net/rxrpc/ar-peer.c

   1 /* RxRPC remote transport 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/udp.h>
  16 #include <linux/in.h>
  17 #include <linux/in6.h>
  18 #include <linux/icmp.h>
  19 #include <net/sock.h>
  20 #include <net/af_rxrpc.h>
  21 #include <net/ip.h>
  22 #include "ar-internal.h"
  23
  24 static LIST_HEAD(rxrpc_peers);
  25 static DEFINE_RWLOCK(rxrpc_peer_lock);
  26 static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);
  27
  28 static void rxrpc_destroy_peer(struct work_struct *work);
  29
  30 /*
  31  * allocate a new peer
  32  */
  33 static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
  34                                            gfp_t gfp)
  35 {
  36         struct rxrpc_peer *peer;
  37
  38         _enter("");
  39
  40         peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
  41         if (peer) {
  42                 INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
  43                 INIT_LIST_HEAD(&peer->link);
  44                 INIT_LIST_HEAD(&peer->error_targets);
  45                 spin_lock_init(&peer->lock);
  46                 atomic_set(&peer->usage, 1);
  47                 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
  48                 memcpy(&peer->srx, srx, sizeof(*srx));
  49
  50                 peer->mtu = peer->if_mtu = 65535;
  51
  52                 if (srx->transport.family == AF_INET) {
  53                         peer->hdrsize = sizeof(struct iphdr);
  54                         switch (srx->transport_type) {
  55                         case SOCK_DGRAM:
  56                                 peer->hdrsize += sizeof(struct udphdr);
  57                                 break;
  58                         default:
  59                                 BUG();
  60                                 break;
  61                         }
  62                 } else {
  63                         BUG();
  64                 }
  65
  66                 peer->hdrsize += sizeof(struct rxrpc_header);
  67                 peer->maxdata = peer->mtu - peer->hdrsize;
  68         }
  69
  70         _leave(" = %p", peer);
  71         return peer;
  72 }
  73
  74 /*
  75  * obtain a remote transport endpoint for the specified address
  76  */
  77 struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
  78 {
  79         struct rxrpc_peer *peer, *candidate;
  80         const char *new = "old";
  81         int usage;
  82
  83         _enter("{%d,%d,%u.%u.%u.%u+%hu}",
  84                srx->transport_type,
  85                srx->transport_len,
  86                NIPQUAD(srx->transport.sin.sin_addr),
  87                ntohs(srx->transport.sin.sin_port));
  88
  89         /* search the peer list first */
  90         read_lock_bh(&rxrpc_peer_lock);
  91         list_for_each_entry(peer, &rxrpc_peers, link) {
  92                 _debug("check PEER %d { u=%d t=%d l=%d }",
  93                        peer->debug_id,
  94                        atomic_read(&peer->usage),
  95                        peer->srx.transport_type,
  96                        peer->srx.transport_len);
  97
  98                 if (atomic_read(&peer->usage) > 0 &&
  99                     peer->srx.transport_type == srx->transport_type &&
 100                     peer->srx.transport_len == srx->transport_len &&
 101                     memcmp(&peer->srx.transport,
 102                            &srx->transport,
 103                            srx->transport_len) == 0)
 104                         goto found_extant_peer;
 105         }
 106         read_unlock_bh(&rxrpc_peer_lock);
 107
 108         /* not yet present - create a candidate for a new record and then
 109          * redo the search */
 110         candidate = rxrpc_alloc_peer(srx, gfp);
 111         if (!candidate) {
 112                 _leave(" = -ENOMEM");
 113                 return ERR_PTR(-ENOMEM);
 114         }
 115
 116         write_lock_bh(&rxrpc_peer_lock);
 117
 118         list_for_each_entry(peer, &rxrpc_peers, link) {
 119                 if (atomic_read(&peer->usage) > 0 &&
 120                     peer->srx.transport_type == srx->transport_type &&
 121                     peer->srx.transport_len == srx->transport_len &&
 122                     memcmp(&peer->srx.transport,
 123                            &srx->transport,
 124                            srx->transport_len) == 0)
 125                         goto found_extant_second;
 126         }
 127
 128         /* we can now add the new candidate to the list */
 129         peer = candidate;
 130         candidate = NULL;
 131
 132         list_add_tail(&peer->link, &rxrpc_peers);
 133         write_unlock_bh(&rxrpc_peer_lock);
