xref: /openbmc/linux/drivers/net/wan/hdlc_ppp.c (revision 76a4f7cc)
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_LCP:
130 		return "LCP";
131 	case PID_IPCP:
132 		return "IPCP";
133 	case PID_IPV6CP:
134 		return "IPV6CP";
135 	default:
136 		return NULL;
137 	}
138 }
139 
140 static __be16 ppp_type_trans(struct sk_buff *skb, struct net_device *dev)
141 {
142 	struct hdlc_header *data = (struct hdlc_header *)skb->data;
143 
144 	if (skb->len < sizeof(struct hdlc_header))
145 		return htons(ETH_P_HDLC);
146 	if (data->address != HDLC_ADDR_ALLSTATIONS ||
147 	    data->control != HDLC_CTRL_UI)
148 		return htons(ETH_P_HDLC);
149 
150 	switch (data->protocol) {
151 	case cpu_to_be16(PID_IP):
152 		skb_pull(skb, sizeof(struct hdlc_header));
153 		return htons(ETH_P_IP);
154 
155 	case cpu_to_be16(PID_IPV6):
156 		skb_pull(skb, sizeof(struct hdlc_header));
157 		return htons(ETH_P_IPV6);
158 
159 	default:
160 		return htons(ETH_P_HDLC);
161 	}
162 }
163 
164 static int ppp_hard_header(struct sk_buff *skb, struct net_device *dev,
165 			   u16 type, const void *daddr, const void *saddr,
166 			   unsigned int len)
167 {
168 	struct hdlc_header *data;
169 #if DEBUG_HARD_HEADER
170 	printk(KERN_DEBUG "%s: ppp_hard_header() called\n", dev->name);
171 #endif
172 
173 	skb_push(skb, sizeof(struct hdlc_header));
174 	data = (struct hdlc_header *)skb->data;
175 
176 	data->address = HDLC_ADDR_ALLSTATIONS;
177 	data->control = HDLC_CTRL_UI;
178 	switch (type) {
179 	case ETH_P_IP:
180 		data->protocol = htons(PID_IP);
181 		break;
182 	case ETH_P_IPV6:
183 		data->protocol = htons(PID_IPV6);
184 		break;
185 	case PID_LCP:
186 	case PID_IPCP:
187 	case PID_IPV6CP:
188 		data->protocol = htons(type);
189 		break;
190 	default:		/* unknown protocol */
191 		data->protocol = 0;
192 	}
193 	return sizeof(struct hdlc_header);
194 }
195 
196 static void ppp_tx_flush(void)
197 {
198 	struct sk_buff *skb;
199 
200 	while ((skb = skb_dequeue(&tx_queue)) != NULL)
201 		dev_queue_xmit(skb);
202 }
203 
204 static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,
205 		      u8 id, unsigned int len, const void *data)
206 {
207 	struct sk_buff *skb;
208 	struct cp_header *cp;
209 	unsigned int magic_len = 0;
210 	static u32 magic;
211 
212 #if DEBUG_CP
213 	int i;
214 	char *ptr;
215 #endif
216 
217 	if (pid == PID_LCP && (code == LCP_ECHO_REQ || code == LCP_ECHO_REPLY))
218 		magic_len = sizeof(magic);
219 
220 	skb = dev_alloc_skb(sizeof(struct hdlc_header) +
221 			    sizeof(struct cp_header) + magic_len + len);
222 	if (!skb)
223 		return;
224 
225 	skb_reserve(skb, sizeof(struct hdlc_header));
226 
227 	cp = skb_put(skb, sizeof(struct cp_header));
228 	cp->code = code;
229 	cp->id = id;
230 	cp->len = htons(sizeof(struct cp_header) + magic_len + len);
231 
232 	if (magic_len)
233 		skb_put_data(skb, &magic, magic_len);
234 	if (len)
235 		skb_put_data(skb, data, len);
236 
237 #if DEBUG_CP
238 	BUG_ON(code >= CP_CODES);
239 	ptr = debug_buffer;
240 	*ptr = '\x0';
241 	for (i = 0; i < min_t(unsigned int, magic_len + len, DEBUG_CP); i++) {
242 		sprintf(ptr, " %02X", skb->data[sizeof(struct cp_header) + i]);
243 		ptr += strlen(ptr);
244 	}
245 	printk(KERN_DEBUG "%s: TX %s [%s id 0x%X]%s\n", dev->name,
246 	       proto_name(pid), code_names[code], id, debug_buffer);
247 #endif
248 
249 	ppp_hard_header(skb, dev, pid, NULL, NULL, 0);
250 
251 	skb->priority = TC_PRIO_CONTROL;
252 	skb->dev = dev;
253 	skb->protocol = htons(ETH_P_HDLC);
