crypto/cipher.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Cipher operations.
   5  *
   6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License as published by the Free
  10  * Software Foundation; either version 2 of the License, or (at your option)
  11  * any later version.
  12  *
  13  */
  14 #include <linux/compiler.h>
  15 #include <linux/kernel.h>
  16 #include <linux/crypto.h>
  17 #include <linux/errno.h>
  18 #include <linux/mm.h>
  19 #include <linux/slab.h>
  20 #include <linux/string.h>
  21 #include <asm/scatterlist.h>
  22 #include "internal.h"
  23 #include "scatterwalk.h"
  24
  25 typedef void (cryptfn_t)(void *, u8 *, const u8 *);
  26 typedef void (procfn_t)(struct crypto_tfm *, u8 *,
  27                         u8*, cryptfn_t, void *);
  28
  29 static inline void xor_64(u8 *a, const u8 *b)
  30 {
  31         ((u32 *)a)[0] ^= ((u32 *)b)[0];
  32         ((u32 *)a)[1] ^= ((u32 *)b)[1];
  33 }
  34
  35 static inline void xor_128(u8 *a, const u8 *b)
  36 {
  37         ((u32 *)a)[0] ^= ((u32 *)b)[0];
  38         ((u32 *)a)[1] ^= ((u32 *)b)[1];
  39         ((u32 *)a)[2] ^= ((u32 *)b)[2];
  40         ((u32 *)a)[3] ^= ((u32 *)b)[3];
  41 }
  42
  43 static inline void *prepare_src(struct scatter_walk *walk, int bsize,
  44                                 void *tmp, int in_place)
  45 {
  46         void *src = walk->data;
  47         int n = bsize;
  48
  49         if (unlikely(scatterwalk_across_pages(walk, bsize))) {
  50                 src = tmp;
  51                 n = scatterwalk_copychunks(src, walk, bsize, 0);
  52         }
  53         scatterwalk_advance(walk, n);
  54         return src;
  55 }
  56
  57 static inline void *prepare_dst(struct scatter_walk *walk, int bsize,
  58                                 void *tmp, int in_place)
  59 {
  60         void *dst = walk->data;
  61
  62         if (unlikely(scatterwalk_across_pages(walk, bsize)) || in_place)
  63                 dst = tmp;
  64         return dst;
  65 }
  66
  67 static inline void complete_src(struct scatter_walk *walk, int bsize,
  68                                 void *src, int in_place)
  69 {
  70 }
  71
  72 static inline void complete_dst(struct scatter_walk *walk, int bsize,
  73                                 void *dst, int in_place)
  74 {
  75         int n = bsize;
  76
  77         if (unlikely(scatterwalk_across_pages(walk, bsize)))
  78                 n = scatterwalk_copychunks(dst, walk, bsize, 1);
  79         else if (in_place)
  80                 memcpy(walk->data, dst, bsize);
  81         scatterwalk_advance(walk, n);
  82 }
  83
  84 /*
  85  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
  86  * multiple page boundaries by using temporary blocks.  In user context,
  87  * the kernel is given a chance to schedule us once per block.
