net/rxrpc/local_object.c

   1 /* Local endpoint object management
   2  *
   3  * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/slab.h>
  18 #include <linux/udp.h>
  19 #include <linux/ip.h>
  20 #include <linux/hashtable.h>
  21 #include <net/sock.h>
  22 #include <net/udp.h>
  23 #include <net/af_rxrpc.h>
  24 #include "ar-internal.h"
  25
  26 static void rxrpc_local_processor(struct work_struct *);
  27 static void rxrpc_local_rcu(struct rcu_head *);
  28
  29 /*
  30  * Compare a local to an address.  Return -ve, 0 or +ve to indicate less than,
  31  * same or greater than.
  32  *
  33  * We explicitly don't compare the RxRPC service ID as we want to reject
  34  * conflicting uses by differing services.  Further, we don't want to share
  35  * addresses with different options (IPv6), so we don't compare those bits
  36  * either.
  37  */
  38 static long rxrpc_local_cmp_key(const struct rxrpc_local *local,
  39                                 const struct sockaddr_rxrpc *srx)
  40 {
  41         long diff;
  42
  43         diff = ((local->srx.transport_type - srx->transport_type) ?:
  44                 (local->srx.transport_len - srx->transport_len) ?:
  45                 (local->srx.transport.family - srx->transport.family));
  46         if (diff != 0)
  47                 return diff;
  48
  49         switch (srx->transport.family) {
  50         case AF_INET:
  51                 /* If the choice of UDP port is left up to the transport, then
  52                  * the endpoint record doesn't match.
  53                  */
  54                 return ((u16 __force)local->srx.transport.sin.sin_port -
  55                         (u16 __force)srx->transport.sin.sin_port) ?:
  56                         memcmp(&local->srx.transport.sin.sin_addr,
  57                                &srx->transport.sin.sin_addr,
  58                                sizeof(struct in_addr));
  59 #ifdef CONFIG_AF_RXRPC_IPV6
  60         case AF_INET6:
  61                 /* If the choice of UDP6 port is left up to the transport, then
  62                  * the endpoint record doesn't match.
  63                  */
  64                 return ((u16 __force)local->srx.transport.sin6.sin6_port -
  65                         (u16 __force)srx->transport.sin6.sin6_port) ?:
  66                         memcmp(&local->srx.transport.sin6.sin6_addr,
  67                                &srx->transport.sin6.sin6_addr,
  68                                sizeof(struct in6_addr));
  69 #endif
  70         default:
  71                 BUG();
  72         }
  73 }
  74
  75 /*
  76  * Allocate a new local endpoint.
  77  */
  78 static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet,
  79                                              const struct sockaddr_rxrpc *srx)
  80 {
  81         struct rxrpc_local *local;
  82
  83         local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
  84         if (local) {
  85                 atomic_set(&local->usage, 1);
  86                 local->rxnet = rxnet;
  87                 INIT_LIST_HEAD(&local->link);
  88                 INIT_WORK(&local->processor, rxrpc_local_processor);
  89                 init_rwsem(&local->defrag_sem);
  90                 skb_queue_head_init(&local->reject_queue);
  91                 skb_queue_head_init(&local->event_queue);
  92                 local->client_conns = RB_ROOT;
  93                 spin_lock_init(&local->client_conns_lock);
  94                 spin_lock_init(&local->lock);
  95                 rwlock_init(&local->services_lock);
  96                 local->debug_id = atomic_inc_return(&rxrpc_debug_id);
  97                 memcpy(&local->srx, srx, sizeof(*srx));
  98                 local->srx.srx_service = 0;
  99                 trace_rxrpc_local(local, rxrpc_local_new, 1, NULL);
 100         }
 101
 102         _leave(" = %p", local);
 103         return local;
 104 }
 105
 106 /*
 107  * create the local socket
 108  * - must be called with rxrpc_local_mutex locked
 109  */
 110 static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
 111 {
 112         struct sock *usk;
 113         int ret, opt;
 114
 115         _enter("%p{%d,%d}",
 116                local, local->srx.transport_type, local->srx.transport.family);
 117
 118         /* create a socket to represent the local endpoint */
 119         ret = sock_create_kern(net, local->srx.transport.family,
