selftests/bpf: Add netkit to tc_redirect selftest

Extend the existing tc_redirect selftest to also cover netkit devices
for exercising the bpf_redirect_peer() code paths, so that we have both
veth as well as netkit covered, all tests still pass after this change.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/20231114004220.6495-9-daniel@iogearbox.netSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/testing/selftests/bpf/prog_tests/tc_redirect.c

@@ -24,6 +24,7 @@
 
 #include "test_progs.h"
 #include "network_helpers.h"
+#include "netlink_helpers.h"
 #include "test_tc_neigh_fib.skel.h"
 #include "test_tc_neigh.skel.h"
 #include "test_tc_peer.skel.h"
@@ -112,6 +113,7 @@ static void netns_setup_namespaces_nofail(const char *verb)
 
 enum dev_mode {
 	MODE_VETH,
+	MODE_NETKIT,
 };
 
 struct netns_setup_result {
@@ -142,10 +144,51 @@ static int get_ifaddr(const char *name, char *ifaddr)
 	return 0;
 }
 
+static int create_netkit(int mode, char *prim, char *peer)
+{
+	struct rtattr *linkinfo, *data, *peer_info;
+	struct rtnl_handle rth = { .fd = -1 };
+	const char *type = "netkit";
+	struct {
+		struct nlmsghdr n;
+		struct ifinfomsg i;
+		char buf[1024];
+	} req = {};
+	int err;
+
+	err = rtnl_open(&rth, 0);
+	if (!ASSERT_OK(err, "open_rtnetlink"))
+		return err;
+
+	memset(&req, 0, sizeof(req));
+	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+	req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL;
+	req.n.nlmsg_type = RTM_NEWLINK;
+	req.i.ifi_family = AF_UNSPEC;
+
+	addattr_l(&req.n, sizeof(req), IFLA_IFNAME, prim, strlen(prim));
+	linkinfo = addattr_nest(&req.n, sizeof(req), IFLA_LINKINFO);
+	addattr_l(&req.n, sizeof(req), IFLA_INFO_KIND, type, strlen(type));
+	data = addattr_nest(&req.n, sizeof(req), IFLA_INFO_DATA);
+	addattr32(&req.n, sizeof(req), IFLA_NETKIT_MODE, mode);
+	peer_info = addattr_nest(&req.n, sizeof(req), IFLA_NETKIT_PEER_INFO);
+	req.n.nlmsg_len += sizeof(struct ifinfomsg);
+	addattr_l(&req.n, sizeof(req), IFLA_IFNAME, peer, strlen(peer));
+	addattr_nest_end(&req.n, peer_info);
+	addattr_nest_end(&req.n, data);
+	addattr_nest_end(&req.n, linkinfo);
+
+	err = rtnl_talk(&rth, &req.n, NULL);
+	ASSERT_OK(err, "talk_rtnetlink");
+	rtnl_close(&rth);
+	return err;
+}
+
 static int netns_setup_links_and_routes(struct netns_setup_result *result)
 {
 	struct nstoken *nstoken = NULL;
 	char src_fwd_addr[IFADDR_STR_LEN+1] = {};
+	int err;
 
 	if (result->dev_mode == MODE_VETH) {
 		SYS(fail, "ip link add src type veth peer name src_fwd");
@@ -153,6 +196,13 @@ static int netns_setup_links_and_routes(struct netns_setup_result *result)
 
 		SYS(fail, "ip link set dst_fwd address " MAC_DST_FWD);
 		SYS(fail, "ip link set dst address " MAC_DST);
+	} else if (result->dev_mode == MODE_NETKIT) {
+		err = create_netkit(NETKIT_L3, "src", "src_fwd");
+		if (!ASSERT_OK(err, "create_ifindex_src"))
+			goto fail;
+		err = create_netkit(NETKIT_L3, "dst", "dst_fwd");
+		if (!ASSERT_OK(err, "create_ifindex_dst"))
+			goto fail;
 	}
 
 	if (get_ifaddr("src_fwd", src_fwd_addr))
@@ -1134,7 +1184,9 @@ static void *test_tc_redirect_run_tests(void *arg)
 	netns_setup_namespaces_nofail("delete");
 
 	RUN_TEST(tc_redirect_peer, MODE_VETH);
+	RUN_TEST(tc_redirect_peer, MODE_NETKIT);
 	RUN_TEST(tc_redirect_peer_l3, MODE_VETH);
+	RUN_TEST(tc_redirect_peer_l3, MODE_NETKIT);
 	RUN_TEST(tc_redirect_neigh, MODE_VETH);
 	RUN_TEST(tc_redirect_neigh_fib, MODE_VETH);
 	RUN_TEST(tc_redirect_dtime, MODE_VETH);