xref: /openbmc/linux/net/xfrm/xfrm_replay.c (revision 4f6cce39) 
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 		XFRM_SKB_CB(skb)->seq.output.hi = 0;
103 		if (unlikely(x->replay.oseq == 0)) {
104 			x->replay.oseq--;
105 			xfrm_audit_state_replay_overflow(x, skb);
106 			err = -EOVERFLOW;
107 
108 			return err;
109 		}
110 		if (xfrm_aevent_is_on(net))
111 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
112 	}
113 
114 	return err;
115 }
116 
117 static int xfrm_replay_check(struct xfrm_state *x,
118 		      struct sk_buff *skb, __be32 net_seq)
119 {
120 	u32 diff;
121 	u32 seq = ntohl(net_seq);
122 
123 	if (!x->props.replay_window)
124 		return 0;
125 
126 	if (unlikely(seq == 0))
127 		goto err;
128 
129 	if (likely(seq > x->replay.seq))
130 		return 0;
131 
132 	diff = x->replay.seq - seq;
133 	if (diff >= x->props.replay_window) {
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 		XFRM_SKB_CB(skb)->seq.output.hi = 0;
182 		if (unlikely(replay_esn->oseq == 0)) {
183 			replay_esn->oseq--;
184 			xfrm_audit_state_replay_overflow(x, skb);
185 			err = -EOVERFLOW;
186 
187 			return err;
188 		}
189 		if (xfrm_aevent_is_on(net))
190 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
191 	}
192 
193 	return err;
194 }
195 
196 static int xfrm_replay_check_bmp(struct xfrm_state *x,
197 				 struct sk_buff *skb, __be32 net_seq)
198 {
199 	unsigned int bitnr, nr;
200 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
201 	u32 pos;
202 	u32 seq = ntohl(net_seq);
203 	u32 diff =  replay_esn->seq - seq;
204 
205 	if (!replay_esn->replay_window)
206 		return 0;
207 
208 	if (unlikely(seq == 0))
209 		goto err;
210 
211 	if (likely(seq > replay_esn->seq))
212 		return 0;
213 
214 	if (diff >= replay_esn->replay_window) {
215 		x->stats.replay_window++;
216 		goto err;
217 	}
218 
219 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
220 
221 	if (pos >= diff)
222 		bitnr = (pos - diff) % replay_esn->replay_window;
223 	else
224 		bitnr = replay_esn->replay_window - (diff - pos);
225 
226 	nr = bitnr >> 5;
227 	bitnr = bitnr & 0x1F;
228 	if (replay_esn->bmp[nr] & (1U << bitnr))
229 		goto err_replay;
230 
231 	return 0;
232 
233 err_replay:
234 	x->stats.replay++;
235 err:
236 	xfrm_audit_state_replay(x, skb, net_seq);
237 	return -EINVAL;
238 }
239 
240 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
241 {
242 	unsigned int bitnr, nr, i;
243 	u32 diff;
244 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
245 	u32 seq = ntohl(net_seq);
246 	u32 pos;
247 
248 	if (!replay_esn->replay_window)
249 		return;
250 
251 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
252 
253 	if (seq > replay_esn->seq) {
254 		diff = seq - replay_esn->seq;
255 
256 		if (diff < replay_esn->replay_window) {
257 			for (i = 1; i < diff; i++) {
258 				bitnr = (pos + i) % replay_esn->replay_window;
259 				nr = bitnr >> 5;
260 				bitnr = bitnr & 0x1F;
261 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
262 			}
263 		} else {
264 			nr = (replay_esn->replay_window - 1) >> 5;
265 			for (i = 0; i <= nr; i++)
266 				replay_esn->bmp[i] = 0;
267 		}
268 
269 		bitnr = (pos + diff) % replay_esn->replay_window;
270 		replay_esn->seq = seq;
271 	} else {
272 		diff = replay_esn->seq - seq;
273 
274 		if (pos >= diff)
275 			bitnr = (pos - diff) % replay_esn->replay_window;
276 		else
277 			bitnr = replay_esn->replay_window - (diff - pos);
278 	}
279 
280 	nr = bitnr >> 5;
281 	bitnr = bitnr & 0x1F;
282 	replay_esn->bmp[nr] |= (1U << bitnr);
283 
284 	if (xfrm_aevent_is_on(xs_net(x)))
285 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
286 }
287 
288 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
289 {
290 	struct km_event c;
291 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
292 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
293 
294 	/* we send notify messages in case
295 	 *  1. we updated on of the sequence numbers, and the seqno difference
296 	 *     is at least x->replay_maxdiff, in this case we also update the
297 	 *     timeout of our timer function
298 	 *  2. if x->replay_maxage has elapsed since last update,
299 	 *     and there were changes
300 	 *
301 	 *  The state structure must be locked!
