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         return x;
 143 }
 144
 145 static int post_crypt(struct skcipher_request *req)
 146 {
 147         struct rctx *rctx = skcipher_request_ctx(req);
 148         be128 *buf = rctx->ext ?: rctx->buf;
 149         struct skcipher_request *subreq;
 150         const int bs = LRW_BLOCK_SIZE;
 151         struct skcipher_walk w;
 152         struct scatterlist *sg;
 153         unsigned offset;
 154         int err;
 155
 156         subreq = &rctx->subreq;
 157         err = skcipher_walk_virt(&w, subreq, false);
 158
 159         while (w.nbytes) {
 160                 unsigned int avail = w.nbytes;
 161                 be128 *wdst;
 162
 163                 wdst = w.dst.virt.addr;
 164
 165                 do {
 166                         be128_xor(wdst, buf++, wdst);
 167                         wdst++;
 168                 } while ((avail -= bs) >= bs);
 169
 170                 err = skcipher_walk_done(&w, avail);
 171         }
 172
 173         rctx->left -= subreq->cryptlen;
 174
 175         if (err || !rctx->left)
 176                 goto out;
 177
 178         rctx->dst = rctx->dstbuf;
 179
 180         scatterwalk_done(&w.out, 0, 1);
 181         sg = w.out.sg;
 182         offset = w.out.offset;
 183
 184         if (rctx->dst != sg) {
 185                 rctx->dst[0] = *sg;
 186                 sg_unmark_end(rctx->dst);
 187                 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
 188         }
 189         rctx->dst[0].length -= offset - sg->offset;
 190         rctx->dst[0].offset = offset;
 191
 192 out:
 193         return err;
 194 }
 195
 196 static int pre_crypt(struct skcipher_request *req)
 197 {
 198         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 199         struct rctx *rctx = skcipher_request_ctx(req);
 200         struct priv *ctx = crypto_skcipher_ctx(tfm);
 201         be128 *buf = rctx->ext ?: rctx->buf;
 202         struct skcipher_request *subreq;
 203         const int bs = LRW_BLOCK_SIZE;
 204         struct skcipher_walk w;
 205         struct scatterlist *sg;
 206         unsigned cryptlen;
 207         unsigned offset;
 208         be128 *iv;
 209         bool more;
 210         int err;
 211
 212         subreq = &rctx->subreq;
 213         skcipher_request_set_tfm(subreq, tfm);
 214
 215         cryptlen = subreq->cryptlen;
 216         more = rctx->left > cryptlen;
 217         if (!more)
 218                 cryptlen = rctx->left;
 219
 220         skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
 221                                    cryptlen, req->iv);
 222
 223         err = skcipher_walk_virt(&w, subreq, false);
 224         iv = w.iv;
 225
 226         while (w.nbytes) {
 227                 unsigned int avail = w.nbytes;
 228                 be128 *wsrc;
 229                 be128 *wdst;
 230
 231                 wsrc = w.src.virt.addr;
 232                 wdst = w.dst.virt.addr;
 233
 234                 do {
 235                         *buf++ = rctx->t;
 236                         be128_xor(wdst++, &rctx->t, wsrc++);
 237
 238                         /* T <- I*Key2, using the optimization
 239                          * discussed in the specification */
 240                         be128_xor(&rctx->t, &rctx->t,
 241                                   &ctx->table.mulinc[get_index128(iv)]);
 242                         inc(iv);
 243                 } while ((avail -= bs) >= bs);
 244
 245                 err = skcipher_walk_done(&w, avail);
 246         }
 247
 248         skcipher_request_set_tfm(subreq, ctx->child);
 249         skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
 250                                    cryptlen, NULL);
 251
 252         if (err || !more)
 253                 goto out;
 254
 255         rctx->src = rctx->srcbuf;
 256
 257         scatterwalk_done(&w.in, 0, 1);
 258         sg = w.in.sg;
 259         offset = w.in.offset;
 260
 261         if (rctx->src != sg) {
 262                 rctx->src[0] = *sg;
 263                 sg_unmark_end(rctx->src);
 264                 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
 265         }
 266         rctx->src[0].length -= offset - sg->offset;
 267         rctx->src[0].offset = offset;
 268
 269 out:
 270         return err;
 271 }
 272
 273 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
 274 {
 275         struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
