1/*
2 * File: af_phonet.c
3 *
4 * Phonet protocols family
5 *
6 * Copyright (C) 2008 Nokia Corporation.
7 *
8 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
9 *          Rémi Denis-Courmont
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 */
38static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
39
40static 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
56static inline void phonet_proto_put(struct phonet_protocol *pp)
57{
58	module_put(pp->prot->owner);
59}
60
61/* protocol family functions */
62
63static 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->dobject = 0;
114	pn->resource = 0;
115	sk->sk_prot->init(sk);
116	err = 0;
117
118out:
119	phonet_proto_put(pnp);
120	return err;
121}
122
123static const struct net_proto_family phonet_proto_family = {
124	.family = PF_PHONET,
125	.create = pn_socket_create,
126	.owner = THIS_MODULE,
127};
128
129/* Phonet device header operations */
130static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
131				unsigned short type, const void *daddr,
132				const void *saddr, unsigned int len)
133{
134	u8 *media = skb_push(skb, 1);
135
136	if (type != ETH_P_PHONET)
137		return -1;
138
139	if (!saddr)
140		saddr = dev->dev_addr;
141	*media = *(const u8 *)saddr;
142	return 1;
143}
144
145static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
146{
147	const u8 *media = skb_mac_header(skb);
148	*haddr = *media;
149	return 1;
150}
151
152struct header_ops phonet_header_ops = {
153	.create = pn_header_create,
154	.parse = pn_header_parse,
155};
156EXPORT_SYMBOL(phonet_header_ops);
157
158/*
159 * Prepends an ISI header and sends a datagram.
160 */
161static int pn_send(struct sk_buff *skb, struct net_device *dev,
162			u16 dst, u16 src, u8 res, u8 irq)
163{
164	struct phonethdr *ph;
165	int err;
166
167	if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
168	    skb->len + sizeof(struct phonethdr) > dev->mtu) {
169		err = -EMSGSIZE;
170		goto drop;
171	}
172
173	/* Broadcast sending is not implemented */
174	if (pn_addr(dst) == PNADDR_BROADCAST) {
175		err = -EOPNOTSUPP;
176		goto drop;
177	}
178
179	skb_reset_transport_header(skb);
180	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
181	skb_push(skb, sizeof(struct phonethdr));
182	skb_reset_network_header(skb);
183	ph = pn_hdr(skb);
184	ph->pn_rdev = pn_dev(dst);
185	ph->pn_sdev = pn_dev(src);
186	ph->pn_res = res;
187	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
188	ph->pn_robj = pn_obj(dst);
189	ph->pn_sobj = pn_obj(src);
190
191	skb->protocol = htons(ETH_P_PHONET);
192	skb->priority = 0;
193	skb->dev = dev;
194
195	if (skb->pkt_type == PACKET_LOOPBACK) {
196		skb_reset_mac_header(skb);
197		skb_orphan(skb);
198		err = (irq ? netif_rx(skb) : netif_rx_ni(skb)) ? -ENOBUFS : 0;
199	} else {
200		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
201					NULL, NULL, skb->len);
202		if (err < 0) {
203			err = -EHOSTUNREACH;
204			goto drop;
205		}
206		err = dev_queue_xmit(skb);
207		if (unlikely(err > 0))
208			err = net_xmit_errno(err);
209	}
210
211	return err;
212drop:
213	kfree_skb(skb);
214	return err;
215}
216
217static int pn_raw_send(const void *data, int len, struct net_device *dev,
218			u16 dst, u16 src, u8 res)
219{
220	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
221	if (skb == NULL)
222		return -ENOMEM;
223
224	if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
225		skb->pkt_type = PACKET_LOOPBACK;
226
227	skb_reserve(skb, MAX_PHONET_HEADER);
228	__skb_put(skb, len);
229	skb_copy_to_linear_data(skb, data, len);
230	return pn_send(skb, dev, dst, src, res, 1);
231}
232
233/*
234 * Create a Phonet header for the skb and send it out. Returns
235 * non-zero error code if failed. The skb is freed then.
