[PATCH net-next v2 3/4] selftests: net: test IPV6_FL_F_REFLECT

[Marcelo Mendes Spessoto Junior <marcelomspessoto@gmail.com>]

According to source code, flowlabel_consistency must be deactivated
for the IPV6_FL_F_REFLECT flag to work. Therefore, take the following
measures: deactivate it on the wrapper .sh script, and skip this test
if it is run on an environment that does not correspond.

The previously defined tcp_listen and tcp_connect helpers were reused,
since the connection flow required for REFLECT validation is very
similar to REMOTE.

Signed-off-by: Marcelo Mendes Spessoto Junior <marcelomspessoto@gmail.com>
---
 tools/testing/selftests/net/ipv6_flowlabel.sh |  3 +-
 .../selftests/net/ipv6_flowlabel_mgr.c        | 61 +++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/ipv6_flowlabel.sh b/tools/testing/selftests/net/ipv6_flowlabel.sh
index cee95e252bee..4c3de3a27807 100755
--- a/tools/testing/selftests/net/ipv6_flowlabel.sh
+++ b/tools/testing/selftests/net/ipv6_flowlabel.sh
@@ -8,7 +8,8 @@
 set -e
 
 echo "TEST management"
-./in_netns.sh ./ipv6_flowlabel_mgr
+./in_netns.sh \
+  sh -c 'sysctl -q -w net.ipv6.flowlabel_consistency=0 && ./ipv6_flowlabel_mgr'
 
 echo "TEST datapath"
 ./in_netns.sh \
diff --git a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
index d482be2e9f9f..af87eec799c8 100644
--- a/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
+++ b/tools/testing/selftests/net/ipv6_flowlabel_mgr.c
@@ -6,6 +6,7 @@
 #include <arpa/inet.h>
 #include <error.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <limits.h>
 #include <linux/in6.h>
 #include <stdbool.h>
@@ -158,6 +159,22 @@ static void tcp_connect(int listener, uint32_t flowlabel, int *client, int *acce
 	*accepted = afd;
 }
 
+static bool flowlabel_consistency_enabled(void)
+{
+	char buf[2] = {};
+	int fd;
+
+	fd = open("/proc/sys/net/ipv6/flowlabel_consistency", O_RDONLY);
+	if (fd == -1)
+		return true;
+
+	if (read(fd, buf, sizeof(buf) - 1) < 0)
+		buf[0] = '1';
+	close(fd);
+
+	return buf[0] != '0';
+}
+
 static void run_tests(int fd)
 {
 	int wstatus;
@@ -288,6 +305,50 @@ static void run_tests(int fd)
 		close(remote_cfd);
 		close(remote_listener);
 	}
+
+	if (flowlabel_consistency_enabled()) {
+		fprintf(stderr,
+			"[INFO] skip REFLECT flag validation (net.ipv6.flowlabel_consistency must be 0)\n");
+	} else {
+		struct in6_flowlabel_req reflect_query = {
+			.flr_action = IPV6_FL_A_GET,
+		};
+		struct in6_flowlabel_req reflect_off = {
+			.flr_action = IPV6_FL_A_PUT,
+			.flr_flags = IPV6_FL_F_REFLECT,
+		};
+		struct in6_flowlabel_req reflect_on = {
+			.flr_action = IPV6_FL_A_GET,
+			.flr_flags = IPV6_FL_F_REFLECT,
+		};
+		socklen_t reflect_query_len = sizeof(reflect_query);
+		int reflect_listener = tcp_listen();
+		int reflect_cfd, reflect_afd;
+
+		explain("Enable REFLECT on the listener before the client connects");
+		expect_pass(setsockopt(reflect_listener, SOL_IPV6, IPV6_FLOWLABEL_MGR,
+				       &reflect_on, sizeof(reflect_on)));
+
+		tcp_connect(reflect_listener, 8, &reflect_cfd, &reflect_afd);
+
+		explain("Query the accepted socket's outgoing label, should be reflected");
+		expect_pass(getsockopt(reflect_afd, SOL_IPV6, IPV6_FLOWLABEL_MGR,
+				       &reflect_query, &reflect_query_len));
+		if (ntohl(reflect_query.flr_label) != 8)
+			error(1, 0, "unexpected reflected flowlabel %u",
+			      ntohl(reflect_query.flr_label));
+
+		explain("PUT+REFLECT disables reflection on the accepted socket");
+		expect_pass(setsockopt(reflect_afd, SOL_IPV6, IPV6_FLOWLABEL_MGR,
+				       &reflect_off, sizeof(reflect_off)));
+		explain("cannot disable reflection twice");
+		expect_fail(setsockopt(reflect_afd, SOL_IPV6, IPV6_FLOWLABEL_MGR,
+				       &reflect_off, sizeof(reflect_off)));
+
+		close(reflect_afd);
+		close(reflect_cfd);
+		close(reflect_listener);
+	}
 }
 
 static void parse_opts(int argc, char **argv)
-- 
2.55.0