linux-kernel - Re: [PATCH] netfilter: xt_osf: Add missing permission checks

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Message-ID: <20171206080134.GA2844@salvia>
Date:   Wed, 6 Dec 2017 09:01:34 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Kevin Cernekee <cernekee@...omium.org>
Cc:     netfilter-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: xt_osf: Add missing permission checks

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.