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[linux-2.6/next.git] / net / xfrm / xfrm_replay.c
blobb11ea692bd7d0870c8586e115bcfc6b6a69c2997
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 <net/xfrm.h>
22
23 u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq)
24 {
25 u32 seq, seq_hi, bottom;
26 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
27
28 if (!(x->props.flags & XFRM_STATE_ESN))
29 return 0;
30
31 seq = ntohl(net_seq);
32 seq_hi = replay_esn->seq_hi;
33 bottom = replay_esn->seq - replay_esn->replay_window + 1;
34
35 if (likely(replay_esn->seq >= replay_esn->replay_window - 1)) {
36 /* A. same subspace */
37 if (unlikely(seq < bottom))
38 seq_hi++;
39 } else {
40 /* B. window spans two subspaces */
41 if (unlikely(seq >= bottom))
42 seq_hi--;
43 }
44
45 return seq_hi;
46 }
47
48 static void xfrm_replay_notify(struct xfrm_state *x, int event)
49 {
50 struct km_event c;
51 /* we send notify messages in case
52 * 1. we updated on of the sequence numbers, and the seqno difference
53 * is at least x->replay_maxdiff, in this case we also update the
54 * timeout of our timer function
55 * 2. if x->replay_maxage has elapsed since last update,
56 * and there were changes
57 *
58 * The state structure must be locked!
59 */
60
61 switch (event) {
62 case XFRM_REPLAY_UPDATE:
63 if (x->replay_maxdiff &&
64 (x->replay.seq - x->preplay.seq < x->replay_maxdiff) &&
65 (x->replay.oseq - x->preplay.oseq < x->replay_maxdiff)) {
66 if (x->xflags & XFRM_TIME_DEFER)
67 event = XFRM_REPLAY_TIMEOUT;
68 else
69 return;
70 }
71
72 break;
73
74 case XFRM_REPLAY_TIMEOUT:
75 if (memcmp(&x->replay, &x->preplay,
76 sizeof(struct xfrm_replay_state)) == 0) {
77 x->xflags |= XFRM_TIME_DEFER;
78 return;
79 }
80
81 break;
82 }
83
84 memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state));
85 c.event = XFRM_MSG_NEWAE;
86 c.data.aevent = event;
87 km_state_notify(x, &c);
88
89 if (x->replay_maxage &&
90 !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
91 x->xflags &= ~XFRM_TIME_DEFER;
92 }
93
94 static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
95 {
96 int err = 0;
97 struct net *net = xs_net(x);
98
99 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
100 XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
101 if (unlikely(x->replay.oseq == 0)) {
102 x->replay.oseq--;
103 xfrm_audit_state_replay_overflow(x, skb);
104 err = -EOVERFLOW;
105
106 return err;
107 }
108 if (xfrm_aevent_is_on(net))
109 x->repl->notify(x, XFRM_REPLAY_UPDATE);
110 }
111
112 return err;
113 }
114
115 static int xfrm_replay_check(struct xfrm_state *x,
116 struct sk_buff *skb, __be32 net_seq)
117 {
118 u32 diff;
119 u32 seq = ntohl(net_seq);
120
121 if (!x->props.replay_window)
122 return 0;
123
124 if (unlikely(seq == 0))
125 goto err;
126
127 if (likely(seq > x->replay.seq))
128 return 0;
129
130 diff = x->replay.seq - seq;
131 if (diff >= min_t(unsigned int, x->props.replay_window,
132 sizeof(x->replay.bitmap) * 8)) {
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 xfrm_replay_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 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
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 if (pos >= diff) {
220 bitnr = (pos - diff) % replay_esn->replay_window;
221 nr = bitnr >> 5;
222 bitnr = bitnr & 0x1F;
223 if (replay_esn->bmp[nr] & (1U << bitnr))
224 goto err_replay;
225 } else {
226 bitnr = replay_esn->replay_window - (diff - pos);
227 nr = bitnr >> 5;
228 bitnr = bitnr & 0x1F;
229 if (replay_esn->bmp[nr] & (1U << bitnr))
230 goto err_replay;
231 }
232 return 0;
233
234 err_replay:
235 x->stats.replay++;
236 err:
237 xfrm_audit_state_replay(x, skb, net_seq);
238 return -EINVAL;
239 }
240
241 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
242 {
243 unsigned int bitnr, nr, i;
244 u32 diff;
245 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
246 u32 seq = ntohl(net_seq);
