netdev - Re: [PATCH iwl-net v1 1/2] drivers/net/bonding/bond_3ad: Use updated MAC address for lacpdu packets

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Message-ID: <31753.1684249376@famine>
Date: Tue, 16 May 2023 08:02:56 -0700
From: Jay Vosburgh <jay.vosburgh@...onical.com>
To: Mateusz Palczewski <mateusz.palczewski@...el.com>
cc: andy@...yhouse.net, davem@...emloft.net, edumazet@...gle.com,
    kuba@...nel.org, pabeni@...hat.com, dbanerje@...mai.com,
    netdev@...r.kernel.org,
    Sebastian Basierski <sebastianx.basierski@...el.com>
Subject: Re: [PATCH iwl-net v1 1/2] drivers/net/bonding/bond_3ad: Use updated MAC address for lacpdu packets

Mateusz Palczewski <mateusz.palczewski@...el.com> wrote:

>From: Sebastian Basierski <sebastianx.basierski@...el.com>
>
>After changing VFs MAC address, bonding driver shouldn't use
>the old address. Otherwise lapcdu packets will have set wrong
>source MAC address.

	This patch is incorrect, the existing code is behaving
correctly.

	Bonding uses the original device MAC address deliberately, as
IEEE 802.1AX-2014 6.2.1.i requires that each port utilize a MAC address
that is "unique over the LAG" as the source address for LACPDUs.

	As bonding sets all ports of the bond to the same MAC (so that
non-control traffic uses the same source MAC per 802.1AX 6.2.1.j), this
change would cause every port of the bond to use a single MAC address
for the LACPDU source address, thus violating 802.1AX.

	-J

>Fixes: ada0f8633c5b ("bonding: Convert memcpy(foo, bar, ETH_ALEN) to ether_addr_copy(foo, bar)")
>Signed-off-by: Sebastian Basierski <sebastianx.basierski@...el.com>
>Signed-off-by: Mateusz Palczewski <mateusz.palczewski@...el.com>
>---
> drivers/net/bonding/bond_3ad.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>index c99ffe6c683a..b5202af79f20 100644
>--- a/drivers/net/bonding/bond_3ad.c
>+++ b/drivers/net/bonding/bond_3ad.c
>@@ -869,10 +869,10 @@ static int ad_lacpdu_send(struct port *port)
> 	lacpdu_header = skb_put(skb, length);
> 
> 	ether_addr_copy(lacpdu_header->hdr.h_dest, lacpdu_mcast_addr);
>-	/* Note: source address is set to be the member's PERMANENT address,
>+	/* Note: source address is set to be the member's CURRENT address,
> 	 * because we use it to identify loopback lacpdus in receive.
> 	 */
>-	ether_addr_copy(lacpdu_header->hdr.h_source, slave->perm_hwaddr);
>+	ether_addr_copy(lacpdu_header->hdr.h_source, slave->dev->dev_addr);
> 	lacpdu_header->hdr.h_proto = PKT_TYPE_LACPDU;
> 
> 	lacpdu_header->lacpdu = port->lacpdu;
>-- 
>2.31.1

---
	-Jay Vosburgh, jay.vosburgh@...onical.com