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
  32 #define LRW_BUFFER_SIZE 128u
  33
  34 #define LRW_BLOCK_SIZE 16
  35
  36 struct priv {
  37         struct crypto_skcipher *child;
  38
  39         /*
  40          * optimizes multiplying a random (non incrementing, as at the
  41          * start of a new sector) value with key2, we could also have
  42          * used 4k optimization tables or no optimization at all. In the
  43          * latter case we would have to store key2 here
  44          */
  45         struct gf128mul_64k *table;
  46
  47         /*
  48          * stores:
  49          *  key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
  50          *  key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
  51          *  key2*{ 0,0,...1,1,1,1,1 }, etc
  52          * needed for optimized multiplication of incrementing values
  53          * with key2
  54          */
  55         be128 mulinc[128];
  56 };
  57
  58 struct rctx {
  59         be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
  60
  61         be128 t;
  62
  63         be128 *ext;
  64
  65         struct scatterlist srcbuf[2];
  66         struct scatterlist dstbuf[2];
  67         struct scatterlist *src;
  68         struct scatterlist *dst;
  69
  70         unsigned int left;
  71
  72         struct skcipher_request subreq;
  73 };
  74
  75 static inline void setbit128_bbe(void *b, int bit)
  76 {
  77         __set_bit(bit ^ (0x80 -
  78 #ifdef __BIG_ENDIAN
  79                          BITS_PER_LONG
  80 #else
  81                          BITS_PER_BYTE
  82 #endif
  83                         ), b);
  84 }
  85
  86 static int setkey(struct crypto_skcipher *parent, const u8 *key,
  87                   unsigned int keylen)
  88 {
  89         struct priv *ctx = crypto_skcipher_ctx(parent);
  90         struct crypto_skcipher *child = ctx->child;
  91         int err, bsize = LRW_BLOCK_SIZE;
  92         const u8 *tweak = key + keylen - bsize;
  93         be128 tmp = { 0 };
  94         int i;
  95
  96         crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  97         crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
  98                                          CRYPTO_TFM_REQ_MASK);
  99         err = crypto_skcipher_setkey(child, key, keylen - bsize);
 100         crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
 101                                           CRYPTO_TFM_RES_MASK);
 102         if (err)
 103                 return err;
 104
 105         if (ctx->table)
 106                 gf128mul_free_64k(ctx->table);
 107
 108         /* initialize multiplication table for Key2 */
 109         ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
 110         if (!ctx->table)
 111                 return -ENOMEM;
 112
 113         /* initialize optimization table */
 114         for (i = 0; i < 128; i++) {
 115                 setbit128_bbe(&tmp, i);
 116                 ctx->mulinc[i] = tmp;
 117                 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
 118         }
 119
 120         return 0;
 121 }
 122
 123 static inline void inc(be128 *iv)
 124 {
 125         be64_add_cpu(&iv->b, 1);
 126         if (!iv->b)
 127                 be64_add_cpu(&iv->a, 1);
 128 }
 129
 130 /* this returns the number of consequative 1 bits starting
 131  * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
 132 static inline int get_index128(be128 *block)
 133 {
 134         int x;
 135         __be32 *p = (__be32 *) block;
 136
 137         for (p += 3, x = 0; x < 128; p--, x += 32) {
 138                 u32 val = be32_to_cpup(p);
 139
 140                 if (!~val)
 141                         continue;
 142
 143                 return x + ffz(val);
 144         }
 145
 146         return x;
 147 }
 148
 149 static int post_crypt(struct skcipher_request *req)
 150 {
 151         struct rctx *rctx = skcipher_request_ctx(req);
 152         be128 *buf = rctx->ext ?: rctx->buf;
 153         struct skcipher_request *subreq;
 154         const int bs = LRW_BLOCK_SIZE;
 155         struct skcipher_walk w;
 156         struct scatterlist *sg;
 157         unsigned offset;
 158         int err;
 159
 160         subreq = &rctx->subreq;
 161         err = skcipher_walk_virt(&w, subreq, false);
 162
 163         while (w.nbytes) {
 164                 unsigned int avail = w.nbytes;
 165                 be128 *wdst;
 166
 167                 wdst = w.dst.virt.addr;
 168
 169                 do {
 170                         be128_xor(wdst, buf++, wdst);
 171                         wdst++;
 172                 } while ((avail -= bs) >= bs);
 173
 174                 err = skcipher_walk_done(&w, avail);
