linux-kernel - Re: [PATCH] net: ipv6: fix __rt6_purge_dflt_routers when forwarding is not set on all ifaces

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Message-ID: <CANn89iL+C5QWxbqKbxcdAa=BtDkEg-tm5dNnvrvXJrMRXQb=mg@mail.gmail.com>
Date:   Tue, 1 Sep 2020 10:20:27 +0200
From:   Eric Dumazet <edumazet@...gle.com>
To:     Brian Vazquez <brianvv@...gle.com>
Cc:     Brian Vazquez <brianvv.kernel@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        David Ahern <dsa@...ulusnetworks.com>
Subject: Re: [PATCH] net: ipv6: fix __rt6_purge_dflt_routers when forwarding
 is not set on all ifaces

On Tue, Sep 1, 2020 at 8:58 AM Brian Vazquez <brianvv@...gle.com> wrote:
>
> The problem is exposed when the system has multiple ifaces and
> forwarding is enabled on a subset of them, __rt6_purge_dflt_routers will
> clean the default route on all the ifaces which is not desired.

What is the exact problem you want to fix ?

>
> This patches fixes that by cleaning only the routes where the iface has
> forwarding enabled.

This seems like a new feature, and this might break some setups.

linux always had removed any IPv6 address and default route it learnt via SLAAC.
(this might be to conform to one RFC or known security rule).
It would be nice to add a nice comment giving references.

>
> Fixes: 830218c1add1 ("net: ipv6: Fix processing of RAs in presence of VRF")

Please provide a test, or a better commit message ?

If your patch targets the net tree, then it should only fix a bug.

Thanks.