root/net/rxrpc/local_object.c

DEFINITIONS

1. rxrpc_local_cmp_key
2. rxrpc_alloc_local
3. rxrpc_open_socket
4. rxrpc_lookup_local
5. rxrpc_get_local
6. rxrpc_get_local_maybe
7. rxrpc_queue_local
8. rxrpc_put_local
9. rxrpc_use_local
10. rxrpc_unuse_local
11. rxrpc_local_destroyer
12. rxrpc_local_processor
13. rxrpc_local_rcu
14. rxrpc_destroy_all_locals

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Local endpoint object management
   3  *
   4  * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7 
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9 
  10 #include <linux/module.h>
  11 #include <linux/net.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/slab.h>
  14 #include <linux/udp.h>
  15 #include <linux/ip.h>
  16 #include <linux/hashtable.h>
  17 #include <net/sock.h>
  18 #include <net/udp.h>
  19 #include <net/af_rxrpc.h>
  20 #include "ar-internal.h"
  21 
  22 static void rxrpc_local_processor(struct work_struct *);
  23 static void rxrpc_local_rcu(struct rcu_head *);
  24 
  25 /*
  26  * Compare a local to an address.  Return -ve, 0 or +ve to indicate less than,
  27  * same or greater than.
  28  *
  29  * We explicitly don't compare the RxRPC service ID as we want to reject
  30  * conflicting uses by differing services.  Further, we don't want to share
  31  * addresses with different options (IPv6), so we don't compare those bits
  32  * either.
  33  */
  34 static long rxrpc_local_cmp_key(const struct rxrpc_local *local,
  35                                 const struct sockaddr_rxrpc *srx)
  36 {
  37         long diff;
  38 
  39         diff = ((local->srx.transport_type - srx->transport_type) ?:
  40                 (local->srx.transport_len - srx->transport_len) ?:
  41                 (local->srx.transport.family - srx->transport.family));
  42         if (diff != 0)
  43                 return diff;
  44 
  45         switch (srx->transport.family) {
  46         case AF_INET:
  47                 /* If the choice of UDP port is left up to the transport, then
  48                  * the endpoint record doesn't match.
  49                  */
  50                 return ((u16 __force)local->srx.transport.sin.sin_port -
  51                         (u16 __force)srx->transport.sin.sin_port) ?:
  52                         memcmp(&local->srx.transport.sin.sin_addr,
  53                                &srx->transport.sin.sin_addr,
  54                                sizeof(struct in_addr));
  55 #ifdef CONFIG_AF_RXRPC_IPV6
  56         case AF_INET6:
  57                 /* If the choice of UDP6 port is left up to the transport, then
  58                  * the endpoint record doesn't match.
  59                  */
  60                 return ((u16 __force)local->srx.transport.sin6.sin6_port -
  61                         (u16 __force)srx->transport.sin6.sin6_port) ?:
  62                         memcmp(&local->srx.transport.sin6.sin6_addr,
  63                                &srx->transport.sin6.sin6_addr,
  64                                sizeof(struct in6_addr));
  65 #endif
  66         default:
  67                 BUG();
  68         }
  69 }
  70 
  71 /*
  72  * Allocate a new local endpoint.
  73  */
  74 static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet,
  75                                              const struct sockaddr_rxrpc *srx)
  76 {
  77         struct rxrpc_local *local;
  78 
  79         local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
  80         if (local) {
  81                 atomic_set(&local->usage, 1);
  82                 atomic_set(&local->active_users, 1);
  83                 local->rxnet = rxnet;
  84                 INIT_LIST_HEAD(&local->link);
  85                 INIT_WORK(&local->processor, rxrpc_local_processor);
  86                 init_rwsem(&local->defrag_sem);
  87                 skb_queue_head_init(&local->reject_queue);
  88                 skb_queue_head_init(&local->event_queue);
  89                 local->client_conns = RB_ROOT;
  90                 spin_lock_init(&local->client_conns_lock);
  91                 spin_lock_init(&local->lock);
  92                 rwlock_init(&local->services_lock);
  93                 local->debug_id = atomic_inc_return(&rxrpc_debug_id);
  94                 memcpy(&local->srx, srx, sizeof(*srx));
  95                 local->srx.srx_service = 0;
  96                 trace_rxrpc_local(local->debug_id, rxrpc_local_new, 1, NULL);
  97         }
  98 
  99         _leave(" = %p", local);
 100         return local;
 101 }
 102 
 103 /*
