[RFC PATCH bpf-next 5/9] selftests/bpf: fib_lookup: Add IPv4 output route tests
From: Ido Schimmel <idosch@nvidia.com>
Date: 2026-02-26 08:01:30
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds
When the BPF_FIB_LOOKUP_OUTPUT flag is passed to the bpf_fib_lookup() helper the expectation is that the helper will resolve the most specific route whose nexthop device matches the specified ifindex. This is useful when we already know the nexthop device, but need the helper to resolve the destination MAC. Add test cases to test this behavior. To that end, configure two identical routes that differ in their metric and nexthop device and test that the correct route is resolved each time. Also test the scenario where a matching route for the destination address exists, but with the wrong nexthop device. Expect the helper to return an error. Reviewed-by: Petr Machata <petrm@nvidia.com> Signed-off-by: Ido Schimmel <idosch@nvidia.com> --- .../selftests/bpf/prog_tests/fib_lookup.c | 37 +++++++++++++++++++ 1 file changed, 37 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/fib_lookup.c b/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
index 0541fd982e63..6ceeecbdca43 100644
--- a/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/fib_lookup.c@@ -43,6 +43,8 @@ #define DMAC_INIT2 { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, } #define IFINDEX_VETH1 10010 #define IFINDEX_VETH2 10020 +#define IPV4_OUTPUT_NET "192.0.2.0" +#define IPV4_OUTPUT_DST "192.0.2.1" struct fib_lookup_test { const char *desc;
@@ -146,6 +148,35 @@ static const struct fib_lookup_test tests[] = { .expected_dst = IPV6_GW1, .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH, .mark = MARK, }, + /* output routes */ + { .desc = "IPv4 output route, without source, via first device", + .daddr = IPV4_OUTPUT_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS, + .lookup_flags = BPF_FIB_LOOKUP_OUTPUT | BPF_FIB_LOOKUP_SRC, + .dmac = DMAC_INIT, .ifindex = IFINDEX_VETH1, + .expected_ifindex = IFINDEX_VETH1, }, + { .desc = "IPv4 output route, without source, via second device", + .daddr = IPV4_OUTPUT_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS, + .lookup_flags = BPF_FIB_LOOKUP_OUTPUT | BPF_FIB_LOOKUP_SRC, + .dmac = DMAC_INIT2, .ifindex = IFINDEX_VETH2, + .expected_ifindex = IFINDEX_VETH2, }, + { .desc = "IPv4 output route, with source, via first device", + .daddr = IPV4_OUTPUT_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS, + .lookup_flags = BPF_FIB_LOOKUP_OUTPUT, .dmac = DMAC_INIT, + .ifindex = IFINDEX_VETH1, .expected_ifindex = IFINDEX_VETH1, }, + { .desc = "IPv4 output route, with source, via second device", + .daddr = IPV4_OUTPUT_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS, + .lookup_flags = BPF_FIB_LOOKUP_OUTPUT, .dmac = DMAC_INIT2, + .ifindex = IFINDEX_VETH2, .expected_ifindex = IFINDEX_VETH2, }, + { .desc = "IPv4 output route, oif match", + .daddr = IPV4_NUD_STALE_ADDR, + .expected_ret = BPF_FIB_LKUP_RET_SUCCESS, + .lookup_flags = BPF_FIB_LOOKUP_OUTPUT | BPF_FIB_LOOKUP_SKIP_NEIGH, + .ifindex = IFINDEX_VETH1, .expected_ifindex = IFINDEX_VETH1, }, + { .desc = "IPv4 output route, oif mismatch", + .daddr = IPV4_NUD_STALE_ADDR, + .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED, + .lookup_flags = BPF_FIB_LOOKUP_OUTPUT | BPF_FIB_LOOKUP_SKIP_NEIGH, + .ifindex = IFINDEX_VETH2, }, }; static int setup_netns(void)
@@ -217,6 +248,12 @@ static int setup_netns(void) SYS(fail, "ip rule add prio 2 fwmark %d lookup %s", MARK, MARK_TABLE); SYS(fail, "ip -6 rule add prio 2 fwmark %d lookup %s", MARK, MARK_TABLE); + /* Setup for output route tests */ + SYS(fail, "ip route add %s/24 dev veth1 metric 100", IPV4_OUTPUT_NET); + SYS(fail, "ip route add %s/24 dev veth2 metric 200", IPV4_OUTPUT_NET); + SYS(fail, "ip neigh add %s dev veth1 lladdr %s nud perm", IPV4_OUTPUT_DST, DMAC); + SYS(fail, "ip neigh add %s dev veth2 lladdr %s nud perm", IPV4_OUTPUT_DST, DMAC2); + return 0; fail: return -1;
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2.53.0