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   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
  39 static inline void phonet_proto_put(struct phonet_protocol *pp)
  40 {
  41         module_put(pp->prot->owner);
  42 }
  43
  44 /* protocol family functions */
  45
  46 static int pn_socket_create(struct net *net, struct socket *sock, int protocol)
  47 {
  48         struct sock *sk;
  49         struct pn_sock *pn;
  50         struct phonet_protocol *pnp;
  51         int err;
  52
  53         if (net != &init_net)
  54                 return -EAFNOSUPPORT;
  55
  56         if (!capable(CAP_SYS_ADMIN))
  57                 return -EPERM;
  58
  59         if (protocol == 0) {
  60                 /* Default protocol selection */
  61                 switch (sock->type) {
  62                 case SOCK_DGRAM:
  63                         protocol = PN_PROTO_PHONET;
  64                         break;
  65                 case SOCK_SEQPACKET:
  66                         protocol = PN_PROTO_PIPE;
  67                         break;
  68                 default:
  69                         return -EPROTONOSUPPORT;
  70                 }
  71         }
  72
  73         pnp = phonet_proto_get(protocol);
  74         if (pnp == NULL &&
  75             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
  76                 pnp = phonet_proto_get(protocol);
  77
  78         if (pnp == NULL)
  79                 return -EPROTONOSUPPORT;
  80         if (sock->type != pnp->sock_type) {
  81                 err = -EPROTONOSUPPORT;
  82                 goto out;
  83         }
  84
  85         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
  86         if (sk == NULL) {
  87                 err = -ENOMEM;
  88                 goto out;
  89         }
  90
  91         sock_init_data(sock, sk);
  92         sock->state = SS_UNCONNECTED;
  93         sock->ops = pnp->ops;
  94         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
  95         sk->sk_protocol = protocol;
  96         pn = pn_sk(sk);
  97         pn->sobject = 0;
  98         pn->resource = 0;
  99         sk->sk_prot->init(sk);
 100         err = 0;
 101
 102 out:
 103         phonet_proto_put(pnp);
 104         return err;
 105 }
 106
 107 static struct net_proto_family phonet_proto_family = {
 108         .family = PF_PHONET,
 109         .create = pn_socket_create,
 110         .owner = THIS_MODULE,
 111 };
 112
 113 /* Phonet device header operations */
 114 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 115                                 unsigned short type, const void *daddr,
 116                                 const void *saddr, unsigned len)
 117 {
 118         u8 *media = skb_push(skb, 1);
 119
 120         if (type != ETH_P_PHONET)
 121                 return -1;
 122
 123         if (!saddr)
 124                 saddr = dev->dev_addr;
 125         *media = *(const u8 *)saddr;
 126         return 1;
 127 }
 128
 129 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 130 {
 131         const u8 *media = skb_mac_header(skb);
 132         *haddr = *media;
 133         return 1;
 134 }
 135
 136 struct header_ops phonet_header_ops = {
 137         .create = pn_header_create,
 138         .parse = pn_header_parse,
 139 };
 140 EXPORT_SYMBOL(phonet_header_ops);
 141
 142 /*
 143  * Prepends an ISI header and sends a datagram.
 144  */
 145 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 146                         u16 dst, u16 src, u8 res, u8 irq)
 147 {
 148         struct phonethdr *ph;
 149         int err;
 150
 151         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
 152             skb->len + sizeof(struct phonethdr) > dev->mtu) {
 153                 err = -EMSGSIZE;
 154                 goto drop;
 155         }
 156
 157         skb_reset_transport_header(skb);
 158         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 159         skb_push(skb, sizeof(struct phonethdr));
 160         skb_reset_network_header(skb);
 161         ph = pn_hdr(skb);
 162         ph->pn_rdev = pn_dev(dst);
 163         ph->pn_sdev = pn_dev(src);
 164         ph->pn_res = res;
 165         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 166         ph->pn_robj = pn_obj(dst);
 167         ph->pn_sobj = pn_obj(src);
 168
 169         skb->protocol = htons(ETH_P_PHONET);
 170         skb->priority = 0;
 171         skb->dev = dev;
 172
 173         if (pn_addr(src) == pn_addr(dst)) {
 174                 skb_reset_mac_header(skb);
 175                 skb->pkt_type = PACKET_LOOPBACK;
 176                 skb_orphan(skb);
 177                 if (irq)
 178                         netif_rx(skb);
 179                 else
 180                         netif_rx_ni(skb);
 181                 err = 0;
 182         } else {
 183                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 184                                         NULL, NULL, skb->len);
 185                 if (err < 0) {
 186                         err = -EHOSTUNREACH;
 187                         goto drop;
 188                 }
 189                 err = dev_queue_xmit(skb);
 190         }
 191
 192         return err;
 193 drop:
 194         kfree_skb(skb);
 195         return err;
 196 }
 197
 198 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 199                         u16 dst, u16 src, u8 res)
 200 {
 201         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 202         if (skb == NULL)
 203                 return -ENOMEM;
 204
 205         skb_reserve(skb, MAX_PHONET_HEADER);
 206         __skb_put(skb, len);
 207         skb_copy_to_linear_data(skb, data, len);
 208         return pn_send(skb, dev, dst, src, res, 1);
 209 }
 210
 211 /*
 212  * Create a Phonet header for the skb and send it out. Returns
 213  * non-zero error code if failed. The skb is freed then.
