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 <net/route.h>
  23 #include "ar-internal.h"
  24
  25 static LIST_HEAD(rxrpc_peers);
  26 static DEFINE_RWLOCK(rxrpc_peer_lock);
  27 static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);
  28
  29 static void rxrpc_destroy_peer(struct work_struct *work);
  30
  31 /*
  32  * assess the MTU size for the network interface through which this peer is
  33  * reached
  34  */
  35 static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
  36 {
  37         struct rtable *rt;
  38         struct flowi fl;
  39         int ret;
  40
  41         peer->if_mtu = 1500;
  42
  43         memset(&fl, 0, sizeof(fl));
  44
  45         switch (peer->srx.transport.family) {
  46         case AF_INET:
  47                 fl.oif = 0;
  48                 fl.proto = IPPROTO_UDP,
  49                 fl.nl_u.ip4_u.saddr = 0;
  50                 fl.nl_u.ip4_u.daddr = peer->srx.transport.sin.sin_addr.s_addr;
  51                 fl.nl_u.ip4_u.tos = 0;
  52                 /* assume AFS.CM talking to AFS.FS */
  53                 fl.uli_u.ports.sport = htons(7001);
  54                 fl.uli_u.ports.dport = htons(7000);
  55                 break;
  56         default:
  57                 BUG();
  58         }
  59
  60         ret = ip_route_output_key(&init_net, &rt, &fl);
  61         if (ret < 0) {
  62                 _leave(" [route err %d]", ret);
  63                 return;
  64         }
  65
  66         peer->if_mtu = dst_mtu(&rt->u.dst);
  67         dst_release(&rt->u.dst);
  68
  69         _leave(" [if_mtu %u]", peer->if_mtu);
  70 }
  71
  72 /*
  73  * allocate a new peer
  74  */
  75 static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
  76                                            gfp_t gfp)
  77 {
  78         struct rxrpc_peer *peer;
  79
  80         _enter("");
  81
  82         peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
  83         if (peer) {
  84                 INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
  85                 INIT_LIST_HEAD(&peer->link);
  86                 INIT_LIST_HEAD(&peer->error_targets);
  87                 spin_lock_init(&peer->lock);
  88                 atomic_set(&peer->usage, 1);
  89                 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
  90                 memcpy(&peer->srx, srx, sizeof(*srx));
  91
  92                 rxrpc_assess_MTU_size(peer);
  93                 peer->mtu = peer->if_mtu;
  94
  95                 if (srx->transport.family == AF_INET) {
  96                         peer->hdrsize = sizeof(struct iphdr);
  97                         switch (srx->transport_type) {
  98                         case SOCK_DGRAM:
  99                                 peer->hdrsize += sizeof(struct udphdr);
 100                                 break;
 101                         default:
 102                                 BUG();
 103                                 break;
 104                         }
 105                 } else {
 106                         BUG();
 107                 }
 108
 109                 peer->hdrsize += sizeof(struct rxrpc_header);
 110                 peer->maxdata = peer->mtu - peer->hdrsize;
 111         }
 112
 113         _leave(" = %p", peer);
 114         return peer;
 115 }
 116
 117 /*
 118  * obtain a remote transport endpoint for the specified address
 119  */
 120 struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
 121 {
 122         struct rxrpc_peer *peer, *candidate;
 123         const char *new = "old";
 124         int usage;
 125
 126         _enter("{%d,%d,%pI4+%hu}",
 127                srx->transport_type,
 128                srx->transport_len,
 129                &srx->transport.sin.sin_addr,
 130                ntohs(srx->transport.sin.sin_port));
 131
 132         /* search the peer list first */
 133         read_lock_bh(&rxrpc_peer_lock);
 134         list_for_each_entry(peer, &rxrpc_peers, link) {
 135                 _debug("check PEER %d { u=%d t=%d l=%d }",
 136                        peer->debug_id,
 137                        atomic_read(&peer->usage),
 138                        peer->srx.transport_type,
 139                        peer->srx.transport_len);
 140
 141                 if (atomic_read(&peer->usage) > 0 &&
 142                     peer->srx.transport_type == srx->transport_type &&
 143                     peer->srx.transport_len == srx->transport_len &&
 144                     memcmp(&peer->srx.transport,
 145                            &srx->transport,
 146                            srx->transport_len) == 0)
 147                         goto found_extant_peer;
 148         }
 149         read_unlock_bh(&rxrpc_peer_lock);
 150
 151         /* not yet present - create a candidate for a new record and then
 152          * redo the search */
 153         candidate = rxrpc_alloc_peer(srx, gfp);
 154         if (!candidate) {
 155                 _leave(" = -ENOMEM");
 156                 return ERR_PTR(-ENOMEM);
 157         }
 158
 159         write_lock_bh(&rxrpc_peer_lock);
 160
 161         list_for_each_entry(peer, &rxrpc_peers, link) {
 162                 if (atomic_read(&peer->usage) > 0 &&
