ext4: require encryption feature for EXT4_IOC_SET_ENCRYPTION_POLICY

...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@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index c64239b24c2fc8441c6a6c991fd72ad7f86df95b..22abf7aeb25d009cc7d71e06a7d6ec53d9bce9c4 100644 (file)
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -769,6 +769,9 @@ resizefs_out:
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
                struct fscrypt_policy policy;
 
+               if (!ext4_has_feature_encrypt(sb))
+                       return -EOPNOTSUPP;
+
                if (copy_from_user(&policy,
                                   (struct fscrypt_policy __user *)arg,
                                   sizeof(policy)))