selftests: tc: act_pedit: require matching IPv4 L4 protocol

Add a tdc test that checks the act_pedit extended L4 header mode does not
edit a packet whose IPv4 protocol does not match the selected transport
header.

The test installs an ingress pedit rule that sets the UDP destination
port, then injects a TCP packet with dport 2222. The UDP and TCP
destination ports sit at the same L4 offset, so a buggy kernel rewrites
the TCP dport. A second flower filter matches TCP dport 2222 and drops
the packet through an indexed gact action; the test then verifies via
JSON that this action saw exactly one packet, i.e. the dport was left
untouched and still matched 2222.

Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/tc-testing/tc-tests/actions/pedit.json

@@ -1920,5 +1920,54 @@
         "teardown": [
             "$TC actions flush action pedit"
         ]
+    },
+    {
+        "id": "1a4f",
+        "name": "Pedit udp dport should not mangle TCP packet dport",
+        "category": [
+            "actions",
+            "pedit"
+        ],
+        "plugins": {
+            "requires": [
+                "nsPlugin",
+                "scapyPlugin"
+            ]
+        },
+        "setup": [
+            "$TC qdisc add dev $DEV1 clsact",
+            "$TC filter add dev $DEV1 ingress protocol ip pref 1 matchall action pedit ex munge udp dport set 18053 continue"
+        ],
+        "cmdUnderTest": "$TC filter add dev $DEV1 ingress protocol ip pref 2 flower ip_proto tcp dst_port 2222 action drop index 1",
+        "scapy": {
+            "iface": "$DEV0",
+            "count": 1,
+            "packet": "Ether()/IP(dst='10.10.10.1')/TCP(dport=2222)"
+        },
+        "expExitCode": "0",
+        "verifyCmd": "$TC -j -s actions get action gact index 1",
+        "matchJSON": [
+            {
+                "total acts": 0
+            },
+            {
+                "actions": [
+                    {
+                        "order": 1,
+                        "kind": "gact",
+                        "control_action": {
+                            "type": "drop"
+                        },
+                        "index": 1,
+                        "stats": {
+                            "packets": 1
+                        }
+                    }
+                ]
+            }
+        ],
+        "teardown": [
+            "$TC qdisc del dev $DEV1 clsact"
+        ]
     }
 ]