selftests/bpf: Update xdp_context_test_run test to check maximum metadata size

Update the selftest to check that the metadata size check takes the
xdp_frame size into account in bpf_prog_test_run. The original
check (for meta size 256) was broken because the data frame supplied was
smaller than this, triggering a different EINVAL return. So supply a
larger data frame for this test to make sure we actually exercise the
check we think we are.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260105114747.1358750-2-toke@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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 ee94c281888ae0ea0da37c0c69c9ac4af2d13411..26159e0499c763f64d277101430e893218061622 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
@@ -47,6 +47,7 @@ void test_xdp_context_test_run(void)
        struct test_xdp_context_test_run *skel = NULL;
        char data[sizeof(pkt_v4) + sizeof(__u32)];
        char bad_ctx[sizeof(struct xdp_md) + 1];
+       char large_data[256];
        struct xdp_md ctx_in, ctx_out;
        DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
                            .data_in = &data,
@@ -94,9 +95,6 @@ void test_xdp_context_test_run(void)
        test_xdp_context_error(prog_fd, opts, 4, sizeof(__u32), sizeof(data),
                               0, 0, 0);
 
-       /* Meta data must be 255 bytes or smaller */
-       test_xdp_context_error(prog_fd, opts, 0, 256, sizeof(data), 0, 0, 0);
-
        /* Total size of data must be data_end - data_meta or larger */
        test_xdp_context_error(prog_fd, opts, 0, sizeof(__u32),
                               sizeof(data) + 1, 0, 0, 0);
@@ -116,6 +114,16 @@ void test_xdp_context_test_run(void)
        test_xdp_context_error(prog_fd, opts, 0, sizeof(__u32), sizeof(data),
                               0, 0, 1);
 
+       /* Meta data must be 216 bytes or smaller (256 - sizeof(struct
+        * xdp_frame)). Test both nearest invalid size and nearest invalid
+        * 4-byte-aligned size, and make sure data_in is large enough that we
+        * actually hit the check on metadata length
+        */
+       opts.data_in = large_data;
+       opts.data_size_in = sizeof(large_data);
+       test_xdp_context_error(prog_fd, opts, 0, 217, sizeof(large_data), 0, 0, 0);
+       test_xdp_context_error(prog_fd, opts, 0, 220, sizeof(large_data), 0, 0, 0);
+
        test_xdp_context_test_run__destroy(skel);
 }