xref: /openbmc/linux/net/xfrm/xfrm_replay.c (revision c4c11dd1) 
1 /*
2  * xfrm_replay.c - xfrm replay detection, derived from xfrm_state.c.
3  *
4  * Copyright (C) 2010 secunet Security Networks AG
5  * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
6  *
7  * This program is free software; you can redistribute it and/or modify it
8  * under the terms and conditions of the GNU General Public License,
9  * version 2, as published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
14  * more details.
15  *
16  * You should have received a copy of the GNU General Public License along with
17  * this program; if not, write to the Free Software Foundation, Inc.,
18  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
19  */
20 
21 #include <linux/export.h>
22 #include <net/xfrm.h>
23 
24 u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq)
25 {
26 	u32 seq, seq_hi, bottom;
27 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
28 
29 	if (!(x->props.flags & XFRM_STATE_ESN))
30 		return 0;
31 
32 	seq = ntohl(net_seq);
33 	seq_hi = replay_esn->seq_hi;
34 	bottom = replay_esn->seq - replay_esn->replay_window + 1;
35 
36 	if (likely(replay_esn->seq >= replay_esn->replay_window - 1)) {
37 		/* A. same subspace */
38 		if (unlikely(seq < bottom))
39 			seq_hi++;
40 	} else {
41 		/* B. window spans two subspaces */
42 		if (unlikely(seq >= bottom))
43 			seq_hi--;
44 	}
45 
46 	return seq_hi;
47 }
48 
49 static void xfrm_replay_notify(struct xfrm_state *x, int event)
50 {
51 	struct km_event c;
52 	/* we send notify messages in case
53 	 *  1. we updated on of the sequence numbers, and the seqno difference
54 	 *     is at least x->replay_maxdiff, in this case we also update the
55 	 *     timeout of our timer function
56 	 *  2. if x->replay_maxage has elapsed since last update,
57 	 *     and there were changes
58 	 *
59 	 *  The state structure must be locked!
60 	 */
61 
62 	switch (event) {
63 	case XFRM_REPLAY_UPDATE:
64 		if (x->replay_maxdiff &&
65 		    (x->replay.seq - x->preplay.seq < x->replay_maxdiff) &&
66 		    (x->replay.oseq - x->preplay.oseq < x->replay_maxdiff)) {
67 			if (x->xflags & XFRM_TIME_DEFER)
68 				event = XFRM_REPLAY_TIMEOUT;
69 			else
70 				return;
71 		}
72 
73 		break;
74 
75 	case XFRM_REPLAY_TIMEOUT:
76 		if (memcmp(&x->replay, &x->preplay,
77 			   sizeof(struct xfrm_replay_state)) == 0) {
78 			x->xflags |= XFRM_TIME_DEFER;
79 			return;
80 		}
81 
82 		break;
83 	}
84 
85 	memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state));
86 	c.event = XFRM_MSG_NEWAE;
87 	c.data.aevent = event;
88 	km_state_notify(x, &c);
89 
90 	if (x->replay_maxage &&
91 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
92 		x->xflags &= ~XFRM_TIME_DEFER;
93 }
94 
95 static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
96 {
97 	int err = 0;
98 	struct net *net = xs_net(x);
99 
100 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
101 		XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
102 		if (unlikely(x->replay.oseq == 0)) {
103 			x->replay.oseq--;
104 			xfrm_audit_state_replay_overflow(x, skb);
105 			err = -EOVERFLOW;
106 
107 			return err;
108 		}
109 		if (xfrm_aevent_is_on(net))
110 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
111 	}
112 
113 	return err;
114 }
115 
116 static int xfrm_replay_check(struct xfrm_state *x,
117 		      struct sk_buff *skb, __be32 net_seq)
118 {
119 	u32 diff;
120 	u32 seq = ntohl(net_seq);
121 
122 	if (!x->props.replay_window)
123 		return 0;
124 
125 	if (unlikely(seq == 0))
126 		goto err;
127 
128 	if (likely(seq > x->replay.seq))
129 		return 0;
130 
131 	diff = x->replay.seq - seq;
132 	if (diff >= min_t(unsigned int, x->props.replay_window,
133 			  sizeof(x->replay.bitmap) * 8)) {
134 		x->stats.replay_window++;
135 		goto err;
136 	}
137 
138 	if (x->replay.bitmap & (1U << diff)) {
139 		x->stats.replay++;
140 		goto err;
141 	}
142 	return 0;
143 
144 err:
145 	xfrm_audit_state_replay(x, skb, net_seq);
146 	return -EINVAL;
147 }
148 
149 static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
150 {
151 	u32 diff;
