bpf: cgroup: Fix build error without CONFIG_NET

If CONFIG_NET is not set and CONFIG_CGROUP_BPF=y,
gcc building fails:

kernel/bpf/cgroup.o: In function `cg_sockopt_func_proto':
cgroup.c:(.text+0x237e): undefined reference to `bpf_sk_storage_get_proto'
cgroup.c:(.text+0x2394): undefined reference to `bpf_sk_storage_delete_proto'
kernel/bpf/cgroup.o: In function `__cgroup_bpf_run_filter_getsockopt':
(.text+0x2a1f): undefined reference to `lock_sock_nested'
(.text+0x2ca2): undefined reference to `release_sock'
kernel/bpf/cgroup.o: In function `__cgroup_bpf_run_filter_setsockopt':
(.text+0x3006): undefined reference to `lock_sock_nested'
(.text+0x32bb): undefined reference to `release_sock'
Reported-by: Hulk Robot <hulkci@huawei.com>
Suggested-by: Stanislav Fomichev <sdf@fomichev.me>
Fixes: 0d01da6a ("bpf: implement getsockopt and setsockopt hooks")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/cgroup.c

@@ -939,6 +939,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
 }
 EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
 
+#ifdef CONFIG_NET
 static bool __cgroup_bpf_prog_array_is_empty(struct cgroup *cgrp,
 					     enum bpf_attach_type attach_type)
 {
@@ -1120,6 +1121,7 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
 	return ret;
 }
 EXPORT_SYMBOL(__cgroup_bpf_run_filter_getsockopt);
+#endif
 
 static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
 			      size_t *lenp)
@@ -1386,10 +1388,12 @@ static const struct bpf_func_proto *
 cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
 	switch (func_id) {
+#ifdef CONFIG_NET
 	case BPF_FUNC_sk_storage_get:
 		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_proto;
+#endif
 #ifdef CONFIG_INET
 	case BPF_FUNC_tcp_sock:
 		return &bpf_tcp_sock_proto;