[PATCH bpf v2 4/4] selftests/bpf: Add netkit test for pkt_type

Daniel Borkmann
2024-05-24T16:36:25Z

Add a test case to assert that the skb->pkt_type which was set from the BPF
program is retained from the netkit xmit side to the peer's device at tcx
ingress location.

# ./vmtest.sh -- ./test_progs -t netkit
[...]
./test_progs -t netkit
[ 1.140780] bpf_testmod: loading out-of-tree module taints kernel.
[ 1.141127] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
[ 1.284601] tsc: Refined TSC clocksource calibration: 3408.006 MHz
[ 1.286672] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fd9b189d, max_idle_ns: 440795225691 ns
[ 1.290384] clocksource: Switched to clocksource tsc
#345 tc_netkit_basic:OK
#346 tc_netkit_device:OK
#347 tc_netkit_multi_links:OK
#348 tc_netkit_multi_opts:OK
#349 tc_netkit_neigh_links:OK
#350 tc_netkit_pkt_type:OK
Summary: 6/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
.../selftests/bpf/prog_tests/tc_netkit.c | 84 +++++++++++++++++++
.../selftests/bpf/progs/test_tc_link.c | 33 ++++++++
2 files changed, 117 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/tc_netkit.c b/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
index 18b2e969a456..b9135720024c 100644
--- a/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
+++ b/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
@@ -99,6 +99,16 @@ static int create_netkit(int mode, int policy, int peer_policy, int *ifindex,
return err;
}

+static void move_netkit(void)
+{
+ ASSERT_OK(system("ip link set " netkit_peer " netns foo"),
+ "move peer");
+ ASSERT_OK(system("ip netns exec foo ip link set dev "
+ netkit_peer " up"), "up peer");
+ ASSERT_OK(system("ip netns exec foo ip addr add dev "
+ netkit_peer " 10.0.0.2/24"), "addr peer");
+}
+
static void destroy_netkit(void)
{
ASSERT_OK(system("ip link del dev " netkit_name), "del primary");
@@ -695,3 +705,77 @@ void serial_test_tc_netkit_neigh_links(void)
serial_test_tc_netkit_neigh_links_target(NETKIT_L2, BPF_NETKIT_PRIMARY);
serial_test_tc_netkit_neigh_links_target(NETKIT_L3, BPF_NETKIT_PRIMARY);
}
+
+static void serial_test_tc_netkit_pkt_type_mode(int mode)
+{
+ LIBBPF_OPTS(bpf_netkit_opts, optl_nk);
+ LIBBPF_OPTS(bpf_tcx_opts, optl_tcx);
+ int err, ifindex, ifindex2;
+ struct test_tc_link *skel;
+ struct bpf_link *link;
+
+ err = create_netkit(mode, NETKIT_PASS, NETKIT_PASS,
+ &ifindex, true);
+ if (err)
+ return;
+
+ ifindex2 = if_nametoindex(netkit_peer);
+ ASSERT_NEQ(ifindex, ifindex2, "ifindex_1_2");
+
+ skel = test_tc_link__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ goto cleanup;
+
+ ASSERT_EQ(bpf_program__set_expected_attach_type(skel->progs.tc1,
+ BPF_NETKIT_PRIMARY), 0, "tc1_attach_type");
+ ASSERT_EQ(bpf_program__set_expected_attach_type(skel->progs.tc7,
+ BPF_TCX_INGRESS), 0, "tc7_attach_type");
+
+ err = test_tc_link__load(skel);
+ if (!ASSERT_OK(err, "skel_load"))
+ goto cleanup;
+
+ assert_mprog_count_ifindex(ifindex, BPF_NETKIT_PRIMARY, 0);
+ assert_mprog_count_ifindex(ifindex2, BPF_TCX_INGRESS, 0);
+
+ link = bpf_program__attach_netkit(skel->progs.tc1, ifindex, &optl_nk);
+ if (!ASSERT_OK_PTR(link, "link_attach"))
+ goto cleanup;
+
+ skel->links.tc1 = link;
+
+ assert_mprog_count_ifindex(ifindex, BPF_NETKIT_PRIMARY, 1);
+ assert_mprog_count_ifindex(ifindex2, BPF_TCX_INGRESS, 0);
+
+ link = bpf_program__attach_tcx(skel->progs.tc7, ifindex2, &optl_tcx);
+ if (!ASSERT_OK_PTR(link, "link_attach"))
+ goto cleanup;
+
+ skel->links.tc7 = link;
+
+ assert_mprog_count_ifindex(ifindex, BPF_NETKIT_PRIMARY, 1);
+ assert_mprog_count_ifindex(ifindex2, BPF_TCX_INGRESS, 1);
+
+ move_netkit();
+
+ tc_skel_reset_all_seen(skel);
+ skel->bss->set_type = true;
+ ASSERT_EQ(send_icmp(), 0, "icmp_pkt");
+
+ ASSERT_EQ(skel->bss->seen_tc1, true, "seen_tc1");
+ ASSERT_EQ(skel->bss->seen_tc7, true, "seen_tc7");
+
+ ASSERT_EQ(skel->bss->seen_host, true, "seen_host");
+ ASSERT_EQ(skel->bss->seen_mcast, true, "seen_mcast");
+cleanup:
+ test_tc_link__destroy(skel);
+
+ assert_mprog_count_ifindex(ifindex, BPF_NETKIT_PRIMARY, 0);
+ destroy_netkit();
+}
+
+void serial_test_tc_netkit_pkt_type(void)
+{
+ serial_test_tc_netkit_pkt_type_mode(NETKIT_L2);
+ serial_test_tc_netkit_pkt_type_mode(NETKIT_L3);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_tc_link.c b/tools/testing/selftests/bpf/progs/test_tc_link.c
index 992400acb957..b64fcb70ef2f 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_link.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_link.c
@@ -4,6 +4,7 @@

#include <linux/bpf.h>
#include <linux/if_ether.h>
+#include <linux/if_packet.h>

#include <bpf/bpf_endian.h>
#include <bpf/bpf_helpers.h>
@@ -16,7 +17,13 @@ bool seen_tc3;
bool seen_tc4;
bool seen_tc5;
bool seen_tc6;
+bool seen_tc7;
+
+bool set_type;
+
bool seen_eth;
+bool seen_host;
+bool seen_mcast;

SEC("tc/ingress")
int tc1(struct __sk_buff *skb)
@@ -28,8 +35,16 @@ int tc1(struct __sk_buff *skb)
if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)))
goto out;
seen_eth = eth.h_proto == bpf_htons(ETH_P_IP);
+ seen_host = skb->pkt_type == PACKET_HOST;
+ if (seen_host && set_type) {
+ eth.h_dest[0] = 4;
+ if (bpf_skb_store_bytes(skb, 0, &eth, sizeof(eth), 0))
+ goto fail;
+ bpf_skb_change_type(skb, PACKET_MULTICAST);
+ }
out:
seen_tc1 = true;
+fail:
return TCX_NEXT;
}

@@ -67,3 +82,21 @@ int tc6(struct __sk_buff *skb)
seen_tc6 = true;
return TCX_PASS;
}
+
+SEC("tc/ingress")
+int tc7(struct __sk_buff *skb)
+{
+ struct ethhdr eth = {};
+
+ if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
+ goto out;
+ if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)))
+ goto out;
+ if (eth.h_dest[0] == 4 && set_type) {
+ seen_mcast = skb->pkt_type == PACKET_MULTICAST;
+ bpf_skb_change_type(skb, PACKET_HOST);
+ }
+out:
+ seen_tc7 = true;
+ return TCX_PASS;
+}
--
2.34.1