152 	u32 seq = ntohl(net_seq);
153 
154 	if (!x->props.replay_window)
155 		return;
156 
157 	if (seq > x->replay.seq) {
158 		diff = seq - x->replay.seq;
159 		if (diff < x->props.replay_window)
160 			x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
161 		else
162 			x->replay.bitmap = 1;
163 		x->replay.seq = seq;
164 	} else {
165 		diff = x->replay.seq - seq;
166 		x->replay.bitmap |= (1U << diff);
167 	}
168 
169 	if (xfrm_aevent_is_on(xs_net(x)))
170 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
171 }
172 
173 static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
174 {
175 	int err = 0;
176 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
177 	struct net *net = xs_net(x);
178 
179 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
180 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
181 		if (unlikely(replay_esn->oseq == 0)) {
182 			replay_esn->oseq--;
183 			xfrm_audit_state_replay_overflow(x, skb);
184 			err = -EOVERFLOW;
185 
186 			return err;
187 		}
188 		if (xfrm_aevent_is_on(net))
189 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
190 	}
191 
192 	return err;
193 }
194 
195 static int xfrm_replay_check_bmp(struct xfrm_state *x,
196 				 struct sk_buff *skb, __be32 net_seq)
197 {
198 	unsigned int bitnr, nr;
199 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
200 	u32 pos;
201 	u32 seq = ntohl(net_seq);
202 	u32 diff =  replay_esn->seq - seq;
203 
204 	if (!replay_esn->replay_window)
205 		return 0;
206 
207 	if (unlikely(seq == 0))
208 		goto err;
209 
210 	if (likely(seq > replay_esn->seq))
211 		return 0;
212 
213 	if (diff >= replay_esn->replay_window) {
214 		x->stats.replay_window++;
215 		goto err;
216 	}
217 
218 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
219 
220 	if (pos >= diff)
221 		bitnr = (pos - diff) % replay_esn->replay_window;
222 	else
223 		bitnr = replay_esn->replay_window - (diff - pos);
224 
225 	nr = bitnr >> 5;
226 	bitnr = bitnr & 0x1F;
227 	if (replay_esn->bmp[nr] & (1U << bitnr))
228 		goto err_replay;
229 
230 	return 0;
231 
232 err_replay:
233 	x->stats.replay++;
234 err:
235 	xfrm_audit_state_replay(x, skb, net_seq);
236 	return -EINVAL;
237 }
238 
239 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
240 {
241 	unsigned int bitnr, nr, i;
242 	u32 diff;
243 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
244 	u32 seq = ntohl(net_seq);
245 	u32 pos;
246 
247 	if (!replay_esn->replay_window)
248 		return;
249 
250 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
251 
252 	if (seq > replay_esn->seq) {
253 		diff = seq - replay_esn->seq;
254 
255 		if (diff < replay_esn->replay_window) {
256 			for (i = 1; i < diff; i++) {
257 				bitnr = (pos + i) % replay_esn->replay_window;
258 				nr = bitnr >> 5;
259 				bitnr = bitnr & 0x1F;
260 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
261 			}
262 		} else {
263 			nr = (replay_esn->replay_window - 1) >> 5;
264 			for (i = 0; i <= nr; i++)
265 				replay_esn->bmp[i] = 0;
266 		}
267 
268 		bitnr = (pos + diff) % replay_esn->replay_window;
269 		replay_esn->seq = seq;
270 	} else {
271 		diff = replay_esn->seq - seq;
272 
273 		if (pos >= diff)
274 			bitnr = (pos - diff) % replay_esn->replay_window;
275 		else
276 			bitnr = replay_esn->replay_window - (diff - pos);
277 	}
278 
279 	nr = bitnr >> 5;
280 	bitnr = bitnr & 0x1F;
281 	replay_esn->bmp[nr] |= (1U << bitnr);
282 
283 	if (xfrm_aevent_is_on(xs_net(x)))
284 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
285 }
286 
287 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
288 {
289 	struct km_event c;
290 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
291 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
292 
293 	/* we send notify messages in case
294 	 *  1. we updated on of the sequence numbers, and the seqno difference
295 	 *     is at least x->replay_maxdiff, in this case we also update the
296 	 *     timeout of our timer function
297 	 *  2. if x->replay_maxage has elapsed since last update,
298 	 *     and there were changes
299 	 *
300 	 *  The state structure must be locked!
