2016-10-10 19:06:37

by Eric Biggers

Subject: [PATCH] ext4: do not advertise encryption support when disabled

The sysfs file /sys/fs/ext4/features/encryption was present on kernels
compiled with CONFIG_EXT4_FS_ENCRYPTION=n. This was misleading because
such kernels do not actually support ext4 encryption. Therefore, only
provide this file on kernels compiled with CONFIG_EXT4_FS_ENCRYPTION=y.

Note: since the ext4 feature files are all hardcoded to have a contents
of "supported", it really is the presence or absence of the file that is
significant, not the contents (and this change reflects that).

Signed-off-by: Eric Biggers <[email protected]>
---
fs/ext4/sysfs.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 73bcfd4..42145be 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -223,14 +223,18 @@ static struct attribute *ext4_attrs[] = {
EXT4_ATTR_FEATURE(lazy_itable_init);
EXT4_ATTR_FEATURE(batched_discard);
EXT4_ATTR_FEATURE(meta_bg_resize);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
EXT4_ATTR_FEATURE(encryption);
+#endif
EXT4_ATTR_FEATURE(metadata_csum_seed);

static struct attribute *ext4_feat_attrs[] = {
ATTR_LIST(lazy_itable_init),
ATTR_LIST(batched_discard),
ATTR_LIST(meta_bg_resize),
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
ATTR_LIST(encryption),
+#endif
ATTR_LIST(metadata_csum_seed),
NULL,
};
--
2.8.0.rc3.226.g39d4020

2016-10-13 03:29:09

by Theodore Ts'o

Subject: Re: [PATCH] ext4: do not advertise encryption support when disabled

On Mon, Oct 10, 2016 at 12:05:31PM -0700, Eric Biggers wrote:
> The sysfs file /sys/fs/ext4/features/encryption was present on kernels
> compiled with CONFIG_EXT4_FS_ENCRYPTION=n. This was misleading because
> such kernels do not actually support ext4 encryption. Therefore, only
> provide this file on kernels compiled with CONFIG_EXT4_FS_ENCRYPTION=y.
>
> Note: since the ext4 feature files are all hardcoded to have a contents
> of "supported", it really is the presence or absence of the file that is
> significant, not the contents (and this change reflects that).
>
> Signed-off-by: Eric Biggers <[email protected]>

Thanks, applied.

- Ted