netdev - Re: [PATCH net] team: prevent ipv6 link local address on port devices

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Date:   Tue, 6 Dec 2022 16:52:33 -0500
From:   Xin Long <lucien.xin@...il.com>
To:     Jiri Pirko <jiri@...nulli.us>,
        Stephen Hemminger <stephen@...workplumber.org>
Cc:     network dev <netdev@...r.kernel.org>, davem@...emloft.net,
        kuba@...nel.org, Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, LiLiang <liali@...hat.com>
Subject: Re: [PATCH net] team: prevent ipv6 link local address on port devices

On Tue, Dec 6, 2022 at 8:32 AM Xin Long <lucien.xin@...il.com> wrote:
>
> On Tue, Dec 6, 2022 at 3:05 AM Jiri Pirko <jiri@...nulli.us> wrote:
> >
> > Mon, Dec 05, 2022 at 06:46:05PM CET, lucien.xin@...il.com wrote:
> > >The similar fix from commit c2edacf80e15 ("bonding / ipv6: no addrconf
> > >for slaves separately from master") is also needed in Team. Otherwise,
> > >DAD and RS packets to be sent from the slaves in turn can confuse the
> > >switches and cause them to incorrectly update their forwarding tables
> > >as Liang noticed in the test with activebackup mode.
> > >
> > >Note that the patch also sets IFF_MASTER flag for Team dev accordingly
> > >while IFF_SLAVE flag is set for port devs. Although IFF_MASTER flag is
> > >not really used in Team, it's good to show in 'ip link':
> > >
> > >  eth1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP>
> > >  team0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP>
> > >
> > >Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
> > >Reported-by: LiLiang <liali@...hat.com>
> > >Signed-off-by: Xin Long <lucien.xin@...il.com>
> >
> > Nack. Please don't do this. IFF_MASTER and IFF_SLAVE are historical
> > flags used by bonding and eql. Should not be used for other devices.
> I see. I was wondering why it was not used in Team at the beginning. :)
>
> >
> > addrconf_addr_gen() should not check IFF_SLAVE. It should use:
> > netif_is_lag_port() and netif_is_failover_slave() helpers.
Hi Jiri,

Sorry, it seems not to work with this.

As addrconf_addr_gen() is also called in NETDEV_UP event where
IFF_TEAM_PORT and IFF_BONDING haven't yet been set before
dev_open() when adding the port.

If we move IFF_TEAM_PORT setting ahead of dev_open(), it will revert
the fix in:

commit d7d3c05135f37d8fdf73f9966d27155cada36e56
Author: Jiri Pirko <jiri@...nulli.us>
Date:   Mon Aug 25 21:38:27 2014 +0200

    team: set IFF_TEAM_PORT priv_flag after rx_handler is registered

Can we keep IFF_SLAVE here only for no ipv6 addrconf?
or do you see a better solution?

Thanks.