302 	 */
303 
304 	switch (event) {
305 	case XFRM_REPLAY_UPDATE:
306 		if (!x->replay_maxdiff ||
307 		    ((replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
308 		    (replay_esn->oseq - preplay_esn->oseq
309 		     < x->replay_maxdiff))) {
310 			if (x->xflags & XFRM_TIME_DEFER)
311 				event = XFRM_REPLAY_TIMEOUT;
312 			else
313 				return;
314 		}
315 
316 		break;
317 
318 	case XFRM_REPLAY_TIMEOUT:
319 		if (memcmp(x->replay_esn, x->preplay_esn,
320 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
321 			x->xflags |= XFRM_TIME_DEFER;
322 			return;
323 		}
324 
325 		break;
326 	}
327 
328 	memcpy(x->preplay_esn, x->replay_esn,
329 	       xfrm_replay_state_esn_len(replay_esn));
330 	c.event = XFRM_MSG_NEWAE;
331 	c.data.aevent = event;
332 	km_state_notify(x, &c);
333 
334 	if (x->replay_maxage &&
335 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
336 		x->xflags &= ~XFRM_TIME_DEFER;
337 }
338 
339 static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
340 {
341 	u32 seq_diff, oseq_diff;
342 	struct km_event c;
343 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
344 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
345 
346 	/* we send notify messages in case
347 	 *  1. we updated on of the sequence numbers, and the seqno difference
348 	 *     is at least x->replay_maxdiff, in this case we also update the
349 	 *     timeout of our timer function
350 	 *  2. if x->replay_maxage has elapsed since last update,
351 	 *     and there were changes
352 	 *
353 	 *  The state structure must be locked!
354 	 */
355 
356 	switch (event) {
357 	case XFRM_REPLAY_UPDATE:
358 		if (x->replay_maxdiff) {
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
363 					   + 1;
364 
365 			if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
366 				oseq_diff = replay_esn->oseq
367 					    - preplay_esn->oseq;
368 			else
369 				oseq_diff = ~preplay_esn->oseq
370 					    + replay_esn->oseq + 1;
371 
372 			if (seq_diff >= x->replay_maxdiff ||
373 			    oseq_diff >= x->replay_maxdiff)
374 				break;
375 		}
376 
377 		if (x->xflags & XFRM_TIME_DEFER)
378 			event = XFRM_REPLAY_TIMEOUT;
379 		else
380 			return;
381 
382 		break;
383 
384 	case XFRM_REPLAY_TIMEOUT:
385 		if (memcmp(x->replay_esn, x->preplay_esn,
386 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
387 			x->xflags |= XFRM_TIME_DEFER;
388 			return;
389 		}
390 
391 		break;
392 	}
393 
394 	memcpy(x->preplay_esn, x->replay_esn,
395 	       xfrm_replay_state_esn_len(replay_esn));
396 	c.event = XFRM_MSG_NEWAE;
397 	c.data.aevent = event;
398 	km_state_notify(x, &c);
399 
400 	if (x->replay_maxage &&
401 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
402 		x->xflags &= ~XFRM_TIME_DEFER;
403 }
404 
405 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
406 {
407 	int err = 0;
408 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
409 	struct net *net = xs_net(x);
410 
411 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
412 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
413 		XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
414 
415 		if (unlikely(replay_esn->oseq == 0)) {
416 			XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
417 
418 			if (replay_esn->oseq_hi == 0) {
419 				replay_esn->oseq--;
420 				replay_esn->oseq_hi--;
421 				xfrm_audit_state_replay_overflow(x, skb);
422 				err = -EOVERFLOW;
423 
424 				return err;
425 			}
426 		}
427 		if (xfrm_aevent_is_on(net))
428 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
429 	}
430 
431 	return err;
432 }
433 
434 static int xfrm_replay_check_esn(struct xfrm_state *x,
435 				 struct sk_buff *skb, __be32 net_seq)
436 {
437 	unsigned int bitnr, nr;
438 	u32 diff;
439 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
440 	u32 pos;
441 	u32 seq = ntohl(net_seq);
442 	u32 wsize = replay_esn->replay_window;
443 	u32 top = replay_esn->seq;
444 	u32 bottom = top - wsize + 1;
445 
446 	if (!wsize)
447 		return 0;
448 
449 	if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
450 		     (replay_esn->seq < replay_esn->replay_window - 1)))
451 		goto err;
452 
453 	diff = top - seq;
454 
455 	if (likely(top >= wsize - 1)) {
