Commit bb516f98 authored by John Fastabend's avatar John Fastabend Committed by Daniel Borkmann
Browse files

bpf, sockmap: Test FIONREAD returns correct bytes in rx buffer 



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: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20230523025618.113937-13-john.fastabend@gmail.com
parent 1fa1fe8f

tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

+48 −0
Original line number Diff line number Diff line
@@ -410,6 +410,52 @@ 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"))
@@ -446,4 +492,6 @@ 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();

}