netdev - Re: [net,v2] netfilter: nat: fix ICMP header corruption on ICMP errors

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Message-ID: <20200114113152.GN795@breakpoint.cc>
Date:   Tue, 14 Jan 2020 12:31:52 +0100
From:   Florian Westphal <fw@...len.de>
To:     Eyal Birger <eyal.birger@...il.com>
Cc:     pablo@...filter.org, kadlec@...filter.org, fw@...len.de,
        davem@...emloft.net, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, netdev@...r.kernel.org,
        Shmulik Ladkani <shmulik.ladkani@...il.com>
Subject: Re: [net,v2] netfilter: nat: fix ICMP header corruption on ICMP
 errors

Eyal Birger <eyal.birger@...il.com> wrote:
> Commit 8303b7e8f018 ("netfilter: nat: fix spurious connection timeouts")
> made nf_nat_icmp_reply_translation() use icmp_manip_pkt() as the l4
> manipulation function for the outer packet on ICMP errors.
> 
> However, icmp_manip_pkt() assumes the packet has an 'id' field which
> is not correct for all types of ICMP messages.
> 
> This is not correct for ICMP error packets, and leads to bogus bytes
> being written the ICMP header, which can be wrongfully regarded as
> 'length' bytes by RFC 4884 compliant receivers.
> 
> Fix by assigning the 'id' field only for ICMP messages that have this
> semantic.

Looks good, thanks Eyal.

Acked-by: Florian Westphal <fw@...len.de>