Skip fw->fw policies and treat dest-side + as intra-zone override

internal/nftables/compiler.go

@@ -868,7 +868,7 @@ func (c *Compiler) compilePolicies(state *FirewallState) error {
 		for _, sz := range srcZones {
 			for _, dz := range dstZones {
 				if sz == dz {
-					if !explicitIntra && !strings.HasSuffix(pol.Source, "+") {
+					if sz == fwZone || (!explicitIntra && !strings.HasSuffix(pol.Source, "+") && !strings.HasSuffix(pol.Dest, "+")) {
 						continue
 					}
 					overridden[sz] = true

internal/nftables/compiler_test.go

@@ -3388,3 +3388,39 @@ func TestCompile_IntraZoneMultiInterface(t *testing.T) {
 		})
 	}
 }
+
+func TestCompile_FirewallSelfPolicySkipped(t *testing.T) {
+	for _, action := range []config.PolicyAction{config.PolicyAccept, config.PolicyDrop} {
+		t.Run(string(action), func(t *testing.T) {
+			state := mustCompile(t, listCfg(func(c *config.Config) {
+				c.Policy = []config.Policy{
+					{Source: "fw", Dest: "fw", Action: action},
+					{Source: "net", Dest: "fw", Action: config.PolicyDrop, Log: "info"},
+				}
+			}))
+			for _, chain := range []string{"input", "output", "forward"} {
+				if got := taggedRules(state, chain, "policy:0"); len(got) != 0 {
+					t.Errorf("fw->fw emitted %d rules in %s", len(got), chain)
+				}
+			}
+			got := taggedRules(state, "input", "policy:1")
+			if len(got) != 1 || describeRule(got[0]) != "iif=eth0" {
+				t.Errorf("net->fw input rules = %d, want one scoped to eth0", len(got))
+			}
+		})
+	}
+}
+
+func TestCompile_DestPlusOverridesIntraZone(t *testing.T) {
+	state := mustCompile(t, listCfg(func(c *config.Config) {
+		c.Zones["lxd"] = config.Zone{Type: config.ZoneIP}
+		c.Interfaces = append(c.Interfaces, config.Interface{Zone: "lxd", Interface: "lxdbr0"}, config.Interface{Zone: "lxd", Interface: "docker0"})
+		c.Policy = []config.Policy{{Source: "lxd", Dest: "all+", Action: config.PolicyDrop}}
+	}))
+	if got := taggedRules(state, "forward", "intra:lxd"); len(got) != 0 {
+		t.Errorf("lxd all+ must override implicit intra-zone accept, got %d rules", len(got))
+	}
+	if got := taggedRules(state, "forward", "policy:0"); len(got) == 0 {
+		t.Error("lxd all+ emitted no forward rules")
+	}
+}