xref: /openbmc/linux/net/xfrm/xfrm_replay.c (revision bc000245) 
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 >= x->props.replay_window) {
133 		x->stats.replay_window++;
134 		goto err;
135 	}
136 
137 	if (x->replay.bitmap & (1U << diff)) {
138 		x->stats.replay++;
139 		goto err;
140 	}
141 	return 0;
142 
143 err:
144 	xfrm_audit_state_replay(x, skb, net_seq);
145 	return -EINVAL;
146 }
147 
148 static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
149 {
150 	u32 diff;
151 	u32 seq = ntohl(net_seq);
152 
153 	if (!x->props.replay_window)
154 		return;
155 
156 	if (seq > x->replay.seq) {
157 		diff = seq - x->replay.seq;
158 		if (diff < x->props.replay_window)
159 			x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
160 		else
161 			x->replay.bitmap = 1;
162 		x->replay.seq = seq;
163 	} else {
164 		diff = x->replay.seq - seq;
165 		x->replay.bitmap |= (1U << diff);
166 	}
167 
168 	if (xfrm_aevent_is_on(xs_net(x)))
169 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
170 }
171 
172 static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
173 {
174 	int err = 0;
175 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
176 	struct net *net = xs_net(x);
177 
178 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
179 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
180 		if (unlikely(replay_esn->oseq == 0)) {
181 			replay_esn->oseq--;
182 			xfrm_audit_state_replay_overflow(x, skb);
183 			err = -EOVERFLOW;
184 
185 			return err;
186 		}
187 		if (xfrm_aevent_is_on(net))
188 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
189 	}
190 
191 	return err;
192 }
193 
194 static int xfrm_replay_check_bmp(struct xfrm_state *x,
195 				 struct sk_buff *skb, __be32 net_seq)
196 {
197 	unsigned int bitnr, nr;
198 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
199 	u32 pos;
200 	u32 seq = ntohl(net_seq);
201 	u32 diff =  replay_esn->seq - seq;
202 
203 	if (!replay_esn->replay_window)
204 		return 0;
205 
206 	if (unlikely(seq == 0))
207 		goto err;
208 
209 	if (likely(seq > replay_esn->seq))
210 		return 0;
211 
212 	if (diff >= replay_esn->replay_window) {
213 		x->stats.replay_window++;
214 		goto err;
215 	}
216 
217 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
218 
219 	if (pos >= diff)
220 		bitnr = (pos - diff) % replay_esn->replay_window;
221 	else
222 		bitnr = replay_esn->replay_window - (diff - pos);
223 
224 	nr = bitnr >> 5;
225 	bitnr = bitnr & 0x1F;
226 	if (replay_esn->bmp[nr] & (1U << bitnr))
227 		goto err_replay;
228 
229 	return 0;
230 
231 err_replay:
232 	x->stats.replay++;
233 err:
234 	xfrm_audit_state_replay(x, skb, net_seq);
235 	return -EINVAL;
236 }
237 
238 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
239 {
240 	unsigned int bitnr, nr, i;
241 	u32 diff;
242 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
243 	u32 seq = ntohl(net_seq);
244 	u32 pos;
245 
246 	if (!replay_esn->replay_window)
247 		return;
248 
249 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
250 
251 	if (seq > replay_esn->seq) {
252 		diff = seq - replay_esn->seq;
253 
254 		if (diff < replay_esn->replay_window) {
255 			for (i = 1; i < diff; i++) {
256 				bitnr = (pos + i) % replay_esn->replay_window;
257 				nr = bitnr >> 5;
258 				bitnr = bitnr & 0x1F;
259 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
260 			}
261 		} else {
262 			nr = (replay_esn->replay_window - 1) >> 5;
263 			for (i = 0; i <= nr; i++)
264 				replay_esn->bmp[i] = 0;
265 		}
266 
267 		bitnr = (pos + diff) % replay_esn->replay_window;
268 		replay_esn->seq = seq;
269 	} else {
270 		diff = replay_esn->seq - seq;
271 
272 		if (pos >= diff)
273 			bitnr = (pos - diff) % replay_esn->replay_window;
274 		else
275 			bitnr = replay_esn->replay_window - (diff - pos);
276 	}
277 
278 	nr = bitnr >> 5;
279 	bitnr = bitnr & 0x1F;
280 	replay_esn->bmp[nr] |= (1U << bitnr);
281 
282 	if (xfrm_aevent_is_on(xs_net(x)))
283 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
284 }
285 
286 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
287 {
288 	struct km_event c;
289 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
290 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
291 
292 	/* we send notify messages in case
293 	 *  1. we updated on of the sequence numbers, and the seqno difference
294 	 *     is at least x->replay_maxdiff, in this case we also update the
295 	 *     timeout of our timer function
296 	 *  2. if x->replay_maxage has elapsed since last update,
297 	 *     and there were changes
298 	 *
299 	 *  The state structure must be locked!
