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Date:   Wed, 01 Apr 2020 11:14:27 -0700 (PDT)
Message-Id: <20200401.111427.789296252666544265.davem@davemloft.net>
To:     jarod@redhat.com
Cc:     linux-kernel@vger.kernel.org, moshele@mellanox.com,
        stephen@networkplumber.org, mleitner@redhat.com,
        netdev@vger.kernel.org
Subject: Re: [PATCH net v2] ipv6: don't auto-add link-local address to lag
 ports
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20200330152219.58296-1-jarod@redhat.com>
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        <20200330152219.58296-1-jarod@redhat.com>
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From: Jarod Wilson <jarod@redhat.com>
Date: Mon, 30 Mar 2020 11:22:19 -0400

> Bonding slave and team port devices should not have link-local addresses
> automatically added to them, as it can interfere with openvswitch being
> able to properly add tc ingress.
> 
> Basic reproducer, courtesy of Marcelo:
 ...
> (above trimmed to relevant entries, obviously)
> 
> $ sysctl net.ipv6.conf.ens2f0np0.addr_gen_mode=0
> net.ipv6.conf.ens2f0np0.addr_gen_mode = 0
> $ sysctl net.ipv6.conf.ens2f1np2.addr_gen_mode=0
> net.ipv6.conf.ens2f1np2.addr_gen_mode = 0
> 
> $ ip a l ens2f0np0
> 2: ens2f0np0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc
> mq master bond0 state UP group default qlen 1000
>     link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::20f:53ff:fe2f:ea40/64 scope link tentative
>        valid_lft forever preferred_lft forever
> $ ip a l ens2f1np2
> 5: ens2f1np2: <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP> mtu 1500 qdisc
> mq master bond0 state DOWN group default qlen 1000
>     link/ether 00:0f:53:2f:ea:40 brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::20f:53ff:fe2f:ea40/64 scope link tentative
>        valid_lft forever preferred_lft forever
> 
> Looks like addrconf_sysctl_addr_gen_mode() bypasses the original "is
> this a slave interface?" check added by commit c2edacf80e15, and
> results in an address getting added, while w/the proposed patch added,
> no address gets added. This simply adds the same gating check to another
> code path, and thus should prevent the same devices from erroneously
> obtaining an ipv6 link-local address.
> 
> Fixes: d35a00b8e33d ("net/ipv6: allow sysctl to change link-local address generation mode")
> Reported-by: Moshe Levi <moshele@mellanox.com>
> CC: Stephen Hemminger <stephen@networkplumber.org>
> CC: Marcelo Ricardo Leitner <mleitner@redhat.com>
> CC: netdev@vger.kernel.org
> Signed-off-by: Jarod Wilson <jarod@redhat.com>

Applied and queued up for -stable, thanks.