crypto/cipher.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Cipher operations.
   5  *
   6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   7  * Copyright (c) 2005 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  */
  15 #include <linux/compiler.h>
  16 #include <linux/kernel.h>
  17 #include <linux/crypto.h>
  18 #include <linux/errno.h>
  19 #include <linux/mm.h>
  20 #include <linux/slab.h>
  21 #include <linux/string.h>
  22 #include <asm/scatterlist.h>
  23 #include "internal.h"
  24 #include "scatterwalk.h"
  25
  26 struct cipher_alg_compat {
  27         unsigned int cia_min_keysize;
  28         unsigned int cia_max_keysize;
  29         int (*cia_setkey)(struct crypto_tfm *tfm, const u8 *key,
  30                           unsigned int keylen);
  31         void (*cia_encrypt)(struct crypto_tfm *tfm, u8 *dst, const u8 *src);
  32         void (*cia_decrypt)(struct crypto_tfm *tfm, u8 *dst, const u8 *src);
  33
  34         unsigned int (*cia_encrypt_ecb)(const struct cipher_desc *desc,
  35                                         u8 *dst, const u8 *src,
  36                                         unsigned int nbytes);
  37         unsigned int (*cia_decrypt_ecb)(const struct cipher_desc *desc,
  38                                         u8 *dst, const u8 *src,
  39                                         unsigned int nbytes);
  40         unsigned int (*cia_encrypt_cbc)(const struct cipher_desc *desc,
  41                                         u8 *dst, const u8 *src,
  42                                         unsigned int nbytes);
  43         unsigned int (*cia_decrypt_cbc)(const struct cipher_desc *desc,
  44                                         u8 *dst, const u8 *src,
  45                                         unsigned int nbytes);
  46 };
  47
  48 static inline void xor_64(u8 *a, const u8 *b)
  49 {
  50         ((u32 *)a)[0] ^= ((u32 *)b)[0];
  51         ((u32 *)a)[1] ^= ((u32 *)b)[1];
  52 }
  53
  54 static inline void xor_128(u8 *a, const u8 *b)
  55 {
  56         ((u32 *)a)[0] ^= ((u32 *)b)[0];
  57         ((u32 *)a)[1] ^= ((u32 *)b)[1];
  58         ((u32 *)a)[2] ^= ((u32 *)b)[2];
  59         ((u32 *)a)[3] ^= ((u32 *)b)[3];
  60 }
  61
  62 static unsigned int crypt_slow(const struct cipher_desc *desc,
  63                                struct scatter_walk *in,
  64                                struct scatter_walk *out, unsigned int bsize)
  65 {
  66         unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
  67         u8 buffer[bsize * 2 + alignmask];
  68         u8 *src = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
  69         u8 *dst = src + bsize;
  70
  71         scatterwalk_copychunks(src, in, bsize, 0);
  72         desc->prfn(desc, dst, src, bsize);
  73         scatterwalk_copychunks(dst, out, bsize, 1);
  74
  75         return bsize;
  76 }
  77
  78 static inline unsigned int crypt_fast(const struct cipher_desc *desc,
  79                                       struct scatter_walk *in,
  80                                       struct scatter_walk *out,
  81                                       unsigned int nbytes, u8 *tmp)
  82 {
  83         u8 *src, *dst;
  84         u8 *real_src, *real_dst;
  85
  86         real_src = scatterwalk_map(in, 0);
  87         real_dst = scatterwalk_map(out, 1);
  88
  89         src = real_src;
  90         dst = scatterwalk_samebuf(in, out) ? src : real_dst;
  91
  92         if (tmp) {
  93                 memcpy(tmp, src, nbytes);
  94                 src = tmp;
  95                 dst = tmp;
  96         }
  97
  98         nbytes = desc->prfn(desc, dst, src, nbytes);
  99
 100         if (tmp)
 101                 memcpy(real_dst, tmp, nbytes);
 102
 103         scatterwalk_unmap(real_src, 0);
 104         scatterwalk_unmap(real_dst, 1);
 105
 106         scatterwalk_advance(in, nbytes);
 107         scatterwalk_advance(out, nbytes);
 108
 109         return nbytes;
 110 }
 111
 112 /*
 113  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
 114  * multiple page boundaries by using temporary blocks.  In user context,
 115  * the kernel is given a chance to schedule us once per page.
