xref: /openbmc/linux/net/xfrm/xfrm_replay.c (revision 7f6964c5) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * xfrm_replay.c - xfrm replay detection, derived from xfrm_state.c.
4  *
5  * Copyright (C) 2010 secunet Security Networks AG
6  * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
7  */
8 
9 #include <linux/export.h>
10 #include <net/xfrm.h>
11 
12 u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq)
13 {
14 	u32 seq, seq_hi, bottom;
15 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
16 
17 	if (!(x->props.flags & XFRM_STATE_ESN))
18 		return 0;
19 
20 	seq = ntohl(net_seq);
21 	seq_hi = replay_esn->seq_hi;
22 	bottom = replay_esn->seq - replay_esn->replay_window + 1;
23 
24 	if (likely(replay_esn->seq >= replay_esn->replay_window - 1)) {
25 		/* A. same subspace */
26 		if (unlikely(seq < bottom))
27 			seq_hi++;
28 	} else {
29 		/* B. window spans two subspaces */
30 		if (unlikely(seq >= bottom))
31 			seq_hi--;
32 	}
33 
34 	return seq_hi;
35 }
36 EXPORT_SYMBOL(xfrm_replay_seqhi);
37 ;
38 static void xfrm_replay_notify(struct xfrm_state *x, int event)
39 {
40 	struct km_event c;
41 	/* we send notify messages in case
42 	 *  1. we updated on of the sequence numbers, and the seqno difference
43 	 *     is at least x->replay_maxdiff, in this case we also update the
44 	 *     timeout of our timer function
45 	 *  2. if x->replay_maxage has elapsed since last update,
46 	 *     and there were changes
47 	 *
48 	 *  The state structure must be locked!
49 	 */
50 
51 	switch (event) {
52 	case XFRM_REPLAY_UPDATE:
53 		if (!x->replay_maxdiff ||
54 		    ((x->replay.seq - x->preplay.seq < x->replay_maxdiff) &&
55 		    (x->replay.oseq - x->preplay.oseq < x->replay_maxdiff))) {
56 			if (x->xflags & XFRM_TIME_DEFER)
57 				event = XFRM_REPLAY_TIMEOUT;
58 			else
59 				return;
60 		}
61 
62 		break;
63 
64 	case XFRM_REPLAY_TIMEOUT:
65 		if (memcmp(&x->replay, &x->preplay,
66 			   sizeof(struct xfrm_replay_state)) == 0) {
67 			x->xflags |= XFRM_TIME_DEFER;
68 			return;
69 		}
70 
71 		break;
72 	}
73 
74 	memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state));
75 	c.event = XFRM_MSG_NEWAE;
76 	c.data.aevent = event;
77 	km_state_notify(x, &c);
78 
79 	if (x->replay_maxage &&
80 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
81 		x->xflags &= ~XFRM_TIME_DEFER;
82 }
83 
84 static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
85 {
86 	int err = 0;
87 	struct net *net = xs_net(x);
88 
89 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
90 		XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
91 		XFRM_SKB_CB(skb)->seq.output.hi = 0;
92 		if (unlikely(x->replay.oseq == 0)) {
93 			x->replay.oseq--;
94 			xfrm_audit_state_replay_overflow(x, skb);
95 			err = -EOVERFLOW;
96 
97 			return err;
98 		}
99 		if (xfrm_aevent_is_on(net))
100 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
101 	}
102 
103 	return err;
104 }
105 
106 static int xfrm_replay_check(struct xfrm_state *x,
107 		      struct sk_buff *skb, __be32 net_seq)
108 {
109 	u32 diff;
110 	u32 seq = ntohl(net_seq);
111 
112 	if (!x->props.replay_window)
113 		return 0;
114 
115 	if (unlikely(seq == 0))
116 		goto err;
117 
118 	if (likely(seq > x->replay.seq))
119 		return 0;
120 
121 	diff = x->replay.seq - seq;
122 	if (diff >= x->props.replay_window) {
123 		x->stats.replay_window++;
124 		goto err;
125 	}
126 
127 	if (x->replay.bitmap & (1U << diff)) {
128 		x->stats.replay++;
129 		goto err;
130 	}
131 	return 0;
132 
133 err:
134 	xfrm_audit_state_replay(x, skb, net_seq);
135 	return -EINVAL;
136 }
137 
138 static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
139 {
140 	u32 diff;
141 	u32 seq = ntohl(net_seq);
142 
143 	if (!x->props.replay_window)
144 		return;
145 
146 	if (seq > x->replay.seq) {
147 		diff = seq - x->replay.seq;
148 		if (diff < x->props.replay_window)
149 			x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