254 	skb_reset_network_header(skb);
255 	skb_queue_tail(&tx_queue, skb);
256 }
257 
258 /* State transition table (compare STD-51)
259    Events                                   Actions
260    TO+  = Timeout with counter > 0          irc = Initialize-Restart-Count
261    TO-  = Timeout with counter expired      zrc = Zero-Restart-Count
262 
263    RCR+ = Receive-Configure-Request (Good)  scr = Send-Configure-Request
264    RCR- = Receive-Configure-Request (Bad)
265    RCA  = Receive-Configure-Ack             sca = Send-Configure-Ack
266    RCN  = Receive-Configure-Nak/Rej         scn = Send-Configure-Nak/Rej
267 
268    RTR  = Receive-Terminate-Request         str = Send-Terminate-Request
269    RTA  = Receive-Terminate-Ack             sta = Send-Terminate-Ack
270 
271    RUC  = Receive-Unknown-Code              scj = Send-Code-Reject
272    RXJ+ = Receive-Code-Reject (permitted)
273        or Receive-Protocol-Reject
274    RXJ- = Receive-Code-Reject (catastrophic)
275        or Receive-Protocol-Reject
276 */
277 static int cp_table[EVENTS][STATES] = {
278 	/* CLOSED     STOPPED STOPPING REQ_SENT ACK_RECV ACK_SENT OPENED
279 	     0           1         2       3       4      5          6    */
280 	{IRC|SCR|3,     INV     , INV ,   INV   , INV ,  INV    ,   INV   }, /* START */
281 	{   INV   ,      0      ,  0  ,    0    ,  0  ,   0     ,    0    }, /* STOP */
282 	{   INV   ,     INV     ,STR|2,  SCR|3  ,SCR|3,  SCR|5  ,   INV   }, /* TO+ */
283 	{   INV   ,     INV     ,  1  ,    1    ,  1  ,    1    ,   INV   }, /* TO- */
284 	{  STA|0  ,IRC|SCR|SCA|5,  2  ,  SCA|5  ,SCA|6,  SCA|5  ,SCR|SCA|5}, /* RCR+ */
285 	{  STA|0  ,IRC|SCR|SCN|3,  2  ,  SCN|3  ,SCN|4,  SCN|3  ,SCR|SCN|3}, /* RCR- */
286 	{  STA|0  ,    STA|1    ,  2  ,  IRC|4  ,SCR|3,    6    , SCR|3   }, /* RCA */
287 	{  STA|0  ,    STA|1    ,  2  ,IRC|SCR|3,SCR|3,IRC|SCR|5, SCR|3   }, /* RCN */
288 	{  STA|0  ,    STA|1    ,STA|2,  STA|3  ,STA|3,  STA|3  ,ZRC|STA|2}, /* RTR */
289 	{    0    ,      1      ,  1  ,    3    ,  3  ,    5    ,  SCR|3  }, /* RTA */
290 	{  SCJ|0  ,    SCJ|1    ,SCJ|2,  SCJ|3  ,SCJ|4,  SCJ|5  ,  SCJ|6  }, /* RUC */
291 	{    0    ,      1      ,  2  ,    3    ,  3  ,    5    ,    6    }, /* RXJ+ */
292 	{    0    ,      1      ,  1  ,    1    ,  1  ,    1    ,IRC|STR|2}, /* RXJ- */
293 };
294 
295 /* SCA: RCR+ must supply id, len and data
296    SCN: RCR- must supply code, id, len and data
297    STA: RTR must supply id
298    SCJ: RUC must supply CP packet len and data */
299 static void ppp_cp_event(struct net_device *dev, u16 pid, u16 event, u8 code,
300 			 u8 id, unsigned int len, const void *data)
301 {
302 	int old_state, action;
303 	struct ppp *ppp = get_ppp(dev);
304 	struct proto *proto = get_proto(dev, pid);
305 
306 	old_state = proto->state;
307 	BUG_ON(old_state >= STATES);
308 	BUG_ON(event >= EVENTS);
309 
310 #if DEBUG_STATE
311 	printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) %s ...\n", dev->name,
312 	       proto_name(pid), event_names[event], state_names[proto->state]);
313 #endif
314 
315 	action = cp_table[event][old_state];
316 
317 	proto->state = action & STATE_MASK;
318 	if (action & (SCR | STR)) /* set Configure-Req/Terminate-Req timer */
319 		mod_timer(&proto->timer, proto->timeout =
320 			  jiffies + ppp->req_timeout * HZ);
321 	if (action & ZRC)
322 		proto->restart_counter = 0;
323 	if (action & IRC)
324 		proto->restart_counter = (proto->state == STOPPING) ?
