATE
309 	printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) %s ...\n", dev->name,
310 	       proto_name(pid), event_names[event], state_names[proto->state]);
311 #endif
312 
313 	action = cp_table[event][old_state];
314 
315 	proto->state = action & STATE_MASK;
316 	if (action & (SCR | STR)) /* set Configure-Req/Terminate-Req timer */
317 		mod_timer(&proto->timer, proto->timeout =
318 			  jiffies + ppp->req_timeout * HZ);
319 	if (action & ZRC)
320 		proto->restart_counter = 0;
321 	if (action & IRC)
322 		proto->restart_counter = (proto->state == STOPPING) ?
323 			ppp->term_retries : ppp->cr_retries;
324 
325 	if (action & SCR)	/* send Configure-Request */
326 		ppp_tx_cp(dev, pid, CP_CONF_REQ, proto->cr_id = ++ppp->seq,
327 			  0, NULL);
328 	if (action & SCA)	/* send Configure-Ack */
329 		ppp_tx_cp(dev, pid, CP_CONF_ACK, id, len, data);
330 	if (action & SCN)	/* send Configure-Nak/Reject */
331 		ppp_tx_cp(dev, pid, code, id, len, data);
332 	if (action & STR)	/* send Terminate-Request */
333 		ppp_tx_cp(dev, pid, CP_TERM_REQ, ++ppp->seq, 0, NULL);
334 	if (action & STA)	/* send Terminate-Ack */
335 		ppp_tx_cp(dev, pid, CP_TERM_ACK, id, 0, NULL);
336 	if (action & SCJ)	/* send Code-Reject */
337 		ppp_tx_cp(dev, pid, CP_CODE_REJ, ++ppp->seq, len, data);
338 
339 	if (old_state != OPENED && proto->state == OPENED) {
340 		netdev_info(dev, "%s up\n", proto_name(pid));
341 		if (pid == PID_LCP) {
342 			netif_dormant_off(dev);
343 			ppp_cp_event(dev, PID_IPCP, START, 0, 0, 0, NULL);
344 			ppp_cp_event(dev, PID_IPV6CP, START, 0, 0, 0, NULL);
345 			ppp->last_pong = jiffies;
346 			mod_timer(&proto->timer, proto->timeout =
347 				  jiffies + ppp->keepalive_interval * HZ);
348 		}
349 	}
350 	if (old_state == OPENED && proto->state != OPENED) {
351 		netdev_info(dev, "%s down\n", proto_name(pid));
352 		if (pid == PID_LCP) {
353 			netif_dormant_on(dev);
354 			ppp_cp_event(dev, PID_IPCP, STOP, 0, 0, 0, NULL);
355 			ppp_cp_event(dev, PID_IPV6CP, STOP, 0, 0, 0, NULL);
356 		}
357 	}
358 	if (old_state != CLOSED && proto->state == CLOSED)
359 		timer_delete(&proto->timer);
360 
361 #if DEBUG_STATE
362 	printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) ... %s\n", dev->name,
363 	       proto_name(pid), event_names[event], state_names[proto->state]);
364 #endif
365 }
366 
367 static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id,
368 			    unsigned int req_len, const u8 *data)
369 {
370 	static u8 const valid_accm[6] = { LCP_OPTION_ACCM, 6, 0, 0, 0, 0 };
371 	const u8 *opt;
372 	u8 *out;
373 	unsigned int len = req_len, nak_len = 0, rej_len = 0;
374 
375 	out = kmalloc(len, GFP_ATOMIC);
376 	if (!out) {
377 		dev->stats.rx_dropped++;
378 		return;	/* out of memory, ignore CR packet */
379 	}
380 
381 	for (opt = data; len; len -= opt[1], opt += opt[1]) {
382 		if (len < 2 || opt[1] < 2 || len < opt[1])
383 			goto err_out;
384 
385 		if (pid == PID_LCP)
386 			switch (opt[0]) {
387 			case LCP_OPTION_MRU:
388 				continue; /* MRU always OK and > 1500 bytes? */
389 
