xref: /openbmc/linux/net/phonet/af_phonet.c (revision 4800cd83)
1 /*
2  * File: af_phonet.c
3  *
4  * Phonet protocols family
5  *
6  * Copyright (C) 2008 Nokia Corporation.
7  *
8  * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
9  * Original author: Sakari Ailus <sakari.ailus@nokia.com>
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License
13  * version 2 as published by the Free Software Foundation.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
23  * 02110-1301 USA
24  */
25 
26 #include <linux/kernel.h>
27 #include <linux/module.h>
28 #include <linux/slab.h>
29 #include <asm/unaligned.h>
30 #include <net/sock.h>
31 
32 #include <linux/if_phonet.h>
33 #include <linux/phonet.h>
34 #include <net/phonet/phonet.h>
35 #include <net/phonet/pn_dev.h>
36 
37 /* Transport protocol registration */
38 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
39 
40 static struct phonet_protocol *phonet_proto_get(unsigned int protocol)
41 {
42 	struct phonet_protocol *pp;
43 
44 	if (protocol >= PHONET_NPROTO)
45 		return NULL;
46 
47 	rcu_read_lock();
48 	pp = rcu_dereference(proto_tab[protocol]);
49 	if (pp && !try_module_get(pp->prot->owner))
50 		pp = NULL;
51 	rcu_read_unlock();
52 
53 	return pp;
54 }
55 
56 static inline void phonet_proto_put(struct phonet_protocol *pp)
57 {
58 	module_put(pp->prot->owner);
59 }
60 
61 /* protocol family functions */
62 
63 static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
64 			    int kern)
65 {
66 	struct sock *sk;
67 	struct pn_sock *pn;
68 	struct phonet_protocol *pnp;
69 	int err;
70 
71 	if (!capable(CAP_SYS_ADMIN))
72 		return -EPERM;
73 
74 	if (protocol == 0) {
75 		/* Default protocol selection */
76 		switch (sock->type) {
77 		case SOCK_DGRAM:
78 			protocol = PN_PROTO_PHONET;
79 			break;
80 		case SOCK_SEQPACKET:
81 			protocol = PN_PROTO_PIPE;
82 			break;
83 		default:
84 			return -EPROTONOSUPPORT;
85 		}
86 	}
87 
88 	pnp = phonet_proto_get(protocol);
89 	if (pnp == NULL &&
90 	    request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
91 		pnp = phonet_proto_get(protocol);
92 
93 	if (pnp == NULL)
94 		return -EPROTONOSUPPORT;
95 	if (sock->type != pnp->sock_type) {
96 		err = -EPROTONOSUPPORT;
97 		goto out;
98 	}
99 
100 	sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
101 	if (sk == NULL) {
102 		err = -ENOMEM;
103 		goto out;
104 	}
105 
106 	sock_init_data(sock, sk);
107 	sock->state = SS_UNCONNECTED;
108 	sock->ops = pnp->ops;
109 	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
110 	sk->sk_protocol = protocol;
111 	pn = pn_sk(sk);
112 	pn->sobject = 0;
113 	pn->resource = 0;
114 	sk->sk_prot->init(sk);
115 	err = 0;
116 
117 out:
118 	phonet_proto_put(pnp);
119 	return err;
120 }
121 
122 static const struct net_proto_family phonet_proto_family = {
123 	.family = PF_PHONET,
124 	.create = pn_socket_create,
125 	.owner = THIS_MODULE,
126 };
127 
128 /* Phonet device header operations */
129 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
130 				unsigned short type, const void *daddr,
131 				const void *saddr, unsigned len)
132 {
133 	u8 *media = skb_push(skb, 1);
134 
135 	if (type != ETH_P_PHONET)
136 		return -1;
137 
138 	if (!saddr)
139 		saddr = dev->dev_addr;
140 	*media = *(const u8 *)saddr;
141 	return 1;
142 }
143 
144 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
145 {
146 	const u8 *media = skb_mac_header(skb);
147 	*haddr = *media;
148 	return 1;
149 }
150 
151 struct header_ops phonet_header_ops = {
152 	.create = pn_header_create,
153 	.parse = pn_header_parse,
154 };
155 EXPORT_SYMBOL(phonet_header_ops);
156 
157 /*
158  * Prepends an ISI header and sends a datagram.
