While reviewing the struct proto_ops connect() and bind() callback
implementations, I noticed that there doesn't appear to be any
validation that AF_PPPOX sockaddr structures actually have sa_family set
to AF_PPPOX. The pppol2tp_sockaddr_get_info() checks only look at the
sizes.

I don't see any way that this might actually cause problems as specific
info fields are being populated, for which the existing size checks are
correct, but it stood out as a missing address family check.

Add the check and return -EAFNOSUPPORT on mismatch.

Signed-off-by: Kees Cook <[email protected]>

Update all struct proto_ops bind() callback function prototypes from
"struct sockaddr *" to "struct sockaddr_unspec *" to avoid lying to the
compiler about object sizes. Calls into struct proto handlers gain casts
that will be removed in the struct proto conversion patch.

No binary changes expected.

Signed-off-by: Kees Cook <[email protected]>

Update all struct proto_ops connect() callback function prototypes from
"struct sockaddr *" to "struct sockaddr_unspec *" to avoid lying to the
compiler about object sizes. Calls into struct proto handlers gain casts
that will be removed in the struct proto conversion patch.

No binary changes expected.

Signed-off-by: Kees Cook <[email protected]>

Now that struct sockaddr is no longer used by net.h, remove it.

Signed-off-by: Kees Cook <[email protected]>

Update BPF cgroup sockaddr filtering infrastructure to use sockaddr_unspec
consistently throughout the call chain, removing redundant explicit casts
from callers.

Signed-off-by: Kees Cook <[email protected]>

Change struct bpf_sock_addr_kern to use sockaddr_unspec for the "uaddr"
field instead of sockaddr. This improves type safety in the BPF cgroup
socket address filtering code.

The casting in __cgroup_bpf_run_filter_sock_addr() is updated to match the
new type, removing an unnecessary cast in the initialization and updating
the conditional assignment to use the appropriate sockaddr_unspec cast.

Signed-off-by: Kees Cook <[email protected]>

Revert struct sockaddr from flexible array to fixed 14-byte "sa_data",
solves over 36,000 -Wflex-array-member-not-at-end warnings, since struct
sockaddr is embedded within many network structs.

With socket/proto sockaddr-based internal APIs switched to use struct
sockaddr_unspec, there should be no more uses of struct sockaddr that
depend on reading beyond the end of struct sockaddr::sa_data that might
trigger bounds checking.

Comparing an x86_64 "allyesconfig" vmlinux build before and after this
patch showed no new "ud1" instructions from CONFIG_UBSAN_BOUNDS nor any
explicit "field-spanning" memcpy CONFIG_FORTIFY_SOURCE instrumentations.

Cc: "Gustavo A. R. Silva" <[email protected]>
Signed-off-by: Kees Cook <[email protected]>