300 	 */
301 
302 	switch (event) {
303 	case XFRM_REPLAY_UPDATE:
304 		if (!x->replay_maxdiff ||
305 		    ((replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
306 		    (replay_esn->oseq - preplay_esn->oseq
307 		     < 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 			if (replay_esn->seq_hi == preplay_esn->seq_hi)
358 				seq_diff = replay_esn->seq - preplay_esn->seq;
359 			else
360 				seq_diff = ~preplay_esn->seq + replay_esn->seq
361 					   + 1;
362 
363 			if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
364 				oseq_diff = replay_esn->oseq
365 					    - preplay_esn->oseq;
366 			else
367 				oseq_diff = ~preplay_esn->oseq
368 					    + replay_esn->oseq + 1;
369 
370 			if (seq_diff >= x->replay_maxdiff ||
371 			    oseq_diff >= x->replay_maxdiff)
372 				break;
373 		}
374 
375 		if (x->xflags & XFRM_TIME_DEFER)
376 			event = XFRM_REPLAY_TIMEOUT;
377 		else
378 			return;
379 
380 		break;
381 
382 	case XFRM_REPLAY_TIMEOUT:
383 		if (memcmp(x->replay_esn, x->preplay_esn,
384 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
385 			x->xflags |= XFRM_TIME_DEFER;
386 			return;
387 		}
388 
389 		break;
390 	}
391 
392 	memcpy(x->preplay_esn, x->replay_esn,
393 	       xfrm_replay_state_esn_len(replay_esn));
394 	c.event = XFRM_MSG_NEWAE;
395 	c.data.aevent = event;
396 	km_state_notify(x, &c);
397 
398 	if (x->replay_maxage &&
399 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
400 		x->xflags &= ~XFRM_TIME_DEFER;
401 }
402 
403 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
404 {
405 	int err = 0;
406 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
407 	struct net *net = xs_net(x);
408 
409 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
410 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
411 		XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
412 
413 		if (unlikely(replay_esn->oseq == 0)) {
414 			XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
415 
416 			if (replay_esn->oseq_hi == 0) {
417 				replay_esn->oseq--;
418 				replay_esn->oseq_hi--;
419 				xfrm_audit_state_replay_overflow(x, skb);
420 				err = -EOVERFLOW;
421 
422 				return err;
423 			}
424 		}
425 		if (xfrm_aevent_is_on(net))
426 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
427 	}
428 
429 	return err;
430 }
431 
432 static int xfrm_replay_check_esn(struct xfrm_state *x,
433 				 struct sk_buff *skb, __be32 net_seq)
434 {
435 	unsigned int bitnr, nr;
436 	u32 diff;
437 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
438 	u32 pos;
439 	u32 seq = ntohl(net_seq);
440 	u32 wsize = replay_esn->replay_window;
441 	u32 top = replay_esn->seq;
442 	u32 bottom = top - wsize + 1;
443 
444 	if (!wsize)
445 		return 0;
446 
447 	if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
448 		     (replay_esn->seq < replay_esn->replay_window - 1)))
449 		goto err;
450 
451 	diff = top - seq;
452 
453 	if (likely(top >= wsize - 1)) {
454 		/* A. same subspace */
455 		if (likely(seq > top) || seq < bottom)
456 			return 0;
457 	} else {
458 		/* B. window spans two subspaces */
459 		if (likely(seq > top && seq < bottom))
460 			return 0;
461 		if (seq >= bottom)
462 			diff = ~seq + top + 1;
463 	}
464 
465 	if (diff >= replay_esn->replay_window) {
466 		x->stats.replay_window++;
467 		goto err;
468 	}
469 
470 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
471 
472 	if (pos >= diff)
473 		bitnr = (pos - diff) % replay_esn->replay_window;
474 	else
475 		bitnr = replay_esn->replay_window - (diff - pos);
476 
477 	nr = bitnr >> 5;
