netdev - Re: [RFC PATCH ipsec] xfrm: don't pass too short packets to userspace with ESPINUDP encap

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Message-ID: <20200727092819.GY20687@gauss3.secunet.de>
Date:   Mon, 27 Jul 2020 11:28:19 +0200
From:   Steffen Klassert <steffen.klassert@...unet.com>
To:     Sabrina Dubroca <sd@...asysnail.net>
CC:     <netdev@...r.kernel.org>, Paul Wouters <paul@...ats.ca>,
        Andrew Cagney <andrew.cagney@...il.com>,
        Tobias Brunner <tobias@...ongswan.org>
Subject: Re: [RFC PATCH ipsec] xfrm: don't pass too short packets to
 userspace with ESPINUDP encap

On Fri, Jul 24, 2020 at 04:46:07PM +0200, Sabrina Dubroca wrote:
> Currently, any UDP-encapsulated packet of 8 bytes or less will be
> passed to userspace, whether it starts with the non-ESP prefix or
> not (except keepalives). This includes:
>  - messages of 1, 2, 3 bytes
>  - messages of 4 to 8 bytes not starting with 00 00 00 00
> 
> This patch changes that behavior, so that only properly-formed non-ESP
> messages are passed to userspace. Messages of 8 bytes or less that
> don't contain a full non-ESP prefix followed by some data (at least
> one byte) will be dropped and counted as XfrmInHdrError.

I'm ok with that change. But it affects userspace, so the *swan
people have to tell if that's ok for them.