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 static struct net_proto_family phonet_proto_family;
  37 static struct phonet_protocol *phonet_proto_get(int protocol);
  38 static inline void phonet_proto_put(struct phonet_protocol *pp);
  39
  40 /* protocol family functions */
  41
  42 static int pn_socket_create(struct net *net, struct socket *sock, int protocol)
  43 {
  44         struct sock *sk;
  45         struct pn_sock *pn;
  46         struct phonet_protocol *pnp;
  47         int err;
  48
  49         if (net != &init_net)
  50                 return -EAFNOSUPPORT;
  51
  52         if (!capable(CAP_SYS_ADMIN))
  53                 return -EPERM;
  54
  55         if (protocol == 0) {
  56                 /* Default protocol selection */
  57                 switch (sock->type) {
  58                 case SOCK_DGRAM:
  59                         protocol = PN_PROTO_PHONET;
  60                         break;
  61                 default:
  62                         return -EPROTONOSUPPORT;
  63                 }
  64         }
  65
  66         pnp = phonet_proto_get(protocol);
  67 #ifdef CONFIG_KMOD
  68         if (pnp == NULL &&
  69             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
  70                 pnp = phonet_proto_get(protocol);
  71 #endif
  72         if (pnp == NULL)
  73                 return -EPROTONOSUPPORT;
  74         if (sock->type != pnp->sock_type) {
  75                 err = -EPROTONOSUPPORT;
  76                 goto out;
  77         }
  78
  79         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
  80         if (sk == NULL) {
  81                 err = -ENOMEM;
  82                 goto out;
  83         }
  84
  85         sock_init_data(sock, sk);
  86         sock->state = SS_UNCONNECTED;
  87         sock->ops = pnp->ops;
  88         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
  89         sk->sk_protocol = protocol;
  90         pn = pn_sk(sk);
  91         pn->sobject = 0;
  92         pn->resource = 0;
  93         sk->sk_prot->init(sk);
  94         err = 0;
  95
  96 out:
  97         phonet_proto_put(pnp);
  98         return err;
  99 }
 100
 101 static struct net_proto_family phonet_proto_family = {
 102         .family = PF_PHONET,
 103         .create = pn_socket_create,
 104         .owner = THIS_MODULE,
 105 };
 106
 107 /* Phonet device header operations */
 108 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 109                                 unsigned short type, const void *daddr,
 110                                 const void *saddr, unsigned len)
 111 {
 112         u8 *media = skb_push(skb, 1);
 113
 114         if (type != ETH_P_PHONET)
 115                 return -1;
 116
 117         if (!saddr)
 118                 saddr = dev->dev_addr;
 119         *media = *(const u8 *)saddr;
 120         return 1;
 121 }
 122
 123 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 124 {
 125         const u8 *media = skb_mac_header(skb);
 126         *haddr = *media;
 127         return 1;
 128 }
 129
 130 struct header_ops phonet_header_ops = {
 131         .create = pn_header_create,
 132         .parse = pn_header_parse,
 133 };
 134 EXPORT_SYMBOL(phonet_header_ops);
 135
 136 /*
 137  * Prepends an ISI header and sends a datagram.
 138  */
 139 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 140                         u16 dst, u16 src, u8 res, u8 irq)
 141 {
 142         struct phonethdr *ph;
 143         int err;
 144
 145         if (skb->len + 2 > 0xffff) {
 146                 /* Phonet length field would overflow */
 147                 err = -EMSGSIZE;
 148                 goto drop;
 149         }
 150
 151         skb_reset_transport_header(skb);
 152         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 153         skb_push(skb, sizeof(struct phonethdr));
 154         skb_reset_network_header(skb);
 155         ph = pn_hdr(skb);
 156         ph->pn_rdev = pn_dev(dst);
 157         ph->pn_sdev = pn_dev(src);
 158         ph->pn_res = res;
 159         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 160         ph->pn_robj = pn_obj(dst);
 161         ph->pn_sobj = pn_obj(src);
 162
 163         skb->protocol = htons(ETH_P_PHONET);
 164         skb->priority = 0;
 165         skb->dev = dev;
 166
 167         if (pn_addr(src) == pn_addr(dst)) {
 168                 skb_reset_mac_header(skb);
 169                 skb->pkt_type = PACKET_LOOPBACK;
 170                 skb_orphan(skb);
 171                 if (irq)
 172                         netif_rx(skb);
 173                 else
 174                         netif_rx_ni(skb);
 175                 err = 0;
 176         } else {
 177                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 178                                         NULL, NULL, skb->len);
 179                 if (err < 0) {
 180                         err = -EHOSTUNREACH;
 181                         goto drop;
 182                 }
 183                 err = dev_queue_xmit(skb);
 184         }
 185
 186         return err;
 187 drop:
 188         kfree_skb(skb);
 189         return err;
 190 }
 191
 192 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 193                         u16 dst, u16 src, u8 res)
 194 {
 195         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 196         if (skb == NULL)
 197                 return -ENOMEM;
 198
 199         skb_reserve(skb, MAX_PHONET_HEADER);
 200         __skb_put(skb, len);
 201         skb_copy_to_linear_data(skb, data, len);
 202         return pn_send(skb, dev, dst, src, res, 1);
 203 }
 204
 205 /*
 206  * Create a Phonet header for the skb and send it out. Returns
 207  * non-zero error code if failed. The skb is freed then.
