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 (unlikely(seq == 0))
 122                 goto err;
 123
 124         if (likely(seq > x->replay.seq))
 125                 return 0;
 126
 127         diff = x->replay.seq - seq;
 128         if (diff >= min_t(unsigned int, x->props.replay_window,
 129                           sizeof(x->replay.bitmap) * 8)) {
 130                 x->stats.replay_window++;
 131                 goto err;
 132         }
 133
 134         if (x->replay.bitmap & (1U << diff)) {
 135                 x->stats.replay++;
 136                 goto err;
 137         }
 138         return 0;
 139
 140 err:
 141         xfrm_audit_state_replay(x, skb, net_seq);
 142         return -EINVAL;
 143 }
 144
 145 static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
 146 {
 147         u32 diff;
 148         u32 seq = ntohl(net_seq);
 149
 150         if (!x->props.replay_window)
 151                 return;
 152
 153         if (seq > x->replay.seq) {
 154                 diff = seq - x->replay.seq;
 155                 if (diff < x->props.replay_window)
 156                         x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
 157                 else
 158                         x->replay.bitmap = 1;
 159                 x->replay.seq = seq;
 160         } else {
 161                 diff = x->replay.seq - seq;
 162                 x->replay.bitmap |= (1U << diff);
 163         }
 164
 165         if (xfrm_aevent_is_on(xs_net(x)))
 166                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
 167 }
 168
 169 static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
 170 {
 171         int err = 0;
 172         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 173         struct net *net = xs_net(x);
 174
 175         if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
 176                 XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
 177                 if (unlikely(replay_esn->oseq == 0)) {
 178                         replay_esn->oseq--;
 179                         xfrm_audit_state_replay_overflow(x, skb);
 180                         err = -EOVERFLOW;
 181
 182                         return err;
 183                 }
 184                 if (xfrm_aevent_is_on(net))
 185                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
 186         }
 187
 188         return err;
 189 }
 190
 191 static int xfrm_replay_check_bmp(struct xfrm_state *x,
 192                                  struct sk_buff *skb, __be32 net_seq)
 193 {
 194         unsigned int bitnr, nr;
 195         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 196         u32 seq = ntohl(net_seq);
 197         u32 diff =  replay_esn->seq - seq;
 198         u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 199
 200         if (unlikely(seq == 0))
 201                 goto err;
 202
 203         if (likely(seq > replay_esn->seq))
 204                 return 0;
 205
 206         if (diff >= replay_esn->replay_window) {
 207                 x->stats.replay_window++;
 208                 goto err;
 209         }
 210
 211         if (pos >= diff) {
 212                 bitnr = (pos - diff) % replay_esn->replay_window;
 213                 nr = bitnr >> 5;
 214                 bitnr = bitnr & 0x1F;
 215                 if (replay_esn->bmp[nr] & (1U << bitnr))
 216                         goto err_replay;
 217         } else {
 218                 bitnr = replay_esn->replay_window - (diff - pos);
 219                 nr = bitnr >> 5;
 220                 bitnr = bitnr & 0x1F;
 221                 if (replay_esn->bmp[nr] & (1U << bitnr))
 222                         goto err_replay;
 223         }
 224         return 0;
 225
 226 err_replay:
 227         x->stats.replay++;
 228 err:
 229         xfrm_audit_state_replay(x, skb, net_seq);
 230         return -EINVAL;
 231 }
 232
 233 static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
 234 {
 235         unsigned int bitnr, nr, i;
 236         u32 diff;
 237         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 238         u32 seq = ntohl(net_seq);
 239         u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 240
 241         if (!replay_esn->replay_window)
 242                 return;
 243
 244         if (seq > replay_esn->seq) {
 245                 diff = seq - replay_esn->seq;
 246
 247                 if (diff < replay_esn->replay_window) {
 248                         for (i = 1; i < diff; i++) {
 249                                 bitnr = (pos + i) % replay_esn->replay_window;
 250                                 nr = bitnr >> 5;
 251                                 bitnr = bitnr & 0x1F;
 252                                 replay_esn->bmp[nr] &=  ~(1U << bitnr);
 253                         }
 254
 255                         bitnr = (pos + diff) % replay_esn->replay_window;
 256                         nr = bitnr >> 5;
 257                         bitnr = bitnr & 0x1F;
 258                         replay_esn->bmp[nr] |= (1U << bitnr);
 259                 } else {
 260                         nr = replay_esn->replay_window >> 5;
 261                         for (i = 0; i <= nr; i++)
 262                                 replay_esn->bmp[i] = 0;
 263
 264                         bitnr = (pos + diff) % replay_esn->replay_window;
 265                         nr = bitnr >> 5;
 266                         bitnr = bitnr & 0x1F;
 267                         replay_esn->bmp[nr] |= (1U << bitnr);
 268                 }
 269
 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                         nr = bitnr >> 5;
 277                         bitnr = bitnr & 0x1F;
 278                         replay_esn->bmp[nr] |= (1U << bitnr);
 279                 } else {
 280                         bitnr = replay_esn->replay_window - (diff - pos);
 281                         nr = bitnr >> 5;
 282                         bitnr = bitnr & 0x1F;
 283                         replay_esn->bmp[nr] |= (1U << bitnr);
 284                 }
 285         }
 286
 287         if (xfrm_aevent_is_on(xs_net(x)))
 288                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
 289 }
 290
 291 static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
 292 {
 293         struct km_event c;
 294         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 295         struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
 296
 297         /* we send notify messages in case
 298          *  1. we updated on of the sequence numbers, and the seqno difference
 299          *     is at least x->replay_maxdiff, in this case we also update the
 300          *     timeout of our timer function
 301          *  2. if x->replay_maxage has elapsed since last update,
 302          *     and there were changes
 303          *
 304          *  The state structure must be locked!
