linux-kernel - Re: [PATCH net-next v2 8/8] net: core: Convert dev_set_mac_address_user() to use struct sockaddr

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Message-ID: <202505271142.EA78EAB04@keescook>
Date: Tue, 27 May 2025 11:43:08 -0700
From: Kees Cook <kees@...nel.org>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Kuniyuki Iwashima <kuniyu@...zon.com>,
	Willem de Bruijn <willemdebruijn.kernel@...il.com>,
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Subject: Re: [PATCH net-next v2 8/8] net: core: Convert
 dev_set_mac_address_user() to use struct sockaddr_storage

On Tue, May 27, 2025 at 09:02:28AM +0200, Paolo Abeni wrote:
> On 5/21/25 10:46 PM, Kees Cook wrote:
> > diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
> > index fff13a8b48f1..616479e71466 100644
> > --- a/net/core/dev_ioctl.c
> > +++ b/net/core/dev_ioctl.c
> > @@ -572,9 +572,11 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
> >  		return dev_set_mtu(dev, ifr->ifr_mtu);
> >  
> >  	case SIOCSIFHWADDR:
> > -		if (dev->addr_len > sizeof(struct sockaddr))
> > +		if (dev->addr_len > sizeof(ifr->ifr_hwaddr))
> >  			return -EINVAL;
> > -		return dev_set_mac_address_user(dev, &ifr->ifr_hwaddr, NULL);
> > +		return dev_set_mac_address_user(dev,
> > +						(struct sockaddr_storage *)&ifr->ifr_hwaddr,
> > +						NULL);
> 
> Side note for a possible follow-up: the above pattern is repeated a
> couple of times: IMHO consolidating it into an helper would be nice.

Yeah, I will look at that.

> Also such helper could/should explicitly convert ifr->ifr_hwaddr to
> sockaddr_storage and avoid the cast.

It's UAPI, so it looked verrrry painful to change.

-- 
Kees Cook