selftests/bpf: Verify skb metadata in BPF instead of userspace

Move metadata verification into the BPF TC programs. Previously,
userspace read metadata from a map and verified it once at test end.

Now TC programs compare metadata directly using __builtin_memcmp() and
set a test_pass flag. This enables verification at multiple points during
test execution rather than a single final check.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20251105-skb-meta-rx-path-v4-10-5ceb08a9b37b@cloudflare.com

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
index 178292d1251a1082b34f7fd38d12047344a1277e..93a1fbe6a4fdb7a94bbc04f6ff1887b07d0da537 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
@@ -171,33 +171,6 @@ static int write_test_packet(int tap_fd)
        return 0;
 }
 
-static void assert_test_result(const struct bpf_map *result_map)
-{
-       int err;
-       __u32 map_key = 0;
-       __u8 map_value[TEST_PAYLOAD_LEN];
-
-       err = bpf_map__lookup_elem(result_map, &map_key, sizeof(map_key),
-                                  &map_value, TEST_PAYLOAD_LEN, BPF_ANY);
-       if (!ASSERT_OK(err, "lookup test_result"))
-               return;
-
-       ASSERT_MEMEQ(&map_value, &test_payload, TEST_PAYLOAD_LEN,
-                    "test_result map contains test payload");
-}
-
-static bool clear_test_result(struct bpf_map *result_map)
-{
-       const __u8 v[sizeof(test_payload)] = {};
-       const __u32 k = 0;
-       int err;
-
-       err = bpf_map__update_elem(result_map, &k, sizeof(k), v, sizeof(v), BPF_ANY);
-       ASSERT_OK(err, "update test_result");
-
-       return err == 0;
-}
-
 void test_xdp_context_veth(void)
 {
        LIBBPF_OPTS(bpf_tc_hook, tc_hook, .attach_point = BPF_TC_INGRESS);
@@ -270,11 +243,13 @@ void test_xdp_context_veth(void)
        if (!ASSERT_GE(tx_ifindex, 0, "if_nametoindex tx"))
                goto close;
 
+       skel->bss->test_pass = false;
+
        ret = send_test_packet(tx_ifindex);
        if (!ASSERT_OK(ret, "send_test_packet"))
                goto close;
 
-       assert_test_result(skel->maps.test_result);
+       ASSERT_TRUE(skel->bss->test_pass, "test_pass");
 
 close:
        close_netns(nstoken);
@@ -286,7 +261,7 @@ close:
 static void test_tuntap(struct bpf_program *xdp_prog,
                        struct bpf_program *tc_prio_1_prog,
                        struct bpf_program *tc_prio_2_prog,
-                       struct bpf_map *result_map)
+                       bool *test_pass)
 {
        LIBBPF_OPTS(bpf_tc_hook, tc_hook, .attach_point = BPF_TC_INGRESS);
        LIBBPF_OPTS(bpf_tc_opts, tc_opts, .handle = 1, .priority = 1);
@@ -295,8 +270,7 @@ static void test_tuntap(struct bpf_program *xdp_prog,
        int tap_ifindex;
        int ret;
 
-       if (!clear_test_result(result_map))
-               return;
+       *test_pass = false;
 
        ns = netns_new(TAP_NETNS, true);
        if (!ASSERT_OK_PTR(ns, "create and open ns"))
@@ -340,7 +314,7 @@ static void test_tuntap(struct bpf_program *xdp_prog,
        if (!ASSERT_OK(ret, "write_test_packet"))
                goto close;
 
-       assert_test_result(result_map);
+       ASSERT_TRUE(*test_pass, "test_pass");
 
 close:
        if (tap_fd >= 0)
@@ -431,37 +405,37 @@ void test_xdp_context_tuntap(void)
                test_tuntap(skel->progs.ing_xdp,
                            skel->progs.ing_cls,
                            NULL, /* tc prio 2 */
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("dynptr_read"))
                test_tuntap(skel->progs.ing_xdp,
                            skel->progs.ing_cls_dynptr_read,
                            NULL, /* tc prio 2 */
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("dynptr_slice"))
                test_tuntap(skel->progs.ing_xdp,
                            skel->progs.ing_cls_dynptr_slice,
                            NULL, /* tc prio 2 */
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("dynptr_write"))
                test_tuntap(skel->progs.ing_xdp_zalloc_meta,
                            skel->progs.ing_cls_dynptr_write,
                            skel->progs.ing_cls_dynptr_read,
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("dynptr_slice_rdwr"))
                test_tuntap(skel->progs.ing_xdp_zalloc_meta,
                            skel->progs.ing_cls_dynptr_slice_rdwr,
                            skel->progs.ing_cls_dynptr_slice,
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("dynptr_offset"))
                test_tuntap(skel->progs.ing_xdp_zalloc_meta,
                            skel->progs.ing_cls_dynptr_offset_wr,
                            skel->progs.ing_cls_dynptr_offset_rd,
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("dynptr_offset_oob"))
                test_tuntap(skel->progs.ing_xdp,
                            skel->progs.ing_cls_dynptr_offset_oob,
                            skel->progs.ing_cls,
-                           skel->maps.test_result);
+                           &skel->bss->test_pass);
        if (test__start_subtest("clone_data_meta_empty_on_data_write"))
                test_tuntap_mirred(skel->progs.ing_xdp,
                                   skel->progs.clone_data_meta_empty_on_data_write,

diff --git a/tools/testing/selftests/bpf/progs/test_xdp_meta.c b/tools/testing/selftests/bpf/progs/test_xdp_meta.c
index d79cb74b571e723041ece4f6d39e389653bce4b0..11288b20f56c731dfc88b88cbf8b4cc45db4f59b 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_xdp_meta.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_meta.c
@@ -11,37 +11,36 @@
 
