net/rxrpc/peer_object.c

   1 /* RxRPC remote transport endpoint record management
   2  *
   3  * Copyright (C) 2007, 2016 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/udp.h>
  18 #include <linux/in.h>
  19 #include <linux/in6.h>
  20 #include <linux/slab.h>
  21 #include <linux/hashtable.h>
  22 #include <net/sock.h>
  23 #include <net/af_rxrpc.h>
  24 #include <net/ip.h>
  25 #include <net/route.h>
  26 #include <net/ip6_route.h>
  27 #include "ar-internal.h"
  28
  29 static DEFINE_HASHTABLE(rxrpc_peer_hash, 10);
  30 static DEFINE_SPINLOCK(rxrpc_peer_hash_lock);
  31
  32 /*
  33  * Hash a peer key.
  34  */
  35 static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local,
  36                                          const struct sockaddr_rxrpc *srx)
  37 {
  38         const u16 *p;
  39         unsigned int i, size;
  40         unsigned long hash_key;
  41
  42         _enter("");
  43
  44         hash_key = (unsigned long)local / __alignof__(*local);
  45         hash_key += srx->transport_type;
  46         hash_key += srx->transport_len;
  47         hash_key += srx->transport.family;
  48
  49         switch (srx->transport.family) {
  50         case AF_INET:
  51                 hash_key += (u16 __force)srx->transport.sin.sin_port;
  52                 size = sizeof(srx->transport.sin.sin_addr);
  53                 p = (u16 *)&srx->transport.sin.sin_addr;
  54                 break;
  55         case AF_INET6:
  56                 hash_key += (u16 __force)srx->transport.sin.sin_port;
  57                 size = sizeof(srx->transport.sin6.sin6_addr);
  58                 p = (u16 *)&srx->transport.sin6.sin6_addr;
  59                 break;
  60         default:
  61                 WARN(1, "AF_RXRPC: Unsupported transport address family\n");
  62                 return 0;
  63         }
  64
  65         /* Step through the peer address in 16-bit portions for speed */
  66         for (i = 0; i < size; i += sizeof(*p), p++)
  67                 hash_key += *p;
  68
  69         _leave(" 0x%lx", hash_key);
  70         return hash_key;
  71 }
  72
  73 /*
  74  * Compare a peer to a key.  Return -ve, 0 or +ve to indicate less than, same
  75  * or greater than.
  76  *
  77  * Unfortunately, the primitives in linux/hashtable.h don't allow for sorted
  78  * buckets and mid-bucket insertion, so we don't make full use of this
  79  * information at this point.
  80  */
  81 static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer,
  82                                struct rxrpc_local *local,
  83                                const struct sockaddr_rxrpc *srx,
  84                                unsigned long hash_key)
  85 {
  86         long diff;
  87
  88         diff = ((peer->hash_key - hash_key) ?:
  89                 ((unsigned long)peer->local - (unsigned long)local) ?:
  90                 (peer->srx.transport_type - srx->transport_type) ?:
  91                 (peer->srx.transport_len - srx->transport_len) ?:
  92                 (peer->srx.transport.family - srx->transport.family));
  93         if (diff != 0)
  94                 return diff;
  95
  96         switch (srx->transport.family) {
  97         case AF_INET:
  98                 return ((u16 __force)peer->srx.transport.sin.sin_port -
  99                         (u16 __force)srx->transport.sin.sin_port) ?:
 100                         memcmp(&peer->srx.transport.sin.sin_addr,
 101                                &srx->transport.sin.sin_addr,
 102                                sizeof(struct in_addr));
 103         case AF_INET6:
 104                 return ((u16 __force)peer->srx.transport.sin6.sin6_port -
 105                         (u16 __force)srx->transport.sin6.sin6_port) ?:
 106                         memcmp(&peer->srx.transport.sin6.sin6_addr,
 107                                &srx->transport.sin6.sin6_addr,
 108                                sizeof(struct in6_addr));
 109         default:
 110                 BUG();
 111         }
 112 }
 113
 114 /*
 115  * Look up a remote transport endpoint for the specified address using RCU.
 116  */
 117 static struct rxrpc_peer *__rxrpc_lookup_peer_rcu(
 118         struct rxrpc_local *local,
 119         const struct sockaddr_rxrpc *srx,
 120         unsigned long hash_key)
 121 {
 122         struct rxrpc_peer *peer;
 123
 124         hash_for_each_possible_rcu(rxrpc_peer_hash, peer, hash_link, hash_key) {
 125                 if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0) {
 126                         if (atomic_read(&peer->usage) == 0)
 127                                 return NULL;
 128                         return peer;
 129                 }
 130         }
 131
 132         return NULL;
 133 }
 134
 135 /*
 136  * Look up a remote transport endpoint for the specified address using RCU.
