crypto/lrw.c

   1 /* LRW: as defined by Cyril Guyot in
   2  *      http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
   3  *
   4  * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
   5  *
   6  * Based on ecb.c
   7  * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the Free
  11  * Software Foundation; either version 2 of the License, or (at your option)
  12  * any later version.
  13  */
  14 /* This implementation is checked against the test vectors in the above
  15  * document and by a test vector provided by Ken Buchanan at
  16  * http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
  17  *
  18  * The test vectors are included in the testing module tcrypt.[ch] */
  19
  20 #include <crypto/internal/skcipher.h>
  21 #include <crypto/scatterwalk.h>
  22 #include <linux/err.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/scatterlist.h>
  27 #include <linux/slab.h>
  28
  29 #include <crypto/b128ops.h>
  30 #include <crypto/gf128mul.h>
  31 #include <crypto/lrw.h>
  32
  33 #define LRW_BUFFER_SIZE 128u
  34
  35 struct priv {
  36         struct crypto_skcipher *child;
  37         struct lrw_table_ctx table;
  38 };
  39
  40 struct rctx {
  41         be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
  42
  43         be128 t;
  44
  45         be128 *ext;
  46
  47         struct scatterlist srcbuf[2];
  48         struct scatterlist dstbuf[2];
  49         struct scatterlist *src;
  50         struct scatterlist *dst;
  51
  52         unsigned int left;
  53
  54         struct skcipher_request subreq;
  55 };
  56
  57 static inline void setbit128_bbe(void *b, int bit)
  58 {
  59         __set_bit(bit ^ (0x80 -
  60 #ifdef __BIG_ENDIAN
  61                          BITS_PER_LONG
  62 #else
  63                          BITS_PER_BYTE
  64 #endif
  65                         ), b);
  66 }
  67
  68 int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
  69 {
  70         be128 tmp = { 0 };
  71         int i;
  72
  73         if (ctx->table)
  74                 gf128mul_free_64k(ctx->table);
  75
  76         /* initialize multiplication table for Key2 */
  77         ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
  78         if (!ctx->table)
  79                 return -ENOMEM;
  80
  81         /* initialize optimization table */
  82         for (i = 0; i < 128; i++) {
  83                 setbit128_bbe(&tmp, i);
  84                 ctx->mulinc[i] = tmp;
  85                 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
  86         }
  87
  88         return 0;
  89 }
  90 EXPORT_SYMBOL_GPL(lrw_init_table);
  91
  92 void lrw_free_table(struct lrw_table_ctx *ctx)
  93 {
  94         if (ctx->table)
  95                 gf128mul_free_64k(ctx->table);
  96 }
  97 EXPORT_SYMBOL_GPL(lrw_free_table);
  98
  99 static int setkey(struct crypto_skcipher *parent, const u8 *key,
 100                   unsigned int keylen)
 101 {
 102         struct priv *ctx = crypto_skcipher_ctx(parent);
 103         struct crypto_skcipher *child = ctx->child;
 104         int err, bsize = LRW_BLOCK_SIZE;
 105         const u8 *tweak = key + keylen - bsize;
 106
 107         crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 108         crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
 109                                          CRYPTO_TFM_REQ_MASK);
 110         err = crypto_skcipher_setkey(child, key, keylen - bsize);
 111         crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
 112                                           CRYPTO_TFM_RES_MASK);
 113         if (err)
 114                 return err;
 115
 116         return lrw_init_table(&ctx->table, tweak);
 117 }
 118
 119 static inline void inc(be128 *iv)
 120 {
 121         be64_add_cpu(&iv->b, 1);
 122         if (!iv->b)
 123                 be64_add_cpu(&iv->a, 1);
 124 }
 125
 126 /* this returns the number of consequative 1 bits starting
 127  * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
 128 static inline int get_index128(be128 *block)
 129 {
 130         int x;
 131         __be32 *p = (__be32 *) block;
 132
 133         for (p += 3, x = 0; x < 128; p--, x += 32) {
 134                 u32 val = be32_to_cpup(p);
 135
 136                 if (!~val)
 137                         continue;
 138
 139                 return x + ffz(val);
 140         }
 141
 142         /*
 143          * If we get here, then x == 128 and we are incrementing the counter
 144          * from all ones to all zeros. This means we must return index 127, i.e.
