aboutsummaryrefslogtreecommitdiffstats
path: root/net/xfrm/xfrm_replay.c
blob: f218385950ca06a3a8b6830c51c29ac370ca2ea0 (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
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
/*
 * xfrm_replay.c - xfrm replay detection, derived from xfrm_state.c.
 *
 * Copyright (C) 2010 secunet Security Networks AG
 * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <net/xfrm.h>

u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq)
{
	u32 seq, seq_hi, bottom;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;

	if (!(x->props.flags & XFRM_STATE_ESN))
		return 0;

	seq = ntohl(net_seq);
	seq_hi = replay_esn->seq_hi;
	bottom = replay_esn->seq - replay_esn->replay_window + 1;

	if (likely(replay_esn->seq >= replay_esn->replay_window - 1)) {
		/* A. same subspace */
		if (unlikely(seq < bottom))
			seq_hi++;
	} else {
		/* B. window spans two subspaces */
		if (unlikely(seq >= bottom))
			seq_hi--;
	}

	return seq_hi;
}

static void xfrm_replay_notify(struct xfrm_state *x, int event)
{
	struct km_event c;
	/* we send notify messages in case
	 *  1. we updated on of the sequence numbers, and the seqno difference
	 *     is at least x->replay_maxdiff, in this case we also update the
	 *     timeout of our timer function
	 *  2. if x->replay_maxage has elapsed since last update,
	 *     and there were changes
	 *
	 *  The state structure must be locked!
	 */

	switch (event) {
	case XFRM_REPLAY_UPDATE:
		if (x->replay_maxdiff &&
		    (x->replay.seq - x->preplay.seq < x->replay_maxdiff) &&
		    (x->replay.oseq - x->preplay.oseq < x->replay_maxdiff)) {
			if (x->xflags & XFRM_TIME_DEFER)
				event = XFRM_REPLAY_TIMEOUT;
			else
				return;
		}

		break;

	case XFRM_REPLAY_TIMEOUT:
		if (memcmp(&x->replay, &x->preplay,
			   sizeof(struct xfrm_replay_state)) == 0) {
			x->xflags |= XFRM_TIME_DEFER;
			return;
		}

		break;
	}

	memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state));
	c.event = XFRM_MSG_NEWAE;
	c.data.aevent = event;
	km_state_notify(x, &c);

	if (x->replay_maxage &&
	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
		x->xflags &= ~XFRM_TIME_DEFER;
}

static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
{
	int err = 0;
	struct net *net = xs_net(x);

	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
		XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
		if (unlikely(x->replay.oseq == 0)) {
			x->replay.oseq--;
			xfrm_audit_state_replay_overflow(x, skb);
			err = -EOVERFLOW;

			return err;
		}
		if (xfrm_aevent_is_on(net))
			x->repl->notify(x, XFRM_REPLAY_UPDATE);
	}

	return err;
}

static int xfrm_replay_check(struct xfrm_state *x,
		      struct sk_buff *skb, __be32 net_seq)
{
	u32 diff;
	u32 seq = ntohl(net_seq);

	if (!x->props.replay_window)
		return 0;

	if (unlikely(seq == 0))
		goto err;

	if (likely(seq > x->replay.seq))
		return 0;

	diff = x->replay.seq - seq;
	if (diff >= min_t(unsigned int, x->props.replay_window,
			  sizeof(x->replay.bitmap) * 8)) {
		x->stats.replay_window++;
		goto err;
	}

	if (x->replay.bitmap & (1U << diff)) {
		x->stats.replay++;
		goto err;
	}
	return 0;

err:
	xfrm_audit_state_replay(x, skb, net_seq);
	return -EINVAL;
}

static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
{
	u32 diff;
	u32 seq = ntohl(net_seq);

	if (!x->props.replay_window)
		return;

	if (seq > x->replay.seq) {
		diff = seq - x->replay.seq;
		if (diff < x->props.replay_window)
			x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
		else
			x->replay.bitmap = 1;
		x->replay.seq = seq;
	} else {
		diff = x->replay.seq - seq;
		x->replay.bitmap |= (1U << diff);
	}

	if (xfrm_aevent_is_on(xs_net(x)))
		xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
}

static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
{
	int err = 0;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
	struct net *net = xs_net(x);

