[PATCH net-next 0/5] Add PACKET_IGNORE_OUTGOING selftest for packet sockets

[PATCH net-next 0/5] Add PACKET_IGNORE_OUTGOING selftest for packet sockets

[Joe Damato]

Greetings:

Following up on my previous series [1] and further extending the selftests
for packet sockets to test PACKET_IGNORE_OUTGOING.

I re-ran the tests and the existing and new tests all pass.

Thanks,
Joe

[1]: https://lore.kernel.org/netdev/20260720122714.759175-1-joe@dama.to/
Joe Damato (5):
  selftests/net: psock: Generalize psock bind
  selftests/net: psock: Generalize stats check
  selftests/net: psock_snd: unify on recvmsg()
  selftests/net: psock_snd: Verify sll_pkttype
  selftests/net: test PACKET_IGNORE_OUTGOING

 tools/testing/selftests/net/psock_snd.c  | 147 ++++++++++++++++++-----
 tools/testing/selftests/net/psock_snd.sh |   5 +
 2 files changed, 124 insertions(+), 28 deletions(-)


base-commit: b515dc54795ef370be3cb396e7c12ad91686b6d1
-- 
2.53.0-Meta

[PATCH net-next 1/5] selftests/net: psock: Generalize psock bind

[Joe Damato]

Generalize packet socket binding so that types other than ETH_P_IP can
be used.

Signed-off-by: Joe Damato <joe@dama.to>
---
 tools/testing/selftests/net/psock_snd.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index 3313a15e0ca1..bb9a9cfdbe95 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -171,12 +171,12 @@ static int build_packet(int payload_len)
 	return off + payload_len;
 }
 
-static void do_bind(int fd)
+static void do_bind_proto(int fd, uint16_t proto)
 {
 	struct sockaddr_ll laddr = {0};
 
 	laddr.sll_family = AF_PACKET;
-	laddr.sll_protocol = htons(ETH_P_IP);
+	laddr.sll_protocol = htons(proto);
 	laddr.sll_ifindex = if_nametoindex(cfg_ifname);
 	if (!laddr.sll_ifindex)
 		error(1, errno, "if_nametoindex");
@@ -185,6 +185,11 @@ static void do_bind(int fd)
 		error(1, errno, "bind");
 }
 
+static void do_bind(int fd)
+{
+	do_bind_proto(fd, ETH_P_IP);
+}
+
 static void do_send(int fd, char *buf, int len)
 {
 	int ret;
-- 
2.53.0-Meta

Re: [PATCH net-next 1/5] selftests/net: psock: Generalize psock bind

[Willem de Bruijn]

Joe Damato wrote:
> Generalize packet socket binding so that types other than ETH_P_IP can
> be used.
> 
> Signed-off-by: Joe Damato <joe@dama.to>

Reviewed-by: Willem de Bruijn <willemb@google.com>

I'm generally in favor of splitting out series and subjective, but a
few of these patches could probably have been squashed.

[PATCH net-next 2/5] selftests/net: psock: Generalize stats check

[Joe Damato]

Generalize stats check code so that callers can specify the expected
packets.

Signed-off-by: Joe Damato <joe@dama.to>
---
 tools/testing/selftests/net/psock_snd.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index bb9a9cfdbe95..d506ea19491b 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -440,7 +440,7 @@ static void parse_opts(int argc, char **argv)
 		error(1, 0, "option aux data (-a) conflicts with drop (-D)");
 }
 
-static void check_packet_stats(int fd)
+static void check_packet_stats(int fd, unsigned int expected_packets)
 {
 	struct tpacket_stats st = {};
 	socklen_t len = sizeof(st);
@@ -459,8 +459,9 @@ static void check_packet_stats(int fd)
 		if (st.tp_drops == 0)
 			error(1, 0, "stats: expected drops but tp_drops == 0");
 	} else {
-		if (st.tp_packets != 1)
-			error(1, 0, "stats: tp_packets %u != 1", st.tp_packets);
+		if (st.tp_packets != expected_packets)
+			error(1, 0, "stats: tp_packets %u != %u",
+			      st.tp_packets, expected_packets);
 
 		if (st.tp_drops != 0)
 			error(1, 0, "stats: tp_drops %u != 0", st.tp_drops);
@@ -490,7 +491,7 @@ static void run_test(void)
 	total_len = do_tx();
 
 	if (cfg_drop) {
-		check_packet_stats(fds);
+		check_packet_stats(fds, 0);
 		goto out;
 	}
 
