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                 XFRM_SKB_CB(skb)->seq.output.hi = 0;
 103                 if (unlikely(x->replay.oseq == 0)) {
 104                         x->replay.oseq--;
 105                         xfrm_audit_state_replay_overflow(x, skb);
 106                         err = -EOVERFLOW;
 107
 108                         return err;
 109                 }
 110                 if (xfrm_aevent_is_on(net))
 111                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
 112         }
 113
 114         return err;
 115 }
 116
 117 static int xfrm_replay_check(struct xfrm_state *x,
 118                       struct sk_buff *skb, __be32 net_seq)
 119 {
 120         u32 diff;
 121         u32 seq = ntohl(net_seq);
 122
 123         if (!x->props.replay_window)
 124                 return 0;
 125
 126         if (unlikely(seq == 0))
 127                 goto err;
 128
 129         if (likely(seq > x->replay.seq))
 130                 return 0;
 131
 132         diff = x->replay.seq - seq;
 133         if (diff >= x->props.replay_window) {
 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                 XFRM_SKB_CB(skb)->seq.output.hi = 0;
 182                 if (unlikely(replay_esn->oseq == 0)) {
 183                         replay_esn->oseq--;
 184                         xfrm_audit_state_replay_overflow(x, skb);
 185                         err = -EOVERFLOW;
 186
 187                         return err;
 188                 }
 189                 if (xfrm_aevent_is_on(net))
 190                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
 191         }
 192
 193         return err;
 194 }
 195
 196 static int xfrm_replay_check_bmp(struct xfrm_state *x,
 197                                  struct sk_buff *skb, __be32 net_seq)
 198 {
 199         unsigned int bitnr, nr;
 200         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 201         u32 pos;
 202         u32 seq = ntohl(net_seq);
 203         u32 diff =  replay_esn->seq - seq;
 204
 205         if (!replay_esn->replay_window)
 206                 return 0;
 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         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 220
 221         if (pos >= diff)
 222                 bitnr = (pos - diff) % replay_esn->replay_window;
 223         else
 224                 bitnr = replay_esn->replay_window - (diff - pos);
 225
 226         nr = bitnr >> 5;
 227         bitnr = bitnr & 0x1F;
 228         if (replay_esn->bmp[nr] & (1U << bitnr))
 229                 goto err_replay;
 230
 231         return 0;
 232
 233 err_replay:
 234         x->stats.replay++;
 235 err:
 236         xfrm_audit_state_replay(x, skb, net_seq);
 237         return -EINVAL;
 238 }
 239
 240 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
 241 {
 242         unsigned int bitnr, nr, i;
 243         u32 diff;
 244         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 245         u32 seq = ntohl(net_seq);
 246         u32 pos;
 247
 248         if (!replay_esn->replay_window)
 249                 return;
 250
 251         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 252
 253         if (seq > replay_esn->seq) {
 254                 diff = seq - replay_esn->seq;
 255
 256                 if (diff < replay_esn->replay_window) {
 257                         for (i = 1; i < diff; i++) {
 258                                 bitnr = (pos + i) % replay_esn->replay_window;
 259                                 nr = bitnr >> 5;
 260                                 bitnr = bitnr & 0x1F;
 261                                 replay_esn->bmp[nr] &=  ~(1U << bitnr);
 262                         }
 263                 } else {
 264                         nr = (replay_esn->replay_window - 1) >> 5;
 265                         for (i = 0; i <= nr; i++)
 266                                 replay_esn->bmp[i] = 0;
 267                 }
 268
 269                 bitnr = (pos + diff) % replay_esn->replay_window;
 270                 replay_esn->seq = seq;
 271         } else {
 272                 diff = replay_esn->seq - seq;
 273
 274                 if (pos >= diff)
 275                         bitnr = (pos - diff) % replay_esn->replay_window;
 276                 else
 277                         bitnr = replay_esn->replay_window - (diff - pos);
 278         }
 279
 280         nr = bitnr >> 5;
 281         bitnr = bitnr & 0x1F;
 282         replay_esn->bmp[nr] |= (1U << bitnr);
 283
 284         if (xfrm_aevent_is_on(xs_net(x)))
 285                 x->repl->notify(x, XFRM_REPLAY_UPDATE);
 286 }
 287
 288 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
 289 {
 290         struct km_event c;
 291         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 292         struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
 293
 294         /* we send notify messages in case
 295          *  1. we updated on of the sequence numbers, and the seqno difference
 296          *     is at least x->replay_maxdiff, in this case we also update the
 297          *     timeout of our timer function
 298          *  2. if x->replay_maxage has elapsed since last update,
 299          *     and there were changes
 300          *
 301          *  The state structure must be locked!