 104  * create the local socket
 105  * - must be called with rxrpc_local_mutex locked
 106  */
 107 static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
 108 {
 109         struct sock *usk;
 110         int ret, opt;
 111 
 112         _enter("%p{%d,%d}",
 113                local, local->srx.transport_type, local->srx.transport.family);
 114 
 115         /* create a socket to represent the local endpoint */
 116         ret = sock_create_kern(net, local->srx.transport.family,
 117                                local->srx.transport_type, 0, &local->socket);
 118         if (ret < 0) {
 119                 _leave(" = %d [socket]", ret);
 120                 return ret;
 121         }
 122 
 123         /* set the socket up */
 124         usk = local->socket->sk;
 125         inet_sk(usk)->mc_loop = 0;
 126 
 127         /* Enable CHECKSUM_UNNECESSARY to CHECKSUM_COMPLETE conversion */
 128         inet_inc_convert_csum(usk);
 129 
 130         rcu_assign_sk_user_data(usk, local);
 131 
 132         udp_sk(usk)->encap_type = UDP_ENCAP_RXRPC;
 133         udp_sk(usk)->encap_rcv = rxrpc_input_packet;
 134         udp_sk(usk)->encap_destroy = NULL;
 135         udp_sk(usk)->gro_receive = NULL;
 136         udp_sk(usk)->gro_complete = NULL;
 137 
 138         udp_encap_enable();
 139 #if IS_ENABLED(CONFIG_AF_RXRPC_IPV6)
 140         if (local->srx.transport.family == AF_INET6)
 141                 udpv6_encap_enable();
 142 #endif
 143         usk->sk_error_report = rxrpc_error_report;
 144 
 145         /* if a local address was supplied then bind it */
 146         if (local->srx.transport_len > sizeof(sa_family_t)) {
 147                 _debug("bind");
 148                 ret = kernel_bind(local->socket,
 149                                   (struct sockaddr *)&local->srx.transport,
 150                                   local->srx.transport_len);
 151                 if (ret < 0) {
 152                         _debug("bind failed %d", ret);
 153                         goto error;
 154                 }
 155         }
 156 
 157         switch (local->srx.transport.family) {
 158         case AF_INET6:
 159                 /* we want to receive ICMPv6 errors */
 160                 opt = 1;
 161                 ret = kernel_setsockopt(local->socket, SOL_IPV6, IPV6_RECVERR,
 162                                         (char *) &opt, sizeof(opt));
 163                 if (ret < 0) {
 164                         _debug("setsockopt failed");
 165                         goto error;
 166                 }
 167 
 168                 /* Fall through and set IPv4 options too otherwise we don't get
 169                  * errors from IPv4 packets sent through the IPv6 socket.
 170                  */
 171                 /* Fall through */
 172         case AF_INET:
 173                 /* we want to receive ICMP errors */
 174                 opt = 1;
 175                 ret = kernel_setsockopt(local->socket, SOL_IP, IP_RECVERR,
 176                                         (char *) &opt, sizeof(opt));
 177                 if (ret < 0) {
 178                         _debug("setsockopt failed");
 179                         goto error;
 180                 }
 181 
 182                 /* we want to set the don't fragment bit */
 183                 opt = IP_PMTUDISC_DO;
 184                 ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
 185                                         (char *) &opt, sizeof(opt));
 186                 if (ret < 0) {
 187                         _debug("setsockopt failed");
 188                         goto error;
 189                 }
 190 
 191                 /* We want receive timestamps. */
 192                 opt = 1;
 193                 ret = kernel_setsockopt(local->socket, SOL_SOCKET, SO_TIMESTAMPNS_OLD,
 194                                         (char *)&opt, sizeof(opt));
 195                 if (ret < 0) {
 196                         _debug("setsockopt failed");
 197                         goto error;
 198                 }
 199                 break;
 200 
 201         default:
 202                 BUG();
 203         }
 204 
 205         _leave(" = 0");
 206         return 0;
 207 
 208 error:
 209         kernel_sock_shutdown(local->socket, SHUT_RDWR);
 210         local->socket->sk->sk_user_data = NULL;
 211         sock_release(local->socket);
 212         local->socket = NULL;
 213 
 214         _leave(" = %d", ret);
 215         return ret;
 216 }
 217 
 218 /*
 219  * Look up or create a new local endpoint using the specified local address.
