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chore: forbid double stateful NAT #334

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Frostman merged 1 commit into from
Mar 6, 2026
Merged

chore: forbid double stateful NAT #334

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20 changes: 20 additions & 0 deletions api/gateway/v1alpha1/peering_types.go
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,11 @@ func (p *Peering) Validate(ctx context.Context, kube kclient.Reader) error {
if len(vpcs) != 2 {
return fmt.Errorf("peering must have exactly 2 VPCs, got %d", len(vpcs)) //nolint:err113
}
// track the NAT on each side of the peering and disallow unsupported configurations
vpcNAT := make(map[string]struct {
Stateful bool
Stateless bool
}, 2)
for name, vpc := range p.Spec.Peering {
if vpc == nil {
continue
Expand Down Expand Up @@ -239,12 +244,21 @@ func (p *Peering) Validate(ctx context.Context, kube kclient.Reader) error {
nonNils := 0
if expose.NAT.Static != nil {
nonNils++
vpcEntry := vpcNAT[name]
vpcEntry.Stateless = true
vpcNAT[name] = vpcEntry
}
if expose.NAT.Masquerade != nil {
nonNils++
vpcEntry := vpcNAT[name]
vpcEntry.Stateful = true
vpcNAT[name] = vpcEntry
}
if expose.NAT.PortForward != nil {
nonNils++
vpcEntry := vpcNAT[name]
vpcEntry.Stateful = true
vpcNAT[name] = vpcEntry
}

if nonNils != 1 {
Expand Down Expand Up @@ -273,6 +287,12 @@ func (p *Peering) Validate(ctx context.Context, kube kclient.Reader) error {
}
}
}
if vpcNAT[vpcs[0]].Stateful && vpcNAT[vpcs[1]].Stateful {
return fmt.Errorf("unsupported configuration, only one side of a peering can use stateful NAT (i.e. masquerade or portForward)") //nolint:err113
}
if (vpcNAT[vpcs[0]].Stateless && vpcNAT[vpcs[1]].Stateful) || (vpcNAT[vpcs[1]].Stateless && vpcNAT[vpcs[0]].Stateful) {
return fmt.Errorf("unsupported configuration, one side of a peering using static NAT cannot peer with a side using stateful NAT") //nolint:err113
}

if kube != nil {
gwGroup := &GatewayGroup{}
Expand Down
169 changes: 167 additions & 2 deletions api/gateway/v1alpha1/peering_types_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -188,7 +188,7 @@ func TestPeeringWithStaticNAT(t *testing.T) {
assert.Equal(t, ref, peering)
}

func TestPeeringWithMasqueradeNAT(t *testing.T) {
func TestPeeringWithDoubleMasqueradeNAT(t *testing.T) {
common := &Peering{}
common.Spec.Peering = map[string]*PeeringEntry{
"vpc1": {
Expand Down Expand Up @@ -239,8 +239,56 @@ func TestPeeringWithMasqueradeNAT(t *testing.T) {

peering := common.DeepCopy()
peering.Default()
assert.NoError(t, peering.Validate(t.Context(), nil), "peering should be valid")
assert.Error(t, peering.Validate(t.Context(), nil), "masquerade on both sides should not be allowed")
assert.Equal(t, ref, peering)
}

func TestPeeringWithMasqueradeAndStaticNAT(t *testing.T) {
common := &Peering{}
common.Spec.Peering = map[string]*PeeringEntry{
"vpc1": {
Expose: []PeeringEntryExpose{
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.1.0/24"},
},
As: []PeeringEntryAs{
{CIDR: "192.168.1.0/24"},
},
NAT: &PeeringNAT{
Static: &PeeringNATStatic{},
},
},
},
},
"vpc2": {
Expose: []PeeringEntryExpose{
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.2.0/24"},
},
As: []PeeringEntryAs{
{CIDR: "192.168.2.0/24"},
},
NAT: &PeeringNAT{
Masquerade: &PeeringNATMasquerade{
IdleTimeout: kmetav1.Duration{Duration: time.Duration(3 * time.Minute)},
},
},
},
},
},
}

ref := common.DeepCopy()
ref.Labels = map[string]string{
ListLabelVPC("vpc1"): "true",
ListLabelVPC("vpc2"): "true",
}
ref.Spec.GatewayGroup = DefaultGatewayGroup
peering := common.DeepCopy()
peering.Default()
assert.Error(t, peering.Validate(t.Context(), nil), "masquerade plus static should not be allowed")
assert.Equal(t, ref, peering)
}

