summaryrefslogtreecommitdiffstats
path: root/net/strparser/strparser.c
blob: 4ecfc10cbe6dea778037c8fc2bd8f5def4c289e9 (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
492
493
494
495
496
497
498
499
500
/*
 * Stream Parser
 *
 * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 */

#include <linux/bpf.h>
#include <linux/errno.h>
#include <linux/errqueue.h>
#include <linux/file.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/poll.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
#include <net/strparser.h>
#include <net/netns/generic.h>
#include <net/sock.h>
#include <net/tcp.h>

static struct workqueue_struct *strp_wq;

struct _strp_rx_msg {
	/* Internal cb structure. struct strp_rx_msg must be first for passing
	 * to upper layer.
	 */
	struct strp_rx_msg strp;
	int accum_len;
	int early_eaten;
};

static inline struct _strp_rx_msg *_strp_rx_msg(struct sk_buff *skb)
{
	return (struct _strp_rx_msg *)((void *)skb->cb +
		offsetof(struct qdisc_skb_cb, data));
}

/* Lower lock held */
static void strp_abort_rx_strp(struct strparser *strp, int err)
{
	struct sock *csk = strp->sk;

	/* Unrecoverable error in receive */

	del_timer(&strp->rx_msg_timer);

	if (strp->rx_stopped)
		return;

	strp->rx_stopped = 1;

	/* Report an error on the lower socket */
	csk->sk_err = err;
	csk->sk_error_report(csk);
}

static void strp_start_rx_timer(struct strparser *strp)
{
	if (strp->sk->sk_rcvtimeo)
		mod_timer(&strp->rx_msg_timer, strp->sk->sk_rcvtimeo);
}

/* Lower lock held */
static void strp_parser_err(struct strparser *strp, int err,
			    read_descriptor_t *desc)
{
	desc->error = err;
	kfree_skb(strp->rx_skb_head);
	strp->rx_skb_head = NULL;
	strp->cb.abort_parser(strp, err);
}

/* Lower socket lock held */
static int strp_tcp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
			 unsigned int orig_offset, size_t orig_len)
{
	struct strparser *strp = (struct strparser *)desc->arg.data;
	struct _strp_rx_msg *rxm;
	struct sk_buff *head, *skb;
	size_t eaten = 0, cand_len;
	ssize_t extra;
	int err;
	bool cloned_orig = false;

	if (strp->rx_paused)
		return 0;

	head = strp->rx_skb_head;
	if (head) {
		/* Message already in progress */

		rxm = _strp_rx_msg(head);
		if (unlikely(rxm->early_eaten)) {
			/* Already some number of bytes on the receive sock
			 * data saved in rx_skb_head, just indicate they
			 * are consumed.
			 */
			eaten = orig_len <= rxm->early_eaten ?
				orig_len : rxm->early_eaten;
			rxm->early_eaten -= eaten;

			return eaten;
		}

		if (unlikely(orig_offset)) {
			/* Getting data with a non-zero offset when a message is
			 * in progress is not expected. If it does happen, we
			 * need to clone and pull since we can't deal with
			 * offsets in the skbs for a message expect in the head.
			 */
			orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
			if (!orig_skb) {
				STRP_STATS_INCR(strp->stats.rx_mem_fail);
				desc->error = -ENOMEM;
				return 0;
			}
			if (!pskb_pull(orig_skb, orig_offset)) {
				STRP_STATS_INCR(strp->stats.rx_mem_fail);
				kfree_skb(orig_skb);
				desc->error = -ENOMEM;
				return 0;
			}
			cloned_orig = true;
			orig_offset = 0;
		}

		if (!strp->rx_skb_nextp) {
			/* We are going to append to the frags_list of head.
			 * Need to unshare the frag_list.
			 */
			err = skb_unclone(head, GFP_ATOMIC);
			if (err) {
				STRP_STATS_INCR(strp->stats.rx_mem_fail);
				desc->error = err;
				return 0;
			}

			if (unlikely(skb_shinfo(head)->frag_list)) {
				/* We can't append to an sk_buff that already
				 * has a frag_list. We create a new head, point
				 * the frag_list of that to the old head, and
				 * then are able to use the old head->next for
				 * appending to the message.
				 */
				if (WARN_ON(head->next)) {
					desc->error = -EINVAL;
					return 0;
				}

				skb = alloc_skb(0, GFP_ATOMIC);
				if (!skb) {
					STRP_STATS_INCR(strp->stats.rx_mem_fail);
					desc->error = -ENOMEM;
					return 0;
				}
				skb->len = head->len;
				skb->data_len = head->len;
				skb->truesize = head->truesize;
				*_strp_rx_msg(skb) = *_strp_rx_msg(head);
				strp->rx_skb_nextp = &head->next;
				skb_shinfo(skb)->frag_list = head;
				strp->rx_skb_head = skb;
				head = skb;
			} else {
				strp->rx_skb_nextp =
				    &skb_shinfo(head)->frag_list;
			}
		}
	}