159  */
160 static int pn_send(struct sk_buff *skb, struct net_device *dev,
161 			u16 dst, u16 src, u8 res, u8 irq)
162 {
163 	struct phonethdr *ph;
164 	int err;
165 
166 	if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
167 	    skb->len + sizeof(struct phonethdr) > dev->mtu) {
168 		err = -EMSGSIZE;
169 		goto drop;
170 	}
171 
172 	/* Broadcast sending is not implemented */
173 	if (pn_addr(dst) == PNADDR_BROADCAST) {
174 		err = -EOPNOTSUPP;
175 		goto drop;
176 	}
177 
178 	skb_reset_transport_header(skb);
179 	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
180 	skb_push(skb, sizeof(struct phonethdr));
181 	skb_reset_network_header(skb);
182 	ph = pn_hdr(skb);
183 	ph->pn_rdev = pn_dev(dst);
184 	ph->pn_sdev = pn_dev(src);
185 	ph->pn_res = res;
186 	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
187 	ph->pn_robj = pn_obj(dst);
188 	ph->pn_sobj = pn_obj(src);
189 
190 	skb->protocol = htons(ETH_P_PHONET);
191 	skb->priority = 0;
192 	skb->dev = dev;
193 
194 	if (skb->pkt_type == PACKET_LOOPBACK) {
195 		skb_reset_mac_header(skb);
196 		skb_orphan(skb);
197 		if (irq)
198 			netif_rx(skb);
199 		else
200 			netif_rx_ni(skb);
201 		err = 0;
202 	} else {
203 		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
204 					NULL, NULL, skb->len);
205 		if (err < 0) {
206 			err = -EHOSTUNREACH;
207 			goto drop;
208 		}
209 		err = dev_queue_xmit(skb);
210 	}
211 
212 	return err;
213 drop:
214 	kfree_skb(skb);
215 	return err;
216 }
217 
218 static int pn_raw_send(const void *data, int len, struct net_device *dev,
219 			u16 dst, u16 src, u8 res)
220 {
221 	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
222 	if (skb == NULL)
223 		return -ENOMEM;
224 
225 	if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
226 		skb->pkt_type = PACKET_LOOPBACK;
227 
228 	skb_reserve(skb, MAX_PHONET_HEADER);
229 	__skb_put(skb, len);
230 	skb_copy_to_linear_data(skb, data, len);
231 	return pn_send(skb, dev, dst, src, res, 1);
232 }
233 
234 /*
235  * Create a Phonet header for the skb and send it out. Returns
236  * non-zero error code if failed. The skb is freed then.
237  */
238 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
239 		const struct sockaddr_pn *target)
240 {
241 	struct net *net = sock_net(sk);
242 	struct net_device *dev;
243 	struct pn_sock *pn = pn_sk(sk);
244 	int err;
245 	u16 src;
246 	u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
247 
248 	err = -EHOSTUNREACH;
249 	if (sk->sk_bound_dev_if)
250 		dev = dev_get_by_index(net, sk->sk_bound_dev_if);
251 	else if (phonet_address_lookup(net, daddr) == 0) {
252 		dev = phonet_device_get(net);
253 		skb->pkt_type = PACKET_LOOPBACK;
254 	} else if (pn_sockaddr_get_object(target) == 0) {
255 		/* Resource routing (small race until phonet_rcv()) */
256 		struct sock *sk = pn_find_sock_by_res(net,
257 							target->spn_resource);
258 		if (sk)	{
259 			sock_put(sk);
260 			dev = phonet_device_get(net);
261 			skb->pkt_type = PACKET_LOOPBACK;
262 		} else
263 			dev = phonet_route_output(net, daddr);
264 	} else
265 		dev = phonet_route_output(net, daddr);
266 
267 	if (!dev || !(dev->flags & IFF_UP))
268 		goto drop;
269 
270 	saddr = phonet_address_get(dev, daddr);
271 	if (saddr == PN_NO_ADDR)
272 		goto drop;
273 
274 	src = pn->sobject;
275 	if (!pn_addr(src))
276 		src = pn_object(saddr, pn_obj(src));
277 
278 	err = pn_send(skb, dev, pn_sockaddr_get_object(target),
279 			src, pn_sockaddr_get_resource(target), 0);
280 	dev_put(dev);
281 	return err;
282 
283 drop:
284 	kfree_skb(skb);
285 	if (dev)
