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 = desc->tfm->__crt_alg->cra_alignmask;
  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 = tfm->__crt_alg->cra_alignmask;
 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 unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
 158                                         u8 *dst, const u8 *src,
 159                                         unsigned int nbytes)
 160 {
 161         struct crypto_tfm *tfm = desc->tfm;
 162         void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
 163         int bsize = crypto_tfm_alg_blocksize(tfm);
 164
 165         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
 166         u8 *iv = desc->info;
 167         unsigned int done = 0;
 168
 169         do {
 170                 xor(iv, src);
 171                 fn(crypto_tfm_ctx(tfm), dst, iv);
 172                 memcpy(iv, dst, bsize);
 173
 174                 src += bsize;
 175                 dst += bsize;
 176         } while ((done += bsize) < nbytes);
 177
 178         return done;
 179 }
 180
 181 static unsigned int cbc_process_decrypt(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         u8 stack[src == dst ? bsize : 0];
 190         u8 *buf = stack;
 191         u8 **dst_p = src == dst ? &buf : &dst;
 192
 193         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
 194         u8 *iv = desc->info;
 195         unsigned int done = 0;
 196
 197         do {
 198                 u8 *tmp_dst = *dst_p;
 199
 200                 fn(crypto_tfm_ctx(tfm), tmp_dst, src);
 201                 xor(tmp_dst, iv);
 202                 memcpy(iv, src, bsize);
 203                 if (tmp_dst != dst)
 204                         memcpy(dst, tmp_dst, bsize);
 205
 206                 src += bsize;
 207                 dst += bsize;
 208         } while ((done += bsize) < nbytes);
 209
 210         return done;
 211 }
 212
 213 static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
 214                                 const u8 *src, unsigned int nbytes)
 215 {
 216         struct crypto_tfm *tfm = desc->tfm;
 217         int bsize = crypto_tfm_alg_blocksize(tfm);
 218         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
 219         unsigned int done = 0;
 220
 221         do {
 222                 fn(crypto_tfm_ctx(tfm), dst, src);
 223
 224                 src += bsize;
 225                 dst += bsize;
 226         } while ((done += bsize) < nbytes);
 227
 228         return done;
 229 }
 230
 231 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
 232 {
 233         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
 234
 235         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
 236                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 237                 return -EINVAL;
 238         } else
 239                 return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
 240                                        &tfm->crt_flags);
 241 }
 242
 243 static int ecb_encrypt(struct crypto_tfm *tfm,
 244                        struct scatterlist *dst,
 245                        struct scatterlist *src, unsigned int nbytes)
 246 {
 247         struct cipher_desc desc;
 248         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 249
 250         desc.tfm = tfm;
 251         desc.crfn = cipher->cia_encrypt;
 252         desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
 253
 254         return crypt(&desc, dst, src, nbytes);
 255 }
 256
 257 static int ecb_decrypt(struct crypto_tfm *tfm,
 258                        struct scatterlist *dst,
 259                        struct scatterlist *src,
 260                        unsigned int nbytes)
 261 {
 262         struct cipher_desc desc;
 263         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 264
 265         desc.tfm = tfm;
 266         desc.crfn = cipher->cia_decrypt;
 267         desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
 268
 269         return crypt(&desc, dst, src, nbytes);
 270 }
 271
 272 static int cbc_encrypt(struct crypto_tfm *tfm,
 273                        struct scatterlist *dst,
 274                        struct scatterlist *src,
 275                        unsigned int nbytes)
 276 {
 277         struct cipher_desc desc;
 278         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 279
 280         desc.tfm = tfm;
 281         desc.crfn = cipher->cia_encrypt;
 282         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
 283         desc.info = tfm->crt_cipher.cit_iv;
 284
 285         return crypt(&desc, dst, src, nbytes);
 286 }
 287
 288 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
 289                           struct scatterlist *dst,
 290                           struct scatterlist *src,
