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