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

1 files changed, 18 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/bpf_tcp_helpers.h b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
index 029589c008c9..c9f9bdad60c7 100644
--- a/tools/testing/selftests/bpf/bpf_tcp_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_tcp_helpers.h
@@ -12,6 +12,10 @@
 SEC("struct_ops/"#name) \
 BPF_PROG(name, args)
 
+#ifndef SOL_TCP
+#define SOL_TCP 6
+#endif
+
 #define tcp_jiffies32 ((__u32)bpf_jiffies64())
 
 struct sock_common {
@@ -203,6 +207,20 @@ static __always_inline bool tcp_is_cwnd_limited(const struct sock *sk)
 	return !!BPF_CORE_READ_BITFIELD(tp, is_cwnd_limited);
 }
 
+static __always_inline bool tcp_cc_eq(const char *a, const char *b)
+{
+	int i;
+
+	for (i = 0; i < TCP_CA_NAME_MAX; i++) {
+		if (a[i] != b[i])
+			return false;
+		if (!a[i])
+			break;
+	}
+
+	return true;
+}
+
 extern __u32 tcp_slow_start(struct tcp_sock *tp, __u32 acked) __ksym;
 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, __u32 w, __u32 acked) __ksym;