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 >= 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
 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                 x->repl->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;
 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
 286 static 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
 337 static 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
 403 static 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
 432 static 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
 484 err_replay:
 485         x->stats.replay++;
 486 err:
 487         xfrm_audit_state_replay(x, skb, net_seq);
 488         return -EINVAL;
 489 }
 490
 491 static 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
 503 static 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
 559 static 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
 567 static 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
 575 static 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
 583 int 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 }
 603 EXPORT_SYMBOL(xfrm_init_replay);