Phonet: connected sockets glue
[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 static struct net_proto_family phonet_proto_family;
37 static struct phonet_protocol *phonet_proto_get(int protocol);
38 static inline void phonet_proto_put(struct phonet_protocol *pp);
39
40 /* protocol family functions */
41
42 static int pn_socket_create(struct net *net, struct socket *sock, int protocol)
43 {
44         struct sock *sk;
45         struct pn_sock *pn;
46         struct phonet_protocol *pnp;
47         int err;
48
49         if (net != &init_net)
50                 return -EAFNOSUPPORT;
51
52         if (!capable(CAP_SYS_ADMIN))
53                 return -EPERM;
54
55         if (protocol == 0) {
56                 /* Default protocol selection */
57                 switch (sock->type) {
58                 case SOCK_DGRAM:
59                         protocol = PN_PROTO_PHONET;
60                         break;
61                 default:
62                         return -EPROTONOSUPPORT;
63                 }
64         }
65
66         pnp = phonet_proto_get(protocol);
67 #ifdef CONFIG_KMOD
68         if (pnp == NULL &&
69             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
70                 pnp = phonet_proto_get(protocol);
71 #endif
72         if (pnp == NULL)
73                 return -EPROTONOSUPPORT;
74         if (sock->type != pnp->sock_type) {
75                 err = -EPROTONOSUPPORT;
76                 goto out;
77         }
78
79         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
80         if (sk == NULL) {
81                 err = -ENOMEM;
82                 goto out;
83         }
84
85         sock_init_data(sock, sk);
86         sock->state = SS_UNCONNECTED;
87         sock->ops = pnp->ops;
88         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
89         sk->sk_protocol = protocol;
90         pn = pn_sk(sk);
91         pn->sobject = 0;
92         pn->resource = 0;
93         sk->sk_prot->init(sk);
94         err = 0;
95
96 out:
97         phonet_proto_put(pnp);
98         return err;
99 }
100
101 static struct net_proto_family phonet_proto_family = {
102         .family = PF_PHONET,
103         .create = pn_socket_create,
104         .owner = THIS_MODULE,
105 };
106
107 /* Phonet device header operations */
108 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
109                                 unsigned short type, const void *daddr,
110                                 const void *saddr, unsigned len)
111 {
112         u8 *media = skb_push(skb, 1);
113
114         if (type != ETH_P_PHONET)
115                 return -1;
116
117         if (!saddr)
118                 saddr = dev->dev_addr;
119         *media = *(const u8 *)saddr;
120         return 1;
121 }
122
123 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
124 {
125         const u8 *media = skb_mac_header(skb);
126         *haddr = *media;
127         return 1;
128 }
129
130 struct header_ops phonet_header_ops = {
131         .create = pn_header_create,
132         .parse = pn_header_parse,
133 };
134 EXPORT_SYMBOL(phonet_header_ops);
135
136 /*
137  * Prepends an ISI header and sends a datagram.
138  */
139 static int pn_send(struct sk_buff *skb, struct net_device *dev,
140                         u16 dst, u16 src, u8 res, u8 irq)
141 {
142         struct phonethdr *ph;
143         int err;
144
145         if (skb->len + 2 > 0xffff) {
146                 /* Phonet length field would overflow */
147                 err = -EMSGSIZE;
148                 goto drop;
149         }
150
151         skb_reset_transport_header(skb);
152         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
153         skb_push(skb, sizeof(struct phonethdr));
154         skb_reset_network_header(skb);
155         ph = pn_hdr(skb);
156         ph->pn_rdev = pn_dev(dst);
157         ph->pn_sdev = pn_dev(src);
158         ph->pn_res = res;
159         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
160         ph->pn_robj = pn_obj(dst);
161         ph->pn_sobj = pn_obj(src);
162
163         skb->protocol = htons(ETH_P_PHONET);
164         skb->priority = 0;
165         skb->dev = dev;
166
167         if (pn_addr(src) == pn_addr(dst)) {
168                 skb_reset_mac_header(skb);
169                 skb->pkt_type = PACKET_LOOPBACK;
170                 skb_orphan(skb);
171                 if (irq)
172                         netif_rx(skb);
173                 else
174                         netif_rx_ni(skb);
175                 err = 0;
176         } else {
177                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
178                                         NULL, NULL, skb->len);
179                 if (err < 0) {
180                         err = -EHOSTUNREACH;
181                         goto drop;
182                 }
183                 err = dev_queue_xmit(skb);
184         }
185
186         return err;
187 drop:
188         kfree_skb(skb);
189         return err;
190 }
191
192 static int pn_raw_send(const void *data, int len, struct net_device *dev,
193                         u16 dst, u16 src, u8 res)
194 {
195         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
196         if (skb == NULL)
197                 return -ENOMEM;
198
199         skb_reserve(skb, MAX_PHONET_HEADER);
200         __skb_put(skb, len);
201         skb_copy_to_linear_data(skb, data, len);
202         return pn_send(skb, dev, dst, src, res, 1);
203 }
204
205 /*
206  * Create a Phonet header for the skb and send it out. Returns
207  * non-zero error code if failed. The skb is freed then.