150 		else
151 			x->replay.bitmap = 1;
152 		x->replay.seq = seq;
153 	} else {
154 		diff = x->replay.seq - seq;
155 		x->replay.bitmap |= (1U << diff);
156 	}
157 
158 	if (xfrm_aevent_is_on(xs_net(x)))
159 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
160 }
161 
162 static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
163 {
164 	int err = 0;
165 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
166 	struct net *net = xs_net(x);
167 
168 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
169 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
170 		XFRM_SKB_CB(skb)->seq.output.hi = 0;
171 		if (unlikely(replay_esn->oseq == 0)) {
172 			replay_esn->oseq--;
173 			xfrm_audit_state_replay_overflow(x, skb);
174 			err = -EOVERFLOW;
175 
176 			return err;
177 		}
178 		if (xfrm_aevent_is_on(net))
179 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
180 	}
181 
182 	return err;
183 }
184 
185 static int xfrm_replay_check_bmp(struct xfrm_state *x,
186 				 struct sk_buff *skb, __be32 net_seq)
187 {
188 	unsigned int bitnr, nr;
189 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
190 	u32 pos;
191 	u32 seq = ntohl(net_seq);
192 	u32 diff =  replay_esn->seq - seq;
193 
194 	if (!replay_esn->replay_window)
195 		return 0;
196 
197 	if (unlikely(seq == 0))
198 		goto err;
199 
200 	if (likely(seq > replay_esn->seq))
201 		return 0;
202 
203 	if (diff >= replay_esn->replay_window) {
204 		x->stats.replay_window++;
205 		goto err;
206 	}
207 
208 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
209 
210 	if (pos >= diff)
211 		bitnr = (pos - diff) % replay_esn->replay_window;
212 	else
213 		bitnr = replay_esn->replay_window - (diff - pos);
214 
215 	nr = bitnr >> 5;
216 	bitnr = bitnr & 0x1F;
217 	if (replay_esn->bmp[nr] & (1U << bitnr))
218 		goto err_replay;
219 
220 	return 0;
221 
222 err_replay:
223 	x->stats.replay++;
224 err:
225 	xfrm_audit_state_replay(x, skb, net_seq);
226 	return -EINVAL;
227 }
228 
229 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
230 {
231 	unsigned int bitnr, nr, i;
232 	u32 diff;
233 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
234 	u32 seq = ntohl(net_seq);
235 	u32 pos;
236 
237 	if (!replay_esn->replay_window)
238 		return;
239 
240 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
241 
242 	if (seq > replay_esn->seq) {
243 		diff = seq - replay_esn->seq;
244 
245 		if (diff < replay_esn->replay_window) {
246 			for (i = 1; i < diff; i++) {
247 				bitnr = (pos + i) % replay_esn->replay_window;
248 				nr = bitnr >> 5;
249 				bitnr = bitnr & 0x1F;
250 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
251 			}
252 		} else {
253 			nr = (replay_esn->replay_window - 1) >> 5;
254 			for (i = 0; i <= nr; i++)
255 				replay_esn->bmp[i] = 0;
256 		}
257 
258 		bitnr = (pos + diff) % replay_esn->replay_window;
259 		replay_esn->seq = seq;
260 	} else {
261 		diff = replay_esn->seq - seq;
262 
263 		if (pos >= diff)
264 			bitnr = (pos - diff) % replay_esn->replay_window;
265 		else
266 			bitnr = replay_esn->replay_window - (diff - pos);
267 	}
268 
269 	nr = bitnr >> 5;
270 	bitnr = bitnr & 0x1F;
271 	replay_esn->bmp[nr] |= (1U << bitnr);
272 
273 	if (xfrm_aevent_is_on(xs_net(x)))
274 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
275 }
276 
277 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
278 {
279 	struct km_event c;
280 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
281 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
282 
283 	/* we send notify messages in case
284 	 *  1. we updated on of the sequence numbers, and the seqno difference
285 	 *     is at least x->replay_maxdiff, in this case we also update the
286 	 *     timeout of our timer function
287 	 *  2. if x->replay_maxage has elapsed since last update,
288 	 *     and there were changes
289 	 *
290 	 *  The state structure must be locked!
