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/af_rxrpc.h>
  23 #include "ar-internal.h"
  24
  25 static void rxrpc_local_processor(struct work_struct *);
  26 static void rxrpc_local_rcu(struct rcu_head *);
  27
  28 static DEFINE_MUTEX(rxrpc_local_mutex);
  29 static LIST_HEAD(rxrpc_local_endpoints);
  30
  31 /*
  32  * Compare a local to an address.  Return -ve, 0 or +ve to indicate less than,
  33  * same or greater than.
  34  *
  35  * We explicitly don't compare the RxRPC service ID as we want to reject
  36  * conflicting uses by differing services.  Further, we don't want to share
  37  * addresses with different options (IPv6), so we don't compare those bits
  38  * either.
  39  */
  40 static long rxrpc_local_cmp_key(const struct rxrpc_local *local,
  41                                 const struct sockaddr_rxrpc *srx)
  42 {
  43         long diff;
  44
  45         diff = ((local->srx.transport_type - srx->transport_type) ?:
  46                 (local->srx.transport_len - srx->transport_len) ?:
  47                 (local->srx.transport.family - srx->transport.family));
  48         if (diff != 0)
  49                 return diff;
  50
  51         switch (srx->transport.family) {
  52         case AF_INET:
  53                 /* If the choice of UDP port is left up to the transport, then
  54                  * the endpoint record doesn't match.
  55                  */
  56                 return ((u16 __force)local->srx.transport.sin.sin_port -
  57                         (u16 __force)srx->transport.sin.sin_port) ?:
  58                         memcmp(&local->srx.transport.sin.sin_addr,
  59                                &srx->transport.sin.sin_addr,
  60                                sizeof(struct in_addr));
  61         default:
  62                 BUG();
  63         }
  64 }
  65
  66 /*
  67  * Allocate a new local endpoint.
  68  */
  69 static struct rxrpc_local *rxrpc_alloc_local(const struct sockaddr_rxrpc *srx)
  70 {
  71         struct rxrpc_local *local;
  72
  73         local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
  74         if (local) {
  75                 atomic_set(&local->usage, 1);
  76                 INIT_LIST_HEAD(&local->link);
  77                 INIT_WORK(&local->processor, rxrpc_local_processor);
  78                 INIT_LIST_HEAD(&local->services);
  79                 init_rwsem(&local->defrag_sem);
  80                 skb_queue_head_init(&local->accept_queue);
  81                 skb_queue_head_init(&local->reject_queue);
  82                 skb_queue_head_init(&local->event_queue);
  83                 local->client_conns = RB_ROOT;
  84                 spin_lock_init(&local->client_conns_lock);
  85                 spin_lock_init(&local->lock);
  86                 rwlock_init(&local->services_lock);
  87                 local->debug_id = atomic_inc_return(&rxrpc_debug_id);
  88                 memcpy(&local->srx, srx, sizeof(*srx));
  89         }
  90
  91         _leave(" = %p", local);
  92         return local;
  93 }
  94
  95 /*
  96  * create the local socket
  97  * - must be called with rxrpc_local_mutex locked
  98  */
  99 static int rxrpc_open_socket(struct rxrpc_local *local)
 100 {
 101         struct sock *sock;
 102         int ret, opt;
 103
 104         _enter("%p{%d}", local, local->srx.transport_type);
 105
 106         /* create a socket to represent the local endpoint */
 107         ret = sock_create_kern(&init_net, PF_INET, local->srx.transport_type,
 108                                IPPROTO_UDP, &local->socket);
 109         if (ret < 0) {
 110                 _leave(" = %d [socket]", ret);
 111                 return ret;
 112         }
 113
 114         /* if a local address was supplied then bind it */
 115         if (local->srx.transport_len > sizeof(sa_family_t)) {
 116                 _debug("bind");
 117                 ret = kernel_bind(local->socket,
 118                                   (struct sockaddr *)&local->srx.transport,
 119                                   local->srx.transport_len);
 120                 if (ret < 0) {
 121                         _debug("bind failed %d", ret);
 122                         goto error;
 123                 }
 124         }
 125
 126         /* we want to receive ICMP errors */
 127         opt = 1;
 128         ret = kernel_setsockopt(local->socket, SOL_IP, IP_RECVERR,
 129                                 (char *) &opt, sizeof(opt));
 130         if (ret < 0) {
 131                 _debug("setsockopt failed");
 132                 goto error;
 133         }
 134
 135         /* we want to set the don't fragment bit */
 136         opt = IP_PMTUDISC_DO;
 137         ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
 138                                 (char *) &opt, sizeof(opt));
 139         if (ret < 0) {
 140                 _debug("setsockopt failed");
 141                 goto error;
 142         }
 143
 144         /* set the socket up */
 145         sock = local->socket->sk;
 146         sock->sk_user_data      = local;
 147         sock->sk_data_ready     = rxrpc_data_ready;
 148         sock->sk_error_report   = rxrpc_error_report;
 149         _leave(" = 0");
 150         return 0;
 151
 152 error:
 153         kernel_sock_shutdown(local->socket, SHUT_RDWR);
 154         local->socket->sk->sk_user_data = NULL;
 155         sock_release(local->socket);
 156         local->socket = NULL;
 157
 158         _leave(" = %d", ret);
 159         return ret;
 160 }
 161
 162 /*
 163  * Look up or create a new local endpoint using the specified local address.
