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/slab.h> 20 #include <linux/hashtable.h> 21 #include <net/sock.h> 22 #include <net/af_rxrpc.h> 23 #include <net/ip.h> 24 #include <net/route.h> 25 #include "ar-internal.h" 26 27 static DEFINE_HASHTABLE(rxrpc_peer_hash, 10); 28 static DEFINE_SPINLOCK(rxrpc_peer_hash_lock); 29 30 /* 31 * Hash a peer key. 32 */ 33 static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local, 34 const struct sockaddr_rxrpc *srx) 35 { 36 const u16 *p; 37 unsigned int i, size; 38 unsigned long hash_key; 39 40 _enter(""); 41 42 hash_key = (unsigned long)local / __alignof__(*local); 43 hash_key += srx->transport_type; 44 hash_key += srx->transport_len; 45 hash_key += srx->transport.family; 46 47 switch (srx->transport.family) { 48 case AF_INET: 49 hash_key += (u16 __force)srx->transport.sin.sin_port; 50 size = sizeof(srx->transport.sin.sin_addr); 51 p = (u16 *)&srx->transport.sin.sin_addr; 52 break; 53 default: 54 WARN(1, "AF_RXRPC: Unsupported transport address family\n"); 55 return 0; 56 } 57 58 /* Step through the peer address in 16-bit portions for speed */ 59 for (i = 0; i < size; i += sizeof(*p), p++) 60 hash_key += *p; 61 62 _leave(" 0x%lx", hash_key); 63 return hash_key; 64 } 65 66 /* 67 * Compare a peer to a key. Return -ve, 0 or +ve to indicate less than, same 68 * or greater than. 69 * 70 * Unfortunately, the primitives in linux/hashtable.h don't allow for sorted 71 * buckets and mid-bucket insertion, so we don't make full use of this 72 * information at this point. 73 */ 74 static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer, 75 struct rxrpc_local *local, 76 const struct sockaddr_rxrpc *srx, 77 unsigned long hash_key) 78 { 79 long diff; 80 81 diff = ((peer->hash_key - hash_key) ?: 82 ((unsigned long)peer->local - (unsigned long)local) ?: 83 (peer->srx.transport_type - srx->transport_type) ?: 84 (peer->srx.transport_len - srx->transport_len) ?: 85 (peer->srx.transport.family - srx->transport.family)); 86 if (diff != 0) 87 return diff; 88 89 switch (srx->transport.family) { 90 case AF_INET: 91 return ((u16 __force)peer->srx.transport.sin.sin_port - 92 (u16 __force)srx->transport.sin.sin_port) ?: 93 memcmp(&peer->srx.transport.sin.sin_addr, 94 &srx->transport.sin.sin_addr, 95 sizeof(struct in_addr)); 96 default: 97 BUG(); 98 } 99 } 100 101 /* 102 * Look up a remote transport endpoint for the specified address using RCU. 103 */ 104 static struct rxrpc_peer *__rxrpc_lookup_peer_rcu( 105 struct rxrpc_local *local, 106 const struct sockaddr_rxrpc *srx, 107 unsigned long hash_key) 108 { 109 struct rxrpc_peer *peer; 110 111 hash_for_each_possible_rcu(rxrpc_peer_hash, peer, hash_link, hash_key) { 112 if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0) { 113 if (atomic_read(&peer->usage) == 0) 114 return NULL; 115 return peer; 116 } 117 } 118 119 return NULL; 120 } 121 122 /* 123 * Look up a remote transport endpoint for the specified address using RCU. 124 */ 125 struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local, 126 const struct sockaddr_rxrpc *srx) 127 { 128 struct rxrpc_peer *peer; 129 unsigned long hash_key = rxrpc_peer_hash_key(local, srx); 130 131 peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key); 132 if (peer) { 133 switch (srx->transport.family) { 134 case AF_INET: 135 _net("PEER %d {%d,%u,%pI4+%hu}", 136 peer->debug_id, 137 peer->srx.transport_type, 138 peer->srx.transport.family, 139 &peer->srx.transport.sin.sin_addr, 140 ntohs(peer->srx.transport.sin.sin_port)); 141 break; 142 } 143 144 _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage)); 145 } 146 return peer; 147 } 148 149 /* 150 * assess the MTU size for the network interface through which this peer is 151 * reached 152 */ 153 static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer) 154 { 155 struct rtable *rt; 156 struct flowi4 fl4; 157 158 peer->if_mtu = 1500; 