aboutsummaryrefslogtreecommitdiffstats
path: root/net/rxrpc/ar-peer.c
blob: ce08b78647ce85a168ccce87ade906b9b13c3e0c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
/* RxRPC remote transport endpoint management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/icmp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <net/ip.h>
#include <net/route.h>
#include "ar-internal.h"

static LIST_HEAD(rxrpc_peers);
static DEFINE_RWLOCK(rxrpc_peer_lock);
static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);

static void rxrpc_destroy_peer(struct work_struct *work);

/*
 * assess the MTU size for the network interface through which this peer is
 * reached
 */
static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
{
	struct rtable *rt;
	struct flowi fl;
	int ret;

	peer->if_mtu = 1500;

	memset(&fl, 0, sizeof(fl));

	switch (peer->srx.transport.family) {
	case AF_INET:
		fl.oif = 0;
		fl.proto = IPPROTO_UDP,
		fl.nl_u.ip4_u.saddr = 0;
		fl.nl_u.ip4_u.daddr = peer->srx.transport.sin.sin_addr.s_addr;
		fl.nl_u.ip4_u.tos = 0;
		/* assume AFS.CM talking to AFS.FS */
		fl.uli_u.ports.sport = htons(7001);
		fl.uli_u.ports.dport = htons(7000);
		break;
	default:
		BUG();
	}

	ret = ip_route_output_key(&rt, &fl);
	if (ret < 0) {
		kleave(" [route err %d]", ret);
		return;
	}

	peer->if_mtu = dst_mtu(&rt->u.dst);
	dst_release(&rt->u.dst);

	kleave(" [if_mtu %u]", peer->if_mtu);
}

/*
 * allocate a new peer
 */
static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
					   gfp_t gfp)
{
	struct rxrpc_peer *peer;

	_enter("");

	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
	if (peer) {
		INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
		INIT_LIST_HEAD(&peer->link);
		INIT_LIST_HEAD(&peer->error_targets);
		spin_lock_init(&peer->lock);
		atomic_set(&peer->usage, 1);
		peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
		memcpy(&peer->srx, srx, sizeof(*srx));

		rxrpc_assess_MTU_size(peer);
		peer->mtu = peer->if_mtu;

		if (srx->transport.family == AF_INET) {
			peer->hdrsize = sizeof(struct iphdr);
			switch (srx->transport_type) {
			case SOCK_DGRAM:
				peer->hdrsize += sizeof(struct udphdr);
				break;
			default:
				BUG();
				break;
			}
		} else {
			BUG();
		}

		peer->hdrsize += sizeof(struct rxrpc_header);
		peer->maxdata = peer->mtu - peer->hdrsize;
	}

	_leave(" = %p", peer);
	return peer;
}

/*
 * obtain a remote transport endpoint for the specified address
 */
struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
{
	struct rxrpc_peer *peer, *candidate;
	const char *new = "old";
	int usage;

	_enter("{%d,%d,%u.%u.%u.%u+%hu}",
	       srx->transport_type,
	       srx->transport_len,
	       NIPQUAD(srx->transport.sin.sin_addr),
	       ntohs(srx->transport.sin.sin_port));

	/* search the peer list first */
	read_lock_bh(&rxrpc_peer_lock);
	list_for_each_entry(peer, &rxrpc_peers, link) {
		_debug("check PEER %d { u=%d t=%d l=%d }",
		       peer->debug_id,
		       atomic_read(&peer->usage),
		       peer->srx.transport_type,
		       peer->srx.transport_len);

		if (atomic_read(&peer->usage) > 0 &&
		    peer->srx.transport_type == srx->transport_type &&
		    peer->srx.transport_len == srx->transport_len &&
		    memcmp(&peer->srx.transport,
			   &srx->transport,
			   srx->transport_len) == 0)
			goto found_extant_peer;
	}
	read_unlock_bh(&rxrpc_peer_lock);

	/* not yet present - create a candidate for a new record and then
	 * redo the search */
	candidate = rxrpc_alloc_peer(srx, gfp);
	if (!candidate) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	write_lock_bh(&rxrpc_peer_lock);

	list_for_each_entry(peer, &rxrpc_peers, link) {
		if (atomic_read(&peer->usage) > 0 &&
		    peer->srx.transport_type == srx->transport_type &&
		    peer->srx.transport_len == srx->transport_len &&
		    memcmp(&peer->srx.transport,
			   &srx->transport,
			   srx->transport_len) == 0)
			goto found_extant_second;
	}

