summaryrefslogtreecommitdiff
path: root/net/rxrpc/call_accept.c
blob: 1ae90fb979362b8a585b5a5f984de91ba871220e (plain)
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
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
// SPDX-License-Identifier: GPL-2.0-or-later
/* incoming call handling
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

static void rxrpc_dummy_notify(struct sock *sk, struct rxrpc_call *call,
			       unsigned long user_call_ID)
{
}

/*
 * Preallocate a single service call, connection and peer and, if possible,
 * give them a user ID and attach the user's side of the ID to them.
 */
static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
				      struct rxrpc_backlog *b,
				      rxrpc_notify_rx_t notify_rx,
				      rxrpc_user_attach_call_t user_attach_call,
				      unsigned long user_call_ID, gfp_t gfp,
				      unsigned int debug_id)
{
	const void *here = __builtin_return_address(0);
	struct rxrpc_call *call, *xcall;
	struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
	struct rb_node *parent, **pp;
	int max, tmp;
	unsigned int size = RXRPC_BACKLOG_MAX;
	unsigned int head, tail, call_head, call_tail;

	max = rx->sk.sk_max_ack_backlog;
	tmp = rx->sk.sk_ack_backlog;
	if (tmp >= max) {
		_leave(" = -ENOBUFS [full %u]", max);
		return -ENOBUFS;
	}
	max -= tmp;

	/* We don't need more conns and peers than we have calls, but on the
	 * other hand, we shouldn't ever use more peers than conns or conns
	 * than calls.
	 */
	call_head = b->call_backlog_head;
	call_tail = READ_ONCE(b->call_backlog_tail);
	tmp = CIRC_CNT(call_head, call_tail, size);
	if (tmp >= max) {
		_leave(" = -ENOBUFS [enough %u]", tmp);
		return -ENOBUFS;
	}
	max = tmp + 1;

	head = b->peer_backlog_head;
	tail = READ_ONCE(b->peer_backlog_tail);
	if (CIRC_CNT(head, tail, size) < max) {
		struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
		if (!peer)
			return -ENOMEM;
		b->peer_backlog[head] = peer;
		smp_store_release(&b->peer_backlog_head,
				  (head + 1) & (size - 1));
	}

	head = b->conn_backlog_head;
	tail = READ_ONCE(b->conn_backlog_tail);
	if (CIRC_CNT(head, tail, size) < max) {
		struct rxrpc_connection *conn;

		conn = rxrpc_prealloc_service_connection(rxnet, gfp);
		if (!conn)
			return -ENOMEM;
		b->conn_backlog[head] = conn;
		smp_store_release(&b->conn_backlog_head,
				  (head + 1) & (size - 1));

		trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_service,
				 atomic_read(&conn->usage), here);
	}

	/* Now it gets complicated, because calls get registered with the
	 * socket here, with a user ID preassigned by the user.
	 */
	call = rxrpc_alloc_call(rx, gfp, debug_id);
	if (!call)
		return -ENOMEM;
	call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
	call->state = RXRPC_CALL_SERVER_PREALLOC;

	trace_rxrpc_call(call->debug_id, rxrpc_call_new_service,
			 atomic_read(&call->usage),
			 here, (const void *)user_call_ID);

	write_lock(&rx->call_lock);

	/* Check the user ID isn't already in use */
	pp = &rx->calls.rb_node;
	parent = NULL;
	while (*pp) {
		parent = *pp;
		xcall = rb_entry(parent, struct rxrpc_call, sock_node);
		if (user_call_ID < xcall->user_call_ID)
			pp = &(*pp)->rb_left;
		else if (user_call_ID > xcall->user_call_ID)
			pp = &(*pp)->rb_right;
		else
			goto id_in_use;
	}

	call->user_call_ID = user_call_ID;
	call->notify_rx = notify_rx;
	if (user_attach_call) {
		rxrpc_get_call(call, rxrpc_call_got_kernel);
		user_attach_call(call, user_call_ID);
	}