 120                                local->srx.transport_type, 0, &local->socket);
 121         if (ret < 0) {
 122                 _leave(" = %d [socket]", ret);
 123                 return ret;
 124         }
 125
 126         /* set the socket up */
 127         usk = local->socket->sk;
 128         inet_sk(usk)->mc_loop = 0;
 129
 130         /* Enable CHECKSUM_UNNECESSARY to CHECKSUM_COMPLETE conversion */
 131         inet_inc_convert_csum(usk);
 132
 133         rcu_assign_sk_user_data(usk, local);
 134
 135         udp_sk(usk)->encap_type = UDP_ENCAP_RXRPC;
 136         udp_sk(usk)->encap_rcv = rxrpc_input_packet;
 137         udp_sk(usk)->encap_destroy = NULL;
 138         udp_sk(usk)->gro_receive = NULL;
 139         udp_sk(usk)->gro_complete = NULL;
 140
 141         udp_encap_enable();
 142 #if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
 143         if (local->srx.transport.family == AF_INET6)
 144                 udpv6_encap_enable();
 145 #endif
 146         usk->sk_error_report = rxrpc_error_report;
 147
 148         /* if a local address was supplied then bind it */
 149         if (local->srx.transport_len > sizeof(sa_family_t)) {
 150                 _debug("bind");
 151                 ret = kernel_bind(local->socket,
 152                                   (struct sockaddr *)&local->srx.transport,
 153                                   local->srx.transport_len);
 154                 if (ret < 0) {
 155                         _debug("bind failed %d", ret);
 156                         goto error;
 157                 }
 158         }
 159
 160         switch (local->srx.transport.family) {
 161         case AF_INET6:
 162                 /* we want to receive ICMPv6 errors */
 163                 opt = 1;
 164                 ret = kernel_setsockopt(local->socket, SOL_IPV6, IPV6_RECVERR,
 165                                         (char *) &opt, sizeof(opt));
 166                 if (ret < 0) {
 167                         _debug("setsockopt failed");
 168                         goto error;
 169                 }
 170
 171                 /* we want to set the don't fragment bit */
 172                 opt = IPV6_PMTUDISC_DO;
 173                 ret = kernel_setsockopt(local->socket, SOL_IPV6, IPV6_MTU_DISCOVER,
 174                                         (char *) &opt, sizeof(opt));
 175                 if (ret < 0) {
 176                         _debug("setsockopt failed");
 177                         goto error;
 178                 }
 179
 180                 /* Fall through and set IPv4 options too otherwise we don't get
 181                  * errors from IPv4 packets sent through the IPv6 socket.
 182                  */
 183
 184         case AF_INET:
 185                 /* we want to receive ICMP errors */
 186                 opt = 1;
 187                 ret = kernel_setsockopt(local->socket, SOL_IP, IP_RECVERR,
 188                                         (char *) &opt, sizeof(opt));
 189                 if (ret < 0) {
 190                         _debug("setsockopt failed");
 191                         goto error;
 192                 }
 193
 194                 /* we want to set the don't fragment bit */
 195                 opt = IP_PMTUDISC_DO;
 196                 ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
 197                                         (char *) &opt, sizeof(opt));
 198                 if (ret < 0) {
 199                         _debug("setsockopt failed");
 200                         goto error;
 201                 }
 202
 203                 /* We want receive timestamps. */
 204                 opt = 1;
 205                 ret = kernel_setsockopt(local->socket, SOL_SOCKET, SO_TIMESTAMPNS,
 206                                         (char *)&opt, sizeof(opt));
 207                 if (ret < 0) {
 208                         _debug("setsockopt failed");
 209                         goto error;
 210                 }
 211                 break;
 212
 213         default:
 214                 BUG();
 215         }
 216
 217         _leave(" = 0");
 218         return 0;
 219
 220 error:
 221         kernel_sock_shutdown(local->socket, SHUT_RDWR);
 222         local->socket->sk->sk_user_data = NULL;
 223         sock_release(local->socket);
 224         local->socket = NULL;
 225
 226         _leave(" = %d", ret);
 227         return ret;
 228 }
 229
 230 /*
 231  * Look up or create a new local endpoint using the specified local address.
