linux/net/rxrpc/ar-local.c
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   1/* AF_RXRPC local endpoint management
   2 *
   3 * Copyright (C) 2007 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 License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/net.h>
  14#include <linux/skbuff.h>
  15#include <linux/slab.h>
  16#include <net/sock.h>
  17#include <net/af_rxrpc.h>
  18#include "ar-internal.h"
  19
  20static LIST_HEAD(rxrpc_locals);
  21DEFINE_RWLOCK(rxrpc_local_lock);
  22static DECLARE_RWSEM(rxrpc_local_sem);
  23static DECLARE_WAIT_QUEUE_HEAD(rxrpc_local_wq);
  24
  25static void rxrpc_destroy_local(struct work_struct *work);
  26
  27/*
  28 * allocate a new local
  29 */
  30static
  31struct rxrpc_local *rxrpc_alloc_local(struct sockaddr_rxrpc *srx)
  32{
  33        struct rxrpc_local *local;
  34
  35        local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
  36        if (local) {
  37                INIT_WORK(&local->destroyer, &rxrpc_destroy_local);
  38                INIT_WORK(&local->acceptor, &rxrpc_accept_incoming_calls);
  39                INIT_WORK(&local->rejecter, &rxrpc_reject_packets);
  40                INIT_LIST_HEAD(&local->services);
  41                INIT_LIST_HEAD(&local->link);
  42                init_rwsem(&local->defrag_sem);
  43                skb_queue_head_init(&local->accept_queue);
  44                skb_queue_head_init(&local->reject_queue);
  45                spin_lock_init(&local->lock);
  46                rwlock_init(&local->services_lock);
  47                atomic_set(&local->usage, 1);
  48                local->debug_id = atomic_inc_return(&rxrpc_debug_id);
  49                memcpy(&local->srx, srx, sizeof(*srx));
  50        }
  51
  52        _leave(" = %p", local);
  53        return local;
  54}
  55
  56/*
  57 * create the local socket
  58 * - must be called with rxrpc_local_sem writelocked
  59 */
  60static int rxrpc_create_local(struct rxrpc_local *local)
  61{
  62        struct sock *sock;
  63        int ret, opt;
  64
  65        _enter("%p{%d}", local, local->srx.transport_type);
  66
  67        /* create a socket to represent the local endpoint */
  68        ret = sock_create_kern(PF_INET, local->srx.transport_type, IPPROTO_UDP,
  69                               &local->socket);
  70        if (ret < 0) {
  71                _leave(" = %d [socket]", ret);
  72                return ret;
  73        }
  74
  75        /* if a local address was supplied then bind it */
  76        if (local->srx.transport_len > sizeof(sa_family_t)) {
  77                _debug("bind");
  78                ret = kernel_bind(local->socket,
  79                                  (struct sockaddr *) &local->srx.transport,
  80                                  local->srx.transport_len);
  81                if (ret < 0) {
  82                        _debug("bind failed");
  83                        goto error;
  84                }
  85        }
  86
  87        /* we want to receive ICMP errors */
  88        opt = 1;
  89        ret = kernel_setsockopt(local->socket, SOL_IP, IP_RECVERR,
  90                                (char *) &opt, sizeof(opt));
  91        if (ret < 0) {
  92                _debug("setsockopt failed");
  93                goto error;
  94        }
  95
  96        /* we want to set the don't fragment bit */
  97        opt = IP_PMTUDISC_DO;
  98        ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
  99                                (char *) &opt, sizeof(opt));
 100        if (ret < 0) {
 101                _debug("setsockopt failed");
 102                goto error;
 103        }
 104
 105        write_lock_bh(&rxrpc_local_lock);
 106        list_add(&local->link, &rxrpc_locals);
 107        write_unlock_bh(&rxrpc_local_lock);
 108
 109        /* set the socket up */
 110        sock = local->socket->sk;
 111        sock->sk_user_data      = local;
 112        sock->sk_data_ready     = rxrpc_data_ready;
 113        sock->sk_error_report   = rxrpc_UDP_error_report;
 114        _leave(" = 0");
 115        return 0;
 116
 117error:
 118        kernel_sock_shutdown(local->socket, SHUT_RDWR);
 119        local->socket->sk->sk_user_data = NULL;
 120        sock_release(local->socket);
 121        local->socket = NULL;
 122
 123        _leave(" = %d", ret);
 124        return ret;
 125}
 126
 127/*
 128 * create a new local endpoint using the specified UDP address
 129 */
 130struct rxrpc_local *rxrpc_lookup_local(struct sockaddr_rxrpc *srx)
 131{
 132        struct rxrpc_local *local;
 133        int ret;
 134
 135        _enter("{%d,%u,%pI4+%hu}",
 136               srx->transport_type,
 137               srx->transport.family,
 138               &srx->transport.sin.sin_addr,
 139               ntohs(srx->transport.sin.sin_port));
 140
 141        down_write(&rxrpc_local_sem);
 142
 143        /* see if we have a suitable local local endpoint already */
 144        read_lock_bh(&rxrpc_local_lock);
 145
 146        list_for_each_entry(local, &rxrpc_locals, link) {
 147                _debug("CMP {%d,%u,%pI4+%hu}",
 148                       local->srx.transport_type,
 149                       local->srx.transport.family,
 150                       &local->srx.transport.sin.sin_addr,
 151                       ntohs(local->srx.transport.sin.sin_port));
 152
 153                if (local->srx.transport_type != srx->transport_type ||