	while (eaten < orig_len) {
		/* Always clone since we will consume something */
		skb = skb_clone(orig_skb, GFP_ATOMIC);
		if (!skb) {
			STRP_STATS_INCR(strp->stats.rx_mem_fail);
			desc->error = -ENOMEM;
			break;
		}

		cand_len = orig_len - eaten;

		head = strp->rx_skb_head;
		if (!head) {
			head = skb;
			strp->rx_skb_head = head;
			/* Will set rx_skb_nextp on next packet if needed */
			strp->rx_skb_nextp = NULL;
			rxm = _strp_rx_msg(head);
			memset(rxm, 0, sizeof(*rxm));
			rxm->strp.offset = orig_offset + eaten;
		} else {
			/* Unclone since we may be appending to an skb that we
			 * already share a frag_list with.
			 */
			err = skb_unclone(skb, GFP_ATOMIC);
			if (err) {
				STRP_STATS_INCR(strp->stats.rx_mem_fail);
				desc->error = err;
				break;
			}

			rxm = _strp_rx_msg(head);
			*strp->rx_skb_nextp = skb;
			strp->rx_skb_nextp = &skb->next;
			head->data_len += skb->len;
			head->len += skb->len;
			head->truesize += skb->truesize;
		}

		if (!rxm->strp.full_len) {
			ssize_t len;

			len = (*strp->cb.parse_msg)(strp, head);

			if (!len) {
				/* Need more header to determine length */
				if (!rxm->accum_len) {
					/* Start RX timer for new message */
					strp_start_rx_timer(strp);
				}
				rxm->accum_len += cand_len;
				eaten += cand_len;
				STRP_STATS_INCR(strp->stats.rx_need_more_hdr);
				WARN_ON(eaten != orig_len);
				break;
			} else if (len < 0) {
				if (len == -ESTRPIPE && rxm->accum_len) {
					len = -ENODATA;
					strp->rx_unrecov_intr = 1;
				} else {
					strp->rx_interrupted = 1;
				}
				strp_parser_err(strp, err, desc);
				break;
			} else if (len > strp->sk->sk_rcvbuf) {
				/* Message length exceeds maximum allowed */
				STRP_STATS_INCR(strp->stats.rx_msg_too_big);
				strp_parser_err(strp, -EMSGSIZE, desc);
				break;
			} else if (len <= (ssize_t)head->len -
					  skb->len - rxm->strp.offset) {
				/* Length must be into new skb (and also
				 * greater than zero)
				 */
				STRP_STATS_INCR(strp->stats.rx_bad_hdr_len);
				strp_parser_err(strp, -EPROTO, desc);
				break;
			}

			rxm->strp.full_len = len;
		}

		extra = (ssize_t)(rxm->accum_len + cand_len) -
			rxm->strp.full_len;

		if (extra < 0) {
			/* Message not complete yet. */
			if (rxm->strp.full_len - rxm->accum_len >
			    tcp_inq(strp->sk)) {
				/* Don't have the whole messages in the socket
				 * buffer. Set strp->rx_need_bytes to wait for
				 * the rest of the message. Also, set "early
				 * eaten" since we've already buffered the skb
				 * but don't consume yet per tcp_read_sock.
				 */

				if (!rxm->accum_len) {
					/* Start RX timer for new message */
					strp_start_rx_timer(strp);
				}

				strp->rx_need_bytes = rxm->strp.full_len -
						       rxm->accum_len;
				rxm->accum_len += cand_len;
				rxm->early_eaten = cand_len;
				STRP_STATS_ADD(strp->stats.rx_bytes, cand_len);
				desc->count = 0; /* Stop reading socket */
				break;
			}
			rxm->accum_len += cand_len;
			eaten += cand_len;
			WARN_ON(eaten != orig_len);
			break;
		}

		/* Positive extra indicates ore bytes than needed for the
		 * message
		 */

		WARN_ON(extra > cand_len);

		eaten += (cand_len - extra);

		/* Hurray, we have a new message! */
		del_timer(&strp->rx_msg_timer);
		strp->rx_skb_head = NULL;
		STRP_STATS_INCR(strp->stats.rx_msgs);

		/* Give skb to upper layer */
		strp->cb.rcv_msg(strp, head);

		if (unlikely(strp->rx_paused)) {
			/* Upper layer paused strp */
			break;
		}
	}

	if (cloned_orig)
		kfree_skb(orig_skb);

	STRP_STATS_ADD(strp->stats.rx_bytes, eaten);

	return eaten;
}

static int default_read_sock_done(struct strparser *strp, int err)
{
	return err;
}