 232  */
 233 struct rxrpc_local *rxrpc_lookup_local(struct net *net,
 234                                        const struct sockaddr_rxrpc *srx)
 235 {
 236         struct rxrpc_local *local;
 237         struct rxrpc_net *rxnet = rxrpc_net(net);
 238         struct list_head *cursor;
 239         const char *age;
 240         long diff;
 241         int ret;
 242
 243         _enter("{%d,%d,%pISp}",
 244                srx->transport_type, srx->transport.family, &srx->transport);
 245
 246         mutex_lock(&rxnet->local_mutex);
 247
 248         for (cursor = rxnet->local_endpoints.next;
 249              cursor != &rxnet->local_endpoints;
 250              cursor = cursor->next) {
 251                 local = list_entry(cursor, struct rxrpc_local, link);
 252
 253                 diff = rxrpc_local_cmp_key(local, srx);
 254                 if (diff < 0)
 255                         continue;
 256                 if (diff > 0)
 257                         break;
 258
 259                 /* Services aren't allowed to share transport sockets, so
 260                  * reject that here.  It is possible that the object is dying -
 261                  * but it may also still have the local transport address that
 262                  * we want bound.
 263                  */
 264                 if (srx->srx_service) {
 265                         local = NULL;
 266                         goto addr_in_use;
 267                 }
 268
 269                 /* Found a match.  We replace a dying object.  Attempting to
 270                  * bind the transport socket may still fail if we're attempting
 271                  * to use a local address that the dying object is still using.
 272                  */
 273                 if (!rxrpc_get_local_maybe(local)) {
 274                         cursor = cursor->next;
 275                         list_del_init(&local->link);
 276                         break;
 277                 }
 278
 279                 age = "old";
 280                 goto found;
 281         }
 282
 283         local = rxrpc_alloc_local(rxnet, srx);
 284         if (!local)
 285                 goto nomem;
 286
 287         ret = rxrpc_open_socket(local, net);
 288         if (ret < 0)
 289                 goto sock_error;
 290
 291         list_add_tail(&local->link, cursor);
 292         age = "new";
 293
 294 found:
 295         mutex_unlock(&rxnet->local_mutex);
 296
 297         _net("LOCAL %s %d {%pISp}",
 298              age, local->debug_id, &local->srx.transport);
 299
 300         _leave(" = %p", local);
 301         return local;
 302
 303 nomem:
 304         ret = -ENOMEM;
 305 sock_error:
 306         mutex_unlock(&rxnet->local_mutex);
 307         kfree(local);
 308         _leave(" = %d", ret);
 309         return ERR_PTR(ret);
 310
 311 addr_in_use:
 312         mutex_unlock(&rxnet->local_mutex);
 313         _leave(" = -EADDRINUSE");
 314         return ERR_PTR(-EADDRINUSE);
 315 }
 316
 317 /*
 318  * Get a ref on a local endpoint.
 319  */
 320 struct rxrpc_local *rxrpc_get_local(struct rxrpc_local *local)
 321 {
 322         const void *here = __builtin_return_address(0);
 323         int n;
 324
 325         n = atomic_inc_return(&local->usage);
 326         trace_rxrpc_local(local, rxrpc_local_got, n, here);
 327         return local;
 328 }
 329
 330 /*
 331  * Get a ref on a local endpoint unless its usage has already reached 0.
 332  */
 333 struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local)
 334 {
 335         const void *here = __builtin_return_address(0);
 336
 337         if (local) {
 338                 int n = atomic_fetch_add_unless(&local->usage, 1, 0);
 339                 if (n > 0)
 340                         trace_rxrpc_local(local, rxrpc_local_got, n + 1, here);
 341                 else
 342                         local = NULL;
 343         }
 344         return local;
 345 }
 346
 347 /*
 348  * Queue a local endpoint.
 349  */
 350 void rxrpc_queue_local(struct rxrpc_local *local)
 351 {
 352         const void *here = __builtin_return_address(0);
 353
 354         if (rxrpc_queue_work(&local->processor))
 355                 trace_rxrpc_local(local, rxrpc_local_queued,
 356                                   atomic_read(&local->usage), here);
 357 }
 358
 359 /*
 360  * A local endpoint reached its end of life.
 361  */
 362 static void __rxrpc_put_local(struct rxrpc_local *local)
 363 {
 364         _enter("%d", local->debug_id);
 365         rxrpc_queue_work(&local->processor);
 366 }
 367
 368 /*
 369  * Drop a ref on a local endpoint.
