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Linux/net/phonet/af_phonet.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * File: af_phonet.c
  4  *
  5  * Phonet protocols family
  6  *
  7  * Copyright (C) 2008 Nokia Corporation.
  8  *
  9  * Authors: Sakari Ailus <sakari.ailus@nokia.com>
 10  *          RĂ©mi Denis-Courmont
 11  */
 12 
 13 #include <linux/kernel.h>
 14 #include <linux/module.h>
 15 #include <linux/slab.h>
 16 #include <asm/unaligned.h>
 17 #include <net/sock.h>
 18 
 19 #include <linux/if_phonet.h>
 20 #include <linux/phonet.h>
 21 #include <net/phonet/phonet.h>
 22 #include <net/phonet/pn_dev.h>
 23 
 24 /* Transport protocol registration */
 25 static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 26 
 27 static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
 28 {
 29         const struct phonet_protocol *pp;
 30 
 31         if (protocol >= PHONET_NPROTO)
 32                 return NULL;
 33 
 34         rcu_read_lock();
 35         pp = rcu_dereference(proto_tab[protocol]);
 36         if (pp && !try_module_get(pp->prot->owner))
 37                 pp = NULL;
 38         rcu_read_unlock();
 39 
 40         return pp;
 41 }
 42 
 43 static inline void phonet_proto_put(const struct phonet_protocol *pp)
 44 {
 45         module_put(pp->prot->owner);
 46 }
 47 
 48 /* protocol family functions */
 49 
 50 static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
 51                             int kern)
 52 {
 53         struct sock *sk;
 54         struct pn_sock *pn;
 55         const struct phonet_protocol *pnp;
 56         int err;
 57 
 58         if (!capable(CAP_SYS_ADMIN))
 59                 return -EPERM;
 60 
 61         if (protocol == 0) {
 62                 /* Default protocol selection */
 63                 switch (sock->type) {
 64                 case SOCK_DGRAM:
 65                         protocol = PN_PROTO_PHONET;
 66                         break;
 67                 case SOCK_SEQPACKET:
 68                         protocol = PN_PROTO_PIPE;
 69                         break;
 70                 default:
 71                         return -EPROTONOSUPPORT;
 72                 }
 73         }
 74 
 75         pnp = phonet_proto_get(protocol);
 76         if (pnp == NULL &&
 77             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
 78                 pnp = phonet_proto_get(protocol);
 79 
 80         if (pnp == NULL)
 81                 return -EPROTONOSUPPORT;
 82         if (sock->type != pnp->sock_type) {
 83                 err = -EPROTONOSUPPORT;
 84                 goto out;
 85         }
 86 
 87         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot, kern);
 88         if (sk == NULL) {
 89                 err = -ENOMEM;
 90                 goto out;
 91         }
 92 
 93         sock_init_data(sock, sk);
 94         sock->state = SS_UNCONNECTED;
 95         sock->ops = pnp->ops;
 96         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
 97         sk->sk_protocol = protocol;
 98         pn = pn_sk(sk);
 99         pn->sobject = 0;
100         pn->dobject = 0;
101         pn->resource = 0;
102         sk->sk_prot->init(sk);
103         err = 0;
104 
105 out:
106         phonet_proto_put(pnp);
107         return err;
108 }
109 
110 static const struct net_proto_family phonet_proto_family = {
111         .family = PF_PHONET,
112         .create = pn_socket_create,
113         .owner = THIS_MODULE,
114 };
115 
116 /* Phonet device header operations */
117 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
118                                 unsigned short type, const void *daddr,
119                                 const void *saddr, unsigned int len)
120 {
121         u8 *media = skb_push(skb, 1);
122 
123         if (type != ETH_P_PHONET)
124                 return -1;
125 
126         if (!saddr)
127                 saddr = dev->dev_addr;
128         *media = *(const u8 *)saddr;
129         return 1;
130 }
131 
132 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
133 {
134         const u8 *media = skb_mac_header(skb);
135         *haddr = *media;
136         return 1;
137 }
138 
139 const struct header_ops phonet_header_ops = {
140         .create = pn_header_create,
141         .parse = pn_header_parse,
142 };
143 EXPORT_SYMBOL(phonet_header_ops);
144 
145 /*
146  * Prepends an ISI header and sends a datagram.
