selftests/bpf: fix lots of silly mistakes pointed out by compiler

Once we enable -Wall for BPF sources, compiler will complain about lots
of unused variables, variables that are set but never read, etc.

Fix all these issues first before enabling -Wall in Makefile.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Fix sk_assign on s390x

sk_assign is failing on an s390x machine running Debian "bookworm" for
2 reasons: legacy server_map definition and uninitialized addrlen in
recvfrom() call.

Fix by adding a new-style server_map definition and dropping addrlen
(recvfrom() allows NULL values for src_addr and addrlen).

Since the test should support tc built without libbpf, build the prog
twice: with the old-style definition and with the new-style definition,
then select the right one at runtime. This could be done at compile
time too, but this would not be cross-compilation friendly.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230129190501.1624747-2-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Remove unused variable from bpf_sk_assign test

Was never used in bpf_sk_assign_test(), and was removed from handle_{tcp,udp}()
in commit 0b9ad56b1ea6 ("selftests/bpf: Use SOCKMAP for server sockets in
bpf_sk_assign test").

Fixes: 0b9ad56b1ea6 ("selftests/bpf: Use SOCKMAP for server sockets in bpf_sk_assign test")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220329154914.3718658-1-eyal.birger@gmail.com

selftests/bpf: Switch SEC("classifier*") usage to a strict SEC("tc")

Convert all SEC("classifier*") uses to a new and strict SEC("tc")
section name. In reference_tracking selftests switch from ambiguous
searching by program title (section name) to non-ambiguous searching by
name in some selftests, getting closer to completely removing
bpf_object__find_program_by_title().

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-4-andrii@kernel.org

selftests/bpf: Use SOCKMAP for server sockets in bpf_sk_assign test

Update bpf_sk_assign test to fetch the server socket from SOCKMAP, now that
map lookup from BPF in SOCKMAP is enabled. This way the test TC BPF program
doesn't need to know what address server socket is bound to.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200429181154.479310-4-jakub@cloudflare.com

selftests: bpf: Extend sk_assign tests for UDP

Add support for testing UDP sk_assign to the existing tests.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Lorenz Bauer <lmb@cloudflare.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-6-joe@wand.net.nz

selftests: bpf: Add test for sk_assign

Attach a tc direct-action classifier to lo in a fresh network
namespace, and rewrite all connection attempts to localhost:4321
to localhost:1234 (for port tests) and connections to unreachable
IPv4/IPv6 IPs to the local socket (for address tests). Includes
implementations for both TCP and UDP.

Keep in mind that both client to server and server to client traffic
passes the classifier.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-5-joe@wand.net.nz

Co-authored-by: Joe Stringer <joe@wand.net.nz>