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         struct flowi fl;
  40         int ret;
  41
  42         peer->if_mtu = 1500;
  43
  44         memset(&fl, 0, sizeof(fl));
  45
  46         switch (peer->srx.transport.family) {
  47         case AF_INET:
  48                 fl.oif = 0;
  49                 fl.proto = IPPROTO_UDP,
  50                 fl.fl4_dst = peer->srx.transport.sin.sin_addr.s_addr;
  51                 fl.fl4_src = 0;
  52                 fl.fl4_tos = 0;
  53                 /* assume AFS.CM talking to AFS.FS */
  54                 fl.fl_ip_sport = htons(7001);
  55                 fl.fl_ip_dport = htons(7000);
  56                 break;
  57         default:
  58                 BUG();
  59         }
  60
  61         ret = ip_route_output_key(&init_net, &rt, &fl);
  62         if (ret < 0) {
  63                 _leave(" [route err %d]", ret);
  64                 return;
  65         }
  66
  67         peer->if_mtu = dst_mtu(&rt->dst);
  68         dst_release(&rt->dst);
  69
  70         _leave(" [if_mtu %u]", peer->if_mtu);
  71 }
  72
  73 /*
  74  * allocate a new peer
  75  */
  76 static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
  77                                            gfp_t gfp)
  78 {
  79         struct rxrpc_peer *peer;
  80
  81         _enter("");
  82
  83         peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
  84         if (peer) {
  85                 INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
  86                 INIT_LIST_HEAD(&peer->link);
  87                 INIT_LIST_HEAD(&peer->error_targets);
  88                 spin_lock_init(&peer->lock);
  89                 atomic_set(&peer->usage, 1);
  90                 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
  91                 memcpy(&peer->srx, srx, sizeof(*srx));
  92
  93                 rxrpc_assess_MTU_size(peer);
  94                 peer->mtu = peer->if_mtu;
  95
  96                 if (srx->transport.family == AF_INET) {
  97                         peer->hdrsize = sizeof(struct iphdr);
  98                         switch (srx->transport_type) {
  99                         case SOCK_DGRAM:
 100                                 peer->hdrsize += sizeof(struct udphdr);
 101                                 break;
 102                         default:
 103                                 BUG();
 104                                 break;
 105                         }
 106                 } else {
 107                         BUG();
 108                 }
 109
 110                 peer->hdrsize += sizeof(struct rxrpc_header);
 111                 peer->maxdata = peer->mtu - peer->hdrsize;
 112         }
 113
 114         _leave(" = %p", peer);
 115         return peer;
 116 }
 117
 118 /*
 119  * obtain a remote transport endpoint for the specified address
 120  */
 121 struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
 122 {
 123         struct rxrpc_peer *peer, *candidate;
 124         const char *new = "old";
 125         int usage;
 126
 127         _enter("{%d,%d,%pI4+%hu}",
 128                srx->transport_type,
 129                srx->transport_len,
 130                &srx->transport.sin.sin_addr,
 131                ntohs(srx->transport.sin.sin_port));
 132
 133         /* search the peer list first */
 134         read_lock_bh(&rxrpc_peer_lock);
 135         list_for_each_entry(peer, &rxrpc_peers, link) {
 136                 _debug("check PEER %d { u=%d t=%d l=%d }",
 137                        peer->debug_id,
 138                        atomic_read(&peer->usage),
 139                        peer->srx.transport_type,
 140                        peer->srx.transport_len);
 141
 142                 if (atomic_read(&peer->usage) > 0 &&
 143                     peer->srx.transport_type == srx->transport_type &&
 144                     peer->srx.transport_len == srx->transport_len &&
 145                     memcmp(&peer->srx.transport,
 146                            &srx->transport,
 147                            srx->transport_len) == 0)
 148                         goto found_extant_peer;
 149         }
 150         read_unlock_bh(&rxrpc_peer_lock);
 151
 152         /* not yet present - create a candidate for a new record and then
 153          * redo the search */
 154         candidate = rxrpc_alloc_peer(srx, gfp);
 155         if (!candidate) {
 156                 _leave(" = -ENOMEM");
 157                 return ERR_PTR(-ENOMEM);
 158         }
 159
 160         write_lock_bh(&rxrpc_peer_lock);
 161
 162         list_for_each_entry(peer, &rxrpc_peers, link) {
 163                 if (atomic_read(&peer->usage) > 0 &&
 164                     peer->srx.transport_type == srx->transport_type &&
 165                     peer->srx.transport_len == srx->transport_len &&
 166                     memcmp(&peer->srx.transport,
 167                            &srx->transport,
 168                            srx->transport_len) == 0)