147  */
148 static int pn_send(struct sk_buff *skb, struct net_device *dev,
149                         u16 dst, u16 src, u8 res, u8 irq)
150 {
151         struct phonethdr *ph;
152         int err;
153 
154         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
155             skb->len + sizeof(struct phonethdr) > dev->mtu) {
156                 err = -EMSGSIZE;
157                 goto drop;
158         }
159 
160         /* Broadcast sending is not implemented */
161         if (pn_addr(dst) == PNADDR_BROADCAST) {
162                 err = -EOPNOTSUPP;
163                 goto drop;
164         }
165 
166         skb_reset_transport_header(skb);
167         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
168         skb_push(skb, sizeof(struct phonethdr));
169         skb_reset_network_header(skb);
170         ph = pn_hdr(skb);
171         ph->pn_rdev = pn_dev(dst);
172         ph->pn_sdev = pn_dev(src);
173         ph->pn_res = res;
174         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
175         ph->pn_robj = pn_obj(dst);
176         ph->pn_sobj = pn_obj(src);
177 
178         skb->protocol = htons(ETH_P_PHONET);
179         skb->priority = 0;
180         skb->dev = dev;
181 
182         if (skb->pkt_type == PACKET_LOOPBACK) {
183                 skb_reset_mac_header(skb);
184                 skb_orphan(skb);
185                 err = (irq ? netif_rx(skb) : netif_rx_ni(skb)) ? -ENOBUFS : 0;
186         } else {
187                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
188                                         NULL, NULL, skb->len);
189                 if (err < 0) {
190                         err = -EHOSTUNREACH;
191                         goto drop;
192                 }
193                 err = dev_queue_xmit(skb);
194                 if (unlikely(err > 0))
195                         err = net_xmit_errno(err);
196         }
197 
198         return err;
199 drop:
200         kfree_skb(skb);
201         return err;
202 }
203 
204 static int pn_raw_send(const void *data, int len, struct net_device *dev,
205                         u16 dst, u16 src, u8 res)
206 {
207         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
208         if (skb == NULL)
209                 return -ENOMEM;
210 
211         if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
212                 skb->pkt_type = PACKET_LOOPBACK;
213 
214         skb_reserve(skb, MAX_PHONET_HEADER);
215         __skb_put(skb, len);
216         skb_copy_to_linear_data(skb, data, len);
217         return pn_send(skb, dev, dst, src, res, 1);
218 }
219 
220 /*
221  * Create a Phonet header for the skb and send it out. Returns
222  * non-zero error code if failed. The skb is freed then.
223  */
224 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
225                 const struct sockaddr_pn *target)
226 {
227         struct net *net = sock_net(sk);
228         struct net_device *dev;
229         struct pn_sock *pn = pn_sk(sk);
230         int err;
231         u16 src, dst;
232         u8 daddr, saddr, res;
233 
234         src = pn->sobject;
235         if (target != NULL) {
236                 dst = pn_sockaddr_get_object(target);
237                 res = pn_sockaddr_get_resource(target);
238         } else {
239                 dst = pn->dobject;
240                 res = pn->resource;
241         }
242         daddr = pn_addr(dst);
243 
244         err = -EHOSTUNREACH;
245         if (sk->sk_bound_dev_if)
246                 dev = dev_get_by_index(net, sk->sk_bound_dev_if);
247         else if (phonet_address_lookup(net, daddr) == 0) {
248                 dev = phonet_device_get(net);
249                 skb->pkt_type = PACKET_LOOPBACK;
250         } else if (dst == 0) {
251                 /* Resource routing (small race until phonet_rcv()) */
252                 struct sock *sk = pn_find_sock_by_res(net, res);
253                 if (sk) {
254                         sock_put(sk);
255                         dev = phonet_device_get(net);
256                         skb->pkt_type = PACKET_LOOPBACK;
257                 } else
258                         dev = phonet_route_output(net, daddr);
259         } else
260                 dev = phonet_route_output(net, daddr);
261 
262         if (!dev || !(dev->flags & IFF_UP))
263                 goto drop;
264 
265         saddr = phonet_address_get(dev, daddr);
266         if (saddr == PN_NO_ADDR)
267                 goto drop;
268 
269         if (!pn_addr(src))
270                 src = pn_object(saddr, pn_obj(src));
271 
272         err = pn_send(skb, dev, dst, src, res, 0);
273         dev_put(dev);
274         return err;
275 
276 drop:
277         kfree_skb(skb);
278         dev_put(dev);
279         return err;
280 }
281 EXPORT_SYMBOL(pn_skb_send);
282 
283 /* Do not send an error message in response to an error message */
284 static inline int can_respond(struct sk_buff *skb)
285 {
286         const struct phonethdr *ph;
287         const struct phonetmsg *pm;
288         u8 submsg_id;
289 
290         if (!pskb_may_pull(skb, 3))
291                 return 0;
292 
293         ph = pn_hdr(skb);
294         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
295                 return 0;
296         if (ph->pn_res == PN_COMMGR) /* indications */
297                 return 0;
298 
299         ph = pn_hdr(skb); /* re-acquires the pointer */
300         pm = pn_msg(skb);
301         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
302                 return 1;
303         submsg_id = (ph->pn_res == PN_PREFIX)
304                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
305         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
306                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
307                 return 1;
308         return 0;
309 }
310 
311 static int send_obj_unreachable(struct sk_buff *rskb)
312 {
313         const struct phonethdr *oph = pn_hdr(rskb);
314         const struct phonetmsg *opm = pn_msg(rskb);
315         struct phonetmsg resp;
316 
317         memset(&resp, 0, sizeof(resp));
318         resp.pn_trans_id = opm->pn_trans_id;
319         resp.pn_msg_id = PN_COMMON_MESSAGE;
320         if (oph->pn_res == PN_PREFIX) {
321                 resp.pn_e_res_id = opm->pn_e_res_id;
322                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
323                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
324                 resp.pn_e_status = 0;
325         } else {
326                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
327                 resp.pn_orig_msg_id = opm->pn_msg_id;
328                 resp.pn_status = 0;
329         }
330         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
331                                 pn_object(oph->pn_sdev, oph->pn_sobj),
332                                 pn_object(oph->pn_rdev, oph->pn_robj),
333                                 oph->pn_res);
334 }
335 
336 static int send_reset_indications(struct sk_buff *rskb)
337 {
338         struct phonethdr *oph = pn_hdr(rskb);
339         static const u8 data[4] = {
340                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
341                 0x00 /* subscription count */, 0x00 /* dummy */
342         };
343 
344         return pn_raw_send(data, sizeof(data), rskb->dev,
345                                 pn_object(oph->pn_sdev, 0x00),
346                                 pn_object(oph->pn_rdev, oph->pn_robj),
347                                 PN_COMMGR);
348 }
349 
350 
351 /* packet type functions */
352 
353 /*
354  * Stuff received packets to associated sockets.
355  * On error, returns non-zero and releases the skb.
356  */
357 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
358                         struct packet_type *pkttype,
359                         struct net_device *orig_dev)
360 {
361         struct net *net = dev_net(dev);
362         struct phonethdr *ph;
363         struct sockaddr_pn sa;
364         u16 len;
365 
366         skb = skb_share_check(skb, GFP_ATOMIC);
367         if (!skb)
368                 return NET_RX_DROP;
369 
370         /* check we have at least a full Phonet header */
371         if (!pskb_pull(skb, sizeof(struct phonethdr)))
372                 goto out;
373 
374         /* check that the advertised length is correct */
375         ph = pn_hdr(skb);
376         len = get_unaligned_be16(&ph->pn_length);
377         if (len < 2)
378                 goto out;
379         len -= 2;
380         if ((len > skb->len) || pskb_trim(skb, len))
381                 goto out;
382         skb_reset_transport_header(skb);
383 
384         pn_skb_get_dst_sockaddr(skb, &sa);
385 
386         /* check if this is broadcasted */
387         if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
388                 pn_deliver_sock_broadcast(net, skb);
389                 goto out;
390         }
391 
392         /* resource routing */
393         if (pn_sockaddr_get_object(&sa) == 0) {
394                 struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
395                 if (sk)
396                         return sk_receive_skb(sk, skb, 0);
397         }
398 
399         /* check if we are the destination */
400         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
401                 /* Phonet packet input */