247 u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
248
249 if (!replay_esn->replay_window)
250 return;
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
263 bitnr = (pos + diff) % replay_esn->replay_window;
264 nr = bitnr >> 5;
265 bitnr = bitnr & 0x1F;
266 replay_esn->bmp[nr] |= (1U << bitnr);
267 } else {
268 nr = (replay_esn->replay_window - 1) >> 5;
269 for (i = 0; i <= nr; i++)
270 replay_esn->bmp[i] = 0;
271
272 bitnr = (pos + diff) % replay_esn->replay_window;
273 nr = bitnr >> 5;
274 bitnr = bitnr & 0x1F;
275 replay_esn->bmp[nr] |= (1U << bitnr);
276 }
277
278 replay_esn->seq = seq;
279 } else {
280 diff = replay_esn->seq - seq;
281
282 if (pos >= diff) {
283 bitnr = (pos - diff) % replay_esn->replay_window;
284 nr = bitnr >> 5;
285 bitnr = bitnr & 0x1F;
286 replay_esn->bmp[nr] |= (1U << bitnr);
287 } else {
288 bitnr = replay_esn->replay_window - (diff - pos);
289 nr = bitnr >> 5;
290 bitnr = bitnr & 0x1F;
291 replay_esn->bmp[nr] |= (1U << bitnr);
292 }
293 }
294
295 if (xfrm_aevent_is_on(xs_net(x)))
296 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
297 }
298
299 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
300 {
301 struct km_event c;
302 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
303 struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
304
305 /* we send notify messages in case
306 * 1. we updated on of the sequence numbers, and the seqno difference
307 * is at least x->replay_maxdiff, in this case we also update the
308 * timeout of our timer function
309 * 2. if x->replay_maxage has elapsed since last update,
310 * and there were changes
311 *
312 * The state structure must be locked!
313 */
314
315 switch (event) {
316 case XFRM_REPLAY_UPDATE:
317 if (x->replay_maxdiff &&
318 (replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
319 (replay_esn->oseq - preplay_esn->oseq < x->replay_maxdiff)) {
320 if (x->xflags & XFRM_TIME_DEFER)
321 event = XFRM_REPLAY_TIMEOUT;
322 else
323 return;
324 }
325
326 break;
327
328 case XFRM_REPLAY_TIMEOUT:
329 if (memcmp(x->replay_esn, x->preplay_esn,
330 xfrm_replay_state_esn_len(replay_esn)) == 0) {
331 x->xflags |= XFRM_TIME_DEFER;
332 return;
333 }
334
335 break;
336 }
337
338 memcpy(x->preplay_esn, x->replay_esn,
339 xfrm_replay_state_esn_len(replay_esn));
340 c.event = XFRM_MSG_NEWAE;
341 c.data.aevent = event;
342 km_state_notify(x, &c);
343
344 if (x->replay_maxage &&
345 !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
346 x->xflags &= ~XFRM_TIME_DEFER;
347 }
348
349 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
350 {
351 int err = 0;
352 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
353 struct net *net = xs_net(x);
354
355 if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
356 XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
357 XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
358
359 if (unlikely(replay_esn->oseq == 0)) {
360 XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
361
362 if (replay_esn->oseq_hi == 0) {
363 replay_esn->oseq--;
364 replay_esn->oseq_hi--;
365 xfrm_audit_state_replay_overflow(x, skb);
366 err = -EOVERFLOW;
367
368 return err;
369 }
370 }
371 if (xfrm_aevent_is_on(net))
372 x->repl->notify(x, XFRM_REPLAY_UPDATE);
373 }
374
375 return err;
376 }
377
378 static int xfrm_replay_check_esn(struct xfrm_state *x,
379 struct sk_buff *skb, __be32 net_seq)
380 {
381 unsigned int bitnr, nr;
382 u32 diff;
383 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
384 u32 pos;
385 u32 seq = ntohl(net_seq);
386 u32 wsize = replay_esn->replay_window;
387 u32 top = replay_esn->seq;
388 u32 bottom = top - wsize + 1;
389
390 if (!wsize)
391 return 0;
392
393 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
394
395 if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
396 (replay_esn->seq < replay_esn->replay_window - 1)))
397 goto err;
398
399 diff = top - seq;
400
401 if (likely(top >= wsize - 1)) {
