include/crypto/xts.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _CRYPTO_XTS_H
   3 #define _CRYPTO_XTS_H
   4
   5 #include <crypto/b128ops.h>
   6 #include <crypto/internal/skcipher.h>
   7 #include <linux/fips.h>
   8
   9 struct scatterlist;
  10 struct blkcipher_desc;
  11
  12 #define XTS_BLOCK_SIZE 16
  13
  14 struct xts_crypt_req {
  15         le128 *tbuf;
  16         unsigned int tbuflen;
  17
  18         void *tweak_ctx;
  19         void (*tweak_fn)(void *ctx, u8* dst, const u8* src);
  20         void *crypt_ctx;
  21         void (*crypt_fn)(void *ctx, u8 *blks, unsigned int nbytes);
  22 };
  23
  24 #define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x))
  25
  26 int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
  27               struct scatterlist *src, unsigned int nbytes,
  28               struct xts_crypt_req *req);
  29
  30 static inline int xts_check_key(struct crypto_tfm *tfm,
  31                                 const u8 *key, unsigned int keylen)
  32 {
  33         u32 *flags = &tfm->crt_flags;
  34
  35         /*
  36          * key consists of keys of equal size concatenated, therefore
  37          * the length must be even.
  38          */
  39         if (keylen % 2) {
  40                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  41                 return -EINVAL;
  42         }
  43
  44         /* ensure that the AES and tweak key are not identical */
  45         if (fips_enabled &&
  46             !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
  47                 *flags |= CRYPTO_TFM_RES_WEAK_KEY;
  48                 return -EINVAL;
  49         }
  50
  51         return 0;
  52 }
  53
  54 static inline int xts_verify_key(struct crypto_skcipher *tfm,
  55                                  const u8 *key, unsigned int keylen)
  56 {
  57         /*
  58          * key consists of keys of equal size concatenated, therefore
  59          * the length must be even.
  60          */
  61         if (keylen % 2) {
  62                 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  63                 return -EINVAL;
  64         }
  65
  66         /* ensure that the AES and tweak key are not identical */
  67         if ((fips_enabled || crypto_skcipher_get_flags(tfm) &
  68                              CRYPTO_TFM_REQ_WEAK_KEY) &&
  69             !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
  70                 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_WEAK_KEY);
  71                 return -EINVAL;
  72         }
  73
  74         return 0;
  75 }
  76
  77 #endif  /* _CRYPTO_XTS_H */