ed65da251b6a70e016de7343299799dfa31781f7
[linux-2.6.git] / net / phonet / af_phonet.c
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 */
37 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
38
39 static struct phonet_protocol *phonet_proto_get(int protocol)
40 {
41         struct phonet_protocol *pp;
42
43         if (protocol >= PHONET_NPROTO)
44                 return NULL;
45
46         rcu_read_lock();
47         pp = proto_tab[protocol];
48         if (pp && !try_module_get(pp->prot->owner))
49                 pp = NULL;
50         rcu_read_unlock();
51
52         return pp;
53 }
54
55 static inline void phonet_proto_put(struct phonet_protocol *pp)
56 {
57         module_put(pp->prot->owner);
58 }
59
60 /* protocol family functions */
61
62 static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
63                             int kern)
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
116 out:
117         phonet_proto_put(pnp);
118         return err;
119 }
120
121 static const 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 */
128 static 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
143 static 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
150 struct header_ops phonet_header_ops = {
151         .create = pn_header_create,
152         .parse = pn_header_parse,
153 };
154 EXPORT_SYMBOL(phonet_header_ops);
155
156 /*
157  * Prepends an ISI header and sends a datagram.
158  */
159 static 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         /* Broadcast sending is not implemented */
172         if (pn_addr(dst) == PNADDR_BROADCAST) {
173                 err = -EOPNOTSUPP;
174                 goto drop;
175         }
176
177         skb_reset_transport_header(skb);
178         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
179         skb_push(skb, sizeof(struct phonethdr));
180         skb_reset_network_header(skb);
181         ph = pn_hdr(skb);
182         ph->pn_rdev = pn_dev(dst);
183         ph->pn_sdev = pn_dev(src);
184         ph->pn_res = res;
185         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
186         ph->pn_robj = pn_obj(dst);
187         ph->pn_sobj = pn_obj(src);
188
189         skb->protocol = htons(ETH_P_PHONET);
190         skb->priority = 0;
191         skb->dev = dev;
192
193         if (skb->pkt_type == PACKET_LOOPBACK) {
194                 skb_reset_mac_header(skb);
195                 skb_orphan(skb);
196                 if (irq)
197                         netif_rx(skb);
198                 else
199                         netif_rx_ni(skb);
200                 err = 0;
201         } else {
202                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
203                                         NULL, NULL, skb->len);
204                 if (err < 0) {
205                         err = -EHOSTUNREACH;
206                         goto drop;
207                 }
208                 err = dev_queue_xmit(skb);
209         }
210
211         return err;
212 drop:
213         kfree_skb(skb);
214         return err;
215 }
216
217 static 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  */
237 int 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;
245         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
246
247         err = -EHOSTUNREACH;
248         if (sk->sk_bound_dev_if)
249                 dev = dev_get_by_index(net, sk->sk_bound_dev_if);
250         else if (phonet_address_lookup(net, daddr) == 0) {
251                 dev = phonet_device_get(net);
252                 skb->pkt_type = PACKET_LOOPBACK;
253         } else
254                 dev = phonet_route_output(net, daddr);
255
256         if (!dev || !(dev->flags & IFF_UP))
257                 goto drop;
258
259         saddr = phonet_address_get(dev, daddr);
260         if (saddr == PN_NO_ADDR)
261                 goto drop;
262
263         src = pn->sobject;
264         if (!pn_addr(src))
265                 src = pn_object(saddr, pn_obj(src));
266
267         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
268                         src, pn_sockaddr_get_resource(target), 0);
269         dev_put(dev);
270         return err;
271
272 drop:
273         kfree_skb(skb);
274         if (dev)
275                 dev_put(dev);
276         return err;
277 }
278 EXPORT_SYMBOL(pn_skb_send);
279
280 /* Do not send an error message in response to an error message */
281 static inline int can_respond(struct sk_buff *skb)
282 {
283         const struct phonethdr *ph;
284         const struct phonetmsg *pm;
285         u8 submsg_id;
286
287         if (!pskb_may_pull(skb, 3))
288                 return 0;
289
290         ph = pn_hdr(skb);
291         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
292                 return 0;
293         if (ph->pn_res == PN_COMMGR) /* indications */
294                 return 0;
295
296         ph = pn_hdr(skb); /* re-acquires the pointer */
297         pm = pn_msg(skb);
298         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
299                 return 1;
300         submsg_id = (ph->pn_res == PN_PREFIX)
301                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
302         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
303                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
304                 return 1;
305         return 0;
306 }
307
308 static int send_obj_unreachable(struct sk_buff *rskb)
309 {
310         const struct phonethdr *oph = pn_hdr(rskb);
311         const struct phonetmsg *opm = pn_msg(rskb);
312         struct phonetmsg resp;
313
314         memset(&resp, 0, sizeof(resp));
315         resp.pn_trans_id = opm->pn_trans_id;
316         resp.pn_msg_id = PN_COMMON_MESSAGE;
317         if (oph->pn_res == PN_PREFIX) {
318                 resp.pn_e_res_id = opm->pn_e_res_id;
319                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
320                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
321                 resp.pn_e_status = 0;
322         } else {
323                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
324                 resp.pn_orig_msg_id = opm->pn_msg_id;
325                 resp.pn_status = 0;
326         }
327         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
328                                 pn_object(oph->pn_sdev, oph->pn_sobj),
329                                 pn_object(oph->pn_rdev, oph->pn_robj),
330                                 oph->pn_res);
331 }
332
333 static int send_reset_indications(struct sk_buff *rskb)
334 {
335         struct phonethdr *oph = pn_hdr(rskb);
336         static const u8 data[4] = {
337                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
338                 0x00 /* subscription count */, 0x00 /* dummy */
339         };
340
341         return pn_raw_send(data, sizeof(data), rskb->dev,
342                                 pn_object(oph->pn_sdev, 0x00),
343                                 pn_object(oph->pn_rdev, oph->pn_robj),
344                                 PN_COMMGR);
345 }
346
347
348 /* packet type functions */
349
350 /*
351  * Stuff received packets to associated sockets.
