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Linux/net/phonet/af_phonet.c

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  1 /*
  2  * File: af_phonet.c
  3  *
  4  * Phonet protocols family
  5  *
  6  * Copyright (C) 2008 Nokia Corporation.
  7  *
  8  * Authors: Sakari Ailus <sakari.ailus@nokia.com>
  9  *          RĂ©mi Denis-Courmont
 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 <linux/slab.h>
 29 #include <asm/unaligned.h>
 30 #include <net/sock.h>
 31 
 32 #include <linux/if_phonet.h>
 33 #include <linux/phonet.h>
 34 #include <net/phonet/phonet.h>
 35 #include <net/phonet/pn_dev.h>
 36 
 37 /* Transport protocol registration */
 38 static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 39 
 40 static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
 41 {
 42         const struct phonet_protocol *pp;
 43 
 44         if (protocol >= PHONET_NPROTO)
 45                 return NULL;
 46 
 47         rcu_read_lock();
 48         pp = rcu_dereference(proto_tab[protocol]);
 49         if (pp && !try_module_get(pp->prot->owner))
 50                 pp = NULL;
 51         rcu_read_unlock();
 52 
 53         return pp;
 54 }
 55 
 56 static inline void phonet_proto_put(const struct phonet_protocol *pp)
 57 {
 58         module_put(pp->prot->owner);
 59 }
 60 
 61 /* protocol family functions */
 62 
 63 static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
 64                             int kern)
 65 {
 66         struct sock *sk;
 67         struct pn_sock *pn;
 68         const struct phonet_protocol *pnp;
 69         int err;
 70 
 71         if (!capable(CAP_SYS_ADMIN))
 72                 return -EPERM;
 73 
 74         if (protocol == 0) {
 75                 /* Default protocol selection */
 76                 switch (sock->type) {
 77                 case SOCK_DGRAM:
 78                         protocol = PN_PROTO_PHONET;
 79                         break;
 80                 case SOCK_SEQPACKET:
 81                         protocol = PN_PROTO_PIPE;
 82                         break;
 83                 default:
 84                         return -EPROTONOSUPPORT;
 85                 }
 86         }
 87 
 88         pnp = phonet_proto_get(protocol);
 89         if (pnp == NULL &&
 90             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
 91                 pnp = phonet_proto_get(protocol);
 92 
 93         if (pnp == NULL)
 94                 return -EPROTONOSUPPORT;
 95         if (sock->type != pnp->sock_type) {
 96                 err = -EPROTONOSUPPORT;
 97                 goto out;
 98         }
 99 
100         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot, kern);
101         if (sk == NULL) {
102                 err = -ENOMEM;
103                 goto out;
104         }
105 
106         sock_init_data(sock, sk);
107         sock->state = SS_UNCONNECTED;
108         sock->ops = pnp->ops;
109         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
110         sk->sk_protocol = protocol;
111         pn = pn_sk(sk);
112         pn->sobject = 0;
113         pn->dobject = 0;
114         pn->resource = 0;
115         sk->sk_prot->init(sk);
116         err = 0;
117 
118 out:
119         phonet_proto_put(pnp);
120         return err;
121 }
122 
123 static const struct net_proto_family phonet_proto_family = {
124         .family = PF_PHONET,
125         .create = pn_socket_create,
126         .owner = THIS_MODULE,
127 };
128 
129 /* Phonet device header operations */
130 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
131                                 unsigned short type, const void *daddr,
132                                 const void *saddr, unsigned int len)
133 {
134         u8 *media = skb_push(skb, 1);
135 
136         if (type != ETH_P_PHONET)
137                 return -1;
138 
139         if (!saddr)
140                 saddr = dev->dev_addr;
141         *media = *(const u8 *)saddr;
142         return 1;
143 }
144 
145 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
146 {
147         const u8 *media = skb_mac_header(skb);
148         *haddr = *media;
149         return 1;
150 }
151 
152 const struct header_ops phonet_header_ops = {
153         .create = pn_header_create,
154         .parse = pn_header_parse,
155 };
156 EXPORT_SYMBOL(phonet_header_ops);
157 
158 /*
159  * Prepends an ISI header and sends a datagram.
