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 <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 struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
  39
  40 static struct phonet_protocol *phonet_proto_get(int protocol)
  41 {
  42         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(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         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);
 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->resource = 0;
 114         sk->sk_prot->init(sk);
 115         err = 0;
 116
 117 out:
 118         phonet_proto_put(pnp);
 119         return err;
 120 }
 121
 122 static const struct net_proto_family phonet_proto_family = {
 123         .family = PF_PHONET,
 124         .create = pn_socket_create,
 125         .owner = THIS_MODULE,
 126 };
 127
 128 /* Phonet device header operations */
 129 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 130                                 unsigned short type, const void *daddr,
 131                                 const void *saddr, unsigned len)
 132 {
 133         u8 *media = skb_push(skb, 1);
 134
 135         if (type != ETH_P_PHONET)
 136                 return -1;
 137
 138         if (!saddr)
 139                 saddr = dev->dev_addr;
 140         *media = *(const u8 *)saddr;
 141         return 1;
 142 }
 143
 144 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 145 {
 146         const u8 *media = skb_mac_header(skb);
 147         *haddr = *media;
 148         return 1;
 149 }
 150
 151 struct header_ops phonet_header_ops = {
 152         .create = pn_header_create,
 153         .parse = pn_header_parse,
 154 };
 155 EXPORT_SYMBOL(phonet_header_ops);
 156
 157 /*
 158  * Prepends an ISI header and sends a datagram.
 159  */
 160 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 161                         u16 dst, u16 src, u8 res, u8 irq)
 162 {
 163         struct phonethdr *ph;
 164         int err;
 165
 166         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
 167             skb->len + sizeof(struct phonethdr) > dev->mtu) {
 168                 err = -EMSGSIZE;
 169                 goto drop;
 170         }
 171
 172         /* Broadcast sending is not implemented */
 173         if (pn_addr(dst) == PNADDR_BROADCAST) {
 174                 err = -EOPNOTSUPP;
 175                 goto drop;
 176         }
 177
 178         skb_reset_transport_header(skb);
 179         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 180         skb_push(skb, sizeof(struct phonethdr));
 181         skb_reset_network_header(skb);
 182         ph = pn_hdr(skb);
 183         ph->pn_rdev = pn_dev(dst);
 184         ph->pn_sdev = pn_dev(src);
 185         ph->pn_res = res;
 186         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 187         ph->pn_robj = pn_obj(dst);
 188         ph->pn_sobj = pn_obj(src);
 189
 190         skb->protocol = htons(ETH_P_PHONET);
 191         skb->priority = 0;
 192         skb->dev = dev;
 193
 194         if (skb->pkt_type == PACKET_LOOPBACK) {
 195                 skb_reset_mac_header(skb);
 196                 skb_orphan(skb);
 197                 if (irq)
 198                         netif_rx(skb);
 199                 else
 200                         netif_rx_ni(skb);
 201                 err = 0;
 202         } else {
 203                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 204                                         NULL, NULL, skb->len);
 205                 if (err < 0) {
 206                         err = -EHOSTUNREACH;
 207                         goto drop;
 208                 }
 209                 err = dev_queue_xmit(skb);
 210         }
 211
 212         return err;
 213 drop:
 214         kfree_skb(skb);
 215         return err;
 216 }
 217
 218 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 219                         u16 dst, u16 src, u8 res)
 220 {
 221         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 222         if (skb == NULL)
 223                 return -ENOMEM;
 224
 225         if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
 226                 skb->pkt_type = PACKET_LOOPBACK;
 227
 228         skb_reserve(skb, MAX_PHONET_HEADER);
 229         __skb_put(skb, len);
 230         skb_copy_to_linear_data(skb, data, len);
 231         return pn_send(skb, dev, dst, src, res, 1);
 232 }
 233
 234 /*
 235  * Create a Phonet header for the skb and send it out. Returns
 236  * non-zero error code if failed. The skb is freed then.