	rxrpc_get_call(call, rxrpc_call_got_userid);
	rb_link_node(&call->sock_node, parent, pp);
	rb_insert_color(&call->sock_node, &rx->calls);
	set_bit(RXRPC_CALL_HAS_USERID, &call->flags);

	list_add(&call->sock_link, &rx->sock_calls);

	write_unlock(&rx->call_lock);

	rxnet = call->rxnet;
	write_lock(&rxnet->call_lock);
	list_add_tail(&call->link, &rxnet->calls);
	write_unlock(&rxnet->call_lock);

	b->call_backlog[call_head] = call;
	smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
	_leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
	return 0;

id_in_use:
	write_unlock(&rx->call_lock);
	rxrpc_cleanup_call(call);
	_leave(" = -EBADSLT");
	return -EBADSLT;
}

/*
 * Allocate the preallocation buffers for incoming service calls.  These must
 * be charged manually.
 */
int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
{
	struct rxrpc_backlog *b = rx->backlog;

	if (!b) {
		b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
		if (!b)
			return -ENOMEM;
		rx->backlog = b;
	}

	return 0;
}

/*
 * Discard the preallocation on a service.
 */
void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
{
	struct rxrpc_backlog *b = rx->backlog;
	struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
	unsigned int size = RXRPC_BACKLOG_MAX, head, tail;

	if (!b)
		return;
	rx->backlog = NULL;

	/* Make sure that there aren't any incoming calls in progress before we
	 * clear the preallocation buffers.
	 */
	spin_lock_bh(&rx->incoming_lock);
	spin_unlock_bh(&rx->incoming_lock);

	head = b->peer_backlog_head;
	tail = b->peer_backlog_tail;
	while (CIRC_CNT(head, tail, size) > 0) {
		struct rxrpc_peer *peer = b->peer_backlog[tail];
		rxrpc_put_local(peer->local);
		kfree(peer);
		tail = (tail + 1) & (size - 1);
	}

	head = b->conn_backlog_head;
	tail = b->conn_backlog_tail;
	while (CIRC_CNT(head, tail, size) > 0) {
		struct rxrpc_connection *conn = b->conn_backlog[tail];
		write_lock(&rxnet->conn_lock);
		list_del(&conn->link);
		list_del(&conn->proc_link);
		write_unlock(&rxnet->conn_lock);
		kfree(conn);
		if (atomic_dec_and_test(&rxnet->nr_conns))
			wake_up_var(&rxnet->nr_conns);
		tail = (tail + 1) & (size - 1);
	}

	head = b->call_backlog_head;
	tail = b->call_backlog_tail;
	while (CIRC_CNT(head, tail, size) > 0) {
		struct rxrpc_call *call = b->call_backlog[tail];
		rcu_assign_pointer(call->socket, rx);
		if (rx->discard_new_call) {
			_debug("discard %lx", call->user_call_ID);
			rx->discard_new_call(call, call->user_call_ID);
			if (call->notify_rx)
				call->notify_rx = rxrpc_dummy_notify;
			rxrpc_put_call(call, rxrpc_call_put_kernel);
		}
		rxrpc_call_completed(call);
		rxrpc_release_call(rx, call);
		rxrpc_put_call(call, rxrpc_call_put);
		tail = (tail + 1) & (size - 1);
	}

	kfree(b);
}

/*
 * Ping the other end to fill our RTT cache and to retrieve the rwind
 * and MTU parameters.
 */
static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
{
	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
	ktime_t now = skb->tstamp;

	if (call->peer->rtt_count < 3 ||
	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
		rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
				  true, true,
				  rxrpc_propose_ack_ping_for_params);
}

