af_phonet.c revision 09640e6365c679b5642b1c41b6d7078f51689ddf 
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 <asm/unaligned.h>
29#include <net/sock.h>
30
31#include <linux/if_phonet.h>
32#include <linux/phonet.h>
33#include <net/phonet/phonet.h>
34#include <net/phonet/pn_dev.h>
35
36/* Transport protocol registration */
37static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
38static DEFINE_SPINLOCK(proto_tab_lock);
39
40static struct phonet_protocol *phonet_proto_get(int protocol)
41{
42	struct phonet_protocol *pp;
43
44	if (protocol >= PHONET_NPROTO)
45		return NULL;
46
47	spin_lock(&proto_tab_lock);
48	pp = proto_tab[protocol];
49	if (pp && !try_module_get(pp->prot->owner))
50		pp = NULL;
51	spin_unlock(&proto_tab_lock);
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{
65	struct sock *sk;
66	struct pn_sock *pn;
67	struct phonet_protocol *pnp;
68	int err;
69
70	if (!capable(CAP_SYS_ADMIN))
71		return -EPERM;
72
73	if (protocol == 0) {
74		/* Default protocol selection */
75		switch (sock->type) {
76		case SOCK_DGRAM:
77			protocol = PN_PROTO_PHONET;
78			break;
79		case SOCK_SEQPACKET:
80			protocol = PN_PROTO_PIPE;
81			break;
82		default:
83			return -EPROTONOSUPPORT;
84		}
85	}
86
87	pnp = phonet_proto_get(protocol);
88	if (pnp == NULL &&
89	    request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
90		pnp = phonet_proto_get(protocol);
91
92	if (pnp == NULL)
93		return -EPROTONOSUPPORT;
94	if (sock->type != pnp->sock_type) {
95		err = -EPROTONOSUPPORT;
96		goto out;
97	}
98
99	sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
100	if (sk == NULL) {
101		err = -ENOMEM;
102		goto out;
103	}
104
105	sock_init_data(sock, sk);
106	sock->state = SS_UNCONNECTED;
107	sock->ops = pnp->ops;
108	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
109	sk->sk_protocol = protocol;
110	pn = pn_sk(sk);
111	pn->sobject = 0;
112	pn->resource = 0;
113	sk->sk_prot->init(sk);
114	err = 0;
115
116out:
117	phonet_proto_put(pnp);
118	return err;
119}
120
121static struct net_proto_family phonet_proto_family = {
122	.family = PF_PHONET,
123	.create = pn_socket_create,
124	.owner = THIS_MODULE,
125};
126
127/* Phonet device header operations */
128static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
129				unsigned short type, const void *daddr,
130				const void *saddr, unsigned len)
131{
132	u8 *media = skb_push(skb, 1);
133
134	if (type != ETH_P_PHONET)
135		return -1;
136
137	if (!saddr)
138		saddr = dev->dev_addr;
139	*media = *(const u8 *)saddr;
140	return 1;
141}
142
143static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
144{
145	const u8 *media = skb_mac_header(skb);
146	*haddr = *media;
147	return 1;
148}
149
150struct header_ops phonet_header_ops = {
151	.create = pn_header_create,
152	.parse = pn_header_parse,
153};
154EXPORT_SYMBOL(phonet_header_ops);
155
156/*
157 * Prepends an ISI header and sends a datagram.