 291                           unsigned int nbytes, u8 *iv)
 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_encrypt;
 298         desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
 299         desc.info = iv;
 300
 301         return crypt(&desc, dst, src, nbytes);
 302 }
 303
 304 static int cbc_decrypt(struct crypto_tfm *tfm,
 305                        struct scatterlist *dst,
 306                        struct scatterlist *src,
 307                        unsigned int nbytes)
 308 {
 309         struct cipher_desc desc;
 310         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 311
 312         desc.tfm = tfm;
 313         desc.crfn = cipher->cia_decrypt;
 314         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
 315         desc.info = tfm->crt_cipher.cit_iv;
 316
 317         return crypt(&desc, dst, src, nbytes);
 318 }
 319
 320 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
 321                           struct scatterlist *dst,
 322                           struct scatterlist *src,
 323                           unsigned int nbytes, u8 *iv)
 324 {
 325         struct cipher_desc desc;
 326         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 327
 328         desc.tfm = tfm;
 329         desc.crfn = cipher->cia_decrypt;
 330         desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
 331         desc.info = iv;
 332
 333         return crypt(&desc, dst, src, nbytes);
 334 }
 335
 336 static int nocrypt(struct crypto_tfm *tfm,
 337                    struct scatterlist *dst,
 338                    struct scatterlist *src,
 339                    unsigned int nbytes)
 340 {
 341         return -ENOSYS;
 342 }
 343
 344 static int nocrypt_iv(struct crypto_tfm *tfm,
 345                       struct scatterlist *dst,
 346                       struct scatterlist *src,
 347                       unsigned int nbytes, u8 *iv)
 348 {
 349         return -ENOSYS;
 350 }
 351
 352 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
 353 {
 354         u32 mode = flags & CRYPTO_TFM_MODE_MASK;
 355
 356         tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
 357         if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
 358                 tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
 359
 360         return 0;
 361 }
 362
 363 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
 364 {
 365         int ret = 0;
 366         struct cipher_tfm *ops = &tfm->crt_cipher;
 367
 368         ops->cit_setkey = setkey;
 369
 370         switch (tfm->crt_cipher.cit_mode) {
 371         case CRYPTO_TFM_MODE_ECB:
 372                 ops->cit_encrypt = ecb_encrypt;
 373                 ops->cit_decrypt = ecb_decrypt;
 374                 break;
 375
 376         case CRYPTO_TFM_MODE_CBC:
 377                 ops->cit_encrypt = cbc_encrypt;
 378                 ops->cit_decrypt = cbc_decrypt;
 379                 ops->cit_encrypt_iv = cbc_encrypt_iv;
 380                 ops->cit_decrypt_iv = cbc_decrypt_iv;
 381                 break;
 382
 383         case CRYPTO_TFM_MODE_CFB:
 384                 ops->cit_encrypt = nocrypt;
 385                 ops->cit_decrypt = nocrypt;
 386                 ops->cit_encrypt_iv = nocrypt_iv;
 387                 ops->cit_decrypt_iv = nocrypt_iv;
 388                 break;
 389
 390         case CRYPTO_TFM_MODE_CTR:
 391                 ops->cit_encrypt = nocrypt;
 392                 ops->cit_decrypt = nocrypt;
 393                 ops->cit_encrypt_iv = nocrypt_iv;
 394                 ops->cit_decrypt_iv = nocrypt_iv;
 395                 break;
 396
 397         default:
 398                 BUG();
 399         }
 400
 401         if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
 402
 403                 switch (crypto_tfm_alg_blocksize(tfm)) {
 404                 case 8:
 405                         ops->cit_xor_block = xor_64;
 406                         break;
 407
 408                 case 16:
 409                         ops->cit_xor_block = xor_128;
 410                         break;
 411
 412                 default:
 413                         printk(KERN_WARNING "%s: block size %u not supported\n",
 414                                crypto_tfm_alg_name(tfm),
 415                                crypto_tfm_alg_blocksize(tfm));
 416                         ret = -EINVAL;
 417                         goto out;
 418                 }
 419
 420                 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
 421                 ops->cit_iv = kmalloc(ops->cit_ivsize, GFP_KERNEL);
 422                 if (ops->cit_iv == NULL)
 423                         ret = -ENOMEM;
 424         }
 425
 426 out:
 427         return ret;
 428 }
 429
 430 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
 431 {
 432         kfree(tfm->crt_cipher.cit_iv);
 433 }