selftests/bpf: Test table ID fib lookup BPF helper

Add additional test cases to `fib_lookup.c` prog_test.

These test cases add a new /24 network to the previously unused veth2
device, removes the directly connected route from the main routing table
and moves it to table 100.

The first test case then confirms a fib lookup for a remote address in
this directly connected network, using the main routing table fails.

The second test case ensures the same fib lookup using table 100 succeeds.

An additional pair of tests which function in the same manner are added
for IPv6.
Signed-off-by: Louis DeLosSantos <louis.delos.devel@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230505-bpf-add-tbid-fib-lookup-v2-2-0a31c22c748c@gmail.com

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

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
 
+#include <linux/rtnetlink.h>
 #include <sys/types.h>
 #include <net/if.h>
 
@@ -15,14 +16,23 @@
 #define IPV4_IFACE_ADDR		"10.0.0.254"
 #define IPV4_NUD_FAILED_ADDR	"10.0.0.1"
 #define IPV4_NUD_STALE_ADDR	"10.0.0.2"
+#define IPV4_TBID_ADDR		"172.0.0.254"
+#define IPV4_TBID_NET		"172.0.0.0"
+#define IPV4_TBID_DST		"172.0.0.2"
+#define IPV6_TBID_ADDR		"fd00::FFFF"
+#define IPV6_TBID_NET		"fd00::"
+#define IPV6_TBID_DST		"fd00::2"
 #define DMAC			"11:11:11:11:11:11"
 #define DMAC_INIT { 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, }
+#define DMAC2			"01:01:01:01:01:01"
+#define DMAC_INIT2 { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, }
 
 struct fib_lookup_test {
 	const char *desc;
 	const char *daddr;
 	int expected_ret;
 	int lookup_flags;
+	__u32 tbid;
 	__u8 dmac[6];
 };
 
@@ -43,6 +53,22 @@ static const struct fib_lookup_test tests[] = {
 	{ .desc = "IPv4 skip neigh",
 	  .daddr = IPV4_NUD_FAILED_ADDR, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
 	  .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH, },
+	{ .desc = "IPv4 TBID lookup failure",
+	  .daddr = IPV4_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+	  .lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID,
+	  .tbid = RT_TABLE_MAIN, },
+	{ .desc = "IPv4 TBID lookup success",
+	  .daddr = IPV4_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+	  .lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID, .tbid = 100,
+	  .dmac = DMAC_INIT2, },
+	{ .desc = "IPv6 TBID lookup failure",
+	  .daddr = IPV6_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+	  .lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID,
+	  .tbid = RT_TABLE_MAIN, },
+	{ .desc = "IPv6 TBID lookup success",
+	  .daddr = IPV6_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+	  .lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID, .tbid = 100,
+	  .dmac = DMAC_INIT2, },
 };
 
 static int ifindex;
@@ -53,6 +79,7 @@ static int setup_netns(void)
 
 	SYS(fail, "ip link add veth1 type veth peer name veth2");
 	SYS(fail, "ip link set dev veth1 up");
+	SYS(fail, "ip link set dev veth2 up");
 
 	err = write_sysctl("/proc/sys/net/ipv4/neigh/veth1/gc_stale_time", "900");
 	if (!ASSERT_OK(err, "write_sysctl(net.ipv4.neigh.veth1.gc_stale_time)"))
@@ -70,6 +97,17 @@ static int setup_netns(void)
 	SYS(fail, "ip neigh add %s dev veth1 nud failed", IPV4_NUD_FAILED_ADDR);
 	SYS(fail, "ip neigh add %s dev veth1 lladdr %s nud stale", IPV4_NUD_STALE_ADDR, DMAC);
 
