netdev - Re: [PATCH V9 net-next 11/11] net: add ndo_validate_addr check in dev_set_mac

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Message-ID: <a167de50-9759-4ba6-97a6-96cd6356fdc3@lunn.ch>
Date: Wed, 11 Sep 2024 16:41:03 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Jijie Shao <shaojijie@...wei.com>
Cc: Kalesh Anakkur Purayil <kalesh-anakkur.purayil@...adcom.com>,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, shenjian15@...wei.com, wangpeiyang1@...wei.com,
	liuyonglong@...wei.com, chenhao418@...wei.com,
	sudongming1@...wei.com, xujunsheng@...wei.com,
	shiyongbang@...wei.com, libaihan@...wei.com, jdamato@...tly.com,
	horms@...nel.org, jonathan.cameron@...wei.com,
	shameerali.kolothum.thodi@...wei.com, salil.mehta@...wei.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V9 net-next 11/11] net: add ndo_validate_addr check in
 dev_set_mac_address

> This patch may not work as expected.
> 
> ndo_validate_addr() has only one parameter.
> The sa parameter of the MAC address is not transferred to the function.
> So ndo_validate_addr() checks the old MAC address, not the new MAC address.

Yes, i agree. The current API does not lend itself to validation
before change.

> I haven't found a better way to fix it yet.

Maybe in dev_set_mac_address(), make a copy of dev->dev_addr. Call
ops->ndo_set_mac_address(). If there is no error call
ndo_validate_addr(). If that returns an error, call
ops->ndo_set_mac_address() again with the old MAC address, and then
return the error from ndo_validate_addr().

It is not great, but it is the best i can think of.

Since this is not as simple i was expecting, feel free to drop it from
your patchset, and submit it as a standalone patch.

	Andrew