 214  */
 215 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 216                 const struct sockaddr_pn *target)
 217 {
 218         struct net_device *dev;
 219         struct pn_sock *pn = pn_sk(sk);
 220         int err;
 221         u16 src;
 222         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
 223
 224         err = -EHOSTUNREACH;
 225         if (sk->sk_bound_dev_if)
 226                 dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
 227         else
 228                 dev = phonet_device_get(sock_net(sk));
 229         if (!dev || !(dev->flags & IFF_UP))
 230                 goto drop;
 231
 232         saddr = phonet_address_get(dev, daddr);
 233         if (saddr == PN_NO_ADDR)
 234                 goto drop;
 235
 236         src = pn->sobject;
 237         if (!pn_addr(src))
 238                 src = pn_object(saddr, pn_obj(src));
 239
 240         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
 241                         src, pn_sockaddr_get_resource(target), 0);
 242         dev_put(dev);
 243         return err;
 244
 245 drop:
 246         kfree_skb(skb);
 247         if (dev)
 248                 dev_put(dev);
 249         return err;
 250 }
 251 EXPORT_SYMBOL(pn_skb_send);
 252
 253 /* Do not send an error message in response to an error message */
 254 static inline int can_respond(struct sk_buff *skb)
 255 {
 256         const struct phonethdr *ph;
 257         const struct phonetmsg *pm;
 258         u8 submsg_id;
 259
 260         if (!pskb_may_pull(skb, 3))
 261                 return 0;
 262
 263         ph = pn_hdr(skb);
 264         if (phonet_address_get(skb->dev, ph->pn_rdev) != ph->pn_rdev)
 265                 return 0; /* we are not the destination */
 266         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 267                 return 0;
 268         if (ph->pn_res == PN_COMMGR) /* indications */
 269                 return 0;
 270
 271         ph = pn_hdr(skb); /* re-acquires the pointer */
 272         pm = pn_msg(skb);
 273         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 274                 return 1;
 275         submsg_id = (ph->pn_res == PN_PREFIX)
 276                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 277         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 278                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 279                 return 1;
 280         return 0;
 281 }
 282
 283 static int send_obj_unreachable(struct sk_buff *rskb)
 284 {
 285         const struct phonethdr *oph = pn_hdr(rskb);
 286         const struct phonetmsg *opm = pn_msg(rskb);
 287         struct phonetmsg resp;
 288
 289         memset(&resp, 0, sizeof(resp));
 290         resp.pn_trans_id = opm->pn_trans_id;
 291         resp.pn_msg_id = PN_COMMON_MESSAGE;
 292         if (oph->pn_res == PN_PREFIX) {
 293                 resp.pn_e_res_id = opm->pn_e_res_id;
 294                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 295                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 296                 resp.pn_e_status = 0;
 297         } else {
 298                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 299                 resp.pn_orig_msg_id = opm->pn_msg_id;
 300                 resp.pn_status = 0;
 301         }
 302         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 303                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 304                                 pn_object(oph->pn_rdev, oph->pn_robj),
 305                                 oph->pn_res);
 306 }
 307
 308 static int send_reset_indications(struct sk_buff *rskb)
 309 {
 310         struct phonethdr *oph = pn_hdr(rskb);
 311         static const u8 data[4] = {
 312                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 313                 0x00 /* subscription count */, 0x00 /* dummy */
 314         };
 315
 316         return pn_raw_send(data, sizeof(data), rskb->dev,
 317                                 pn_object(oph->pn_sdev, 0x00),
 318                                 pn_object(oph->pn_rdev, oph->pn_robj),
 319                                 PN_COMMGR);
 320 }
 321
 322
 323 /* packet type functions */
 324
 325 /*
 326  * Stuff received packets to associated sockets.
