[PATCH bpf v5 11/12] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer

John Fastabend
2023-04-06T01:01:52Z

A bug was reported where ioctl(FIONREAD) returned zero even though the
socket with a SK_SKB verdict program attached had bytes in the msg
queue. The result is programs may hang or more likely try to recover,
but use suboptimal buffer sizes.

Add a test to check that ioctl(FIONREAD) returns the correct number of
bytes.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---
.../selftests/bpf/prog_tests/sockmap_basic.c | 48 +++++++++++++++++++
1 file changed, 48 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index f9f611618e45..322b5a135740 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -416,6 +416,52 @@ static void test_sockmap_skb_verdict_shutdown(void)
test_sockmap_pass_prog__destroy(skel);
}

+static void test_sockmap_skb_verdict_fionread(void)
+{
+ int err, map, verdict, s, c0, c1, p0, p1;
+ struct test_sockmap_pass_prog *skel;
+ int zero = 0, sent, recvd, avail;
+ char buf[256] = "0123456789";
+
+ skel = test_sockmap_pass_prog__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "open_and_load"))
+ return;
+
+ verdict = bpf_program__fd(skel->progs.prog_skb_verdict);
+ map = bpf_map__fd(skel->maps.sock_map_rx);
+
+ err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0);
+ if (!ASSERT_OK(err, "bpf_prog_attach"))
+ goto out;
+
+ s = socket_loopback(AF_INET, SOCK_STREAM);
+ if (!ASSERT_GT(s, -1, "socket_loopback(s)"))
+ goto out;
+ err = create_socket_pairs(s, AF_INET, SOCK_STREAM, &c0, &c1, &p0, &p1);
+ if (!ASSERT_OK(err, "create_socket_pairs(s)"))
+ 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(p0)");
+ err = ioctl(c1, FIONREAD, &avail);
+ ASSERT_OK(err, "ioctl(FIONREAD) error");
+ ASSERT_EQ(avail, sizeof(buf), "ioctl(FIONREAD)");
+ recvd = recv_timeout(c1, &buf, sizeof(buf), SOCK_NONBLOCK, IO_TIMEOUT_SEC);
+ ASSERT_EQ(recvd, sizeof(buf), "recv_timeout(c0)");
+
+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"))
@@ -452,4 +498,6 @@ void test_sockmap_basic(void)
test_sockmap_progs_query(BPF_SK_SKB_VERDICT);
if (test__start_subtest("sockmap skb_verdict shutdown"))
test_sockmap_skb_verdict_shutdown();
+ if (test__start_subtest("sockmap skb_verdict fionread"))
+ test_sockmap_skb_verdict_fionread();
}
--
2.33.0