301 	 */
302 
303 	switch (event) {
304 	case XFRM_REPLAY_UPDATE:
305 		if (x->replay_maxdiff &&
306 		    (replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
307 		    (replay_esn->oseq - preplay_esn->oseq < x->replay_maxdiff)) {
308 			if (x->xflags & XFRM_TIME_DEFER)
309 				event = XFRM_REPLAY_TIMEOUT;
310 			else
311 				return;
312 		}
313 
314 		break;
315 
316 	case XFRM_REPLAY_TIMEOUT:
317 		if (memcmp(x->replay_esn, x->preplay_esn,
318 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
319 			x->xflags |= XFRM_TIME_DEFER;
320 			return;
321 		}
322 
323 		break;
324 	}
325 
326 	memcpy(x->preplay_esn, x->replay_esn,
327 	       xfrm_replay_state_esn_len(replay_esn));
328 	c.event = XFRM_MSG_NEWAE;
329 	c.data.aevent = event;
330 	km_state_notify(x, &c);
331 
332 	if (x->replay_maxage &&
333 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
334 		x->xflags &= ~XFRM_TIME_DEFER;
335 }
336 
337 static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
338 {
339 	u32 seq_diff, oseq_diff;
340 	struct km_event c;
341 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
342 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
343 
344 	/* we send notify messages in case
345 	 *  1. we updated on of the sequence numbers, and the seqno difference
346 	 *     is at least x->replay_maxdiff, in this case we also update the
347 	 *     timeout of our timer function
348 	 *  2. if x->replay_maxage has elapsed since last update,
349 	 *     and there were changes
350 	 *
351 	 *  The state structure must be locked!
352 	 */
353 
354 	switch (event) {
355 	case XFRM_REPLAY_UPDATE:
356 		if (!x->replay_maxdiff)
357 			break;
358 
359 		if (replay_esn->seq_hi == preplay_esn->seq_hi)
360 			seq_diff = replay_esn->seq - preplay_esn->seq;
361 		else
362 			seq_diff = ~preplay_esn->seq + replay_esn->seq + 1;
363 
364 		if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
365 			oseq_diff = replay_esn->oseq - preplay_esn->oseq;
366 		else
367 			oseq_diff = ~preplay_esn->oseq + replay_esn->oseq + 1;
368 
369 		if (seq_diff < x->replay_maxdiff &&
370 		    oseq_diff < x->replay_maxdiff) {
371 
372 			if (x->xflags & XFRM_TIME_DEFER)
373 				event = XFRM_REPLAY_TIMEOUT;
374 			else
375 				return;
376 		}
377 
378 		break;
379 
380 	case XFRM_REPLAY_TIMEOUT:
381 		if (memcmp(x->replay_esn, x->preplay_esn,
382 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
383 			x->xflags |= XFRM_TIME_DEFER;
384 			return;
385 		}
386 
387 		break;
388 	}
389 
390 	memcpy(x->preplay_esn, x->replay_esn,
391 	       xfrm_replay_state_esn_len(replay_esn));
392 	c.event = XFRM_MSG_NEWAE;
393 	c.data.aevent = event;
394 	km_state_notify(x, &c);
395 
396 	if (x->replay_maxage &&
397 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
398 		x->xflags &= ~XFRM_TIME_DEFER;
399 }
400 
401 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
402 {
403 	int err = 0;
404 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
405 	struct net *net = xs_net(x);
406 
407 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
408 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
409 		XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
410 
411 		if (unlikely(replay_esn->oseq == 0)) {
412 			XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
413 
414 			if (replay_esn->oseq_hi == 0) {
415 				replay_esn->oseq--;
416 				replay_esn->oseq_hi--;
417 				xfrm_audit_state_replay_overflow(x, skb);
418 				err = -EOVERFLOW;
419 
420 				return err;
421 			}
422 		}
423 		if (xfrm_aevent_is_on(net))
424 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
425 	}
426 
427 	return err;
428 }
429 
430 static int xfrm_replay_check_esn(struct xfrm_state *x,
431 				 struct sk_buff *skb, __be32 net_seq)
432 {
433 	unsigned int bitnr, nr;
434 	u32 diff;
435 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
436 	u32 pos;
437 	u32 seq = ntohl(net_seq);
438 	u32 wsize = replay_esn->replay_window;
439 	u32 top = replay_esn->seq;
440 	u32 bottom = top - wsize + 1;
441 
442 	if (!wsize)
443 		return 0;
444 
445 	if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
446 		     (replay_esn->seq < replay_esn->replay_window - 1)))
447 		goto err;
448 