456 		/* A. same subspace */
457 		if (likely(seq > top) || seq < bottom)
458 			return 0;
459 	} else {
460 		/* B. window spans two subspaces */
461 		if (likely(seq > top && seq < bottom))
462 			return 0;
463 		if (seq >= bottom)
464 			diff = ~seq + top + 1;
465 	}
466 
467 	if (diff >= replay_esn->replay_window) {
468 		x->stats.replay_window++;
469 		goto err;
470 	}
471 
472 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
473 
474 	if (pos >= diff)
475 		bitnr = (pos - diff) % replay_esn->replay_window;
476 	else
477 		bitnr = replay_esn->replay_window - (diff - pos);
478 
479 	nr = bitnr >> 5;
480 	bitnr = bitnr & 0x1F;
481 	if (replay_esn->bmp[nr] & (1U << bitnr))
482 		goto err_replay;
483 
484 	return 0;
485 
486 err_replay:
487 	x->stats.replay++;
488 err:
489 	xfrm_audit_state_replay(x, skb, net_seq);
490 	return -EINVAL;
491 }
492 
493 static int xfrm_replay_recheck_esn(struct xfrm_state *x,
494 				   struct sk_buff *skb, __be32 net_seq)
495 {
496 	if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
497 		     htonl(xfrm_replay_seqhi(x, net_seq)))) {
498 			x->stats.replay_window++;
499 			return -EINVAL;
500 	}
501 
502 	return xfrm_replay_check_esn(x, skb, net_seq);
503 }
504 
505 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
506 {
507 	unsigned int bitnr, nr, i;
508 	int wrap;
509 	u32 diff, pos, seq, seq_hi;
510 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
511 
512 	if (!replay_esn->replay_window)
513 		return;
514 
515 	seq = ntohl(net_seq);
516 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
517 	seq_hi = xfrm_replay_seqhi(x, net_seq);
518 	wrap = seq_hi - replay_esn->seq_hi;
519 
520 	if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
521 		if (likely(!wrap))
522 			diff = seq - replay_esn->seq;
523 		else
524 			diff = ~replay_esn->seq + seq + 1;
525 
526 		if (diff < replay_esn->replay_window) {
527 			for (i = 1; i < diff; i++) {
528 				bitnr = (pos + i) % replay_esn->replay_window;
529 				nr = bitnr >> 5;
530 				bitnr = bitnr & 0x1F;
531 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
532 			}
533 		} else {
534 			nr = (replay_esn->replay_window - 1) >> 5;
535 			for (i = 0; i <= nr; i++)
536 				replay_esn->bmp[i] = 0;
537 		}
538 
539 		bitnr = (pos + diff) % replay_esn->replay_window;
540 		replay_esn->seq = seq;
541 
542 		if (unlikely(wrap > 0))
543 			replay_esn->seq_hi++;
544 	} else {
545 		diff = replay_esn->seq - seq;
546 
547 		if (pos >= diff)
548 			bitnr = (pos - diff) % replay_esn->replay_window;
549 		else
550 			bitnr = replay_esn->replay_window - (diff - pos);
551 	}
552 
553 	nr = bitnr >> 5;
554 	bitnr = bitnr & 0x1F;
555 	replay_esn->bmp[nr] |= (1U << bitnr);
556 
557 	if (xfrm_aevent_is_on(xs_net(x)))
558 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
559 }
560 
561 static const struct xfrm_replay xfrm_replay_legacy = {
562 	.advance	= xfrm_replay_advance,
563 	.check		= xfrm_replay_check,
564 	.recheck	= xfrm_replay_check,
565 	.notify		= xfrm_replay_notify,
566 	.overflow	= xfrm_replay_overflow,
567 };
568 
569 static const struct xfrm_replay xfrm_replay_bmp = {
570 	.advance	= xfrm_replay_advance_bmp,
571 	.check		= xfrm_replay_check_bmp,
572 	.recheck	= xfrm_replay_check_bmp,
573 	.notify		= xfrm_replay_notify_bmp,
574 	.overflow	= xfrm_replay_overflow_bmp,
575 };
576 
577 static const struct xfrm_replay xfrm_replay_esn = {
578 	.advance	= xfrm_replay_advance_esn,
579 	.check		= xfrm_replay_check_esn,
580 	.recheck	= xfrm_replay_recheck_esn,
581 	.notify		= xfrm_replay_notify_esn,
582 	.overflow	= xfrm_replay_overflow_esn,
583 };
584 
585 int xfrm_init_replay(struct xfrm_state *x)
586 {
587 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
588 
589 	if (replay_esn) {
590 		if (replay_esn->replay_window >
591 		    replay_esn->bmp_len * sizeof(__u32) * 8)
592 			return -EINVAL;
593 
594 		if (x->props.flags & XFRM_STATE_ESN) {
595 			if (replay_esn->replay_window == 0)
596 				return -EINVAL;
597 			x->repl = &xfrm_replay_esn;
598 		} else
599 			x->repl = &xfrm_replay_bmp;
600 	} else
601 		x->repl = &xfrm_replay_legacy;
602 
603 	return 0;
604 }
605 EXPORT_SYMBOL(xfrm_init_replay);
606