 116  */
 117 static int crypt(const struct cipher_desc *desc,
 118                  struct scatterlist *dst,
 119                  struct scatterlist *src,
 120                  unsigned int nbytes)
 121 {
 122         struct scatter_walk walk_in, walk_out;
 123         struct crypto_tfm *tfm = desc->tfm;
 124         const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
 125         unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
 126         unsigned long buffer = 0;
 127
 128         if (!nbytes)
 129                 return 0;
 130
 131         if (nbytes % bsize) {
 132                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 133                 return -EINVAL;
 134         }
 135
 136         scatterwalk_start(&walk_in, src);
 137         scatterwalk_start(&walk_out, dst);
 138
 139         for(;;) {
 140                 unsigned int n = nbytes;
 141                 u8 *tmp = NULL;
 142
 143                 if (!scatterwalk_aligned(&walk_in, alignmask) ||
 144                     !scatterwalk_aligned(&walk_out, alignmask)) {
 145                         if (!buffer) {
 146                                 buffer = __get_free_page(GFP_ATOMIC);
 147                                 if (!buffer)
 148                                         n = 0;
 149                         }
 150                         tmp = (u8 *)buffer;
 151                 }
 152
 153                 n = scatterwalk_clamp(&walk_in, n);
 154                 n = scatterwalk_clamp(&walk_out, n);
 155
 156                 if (likely(n >= bsize))
 157                         n = crypt_fast(desc, &walk_in, &walk_out, n, tmp);
 158                 else
 159                         n = crypt_slow(desc, &walk_in, &walk_out, bsize);
 160
 161                 nbytes -= n;
 162
 163                 scatterwalk_done(&walk_in, 0, nbytes);
 164                 scatterwalk_done(&walk_out, 1, nbytes);
 165
 166                 if (!nbytes)
 167                         break;
 168
 169                 crypto_yield(tfm->crt_flags);
 170         }
 171
 172         if (buffer)
 173                 free_page(buffer);
 174
 175         return 0;
 176 }
 177
 178 static int crypt_iv_unaligned(struct cipher_desc *desc,
 179                               struct scatterlist *dst,
 180                               struct scatterlist *src,
 181                               unsigned int nbytes)
 182 {
 183         struct crypto_tfm *tfm = desc->tfm;
 184         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 185         u8 *iv = desc->info;
 186
 187         if (unlikely(((unsigned long)iv & alignmask))) {
 188                 unsigned int ivsize = tfm->crt_cipher.cit_ivsize;
 189                 u8 buffer[ivsize + alignmask];
 190                 u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 191                 int err;
 192
 193                 desc->info = memcpy(tmp, iv, ivsize);
 194                 err = crypt(desc, dst, src, nbytes);
 195                 memcpy(iv, tmp, ivsize);
 196
 197                 return err;
 198         }
 199
 200         return crypt(desc, dst, src, nbytes);
 201 }
 202
 203 static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
 204                                         u8 *dst, const u8 *src,
 205                                         unsigned int nbytes)
 206 {
 207         struct crypto_tfm *tfm = desc->tfm;
 208         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
 209         int bsize = crypto_tfm_alg_blocksize(tfm);
 210
 211         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
 212         u8 *iv = desc->info;
 213         unsigned int done = 0;
 214
 215         nbytes -= bsize;
 216
 217         do {
 218                 xor(iv, src);
 219                 fn(tfm, dst, iv);
 220                 memcpy(iv, dst, bsize);
 221
 222                 src += bsize;
 223                 dst += bsize;
 224         } while ((done += bsize) <= nbytes);
 225
 226         return done;
 227 }
 228
 229 static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
 230                                         u8 *dst, const u8 *src,
 231                                         unsigned int nbytes)
 232 {
 233         struct crypto_tfm *tfm = desc->tfm;
 234         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
 235         int bsize = crypto_tfm_alg_blocksize(tfm);
 236         unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
 237
 238         u8 stack[src == dst ? bsize + alignmask : 0];
 239         u8 *buf = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
 240         u8 **dst_p = src == dst ? &buf : &dst;
 241
 242         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
 243         u8 *iv = desc->info;
 244         unsigned int done = 0;
 245
 246         nbytes -= bsize;
 247
 248         do {
 249                 u8 *tmp_dst = *dst_p;
 250
 251                 fn(tfm, tmp_dst, src);
 252                 xor(tmp_dst, iv);
 253                 memcpy(iv, src, bsize);
 254                 if (tmp_dst != dst)
 255                         memcpy(dst, tmp_dst, bsize);
 256
 257                 src += bsize;