 175         }
 176
 177         rctx->left -= subreq->cryptlen;
 178
 179         if (err || !rctx->left)
 180                 goto out;
 181
 182         rctx->dst = rctx->dstbuf;
 183
 184         scatterwalk_done(&w.out, 0, 1);
 185         sg = w.out.sg;
 186         offset = w.out.offset;
 187
 188         if (rctx->dst != sg) {
 189                 rctx->dst[0] = *sg;
 190                 sg_unmark_end(rctx->dst);
 191                 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
 192         }
 193         rctx->dst[0].length -= offset - sg->offset;
 194         rctx->dst[0].offset = offset;
 195
 196 out:
 197         return err;
 198 }
 199
 200 static int pre_crypt(struct skcipher_request *req)
 201 {
 202         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 203         struct rctx *rctx = skcipher_request_ctx(req);
 204         struct priv *ctx = crypto_skcipher_ctx(tfm);
 205         be128 *buf = rctx->ext ?: rctx->buf;
 206         struct skcipher_request *subreq;
 207         const int bs = LRW_BLOCK_SIZE;
 208         struct skcipher_walk w;
 209         struct scatterlist *sg;
 210         unsigned cryptlen;
 211         unsigned offset;
 212         be128 *iv;
 213         bool more;
 214         int err;
 215
 216         subreq = &rctx->subreq;
 217         skcipher_request_set_tfm(subreq, tfm);
 218
 219         cryptlen = subreq->cryptlen;
 220         more = rctx->left > cryptlen;
 221         if (!more)
 222                 cryptlen = rctx->left;
 223
 224         skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
 225                                    cryptlen, req->iv);
 226
 227         err = skcipher_walk_virt(&w, subreq, false);
 228         iv = w.iv;
 229
 230         while (w.nbytes) {
 231                 unsigned int avail = w.nbytes;
 232                 be128 *wsrc;
 233                 be128 *wdst;
 234
 235                 wsrc = w.src.virt.addr;
 236                 wdst = w.dst.virt.addr;
 237
 238                 do {
 239                         *buf++ = rctx->t;
 240                         be128_xor(wdst++, &rctx->t, wsrc++);
 241
 242                         /* T <- I*Key2, using the optimization
 243                          * discussed in the specification */
 244                         be128_xor(&rctx->t, &rctx->t,
 245                                   &ctx->mulinc[get_index128(iv)]);
 246                         inc(iv);
 247                 } while ((avail -= bs) >= bs);
 248
 249                 err = skcipher_walk_done(&w, avail);
 250         }
 251
 252         skcipher_request_set_tfm(subreq, ctx->child);
 253         skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
 254                                    cryptlen, NULL);
 255
 256         if (err || !more)
 257                 goto out;
 258
 259         rctx->src = rctx->srcbuf;
 260
 261         scatterwalk_done(&w.in, 0, 1);
 262         sg = w.in.sg;
 263         offset = w.in.offset;
 264
 265         if (rctx->src != sg) {
 266                 rctx->src[0] = *sg;
 267                 sg_unmark_end(rctx->src);
 268                 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
 269         }
 270         rctx->src[0].length -= offset - sg->offset;
 271         rctx->src[0].offset = offset;
 272
 273 out:
 274         return err;
 275 }
 276
 277 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
 278 {
 279         struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
 280         struct rctx *rctx = skcipher_request_ctx(req);
 281         struct skcipher_request *subreq;
 282         gfp_t gfp;
 283
 284         subreq = &rctx->subreq;
 285         skcipher_request_set_callback(subreq, req->base.flags, done, req);
 286
 287         gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
 288                                                            GFP_ATOMIC;
 289         rctx->ext = NULL;
 290
 291         subreq->cryptlen = LRW_BUFFER_SIZE;
 292         if (req->cryptlen > LRW_BUFFER_SIZE) {
 293                 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
 294
 295                 rctx->ext = kmalloc(n, gfp);
 296                 if (rctx->ext)
 297                         subreq->cryptlen = n;
 298         }
 299
 300         rctx->src = req->src;
 301         rctx->dst = req->dst;
 302         rctx->left = req->cryptlen;
 303
 304         /* calculate first value of T */
 305         memcpy(&rctx->t, req->iv, sizeof(rctx->t));
 306
 307         /* T <- I*Key2 */
 308         gf128mul_64k_bbe(&rctx->t, ctx->table);
 309
 310         return 0;
 311 }
 312
 313 static void exit_crypt(struct skcipher_request *req)
 314 {
 315         struct rctx *rctx = skcipher_request_ctx(req);
