Subject: Re: [PATCH v1 bpf-next 2/2] selftests/bpf: Add BPF_FIB_LOOKUP_MARK tests

From: Martin KaFai Lau <[email-masked]>
Date: Sat, 23 Mar 2024 15:34:10 -0700

On 3/22/24 7:02 AM, Anton Protopopov wrote:
> This patch extends the fib_lookup test suite by adding a few test
> cases for each IP family to test the new BPF_FIB_LOOKUP_MARK flag
> to the bpf_fib_lookup:
> 
>    * Test destination IP address selection with and without a mark
>      and/or the BPF_FIB_LOOKUP_MARK flag set
> 
> To test this functionality another network namespace and a new veth
> pair were added to the test.
> 

[ ... ]

>   static const struct fib_lookup_test tests[] = {
> @@ -90,10 +105,47 @@ static const struct fib_lookup_test tests[] = {
>   	  .daddr = IPV6_ADDR_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
>   	  .expected_src = IPV6_IFACE_ADDR_SEC,
>   	  .lookup_flags = BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH, },
> +	/* policy routing */
> +	{ .desc = "IPv4 policy routing, default",
> +	  .daddr = IPV4_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV4_GW1, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_MARK | BPF_FIB_LOOKUP_SKIP_NEIGH, },
> +	{ .desc = "IPv4 policy routing, mark doesn't point to a policy",
> +	  .daddr = IPV4_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV4_GW1, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_MARK | BPF_FIB_LOOKUP_SKIP_NEIGH,
> +	  .mark = MARK_NO_POLICY, },
> +	{ .desc = "IPv4 policy routing, mark points to a policy",
> +	  .daddr = IPV4_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV4_GW2, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_MARK | BPF_FIB_LOOKUP_SKIP_NEIGH,
> +	  .mark = MARK, },
> +	{ .desc = "IPv4 policy routing, mark points to a policy, but no flag",
> +	  .daddr = IPV4_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV4_GW1, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH,
> +	  .mark = MARK, },
> +	{ .desc = "IPv6 policy routing, default",
> +	  .daddr = IPV6_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV6_GW1, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_MARK | BPF_FIB_LOOKUP_SKIP_NEIGH, },
> +	{ .desc = "IPv6 policy routing, mark doesn't point to a policy",
> +	  .daddr = IPV6_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV6_GW1, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_MARK | BPF_FIB_LOOKUP_SKIP_NEIGH,
> +	  .mark = MARK_NO_POLICY, },
> +	{ .desc = "IPv6 policy routing, mark points to a policy",
> +	  .daddr = IPV6_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV6_GW2, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_MARK | BPF_FIB_LOOKUP_SKIP_NEIGH,
> +	  .mark = MARK, },
> +	{ .desc = "IPv6 policy routing, mark points to a policy, but no flag",
> +	  .daddr = IPV6_REMOTE_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
> +	  .expected_dst = IPV6_GW1, .ifname = "veth3",
> +	  .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH,
> +	  .mark = MARK, },
>   };
>   
> -static int ifindex;
> -
>   static int setup_netns(void)
>   {
>   	int err;
> @@ -144,12 +196,40 @@ static int setup_netns(void)
>   	if (!ASSERT_OK(err, "write_sysctl(net.ipv6.conf.veth1.forwarding)"))
>   		goto fail;
>   
> +	/* Setup for policy routing tests */
> +	SYS(fail, "ip link add veth3 type veth peer name veth4");
> +	SYS(fail, "ip link set dev veth3 up");
> +	SYS(fail, "ip link set dev veth4 netns %s up", NS_REMOTE);
> +
> +	SYS(fail, "ip addr add %s/24 dev veth3", IPV4_LOCAL);
> +	SYS(fail, "ip netns exec %s ip addr add %s/24 dev veth4", NS_REMOTE, IPV4_GW1);
> +	SYS(fail, "ip netns exec %s ip addr add %s/24 dev veth4", NS_REMOTE, IPV4_GW2);
> +	SYS(fail, "ip addr add %s/64 dev veth3 nodad", IPV6_LOCAL);
> +	SYS(fail, "ip netns exec %s ip addr add %s/64 dev veth4 nodad", NS_REMOTE, IPV6_GW1);
> +	SYS(fail, "ip netns exec %s ip addr add %s/64 dev veth4 nodad", NS_REMOTE, IPV6_GW2);

Trying to see if the setup can be simplified.

Does it need to add another netns and setup a reachable IPV[46]_GW[12] gateway?

The test is not sending any traffic and it is a BPF_FIB_LOOKUP_SKIP_NEIGH test.

> +	SYS(fail, "ip route add %s/32 via %s", IPV4_REMOTE_DST, IPV4_GW1);
> +	SYS(fail, "ip route add %s/32 via %s table %s", IPV4_REMOTE_DST, IPV4_GW2, MARK_TABLE);
> +	SYS(fail, "ip -6 route add %s/128 via %s", IPV6_REMOTE_DST, IPV6_GW1);
> +	SYS(fail, "ip -6 route add %s/128 via %s table %s", IPV6_REMOTE_DST, IPV6_GW2, MARK_TABLE);
> +	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);
> +
> +	err = write_sysctl("/proc/sys/net/ipv4/conf/veth3/forwarding", "1");
> +	if (!ASSERT_OK(err, "write_sysctl(net.ipv4.conf.veth3.forwarding)"))
> +		goto fail;
> +
> +	err = write_sysctl("/proc/sys/net/ipv6/conf/veth3/forwarding", "1");
> +	if (!ASSERT_OK(err, "write_sysctl(net.ipv6.conf.veth3.forwarding)"))
> +		goto fail;
> +
>   	return 0;
>   fail:
>   	return -1;
>   }

[ ... ]

> @@ -248,6 +337,7 @@ void test_fib_lookup(void)
>   	prog_fd = bpf_program__fd(skel->progs.fib_lookup);
>   
>   	SYS(fail, "ip netns add %s", NS_TEST);
> +	SYS(fail, "ip netns add %s", NS_REMOTE);