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                 subreq->cryptlen = min(req->cryptlen, (unsigned)PAGE_SIZE);
 290                 rctx->ext = kmalloc(subreq->cryptlen, gfp);
 291         }
 292
 293         rctx->src = req->src;
 294         rctx->dst = req->dst;
 295         rctx->left = req->cryptlen;
 296
 297         /* calculate first value of T */
 298         memcpy(&rctx->t, req->iv, sizeof(rctx->t));
 299
 300         /* T <- I*Key2 */
 301         gf128mul_64k_bbe(&rctx->t, ctx->table.table);
 302
 303         return 0;
 304 }
 305
 306 static void exit_crypt(struct skcipher_request *req)
 307 {
 308         struct rctx *rctx = skcipher_request_ctx(req);
 309
 310         rctx->left = 0;
 311
 312         if (rctx->ext)
 313                 kfree(rctx->ext);
 314 }
 315
 316 static int do_encrypt(struct skcipher_request *req, int err)
 317 {
 318         struct rctx *rctx = skcipher_request_ctx(req);
 319         struct skcipher_request *subreq;
 320
 321         subreq = &rctx->subreq;
 322
 323         while (!err && rctx->left) {
 324                 err = pre_crypt(req) ?:
 325                       crypto_skcipher_encrypt(subreq) ?:
 326                       post_crypt(req);
 327
 328                 if (err == -EINPROGRESS ||
 329                     (err == -EBUSY &&
 330                      req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
 331                         return err;
 332         }
 333
 334         exit_crypt(req);
 335         return err;
 336 }
 337
 338 static void encrypt_done(struct crypto_async_request *areq, int err)
 339 {
 340         struct skcipher_request *req = areq->data;
 341         struct skcipher_request *subreq;
 342         struct rctx *rctx;
 343
 344         rctx = skcipher_request_ctx(req);
 345         subreq = &rctx->subreq;
 346         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 347
 348         err = do_encrypt(req, err ?: post_crypt(req));
 349         if (rctx->left)
 350                 return;
 351
 352         skcipher_request_complete(req, err);
 353 }
 354
 355 static int encrypt(struct skcipher_request *req)
 356 {
 357         return do_encrypt(req, init_crypt(req, encrypt_done));
 358 }
 359
 360 static int do_decrypt(struct skcipher_request *req, int err)
 361 {
 362         struct rctx *rctx = skcipher_request_ctx(req);
 363         struct skcipher_request *subreq;
 364
 365         subreq = &rctx->subreq;
 366
 367         while (!err && rctx->left) {
 368                 err = pre_crypt(req) ?:
 369                       crypto_skcipher_decrypt(subreq) ?:
 370                       post_crypt(req);
 371
 372                 if (err == -EINPROGRESS ||
 373                     (err == -EBUSY &&
 374                      req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
 375                         return err;
 376         }
 377
 378         exit_crypt(req);
 379         return err;
 380 }
 381
 382 static void decrypt_done(struct crypto_async_request *areq, int err)
 383 {
 384         struct skcipher_request *req = areq->data;
 385         struct skcipher_request *subreq;
 386         struct rctx *rctx;
 387
 388         rctx = skcipher_request_ctx(req);
 389         subreq = &rctx->subreq;
 390         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 391
 392         err = do_decrypt(req, err ?: post_crypt(req));
 393         if (rctx->left)
 394                 return;
 395
 396         skcipher_request_complete(req, err);
 397 }
 398
 399 static int decrypt(struct skcipher_request *req)
 400 {
 401         return do_decrypt(req, init_crypt(req, decrypt_done));
 402 }
 403
 404 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
 405               struct scatterlist *ssrc, unsigned int nbytes,
 406               struct lrw_crypt_req *req)
 407 {
 408         const unsigned int bsize = LRW_BLOCK_SIZE;
 409         const unsigned int max_blks = req->tbuflen / bsize;
 410         struct lrw_table_ctx *ctx = req->table_ctx;
 411         struct blkcipher_walk walk;
 412         unsigned int nblocks;
 413         be128 *iv, *src, *dst, *t;
 414         be128 *t_buf = req->tbuf;
 415         int err, i;
 416
 417         BUG_ON(max_blks < 1);
 418
