[PATCH bpf-next 2/5] selftests/bpf: sockmap_redir: Fix OOB handling

Michal Luczaj
2025-09-05T11:12:03Z

In some test cases, OOB packets might have been left unread. Flush them out
and introduce additional checks.

Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
tools/testing/selftests/bpf/prog_tests/sockmap_redir.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c b/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c
index c1bf1076e8152b7d83c3e07e2dce746b5a39cf7e..4997e72c14345b274367f3f2f4115c39d1ae48c9 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c
@@ -184,6 +184,19 @@ static void handle_unsupported(int sd_send, int sd_peer, int sd_in, int sd_out,
FAIL_ERRNO("unsupported: packet missing, retval=%zd", n);
}

+ /* af_unix send("ab", MSG_OOB) spits out 2 packets, but only the latter
+ * ("b") is designated OOB. If the peer is in a sockmap, the OOB packet
+ * will be silently dropped. Otherwise OOB stays in the queue and should
+ * be taken care of.
+ */
+ if ((send_flags & MSG_OOB) && !pass && !drop) {
+ errno = 0;
+ n = recv_timeout(sd_peer, &recv_buf, 1, MSG_OOB, IO_TIMEOUT_SEC);
+ /* Ignore unsupported sk_msg error */
+ if (n != 1 && errno != EOPNOTSUPP)
+ FAIL_ERRNO("recv(OOB): retval=%zd", n);
+ }
+
/* Ensure queues are empty */
fail_recv("bpf.recv(sd_send)", sd_send, 0);
if (sd_in != sd_send)
@@ -192,6 +205,9 @@ static void handle_unsupported(int sd_send, int sd_peer, int sd_in, int sd_out,
fail_recv("bpf.recv(sd_out)", sd_out, 0);
if (sd_recv != sd_out)
fail_recv("bpf.recv(sd_recv)", sd_recv, 0);
+
+ fail_recv("recv(sd_peer, OOB)", sd_peer, MSG_OOB);
+ fail_recv("recv(sd_out, OOB)", sd_out, MSG_OOB);
}

static void test_send_redir_recv(int sd_send, int send_flags, int sd_peer,

--
2.50.1