Merge branch 'net-add-sockaddr_inet-unified-address-structure'

Kees Cook says:

====================
net: Add sockaddr_inet unified address structure

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.
====================

Link: https://patch.msgid.link/20250722171528.work.209-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>