 302          */
 303
 304         switch (event) {
 305         case XFRM_REPLAY_UPDATE:
 306                 if (!x->replay_maxdiff ||
 307                     ((replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
 308                     (replay_esn->oseq - preplay_esn->oseq
 309                      < x->replay_maxdiff))) {
 310                         if (x->xflags & XFRM_TIME_DEFER)
 311                                 event = XFRM_REPLAY_TIMEOUT;
 312                         else
 313                                 return;
 314                 }
 315
 316                 break;
 317
 318         case XFRM_REPLAY_TIMEOUT:
 319                 if (memcmp(x->replay_esn, x->preplay_esn,
 320                            xfrm_replay_state_esn_len(replay_esn)) == 0) {
 321                         x->xflags |= XFRM_TIME_DEFER;
 322                         return;
 323                 }
 324
 325                 break;
 326         }
 327
 328         memcpy(x->preplay_esn, x->replay_esn,
 329                xfrm_replay_state_esn_len(replay_esn));
 330         c.event = XFRM_MSG_NEWAE;
 331         c.data.aevent = event;
 332         km_state_notify(x, &c);
 333
 334         if (x->replay_maxage &&
 335             !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
 336                 x->xflags &= ~XFRM_TIME_DEFER;
 337 }
 338
 339 static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
 340 {
 341         u32 seq_diff, oseq_diff;
 342         struct km_event c;
 343         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 344         struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
 345
 346         /* we send notify messages in case
 347          *  1. we updated on of the sequence numbers, and the seqno difference
 348          *     is at least x->replay_maxdiff, in this case we also update the
 349          *     timeout of our timer function
 350          *  2. if x->replay_maxage has elapsed since last update,
 351          *     and there were changes
 352          *
 353          *  The state structure must be locked!
 354          */
 355
 356         switch (event) {
 357         case XFRM_REPLAY_UPDATE:
 358                 if (x->replay_maxdiff) {
 359                         if (replay_esn->seq_hi == preplay_esn->seq_hi)
 360                                 seq_diff = replay_esn->seq - preplay_esn->seq;
 361                         else
 362                                 seq_diff = ~preplay_esn->seq + replay_esn->seq
 363                                            + 1;
 364
 365                         if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
 366                                 oseq_diff = replay_esn->oseq
 367                                             - preplay_esn->oseq;
 368                         else
 369                                 oseq_diff = ~preplay_esn->oseq
 370                                             + replay_esn->oseq + 1;
 371
 372                         if (seq_diff >= x->replay_maxdiff ||
 373                             oseq_diff >= x->replay_maxdiff)
 374                                 break;
 375                 }
 376
 377                 if (x->xflags & XFRM_TIME_DEFER)
 378                         event = XFRM_REPLAY_TIMEOUT;
 379                 else
 380                         return;
 381
 382                 break;
 383
 384         case XFRM_REPLAY_TIMEOUT:
 385                 if (memcmp(x->replay_esn, x->preplay_esn,
 386                            xfrm_replay_state_esn_len(replay_esn)) == 0) {
 387                         x->xflags |= XFRM_TIME_DEFER;
 388                         return;
 389                 }
 390
 391                 break;
 392         }
 393
 394         memcpy(x->preplay_esn, x->replay_esn,
 395                xfrm_replay_state_esn_len(replay_esn));
 396         c.event = XFRM_MSG_NEWAE;
 397         c.data.aevent = event;
 398         km_state_notify(x, &c);
 399
 400         if (x->replay_maxage &&
 401             !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
 402                 x->xflags &= ~XFRM_TIME_DEFER;
 403 }
 404
 405 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
 406 {
 407         int err = 0;
 408         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 409         struct net *net = xs_net(x);
 410
 411         if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
 412                 XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
 413                 XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
 414
 415                 if (unlikely(replay_esn->oseq == 0)) {
 416                         XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
 417
 418                         if (replay_esn->oseq_hi == 0) {
 419                                 replay_esn->oseq--;
 420                                 replay_esn->oseq_hi--;
 421                                 xfrm_audit_state_replay_overflow(x, skb);
 422                                 err = -EOVERFLOW;
 423
 424                                 return err;
 425                         }
 426                 }
 427                 if (xfrm_aevent_is_on(net))
 428                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
 429         }
 430
 431         return err;
 432 }
 433
 434 static int xfrm_replay_check_esn(struct xfrm_state *x,
 435                                  struct sk_buff *skb, __be32 net_seq)
 436 {
 437         unsigned int bitnr, nr;
 438         u32 diff;
 439         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 440         u32 pos;
 441         u32 seq = ntohl(net_seq);
 442         u32 wsize = replay_esn->replay_window;
 443         u32 top = replay_esn->seq;
 444         u32 bottom = top - wsize + 1;
 445
 446         if (!wsize)
 447                 return 0;
 448
 449         if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
