netdev - Re: [PATCH nf-next v3 0/3] Netfilter egress hook

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <454130d7-7256-838d-515e-c7340892278c@iogearbox.net>
Date:   Fri, 28 Aug 2020 09:14:00 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Lukas Wunner <lukas@...ner.de>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>
Cc:     netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Thomas Graf <tgraf@...g.ch>, Laura Garcia <nevola@...il.com>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH nf-next v3 0/3] Netfilter egress hook

Hi Lukas,

On 8/27/20 10:55 AM, Lukas Wunner wrote:
> Introduce a netfilter egress hook to allow filtering outbound AF_PACKETs
> such as DHCP and to prepare for in-kernel NAT64/NAT46.

Thinking more about this, how will this allow to sufficiently filter AF_PACKET?
It won't. Any AF_PACKET application can freely set PACKET_QDISC_BYPASS without
additional privileges and then dev_queue_xmit() is being bypassed in the host ns.
This is therefore ineffective and not sufficient. (From container side these can
be caught w/ host veth on ingress, but not in host ns, of course, so hook won't
be invoked.)

Thanks,
Daniel