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TOMOYO Linux Cross Reference
Linux/net/rxrpc/ar-peer.c

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  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  */
 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  */
 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  */
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  */
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  */
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  */
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  */
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 

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