	/* we can now add the new candidate to the list */
	peer = candidate;
	candidate = NULL;

	list_add_tail(&peer->link, &rxrpc_peers);
	write_unlock_bh(&rxrpc_peer_lock);
	new = "new";

success:
	_net("PEER %s %d {%d,%u,%u.%u.%u.%u+%hu}",
	     new,
	     peer->debug_id,
	     peer->srx.transport_type,
	     peer->srx.transport.family,
	     NIPQUAD(peer->srx.transport.sin.sin_addr),
	     ntohs(peer->srx.transport.sin.sin_port));

	_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
	return peer;

	/* we found the peer in the list immediately */
found_extant_peer:
	usage = atomic_inc_return(&peer->usage);
	read_unlock_bh(&rxrpc_peer_lock);
	goto success;

	/* we found the peer on the second time through the list */
found_extant_second:
	usage = atomic_inc_return(&peer->usage);
	write_unlock_bh(&rxrpc_peer_lock);
	kfree(candidate);
	goto success;
}

/*
 * find the peer associated with a packet
 */
struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
				   __be32 addr, __be16 port)
{
	struct rxrpc_peer *peer;

	_enter("");

	/* search the peer list */
	read_lock_bh(&rxrpc_peer_lock);

	if (local->srx.transport.family == AF_INET &&
	    local->srx.transport_type == SOCK_DGRAM
	    ) {
		list_for_each_entry(peer, &rxrpc_peers, link) {
			if (atomic_read(&peer->usage) > 0 &&
			    peer->srx.transport_type == SOCK_DGRAM &&
			    peer->srx.transport.family == AF_INET &&
			    peer->srx.transport.sin.sin_port == port &&
			    peer->srx.transport.sin.sin_addr.s_addr == addr)
				goto found_UDP_peer;
		}

		goto new_UDP_peer;
	}

	read_unlock_bh(&rxrpc_peer_lock);
	_leave(" = -EAFNOSUPPORT");
	return ERR_PTR(-EAFNOSUPPORT);

found_UDP_peer:
	_net("Rx UDP DGRAM from peer %d", peer->debug_id);
	atomic_inc(&peer->usage);
	read_unlock_bh(&rxrpc_peer_lock);
	_leave(" = %p", peer);
	return peer;

new_UDP_peer:
	_net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
	read_unlock_bh(&rxrpc_peer_lock);
	_leave(" = -EBUSY [new]");
	return ERR_PTR(-EBUSY);
}

/*
 * release a remote transport endpoint
 */
void rxrpc_put_peer(struct rxrpc_peer *peer)
{
	_enter("%p{u=%d}", peer, atomic_read(&peer->usage));

	ASSERTCMP(atomic_read(&peer->usage), >, 0);

	if (likely(!atomic_dec_and_test(&peer->usage))) {
		_leave(" [in use]");
		return;
	}

	rxrpc_queue_work(&peer->destroyer);
	_leave("");
}

/*
 * destroy a remote transport endpoint
 */
static void rxrpc_destroy_peer(struct work_struct *work)
{
	struct rxrpc_peer *peer =
		container_of(work, struct rxrpc_peer, destroyer);

	_enter("%p{%d}", peer, atomic_read(&peer->usage));

	write_lock_bh(&rxrpc_peer_lock);
	list_del(&peer->link);
	write_unlock_bh(&rxrpc_peer_lock);

	_net("DESTROY PEER %d", peer->debug_id);
	kfree(peer);

	if (list_empty(&rxrpc_peers))
		wake_up_all(&rxrpc_peer_wq);
	_leave("");
}

/*
 * preemptively destroy all the peer records from a transport endpoint rather
 * than waiting for them to time out
 */
void __exit rxrpc_destroy_all_peers(void)
{
	DECLARE_WAITQUEUE(myself,current);

	_enter("");

	/* we simply have to wait for them to go away */
	if (!list_empty(&rxrpc_peers)) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&rxrpc_peer_wq, &myself);

		while (!list_empty(&rxrpc_peers)) {
			schedule();
			set_current_state(TASK_UNINTERRUPTIBLE);
		}

		remove_wait_queue(&rxrpc_peer_wq, &myself);
		set_current_state(TASK_RUNNING);
	}

	_leave("");
}