Subject: Re: BUG REPORT: iproute2 seems to have bug with dsfield/tos in ip-rule and ip-route

From: Stephen Hemminger <[email-masked]>
Date: Wed, 13 Dec 2017 10:12:59 -0800

On Wed, 13 Dec 2017 09:40:08 -0800
Daniel Lakeland <[email-masked]> wrote:

> This same problem as detailed here
> 
> http://lists.openwall.net/netdev/2010/03/26/36

This mail reports an issue from 7 years ago, much nas
changed since then.

> 
> or here:
> 
> https://www.spinics.net/lists/lartc/msg22541.html
> 
> bit me today
> 
> I tried either
> 
> ip rule add dsfield CS6 table 100
> 
> or
> 
> ip rule add dsfield 0xc0 table 100
> 
> or replace dsfield with tos, all return:
> 
> RTNETLINK answers: Invalid argument
> 
> on the other hand, for ip route it will accept the ds/tos values
> 
> ip route add default dsfield CS6 dev dummy0
> 
> or
> 
> ip route add default dsfield 0xc0 dev dummy0
> 
> but packets tagged with CS6 don't go to dummy0 they go the regular 
> default route
> 
> 

The kernel is complaining that ip rule is not valid, (ie not iproute2 issue).
Not sure exactly why or where in fib_rules.c this is happening.