xref: /linux/drivers/net/wan/hdlc_cisco.c (revision 762f99f4f3cb41a775b5157dd761217beba65873)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Generic HDLC support routines for Linux
4  * Cisco HDLC support
5  *
6  * Copyright (C) 2000 - 2006 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/rtnetlink.h>
19 #include <linux/skbuff.h>
20 
21 #undef DEBUG_HARD_HEADER
22 
23 #define CISCO_MULTICAST		0x8F	/* Cisco multicast address */
24 #define CISCO_UNICAST		0x0F	/* Cisco unicast address */
25 #define CISCO_KEEPALIVE		0x8035	/* Cisco keepalive protocol */
26 #define CISCO_SYS_INFO		0x2000	/* Cisco interface/system info */
27 #define CISCO_ADDR_REQ		0	/* Cisco address request */
28 #define CISCO_ADDR_REPLY	1	/* Cisco address reply */
29 #define CISCO_KEEPALIVE_REQ	2	/* Cisco keepalive request */
30 
31 struct hdlc_header {
32 	u8 address;
33 	u8 control;
34 	__be16 protocol;
35 } __packed;
36 
37 struct cisco_packet {
38 	__be32 type;		/* code */
39 	__be32 par1;
40 	__be32 par2;
41 	__be16 rel;		/* reliability */
42 	__be32 time;
43 } __packed;
44 #define	CISCO_PACKET_LEN	18
45 #define	CISCO_BIG_PACKET_LEN	20
46 
47 struct cisco_state {
48 	cisco_proto settings;
49 
50 	struct timer_list timer;
51 	struct net_device *dev;
52 	spinlock_t lock;
53 	unsigned long last_poll;
54 	int up;
55 	u32 txseq; /* TX sequence number, 0 = none */
56 	u32 rxseq; /* RX sequence number */
57 };
58 
59 static int cisco_ioctl(struct net_device *dev, struct if_settings *ifs);
60 
state(hdlc_device * hdlc)61 static inline struct cisco_state *state(hdlc_device *hdlc)
62 {
63 	return (struct cisco_state *)hdlc->state;
64 }
65 
cisco_hard_header(struct sk_buff * skb,struct net_device * dev,u16 type,const void * daddr,const void * saddr,unsigned int len)66 static int cisco_hard_header(struct sk_buff *skb, struct net_device *dev,
67 			     u16 type, const void *daddr, const void *saddr,
68 			     unsigned int len)
69 {
70 	struct hdlc_header *data;
71 #ifdef DEBUG_HARD_HEADER
72 	netdev_dbg(dev, "%s called\n", __func__);
73 #endif
74 
75 	skb_push(skb, sizeof(struct hdlc_header));
76 	data = (struct hdlc_header *)skb->data;
77 	if (type == CISCO_KEEPALIVE)
78 		data->address = CISCO_MULTICAST;
79 	else
80 		data->address = CISCO_UNICAST;
81 	data->control = 0;
82 	data->protocol = htons(type);
83 
84 	return sizeof(struct hdlc_header);
85 }
86 
cisco_keepalive_send(struct net_device * dev,u32 type,__be32 par1,__be32 par2)87 static void cisco_keepalive_send(struct net_device *dev, u32 type,
88 				 __be32 par1, __be32 par2)
89 {
90 	struct sk_buff *skb;
91 	struct cisco_packet *data;
92 
93 	skb = dev_alloc_skb(sizeof(struct hdlc_header) +
94 			    sizeof(struct cisco_packet));
95 	if (!skb)
96 		return;
97 
98 	skb_reserve(skb, 4);
99 	cisco_hard_header(skb, dev, CISCO_KEEPALIVE, NULL, NULL, 0);
100 	data = (struct cisco_packet *)(skb->data + 4);
101 
102 	data->type = htonl(type);
103 	data->par1 = par1;
104 	data->par2 = par2;
105 	data->rel = cpu_to_be16(0xFFFF);
106 	/* we will need do_div here if 1000 % HZ != 0 */
107 	data->time = htonl((jiffies - INITIAL_JIFFIES) * (1000 / HZ));
108 
109 	skb_put(skb, sizeof(struct cisco_packet));
110 	skb->priority = TC_PRIO_CONTROL;
111 	skb->dev = dev;
112 	skb->protocol = htons(ETH_P_HDLC);
113 	skb_reset_network_header(skb);
114 
115 	dev_queue_xmit(skb);
116 }
117 
cisco_type_trans(struct sk_buff * skb,struct net_device * dev)118 static __be16 cisco_type_trans(struct sk_buff *skb, struct net_device *dev)
119 {
120 	struct hdlc_header *data = (struct hdlc_header *)skb->data;
121 
122 	if (skb->len < sizeof(struct hdlc_header))
123 		return cpu_to_be16(ETH_P_HDLC);
124 
125 	if (data->address != CISCO_MULTICAST &&
126 	    data->address != CISCO_UNICAST)
127 		return cpu_to_be16(ETH_P_HDLC);