 316
 317         rctx->left = 0;
 318
 319         if (rctx->ext)
 320                 kzfree(rctx->ext);
 321 }
 322
 323 static int do_encrypt(struct skcipher_request *req, int err)
 324 {
 325         struct rctx *rctx = skcipher_request_ctx(req);
 326         struct skcipher_request *subreq;
 327
 328         subreq = &rctx->subreq;
 329
 330         while (!err && rctx->left) {
 331                 err = pre_crypt(req) ?:
 332                       crypto_skcipher_encrypt(subreq) ?:
 333                       post_crypt(req);
 334
 335                 if (err == -EINPROGRESS || err == -EBUSY)
 336                         return err;
 337         }
 338
 339         exit_crypt(req);
 340         return err;
 341 }
 342
 343 static void encrypt_done(struct crypto_async_request *areq, int err)
 344 {
 345         struct skcipher_request *req = areq->data;
 346         struct skcipher_request *subreq;
 347         struct rctx *rctx;
 348
 349         rctx = skcipher_request_ctx(req);
 350
 351         if (err == -EINPROGRESS) {
 352                 if (rctx->left != req->cryptlen)
 353                         return;
 354                 goto out;
 355         }
 356
 357         subreq = &rctx->subreq;
 358         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 359
 360         err = do_encrypt(req, err ?: post_crypt(req));
 361         if (rctx->left)
 362                 return;
 363
 364 out:
 365         skcipher_request_complete(req, err);
 366 }
 367
 368 static int encrypt(struct skcipher_request *req)
 369 {
 370         return do_encrypt(req, init_crypt(req, encrypt_done));
 371 }
 372
 373 static int do_decrypt(struct skcipher_request *req, int err)
 374 {
 375         struct rctx *rctx = skcipher_request_ctx(req);
 376         struct skcipher_request *subreq;
 377
 378         subreq = &rctx->subreq;
 379
 380         while (!err && rctx->left) {
 381                 err = pre_crypt(req) ?:
 382                       crypto_skcipher_decrypt(subreq) ?:
 383                       post_crypt(req);
 384
 385                 if (err == -EINPROGRESS || err == -EBUSY)
 386                         return err;
 387         }
 388
 389         exit_crypt(req);
 390         return err;
 391 }
 392
 393 static void decrypt_done(struct crypto_async_request *areq, int err)
 394 {
 395         struct skcipher_request *req = areq->data;
 396         struct skcipher_request *subreq;
 397         struct rctx *rctx;
 398
 399         rctx = skcipher_request_ctx(req);
 400
 401         if (err == -EINPROGRESS) {
 402                 if (rctx->left != req->cryptlen)
 403                         return;
 404                 goto out;
 405         }
 406
 407         subreq = &rctx->subreq;
 408         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
 409
 410         err = do_decrypt(req, err ?: post_crypt(req));
 411         if (rctx->left)
 412                 return;
 413
 414 out:
 415         skcipher_request_complete(req, err);
 416 }
 417
 418 static int decrypt(struct skcipher_request *req)
 419 {
 420         return do_decrypt(req, init_crypt(req, decrypt_done));
 421 }
 422
 423 static int init_tfm(struct crypto_skcipher *tfm)
 424 {
 425         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 426         struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
 427         struct priv *ctx = crypto_skcipher_ctx(tfm);
 428         struct crypto_skcipher *cipher;
 429
 430         cipher = crypto_spawn_skcipher(spawn);
 431         if (IS_ERR(cipher))
 432                 return PTR_ERR(cipher);
 433
 434         ctx->child = cipher;
 435
 436         crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
 437                                          sizeof(struct rctx));
 438
 439         return 0;
 440 }
 441
 442 static void exit_tfm(struct crypto_skcipher *tfm)
 443 {
 444         struct priv *ctx = crypto_skcipher_ctx(tfm);
 445
 446         if (ctx->table)
 447                 gf128mul_free_64k(ctx->table);
 448         crypto_free_skcipher(ctx->child);
 449 }
 450
 451 static void free(struct skcipher_instance *inst)
 452 {
 453         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 454         kfree(inst);
 455 }
 456
 457 static int create(struct crypto_template *tmpl, struct rtattr **tb)
 458 {
 459         struct crypto_skcipher_spawn *spawn;
 460         struct skcipher_instance *inst;
 461         struct crypto_attr_type *algt;
 462         struct skcipher_alg *alg;
 463         const char *cipher_name;
 464         char ecb_name[CRYPTO_MAX_ALG_NAME];
 465         int err;
 466
 467         algt = crypto_get_attr_type(tb);
 468         if (IS_ERR(algt))