402                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
403 
404                 if (sk)
405                         return sk_receive_skb(sk, skb, 0);
406 
407                 if (can_respond(skb)) {
408                         send_obj_unreachable(skb);
409                         send_reset_indications(skb);
410                 }
411         } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
412                 goto out; /* Race between address deletion and loopback */
413         else {
414                 /* Phonet packet routing */
415                 struct net_device *out_dev;
416 
417                 out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
418                 if (!out_dev) {
419                         net_dbg_ratelimited("No Phonet route to %02X\n",
420                                             pn_sockaddr_get_addr(&sa));
421                         goto out;
422                 }
423 
424                 __skb_push(skb, sizeof(struct phonethdr));
425                 skb->dev = out_dev;
426                 if (out_dev == dev) {
427                         net_dbg_ratelimited("Phonet loop to %02X on %s\n",
428                                             pn_sockaddr_get_addr(&sa),
429                                             dev->name);
430                         goto out_dev;
431                 }
432                 /* Some drivers (e.g. TUN) do not allocate HW header space */
433                 if (skb_cow_head(skb, out_dev->hard_header_len))
434                         goto out_dev;
435 
436                 if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
437                                         skb->len) < 0)
438                         goto out_dev;
439                 dev_queue_xmit(skb);
440                 dev_put(out_dev);
441                 return NET_RX_SUCCESS;
442 out_dev:
443                 dev_put(out_dev);
444         }
445 
446 out:
447         kfree_skb(skb);
448         return NET_RX_DROP;
449 }
450 
451 static struct packet_type phonet_packet_type __read_mostly = {
452         .type = cpu_to_be16(ETH_P_PHONET),
453         .func = phonet_rcv,
454 };
455 
456 static DEFINE_MUTEX(proto_tab_lock);
457 
458 int __init_or_module phonet_proto_register(unsigned int protocol,
459                                 const struct phonet_protocol *pp)
460 {
461         int err = 0;
462 
463         if (protocol >= PHONET_NPROTO)
464                 return -EINVAL;
465 
466         err = proto_register(pp->prot, 1);
467         if (err)
468                 return err;
469 
470         mutex_lock(&proto_tab_lock);
471         if (proto_tab[protocol])
472                 err = -EBUSY;
473         else
474                 rcu_assign_pointer(proto_tab[protocol], pp);
475         mutex_unlock(&proto_tab_lock);
476 
477         return err;
478 }
479 EXPORT_SYMBOL(phonet_proto_register);
480 
481 void phonet_proto_unregister(unsigned int protocol,
482                         const struct phonet_protocol *pp)
483 {
484         mutex_lock(&proto_tab_lock);
485         BUG_ON(proto_tab[protocol] != pp);
486         RCU_INIT_POINTER(proto_tab[protocol], NULL);
487         mutex_unlock(&proto_tab_lock);
488         synchronize_rcu();
489         proto_unregister(pp->prot);
490 }
491 EXPORT_SYMBOL(phonet_proto_unregister);
492 
493 /* Module registration */
494 static int __init phonet_init(void)
495 {
496         int err;
497 
498         err = phonet_device_init();
499         if (err)
500                 return err;
501 
502         pn_sock_init();
503         err = sock_register(&phonet_proto_family);
504         if (err) {
505                 printk(KERN_ALERT
506                         "phonet protocol family initialization failed\n");
507                 goto err_sock;
508         }
509 
510         dev_add_pack(&phonet_packet_type);
511         phonet_sysctl_init();
512 
513         err = isi_register();
514         if (err)
515                 goto err;
516         return 0;
517 
518 err:
519         phonet_sysctl_exit();
520         sock_unregister(PF_PHONET);
521         dev_remove_pack(&phonet_packet_type);
522 err_sock:
523         phonet_device_exit();
524         return err;
525 }
526 
527 static void __exit phonet_exit(void)
528 {
529         isi_unregister();
530         phonet_sysctl_exit();
531         sock_unregister(PF_PHONET);
532         dev_remove_pack(&phonet_packet_type);
533         phonet_device_exit();
534 }
535 
536 module_init(phonet_init);
537 module_exit(phonet_exit);
538 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
539 MODULE_LICENSE("GPL");
540 MODULE_ALIAS_NETPROTO(PF_PHONET);
541 

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