 237  */
 238 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 239                 const struct sockaddr_pn *target)
 240 {
 241         struct net *net = sock_net(sk);
 242         struct net_device *dev;
 243         struct pn_sock *pn = pn_sk(sk);
 244         int err;
 245         u16 src;
 246         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
 247
 248         err = -EHOSTUNREACH;
 249         if (sk->sk_bound_dev_if)
 250                 dev = dev_get_by_index(net, sk->sk_bound_dev_if);
 251         else if (phonet_address_lookup(net, daddr) == 0) {
 252                 dev = phonet_device_get(net);
 253                 skb->pkt_type = PACKET_LOOPBACK;
 254         } else
 255                 dev = phonet_route_output(net, daddr);
 256
 257         if (!dev || !(dev->flags & IFF_UP))
 258                 goto drop;
 259
 260         saddr = phonet_address_get(dev, daddr);
 261         if (saddr == PN_NO_ADDR)
 262                 goto drop;
 263
 264         src = pn->sobject;
 265         if (!pn_addr(src))
 266                 src = pn_object(saddr, pn_obj(src));
 267
 268         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
 269                         src, pn_sockaddr_get_resource(target), 0);
 270         dev_put(dev);
 271         return err;
 272
 273 drop:
 274         kfree_skb(skb);
 275         if (dev)
 276                 dev_put(dev);
 277         return err;
 278 }
 279 EXPORT_SYMBOL(pn_skb_send);
 280
 281 /* Do not send an error message in response to an error message */
 282 static inline int can_respond(struct sk_buff *skb)
 283 {
 284         const struct phonethdr *ph;
 285         const struct phonetmsg *pm;
 286         u8 submsg_id;
 287
 288         if (!pskb_may_pull(skb, 3))
 289                 return 0;
 290
 291         ph = pn_hdr(skb);
 292         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 293                 return 0;
 294         if (ph->pn_res == PN_COMMGR) /* indications */
 295                 return 0;
 296
 297         ph = pn_hdr(skb); /* re-acquires the pointer */
 298         pm = pn_msg(skb);
 299         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 300                 return 1;
 301         submsg_id = (ph->pn_res == PN_PREFIX)
 302                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 303         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 304                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 305                 return 1;
 306         return 0;
 307 }
 308
 309 static int send_obj_unreachable(struct sk_buff *rskb)
 310 {
 311         const struct phonethdr *oph = pn_hdr(rskb);
 312         const struct phonetmsg *opm = pn_msg(rskb);
 313         struct phonetmsg resp;
 314
 315         memset(&resp, 0, sizeof(resp));
 316         resp.pn_trans_id = opm->pn_trans_id;
 317         resp.pn_msg_id = PN_COMMON_MESSAGE;
 318         if (oph->pn_res == PN_PREFIX) {
 319                 resp.pn_e_res_id = opm->pn_e_res_id;
 320                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 321                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 322                 resp.pn_e_status = 0;
 323         } else {
 324                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 325                 resp.pn_orig_msg_id = opm->pn_msg_id;
 326                 resp.pn_status = 0;
 327         }
 328         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 329                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 330                                 pn_object(oph->pn_rdev, oph->pn_robj),
 331                                 oph->pn_res);
 332 }
 333
 334 static int send_reset_indications(struct sk_buff *rskb)
 335 {
 336         struct phonethdr *oph = pn_hdr(rskb);
 337         static const u8 data[4] = {
 338                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 339                 0x00 /* subscription count */, 0x00 /* dummy */
 340         };
 341
 342         return pn_raw_send(data, sizeof(data), rskb->dev,
 343                                 pn_object(oph->pn_sdev, 0x00),
 344                                 pn_object(oph->pn_rdev, oph->pn_robj),
 345                                 PN_COMMGR);
 346 }
 347
 348
 349 /* packet type functions */
 350
 351 /*
 352  * Stuff received packets to associated sockets.
 353  * On error, returns non-zero and releases the skb.
