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