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Date:   Tue, 8 Aug 2023 17:22:11 +0200
From:   Sabrina Dubroca <sd@queasysnail.net>
To:     "Radu Pirea (NXP OSS)" <radu-nicolae.pirea@oss.nxp.com>
Cc:     davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: macsec: use TX SCI as MAC address
Message-ID: <ZNJdo6bow7uK8bTn@hog>
References: <20230808141429.220830-1-radu-nicolae.pirea@oss.nxp.com>
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2023-08-08, 17:14:29 +0300, Radu Pirea (NXP OSS) wrote:
> According to IEEE 802.1AE the SCI comprises the MAC address and the port
> identifier.

I don't think the SCI needs to be composed of the actual device's MAC
address. 8.2.1 says that the MAC address *can* be used to compose the
SCI, but doesn't mandate it.

If you want the SCI to match the device's MAC address, why not use
IFLA_MACSEC_PORT instead?

> If a new MACsec interface is created with a specific TX SCI, use that
> SCI to set the MAC address of the new interface.
> 
> Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
> ---
>  drivers/net/macsec.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
> index 984dfa5d6c11..6db69daf880d 100644
> --- a/drivers/net/macsec.c
> +++ b/drivers/net/macsec.c
> @@ -4103,12 +4103,14 @@ static int macsec_newlink(struct net *net, struct net_device *dev,
>  	/* need to be already registered so that ->init has run and
>  	 * the MAC addr is set
>  	 */
> -	if (data && data[IFLA_MACSEC_SCI])
> +	if (data && data[IFLA_MACSEC_SCI]) {
>  		sci = nla_get_sci(data[IFLA_MACSEC_SCI]);
> -	else if (data && data[IFLA_MACSEC_PORT])
> +		eth_hw_addr_set(dev, (u8 *)&sci);
> +	} else if (data && data[IFLA_MACSEC_PORT]) {
>  		sci = dev_to_sci(dev, nla_get_be16(data[IFLA_MACSEC_PORT]));
> -	else
> +	} else {
>  		sci = dev_to_sci(dev, MACSEC_PORT_ES);
> +	}
>  
>  	if (rx_handler && sci_exists(real_dev, sci)) {
>  		err = -EBUSY;
> -- 
> 2.34.1
> 

-- 
Sabrina