 145          * the one corresponding to key2*{ 1,...,1 }.
 146          */
 147         return 127;
 148 }
 149
 150 static int post_crypt(struct skcipher_request *req)
 151 {
 152         struct rctx *rctx = skcipher_request_ctx(req);
 153         be128 *buf = rctx->ext ?: rctx->buf;
 154         struct skcipher_request *subreq;
 155         const int bs = LRW_BLOCK_SIZE;
 156         struct skcipher_walk w;
 157         struct scatterlist *sg;
 158         unsigned offset;
 159         int err;
 160
 161         subreq = &rctx->subreq;
 162         err = skcipher_walk_virt(&w, subreq, false);
 163
 164         while (w.nbytes) {
 165                 unsigned int avail = w.nbytes;
 166                 be128 *wdst;
 167
 168                 wdst = w.dst.virt.addr;
 169
 170                 do {
 171                         be128_xor(wdst, buf++, wdst);
 172                         wdst++;
 173                 } while ((avail -= bs) >= bs);
 174
 175                 err = skcipher_walk_done(&w, avail);
 176         }
 177
 178         rctx->left -= subreq->cryptlen;
 179
 180         if (err || !rctx->left)
 181                 goto out;
 182
 183         rctx->dst = rctx->dstbuf;
 184
 185         scatterwalk_done(&w.out, 0, 1);
 186         sg = w.out.sg;
 187         offset = w.out.offset;
 188
 189         if (rctx->dst != sg) {
 190                 rctx->dst[0] = *sg;
 191                 sg_unmark_end(rctx->dst);
 192                 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
 193         }
 194         rctx->dst[0].length -= offset - sg->offset;
 195         rctx->dst[0].offset = offset;
 196
 197 out:
 198         return err;
 199 }
 200
 201 static int pre_crypt(struct skcipher_request *req)
 202 {
 203         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 204         struct rctx *rctx = skcipher_request_ctx(req);
 205         struct priv *ctx = crypto_skcipher_ctx(tfm);
 206         be128 *buf = rctx->ext ?: rctx->buf;
 207         struct skcipher_request *subreq;
 208         const int bs = LRW_BLOCK_SIZE;
 209         struct skcipher_walk w;
 210         struct scatterlist *sg;
 211         unsigned cryptlen;
 212         unsigned offset;
 213         be128 *iv;
 214         bool more;
 215         int err;
 216
 217         subreq = &rctx->subreq;
 218         skcipher_request_set_tfm(subreq, tfm);
 219
 220         cryptlen = subreq->cryptlen;
 221         more = rctx->left > cryptlen;
 222         if (!more)
 223                 cryptlen = rctx->left;
 224
 225         skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
 226                                    cryptlen, req->iv);
 227
 228         err = skcipher_walk_virt(&w, subreq, false);
 229         iv = w.iv;
 230
 231         while (w.nbytes) {
 232                 unsigned int avail = w.nbytes;
 233                 be128 *wsrc;
 234                 be128 *wdst;
 235
 236                 wsrc = w.src.virt.addr;
 237                 wdst = w.dst.virt.addr;
 238
 239                 do {
 240                         *buf++ = rctx->t;
 241                         be128_xor(wdst++, &rctx->t, wsrc++);
 242
 243                         /* T <- I*Key2, using the optimization
 244                          * discussed in the specification */
 245                         be128_xor(&rctx->t, &rctx->t,
 246                                   &ctx->table.mulinc[get_index128(iv)]);
 247                         inc(iv);
 248                 } while ((avail -= bs) >= bs);
 249
 250                 err = skcipher_walk_done(&w, avail);
 251         }
 252
 253         skcipher_request_set_tfm(subreq, ctx->child);
 254         skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
 255                                    cryptlen, NULL);
 256
 257         if (err || !more)
 258                 goto out;
 259
 260         rctx->src = rctx->srcbuf;
 261
 262         scatterwalk_done(&w.in, 0, 1);
 263         sg = w.in.sg;
 264         offset = w.in.offset;
 265
 266         if (rctx->src != sg) {
 267                 rctx->src[0] = *sg;
 268                 sg_unmark_end(rctx->src);
 269                 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
 270         }
 271         rctx->src[0].length -= offset - sg->offset;
 272         rctx->src[0].offset = offset;
 273
 274 out:
 275         return err;
 276 }
 277
 278 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
 279 {
 280         struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
 281         struct rctx *rctx = skcipher_request_ctx(req);