 164  */
 165 struct rxrpc_local *rxrpc_lookup_local(const struct sockaddr_rxrpc *srx)
 166 {
 167         struct rxrpc_local *local;
 168         struct list_head *cursor;
 169         const char *age;
 170         long diff;
 171         int ret;
 172
 173         if (srx->transport.family == AF_INET) {
 174                 _enter("{%d,%u,%pI4+%hu}",
 175                        srx->transport_type,
 176                        srx->transport.family,
 177                        &srx->transport.sin.sin_addr,
 178                        ntohs(srx->transport.sin.sin_port));
 179         } else {
 180                 _enter("{%d,%u}",
 181                        srx->transport_type,
 182                        srx->transport.family);
 183                 return ERR_PTR(-EAFNOSUPPORT);
 184         }
 185
 186         mutex_lock(&rxrpc_local_mutex);
 187
 188         for (cursor = rxrpc_local_endpoints.next;
 189              cursor != &rxrpc_local_endpoints;
 190              cursor = cursor->next) {
 191                 local = list_entry(cursor, struct rxrpc_local, link);
 192
 193                 diff = rxrpc_local_cmp_key(local, srx);
 194                 if (diff < 0)
 195                         continue;
 196                 if (diff > 0)
 197                         break;
 198
 199                 /* Services aren't allowed to share transport sockets, so
 200                  * reject that here.  It is possible that the object is dying -
 201                  * but it may also still have the local transport address that
 202                  * we want bound.
 203                  */
 204                 if (srx->srx_service) {
 205                         local = NULL;
 206                         goto addr_in_use;
 207                 }
 208
 209                 /* Found a match.  We replace a dying object.  Attempting to
 210                  * bind the transport socket may still fail if we're attempting
 211                  * to use a local address that the dying object is still using.
 212                  */
 213                 if (!rxrpc_get_local_maybe(local)) {
 214                         cursor = cursor->next;
 215                         list_del_init(&local->link);
 216                         break;
 217                 }
 218
 219                 age = "old";
 220                 goto found;
 221         }
 222
 223         local = rxrpc_alloc_local(srx);
 224         if (!local)
 225                 goto nomem;
 226
 227         ret = rxrpc_open_socket(local);
 228         if (ret < 0)
 229                 goto sock_error;
 230
 231         list_add_tail(&local->link, cursor);
 232         age = "new";
 233
 234 found:
 235         mutex_unlock(&rxrpc_local_mutex);
 236
 237         _net("LOCAL %s %d {%d,%u,%pI4+%hu}",
 238              age,
 239              local->debug_id,
 240              local->srx.transport_type,
 241              local->srx.transport.family,
 242              &local->srx.transport.sin.sin_addr,
 243              ntohs(local->srx.transport.sin.sin_port));
 244
 245         _leave(" = %p", local);
 246         return local;
 247
 248 nomem:
 249         ret = -ENOMEM;
 250 sock_error:
 251         mutex_unlock(&rxrpc_local_mutex);
 252         kfree(local);
 253         _leave(" = %d", ret);
 254         return ERR_PTR(ret);
 255
 256 addr_in_use:
 257         mutex_unlock(&rxrpc_local_mutex);
 258         _leave(" = -EADDRINUSE");
 259         return ERR_PTR(-EADDRINUSE);
 260 }
 261
 262 /*
 263  * A local endpoint reached its end of life.
