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/algapi.h>
  21 #include <linux/err.h>
  22 #include <linux/init.h>
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/scatterlist.h>
  26 #include <linux/slab.h>
  27
  28 #include <crypto/b128ops.h>
  29 #include <crypto/gf128mul.h>
  30 #include <crypto/lrw.h>
  31
  32 struct priv {
  33         struct crypto_cipher *child;
  34         struct lrw_table_ctx table;
  35 };
  36
  37 static inline void setbit128_bbe(void *b, int bit)
  38 {
  39         __set_bit(bit ^ (0x80 -
  40 #ifdef __BIG_ENDIAN
  41                          BITS_PER_LONG
  42 #else
  43                          BITS_PER_BYTE
  44 #endif
  45                         ), b);
  46 }
  47
  48 int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
  49 {
  50         be128 tmp = { 0 };
  51         int i;
  52
  53         if (ctx->table)
  54                 gf128mul_free_64k(ctx->table);
  55
  56         /* initialize multiplication table for Key2 */
  57         ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
  58         if (!ctx->table)
  59                 return -ENOMEM;
  60
  61         /* initialize optimization table */
  62         for (i = 0; i < 128; i++) {
  63                 setbit128_bbe(&tmp, i);
  64                 ctx->mulinc[i] = tmp;
  65                 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
  66         }
  67
  68         return 0;
  69 }
  70 EXPORT_SYMBOL_GPL(lrw_init_table);
  71
  72 void lrw_free_table(struct lrw_table_ctx *ctx)
  73 {
  74         if (ctx->table)
  75                 gf128mul_free_64k(ctx->table);
  76 }
  77 EXPORT_SYMBOL_GPL(lrw_free_table);
  78
  79 static int setkey(struct crypto_tfm *parent, const u8 *key,
  80                   unsigned int keylen)
  81 {
  82         struct priv *ctx = crypto_tfm_ctx(parent);
  83         struct crypto_cipher *child = ctx->child;
  84         int err, bsize = LRW_BLOCK_SIZE;
  85         const u8 *tweak = key + keylen - bsize;
  86
  87         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  88         crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
  89                                        CRYPTO_TFM_REQ_MASK);
  90         err = crypto_cipher_setkey(child, key, keylen - bsize);
  91         if (err)
  92                 return err;
  93         crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
  94                                      CRYPTO_TFM_RES_MASK);
  95
  96         return lrw_init_table(&ctx->table, tweak);
  97 }
  98
  99 struct sinfo {
 100         be128 t;
 101         struct crypto_tfm *tfm;
 102         void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
 103 };
 104
 105 static inline void inc(be128 *iv)
 106 {
 107         be64_add_cpu(&iv->b, 1);
 108         if (!iv->b)
 109                 be64_add_cpu(&iv->a, 1);
 110 }
 111
 112 static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
 113 {
 114         be128_xor(dst, &s->t, src);             /* PP <- T xor P */
 115         s->fn(s->tfm, dst, dst);                /* CC <- E(Key2,PP) */
 116         be128_xor(dst, dst, &s->t);             /* C <- T xor CC */
 117 }
 118
 119 /* this returns the number of consequative 1 bits starting
 120  * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
 121 static inline int get_index128(be128 *block)
 122 {
 123         int x;
 124         __be32 *p = (__be32 *) block;
 125
 126         for (p += 3, x = 0; x < 128; p--, x += 32) {
 127                 u32 val = be32_to_cpup(p);
 128
 129                 if (!~val)
 130                         continue;
 131
 132                 return x + ffz(val);
 133         }
 134
 135         /*
 136          * If we get here, then x == 128 and we are incrementing the counter
 137          * from all ones to all zeros. This means we must return index 127, i.e.
 138          * the one corresponding to key2*{ 1,...,1 }.
