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