3.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
commit 3e1866410f11356a9fd869beb3e95983dc79c067 upstream.
Now that remount is properly enforcing the rule that you can't remove
nodev at least sandstorm.io is breaking when performing a remount.
It turns out that there is an easy intuitive solution implicitly
add nodev on remount when nodev was implicitly added on mount.
Tested-by: Cedric Bosdonnat <cbosdonnat@xxxxxxxx>
Tested-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2100,7 +2100,13 @@ static int do_remount(struct path *path,
}
if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) &&
!(mnt_flags & MNT_NODEV)) {
- return -EPERM;
+ /* Was the nodev implicitly added in mount? */
+ if ((mnt->mnt_ns->user_ns != &init_user_ns) &&
+ !(sb->s_type->fs_flags & FS_USERNS_DEV_MOUNT)) {
+ mnt_flags |= MNT_NODEV;
+ } else {
+ return -EPERM;
+ }
}
if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) &&
!(mnt_flags & MNT_NOSUID)) {
--
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