/*
 * Allocate a new incoming call from the prealloc pool, along with a connection
 * and a peer as necessary.
 */
static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
						    struct rxrpc_local *local,
						    struct rxrpc_peer *peer,
						    struct rxrpc_connection *conn,
						    const struct rxrpc_security *sec,
						    struct sk_buff *skb)
{
	struct rxrpc_backlog *b = rx->backlog;
	struct rxrpc_call *call;
	unsigned short call_head, conn_head, peer_head;
	unsigned short call_tail, conn_tail, peer_tail;
	unsigned short call_count, conn_count;

	/* #calls >= #conns >= #peers must hold true. */
	call_head = smp_load_acquire(&b->call_backlog_head);
	call_tail = b->call_backlog_tail;
	call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
	conn_head = smp_load_acquire(&b->conn_backlog_head);
	conn_tail = b->conn_backlog_tail;
	conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
	ASSERTCMP(conn_count, >=, call_count);
	peer_head = smp_load_acquire(&b->peer_backlog_head);
	peer_tail = b->peer_backlog_tail;
	ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
		  conn_count);

	if (call_count == 0)
		return NULL;

	if (!conn) {
		if (peer && !rxrpc_get_peer_maybe(peer))
			peer = NULL;
		if (!peer) {
			peer = b->peer_backlog[peer_tail];
			if (rxrpc_extract_addr_from_skb(&peer->srx, skb) < 0)
				return NULL;
			b->peer_backlog[peer_tail] = NULL;
			smp_store_release(&b->peer_backlog_tail,
					  (peer_tail + 1) &
					  (RXRPC_BACKLOG_MAX - 1));

			rxrpc_new_incoming_peer(rx, local, peer);
		}

		/* Now allocate and set up the connection */
		conn = b->conn_backlog[conn_tail];
		b->conn_backlog[conn_tail] = NULL;
		smp_store_release(&b->conn_backlog_tail,
				  (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
		conn->params.local = rxrpc_get_local(local);
		conn->params.peer = peer;
		rxrpc_see_connection(conn);
		rxrpc_new_incoming_connection(rx, conn, sec, skb);
	} else {
		rxrpc_get_connection(conn);
	}

	/* And now we can allocate and set up a new call */
	call = b->call_backlog[call_tail];
	b->call_backlog[call_tail] = NULL;
	smp_store_release(&b->call_backlog_tail,
			  (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));

	rxrpc_see_call(call);
	call->conn = conn;
	call->security = conn->security;
	call->security_ix = conn->security_ix;
	call->peer = rxrpc_get_peer(conn->params.peer);
	call->cong_cwnd = call->peer->cong_cwnd;
	return call;
}

/*
 * Set up a new incoming call.  Called in BH context with the RCU read lock
 * held.
 *
 * If this is for a kernel service, when we allocate the call, it will have
 * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
 * retainer ref obtained from the backlog buffer.  Prealloc calls for userspace
 * services only have the ref from the backlog buffer.  We want to pass this
 * ref to non-BH context to dispose of.
 *
 * If we want to report an error, we mark the skb with the packet type and
 * abort code and return NULL.
 *
 * The call is returned with the user access mutex held.
 */
struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
					   struct rxrpc_sock *rx,
					   struct sk_buff *skb)
{
	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
	const struct rxrpc_security *sec = NULL;
	struct rxrpc_connection *conn;
	struct rxrpc_peer *peer = NULL;
	struct rxrpc_call *call = NULL;

	_enter("");

	spin_lock(&rx->incoming_lock);
	if (rx->sk.sk_state == RXRPC_SERVER_LISTEN_DISABLED ||
	    rx->sk.sk_state == RXRPC_CLOSE) {
		trace_rxrpc_abort(0, "CLS", sp->hdr.cid, sp->hdr.callNumber,
				  sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
		skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
		skb->priority = RX_INVALID_OPERATION;
		goto no_call;
	}

