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[linux-3.10.git] / 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
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 >= min_t(unsigned int, x->props.replay_window,
133                           sizeof(x->replay.bitmap) * 8)) {
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                 if (unlikely(replay_esn->oseq == 0)) {
182                         replay_esn->oseq--;
183                         xfrm_audit_state_replay_overflow(x, skb);
184                         err = -EOVERFLOW;
185
186                         return err;
187                 }
188                 if (xfrm_aevent_is_on(net))
189                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
190         }
191
192         return err;
193 }
194
195 static int xfrm_replay_check_bmp(struct xfrm_state *x,
196                                  struct sk_buff *skb, __be32 net_seq)
197 {
198         unsigned int bitnr, nr;
199         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
200         u32 pos;
201         u32 seq = ntohl(net_seq);
202         u32 diff =  replay_esn->seq - seq;
203
204         if (!replay_esn->replay_window)
205                 return 0;
206
207         if (unlikely(seq == 0))
208                 goto err;
209
210         if (likely(seq > replay_esn->seq))
211                 return 0;
212
213         if (diff >= replay_esn->replay_window) {
214                 x->stats.replay_window++;
215                 goto err;
216         }
217
218         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
219
220         if (pos >= diff)
221                 bitnr = (pos - diff) % replay_esn->replay_window;
222         else
223                 bitnr = replay_esn->replay_window - (diff - pos);
224
225         nr = bitnr >> 5;
226         bitnr = bitnr & 0x1F;
227         if (replay_esn->bmp[nr] & (1U << bitnr))
228                 goto err_replay;
229
230         return 0;
231
232 err_replay:
233         x->stats.replay++;
234 err:
235         xfrm_audit_state_replay(x, skb, net_seq);
236         return -EINVAL;
237 }
238
239 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
240 {
241         unsigned int bitnr, nr, i;
242         u32 diff;
243         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
244         u32 seq = ntohl(net_seq);
245         u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
246
247         if (!replay_esn->replay_window)
248                 return;
249
250         if (seq > replay_esn->seq) {
251                 diff = seq - replay_esn->seq;
252
253                 if (diff < replay_esn->replay_window) {
254                         for (i = 1; i < diff; i++) {
255                                 bitnr = (pos + i) % replay_esn->replay_window;
256                                 nr = bitnr >> 5;
257                                 bitnr = bitnr & 0x1F;
258                                 replay_esn->bmp[nr] &=  ~(1U << bitnr);
259                         }
260                 } else {
261                         nr = (replay_esn->replay_window - 1) >> 5;
262                         for (i = 0; i <= nr; i++)
263                                 replay_esn->bmp[i] = 0;
264                 }
265
266                 bitnr = (pos + diff) % replay_esn->replay_window;
267                 replay_esn->seq = seq;
268         } else {
269                 diff = replay_esn->seq - seq;
270
271                 if (pos >= diff)
272                         bitnr = (pos - diff) % replay_esn->replay_window;
273                 else
274                         bitnr = replay_esn->replay_window - (diff - pos);
275         }
276
277         nr = bitnr >> 5;
278         bitnr = bitnr & 0x1F;
279         replay_esn->bmp[nr] |= (1U << bitnr);
280
281         if (xfrm_aevent_is_on(xs_net(x)))
282                 x->repl->notify(x, XFRM_REPLAY_UPDATE);
283 }
284
285 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
286 {
287         struct km_event c;
288         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
289         struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
290
291         /* we send notify messages in case
292          *  1. we updated on of the sequence numbers, and the seqno difference
293          *     is at least x->replay_maxdiff, in this case we also update the
294          *     timeout of our timer function
295          *  2. if x->replay_maxage has elapsed since last update,
296          *     and there were changes
297          *
298          *  The state structure must be locked!
299          */
300
301         switch (event) {
302         case XFRM_REPLAY_UPDATE:
303                 if (x->replay_maxdiff &&
304                     (replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
305                     (replay_esn->oseq - preplay_esn->oseq < x->replay_maxdiff)) {
306                         if (x->xflags & XFRM_TIME_DEFER)
307                                 event = XFRM_REPLAY_TIMEOUT;
308                         else
309                                 return;
310                 }
311
312                 break;
313
314         case XFRM_REPLAY_TIMEOUT:
315                 if (memcmp(x->replay_esn, x->preplay_esn,
316                            xfrm_replay_state_esn_len(replay_esn)) == 0) {
317                         x->xflags |= XFRM_TIME_DEFER;
318                         return;
319                 }
320
321                 break;
322         }
323
324         memcpy(x->preplay_esn, x->replay_esn,
325                xfrm_replay_state_esn_len(replay_esn));
326         c.event = XFRM_MSG_NEWAE;
327         c.data.aevent = event;
328         km_state_notify(x, &c);
329
330         if (x->replay_maxage &&
331             !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
332                 x->xflags &= ~XFRM_TIME_DEFER;
333 }
334
335 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
336 {
337         int err = 0;
338         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
339         struct net *net = xs_net(x);
340
341         if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
342                 XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
343                 XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
344
345                 if (unlikely(replay_esn->oseq == 0)) {