 282         struct skcipher_request *subreq;
 283         gfp_t gfp;
 284
 285         subreq = &rctx->subreq;
 286         skcipher_request_set_callback(subreq, req->base.flags, done, req);
 287
 288         gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
 289                                                            GFP_ATOMIC;
 290         rctx->ext = NULL;
 291
 292         subreq->cryptlen = LRW_BUFFER_SIZE;
 293         if (req->cryptlen > LRW_BUFFER_SIZE) {
 294                 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
 295
 296                 rctx->ext = kmalloc(n, gfp);
 297                 if (rctx->ext)
 298                         subreq->cryptlen = n;
 299         }
 300
 301         rctx->src = req->src;
 302         rctx->dst = req->dst;
 303         rctx->left = req->cryptlen;
 304
 305         /* calculate first value of T */
 306         memcpy(&rctx->t, req->iv, sizeof(rctx->t));
 307
 308         /* T <- I*Key2 */
 309         gf128mul_64k_bbe(&rctx->t, ctx->table.table);
 310
 311         return 0;
 312 }
 313
 314 static void exit_crypt(struct skcipher_request *req)
 315 {
 316         struct rctx *rctx = skcipher_request_ctx(req);
 317
 318         rctx->left = 0;
 319
 320         if (rctx->ext)
 321                 kzfree(rctx->ext);
 322 }
 323
 324 static int do_encrypt(struct skcipher_request *req, int err)
 325 {
 326         struct rctx *rctx = skcipher_request_ctx(req);
 327         struct skcipher_request *subreq;
 328
 329         subreq = &rctx->subreq;
 330
 331         while (!err && rctx->left) {
 332                 err = pre_crypt(req) ?:
 333                       crypto_skcipher_encrypt(subreq) ?:
 334                       post_crypt(req);
 335
 336                 if (err == -EINPROGRESS ||
 337                     (err == -EBUSY &&
 338                      req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
 339                         return err;
 340         }
 341
 342         exit_crypt(req);
 343         return err;
 344 }
 345
 346 static void encrypt_done(struct crypto_async_request *areq, int err)
 347 {
 348         struct skcipher_request *req = areq->data;
 349         struct skcipher_request *subreq;
 350         struct rctx *rctx;
 351
 352         rctx = skcipher_request_ctx(req);
 353
 354         if (err == -EINPROGRESS) {
 355                 if (rctx->left != req->cryptlen)
 356                         return;
 357                 goto out;
 358         }
 359
 360         subreq = &rctx->subreq;
 361         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 362
 363         err = do_encrypt(req, err ?: post_crypt(req));
 364         if (rctx->left)
 365                 return;
 366
 367 out:
 368         skcipher_request_complete(req, err);
 369 }
 370
 371 static int encrypt(struct skcipher_request *req)
 372 {
 373         return do_encrypt(req, init_crypt(req, encrypt_done));
 374 }
 375
 376 static int do_decrypt(struct skcipher_request *req, int err)
 377 {
 378         struct rctx *rctx = skcipher_request_ctx(req);
 379         struct skcipher_request *subreq;
 380
 381         subreq = &rctx->subreq;
 382
 383         while (!err && rctx->left) {
 384                 err = pre_crypt(req) ?:
 385                       crypto_skcipher_decrypt(subreq) ?:
 386                       post_crypt(req);
 387
 388                 if (err == -EINPROGRESS ||
 389                     (err == -EBUSY &&
 390                      req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
 391                         return err;
 392         }
 393
 394         exit_crypt(req);
 395         return err;
 396 }
 397
 398 static void decrypt_done(struct crypto_async_request *areq, int err)
 399 {
 400         struct skcipher_request *req = areq->data;
 401         struct skcipher_request *subreq;
 402         struct rctx *rctx;
 403
 404         rctx = skcipher_request_ctx(req);
 405
 406         if (err == -EINPROGRESS) {
 407                 if (rctx->left != req->cryptlen)
 408                         return;
 409                 goto out;
 410         }
 411
 412         subreq = &rctx->subreq;
 413         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 414
 415         err = do_decrypt(req, err ?: post_crypt(req));
 416         if (rctx->left)
 417                 return;
 418
 419 out:
 420         skcipher_request_complete(req, err);
 421 }
 422
 423 static int decrypt(struct skcipher_request *req)
 424 {
 425         return do_decrypt(req, init_crypt(req, decrypt_done));
 426 }
 427
