netdev - Re: [PATCH net-next 09/10] netfilter: get ipv6 pktlen properly in length

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: <CANn89iKc9HiswDGVVUBGDUef3V74Cq0pWdAG-zMK79pC6oDyEA@mail.gmail.com>
Date:   Mon, 16 Jan 2023 17:02:12 +0100
From:   Eric Dumazet <edumazet@...gle.com>
To:     David Ahern <dsahern@...il.com>
Cc:     Xin Long <lucien.xin@...il.com>,
        network dev <netdev@...r.kernel.org>, davem@...emloft.net,
        kuba@...nel.org, Paolo Abeni <pabeni@...hat.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Pravin B Shelar <pshelar@....org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Westphal <fw@...len.de>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Ilya Maximets <i.maximets@....org>,
        Aaron Conole <aconole@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Mahesh Bandewar <maheshb@...gle.com>,
        Paul Moore <paul@...l-moore.com>,
        Guillaume Nault <gnault@...hat.com>
Subject: Re: [PATCH net-next 09/10] netfilter: get ipv6 pktlen properly in length_mt6

On Mon, Jan 16, 2023 at 4:08 PM David Ahern <dsahern@...il.com> wrote:
>

> not sure why you think it would not be detected. Today's model for gro
> sets tot_len based on skb->len. There is an inherent trust that the
> user's of the gro API set the length correctly. If it is not, the
> payload to userspace would ultimately be non-sense and hence detectable.

Only if you use some kind of upper protocol adding message integrity
verification.

> >
> > As you said, user space sniffing packets now have to guess what is the
> > intent, instead of headers carrying all the needed information
> > that can be fully validated by parsers.
>
> This is a solveable problem within the packet socket API, and the entire
> thing is opt-in. If a user's tcpdump / packet capture program is out of
> date and does not support the new API for large packets, then that user
> does not have to enable large GRO/TSO.

I do not see this being solved yet.

We have enabled BIG TCP only for IPv6, we do not want the same to
magically be enabled for ipv4
when a new kernel is deployed.

Make sure that IPV4 BIG TCP is guarded by a separate tunable.

Note that our initial patches were adding IPv6 tunables for a reason.

We agreed to change them to IFLA_GRO_MAX_SIZE, IFLA_TSO_MAX_SIZE,
as long as they would not enable unwanted/untested behavior.