236 */
237int pn_skb_send(struct sock *sk, struct sk_buff *skb,
238		const struct sockaddr_pn *target)
239{
240	struct net *net = sock_net(sk);
241	struct net_device *dev;
242	struct pn_sock *pn = pn_sk(sk);
243	int err;
244	u16 src, dst;
245	u8 daddr, saddr, res;
246
247	src = pn->sobject;
248	if (target != NULL) {
249		dst = pn_sockaddr_get_object(target);
250		res = pn_sockaddr_get_resource(target);
251	} else {
252		dst = pn->dobject;
253		res = pn->resource;
254	}
255	daddr = pn_addr(dst);
256
257	err = -EHOSTUNREACH;
258	if (sk->sk_bound_dev_if)
259		dev = dev_get_by_index(net, sk->sk_bound_dev_if);
260	else if (phonet_address_lookup(net, daddr) == 0) {
261		dev = phonet_device_get(net);
262		skb->pkt_type = PACKET_LOOPBACK;
263	} else if (dst == 0) {
264		/* Resource routing (small race until phonet_rcv()) */
265		struct sock *sk = pn_find_sock_by_res(net, res);
266		if (sk)	{
267			sock_put(sk);
268			dev = phonet_device_get(net);
269			skb->pkt_type = PACKET_LOOPBACK;
270		} else
271			dev = phonet_route_output(net, daddr);
272	} else
273		dev = phonet_route_output(net, daddr);
274
275	if (!dev || !(dev->flags & IFF_UP))
276		goto drop;
277
278	saddr = phonet_address_get(dev, daddr);
279	if (saddr == PN_NO_ADDR)
280		goto drop;
281
282	if (!pn_addr(src))
283		src = pn_object(saddr, pn_obj(src));
284
285	err = pn_send(skb, dev, dst, src, res, 0);
286	dev_put(dev);
287	return err;
288
289drop:
290	kfree_skb(skb);
291	if (dev)
292		dev_put(dev);
293	return err;
294}
295EXPORT_SYMBOL(pn_skb_send);
296
297/* Do not send an error message in response to an error message */
298static inline int can_respond(struct sk_buff *skb)
299{
300	const struct phonethdr *ph;
301	const struct phonetmsg *pm;
302	u8 submsg_id;
303
304	if (!pskb_may_pull(skb, 3))
305		return 0;
306
307	ph = pn_hdr(skb);
308	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
309		return 0;
310	if (ph->pn_res == PN_COMMGR) /* indications */
311		return 0;
312
313	ph = pn_hdr(skb); /* re-acquires the pointer */
314	pm = pn_msg(skb);
315	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
316		return 1;
317	submsg_id = (ph->pn_res == PN_PREFIX)
318		? pm->pn_e_submsg_id : pm->pn_submsg_id;
319	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
320		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
321		return 1;
322	return 0;
323}
324
325static int send_obj_unreachable(struct sk_buff *rskb)
326{
327	const struct phonethdr *oph = pn_hdr(rskb);
328	const struct phonetmsg *opm = pn_msg(rskb);
329	struct phonetmsg resp;
330
331	memset(&resp, 0, sizeof(resp));
332	resp.pn_trans_id = opm->pn_trans_id;
333	resp.pn_msg_id = PN_COMMON_MESSAGE;
334	if (oph->pn_res == PN_PREFIX) {
335		resp.pn_e_res_id = opm->pn_e_res_id;
336		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
337		resp.pn_e_orig_msg_id = opm->pn_msg_id;
338		resp.pn_e_status = 0;
339	} else {
340		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
341		resp.pn_orig_msg_id = opm->pn_msg_id;
342		resp.pn_status = 0;
343	}
344	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
345				pn_object(oph->pn_sdev, oph->pn_sobj),
346				pn_object(oph->pn_rdev, oph->pn_robj),
347				oph->pn_res);
348}
349
350static int send_reset_indications(struct sk_buff *rskb)
351{
352	struct phonethdr *oph = pn_hdr(rskb);
353	static const u8 data[4] = {
354		0x00 /* trans ID */, 0x10 /* subscribe msg */,
355		0x00 /* subscription count */, 0x00 /* dummy */
356	};
357
358	return pn_raw_send(data, sizeof(data), rskb->dev,
359				pn_object(oph->pn_sdev, 0x00),
360				pn_object(oph->pn_rdev, oph->pn_robj),
361				PN_COMMGR);
362}
363
364
365/* packet type functions */
366
367/*
368 * Stuff received packets to associated sockets.
369 * On error, returns non-zero and releases the skb.
