From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Loosen the permission check on forced umount to allow users holding
CAP_SYS_ADMIN privileges in namespaces that are privileged with respect
to the userns that originally mounted the filesystem.
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/namespace.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 8f1000f9f3df..d401486fe95d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2026,6 +2026,7 @@ static void warn_mandlock(void)
static int can_umount(const struct path *path, int flags)
{
struct mount *mnt = real_mount(path->mnt);
+ struct super_block *sb = path->dentry->d_sb;
if (!may_mount())
return -EPERM;
@@ -2035,7 +2036,7 @@ static int can_umount(const struct path *path, int flags)
return -EINVAL;
if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
return -EINVAL;
- if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
+ if (flags & MNT_FORCE && !ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
--
2.48.1