158 */
159static int pn_send(struct sk_buff *skb, struct net_device *dev,
160			u16 dst, u16 src, u8 res, u8 irq)
161{
162	struct phonethdr *ph;
163	int err;
164
165	if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
166	    skb->len + sizeof(struct phonethdr) > dev->mtu) {
167		err = -EMSGSIZE;
168		goto drop;
169	}
170
171	skb_reset_transport_header(skb);
172	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
173	skb_push(skb, sizeof(struct phonethdr));
174	skb_reset_network_header(skb);
175	ph = pn_hdr(skb);
176	ph->pn_rdev = pn_dev(dst);
177	ph->pn_sdev = pn_dev(src);
178	ph->pn_res = res;
179	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
180	ph->pn_robj = pn_obj(dst);
181	ph->pn_sobj = pn_obj(src);
182
183	skb->protocol = htons(ETH_P_PHONET);
184	skb->priority = 0;
185	skb->dev = dev;
186
187	if (pn_addr(src) == pn_addr(dst)) {
188		skb_reset_mac_header(skb);
189		skb->pkt_type = PACKET_LOOPBACK;
190		skb_orphan(skb);
191		if (irq)
192			netif_rx(skb);
193		else
194			netif_rx_ni(skb);
195		err = 0;
196	} else {
197		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
198					NULL, NULL, skb->len);
199		if (err < 0) {
200			err = -EHOSTUNREACH;
201			goto drop;
202		}
203		err = dev_queue_xmit(skb);
204	}
205
206	return err;
207drop:
208	kfree_skb(skb);
209	return err;
210}
211
212static int pn_raw_send(const void *data, int len, struct net_device *dev,
213			u16 dst, u16 src, u8 res)
214{
215	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
216	if (skb == NULL)
217		return -ENOMEM;
218
219	skb_reserve(skb, MAX_PHONET_HEADER);
220	__skb_put(skb, len);
221	skb_copy_to_linear_data(skb, data, len);
222	return pn_send(skb, dev, dst, src, res, 1);
223}
224
225/*
226 * Create a Phonet header for the skb and send it out. Returns
227 * non-zero error code if failed. The skb is freed then.
228 */
229int pn_skb_send(struct sock *sk, struct sk_buff *skb,
230		const struct sockaddr_pn *target)
231{
232	struct net_device *dev;
233	struct pn_sock *pn = pn_sk(sk);
234	int err;
235	u16 src;
236	u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
237
238	err = -EHOSTUNREACH;
239	if (sk->sk_bound_dev_if)
240		dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
241	else
242		dev = phonet_device_get(sock_net(sk));
243	if (!dev || !(dev->flags & IFF_UP))
244		goto drop;
245
246	saddr = phonet_address_get(dev, daddr);
247	if (saddr == PN_NO_ADDR)
248		goto drop;
249
250	src = pn->sobject;
251	if (!pn_addr(src))
252		src = pn_object(saddr, pn_obj(src));
253
254	err = pn_send(skb, dev, pn_sockaddr_get_object(target),
255			src, pn_sockaddr_get_resource(target), 0);
256	dev_put(dev);
257	return err;
258
259drop:
260	kfree_skb(skb);
261	if (dev)
262		dev_put(dev);
263	return err;
264}
265EXPORT_SYMBOL(pn_skb_send);
266
267/* Do not send an error message in response to an error message */
268static inline int can_respond(struct sk_buff *skb)
269{
270	const struct phonethdr *ph;
271	const struct phonetmsg *pm;
272	u8 submsg_id;
273
274	if (!pskb_may_pull(skb, 3))
275		return 0;
276
277	ph = pn_hdr(skb);
278	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
279		return 0;
280	if (ph->pn_res == PN_COMMGR) /* indications */
281		return 0;
282
283	ph = pn_hdr(skb); /* re-acquires the pointer */
284	pm = pn_msg(skb);
285	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
286		return 1;
287	submsg_id = (ph->pn_res == PN_PREFIX)
288		? pm->pn_e_submsg_id : pm->pn_submsg_id;
289	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
290		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
291		return 1;
292	return 0;
293}
294
295static int send_obj_unreachable(struct sk_buff *rskb)
296{
297	const struct phonethdr *oph = pn_hdr(rskb);
298	const struct phonetmsg *opm = pn_msg(rskb);
299	struct phonetmsg resp;
300
301	memset(&resp, 0, sizeof(resp));
302	resp.pn_trans_id = opm->pn_trans_id;
303	resp.pn_msg_id = PN_COMMON_MESSAGE;
304	if (oph->pn_res == PN_PREFIX) {
305		resp.pn_e_res_id = opm->pn_e_res_id;
306		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
307		resp.pn_e_orig_msg_id = opm->pn_msg_id;
308		resp.pn_e_status = 0;
309	} else {
310		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
311		resp.pn_orig_msg_id = opm->pn_msg_id;
312		resp.pn_status = 0;
313	}
314	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
315				pn_object(oph->pn_sdev, oph->pn_sobj),
316				pn_object(oph->pn_rdev, oph->pn_robj),
317				oph->pn_res);
318}
319
320static int send_reset_indications(struct sk_buff *rskb)
321{
322	struct phonethdr *oph = pn_hdr(rskb);
323	static const u8 data[4] = {
324		0x00 /* trans ID */, 0x10 /* subscribe msg */,
325		0x00 /* subscription count */, 0x00 /* dummy */
326	};
327
328	return pn_raw_send(data, sizeof(data), rskb->dev,
329				pn_object(oph->pn_sdev, 0x00),
330				pn_object(oph->pn_rdev, oph->pn_robj),
331				PN_COMMGR);
332}
333
334
335/* packet type functions */
336
337/*
338 * Stuff received packets to associated sockets.
