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 */
rxrpc_assess_MTU_size(struct rxrpc_peer * peer)36 static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
37 {
38 struct rtable *rt;
39 struct flowi4 fl4;
40
41 peer->if_mtu = 1500;
42
43 rt = ip_route_output_ports(&init_net, &fl4, NULL,
44 peer->srx.transport.sin.sin_addr.s_addr, 0,
45 htons(7000), htons(7001),
46 IPPROTO_UDP, 0, 0);
47 if (IS_ERR(rt)) {
48 _leave(" [route err %ld]", PTR_ERR(rt));
49 return;
50 }
51
52 peer->if_mtu = dst_mtu(&rt->dst);
53 dst_release(&rt->dst);
54
55 _leave(" [if_mtu %u]", peer->if_mtu);
56 }
57
58 /*
59 * allocate a new peer
60 */
rxrpc_alloc_peer(struct sockaddr_rxrpc * srx,gfp_t gfp)61 static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
62 gfp_t gfp)
63 {
64 struct rxrpc_peer *peer;
65
66 _enter("");
67
68 peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
69 if (peer) {
70 INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
71 INIT_LIST_HEAD(&peer->link);
72 INIT_LIST_HEAD(&peer->error_targets);
73 spin_lock_init(&peer->lock);
74 atomic_set(&peer->usage, 1);
75 peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
76 memcpy(&peer->srx, srx, sizeof(*srx));
77
78 rxrpc_assess_MTU_size(peer);
79 peer->mtu = peer->if_mtu;
80
81 if (srx->transport.family == AF_INET) {
82 peer->hdrsize = sizeof(struct iphdr);
83 switch (srx->transport_type) {
84 case SOCK_DGRAM:
85 peer->hdrsize += sizeof(struct udphdr);
86 break;
87 default:
88 BUG();
89 break;
90 }
91 } else {
92 BUG();
93 }
94
95 peer->hdrsize += sizeof(struct rxrpc_header);
96 peer->maxdata = peer->mtu - peer->hdrsize;
97 }
98
99 _leave(" = %p", peer);
100 return peer;
101 }
102
103 /*
104 * obtain a remote transport endpoint for the specified address
105 */
rxrpc_get_peer(struct sockaddr_rxrpc * srx,gfp_t gfp)106 struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
107 {
108 struct rxrpc_peer *peer, *candidate;
109 const char *new = "old";
110 int usage;
111
112 _enter("{%d,%d,%pI4+%hu}",
113 srx->transport_type,
114 srx->transport_len,
115 &srx->transport.sin.sin_addr,
116 ntohs(srx->transport.sin.sin_port));
117
118 /* search the peer list first */
119 read_lock_bh(&rxrpc_peer_lock);
120 list_for_each_entry(peer, &rxrpc_peers, link) {
121 _debug("check PEER %d { u=%d t=%d l=%d }",
122 peer->debug_id,
123 atomic_read(&peer->usage),
124 peer->srx.transport_type,
125 peer->srx.transport_len);
126
127 if (atomic_read(&peer->usage) > 0 &&
128 peer->srx.transport_type == srx->transport_type &&
129 peer->srx.transport_len == srx->transport_len &&
130 memcmp(&peer->srx.transport,
131 &srx->transport,
132 srx->transport_len) == 0)
133 goto found_extant_peer;
134 }
135 read_unlock_bh(&rxrpc_peer_lock);
136
137 /* not yet present - create a candidate for a new record and then
138 * redo the search */
139 candidate = rxrpc_alloc_peer(srx, gfp);
140 if (!candidate) {
141 _leave(" = -ENOMEM");
142 return ERR_PTR(-ENOMEM);
143 }
144
145 write_lock_bh(&rxrpc_peer_lock);
146
147 list_for_each_entry(peer, &rxrpc_peers, link) {
148 if (atomic_read(&peer->usage) > 0 &&
149 peer->srx.transport_type == srx->transport_type &&
150 peer->srx.transport_len == srx->transport_len &&
151 memcmp(&peer->srx.transport,
152 &srx->transport,
153 srx->transport_len) == 0)
154 goto found_extant_second;
155 }
156
157 /* we can now add the new candidate to the list */
158 peer = candidate;
159 candidate = NULL;
160 usage = atomic_read(&peer->usage);
161
162 list_add_tail(&peer->link, &rxrpc_peers);
163 write_unlock_bh(&rxrpc_peer_lock);
164 new = "new";
165
166 success:
167 _net("PEER %s %d {%d,%u,%pI4+%hu}",
168 new,
