libbpf: add the capability to specify netlink proto in libbpf_netlink_send_recv

This is a preliminary patch in order to introduce netlink_generic
protocol support to libbpf.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/7878a54667e74afeec3ee519999c044bd514b44c.1675245258.git.lorenzo@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/lib/bpf/netlink.c

@@ -41,7 +41,7 @@ struct xdp_id_md {
 	struct xdp_link_info info;
 };
 
-static int libbpf_netlink_open(__u32 *nl_pid)
+static int libbpf_netlink_open(__u32 *nl_pid, int proto)
 {
 	struct sockaddr_nl sa;
 	socklen_t addrlen;
@@ -51,7 +51,7 @@ static int libbpf_netlink_open(__u32 *nl_pid)
 	memset(&sa, 0, sizeof(sa));
 	sa.nl_family = AF_NETLINK;
 
-	sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
+	sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, proto);
 	if (sock < 0)
 		return -errno;
 
@@ -212,14 +212,14 @@ static int libbpf_netlink_recv(int sock, __u32 nl_pid, int seq,
 }
 
 static int libbpf_netlink_send_recv(struct libbpf_nla_req *req,
-				    __dump_nlmsg_t parse_msg,
+				    int proto, __dump_nlmsg_t parse_msg,
 				    libbpf_dump_nlmsg_t parse_attr,
 				    void *cookie)
 {
 	__u32 nl_pid = 0;
 	int sock, ret;
 
-	sock = libbpf_netlink_open(&nl_pid);
+	sock = libbpf_netlink_open(&nl_pid, proto);
 	if (sock < 0)
 		return sock;
 
@@ -271,7 +271,7 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
 	}
 	nlattr_end_nested(&req, nla);
 
-	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
+	return libbpf_netlink_send_recv(&req, NETLINK_ROUTE, NULL, NULL, NULL);
 }
 
 int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags, const struct bpf_xdp_attach_opts *opts)
@@ -382,7 +382,7 @@ int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts)
 	xdp_id.ifindex = ifindex;
 	xdp_id.flags = xdp_flags;
 
-	err = libbpf_netlink_send_recv(&req, __dump_link_nlmsg,
+	err = libbpf_netlink_send_recv(&req, NETLINK_ROUTE, __dump_link_nlmsg,
 				       get_xdp_info, &xdp_id);
 	if (err)
 		return libbpf_err(err);
@@ -493,7 +493,7 @@ static int tc_qdisc_modify(struct bpf_tc_hook *hook, int cmd, int flags)
 	if (ret < 0)
 		return ret;
 
-	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
+	return libbpf_netlink_send_recv(&req, NETLINK_ROUTE, NULL, NULL, NULL);
 }
 
 static int tc_qdisc_create_excl(struct bpf_tc_hook *hook)
@@ -673,7 +673,8 @@ int bpf_tc_attach(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
 
 	info.opts = opts;
 
-	ret = libbpf_netlink_send_recv(&req, get_tc_info, NULL, &info);
+	ret = libbpf_netlink_send_recv(&req, NETLINK_ROUTE, get_tc_info, NULL,
+				       &info);
 	if (ret < 0)
 		return libbpf_err(ret);
 	if (!info.processed)
@@ -739,7 +740,7 @@ static int __bpf_tc_detach(const struct bpf_tc_hook *hook,
 			return ret;
 	}
 
-	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
+	return libbpf_netlink_send_recv(&req, NETLINK_ROUTE, NULL, NULL, NULL);
 }
 
 int bpf_tc_detach(const struct bpf_tc_hook *hook,
@@ -804,7 +805,8 @@ int bpf_tc_query(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
 
 	info.opts = opts;
 
-	ret = libbpf_netlink_send_recv(&req, get_tc_info, NULL, &info);
+	ret = libbpf_netlink_send_recv(&req, NETLINK_ROUTE, get_tc_info, NULL,
+				       &info);
 	if (ret < 0)
 		return libbpf_err(ret);
 	if (!info.processed)