325 			ppp->term_retries : ppp->cr_retries;
326 
327 	if (action & SCR)	/* send Configure-Request */
328 		ppp_tx_cp(dev, pid, CP_CONF_REQ, proto->cr_id = ++ppp->seq,
329 			  0, NULL);
330 	if (action & SCA)	/* send Configure-Ack */
331 		ppp_tx_cp(dev, pid, CP_CONF_ACK, id, len, data);
332 	if (action & SCN)	/* send Configure-Nak/Reject */
333 		ppp_tx_cp(dev, pid, code, id, len, data);
334 	if (action & STR)	/* send Terminate-Request */
335 		ppp_tx_cp(dev, pid, CP_TERM_REQ, ++ppp->seq, 0, NULL);
336 	if (action & STA)	/* send Terminate-Ack */
337 		ppp_tx_cp(dev, pid, CP_TERM_ACK, id, 0, NULL);
338 	if (action & SCJ)	/* send Code-Reject */
339 		ppp_tx_cp(dev, pid, CP_CODE_REJ, ++ppp->seq, len, data);
340 
341 	if (old_state != OPENED && proto->state == OPENED) {
342 		netdev_info(dev, "%s up\n", proto_name(pid));
343 		if (pid == PID_LCP) {
344 			netif_dormant_off(dev);
345 			ppp_cp_event(dev, PID_IPCP, START, 0, 0, 0, NULL);
346 			ppp_cp_event(dev, PID_IPV6CP, START, 0, 0, 0, NULL);
347 			ppp->last_pong = jiffies;
348 			mod_timer(&proto->timer, proto->timeout =
349 				  jiffies + ppp->keepalive_interval * HZ);
350 		}
351 	}
352 	if (old_state == OPENED && proto->state != OPENED) {
353 		netdev_info(dev, "%s down\n", proto_name(pid));
354 		if (pid == PID_LCP) {
355 			netif_dormant_on(dev);
356 			ppp_cp_event(dev, PID_IPCP, STOP, 0, 0, 0, NULL);
357 			ppp_cp_event(dev, PID_IPV6CP, STOP, 0, 0, 0, NULL);
358 		}
359 	}
360 	if (old_state != CLOSED && proto->state == CLOSED)
361 		del_timer(&proto->timer);
362 
363 #if DEBUG_STATE
364 	printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) ... %s\n", dev->name,
365 	       proto_name(pid), event_names[event], state_names[proto->state]);
366 #endif
367 }
368 
369 static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id,
370 			    unsigned int req_len, const u8 *data)
371 {
372 	static u8 const valid_accm[6] = { LCP_OPTION_ACCM, 6, 0, 0, 0, 0 };
373 	const u8 *opt;
374 	u8 *out;
375 	unsigned int len = req_len, nak_len = 0, rej_len = 0;
376 
377 	out = kmalloc(len, GFP_ATOMIC);
378 	if (!out) {
379 		dev->stats.rx_dropped++;
380 		return;	/* out of memory, ignore CR packet */
381 	}
382 
383 	for (opt = data; len; len -= opt[1], opt += opt[1]) {
384 		if (len < 2 || opt[1] < 2 || len < opt[1])
385 			goto err_out;
386 
387 		if (pid == PID_LCP)
388 			switch (opt[0]) {
389 			case LCP_OPTION_MRU:
390 				continue; /* MRU always OK and > 1500 bytes? */
391 
392 			case LCP_OPTION_ACCM: /* async control character map */