 208  */
 209 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 210                 const struct sockaddr_pn *target)
 211 {
 212         struct net_device *dev;
 213         struct pn_sock *pn = pn_sk(sk);
 214         int err;
 215         u16 src;
 216         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
 217
 218         err = -EHOSTUNREACH;
 219         if (sk->sk_bound_dev_if)
 220                 dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
 221         else
 222                 dev = phonet_device_get(sock_net(sk));
 223         if (!dev || !(dev->flags & IFF_UP))
 224                 goto drop;
 225
 226         saddr = phonet_address_get(dev, daddr);
 227         if (saddr == PN_NO_ADDR)
 228                 goto drop;
 229
 230         src = pn->sobject;
 231         if (!pn_addr(src))
 232                 src = pn_object(saddr, pn_obj(src));
 233
 234         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
 235                         src, pn_sockaddr_get_resource(target), 0);
 236         dev_put(dev);
 237         return err;
 238
 239 drop:
 240         kfree_skb(skb);
 241         if (dev)
 242                 dev_put(dev);
 243         return err;
 244 }
 245 EXPORT_SYMBOL(pn_skb_send);
 246
 247 /* Do not send an error message in response to an error message */
 248 static inline int can_respond(struct sk_buff *skb)
 249 {
 250         const struct phonethdr *ph;
 251         const struct phonetmsg *pm;
 252         u8 submsg_id;
 253
 254         if (!pskb_may_pull(skb, 3))
 255                 return 0;
 256
 257         ph = pn_hdr(skb);
 258         if (phonet_address_get(skb->dev, ph->pn_rdev) != ph->pn_rdev)
 259                 return 0; /* we are not the destination */
 260         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 261                 return 0;
 262
 263         ph = pn_hdr(skb); /* re-acquires the pointer */
 264         pm = pn_msg(skb);
 265         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 266                 return 1;
 267         submsg_id = (ph->pn_res == PN_PREFIX)
 268                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 269         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 270                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 271                 return 1;
 272         return 0;
 273 }
 274
 275 static int send_obj_unreachable(struct sk_buff *rskb)
 276 {
 277         const struct phonethdr *oph = pn_hdr(rskb);
 278         const struct phonetmsg *opm = pn_msg(rskb);
 279         struct phonetmsg resp;
 280
 281         memset(&resp, 0, sizeof(resp));
 282         resp.pn_trans_id = opm->pn_trans_id;
 283         resp.pn_msg_id = PN_COMMON_MESSAGE;
 284         if (oph->pn_res == PN_PREFIX) {
 285                 resp.pn_e_res_id = opm->pn_e_res_id;
 286                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 287                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 288                 resp.pn_e_status = 0;
 289         } else {
 290                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 291                 resp.pn_orig_msg_id = opm->pn_msg_id;
 292                 resp.pn_status = 0;
 293         }
 294         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 295                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 296                                 pn_object(oph->pn_rdev, oph->pn_robj),
 297                                 oph->pn_res);
 298 }
 299
 300 static int send_reset_indications(struct sk_buff *rskb)
 301 {
 302         struct phonethdr *oph = pn_hdr(rskb);
 303         static const u8 data[4] = {
 304                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 305                 0x00 /* subscription count */, 0x00 /* dummy */
 306         };
 307
 308         return pn_raw_send(data, sizeof(data), rskb->dev,
 309                                 pn_object(oph->pn_sdev, 0x00),
 310                                 pn_object(oph->pn_rdev, oph->pn_robj), 0x10);
 311 }
 312
 313
 314 /* packet type functions */
 315
 316 /*
 317  * Stuff received packets to associated sockets.
 318  * On error, returns non-zero and releases the skb.