 305          */
 306
 307         switch (event) {
 308         case XFRM_REPLAY_UPDATE:
 309                 if (x->replay_maxdiff &&
 310                     (replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
 311                     (replay_esn->oseq - preplay_esn->oseq < x->replay_maxdiff)) {
 312                         if (x->xflags & XFRM_TIME_DEFER)
 313                                 event = XFRM_REPLAY_TIMEOUT;
 314                         else
 315                                 return;
 316                 }
 317
 318                 break;
 319
 320         case XFRM_REPLAY_TIMEOUT:
 321                 if (memcmp(x->replay_esn, x->preplay_esn,
 322                            xfrm_replay_state_esn_len(replay_esn)) == 0) {
 323                         x->xflags |= XFRM_TIME_DEFER;
 324                         return;
 325                 }
 326
 327                 break;
 328         }
 329
 330         memcpy(x->preplay_esn, x->replay_esn,
 331                xfrm_replay_state_esn_len(replay_esn));
 332         c.event = XFRM_MSG_NEWAE;
 333         c.data.aevent = event;
 334         km_state_notify(x, &c);
 335
 336         if (x->replay_maxage &&
 337             !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
 338                 x->xflags &= ~XFRM_TIME_DEFER;
 339 }
 340
 341 static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
 342 {
 343         int err = 0;
 344         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 345         struct net *net = xs_net(x);
 346
 347         if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
 348                 XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
 349                 XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
 350
 351                 if (unlikely(replay_esn->oseq == 0)) {
 352                         XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
 353
 354                         if (replay_esn->oseq_hi == 0) {
 355                                 replay_esn->oseq--;
 356                                 replay_esn->oseq_hi--;
 357                                 xfrm_audit_state_replay_overflow(x, skb);
 358                                 err = -EOVERFLOW;
 359
 360                                 return err;
 361                         }
 362                 }
 363                 if (xfrm_aevent_is_on(net))
 364                         x->repl->notify(x, XFRM_REPLAY_UPDATE);
 365         }
 366
 367         return err;
 368 }
 369
 370 static int xfrm_replay_check_esn(struct xfrm_state *x,
 371                                  struct sk_buff *skb, __be32 net_seq)
 372 {
 373         unsigned int bitnr, nr;
 374         u32 diff;
 375         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 376         u32 seq = ntohl(net_seq);
 377         u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 378         u32 wsize = replay_esn->replay_window;
 379         u32 top = replay_esn->seq;
 380         u32 bottom = top - wsize + 1;
 381
 382         if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
 383                      (replay_esn->seq < replay_esn->replay_window - 1)))
 384                 goto err;
 385
 386         diff = top - seq;
 387
 388         if (likely(top >= wsize - 1)) {
 389                 /* A. same subspace */
 390                 if (likely(seq > top) || seq < bottom)
 391                         return 0;
 392         } else {
 393                 /* B. window spans two subspaces */
 394                 if (likely(seq > top && seq < bottom))
 395                         return 0;
 396                 if (seq >= bottom)
 397                         diff = ~seq + top + 1;
 398         }
 399
 400         if (diff >= replay_esn->replay_window) {
 401                 x->stats.replay_window++;
 402                 goto err;
 403         }
 404
 405         if (pos >= diff) {
 406                 bitnr = (pos - diff) % replay_esn->replay_window;
 407                 nr = bitnr >> 5;
 408                 bitnr = bitnr & 0x1F;
 409                 if (replay_esn->bmp[nr] & (1U << bitnr))
 410                         goto err_replay;
 411         } else {
 412                 bitnr = replay_esn->replay_window - (diff - pos);
 413                 nr = bitnr >> 5;
 414                 bitnr = bitnr & 0x1F;
 415                 if (replay_esn->bmp[nr] & (1U << bitnr))
 416                         goto err_replay;
 417         }
 418         return 0;
 419
 420 err_replay:
 421         x->stats.replay++;
