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