Instead of instantiating a separate cipher to perform the encryption needed to produce the IV, reuse the skcipher used for the block data and invoke it one additional time for each block to encrypt a zero vector and use the output as the IV. For CBC mode, this is equivalent to using the bare block cipher, but without the risk of ending up with a non-time invariant implementation of AES when the skcipher itself is time variant (e.g., arm64 without Crypto Extensions has a NEON based time invariant implementation of cbc(aes) but no time invariant implementation of the core cipher other than aes-ti, which is not enabled by default) This approach is a compromise between dm-crypt API flexibility and reducing dependence on parts of the crypto API that should not usually be exposed to other subsystems, such as the bare cipher API. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> --- drivers/md/dm-crypt.c | 70 ++++++++++++++----------------------------- 1 file changed, 22 insertions(+), 48 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index d5216bcc4649..48cd76c88d77 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -120,10 +120,6 @@ 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. @@ -163,7 +159,6 @@ 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; @@ -847,65 +842,47 @@ 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 (test_bit(CRYPT_MODE_INTEGRITY_AEAD, &cc->cipher_flags)) { + ti->error = "AEAD transforms not supported for EBOIV"; + return -EINVAL; } - if (crypto_cipher_blocksize(tfm) != cc->iv_size) { + if (crypto_skcipher_blocksize(any_tfm(cc)) != 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) +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; + u8 buf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(__le64)); + struct skcipher_request *req; + struct scatterlist src, dst; + struct crypto_wait wait; 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); -} + req = skcipher_request_alloc(any_tfm(cc), GFP_KERNEL | GFP_NOFS); + if (!req) + return -ENOMEM; -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(buf, 0, cc->iv_size); + *(__le64 *)buf = cpu_to_le64(dmreq->iv_sector * cc->sector_size); - 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); + sg_init_one(&src, page_address(ZERO_PAGE(0)), cc->iv_size); + sg_init_one(&dst, iv, cc->iv_size); + skcipher_request_set_crypt(req, &src, &dst, cc->iv_size, buf); + skcipher_request_set_callback(req, 0, crypto_req_done, &wait); + err = crypto_wait_req(crypto_skcipher_encrypt(req), &wait); + skcipher_request_free(req); - return 0; + return err; } static const struct crypt_iv_operations crypt_iv_plain_ops = { @@ -962,9 +939,6 @@ static struct crypt_iv_operations crypt_iv_random_ops = { 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 }; -- 2.17.1