339 * On error, returns non-zero and releases the skb.
340 */
341static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
342			struct packet_type *pkttype,
343			struct net_device *orig_dev)
344{
345	struct net *net = dev_net(dev);
346	struct phonethdr *ph;
347	struct sockaddr_pn sa;
348	u16 len;
349
350	/* check we have at least a full Phonet header */
351	if (!pskb_pull(skb, sizeof(struct phonethdr)))
352		goto out;
353
354	/* check that the advertised length is correct */
355	ph = pn_hdr(skb);
356	len = get_unaligned_be16(&ph->pn_length);
357	if (len < 2)
358		goto out;
359	len -= 2;
360	if ((len > skb->len) || pskb_trim(skb, len))
361		goto out;
362	skb_reset_transport_header(skb);
363
364	pn_skb_get_dst_sockaddr(skb, &sa);
365
366	/* check if we are the destination */
367	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
368		/* Phonet packet input */
369		struct sock *sk = pn_find_sock_by_sa(net, &sa);
370
371		if (sk)
372			return sk_receive_skb(sk, skb, 0);
373
374		if (can_respond(skb)) {
375			send_obj_unreachable(skb);
376			send_reset_indications(skb);
377		}
378	}
379
380out:
381	kfree_skb(skb);
382	return NET_RX_DROP;
383}
384
385static struct packet_type phonet_packet_type = {
386	.type = cpu_to_be16(ETH_P_PHONET),
387	.dev = NULL,
388	.func = phonet_rcv,
389};
390
391int __init_or_module phonet_proto_register(int protocol,
392						struct phonet_protocol *pp)
393{
394	int err = 0;
395
396	if (protocol >= PHONET_NPROTO)
397		return -EINVAL;
398
399	err = proto_register(pp->prot, 1);
400	if (err)
401		return err;
402
403	spin_lock(&proto_tab_lock);
404	if (proto_tab[protocol])
405		err = -EBUSY;
406	else
407		proto_tab[protocol] = pp;
408	spin_unlock(&proto_tab_lock);
409
410	return err;
411}
412EXPORT_SYMBOL(phonet_proto_register);
413
414void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
415{
416	spin_lock(&proto_tab_lock);
417	BUG_ON(proto_tab[protocol] != pp);
418	proto_tab[protocol] = NULL;
419	spin_unlock(&proto_tab_lock);
420	proto_unregister(pp->prot);
421}
422EXPORT_SYMBOL(phonet_proto_unregister);
423
424/* Module registration */
425static int __init phonet_init(void)
426{
427	int err;
428
429	err = phonet_device_init();
430	if (err)
431		return err;
432
433	err = sock_register(&phonet_proto_family);
434	if (err) {
435		printk(KERN_ALERT
436			"phonet protocol family initialization failed\n");
437		goto err_sock;
438	}
439
440	dev_add_pack(&phonet_packet_type);
441	phonet_sysctl_init();
442
443	err = isi_register();
444	if (err)
445		goto err;
446	return 0;
447
448err:
449	phonet_sysctl_exit();
450	sock_unregister(PF_PHONET);
451	dev_remove_pack(&phonet_packet_type);
452err_sock:
453	phonet_device_exit();
454	return err;
455}
456
457static void __exit phonet_exit(void)
458{
459	isi_unregister();
460	phonet_sysctl_exit();
461	sock_unregister(PF_PHONET);
462	dev_remove_pack(&phonet_packet_type);
463	phonet_device_exit();
464}
465
466module_init(phonet_init);
467module_exit(phonet_exit);
468MODULE_DESCRIPTION("Phonet protocol stack for Linux");
469MODULE_LICENSE("GPL");
470MODULE_ALIAS_NETPROTO(PF_PHONET);
471