 276         struct rctx *rctx = skcipher_request_ctx(req);
 277         struct skcipher_request *subreq;
 278         gfp_t gfp;
 279
 280         subreq = &rctx->subreq;
 281         skcipher_request_set_callback(subreq, req->base.flags, done, req);
 282
 283         gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
 284                                                            GFP_ATOMIC;
 285         rctx->ext = NULL;
 286
 287         subreq->cryptlen = LRW_BUFFER_SIZE;
 288         if (req->cryptlen > LRW_BUFFER_SIZE) {
 289                 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
 290
 291                 rctx->ext = kmalloc(n, gfp);
 292                 if (rctx->ext)
 293                         subreq->cryptlen = n;
 294         }
 295
 296         rctx->src = req->src;
 297         rctx->dst = req->dst;
 298         rctx->left = req->cryptlen;
 299
 300         /* calculate first value of T */
 301         memcpy(&rctx->t, req->iv, sizeof(rctx->t));
 302
 303         /* T <- I*Key2 */
 304         gf128mul_64k_bbe(&rctx->t, ctx->table.table);
 305
 306         return 0;
 307 }
 308
 309 static void exit_crypt(struct skcipher_request *req)
 310 {
 311         struct rctx *rctx = skcipher_request_ctx(req);
 312
 313         rctx->left = 0;
 314
 315         if (rctx->ext)
 316                 kfree(rctx->ext);
 317 }
 318
 319 static int do_encrypt(struct skcipher_request *req, int err)
 320 {
 321         struct rctx *rctx = skcipher_request_ctx(req);
 322         struct skcipher_request *subreq;
 323
 324         subreq = &rctx->subreq;
 325
 326         while (!err && rctx->left) {
 327                 err = pre_crypt(req) ?:
 328                       crypto_skcipher_encrypt(subreq) ?:
 329                       post_crypt(req);
 330
 331                 if (err == -EINPROGRESS ||
 332                     (err == -EBUSY &&
 333                      req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
 334                         return err;
 335         }
 336
 337         exit_crypt(req);
 338         return err;
 339 }
 340
 341 static void encrypt_done(struct crypto_async_request *areq, int err)
 342 {
 343         struct skcipher_request *req = areq->data;
 344         struct skcipher_request *subreq;
 345         struct rctx *rctx;
 346
 347         rctx = skcipher_request_ctx(req);
 348         subreq = &rctx->subreq;
 349         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 350
 351         err = do_encrypt(req, err ?: post_crypt(req));
 352         if (rctx->left)
 353                 return;
 354
 355         skcipher_request_complete(req, err);
 356 }
 357
 358 static int encrypt(struct skcipher_request *req)
 359 {
 360         return do_encrypt(req, init_crypt(req, encrypt_done));
 361 }
 362
 363 static int do_decrypt(struct skcipher_request *req, int err)
 364 {
 365         struct rctx *rctx = skcipher_request_ctx(req);
 366         struct skcipher_request *subreq;
 367
 368         subreq = &rctx->subreq;
 369
 370         while (!err && rctx->left) {
 371                 err = pre_crypt(req) ?:
 372                       crypto_skcipher_decrypt(subreq) ?:
 373                       post_crypt(req);
 374
 375                 if (err == -EINPROGRESS ||
 376                     (err == -EBUSY &&
 377                      req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
 378                         return err;
 379         }
 380
 381         exit_crypt(req);
 382         return err;
 383 }
 384
 385 static void decrypt_done(struct crypto_async_request *areq, int err)
 386 {
 387         struct skcipher_request *req = areq->data;
 388         struct skcipher_request *subreq;
 389         struct rctx *rctx;
 390
 391         rctx = skcipher_request_ctx(req);
 392         subreq = &rctx->subreq;
 393         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 394
 395         err = do_decrypt(req, err ?: post_crypt(req));
 396         if (rctx->left)
 397                 return;
 398
 399         skcipher_request_complete(req, err);
 400 }
 401
 402 static int decrypt(struct skcipher_request *req)
 403 {
 404         return do_decrypt(req, init_crypt(req, decrypt_done));
 405 }
 406
 407 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
 408               struct scatterlist *ssrc, unsigned int nbytes,
 409               struct lrw_crypt_req *req)
 410 {
