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 (!capable(CAP_SYS_ADMIN))
  71                 return -EPERM;
  72
  73         if (protocol == 0) {
  74                 /* Default protocol selection */
  75                 switch (sock->type) {
  76                 case SOCK_DGRAM:
  77                         protocol = PN_PROTO_PHONET;
  78                         break;
  79                 case SOCK_SEQPACKET:
  80                         protocol = PN_PROTO_PIPE;
  81                         break;
  82                 default:
  83                         return -EPROTONOSUPPORT;
  84                 }
  85         }
  86
  87         pnp = phonet_proto_get(protocol);
  88         if (pnp == NULL &&
  89             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
  90                 pnp = phonet_proto_get(protocol);
  91
  92         if (pnp == NULL)
  93                 return -EPROTONOSUPPORT;
  94         if (sock->type != pnp->sock_type) {
  95                 err = -EPROTONOSUPPORT;
  96                 goto out;
  97         }
  98
  99         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
 100         if (sk == NULL) {
 101                 err = -ENOMEM;
 102                 goto out;
 103         }
 104
 105         sock_init_data(sock, sk);
 106         sock->state = SS_UNCONNECTED;
 107         sock->ops = pnp->ops;
 108         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
 109         sk->sk_protocol = protocol;
 110         pn = pn_sk(sk);
 111         pn->sobject = 0;
 112         pn->resource = 0;
 113         sk->sk_prot->init(sk);
 114         err = 0;
 115
 116 out:
 117         phonet_proto_put(pnp);
 118         return err;
 119 }
 120
 121 static struct net_proto_family phonet_proto_family = {
 122         .family = PF_PHONET,
 123         .create = pn_socket_create,
 124         .owner = THIS_MODULE,
 125 };
 126
 127 /* Phonet device header operations */
 128 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 129                                 unsigned short type, const void *daddr,
 130                                 const void *saddr, unsigned len)
 131 {
 132         u8 *media = skb_push(skb, 1);
 133
 134         if (type != ETH_P_PHONET)
 135                 return -1;
 136
 137         if (!saddr)
 138                 saddr = dev->dev_addr;
 139         *media = *(const u8 *)saddr;
 140         return 1;
 141 }
 142
 143 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 144 {
 145         const u8 *media = skb_mac_header(skb);
 146         *haddr = *media;
 147         return 1;
 148 }
 149
 150 struct header_ops phonet_header_ops = {
 151         .create = pn_header_create,
 152         .parse = pn_header_parse,
 153 };
 154 EXPORT_SYMBOL(phonet_header_ops);
 155
 156 /*
 157  * Prepends an ISI header and sends a datagram.
 158  */
 159 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 160                         u16 dst, u16 src, u8 res, u8 irq)
 161 {
 162         struct phonethdr *ph;
 163         int err;
 164
 165         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
 166             skb->len + sizeof(struct phonethdr) > dev->mtu) {
 167                 err = -EMSGSIZE;
 168                 goto drop;
 169         }
 170
 171         skb_reset_transport_header(skb);
 172         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 173         skb_push(skb, sizeof(struct phonethdr));
 174         skb_reset_network_header(skb);
 175         ph = pn_hdr(skb);
 176         ph->pn_rdev = pn_dev(dst);
 177         ph->pn_sdev = pn_dev(src);
 178         ph->pn_res = res;
 179         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 180         ph->pn_robj = pn_obj(dst);
 181         ph->pn_sobj = pn_obj(src);
 182
 183         skb->protocol = htons(ETH_P_PHONET);
 184         skb->priority = 0;
 185         skb->dev = dev;
 186
 187         if (pn_addr(src) == pn_addr(dst)) {
 188                 skb_reset_mac_header(skb);
 189                 skb->pkt_type = PACKET_LOOPBACK;
 190                 skb_orphan(skb);
 191                 if (irq)
 192                         netif_rx(skb);
 193                 else
 194                         netif_rx_ni(skb);
 195                 err = 0;
 196         } else {
 197                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 198                                         NULL, NULL, skb->len);
 199                 if (err < 0) {
 200                         err = -EHOSTUNREACH;
 201                         goto drop;
 202                 }
 203                 err = dev_queue_xmit(skb);
 204         }
 205
 206         return err;
 207 drop:
 208         kfree_skb(skb);
 209         return err;
 210 }
 211
 212 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 213                         u16 dst, u16 src, u8 res)
 214 {
 215         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 216         if (skb == NULL)
 217                 return -ENOMEM;
 218
 219         skb_reserve(skb, MAX_PHONET_HEADER);
 220         __skb_put(skb, len);
 221         skb_copy_to_linear_data(skb, data, len);
 222         return pn_send(skb, dev, dst, src, res, 1);
 223 }
 224
 225 /*
 226  * Create a Phonet header for the skb and send it out. Returns
 227  * non-zero error code if failed. The skb is freed then.
