Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220829114648.GA2409@debian> <CANn89iLkfMUK8n5w00naST9J+KrLaAqqg2r0X9Sd-L0XzpLzSQ@mail.gmail.com>
 <20220901150115.GB31767@debian>
In-Reply-To: <20220901150115.GB31767@debian>
From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 1 Sep 2022 09:06:59 -0700
Message-ID: <CANn89iKMe7WZS-Q4rzqEUUD+ANL6Fmb6BnFo8TvX7y_EVi=HOw@mail.gmail.com>
Subject: Re: [PATCH 3/4] net-next: frags: add inetpeer frag_mem tracking
To:     Richard Gobert <richardbgobert@gmail.com>
Cc:     David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Alexander Aring <alex.aring@gmail.com>,
        Stefan Schmidt <stefan@datenfreihafen.org>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        Martin KaFai Lau <kafai@fb.com>,
        netdev <netdev@vger.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-wpan@vger.kernel.org,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Sep 1, 2022 at 8:03 AM Richard Gobert <richardbgobert@gmail.com> wrote:
>
> On Mon, Aug 29, 2022 at 03:15:47PM -0700, Eric Dumazet wrote:
> > We tried to get rid of any dependence over inetpeer, which is not
> > resistant against DDOS attacks.
> >
> > So I would not add a new dependency.
>
> I see your point. What do you suggest doing differently?
>
> The inetpeer mechanism is used for IPv4 frags. If it isn't resistant
> against DDoS attacks, can it perhaps be improved?

It can be disabled if needed, by changing ipfrag_max_dist sysctl.

Quite frankly IPv4 reassembly unit is a toy, I am always surprised
some applications are still relying on IP fragments.