netdev - Re: [RFC] Fixing up TCP/UDP checksum for UDP encap. ESP4 packets in transport mode

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, 7 Jul 2009 09:58:50 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	David Miller <davem@...emloft.net>
Cc:	christophe@...ut.de, netdev@...r.kernel.org
Subject: Re: [RFC] Fixing up TCP/UDP checksum for UDP encap. ESP4 packets
	in transport mode

On Mon, Jul 06, 2009 at 06:54:11PM -0700, David Miller wrote:
> 
> Hmmm, aren't we talking about packets which were protected by either a
> hash, strong encryption, or both at some point?

Only if there is no inner NAT, i.e., only if this patch isn't
needed.  Otherwise

Source  ---  GW1  ----  GW2  ---  Dest

the path between Source and GW1, will be unprotected if transport
mode is used between GW1 and GW2.  The only bit protected by IPsec's
hash is between GW1 and GW2.

When the traffic comes back, then the bit between Dest and GW2 will
be unprotected.  This is why the only safe way to use this would be
if your traffic is one-way and you only had inner NAT at the other
end.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
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