291 	 */
292 
293 	switch (event) {
294 	case XFRM_REPLAY_UPDATE:
295 		if (!x->replay_maxdiff ||
296 		    ((replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
297 		    (replay_esn->oseq - preplay_esn->oseq
298 		     < x->replay_maxdiff))) {
299 			if (x->xflags & XFRM_TIME_DEFER)
300 				event = XFRM_REPLAY_TIMEOUT;
301 			else
302 				return;
303 		}
304 
305 		break;
306 
307 	case XFRM_REPLAY_TIMEOUT:
308 		if (memcmp(x->replay_esn, x->preplay_esn,
309 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
310 			x->xflags |= XFRM_TIME_DEFER;
311 			return;
312 		}
313 
314 		break;
315 	}
316 
317 	memcpy(x->preplay_esn, x->replay_esn,
318 	       xfrm_replay_state_esn_len(replay_esn));
319 	c.event = XFRM_MSG_NEWAE;
320 	c.data.aevent = event;
321 	km_state_notify(x, &c);
322 
323 	if (x->replay_maxage &&
324 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
325 		x->xflags &= ~XFRM_TIME_DEFER;
326 }
327 
328 static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
329 {
330 	u32 seq_diff, oseq_diff;
331 	struct km_event c;
332 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
333 	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
334 
335 	/* we send notify messages in case
336 	 *  1. we updated on of the sequence numbers, and the seqno difference
337 	 *     is at least x->replay_maxdiff, in this case we also update the
338 	 *     timeout of our timer function
339 	 *  2. if x->replay_maxage has elapsed since last update,
340 	 *     and there were changes
341 	 *
342 	 *  The state structure must be locked!
343 	 */
344 
345 	switch (event) {
346 	case XFRM_REPLAY_UPDATE:
347 		if (x->replay_maxdiff) {
348 			if (replay_esn->seq_hi == preplay_esn->seq_hi)
349 				seq_diff = replay_esn->seq - preplay_esn->seq;
350 			else
351 				seq_diff = ~preplay_esn->seq + replay_esn->seq
352 					   + 1;
353 
354 			if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
355 				oseq_diff = replay_esn->oseq
356 					    - preplay_esn->oseq;
357 			else
358 				oseq_diff = ~preplay_esn->oseq
359 					    + replay_esn->oseq + 1;
360 
361 			if (seq_diff >= x->replay_maxdiff ||
362 			    oseq_diff >= x->replay_maxdiff)
363 				break;
364 		}
365 
366 		if (x->xflags & XFRM_TIME_DEFER)
367 			event = XFRM_REPLAY_TIMEOUT;
368 		else
369 			return;
370 
371 		break;
372 
373 	case XFRM_REPLAY_TIMEOUT:
374 		if (memcmp(x->replay_esn, x->preplay_esn,
375 			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
376 			x->xflags |= XFRM_TIME_DEFER;
377 			return;
378 		}
379 
380 		break;
381 	}
382 
383 	memcpy(x->preplay_esn, x->replay_esn,
384 	       xfrm_replay_state_esn_len(replay_esn));
385 	c.event = XFRM_MSG_NEWAE;
386 	c.data.aevent = event;
387 	km_state_notify(x, &c);
388 
389 	if (x->replay_maxage &&
390 	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
391 		x->xflags &= ~XFRM_TIME_DEFER;
392 }
393 
394 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
395 {
396 	int err = 0;
397 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
398 	struct net *net = xs_net(x);
399 
400 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
401 		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
402 		XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