 139          */
 140         return 127;
 141 }
 142
 143 static int crypt(struct blkcipher_desc *d,
 144                  struct blkcipher_walk *w, struct priv *ctx,
 145                  void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
 146 {
 147         int err;
 148         unsigned int avail;
 149         const int bs = LRW_BLOCK_SIZE;
 150         struct sinfo s = {
 151                 .tfm = crypto_cipher_tfm(ctx->child),
 152                 .fn = fn
 153         };
 154         be128 *iv;
 155         u8 *wsrc;
 156         u8 *wdst;
 157
 158         err = blkcipher_walk_virt(d, w);
 159         if (!(avail = w->nbytes))
 160                 return err;
 161
 162         wsrc = w->src.virt.addr;
 163         wdst = w->dst.virt.addr;
 164
 165         /* calculate first value of T */
 166         iv = (be128 *)w->iv;
 167         s.t = *iv;
 168
 169         /* T <- I*Key2 */
 170         gf128mul_64k_bbe(&s.t, ctx->table.table);
 171
 172         goto first;
 173
 174         for (;;) {
 175                 do {
 176                         /* T <- I*Key2, using the optimization
 177                          * discussed in the specification */
 178                         be128_xor(&s.t, &s.t,
 179                                   &ctx->table.mulinc[get_index128(iv)]);
 180                         inc(iv);
 181
 182 first:
 183                         lrw_round(&s, wdst, wsrc);
 184
 185                         wsrc += bs;
 186                         wdst += bs;
 187                 } while ((avail -= bs) >= bs);
 188
 189                 err = blkcipher_walk_done(d, w, avail);
 190                 if (!(avail = w->nbytes))
 191                         break;
 192
 193                 wsrc = w->src.virt.addr;
 194                 wdst = w->dst.virt.addr;
 195         }
 196
 197         return err;
 198 }
 199
 200 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
 201                    struct scatterlist *src, unsigned int nbytes)
 202 {
 203         struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
 204         struct blkcipher_walk w;
 205
 206         blkcipher_walk_init(&w, dst, src, nbytes);
 207         return crypt(desc, &w, ctx,
 208                      crypto_cipher_alg(ctx->child)->cia_encrypt);
 209 }
 210
 211 static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
 212                    struct scatterlist *src, unsigned int nbytes)
 213 {
 214         struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
 215         struct blkcipher_walk w;
 216
 217         blkcipher_walk_init(&w, dst, src, nbytes);
 218         return crypt(desc, &w, ctx,
 219                      crypto_cipher_alg(ctx->child)->cia_decrypt);
 220 }
 221
 222 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
 223               struct scatterlist *ssrc, unsigned int nbytes,
 224               struct lrw_crypt_req *req)
 225 {
 226         const unsigned int bsize = LRW_BLOCK_SIZE;
 227         const unsigned int max_blks = req->tbuflen / bsize;
 228         struct lrw_table_ctx *ctx = req->table_ctx;
 229         struct blkcipher_walk walk;
 230         unsigned int nblocks;
 231         be128 *iv, *src, *dst, *t;
 232         be128 *t_buf = req->tbuf;
 233         int err, i;
 234
 235         BUG_ON(max_blks < 1);
 236
 237         blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
 238
 239         err = blkcipher_walk_virt(desc, &walk);
 240         nbytes = walk.nbytes;
 241         if (!nbytes)
 242                 return err;
 243
 244         nblocks = min(walk.nbytes / bsize, max_blks);
 245         src = (be128 *)walk.src.virt.addr;
 246         dst = (be128 *)walk.dst.virt.addr;
 247
 248         /* calculate first value of T */
 249         iv = (be128 *)walk.iv;
 250         t_buf[0] = *iv;
 251
 252         /* T <- I*Key2 */
 253         gf128mul_64k_bbe(&t_buf[0], ctx->table);
 254
 255         i = 0;
 256         goto first;
 257
 258         for (;;) {
 259                 do {
 260                         for (i = 0; i < nblocks; i++) {
 261                                 /* T <- I*Key2, using the optimization
 262                                  * discussed in the specification */
 263                                 be128_xor(&t_buf[i], t,
 264                                                 &ctx->mulinc[get_index128(iv)]);
 265                                 inc(iv);
 266 first:
 267                                 t = &t_buf[i];
 268
 269                                 /* PP <- T xor P */
 270                                 be128_xor(dst + i, t, src + i);
 271                         }
 272
 273                         /* CC <- E(Key2,PP) */