Expand Down Expand Up @@ -294,6 +342,123 @@ func TestPeeringWithPortForwardNAT(t *testing.T) {
assert.Equal(t, ref, peering)
}

func TestPeeringWithPortForwardAndMasqueradeSameSideNAT(t *testing.T) {
common := &Peering{}
common.Spec.Peering = map[string]*PeeringEntry{
"vpc1": {
Expose: []PeeringEntryExpose{
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.1.0/24"},
},
As: []PeeringEntryAs{
{CIDR: "192.168.1.0/24"},
},
NAT: &PeeringNAT{
PortForward: &PeeringNATPortForward{
Ports: []PeeringNATPortForwardEntry{
{Protocol: "tcp", Port: "80", As: "8080"},
{Protocol: "udp", Port: "90-100", As: "8090-8100"},
{Port: "88", As: "8088"},
},
IdleTimeout: kmetav1.Duration{Duration: DefaultPortForwardIdleTimeout},
},
},
},
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.2.0/24"},
},
As: []PeeringEntryAs{
{CIDR: "192.168.2.0/24"},
},
NAT: &PeeringNAT{
Masquerade: &PeeringNATMasquerade{
IdleTimeout: kmetav1.Duration{Duration: time.Duration(3 * time.Minute)},
},
},
},
},
},
"vpc2": {
Expose: []PeeringEntryExpose{
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.3.0/24"},
},
},
},
},
}

ref := common.DeepCopy()
ref.Labels = map[string]string{
ListLabelVPC("vpc1"): "true",
ListLabelVPC("vpc2"): "true",
}
ref.Spec.GatewayGroup = DefaultGatewayGroup
peering := common.DeepCopy()
peering.Default()
assert.NoError(t, peering.Validate(t.Context(), nil), "peering should be valid")
assert.Equal(t, ref, peering)
}

func TestPeeringWithPortForwardAndMasqueradeNAT(t *testing.T) {
common := &Peering{}
common.Spec.Peering = map[string]*PeeringEntry{
"vpc1": {
Expose: []PeeringEntryExpose{
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.1.0/24"},
},
As: []PeeringEntryAs{
{CIDR: "192.168.1.0/24"},
},
NAT: &PeeringNAT{
PortForward: &PeeringNATPortForward{
Ports: []PeeringNATPortForwardEntry{
{Protocol: "tcp", Port: "80", As: "8080"},
{Protocol: "udp", Port: "90-100", As: "8090-8100"},
{Port: "88", As: "8088"},
},
IdleTimeout: kmetav1.Duration{Duration: DefaultPortForwardIdleTimeout},
},
},
},
},
},
"vpc2": {
Expose: []PeeringEntryExpose{
{
IPs: []PeeringEntryIP{
{CIDR: "10.0.2.0/24"},
},
As: []PeeringEntryAs{
{CIDR: "192.168.2.0/24"},
},
NAT: &PeeringNAT{
Masquerade: &PeeringNATMasquerade{
IdleTimeout: kmetav1.Duration{Duration: time.Duration(3 * time.Minute)},
},
},
},
},
},
}

ref := common.DeepCopy()
ref.Labels = map[string]string{
ListLabelVPC("vpc1"): "true",
ListLabelVPC("vpc2"): "true",
}
ref.Spec.GatewayGroup = DefaultGatewayGroup
peering := common.DeepCopy()
peering.Default()
assert.Error(t, peering.Validate(t.Context(), nil), "masquerade + portForward should not be allowed")
assert.Equal(t, ref, peering)
}

func TestValidateDefaultDestination(t *testing.T) {
for _, tt := range []struct {
name string
Expand Down
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