 154                    local->srx.transport.family != srx->transport.family)
 155                        continue;
 156
 157                switch (srx->transport.family) {
 158                case AF_INET:
 159                        if (local->srx.transport.sin.sin_port !=
 160                            srx->transport.sin.sin_port)
 161                                continue;
 162                        if (memcmp(&local->srx.transport.sin.sin_addr,
 163                                   &srx->transport.sin.sin_addr,
 164                                   sizeof(struct in_addr)) != 0)
 165                                continue;
 166                        goto found_local;
 167
 168                default:
 169                        BUG();
 170                }
 171        }
 172
 173        read_unlock_bh(&rxrpc_local_lock);
 174
 175        /* we didn't find one, so we need to create one */
 176        local = rxrpc_alloc_local(srx);
 177        if (!local) {
 178                up_write(&rxrpc_local_sem);
 179                return ERR_PTR(-ENOMEM);
 180        }
 181
 182        ret = rxrpc_create_local(local);
 183        if (ret < 0) {
 184                up_write(&rxrpc_local_sem);
 185                kfree(local);
 186                _leave(" = %d", ret);
 187                return ERR_PTR(ret);
 188        }
 189
 190        up_write(&rxrpc_local_sem);
 191
 192        _net("LOCAL new %d {%d,%u,%pI4+%hu}",
 193             local->debug_id,
 194             local->srx.transport_type,
 195             local->srx.transport.family,
 196             &local->srx.transport.sin.sin_addr,
 197             ntohs(local->srx.transport.sin.sin_port));
 198
 199        _leave(" = %p [new]", local);
 200        return local;
 201
 202found_local:
 203        rxrpc_get_local(local);
 204        read_unlock_bh(&rxrpc_local_lock);
 205        up_write(&rxrpc_local_sem);
 206
 207        _net("LOCAL old %d {%d,%u,%pI4+%hu}",
 208             local->debug_id,
 209             local->srx.transport_type,
 210             local->srx.transport.family,
 211             &local->srx.transport.sin.sin_addr,
 212             ntohs(local->srx.transport.sin.sin_port));
 213
 214        _leave(" = %p [reuse]", local);
 215        return local;
 216}
 217
 218/*
 219 * release a local endpoint
 220 */
 221void rxrpc_put_local(struct rxrpc_local *local)
 222{
 223        _enter("%p{u=%d}", local, atomic_read(&local->usage));
 224
 225        ASSERTCMP(atomic_read(&local->usage), >, 0);
 226
 227        /* to prevent a race, the decrement and the dequeue must be effectively
 228         * atomic */
 229        write_lock_bh(&rxrpc_local_lock);
 230        if (unlikely(atomic_dec_and_test(&local->usage))) {
 231                _debug("destroy local");
 232                rxrpc_queue_work(&local->destroyer);
 233        }
 234        write_unlock_bh(&rxrpc_local_lock);
 235        _leave("");
 236}
 237
 238/*
 239 * destroy a local endpoint
 240 */
 241static void rxrpc_destroy_local(struct work_struct *work)
 242{
 243        struct rxrpc_local *local =
 244                container_of(work, struct rxrpc_local, destroyer);
 245
 246        _enter("%p{%d}", local, atomic_read(&local->usage));
 247
 248        down_write(&rxrpc_local_sem);
 249
 250        write_lock_bh(&rxrpc_local_lock);
 251        if (atomic_read(&local->usage) > 0) {
 252                write_unlock_bh(&rxrpc_local_lock);
 253                up_read(&rxrpc_local_sem);
 254                _leave(" [resurrected]");
 255                return;
 256        }
 257
 258        list_del(&local->link);
 259        local->socket->sk->sk_user_data = NULL;
 260        write_unlock_bh(&rxrpc_local_lock);
 261
 262        downgrade_write(&rxrpc_local_sem);
 263
 264        ASSERT(list_empty(&local->services));
 265        ASSERT(!work_pending(&local->acceptor));
 266        ASSERT(!work_pending(&local->rejecter));
 267
 268        /* finish cleaning up the local descriptor */
 269        rxrpc_purge_queue(&local->accept_queue);
 270        rxrpc_purge_queue(&local->reject_queue);
 271        kernel_sock_shutdown(local->socket, SHUT_RDWR);
 272        sock_release(local->socket);
 273
 274        up_read(&rxrpc_local_sem);
 275
 276        _net("DESTROY LOCAL %d", local->debug_id);
 277        kfree(local);
 278
 279        if (list_empty(&rxrpc_locals))
 280                wake_up_all(&rxrpc_local_wq);
 281
 282        _leave("");
 283}
 284
 285/*
 286 * preemptively destroy all local local endpoint rather than waiting for
 287 * them to be destroyed
 288 */
 289void __exit rxrpc_destroy_all_locals(void)
 290{
 291        DECLARE_WAITQUEUE(myself,current);
 292
 293        _enter("");
 294
 295        /* we simply have to wait for them to go away */
 296        if (!list_empty(&rxrpc_locals)) {
 297                set_current_state(TASK_UNINTERRUPTIBLE);
 298                add_wait_queue(&rxrpc_local_wq, &myself);
 299
 300                while (!list_empty(&rxrpc_locals)) {
 301                        schedule();
 302                        set_current_state(TASK_UNINTERRUPTIBLE);
 303                }
 304
 305                remove_wait_queue(&rxrpc_local_wq, &myself);
 306                set_current_state(TASK_RUNNING);
 307        }
 308
 309        _leave("");
 310}
 311
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