generic: add test for custom crypto data unit size

Add a test that verifies the on-disk format of encrypted files that use
a crypto data unit size that differs from the filesystem block size.
This tests the functionality that was introduced in Linux 6.7 by kernel
commit 5b1188847180 ("fscrypt: support crypto data unit size less than
filesystem block size").

This depends on the xfsprogs patch
"xfs_io/encrypt: support specifying crypto data unit size"
(https://lore.kernel.org/r/20231013062639.141468-1-ebiggers@kernel.org)
which adds the '-s' option to the set_encpolicy command of xfs_io.

As usual, the test skips itself when any prerequisite isn't met.

[zlang: add _wants_kernel_commit]

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>

diff --git a/tests/generic/739 b/tests/generic/739
new file mode 100755 (executable)
index 0000000..0941dd3
--- /dev/null
+++ b/tests/generic/739
@@ -0,0 +1,31 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2023 Google LLC
+#
+# FS QA Test No. 739
+#
+# Verify the on-disk format of encrypted files that use a crypto data unit size
+# that differs from the filesystem block size.  This tests the functionality
+# that was introduced in Linux 6.7 by kernel commit 5b1188847180
+# ("fscrypt: support crypto data unit size less than filesystem block size").
+#
+. ./common/preamble
+_begin_fstest auto quick encrypt
+
+. ./common/filter
+. ./common/encrypt
+
+_supported_fs generic
+_wants_kernel_commit 5b1188847180 \
+       "fscrypt: support crypto data unit size less than filesystem block size"
+
+# For now, just test 512-byte and 1024-byte data units.  Filesystems accept
+# power-of-2 sizes between 512 and the filesystem block size, inclusively.
+# Testing 512 and 1024 ensures this test will run for any FS block size >= 1024
+# (provided that the filesystem supports sub-block data units at all).
+_verify_ciphertext_for_encryption_policy AES-256-XTS AES-256-CTS-CBC v2 log2_dusize=9
+_verify_ciphertext_for_encryption_policy AES-256-XTS AES-256-CTS-CBC v2 log2_dusize=10
+
+# success, all done
+status=0
+exit

diff --git a/tests/generic/739.out b/tests/generic/739.out
new file mode 100644 (file)
index 0000000..0066605
--- /dev/null
+++ b/tests/generic/739.out
@@ -0,0 +1,11 @@
+QA output created by 739
+
+Verifying ciphertext with parameters:
+       contents_encryption_mode: AES-256-XTS
+       filenames_encryption_mode: AES-256-CTS-CBC
+       options: v2 log2_dusize=9
+
+Verifying ciphertext with parameters:
+       contents_encryption_mode: AES-256-XTS
+       filenames_encryption_mode: AES-256-CTS-CBC
+       options: v2 log2_dusize=10