390 			case LCP_OPTION_ACCM: /* async control character map */
391 				if (opt[1] < sizeof(valid_accm))
392 					goto err_out;
393 				if (!memcmp(opt, valid_accm,
394 					    sizeof(valid_accm)))
395 					continue;
396 				if (!rej_len) { /* NAK it */
397 					memcpy(out + nak_len, valid_accm,
398 					       sizeof(valid_accm));
399 					nak_len += sizeof(valid_accm);
400 					continue;
401 				}
402 				break;
403 			case LCP_OPTION_MAGIC:
404 				if (len < 6)
405 					goto err_out;
406 				if (opt[1] != 6 || (!opt[2] && !opt[3] &&
407 						    !opt[4] && !opt[5]))
408 					break; /* reject invalid magic number */
409 				continue;
410 			}
411 		/* reject this option */
412 		memcpy(out + rej_len, opt, opt[1]);
413 		rej_len += opt[1];
414 	}
415 
416 	if (rej_len)
417 		ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_REJ, id, rej_len, out);
418 	else if (nak_len)
419 		ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_NAK, id, nak_len, out);
420 	else
421 		ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data);
422 
423 	kfree(out);
424 	return;
425 
426 err_out:
427 	dev->stats.rx_errors++;
428 	kfree(out);
429 }
430 
431 static int ppp_rx(struct sk_buff *skb)
432 {
433 	struct hdlc_header *hdr = (struct hdlc_header *)skb->data;
434 	struct net_device *dev = skb->dev;
435 	struct ppp *ppp = get_ppp(dev);
436 	struct proto *proto;
437 	struct cp_header *cp;
438 	unsigned long flags;
439 	unsigned int len;
440 	u16 pid;
441 #if DEBUG_CP
442 	int i;
443 	char *ptr;
444 #endif
445 
446 	spin_lock_irqsave(&ppp->lock, flags);
447 	/* Check HDLC header */
448 	if (skb->len < sizeof(struct hdlc_header))
449 		goto rx_error;
450 	cp = skb_pull(skb, sizeof(struct hdlc_header));
451 	if (hdr->address != HDLC_ADDR_ALLSTATIONS ||
452 	    hdr->control != HDLC_CTRL_UI)
453 		goto rx_error;
454 
455 	pid = ntohs(hdr->protocol);
456 	proto = get_proto(dev, pid);
457 	if (!proto) {
458 		if (ppp->protos[IDX_LCP].state == OPENED)
459 			ppp_tx_cp(dev, PID_LCP, LCP_PROTO_REJ,
460 				  ++ppp->seq, skb->len + 2, &hdr->protocol);
461 		goto rx_error;
462 	}
463 
464 	len = ntohs(cp->len);
465 	if (len < sizeof(struct cp_header) /* no complete CP header? */ ||
466 	    skb->len < len /* truncated packet? */)
467 		goto rx_error;
468 	skb_pull(skb, sizeof(struct cp_header));
469 	len -= sizeof(struct cp_header);
470 
471 	/* HDLC and CP headers stripped from skb */
472 #if DEBUG_CP
473 	if (cp->code < CP_CODES)
474 		sprintf(debug_buffer, "[%s id 0x%X]", code_names[cp->code],
475 			cp->id);
476 	else
477 		sprintf(debug_buffer, "[code %u id 0x%X]", cp->code, cp->id);
478 	ptr = debug_buffer + strlen(debug_buffer);
479 	for (i = 0; i < min_t(unsigned int, len, DEBUG_CP); i++) {
480 		sprintf(ptr, " %02X", skb->data[i]);
481 		ptr += strlen(ptr);
482 	}
483 	printk(KERN_DEBUG "%s: RX %s %s\n", dev->name, proto_name(pid),
484 	       debug_buffer);
485 #endif
486 
487 	/* LCP only */
488 	if (pid == PID_LCP)
489 		switch (cp->code) {
490 		case LCP_PROTO_REJ:
491 			pid = ntohs(*(__be16 *)skb->data);
492 			if (pid == PID_LCP || pid == PID_IPCP ||