 258                 dst += bsize;
 259         } while ((done += bsize) <= nbytes);
 260
 261         return done;
 262 }
 263
 264 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
 265                                 const u8 *src, unsigned int nbytes)
 266 {
 267         struct crypto_tfm *tfm = desc->tfm;
 268         int bsize = crypto_tfm_alg_blocksize(tfm);
 269         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
 270         unsigned int done = 0;
 271
 272         nbytes -= bsize;
 273
 274         do {
 275                 fn(tfm, dst, src);
 276
 277                 src += bsize;
 278                 dst += bsize;
 279         } while ((done += bsize) <= nbytes);
 280
 281         return done;
 282 }
 283
 284 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
 285 {
 286         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
 287
 288         tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
 289         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
 290                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 291                 return -EINVAL;
 292         } else
 293                 return cia->cia_setkey(tfm, key, keylen);
 294 }
 295
 296 static int ecb_encrypt(struct crypto_tfm *tfm,
 297                        struct scatterlist *dst,
 298                        struct scatterlist *src, unsigned int nbytes)
 299 {
 300         struct cipher_desc desc;
 301         struct cipher_alg_compat *cipher = (void *)&tfm->__crt_alg->cra_cipher;
 302
 303         desc.tfm = tfm;
 304         desc.crfn = cipher->cia_encrypt;
 305         desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
 306
 307         return crypt(&desc, dst, src, nbytes);
 308 }
 309
 310 static int ecb_decrypt(struct crypto_tfm *tfm,
 311                        struct scatterlist *dst,
 312                        struct scatterlist *src,
 313                        unsigned int nbytes)
 314 {
 315         struct cipher_desc desc;
 316         struct cipher_alg_compat *cipher = (void *)&tfm->__crt_alg->cra_cipher;
 317
 318         desc.tfm = tfm;
 319         desc.crfn = cipher->cia_decrypt;
 320         desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
 321
 322         return crypt(&desc, dst, src, nbytes);
 323 }
 324
 325 static int cbc_encrypt(struct crypto_tfm *tfm,
 326                        struct scatterlist *dst,
 327                        struct scatterlist *src,
 328                        unsigned int nbytes)
 329 {
 330         struct cipher_desc desc;
 331         struct cipher_alg_compat *cipher = (void *)&tfm->__crt_alg->cra_cipher;
 332
 333         desc.tfm = tfm;
 334         desc.crfn = cipher->cia_encrypt;
 335         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
 336         desc.info = tfm->crt_cipher.cit_iv;
 337
 338         return crypt(&desc, dst, src, nbytes);
 339 }
 340
 341 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
 342                           struct scatterlist *dst,
 343                           struct scatterlist *src,
 344                           unsigned int nbytes, u8 *iv)
 345 {
 346         struct cipher_desc desc;
 347         struct cipher_alg_compat *cipher = (void *)&tfm->__crt_alg->cra_cipher;
 348
 349         desc.tfm = tfm;
 350         desc.crfn = cipher->cia_encrypt;
 351         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
 352         desc.info = iv;
 353
 354         return crypt_iv_unaligned(&desc, dst, src, nbytes);
 355 }
 356
 357 static int cbc_decrypt(struct crypto_tfm *tfm,
 358                        struct scatterlist *dst,
 359                        struct scatterlist *src,
 360                        unsigned int nbytes)
 361 {
 362         struct cipher_desc desc;
 363         struct cipher_alg_compat *cipher = (void *)&tfm->__crt_alg->cra_cipher;
 364
 365         desc.tfm = tfm;
 366         desc.crfn = cipher->cia_decrypt;
 367         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
 368         desc.info = tfm->crt_cipher.cit_iv;
 369
 370         return crypt(&desc, dst, src, nbytes);
 371 }
 372
 373 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
 374                           struct scatterlist *dst,
 375                           struct scatterlist *src,
 376                           unsigned int nbytes, u8 *iv)
 377 {
 378         struct cipher_desc desc;
 379         struct cipher_alg_compat *cipher = (void *)&tfm->__crt_alg->cra_cipher;
 380
 381         desc.tfm = tfm;
 382         desc.crfn = cipher->cia_decrypt;
 383         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
 384         desc.info = iv;
 385
 386         return crypt_iv_unaligned(&desc, dst, src, nbytes);
 387 }
 388
 389 static int nocrypt(struct crypto_tfm *tfm,
 390                    struct scatterlist *dst,
 391                    struct scatterlist *src,
 392                    unsigned int nbytes)
 393 {
 394         return -ENOSYS;
 395 }
 396
 397 static int nocrypt_iv(struct crypto_tfm *tfm,
 398                       struct scatterlist *dst,
 399                       struct scatterlist *src,
