[net-next v2 3/3] selftests/net: Test PACKET_AUXDATA

[Joe Damato <joe@dama.to>]

Extend the packet socket selftest, adding a recvmsg path, to test
PACKET_AUXDATA. Check basic attributes of tpacket_auxdata.

Signed-off-by: Joe Damato <joe@dama.to>
---
 tools/testing/selftests/net/psock_snd.c  | 67 ++++++++++++++++++++++--
 tools/testing/selftests/net/psock_snd.sh |  5 ++
 2 files changed, 67 insertions(+), 5 deletions(-)

v2:
  - Add is_psock bool argument to do_rx.
  - Factor out aux data check into its own function for readability.

diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index 81096df5cffc..5464317c1764 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -40,6 +40,7 @@ static bool	cfg_use_qdisc_bypass;
 static bool	cfg_use_vlan;
 static bool	cfg_use_vnet;
 static bool	cfg_drop;
+static bool	cfg_aux_data;
 
 static char	*cfg_ifname = "lo";
 static int	cfg_mtu	= 1500;
@@ -279,11 +280,54 @@ static int setup_rx(void)
 	return fd;
 }
 
-static void do_rx(int fd, int expected_len, char *expected)
+static void check_aux_data(struct cmsghdr *cmsg, int expected_len)
 {
+	struct tpacket_auxdata *adata;
+
+	if (!cmsg)
+		error(1, 0, "auxdata null");
+
+	if (cmsg->cmsg_level != SOL_PACKET)
+		error(1, 0, "cmsg_level != SOL_PACKET");
+
+	if (cmsg->cmsg_type != PACKET_AUXDATA)
+		error(1, 0, "cmsg_type != PACKET_AUXDATA");
+
+	adata = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
+
+	if (adata->tp_net != ETH_HLEN)
+		error(1, 0, "cmsg tp_net != ETH_HLEN");
+
+	if (adata->tp_len != expected_len)
+		error(1, 0, "cmsg tp_len != %u", expected_len);
+
+	if (adata->tp_snaplen != expected_len)
+		error(1, 0, "cmsg tp_snaplen != %u", expected_len);
+}
+
+static void do_rx(int fd, int expected_len, char *expected, bool is_psock)
+{
+	bool aux = is_psock && cfg_aux_data;
+	char cmsg_buf[1024] = {};
+	struct msghdr msg = {};
+	struct iovec iov[1];
 	int ret;
 
-	ret = recv(fd, rbuf, sizeof(rbuf), 0);
+	if (aux) {
+		iov[0].iov_base = rbuf;
+		iov[0].iov_len = sizeof(rbuf);
+
+		msg.msg_iov = iov;
+		msg.msg_iovlen = 1;
+
+		msg.msg_control = cmsg_buf;
+		msg.msg_controllen = sizeof(cmsg_buf);
+
+		ret = recvmsg(fd, &msg, 0);
+	} else {
+		ret = recv(fd, rbuf, sizeof(rbuf), 0);
+	}
+
 	if (ret == -1)
 		error(1, errno, "recv");
 	if (ret != expected_len)
@@ -292,6 +336,12 @@ static void do_rx(int fd, int expected_len, char *expected)
 	if (memcmp(rbuf, expected, ret))
 		error(1, 0, "recv: data mismatch");
 
+	if (aux) {
+		struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+
+		check_aux_data(cmsg, expected_len);
+	}
+
 	fprintf(stderr, "rx: %u\n", ret);
 }
 
@@ -312,6 +362,10 @@ static int setup_sniffer(void)
 		if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &one, sizeof(one)))
 			error(1, errno, "setsockopt SO_RCVBUF");
 
+	if (cfg_aux_data)
+		if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA, &one, sizeof(one)))
+			error(1, errno, "setsockopt PACKET_AUXDATA");
+
 	pair_udp_setfilter(fd);
 	do_bind(fd);
 
@@ -322,8 +376,11 @@ static void parse_opts(int argc, char **argv)
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "bcCdDgl:qt:vV")) != -1) {
+	while ((c = getopt(argc, argv, "abcCdDgl:qt:vV")) != -1) {
 		switch (c) {
+		case 'a':
+			cfg_aux_data = true;
+			break;
 		case 'b':
 			cfg_use_bind = true;
 			break;
@@ -432,11 +489,11 @@ static void run_test(void)
 	/* BPF filter accepts only this length, vlan changes MAC */
 	if (cfg_payload_len == DATA_LEN && !cfg_use_vlan) {
 		do_rx(fds, total_len - sizeof(struct virtio_net_hdr),
-		      tbuf + sizeof(struct virtio_net_hdr));
+		      tbuf + sizeof(struct virtio_net_hdr), true);
 		check_packet_stats(fds);
 	}
 
-	do_rx(fdr, cfg_payload_len, tbuf + total_len - cfg_payload_len);
+	do_rx(fdr, cfg_payload_len, tbuf + total_len - cfg_payload_len, false);
 
 out:
 	if (close(fds))
diff --git a/tools/testing/selftests/net/psock_snd.sh b/tools/testing/selftests/net/psock_snd.sh
index b6ef12fad5d5..111c9e2f0d21 100755
--- a/tools/testing/selftests/net/psock_snd.sh
+++ b/tools/testing/selftests/net/psock_snd.sh
@@ -97,4 +97,9 @@ echo "raw gso max size + 1 (expected to fail)"
 echo "test drops statistics"
 ./in_netns.sh ./psock_snd -D
 
+# test aux data
+
+echo "test aux data"
+./in_netns.sh ./psock_snd -a
+
 echo "OK. All tests passed"
-- 
2.52.0