128 
129 	switch (data->protocol) {
130 	case cpu_to_be16(ETH_P_IP):
131 	case cpu_to_be16(ETH_P_IPX):
132 	case cpu_to_be16(ETH_P_IPV6):
133 		skb_pull(skb, sizeof(struct hdlc_header));
134 		return data->protocol;
135 	default:
136 		return cpu_to_be16(ETH_P_HDLC);
137 	}
138 }
139 
cisco_rx(struct sk_buff * skb)140 static int cisco_rx(struct sk_buff *skb)
141 {
142 	struct net_device *dev = skb->dev;
143 	hdlc_device *hdlc = dev_to_hdlc(dev);
144 	struct cisco_state *st = state(hdlc);
145 	struct hdlc_header *data = (struct hdlc_header *)skb->data;
146 	struct cisco_packet *cisco_data;
147 	struct in_device *in_dev;
148 	__be32 addr, mask;
149 	u32 ack;
150 
151 	if (skb->len < sizeof(struct hdlc_header))
152 		goto rx_error;
153 
154 	if (data->address != CISCO_MULTICAST &&
155 	    data->address != CISCO_UNICAST)
156 		goto rx_error;
157 
158 	switch (ntohs(data->protocol)) {
159 	case CISCO_SYS_INFO:
160 		/* Packet is not needed, drop it. */
161 		dev_kfree_skb_any(skb);
162 		return NET_RX_SUCCESS;
163 
164 	case CISCO_KEEPALIVE:
165 		if ((skb->len != sizeof(struct hdlc_header) +
166 		     CISCO_PACKET_LEN) &&
167 		    (skb->len != sizeof(struct hdlc_header) +
168 		     CISCO_BIG_PACKET_LEN)) {
169 			netdev_info(dev, "Invalid length of Cisco control packet (%d bytes)\n",
170 				    skb->len);
171 			goto rx_error;
172 		}
173 
174 		cisco_data = (struct cisco_packet *)(skb->data + sizeof
175 						    (struct hdlc_header));
176 
177 		switch (ntohl(cisco_data->type)) {
178 		case CISCO_ADDR_REQ: /* Stolen from syncppp.c :-) */
179 			rcu_read_lock();
180 			in_dev = __in_dev_get_rcu(dev);
181 			addr = 0;
182 			mask = ~cpu_to_be32(0); /* is the mask correct? */
183 
184 			if (in_dev != NULL) {
185 				const struct in_ifaddr *ifa;
186 
187 				in_dev_for_each_ifa_rcu(ifa, in_dev) {
188 					if (strcmp(dev->name,
189 						   ifa->ifa_label) == 0) {
190 						addr = ifa->ifa_local;
191 						mask = ifa->ifa_mask;
192 						break;
193 					}
194 				}
195 
196 				cisco_keepalive_send(dev, CISCO_ADDR_REPLY,
197 						     addr, mask);
198 			}
199 			rcu_read_unlock();
200 			dev_kfree_skb_any(skb);
201 			return NET_RX_SUCCESS;
202 
203 		case CISCO_ADDR_REPLY:
204 			netdev_info(dev, "Unexpected Cisco IP address reply\n");
205 			goto rx_error;
206 
207 		case CISCO_KEEPALIVE_REQ:
208 			spin_lock(&st->lock);
209 			st->rxseq = ntohl(cisco_data->par1);
210 			ack = ntohl(cisco_data->par2);
211 			if (ack && (ack == st->txseq ||
212 				    /* our current REQ may be in transit */
213 				    ack == st->txseq - 1)) {
214 				st->last_poll = jiffies;
215 				if (!st->up) {
216 					u32 sec, min, hrs, days;
217 
218 					sec = ntohl(cisco_data->time) / 1000;
219 					min = sec / 60; sec -= min * 60;
220 					hrs = min / 60; min -= hrs * 60;
221 					days = hrs / 24; hrs -= days * 24;
222 					netdev_info(dev, "Link up (peer uptime %ud%uh%um%us)\n",
223 						    days, hrs, min, sec);
224 					netif_dormant_off(dev);
225 					st->up = 1;
226 				}
227 			}
228 			spin_unlock(&st->lock);
229 
230 			dev_kfree_skb_any(skb);
231 			return NET_RX_SUCCESS;
232 		} /* switch (keepalive type) */
233 	} /* switch (protocol) */
234 
235 	netdev_info(dev, "Unsupported protocol %x\n", ntohs(data->protocol));
236 	dev_kfree_skb_any(skb);
237 	return NET_RX_DROP;
238 
239 rx_error:
240 	dev->stats.rx_errors++; /* Mark error */
241 	dev_kfree_skb_any(skb);
242 	return NET_RX_DROP;
243 }
244 
cisco_timer(struct timer_list * t)245 static void cisco_timer(struct timer_list *t)
246 {
247 	struct cisco_state *st = from_timer(st, t, timer);
248 	struct net_device *dev = st->dev;
249 
250 	spin_lock(&st->lock);
251 	if (st->up &&
252 	    time_after(jiffies, st->last_poll + st->settings.timeout * HZ)) {