286 		dev_put(dev);
287 	return err;
288 }
289 EXPORT_SYMBOL(pn_skb_send);
290 
291 /* Do not send an error message in response to an error message */
292 static inline int can_respond(struct sk_buff *skb)
293 {
294 	const struct phonethdr *ph;
295 	const struct phonetmsg *pm;
296 	u8 submsg_id;
297 
298 	if (!pskb_may_pull(skb, 3))
299 		return 0;
300 
301 	ph = pn_hdr(skb);
302 	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
303 		return 0;
304 	if (ph->pn_res == PN_COMMGR) /* indications */
305 		return 0;
306 
307 	ph = pn_hdr(skb); /* re-acquires the pointer */
308 	pm = pn_msg(skb);
309 	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
310 		return 1;
311 	submsg_id = (ph->pn_res == PN_PREFIX)
312 		? pm->pn_e_submsg_id : pm->pn_submsg_id;
313 	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
314 		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
315 		return 1;
316 	return 0;
317 }
318 
319 static int send_obj_unreachable(struct sk_buff *rskb)
320 {
321 	const struct phonethdr *oph = pn_hdr(rskb);
322 	const struct phonetmsg *opm = pn_msg(rskb);
323 	struct phonetmsg resp;
324 
325 	memset(&resp, 0, sizeof(resp));
326 	resp.pn_trans_id = opm->pn_trans_id;
327 	resp.pn_msg_id = PN_COMMON_MESSAGE;
328 	if (oph->pn_res == PN_PREFIX) {
329 		resp.pn_e_res_id = opm->pn_e_res_id;
330 		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
331 		resp.pn_e_orig_msg_id = opm->pn_msg_id;
332 		resp.pn_e_status = 0;
333 	} else {
334 		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
335 		resp.pn_orig_msg_id = opm->pn_msg_id;
336 		resp.pn_status = 0;
337 	}
338 	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
339 				pn_object(oph->pn_sdev, oph->pn_sobj),
340 				pn_object(oph->pn_rdev, oph->pn_robj),
341 				oph->pn_res);
342 }
343 
344 static int send_reset_indications(struct sk_buff *rskb)
345 {
346 	struct phonethdr *oph = pn_hdr(rskb);
347 	static const u8 data[4] = {
348 		0x00 /* trans ID */, 0x10 /* subscribe msg */,
349 		0x00 /* subscription count */, 0x00 /* dummy */
350 	};
351 
352 	return pn_raw_send(data, sizeof(data), rskb->dev,
353 				pn_object(oph->pn_sdev, 0x00),
354 				pn_object(oph->pn_rdev, oph->pn_robj),
355 				PN_COMMGR);
356 }
357 
358 
359 /* packet type functions */
360 
361 /*
362  * Stuff received packets to associated sockets.
363  * On error, returns non-zero and releases the skb.
364  */
365 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
366 			struct packet_type *pkttype,
367 			struct net_device *orig_dev)
368 {
369 	struct net *net = dev_net(dev);
370 	struct phonethdr *ph;
371 	struct sockaddr_pn sa;
372 	u16 len;
373 
374 	/* check we have at least a full Phonet header */
375 	if (!pskb_pull(skb, sizeof(struct phonethdr)))
376 		goto out;
377 
378 	/* check that the advertised length is correct */
379 	ph = pn_hdr(skb);
380 	len = get_unaligned_be16(&ph->pn_length);
381 	if (len < 2)
382 		goto out;
383 	len -= 2;
384 	if ((len > skb->len) || pskb_trim(skb, len))
385 		goto out;
386 	skb_reset_transport_header(skb);
387 
388 	pn_skb_get_dst_sockaddr(skb, &sa);
389 
390 	/* check if this is broadcasted */
391 	if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
392 		pn_deliver_sock_broadcast(net, skb);
393 		goto out;
394 	}
395 
396 	/* resource routing */
397 	if (pn_sockaddr_get_object(&sa) == 0) {
398 		struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
399 		if (sk)
400 			return sk_receive_skb(sk, skb, 0);
401 	}
402 
403 	/* check if we are the destination */
404 	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
