vfs: Allow unprivileged manipulation of the mount namespace.
- Add a filesystem flag to mark filesystems that are safe to mount as
an unprivileged user.
- Add a filesystem flag to mark filesystems that don't need MNT_NODEV
when mounted by an unprivileged user.
- Relax the permission checks to allow unprivileged users that have
CAP_SYS_ADMIN permissions in the user namespace referred to by the
current mount namespace to be allowed to mount, unmount, and move
filesystems.
Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b33cfc9..5037aa6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1812,6 +1812,8 @@
#define FS_REQUIRES_DEV 1
#define FS_BINARY_MOUNTDATA 2
#define FS_HAS_SUBTYPE 4
+#define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */
+#define FS_USERNS_DEV_MOUNT 16 /* A userns mount does not imply MNT_NODEV */
#define FS_REVAL_DOT 16384 /* Check the paths ".", ".." for staleness */
#define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */
struct dentry *(*mount) (struct file_system_type *, int,
