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