 137  */
 138 struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local,
 139                                          const struct sockaddr_rxrpc *srx)
 140 {
 141         struct rxrpc_peer *peer;
 142         unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
 143
 144         peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
 145         if (peer) {
 146                 _net("PEER %d {%pISp}", peer->debug_id, &peer->srx.transport);
 147                 _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
 148         }
 149         return peer;
 150 }
 151
 152 /*
 153  * assess the MTU size for the network interface through which this peer is
 154  * reached
 155  */
 156 static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
 157 {
 158         struct dst_entry *dst;
 159         struct rtable *rt;
 160         struct flowi fl;
 161         struct flowi4 *fl4 = &fl.u.ip4;
 162         struct flowi6 *fl6 = &fl.u.ip6;
 163
 164         peer->if_mtu = 1500;
 165
 166         memset(&fl, 0, sizeof(fl));
 167         switch (peer->srx.transport.family) {
 168         case AF_INET:
 169                 rt = ip_route_output_ports(
 170                         &init_net, fl4, NULL,
 171                         peer->srx.transport.sin.sin_addr.s_addr, 0,
 172                         htons(7000), htons(7001), IPPROTO_UDP, 0, 0);
 173                 if (IS_ERR(rt)) {
 174                         _leave(" [route err %ld]", PTR_ERR(rt));
 175                         return;
 176                 }
 177                 dst = &rt->dst;
 178                 break;
 179
 180         case AF_INET6:
 181                 fl6->flowi6_iif = LOOPBACK_IFINDEX;
 182                 fl6->flowi6_scope = RT_SCOPE_UNIVERSE;
 183                 fl6->flowi6_proto = IPPROTO_UDP;
 184                 memcpy(&fl6->daddr, &peer->srx.transport.sin6.sin6_addr,
 185                        sizeof(struct in6_addr));
 186                 fl6->fl6_dport = htons(7001);
 187                 fl6->fl6_sport = htons(7000);
 188                 dst = ip6_route_output(&init_net, NULL, fl6);
 189                 if (IS_ERR(dst)) {
 190                         _leave(" [route err %ld]", PTR_ERR(dst));
 191                         return;
 192                 }
 193                 break;
 194
 195         default:
 196                 BUG();
 197         }
 198
 199         peer->if_mtu = dst_mtu(dst);
 200         dst_release(dst);
 201
 202         _leave(" [if_mtu %u]", peer->if_mtu);
 203 }
 204
 205 /*
 206  * Allocate a peer.
 207  */
 208 struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp)
 209 {
 210         struct rxrpc_peer *peer;
 211
 212         _enter("");
 213
 214         peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
 215         if (peer) {
 216                 atomic_set(&peer->usage, 1);
 217                 peer->local = local;
 218                 INIT_HLIST_HEAD(&peer->error_targets);
 219                 INIT_WORK(&peer->error_distributor,
 220                           &rxrpc_peer_error_distributor);
 221                 peer->service_conns = RB_ROOT;
 222                 seqlock_init(&peer->service_conn_lock);
 223                 spin_lock_init(&peer->lock);
 224                 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
 225         }
 226
 227         _leave(" = %p", peer);
 228         return peer;
 229 }
 230
 231 /*
 232  * Initialise peer record.
 233  */
 234 static void rxrpc_init_peer(struct rxrpc_peer *peer, unsigned long hash_key)
 235 {
 236         peer->hash_key = hash_key;
 237         rxrpc_assess_MTU_size(peer);
 238         peer->mtu = peer->if_mtu;
 239
 240         switch (peer->srx.transport.family) {
 241         case AF_INET:
 242                 peer->hdrsize = sizeof(struct iphdr);
 243                 break;
 244         case AF_INET6:
 245                 peer->hdrsize = sizeof(struct ipv6hdr);
 246                 break;
 247         default:
 248                 BUG();
 249         }
 250
 251         switch (peer->srx.transport_type) {
 252         case SOCK_DGRAM:
 253                 peer->hdrsize += sizeof(struct udphdr);
 254                 break;
 255         default:
 256                 BUG();
 257         }
 258
 259         peer->hdrsize += sizeof(struct rxrpc_wire_header);
 260         peer->maxdata = peer->mtu - peer->hdrsize;
 261 }
 262
 263 /*
 264  * Set up a new peer.
