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, u8 irq)
 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 = (irq ? netif_rx(skb) : netif_rx_ni(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, 1);
 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, 0);
 273         dev_put(dev);
 274         return err;
 275
 276 drop:
 277         kfree_skb(skb);
 278         if (dev)
 279                 dev_put(dev);
 280         return err;
 281 }
 282 EXPORT_SYMBOL(pn_skb_send);
 283
 284 /* Do not send an error message in response to an error message */
 285 static inline int can_respond(struct sk_buff *skb)
 286 {
 287         const struct phonethdr *ph;
 288         const struct phonetmsg *pm;
 289         u8 submsg_id;
 290
 291         if (!pskb_may_pull(skb, 3))
 292                 return 0;
 293
 294         ph = pn_hdr(skb);
 295         if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
 296                 return 0;
 297         if (ph->pn_res == PN_COMMGR) /* indications */
 298                 return 0;
 299
 300         ph = pn_hdr(skb); /* re-acquires the pointer */
 301         pm = pn_msg(skb);
 302         if (pm->pn_msg_id != PN_COMMON_MESSAGE)
 303                 return 1;
 304         submsg_id = (ph->pn_res == PN_PREFIX)
 305                 ? pm->pn_e_submsg_id : pm->pn_submsg_id;
 306         if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
 307                 pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
 308                 return 1;
 309         return 0;
 310 }
 311
 312 static int send_obj_unreachable(struct sk_buff *rskb)
 313 {
 314         const struct phonethdr *oph = pn_hdr(rskb);
 315         const struct phonetmsg *opm = pn_msg(rskb);
 316         struct phonetmsg resp;
 317
 318         memset(&resp, 0, sizeof(resp));
 319         resp.pn_trans_id = opm->pn_trans_id;
 320         resp.pn_msg_id = PN_COMMON_MESSAGE;
 321         if (oph->pn_res == PN_PREFIX) {
 322                 resp.pn_e_res_id = opm->pn_e_res_id;
 323                 resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 324                 resp.pn_e_orig_msg_id = opm->pn_msg_id;
 325                 resp.pn_e_status = 0;
 326         } else {
 327                 resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
 328                 resp.pn_orig_msg_id = opm->pn_msg_id;
 329                 resp.pn_status = 0;
 330         }
 331         return pn_raw_send(&resp, sizeof(resp), rskb->dev,
 332                                 pn_object(oph->pn_sdev, oph->pn_sobj),
 333                                 pn_object(oph->pn_rdev, oph->pn_robj),
 334                                 oph->pn_res);
 335 }
 336
 337 static int send_reset_indications(struct sk_buff *rskb)
 338 {
 339         struct phonethdr *oph = pn_hdr(rskb);
 340         static const u8 data[4] = {
 341                 0x00 /* trans ID */, 0x10 /* subscribe msg */,
 342                 0x00 /* subscription count */, 0x00 /* dummy */
 343         };
 344
 345         return pn_raw_send(data, sizeof(data), rskb->dev,
 346                                 pn_object(oph->pn_sdev, 0x00),
 347                                 pn_object(oph->pn_rdev, oph->pn_robj),
 348                                 PN_COMMGR);
 349 }
 350
 351
 352 /* packet type functions */
 353
 354 /*
 355  * Stuff received packets to associated sockets.
 356  * On error, returns non-zero and releases the skb.
