net/phonet/af_phonet.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * File: af_phonet.c
   4  *
   5  * Phonet protocols family
   6  *
   7  * Copyright (C) 2008 Nokia Corporation.
   8  *
   9  * Authors: Sakari Ailus <sakari.ailus@nokia.com>
  10  *          Rémi Denis-Courmont
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <asm/unaligned.h>
  17 #include <net/sock.h>
  18
  19 #include <linux/if_phonet.h>
  20 #include <linux/phonet.h>
  21 #include <net/phonet/phonet.h>
  22 #include <net/phonet/pn_dev.h>
  23
  24 /* Transport protocol registration */
  25 static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
  26
  27 static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
  28 {
  29         const struct phonet_protocol *pp;
  30
  31         if (protocol >= PHONET_NPROTO)
  32                 return NULL;
  33
  34         rcu_read_lock();
  35         pp = rcu_dereference(proto_tab[protocol]);
  36         if (pp && !try_module_get(pp->prot->owner))
  37                 pp = NULL;
  38         rcu_read_unlock();
  39
  40         return pp;
  41 }
  42
  43 static inline void phonet_proto_put(const struct phonet_protocol *pp)
  44 {
  45         module_put(pp->prot->owner);
  46 }
  47
  48 /* protocol family functions */
  49
  50 static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
  51                             int kern)
  52 {
  53         struct sock *sk;
  54         struct pn_sock *pn;
  55         const struct phonet_protocol *pnp;
  56         int err;
  57
  58         if (!capable(CAP_SYS_ADMIN))
  59                 return -EPERM;
  60
  61         if (protocol == 0) {
  62                 /* Default protocol selection */
  63                 switch (sock->type) {
  64                 case SOCK_DGRAM:
  65                         protocol = PN_PROTO_PHONET;
  66                         break;
  67                 case SOCK_SEQPACKET:
  68                         protocol = PN_PROTO_PIPE;
  69                         break;
  70                 default:
  71                         return -EPROTONOSUPPORT;
  72                 }
  73         }
  74
  75         pnp = phonet_proto_get(protocol);
  76         if (pnp == NULL &&
  77             request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
  78                 pnp = phonet_proto_get(protocol);
  79
  80         if (pnp == NULL)
  81                 return -EPROTONOSUPPORT;
  82         if (sock->type != pnp->sock_type) {
  83                 err = -EPROTONOSUPPORT;
  84                 goto out;
  85         }
  86
  87         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot, kern);
  88         if (sk == NULL) {
  89                 err = -ENOMEM;
  90                 goto out;
  91         }
  92
  93         sock_init_data(sock, sk);
  94         sock->state = SS_UNCONNECTED;
  95         sock->ops = pnp->ops;
  96         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
  97         sk->sk_protocol = protocol;
  98         pn = pn_sk(sk);
  99         pn->sobject = 0;
 100         pn->dobject = 0;
 101         pn->resource = 0;
 102         sk->sk_prot->init(sk);
 103         err = 0;
 104
 105 out:
 106         phonet_proto_put(pnp);
 107         return err;
 108 }
 109
 110 static const struct net_proto_family phonet_proto_family = {
 111         .family = PF_PHONET,
 112         .create = pn_socket_create,
 113         .owner = THIS_MODULE,
 114 };
 115
 116 /* Phonet device header operations */
 117 static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 118                                 unsigned short type, const void *daddr,
 119                                 const void *saddr, unsigned int len)
 120 {
 121         u8 *media = skb_push(skb, 1);
 122
 123         if (type != ETH_P_PHONET)
 124                 return -1;
 125
 126         if (!saddr)
 127                 saddr = dev->dev_addr;
 128         *media = *(const u8 *)saddr;
 129         return 1;
 130 }
 131
 132 static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 133 {
 134         const u8 *media = skb_mac_header(skb);
 135         *haddr = *media;
 136         return 1;
 137 }
 138
 139 const struct header_ops phonet_header_ops = {
 140         .create = pn_header_create,
 141         .parse = pn_header_parse,
 142 };
 143 EXPORT_SYMBOL(phonet_header_ops);
 144
 145 /*
 146  * Prepends an ISI header and sends a datagram.
