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