393 				if (opt[1] < sizeof(valid_accm))
394 					goto err_out;
395 				if (!memcmp(opt, valid_accm,
396 					    sizeof(valid_accm)))
397 					continue;
398 				if (!rej_len) { /* NAK it */
399 					memcpy(out + nak_len, valid_accm,
400 					       sizeof(valid_accm));
401 					nak_len += sizeof(valid_accm);
402 					continue;
403 				}
404 				break;
405 			case LCP_OPTION_MAGIC:
406 				if (len < 6)
407 					goto err_out;
408 				if (opt[1] != 6 || (!opt[2] && !opt[3] &&
409 						    !opt[4] && !opt[5]))
410 					break; /* reject invalid magic number */
411 				continue;
412 			}
413 		/* reject this option */
414 		memcpy(out + rej_len, opt, opt[1]);
415 		rej_len += opt[1];
416 	}
417 
418 	if (rej_len)
419 		ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_REJ, id, rej_len, out);
420 	else if (nak_len)
421 		ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_NAK, id, nak_len, out);
422 	else
423 		ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data);
424 
425 	kfree(out);
426 	return;
427 
428 err_out:
429 	dev->stats.rx_errors++;
430 	kfree(out);
431 }
432 
433 static int ppp_rx(struct sk_buff *skb)
434 {
435 	struct hdlc_header *hdr = (struct hdlc_header *)skb->data;
436 	struct net_device *dev = skb->dev;
437 	struct ppp *ppp = get_ppp(dev);
438 	struct proto *proto;
439 	struct cp_header *cp;
440 	unsigned long flags;
441 	unsigned int len;
442 	u16 pid;
443 #if DEBUG_CP
444 	int i;
445 	char *ptr;
446 #endif
447 
448 	spin_lock_irqsave(&ppp->lock, flags);
449 	/* Check HDLC header */
450 	if (skb->len < sizeof(struct hdlc_header))
451 		goto rx_error;
452 	cp = skb_pull(skb, sizeof(struct hdlc_header));
453 	if (hdr->address != HDLC_ADDR_ALLSTATIONS ||
454 	    hdr->control != HDLC_CTRL_UI)
455 		goto rx_error;
456 
457 	pid = ntohs(hdr->protocol);
458 	proto = get_proto(dev, pid);
459 	if (!proto) {
460 		if (ppp->protos[IDX_LCP].state == OPENED)
461 			ppp_tx_cp(dev, PID_LCP, LCP_PROTO_REJ,
462 				  ++ppp->seq, skb->len + 2, &hdr->protocol);
463 		goto rx_error;
464 	}
465 
466 	len = ntohs(cp->len);
467 	if (len < sizeof(struct cp_header) /* no complete CP header? */ ||
468 	    skb->len < len /* truncated packet? */)
469 		goto rx_error;
470 	skb_pull(skb, sizeof(struct cp_header));
471 	len -= sizeof(struct cp_header);
472 
473 	/* HDLC and CP headers stripped from skb */
474 #if DEBUG_CP
475 	if (cp->code < CP_CODES)
476 		sprintf(debug_buffer, "[%s id 0x%X]", code_names[cp->code],
477 			cp->id);