@@ -498,7 +499,7 @@ static void run_test(void)
 	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), true);
-		check_packet_stats(fds);
+		check_packet_stats(fds, 1);
 	}
 
 	do_rx(fdr, cfg_payload_len, tbuf + total_len - cfg_payload_len, false);
-- 
2.53.0-Meta

Re: [PATCH net-next 2/5] selftests/net: psock: Generalize stats check

[Willem de Bruijn]

Joe Damato wrote:
> Generalize stats check code so that callers can specify the expected
> packets.
> 
> Signed-off-by: Joe Damato <joe@dama.to>

Reviewed-by: Willem de Bruijn <willemb@google.com>

[PATCH net-next 3/5] selftests/net: psock_snd: unify on recvmsg()

[Joe Damato]

Don't maintain two RX paths in do_rx(). Unify on recvmsg() and pass aux
data only when needed.

No functional change.

Signed-off-by: Joe Damato <joe@dama.to>
---
 tools/testing/selftests/net/psock_snd.c | 28 ++++++++++---------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index d506ea19491b..b2593daca603 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -314,25 +314,22 @@ static void do_rx(int fd, int expected_len, char *expected, bool is_psock)
 {
 	char cmsg_buf[1024] __attribute__((aligned(8))) = {};
 	bool aux = is_psock && cfg_aux_data;
-	struct msghdr msg = {};
-	struct iovec iov[1];
+	struct iovec iov = {
+		.iov_base = rbuf,
+		.iov_len = sizeof(rbuf),
+	};
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
 	int ret;
 
 	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);
 	}
 
+	ret = recvmsg(fd, &msg, 0);
 	if (ret == -1)
 		error(1, errno, "recv");
 	if (ret != expected_len)
@@ -341,11 +338,8 @@ static void do_rx(int fd, int expected_len, char *expected, bool is_psock)
 	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);
-	}
+	if (aux)
+		check_aux_data(CMSG_FIRSTHDR(&msg), expected_len);
 
 	fprintf(stderr, "rx: %u\n", ret);
 }
-- 
2.53.0-Meta

Re: [PATCH net-next 3/5] selftests/net: psock_snd: unify on recvmsg()

[Willem de Bruijn]

Joe Damato wrote:
> Don't maintain two RX paths in do_rx(). Unify on recvmsg() and pass aux
> data only when needed.
> 
> No functional change.
> 
> Signed-off-by: Joe Damato <joe@dama.to>

Reviewed-by: Willem de Bruijn <willemb@google.com>

[PATCH net-next 4/5] selftests/net: psock_snd: Verify sll_pkttype

[Joe Damato]

Extend do_rx() to take an expected packet type. Existing callers pass -1
to skip the check.

Signed-off-by: Joe Damato <joe@dama.to>
---
 tools/testing/selftests/net/psock_snd.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index b2593daca603..f23877942ea3 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -310,10 +310,13 @@ static void check_aux_data(struct cmsghdr *cmsg, int 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)
+/* expected_pkttype < 0 skips the sll_pkttype check. */
+static void do_rx(int fd, int expected_len, char *expected, bool is_psock,
+		  int expected_pkttype)
 {
 	char cmsg_buf[1024] __attribute__((aligned(8))) = {};
 	bool aux = is_psock && cfg_aux_data;
+	struct sockaddr_ll saddr = {};
 	struct iovec iov = {
 		.iov_base = rbuf,
 		.iov_len = sizeof(rbuf),
@@ -328,6 +331,10 @@ static void do_rx(int fd, int expected_len, char *expected, bool is_psock)
 		msg.msg_control = cmsg_buf;
 		msg.msg_controllen = sizeof(cmsg_buf);
 	}
+	if (is_psock) {
+		msg.msg_name = &saddr;
+		msg.msg_namelen = sizeof(saddr);
+	}
 
 	ret = recvmsg(fd, &msg, 0);
 	if (ret == -1)
@@ -341,6 +348,10 @@ static void do_rx(int fd, int expected_len, char *expected, bool is_psock)
 	if (aux)
 		check_aux_data(CMSG_FIRSTHDR(&msg), expected_len);
 