405 		/* Phonet packet input */
406 		struct sock *sk = pn_find_sock_by_sa(net, &sa);
407 
408 		if (sk)
409 			return sk_receive_skb(sk, skb, 0);
410 
411 		if (can_respond(skb)) {
412 			send_obj_unreachable(skb);
413 			send_reset_indications(skb);
414 		}
415 	} else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
416 		goto out; /* Race between address deletion and loopback */
417 	else {
418 		/* Phonet packet routing */
419 		struct net_device *out_dev;
420 
421 		out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
422 		if (!out_dev) {
423 			LIMIT_NETDEBUG(KERN_WARNING"No Phonet route to %02X\n",
424 					pn_sockaddr_get_addr(&sa));
425 			goto out;
426 		}
427 
428 		__skb_push(skb, sizeof(struct phonethdr));
429 		skb->dev = out_dev;
430 		if (out_dev == dev) {
431 			LIMIT_NETDEBUG(KERN_ERR"Phonet loop to %02X on %s\n",
432 					pn_sockaddr_get_addr(&sa), dev->name);
433 			goto out_dev;
434 		}
435 		/* Some drivers (e.g. TUN) do not allocate HW header space */
436 		if (skb_cow_head(skb, out_dev->hard_header_len))
437 			goto out_dev;
438 
439 		if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
440 					skb->len) < 0)
441 			goto out_dev;
442 		dev_queue_xmit(skb);
443 		dev_put(out_dev);
444 		return NET_RX_SUCCESS;
445 out_dev:
446 		dev_put(out_dev);
447 	}
448 
449 out:
450 	kfree_skb(skb);
451 	return NET_RX_DROP;
452 }
453 
454 static struct packet_type phonet_packet_type __read_mostly = {
455 	.type = cpu_to_be16(ETH_P_PHONET),
456 	.func = phonet_rcv,
457 };
458 
459 static DEFINE_MUTEX(proto_tab_lock);
460 
461 int __init_or_module phonet_proto_register(unsigned int protocol,
462 						struct phonet_protocol *pp)
463 {
464 	int err = 0;
465 
466 	if (protocol >= PHONET_NPROTO)
467 		return -EINVAL;
468 
469 	err = proto_register(pp->prot, 1);
470 	if (err)
471 		return err;
472 
473 	mutex_lock(&proto_tab_lock);
474 	if (proto_tab[protocol])
475 		err = -EBUSY;
476 	else
477 		rcu_assign_pointer(proto_tab[protocol], pp);
478 	mutex_unlock(&proto_tab_lock);
479 
480 	return err;
481 }
482 EXPORT_SYMBOL(phonet_proto_register);
483 
484 void phonet_proto_unregister(unsigned int protocol, struct phonet_protocol *pp)
485 {
486 	mutex_lock(&proto_tab_lock);
487 	BUG_ON(proto_tab[protocol] != pp);
488 	rcu_assign_pointer(proto_tab[protocol], NULL);
489 	mutex_unlock(&proto_tab_lock);
490 	synchronize_rcu();
491 	proto_unregister(pp->prot);
492 }
493 EXPORT_SYMBOL(phonet_proto_unregister);
494 
495 /* Module registration */
496 static int __init phonet_init(void)
497 {
498 	int err;
499 
500 	err = phonet_device_init();
501 	if (err)
502 		return err;
503 
504 	pn_sock_init();
505 	err = sock_register(&phonet_proto_family);
506 	if (err) {
507 		printk(KERN_ALERT
508 			"phonet protocol family initialization failed\n");
509 		goto err_sock;
510 	}
511 
512 	dev_add_pack(&phonet_packet_type);
513 	phonet_sysctl_init();
514 
515 	err = isi_register();
516 	if (err)
517 		goto err;
518 	return 0;
519 
520 err:
521 	phonet_sysctl_exit();
522 	sock_unregister(PF_PHONET);
523 	dev_remove_pack(&phonet_packet_type);
524 err_sock:
525 	phonet_device_exit();
526 	return err;
527 }
528 
529 static void __exit phonet_exit(void)
530 {
531 	isi_unregister();
532 	phonet_sysctl_exit();
533 	sock_unregister(PF_PHONET);
534 	dev_remove_pack(&phonet_packet_type);
535 	phonet_device_exit();
536 }
537 
538 module_init(phonet_init);
539 module_exit(phonet_exit);
540 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
541 MODULE_LICENSE("GPL");
542 MODULE_ALIAS_NETPROTO(PF_PHONET);
543