208  */
209 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
210                 const struct sockaddr_pn *target)
211 {
212         struct net_device *dev;
213         struct pn_sock *pn = pn_sk(sk);
214         int err;
215         u16 src;
216         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
217
218         err = -EHOSTUNREACH;
219         if (sk->sk_bound_dev_if)
220                 dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
221         else
222                 dev = phonet_device_get(sock_net(sk));
223         if (!dev || !(dev->flags & IFF_UP))
224                 goto drop;
225
226         saddr = phonet_address_get(dev, daddr);
227         if (saddr == PN_NO_ADDR)
228                 goto drop;
229
230         src = pn->sobject;
231         if (!pn_addr(src))
232                 src = pn_object(saddr, pn_obj(src));
233
234         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
235                         src, pn_sockaddr_get_resource(target), 0);
236         dev_put(dev);
237         return err;
238
239 drop:
240         kfree_skb(skb);
241         if (dev)
242                 dev_put(dev);
243         return err;
244 }
245 EXPORT_SYMBOL(pn_skb_send);
246
247 /* Do not send an error message in response to an error message */
248 static inline int can_respond(struct sk_buff *skb)
249 {
250         const struct phonethdr *ph;
251         const struct phonetmsg *pm;
252         u8 submsg_id;
253
254         if (!pskb_may_pull(skb, 3))
255                 return 0;
256
257         ph = pn_hdr(skb);
258         if (phonet_address_get(skb->dev, ph->pn_rdev) != ph->pn_rdev)
259                 return 0; /* we are not the destination */
260         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
261                 return 0;
262
263         ph = pn_hdr(skb); /* re-acquires the pointer */
264         pm = pn_msg(skb);
265         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
266                 return 1;
267         submsg_id = (ph->pn_res == PN_PREFIX)
268                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
269         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
270                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
271                 return 1;
272         return 0;
273 }
274
275 static int send_obj_unreachable(struct sk_buff *rskb)
276 {
277         const struct phonethdr *oph = pn_hdr(rskb);
278         const struct phonetmsg *opm = pn_msg(rskb);
279         struct phonetmsg resp;
280
281         memset(&resp, 0, sizeof(resp));
282         resp.pn_trans_id = opm->pn_trans_id;
283         resp.pn_msg_id = PN_COMMON_MESSAGE;
284         if (oph->pn_res == PN_PREFIX) {
285                 resp.pn_e_res_id = opm->pn_e_res_id;
286                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
287                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
288                 resp.pn_e_status = 0;
289         } else {
290                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
291                 resp.pn_orig_msg_id = opm->pn_msg_id;
292                 resp.pn_status = 0;
293         }
294         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
295                                 pn_object(oph->pn_sdev, oph->pn_sobj),
296                                 pn_object(oph->pn_rdev, oph->pn_robj),
297                                 oph->pn_res);
298 }
299
300 static int send_reset_indications(struct sk_buff *rskb)
301 {
302         struct phonethdr *oph = pn_hdr(rskb);
303         static const u8 data[4] = {
304                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
305                 0x00 /* subscription count */, 0x00 /* dummy */
306         };
307
308         return pn_raw_send(data, sizeof(data), rskb->dev,
309                                 pn_object(oph->pn_sdev, 0x00),
310                                 pn_object(oph->pn_rdev, oph->pn_robj), 0x10);
311 }
312
313
314 /* packet type functions */
315
316 /*
317  * Stuff received packets to associated sockets.
318  * On error, returns non-zero and releases the skb.