  88  */
  89 static int crypt(struct crypto_tfm *tfm,
  90                  struct scatterlist *dst,
  91                  struct scatterlist *src,
  92                  unsigned int nbytes, cryptfn_t crfn,
  93                  procfn_t prfn, void *info)
  94 {
  95         struct scatter_walk walk_in, walk_out;
  96         const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
  97         u8 tmp_src[bsize];
  98         u8 tmp_dst[bsize];
  99
 100         if (!nbytes)
 101                 return 0;
 102
 103         if (nbytes % bsize) {
 104                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 105                 return -EINVAL;
 106         }
 107
 108         scatterwalk_start(&walk_in, src);
 109         scatterwalk_start(&walk_out, dst);
 110
 111         for(;;) {
 112                 u8 *src_p, *dst_p;
 113                 int in_place;
 114
 115                 scatterwalk_map(&walk_in, 0);
 116                 scatterwalk_map(&walk_out, 1);
 117
 118                 in_place = scatterwalk_samebuf(&walk_in, &walk_out);
 119
 120                 do {
 121                         src_p = prepare_src(&walk_in, bsize, tmp_src,
 122                                             in_place);
 123                         dst_p = prepare_dst(&walk_out, bsize, tmp_dst,
 124                                             in_place);
 125
 126                         prfn(tfm, dst_p, src_p, crfn, info);
 127
 128                         complete_src(&walk_in, bsize, src_p, in_place);
 129                         complete_dst(&walk_out, bsize, dst_p, in_place);
 130
 131                         nbytes -= bsize;
 132                 } while (nbytes &&
 133                          !scatterwalk_across_pages(&walk_in, bsize) &&
 134                          !scatterwalk_across_pages(&walk_out, bsize));
 135
 136                 scatterwalk_done(&walk_in, 0, nbytes);
 137                 scatterwalk_done(&walk_out, 1, nbytes);
 138
 139                 if (!nbytes)
 140                         return 0;
 141
 142                 crypto_yield(tfm);
 143         }
 144 }
 145
 146 static void cbc_process_encrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
 147                                 cryptfn_t fn, void *info)
 148 {
 149         u8 *iv = info;
 150
 151         tfm->crt_u.cipher.cit_xor_block(iv, src);
 152         fn(crypto_tfm_ctx(tfm), dst, iv);
 153         memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
 154 }
 155
 156 static void cbc_process_decrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
 157                                 cryptfn_t fn, void *info)
 158 {
 159         u8 *iv = info;
 160
 161         fn(crypto_tfm_ctx(tfm), dst, src);
 162         tfm->crt_u.cipher.cit_xor_block(dst, iv);
 163         memcpy(iv, src, crypto_tfm_alg_blocksize(tfm));
 164 }
 165
 166 static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
 167                         cryptfn_t fn, void *info)
 168 {
 169         fn(crypto_tfm_ctx(tfm), dst, src);
 170 }
 171
 172 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
 173 {
 174         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
 175
 176         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
 177                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 178                 return -EINVAL;
 179         } else
 180                 return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
 181                                        &tfm->crt_flags);
 182 }
 183
 184 static int ecb_encrypt(struct crypto_tfm *tfm,
 185                        struct scatterlist *dst,
 186                        struct scatterlist *src, unsigned int nbytes)
 187 {
 188         return crypt(tfm, dst, src, nbytes,
 189                      tfm->__crt_alg->cra_cipher.cia_encrypt,
 190                      ecb_process, NULL);
 191 }
 192
 193 static int ecb_decrypt(struct crypto_tfm *tfm,
 194                        struct scatterlist *dst,
 195                        struct scatterlist *src,
 196                        unsigned int nbytes)
 197 {
 198         return crypt(tfm, dst, src, nbytes,
 199                      tfm->__crt_alg->cra_cipher.cia_decrypt,
 200                      ecb_process, NULL);
 201 }
 202
 203 static int cbc_encrypt(struct crypto_tfm *tfm,
 204                        struct scatterlist *dst,
 205                        struct scatterlist *src,
 206                        unsigned int nbytes)
 207 {
 208         return crypt(tfm, dst, src, nbytes,
 209                      tfm->__crt_alg->cra_cipher.cia_encrypt,
 210                      cbc_process_encrypt, tfm->crt_cipher.cit_iv);
 211 }
 212