 #define ctx_ptr(ctx, mem) (void *)(unsigned long)ctx->mem
 
-/* Demonstrates how metadata can be passed from an XDP program to a TC program
- * using bpf_xdp_adjust_meta.
- * For the sake of testing the metadata support in drivers, the XDP program uses
- * a fixed-size payload after the Ethernet header as metadata. The TC program
- * copies the metadata it receives into a map so it can be checked from
- * userspace.
+/* Demonstrate passing metadata from XDP to TC using bpf_xdp_adjust_meta.
+ *
+ * The XDP program extracts a fixed-size payload following the Ethernet header
+ * and stores it as packet metadata to test the driver's metadata support. The
+ * TC program then verifies if the passed metadata is correct.
  */
 
-struct {
-       __uint(type, BPF_MAP_TYPE_ARRAY);
-       __uint(max_entries, 1);
-       __type(key, __u32);
-       __uint(value_size, META_SIZE);
-} test_result SEC(".maps");
-
 bool test_pass;
 
+static const __u8 meta_want[META_SIZE] = {
+       0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+       0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
+       0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
+       0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38,
+};
+
 SEC("tc")
 int ing_cls(struct __sk_buff *ctx)
 {
-       __u8 *data, *data_meta;
-       __u32 key = 0;
-
-       data_meta = ctx_ptr(ctx, data_meta);
-       data      = ctx_ptr(ctx, data);
+       __u8 *meta_have = ctx_ptr(ctx, data_meta);
+       __u8 *data = ctx_ptr(ctx, data);
 
-       if (data_meta + META_SIZE > data)
-               return TC_ACT_SHOT;
+       if (meta_have + META_SIZE > data)
+               goto out;
 
-       bpf_map_update_elem(&test_result, &key, data_meta, BPF_ANY);
+       if (__builtin_memcmp(meta_want, meta_have, META_SIZE))
+               goto out;
 
+       test_pass = true;
+out:
        return TC_ACT_SHOT;
 }
 
@@ -49,17 +48,17 @@ int ing_cls(struct __sk_buff *ctx)
 SEC("tc")
 int ing_cls_dynptr_read(struct __sk_buff *ctx)
 {
+       __u8 meta_have[META_SIZE];
        struct bpf_dynptr meta;
-       const __u32 zero = 0;
-       __u8 *dst;
-
-       dst = bpf_map_lookup_elem(&test_result, &zero);
-       if (!dst)
-               return TC_ACT_SHOT;
 
        bpf_dynptr_from_skb_meta(ctx, 0, &meta);
-       bpf_dynptr_read(dst, META_SIZE, &meta, 0, 0);
+       bpf_dynptr_read(meta_have, META_SIZE, &meta, 0, 0);
+
+       if (__builtin_memcmp(meta_want, meta_have, META_SIZE))
+               goto out;
 
+       test_pass = true;
+out:
        return TC_ACT_SHOT;
 }
 
@@ -86,20 +85,18 @@ SEC("tc")
 int ing_cls_dynptr_slice(struct __sk_buff *ctx)
 {
        struct bpf_dynptr meta;
-       const __u32 zero = 0;
-       __u8 *dst, *src;
-
-       dst = bpf_map_lookup_elem(&test_result, &zero);
-       if (!dst)
-               return TC_ACT_SHOT;
+       __u8 *meta_have;
 
        bpf_dynptr_from_skb_meta(ctx, 0, &meta);
-       src = bpf_dynptr_slice(&meta, 0, NULL, META_SIZE);
-       if (!src)
-               return TC_ACT_SHOT;
+       meta_have = bpf_dynptr_slice(&meta, 0, NULL, META_SIZE);
+       if (!meta_have)
+               goto out;
 
-       __builtin_memcpy(dst, src, META_SIZE);
+       if (__builtin_memcmp(meta_want, meta_have, META_SIZE))
+               goto out;
 
+       test_pass = true;
+out:
        return TC_ACT_SHOT;
 }
 
@@ -129,14 +126,12 @@ int ing_cls_dynptr_slice_rdwr(struct __sk_buff *ctx)
 SEC("tc")
 int ing_cls_dynptr_offset_rd(struct __sk_buff *ctx)
 {
-       struct bpf_dynptr meta;
        const __u32 chunk_len = META_SIZE / 4;
-       const __u32 zero = 0;
+       __u8 meta_have[META_SIZE];
+       struct bpf_dynptr meta;
        __u8 *dst, *src;
 
-       dst = bpf_map_lookup_elem(&test_result, &zero);
-       if (!dst)
-               return TC_ACT_SHOT;
+       dst = meta_have;
 
        /* 1. Regular read */
        bpf_dynptr_from_skb_meta(ctx, 0, &meta);
@@ -155,9 +150,14 @@ int ing_cls_dynptr_offset_rd(struct __sk_buff *ctx)
        /* 4. Read from a slice starting at an offset */
        src = bpf_dynptr_slice(&meta, 2 * chunk_len, NULL, chunk_len);
        if (!src)
-               return TC_ACT_SHOT;
+               goto out;
        __builtin_memcpy(dst, src, chunk_len);
 
+       if (__builtin_memcmp(meta_want, meta_have, META_SIZE))
+               goto out;
+
+       test_pass = true;
+out:
        return TC_ACT_SHOT;
 }