Root/net/xfrm/xfrm_replay.c

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
24u32 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
49static 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
95static 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
116static 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
143err:
144    xfrm_audit_state_replay(x, skb, net_seq);
145    return -EINVAL;
146}
147
148static 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
172static 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
194static 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
231err_replay:
232    x->stats.replay++;
233err:
234    xfrm_audit_state_replay(x, skb, net_seq);
235    return -EINVAL;
236}
237
238static 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
286static 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
337static 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
403static 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
432static 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
484err_replay:
485    x->stats.replay++;
486err:
487    xfrm_audit_state_replay(x, skb, net_seq);
488    return -EINVAL;
489}
490
491static 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
503static 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
559static 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
567static 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
575static 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
583int 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}
603EXPORT_SYMBOL(xfrm_init_replay);
604

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