319  */
320 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
321                         struct packet_type *pkttype,
322                         struct net_device *orig_dev)
323 {
324         struct phonethdr *ph;
325         struct sock *sk;
326         struct sockaddr_pn sa;
327         u16 len;
328
329         if (dev_net(dev) != &init_net)
330                 goto out;
331
332         /* check we have at least a full Phonet header */
333         if (!pskb_pull(skb, sizeof(struct phonethdr)))
334                 goto out;
335
336         /* check that the advertised length is correct */
337         ph = pn_hdr(skb);
338         len = get_unaligned_be16(&ph->pn_length);
339         if (len < 2)
340                 goto out;
341         len -= 2;
342         if ((len > skb->len) || pskb_trim(skb, len))
343                 goto out;
344         skb_reset_transport_header(skb);
345
346         pn_skb_get_dst_sockaddr(skb, &sa);
347         if (pn_sockaddr_get_addr(&sa) == 0)
348                 goto out; /* currently, we cannot be device 0 */
349
350         sk = pn_find_sock_by_sa(&sa);
351         if (sk == NULL) {
352                 if (can_respond(skb)) {
353                         send_obj_unreachable(skb);
354                         send_reset_indications(skb);
355                 }
356                 goto out;
357         }
358
359         /* Push data to the socket (or other sockets connected to it). */
360         return sk_receive_skb(sk, skb, 0);
361
362 out:
363         kfree_skb(skb);
364         return NET_RX_DROP;
365 }
366
367 static struct packet_type phonet_packet_type = {
368         .type = __constant_htons(ETH_P_PHONET),
369         .dev = NULL,
370         .func = phonet_rcv,
371 };
372
373 /* Transport protocol registration */
374 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
375 static DEFINE_SPINLOCK(proto_tab_lock);
376
377 int __init_or_module phonet_proto_register(int protocol,
378                                                 struct phonet_protocol *pp)
379 {
380         int err = 0;
381
382         if (protocol >= PHONET_NPROTO)
383                 return -EINVAL;
384
385         err = proto_register(pp->prot, 1);
386         if (err)
387                 return err;
388
389         spin_lock(&proto_tab_lock);
390         if (proto_tab[protocol])
391                 err = -EBUSY;
392         else
393                 proto_tab[protocol] = pp;
394         spin_unlock(&proto_tab_lock);
395
396         return err;
397 }
398 EXPORT_SYMBOL(phonet_proto_register);
399
400 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
401 {
402         spin_lock(&proto_tab_lock);
403         BUG_ON(proto_tab[protocol] != pp);
404         proto_tab[protocol] = NULL;
405         spin_unlock(&proto_tab_lock);
406         proto_unregister(pp->prot);
407 }
408 EXPORT_SYMBOL(phonet_proto_unregister);
409
410 static struct phonet_protocol *phonet_proto_get(int protocol)
411 {
412         struct phonet_protocol *pp;
413
414         if (protocol >= PHONET_NPROTO)
415                 return NULL;
416
417         spin_lock(&proto_tab_lock);
418         pp = proto_tab[protocol];
419         if (pp && !try_module_get(pp->prot->owner))
420                 pp = NULL;
421         spin_unlock(&proto_tab_lock);
422
423         return pp;
424 }
425
426 static inline void phonet_proto_put(struct phonet_protocol *pp)
427 {
428         module_put(pp->prot->owner);
429 }
430
431 /* Module registration */
432 static int __init phonet_init(void)
433 {
434         int err;
435
436         err = sock_register(&phonet_proto_family);
437         if (err) {
438                 printk(KERN_ALERT
439                         "phonet protocol family initialization failed\n");
440                 return err;
441         }
442
443         phonet_device_init();
444         dev_add_pack(&phonet_packet_type);
445         phonet_netlink_register();
446         phonet_sysctl_init();
447
448         err = isi_register();
449         if (err)
450                 goto err;
451         return 0;
452
453 err:
454         phonet_sysctl_exit();
455         sock_unregister(PF_PHONET);
456         dev_remove_pack(&phonet_packet_type);
457         phonet_device_exit();
458         return err;
459 }
460
461 static void __exit phonet_exit(void)
462 {
463         isi_unregister();
464         phonet_sysctl_exit();
465         sock_unregister(PF_PHONET);
466         dev_remove_pack(&phonet_packet_type);
467         phonet_device_exit();
468 }
469
470 module_init(phonet_init);
471 module_exit(phonet_exit);
472 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
473 MODULE_LICENSE("GPL");
474 MODULE_ALIAS_NETPROTO(PF_PHONET);