 169                         goto found_extant_second;
 170         }
 171
 172         /* we can now add the new candidate to the list */
 173         peer = candidate;
 174         candidate = NULL;
 175
 176         list_add_tail(&peer->link, &rxrpc_peers);
 177         write_unlock_bh(&rxrpc_peer_lock);
 178         new = "new";
 179
 180 success:
 181         _net("PEER %s %d {%d,%u,%pI4+%hu}",
 182              new,
 183              peer->debug_id,
 184              peer->srx.transport_type,
 185              peer->srx.transport.family,
 186              &peer->srx.transport.sin.sin_addr,
 187              ntohs(peer->srx.transport.sin.sin_port));
 188
 189         _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
 190         return peer;
 191
 192         /* we found the peer in the list immediately */
 193 found_extant_peer:
 194         usage = atomic_inc_return(&peer->usage);
 195         read_unlock_bh(&rxrpc_peer_lock);
 196         goto success;
 197
 198         /* we found the peer on the second time through the list */
 199 found_extant_second:
 200         usage = atomic_inc_return(&peer->usage);
 201         write_unlock_bh(&rxrpc_peer_lock);
 202         kfree(candidate);
 203         goto success;
 204 }
 205
 206 /*
 207  * find the peer associated with a packet
 208  */
 209 struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
 210                                    __be32 addr, __be16 port)
 211 {
 212         struct rxrpc_peer *peer;
 213
 214         _enter("");
 215
 216         /* search the peer list */
 217         read_lock_bh(&rxrpc_peer_lock);
 218
 219         if (local->srx.transport.family == AF_INET &&
 220             local->srx.transport_type == SOCK_DGRAM
 221             ) {
 222                 list_for_each_entry(peer, &rxrpc_peers, link) {
 223                         if (atomic_read(&peer->usage) > 0 &&
 224                             peer->srx.transport_type == SOCK_DGRAM &&
 225                             peer->srx.transport.family == AF_INET &&
 226                             peer->srx.transport.sin.sin_port == port &&
 227                             peer->srx.transport.sin.sin_addr.s_addr == addr)
 228                                 goto found_UDP_peer;
 229                 }
 230
 231                 goto new_UDP_peer;
 232         }
 233
 234         read_unlock_bh(&rxrpc_peer_lock);
 235         _leave(" = -EAFNOSUPPORT");
 236         return ERR_PTR(-EAFNOSUPPORT);
 237
 238 found_UDP_peer:
 239         _net("Rx UDP DGRAM from peer %d", peer->debug_id);
 240         atomic_inc(&peer->usage);
 241         read_unlock_bh(&rxrpc_peer_lock);
 242         _leave(" = %p", peer);
 243         return peer;
 244
 245 new_UDP_peer:
 246         _net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
 247         read_unlock_bh(&rxrpc_peer_lock);
 248         _leave(" = -EBUSY [new]");
 249         return ERR_PTR(-EBUSY);
 250 }
 251
 252 /*
 253  * release a remote transport endpoint
 254  */
 255 void rxrpc_put_peer(struct rxrpc_peer *peer)
 256 {
 257         _enter("%p{u=%d}", peer, atomic_read(&peer->usage));
 258
 259         ASSERTCMP(atomic_read(&peer->usage), >, 0);
 260
 261         if (likely(!atomic_dec_and_test(&peer->usage))) {
 262                 _leave(" [in use]");
 263                 return;
 264         }
 265
 266         rxrpc_queue_work(&peer->destroyer);
 267         _leave("");
 268 }
 269
 270 /*
 271  * destroy a remote transport endpoint
 272  */
 273 static void rxrpc_destroy_peer(struct work_struct *work)
 274 {
 275         struct rxrpc_peer *peer =
 276                 container_of(work, struct rxrpc_peer, destroyer);
 277
 278         _enter("%p{%d}", peer, atomic_read(&peer->usage));
 279
 280         write_lock_bh(&rxrpc_peer_lock);
 281         list_del(&peer->link);
 282         write_unlock_bh(&rxrpc_peer_lock);
 283
 284         _net("DESTROY PEER %d", peer->debug_id);
 285         kfree(peer);
 286
 287         if (list_empty(&rxrpc_peers))
 288                 wake_up_all(&rxrpc_peer_wq);
 289         _leave("");
 290 }
 291
 292 /*
 293  * preemptively destroy all the peer records from a transport endpoint rather
 294  * than waiting for them to time out
 295  */
 296 void __exit rxrpc_destroy_all_peers(void)
 297 {
 298         DECLARE_WAITQUEUE(myself,current);
 299
 300         _enter("");
 301
 302         /* we simply have to wait for them to go away */
 303         if (!list_empty(&rxrpc_peers)) {
 304                 set_current_state(TASK_UNINTERRUPTIBLE);
 305                 add_wait_queue(&rxrpc_peer_wq, &myself);
 306
 307                 while (!list_empty(&rxrpc_peers)) {
 308                         schedule();
 309                         set_current_state(TASK_UNINTERRUPTIBLE);
 310                 }
 311
 312                 remove_wait_queue(&rxrpc_peer_wq, &myself);
 313                 set_current_state(TASK_RUNNING);
 314         }
 315
 316         _leave("");
 317 }