493 			    pid == PID_IPV6CP)
494 				ppp_cp_event(dev, pid, RXJ_BAD, 0, 0,
495 					     0, NULL);
496 			goto out;
497 
498 		case LCP_ECHO_REQ: /* send Echo-Reply */
499 			if (len >= 4 && proto->state == OPENED)
500 				ppp_tx_cp(dev, PID_LCP, LCP_ECHO_REPLY,
501 					  cp->id, len - 4, skb->data + 4);
502 			goto out;
503 
504 		case LCP_ECHO_REPLY:
505 			if (cp->id == ppp->echo_id)
506 				ppp->last_pong = jiffies;
507 			goto out;
508 
509 		case LCP_DISC_REQ: /* discard */
510 			goto out;
511 		}
512 
513 	/* LCP, IPCP and IPV6CP */
514 	switch (cp->code) {
515 	case CP_CONF_REQ:
516 		ppp_cp_parse_cr(dev, pid, cp->id, len, skb->data);
517 		break;
518 
519 	case CP_CONF_ACK:
520 		if (cp->id == proto->cr_id)
521 			ppp_cp_event(dev, pid, RCA, 0, 0, 0, NULL);
522 		break;
523 
524 	case CP_CONF_REJ:
525 	case CP_CONF_NAK:
526 		if (cp->id == proto->cr_id)
527 			ppp_cp_event(dev, pid, RCN, 0, 0, 0, NULL);
528 		break;
529 
530 	case CP_TERM_REQ:
531 		ppp_cp_event(dev, pid, RTR, 0, cp->id, 0, NULL);
532 		break;
533 
534 	case CP_TERM_ACK:
535 		ppp_cp_event(dev, pid, RTA, 0, 0, 0, NULL);
536 		break;
537 
538 	case CP_CODE_REJ:
539 		ppp_cp_event(dev, pid, RXJ_BAD, 0, 0, 0, NULL);
540 		break;
541 
542 	default:
543 		len += sizeof(struct cp_header);
544 		if (len > dev->mtu)
545 			len = dev->mtu;
546 		ppp_cp_event(dev, pid, RUC, 0, 0, len, cp);
547 		break;
548 	}
549 	goto out;
550 
551 rx_error:
552 	dev->stats.rx_errors++;
553 out:
554 	spin_unlock_irqrestore(&ppp->lock, flags);
555 	dev_kfree_skb_any(skb);
556 	ppp_tx_flush();
557 	return NET_RX_DROP;
558 }
559 
560 static void ppp_timer(struct timer_list *t)
561 {
562 	struct proto *proto = timer_container_of(proto, t, timer);
563 	struct ppp *ppp = get_ppp(proto->dev);
564 	unsigned long flags;
565 
566 	spin_lock_irqsave(&ppp->lock, flags);
567 	/* mod_timer could be called after we entered this function but
568 	 * before we got the lock.
569 	 */
570 	if (timer_pending(&proto->timer)) {
571 		spin_unlock_irqrestore(&ppp->lock, flags);
572 		return;
573 	}
574 	switch (proto->state) {
575 	case STOPPING:
576 	case REQ_SENT:
577 	case ACK_RECV:
578 	case ACK_SENT:
579 		if (proto->restart_counter) {
580 			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
581 				     0, NULL);
582 			proto->restart_counter--;
583 		} else if (netif_carrier_ok(proto->dev))
584 			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
585 				     0, NULL);
586 		else
587 			ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
588 				     0, NULL);
589 		break;
590 
591 	case OPENED:
592 		if (proto->pid != PID_LCP)
593 			break;
594 		if (time_after(jiffies, ppp->last_pong +
595 			       ppp->keepalive_timeout * HZ)) {
596 			netdev_info(proto->dev, "Link down\n");
597 			ppp_cp_event(proto->dev, PID_LCP, STOP, 0, 0, 0, NULL);
598 			ppp_cp_event(proto->dev, PID_LCP, START, 0, 0, 0, NULL);
599 		} else {	/* send keep-alive packet */
600 			ppp->echo_id = ++ppp->seq;
601 			ppp_tx_cp(proto->dev, PID_LCP, LCP_ECHO_REQ,
602 				  ppp->echo_id, 0, NULL);
