Re: [PATCH bpf v2 2/2] selftests/bpf: Add BPF_FIB_LOOKUP_SET_SRC tests

Martin KaFai Lau <martin.lau@xxxxxxxxx> · Wed, 4 Oct 2023 15:02:45 -0700

On 10/3/23 12:10 AM, Martynas Pumputis wrote:
This patch extends the existing fib_lookup test suite by adding two test
cases (for each IP family):

* Test source IP selection when default route is used.

It will be helpful to reword "default route". I was looking in the patch for a 
new route addition like "default via xxx". I think the test is reusing the 
existing prefix route "/24" and "/64".  This is to test the address selection 
from the dev.

* Test source IP selection when an IP route has a preferred src IP addr.

Signed-off-by: Martynas Pumputis <m@xxxxxxxxx>
---
  .../selftests/bpf/prog_tests/fib_lookup.c     | 76 +++++++++++++++++--
  1 file changed, 70 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/fib_lookup.c b/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
index 2fd05649bad1..1b0ab1dbd4f1 100644
--- a/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
@@ -11,9 +11,13 @@
  
  #define NS_TEST			"fib_lookup_ns"
  #define IPV6_IFACE_ADDR		"face::face"
+#define IPV6_IFACE_ADDR_SEC	"cafe::cafe"

SEC stands for secondary?

+#define IPV6_ADDR_DST		"face::3"
  #define IPV6_NUD_FAILED_ADDR	"face::1"
  #define IPV6_NUD_STALE_ADDR	"face::2"
  #define IPV4_IFACE_ADDR		"10.0.0.254"
+#define IPV4_IFACE_ADDR_SEC	"10.1.0.254"
+#define IPV4_ADDR_DST		"10.2.0.254"
  #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"
@@ -31,6 +35,8 @@ struct fib_lookup_test {
  	const char *desc;
  	const char *daddr;
  	int expected_ret;
+	const char *expected_ipv4_src;
+	const char *expected_ipv6_src;

Instead of two members, can it be one "expected_src" member which is v4/v6 
agnoastic (similar to the "daddr" above)? The logic needs to be a little smarter 
for one time but the future test additions will be easier and less error prone.

  	int lookup_flags;
  	__u32 tbid;
  	__u8 dmac[6];
@@ -69,6 +75,22 @@ static const struct fib_lookup_test tests[] = {
  	  .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, },
+	{ .desc = "IPv4 set src addr",
+	  .daddr = IPV4_NUD_FAILED_ADDR, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+	  .expected_ipv4_src = IPV4_IFACE_ADDR,
+	  .lookup_flags = BPF_FIB_LOOKUP_SET_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
+	{ .desc = "IPv6 set src addr",
+	  .daddr = IPV6_NUD_FAILED_ADDR, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+	  .expected_ipv6_src = IPV6_IFACE_ADDR,
+	  .lookup_flags = BPF_FIB_LOOKUP_SET_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
+	{ .desc = "IPv4 set prefsrc addr from route",
+	  .daddr = IPV4_ADDR_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+	  .expected_ipv4_src = IPV4_IFACE_ADDR_SEC,
+	  .lookup_flags = BPF_FIB_LOOKUP_SET_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
+	{ .desc = "IPv6 set prefsrc addr route",
+	  .daddr = IPV6_ADDR_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+	  .expected_ipv6_src = IPV6_IFACE_ADDR_SEC,
+	  .lookup_flags = BPF_FIB_LOOKUP_SET_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
  };
  
  static int ifindex;
@@ -97,6 +119,13 @@ 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 prefsrc IP addr selection */
+	SYS(fail, "ip addr add %s/24 dev veth1", IPV4_IFACE_ADDR_SEC);
+	SYS(fail, "ip route add %s/32 dev veth1 src %s", IPV4_ADDR_DST, IPV4_IFACE_ADDR_SEC);
+
+	SYS(fail, "ip addr add %s/64 dev veth1 nodad", IPV6_IFACE_ADDR_SEC);
+	SYS(fail, "ip route add %s/128 dev veth1 src %s", IPV6_ADDR_DST, IPV6_IFACE_ADDR_SEC);
+
  	/* 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);
@@ -133,9 +162,12 @@ static int set_lookup_params(struct bpf_fib_lookup *params, const struct fib_loo
  
  	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)"))
-			return -1;
+		if (!(test->lookup_flags & BPF_FIB_LOOKUP_SET_SRC)) {
+			ret = inet_pton(AF_INET6, IPV6_IFACE_ADDR, params->ipv6_src);
+			if (!ASSERT_EQ(ret, 1, "inet_pton(IPV6_IFACE_ADDR)"))
+				return -1;
+		}
+
  		return 0;
  	}
  
@@ -143,9 +175,12 @@ static int set_lookup_params(struct bpf_fib_lookup *params, const struct fib_loo
  	if (!ASSERT_EQ(ret, 1, "convert IP[46] address"))
  		return -1;
  	params->family = AF_INET;
-	ret = inet_pton(AF_INET, IPV4_IFACE_ADDR, &params->ipv4_src);
-	if (!ASSERT_EQ(ret, 1, "inet_pton(IPV4_IFACE_ADDR)"))
-		return -1;
+
+	if (!(test->lookup_flags & BPF_FIB_LOOKUP_SET_SRC)) {
+		ret = inet_pton(AF_INET, IPV4_IFACE_ADDR, &params->ipv4_src);
+		if (!ASSERT_EQ(ret, 1, "inet_pton(IPV4_IFACE_ADDR)"))
+			return -1;
+	}
  
  	return 0;
  }
@@ -207,6 +242,35 @@ void test_fib_lookup(void)
  		ASSERT_EQ(skel->bss->fib_lookup_ret, tests[i].expected_ret,
  			  "fib_lookup_ret");
  
+		if (tests[i].expected_ipv4_src) {
+			__be32 expected_ipv4_src;
+
+			ret = inet_pton(AF_INET, tests[i].expected_ipv4_src,
+					&expected_ipv4_src);
+			ASSERT_EQ(ret, 1, "inet_pton(expected_ipv4_src)");
+
+			ASSERT_EQ(fib_params->ipv4_src, expected_ipv4_src,
+			  "fib_lookup ipv4 src");
+		}
+		if (tests[i].expected_ipv6_src) {
+			__u32 expected_ipv6_src[4];
+
+			ret = inet_pton(AF_INET6, tests[i].expected_ipv6_src,
+					expected_ipv6_src);
+			ASSERT_EQ(ret, 1, "inet_pton(expected_ipv6_src)");
+
+			ret = memcmp(expected_ipv6_src, fib_params->ipv6_src,
+				     sizeof(fib_params->ipv6_src));
+			if (!ASSERT_EQ(ret, 0, "fib_lookup ipv6 src")) {
+				char src_ip6[64];
+
+				inet_ntop(AF_INET6, fib_params->ipv6_src, src_ip6,
+					  sizeof(src_ip6));
+				printf("ipv6 expected %s actual %s ",
+				       tests[i].expected_ipv6_src, src_ip6);
+			}
+		}

nit. Move the v4/v6 expected_src comparison to a static function, potentially 
done in a v4/v6 agnostic way mentioned in the above expected_ipv[46]_src comment.


+
  		ret = memcmp(tests[i].dmac, fib_params->dmac, sizeof(tests[i].dmac));
  		if (!ASSERT_EQ(ret, 0, "dmac not match")) {
  			char expected[18], actual[18];