 411         const unsigned int bsize = LRW_BLOCK_SIZE;
 412         const unsigned int max_blks = req->tbuflen / bsize;
 413         struct lrw_table_ctx *ctx = req->table_ctx;
 414         struct blkcipher_walk walk;
 415         unsigned int nblocks;
 416         be128 *iv, *src, *dst, *t;
 417         be128 *t_buf = req->tbuf;
 418         int err, i;
 419
 420         BUG_ON(max_blks < 1);
 421
 422         blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
 423
 424         err = blkcipher_walk_virt(desc, &walk);
 425         nbytes = walk.nbytes;
 426         if (!nbytes)
 427                 return err;
 428
 429         nblocks = min(walk.nbytes / bsize, max_blks);
 430         src = (be128 *)walk.src.virt.addr;
 431         dst = (be128 *)walk.dst.virt.addr;
 432
 433         /* calculate first value of T */
 434         iv = (be128 *)walk.iv;
 435         t_buf[0] = *iv;
 436
 437         /* T <- I*Key2 */
 438         gf128mul_64k_bbe(&t_buf[0], ctx->table);
 439
 440         i = 0;
 441         goto first;
 442
 443         for (;;) {
 444                 do {
 445                         for (i = 0; i < nblocks; i++) {
 446                                 /* T <- I*Key2, using the optimization
 447                                  * discussed in the specification */
 448                                 be128_xor(&t_buf[i], t,
 449                                                 &ctx->mulinc[get_index128(iv)]);
 450                                 inc(iv);
 451 first:
 452                                 t = &t_buf[i];
 453
 454                                 /* PP <- T xor P */
 455                                 be128_xor(dst + i, t, src + i);
 456                         }
 457
 458                         /* CC <- E(Key2,PP) */
 459                         req->crypt_fn(req->crypt_ctx, (u8 *)dst,
 460                                       nblocks * bsize);
 461
 462                         /* C <- T xor CC */
 463                         for (i = 0; i < nblocks; i++)
 464                                 be128_xor(dst + i, dst + i, &t_buf[i]);
 465
 466                         src += nblocks;
 467                         dst += nblocks;
 468                         nbytes -= nblocks * bsize;
 469                         nblocks = min(nbytes / bsize, max_blks);
 470                 } while (nblocks > 0);
 471
 472                 err = blkcipher_walk_done(desc, &walk, nbytes);
 473                 nbytes = walk.nbytes;
 474                 if (!nbytes)
 475                         break;
 476
 477                 nblocks = min(nbytes / bsize, max_blks);
 478                 src = (be128 *)walk.src.virt.addr;
 479                 dst = (be128 *)walk.dst.virt.addr;
 480         }
 481
 482         return err;
 483 }
 484 EXPORT_SYMBOL_GPL(lrw_crypt);
 485
 486 static int init_tfm(struct crypto_skcipher *tfm)
 487 {
 488         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 489         struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
 490         struct priv *ctx = crypto_skcipher_ctx(tfm);
 491         struct crypto_skcipher *cipher;
 492
 493         cipher = crypto_spawn_skcipher(spawn);
 494         if (IS_ERR(cipher))
 495                 return PTR_ERR(cipher);
 496
 497         ctx->child = cipher;
 498
 499         crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
 500                                          sizeof(struct rctx));
 501
 502         return 0;
 503 }
 504
 505 static void exit_tfm(struct crypto_skcipher *tfm)
 506 {
 507         struct priv *ctx = crypto_skcipher_ctx(tfm);
 508
 509         lrw_free_table(&ctx->table);
 510         crypto_free_skcipher(ctx->child);
 511 }
 512
 513 static void free(struct skcipher_instance *inst)
 514 {
 515         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 516         kfree(inst);
 517 }
 518
 519 static int create(struct crypto_template *tmpl, struct rtattr **tb)
 520 {
 521         struct crypto_skcipher_spawn *spawn;
 522         struct skcipher_instance *inst;
 523         struct crypto_attr_type *algt;
 524         struct skcipher_alg *alg;
 525         const char *cipher_name;
 526         char ecb_name[CRYPTO_MAX_ALG_NAME];
 527         int err;
 528
 529         algt = crypto_get_attr_type(tb);
 530         if (IS_ERR(algt))
 531                 return PTR_ERR(algt);
 532
 533         if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
 534                 return -EINVAL;