370 */
371static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
372			struct packet_type *pkttype,
373			struct net_device *orig_dev)
374{
375	struct net *net = dev_net(dev);
376	struct phonethdr *ph;
377	struct sockaddr_pn sa;
378	u16 len;
379
380	/* check we have at least a full Phonet header */
381	if (!pskb_pull(skb, sizeof(struct phonethdr)))
382		goto out;
383
384	/* check that the advertised length is correct */
385	ph = pn_hdr(skb);
386	len = get_unaligned_be16(&ph->pn_length);
387	if (len < 2)
388		goto out;
389	len -= 2;
390	if ((len > skb->len) || pskb_trim(skb, len))
391		goto out;
392	skb_reset_transport_header(skb);
393
394	pn_skb_get_dst_sockaddr(skb, &sa);
395
396	/* check if this is broadcasted */
397	if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
398		pn_deliver_sock_broadcast(net, skb);
399		goto out;
400	}
401
402	/* resource routing */
403	if (pn_sockaddr_get_object(&sa) == 0) {
404		struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
405		if (sk)
406			return sk_receive_skb(sk, skb, 0);
407	}
408
409	/* check if we are the destination */
410	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
411		/* Phonet packet input */
412		struct sock *sk = pn_find_sock_by_sa(net, &sa);
413
414		if (sk)
415			return sk_receive_skb(sk, skb, 0);
416
417		if (can_respond(skb)) {
418			send_obj_unreachable(skb);
419			send_reset_indications(skb);
420		}
421	} else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
422		goto out; /* Race between address deletion and loopback */
423	else {
424		/* Phonet packet routing */
425		struct net_device *out_dev;
426
427		out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
428		if (!out_dev) {
429			LIMIT_NETDEBUG(KERN_WARNING"No Phonet route to %02X\n",
430					pn_sockaddr_get_addr(&sa));
431			goto out;
432		}
433
434		__skb_push(skb, sizeof(struct phonethdr));
435		skb->dev = out_dev;
436		if (out_dev == dev) {
437			LIMIT_NETDEBUG(KERN_ERR"Phonet loop to %02X on %s\n",
438					pn_sockaddr_get_addr(&sa), dev->name);
439			goto out_dev;
440		}
441		/* Some drivers (e.g. TUN) do not allocate HW header space */
442		if (skb_cow_head(skb, out_dev->hard_header_len))
443			goto out_dev;
444
445		if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
446					skb->len) < 0)
447			goto out_dev;
448		dev_queue_xmit(skb);
449		dev_put(out_dev);
450		return NET_RX_SUCCESS;
451out_dev:
452		dev_put(out_dev);
453	}
454
455out:
456	kfree_skb(skb);
457	return NET_RX_DROP;
458}
459
460static struct packet_type phonet_packet_type __read_mostly = {
461	.type = cpu_to_be16(ETH_P_PHONET),
462	.func = phonet_rcv,
463};
464
465static DEFINE_MUTEX(proto_tab_lock);
466
467int __init_or_module phonet_proto_register(unsigned int protocol,
468						struct phonet_protocol *pp)
469{
470	int err = 0;
471
472	if (protocol >= PHONET_NPROTO)
473		return -EINVAL;
474
475	err = proto_register(pp->prot, 1);
476	if (err)
477		return err;
478
479	mutex_lock(&proto_tab_lock);
480	if (proto_tab[protocol])
481		err = -EBUSY;
482	else
483		rcu_assign_pointer(proto_tab[protocol], pp);
484	mutex_unlock(&proto_tab_lock);
485
486	return err;
487}
488EXPORT_SYMBOL(phonet_proto_register);
489
490void phonet_proto_unregister(unsigned int protocol, struct phonet_protocol *pp)
491{
492	mutex_lock(&proto_tab_lock);
493	BUG_ON(proto_tab[protocol] != pp);
494	RCU_INIT_POINTER(proto_tab[protocol], NULL);
495	mutex_unlock(&proto_tab_lock);
496	synchronize_rcu();
497	proto_unregister(pp->prot);
498}
499EXPORT_SYMBOL(phonet_proto_unregister);
500
501/* Module registration */
502static int __init phonet_init(void)
503{
504	int err;
505
506	err = phonet_device_init();
507	if (err)
508		return err;
509
510	pn_sock_init();
511	err = sock_register(&phonet_proto_family);
512	if (err) {
513		printk(KERN_ALERT
514			"phonet protocol family initialization failed\n");
515		goto err_sock;
516	}
517
518	dev_add_pack(&phonet_packet_type);
519	phonet_sysctl_init();
520
521	err = isi_register();
522	if (err)
523		goto err;
524	return 0;
525
526err:
527	phonet_sysctl_exit();
528	sock_unregister(PF_PHONET);
529	dev_remove_pack(&phonet_packet_type);
530err_sock:
531	phonet_device_exit();
532	return err;
533}
534
535static void __exit phonet_exit(void)
536{
537	isi_unregister();
538	phonet_sysctl_exit();
539	sock_unregister(PF_PHONET);
540	dev_remove_pack(&phonet_packet_type);
541	phonet_device_exit();
542}
543
544module_init(phonet_init);
545module_exit(phonet_exit);
546MODULE_DESCRIPTION("Phonet protocol stack for Linux");
547MODULE_LICENSE("GPL");
548MODULE_ALIAS_NETPROTO(PF_PHONET);
549