selftests/bpf: Test FIONREAD on a sockmap socket without a verdict program

Add a test validating that FIONREAD on a TCP socket in a sockmap
without a verdict program reports data pending in sk_receive_queue.

Signed-off-by: Mattia Meleleo <mattia.meleleo@coralogix.com>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20260708-fionread-no-verdict-v3-2-b4ee31b3af53@coralogix.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index 2d22a9058a8e9230052ab64821f4244d712f8c61..e5fc038d747b6f5082eac568a456602a46eda6d1 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -1373,6 +1373,43 @@ end:
        test_sockmap_pass_prog__destroy(skel);
 }
 
+/* A socket in a sockmap without a verdict program keeps its ingress data
+ * in sk_receive_queue: FIONREAD must account for it.
+ */
+static void test_sockmap_no_verdict_fionread(void)
+{
+       int err, map, zero = 0, sent, avail;
+       int c0 = -1, c1 = -1, p0 = -1, p1 = -1;
+       struct test_sockmap_pass_prog *skel;
+       char buf[256] = "0123456789";
+
+       skel = test_sockmap_pass_prog__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "open_and_load"))
+               return;
+       map = bpf_map__fd(skel->maps.sock_map_rx);
+
+       err = create_socket_pairs(AF_INET, SOCK_STREAM, &c0, &c1, &p0, &p1);
+       if (!ASSERT_OK(err, "create_socket_pairs()"))
+               goto out;
+
+       err = bpf_map_update_elem(map, &zero, &c1, BPF_NOEXIST);
+       if (!ASSERT_OK(err, "bpf_map_update_elem(c1)"))
+               goto out_close;
+
+       sent = xsend(p1, &buf, sizeof(buf), 0);
+       ASSERT_EQ(sent, sizeof(buf), "xsend(p1)");
+       avail = wait_for_fionread(c1, sizeof(buf), IO_TIMEOUT_SEC);
+       ASSERT_EQ(avail, sizeof(buf), "ioctl(FIONREAD)");
+
+out_close:
+       close(c0);
+       close(p0);
+       close(c1);
+       close(p1);
+out:
+       test_sockmap_pass_prog__destroy(skel);
+}
+
 void test_sockmap_basic(void)
 {
        if (test__start_subtest("sockmap create_update_free"))
@@ -1415,6 +1452,8 @@ void test_sockmap_basic(void)
                test_sockmap_skb_verdict_shutdown();
        if (test__start_subtest("sockmap skb_verdict fionread"))
                test_sockmap_skb_verdict_fionread(true);
+       if (test__start_subtest("sockmap no_verdict fionread"))
+               test_sockmap_no_verdict_fionread();
        if (test__start_subtest("sockmap skb_verdict fionread on drop"))
                test_sockmap_skb_verdict_fionread(false);
        if (test__start_subtest("sockmap skb_verdict change tail"))