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 <linux/slab.h>
  20 #include <net/sock.h>
  21 #include <net/af_rxrpc.h>
  22 #include <net/ip.h>
  23 #include <net/route.h>
  24 #include "ar-internal.h"
  25
  26 static LIST_HEAD(rxrpc_peers);
  27 static DEFINE_RWLOCK(rxrpc_peer_lock);
  28 static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);
  29
  30 static void rxrpc_destroy_peer(struct work_struct *work);
  31
  32 /*
  33  * assess the MTU size for the network interface through which this peer is
  34  * reached
  35  */
  36 static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
  37 {
  38         struct rtable *rt;
  39
  40         peer->if_mtu = 1500;
  41
  42         rt = ip_route_output_ports(&init_net, NULL,
  43                                    peer->srx.transport.sin.sin_addr.s_addr, 0,
  44                                    htons(7000), htons(7001),
  45                                    IPPROTO_UDP, 0, 0);
  46         if (IS_ERR(rt)) {
  47                 _leave(" [route err %ld]", PTR_ERR(rt));
  48                 return;
  49         }
  50
  51         peer->if_mtu = dst_mtu(&rt->dst);
  52         dst_release(&rt->dst);
  53
  54         _leave(" [if_mtu %u]", peer->if_mtu);
  55 }
  56
  57 /*
  58  * allocate a new peer
  59  */
  60 static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
  61                                            gfp_t gfp)
  62 {
  63         struct rxrpc_peer *peer;
  64
  65         _enter("");
  66
  67         peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
  68         if (peer) {
  69                 INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
  70                 INIT_LIST_HEAD(&peer->link);
  71                 INIT_LIST_HEAD(&peer->error_targets);
  72                 spin_lock_init(&peer->lock);
  73                 atomic_set(&peer->usage, 1);
  74                 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
  75                 memcpy(&peer->srx, srx, sizeof(*srx));
  76
  77                 rxrpc_assess_MTU_size(peer);
  78                 peer->mtu = peer->if_mtu;
  79
  80                 if (srx->transport.family == AF_INET) {
  81                         peer->hdrsize = sizeof(struct iphdr);
  82                         switch (srx->transport_type) {
  83                         case SOCK_DGRAM:
  84                                 peer->hdrsize += sizeof(struct udphdr);
  85                                 break;
  86                         default:
  87                                 BUG();
  88                                 break;
  89                         }
  90                 } else {
  91                         BUG();
  92                 }
  93
  94                 peer->hdrsize += sizeof(struct rxrpc_header);
  95                 peer->maxdata = peer->mtu - peer->hdrsize;
  96         }
  97
  98         _leave(" = %p", peer);
  99         return peer;
 100 }
 101
 102 /*
 103  * obtain a remote transport endpoint for the specified address
 104  */
 105 struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
 106 {
 107         struct rxrpc_peer *peer, *candidate;
 108         const char *new = "old";
 109         int usage;
 110
 111         _enter("{%d,%d,%pI4+%hu}",
 112                srx->transport_type,
 113                srx->transport_len,
 114                &srx->transport.sin.sin_addr,
 115                ntohs(srx->transport.sin.sin_port));
 116
 117         /* search the peer list first */
 118         read_lock_bh(&rxrpc_peer_lock);
 119         list_for_each_entry(peer, &rxrpc_peers, link) {
 120                 _debug("check PEER %d { u=%d t=%d l=%d }",
 121                        peer->debug_id,
 122                        atomic_read(&peer->usage),
 123                        peer->srx.transport_type,
 124                        peer->srx.transport_len);
 125
 126                 if (atomic_read(&peer->usage) > 0 &&
 127                     peer->srx.transport_type == srx->transport_type &&
 128                     peer->srx.transport_len == srx->transport_len &&
 129                     memcmp(&peer->srx.transport,
 130                            &srx->transport,
 131                            srx->transport_len) == 0)
 132                         goto found_extant_peer;
 133         }
 134         read_unlock_bh(&rxrpc_peer_lock);
 135
 136         /* not yet present - create a candidate for a new record and then
 137          * redo the search */
 138         candidate = rxrpc_alloc_peer(srx, gfp);
 139         if (!candidate) {
 140                 _leave(" = -ENOMEM");
 141                 return ERR_PTR(-ENOMEM);
 142         }
 143
 144         write_lock_bh(&rxrpc_peer_lock);
 145
 146         list_for_each_entry(peer, &rxrpc_peers, link) {
 147                 if (atomic_read(&peer->usage) > 0 &&
 148                     peer->srx.transport_type == srx->transport_type &&
 149                     peer->srx.transport_len == srx->transport_len &&
 150                     memcmp(&peer->srx.transport,
