netdev - Re: Bug w/ (policy) routing

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Message-ID: <20170102180548.1390a09c@jjacky.com>
Date:   Mon, 2 Jan 2017 18:05:48 +0100
From:   Olivier Brunel <jjk@...cky.com>
To:     David Ahern <dsa@...ulusnetworks.com>
Cc:     netdev@...r.kernel.org
Subject: Re: Bug w/ (policy) routing

On Mon, 2 Jan 2017 09:48:12 -0700
David Ahern <dsa@...ulusnetworks.com> wrote:

> On 1/1/17 12:52 PM, Olivier Brunel wrote:
> > Indeed, if I first delete the rule for lookup local and recreate it
> > w/ higher prio than my "lookup 50", then no more issue.  
> 
> After the unshare or when creating a new network namespace, bringing
> the lo device up will create the local table and the rest of the
> commands will work properly. ie., instead of moving the local rule
> you can run:

Indeed, and that's a much better solution for me, since I bring lo up
anyways, I might as well do it first. Thank you.


> unshare -n bash
> 
> ip li set lo up
> ip rule add table 50 prio 50
> ip link add test type veth peer name test2
> ...
> 
> -----
> 
> Alex: 
> 
> The order of commands is influencing whether the unmerge succeeds or
> not which is wrong. I took a quick look and I don't see a simple
> solution to this. Effectively:
> 
> Adding a rule before bringing up any interface does not unmerge the
> tables: $ unshare -n bash
> $ ip rule add table 50 prio 50
> $ ip li set lo up
> 
> In fib_unmerge(), fib_new_table(net, RT_TABLE_LOCAL) returns null.
> 
> 
> Where the reverse order works:
> $ unshare -n bash
> $ ip li set lo up
> $ ip rule add table 50 prio 50
> 
> David