 370  */
 371 void rxrpc_put_local(struct rxrpc_local *local)
 372 {
 373         const void *here = __builtin_return_address(0);
 374         int n;
 375
 376         if (local) {
 377                 n = atomic_dec_return(&local->usage);
 378                 trace_rxrpc_local(local, rxrpc_local_put, n, here);
 379
 380                 if (n == 0)
 381                         __rxrpc_put_local(local);
 382         }
 383 }
 384
 385 /*
 386  * Destroy a local endpoint's socket and then hand the record to RCU to dispose
 387  * of.
 388  *
 389  * Closing the socket cannot be done from bottom half context or RCU callback
 390  * context because it might sleep.
 391  */
 392 static void rxrpc_local_destroyer(struct rxrpc_local *local)
 393 {
 394         struct socket *socket = local->socket;
 395         struct rxrpc_net *rxnet = local->rxnet;
 396
 397         _enter("%d", local->debug_id);
 398
 399         /* We can get a race between an incoming call packet queueing the
 400          * processor again and the work processor starting the destruction
 401          * process which will shut down the UDP socket.
 402          */
 403         if (local->dead) {
 404                 _leave(" [already dead]");
 405                 return;
 406         }
 407         local->dead = true;
 408
 409         mutex_lock(&rxnet->local_mutex);
 410         list_del_init(&local->link);
 411         mutex_unlock(&rxnet->local_mutex);
 412
 413         ASSERT(RB_EMPTY_ROOT(&local->client_conns));
 414         ASSERT(!local->service);
 415
 416         if (socket) {
 417                 local->socket = NULL;
 418                 kernel_sock_shutdown(socket, SHUT_RDWR);
 419                 socket->sk->sk_user_data = NULL;
 420                 sock_release(socket);
 421         }
 422
 423         /* At this point, there should be no more packets coming in to the
 424          * local endpoint.
 425          */
 426         rxrpc_purge_queue(&local->reject_queue);
 427         rxrpc_purge_queue(&local->event_queue);
 428
 429         _debug("rcu local %d", local->debug_id);
 430         call_rcu(&local->rcu, rxrpc_local_rcu);
 431 }
 432
 433 /*
 434  * Process events on an endpoint
 435  */
 436 static void rxrpc_local_processor(struct work_struct *work)
 437 {
 438         struct rxrpc_local *local =
 439                 container_of(work, struct rxrpc_local, processor);
 440         bool again;
 441
 442         trace_rxrpc_local(local, rxrpc_local_processing,
 443                           atomic_read(&local->usage), NULL);
 444
 445         do {
 446                 again = false;
 447                 if (atomic_read(&local->usage) == 0)
 448                         return rxrpc_local_destroyer(local);
 449
 450                 if (!skb_queue_empty(&local->reject_queue)) {
 451                         rxrpc_reject_packets(local);
 452                         again = true;
 453                 }
 454
 455                 if (!skb_queue_empty(&local->event_queue)) {
 456                         rxrpc_process_local_events(local);
 457                         again = true;
 458                 }
 459         } while (again);
 460 }
 461
 462 /*
 463  * Destroy a local endpoint after the RCU grace period expires.
 464  */
 465 static void rxrpc_local_rcu(struct rcu_head *rcu)
 466 {
 467         struct rxrpc_local *local = container_of(rcu, struct rxrpc_local, rcu);
 468
 469         _enter("%d", local->debug_id);
 470
 471         ASSERT(!work_pending(&local->processor));
 472
 473         _net("DESTROY LOCAL %d", local->debug_id);
 474         kfree(local);
 475         _leave("");
 476 }
 477
 478 /*
 479  * Verify the local endpoint list is empty by this point.
 480  */
 481 void rxrpc_destroy_all_locals(struct rxrpc_net *rxnet)
 482 {
 483         struct rxrpc_local *local;
 484
 485         _enter("");
 486
 487         flush_workqueue(rxrpc_workqueue);
 488
 489         if (!list_empty(&rxnet->local_endpoints)) {
 490                 mutex_lock(&rxnet->local_mutex);
 491                 list_for_each_entry(local, &rxnet->local_endpoints, link) {
 492                         pr_err("AF_RXRPC: Leaked local %p {%d}\n",
 493                                local, atomic_read(&local->usage));
 494                 }
 495                 mutex_unlock(&rxnet->local_mutex);
 496                 BUG();
 497         }
 498 }