 228  */
 229 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 230                 const struct sockaddr_pn *target)
 231 {
 232         struct net_device *dev;
 233         struct pn_sock *pn = pn_sk(sk);
 234         int err;
 235         u16 src;
 236         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
 237
 238         err = -EHOSTUNREACH;
 239         if (sk->sk_bound_dev_if)
 240                 dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
 241         else
 242                 dev = phonet_device_get(sock_net(sk));
 243         if (!dev || !(dev->flags & IFF_UP))
 244                 goto drop;
 245
 246         saddr = phonet_address_get(dev, daddr);
 247         if (saddr == PN_NO_ADDR)
 248                 goto drop;
 249
 250         src = pn->sobject;
 251         if (!pn_addr(src))
 252                 src = pn_object(saddr, pn_obj(src));
 253
 254         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
 255                         src, pn_sockaddr_get_resource(target), 0);
 256         dev_put(dev);
 257         return err;
 258
 259 drop:
 260         kfree_skb(skb);
 261         if (dev)
 262                 dev_put(dev);
 263         return err;
 264 }
 265 EXPORT_SYMBOL(pn_skb_send);
 266
 267 /* Do not send an error message in response to an error message */
 268 static inline int can_respond(struct sk_buff *skb)
 269 {
 270         const struct phonethdr *ph;
 271         const struct phonetmsg *pm;
 272         u8 submsg_id;
 273
 274         if (!pskb_may_pull(skb, 3))
 275                 return 0;
 276
 277         ph = pn_hdr(skb);
 278         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 279                 return 0;
 280         if (ph->pn_res == PN_COMMGR) /* indications */
 281                 return 0;
 282
 283         ph = pn_hdr(skb); /* re-acquires the pointer */
 284         pm = pn_msg(skb);
 285         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 286                 return 1;
 287         submsg_id = (ph->pn_res == PN_PREFIX)
 288                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 289         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 290                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 291                 return 1;
 292         return 0;
 293 }
 294
 295 static int send_obj_unreachable(struct sk_buff *rskb)
 296 {
 297         const struct phonethdr *oph = pn_hdr(rskb);
 298         const struct phonetmsg *opm = pn_msg(rskb);
 299         struct phonetmsg resp;
 300
 301         memset(&resp, 0, sizeof(resp));
 302         resp.pn_trans_id = opm->pn_trans_id;
 303         resp.pn_msg_id = PN_COMMON_MESSAGE;
 304         if (oph->pn_res == PN_PREFIX) {
 305                 resp.pn_e_res_id = opm->pn_e_res_id;
 306                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 307                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 308                 resp.pn_e_status = 0;
 309         } else {
 310                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 311                 resp.pn_orig_msg_id = opm->pn_msg_id;
 312                 resp.pn_status = 0;
 313         }
 314         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 315                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 316                                 pn_object(oph->pn_rdev, oph->pn_robj),
 317                                 oph->pn_res);
 318 }
 319
 320 static int send_reset_indications(struct sk_buff *rskb)
 321 {
 322         struct phonethdr *oph = pn_hdr(rskb);
 323         static const u8 data[4] = {
 324                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 325                 0x00 /* subscription count */, 0x00 /* dummy */
 326         };
 327
 328         return pn_raw_send(data, sizeof(data), rskb->dev,
 329                                 pn_object(oph->pn_sdev, 0x00),
 330                                 pn_object(oph->pn_rdev, oph->pn_robj),
 331                                 PN_COMMGR);
 332 }
 333
 334
 335 /* packet type functions */
 336
 337 /*
 338  * Stuff received packets to associated sockets.
