XTS support
This commit is contained in:
Vladimir 'phcoder' Serbinenko
parent
2cb55e6f73
commit
fe32915a5e
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@ -73,7 +73,8 @@ typedef enum
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{
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GRUB_LUKS_MODE_ECB,
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GRUB_LUKS_MODE_CBC_PLAIN,
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GRUB_LUKS_MODE_CBC_ESSIV
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GRUB_LUKS_MODE_CBC_ESSIV,
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GRUB_LUKS_MODE_XTS
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} luks_mode_t;
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struct grub_luks
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@ -83,7 +84,7 @@ struct grub_luks
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grub_disk_t source_disk;
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int ref;
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grub_crypto_cipher_handle_t cipher;
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grub_crypto_cipher_handle_t essiv_cipher;
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grub_crypto_cipher_handle_t secondary_cipher;
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const gcry_md_spec_t *essiv_hash, *hash;
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luks_mode_t mode;
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unsigned long id, source_id;
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@ -111,6 +112,33 @@ static const struct grub_arg_option options[] =
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{0, 0, 0, 0, 0, 0}
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};
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static inline void
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make_iv (grub_uint32_t *iv, grub_size_t sz, grub_disk_addr_t sector)
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{
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grub_memset (iv, 0, sz * sizeof (iv[0]));
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iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
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}
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/* Our irreducible polynom is x^128+x^7+x^2+x+1. Lowest byte of it is: */
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#define POLYNOM 0x87
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static void
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gf_mul_x (grub_uint8_t *g)
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{
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int over = 0, over2 = 0;
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int j;
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for (j = 0; j < 16; j++)
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{
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over2 = !!(g[j] & 0x80);
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g[j] <<= 1;
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g[j] |= over;
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over = over2;
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}
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if (over)
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g[0] ^= POLYNOM;
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}
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static gcry_err_code_t
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luks_decrypt (const struct grub_luks *dev,
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grub_uint8_t * data, grub_size_t len, grub_size_t sector)
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@ -126,11 +154,11 @@ luks_decrypt (const struct grub_luks *dev,
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case GRUB_LUKS_MODE_CBC_PLAIN:
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for (i = 0; i < len; i += GRUB_DISK_SECTOR_SIZE)
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{
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grub_uint32_t iv[(dev->cipher->cipher->blocksize
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grub_size_t sz = ((dev->cipher->cipher->blocksize
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+ sizeof (grub_uint32_t) - 1)
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/ sizeof (grub_uint32_t)];
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grub_memset (iv, 0, dev->cipher->cipher->blocksize);
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iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
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/ sizeof (grub_uint32_t));
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grub_uint32_t iv[sz];
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make_iv (iv, sz, sector);
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err = grub_crypto_cbc_decrypt (dev->cipher, data + i, data + i,
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GRUB_DISK_SECTOR_SIZE, iv);
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if (err)
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@ -142,14 +170,14 @@ luks_decrypt (const struct grub_luks *dev,
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case GRUB_LUKS_MODE_CBC_ESSIV:
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for (i = 0; i < len; i += GRUB_DISK_SECTOR_SIZE)
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{
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grub_uint32_t iv[(dev->cipher->cipher->blocksize
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grub_size_t sz = ((dev->cipher->cipher->blocksize
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+ sizeof (grub_uint32_t) - 1)
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/ sizeof (grub_uint32_t)];
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grub_memset (iv, 0, dev->cipher->cipher->blocksize);
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iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
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err =
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grub_crypto_ecb_encrypt (dev->essiv_cipher, iv, iv,
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dev->cipher->cipher->blocksize);
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/ sizeof (grub_uint32_t));
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grub_uint32_t iv[sz];
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make_iv (iv, sz, sector);
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err = grub_crypto_ecb_encrypt (dev->secondary_cipher, iv, iv,
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dev->cipher->cipher->blocksize);
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if (err)
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return err;
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err = grub_crypto_cbc_decrypt (dev->cipher, data + i, data + i,
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@ -160,6 +188,39 @@ luks_decrypt (const struct grub_luks *dev,
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}
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return GPG_ERR_NO_ERROR;
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case GRUB_LUKS_MODE_XTS:
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for (i = 0; i < len; i += GRUB_DISK_SECTOR_SIZE)
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{
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grub_size_t sz = ((dev->cipher->cipher->blocksize
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+ sizeof (grub_uint32_t) - 1)
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/ sizeof (grub_uint32_t));
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grub_uint32_t iv[sz];
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int j;
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make_iv (iv, sz, sector);
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err = grub_crypto_ecb_encrypt (dev->secondary_cipher, iv, iv,
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dev->cipher->cipher->blocksize);
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if (err)
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return err;
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for (j = 0; j < GRUB_DISK_SECTOR_SIZE;
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j += dev->cipher->cipher->blocksize)
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{
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grub_crypto_xor (data + i + j, data + i + j, iv,
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dev->cipher->cipher->blocksize);