+	/* Setup for tbid lookup tests */
+	SYS(fail, "ip addr add %s/24 dev veth2", IPV4_TBID_ADDR);
+	SYS(fail, "ip route del %s/24 dev veth2", IPV4_TBID_NET);
+	SYS(fail, "ip route add table 100 %s/24 dev veth2", IPV4_TBID_NET);
+	SYS(fail, "ip neigh add %s dev veth2 lladdr %s nud stale", IPV4_TBID_DST, DMAC2);
+
+	SYS(fail, "ip addr add %s/64 dev veth2", IPV6_TBID_ADDR);
+	SYS(fail, "ip -6 route del %s/64 dev veth2", IPV6_TBID_NET);
+	SYS(fail, "ip -6 route add table 100 %s/64 dev veth2", IPV6_TBID_NET);
+	SYS(fail, "ip neigh add %s dev veth2 lladdr %s nud stale", IPV6_TBID_DST, DMAC2);
+
 	err = write_sysctl("/proc/sys/net/ipv4/conf/veth1/forwarding", "1");
 	if (!ASSERT_OK(err, "write_sysctl(net.ipv4.conf.veth1.forwarding)"))
 		goto fail;
@@ -83,7 +121,7 @@ static int setup_netns(void)
 	return -1;
 }
 
-static int set_lookup_params(struct bpf_fib_lookup *params, const char *daddr)
+static int set_lookup_params(struct bpf_fib_lookup *params, const struct fib_lookup_test *test)
 {
 	int ret;
 
@@ -91,8 +129,9 @@ static int set_lookup_params(struct bpf_fib_lookup *params, const char *daddr)
 
 	params->l4_protocol = IPPROTO_TCP;
 	params->ifindex = ifindex;
+	params->tbid = test->tbid;
 
-	if (inet_pton(AF_INET6, daddr, params->ipv6_dst) == 1) {
+	if (inet_pton(AF_INET6, test->daddr, params->ipv6_dst) == 1) {
 		params->family = AF_INET6;
 		ret = inet_pton(AF_INET6, IPV6_IFACE_ADDR, params->ipv6_src);
 		if (!ASSERT_EQ(ret, 1, "inet_pton(IPV6_IFACE_ADDR)"))
@@ -100,7 +139,7 @@ static int set_lookup_params(struct bpf_fib_lookup *params, const char *daddr)
 		return 0;
 	}
 
-	ret = inet_pton(AF_INET, daddr, &params->ipv4_dst);
+	ret = inet_pton(AF_INET, test->daddr, &params->ipv4_dst);
 	if (!ASSERT_EQ(ret, 1, "convert IP[46] address"))
 		return -1;
 	params->family = AF_INET;
@@ -154,13 +193,12 @@ void test_fib_lookup(void)
 	fib_params = &skel->bss->fib_params;
 
 	for (i = 0; i < ARRAY_SIZE(tests); i++) {
-		printf("Testing %s\n", tests[i].desc);
+		printf("Testing %s ", tests[i].desc);
 
-		if (set_lookup_params(fib_params, tests[i].daddr))
+		if (set_lookup_params(fib_params, &tests[i]))
 			continue;
 		skel->bss->fib_lookup_ret = -1;
-		skel->bss->lookup_flags = BPF_FIB_LOOKUP_OUTPUT |
-			tests[i].lookup_flags;
+		skel->bss->lookup_flags = tests[i].lookup_flags;
 
 		err = bpf_prog_test_run_opts(prog_fd, &run_opts);
 		if (!ASSERT_OK(err, "bpf_prog_test_run_opts"))
@@ -175,7 +213,14 @@ void test_fib_lookup(void)
 
 			mac_str(expected, tests[i].dmac);
 			mac_str(actual, fib_params->dmac);
-			printf("dmac expected %s actual %s\n", expected, actual);
+			printf("dmac expected %s actual %s ", expected, actual);
+		}
+
+		// ensure tbid is zero'd out after fib lookup.
+		if (tests[i].lookup_flags & BPF_FIB_LOOKUP_DIRECT) {
+			if (!ASSERT_EQ(skel->bss->fib_params.tbid, 0,
+					"expected fib_params.tbid to be zero"))
+				goto fail;
 		}
 	}