402 /* A. same subspace */
403 if (likely(seq > top) || seq < bottom)
404 return 0;
405 } else {
406 /* B. window spans two subspaces */
407 if (likely(seq > top && seq < bottom))
408 return 0;
409 if (seq >= bottom)
410 diff = ~seq + top + 1;
411 }
412
413 if (diff >= replay_esn->replay_window) {
414 x->stats.replay_window++;
415 goto err;
416 }
417
418 if (pos >= diff) {
419 bitnr = (pos - diff) % replay_esn->replay_window;
420 nr = bitnr >> 5;
421 bitnr = bitnr & 0x1F;
422 if (replay_esn->bmp[nr] & (1U << bitnr))
423 goto err_replay;
424 } else {
425 bitnr = replay_esn->replay_window - (diff - pos);
426 nr = bitnr >> 5;
427 bitnr = bitnr & 0x1F;
428 if (replay_esn->bmp[nr] & (1U << bitnr))
429 goto err_replay;
430 }
431 return 0;
432
433 err_replay:
434 x->stats.replay++;
435 err:
436 xfrm_audit_state_replay(x, skb, net_seq);
437 return -EINVAL;
438 }
439
440 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
441 {
442 unsigned int bitnr, nr, i;
443 int wrap;
444 u32 diff, pos, seq, seq_hi;
445 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
446
447 if (!replay_esn->replay_window)
448 return;
449
450 seq = ntohl(net_seq);
451 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
452 seq_hi = xfrm_replay_seqhi(x, net_seq);
453 wrap = seq_hi - replay_esn->seq_hi;
454
455 if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
456 if (likely(!wrap))
457 diff = seq - replay_esn->seq;
458 else
459 diff = ~replay_esn->seq + seq + 1;
460
461 if (diff < replay_esn->replay_window) {
462 for (i = 1; i < diff; i++) {
463 bitnr = (pos + i) % replay_esn->replay_window;
464 nr = bitnr >> 5;
465 bitnr = bitnr & 0x1F;
466 replay_esn->bmp[nr] &= ~(1U << bitnr);
467 }
468
469 bitnr = (pos + diff) % replay_esn->replay_window;
470 nr = bitnr >> 5;
471 bitnr = bitnr & 0x1F;
472 replay_esn->bmp[nr] |= (1U << bitnr);
473 } else {
474 nr = (replay_esn->replay_window - 1) >> 5;
475 for (i = 0; i <= nr; i++)
476 replay_esn->bmp[i] = 0;
477
478 bitnr = (pos + diff) % replay_esn->replay_window;
479 nr = bitnr >> 5;
480 bitnr = bitnr & 0x1F;
481 replay_esn->bmp[nr] |= (1U << bitnr);
482 }
483
484 replay_esn->seq = seq;
485
486 if (unlikely(wrap > 0))
487 replay_esn->seq_hi++;
488 } else {
489 diff = replay_esn->seq - seq;
490
491 if (pos >= diff) {
492 bitnr = (pos - diff) % replay_esn->replay_window;
493 nr = bitnr >> 5;
494 bitnr = bitnr & 0x1F;
495 replay_esn->bmp[nr] |= (1U << bitnr);
496 } else {
497 bitnr = replay_esn->replay_window - (diff - pos);
498 nr = bitnr >> 5;
499 bitnr = bitnr & 0x1F;
500 replay_esn->bmp[nr] |= (1U << bitnr);
501 }
502 }
503
504 if (xfrm_aevent_is_on(xs_net(x)))
505 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
506 }
507
508 static struct xfrm_replay xfrm_replay_legacy = {
509 .advance = xfrm_replay_advance,
510 .check = xfrm_replay_check,
511 .notify = xfrm_replay_notify,
512 .overflow = xfrm_replay_overflow,
513 };
514
515 static struct xfrm_replay xfrm_replay_bmp = {
516 .advance = xfrm_replay_advance_bmp,
517 .check = xfrm_replay_check_bmp,
518 .notify = xfrm_replay_notify_bmp,
519 .overflow = xfrm_replay_overflow_bmp,
520 };
521
522 static struct xfrm_replay xfrm_replay_esn = {
523 .advance = xfrm_replay_advance_esn,
524 .check = xfrm_replay_check_esn,
525 .notify = xfrm_replay_notify_bmp,
526 .overflow = xfrm_replay_overflow_esn,
527 };
528
529 int xfrm_init_replay(struct xfrm_state *x)
530 {
531 struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
532
533 if (replay_esn) {
534 if (replay_esn->replay_window >
535 replay_esn->bmp_len * sizeof(__u32) * 8)
536 return -EINVAL;
537
538 if ((x->props.flags & XFRM_STATE_ESN) && replay_esn->replay_window == 0)
539 return -EINVAL;
540
541 if ((x->props.flags & XFRM_STATE_ESN) && x->replay_esn)
542 x->repl = &xfrm_replay_esn;
543 else
544 x->repl = &xfrm_replay_bmp;
545 } else
546 x->repl = &xfrm_replay_legacy;
547
548 return 0;
549 }
550 EXPORT_SYMBOL(xfrm_init_replay);
linux-next