Subject: Re: [PATCH 19/64] ip: Use struct_group() for memcpy() regions

From: Kees Cook <[email-masked]>
Date: Wed, 28 Jul 2021 14:01:24 -0700

On Wed, Jul 28, 2021 at 07:55:53AM +0200, Greg Kroah-Hartman wrote:
> >  struct ethhdr {
> > -	unsigned char	h_dest[ETH_ALEN];	/* destination eth addr	*/
> > -	unsigned char	h_source[ETH_ALEN];	/* source ether addr	*/
> > +	union {
> > +		struct {
> > +			unsigned char h_dest[ETH_ALEN];	  /* destination eth addr */
> > +			unsigned char h_source[ETH_ALEN]; /* source ether addr	  */
> > +		};
> > +		struct {
> > +			unsigned char h_dest[ETH_ALEN];	  /* destination eth addr */
> > +			unsigned char h_source[ETH_ALEN]; /* source ether addr	  */
> > +		} addrs;
> 
> A union of the same fields in the same structure in the same way?
> 
> Ah, because struct_group() can not be used here?  Still feels odd to see
> in a userspace-visible header.

Yeah, there is some inconsistency here. I will clean this up for v2.

Is there a place we can put kernel-specific macros for use in UAPI
headers? (I need to figure out where things like __kernel_size_t get
defined...)

-- 
Kees Cook