 422 err:
 423         xfrm_audit_state_replay(x, skb, net_seq);
 424         return -EINVAL;
 425 }
 426
 427 static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
 428 {
 429         unsigned int bitnr, nr, i;
 430         int wrap;
 431         u32 diff, pos, seq, seq_hi;
 432         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 433
 434         if (!replay_esn->replay_window)
 435                 return;
 436
 437         seq = ntohl(net_seq);
 438         pos = (replay_esn->seq - 1) % replay_esn->replay_window;
 439         seq_hi = xfrm_replay_seqhi(x, net_seq);
 440         wrap = seq_hi - replay_esn->seq_hi;
 441
 442         if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
 443                 if (likely(!wrap))
 444                         diff = seq - replay_esn->seq;
 445                 else
 446                         diff = ~replay_esn->seq + seq + 1;
 447
 448                 if (diff < replay_esn->replay_window) {
 449                         for (i = 1; i < diff; i++) {
 450                                 bitnr = (pos + i) % replay_esn->replay_window;
 451                                 nr = bitnr >> 5;
 452                                 bitnr = bitnr & 0x1F;
 453                                 replay_esn->bmp[nr] &=  ~(1U << bitnr);
 454                         }
 455
 456                         bitnr = (pos + diff) % replay_esn->replay_window;
 457                         nr = bitnr >> 5;
 458                         bitnr = bitnr & 0x1F;
 459                         replay_esn->bmp[nr] |= (1U << bitnr);
 460                 } else {
 461                         nr = replay_esn->replay_window >> 5;
 462                         for (i = 0; i <= nr; i++)
 463                                 replay_esn->bmp[i] = 0;
 464
 465                         bitnr = (pos + diff) % replay_esn->replay_window;
 466                         nr = bitnr >> 5;
 467                         bitnr = bitnr & 0x1F;
 468                         replay_esn->bmp[nr] |= (1U << bitnr);
 469                 }
 470
 471                 replay_esn->seq = seq;
 472
 473                 if (unlikely(wrap > 0))
 474                         replay_esn->seq_hi++;
 475         } else {
 476                 diff = replay_esn->seq - seq;
 477
 478                 if (pos >= diff) {
 479                         bitnr = (pos - diff) % replay_esn->replay_window;
 480                         nr = bitnr >> 5;
 481                         bitnr = bitnr & 0x1F;
 482                         replay_esn->bmp[nr] |= (1U << bitnr);
 483                 } else {
 484                         bitnr = replay_esn->replay_window - (diff - pos);
 485                         nr = bitnr >> 5;
 486                         bitnr = bitnr & 0x1F;
 487                         replay_esn->bmp[nr] |= (1U << bitnr);
 488                 }
 489         }
 490
 491         if (xfrm_aevent_is_on(xs_net(x)))
 492                 xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
 493 }
 494
 495 static struct xfrm_replay xfrm_replay_legacy = {
 496         .advance        = xfrm_replay_advance,
 497         .check          = xfrm_replay_check,
 498         .notify         = xfrm_replay_notify,
 499         .overflow       = xfrm_replay_overflow,
 500 };
 501
 502 static struct xfrm_replay xfrm_replay_bmp = {
 503         .advance        = xfrm_replay_advance_bmp,
 504         .check          = xfrm_replay_check_bmp,
 505         .notify         = xfrm_replay_notify_bmp,
 506         .overflow       = xfrm_replay_overflow_bmp,
 507 };
 508
 509 static struct xfrm_replay xfrm_replay_esn = {
 510         .advance        = xfrm_replay_advance_esn,
 511         .check          = xfrm_replay_check_esn,
 512         .notify         = xfrm_replay_notify_bmp,
 513         .overflow       = xfrm_replay_overflow_esn,
 514 };
 515
 516 int xfrm_init_replay(struct xfrm_state *x)
 517 {
 518         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
 519
 520         if (replay_esn) {
 521                 if (replay_esn->replay_window >
 522                     replay_esn->bmp_len * sizeof(__u32))
 523                         return -EINVAL;
 524
 525         if ((x->props.flags & XFRM_STATE_ESN) && x->replay_esn)
 526                 x->repl = &xfrm_replay_esn;
 527         else
 528                 x->repl = &xfrm_replay_bmp;
 529         } else
 530                 x->repl = &xfrm_replay_legacy;
 531
 532         return 0;
 533 }
 534 EXPORT_SYMBOL(xfrm_init_replay);