 147  */
 148 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 149                         u16 dst, u16 src, u8 res)
 150 {
 151         struct phonethdr *ph;
 152         int err;
 153
 154         if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
 155             skb->len + sizeof(struct phonethdr) > dev->mtu) {
 156                 err = -EMSGSIZE;
 157                 goto drop;
 158         }
 159
 160         /* Broadcast sending is not implemented */
 161         if (pn_addr(dst) == PNADDR_BROADCAST) {
 162                 err = -EOPNOTSUPP;
 163                 goto drop;
 164         }
 165
 166         skb_reset_transport_header(skb);
 167         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 168         skb_push(skb, sizeof(struct phonethdr));
 169         skb_reset_network_header(skb);
 170         ph = pn_hdr(skb);
 171         ph->pn_rdev = pn_dev(dst);
 172         ph->pn_sdev = pn_dev(src);
 173         ph->pn_res = res;
 174         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 175         ph->pn_robj = pn_obj(dst);
 176         ph->pn_sobj = pn_obj(src);
 177
 178         skb->protocol = htons(ETH_P_PHONET);
 179         skb->priority = 0;
 180         skb->dev = dev;
 181
 182         if (skb->pkt_type == PACKET_LOOPBACK) {
 183                 skb_reset_mac_header(skb);
 184                 skb_orphan(skb);
 185                 err = netif_rx(skb) ? -ENOBUFS : 0;
 186         } else {
 187                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 188                                         NULL, NULL, skb->len);
 189                 if (err < 0) {
 190                         err = -EHOSTUNREACH;
 191                         goto drop;
 192                 }
 193                 err = dev_queue_xmit(skb);
 194                 if (unlikely(err > 0))
 195                         err = net_xmit_errno(err);
 196         }
 197
 198         return err;
 199 drop:
 200         kfree_skb(skb);
 201         return err;
 202 }
 203
 204 static int pn_raw_send(const void *data, int len, struct net_device *dev,
 205                         u16 dst, u16 src, u8 res)
 206 {
 207         struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
 208         if (skb == NULL)
 209                 return -ENOMEM;
 210
 211         if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
 212                 skb->pkt_type = PACKET_LOOPBACK;
 213
 214         skb_reserve(skb, MAX_PHONET_HEADER);
 215         __skb_put(skb, len);
 216         skb_copy_to_linear_data(skb, data, len);
 217         return pn_send(skb, dev, dst, src, res);
 218 }
 219
 220 /*
 221  * Create a Phonet header for the skb and send it out. Returns
 222  * non-zero error code if failed. The skb is freed then.
 223  */
 224 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 225                 const struct sockaddr_pn *target)
 226 {
 227         struct net *net = sock_net(sk);
 228         struct net_device *dev;
 229         struct pn_sock *pn = pn_sk(sk);
 230         int err;
 231         u16 src, dst;
 232         u8 daddr, saddr, res;
 233
 234         src = pn->sobject;
 235         if (target != NULL) {
 236                 dst = pn_sockaddr_get_object(target);
 237                 res = pn_sockaddr_get_resource(target);
 238         } else {
 239                 dst = pn->dobject;
 240                 res = pn->resource;
 241         }
 242         daddr = pn_addr(dst);
 243
 244         err = -EHOSTUNREACH;
 245         if (sk->sk_bound_dev_if)
 246                 dev = dev_get_by_index(net, sk->sk_bound_dev_if);
 247         else if (phonet_address_lookup(net, daddr) == 0) {
 248                 dev = phonet_device_get(net);
 249                 skb->pkt_type = PACKET_LOOPBACK;
 250         } else if (dst == 0) {
 251                 /* Resource routing (small race until phonet_rcv()) */
 252                 struct sock *sk = pn_find_sock_by_res(net, res);
 253                 if (sk) {
 254                         sock_put(sk);
 255                         dev = phonet_device_get(net);
 256                         skb->pkt_type = PACKET_LOOPBACK;
 257                 } else
 258                         dev = phonet_route_output(net, daddr);
 259         } else
 260                 dev = phonet_route_output(net, daddr);
 261
 262         if (!dev || !(dev->flags & IFF_UP))
 263                 goto drop;
 264
 265         saddr = phonet_address_get(dev, daddr);
 266         if (saddr == PN_NO_ADDR)
 267                 goto drop;
 268
 269         if (!pn_addr(src))
 270                 src = pn_object(saddr, pn_obj(src));
 271
 272         err = pn_send(skb, dev, dst, src, res);
 273         dev_put(dev);
 274         return err;
 275
 276 drop:
 277         kfree_skb(skb);