160  */
161 static int pn_send(struct sk_buff *skb, struct net_device *dev,
162                         u16 dst, u16 src, u8 res, u8 irq)
163 {
164         struct phonethdr *ph;
165         int err;
166 
167         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
168             skb->len + sizeof(struct phonethdr) > dev->mtu) {
169                 err = -EMSGSIZE;
170                 goto drop;
171         }
172 
173         /* Broadcast sending is not implemented */
174         if (pn_addr(dst) == PNADDR_BROADCAST) {
175                 err = -EOPNOTSUPP;
176                 goto drop;
177         }
178 
179         skb_reset_transport_header(skb);
180         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
181         skb_push(skb, sizeof(struct phonethdr));
182         skb_reset_network_header(skb);
183         ph = pn_hdr(skb);
184         ph->pn_rdev = pn_dev(dst);
185         ph->pn_sdev = pn_dev(src);
186         ph->pn_res = res;
187         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
188         ph->pn_robj = pn_obj(dst);
189         ph->pn_sobj = pn_obj(src);
190 
191         skb->protocol = htons(ETH_P_PHONET);
192         skb->priority = 0;
193         skb->dev = dev;
194 
195         if (skb->pkt_type == PACKET_LOOPBACK) {
196                 skb_reset_mac_header(skb);
197                 skb_orphan(skb);
198                 err = (irq ? netif_rx(skb) : netif_rx_ni(skb)) ? -ENOBUFS : 0;
199         } else {
200                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
201                                         NULL, NULL, skb->len);
202                 if (err < 0) {
203                         err = -EHOSTUNREACH;
204                         goto drop;
205                 }
206                 err = dev_queue_xmit(skb);
207                 if (unlikely(err > 0))
208                         err = net_xmit_errno(err);
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, dst;
245         u8 daddr, saddr, res;
246 
247         src = pn->sobject;
248         if (target != NULL) {
249                 dst = pn_sockaddr_get_object(target);
250                 res = pn_sockaddr_get_resource(target);
251         } else {
252                 dst = pn->dobject;
253                 res = pn->resource;
254         }
255         daddr = pn_addr(dst);
256 
257         err = -EHOSTUNREACH;
258         if (sk->sk_bound_dev_if)
259                 dev = dev_get_by_index(net, sk->sk_bound_dev_if);
260         else if (phonet_address_lookup(net, daddr) == 0) {
261                 dev = phonet_device_get(net);
262                 skb->pkt_type = PACKET_LOOPBACK;
263         } else if (dst == 0) {
264                 /* Resource routing (small race until phonet_rcv()) */
265                 struct sock *sk = pn_find_sock_by_res(net, res);
266                 if (sk) {
267                         sock_put(sk);
268                         dev = phonet_device_get(net);
269                         skb->pkt_type = PACKET_LOOPBACK;
270                 } else
271                         dev = phonet_route_output(net, daddr);
272         } else
273                 dev = phonet_route_output(net, daddr);
274 
275         if (!dev || !(dev->flags & IFF_UP))
276                 goto drop;
277 
278         saddr = phonet_address_get(dev, daddr);
279         if (saddr == PN_NO_ADDR)
280                 goto drop;
281 
282         if (!pn_addr(src))
283                 src = pn_object(saddr, pn_obj(src));
284 
285         err = pn_send(skb, dev, dst, src, res, 0);
286         dev_put(dev);
287         return err;
288 
289 drop:
290         kfree_skb(skb);
291         if (dev)
292                 dev_put(dev);
293         return err;
294 }
295 EXPORT_SYMBOL(pn_skb_send);
296 
297 /* Do not send an error message in response to an error message */
298 static inline int can_respond(struct sk_buff *skb)
299 {
300         const struct phonethdr *ph;
301         const struct phonetmsg *pm;
302         u8 submsg_id;
303 
304         if (!pskb_may_pull(skb, 3))
305                 return 0;
306 
307         ph = pn_hdr(skb);
308         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
309                 return 0;
310         if (ph->pn_res == PN_COMMGR) /* indications */
311                 return 0;
312 
313         ph = pn_hdr(skb); /* re-acquires the pointer */