 419         blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
 420
 421         err = blkcipher_walk_virt(desc, &walk);
 422         nbytes = walk.nbytes;
 423         if (!nbytes)
 424                 return err;
 425
 426         nblocks = min(walk.nbytes / bsize, max_blks);
 427         src = (be128 *)walk.src.virt.addr;
 428         dst = (be128 *)walk.dst.virt.addr;
 429
 430         /* calculate first value of T */
 431         iv = (be128 *)walk.iv;
 432         t_buf[0] = *iv;
 433
 434         /* T <- I*Key2 */
 435         gf128mul_64k_bbe(&t_buf[0], ctx->table);
 436
 437         i = 0;
 438         goto first;
 439
 440         for (;;) {
 441                 do {
 442                         for (i = 0; i < nblocks; i++) {
 443                                 /* T <- I*Key2, using the optimization
 444                                  * discussed in the specification */
 445                                 be128_xor(&t_buf[i], t,
 446                                                 &ctx->mulinc[get_index128(iv)]);
 447                                 inc(iv);
 448 first:
 449                                 t = &t_buf[i];
 450
 451                                 /* PP <- T xor P */
 452                                 be128_xor(dst + i, t, src + i);
 453                         }
 454
 455                         /* CC <- E(Key2,PP) */
 456                         req->crypt_fn(req->crypt_ctx, (u8 *)dst,
 457                                       nblocks * bsize);
 458
 459                         /* C <- T xor CC */
 460                         for (i = 0; i < nblocks; i++)
 461                                 be128_xor(dst + i, dst + i, &t_buf[i]);
 462
 463                         src += nblocks;
 464                         dst += nblocks;
 465                         nbytes -= nblocks * bsize;
 466                         nblocks = min(nbytes / bsize, max_blks);
 467                 } while (nblocks > 0);
 468
 469                 err = blkcipher_walk_done(desc, &walk, nbytes);
 470                 nbytes = walk.nbytes;
 471                 if (!nbytes)
 472                         break;
 473
 474                 nblocks = min(nbytes / bsize, max_blks);
 475                 src = (be128 *)walk.src.virt.addr;
 476                 dst = (be128 *)walk.dst.virt.addr;
 477         }
 478
 479         return err;
 480 }
 481 EXPORT_SYMBOL_GPL(lrw_crypt);
 482
 483 static int init_tfm(struct crypto_skcipher *tfm)
 484 {
 485         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 486         struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
 487         struct priv *ctx = crypto_skcipher_ctx(tfm);
 488         struct crypto_skcipher *cipher;
 489
 490         cipher = crypto_spawn_skcipher(spawn);
 491         if (IS_ERR(cipher))
 492                 return PTR_ERR(cipher);
 493
 494         ctx->child = cipher;
 495
 496         crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
 497                                          sizeof(struct rctx));
 498
 499         return 0;
 500 }
 501
 502 static void exit_tfm(struct crypto_skcipher *tfm)
 503 {
 504         struct priv *ctx = crypto_skcipher_ctx(tfm);
 505
 506         lrw_free_table(&ctx->table);
 507         crypto_free_skcipher(ctx->child);
 508 }
 509
 510 static void free(struct skcipher_instance *inst)
 511 {
 512         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 513         kfree(inst);
 514 }
 515
 516 static int create(struct crypto_template *tmpl, struct rtattr **tb)
 517 {
 518         struct crypto_skcipher_spawn *spawn;
 519         struct skcipher_instance *inst;
 520         struct crypto_attr_type *algt;
 521         struct skcipher_alg *alg;
 522         const char *cipher_name;
 523         char ecb_name[CRYPTO_MAX_ALG_NAME];
 524         int err;
 525
 526         algt = crypto_get_attr_type(tb);
 527         if (IS_ERR(algt))
 528                 return PTR_ERR(algt);
 529
 530         if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
 531                 return -EINVAL;
 532
 533         cipher_name = crypto_attr_alg_name(tb[1]);
 534         if (IS_ERR(cipher_name))
 535                 return PTR_ERR(cipher_name);
 536
