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