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err = grub_crypto_ecb_decrypt (dev->cipher, data + i + j,
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data + i + j,
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dev->cipher->cipher->blocksize);
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if (err)
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return err;
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grub_crypto_xor (data + i + j, data + i + j, iv,
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dev->cipher->cipher->blocksize);
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gf_mul_x ((grub_uint8_t *) iv);
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}
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sector++;
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}
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return GPG_ERR_NO_ERROR;
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default:
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return GPG_ERR_NOT_IMPLEMENTED;
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}
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@ -178,7 +239,7 @@ configure_ciphers (const struct grub_luks_phdr *header)
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char ciphername[sizeof (header->cipherName) + 1];
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char ciphermode[sizeof (header->cipherMode) + 1];
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char hashspec[sizeof (header->hashSpec) + 1];
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grub_crypto_cipher_handle_t cipher = NULL, essiv_cipher = NULL;
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grub_crypto_cipher_handle_t cipher = NULL, secondary_cipher = NULL;
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const gcry_md_spec_t *hash = NULL, *essiv_hash = NULL;
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const struct gcry_cipher_spec *ciph;
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luks_mode_t mode;
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@ -232,12 +293,13 @@ configure_ciphers (const struct grub_luks_phdr *header)
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}
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/* Configure the cipher mode. */
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if (grub_strncmp (ciphermode, "ecb", 3) == 0)
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if (grub_strcmp (ciphermode, "ecb") == 0)
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mode = GRUB_LUKS_MODE_ECB;
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else if (grub_strncmp (ciphermode, "cbc-plain", 9) == 0
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|| grub_strncmp (ciphermode, "plain", 5) == 0)
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else if (grub_strcmp (ciphermode, "cbc-plain") == 0
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|| grub_strcmp (ciphermode, "plain") == 0)
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mode = GRUB_LUKS_MODE_CBC_PLAIN;
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else if (grub_strncmp (ciphermode, "cbc-essiv", 9) == 0)
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else if (grub_memcmp (ciphermode, "cbc-essiv:", sizeof ("cbc-essiv:") - 1)
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== 0)
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{
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mode = GRUB_LUKS_MODE_CBC_ESSIV;
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char *hash_str = ciphermode + 10;
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@ -251,13 +313,35 @@ configure_ciphers (const struct grub_luks_phdr *header)
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"Couldn't load %s hash", hash_str);
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return NULL;
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}
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essiv_cipher = grub_crypto_cipher_open (ciph);
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if (!cipher)
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secondary_cipher = grub_crypto_cipher_open (ciph);
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if (!secondary_cipher)
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{
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grub_crypto_cipher_close (cipher);
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return NULL;
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}
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}
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else if (grub_strcmp (ciphermode, "xts-plain") == 0)
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{
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mode = GRUB_LUKS_MODE_XTS;
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secondary_cipher = grub_crypto_cipher_open (ciph);
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if (!secondary_cipher)
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{
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grub_crypto_cipher_close (cipher);
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return NULL;
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}
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if (cipher->cipher->blocksize != 16)
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{
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grub_error (GRUB_ERR_BAD_ARGUMENT, "Unsupported XTS block size: %d",
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cipher->cipher->blocksize);
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return NULL;
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}
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if (secondary_cipher->cipher->blocksize != 16)
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{
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grub_error (GRUB_ERR_BAD_ARGUMENT, "Unsupported XTS block size: %d",
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secondary_cipher->cipher->blocksize);
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return NULL;
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}
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}
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else
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{
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grub_crypto_cipher_close (cipher);
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@ -271,7 +355,7 @@ configure_ciphers (const struct grub_luks_phdr *header)
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if (!hash)
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{
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grub_crypto_cipher_close (cipher);
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grub_crypto_cipher_close (essiv_cipher);
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grub_crypto_cipher_close (secondary_cipher);
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grub_error (GRUB_ERR_FILE_NOT_FOUND, "Couldn't load %s hash",
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hashspec);
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return NULL;
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@ -284,7 +368,7 @@ configure_ciphers (const struct grub_luks_phdr *header)
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newdev->offset = grub_be_to_cpu32 (header->payloadOffset);
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newdev->source_disk = NULL;
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newdev->mode = mode;
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newdev->essiv_cipher = essiv_cipher;
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newdev->secondary_cipher = secondary_cipher;
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newdev->essiv_hash = essiv_hash;
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newdev->hash = hash;
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newdev->id = n++;
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@ -309,11 +393,11 @@ luks_recover_key (grub_luks_t dev, const struct grub_luks_phdr *header,
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grub_err_t err;
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if (dev->mode == GRUB_LUKS_MODE_CBC_ESSIV)
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essiv_keysize = dev->essiv_hash->mdlen;
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hashed_key = grub_malloc (dev->essiv_hash->mdlen);
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if (!hashed_key)
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{
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return grub_errno;
