selftests: openvswitch: add psample test

Add a test to verify sampling packets via psample works.

In order to do that, create a subcommand in ovs-dpctl.py to listen to
on the psample multicast group and print samples.
Reviewed-by: Aaron Conole <aconole@redhat.com>
Tested-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Link: https://patch.msgid.link/20240704085710.353845-11-amorenoz@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/openvswitch/openvswitch.sh

@@ -20,7 +20,8 @@ tests="
 	nat_related_v4				ip4-nat-related: ICMP related matches work with SNAT
 	netlink_checks				ovsnl: validate netlink attrs and settings
 	upcall_interfaces			ovs: test the upcall interfaces
-	drop_reason				drop: test drop reasons are emitted"
+	drop_reason				drop: test drop reasons are emitted
+	psample					psample: Sampling packets with psample"
 
 info() {
 	[ "${ovs_dir}" != "" ] &&
@@ -105,12 +106,21 @@ ovs_netns_spawn_daemon() {
 	shift
 	netns=$1
 	shift
-	info "spawning cmd: $*"
+	if [ "$netns" == "_default" ]; then
+		$*  >> $ovs_dir/stdout  2>> $ovs_dir/stderr &
+	else
 		ip netns exec $netns $*  >> $ovs_dir/stdout  2>> $ovs_dir/stderr &
+	fi
 	pid=$!
 	ovs_sbx "$sbx" on_exit "kill -TERM $pid 2>/dev/null"
 }
 
+ovs_spawn_daemon() {
+	sbx=$1
+	shift
+	ovs_netns_spawn_daemon $sbx "_default" $*
+}
+
 ovs_add_netns_and_veths () {
 	info "Adding netns attached: sbx:$1 dp:$2 {$3, $4, $5}"
 	ovs_sbx "$1" ip netns add "$3" || return 1
@@ -173,6 +183,19 @@ ovs_drop_reason_count()
 	return `echo "$perf_output" | grep "$pattern" | wc -l`
 }
 
+ovs_test_flow_fails () {
+	ERR_MSG="Flow actions may not be safe on all matching packets"
+
+	PRE_TEST=$(dmesg | grep -c "${ERR_MSG}")
+	ovs_add_flow $@ &> /dev/null $@ && return 1
+	POST_TEST=$(dmesg | grep -c "${ERR_MSG}")
+
+	if [ "$PRE_TEST" == "$POST_TEST" ]; then
+		return 1
+	fi
+	return 0
+}
+
 usage() {
 	echo
 	echo "$0 [OPTIONS] [TEST]..."
@@ -187,6 +210,92 @@ usage() {
 	exit 1
 }
 
+
+# psample test
+# - use psample to observe packets
+test_psample() {
+	sbx_add "test_psample" || return $?
+
+	# Add a datapath with per-vport dispatching.
+	ovs_add_dp "test_psample" psample -V 2:1 || return 1
+
+	info "create namespaces"
+	ovs_add_netns_and_veths "test_psample" "psample" \
+		client c0 c1 172.31.110.10/24 -u || return 1
+	ovs_add_netns_and_veths "test_psample" "psample" \
+		server s0 s1 172.31.110.20/24 -u || return 1
+
+	# Check if psample actions can be configured.
+	ovs_add_flow "test_psample" psample \
+	'in_port(1),eth(),eth_type(0x0806),arp()' 'psample(group=1)' &> /dev/null
+	if [ $? == 1 ]; then
+		info "no support for psample - skipping"
+		ovs_exit_sig
+		return $ksft_skip
+	fi
+
+	ovs_del_flows "test_psample" psample
+
+	# Test action verification.
+	OLDIFS=$IFS
+	IFS='*'
+	min_key='in_port(1),eth(),eth_type(0x0800),ipv4()'
+	for testcase in \
+		"cookie to large"*"psample(group=1,cookie=1615141312111009080706050403020100)" \
+		"no group with cookie"*"psample(cookie=abcd)" \
+		"no group"*"psample()";
+	do
+		set -- $testcase;
+		ovs_test_flow_fails "test_psample" psample $min_key $2
+		if [ $? == 1 ]; then
+			info "failed - $1"
+			return 1
+		fi
+	done
+	IFS=$OLDIFS
+
+	ovs_del_flows "test_psample" psample
+	# Allow ARP
+	ovs_add_flow "test_psample" psample \
+		'in_port(1),eth(),eth_type(0x0806),arp()' '2' || return 1
+	ovs_add_flow "test_psample" psample \
+		'in_port(2),eth(),eth_type(0x0806),arp()' '1' || return 1
+
+	# Sample first 14 bytes of all traffic.
+	ovs_add_flow "test_psample" psample \
+	    "in_port(1),eth(),eth_type(0x0800),ipv4()" \
+            "trunc(14),psample(group=1,cookie=c0ffee),2"
+
+	# Sample all traffic. In this case, use a sample() action with both
+	# psample and an upcall emulating simultaneous local sampling and
+	# sFlow / IPFIX.
+	nlpid=$(grep -E "listening on upcall packet handler" \
+            $ovs_dir/s0.out | cut -d ":" -f 2 | tr -d ' ')
+
+	ovs_add_flow "test_psample" psample \
+            "in_port(2),eth(),eth_type(0x0800),ipv4()" \
+            "sample(sample=100%,actions(psample(group=2,cookie=eeff0c),userspace(pid=${nlpid},userdata=eeff0c))),1"
+
+	# Record psample data.
+	ovs_spawn_daemon "test_psample" python3 $ovs_base/ovs-dpctl.py psample-events
+
+	# Send a single ping.
+	sleep 1
+	ovs_sbx "test_psample" ip netns exec client ping -I c1 172.31.110.20 -c 1 || return 1
+	sleep 1
+
+	# We should have received one userspace action upcall and 2 psample packets.
+	grep -E "userspace action command" $ovs_dir/s0.out >/dev/null 2>&1 || return 1
+
+	# client -> server samples should only contain the first 14 bytes of the packet.
+	grep -E "rate:4294967295,group:1,cookie:c0ffee data:[0-9a-f]{28}$" \
+			 $ovs_dir/stdout >/dev/null 2>&1 || return 1
+	grep -E "rate:4294967295,group:2,cookie:eeff0c" \
+			 $ovs_dir/stdout >/dev/null 2>&1 || return 1
+
+	return 0
+}
+
 # drop_reason test
 # - drop packets and verify the right drop reason is reported
 test_drop_reason() {

