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 25static LIST_HEAD(rxrpc_peers); 26static DEFINE_RWLOCK(rxrpc_peer_lock); 27static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq); 28 29static 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 */ 35static 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(&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 */ 75static 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 */ 120struct 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,%u.%u.%u.%u+%hu}", 127 srx->transport_type, 128 srx->transport_len, 129 NIPQUAD(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 179success: 180 _net("PEER %s %d {%d,%u,%u.%u.%u.%u+%hu}", 181 new, 182 peer->debug_id, 183 peer->srx.transport_type, 184 peer->srx.transport.family, 185 NIPQUAD(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 */ 192found_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 */ 198found_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 */ 208struct 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 237found_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 244new_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 */ 254void 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 */ 272static 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 */ 295void __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} 317