Re: [PATCH 5/5] ipv4: Add FIB nexthop exceptions.

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 17 Jul 2012 16:00:05 +0200

> On Tue, 2012-07-17 at 06:14 -0700, David Miller wrote:
>> In a regime where we have subnetted route entries, we need a way to
>> store persistent storage about destination specific learned values
>> such as redirects and PMTU values.
>> 
>> This is implemented here via nexthop exceptions.
>> 
>> The initial implementation is a simple linked list, and can be
>> expanded to a hash table when it is shown to be justified.
> 
> Say a typical host uses a single default route, I am trying to convince
> myself it can really use a simple linked list ?
> 
> Arent PMTU entries added by messages coming from untrusted sources ?

They are trusted when we validate them at the socket layer, at least
as is done for TCP.

I totally agree that we'll need to adjust the list into something more
sophisticated, but that's an implementation detail rather than
something that requires the actual infrastructure to be redone.