 220  */
 221 struct rxrpc_local *rxrpc_lookup_local(struct net *net,
 222                                        const struct sockaddr_rxrpc *srx)
 223 {
 224         struct rxrpc_local *local;
 225         struct rxrpc_net *rxnet = rxrpc_net(net);
 226         struct list_head *cursor;
 227         const char *age;
 228         long diff;
 229         int ret;
 230 
 231         _enter("{%d,%d,%pISp}",
 232                srx->transport_type, srx->transport.family, &srx->transport);
 233 
 234         mutex_lock(&rxnet->local_mutex);
 235 
 236         for (cursor = rxnet->local_endpoints.next;
 237              cursor != &rxnet->local_endpoints;
 238              cursor = cursor->next) {
 239                 local = list_entry(cursor, struct rxrpc_local, link);
 240 
 241                 diff = rxrpc_local_cmp_key(local, srx);
 242                 if (diff < 0)
 243                         continue;
 244                 if (diff > 0)
 245                         break;
 246 
 247                 /* Services aren't allowed to share transport sockets, so
 248                  * reject that here.  It is possible that the object is dying -
 249                  * but it may also still have the local transport address that
 250                  * we want bound.
 251                  */
 252                 if (srx->srx_service) {
 253                         local = NULL;
 254                         goto addr_in_use;
 255                 }
 256 
 257                 /* Found a match.  We replace a dying object.  Attempting to
 258                  * bind the transport socket may still fail if we're attempting
 259                  * to use a local address that the dying object is still using.
 260                  */
 261                 if (!rxrpc_use_local(local))
 262                         break;
 263 
 264                 age = "old";
 265                 goto found;
 266         }
 267 
 268         local = rxrpc_alloc_local(rxnet, srx);
 269         if (!local)
 270                 goto nomem;
 271 
 272         ret = rxrpc_open_socket(local, net);
 273         if (ret < 0)
 274                 goto sock_error;
 275 
 276         if (cursor != &rxnet->local_endpoints)
 277                 list_replace_init(cursor, &local->link);
 278         else
 279                 list_add_tail(&local->link, cursor);
 280         age = "new";
 281 
 282 found:
 283         mutex_unlock(&rxnet->local_mutex);
 284 
 285         _net("LOCAL %s %d {%pISp}",
 286              age, local->debug_id, &local->srx.transport);
 287 
 288         _leave(" = %p", local);
 289         return local;
 290 
 291 nomem:
 292         ret = -ENOMEM;
 293 sock_error:
 294         mutex_unlock(&rxnet->local_mutex);
 295         if (local)
 296                 call_rcu(&local->rcu, rxrpc_local_rcu);
 297         _leave(" = %d", ret);
 298         return ERR_PTR(ret);
 299 
 300 addr_in_use:
 301         mutex_unlock(&rxnet->local_mutex);
 302         _leave(" = -EADDRINUSE");
 303         return ERR_PTR(-EADDRINUSE);
 304 }
 305 
 306 /*
 307  * Get a ref on a local endpoint.
 308  */
 309 struct rxrpc_local *rxrpc_get_local(struct rxrpc_local *local)
 310 {
 311         const void *here = __builtin_return_address(0);
 312         int n;
 313 
 314         n = atomic_inc_return(&local->usage);
 315         trace_rxrpc_local(local->debug_id, rxrpc_local_got, n, here);
 316         return local;
 317 }
 318 
 319 /*
 320  * Get a ref on a local endpoint unless its usage has already reached 0.
 321  */
 322 struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local)
 323 {
 324         const void *here = __builtin_return_address(0);
 325 
 326         if (local) {
 327                 int n = atomic_fetch_add_unless(&local->usage, 1, 0);
 328                 if (n > 0)
 329                         trace_rxrpc_local(local->debug_id, rxrpc_local_got,
 330                                           n + 1, here);
 331                 else
 332                         local = NULL;
 333         }
 334         return local;
 335 }
 336 
 337 /*
 338  * Queue a local endpoint and pass the caller's reference to the work item.
 339  */
 340 void rxrpc_queue_local(struct rxrpc_local *local)
 341 {
 342         const void *here = __builtin_return_address(0);
 343         unsigned int debug_id = local->debug_id;
 344         int n = atomic_read(&local->usage);
 345 
 346         if (rxrpc_queue_work(&local->processor))
 347                 trace_rxrpc_local(debug_id, rxrpc_local_queued, n, here);
 348         else
 349                 rxrpc_put_local(local);
 350 }
 351 
 352 /*
 353  * Drop a ref on a local endpoint.
 354  */
 355 void rxrpc_put_local(struct rxrpc_local *local)
 356 {
 357         const void *here = __builtin_return_address(0);
 358         unsigned int debug_id;
 359         int n;
 360 
 361         if (local) {
 362                 debug_id = local->debug_id;
 363 
 364                 n = atomic_dec_return(&local->usage);
 365                 trace_rxrpc_local(debug_id, rxrpc_local_put, n, here);
 366 
 367                 if (n == 0)
 368                         call_rcu(&local->rcu, rxrpc_local_rcu);
 369         }
 370 }
 371 
 372 /*
 373  * Start using a local endpoint.