352  * On error, returns non-zero and releases the skb.
353  */
354 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
355                         struct packet_type *pkttype,
356                         struct net_device *orig_dev)
357 {
358         struct net *net = dev_net(dev);
359         struct phonethdr *ph;
360         struct sockaddr_pn sa;
361         u16 len;
362
363         /* check we have at least a full Phonet header */
364         if (!pskb_pull(skb, sizeof(struct phonethdr)))
365                 goto out;
366
367         /* check that the advertised length is correct */
368         ph = pn_hdr(skb);
369         len = get_unaligned_be16(&ph->pn_length);
370         if (len < 2)
371                 goto out;
372         len -= 2;
373         if ((len > skb->len) || pskb_trim(skb, len))
374                 goto out;
375         skb_reset_transport_header(skb);
376
377         pn_skb_get_dst_sockaddr(skb, &sa);
378
379         /* check if this is broadcasted */
380         if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
381                 pn_deliver_sock_broadcast(net, skb);
382                 goto out;
383         }
384
385         /* check if we are the destination */
386         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
387                 /* Phonet packet input */
388                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
389
390                 if (sk)
391                         return sk_receive_skb(sk, skb, 0);
392
393                 if (can_respond(skb)) {
394                         send_obj_unreachable(skb);
395                         send_reset_indications(skb);
396                 }
397         } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
398                 goto out; /* Race between address deletion and loopback */
399         else {
400                 /* Phonet packet routing */
401                 struct net_device *out_dev;
402
403                 out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
404                 if (!out_dev) {
405                         LIMIT_NETDEBUG(KERN_WARNING"No Phonet route to %02X\n",
406                                         pn_sockaddr_get_addr(&sa));
407                         goto out;
408                 }
409
410                 __skb_push(skb, sizeof(struct phonethdr));
411                 skb->dev = out_dev;
412                 if (out_dev == dev) {
413                         LIMIT_NETDEBUG(KERN_ERR"Phonet loop to %02X on %s\n",
414                                         pn_sockaddr_get_addr(&sa), dev->name);
415                         goto out_dev;
416                 }
417                 /* Some drivers (e.g. TUN) do not allocate HW header space */
418                 if (skb_cow_head(skb, out_dev->hard_header_len))
419                         goto out_dev;
420
421                 if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
422                                         skb->len) < 0)
423                         goto out_dev;
424                 dev_queue_xmit(skb);
425                 dev_put(out_dev);
426                 return NET_RX_SUCCESS;
427 out_dev:
428                 dev_put(out_dev);
429         }
430
431 out:
432         kfree_skb(skb);
433         return NET_RX_DROP;
434 }
435
436 static struct packet_type phonet_packet_type __read_mostly = {
437         .type = cpu_to_be16(ETH_P_PHONET),
438         .func = phonet_rcv,
439 };
440
441 static DEFINE_MUTEX(proto_tab_lock);
442
443 int __init_or_module phonet_proto_register(int protocol,
444                                                 struct phonet_protocol *pp)
445 {
446         int err = 0;
447
448         if (protocol >= PHONET_NPROTO)
449                 return -EINVAL;
450
451         err = proto_register(pp->prot, 1);
452         if (err)
453                 return err;
454
455         mutex_lock(&proto_tab_lock);
456         if (proto_tab[protocol])
457                 err = -EBUSY;
458         else
459                 rcu_assign_pointer(proto_tab[protocol], pp);
460         mutex_unlock(&proto_tab_lock);
461
462         return err;
463 }
464 EXPORT_SYMBOL(phonet_proto_register);
465
466 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
467 {
468         mutex_lock(&proto_tab_lock);
469         BUG_ON(proto_tab[protocol] != pp);
470         rcu_assign_pointer(proto_tab[protocol], NULL);
471         mutex_unlock(&proto_tab_lock);
472         synchronize_rcu();
473         proto_unregister(pp->prot);
474 }
475 EXPORT_SYMBOL(phonet_proto_unregister);
476
477 /* Module registration */
478 static int __init phonet_init(void)
479 {
480         int err;
481
482         err = phonet_device_init();
483         if (err)
484                 return err;
485
486         pn_sock_init();
487         err = sock_register(&phonet_proto_family);
488         if (err) {
489                 printk(KERN_ALERT
490                         "phonet protocol family initialization failed\n");
491                 goto err_sock;
492         }
493
494         dev_add_pack(&phonet_packet_type);
495         phonet_sysctl_init();
496
497         err = isi_register();
498         if (err)
499                 goto err;
500         return 0;
501
502 err:
503         phonet_sysctl_exit();
504         sock_unregister(PF_PHONET);
505         dev_remove_pack(&phonet_packet_type);
506 err_sock:
507         phonet_device_exit();
508         return err;
509 }
510
511 static void __exit phonet_exit(void)
512 {
513         isi_unregister();
514         phonet_sysctl_exit();
515         sock_unregister(PF_PHONET);
516         dev_remove_pack(&phonet_packet_type);
517         phonet_device_exit();
518 }
519
520 module_init(phonet_init);
521 module_exit(phonet_exit);
522 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
523 MODULE_LICENSE("GPL");
524 MODULE_ALIAS_NETPROTO(PF_PHONET);