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  * Authors: Sakari Ailus <sakari.ailus@nokia.com>
   9  *          Rémi 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);