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_eq(net, &init_net))
  71                 return -EAFNOSUPPORT;
  72         if (!capable(CAP_SYS_ADMIN))
  73                 return -EPERM;
  74
  75         if (protocol == 0) {
  76                 /* Default protocol selection */
  77                 switch (sock->type) {
  78                 case SOCK_DGRAM:
  79                         protocol = PN_PROTO_PHONET;
  80                         break;
  81                 case SOCK_SEQPACKET:
  82                         protocol = PN_PROTO_PIPE;
  83                         break;
  84                 default:
  85                         return -EPROTONOSUPPORT;
  86                 }
  87         }
  88
  89         pnp = phonet_proto_get(protocol);
  90         if (pnp == NULL &&
  91             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
  92                 pnp = phonet_proto_get(protocol);
  93
  94         if (pnp == NULL)
  95                 return -EPROTONOSUPPORT;
  96         if (sock->type != pnp->sock_type) {
  97                 err = -EPROTONOSUPPORT;
  98                 goto out;
  99         }
 100
 101         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
 102         if (sk == NULL) {
 103                 err = -ENOMEM;
 104                 goto out;
 105         }
 106
 107         sock_init_data(sock, sk);
 108         sock->state = SS_UNCONNECTED;
 109         sock->ops = pnp->ops;
 110         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
 111         sk->sk_protocol = protocol;
 112         pn = pn_sk(sk);
 113         pn->sobject = 0;
 114         pn->resource = 0;
 115         sk->sk_prot->init(sk);
 116         err = 0;
 117
 118 out:
 119         phonet_proto_put(pnp);
 120         return err;
 121 }
 122
 123 static struct net_proto_family phonet_proto_family = {
 124         .family = PF_PHONET,
 125         .create = pn_socket_create,
 126         .owner = THIS_MODULE,
 127 };
 128
 129 /* Phonet device header operations */
 130 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 131                                 unsigned short type, const void *daddr,
 132                                 const void *saddr, unsigned len)
 133 {
 134         u8 *media = skb_push(skb, 1);
 135
 136         if (type != ETH_P_PHONET)
 137                 return -1;
 138
 139         if (!saddr)
 140                 saddr = dev->dev_addr;
 141         *media = *(const u8 *)saddr;
 142         return 1;
 143 }
 144
 145 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 146 {
 147         const u8 *media = skb_mac_header(skb);
 148         *haddr = *media;
 149         return 1;
 150 }
 151
 152 struct header_ops phonet_header_ops = {
 153         .create = pn_header_create,
 154         .parse = pn_header_parse,
 155 };
 156 EXPORT_SYMBOL(phonet_header_ops);
 157
 158 /*
 159  * Prepends an ISI header and sends a datagram.
 160  */
 161 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 162                         u16 dst, u16 src, u8 res, u8 irq)
 163 {
 164         struct phonethdr *ph;
 165         int err;
 166
 167         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
 168             skb->len + sizeof(struct phonethdr) > dev->mtu) {
 169                 err = -EMSGSIZE;
 170                 goto drop;
 171         }
 172
 173         /* Broadcast sending is not implemented */
 174         if (pn_addr(dst) == PNADDR_BROADCAST) {
 175                 err = -EOPNOTSUPP;
 176                 goto drop;
 177         }
 178
 179         skb_reset_transport_header(skb);
 180         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 181         skb_push(skb, sizeof(struct phonethdr));
 182         skb_reset_network_header(skb);
 183         ph = pn_hdr(skb);
 184         ph->pn_rdev = pn_dev(dst);
 185         ph->pn_sdev = pn_dev(src);
 186         ph->pn_res = res;
 187         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 188         ph->pn_robj = pn_obj(dst);
 189         ph->pn_sobj = pn_obj(src);
 190
 191         skb->protocol = htons(ETH_P_PHONET);
 192         skb->priority = 0;
 193         skb->dev = dev;
 194
 195         if (pn_addr(src) == pn_addr(dst)) {
 196                 skb_reset_mac_header(skb);
 197                 skb->pkt_type = PACKET_LOOPBACK;
 198                 skb_orphan(skb);
 199                 if (irq)
 200                         netif_rx(skb);
 201                 else
 202                         netif_rx_ni(skb);
 203                 err = 0;
 204         } else {
 205                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 206                                         NULL, NULL, skb->len);