 357  */
 358 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 359                         struct packet_type *pkttype,
 360                         struct net_device *orig_dev)
 361 {
 362         struct net *net = dev_net(dev);
 363         struct phonethdr *ph;
 364         struct sockaddr_pn sa;
 365         u16 len;
 366
 367         skb = skb_share_check(skb, GFP_ATOMIC);
 368         if (!skb)
 369                 return NET_RX_DROP;
 370
 371         /* check we have at least a full Phonet header */
 372         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 373                 goto out;
 374
 375         /* check that the advertised length is correct */
 376         ph = pn_hdr(skb);
 377         len = get_unaligned_be16(&ph->pn_length);
 378         if (len < 2)
 379                 goto out;
 380         len -= 2;
 381         if ((len > skb->len) || pskb_trim(skb, len))
 382                 goto out;
 383         skb_reset_transport_header(skb);
 384
 385         pn_skb_get_dst_sockaddr(skb, &sa);
 386
 387         /* check if this is broadcasted */
 388         if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
 389                 pn_deliver_sock_broadcast(net, skb);
 390                 goto out;
 391         }
 392
 393         /* resource routing */
 394         if (pn_sockaddr_get_object(&sa) == 0) {
 395                 struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
 396                 if (sk)
 397                         return sk_receive_skb(sk, skb, 0);
 398         }
 399
 400         /* check if we are the destination */
 401         if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
 402                 /* Phonet packet input */
 403                 struct sock *sk = pn_find_sock_by_sa(net, &sa);
 404
 405                 if (sk)
 406                         return sk_receive_skb(sk, skb, 0);
 407
 408                 if (can_respond(skb)) {
 409                         send_obj_unreachable(skb);
 410                         send_reset_indications(skb);
 411                 }
 412         } else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 413                 goto out; /* Race between address deletion and loopback */
 414         else {
 415                 /* Phonet packet routing */
 416                 struct net_device *out_dev;
 417
 418                 out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
 419                 if (!out_dev) {
 420                         net_dbg_ratelimited("No Phonet route to %02X\n",
 421                                             pn_sockaddr_get_addr(&sa));
 422                         goto out;
 423                 }
 424
 425                 __skb_push(skb, sizeof(struct phonethdr));
 426                 skb->dev = out_dev;
 427                 if (out_dev == dev) {
 428                         net_dbg_ratelimited("Phonet loop to %02X on %s\n",
 429                                             pn_sockaddr_get_addr(&sa),
 430                                             dev->name);
 431                         goto out_dev;
 432                 }
 433                 /* Some drivers (e.g. TUN) do not allocate HW header space */
 434                 if (skb_cow_head(skb, out_dev->hard_header_len))
 435                         goto out_dev;
 436
 437                 if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
 438                                         skb->len) < 0)
 439                         goto out_dev;
 440                 dev_queue_xmit(skb);
 441                 dev_put(out_dev);
 442                 return NET_RX_SUCCESS;
 443 out_dev:
 444                 dev_put(out_dev);
 445         }
 446
 447 out:
 448         kfree_skb(skb);
 449         return NET_RX_DROP;
 450 }
 451
 452 static struct packet_type phonet_packet_type __read_mostly = {
 453         .type = cpu_to_be16(ETH_P_PHONET),
 454         .func = phonet_rcv,
 455 };
 456
 457 static DEFINE_MUTEX(proto_tab_lock);
 458
 459 int __init_or_module phonet_proto_register(unsigned int protocol,
 460                                 const struct phonet_protocol *pp)
 461 {
 462         int err = 0;
 463
 464         if (protocol >= PHONET_NPROTO)
 465                 return -EINVAL;
 466
 467         err = proto_register(pp->prot, 1);
 468         if (err)
 469                 return err;
 470
 471         mutex_lock(&proto_tab_lock);
 472         if (proto_tab[protocol])
 473                 err = -EBUSY;
 474         else
 475                 rcu_assign_pointer(proto_tab[protocol], pp);
 476         mutex_unlock(&proto_tab_lock);
 477
 478         return err;
 479 }
 480 EXPORT_SYMBOL(phonet_proto_register);
 481
 482 void phonet_proto_unregister(unsigned int protocol,
 483                         const struct phonet_protocol *pp)
 484 {
 485         mutex_lock(&proto_tab_lock);
 486         BUG_ON(proto_tab[protocol] != pp);
 487         RCU_INIT_POINTER(proto_tab[protocol], NULL);
 488         mutex_unlock(&proto_tab_lock);
 489         synchronize_rcu();
 490         proto_unregister(pp->prot);
 491 }
 492 EXPORT_SYMBOL(phonet_proto_unregister);
 493
 494 /* Module registration */
 495 static int __init phonet_init(void)
 496 {
 497         int err;
 498
 499         err = phonet_device_init();
 500         if (err)
 501                 return err;
 502
 503         pn_sock_init();
 504         err = sock_register(&phonet_proto_family);
 505         if (err) {
 506                 printk(KERN_ALERT
 507                         "phonet protocol family initialization failed\n");
 508                 goto err_sock;
 509         }
 510
 511         dev_add_pack(&phonet_packet_type);
 512         phonet_sysctl_init();
 513
 514         err = isi_register();
 515         if (err)
 516                 goto err;
 517         return 0;
 518
 519 err:
 520         phonet_sysctl_exit();
 521         sock_unregister(PF_PHONET);
 522         dev_remove_pack(&phonet_packet_type);
 523 err_sock:
 524         phonet_device_exit();
 525         return err;
 526 }
 527
 528 static void __exit phonet_exit(void)
 529 {
 530         isi_unregister();
 531         phonet_sysctl_exit();
 532         sock_unregister(PF_PHONET);
 533         dev_remove_pack(&phonet_packet_type);
 534         phonet_device_exit();
 535 }
 536
 537 module_init(phonet_init);
 538 module_exit(phonet_exit);
 539 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 540 MODULE_LICENSE("GPL");
 541 MODULE_ALIAS_NETPROTO(PF_PHONET);