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ext4 crypto: add ext4 encryption facilities

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On encrypt, we will re-assign the buffer_heads to point to a bounce
page rather than the control_page (which is the original page to write
that contains the plaintext). The block I/O occurs against the bounce
page.  On write completion, we re-assign the buffer_heads to the
original plaintext page.

On decrypt, we will attach a read completion callback to the bio
struct. This read completion will decrypt the read contents in-place
prior to setting the page up-to-date.

The current encryption mode, AES-256-XTS, lacks cryptographic
integrity. AES-256-GCM is in-plan, but we will need to devise a
mechanism for handling the integrity data.

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Michael Halcrow
2015-04-12 00:43:56 -04:00
committed by Theodore Ts'o
parent 9bd8212f98
commit b30ab0e034
6 changed files with 682 additions and 1 deletions
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8
fs/ext4/crypto_policy.c
View File

@@ -52,6 +52,13 @@ static int ext4_create_encryption_context_from_policy(
ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
EXT4_KEY_DESCRIPTOR_SIZE);
if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid contents encryption mode %d\n", __func__,
policy->contents_encryption_mode);
res = -EINVAL;
goto out;
}
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
@@ -60,6 +67,7 @@ static int ext4_create_encryption_context_from_policy(
res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), 0);
out:
if (!res)
ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
return res;