 450                      (replay_esn->seq < replay_esn->replay_window - 1)))
 451                 goto err;
 452
 453         diff = top - seq;
 454
 455         if (likely(top >= wsize - 1)) {
 456                 /* A. same subspace */
 457                 if (likely(seq > top) || seq < bottom)
 458                         return 0;
 459         } else {
 460                 /* B. window spans two subspaces */
 461                 if (likely(seq > top && seq < bottom))
 462                         return 0;
 463                 if (seq >= bottom)
 464                         diff = ~seq + top + 1;
 465         }
 466
 467         if (diff >= replay_esn->replay_window) {
 468                 x->stats.replay_window++;
 469                 goto err;
 470         }
 471
 472         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 473
 474         if (pos >= diff)
 475                 bitnr = (pos - diff) % replay_esn->replay_window;
 476         else
 477                 bitnr = replay_esn->replay_window - (diff - pos);
 478
 479         nr = bitnr >> 5;
 480         bitnr = bitnr & 0x1F;
 481         if (replay_esn->bmp[nr] & (1U << bitnr))
 482                 goto err_replay;
 483
 484         return 0;
 485
 486 err_replay:
 487         x->stats.replay++;
 488 err:
 489         xfrm_audit_state_replay(x, skb, net_seq);
 490         return -EINVAL;
 491 }
 492
 493 static int xfrm_replay_recheck_esn(struct xfrm_state *x,
 494                                    struct sk_buff *skb, __be32 net_seq)
 495 {
 496         if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
 497                      htonl(xfrm_replay_seqhi(x, net_seq)))) {
 498                         x->stats.replay_window++;
 499                         return -EINVAL;
 500         }
 501
 502         return xfrm_replay_check_esn(x, skb, net_seq);
 503 }
 504
 505 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
 506 {
 507         unsigned int bitnr, nr, i;
 508         int wrap;
 509         u32 diff, pos, seq, seq_hi;
 510         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 511
 512         if (!replay_esn->replay_window)
 513                 return;
 514
 515         seq = ntohl(net_seq);
 516         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 517         seq_hi = xfrm_replay_seqhi(x, net_seq);
 518         wrap = seq_hi - replay_esn->seq_hi;
 519
 520         if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
 521                 if (likely(!wrap))
 522                         diff = seq - replay_esn->seq;
 523                 else
 524                         diff = ~replay_esn->seq + seq + 1;
 525
 526                 if (diff < replay_esn->replay_window) {
 527                         for (i = 1; i < diff; i++) {
 528                                 bitnr = (pos + i) % replay_esn->replay_window;
 529                                 nr = bitnr >> 5;
 530                                 bitnr = bitnr & 0x1F;
 531                                 replay_esn->bmp[nr] &=  ~(1U << bitnr);
 532                         }
 533                 } else {
 534                         nr = (replay_esn->replay_window - 1) >> 5;
 535                         for (i = 0; i <= nr; i++)
 536                                 replay_esn->bmp[i] = 0;
 537                 }
 538
 539                 bitnr = (pos + diff) % replay_esn->replay_window;
 540                 replay_esn->seq = seq;
 541
 542                 if (unlikely(wrap > 0))
 543                         replay_esn->seq_hi++;
 544         } else {
 545                 diff = replay_esn->seq - seq;
 546
 547                 if (pos >= diff)
 548                         bitnr = (pos - diff) % replay_esn->replay_window;
 549                 else
 550                         bitnr = replay_esn->replay_window - (diff - pos);
 551         }
 552
 553         nr = bitnr >> 5;
 554         bitnr = bitnr & 0x1F;
 555         replay_esn->bmp[nr] |= (1U << bitnr);
 556
 557         if (xfrm_aevent_is_on(xs_net(x)))
 558                 x->repl->notify(x, XFRM_REPLAY_UPDATE);
 559 }
 560
 561 static struct xfrm_replay xfrm_replay_legacy = {
 562         .advance        = xfrm_replay_advance,
 563         .check          = xfrm_replay_check,
 564         .recheck        = xfrm_replay_check,
 565         .notify         = xfrm_replay_notify,
 566         .overflow       = xfrm_replay_overflow,
 567 };
 568
 569 static struct xfrm_replay xfrm_replay_bmp = {
 570         .advance        = xfrm_replay_advance_bmp,
 571         .check          = xfrm_replay_check_bmp,
 572         .recheck        = xfrm_replay_check_bmp,
 573         .notify         = xfrm_replay_notify_bmp,
 574         .overflow       = xfrm_replay_overflow_bmp,
 575 };
 576
 577 static struct xfrm_replay xfrm_replay_esn = {
 578         .advance        = xfrm_replay_advance_esn,
 579         .check          = xfrm_replay_check_esn,
 580         .recheck        = xfrm_replay_recheck_esn,
 581         .notify         = xfrm_replay_notify_esn,
 582         .overflow       = xfrm_replay_overflow_esn,
 583 };
 584
 585 int xfrm_init_replay(struct xfrm_state *x)
 586 {
 587         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 588
 589         if (replay_esn) {
 590                 if (replay_esn->replay_window >
 591                     replay_esn->bmp_len * sizeof(__u32) * 8)
 592                         return -EINVAL;
 593
 594                 if (x->props.flags & XFRM_STATE_ESN) {
 595                         if (replay_esn->replay_window == 0)
 596                                 return -EINVAL;
 597                         x->repl = &xfrm_replay_esn;
 598                 } else
 599                         x->repl = &xfrm_replay_bmp;
 600         } else
 601                 x->repl = &xfrm_replay_legacy;
 602
 603         return 0;
 604 }
 605 EXPORT_SYMBOL(xfrm_init_replay);