 319  */
 320 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 321                         struct packet_type *pkttype,
 322                         struct net_device *orig_dev)
 323 {
 324         struct phonethdr *ph;
 325         struct sock *sk;
 326         struct sockaddr_pn sa;
 327         u16 len;
 328
 329         if (dev_net(dev) != &init_net)
 330                 goto out;
 331
 332         /* check we have at least a full Phonet header */
 333         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 334                 goto out;
 335
 336         /* check that the advertised length is correct */
 337         ph = pn_hdr(skb);
 338         len = get_unaligned_be16(&ph->pn_length);
 339         if (len < 2)
 340                 goto out;
 341         len -= 2;
 342         if ((len > skb->len) || pskb_trim(skb, len))
 343                 goto out;
 344         skb_reset_transport_header(skb);
 345
 346         pn_skb_get_dst_sockaddr(skb, &sa);
 347         if (pn_sockaddr_get_addr(&sa) == 0)
 348                 goto out; /* currently, we cannot be device 0 */
 349
 350         sk = pn_find_sock_by_sa(&sa);
 351         if (sk == NULL) {
 352                 if (can_respond(skb)) {
 353                         send_obj_unreachable(skb);
 354                         send_reset_indications(skb);
 355                 }
 356                 goto out;
 357         }
 358
 359         /* Push data to the socket (or other sockets connected to it). */
 360         return sk_receive_skb(sk, skb, 0);
 361
 362 out:
 363         kfree_skb(skb);
 364         return NET_RX_DROP;
 365 }
 366
 367 static struct packet_type phonet_packet_type = {
 368         .type = __constant_htons(ETH_P_PHONET),
 369         .dev = NULL,
 370         .func = phonet_rcv,
 371 };
 372
 373 /* Transport protocol registration */
 374 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 375 static DEFINE_SPINLOCK(proto_tab_lock);
 376
 377 int __init_or_module phonet_proto_register(int protocol,
 378                                                 struct phonet_protocol *pp)
 379 {
 380         int err = 0;
 381
 382         if (protocol >= PHONET_NPROTO)
 383                 return -EINVAL;
 384
 385         err = proto_register(pp->prot, 1);
 386         if (err)
 387                 return err;
 388
 389         spin_lock(&proto_tab_lock);
 390         if (proto_tab[protocol])
 391                 err = -EBUSY;
 392         else
 393                 proto_tab[protocol] = pp;
 394         spin_unlock(&proto_tab_lock);
 395
 396         return err;
 397 }
 398 EXPORT_SYMBOL(phonet_proto_register);
 399
 400 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 401 {
 402         spin_lock(&proto_tab_lock);
 403         BUG_ON(proto_tab[protocol] != pp);
 404         proto_tab[protocol] = NULL;
 405         spin_unlock(&proto_tab_lock);
 406         proto_unregister(pp->prot);
 407 }
 408 EXPORT_SYMBOL(phonet_proto_unregister);
 409
 410 static struct phonet_protocol *phonet_proto_get(int protocol)
 411 {
 412         struct phonet_protocol *pp;
 413
 414         if (protocol >= PHONET_NPROTO)
 415                 return NULL;
 416
 417         spin_lock(&proto_tab_lock);
 418         pp = proto_tab[protocol];
 419         if (pp && !try_module_get(pp->prot->owner))
 420                 pp = NULL;
 421         spin_unlock(&proto_tab_lock);
 422
 423         return pp;
 424 }
 425
 426 static inline void phonet_proto_put(struct phonet_protocol *pp)
 427 {
 428         module_put(pp->prot->owner);
 429 }
 430
 431 /* Module registration */
 432 static int __init phonet_init(void)
 433 {
 434         int err;
 435
 436         err = sock_register(&phonet_proto_family);
 437         if (err) {
 438                 printk(KERN_ALERT
 439                         "phonet protocol family initialization failed\n");
 440                 return err;
 441         }
 442
 443         phonet_device_init();
 444         dev_add_pack(&phonet_packet_type);
 445         phonet_netlink_register();
 446         phonet_sysctl_init();
 447
 448         err = isi_register();
 449         if (err)
 450                 goto err;
 451         return 0;
 452
 453 err:
 454         phonet_sysctl_exit();
 455         sock_unregister(PF_PHONET);
 456         dev_remove_pack(&phonet_packet_type);
 457         phonet_device_exit();
 458         return err;
 459 }
 460
 461 static void __exit phonet_exit(void)
 462 {
 463         isi_unregister();
 464         phonet_sysctl_exit();
 465         sock_unregister(PF_PHONET);
 466         dev_remove_pack(&phonet_packet_type);
 467         phonet_device_exit();
 468 }
 469
 470 module_init(phonet_init);
 471 module_exit(phonet_exit);
 472 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 473 MODULE_LICENSE("GPL");
 474 MODULE_ALIAS_NETPROTO(PF_PHONET);