253 		st->up = 0;
254 		netdev_info(dev, "Link down\n");
255 		netif_dormant_on(dev);
256 	}
257 
258 	cisco_keepalive_send(dev, CISCO_KEEPALIVE_REQ, htonl(++st->txseq),
259 			     htonl(st->rxseq));
260 	spin_unlock(&st->lock);
261 
262 	st->timer.expires = jiffies + st->settings.interval * HZ;
263 	add_timer(&st->timer);
264 }
265 
cisco_start(struct net_device * dev)266 static void cisco_start(struct net_device *dev)
267 {
268 	hdlc_device *hdlc = dev_to_hdlc(dev);
269 	struct cisco_state *st = state(hdlc);
270 	unsigned long flags;
271 
272 	spin_lock_irqsave(&st->lock, flags);
273 	st->up = st->txseq = st->rxseq = 0;
274 	spin_unlock_irqrestore(&st->lock, flags);
275 
276 	st->dev = dev;
277 	timer_setup(&st->timer, cisco_timer, 0);
278 	st->timer.expires = jiffies + HZ; /* First poll after 1 s */
279 	add_timer(&st->timer);
280 }
281 
cisco_stop(struct net_device * dev)282 static void cisco_stop(struct net_device *dev)
283 {
284 	hdlc_device *hdlc = dev_to_hdlc(dev);
285 	struct cisco_state *st = state(hdlc);
286 	unsigned long flags;
287 
288 	del_timer_sync(&st->timer);
289 
290 	spin_lock_irqsave(&st->lock, flags);
291 	netif_dormant_on(dev);
292 	st->up = st->txseq = 0;
293 	spin_unlock_irqrestore(&st->lock, flags);
294 }
295 
296 static struct hdlc_proto proto = {
297 	.start		= cisco_start,
298 	.stop		= cisco_stop,
299 	.type_trans	= cisco_type_trans,
300 	.ioctl		= cisco_ioctl,
301 	.netif_rx	= cisco_rx,
302 	.module		= THIS_MODULE,
303 };
304 
305 static const struct header_ops cisco_header_ops = {
306 	.create = cisco_hard_header,
307 };
308 
cisco_ioctl(struct net_device * dev,struct if_settings * ifs)309 static int cisco_ioctl(struct net_device *dev, struct if_settings *ifs)
310 {
311 	cisco_proto __user *cisco_s = ifs->ifs_ifsu.cisco;
312 	const size_t size = sizeof(cisco_proto);
313 	cisco_proto new_settings;
314 	hdlc_device *hdlc = dev_to_hdlc(dev);
315 	int result;
316 
317 	switch (ifs->type) {
318 	case IF_GET_PROTO:
319 		if (dev_to_hdlc(dev)->proto != &proto)
320 			return -EINVAL;
321 		ifs->type = IF_PROTO_CISCO;
322 		if (ifs->size < size) {
323 			ifs->size = size; /* data size wanted */
324 			return -ENOBUFS;
325 		}
326 		if (copy_to_user(cisco_s, &state(hdlc)->settings, size))
327 			return -EFAULT;
328 		return 0;
329 
330 	case IF_PROTO_CISCO:
331 		if (!capable(CAP_NET_ADMIN))
332 			return -EPERM;
333 
334 		if (dev->flags & IFF_UP)
335 			return -EBUSY;
336 
337 		if (copy_from_user(&new_settings, cisco_s, size))
338 			return -EFAULT;
339 
340 		if (new_settings.interval < 1 ||
341 		    new_settings.timeout < 2)
342 			return -EINVAL;
343 
344 		result = hdlc->attach(dev, ENCODING_NRZ,
345 				      PARITY_CRC16_PR1_CCITT);
346 		if (result)
347 			return result;
348 
349 		result = attach_hdlc_protocol(dev, &proto,
350 					      sizeof(struct cisco_state));
351 		if (result)
352 			return result;
353 
354 		memcpy(&state(hdlc)->settings, &new_settings, size);
355 		spin_lock_init(&state(hdlc)->lock);
356 		dev->header_ops = &cisco_header_ops;
357 		dev->hard_header_len = sizeof(struct hdlc_header);
358 		dev->type = ARPHRD_CISCO;
359 		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
360 		netif_dormant_on(dev);
361 		return 0;
362 	}
363 
364 	return -EINVAL;
365 }
366 
hdlc_cisco_init(void)367 static int __init hdlc_cisco_init(void)
368 {
369 	register_hdlc_protocol(&proto);
370 	return 0;
371 }
372 
hdlc_cisco_exit(void)373 static void __exit hdlc_cisco_exit(void)
374 {
375 	unregister_hdlc_protocol(&proto);
376 }
377 
378 module_init(hdlc_cisco_init);
379 module_exit(hdlc_cisco_exit);
380 
381 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
382 MODULE_DESCRIPTION("Cisco HDLC protocol support for generic HDLC");
383 MODULE_LICENSE("GPL v2");
384