 537         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 538         if (!inst)
 539                 return -ENOMEM;
 540
 541         spawn = skcipher_instance_ctx(inst);
 542
 543         crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
 544         err = crypto_grab_skcipher(spawn, cipher_name, 0,
 545                                    crypto_requires_sync(algt->type,
 546                                                         algt->mask));
 547         if (err == -ENOENT) {
 548                 err = -ENAMETOOLONG;
 549                 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
 550                              cipher_name) >= CRYPTO_MAX_ALG_NAME)
 551                         goto err_free_inst;
 552
 553                 err = crypto_grab_skcipher(spawn, ecb_name, 0,
 554                                            crypto_requires_sync(algt->type,
 555                                                                 algt->mask));
 556         }
 557
 558         if (err)
 559                 goto err_free_inst;
 560
 561         alg = crypto_skcipher_spawn_alg(spawn);
 562
 563         err = -EINVAL;
 564         if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
 565                 goto err_drop_spawn;
 566
 567         if (crypto_skcipher_alg_ivsize(alg))
 568                 goto err_drop_spawn;
 569
 570         err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
 571                                   &alg->base);
 572         if (err)
 573                 goto err_drop_spawn;
 574
 575         err = -EINVAL;
 576         cipher_name = alg->base.cra_name;
 577
 578         /* Alas we screwed up the naming so we have to mangle the
 579          * cipher name.
 580          */
 581         if (!strncmp(cipher_name, "ecb(", 4)) {
 582                 unsigned len;
 583
 584                 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
 585                 if (len < 2 || len >= sizeof(ecb_name))
 586                         goto err_drop_spawn;
 587
 588                 if (ecb_name[len - 1] != ')')
 589                         goto err_drop_spawn;
 590
 591                 ecb_name[len - 1] = 0;
 592
 593                 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 594                              "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME)
 595                         return -ENAMETOOLONG;
 596         }
 597
 598         inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
 599         inst->alg.base.cra_priority = alg->base.cra_priority;
 600         inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
 601         inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
 602                                        (__alignof__(u64) - 1);
 603
 604         inst->alg.ivsize = LRW_BLOCK_SIZE;
 605         inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
 606                                 LRW_BLOCK_SIZE;
 607         inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
 608                                 LRW_BLOCK_SIZE;
 609
 610         inst->alg.base.cra_ctxsize = sizeof(struct priv);
 611
 612         inst->alg.init = init_tfm;
 613         inst->alg.exit = exit_tfm;
 614
 615         inst->alg.setkey = setkey;
 616         inst->alg.encrypt = encrypt;
 617         inst->alg.decrypt = decrypt;
 618
 619         inst->free = free;
 620
 621         err = skcipher_register_instance(tmpl, inst);
 622         if (err)
 623                 goto err_drop_spawn;
 624
 625 out:
 626         return err;
 627
 628 err_drop_spawn:
 629         crypto_drop_skcipher(spawn);
 630 err_free_inst:
 631         kfree(inst);
 632         goto out;
 633 }
 634
 635 static struct crypto_template crypto_tmpl = {
 636         .name = "lrw",
 637         .create = create,
 638         .module = THIS_MODULE,
 639 };
 640
 641 static int __init crypto_module_init(void)
 642 {
 643         return crypto_register_template(&crypto_tmpl);
 644 }
 645
 646 static void __exit crypto_module_exit(void)
 647 {
 648         crypto_unregister_template(&crypto_tmpl);
 649 }
 650
 651 module_init(crypto_module_init);
 652 module_exit(crypto_module_exit);
 653
 654 MODULE_LICENSE("GPL");
 655 MODULE_DESCRIPTION("LRW block cipher mode");
 656 MODULE_ALIAS_CRYPTO("lrw");