tools/testing/selftests/net/openvswitch/ovs-dpctl.py

@@ -28,8 +28,10 @@ try:
     from pyroute2.netlink import genlmsg
     from pyroute2.netlink import nla
     from pyroute2.netlink import nlmsg_atoms
+    from pyroute2.netlink.event import EventSocket
     from pyroute2.netlink.exceptions import NetlinkError
     from pyroute2.netlink.generic import GenericNetlinkSocket
+    from pyroute2.netlink.nlsocket import Marshal
     import pyroute2
     import pyroute2.iproute
 
@@ -2460,10 +2462,70 @@ class OvsFlow(GenericNetlinkSocket):
         print("MISS upcall[%d/%s]: %s" % (seq, pktpres, keystr), flush=True)
 
     def execute(self, packetmsg):
-        print("userspace execute command")
+        print("userspace execute command", flush=True)
 
     def action(self, packetmsg):
-        print("userspace action command")
+        print("userspace action command", flush=True)
+
+
+class psample_sample(genlmsg):
+    nla_map = (
+        ("PSAMPLE_ATTR_IIFINDEX", "none"),
+        ("PSAMPLE_ATTR_OIFINDEX", "none"),
+        ("PSAMPLE_ATTR_ORIGSIZE", "none"),
+        ("PSAMPLE_ATTR_SAMPLE_GROUP", "uint32"),
+        ("PSAMPLE_ATTR_GROUP_SEQ", "none"),
+        ("PSAMPLE_ATTR_SAMPLE_RATE", "uint32"),
+        ("PSAMPLE_ATTR_DATA", "array(uint8)"),
+        ("PSAMPLE_ATTR_GROUP_REFCOUNT", "none"),
+        ("PSAMPLE_ATTR_TUNNEL", "none"),
+        ("PSAMPLE_ATTR_PAD", "none"),
+        ("PSAMPLE_ATTR_OUT_TC", "none"),
+        ("PSAMPLE_ATTR_OUT_TC_OCC", "none"),
+        ("PSAMPLE_ATTR_LATENCY", "none"),
+        ("PSAMPLE_ATTR_TIMESTAMP", "none"),
+        ("PSAMPLE_ATTR_PROTO", "none"),
+        ("PSAMPLE_ATTR_USER_COOKIE", "array(uint8)"),
+    )
+
+    def dpstr(self):
+        fields = []
+        data = ""
+        for (attr, value) in self["attrs"]:
+            if attr == "PSAMPLE_ATTR_SAMPLE_GROUP":
+                fields.append("group:%d" % value)
+            if attr == "PSAMPLE_ATTR_SAMPLE_RATE":
+                fields.append("rate:%d" % value)
+            if attr == "PSAMPLE_ATTR_USER_COOKIE":
+                value = "".join(format(x, "02x") for x in value)
+                fields.append("cookie:%s" % value)
+            if attr == "PSAMPLE_ATTR_DATA" and len(value) > 0:
+                data = "data:%s" % "".join(format(x, "02x") for x in value)
+
+        return ("%s %s" % (",".join(fields), data)).strip()
+
+
+class psample_msg(Marshal):
+    PSAMPLE_CMD_SAMPLE = 0
+    PSAMPLE_CMD_GET_GROUP = 1
+    PSAMPLE_CMD_NEW_GROUP = 2
+    PSAMPLE_CMD_DEL_GROUP = 3
+    PSAMPLE_CMD_SET_FILTER = 4
+    msg_map = {PSAMPLE_CMD_SAMPLE: psample_sample}
+
+
+class PsampleEvent(EventSocket):
+    genl_family = "psample"
+    mcast_groups = ["packets"]
+    marshal_class = psample_msg
+
+    def read_samples(self):
+        while True:
+            try:
+                for msg in self.get():
+                    print(msg.dpstr(), flush=True)
+            except NetlinkError as ne:
+                raise ne
 
 
 def print_ovsdp_full(dp_lookup_rep, ifindex, ndb=NDB(), vpl=OvsVport()):
@@ -2530,7 +2592,7 @@ def main(argv):
         help="Increment 'verbose' output counter.",
         default=0,
     )
-    subparsers = parser.add_subparsers()
+    subparsers = parser.add_subparsers(dest="subcommand")
 
     showdpcmd = subparsers.add_parser("show")
     showdpcmd.add_argument(
@@ -2605,6 +2667,8 @@ def main(argv):
     delfscmd = subparsers.add_parser("del-flows")
     delfscmd.add_argument("flsbr", help="Datapath name")
 
+    subparsers.add_parser("psample-events")
+
     args = parser.parse_args()
 
     if args.verbose > 0:
@@ -2619,6 +2683,9 @@ def main(argv):
 
     sys.setrecursionlimit(100000)
 
+    if args.subcommand == "psample-events":
+        PsampleEvent().read_samples()
+
     if hasattr(args, "showdp"):
         found = False
         for iface in ndb.interfaces: