linux/net/phonet/af_phonet.c
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   1/*
   2 * File: af_phonet.c
   3 *
   4 * Phonet protocols family
   5 *
   6 * Copyright (C) 2008 Nokia Corporation.
   7 *
   8 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
   9 *          RĂ©mi Denis-Courmont
  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 <linux/slab.h>
  29#include <asm/unaligned.h>
  30#include <net/sock.h>
  31
  32#include <linux/if_phonet.h>
  33#include <linux/phonet.h>
  34#include <net/phonet/phonet.h>
  35#include <net/phonet/pn_dev.h>
  36
  37/* Transport protocol registration */
  38static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
  39
  40static struct phonet_protocol *phonet_proto_get(unsigned int protocol)
  41{
  42        struct phonet_protocol *pp;
  43
  44        if (protocol >= PHONET_NPROTO)
  45                return NULL;
  46
  47        rcu_read_lock();
  48        pp = rcu_dereference(proto_tab[protocol]);
  49        if (pp && !try_module_get(pp->prot->owner))
  50                pp = NULL;
  51        rcu_read_unlock();
  52
  53        return pp;
  54}
  55
  56static inline void phonet_proto_put(struct phonet_protocol *pp)
  57{
  58        module_put(pp->prot->owner);
  59}
  60
  61/* protocol family functions */
  62
  63static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
  64                            int kern)
  65{
  66        struct sock *sk;
  67        struct pn_sock *pn;
  68        struct phonet_protocol *pnp;
  69        int err;
  70
  71        if (!capable(CAP_SYS_ADMIN))
  72                return -EPERM;
  73
  74        if (protocol == 0) {
  75                /* Default protocol selection */
  76                switch (sock->type) {
  77                case SOCK_DGRAM:
  78                        protocol = PN_PROTO_PHONET;
  79                        break;
  80                case SOCK_SEQPACKET:
  81                        protocol = PN_PROTO_PIPE;
  82                        break;
  83                default:
  84                        return -EPROTONOSUPPORT;
  85                }
  86        }
  87
  88        pnp = phonet_proto_get(protocol);
  89        if (pnp == NULL &&
  90            request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
  91                pnp = phonet_proto_get(protocol);
  92
  93        if (pnp == NULL)
  94                return -EPROTONOSUPPORT;
  95        if (sock->type != pnp->sock_type) {
  96                err = -EPROTONOSUPPORT;
  97                goto out;
  98        }
  99
 100        sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
 101        if (sk == NULL) {
 102                err = -ENOMEM;
 103                goto out;
 104        }
 105
 106        sock_init_data(sock, sk);
 107        sock->state = SS_UNCONNECTED;
 108        sock->ops = pnp->ops;
 109        sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
 110        sk->sk_protocol = protocol;
 111        pn = pn_sk(sk);
 112        pn->sobject = 0;
 113        pn->dobject = 0;
 114        pn->resource = 0;
 115        sk->sk_prot->init(sk);
 116        err = 0;
 117
 118out:
 119        phonet_proto_put(pnp);
 120        return err;
 121}
 122
 123static const 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 */
 130static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 131                                unsigned short type, const void *daddr,
 132                                const void *saddr, unsigned int 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
 145static 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
 152struct header_ops phonet_header_ops = {
 153        .create = pn_header_create,
 154        .parse = pn_header_parse,
 155};
 156EXPORT_SYMBOL(phonet_header_ops);
 157
 158/*
 159 * Prepends an ISI header and sends a datagram.
 160 */
 161static 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 (skb->pkt_type == PACKET_LOOPBACK) {
 196                skb_reset_mac_header(skb);
 197                skb_orphan(skb);
 198                err = (irq ? netif_rx(skb) : netif_rx_ni(skb)) ? -ENOBUFS : 0;
 199        } else {
 200                err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 201                                        NULL, NULL, skb->len);
 202                if (err < 0) {
 203                        err = -EHOSTUNREACH;
 204                        goto drop;
 205                }
 206                err = dev_queue_xmit(skb);
 207                if (unlikely(err > 0))
 208                        err = net_xmit_errno(err);
 209        }
 210
 211        return err;
 212drop:
 213        kfree_skb(skb);
 214        return err;
 215}
 216
 217static int pn_raw_send(const void *data, int len, struct net_device *dev,
 218                        u16 dst, u16 src, u8 res)
 219{
 220        struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 221        if (skb == NULL)
 222                return -ENOMEM;
 223
 224        if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
 225                skb->pkt_type = PACKET_LOOPBACK;
 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 */
 237int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 238                const struct sockaddr_pn *target)
 239{
 240        struct net *net = sock_net(sk);
 241        struct net_device *dev;
 242        struct pn_sock *pn = pn_sk(sk);
 243        int err;
 244        u16 src, dst;
 245        u8 daddr, saddr, res;
 246
 247        src = pn->sobject;
 248        if (target != NULL) {
 249                dst = pn_sockaddr_get_object(target);
 250                res = pn_sockaddr_get_resource(target);
 251        } else {
 252                dst = pn->dobject;
 253                res = pn->resource;
 254        }
 255        daddr = pn_addr(dst);
 256
 257        err = -EHOSTUNREACH;
 258        if (sk->sk_bound_dev_if)
 259                dev = dev_get_by_index(net, sk->sk_bound_dev_if);
 260        else if (phonet_address_lookup(net, daddr) == 0) {
 261                dev = phonet_device_get(net);
 262                skb->pkt_type = PACKET_LOOPBACK;
 263        } else if (dst == 0) {
 264                /* Resource routing (small race until phonet_rcv()) */
 265                struct sock *sk = pn_find_sock_by_res(net, res);
 266                if (sk) {
 267                        sock_put(sk);
 268                        dev = phonet_device_get(net);
 269                        skb->pkt_type = PACKET_LOOPBACK;
 270                } else
 271                        dev = phonet_route_output(net, daddr);
 272        } else
 273                dev = phonet_route_output(net, daddr);
 274
 275        if (!dev || !(dev->flags & IFF_UP))
 276                goto drop;
 277
 278        saddr = phonet_address_get(dev, daddr);
 279        if (saddr == PN_NO_ADDR)
 280                goto drop;
 281
 282        if (!pn_addr(src))
 283                src = pn_object(saddr, pn_obj(src));
 284
 285        err = pn_send(skb, dev, dst, src, res, 0);
 286        dev_put(dev);
 287        return err;
 288
 289drop:
 290        kfree_skb(skb);
 291        if (dev)
 292                dev_put(dev);
 293        return err;
 294}
 295EXPORT_SYMBOL(pn_skb_send);
 296
 297/* Do not send an error message in response to an error message */
 298static inline int can_respond(struct sk_buff *skb)
 299{
 300        const struct phonethdr *ph;
 301        const struct phonetmsg *pm;
 302        u8 submsg_id;
 303
 304        if (!pskb_may_pull(skb, 3))
 305                return 0;
 306
 307        ph = pn_hdr(skb);
 308        if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 309                return 0;
 310        if (ph->pn_res == PN_COMMGR) /* indications */
 311                return 0;
 312
 313        ph = pn_hdr(skb); /* re-acquires the pointer */
 314        pm = pn_msg(skb);
 315        if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 316                return 1;
 317        submsg_id = (ph->pn_res == PN_PREFIX)
 318                ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 319        if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 320                pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 321                return 1;
 322        return 0;
 323}
 324
 325static int send_obj_unreachable(struct sk_buff *rskb)
 326{
 327        const struct phonethdr *oph = pn_hdr(rskb);
 328        const struct phonetmsg *opm = pn_msg(rskb);
 329        struct phonetmsg resp;
 330
 331        memset(&resp, 0, sizeof(resp));
 332        resp.pn_trans_id = opm->pn_trans_id;
 333        resp.pn_msg_id = PN_COMMON_MESSAGE;
 334        if (oph->pn_res == PN_PREFIX) {
 335                resp.pn_e_res_id = opm->pn_e_res_id;
 336                resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 337                resp.pn_e_orig_msg_id = opm->pn_msg_id;
 338                resp.pn_e_status = 0;
 339        } else {
 340                resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 341                resp.pn_orig_msg_id = opm->pn_msg_id;
 342                resp.pn_status = 0;
 343        }
 344        return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 345                                pn_object(oph->pn_sdev, oph->pn_sobj),
 346                                pn_object(oph->pn_rdev, oph->pn_robj),
 347                                oph->pn_res);
 348}
 349
 350static int send_reset_indications(struct sk_buff *rskb)
 351{
 352        struct phonethdr *oph = pn_hdr(rskb);
 353        static const u8 data[4] = {
 354                0x00 /* trans ID */, 0x10 /* subscribe msg */,
 355                0x00 /* subscription count */, 0x00 /* dummy */
 356        };
 357
 358        return pn_raw_send(data, sizeof(data), rskb->dev,
 359                                pn_object(oph->pn_sdev, 0x00),
 360                                pn_object(oph->pn_rdev, oph->pn_robj),
 361                                PN_COMMGR);
 362}
 363
 364
 365/* packet type functions */
 366
 367/*
 368 * Stuff received packets to associated sockets.
 369 * On error, returns non-zero and releases the skb.
 370 */
 371static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 372                        struct packet_type *pkttype,
 373                        struct net_device *orig_dev)
 374{
 375        struct net *net = dev_net(dev);
 376        struct phonethdr *ph;
 377        struct sockaddr_pn sa;
 378        u16 len;
 379
 380        /* check we have at least a full Phonet header */
 381        if (!pskb_pull(skb, sizeof(struct phonethdr)))
 382                goto out;
 383
 384        /* check that the advertised length is correct */
 385        ph = pn_hdr(skb);
 386        len = get_unaligned_be16(&ph->pn_length);
 387        if (len < 2)
 388                goto out;
 389        len -= 2;
 390        if ((len > skb->len) || pskb_trim(skb, len))
 391                goto out;
 392        skb_reset_transport_header(skb);
 393
 394        pn_skb_get_dst_sockaddr(skb, &sa);
 395
 396        /* check if this is broadcasted */
 397        if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
 398                pn_deliver_sock_broadcast(net, skb);
 399                goto out;
 400        }
 401
 402        /* resource routing */
 403        if (pn_sockaddr_get_object(&sa) == 0) {
 404                struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
 405                if (sk)
 406                        return sk_receive_skb(sk, skb, 0);
 407        }
 408
 409        /* check if we are the destination */
 410        if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 411                /* Phonet packet input */
 412                struct sock *sk = pn_find_sock_by_sa(net, &sa);
 413
 414                if (sk)
 415                        return sk_receive_skb(sk, skb, 0);
 416
 417                if (can_respond(skb)) {
 418                        send_obj_unreachable(skb);
 419                        send_reset_indications(skb);
 420                }
 421        } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 422                goto out; /* Race between address deletion and loopback */
 423        else {
 424                /* Phonet packet routing */
 425                struct net_device *out_dev;
 426
 427                out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
 428                if (!out_dev) {
 429                        LIMIT_NETDEBUG(KERN_WARNING"No Phonet route to %02X\n",
 430                                        pn_sockaddr_get_addr(&sa));
 431                        goto out;
 432                }
 433
 434                __skb_push(skb, sizeof(struct phonethdr));
 435                skb->dev = out_dev;
 436                if (out_dev == dev) {
 437                        LIMIT_NETDEBUG(KERN_ERR"Phonet loop to %02X on %s\n",
 438                                        pn_sockaddr_get_addr(&sa), dev->name);
 439                        goto out_dev;
 440                }
 441                /* Some drivers (e.g. TUN) do not allocate HW header space */
 442                if (skb_cow_head(skb, out_dev->hard_header_len))
 443                        goto out_dev;
 444
 445                if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
 446                                        skb->len) < 0)
 447                        goto out_dev;
 448                dev_queue_xmit(skb);
 449                dev_put(out_dev);
 450                return NET_RX_SUCCESS;
 451out_dev:
 452                dev_put(out_dev);
 453        }
 454
 455out:
 456        kfree_skb(skb);
 457        return NET_RX_DROP;
 458}
 459
 460static struct packet_type phonet_packet_type __read_mostly = {
 461        .type = cpu_to_be16(ETH_P_PHONET),
 462        .func = phonet_rcv,
 463};
 464
 465static DEFINE_MUTEX(proto_tab_lock);
 466
 467int __init_or_module phonet_proto_register(unsigned int protocol,
 468                                                struct phonet_protocol *pp)
 469{
 470        int err = 0;
 471
 472        if (protocol >= PHONET_NPROTO)
 473                return -EINVAL;
 474
 475        err = proto_register(pp->prot, 1);
 476        if (err)
 477                return err;
 478
 479        mutex_lock(&proto_tab_lock);
 480        if (proto_tab[protocol])
 481                err = -EBUSY;
 482        else
 483                rcu_assign_pointer(proto_tab[protocol], pp);
 484        mutex_unlock(&proto_tab_lock);
 485
 486        return err;
 487}
 488EXPORT_SYMBOL(phonet_proto_register);
 489
 490void phonet_proto_unregister(unsigned int protocol, struct phonet_protocol *pp)
 491{
 492        mutex_lock(&proto_tab_lock);
 493        BUG_ON(proto_tab[protocol] != pp);
 494        RCU_INIT_POINTER(proto_tab[protocol], NULL);
 495        mutex_unlock(&proto_tab_lock);
 496        synchronize_rcu();
 497        proto_unregister(pp->prot);
 498}
 499EXPORT_SYMBOL(phonet_proto_unregister);
 500
 501/* Module registration */
 502static int __init phonet_init(void)
 503{
 504        int err;
 505
 506        err = phonet_device_init();
 507        if (err)
 508                return err;
 509
 510        pn_sock_init();
 511        err = sock_register(&phonet_proto_family);
 512        if (err) {
 513                printk(KERN_ALERT
 514                        "phonet protocol family initialization failed\n");
 515                goto err_sock;
 516        }
 517
 518        dev_add_pack(&phonet_packet_type);
 519        phonet_sysctl_init();
 520
 521        err = isi_register();
 522        if (err)
 523                goto err;
 524        return 0;
 525
 526err:
 527        phonet_sysctl_exit();
 528        sock_unregister(PF_PHONET);
 529        dev_remove_pack(&phonet_packet_type);
 530err_sock:
 531        phonet_device_exit();
 532        return err;
 533}
 534
 535static void __exit phonet_exit(void)
 536{
 537        isi_unregister();
 538        phonet_sysctl_exit();
 539        sock_unregister(PF_PHONET);
 540        dev_remove_pack(&phonet_packet_type);
 541        phonet_device_exit();
 542}
 543
 544module_init(phonet_init);
 545module_exit(phonet_exit);
 546MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 547MODULE_LICENSE("GPL");
 548MODULE_ALIAS_NETPROTO(PF_PHONET);
 549
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