+	if (expected_pkttype >= 0 && saddr.sll_pkttype != expected_pkttype)
+		error(1, 0, "recv: sll_pkttype %d != %d",
+		      saddr.sll_pkttype, expected_pkttype);
+
 	fprintf(stderr, "rx: %u\n", ret);
 }
 
@@ -492,11 +503,11 @@ 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), true);
+		      tbuf + sizeof(struct virtio_net_hdr), true, -1);
 		check_packet_stats(fds, 1);
 	}
 
-	do_rx(fdr, cfg_payload_len, tbuf + total_len - cfg_payload_len, false);
+	do_rx(fdr, cfg_payload_len, tbuf + total_len - cfg_payload_len, false, -1);
 
 out:
 	if (close(fds))
-- 
2.53.0-Meta

Re: [PATCH net-next 4/5] selftests/net: psock_snd: Verify sll_pkttype

[Willem de Bruijn]

Joe Damato wrote:
> Extend do_rx() to take an expected packet type. Existing callers pass -1
> to skip the check.
> 
> Signed-off-by: Joe Damato <joe@dama.to>

Reviewed-by: Willem de Bruijn <willemb@google.com>

Re: [PATCH net-next 4/5] selftests/net: psock_snd: Verify sll_pkttype

[Willem de Bruijn]

Joe Damato wrote:
> Extend do_rx() to take an expected packet type. Existing callers pass -1
> to skip the check.
> 
> Signed-off-by: Joe Damato <joe@dama.to>

Reviewed-by: Willem de Bruijn <willemb@google.com>

[PATCH net-next 5/5] selftests/net: test PACKET_IGNORE_OUTGOING

[Joe Damato]

Test that setsockopt PACKET_IGNORE_OUTGOING:

 - works with valid values (0 and 1),
 - rejects values outside of that range, and

When enabled for a loopback sniffer, it only produces 1 copy of the
packet (rx) instead of two copies (tx and rx). Use sll_pkttype to check
the direction of the packet to ensure the correct packet is sniffed.

Signed-off-by: Joe Damato <joe@dama.to>
---
 tools/testing/selftests/net/psock_snd.c  | 84 +++++++++++++++++++++++-
 tools/testing/selftests/net/psock_snd.sh |  5 ++
 2 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/psock_snd.c b/tools/testing/selftests/net/psock_snd.c
index f23877942ea3..0f6a30b26912 100644
--- a/tools/testing/selftests/net/psock_snd.c
+++ b/tools/testing/selftests/net/psock_snd.c
@@ -41,6 +41,7 @@ static bool	cfg_use_vlan;
 static bool	cfg_use_vnet;
 static bool	cfg_drop;
 static bool	cfg_aux_data;
+static bool	cfg_ignore_outgoing;
 
 static char	*cfg_ifname = "lo";
 static int	cfg_mtu	= 1500;
@@ -377,7 +378,14 @@ static int setup_sniffer(void)
 			error(1, errno, "setsockopt PACKET_AUXDATA");
 
 	pair_udp_setfilter(fd);
-	do_bind(fd);
+
+	/* binding to ETH_P_ALL adds the sniffer to ptype_all, which will see
+	 * the dev_queue_xmit_nit copy. ignore_outgoing should suppress this.
+	 */
+	if (cfg_ignore_outgoing)
+		do_bind_proto(fd, ETH_P_ALL);
+	else
+		do_bind(fd);
 
 	return fd;
 }
@@ -386,7 +394,7 @@ static void parse_opts(int argc, char **argv)
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "abcCdDgl:qt:vV")) != -1) {
+	while ((c = getopt(argc, argv, "abcCdDgil:qt:vV")) != -1) {
 		switch (c) {
 		case 'a':
 			cfg_aux_data = true;
@@ -409,6 +417,9 @@ static void parse_opts(int argc, char **argv)
 		case 'g':
 			cfg_use_gso = true;
 			break;
+		case 'i':
+			cfg_ignore_outgoing = true;
+			break;
 		case 'l':
 			cfg_payload_len = strtoul(optarg, NULL, 0);
 			break;
@@ -443,6 +454,10 @@ static void parse_opts(int argc, char **argv)
 
 	if (cfg_aux_data && cfg_drop)
 		error(1, 0, "option aux data (-a) conflicts with drop (-D)");
+
+	if (cfg_ignore_outgoing && (cfg_drop || cfg_aux_data))
+		error(1, 0,
+		      "option ignore outgoing (-i) conflicts with -D and -a");
 }
 
 static void check_packet_stats(int fd, unsigned int expected_packets)
@@ -486,6 +501,66 @@ static void check_packet_stats(int fd, unsigned int expected_packets)
 		error(1, 0, "stats: tp_drops %u != 0 after clear", st.tp_drops);
 }
 