403 
404 		if (unlikely(replay_esn->oseq == 0)) {
405 			XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
406 
407 			if (replay_esn->oseq_hi == 0) {
408 				replay_esn->oseq--;
409 				replay_esn->oseq_hi--;
410 				xfrm_audit_state_replay_overflow(x, skb);
411 				err = -EOVERFLOW;
412 
413 				return err;
414 			}
415 		}
416 		if (xfrm_aevent_is_on(net))
417 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
418 	}
419 
420 	return err;
421 }
422 
423 static int xfrm_replay_check_esn(struct xfrm_state *x,
424 				 struct sk_buff *skb, __be32 net_seq)
425 {
426 	unsigned int bitnr, nr;
427 	u32 diff;
428 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
429 	u32 pos;
430 	u32 seq = ntohl(net_seq);
431 	u32 wsize = replay_esn->replay_window;
432 	u32 top = replay_esn->seq;
433 	u32 bottom = top - wsize + 1;
434 
435 	if (!wsize)
436 		return 0;
437 
438 	if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
439 		     (replay_esn->seq < replay_esn->replay_window - 1)))
440 		goto err;
441 
442 	diff = top - seq;
443 
444 	if (likely(top >= wsize - 1)) {
445 		/* A. same subspace */
446 		if (likely(seq > top) || seq < bottom)
447 			return 0;
448 	} else {
449 		/* B. window spans two subspaces */
450 		if (likely(seq > top && seq < bottom))
451 			return 0;
452 		if (seq >= bottom)
453 			diff = ~seq + top + 1;
454 	}
455 
456 	if (diff >= replay_esn->replay_window) {
457 		x->stats.replay_window++;
458 		goto err;
459 	}
460 
461 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
462 
463 	if (pos >= diff)
464 		bitnr = (pos - diff) % replay_esn->replay_window;
465 	else
466 		bitnr = replay_esn->replay_window - (diff - pos);
467 
468 	nr = bitnr >> 5;
469 	bitnr = bitnr & 0x1F;
470 	if (replay_esn->bmp[nr] & (1U << bitnr))
471 		goto err_replay;
472 
473 	return 0;
474 
475 err_replay:
476 	x->stats.replay++;
477 err:
478 	xfrm_audit_state_replay(x, skb, net_seq);
479 	return -EINVAL;
480 }
481 
482 static int xfrm_replay_recheck_esn(struct xfrm_state *x,
483 				   struct sk_buff *skb, __be32 net_seq)
484 {
485 	if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
486 		     htonl(xfrm_replay_seqhi(x, net_seq)))) {
487 			x->stats.replay_window++;
488 			return -EINVAL;
489 	}
490 
491 	return xfrm_replay_check_esn(x, skb, net_seq);
492 }
493 
494 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
495 {
496 	unsigned int bitnr, nr, i;
497 	int wrap;
498 	u32 diff, pos, seq, seq_hi;
499 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
500 
501 	if (!replay_esn->replay_window)
502 		return;
503 
504 	seq = ntohl(net_seq);
505 	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
506 	seq_hi = xfrm_replay_seqhi(x, net_seq);
507 	wrap = seq_hi - replay_esn->seq_hi;
508 
509 	if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
510 		if (likely(!wrap))
511 			diff = seq - replay_esn->seq;
512 		else
513 			diff = ~replay_esn->seq + seq + 1;
514 
515 		if (diff < replay_esn->replay_window) {
516 			for (i = 1; i < diff; i++) {
517 				bitnr = (pos + i) % replay_esn->replay_window;
518 				nr = bitnr >> 5;
519 				bitnr = bitnr & 0x1F;
520 				replay_esn->bmp[nr] &=  ~(1U << bitnr);
521 			}
522 		} else {