 278         dev_put(dev);
 279         return err;
 280 }
 281 EXPORT_SYMBOL(pn_skb_send);
 282
 283 /* Do not send an error message in response to an error message */
 284 static inline int can_respond(struct sk_buff *skb)
 285 {
 286         const struct phonethdr *ph;
 287         const struct phonetmsg *pm;
 288         u8 submsg_id;
 289
 290         if (!pskb_may_pull(skb, 3))
 291                 return 0;
 292
 293         ph = pn_hdr(skb);
 294         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 295                 return 0;
 296         if (ph->pn_res == PN_COMMGR) /* indications */
 297                 return 0;
 298
 299         ph = pn_hdr(skb); /* re-acquires the pointer */
 300         pm = pn_msg(skb);
 301         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 302                 return 1;
 303         submsg_id = (ph->pn_res == PN_PREFIX)
 304                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 305         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 306                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 307                 return 1;
 308         return 0;
 309 }
 310
 311 static int send_obj_unreachable(struct sk_buff *rskb)
 312 {
 313         const struct phonethdr *oph = pn_hdr(rskb);
 314         const struct phonetmsg *opm = pn_msg(rskb);
 315         struct phonetmsg resp;
 316
 317         memset(&resp, 0, sizeof(resp));
 318         resp.pn_trans_id = opm->pn_trans_id;
 319         resp.pn_msg_id = PN_COMMON_MESSAGE;
 320         if (oph->pn_res == PN_PREFIX) {
 321                 resp.pn_e_res_id = opm->pn_e_res_id;
 322                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 323                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 324                 resp.pn_e_status = 0;
 325         } else {
 326                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 327                 resp.pn_orig_msg_id = opm->pn_msg_id;
 328                 resp.pn_status = 0;
 329         }
 330         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 331                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 332                                 pn_object(oph->pn_rdev, oph->pn_robj),
 333                                 oph->pn_res);
 334 }
 335
 336 static int send_reset_indications(struct sk_buff *rskb)
 337 {
 338         struct phonethdr *oph = pn_hdr(rskb);
 339         static const u8 data[4] = {
 340                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 341                 0x00 /* subscription count */, 0x00 /* dummy */
 342         };
 343
 344         return pn_raw_send(data, sizeof(data), rskb->dev,
 345                                 pn_object(oph->pn_sdev, 0x00),
 346                                 pn_object(oph->pn_rdev, oph->pn_robj),
 347                                 PN_COMMGR);
 348 }
 349
 350
 351 /* packet type functions */
 352
 353 /*
 354  * Stuff received packets to associated sockets.
 355  * On error, returns non-zero and releases the skb.
 356  */
 357 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 358                         struct packet_type *pkttype,
 359                         struct net_device *orig_dev)
 360 {
 361         struct net *net = dev_net(dev);
 362         struct phonethdr *ph;
 363         struct sockaddr_pn sa;
 364         u16 len;
 365
 366         skb = skb_share_check(skb, GFP_ATOMIC);
 367         if (!skb)
 368                 return NET_RX_DROP;
 369
 370         /* check we have at least a full Phonet header */
 371         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 372                 goto out;
 373
 374         /* check that the advertised length is correct */
 375         ph = pn_hdr(skb);
 376         len = get_unaligned_be16(&ph->pn_length);
 377         if (len < 2)
 378                 goto out;
 379         len -= 2;
 380         if ((len > skb->len) || pskb_trim(skb, len))
 381                 goto out;
 382         skb_reset_transport_header(skb);
 383
 384         pn_skb_get_dst_sockaddr(skb, &sa);
 385
 386         /* check if this is broadcasted */
 387         if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
 388                 pn_deliver_sock_broadcast(net, skb);
 389                 goto out;
 390         }
 391
 392         /* resource routing */
 393         if (pn_sockaddr_get_object(&sa) == 0) {
 394                 struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
 395                 if (sk)
 396                         return sk_receive_skb(sk, skb, 0);
 397         }
 398
 399         /* check if we are the destination */
 400         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 401                 /* Phonet packet input */