169 peer->debug_id,
170 peer->srx.transport_type,
171 peer->srx.transport.family,
172 &peer->srx.transport.sin.sin_addr,
173 ntohs(peer->srx.transport.sin.sin_port));
174
175 _leave(" = %p {u=%d}", peer, usage);
176 return peer;
177
178 /* we found the peer in the list immediately */
179 found_extant_peer:
180 usage = atomic_inc_return(&peer->usage);
181 read_unlock_bh(&rxrpc_peer_lock);
182 goto success;
183
184 /* we found the peer on the second time through the list */
185 found_extant_second:
186 usage = atomic_inc_return(&peer->usage);
187 write_unlock_bh(&rxrpc_peer_lock);
188 kfree(candidate);
189 goto success;
190 }
191
192 /*
193 * find the peer associated with a packet
194 */
rxrpc_find_peer(struct rxrpc_local * local,__be32 addr,__be16 port)195 struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
196 __be32 addr, __be16 port)
197 {
198 struct rxrpc_peer *peer;
199
200 _enter("");
201
202 /* search the peer list */
203 read_lock_bh(&rxrpc_peer_lock);
204
205 if (local->srx.transport.family == AF_INET &&
206 local->srx.transport_type == SOCK_DGRAM
207 ) {
208 list_for_each_entry(peer, &rxrpc_peers, link) {
209 if (atomic_read(&peer->usage) > 0 &&
210 peer->srx.transport_type == SOCK_DGRAM &&
211 peer->srx.transport.family == AF_INET &&
212 peer->srx.transport.sin.sin_port == port &&
213 peer->srx.transport.sin.sin_addr.s_addr == addr)
214 goto found_UDP_peer;
215 }
216
217 goto new_UDP_peer;
218 }
219
220 read_unlock_bh(&rxrpc_peer_lock);
221 _leave(" = -EAFNOSUPPORT");
222 return ERR_PTR(-EAFNOSUPPORT);
223
224 found_UDP_peer:
225 _net("Rx UDP DGRAM from peer %d", peer->debug_id);
226 atomic_inc(&peer->usage);
227 read_unlock_bh(&rxrpc_peer_lock);
228 _leave(" = %p", peer);
229 return peer;
230
231 new_UDP_peer:
232 _net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
233 read_unlock_bh(&rxrpc_peer_lock);
234 _leave(" = -EBUSY [new]");
235 return ERR_PTR(-EBUSY);
236 }
237
238 /*
239 * release a remote transport endpoint
240 */
rxrpc_put_peer(struct rxrpc_peer * peer)241 void rxrpc_put_peer(struct rxrpc_peer *peer)
242 {
243 _enter("%p{u=%d}", peer, atomic_read(&peer->usage));
244
245 ASSERTCMP(atomic_read(&peer->usage), >, 0);
246
247 if (likely(!atomic_dec_and_test(&peer->usage))) {
248 _leave(" [in use]");
249 return;
250 }
251
252 rxrpc_queue_work(&peer->destroyer);
253 _leave("");
254 }
255
256 /*
257 * destroy a remote transport endpoint
258 */
rxrpc_destroy_peer(struct work_struct * work)259 static void rxrpc_destroy_peer(struct work_struct *work)
260 {
261 struct rxrpc_peer *peer =
262 container_of(work, struct rxrpc_peer, destroyer);
263
264 _enter("%p{%d}", peer, atomic_read(&peer->usage));
265
266 write_lock_bh(&rxrpc_peer_lock);
267 list_del(&peer->link);
268 write_unlock_bh(&rxrpc_peer_lock);
269
270 _net("DESTROY PEER %d", peer->debug_id);
271 kfree(peer);
272
273 if (list_empty(&rxrpc_peers))
274 wake_up_all(&rxrpc_peer_wq);
275 _leave("");
276 }
277
278 /*
279 * preemptively destroy all the peer records from a transport endpoint rather
280 * than waiting for them to time out
281 */
rxrpc_destroy_all_peers(void)282 void __exit rxrpc_destroy_all_peers(void)
283 {
284 DECLARE_WAITQUEUE(myself,current);
285
286 _enter("");
287
288 /* we simply have to wait for them to go away */
289 if (!list_empty(&rxrpc_peers)) {
290 set_current_state(TASK_UNINTERRUPTIBLE);
291 add_wait_queue(&rxrpc_peer_wq, &myself);
292
293 while (!list_empty(&rxrpc_peers)) {
294 schedule();
295 set_current_state(TASK_UNINTERRUPTIBLE);
296 }
297
298 remove_wait_queue(&rxrpc_peer_wq, &myself);
299 set_current_state(TASK_RUNNING);
300 }
301
302 _leave("");
303 }
304