linux-kernel - Re: PROBLEM: DoS Attack on Fragment Cache

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Message-ID: <9e2966be-d210-edf9-4f3c-5681f0d07c5f@bluematt.me>
Date:   Sun, 18 Apr 2021 10:31:33 -0400
From:   Matt Corallo <netdev-list@...tcorallo.com>
To:     Willy Tarreau <w@....eu>
Cc:     Keyu Man <kman001@....edu>, Eric Dumazet <edumazet@...gle.com>,
        David Ahern <dsahern@...il.com>,
        Florian Westphal <fw@...len.de>, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Zhiyun Qian <zhiyunq@...ucr.edu>
Subject: Re: PROBLEM: DoS Attack on Fragment Cache

Should the default, though, be so low? If someone is still using a old modem they can crank up the sysctl, it does seem 
like such things are pretty rare these days :). Its rather trivial to, without any kind of attack, hit 1Mbps of lost 
fragments in today's networks, at which point all fragments are dropped. After all, I submitted the patch to "scratch my 
own itch" :).

Matt

On 4/18/21 00:39, Willy Tarreau wrote:
> I do agree that we shouldn't keep them that long nowadays, we can't go
> too low without risking to break some slow transmission stacks (SLIP/PPP
> over modems for example).