449 	diff = top - seq;
450 
451 	if (likely(top >= wsize - 1)) {
452 		/* A. same subspace */
453 		if (likely(seq > top) || seq < bottom)
454 			return 0;
455 	} else {
456 		/* B. window spans two subspaces */
457 		if (likely(seq > top && seq < bottom))
458 			return 0;
459 		if (seq >= bottom)
460 			diff = ~seq + top + 1;
461 	}
462 
463 	if (diff >= replay_esn->replay_window) {
464 		x->stats.replay_window++;
465 		goto err;
466 	}
467 
468 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
469 
470 	if (pos >= diff)
471 		bitnr = (pos - diff) % replay_esn->replay_window;
472 	else
473 		bitnr = replay_esn->replay_window - (diff - pos);
474 
475 	nr = bitnr >> 5;
476 	bitnr = bitnr & 0x1F;
477 	if (replay_esn->bmp[nr] & (1U << bitnr))
478 		goto err_replay;
479 
480 	return 0;
481 
482 err_replay:
483 	x->stats.replay++;
484 err:
485 	xfrm_audit_state_replay(x, skb, net_seq);
486 	return -EINVAL;
487 }
488 
489 static int xfrm_replay_recheck_esn(struct xfrm_state *x,
490 				   struct sk_buff *skb, __be32 net_seq)
491 {
492 	if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
493 		     htonl(xfrm_replay_seqhi(x, net_seq)))) {
494 			x->stats.replay_window++;
495 			return -EINVAL;
496 	}
497 
498 	return xfrm_replay_check_esn(x, skb, net_seq);
499 }
500 
501 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
502 {
503 	unsigned int bitnr, nr, i;
504 	int wrap;
505 	u32 diff, pos, seq, seq_hi;
506 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
507 
508 	if (!replay_esn->replay_window)
509 		return;
510 
511 	seq = ntohl(net_seq);
512 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
513 	seq_hi = xfrm_replay_seqhi(x, net_seq);
514 	wrap = seq_hi - replay_esn->seq_hi;
515 
516 	if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
517 		if (likely(!wrap))
518 			diff = seq - replay_esn->seq;
519 		else
520 			diff = ~replay_esn->seq + seq + 1;
521 
522 		if (diff < replay_esn->replay_window) {
523 			for (i = 1; i < diff; i++) {
524 				bitnr = (pos + i) % replay_esn->replay_window;
525 				nr = bitnr >> 5;
526 				bitnr = bitnr & 0x1F;
527 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
528 			}
529 		} else {
530 			nr = (replay_esn->replay_window - 1) >> 5;
531 			for (i = 0; i <= nr; i++)
532 				replay_esn->bmp[i] = 0;
533 		}
534 
535 		bitnr = (pos + diff) % replay_esn->replay_window;
536 		replay_esn->seq = seq;
537 
538 		if (unlikely(wrap > 0))
539 			replay_esn->seq_hi++;
540 	} else {
541 		diff = replay_esn->seq - seq;
542 
543 		if (pos >= diff)
544 			bitnr = (pos - diff) % replay_esn->replay_window;
545 		else
546 			bitnr = replay_esn->replay_window - (diff - pos);
547 	}
548 
549 	nr = bitnr >> 5;
550 	bitnr = bitnr & 0x1F;
551 	replay_esn->bmp[nr] |= (1U << bitnr);
552 
553 	if (xfrm_aevent_is_on(xs_net(x)))
554 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
555 }
556 
557 static struct xfrm_replay xfrm_replay_legacy = {
558 	.advance	= xfrm_replay_advance,
559 	.check		= xfrm_replay_check,
560 	.recheck	= xfrm_replay_check,
561 	.notify		= xfrm_replay_notify,
562 	.overflow	= xfrm_replay_overflow,
563 };
564 
565 static struct xfrm_replay xfrm_replay_bmp = {
566 	.advance	= xfrm_replay_advance_bmp,
567 	.check		= xfrm_replay_check_bmp,
568 	.recheck	= xfrm_replay_check_bmp,
569 	.notify		= xfrm_replay_notify_bmp,
570 	.overflow	= xfrm_replay_overflow_bmp,
571 };
572 
573 static struct xfrm_replay xfrm_replay_esn = {
574 	.advance	= xfrm_replay_advance_esn,
575 	.check		= xfrm_replay_check_esn,
576 	.recheck	= xfrm_replay_recheck_esn,
577 	.notify		= xfrm_replay_notify_esn,
578 	.overflow	= xfrm_replay_overflow_esn,
579 };
580 
581 int xfrm_init_replay(struct xfrm_state *x)
582 {
583 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
584 
585 	if (replay_esn) {
586 		if (replay_esn->replay_window >
587 		    replay_esn->bmp_len * sizeof(__u32) * 8)
588 			return -EINVAL;
589 
590 		if (x->props.flags & XFRM_STATE_ESN) {
591 			if (replay_esn->replay_window == 0)
592 				return -EINVAL;
593 			x->repl = &xfrm_replay_esn;
594 		} else
595 			x->repl = &xfrm_replay_bmp;
596 	} else
597 		x->repl = &xfrm_replay_legacy;
598 
599 	return 0;
600 }
601 EXPORT_SYMBOL(xfrm_init_replay);
602