net/rxrpc/ar-local.c

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