 213 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
 214                           struct scatterlist *dst,
 215                           struct scatterlist *src,
 216                           unsigned int nbytes, u8 *iv)
 217 {
 218         return crypt(tfm, dst, src, nbytes,
 219                      tfm->__crt_alg->cra_cipher.cia_encrypt,
 220                      cbc_process_encrypt, iv);
 221 }
 222
 223 static int cbc_decrypt(struct crypto_tfm *tfm,
 224                        struct scatterlist *dst,
 225                        struct scatterlist *src,
 226                        unsigned int nbytes)
 227 {
 228         return crypt(tfm, dst, src, nbytes,
 229                      tfm->__crt_alg->cra_cipher.cia_decrypt,
 230                      cbc_process_decrypt, tfm->crt_cipher.cit_iv);
 231 }
 232
 233 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
 234                           struct scatterlist *dst,
 235                           struct scatterlist *src,
 236                           unsigned int nbytes, u8 *iv)
 237 {
 238         return crypt(tfm, dst, src, nbytes,
 239                      tfm->__crt_alg->cra_cipher.cia_decrypt,
 240                      cbc_process_decrypt, iv);
 241 }
 242
 243 static int nocrypt(struct crypto_tfm *tfm,
 244                    struct scatterlist *dst,
 245                    struct scatterlist *src,
 246                    unsigned int nbytes)
 247 {
 248         return -ENOSYS;
 249 }
 250
 251 static int nocrypt_iv(struct crypto_tfm *tfm,
 252                       struct scatterlist *dst,
 253                       struct scatterlist *src,
 254                       unsigned int nbytes, u8 *iv)
 255 {
 256         return -ENOSYS;
 257 }
 258
 259 int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
 260 {
 261         u32 mode = flags & CRYPTO_TFM_MODE_MASK;
 262
 263         tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
 264         if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
 265                 tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
 266
 267         return 0;
 268 }
 269
 270 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
 271 {
 272         int ret = 0;
 273         struct cipher_tfm *ops = &tfm->crt_cipher;
 274
 275         ops->cit_setkey = setkey;
 276
 277         switch (tfm->crt_cipher.cit_mode) {
 278         case CRYPTO_TFM_MODE_ECB:
 279                 ops->cit_encrypt = ecb_encrypt;
 280                 ops->cit_decrypt = ecb_decrypt;
 281                 break;
 282
 283         case CRYPTO_TFM_MODE_CBC:
 284                 ops->cit_encrypt = cbc_encrypt;
 285                 ops->cit_decrypt = cbc_decrypt;
 286                 ops->cit_encrypt_iv = cbc_encrypt_iv;
 287                 ops->cit_decrypt_iv = cbc_decrypt_iv;
 288                 break;
 289
 290         case CRYPTO_TFM_MODE_CFB:
 291                 ops->cit_encrypt = nocrypt;
 292                 ops->cit_decrypt = nocrypt;
 293                 ops->cit_encrypt_iv = nocrypt_iv;
 294                 ops->cit_decrypt_iv = nocrypt_iv;
 295                 break;
 296
 297         case CRYPTO_TFM_MODE_CTR:
 298                 ops->cit_encrypt = nocrypt;
 299                 ops->cit_decrypt = nocrypt;
 300                 ops->cit_encrypt_iv = nocrypt_iv;
 301                 ops->cit_decrypt_iv = nocrypt_iv;
 302                 break;
 303
 304         default:
 305                 BUG();
 306         }
 307
 308         if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
 309
 310                 switch (crypto_tfm_alg_blocksize(tfm)) {
 311                 case 8:
 312                         ops->cit_xor_block = xor_64;
 313                         break;
 314
 315                 case 16:
 316                         ops->cit_xor_block = xor_128;
 317                         break;
 318
 319                 default:
 320                         printk(KERN_WARNING "%s: block size %u not supported\n",
 321                                crypto_tfm_alg_name(tfm),
 322                                crypto_tfm_alg_blocksize(tfm));
 323                         ret = -EINVAL;
 324                         goto out;
 325                 }
 326
 327                 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
 328                 ops->cit_iv = kmalloc(ops->cit_ivsize, GFP_KERNEL);
 329                 if (ops->cit_iv == NULL)
 330                         ret = -ENOMEM;
 331         }
 332
 333 out:
 334         return ret;
 335 }
 336
 337 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
 338 {
 339         if (tfm->crt_cipher.cit_iv)
 340                 kfree(tfm->crt_cipher.cit_iv);
 341 }