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essiv_keysize = dev->essiv_hash->mdlen;
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hashed_key = grub_malloc (dev->essiv_hash->mdlen);
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if (!hashed_key)
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return grub_errno;
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}
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grub_printf ("Attempting to decrypt master key...\n");
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@ -365,7 +449,9 @@ luks_recover_key (grub_luks_t dev, const struct grub_luks_phdr *header,
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grub_dprintf ("luks", "PBKDF2 done\n");
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/* Set the PBKDF2 output as the cipher key. */
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gcry_err = grub_crypto_cipher_set_key (dev->cipher, digest, keysize);
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gcry_err = grub_crypto_cipher_set_key (dev->cipher, digest,
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(dev->mode == GRUB_LUKS_MODE_XTS)
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? (keysize / 2) : keysize);
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if (gcry_err)
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{
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grub_free (hashed_key);
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@ -377,8 +463,28 @@ luks_recover_key (grub_luks_t dev, const struct grub_luks_phdr *header,
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if (dev->mode == GRUB_LUKS_MODE_CBC_ESSIV)
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{
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grub_crypto_hash (dev->essiv_hash, hashed_key, digest, keysize);
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grub_crypto_cipher_set_key (dev->essiv_cipher, hashed_key,
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essiv_keysize);
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gcry_err = grub_crypto_cipher_set_key (dev->secondary_cipher,
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hashed_key,
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essiv_keysize);
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if (gcry_err)
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{
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grub_free (hashed_key);
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grub_free (split_key);
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return grub_crypto_gcry_error (gcry_err);
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}
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}
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if (dev->mode == GRUB_LUKS_MODE_XTS)
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{
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gcry_err = grub_crypto_cipher_set_key (dev->secondary_cipher,
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digest + (keysize / 2),
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keysize / 2);
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if (gcry_err)
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{
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grub_free (hashed_key);
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grub_free (split_key);
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return grub_crypto_gcry_error (gcry_err);
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}
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}
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length =
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@ -437,13 +543,17 @@ luks_recover_key (grub_luks_t dev, const struct grub_luks_phdr *header,
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in the header to see if it's correct. */
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if (grub_memcmp (candidate_digest, header->mkDigest,
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sizeof (header->mkDigest)) != 0)
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continue;
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{
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grub_dprintf ("luks", "bad digest\n");
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continue;
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}
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grub_printf ("Slot %d opened\n", i);
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/* Set the master key. */
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gcry_err = grub_crypto_cipher_set_key (dev->cipher,
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candidate_key, keysize);
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gcry_err = grub_crypto_cipher_set_key (dev->cipher, candidate_key,
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(dev->mode == GRUB_LUKS_MODE_XTS)
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? (keysize / 2) : keysize);
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if (gcry_err)
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{
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grub_free (hashed_key);
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@ -457,7 +567,7 @@ luks_recover_key (grub_luks_t dev, const struct grub_luks_phdr *header,
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grub_crypto_hash (dev->essiv_hash, hashed_key,
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candidate_key, keysize);
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gcry_err =
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grub_crypto_cipher_set_key (dev->essiv_cipher, hashed_key,
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grub_crypto_cipher_set_key (dev->secondary_cipher, hashed_key,
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essiv_keysize);
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if (gcry_err)
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{
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@ -467,6 +577,18 @@ luks_recover_key (grub_luks_t dev, const struct grub_luks_phdr *header,
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}
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}
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if (dev->mode == GRUB_LUKS_MODE_XTS)
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{
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gcry_err = grub_crypto_cipher_set_key (dev->secondary_cipher,
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candidate_key + (keysize / 2),
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keysize / 2);
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if (gcry_err)
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{
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grub_free (hashed_key);
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grub_free (split_key);
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return grub_crypto_gcry_error (gcry_err);
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}
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}
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grub_free (split_key);
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grub_free (hashed_key);
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@ -481,7 +603,7 @@ static void
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luks_close (grub_luks_t luks)
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{
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grub_crypto_cipher_close (luks->cipher);
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grub_crypto_cipher_close (luks->essiv_cipher);
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grub_crypto_cipher_close (luks->secondary_cipher);
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grub_free (luks);
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}
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@ -751,7 +873,7 @@ luks_cleanup (void)
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{
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grub_free (dev->source);
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grub_free (dev->cipher);
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grub_free (dev->essiv_cipher);
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grub_free (dev->secondary_cipher);
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tmp = dev->next;
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grub_free (dev);
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dev = tmp;
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