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