commit 380cf5ba6b0a ("fs: Treat foreign mounts as nosuid"), in addition to
the intended effect, also prevented suid execution of memfd files.
(And I think that's a good change.)Signed-off-by: Jann Horn <[email protected]> --- fs/namespace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index a7f91265ea67..e68488426e42 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3400,6 +3400,9 @@ bool mnt_may_suid(struct vfsmount *mnt) * prevents namespaces from trusting potentially unsafe * suid/sgid bits, file caps, or security labels that originate * in other namespaces. + * + * check_mnt() rejects MNT_NS_INTERNAL mounts; this means that suid + * execution is blocked for files on internal mounts, e.g. memfds. */ return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && current_in_userns(mnt->mnt_sb->s_user_ns); -- 2.20.0.rc0.387.gc7a69e6b6c-goog