 265  */
 266 static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_local *local,
 267                                             struct sockaddr_rxrpc *srx,
 268                                             unsigned long hash_key,
 269                                             gfp_t gfp)
 270 {
 271         struct rxrpc_peer *peer;
 272
 273         _enter("");
 274
 275         peer = rxrpc_alloc_peer(local, gfp);
 276         if (peer) {
 277                 memcpy(&peer->srx, srx, sizeof(*srx));
 278                 rxrpc_init_peer(peer, hash_key);
 279         }
 280
 281         _leave(" = %p", peer);
 282         return peer;
 283 }
 284
 285 /*
 286  * Set up a new incoming peer.  The address is prestored in the preallocated
 287  * peer.
 288  */
 289 struct rxrpc_peer *rxrpc_lookup_incoming_peer(struct rxrpc_local *local,
 290                                               struct rxrpc_peer *prealloc)
 291 {
 292         struct rxrpc_peer *peer;
 293         unsigned long hash_key;
 294
 295         hash_key = rxrpc_peer_hash_key(local, &prealloc->srx);
 296         prealloc->local = local;
 297         rxrpc_init_peer(prealloc, hash_key);
 298
 299         spin_lock(&rxrpc_peer_hash_lock);
 300
 301         /* Need to check that we aren't racing with someone else */
 302         peer = __rxrpc_lookup_peer_rcu(local, &prealloc->srx, hash_key);
 303         if (peer && !rxrpc_get_peer_maybe(peer))
 304                 peer = NULL;
 305         if (!peer) {
 306                 peer = prealloc;
 307                 hash_add_rcu(rxrpc_peer_hash, &peer->hash_link, hash_key);
 308         }
 309
 310         spin_unlock(&rxrpc_peer_hash_lock);
 311         return peer;
 312 }
 313
 314 /*
 315  * obtain a remote transport endpoint for the specified address
 316  */
 317 struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local,
 318                                      struct sockaddr_rxrpc *srx, gfp_t gfp)
 319 {
 320         struct rxrpc_peer *peer, *candidate;
 321         unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
 322
 323         _enter("{%pISp}", &srx->transport);
 324
 325         /* search the peer list first */
 326         rcu_read_lock();
 327         peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
 328         if (peer && !rxrpc_get_peer_maybe(peer))
 329                 peer = NULL;
 330         rcu_read_unlock();
 331
 332         if (!peer) {
 333                 /* The peer is not yet present in hash - create a candidate
 334                  * for a new record and then redo the search.
 335                  */
 336                 candidate = rxrpc_create_peer(local, srx, hash_key, gfp);
 337                 if (!candidate) {
 338                         _leave(" = NULL [nomem]");
 339                         return NULL;
 340                 }
 341
 342                 spin_lock_bh(&rxrpc_peer_hash_lock);
 343
 344                 /* Need to check that we aren't racing with someone else */
 345                 peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
 346                 if (peer && !rxrpc_get_peer_maybe(peer))
 347                         peer = NULL;
 348                 if (!peer)
 349                         hash_add_rcu(rxrpc_peer_hash,
 350                                      &candidate->hash_link, hash_key);
 351
 352                 spin_unlock_bh(&rxrpc_peer_hash_lock);
 353
 354                 if (peer)
 355                         kfree(candidate);
 356                 else
 357                         peer = candidate;
 358         }
 359
 360         _net("PEER %d {%pISp}", peer->debug_id, &peer->srx.transport);
 361
 362         _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
 363         return peer;
 364 }
 365
 366 /*
 367  * Discard a ref on a remote peer record.
 368  */
 369 void __rxrpc_put_peer(struct rxrpc_peer *peer)
 370 {
 371         ASSERT(hlist_empty(&peer->error_targets));
 372
 373         spin_lock_bh(&rxrpc_peer_hash_lock);
 374         hash_del_rcu(&peer->hash_link);
 375         spin_unlock_bh(&rxrpc_peer_hash_lock);
 376
 377         kfree_rcu(peer, rcu);
 378 }
 379
 380 /**
 381  * rxrpc_kernel_get_peer - Get the peer address of a call
 382  * @sock: The socket on which the call is in progress.
 383  * @call: The call to query
 384  * @_srx: Where to place the result
 385  *
 386  * Get the address of the remote peer in a call.
 387  */
 388 void rxrpc_kernel_get_peer(struct socket *sock, struct rxrpc_call *call,
 389                            struct sockaddr_rxrpc *_srx)
 390 {
 391         *_srx = call->peer->srx;
 392 }
 393 EXPORT_SYMBOL(rxrpc_kernel_get_peer);