478 	bitnr = bitnr & 0x1F;
479 	if (replay_esn->bmp[nr] & (1U << bitnr))
480 		goto err_replay;
481 
482 	return 0;
483 
484 err_replay:
485 	x->stats.replay++;
486 err:
487 	xfrm_audit_state_replay(x, skb, net_seq);
488 	return -EINVAL;
489 }
490 
491 static int xfrm_replay_recheck_esn(struct xfrm_state *x,
492 				   struct sk_buff *skb, __be32 net_seq)
493 {
494 	if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
495 		     htonl(xfrm_replay_seqhi(x, net_seq)))) {
496 			x->stats.replay_window++;
497 			return -EINVAL;
498 	}
499 
500 	return xfrm_replay_check_esn(x, skb, net_seq);
501 }
502 
503 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
504 {
505 	unsigned int bitnr, nr, i;
506 	int wrap;
507 	u32 diff, pos, seq, seq_hi;
508 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
509 
510 	if (!replay_esn->replay_window)
511 		return;
512 
513 	seq = ntohl(net_seq);
514 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
515 	seq_hi = xfrm_replay_seqhi(x, net_seq);
516 	wrap = seq_hi - replay_esn->seq_hi;
517 
518 	if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
519 		if (likely(!wrap))
520 			diff = seq - replay_esn->seq;
521 		else
522 			diff = ~replay_esn->seq + seq + 1;
523 
524 		if (diff < replay_esn->replay_window) {
525 			for (i = 1; i < diff; i++) {
526 				bitnr = (pos + i) % replay_esn->replay_window;
527 				nr = bitnr >> 5;
528 				bitnr = bitnr & 0x1F;
529 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
530 			}
531 		} else {
532 			nr = (replay_esn->replay_window - 1) >> 5;
533 			for (i = 0; i <= nr; i++)
534 				replay_esn->bmp[i] = 0;
535 		}
536 
537 		bitnr = (pos + diff) % replay_esn->replay_window;
538 		replay_esn->seq = seq;
539 
540 		if (unlikely(wrap > 0))
541 			replay_esn->seq_hi++;
542 	} else {
543 		diff = replay_esn->seq - seq;
544 
545 		if (pos >= diff)
546 			bitnr = (pos - diff) % replay_esn->replay_window;
547 		else
548 			bitnr = replay_esn->replay_window - (diff - pos);
549 	}
550 
551 	nr = bitnr >> 5;
552 	bitnr = bitnr & 0x1F;
553 	replay_esn->bmp[nr] |= (1U << bitnr);
554 
555 	if (xfrm_aevent_is_on(xs_net(x)))
556 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
557 }
558 
559 static struct xfrm_replay xfrm_replay_legacy = {
560 	.advance	= xfrm_replay_advance,
561 	.check		= xfrm_replay_check,
562 	.recheck	= xfrm_replay_check,
563 	.notify		= xfrm_replay_notify,
564 	.overflow	= xfrm_replay_overflow,
565 };
566 
567 static struct xfrm_replay xfrm_replay_bmp = {
568 	.advance	= xfrm_replay_advance_bmp,
569 	.check		= xfrm_replay_check_bmp,
570 	.recheck	= xfrm_replay_check_bmp,
571 	.notify		= xfrm_replay_notify_bmp,
572 	.overflow	= xfrm_replay_overflow_bmp,
573 };
574 
575 static struct xfrm_replay xfrm_replay_esn = {
576 	.advance	= xfrm_replay_advance_esn,
577 	.check		= xfrm_replay_check_esn,
578 	.recheck	= xfrm_replay_recheck_esn,
579 	.notify		= xfrm_replay_notify_esn,
580 	.overflow	= xfrm_replay_overflow_esn,
581 };
582 
583 int xfrm_init_replay(struct xfrm_state *x)
584 {
585 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
586 
587 	if (replay_esn) {
588 		if (replay_esn->replay_window >
589 		    replay_esn->bmp_len * sizeof(__u32) * 8)
590 			return -EINVAL;
591 
592 		if (x->props.flags & XFRM_STATE_ESN) {
593 			if (replay_esn->replay_window == 0)
594 				return -EINVAL;
595 			x->repl = &xfrm_replay_esn;
596 		} else
597 			x->repl = &xfrm_replay_bmp;
598 	} else
599 		x->repl = &xfrm_replay_legacy;
600 
601 	return 0;
602 }
603 EXPORT_SYMBOL(xfrm_init_replay);
604