 274                         req->crypt_fn(req->crypt_ctx, (u8 *)dst,
 275                                       nblocks * bsize);
 276
 277                         /* C <- T xor CC */
 278                         for (i = 0; i < nblocks; i++)
 279                                 be128_xor(dst + i, dst + i, &t_buf[i]);
 280
 281                         src += nblocks;
 282                         dst += nblocks;
 283                         nbytes -= nblocks * bsize;
 284                         nblocks = min(nbytes / bsize, max_blks);
 285                 } while (nblocks > 0);
 286
 287                 err = blkcipher_walk_done(desc, &walk, nbytes);
 288                 nbytes = walk.nbytes;
 289                 if (!nbytes)
 290                         break;
 291
 292                 nblocks = min(nbytes / bsize, max_blks);
 293                 src = (be128 *)walk.src.virt.addr;
 294                 dst = (be128 *)walk.dst.virt.addr;
 295         }
 296
 297         return err;
 298 }
 299 EXPORT_SYMBOL_GPL(lrw_crypt);
 300
 301 static int init_tfm(struct crypto_tfm *tfm)
 302 {
 303         struct crypto_cipher *cipher;
 304         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 305         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 306         struct priv *ctx = crypto_tfm_ctx(tfm);
 307         u32 *flags = &tfm->crt_flags;
 308
 309         cipher = crypto_spawn_cipher(spawn);
 310         if (IS_ERR(cipher))
 311                 return PTR_ERR(cipher);
 312
 313         if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) {
 314                 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 315                 crypto_free_cipher(cipher);
 316                 return -EINVAL;
 317         }
 318
 319         ctx->child = cipher;
 320         return 0;
 321 }
 322
 323 static void exit_tfm(struct crypto_tfm *tfm)
 324 {
 325         struct priv *ctx = crypto_tfm_ctx(tfm);
 326
 327         lrw_free_table(&ctx->table);
 328         crypto_free_cipher(ctx->child);
 329 }
 330
 331 static struct crypto_instance *alloc(struct rtattr **tb)
 332 {
 333         struct crypto_instance *inst;
 334         struct crypto_alg *alg;
 335         int err;
 336
 337         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
 338         if (err)
 339                 return ERR_PTR(err);
 340
 341         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 342                                   CRYPTO_ALG_TYPE_MASK);
 343         if (IS_ERR(alg))
 344                 return ERR_CAST(alg);
 345
 346         inst = crypto_alloc_instance("lrw", alg);
 347         if (IS_ERR(inst))
 348                 goto out_put_alg;
 349
 350         inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 351         inst->alg.cra_priority = alg->cra_priority;
 352         inst->alg.cra_blocksize = alg->cra_blocksize;
 353
 354         if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
 355         else inst->alg.cra_alignmask = alg->cra_alignmask;
 356         inst->alg.cra_type = &crypto_blkcipher_type;
 357
 358         if (!(alg->cra_blocksize % 4))
 359                 inst->alg.cra_alignmask |= 3;
 360         inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
 361         inst->alg.cra_blkcipher.min_keysize =
 362                 alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
 363         inst->alg.cra_blkcipher.max_keysize =
 364                 alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
 365
 366         inst->alg.cra_ctxsize = sizeof(struct priv);
 367
 368         inst->alg.cra_init = init_tfm;
 369         inst->alg.cra_exit = exit_tfm;
 370
 371         inst->alg.cra_blkcipher.setkey = setkey;
 372         inst->alg.cra_blkcipher.encrypt = encrypt;
 373         inst->alg.cra_blkcipher.decrypt = decrypt;
 374
 375 out_put_alg:
 376         crypto_mod_put(alg);
 377         return inst;
 378 }
 379
 380 static void free(struct crypto_instance *inst)
 381 {
 382         crypto_drop_spawn(crypto_instance_ctx(inst));
 383         kfree(inst);
 384 }
 385
 386 static struct crypto_template crypto_tmpl = {
 387         .name = "lrw",
 388         .alloc = alloc,
 389         .free = free,
 390         .module = THIS_MODULE,
 391 };
 392
 393 static int __init crypto_module_init(void)
 394 {
 395         return crypto_register_template(&crypto_tmpl);
 396 }
 397
 398 static void __exit crypto_module_exit(void)
 399 {
 400         crypto_unregister_template(&crypto_tmpl);
 401 }
 402
 403 module_init(crypto_module_init);
 404 module_exit(crypto_module_exit);
 405
 406 MODULE_LICENSE("GPL");
 407 MODULE_DESCRIPTION("LRW block cipher mode");
 408 MODULE_ALIAS_CRYPTO("lrw");