 151                            &srx->transport,
 152                            srx->transport_len) == 0)
 153                         goto found_extant_second;
 154         }
 155
 156         /* we can now add the new candidate to the list */
 157         peer = candidate;
 158         candidate = NULL;
 159
 160         list_add_tail(&peer->link, &rxrpc_peers);
 161         write_unlock_bh(&rxrpc_peer_lock);
 162         new = "new";
 163
 164 success:
 165         _net("PEER %s %d {%d,%u,%pI4+%hu}",
 166              new,
 167              peer->debug_id,
 168              peer->srx.transport_type,
 169              peer->srx.transport.family,
 170              &peer->srx.transport.sin.sin_addr,
 171              ntohs(peer->srx.transport.sin.sin_port));
 172
 173         _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
 174         return peer;
 175
 176         /* we found the peer in the list immediately */
 177 found_extant_peer:
 178         usage = atomic_inc_return(&peer->usage);
 179         read_unlock_bh(&rxrpc_peer_lock);
 180         goto success;
 181
 182         /* we found the peer on the second time through the list */
 183 found_extant_second:
 184         usage = atomic_inc_return(&peer->usage);
 185         write_unlock_bh(&rxrpc_peer_lock);
 186         kfree(candidate);
 187         goto success;
 188 }
 189
 190 /*
 191  * find the peer associated with a packet
 192  */
 193 struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
 194                                    __be32 addr, __be16 port)
 195 {
 196         struct rxrpc_peer *peer;
 197
 198         _enter("");
 199
 200         /* search the peer list */
 201         read_lock_bh(&rxrpc_peer_lock);
 202
 203         if (local->srx.transport.family == AF_INET &&
 204             local->srx.transport_type == SOCK_DGRAM
 205             ) {
 206                 list_for_each_entry(peer, &rxrpc_peers, link) {
 207                         if (atomic_read(&peer->usage) > 0 &&
 208                             peer->srx.transport_type == SOCK_DGRAM &&
 209                             peer->srx.transport.family == AF_INET &&
 210                             peer->srx.transport.sin.sin_port == port &&
 211                             peer->srx.transport.sin.sin_addr.s_addr == addr)
 212                                 goto found_UDP_peer;
 213                 }
 214
 215                 goto new_UDP_peer;
 216         }
 217
 218         read_unlock_bh(&rxrpc_peer_lock);
 219         _leave(" = -EAFNOSUPPORT");
 220         return ERR_PTR(-EAFNOSUPPORT);
 221
 222 found_UDP_peer:
 223         _net("Rx UDP DGRAM from peer %d", peer->debug_id);
 224         atomic_inc(&peer->usage);
 225         read_unlock_bh(&rxrpc_peer_lock);
 226         _leave(" = %p", peer);
 227         return peer;
 228
 229 new_UDP_peer:
 230         _net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
 231         read_unlock_bh(&rxrpc_peer_lock);
 232         _leave(" = -EBUSY [new]");
 233         return ERR_PTR(-EBUSY);
 234 }
 235
 236 /*
 237  * release a remote transport endpoint
 238  */
 239 void rxrpc_put_peer(struct rxrpc_peer *peer)
 240 {
 241         _enter("%p{u=%d}", peer, atomic_read(&peer->usage));
 242
 243         ASSERTCMP(atomic_read(&peer->usage), >, 0);
 244
 245         if (likely(!atomic_dec_and_test(&peer->usage))) {
 246                 _leave(" [in use]");
 247                 return;
 248         }
 249
 250         rxrpc_queue_work(&peer->destroyer);
 251         _leave("");
 252 }
 253
 254 /*
 255  * destroy a remote transport endpoint
 256  */
 257 static void rxrpc_destroy_peer(struct work_struct *work)
 258 {
 259         struct rxrpc_peer *peer =
 260                 container_of(work, struct rxrpc_peer, destroyer);
 261
 262         _enter("%p{%d}", peer, atomic_read(&peer->usage));
 263
 264         write_lock_bh(&rxrpc_peer_lock);
 265         list_del(&peer->link);
 266         write_unlock_bh(&rxrpc_peer_lock);
 267
 268         _net("DESTROY PEER %d", peer->debug_id);
 269         kfree(peer);
 270
 271         if (list_empty(&rxrpc_peers))
 272                 wake_up_all(&rxrpc_peer_wq);
 273         _leave("");
 274 }
 275
 276 /*
 277  * preemptively destroy all the peer records from a transport endpoint rather
 278  * than waiting for them to time out
 279  */
 280 void __exit rxrpc_destroy_all_peers(void)
 281 {
 282         DECLARE_WAITQUEUE(myself,current);
 283
 284         _enter("");
 285
 286         /* we simply have to wait for them to go away */
 287         if (!list_empty(&rxrpc_peers)) {
 288                 set_current_state(TASK_UNINTERRUPTIBLE);
 289                 add_wait_queue(&rxrpc_peer_wq, &myself);
 290
 291                 while (!list_empty(&rxrpc_peers)) {
 292                         schedule();
 293                         set_current_state(TASK_UNINTERRUPTIBLE);
 294                 }
 295
 296                 remove_wait_queue(&rxrpc_peer_wq, &myself);
 297                 set_current_state(TASK_RUNNING);
 298         }
 299
 300         _leave("");
 301 }