 327  * On error, returns non-zero and releases the skb.
 328  */
 329 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 330                         struct packet_type *pkttype,
 331                         struct net_device *orig_dev)
 332 {
 333         struct phonethdr *ph;
 334         struct sock *sk;
 335         struct sockaddr_pn sa;
 336         u16 len;
 337
 338         if (dev_net(dev) != &init_net)
 339                 goto out;
 340
 341         /* check we have at least a full Phonet header */
 342         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 343                 goto out;
 344
 345         /* check that the advertised length is correct */
 346         ph = pn_hdr(skb);
 347         len = get_unaligned_be16(&ph->pn_length);
 348         if (len < 2)
 349                 goto out;
 350         len -= 2;
 351         if ((len > skb->len) || pskb_trim(skb, len))
 352                 goto out;
 353         skb_reset_transport_header(skb);
 354
 355         pn_skb_get_dst_sockaddr(skb, &sa);
 356         if (pn_sockaddr_get_addr(&sa) == 0)
 357                 goto out; /* currently, we cannot be device 0 */
 358
 359         sk = pn_find_sock_by_sa(&sa);
 360         if (sk == NULL) {
 361                 if (can_respond(skb)) {
 362                         send_obj_unreachable(skb);
 363                         send_reset_indications(skb);
 364                 }
 365                 goto out;
 366         }
 367
 368         /* Push data to the socket (or other sockets connected to it). */
 369         return sk_receive_skb(sk, skb, 0);
 370
 371 out:
 372         kfree_skb(skb);
 373         return NET_RX_DROP;
 374 }
 375
 376 static struct packet_type phonet_packet_type = {
 377         .type = __constant_htons(ETH_P_PHONET),
 378         .dev = NULL,
 379         .func = phonet_rcv,
 380 };
 381
 382 /* Transport protocol registration */
 383 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 384 static DEFINE_SPINLOCK(proto_tab_lock);
 385
 386 int __init_or_module phonet_proto_register(int protocol,
 387                                                 struct phonet_protocol *pp)
 388 {
 389         int err = 0;
 390
 391         if (protocol >= PHONET_NPROTO)
 392                 return -EINVAL;
 393
 394         err = proto_register(pp->prot, 1);
 395         if (err)
 396                 return err;
 397
 398         spin_lock(&proto_tab_lock);
 399         if (proto_tab[protocol])
 400                 err = -EBUSY;
 401         else
 402                 proto_tab[protocol] = pp;
 403         spin_unlock(&proto_tab_lock);
 404
 405         return err;
 406 }
 407 EXPORT_SYMBOL(phonet_proto_register);
 408
 409 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 410 {
 411         spin_lock(&proto_tab_lock);
 412         BUG_ON(proto_tab[protocol] != pp);
 413         proto_tab[protocol] = NULL;
 414         spin_unlock(&proto_tab_lock);
 415         proto_unregister(pp->prot);
 416 }
 417 EXPORT_SYMBOL(phonet_proto_unregister);
 418
 419 static struct phonet_protocol *phonet_proto_get(int protocol)
 420 {
 421         struct phonet_protocol *pp;
 422
 423         if (protocol >= PHONET_NPROTO)
 424                 return NULL;
 425
 426         spin_lock(&proto_tab_lock);
 427         pp = proto_tab[protocol];
 428         if (pp && !try_module_get(pp->prot->owner))
 429                 pp = NULL;
 430         spin_unlock(&proto_tab_lock);
 431
 432         return pp;
 433 }
 434
 435 /* Module registration */
 436 static int __init phonet_init(void)
 437 {
 438         int err;
 439
 440         err = sock_register(&phonet_proto_family);
 441         if (err) {
 442                 printk(KERN_ALERT
 443                         "phonet protocol family initialization failed\n");
 444                 return err;
 445         }
 446
 447         phonet_device_init();
 448         dev_add_pack(&phonet_packet_type);
 449         phonet_netlink_register();
 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         phonet_device_exit();
 462         return err;
 463 }
 464
 465 static void __exit phonet_exit(void)
 466 {
 467         isi_unregister();
 468         phonet_sysctl_exit();
 469         sock_unregister(PF_PHONET);
 470         dev_remove_pack(&phonet_packet_type);
 471         phonet_device_exit();
 472 }
 473
 474 module_init(phonet_init);
 475 module_exit(phonet_exit);
 476 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 477 MODULE_LICENSE("GPL");
 478 MODULE_ALIAS_NETPROTO(PF_PHONET);