 402                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
 403
 404                 if (sk)
 405                         return sk_receive_skb(sk, skb, 0);
 406
 407                 if (can_respond(skb)) {
 408                         send_obj_unreachable(skb);
 409                         send_reset_indications(skb);
 410                 }
 411         } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 412                 goto out; /* Race between address deletion and loopback */
 413         else {
 414                 /* Phonet packet routing */
 415                 struct net_device *out_dev;
 416
 417                 out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
 418                 if (!out_dev) {
 419                         net_dbg_ratelimited("No Phonet route to %02X\n",
 420                                             pn_sockaddr_get_addr(&sa));
 421                         goto out;
 422                 }
 423
 424                 __skb_push(skb, sizeof(struct phonethdr));
 425                 skb->dev = out_dev;
 426                 if (out_dev == dev) {
 427                         net_dbg_ratelimited("Phonet loop to %02X on %s\n",
 428                                             pn_sockaddr_get_addr(&sa),
 429                                             dev->name);
 430                         goto out_dev;
 431                 }
 432                 /* Some drivers (e.g. TUN) do not allocate HW header space */
 433                 if (skb_cow_head(skb, out_dev->hard_header_len))
 434                         goto out_dev;
 435
 436                 if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
 437                                         skb->len) < 0)
 438                         goto out_dev;
 439                 dev_queue_xmit(skb);
 440                 dev_put(out_dev);
 441                 return NET_RX_SUCCESS;
 442 out_dev:
 443                 dev_put(out_dev);
 444         }
 445
 446 out:
 447         kfree_skb(skb);
 448         return NET_RX_DROP;
 449 }
 450
 451 static struct packet_type phonet_packet_type __read_mostly = {
 452         .type = cpu_to_be16(ETH_P_PHONET),
 453         .func = phonet_rcv,
 454 };
 455
 456 static DEFINE_MUTEX(proto_tab_lock);
 457
 458 int __init_or_module phonet_proto_register(unsigned int protocol,
 459                                 const struct phonet_protocol *pp)
 460 {
 461         int err = 0;
 462
 463         if (protocol >= PHONET_NPROTO)
 464                 return -EINVAL;
 465
 466         err = proto_register(pp->prot, 1);
 467         if (err)
 468                 return err;
 469
 470         mutex_lock(&proto_tab_lock);
 471         if (proto_tab[protocol])
 472                 err = -EBUSY;
 473         else
 474                 rcu_assign_pointer(proto_tab[protocol], pp);
 475         mutex_unlock(&proto_tab_lock);
 476
 477         return err;
 478 }
 479 EXPORT_SYMBOL(phonet_proto_register);
 480
 481 void phonet_proto_unregister(unsigned int protocol,
 482                         const struct phonet_protocol *pp)
 483 {
 484         mutex_lock(&proto_tab_lock);
 485         BUG_ON(proto_tab[protocol] != pp);
 486         RCU_INIT_POINTER(proto_tab[protocol], NULL);
 487         mutex_unlock(&proto_tab_lock);
 488         synchronize_rcu();
 489         proto_unregister(pp->prot);
 490 }
 491 EXPORT_SYMBOL(phonet_proto_unregister);
 492
 493 /* Module registration */
 494 static int __init phonet_init(void)
 495 {
 496         int err;
 497
 498         err = phonet_device_init();
 499         if (err)
 500                 return err;
 501
 502         pn_sock_init();
 503         err = sock_register(&phonet_proto_family);
 504         if (err) {
 505                 printk(KERN_ALERT
 506                         "phonet protocol family initialization failed\n");
 507                 goto err_sock;
 508         }
 509
 510         dev_add_pack(&phonet_packet_type);
 511         phonet_sysctl_init();
 512
 513         err = isi_register();
 514         if (err)
 515                 goto err;
 516         return 0;
 517
 518 err:
 519         phonet_sysctl_exit();
 520         sock_unregister(PF_PHONET);
 521         dev_remove_pack(&phonet_packet_type);
 522 err_sock:
 523         phonet_device_exit();
 524         return err;
 525 }
 526
 527 static void __exit phonet_exit(void)
 528 {
 529         isi_unregister();
 530         phonet_sysctl_exit();
 531         sock_unregister(PF_PHONET);
 532         dev_remove_pack(&phonet_packet_type);
 533         phonet_device_exit();
 534 }
 535
 536 module_init(phonet_init);
 537 module_exit(phonet_exit);
 538 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 539 MODULE_LICENSE("GPL");
 540 MODULE_ALIAS_NETPROTO(PF_PHONET);