 134         new = "new";
 135
 136 success:
 137         _net("PEER %s %d {%d,%u,%u.%u.%u.%u+%hu}",
 138              new,
 139              peer->debug_id,
 140              peer->srx.transport_type,
 141              peer->srx.transport.family,
 142              NIPQUAD(peer->srx.transport.sin.sin_addr),
 143              ntohs(peer->srx.transport.sin.sin_port));
 144
 145         _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
 146         return peer;
 147
 148         /* we found the peer in the list immediately */
 149 found_extant_peer:
 150         usage = atomic_inc_return(&peer->usage);
 151         read_unlock_bh(&rxrpc_peer_lock);
 152         goto success;
 153
 154         /* we found the peer on the second time through the list */
 155 found_extant_second:
 156         usage = atomic_inc_return(&peer->usage);
 157         write_unlock_bh(&rxrpc_peer_lock);
 158         kfree(candidate);
 159         goto success;
 160 }
 161
 162 /*
 163  * find the peer associated with a packet
 164  */
 165 struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
 166                                    __be32 addr, __be16 port)
 167 {
 168         struct rxrpc_peer *peer;
 169
 170         _enter("");
 171
 172         /* search the peer list */
 173         read_lock_bh(&rxrpc_peer_lock);
 174
 175         if (local->srx.transport.family == AF_INET &&
 176             local->srx.transport_type == SOCK_DGRAM
 177             ) {
 178                 list_for_each_entry(peer, &rxrpc_peers, link) {
 179                         if (atomic_read(&peer->usage) > 0 &&
 180                             peer->srx.transport_type == SOCK_DGRAM &&
 181                             peer->srx.transport.family == AF_INET &&
 182                             peer->srx.transport.sin.sin_port == port &&
 183                             peer->srx.transport.sin.sin_addr.s_addr == addr)
 184                                 goto found_UDP_peer;
 185                 }
 186
 187                 goto new_UDP_peer;
 188         }
 189
 190         read_unlock_bh(&rxrpc_peer_lock);
 191         _leave(" = -EAFNOSUPPORT");
 192         return ERR_PTR(-EAFNOSUPPORT);
 193
 194 found_UDP_peer:
 195         _net("Rx UDP DGRAM from peer %d", peer->debug_id);
 196         atomic_inc(&peer->usage);
 197         read_unlock_bh(&rxrpc_peer_lock);
 198         _leave(" = %p", peer);
 199         return peer;
 200
 201 new_UDP_peer:
 202         _net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
 203         read_unlock_bh(&rxrpc_peer_lock);
 204         _leave(" = -EBUSY [new]");
 205         return ERR_PTR(-EBUSY);
 206 }
 207
 208 /*
 209  * release a remote transport endpoint
 210  */
 211 void rxrpc_put_peer(struct rxrpc_peer *peer)
 212 {
 213         _enter("%p{u=%d}", peer, atomic_read(&peer->usage));
 214
 215         ASSERTCMP(atomic_read(&peer->usage), >, 0);
 216
 217         if (likely(!atomic_dec_and_test(&peer->usage))) {
 218                 _leave(" [in use]");
 219                 return;
 220         }
 221
 222         rxrpc_queue_work(&peer->destroyer);
 223         _leave("");
 224 }
 225
 226 /*
 227  * destroy a remote transport endpoint
 228  */
 229 static void rxrpc_destroy_peer(struct work_struct *work)
 230 {
 231         struct rxrpc_peer *peer =
 232                 container_of(work, struct rxrpc_peer, destroyer);
 233
 234         _enter("%p{%d}", peer, atomic_read(&peer->usage));
 235
 236         write_lock_bh(&rxrpc_peer_lock);
 237         list_del(&peer->link);
 238         write_unlock_bh(&rxrpc_peer_lock);
 239
 240         _net("DESTROY PEER %d", peer->debug_id);
 241         kfree(peer);
 242
 243         if (list_empty(&rxrpc_peers))
 244                 wake_up_all(&rxrpc_peer_wq);
 245         _leave("");
 246 }
 247
 248 /*
 249  * preemptively destroy all the peer records from a transport endpoint rather
 250  * than waiting for them to time out
 251  */
 252 void __exit rxrpc_destroy_all_peers(void)
 253 {
 254         DECLARE_WAITQUEUE(myself,current);
 255
 256         _enter("");
 257
 258         /* we simply have to wait for them to go away */
 259         if (!list_empty(&rxrpc_peers)) {
 260                 set_current_state(TASK_UNINTERRUPTIBLE);
 261                 add_wait_queue(&rxrpc_peer_wq, &myself);
 262
 263                 while (!list_empty(&rxrpc_peers)) {
 264                         schedule();
 265                         set_current_state(TASK_UNINTERRUPTIBLE);
 266                 }
 267
 268                 remove_wait_queue(&rxrpc_peer_wq, &myself);
 269                 set_current_state(TASK_RUNNING);
 270         }
 271
 272         _leave("");
 273 }