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