 207                 if (err < 0) {
 208                         err = -EHOSTUNREACH;
 209                         goto drop;
 210                 }
 211                 err = dev_queue_xmit(skb);
 212         }
 213
 214         return err;
 215 drop:
 216         kfree_skb(skb);
 217         return err;
 218 }
 219
 220 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 221                         u16 dst, u16 src, u8 res)
 222 {
 223         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 224         if (skb == NULL)
 225                 return -ENOMEM;
 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_device *dev;
 241         struct pn_sock *pn = pn_sk(sk);
 242         int err;
 243         u16 src;
 244         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
 245
 246         err = -EHOSTUNREACH;
 247         if (sk->sk_bound_dev_if)
 248                 dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
 249         else
 250                 dev = phonet_device_get(sock_net(sk));
 251         if (!dev || !(dev->flags & IFF_UP))
 252                 goto drop;
 253
 254         saddr = phonet_address_get(dev, daddr);
 255         if (saddr == PN_NO_ADDR)
 256                 goto drop;
 257
 258         src = pn->sobject;
 259         if (!pn_addr(src))
 260                 src = pn_object(saddr, pn_obj(src));
 261
 262         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
 263                         src, pn_sockaddr_get_resource(target), 0);
 264         dev_put(dev);
 265         return err;
 266
 267 drop:
 268         kfree_skb(skb);
 269         if (dev)
 270                 dev_put(dev);
 271         return err;
 272 }
 273 EXPORT_SYMBOL(pn_skb_send);
 274
 275 /* Do not send an error message in response to an error message */
 276 static inline int can_respond(struct sk_buff *skb)
 277 {
 278         const struct phonethdr *ph;
 279         const struct phonetmsg *pm;
 280         u8 submsg_id;
 281
 282         if (!pskb_may_pull(skb, 3))
 283                 return 0;
 284
 285         ph = pn_hdr(skb);
 286         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 287                 return 0;
 288         if (ph->pn_res == PN_COMMGR) /* indications */
 289                 return 0;
 290
 291         ph = pn_hdr(skb); /* re-acquires the pointer */
 292         pm = pn_msg(skb);
 293         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 294                 return 1;
 295         submsg_id = (ph->pn_res == PN_PREFIX)
 296                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 297         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 298                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 299                 return 1;
 300         return 0;
 301 }
 302
 303 static int send_obj_unreachable(struct sk_buff *rskb)
 304 {
 305         const struct phonethdr *oph = pn_hdr(rskb);
 306         const struct phonetmsg *opm = pn_msg(rskb);
 307         struct phonetmsg resp;
 308
 309         memset(&resp, 0, sizeof(resp));
 310         resp.pn_trans_id = opm->pn_trans_id;
 311         resp.pn_msg_id = PN_COMMON_MESSAGE;
 312         if (oph->pn_res == PN_PREFIX) {
 313                 resp.pn_e_res_id = opm->pn_e_res_id;
 314                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 315                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 316                 resp.pn_e_status = 0;
 317         } else {
 318                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 319                 resp.pn_orig_msg_id = opm->pn_msg_id;
 320                 resp.pn_status = 0;
 321         }
 322         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 323                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 324                                 pn_object(oph->pn_rdev, oph->pn_robj),
 325                                 oph->pn_res);
 326 }
 327
 328 static int send_reset_indications(struct sk_buff *rskb)
 329 {
 330         struct phonethdr *oph = pn_hdr(rskb);
 331         static const u8 data[4] = {
 332                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 333                 0x00 /* subscription count */, 0x00 /* dummy */
 334         };
 335
 336         return pn_raw_send(data, sizeof(data), rskb->dev,
 337                                 pn_object(oph->pn_sdev, 0x00),
 338                                 pn_object(oph->pn_rdev, oph->pn_robj),
 339                                 PN_COMMGR);
 340 }
 341
 342
 343 /* packet type functions */
 344
 345 /*
 346  * Stuff received packets to associated sockets.