 428 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
 429               struct scatterlist *ssrc, unsigned int nbytes,
 430               struct lrw_crypt_req *req)
 431 {
 432         const unsigned int bsize = LRW_BLOCK_SIZE;
 433         const unsigned int max_blks = req->tbuflen / bsize;
 434         struct lrw_table_ctx *ctx = req->table_ctx;
 435         struct blkcipher_walk walk;
 436         unsigned int nblocks;
 437         be128 *iv, *src, *dst, *t;
 438         be128 *t_buf = req->tbuf;
 439         int err, i;
 440
 441         BUG_ON(max_blks < 1);
 442
 443         blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
 444
 445         err = blkcipher_walk_virt(desc, &walk);
 446         nbytes = walk.nbytes;
 447         if (!nbytes)
 448                 return err;
 449
 450         nblocks = min(walk.nbytes / bsize, max_blks);
 451         src = (be128 *)walk.src.virt.addr;
 452         dst = (be128 *)walk.dst.virt.addr;
 453
 454         /* calculate first value of T */
 455         iv = (be128 *)walk.iv;
 456         t_buf[0] = *iv;
 457
 458         /* T <- I*Key2 */
 459         gf128mul_64k_bbe(&t_buf[0], ctx->table);
 460
 461         i = 0;
 462         goto first;
 463
 464         for (;;) {
 465                 do {
 466                         for (i = 0; i < nblocks; i++) {
 467                                 /* T <- I*Key2, using the optimization
 468                                  * discussed in the specification */
 469                                 be128_xor(&t_buf[i], t,
 470                                                 &ctx->mulinc[get_index128(iv)]);
 471                                 inc(iv);
 472 first:
 473                                 t = &t_buf[i];
 474
 475                                 /* PP <- T xor P */
 476                                 be128_xor(dst + i, t, src + i);
 477                         }
 478
 479                         /* CC <- E(Key2,PP) */
 480                         req->crypt_fn(req->crypt_ctx, (u8 *)dst,
 481                                       nblocks * bsize);
 482
 483                         /* C <- T xor CC */
 484                         for (i = 0; i < nblocks; i++)
 485                                 be128_xor(dst + i, dst + i, &t_buf[i]);
 486
 487                         src += nblocks;
 488                         dst += nblocks;
 489                         nbytes -= nblocks * bsize;
 490                         nblocks = min(nbytes / bsize, max_blks);
 491                 } while (nblocks > 0);
 492
 493                 err = blkcipher_walk_done(desc, &walk, nbytes);
 494                 nbytes = walk.nbytes;
 495                 if (!nbytes)
 496                         break;
 497
 498                 nblocks = min(nbytes / bsize, max_blks);
 499                 src = (be128 *)walk.src.virt.addr;
 500                 dst = (be128 *)walk.dst.virt.addr;
 501         }
 502
 503         return err;
 504 }
 505 EXPORT_SYMBOL_GPL(lrw_crypt);
 506
 507 static int init_tfm(struct crypto_skcipher *tfm)
 508 {
 509         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 510         struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
 511         struct priv *ctx = crypto_skcipher_ctx(tfm);
 512         struct crypto_skcipher *cipher;
 513
 514         cipher = crypto_spawn_skcipher(spawn);
 515         if (IS_ERR(cipher))
 516                 return PTR_ERR(cipher);
 517
 518         ctx->child = cipher;
 519
 520         crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
 521                                          sizeof(struct rctx));
 522
 523         return 0;
 524 }
 525
 526 static void exit_tfm(struct crypto_skcipher *tfm)
 527 {
 528         struct priv *ctx = crypto_skcipher_ctx(tfm);
 529
 530         lrw_free_table(&ctx->table);
 531         crypto_free_skcipher(ctx->child);
 532 }
 533
 534 static void free(struct skcipher_instance *inst)
 535 {
 536         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 537         kfree(inst);
 538 }
 539
 540 static int create(struct crypto_template *tmpl, struct rtattr **tb)
 541 {
 542         struct crypto_skcipher_spawn *spawn;
 543         struct skcipher_instance *inst;
 544         struct crypto_attr_type *algt;
 545         struct skcipher_alg *alg;
 546         const char *cipher_name;
 547         char ecb_name[CRYPTO_MAX_ALG_NAME];
 548         int err;
 549
 550         algt = crypto_get_attr_type(tb);
 551         if (IS_ERR(algt))
 552                 return PTR_ERR(algt);
 553
 554         if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
