[PATCH 4.4 15/20] ext4: require encryption feature for EXT4_IOC_SET_ENCRYPTION_POLICY

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard@xxxxxx>

commit 9a200d075e5d05be1fcad4547a0f8aee4e2f9a04 upstream.

...otherwise an user can enable encryption for certain files even
when the filesystem is unable to support it.
Such a case would be a filesystem created by mkfs.ext4's default
settings, 1KiB block size. Ext4 supports encyption only when block size
is equal to PAGE_SIZE.
But this constraint is only checked when the encryption feature flag
is set.

Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ext4/ioctl.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -622,6 +622,9 @@ resizefs_out:
 		struct ext4_encryption_policy policy;
 		int err = 0;
 
+		if (!ext4_has_feature_encrypt(sb))
+			return -EOPNOTSUPP;
+
 		if (copy_from_user(&policy,
 				   (struct ext4_encryption_policy __user *)arg,
 				   sizeof(policy))) {