	/* The peer, connection and call may all have sprung into existence due
	 * to a duplicate packet being handled on another CPU in parallel, so
	 * we have to recheck the routing.  However, we're now holding
	 * rx->incoming_lock, so the values should remain stable.
	 */
	conn = rxrpc_find_connection_rcu(local, skb, &peer);

	if (!conn) {
		sec = rxrpc_get_incoming_security(rx, skb);
		if (!sec)
			goto no_call;
	}

	call = rxrpc_alloc_incoming_call(rx, local, peer, conn, sec, skb);
	if (!call) {
		skb->mark = RXRPC_SKB_MARK_REJECT_BUSY;
		goto no_call;
	}

	trace_rxrpc_receive(call, rxrpc_receive_incoming,
			    sp->hdr.serial, sp->hdr.seq);

	/* Make the call live. */
	rxrpc_incoming_call(rx, call, skb);
	conn = call->conn;

	if (rx->notify_new_call)
		rx->notify_new_call(&rx->sk, call, call->user_call_ID);

	spin_lock(&conn->state_lock);
	switch (conn->state) {
	case RXRPC_CONN_SERVICE_UNSECURED:
		conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
		set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
		rxrpc_queue_conn(call->conn);
		break;

	case RXRPC_CONN_SERVICE:
		write_lock(&call->state_lock);
		if (call->state < RXRPC_CALL_COMPLETE)
			call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
		write_unlock(&call->state_lock);
		break;

	case RXRPC_CONN_REMOTELY_ABORTED:
		rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
					  conn->abort_code, conn->error);
		break;
	case RXRPC_CONN_LOCALLY_ABORTED:
		rxrpc_abort_call("CON", call, sp->hdr.seq,
				 conn->abort_code, conn->error);
		break;
	default:
		BUG();
	}
	spin_unlock(&conn->state_lock);
	spin_unlock(&rx->incoming_lock);

	rxrpc_send_ping(call, skb);

	/* We have to discard the prealloc queue's ref here and rely on a
	 * combination of the RCU read lock and refs held either by the socket
	 * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
	 * service to prevent the call from being deallocated too early.
	 */
	rxrpc_put_call(call, rxrpc_call_put);

	_leave(" = %p{%d}", call, call->debug_id);
	return call;

no_call:
	spin_unlock(&rx->incoming_lock);
	_leave(" = NULL [%u]", skb->mark);
	return NULL;
}

/*
 * Charge up socket with preallocated calls, attaching user call IDs.
 */
int rxrpc_user_charge_accept(struct rxrpc_sock *rx, unsigned long user_call_ID)
{
	struct rxrpc_backlog *b = rx->backlog;

	if (rx->sk.sk_state == RXRPC_CLOSE)
		return -ESHUTDOWN;

	return rxrpc_service_prealloc_one(rx, b, NULL, NULL, user_call_ID,
					  GFP_KERNEL,
					  atomic_inc_return(&rxrpc_debug_id));
}

/*
 * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
 * @sock: The socket on which to preallocate
 * @notify_rx: Event notification function for the call
 * @user_attach_call: Func to attach call to user_call_ID
 * @user_call_ID: The tag to attach to the preallocated call
 * @gfp: The allocation conditions.
 * @debug_id: The tracing debug ID.
 *
 * Charge up the socket with preallocated calls, each with a user ID.  A
 * function should be provided to effect the attachment from the user's side.
 * The user is given a ref to hold on the call.
 *
 * Note that the call may be come connected before this function returns.
 */
int rxrpc_kernel_charge_accept(struct socket *sock,
			       rxrpc_notify_rx_t notify_rx,
			       rxrpc_user_attach_call_t user_attach_call,
			       unsigned long user_call_ID, gfp_t gfp,
			       unsigned int debug_id)
{
	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
	struct rxrpc_backlog *b = rx->backlog;

	if (sock->sk->sk_state == RXRPC_CLOSE)
		return -ESHUTDOWN;

	return rxrpc_service_prealloc_one(rx, b, notify_rx,
					  user_attach_call, user_call_ID,
					  gfp, debug_id);
}
EXPORT_SYMBOL(rxrpc_kernel_charge_accept);