 347  * On error, returns non-zero and releases the skb.
 348  */
 349 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 350                         struct packet_type *pkttype,
 351                         struct net_device *orig_dev)
 352 {
 353         struct net *net = dev_net(dev);
 354         struct phonethdr *ph;
 355         struct sockaddr_pn sa;
 356         u16 len;
 357
 358         if (!net_eq(net, &init_net))
 359                 goto out;
 360         /* check we have at least a full Phonet header */
 361         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 362                 goto out;
 363
 364         /* check that the advertised length is correct */
 365         ph = pn_hdr(skb);
 366         len = get_unaligned_be16(&ph->pn_length);
 367         if (len < 2)
 368                 goto out;
 369         len -= 2;
 370         if ((len > skb->len) || pskb_trim(skb, len))
 371                 goto out;
 372         skb_reset_transport_header(skb);
 373
 374         pn_skb_get_dst_sockaddr(skb, &sa);
 375
 376         /* check if we are the destination */
 377         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 378                 /* Phonet packet input */
 379                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
 380
 381                 if (sk)
 382                         return sk_receive_skb(sk, skb, 0);
 383
 384                 if (can_respond(skb)) {
 385                         send_obj_unreachable(skb);
 386                         send_reset_indications(skb);
 387                 }
 388         }
 389
 390 out:
 391         kfree_skb(skb);
 392         return NET_RX_DROP;
 393 }
 394
 395 static struct packet_type phonet_packet_type __read_mostly = {
 396         .type = cpu_to_be16(ETH_P_PHONET),
 397         .func = phonet_rcv,
 398 };
 399
 400 int __init_or_module phonet_proto_register(int protocol,
 401                                                 struct phonet_protocol *pp)
 402 {
 403         int err = 0;
 404
 405         if (protocol >= PHONET_NPROTO)
 406                 return -EINVAL;
 407
 408         err = proto_register(pp->prot, 1);
 409         if (err)
 410                 return err;
 411
 412         spin_lock(&proto_tab_lock);
 413         if (proto_tab[protocol])
 414                 err = -EBUSY;
 415         else
 416                 proto_tab[protocol] = pp;
 417         spin_unlock(&proto_tab_lock);
 418
 419         return err;
 420 }
 421 EXPORT_SYMBOL(phonet_proto_register);
 422
 423 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 424 {
 425         spin_lock(&proto_tab_lock);
 426         BUG_ON(proto_tab[protocol] != pp);
 427         proto_tab[protocol] = NULL;
 428         spin_unlock(&proto_tab_lock);
 429         proto_unregister(pp->prot);
 430 }
 431 EXPORT_SYMBOL(phonet_proto_unregister);
 432
 433 /* Module registration */
 434 static int __init phonet_init(void)
 435 {
 436         int err;
 437
 438         err = phonet_device_init();
 439         if (err)
 440                 return err;
 441
 442         err = sock_register(&phonet_proto_family);
 443         if (err) {
 444                 printk(KERN_ALERT
 445                         "phonet protocol family initialization failed\n");
 446                 goto err_sock;
 447         }
 448
 449         dev_add_pack(&phonet_packet_type);
 450         phonet_sysctl_init();
 451
 452         err = isi_register();
 453         if (err)
 454                 goto err;
 455         return 0;
 456
 457 err:
 458         phonet_sysctl_exit();
 459         sock_unregister(PF_PHONET);
 460         dev_remove_pack(&phonet_packet_type);
 461 err_sock:
 462         phonet_device_exit();
 463         return err;
 464 }
 465
 466 static void __exit phonet_exit(void)
 467 {
 468         isi_unregister();
 469         phonet_sysctl_exit();
 470         sock_unregister(PF_PHONET);
 471         dev_remove_pack(&phonet_packet_type);
 472         phonet_device_exit();
 473 }
 474
 475 module_init(phonet_init);
 476 module_exit(phonet_exit);
 477 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 478 MODULE_LICENSE("GPL");
 479 MODULE_ALIAS_NETPROTO(PF_PHONET);