159 160 rt = ip_route_output_ports(&init_net, &fl4, NULL, 161 peer->srx.transport.sin.sin_addr.s_addr, 0, 162 htons(7000), htons(7001), 163 IPPROTO_UDP, 0, 0); 164 if (IS_ERR(rt)) { 165 _leave(" [route err %ld]", PTR_ERR(rt)); 166 return; 167 } 168 169 peer->if_mtu = dst_mtu(&rt->dst); 170 dst_release(&rt->dst); 171 172 _leave(" [if_mtu %u]", peer->if_mtu); 173 } 174 175 /* 176 * Allocate a peer. 177 */ 178 struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp) 179 { 180 struct rxrpc_peer *peer; 181 182 _enter(""); 183 184 peer = kzalloc(sizeof(struct rxrpc_peer), gfp); 185 if (peer) { 186 atomic_set(&peer->usage, 1); 187 peer->local = local; 188 INIT_HLIST_HEAD(&peer->error_targets); 189 INIT_WORK(&peer->error_distributor, 190 &rxrpc_peer_error_distributor); 191 peer->service_conns = RB_ROOT; 192 seqlock_init(&peer->service_conn_lock); 193 spin_lock_init(&peer->lock); 194 peer->debug_id = atomic_inc_return(&rxrpc_debug_id); 195 } 196 197 _leave(" = %p", peer); 198 return peer; 199 } 200 201 /* 202 * Set up a new peer. 203 */ 204 static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_local *local, 205 struct sockaddr_rxrpc *srx, 206 unsigned long hash_key, 207 gfp_t gfp) 208 { 209 struct rxrpc_peer *peer; 210 211 _enter(""); 212 213 peer = rxrpc_alloc_peer(local, gfp); 214 if (peer) { 215 peer->hash_key = hash_key; 216 memcpy(&peer->srx, srx, sizeof(*srx)); 217 218 rxrpc_assess_MTU_size(peer); 219 peer->mtu = peer->if_mtu; 220 221 if (srx->transport.family == AF_INET) { 222 peer->hdrsize = sizeof(struct iphdr); 223 switch (srx->transport_type) { 224 case SOCK_DGRAM: 225 peer->hdrsize += sizeof(struct udphdr); 226 break; 227 default: 228 BUG(); 229 break; 230 } 231 } else { 232 BUG(); 233 } 234 235 peer->hdrsize += sizeof(struct rxrpc_wire_header); 236 peer->maxdata = peer->mtu - peer->hdrsize; 237 } 238 239 _leave(" = %p", peer); 240 return peer; 241 } 242 243 /* 244 * obtain a remote transport endpoint for the specified address 245 */ 246 struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local, 247 struct sockaddr_rxrpc *srx, gfp_t gfp) 248 { 249 struct rxrpc_peer *peer, *candidate; 250 unsigned long hash_key = rxrpc_peer_hash_key(local, srx); 251 252 _enter("{%d,%d,%pI4+%hu}", 253 srx->transport_type, 254 srx->transport_len, 255 &srx->transport.sin.sin_addr, 256 ntohs(srx->transport.sin.sin_port)); 257 258 /* search the peer list first */ 259 rcu_read_lock(); 260 peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key); 261 if (peer && !rxrpc_get_peer_maybe(peer)) 262 peer = NULL; 263 rcu_read_unlock(); 264 265 if (!peer) { 266 /* The peer is not yet present in hash - create a candidate 267 * for a new record and then redo the search. 268 */ 269 candidate = rxrpc_create_peer(local, srx, hash_key, gfp); 270 if (!candidate) { 271 _leave(" = NULL [nomem]"); 272 return NULL; 273 } 274 275 spin_lock(&rxrpc_peer_hash_lock); 276 277 /* Need to check that we aren't racing with someone else */ 278 peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key); 279 if (peer && !rxrpc_get_peer_maybe(peer)) 280 peer = NULL; 281 if (!peer) 282 hash_add_rcu(rxrpc_peer_hash, 283 &candidate->hash_link, hash_key); 284 285 spin_unlock(&rxrpc_peer_hash_lock); 286 287 if (peer) 288 kfree(candidate); 289 else 290 peer = candidate; 291 } 292 293 _net("PEER %d {%d,%pI4+%hu}", 294 peer->debug_id, 295 peer->srx.transport_type, 296 &peer->srx.transport.sin.sin_addr, 297 ntohs(peer->srx.transport.sin.sin_port)); 298 299 _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage)); 300 return peer; 301 } 302 303 /* 304 * Discard a ref on a remote peer record. 305 */ 306 void __rxrpc_put_peer(struct rxrpc_peer *peer) 307 { 308 ASSERT(hlist_empty(&peer->error_targets)); 309 310 spin_lock(&rxrpc_peer_hash_lock); 311 hash_del_rcu(&peer->hash_link); 312 spin_unlock(&rxrpc_peer_hash_lock); 313 314 kfree_rcu(peer, rcu); 315 } 316