523 			nr = (replay_esn->replay_window - 1) >> 5;
524 			for (i = 0; i <= nr; i++)
525 				replay_esn->bmp[i] = 0;
526 		}
527 
528 		bitnr = (pos + diff) % replay_esn->replay_window;
529 		replay_esn->seq = seq;
530 
531 		if (unlikely(wrap > 0))
532 			replay_esn->seq_hi++;
533 	} else {
534 		diff = replay_esn->seq - seq;
535 
536 		if (pos >= diff)
537 			bitnr = (pos - diff) % replay_esn->replay_window;
538 		else
539 			bitnr = replay_esn->replay_window - (diff - pos);
540 	}
541 
542 	xfrm_dev_state_advance_esn(x);
543 
544 	nr = bitnr >> 5;
545 	bitnr = bitnr & 0x1F;
546 	replay_esn->bmp[nr] |= (1U << bitnr);
547 
548 	if (xfrm_aevent_is_on(xs_net(x)))
549 		x->repl->notify(x, XFRM_REPLAY_UPDATE);
550 }
551 
552 #ifdef CONFIG_XFRM_OFFLOAD
553 static int xfrm_replay_overflow_offload(struct xfrm_state *x, struct sk_buff *skb)
554 {
555 	int err = 0;
556 	struct net *net = xs_net(x);
557 	struct xfrm_offload *xo = xfrm_offload(skb);
558 	__u32 oseq = x->replay.oseq;
559 
560 	if (!xo)
561 		return xfrm_replay_overflow(x, skb);
562 
563 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
564 		if (!skb_is_gso(skb)) {
565 			XFRM_SKB_CB(skb)->seq.output.low = ++oseq;
566 			xo->seq.low = oseq;
567 		} else {
568 			XFRM_SKB_CB(skb)->seq.output.low = oseq + 1;
569 			xo->seq.low = oseq + 1;
570 			oseq += skb_shinfo(skb)->gso_segs;
571 		}
572 
573 		XFRM_SKB_CB(skb)->seq.output.hi = 0;
574 		xo->seq.hi = 0;
575 		if (unlikely(oseq < x->replay.oseq)) {
576 			xfrm_audit_state_replay_overflow(x, skb);
577 			err = -EOVERFLOW;
578 
579 			return err;
580 		}
581 
582 		x->replay.oseq = oseq;
583 
584 		if (xfrm_aevent_is_on(net))
585 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
586 	}
587 
588 	return err;
589 }
590 
591 static int xfrm_replay_overflow_offload_bmp(struct xfrm_state *x, struct sk_buff *skb)
592 {
593 	int err = 0;
594 	struct xfrm_offload *xo = xfrm_offload(skb);
595 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
596 	struct net *net = xs_net(x);
597 	__u32 oseq = replay_esn->oseq;
598 
599 	if (!xo)
600 		return xfrm_replay_overflow_bmp(x, skb);
601 
602 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
603 		if (!skb_is_gso(skb)) {
604 			XFRM_SKB_CB(skb)->seq.output.low = ++oseq;
605 			xo->seq.low = oseq;
606 		} else {
607 			XFRM_SKB_CB(skb)->seq.output.low = oseq + 1;
608 			xo->seq.low = oseq + 1;
609 			oseq += skb_shinfo(skb)->gso_segs;
610 		}
611 
612 		XFRM_SKB_CB(skb)->seq.output.hi = 0;
613 		xo->seq.hi = 0;
614 		if (unlikely(oseq < replay_esn->oseq)) {
615 			xfrm_audit_state_replay_overflow(x, skb);
616 			err = -EOVERFLOW;
617 
618 			return err;
619 		} else {
620 			replay_esn->oseq = oseq;
621 		}
622 
623 		if (xfrm_aevent_is_on(net))
624 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
625 	}
626 
627 	return err;
628 }
629 
630 static int xfrm_replay_overflow_offload_esn(struct xfrm_state *x, struct sk_buff *skb)
631 {
632 	int err = 0;
633 	struct xfrm_offload *xo = xfrm_offload(skb);
634 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
635 	struct net *net = xs_net(x);
636 	__u32 oseq = replay_esn->oseq;
637 	__u32 oseq_hi = replay_esn->oseq_hi;
638 
639 	if (!xo)
640 		return xfrm_replay_overflow_esn(x, skb);
641 