 555                 return -EINVAL;
 556
 557         cipher_name = crypto_attr_alg_name(tb[1]);
 558         if (IS_ERR(cipher_name))
 559                 return PTR_ERR(cipher_name);
 560
 561         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 562         if (!inst)
 563                 return -ENOMEM;
 564
 565         spawn = skcipher_instance_ctx(inst);
 566
 567         crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
 568         err = crypto_grab_skcipher(spawn, cipher_name, 0,
 569                                    crypto_requires_sync(algt->type,
 570                                                         algt->mask));
 571         if (err == -ENOENT) {
 572                 err = -ENAMETOOLONG;
 573                 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
 574                              cipher_name) >= CRYPTO_MAX_ALG_NAME)
 575                         goto err_free_inst;
 576
 577                 err = crypto_grab_skcipher(spawn, ecb_name, 0,
 578                                            crypto_requires_sync(algt->type,
 579                                                                 algt->mask));
 580         }
 581
 582         if (err)
 583                 goto err_free_inst;
 584
 585         alg = crypto_skcipher_spawn_alg(spawn);
 586
 587         err = -EINVAL;
 588         if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
 589                 goto err_drop_spawn;
 590
 591         if (crypto_skcipher_alg_ivsize(alg))
 592                 goto err_drop_spawn;
 593
 594         err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
 595                                   &alg->base);
 596         if (err)
 597                 goto err_drop_spawn;
 598
 599         err = -EINVAL;
 600         cipher_name = alg->base.cra_name;
 601
 602         /* Alas we screwed up the naming so we have to mangle the
 603          * cipher name.
 604          */
 605         if (!strncmp(cipher_name, "ecb(", 4)) {
 606                 unsigned len;
 607
 608                 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
 609                 if (len < 2 || len >= sizeof(ecb_name))
 610                         goto err_drop_spawn;
 611
 612                 if (ecb_name[len - 1] != ')')
 613                         goto err_drop_spawn;
 614
 615                 ecb_name[len - 1] = 0;
 616
 617                 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 618                              "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
 619                         err = -ENAMETOOLONG;
 620                         goto err_drop_spawn;
 621                 }
 622         }
 623
 624         inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
 625         inst->alg.base.cra_priority = alg->base.cra_priority;
 626         inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
 627         inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
 628                                        (__alignof__(u64) - 1);
 629
 630         inst->alg.ivsize = LRW_BLOCK_SIZE;
 631         inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
 632                                 LRW_BLOCK_SIZE;
 633         inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
 634                                 LRW_BLOCK_SIZE;
 635
 636         inst->alg.base.cra_ctxsize = sizeof(struct priv);
 637
 638         inst->alg.init = init_tfm;
 639         inst->alg.exit = exit_tfm;
 640
 641         inst->alg.setkey = setkey;
 642         inst->alg.encrypt = encrypt;
 643         inst->alg.decrypt = decrypt;
 644
 645         inst->free = free;
 646
 647         err = skcipher_register_instance(tmpl, inst);
 648         if (err)
 649                 goto err_drop_spawn;
 650
 651 out:
 652         return err;
 653
 654 err_drop_spawn:
 655         crypto_drop_skcipher(spawn);
 656 err_free_inst:
 657         kfree(inst);
 658         goto out;
 659 }
 660
 661 static struct crypto_template crypto_tmpl = {
 662         .name = "lrw",
 663         .create = create,
 664         .module = THIS_MODULE,
 665 };
 666
 667 static int __init crypto_module_init(void)
 668 {
 669         return crypto_register_template(&crypto_tmpl);
 670 }
 671
 672 static void __exit crypto_module_exit(void)
 673 {
 674         crypto_unregister_template(&crypto_tmpl);
 675 }
 676
 677 module_init(crypto_module_init);
 678 module_exit(crypto_module_exit);
 679
 680 MODULE_LICENSE("GPL");
 681 MODULE_DESCRIPTION("LRW block cipher mode");
 682 MODULE_ALIAS_CRYPTO("lrw");