/* Called with lock held on lower socket */
static int strp_tcp_read_sock(struct strparser *strp)
{
	read_descriptor_t desc;

	desc.arg.data = strp;
	desc.error = 0;
	desc.count = 1; /* give more than one skb per call */

	/* sk should be locked here, so okay to do tcp_read_sock */
	tcp_read_sock(strp->sk, &desc, strp_tcp_recv);

	desc.error = strp->cb.read_sock_done(strp, desc.error);

	return desc.error;
}

/* Lower sock lock held */
void strp_tcp_data_ready(struct strparser *strp)
{
	struct sock *csk = strp->sk;

	if (unlikely(strp->rx_stopped))
		return;

	/* This check is needed to synchronize with do_strp_rx_work.
	 * do_strp_rx_work acquires a process lock (lock_sock) whereas
	 * the lock held here is bh_lock_sock. The two locks can be
	 * held by different threads at the same time, but bh_lock_sock
	 * allows a thread in BH context to safely check if the process
	 * lock is held. In this case, if the lock is held, queue work.
	 */
	if (sock_owned_by_user(csk)) {
		queue_work(strp_wq, &strp->rx_work);
		return;
	}

	if (strp->rx_paused)
		return;

	if (strp->rx_need_bytes) {
		if (tcp_inq(csk) >= strp->rx_need_bytes)
			strp->rx_need_bytes = 0;
		else
			return;
	}

	if (strp_tcp_read_sock(strp) == -ENOMEM)
		queue_work(strp_wq, &strp->rx_work);
}
EXPORT_SYMBOL_GPL(strp_tcp_data_ready);

static void do_strp_rx_work(struct strparser *strp)
{
	read_descriptor_t rd_desc;
	struct sock *csk = strp->sk;

	/* We need the read lock to synchronize with strp_tcp_data_ready. We
	 * need the socket lock for calling tcp_read_sock.
	 */
	lock_sock(csk);

	if (unlikely(strp->rx_stopped))
		goto out;

	if (strp->rx_paused)
		goto out;

	rd_desc.arg.data = strp;

	if (strp_tcp_read_sock(strp) == -ENOMEM)
		queue_work(strp_wq, &strp->rx_work);

out:
	release_sock(csk);
}

static void strp_rx_work(struct work_struct *w)
{
	do_strp_rx_work(container_of(w, struct strparser, rx_work));
}

static void strp_rx_msg_timeout(unsigned long arg)
{
	struct strparser *strp = (struct strparser *)arg;

	/* Message assembly timed out */
	STRP_STATS_INCR(strp->stats.rx_msg_timeouts);
	lock_sock(strp->sk);
	strp->cb.abort_parser(strp, ETIMEDOUT);
	release_sock(strp->sk);
}

int strp_init(struct strparser *strp, struct sock *csk,
	      struct strp_callbacks *cb)
{
	if (!cb || !cb->rcv_msg || !cb->parse_msg)
		return -EINVAL;

	memset(strp, 0, sizeof(*strp));

	strp->sk = csk;

	setup_timer(&strp->rx_msg_timer, strp_rx_msg_timeout,
		    (unsigned long)strp);

	INIT_WORK(&strp->rx_work, strp_rx_work);

	strp->cb.rcv_msg = cb->rcv_msg;
	strp->cb.parse_msg = cb->parse_msg;
	strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
	strp->cb.abort_parser = cb->abort_parser ? : strp_abort_rx_strp;

	return 0;
}
EXPORT_SYMBOL_GPL(strp_init);

void strp_unpause(struct strparser *strp)
{
	strp->rx_paused = 0;

	/* Sync setting rx_paused with RX work */
	smp_mb();

	queue_work(strp_wq, &strp->rx_work);
}
EXPORT_SYMBOL_GPL(strp_unpause);

/* strp must already be stopped so that strp_tcp_recv will no longer be called.
 * Note that strp_done is not called with the lower socket held.
 */
void strp_done(struct strparser *strp)
{
	WARN_ON(!strp->rx_stopped);

	del_timer_sync(&strp->rx_msg_timer);
	cancel_work_sync(&strp->rx_work);

	if (strp->rx_skb_head) {
		kfree_skb(strp->rx_skb_head);
		strp->rx_skb_head = NULL;
	}
}
EXPORT_SYMBOL_GPL(strp_done);

void strp_stop(struct strparser *strp)
{
	strp->rx_stopped = 1;
}
EXPORT_SYMBOL_GPL(strp_stop);

void strp_check_rcv(struct strparser *strp)
{
	queue_work(strp_wq, &strp->rx_work);
}
EXPORT_SYMBOL_GPL(strp_check_rcv);

static int __init strp_mod_init(void)
{
	strp_wq = create_singlethread_workqueue("kstrp");

	return 0;
}

static void __exit strp_mod_exit(void)
{
}
module_init(strp_mod_init);
module_exit(strp_mod_exit);
MODULE_LICENSE("GPL");