+static void set_ignore_outgoing(int fd, int val)
+{
+	socklen_t len = sizeof(int);
+	int got = -1;
+
+	if (setsockopt(fd, SOL_PACKET, PACKET_IGNORE_OUTGOING,
+		       &val, sizeof(val)))
+		error(1, errno, "setsockopt PACKET_IGNORE_OUTGOING %d", val);
+
+	if (getsockopt(fd, SOL_PACKET, PACKET_IGNORE_OUTGOING, &got, &len))
+		error(1, errno, "getsockopt PACKET_IGNORE_OUTGOING");
+	if (got != val)
+		error(1, 0, "getsockopt: expected %d got %d", val, got);
+}
+
+static void check_ignore_outgoing_range(int fd)
+{
+	int val;
+
+	/* Values outside [0, 1] must be rejected with -EINVAL. */
+	val = 2;
+	if (setsockopt(fd, SOL_PACKET, PACKET_IGNORE_OUTGOING,
+		       &val, sizeof(val)) != -1 || errno != EINVAL)
+		error(1, errno,
+		      "setsockopt PACKET_IGNORE_OUTGOING val=2: expected EINVAL");
+
+	val = -1;
+	if (setsockopt(fd, SOL_PACKET, PACKET_IGNORE_OUTGOING,
+		       &val, sizeof(val)) != -1 || errno != EINVAL)
+		error(1, errno,
+		      "setsockopt PACKET_IGNORE_OUTGOING val=-1: expected EINVAL");
+}
+
+static void test_ignore_outgoing(int fds)
+{
+	char *expected = tbuf + sizeof(struct virtio_net_hdr);
+	int expected_len;
+
+	/* ptype_all sniffer on loopback should produce two copies per packet
+	 * (RX and TX).
+	 */
+	expected_len = do_tx();
+	expected_len -= sizeof(struct virtio_net_hdr);
+	do_rx(fds, expected_len, expected, true, PACKET_OUTGOING);
+	do_rx(fds, expected_len, expected, true, PACKET_HOST);
+	check_packet_stats(fds, 2);
+
+	/* 0 and 1 accepted; anything else rejected. */
+	set_ignore_outgoing(fds, 0);
+	set_ignore_outgoing(fds, 1);
+	check_ignore_outgoing_range(fds);
+
+	/* With PACKET_IGNORE_OUTGOING set, only the rx copy survives. */
+	do_tx();
+	do_rx(fds, expected_len, expected, true, PACKET_HOST);
+	if (recv(fds, rbuf, sizeof(rbuf), 0) != -1 || errno != EAGAIN)
+		error(1, errno, "expected EAGAIN, got extra packet");
+	check_packet_stats(fds, 1);
+}
+
 static void run_test(void)
 {
 	int fdr, fds, total_len;
@@ -493,6 +568,11 @@ static void run_test(void)
 	fdr = setup_rx();
 	fds = setup_sniffer();
 
+	if (cfg_ignore_outgoing) {
+		test_ignore_outgoing(fds);
+		goto out;
+	}
+
 	total_len = do_tx();
 
 	if (cfg_drop) {
diff --git a/tools/testing/selftests/net/psock_snd.sh b/tools/testing/selftests/net/psock_snd.sh
index 111c9e2f0d21..7fa0a3297988 100755
--- a/tools/testing/selftests/net/psock_snd.sh
+++ b/tools/testing/selftests/net/psock_snd.sh
@@ -102,4 +102,9 @@ echo "test drops statistics"
 echo "test aux data"
 ./in_netns.sh ./psock_snd -a
 
+# test ignore outgoing
+
+echo "test ignore outgoing"
+./in_netns.sh ./psock_snd -i
+
 echo "OK. All tests passed"
-- 
2.53.0-Meta