 339  * On error, returns non-zero and releases the skb.
 340  */
 341 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 342                         struct packet_type *pkttype,
 343                         struct net_device *orig_dev)
 344 {
 345         struct net *net = dev_net(dev);
 346         struct phonethdr *ph;
 347         struct sockaddr_pn sa;
 348         u16 len;
 349
 350         /* check we have at least a full Phonet header */
 351         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 352                 goto out;
 353
 354         /* check that the advertised length is correct */
 355         ph = pn_hdr(skb);
 356         len = get_unaligned_be16(&ph->pn_length);
 357         if (len < 2)
 358                 goto out;
 359         len -= 2;
 360         if ((len > skb->len) || pskb_trim(skb, len))
 361                 goto out;
 362         skb_reset_transport_header(skb);
 363
 364         pn_skb_get_dst_sockaddr(skb, &sa);
 365
 366         /* check if we are the destination */
 367         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 368                 /* Phonet packet input */
 369                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
 370
 371                 if (sk)
 372                         return sk_receive_skb(sk, skb, 0);
 373
 374                 if (can_respond(skb)) {
 375                         send_obj_unreachable(skb);
 376                         send_reset_indications(skb);
 377                 }
 378         }
 379
 380 out:
 381         kfree_skb(skb);
 382         return NET_RX_DROP;
 383 }
 384
 385 static struct packet_type phonet_packet_type __read_mostly = {
 386         .type = cpu_to_be16(ETH_P_PHONET),
 387         .func = phonet_rcv,
 388 };
 389
 390 int __init_or_module phonet_proto_register(int protocol,
 391                                                 struct phonet_protocol *pp)
 392 {
 393         int err = 0;
 394
 395         if (protocol >= PHONET_NPROTO)
 396                 return -EINVAL;
 397
 398         err = proto_register(pp->prot, 1);
 399         if (err)
 400                 return err;
 401
 402         spin_lock(&proto_tab_lock);
 403         if (proto_tab[protocol])
 404                 err = -EBUSY;
 405         else
 406                 proto_tab[protocol] = pp;
 407         spin_unlock(&proto_tab_lock);
 408
 409         return err;
 410 }
 411 EXPORT_SYMBOL(phonet_proto_register);
 412
 413 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 414 {
 415         spin_lock(&proto_tab_lock);
 416         BUG_ON(proto_tab[protocol] != pp);
 417         proto_tab[protocol] = NULL;
 418         spin_unlock(&proto_tab_lock);
 419         proto_unregister(pp->prot);
 420 }
 421 EXPORT_SYMBOL(phonet_proto_unregister);
 422
 423 /* Module registration */
 424 static int __init phonet_init(void)
 425 {
 426         int err;
 427
 428         err = phonet_device_init();
 429         if (err)
 430                 return err;
 431
 432         err = sock_register(&phonet_proto_family);
 433         if (err) {
 434                 printk(KERN_ALERT
 435                         "phonet protocol family initialization failed\n");
 436                 goto err_sock;
 437         }
 438
 439         dev_add_pack(&phonet_packet_type);
 440         phonet_sysctl_init();
 441
 442         err = isi_register();
 443         if (err)
 444                 goto err;
 445         return 0;
 446
 447 err:
 448         phonet_sysctl_exit();
 449         sock_unregister(PF_PHONET);
 450         dev_remove_pack(&phonet_packet_type);
 451 err_sock:
 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(PF_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");
 469 MODULE_ALIAS_NETPROTO(PF_PHONET);