603 			proto->timer.expires = jiffies +
604 				ppp->keepalive_interval * HZ;
605 			add_timer(&proto->timer);
606 		}
607 		break;
608 	}
609 	spin_unlock_irqrestore(&ppp->lock, flags);
610 	ppp_tx_flush();
611 }
612 
613 static void ppp_start(struct net_device *dev)
614 {
615 	struct ppp *ppp = get_ppp(dev);
616 	int i;
617 
618 	for (i = 0; i < IDX_COUNT; i++) {
619 		struct proto *proto = &ppp->protos[i];
620 
621 		proto->dev = dev;
622 		timer_setup(&proto->timer, ppp_timer, 0);
623 		proto->state = CLOSED;
624 	}
625 	ppp->protos[IDX_LCP].pid = PID_LCP;
626 	ppp->protos[IDX_IPCP].pid = PID_IPCP;
627 	ppp->protos[IDX_IPV6CP].pid = PID_IPV6CP;
628 
629 	ppp_cp_event(dev, PID_LCP, START, 0, 0, 0, NULL);
630 }
631 
632 static void ppp_stop(struct net_device *dev)
633 {
634 	ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
635 }
636 
637 static void ppp_close(struct net_device *dev)
638 {
639 	ppp_tx_flush();
640 }
641 
642 static struct hdlc_proto proto = {
643 	.start		= ppp_start,
644 	.stop		= ppp_stop,
645 	.close		= ppp_close,
646 	.type_trans	= ppp_type_trans,
647 	.ioctl		= ppp_ioctl,
648 	.netif_rx	= ppp_rx,
649 	.module		= THIS_MODULE,
650 };
651 
652 static const struct header_ops ppp_header_ops = {
653 	.create = ppp_hard_header,
654 };
655 
656 static int ppp_ioctl(struct net_device *dev, struct if_settings *ifs)
657 {
658 	hdlc_device *hdlc = dev_to_hdlc(dev);
659 	struct ppp *ppp;
660 	int result;
661 
662 	switch (ifs->type) {
663 	case IF_GET_PROTO:
664 		if (dev_to_hdlc(dev)->proto != &proto)
665 			return -EINVAL;
666 		ifs->type = IF_PROTO_PPP;
667 		return 0; /* return protocol only, no settable parameters */
668 
669 	case IF_PROTO_PPP:
670 		if (!capable(CAP_NET_ADMIN))
671 			return -EPERM;
672 
673 		if (dev->flags & IFF_UP)
674 			return -EBUSY;
675 
676 		/* no settable parameters */
677 
678 		result = hdlc->attach(dev, ENCODING_NRZ,
679 				      PARITY_CRC16_PR1_CCITT);
680 		if (result)
681 			return result;
682 
683 		result = attach_hdlc_protocol(dev, &proto, sizeof(struct ppp));
684 		if (result)
685 			return result;
686 
687 		ppp = get_ppp(dev);
688 		spin_lock_init(&ppp->lock);
689 		ppp->req_timeout = 2;
690 		ppp->cr_retries = 10;
691 		ppp->term_retries = 2;
692 		ppp->keepalive_interval = 10;
693 		ppp->keepalive_timeout = 60;
694 
695 		dev->hard_header_len = sizeof(struct hdlc_header);
696 		dev->header_ops = &ppp_header_ops;
697 		dev->type = ARPHRD_PPP;
698 		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
699 		netif_dormant_on(dev);
700 		return 0;
701 	}
702 
703 	return -EINVAL;
704 }
705 
706 static int __init hdlc_ppp_init(void)
707 {
708 	skb_queue_head_init(&tx_queue);
709 	register_hdlc_protocol(&proto);
710 	return 0;
711 }
712 
713 static void __exit hdlc_ppp_exit(void)
714 {
715 	unregister_hdlc_protocol(&proto);
716 }
717 
718 module_init(hdlc_ppp_init);
719 module_exit(hdlc_ppp_exit);
720 
721 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
722 MODULE_DESCRIPTION("PPP protocol support for generic HDLC");
723 MODULE_LICENSE("GPL v2");
724