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