 163                     peer->srx.transport_type == srx->transport_type &&
 164                     peer->srx.transport_len == srx->transport_len &&
 165                     memcmp(&peer->srx.transport,
 166                            &srx->transport,
 167                            srx->transport_len) == 0)
 168                         goto found_extant_second;
 169         }
 170
 171         /* we can now add the new candidate to the list */
 172         peer = candidate;
 173         candidate = NULL;
 174
 175         list_add_tail(&peer->link, &rxrpc_peers);
 176         write_unlock_bh(&rxrpc_peer_lock);
 177         new = "new";
 178
 179 success:
 180         _net("PEER %s %d {%d,%u,%pI4+%hu}",
 181              new,
 182              peer->debug_id,
 183              peer->srx.transport_type,
 184              peer->srx.transport.family,
 185              &peer->srx.transport.sin.sin_addr,
 186              ntohs(peer->srx.transport.sin.sin_port));
 187
 188         _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
 189         return peer;
 190
 191         /* we found the peer in the list immediately */
 192 found_extant_peer:
 193         usage = atomic_inc_return(&peer->usage);
 194         read_unlock_bh(&rxrpc_peer_lock);
 195         goto success;
 196
 197         /* we found the peer on the second time through the list */
 198 found_extant_second:
 199         usage = atomic_inc_return(&peer->usage);
 200         write_unlock_bh(&rxrpc_peer_lock);
 201         kfree(candidate);
 202         goto success;
 203 }
 204
 205 /*
 206  * find the peer associated with a packet
 207  */
 208 struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
 209                                    __be32 addr, __be16 port)
 210 {
 211         struct rxrpc_peer *peer;
 212
 213         _enter("");
 214
 215         /* search the peer list */
 216         read_lock_bh(&rxrpc_peer_lock);
 217
 218         if (local->srx.transport.family == AF_INET &&
 219             local->srx.transport_type == SOCK_DGRAM
 220             ) {
 221                 list_for_each_entry(peer, &rxrpc_peers, link) {
 222                         if (atomic_read(&peer->usage) > 0 &&
 223                             peer->srx.transport_type == SOCK_DGRAM &&
 224                             peer->srx.transport.family == AF_INET &&
 225                             peer->srx.transport.sin.sin_port == port &&
 226                             peer->srx.transport.sin.sin_addr.s_addr == addr)
 227                                 goto found_UDP_peer;
 228                 }
 229
 230                 goto new_UDP_peer;
 231         }
 232
 233         read_unlock_bh(&rxrpc_peer_lock);
 234         _leave(" = -EAFNOSUPPORT");
 235         return ERR_PTR(-EAFNOSUPPORT);
 236
 237 found_UDP_peer:
 238         _net("Rx UDP DGRAM from peer %d", peer->debug_id);
 239         atomic_inc(&peer->usage);
 240         read_unlock_bh(&rxrpc_peer_lock);
 241         _leave(" = %p", peer);
 242         return peer;
 243
 244 new_UDP_peer:
 245         _net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
 246         read_unlock_bh(&rxrpc_peer_lock);
 247         _leave(" = -EBUSY [new]");
 248         return ERR_PTR(-EBUSY);
 249 }
 250
 251 /*
 252  * release a remote transport endpoint
 253  */
 254 void rxrpc_put_peer(struct rxrpc_peer *peer)
 255 {
 256         _enter("%p{u=%d}", peer, atomic_read(&peer->usage));
 257
 258         ASSERTCMP(atomic_read(&peer->usage), >, 0);
 259
 260         if (likely(!atomic_dec_and_test(&peer->usage))) {
 261                 _leave(" [in use]");
 262                 return;
 263         }
 264
 265         rxrpc_queue_work(&peer->destroyer);
 266         _leave("");
 267 }
 268
 269 /*
 270  * destroy a remote transport endpoint
 271  */
 272 static void rxrpc_destroy_peer(struct work_struct *work)
 273 {
 274         struct rxrpc_peer *peer =
 275                 container_of(work, struct rxrpc_peer, destroyer);
 276
 277         _enter("%p{%d}", peer, atomic_read(&peer->usage));
 278
 279         write_lock_bh(&rxrpc_peer_lock);
 280         list_del(&peer->link);
 281         write_unlock_bh(&rxrpc_peer_lock);
 282
 283         _net("DESTROY PEER %d", peer->debug_id);
 284         kfree(peer);
 285
 286         if (list_empty(&rxrpc_peers))
 287                 wake_up_all(&rxrpc_peer_wq);
 288         _leave("");
 289 }
 290
 291 /*
 292  * preemptively destroy all the peer records from a transport endpoint rather
 293  * than waiting for them to time out
 294  */
 295 void __exit rxrpc_destroy_all_peers(void)
 296 {
 297         DECLARE_WAITQUEUE(myself,current);
 298
 299         _enter("");
 300
 301         /* we simply have to wait for them to go away */
 302         if (!list_empty(&rxrpc_peers)) {
 303                 set_current_state(TASK_UNINTERRUPTIBLE);
 304                 add_wait_queue(&rxrpc_peer_wq, &myself);
 305
 306                 while (!list_empty(&rxrpc_peers)) {
 307                         schedule();
 308                         set_current_state(TASK_UNINTERRUPTIBLE);
 309                 }
 310
 311                 remove_wait_queue(&rxrpc_peer_wq, &myself);
 312                 set_current_state(TASK_RUNNING);
 313         }
 314
 315         _leave("");
 316 }