314         pm = pn_msg(skb);
315         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
316                 return 1;
317         submsg_id = (ph->pn_res == PN_PREFIX)
318                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
319         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
320                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
321                 return 1;
322         return 0;
323 }
324 
325 static int send_obj_unreachable(struct sk_buff *rskb)
326 {
327         const struct phonethdr *oph = pn_hdr(rskb);
328         const struct phonetmsg *opm = pn_msg(rskb);
329         struct phonetmsg resp;
330 
331         memset(&resp, 0, sizeof(resp));
332         resp.pn_trans_id = opm->pn_trans_id;
333         resp.pn_msg_id = PN_COMMON_MESSAGE;
334         if (oph->pn_res == PN_PREFIX) {
335                 resp.pn_e_res_id = opm->pn_e_res_id;
336                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
337                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
338                 resp.pn_e_status = 0;
339         } else {
340                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
341                 resp.pn_orig_msg_id = opm->pn_msg_id;
342                 resp.pn_status = 0;
343         }
344         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
345                                 pn_object(oph->pn_sdev, oph->pn_sobj),
346                                 pn_object(oph->pn_rdev, oph->pn_robj),
347                                 oph->pn_res);
348 }
349 
350 static int send_reset_indications(struct sk_buff *rskb)
351 {
352         struct phonethdr *oph = pn_hdr(rskb);
353         static const u8 data[4] = {
354                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
355                 0x00 /* subscription count */, 0x00 /* dummy */
356         };
357 
358         return pn_raw_send(data, sizeof(data), rskb->dev,
359                                 pn_object(oph->pn_sdev, 0x00),
360                                 pn_object(oph->pn_rdev, oph->pn_robj),
361                                 PN_COMMGR);
362 }
363 
364 
365 /* packet type functions */
366 
367 /*
368  * Stuff received packets to associated sockets.
369  * On error, returns non-zero and releases the skb.
370  */
371 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
372                         struct packet_type *pkttype,
373                         struct net_device *orig_dev)
374 {
375         struct net *net = dev_net(dev);
376         struct phonethdr *ph;
377         struct sockaddr_pn sa;
378         u16 len;
379 
380         skb = skb_share_check(skb, GFP_ATOMIC);
381         if (!skb)
382                 return NET_RX_DROP;
383 
384         /* check we have at least a full Phonet header */
385         if (!pskb_pull(skb, sizeof(struct phonethdr)))
386                 goto out;
387 
388         /* check that the advertised length is correct */
389         ph = pn_hdr(skb);
390         len = get_unaligned_be16(&ph->pn_length);
391         if (len < 2)
392                 goto out;
393         len -= 2;
394         if ((len > skb->len) || pskb_trim(skb, len))
395                 goto out;
396         skb_reset_transport_header(skb);
397 
398         pn_skb_get_dst_sockaddr(skb, &sa);
399 
400         /* check if this is broadcasted */
401         if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
402                 pn_deliver_sock_broadcast(net, skb);
403                 goto out;
404         }
405 
406         /* resource routing */
407         if (pn_sockaddr_get_object(&sa) == 0) {
408                 struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
409                 if (sk)
410                         return sk_receive_skb(sk, skb, 0);
411         }
412 
413         /* check if we are the destination */
414         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
415                 /* Phonet packet input */
416                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
417 
418                 if (sk)
419                         return sk_receive_skb(sk, skb, 0);
420 
421                 if (can_respond(skb)) {
422                         send_obj_unreachable(skb);
423                         send_reset_indications(skb);
424                 }
