Re: [PATCH] netfilter: xt_osf: Add missing permission checks

From: Pablo Neira Ayuso
Date: Wed Dec 06 2017 - 03:02:11 EST


On Tue, Dec 05, 2017 at 03:42:41PM -0800, Kevin Cernekee wrote:
> The capability check in nfnetlink_rcv() verifies that the caller
> has CAP_NET_ADMIN in the namespace that "owns" the netlink socket.
> However, xt_osf_fingers is shared by all net namespaces on the
> system. An unprivileged user can create user and net namespaces
> in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable()
> check:
>
> vpnns -- nfnl_osf -f /tmp/pf.os
>
> vpnns -- nfnl_osf -f /tmp/pf.os -d
>
> These non-root operations successfully modify the systemwide OS
> fingerprint list. Add new capable() checks so that they can't.

Applied, thanks Kevin.