UPSTREAM: bpf: Move skb->len == 0 checks into __bpf_redirect

[ Upstream commit 114039b342014680911c35bd6b72624180fd669a ]

To avoid potentially breaking existing users.

Both mac/no-mac cases have to be amended; mac_header >= network_header
is not enough (verified with a new test, see next patch).

Fixes: fd1894224407 ("bpf: Don't redirect packets with invalid pkt_len")
Change-Id: I7f16f664a202d1f962bd9e2d8d8e60064f62ef4f
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221121180340.1983627-1-sdf@google.com


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>