346                         XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
347
348                         if (replay_esn->oseq_hi == 0) {
349                                 replay_esn->oseq--;
350                                 replay_esn->oseq_hi--;
351                                 xfrm_audit_state_replay_overflow(x, skb);
352                                 err = -EOVERFLOW;
353
354                                 return err;
355                         }
356                 }
357                 if (xfrm_aevent_is_on(net))
358                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
359         }
360
361         return err;
362 }
363
364 static int xfrm_replay_check_esn(struct xfrm_state *x,
365                                  struct sk_buff *skb, __be32 net_seq)
366 {
367         unsigned int bitnr, nr;
368         u32 diff;
369         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
370         u32 pos;
371         u32 seq = ntohl(net_seq);
372         u32 wsize = replay_esn->replay_window;
373         u32 top = replay_esn->seq;
374         u32 bottom = top - wsize + 1;
375
376         if (!wsize)
377                 return 0;
378
379         if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
380                      (replay_esn->seq < replay_esn->replay_window - 1)))
381                 goto err;
382
383         diff = top - seq;
384
385         if (likely(top >= wsize - 1)) {
386                 /* A. same subspace */
387                 if (likely(seq > top) || seq < bottom)
388                         return 0;
389         } else {
390                 /* B. window spans two subspaces */
391                 if (likely(seq > top && seq < bottom))
392                         return 0;
393                 if (seq >= bottom)
394                         diff = ~seq + top + 1;
395         }
396
397         if (diff >= replay_esn->replay_window) {
398                 x->stats.replay_window++;
399                 goto err;
400         }
401
402         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
403
404         if (pos >= diff)
405                 bitnr = (pos - diff) % replay_esn->replay_window;
406         else
407                 bitnr = replay_esn->replay_window - (diff - pos);
408
409         nr = bitnr >> 5;
410         bitnr = bitnr & 0x1F;
411         if (replay_esn->bmp[nr] & (1U << bitnr))
412                 goto err_replay;
413
414         return 0;
415
416 err_replay:
417         x->stats.replay++;
418 err:
419         xfrm_audit_state_replay(x, skb, net_seq);
420         return -EINVAL;
421 }
422
423 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
424 {
425         unsigned int bitnr, nr, i;
426         int wrap;
427         u32 diff, pos, seq, seq_hi;
428         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
429
430         if (!replay_esn->replay_window)
431                 return;
432
433         seq = ntohl(net_seq);
434         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
435         seq_hi = xfrm_replay_seqhi(x, net_seq);
436         wrap = seq_hi - replay_esn->seq_hi;
437
438         if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
439                 if (likely(!wrap))
440                         diff = seq - replay_esn->seq;
441                 else
442                         diff = ~replay_esn->seq + seq + 1;
443
444                 if (diff < replay_esn->replay_window) {
445                         for (i = 1; i < diff; i++) {
446                                 bitnr = (pos + i) % replay_esn->replay_window;
447                                 nr = bitnr >> 5;
448                                 bitnr = bitnr & 0x1F;
449                                 replay_esn->bmp[nr] &=  ~(1U << bitnr);
450                         }
451                 } else {
452                         nr = (replay_esn->replay_window - 1) >> 5;
453                         for (i = 0; i <= nr; i++)
454                                 replay_esn->bmp[i] = 0;
455                 }
456
457                 bitnr = (pos + diff) % replay_esn->replay_window;
458                 replay_esn->seq = seq;
459
460                 if (unlikely(wrap > 0))
461                         replay_esn->seq_hi++;
462         } else {
463                 diff = replay_esn->seq - seq;
464
465                 if (pos >= diff)
466                         bitnr = (pos - diff) % replay_esn->replay_window;
467                 else
468                         bitnr = replay_esn->replay_window - (diff - pos);
469         }
470
471         nr = bitnr >> 5;
472         bitnr = bitnr & 0x1F;
473         replay_esn->bmp[nr] |= (1U << bitnr);
474
475         if (xfrm_aevent_is_on(xs_net(x)))
476                 x->repl->notify(x, XFRM_REPLAY_UPDATE);
477 }
478
479 static struct xfrm_replay xfrm_replay_legacy = {
480         .advance        = xfrm_replay_advance,
481         .check          = xfrm_replay_check,
482         .notify         = xfrm_replay_notify,
483         .overflow       = xfrm_replay_overflow,
484 };
485
486 static struct xfrm_replay xfrm_replay_bmp = {
487         .advance        = xfrm_replay_advance_bmp,
488         .check          = xfrm_replay_check_bmp,
489         .notify         = xfrm_replay_notify_bmp,
490         .overflow       = xfrm_replay_overflow_bmp,
491 };
492
493 static struct xfrm_replay xfrm_replay_esn = {
494         .advance        = xfrm_replay_advance_esn,
495         .check          = xfrm_replay_check_esn,
496         .notify         = xfrm_replay_notify_bmp,
497         .overflow       = xfrm_replay_overflow_esn,
498 };
499
500 int xfrm_init_replay(struct xfrm_state *x)
501 {
502         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
503
504         if (replay_esn) {
505                 if (replay_esn->replay_window >
506                     replay_esn->bmp_len * sizeof(__u32) * 8)
507                         return -EINVAL;
508
509         if ((x->props.flags & XFRM_STATE_ESN) && replay_esn->replay_window == 0)
510                 return -EINVAL;
511
512         if ((x->props.flags & XFRM_STATE_ESN) && x->replay_esn)
513                 x->repl = &xfrm_replay_esn;
514         else
515                 x->repl = &xfrm_replay_bmp;
516         } else
517                 x->repl = &xfrm_replay_legacy;
518
519         return 0;
520 }
521 EXPORT_SYMBOL(xfrm_init_replay);