selftests/bpf: Remove the bpf_tcp_helpers.h usages from other non tcp-cc tests

The patch removes the remaining bpf_tcp_helpers.h usages in the
non tcp-cc networking tests. It either replaces it with bpf_tracing_net.h
or just removed it because the test is not actually using any
kernel sockets. For the later, the missing macro (mainly SOL_TCP) is
defined locally.

An exception is the test_sock_fields which is testing
the "struct bpf_sock" type instead of the kernel sock type.
Whenever "vmlinux.h" is used instead, it hits a verifier
error on doing arithmetic on the sock_common pointer:

; return !a6[0] && !a6[1] && !a6[2] && a6[3] == bpf_htonl(1); @ test_sock_fields.c:54
21: (61) r2 = *(u32 *)(r1 +28) ; R1_w=sock_common() R2_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
22: (56) if w2 != 0x0 goto pc-6 ; R2_w=0
23: (b7) r3 = 28 ; R3_w=28
24: (bf) r2 = r1 ; R1_w=sock_common() R2_w=sock_common()
25: (0f) r2 += r3
R2 pointer arithmetic on sock_common prohibited

Hence, instead of including bpf_tracing_net.h, the test_sock_fields test
defines a tcp_sock with one lsndtime field in it.

Another highlight is, in sockopt_qos_to_cc.c, the tcp_cc_eq()
is replaced by bpf_strncmp(). tcp_cc_eq() was a workaround
in bpf_tcp_helpers.h before bpf_strncmp had been added.

The SOL_IPV6 addition to bpf_tracing_net.h is needed by the
test_tcpbpf_kern test.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240509175026.3423614-10-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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

bpf: selftest: Add test_btf_skc_cls_ingress

This patch attaches a classifier prog to the ingress filter.
It exercises the following helpers with different socket pointer
types in different logical branches:
1. bpf_sk_release()
2. bpf_sk_assign()
3. bpf_skc_to_tcp_request_sock(), bpf_skc_to_tcp_sock()
4. bpf_tcp_gen_syncookie, bpf_tcp_check_syncookie

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200925000458.3859627-1-kafai@fb.com