Re: [PATCH v3 1/9] net: Add struct sockaddr_unspec for sockaddr of unknown length

On Thu, Oct 23, 2025 at 12:43:06PM +0200, Paolo Abeni wrote:

On 10/20/25 11:26 PM, Kees Cook wrote:

quoted

Add flexible sockaddr structure to support addresses longer than the
traditional 14-byte struct sockaddr::sa_data limitation without
requiring the full 128-byte sa_data of struct sockaddr_storage. This
allows the network APIs to pass around a pointer to an object that
isn't lying to the compiler about how big it is, but must be accompanied
by its actual size as an additional parameter.

It's possible we may way to migrate to including the size with the
struct in the future, e.g.:

struct sockaddr_unspec {
	u16 sa_data_len;
	u16 sa_family;
	u8  sa_data[] __counted_by(sa_data_len);
};

Side note: sockaddr_unspec is possibly not the optimal name, as
AF_UNSPEC has a specific meaning/semantic.

Name-wise, I think 'sockaddr_sized' would be better, but I agree with
David the struct may cause unaligned access problems.

I'll go with sockaddr_unsized -- doing the sockaddr_sized variant is a
much more involved change. I just want to get us to where we are today
but with no lying to the compiler about sizes. :)

-- 
Kees Cook