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