642 	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
643 		if (!skb_is_gso(skb)) {
644 			XFRM_SKB_CB(skb)->seq.output.low = ++oseq;
645 			XFRM_SKB_CB(skb)->seq.output.hi = oseq_hi;
646 			xo->seq.low = oseq;
647 			xo->seq.hi = oseq_hi;
648 		} else {
649 			XFRM_SKB_CB(skb)->seq.output.low = oseq + 1;
650 			XFRM_SKB_CB(skb)->seq.output.hi = oseq_hi;
651 			xo->seq.low = oseq + 1;
652 			xo->seq.hi = oseq_hi;
653 			oseq += skb_shinfo(skb)->gso_segs;
654 		}
655 
656 		if (unlikely(oseq < replay_esn->oseq)) {
657 			XFRM_SKB_CB(skb)->seq.output.hi = ++oseq_hi;
658 			xo->seq.hi = oseq_hi;
659 			replay_esn->oseq_hi = oseq_hi;
660 			if (replay_esn->oseq_hi == 0) {
661 				replay_esn->oseq--;
662 				replay_esn->oseq_hi--;
663 				xfrm_audit_state_replay_overflow(x, skb);
664 				err = -EOVERFLOW;
665 
666 				return err;
667 			}
668 		}
669 
670 		replay_esn->oseq = oseq;
671 
672 		if (xfrm_aevent_is_on(net))
673 			x->repl->notify(x, XFRM_REPLAY_UPDATE);
674 	}
675 
676 	return err;
677 }
678 
679 static const struct xfrm_replay xfrm_replay_legacy = {
680 	.advance	= xfrm_replay_advance,
681 	.check		= xfrm_replay_check,
682 	.recheck	= xfrm_replay_check,
683 	.notify		= xfrm_replay_notify,
684 	.overflow	= xfrm_replay_overflow_offload,
685 };
686 
687 static const struct xfrm_replay xfrm_replay_bmp = {
688 	.advance	= xfrm_replay_advance_bmp,
689 	.check		= xfrm_replay_check_bmp,
690 	.recheck	= xfrm_replay_check_bmp,
691 	.notify		= xfrm_replay_notify_bmp,
692 	.overflow	= xfrm_replay_overflow_offload_bmp,
693 };
694 
695 static const struct xfrm_replay xfrm_replay_esn = {
696 	.advance	= xfrm_replay_advance_esn,
697 	.check		= xfrm_replay_check_esn,
698 	.recheck	= xfrm_replay_recheck_esn,
699 	.notify		= xfrm_replay_notify_esn,
700 	.overflow	= xfrm_replay_overflow_offload_esn,
701 };
702 #else
703 static const struct xfrm_replay xfrm_replay_legacy = {
704 	.advance	= xfrm_replay_advance,
705 	.check		= xfrm_replay_check,
706 	.recheck	= xfrm_replay_check,
707 	.notify		= xfrm_replay_notify,
708 	.overflow	= xfrm_replay_overflow,
709 };
710 
711 static const struct xfrm_replay xfrm_replay_bmp = {
712 	.advance	= xfrm_replay_advance_bmp,
713 	.check		= xfrm_replay_check_bmp,
714 	.recheck	= xfrm_replay_check_bmp,
715 	.notify		= xfrm_replay_notify_bmp,
716 	.overflow	= xfrm_replay_overflow_bmp,
717 };
718 
719 static const struct xfrm_replay xfrm_replay_esn = {
720 	.advance	= xfrm_replay_advance_esn,
721 	.check		= xfrm_replay_check_esn,
722 	.recheck	= xfrm_replay_recheck_esn,
723 	.notify		= xfrm_replay_notify_esn,
724 	.overflow	= xfrm_replay_overflow_esn,
725 };
726 #endif
727 
728 int xfrm_init_replay(struct xfrm_state *x)
729 {
730 	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
731 
732 	if (replay_esn) {
733 		if (replay_esn->replay_window >
734 		    replay_esn->bmp_len * sizeof(__u32) * 8)
735 			return -EINVAL;
736 
737 		if (x->props.flags & XFRM_STATE_ESN) {
738 			if (replay_esn->replay_window == 0)
739 				return -EINVAL;
740 			x->repl = &xfrm_replay_esn;
741 		} else {
742 			x->repl = &xfrm_replay_bmp;
743 		}
744 	} else {
745 		x->repl = &xfrm_replay_legacy;
746 	}
747 
748 	return 0;
749 }
750 EXPORT_SYMBOL(xfrm_init_replay);
751