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fscrypt: add inline encryption support

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Add support for inline encryption to fs/crypto/.  With "inline
encryption", the block layer handles the decryption/encryption as part
of the bio, instead of the filesystem doing the crypto itself via
Linux's crypto API. This model is needed in order to take advantage of
the inline encryption hardware present on most modern mobile SoCs.

To use inline encryption, the filesystem needs to be mounted with
'-o inlinecrypt'. Blk-crypto will then be used instead of the traditional
filesystem-layer crypto whenever possible to encrypt the contents
of any encrypted files in that filesystem. Fscrypt still provides the key
and IV to use, and the actual ciphertext on-disk is still the same;
therefore it's testable using the existing fscrypt ciphertext verification
tests.

Note that since blk-crypto has a fallback to Linux's crypto API, and
also supports all the encryption modes currently supported by fscrypt,
this feature is usable and testable even without actual inline
encryption hardware.

Per-filesystem changes will be needed to set encryption contexts when
submitting bios and to implement the 'inlinecrypt' mount option.  This
patch just adds the common code.

Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200702015607.1215430-3-satyat@google.com
Co-developed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Satya Tangirala
2020-07-02 01:56:05 +00:00
committed by Eric Biggers
parent 457e7a135c
commit 5fee36095c
12 changed files with 674 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
fs/crypto/keysetup_v1.c
View File

@@ -146,7 +146,7 @@ struct fscrypt_direct_key {
struct hlist_node dk_node;
refcount_t dk_refcount;
const struct fscrypt_mode *dk_mode;
struct crypto_skcipher *dk_ctfm;
struct fscrypt_prepared_key dk_key;
u8 dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
u8 dk_raw[FSCRYPT_MAX_KEY_SIZE];
};
@@ -154,7 +154,7 @@ struct fscrypt_direct_key {
static void free_direct_key(struct fscrypt_direct_key *dk)
{
if (dk) {
crypto_free_skcipher(dk->dk_ctfm);
fscrypt_destroy_prepared_key(&dk->dk_key);
kzfree(dk);
}
}
@@ -199,6 +199,8 @@ find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
continue;
if (ci->ci_mode != dk->dk_mode)
continue;
if (!fscrypt_is_key_prepared(&dk->dk_key, ci))
continue;
if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize))
continue;
/* using existing tfm with same (descriptor, mode, raw_key) */
@@ -231,13 +233,9 @@ fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
return ERR_PTR(-ENOMEM);
refcount_set(&dk->dk_refcount, 1);
dk->dk_mode = ci->ci_mode;
dk->dk_ctfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key,
ci->ci_inode);
if (IS_ERR(dk->dk_ctfm)) {
err = PTR_ERR(dk->dk_ctfm);
dk->dk_ctfm = NULL;
err = fscrypt_prepare_key(&dk->dk_key, raw_key, ci);
if (err)
goto err_free_dk;
}
memcpy(dk->dk_descriptor, ci->ci_policy.v1.master_key_descriptor,
FSCRYPT_KEY_DESCRIPTOR_SIZE);
memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize);
@@ -259,7 +257,7 @@ static int setup_v1_file_key_direct(struct fscrypt_info *ci,
if (IS_ERR(dk))
return PTR_ERR(dk);
ci->ci_direct_key = dk;
ci->ci_ctfm = dk->dk_ctfm;
ci->ci_enc_key = dk->dk_key;
return 0;
}