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: Attempt to build BPF programs with -Wsign-compare

GCC's -Wall includes -Wsign-compare while clang does not.
Since BPF programs are built with clang we need to add this flag explicitly
to catch problematic comparisons like:

int i = -1;
unsigned int j = 1;
if (i < j) // this is false.

long i = -1;
unsigned int j = 1;
if (i < j) // this is true.

C standard for reference:

- If either operand is unsigned long the other shall be converted to unsigned long.

- Otherwise, if one operand is a long int and the other unsigned int, then if a
long int can represent all the values of an unsigned int, the unsigned int
shall be converted to a long int; otherwise both operands shall be converted to
unsigned long int.

- Otherwise, if either operand is long, the other shall be converted to long.

- Otherwise, if either operand is unsigned, the other shall be converted to unsigned.

Unfortunately clang's -Wsign-compare is very noisy.
It complains about (s32)a == (u32)b which is safe and doen't have surprising behavior.

This patch fixes some of the issues. It needs a follow up to fix the rest.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20231226191148.48536-2-alexei.starovoitov@gmail.com

selftests/bpf: Correctly handle optlen > 4096

Even though it's not relevant in selftests, the people
might still copy-paste from them. So let's take care
of optlen > 4096 cases explicitly.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230511170456.1759459-4-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

selftests/bpf: Add tests for {set|get} socket option from setsockopt BPF

Adding selftests for the newly added functionality to call bpf_setsockopt()
and bpf_getsockopt() from setsockopt BPF programs.

Test Details:

1. BPF Program

Checks for changes in IPV6_TCLASS(SOL_IPV6) via setsockopt
If the cca for the socket is not cubic do nothing
If the newly set value for IPV6_TCLASS is 45 (0x2d) (as per our use-case)
then change the cc from cubic to reno

2. User Space Program

Creates an AF_INET6 socket and set the cca for that to be "cubic"
Attach the program and set the IPV6_TCLASS to 0x2d using setsockopt
Verify the cca for the socket changed to reno

Signed-off-by: Prankur Gupta <prankgup@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210817224221.3257826-3-prankgup@fb.com