Hello,
This patchset makes ext4 support encryption on filesystems where the
filesystem block size is not equal to PAGE_SIZE. This allows e.g.
PowerPC systems to use ext4 encryption.
Most of the work for this was already done in prior kernel releases; now
the only part missing is decryption support in block_read_full_page().
Chandan Rajendra has proposed a patchset "Consolidate FS read I/O
callbacks code" [1] to address this and do various other things like
make ext4 use mpage_readpages() again, and make ext4 and f2fs share more
code. But it doesn't seem to be going anywhere.
Therefore, I propose we simply add decryption support to
block_read_full_page() for now. This is a fairly small change, and it
gets ext4 encryption with subpage-sized blocks working.
Note: to keep things simple I'm just allocating the work object from the
bi_end_io function with GFP_ATOMIC. But if people think it's necessary,
it could be changed to use preallocation like the page-based read path.
Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the new
"encrypt_1k" config I created. All tests pass except for those that
already fail or are excluded with the encrypt or 1k configs, and 2 tests
that try to create 1023-byte symlinks which fails since encrypted
symlinks are limited to blocksize-3 bytes. Also ran the dedicated
encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
including the on-disk ciphertext verification tests.
[1] https://lkml.kernel.org/linux-fsdevel/[email protected]/T/#u
Chandan Rajendra (1):
ext4: Enable encryption for subpage-sized blocks
Eric Biggers (1):
fs/buffer.c: support fscrypt in block_read_full_page()
Documentation/filesystems/fscrypt.rst | 4 +--
fs/buffer.c | 47 ++++++++++++++++++++++++---
fs/ext4/super.c | 7 ----
3 files changed, 44 insertions(+), 14 deletions(-)
--
2.23.0
From: Chandan Rajendra <[email protected]>
Now that we have the code to support encryption for subpage-sized
blocks, this commit removes the conditional check in filesystem mount
code.
The commit also changes the support statement in
Documentation/filesystems/fscrypt.rst to reflect the fact that
encryption on filesystems with blocksize less than page size now works.
[EB: Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the
new "encrypt_1k" config I created. All tests pass except for those that
already fail or are excluded with the encrypt or 1k configs, and 2 tests
that try to create 1023-byte symlinks which fails since encrypted
symlinks are limited to blocksize-3 bytes. Also ran the dedicated
encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
including the on-disk ciphertext verification tests.]
Signed-off-by: Chandan Rajendra <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>
---
Documentation/filesystems/fscrypt.rst | 4 ++--
fs/ext4/super.c | 7 -------
2 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index 8a0700af9596..b0d015a8cdc3 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -331,8 +331,8 @@ Contents encryption
-------------------
For file contents, each filesystem block is encrypted independently.
-Currently, only the case where the filesystem block size is equal to
-the system's page size (usually 4096 bytes) is supported.
+Starting from Linux kernel 5.5, encryption of filesystems with block
+size less than system's page size is supported.
Each block's IV is set to the logical block number within the file as
a little endian number, except that:
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index dd654e53ba3d..369f852bef20 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4439,13 +4439,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
}
}
- if ((DUMMY_ENCRYPTION_ENABLED(sbi) || ext4_has_feature_encrypt(sb)) &&
- (blocksize != PAGE_SIZE)) {
- ext4_msg(sb, KERN_ERR,
- "Unsupported blocksize for fs encryption");
- goto failed_mount_wq;
- }
-
if (ext4_has_feature_verity(sb) && blocksize != PAGE_SIZE) {
ext4_msg(sb, KERN_ERR, "Unsupported blocksize for fs-verity");
goto failed_mount_wq;
--
2.23.0
On Thursday, October 17, 2019 3:41 AM Eric Biggers wrote:
> Hello,
>
> This patchset makes ext4 support encryption on filesystems where the
> filesystem block size is not equal to PAGE_SIZE. This allows e.g.
> PowerPC systems to use ext4 encryption.
>
> Most of the work for this was already done in prior kernel releases; now
> the only part missing is decryption support in block_read_full_page().
> Chandan Rajendra has proposed a patchset "Consolidate FS read I/O
> callbacks code" [1] to address this and do various other things like
> make ext4 use mpage_readpages() again, and make ext4 and f2fs share more
> code. But it doesn't seem to be going anywhere.
>
> Therefore, I propose we simply add decryption support to
> block_read_full_page() for now. This is a fairly small change, and it
> gets ext4 encryption with subpage-sized blocks working.
>
> Note: to keep things simple I'm just allocating the work object from the
> bi_end_io function with GFP_ATOMIC. But if people think it's necessary,
> it could be changed to use preallocation like the page-based read path.
>
> Tested with 'gce-xfstests -c ext4/encrypt_1k -g auto', using the new
> "encrypt_1k" config I created. All tests pass except for those that
> already fail or are excluded with the encrypt or 1k configs, and 2 tests
> that try to create 1023-byte symlinks which fails since encrypted
> symlinks are limited to blocksize-3 bytes. Also ran the dedicated
> encryption tests using 'kvm-xfstests -c ext4/1k -g encrypt'; all pass,
> including the on-disk ciphertext verification tests.
>
> [1] https://lkml.kernel.org/linux-fsdevel/[email protected]/T/#u
>
Hi Eric,
Thanks a lot for doing this.
The changes seem to be good. I have started test runs on my ppc64le guest and
I will reply with the test results once they complete.
--
chandan