[PATCH v3] common/encrypt: Explicitly set the test file to uncompressed

[PATCH v3] common/encrypt: Explicitly set the test file to uncompressed

[Jan Prusakowski]

verify_ciphertext_for_encryption_policy() checks if encryption works
correctly by reading encrypted file's contents directly from a block device and
comparing it to a known good ciphertext.

This, however, won't work if the test file is also compressed. So this patch
adds a check if a test file is compressed and disables its compression in this
case.

Signed-off-by: Jan Prusakowski <jprusakowski@google.com>

---
Changes in v2:
The test file is now created empty first, followed by resetting the
FS_COMP_FL attribute, and then copying the test data.

Changes in v3:
Added explicit FS_NOCOMP_FL attribute to the test file.

---
 common/encrypt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/common/encrypt b/common/encrypt
index d4f6e3dc..f2687631 100644
--- a/common/encrypt
+++ b/common/encrypt
@@ -790,6 +790,13 @@ _do_verify_ciphertext_for_encryption_policy()
 	_set_encpolicy $dir $keyspec $set_encpolicy_args -f $policy_flags
 	for src in $tmp.testfile_*; do
 		dst=$dir/${src##*.}
+		# To make sure the test file is not compressed we create an empty one
+		# and disable compression first (F2FS won't allow resetting the
+		# compression flag if the file has data already in it).
+		touch $dst
+		if lsattr $dst | grep -qE ".+c.+ $dst" ; then
+			chattr -c +m $dst
+		fi
 		cp $src $dst
 		inode=$(stat -c %i $dst)
 		blocklist=$(_get_ciphertext_block_list $dst)
-- 
2.51.0.618.g983fd99d29-goog

Re: [PATCH v3] common/encrypt: Explicitly set the test file to uncompressed

[Eric Biggers]

On Mon, Oct 06, 2025 at 11:58:13AM +0200, Jan Prusakowski wrote:
> verify_ciphertext_for_encryption_policy() checks if encryption works
> correctly by reading encrypted file's contents directly from a block device and
> comparing it to a known good ciphertext.
> 
> This, however, won't work if the test file is also compressed. So this patch
> adds a check if a test file is compressed and disables its compression in this
> case.
> 
> Signed-off-by: Jan Prusakowski <jprusakowski@google.com>

Reviewed-by: Eric Biggers <ebiggers@kernel.org>

- Eric

Re: [PATCH v3] common/encrypt: Explicitly set the test file to uncompressed

[Chao Yu]

On 10/6/25 17:58, Jan Prusakowski wrote:
> verify_ciphertext_for_encryption_policy() checks if encryption works
> correctly by reading encrypted file's contents directly from a block device and
> comparing it to a known good ciphertext.
> 
> This, however, won't work if the test file is also compressed. So this patch
> adds a check if a test file is compressed and disables its compression in this
> case.
> 
> Signed-off-by: Jan Prusakowski <jprusakowski@google.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,