 374  */
 375 struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local)
 376 {
 377         local = rxrpc_get_local_maybe(local);
 378         if (!local)
 379                 return NULL;
 380 
 381         if (!__rxrpc_use_local(local)) {
 382                 rxrpc_put_local(local);
 383                 return NULL;
 384         }
 385 
 386         return local;
 387 }
 388 
 389 /*
 390  * Cease using a local endpoint.  Once the number of active users reaches 0, we
 391  * start the closure of the transport in the work processor.
 392  */
 393 void rxrpc_unuse_local(struct rxrpc_local *local)
 394 {
 395         if (local) {
 396                 if (__rxrpc_unuse_local(local)) {
 397                         rxrpc_get_local(local);
 398                         rxrpc_queue_local(local);
 399                 }
 400         }
 401 }
 402 
 403 /*
 404  * Destroy a local endpoint's socket and then hand the record to RCU to dispose
 405  * of.
 406  *
 407  * Closing the socket cannot be done from bottom half context or RCU callback
 408  * context because it might sleep.
 409  */
 410 static void rxrpc_local_destroyer(struct rxrpc_local *local)
 411 {
 412         struct socket *socket = local->socket;
 413         struct rxrpc_net *rxnet = local->rxnet;
 414 
 415         _enter("%d", local->debug_id);
 416 
 417         local->dead = true;
 418 
 419         mutex_lock(&rxnet->local_mutex);
 420         list_del_init(&local->link);
 421         mutex_unlock(&rxnet->local_mutex);
 422 
 423         rxrpc_clean_up_local_conns(local);
 424         rxrpc_service_connection_reaper(&rxnet->service_conn_reaper);
 425         ASSERT(!local->service);
 426 
 427         if (socket) {
 428                 local->socket = NULL;
 429                 kernel_sock_shutdown(socket, SHUT_RDWR);
 430                 socket->sk->sk_user_data = NULL;
 431                 sock_release(socket);
 432         }
 433 
 434         /* At this point, there should be no more packets coming in to the
 435          * local endpoint.
 436          */
 437         rxrpc_purge_queue(&local->reject_queue);
 438         rxrpc_purge_queue(&local->event_queue);
 439 }
 440 
 441 /*
 442  * Process events on an endpoint.  The work item carries a ref which
 443  * we must release.
 444  */
 445 static void rxrpc_local_processor(struct work_struct *work)
 446 {
 447         struct rxrpc_local *local =
 448                 container_of(work, struct rxrpc_local, processor);
 449         bool again;
 450 
 451         trace_rxrpc_local(local->debug_id, rxrpc_local_processing,
 452                           atomic_read(&local->usage), NULL);
 453 
 454         do {
 455                 again = false;
 456                 if (!__rxrpc_use_local(local)) {
 457                         rxrpc_local_destroyer(local);
 458                         break;
 459                 }
 460 
 461                 if (!skb_queue_empty(&local->reject_queue)) {
 462                         rxrpc_reject_packets(local);
 463                         again = true;
 464                 }
 465 
 466                 if (!skb_queue_empty(&local->event_queue)) {
 467                         rxrpc_process_local_events(local);
 468                         again = true;
 469                 }
 470 
 471                 __rxrpc_unuse_local(local);
 472         } while (again);
 473 
 474         rxrpc_put_local(local);
 475 }
 476 
 477 /*
 478  * Destroy a local endpoint after the RCU grace period expires.
 479  */
 480 static void rxrpc_local_rcu(struct rcu_head *rcu)
 481 {
 482         struct rxrpc_local *local = container_of(rcu, struct rxrpc_local, rcu);
 483 
 484         _enter("%d", local->debug_id);
 485 
 486         ASSERT(!work_pending(&local->processor));
 487 
 488         _net("DESTROY LOCAL %d", local->debug_id);
 489         kfree(local);
 490         _leave("");
 491 }
 492 
 493 /*
 494  * Verify the local endpoint list is empty by this point.
 495  */
 496 void rxrpc_destroy_all_locals(struct rxrpc_net *rxnet)
 497 {
 498         struct rxrpc_local *local;
 499 
 500         _enter("");
 501 
 502         flush_workqueue(rxrpc_workqueue);
 503 
 504         if (!list_empty(&rxnet->local_endpoints)) {
 505                 mutex_lock(&rxnet->local_mutex);
 506                 list_for_each_entry(local, &rxnet->local_endpoints, link) {
 507                         pr_err("AF_RXRPC: Leaked local %p {%d}\n",
 508                                local, atomic_read(&local->usage));
 509                 }
 510                 mutex_unlock(&rxnet->local_mutex);
 511                 BUG();
 512         }
 513 }