 469                 return PTR_ERR(algt);
 470
 471         if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
 472                 return -EINVAL;
 473
 474         cipher_name = crypto_attr_alg_name(tb[1]);
 475         if (IS_ERR(cipher_name))
 476                 return PTR_ERR(cipher_name);
 477
 478         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 479         if (!inst)
 480                 return -ENOMEM;
 481
 482         spawn = skcipher_instance_ctx(inst);
 483
 484         crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
 485         err = crypto_grab_skcipher(spawn, cipher_name, 0,
 486                                    crypto_requires_sync(algt->type,
 487                                                         algt->mask));
 488         if (err == -ENOENT) {
 489                 err = -ENAMETOOLONG;
 490                 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
 491                              cipher_name) >= CRYPTO_MAX_ALG_NAME)
 492                         goto err_free_inst;
 493
 494                 err = crypto_grab_skcipher(spawn, ecb_name, 0,
 495                                            crypto_requires_sync(algt->type,
 496                                                                 algt->mask));
 497         }
 498
 499         if (err)
 500                 goto err_free_inst;
 501
 502         alg = crypto_skcipher_spawn_alg(spawn);
 503
 504         err = -EINVAL;
 505         if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
 506                 goto err_drop_spawn;
 507
 508         if (crypto_skcipher_alg_ivsize(alg))
 509                 goto err_drop_spawn;
 510
 511         err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
 512                                   &alg->base);
 513         if (err)
 514                 goto err_drop_spawn;
 515
 516         err = -EINVAL;
 517         cipher_name = alg->base.cra_name;
 518
 519         /* Alas we screwed up the naming so we have to mangle the
 520          * cipher name.
 521          */
 522         if (!strncmp(cipher_name, "ecb(", 4)) {
 523                 unsigned len;
 524
 525                 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
 526                 if (len < 2 || len >= sizeof(ecb_name))
 527                         goto err_drop_spawn;
 528
 529                 if (ecb_name[len - 1] != ')')
 530                         goto err_drop_spawn;
 531
 532                 ecb_name[len - 1] = 0;
 533
 534                 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 535                              "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
 536                         err = -ENAMETOOLONG;
 537                         goto err_drop_spawn;
 538                 }
 539         } else
 540                 goto err_drop_spawn;
 541
 542         inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
 543         inst->alg.base.cra_priority = alg->base.cra_priority;
 544         inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
 545         inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
 546                                        (__alignof__(u64) - 1);
 547
 548         inst->alg.ivsize = LRW_BLOCK_SIZE;
 549         inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
 550                                 LRW_BLOCK_SIZE;
 551         inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
 552                                 LRW_BLOCK_SIZE;
 553
 554         inst->alg.base.cra_ctxsize = sizeof(struct priv);
 555
 556         inst->alg.init = init_tfm;
 557         inst->alg.exit = exit_tfm;
 558
 559         inst->alg.setkey = setkey;
 560         inst->alg.encrypt = encrypt;
 561         inst->alg.decrypt = decrypt;
 562
 563         inst->free = free;
 564
 565         err = skcipher_register_instance(tmpl, inst);
 566         if (err)
 567                 goto err_drop_spawn;
 568
 569 out:
 570         return err;
 571
 572 err_drop_spawn:
 573         crypto_drop_skcipher(spawn);
 574 err_free_inst:
 575         kfree(inst);
 576         goto out;
 577 }
 578
 579 static struct crypto_template crypto_tmpl = {
 580         .name = "lrw",
 581         .create = create,
 582         .module = THIS_MODULE,
 583 };
 584
 585 static int __init crypto_module_init(void)
 586 {
 587         return crypto_register_template(&crypto_tmpl);
 588 }
 589
 590 static void __exit crypto_module_exit(void)
 591 {
 592         crypto_unregister_template(&crypto_tmpl);
 593 }
 594
 595 module_init(crypto_module_init);
 596 module_exit(crypto_module_exit);
 597
 598 MODULE_LICENSE("GPL");
 599 MODULE_DESCRIPTION("LRW block cipher mode");
 600 MODULE_ALIAS_CRYPTO("lrw");