478 	else
479 		sprintf(debug_buffer, "[code %u id 0x%X]", cp->code, cp->id);
480 	ptr = debug_buffer + strlen(debug_buffer);
481 	for (i = 0; i < min_t(unsigned int, len, DEBUG_CP); i++) {
482 		sprintf(ptr, " %02X", skb->data[i]);
483 		ptr += strlen(ptr);
484 	}
485 	printk(KERN_DEBUG "%s: RX %s %s\n", dev->name, proto_name(pid),
486 	       debug_buffer);
487 #endif
488 
489 	/* LCP only */
490 	if (pid == PID_LCP)
491 		switch (cp->code) {
492 		case LCP_PROTO_REJ:
493 			pid = ntohs(*(__be16 *)skb->data);
494 			if (pid == PID_LCP || pid == PID_IPCP ||
495 			    pid == PID_IPV6CP)
496 				ppp_cp_event(dev, pid, RXJ_BAD, 0, 0,
497 					     0, NULL);
498 			goto out;
499 
500 		case LCP_ECHO_REQ: /* send Echo-Reply */
501 			if (len >= 4 && proto->state == OPENED)
502 				ppp_tx_cp(dev, PID_LCP, LCP_ECHO_REPLY,
503 					  cp->id, len - 4, skb->data + 4);
504 			goto out;
505 
506 		case LCP_ECHO_REPLY:
507 			if (cp->id == ppp->echo_id)
508 				ppp->last_pong = jiffies;
509 			goto out;
510 
511 		case LCP_DISC_REQ: /* discard */
512 			goto out;
513 		}
514 
515 	/* LCP, IPCP and IPV6CP */
516 	switch (cp->code) {
517 	case CP_CONF_REQ:
518 		ppp_cp_parse_cr(dev, pid, cp->id, len, skb->data);
519 		break;
520 
521 	case CP_CONF_ACK:
522 		if (cp->id == proto->cr_id)
523 			ppp_cp_event(dev, pid, RCA, 0, 0, 0, NULL);
524 		break;
525 
526 	case CP_CONF_REJ:
527 	case CP_CONF_NAK:
528 		if (cp->id == proto->cr_id)
529 			ppp_cp_event(dev, pid, RCN, 0, 0, 0, NULL);
530 		break;
531 
532 	case CP_TERM_REQ:
533 		ppp_cp_event(dev, pid, RTR, 0, cp->id, 0, NULL);
534 		break;
535 
536 	case CP_TERM_ACK:
537 		ppp_cp_event(dev, pid, RTA, 0, 0, 0, NULL);
538 		break;
539 
540 	case CP_CODE_REJ:
541 		ppp_cp_event(dev, pid, RXJ_BAD, 0, 0, 0, NULL);
542 		break;
543 
544 	default:
545 		len += sizeof(struct cp_header);
546 		if (len > dev->mtu)
547 			len = dev->mtu;
548 		ppp_cp_event(dev, pid, RUC, 0, 0, len, cp);
549 		break;
550 	}
551 	goto out;
552 
553 rx_error:
554 	dev->stats.rx_errors++;
555 out:
556 	spin_unlock_irqrestore(&ppp->lock, flags);
557 	dev_kfree_skb_any(skb);
558 	ppp_tx_flush();
559 	return NET_RX_DROP;
560 }
561 
562 static void ppp_timer(struct timer_list *t)
563 {
564 	struct proto *proto = from_timer(proto, t, timer);
565 	struct ppp *ppp = get_ppp(proto->dev);
566 	unsigned long flags;
567 
568 	spin_lock_irqsave(&ppp->lock, flags);
569 	/* mod_timer could be called after we entered this function but
570 	 * before we got the lock.
