summaryrefslogtreecommitdiffstats
path: root/net/xfrm/xfrm_replay.c
blob: 50589ea9d6a8ddf2b18231b1e6a303a5ddd39bb0 (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
/*
 * 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>

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 (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 seq = ntohl(net_seq);
	u32 diff =  replay_esn->seq - seq;
	u32 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 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,
};

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;

		x->repl = &xfrm_replay_bmp;
	} else
		x->repl = &xfrm_replay_legacy;


	return 0;
}
EXPORT_SYMBOL(xfrm_init_replay);