bpf: Allow use of skc_to_mptcp_sock in cg_sockopt

Currently, bpf_skc_to_mptcp_sock() helper is not allowed to be used
in cg_sockopt. This patch adds this permission.

Signed-off-by: Geliang Tang <[email protected]>

Author: Geliang Tang

kernel/bpf/cgroup.c

@@ -2358,6 +2358,8 @@ cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 #ifdef CONFIG_INET
 	case BPF_FUNC_tcp_sock:
 		return &bpf_tcp_sock_proto;
+	case BPF_FUNC_skc_to_mptcp_sock:
+		return &bpf_skc_to_mptcp_sock_proto;
 #endif
 	case BPF_FUNC_perf_event_output:
 		return &bpf_event_output_data_proto;