571 	 */
572 	if (timer_pending(&proto->timer)) {
573 		spin_unlock_irqrestore(&ppp->lock, flags);
574 		return;
575 	}
576 	switch (proto->state) {
577 	case STOPPING:
578 	case REQ_SENT:
579 	case ACK_RECV:
580 	case ACK_SENT:
581 		if (proto->restart_counter) {
582 			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
583 				     0, NULL);
584 			proto->restart_counter--;
585 		} else if (netif_carrier_ok(proto->dev))
586 			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
587 				     0, NULL);
588 		else
589 			ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
590 				     0, NULL);
591 		break;
592 
593 	case OPENED:
594 		if (proto->pid != PID_LCP)
595 			break;
596 		if (time_after(jiffies, ppp->last_pong +
597 			       ppp->keepalive_timeout * HZ)) {
598 			netdev_info(proto->dev, "Link down\n");
599 			ppp_cp_event(proto->dev, PID_LCP, STOP, 0, 0, 0, NULL);
600 			ppp_cp_event(proto->dev, PID_LCP, START, 0, 0, 0, NULL);
601 		} else {	/* send keep-alive packet */
602 			ppp->echo_id = ++ppp->seq;
603 			ppp_tx_cp(proto->dev, PID_LCP, LCP_ECHO_REQ,
604 				  ppp->echo_id, 0, NULL);
605 			proto->timer.expires = jiffies +
606 				ppp->keepalive_interval * HZ;
607 			add_timer(&proto->timer);
608 		}
609 		break;
610 	}
611 	spin_unlock_irqrestore(&ppp->lock, flags);
612 	ppp_tx_flush();
613 }
614 
615 static void ppp_start(struct net_device *dev)
616 {
617 	struct ppp *ppp = get_ppp(dev);
618 	int i;
619 
620 	for (i = 0; i < IDX_COUNT; i++) {
621 		struct proto *proto = &ppp->protos[i];
622 
623 		proto->dev = dev;
624 		timer_setup(&proto->timer, ppp_timer, 0);
625 		proto->state = CLOSED;
626 	}
627 	ppp->protos[IDX_LCP].pid = PID_LCP;
628 	ppp->protos[IDX_IPCP].pid = PID_IPCP;
629 	ppp->protos[IDX_IPV6CP].pid = PID_IPV6CP;
630 
631 	ppp_cp_event(dev, PID_LCP, START, 0, 0, 0, NULL);
632 }
633 
634 static void ppp_stop(struct net_device *dev)
635 {
636 	ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
637 }
638 
639 static void ppp_close(struct net_device *dev)
640 {
641 	ppp_tx_flush();
642 }
643 
644 static struct hdlc_proto proto = {
645 	.start		= ppp_start,
646 	.stop		= ppp_stop,
647 	.close		= ppp_close,
648 	.type_trans	= ppp_type_trans,
649 	.ioctl		= ppp_ioctl,
650 	.netif_rx	= ppp_rx,
651 	.module		= THIS_MODULE,
652 };
653 
654 static const struct header_ops ppp_header_ops = {
655 	.create = ppp_hard_header,
656 };
657 
658 static int ppp_ioctl(struct net_device *dev, struct if_settings *ifs)
659 {
660 	hdlc_device *hdlc = dev_to_hdlc(dev);
661 	struct ppp *ppp;
662 	int result;
663 
664 	switch (ifs->type) {
665 	case IF_GET_PROTO:
666 		if (dev_to_hdlc(dev)->proto != &proto)
667 			return -EINVAL;
668 		ifs->type = IF_PROTO_PPP;
669 		return 0; /* return protocol only, no settable parameters */
670 
671 	case IF_PROTO_PPP:
672 		if (!capable(CAP_NET_ADMIN))
673 			return -EPERM;
674 
675 		if (dev->flags & IFF_UP)
676 			return -EBUSY;
677 
678 		/* no settable parameters */
679 
680 		result = hdlc->attach(dev, ENCODING_NRZ,
681 				      PARITY_CRC16_PR1_CCITT);
682 		if (result)
683 			return result;
684 
685 		result = attach_hdlc_protocol(dev, &proto, sizeof(struct ppp));
686 		if (result)
687 			return result;
688 
689 		ppp = get_ppp(dev);
690 		spin_lock_init(&ppp->lock);
691 		ppp->req_timeout = 2;
692 		ppp->cr_retries = 10;
693 		ppp->term_retries = 2;
694 		ppp->keepalive_interval = 10;
695 		ppp->keepalive_timeout = 60;
696 
697 		dev->hard_header_len = sizeof(struct hdlc_header);
698 		dev->header_ops = &ppp_header_ops;
699 		dev->type = ARPHRD_PPP;
700 		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
701 		netif_dormant_on(dev);
702 		return 0;
703 	}
704 
705 	return -EINVAL;
706 }
707 
708 static int __init hdlc_ppp_init(void)
709 {
710 	skb_queue_head_init(&tx_queue);
711 	register_hdlc_protocol(&proto);
712 	return 0;
713 }
714 
715 static void __exit hdlc_ppp_exit(void)
716 {
717 	unregister_hdlc_protocol(&proto);
718 }
719 
720 module_init(hdlc_ppp_init);
721 module_exit(hdlc_ppp_exit);
722 
723 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
724 MODULE_DESCRIPTION("PPP protocol support for generic HDLC");
725 MODULE_LICENSE("GPL v2");
726