 400                       unsigned int nbytes, u8 *iv)
 401 {
 402         return -ENOSYS;
 403 }
 404
 405 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
 406 {
 407         u32 mode = flags & CRYPTO_TFM_MODE_MASK;
 408         tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
 409         return 0;
 410 }
 411
 412 static void cipher_crypt_unaligned(void (*fn)(struct crypto_tfm *, u8 *,
 413                                               const u8 *),
 414                                    struct crypto_tfm *tfm,
 415                                    u8 *dst, const u8 *src)
 416 {
 417         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 418         unsigned int size = crypto_tfm_alg_blocksize(tfm);
 419         u8 buffer[size + alignmask];
 420         u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 421
 422         memcpy(tmp, src, size);
 423         fn(tfm, tmp, tmp);
 424         memcpy(dst, tmp, size);
 425 }
 426
 427 static void cipher_encrypt_unaligned(struct crypto_tfm *tfm,
 428                                      u8 *dst, const u8 *src)
 429 {
 430         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 431         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 432
 433         if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
 434                 cipher_crypt_unaligned(cipher->cia_encrypt, tfm, dst, src);
 435                 return;
 436         }
 437
 438         cipher->cia_encrypt(tfm, dst, src);
 439 }
 440
 441 static void cipher_decrypt_unaligned(struct crypto_tfm *tfm,
 442                                      u8 *dst, const u8 *src)
 443 {
 444         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 445         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 446
 447         if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
 448                 cipher_crypt_unaligned(cipher->cia_decrypt, tfm, dst, src);
 449                 return;
 450         }
 451
 452         cipher->cia_decrypt(tfm, dst, src);
 453 }
 454
 455 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
 456 {
 457         int ret = 0;
 458         struct cipher_tfm *ops = &tfm->crt_cipher;
 459         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 460
 461         ops->cit_setkey = setkey;
 462         ops->cit_encrypt_one = crypto_tfm_alg_alignmask(tfm) ?
 463                 cipher_encrypt_unaligned : cipher->cia_encrypt;
 464         ops->cit_decrypt_one = crypto_tfm_alg_alignmask(tfm) ?
 465                 cipher_decrypt_unaligned : cipher->cia_decrypt;
 466
 467         switch (tfm->crt_cipher.cit_mode) {
 468         case CRYPTO_TFM_MODE_ECB:
 469                 ops->cit_encrypt = ecb_encrypt;
 470                 ops->cit_decrypt = ecb_decrypt;
 471                 ops->cit_encrypt_iv = nocrypt_iv;
 472                 ops->cit_decrypt_iv = nocrypt_iv;
 473                 break;
 474
 475         case CRYPTO_TFM_MODE_CBC:
 476                 ops->cit_encrypt = cbc_encrypt;
 477                 ops->cit_decrypt = cbc_decrypt;
 478                 ops->cit_encrypt_iv = cbc_encrypt_iv;
 479                 ops->cit_decrypt_iv = cbc_decrypt_iv;
 480                 break;
 481
 482         case CRYPTO_TFM_MODE_CFB:
 483                 ops->cit_encrypt = nocrypt;
 484                 ops->cit_decrypt = nocrypt;
 485                 ops->cit_encrypt_iv = nocrypt_iv;
 486                 ops->cit_decrypt_iv = nocrypt_iv;
 487                 break;
 488
 489         case CRYPTO_TFM_MODE_CTR:
 490                 ops->cit_encrypt = nocrypt;
 491                 ops->cit_decrypt = nocrypt;
 492                 ops->cit_encrypt_iv = nocrypt_iv;
 493                 ops->cit_decrypt_iv = nocrypt_iv;
 494                 break;
 495
 496         default:
 497                 BUG();
 498         }
 499
 500         if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
 501                 unsigned long align;
 502                 unsigned long addr;
 503
 504                 switch (crypto_tfm_alg_blocksize(tfm)) {
 505                 case 8:
 506                         ops->cit_xor_block = xor_64;
 507                         break;
 508
 509                 case 16:
 510                         ops->cit_xor_block = xor_128;
 511                         break;
 512
 513                 default:
 514                         printk(KERN_WARNING "%s: block size %u not supported\n",
 515                                crypto_tfm_alg_name(tfm),
 516                                crypto_tfm_alg_blocksize(tfm));
 517                         ret = -EINVAL;
 518                         goto out;
 519                 }
 520
 521                 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
 522                 align = crypto_tfm_alg_alignmask(tfm) + 1;
 523                 addr = (unsigned long)crypto_tfm_ctx(tfm);
 524                 addr = ALIGN(addr, align);
 525                 addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
 526                 ops->cit_iv = (void *)addr;
 527         }
 528
 529 out:
 530         return ret;
 531 }
 532
 533 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
 534 {
 535 }