	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
		if (unlikely(replay_esn->oseq == 0)) {
			replay_esn->oseq--;
			xfrm_audit_state_replay_overflow(x, skb);
			err = -EOVERFLOW;

			return err;
		}
		if (xfrm_aevent_is_on(net))
			x->repl->notify(x, XFRM_REPLAY_UPDATE);
	}

	return err;
}

static int xfrm_replay_check_bmp(struct xfrm_state *x,
				 struct sk_buff *skb, __be32 net_seq)
{
	unsigned int bitnr, nr;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
	u32 pos;
	u32 seq = ntohl(net_seq);
	u32 diff =  replay_esn->seq - seq;

	if (!replay_esn->replay_window)
		return 0;

	pos = (replay_esn->seq - 1) % replay_esn->replay_window;

	if (unlikely(seq == 0))
		goto err;

	if (likely(seq > replay_esn->seq))
		return 0;

	if (diff >= replay_esn->replay_window) {
		x->stats.replay_window++;
		goto err;
	}

	if (pos >= diff) {
		bitnr = (pos - diff) % replay_esn->replay_window;
		nr = bitnr >> 5;
		bitnr = bitnr & 0x1F;
		if (replay_esn->bmp[nr] & (1U << bitnr))
			goto err_replay;
	} else {
		bitnr = replay_esn->replay_window - (diff - pos);
		nr = bitnr >> 5;
		bitnr = bitnr & 0x1F;
		if (replay_esn->bmp[nr] & (1U << bitnr))
			goto err_replay;
	}
	return 0;

err_replay:
	x->stats.replay++;
err:
	xfrm_audit_state_replay(x, skb, net_seq);
	return -EINVAL;
}

static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
{
	unsigned int bitnr, nr, i;
	u32 diff;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
	u32 seq = ntohl(net_seq);
	u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;

	if (!replay_esn->replay_window)
		return;

	if (seq > replay_esn->seq) {
		diff = seq - replay_esn->seq;

		if (diff < replay_esn->replay_window) {
			for (i = 1; i < diff; i++) {
				bitnr = (pos + i) % replay_esn->replay_window;
				nr = bitnr >> 5;
				bitnr = bitnr & 0x1F;
				replay_esn->bmp[nr] &=  ~(1U << bitnr);
			}

			bitnr = (pos + diff) % replay_esn->replay_window;
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		} else {
			nr = replay_esn->replay_window >> 5;
			for (i = 0; i <= nr; i++)
				replay_esn->bmp[i] = 0;

			bitnr = (pos + diff) % replay_esn->replay_window;
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		}

		replay_esn->seq = seq;
	} else {
		diff = replay_esn->seq - seq;

		if (pos >= diff) {
			bitnr = (pos - diff) % replay_esn->replay_window;
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		} else {
			bitnr = replay_esn->replay_window - (diff - pos);
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		}
	}

	if (xfrm_aevent_is_on(xs_net(x)))
		xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
}

static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
{
	struct km_event c;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;

	/* we send notify messages in case
	 *  1. we updated on of the sequence numbers, and the seqno difference
	 *     is at least x->replay_maxdiff, in this case we also update the
	 *     timeout of our timer function
	 *  2. if x->replay_maxage has elapsed since last update,
	 *     and there were changes
	 *
	 *  The state structure must be locked!
	 */

	switch (event) {
	case XFRM_REPLAY_UPDATE:
		if (x->replay_maxdiff &&
		    (replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
		    (replay_esn->oseq - preplay_esn->oseq < x->replay_maxdiff)) {
			if (x->xflags & XFRM_TIME_DEFER)
				event = XFRM_REPLAY_TIMEOUT;
			else
				return;
		}

		break;

	case XFRM_REPLAY_TIMEOUT:
		if (memcmp(x->replay_esn, x->preplay_esn,
			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
			x->xflags |= XFRM_TIME_DEFER;
			return;
		}

		break;
	}

	memcpy(x->preplay_esn, x->replay_esn,
	       xfrm_replay_state_esn_len(replay_esn));
	c.event = XFRM_MSG_NEWAE;
	c.data.aevent = event;
	km_state_notify(x, &c);

	if (x->replay_maxage &&
	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
		x->xflags &= ~XFRM_TIME_DEFER;
}

static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
{
	int err = 0;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
	struct net *net = xs_net(x);

