Merge branch 'bpf-ctx-narrow'

Yonghong Song says:

====================
bpf: permit bpf program narrower loads for ctx fields

Today, if users try to access a ctx field through a narrower load, e.g.,
__be16 prot = __sk_buff->protocol, verifier will fail.
This set contains the verifier change to permit such loads for
certain ctx fields as well as the new test cases in selftests/bpf.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>