 264  */
 265 void __rxrpc_put_local(struct rxrpc_local *local)
 266 {
 267         _enter("%d", local->debug_id);
 268         rxrpc_queue_work(&local->processor);
 269 }
 270
 271 /*
 272  * Destroy a local endpoint's socket and then hand the record to RCU to dispose
 273  * of.
 274  *
 275  * Closing the socket cannot be done from bottom half context or RCU callback
 276  * context because it might sleep.
 277  */
 278 static void rxrpc_local_destroyer(struct rxrpc_local *local)
 279 {
 280         struct socket *socket = local->socket;
 281
 282         _enter("%d", local->debug_id);
 283
 284         /* We can get a race between an incoming call packet queueing the
 285          * processor again and the work processor starting the destruction
 286          * process which will shut down the UDP socket.
 287          */
 288         if (local->dead) {
 289                 _leave(" [already dead]");
 290                 return;
 291         }
 292         local->dead = true;
 293
 294         mutex_lock(&rxrpc_local_mutex);
 295         list_del_init(&local->link);
 296         mutex_unlock(&rxrpc_local_mutex);
 297
 298         ASSERT(RB_EMPTY_ROOT(&local->client_conns));
 299         ASSERT(list_empty(&local->services));
 300
 301         if (socket) {
 302                 local->socket = NULL;
 303                 kernel_sock_shutdown(socket, SHUT_RDWR);
 304                 socket->sk->sk_user_data = NULL;
 305                 sock_release(socket);
 306         }
 307
 308         /* At this point, there should be no more packets coming in to the
 309          * local endpoint.
 310          */
 311         rxrpc_purge_queue(&local->accept_queue);
 312         rxrpc_purge_queue(&local->reject_queue);
 313         rxrpc_purge_queue(&local->event_queue);
 314
 315         _debug("rcu local %d", local->debug_id);
 316         call_rcu(&local->rcu, rxrpc_local_rcu);
 317 }
 318
 319 /*
 320  * Process events on an endpoint
 321  */
 322 static void rxrpc_local_processor(struct work_struct *work)
 323 {
 324         struct rxrpc_local *local =
 325                 container_of(work, struct rxrpc_local, processor);
 326         bool again;
 327
 328         _enter("%d", local->debug_id);
 329
 330         do {
 331                 again = false;
 332                 if (atomic_read(&local->usage) == 0)
 333                         return rxrpc_local_destroyer(local);
 334
 335                 if (!skb_queue_empty(&local->accept_queue)) {
 336                         rxrpc_accept_incoming_calls(local);
 337                         again = true;
 338                 }
 339
 340                 if (!skb_queue_empty(&local->reject_queue)) {
 341                         rxrpc_reject_packets(local);
 342                         again = true;
 343                 }
 344
 345                 if (!skb_queue_empty(&local->event_queue)) {
 346                         rxrpc_process_local_events(local);
 347                         again = true;
 348                 }
 349         } while (again);
 350 }
 351
 352 /*
 353  * Destroy a local endpoint after the RCU grace period expires.
 354  */
 355 static void rxrpc_local_rcu(struct rcu_head *rcu)
 356 {
 357         struct rxrpc_local *local = container_of(rcu, struct rxrpc_local, rcu);
 358
 359         _enter("%d", local->debug_id);
 360
 361         ASSERT(!work_pending(&local->processor));
 362
 363         _net("DESTROY LOCAL %d", local->debug_id);
 364         kfree(local);
 365         _leave("");
 366 }
 367
 368 /*
 369  * Verify the local endpoint list is empty by this point.
 370  */
 371 void __exit rxrpc_destroy_all_locals(void)
 372 {
 373         struct rxrpc_local *local;
 374
 375         _enter("");
 376
 377         flush_workqueue(rxrpc_workqueue);
 378
 379         if (!list_empty(&rxrpc_local_endpoints)) {
 380                 mutex_lock(&rxrpc_local_mutex);
 381                 list_for_each_entry(local, &rxrpc_local_endpoints, link) {
 382                         pr_err("AF_RXRPC: Leaked local %p {%d}\n",
 383                                local, atomic_read(&local->usage));
 384                 }
 385                 mutex_unlock(&rxrpc_local_mutex);
 386                 BUG();
 387         }
 388
 389         rcu_barrier();
 390 }