	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
		XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;

		if (unlikely(replay_esn->oseq == 0)) {
			XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;

			if (replay_esn->oseq_hi == 0) {
				replay_esn->oseq--;
				replay_esn->oseq_hi--;
				xfrm_audit_state_replay_overflow(x, skb);
				err = -EOVERFLOW;

				return err;
			}
		}
		if (xfrm_aevent_is_on(net))
			x->repl->notify(x, XFRM_REPLAY_UPDATE);
	}

	return err;
}

static int xfrm_replay_check_esn(struct xfrm_state *x,
				 struct sk_buff *skb, __be32 net_seq)
{
	unsigned int bitnr, nr;
	u32 diff;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
	u32 pos;
	u32 seq = ntohl(net_seq);
	u32 wsize = replay_esn->replay_window;
	u32 top = replay_esn->seq;
	u32 bottom = top - wsize + 1;

	if (!wsize)
		return 0;

	pos = (replay_esn->seq - 1) % replay_esn->replay_window;

	if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
		     (replay_esn->seq < replay_esn->replay_window - 1)))
		goto err;

	diff = top - seq;

	if (likely(top >= wsize - 1)) {
		/* A. same subspace */
		if (likely(seq > top) || seq < bottom)
			return 0;
	} else {
		/* B. window spans two subspaces */
		if (likely(seq > top && seq < bottom))
			return 0;
		if (seq >= bottom)
			diff = ~seq + top + 1;
	}

	if (diff >= replay_esn->replay_window) {
		x->stats.replay_window++;
		goto err;
	}

	if (pos >= diff) {
		bitnr = (pos - diff) % replay_esn->replay_window;
		nr = bitnr >> 5;
		bitnr = bitnr & 0x1F;
		if (replay_esn->bmp[nr] & (1U << bitnr))
			goto err_replay;
	} else {
		bitnr = replay_esn->replay_window - (diff - pos);
		nr = bitnr >> 5;
		bitnr = bitnr & 0x1F;
		if (replay_esn->bmp[nr] & (1U << bitnr))
			goto err_replay;
	}
	return 0;

err_replay:
	x->stats.replay++;
err:
	xfrm_audit_state_replay(x, skb, net_seq);
	return -EINVAL;
}

static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
{
	unsigned int bitnr, nr, i;
	int wrap;
	u32 diff, pos, seq, seq_hi;
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;

	if (!replay_esn->replay_window)
		return;

	seq = ntohl(net_seq);
	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
	seq_hi = xfrm_replay_seqhi(x, net_seq);
	wrap = seq_hi - replay_esn->seq_hi;

	if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
		if (likely(!wrap))
			diff = seq - replay_esn->seq;
		else
			diff = ~replay_esn->seq + seq + 1;

		if (diff < replay_esn->replay_window) {
			for (i = 1; i < diff; i++) {
				bitnr = (pos + i) % replay_esn->replay_window;
				nr = bitnr >> 5;
				bitnr = bitnr & 0x1F;
				replay_esn->bmp[nr] &=  ~(1U << bitnr);
			}

			bitnr = (pos + diff) % replay_esn->replay_window;
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		} else {
			nr = replay_esn->replay_window >> 5;
			for (i = 0; i <= nr; i++)
				replay_esn->bmp[i] = 0;

			bitnr = (pos + diff) % replay_esn->replay_window;
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		}

		replay_esn->seq = seq;

		if (unlikely(wrap > 0))
			replay_esn->seq_hi++;
	} else {
		diff = replay_esn->seq - seq;

		if (pos >= diff) {
			bitnr = (pos - diff) % replay_esn->replay_window;
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		} else {
			bitnr = replay_esn->replay_window - (diff - pos);
			nr = bitnr >> 5;
			bitnr = bitnr & 0x1F;
			replay_esn->bmp[nr] |= (1U << bitnr);
		}
	}

	if (xfrm_aevent_is_on(xs_net(x)))
		xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
}

static struct xfrm_replay xfrm_replay_legacy = {
	.advance	= xfrm_replay_advance,
	.check		= xfrm_replay_check,
	.notify		= xfrm_replay_notify,
	.overflow	= xfrm_replay_overflow,
};

static struct xfrm_replay xfrm_replay_bmp = {
	.advance	= xfrm_replay_advance_bmp,
	.check		= xfrm_replay_check_bmp,
	.notify		= xfrm_replay_notify_bmp,
	.overflow	= xfrm_replay_overflow_bmp,
};

static struct xfrm_replay xfrm_replay_esn = {
	.advance	= xfrm_replay_advance_esn,
	.check		= xfrm_replay_check_esn,
	.notify		= xfrm_replay_notify_bmp,
	.overflow	= xfrm_replay_overflow_esn,
};

int xfrm_init_replay(struct xfrm_state *x)
{
	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;

	if (replay_esn) {
		if (replay_esn->replay_window >
		    replay_esn->bmp_len * sizeof(__u32))
			return -EINVAL;

	if ((x->props.flags & XFRM_STATE_ESN) && x->replay_esn)
		x->repl = &xfrm_replay_esn;
	else
		x->repl = &xfrm_replay_bmp;
	} else
		x->repl = &xfrm_replay_legacy;

	return 0;
}
EXPORT_SYMBOL(xfrm_init_replay);