 535
 536         cipher_name = crypto_attr_alg_name(tb[1]);
 537         if (IS_ERR(cipher_name))
 538                 return PTR_ERR(cipher_name);
 539
 540         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 541         if (!inst)
 542                 return -ENOMEM;
 543
 544         spawn = skcipher_instance_ctx(inst);
 545
 546         crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
 547         err = crypto_grab_skcipher(spawn, cipher_name, 0,
 548                                    crypto_requires_sync(algt->type,
 549                                                         algt->mask));
 550         if (err == -ENOENT) {
 551                 err = -ENAMETOOLONG;
 552                 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
 553                              cipher_name) >= CRYPTO_MAX_ALG_NAME)
 554                         goto err_free_inst;
 555
 556                 err = crypto_grab_skcipher(spawn, ecb_name, 0,
 557                                            crypto_requires_sync(algt->type,
 558                                                                 algt->mask));
 559         }
 560
 561         if (err)
 562                 goto err_free_inst;
 563
 564         alg = crypto_skcipher_spawn_alg(spawn);
 565
 566         err = -EINVAL;
 567         if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
 568                 goto err_drop_spawn;
 569
 570         if (crypto_skcipher_alg_ivsize(alg))
 571                 goto err_drop_spawn;
 572
 573         err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
 574                                   &alg->base);
 575         if (err)
 576                 goto err_drop_spawn;
 577
 578         err = -EINVAL;
 579         cipher_name = alg->base.cra_name;
 580
 581         /* Alas we screwed up the naming so we have to mangle the
 582          * cipher name.
 583          */
 584         if (!strncmp(cipher_name, "ecb(", 4)) {
 585                 unsigned len;
 586
 587                 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
 588                 if (len < 2 || len >= sizeof(ecb_name))
 589                         goto err_drop_spawn;
 590
 591                 if (ecb_name[len - 1] != ')')
 592                         goto err_drop_spawn;
 593
 594                 ecb_name[len - 1] = 0;
 595
 596                 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 597                              "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME)
 598                         return -ENAMETOOLONG;
 599         }
 600
 601         inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
 602         inst->alg.base.cra_priority = alg->base.cra_priority;
 603         inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
 604         inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
 605                                        (__alignof__(u64) - 1);
 606
 607         inst->alg.ivsize = LRW_BLOCK_SIZE;
 608         inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
 609                                 LRW_BLOCK_SIZE;
 610         inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
 611                                 LRW_BLOCK_SIZE;
 612
 613         inst->alg.base.cra_ctxsize = sizeof(struct priv);
 614
 615         inst->alg.init = init_tfm;
 616         inst->alg.exit = exit_tfm;
 617
 618         inst->alg.setkey = setkey;
 619         inst->alg.encrypt = encrypt;
 620         inst->alg.decrypt = decrypt;
 621
 622         inst->free = free;
 623
 624         err = skcipher_register_instance(tmpl, inst);
 625         if (err)
 626                 goto err_drop_spawn;
 627
 628 out:
 629         return err;
 630
 631 err_drop_spawn:
 632         crypto_drop_skcipher(spawn);
 633 err_free_inst:
 634         kfree(inst);
 635         goto out;
 636 }
 637
 638 static struct crypto_template crypto_tmpl = {
 639         .name = "lrw",
 640         .create = create,
 641         .module = THIS_MODULE,
 642 };
 643
 644 static int __init crypto_module_init(void)
 645 {
 646         return crypto_register_template(&crypto_tmpl);
 647 }
 648
 649 static void __exit crypto_module_exit(void)
 650 {
 651         crypto_unregister_template(&crypto_tmpl);
 652 }
 653
 654 module_init(crypto_module_init);
 655 module_exit(crypto_module_exit);
 656
 657 MODULE_LICENSE("GPL");
 658 MODULE_DESCRIPTION("LRW block cipher mode");
 659 MODULE_ALIAS_CRYPTO("lrw");