netdev - Re: [PATCH] ipv4/ipv6: check hop limit field on input

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]

Date:	Tue, 02 Jun 2009 11:36:29 +0200
From:	Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] ipv4/ipv6: check hop limit field on input

David Miller wrote:
> From: Nicolas Dichtel <nicolas.dichtel@....6wind.com>
> Date: Mon, 01 Jun 2009 17:13:43 +0200
> 
>> RFC indicates that a router must drop the packet if this field is 0.
> 
> It only must do this when executing the forwarding function.  It's an
> egress check, not an ingress one.
In my understanding, it can be on input to:
RFC4443 Section 3.3:
    If a router receives a packet with a Hop Limit of zero, or if a
    router decrements a packet's Hop Limit to zero, it MUST discard the
    packet and originate an ICMPv6 Time Exceeded message with Code 0 to
    the source of the packet.

> 
> I'm not applying this patch, it can even break some applications
> out there that use a TTL of zero intentionally to keep traffic
> only on a local subnet.
OK ok. John sends good arguments ;-)


Nicolas

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html