Unverified Commit e1ff7aa3 authored by Trond Myklebust's avatar Trond Myklebust Committed by Christian Brauner
Browse files

umount: Allow superblock owners to force umount 



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: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Link: https://lore.kernel.org/r/12f212d4ef983714d065a6bb372fbb378753bf4c.1742315194.git.trond.myklebust@hammerspace.com


Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent e1c24b52

fs/namespace.c

+2 −1
Original line number Diff line number Diff line
@@ -2105,6 +2105,7 @@ 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;
@@ -2114,7 +2115,7 @@ 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;

}