425         } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
426                 goto out; /* Race between address deletion and loopback */
427         else {
428                 /* Phonet packet routing */
429                 struct net_device *out_dev;
430 
431                 out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
432                 if (!out_dev) {
433                         net_dbg_ratelimited("No Phonet route to %02X\n",
434                                             pn_sockaddr_get_addr(&sa));
435                         goto out;
436                 }
437 
438                 __skb_push(skb, sizeof(struct phonethdr));
439                 skb->dev = out_dev;
440                 if (out_dev == dev) {
441                         net_dbg_ratelimited("Phonet loop to %02X on %s\n",
442                                             pn_sockaddr_get_addr(&sa),
443                                             dev->name);
444                         goto out_dev;
445                 }
446                 /* Some drivers (e.g. TUN) do not allocate HW header space */
447                 if (skb_cow_head(skb, out_dev->hard_header_len))
448                         goto out_dev;
449 
450                 if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
451                                         skb->len) < 0)
452                         goto out_dev;
453                 dev_queue_xmit(skb);
454                 dev_put(out_dev);
455                 return NET_RX_SUCCESS;
456 out_dev:
457                 dev_put(out_dev);
458         }
459 
460 out:
461         kfree_skb(skb);
462         return NET_RX_DROP;
463 }
464 
465 static struct packet_type phonet_packet_type __read_mostly = {
466         .type = cpu_to_be16(ETH_P_PHONET),
467         .func = phonet_rcv,
468 };
469 
470 static DEFINE_MUTEX(proto_tab_lock);
471 
472 int __init_or_module phonet_proto_register(unsigned int protocol,
473                                 const struct phonet_protocol *pp)
474 {
475         int err = 0;
476 
477         if (protocol >= PHONET_NPROTO)
478                 return -EINVAL;
479 
480         err = proto_register(pp->prot, 1);
481         if (err)
482                 return err;
483 
484         mutex_lock(&proto_tab_lock);
485         if (proto_tab[protocol])
486                 err = -EBUSY;
487         else
488                 rcu_assign_pointer(proto_tab[protocol], pp);
489         mutex_unlock(&proto_tab_lock);
490 
491         return err;
492 }
493 EXPORT_SYMBOL(phonet_proto_register);
494 
495 void phonet_proto_unregister(unsigned int protocol,
496                         const struct phonet_protocol *pp)
497 {
498         mutex_lock(&proto_tab_lock);
499         BUG_ON(proto_tab[protocol] != pp);
500         RCU_INIT_POINTER(proto_tab[protocol], NULL);
501         mutex_unlock(&proto_tab_lock);
502         synchronize_rcu();
503         proto_unregister(pp->prot);
504 }
505 EXPORT_SYMBOL(phonet_proto_unregister);
506 
507 /* Module registration */
508 static int __init phonet_init(void)
509 {
510         int err;
511 
512         err = phonet_device_init();
513         if (err)
514                 return err;
515 
516         pn_sock_init();
517         err = sock_register(&phonet_proto_family);
518         if (err) {
519                 printk(KERN_ALERT
520                         "phonet protocol family initialization failed\n");
521                 goto err_sock;
522         }
523 
524         dev_add_pack(&phonet_packet_type);
525         phonet_sysctl_init();
526 
527         err = isi_register();
528         if (err)
529                 goto err;
530         return 0;
531 
532 err:
533         phonet_sysctl_exit();
534         sock_unregister(PF_PHONET);
535         dev_remove_pack(&phonet_packet_type);
536 err_sock:
537         phonet_device_exit();
538         return err;
539 }
540 
541 static void __exit phonet_exit(void)
542 {
543         isi_unregister();
544         phonet_sysctl_exit();
545         sock_unregister(PF_PHONET);
546         dev_remove_pack(&phonet_packet_type);
547         phonet_device_exit();
548 }
549 
550 module_init(phonet_init);
551 module_exit(phonet_exit);
552 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
553 MODULE_LICENSE("GPL");
554 MODULE_ALIAS_NETPROTO(PF_PHONET);
555 

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