 354  */
 355 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 356                         struct packet_type *pkttype,
 357                         struct net_device *orig_dev)
 358 {
 359         struct net *net = dev_net(dev);
 360         struct phonethdr *ph;
 361         struct sockaddr_pn sa;
 362         u16 len;
 363
 364         /* check we have at least a full Phonet header */
 365         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 366                 goto out;
 367
 368         /* check that the advertised length is correct */
 369         ph = pn_hdr(skb);
 370         len = get_unaligned_be16(&ph->pn_length);
 371         if (len < 2)
 372                 goto out;
 373         len -= 2;
 374         if ((len > skb->len) || pskb_trim(skb, len))
 375                 goto out;
 376         skb_reset_transport_header(skb);
 377
 378         pn_skb_get_dst_sockaddr(skb, &sa);
 379
 380         /* check if this is broadcasted */
 381         if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
 382                 pn_deliver_sock_broadcast(net, skb);
 383                 goto out;
 384         }
 385
 386         /* check if we are the destination */
 387         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 388                 /* Phonet packet input */
 389                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
 390
 391                 if (sk)
 392                         return sk_receive_skb(sk, skb, 0);
 393
 394                 if (can_respond(skb)) {
 395                         send_obj_unreachable(skb);
 396                         send_reset_indications(skb);
 397                 }
 398         } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 399                 goto out; /* Race between address deletion and loopback */
 400         else {
 401                 /* Phonet packet routing */
 402                 struct net_device *out_dev;
 403
 404                 out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
 405                 if (!out_dev) {
 406                         LIMIT_NETDEBUG(KERN_WARNING"No Phonet route to %02X\n",
 407                                         pn_sockaddr_get_addr(&sa));
 408                         goto out;
 409                 }
 410
 411                 __skb_push(skb, sizeof(struct phonethdr));
 412                 skb->dev = out_dev;
 413                 if (out_dev == dev) {
 414                         LIMIT_NETDEBUG(KERN_ERR"Phonet loop to %02X on %s\n",
 415                                         pn_sockaddr_get_addr(&sa), dev->name);
 416                         goto out_dev;
 417                 }
 418                 /* Some drivers (e.g. TUN) do not allocate HW header space */
 419                 if (skb_cow_head(skb, out_dev->hard_header_len))
 420                         goto out_dev;
 421
 422                 if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
 423                                         skb->len) < 0)
 424                         goto out_dev;
 425                 dev_queue_xmit(skb);
 426                 dev_put(out_dev);
 427                 return NET_RX_SUCCESS;
 428 out_dev:
 429                 dev_put(out_dev);
 430         }
 431
 432 out:
 433         kfree_skb(skb);
 434         return NET_RX_DROP;
 435 }
 436
 437 static struct packet_type phonet_packet_type __read_mostly = {
 438         .type = cpu_to_be16(ETH_P_PHONET),
 439         .func = phonet_rcv,
 440 };
 441
 442 static DEFINE_MUTEX(proto_tab_lock);
 443
 444 int __init_or_module phonet_proto_register(int protocol,
 445                                                 struct phonet_protocol *pp)
 446 {
 447         int err = 0;
 448
 449         if (protocol >= PHONET_NPROTO)
 450                 return -EINVAL;
 451
 452         err = proto_register(pp->prot, 1);
 453         if (err)
 454                 return err;
 455
 456         mutex_lock(&proto_tab_lock);
 457         if (proto_tab[protocol])
 458                 err = -EBUSY;
 459         else
 460                 rcu_assign_pointer(proto_tab[protocol], pp);
 461         mutex_unlock(&proto_tab_lock);
 462
 463         return err;
 464 }
 465 EXPORT_SYMBOL(phonet_proto_register);
 466
 467 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 468 {
 469         mutex_lock(&proto_tab_lock);
 470         BUG_ON(proto_tab[protocol] != pp);
 471         rcu_assign_pointer(proto_tab[protocol], NULL);
 472         mutex_unlock(&proto_tab_lock);
 473         synchronize_rcu();
 474         proto_unregister(pp->prot);
 475 }
 476 EXPORT_SYMBOL(phonet_proto_unregister);
 477
 478 /* Module registration */
 479 static int __init phonet_init(void)
 480 {
 481         int err;
 482
 483         err = phonet_device_init();
 484         if (err)
 485                 return err;
 486
 487         pn_sock_init();
 488         err = sock_register(&phonet_proto_family);
 489         if (err) {
 490                 printk(KERN_ALERT
 491                         "phonet protocol family initialization failed\n");
 492                 goto err_sock;
 493         }
 494
 495         dev_add_pack(&phonet_packet_type);
 496         phonet_sysctl_init();
 497
 498         err = isi_register();
 499         if (err)
 500                 goto err;
 501         return 0;
 502
 503 err:
 504         phonet_sysctl_exit();
 505         sock_unregister(PF_PHONET);
 506         dev_remove_pack(&phonet_packet_type);
 507 err_sock:
 508         phonet_device_exit();
 509         return err;
 510 }
 511
 512 static void __exit phonet_exit(void)
 513 {
 514         isi_unregister();
 515         phonet_sysctl_exit();
 516         sock_unregister(PF_PHONET);
 517         dev_remove_pack(&phonet_packet_type);
 518         phonet_device_exit();
 519 }
 520
 521 module_init(phonet_init);
 522 module_exit(phonet_exit);
 523 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 524 MODULE_LICENSE("GPL");
 525 MODULE_ALIAS_NETPROTO(PF_PHONET);