This IV is used in some BitLocker devices with CBC encryption mode.
IV is encrypted little-endian byte-offset (with the same key and cipher
as the volume).
Signed-off-by: Milan Broz <gmazyland@xxxxxxxxx>
---
drivers/md/dm-crypt.c | 82 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 81 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index c567e13a0e5f..0443a925840b 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -120,6 +120,10 @@ struct iv_tcw_private {
u8 *whitening;
};
+struct iv_eboiv_private {
+ struct crypto_cipher *tfm;
+};
+
/*
* Crypt: maps a linear range of a block device
* and encrypts / decrypts at the same time.
@@ -159,6 +163,7 @@ struct crypt_config {
struct iv_benbi_private benbi;
struct iv_lmk_private lmk;
struct iv_tcw_private tcw;
+ struct iv_eboiv_private eboiv;
} iv_gen_private;
u64 iv_offset;
unsigned int iv_size;
@@ -290,6 +295,10 @@ static struct crypto_aead *any_tfm_aead(struct crypt_config *cc)
* is calculated from initial key, sector number and mixed using CRC32.
* Note that this encryption scheme is vulnerable to watermarking attacks
* and should be used for old compatible containers access only.
+ *
+ * eboiv: Encrypted byte-offset IV (used in Bitlocker in CBC mode)
+ * The IV is encrypted little-endian byte-offset (with the same key
+ * and cipher as the volume).
*/
static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv,
@@ -838,6 +847,67 @@ static int crypt_iv_random_gen(struct crypt_config *cc, u8 *iv,
return 0;
}
+static void crypt_iv_eboiv_dtr(struct crypt_config *cc)
+{
+ struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;
+
+ crypto_free_cipher(eboiv->tfm);
+ eboiv->tfm = NULL;
+}
+
+static int crypt_iv_eboiv_ctr(struct crypt_config *cc, struct dm_target *ti,
+ const char *opts)
+{
+ struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;
+ struct crypto_cipher *tfm;
+
+ tfm = crypto_alloc_cipher(cc->cipher, 0, 0);
+ if (IS_ERR(tfm)) {
+ ti->error = "Error allocating crypto tfm for EBOIV";
+ return PTR_ERR(tfm);
+ }
+
+ if (crypto_cipher_blocksize(tfm) != cc->iv_size) {
+ ti->error = "Block size of EBOIV cipher does "
+ "not match IV size of block cipher";
+ crypto_free_cipher(tfm);
+ return -EINVAL;
+ }
+
+ eboiv->tfm = tfm;
+ return 0;
+}
+
+static int crypt_iv_eboiv_init(struct crypt_config *cc)
+{
+ struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;
+ int err;
+
+ err = crypto_cipher_setkey(eboiv->tfm, cc->key, cc->key_size);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static int crypt_iv_eboiv_wipe(struct crypt_config *cc)
+{
+ /* Called after cc->key is set to random key in crypt_wipe() */
+ return crypt_iv_eboiv_init(cc);
+}
+
+static int crypt_iv_eboiv_gen(struct crypt_config *cc, u8 *iv,
+ struct dm_crypt_request *dmreq)
+{
+ struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;
+
+ memset(iv, 0, cc->iv_size);
+ *(__le64 *)iv = cpu_to_le64(dmreq->iv_sector * cc->sector_size);
+ crypto_cipher_encrypt_one(eboiv->tfm, iv, iv);
+
+ return 0;
+}
+
static const struct crypt_iv_operations crypt_iv_plain_ops = {
.generator = crypt_iv_plain_gen
};
@@ -890,6 +960,14 @@ static struct crypt_iv_operations crypt_iv_random_ops = {
.generator = crypt_iv_random_gen
};
+static struct crypt_iv_operations crypt_iv_eboiv_ops = {
+ .ctr = crypt_iv_eboiv_ctr,
+ .dtr = crypt_iv_eboiv_dtr,
+ .init = crypt_iv_eboiv_init,
+ .wipe = crypt_iv_eboiv_wipe,
+ .generator = crypt_iv_eboiv_gen
+};
+
/*
* Integrity extensions
*/
@@ -2293,6 +2371,8 @@ static int crypt_ctr_ivmode(struct dm_target *ti, const char *ivmode)
cc->iv_gen_ops = &crypt_iv_benbi_ops;
else if (strcmp(ivmode, "null") == 0)
cc->iv_gen_ops = &crypt_iv_null_ops;
+ else if (strcmp(ivmode, "eboiv") == 0)
+ cc->iv_gen_ops = &crypt_iv_eboiv_ops;
else if (strcmp(ivmode, "lmk") == 0) {
cc->iv_gen_ops = &crypt_iv_lmk_ops;
/*
@@ -3093,7 +3173,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
static struct target_type crypt_target = {
.name = "crypt",
- .version = {1, 18, 1},
+ .version = {1, 19, 0},
.module = THIS_MODULE,
.ctr = crypt_ctr,
.dtr = crypt_dtr,
--
2.20.1
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
