netdev - Re: [PATCH RESEND] ipv6: add anti-spoofing checks for 6to4 and 6rd

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Message-ID: <loom.20130627T154125-104@post.gmane.org>
Date:	Thu, 27 Jun 2013 13:49:59 +0000 (UTC)
From:	Roman Mamedov <rm@...anrm.ru>
To:	netdev@...r.kernel.org
Subject: Re: [PATCH RESEND] ipv6: add anti-spoofing checks for 6to4 and 6rd

Hannes Frederic Sowa <hannes <at> stressinduktion.org> writes:

> 
> This patch adds anti-spoofing checks in sit.c as specified in RFC3964
> section 5.2 for 6to4 and RFC5969 section 12 for 6rd. I left out the
> checks which could easily be implemented with netfilter.
> 
> Specifically this patch adds following logic (based loosely on the
> pseudocode in RFC3964 section 5.2):
> 
> if prefix (inner_src_v6) == rd6_prefix (2002::/16 is the default)
>         and outer_src_v4 != embedded_ipv4 (inner_src_v6)
>                 drop
> if prefix (inner_dst_v6) == rd6_prefix (or 2002::/16 is the default)
>         and outer_dst_v4 != embedded_ipv4 (inner_dst_v6)
>                 drop
> accept
> 
> To accomplish the specified security checks proposed by above RFCs,
> it is still necessary to employ uRPF filters with netfilter. These new
> checks only kick in if the employed addresses are within the 2002::/16 or
> another range specified by the 6rd-prefix (which defaults to 2002::/16).

Hello,

This broke access to all 6to4 destinations from any unrelated sit tunnels.

For example users of tunnelbroker.net IPv6 tunnel service (2001:470::/32)
can no longer communicate with anyone using 6to4 anywhere on the internet.

In general, any host, routing to/from which happens to traverse a sit
tunnel (using native IPv6 ranges), can no longer successfully send
packets to a 6to4 destination.

Thanks


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