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         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 long 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         nbytes -= bsize;
 195
 196         do {
 197                 xor(iv, src);
 198                 fn(crypto_tfm_ctx(tfm), dst, iv);
 199                 memcpy(iv, dst, bsize);
 200
 201                 src += bsize;
 202                 dst += bsize;
 203         } while ((done += bsize) <= nbytes);
 204
 205         return done;
 206 }
 207
 208 static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
 209                                         u8 *dst, const u8 *src,
 210                                         unsigned int nbytes)
 211 {
 212         struct crypto_tfm *tfm = desc->tfm;
 213         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
 214         int bsize = crypto_tfm_alg_blocksize(tfm);
 215
 216         u8 stack[src == dst ? bsize : 0];
 217         u8 *buf = stack;
 218         u8 **dst_p = src == dst ? &buf : &dst;
 219
 220         void (*fn)(void *, 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(crypto_tfm_ctx(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)(void *, u8 *, const u8 *) = desc->crfn;
 248         unsigned int done = 0;
 249
 250         nbytes -= bsize;
 251
 252         do {
 253                 fn(crypto_tfm_ctx(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         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
 267                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 268                 return -EINVAL;
 269         } else
 270                 return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
 271                                        &tfm->crt_flags);
 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
 387         tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
 388         if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
 389                 tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
 390
 391         return 0;
 392 }
 393
 394 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
 395 {
 396         int ret = 0;
 397         struct cipher_tfm *ops = &tfm->crt_cipher;
 398
 399         ops->cit_setkey = setkey;
 400
 401         switch (tfm->crt_cipher.cit_mode) {
 402         case CRYPTO_TFM_MODE_ECB:
 403                 ops->cit_encrypt = ecb_encrypt;
 404                 ops->cit_decrypt = ecb_decrypt;
 405                 break;
 406
 407         case CRYPTO_TFM_MODE_CBC:
 408                 ops->cit_encrypt = cbc_encrypt;
 409                 ops->cit_decrypt = cbc_decrypt;
 410                 ops->cit_encrypt_iv = cbc_encrypt_iv;
 411                 ops->cit_decrypt_iv = cbc_decrypt_iv;
 412                 break;
 413
 414         case CRYPTO_TFM_MODE_CFB:
 415                 ops->cit_encrypt = nocrypt;
 416                 ops->cit_decrypt = nocrypt;
 417                 ops->cit_encrypt_iv = nocrypt_iv;
 418                 ops->cit_decrypt_iv = nocrypt_iv;
 419                 break;
 420
 421         case CRYPTO_TFM_MODE_CTR:
 422                 ops->cit_encrypt = nocrypt;
 423                 ops->cit_decrypt = nocrypt;
 424                 ops->cit_encrypt_iv = nocrypt_iv;
 425                 ops->cit_decrypt_iv = nocrypt_iv;
 426                 break;
 427
 428         default:
 429                 BUG();
 430         }
 431
 432         if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
 433                 unsigned long align;
 434                 unsigned long addr;
 435
 436                 switch (crypto_tfm_alg_blocksize(tfm)) {
 437                 case 8:
 438                         ops->cit_xor_block = xor_64;
 439                         break;
 440
 441                 case 16:
 442                         ops->cit_xor_block = xor_128;
 443                         break;
 444
 445                 default:
 446                         printk(KERN_WARNING "%s: block size %u not supported\n",
 447                                crypto_tfm_alg_name(tfm),
 448                                crypto_tfm_alg_blocksize(tfm));
 449                         ret = -EINVAL;
 450                         goto out;
 451                 }
 452
 453                 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
 454                 align = crypto_tfm_alg_alignmask(tfm) + 1;
 455                 addr = (unsigned long)crypto_tfm_ctx(tfm);
 456                 addr = ALIGN(addr, align);
 457                 addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
 458                 ops->cit_iv = (void *)addr;
 459         }
 460
 461 out:
 462         return ret;
 463 }
 464
 465 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
 466 {
 467 }