Test that sys_sendmsg BPF hook doesn't break sys_sendmsg behaviour to
rewrite destination IPv6 = [::] with [::1] (BSD'ism).
Two test cases are added:
1) User passes dst IPv6 = [::] and BPF_CGROUP_UDP6_SENDMSG program
doesn't touch it.
2) User passes dst IPv6 != [::], but BPF_CGROUP_UDP6_SENDMSG program
rewrites it with [::].
In both cases [::1] is used by sys_sendmsg code eventually and datagram
is sent successfully for unconnected UDP socket.
Example of relevant output:
Test case: sendmsg6: set dst IP = [::] (BSD'ism) .. [PASS]
Test case: sendmsg6: preserve dst IP = [::] (BSD'ism) .. [PASS]
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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