net: Add sockaddr_inet unified address structure

Hi!

Repeating patch 1, as it has the rationale:

There are cases in networking (e.g. wireguard, sctp) where a union is used to provide coverage for either IPv4 or IPv6 network addresses, and they include an embedded "struct sockaddr" as well (for "sa_family" and raw "sa_data" access). The current struct sockaddr contains a flexible array, which means these unions should not be further embedded in other structs because they do not technically have a fixed size (and are generating warnings for the coming -Wflexible-array-not-at-end flag addition). But the future changes to make struct sockaddr a fixed size (i.e. with a 14 byte sa_data member) make the "sa_data" uses with an IPv6 address a potential place for the compiler to get upset about object size mismatches. Therefore, we need a sockaddr that cleanly provides both an sa_family member and an appropriately fixed-sized sa_data member that does not bloat member usage via the potential alternative of sockaddr_storage to cover both IPv4 and IPv6, to avoid unseemly churn in the affected code bases.

Introduce sockaddr_inet as a unified structure for holding both IPv4 and IPv6 addresses (i.e. large enough to accommodate sockaddr_in6).

The structure is defined in linux/in6.h since its max size is sized based on sockaddr_in6 and provides a more specific alternative to the generic sockaddr_storage for IPv4 with IPv6 address family handling.

The "sa_family" member doesn't use the sa_family_t type to avoid needing layer violating header inclusions.

Also includes the replacements for wireguard and sctp.

Thanks,

-Kees

Kees Cook (3):
ipv6: Add sockaddr_inet unified address structure
wireguard: peer: Replace sockaddr with sockaddr_inet
sctp: Replace sockaddr with sockaddr_inet in sctp_addr union

 drivers/net/wireguard/peer.h | 2 +-
 include/linux/in6.h          | 7 +++++++
 include/net/sctp/structs.h   | 2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)

2.34.1