Use NLB Subnet CIDRs instead of VPC CIDRs in updateInstanceSecurityGr…

…oupsForNLB

Signed-off-by: Pedro Tôrres <t0rr3sp3dr0@gmail.com>

staging/src/k8s.io/legacy-cloud-providers/aws/aws.go

@@ -3675,6 +3675,27 @@ func buildListener(port v1.ServicePort, annotations map[string]string, sslPorts
 	return listener, nil
 }
 
+func (c *Cloud) getSubnetCidrs(subnetIDs []string) ([]string, error) {
+	request := &ec2.DescribeSubnetsInput{}
+	for _, subnetID := range subnetIDs {
+		request.SubnetIds = append(request.SubnetIds, aws.String(subnetID))
+	}
+
+	subnets, err := c.ec2.DescribeSubnets(request)
+	if err != nil {
+		return nil, fmt.Errorf("error querying Subnet for ELB: %q", err)
+	}
+	if len(subnets) != len(subnetIDs) {
+		return nil, fmt.Errorf("error querying Subnet for ELB, got %d subnets for %v", len(subnets), subnetIDs)
+	}
+
+	cidrs := make([]string, 0, len(subnets))
+	for _, subnet := range subnets {
+		cidrs = append(cidrs, aws.StringValue(subnet.CidrBlock))
+	}
+	return cidrs, nil
+}
+
 // EnsureLoadBalancer implements LoadBalancer.EnsureLoadBalancer
 func (c *Cloud) EnsureLoadBalancer(ctx context.Context, clusterName string, apiService *v1.Service, nodes []*v1.Node) (*v1.LoadBalancerStatus, error) {
 	annotations := apiService.Annotations
@@ -3804,6 +3825,12 @@ func (c *Cloud) EnsureLoadBalancer(ctx context.Context, clusterName string, apiS
 			return nil, err
 		}
 
+		subnetCidrs, err := c.getSubnetCidrs(subnetIDs)
+		if err != nil {
+			klog.Errorf("Error getting subnet cidrs: %q", err)
+			return nil, err
+		}
+
 		sourceRangeCidrs := []string{}
 		for cidr := range sourceRanges {
 			sourceRangeCidrs = append(sourceRangeCidrs, cidr)
@@ -3812,7 +3839,7 @@ func (c *Cloud) EnsureLoadBalancer(ctx context.Context, clusterName string, apiS
 			sourceRangeCidrs = append(sourceRangeCidrs, "0.0.0.0/0")
 		}
 
-		err = c.updateInstanceSecurityGroupsForNLB(loadBalancerName, instances, sourceRangeCidrs, v2Mappings)
+		err = c.updateInstanceSecurityGroupsForNLB(loadBalancerName, instances, subnetCidrs, sourceRangeCidrs, v2Mappings)
 		if err != nil {
 			klog.Warningf("Error opening ingress rules for the load balancer to the instances: %q", err)
 			return nil, err
@@ -4383,7 +4410,7 @@ func (c *Cloud) EnsureLoadBalancerDeleted(ctx context.Context, clusterName strin
 			}
 		}
 
-		return c.updateInstanceSecurityGroupsForNLB(loadBalancerName, nil, nil, nil)
+		return c.updateInstanceSecurityGroupsForNLB(loadBalancerName, nil, nil, nil, nil)
 	}
 
 	lb, err := c.describeLoadBalancer(loadBalancerName)

staging/src/k8s.io/legacy-cloud-providers/aws/aws_loadbalancer.go

@@ -716,30 +716,9 @@ func (c *Cloud) ensureTargetGroup(targetGroup *elbv2.TargetGroup, serviceName ty
 	return targetGroup, nil
 }
 
-func (c *Cloud) getVpcCidrBlocks() ([]string, error) {
-	vpcs, err := c.ec2.DescribeVpcs(&ec2.DescribeVpcsInput{
-		VpcIds: []*string{aws.String(c.vpcID)},
-	})
-	if err != nil {
-		return nil, fmt.Errorf("error querying VPC for ELB: %q", err)
-	}
-	if len(vpcs.Vpcs) != 1 {
-		return nil, fmt.Errorf("error querying VPC for ELB, got %d vpcs for %s", len(vpcs.Vpcs), c.vpcID)
-	}
-
-	cidrBlocks := make([]string, 0, len(vpcs.Vpcs[0].CidrBlockAssociationSet))
-	for _, cidr := range vpcs.Vpcs[0].CidrBlockAssociationSet {
-		if aws.StringValue(cidr.CidrBlockState.State) != ec2.VpcCidrBlockStateCodeAssociated {
-			continue
-		}
-		cidrBlocks = append(cidrBlocks, aws.StringValue(cidr.CidrBlock))
-	}
-	return cidrBlocks, nil
-}
-
 // updateInstanceSecurityGroupsForNLB will adjust securityGroup's settings to allow inbound traffic into instances from clientCIDRs and portMappings.
 // TIP: if either instances or clientCIDRs or portMappings are nil, then the securityGroup rules for lbName are cleared.
-func (c *Cloud) updateInstanceSecurityGroupsForNLB(lbName string, instances map[InstanceID]*ec2.Instance, clientCIDRs []string, portMappings []nlbPortMapping) error {
+func (c *Cloud) updateInstanceSecurityGroupsForNLB(lbName string, instances map[InstanceID]*ec2.Instance, subnetCIDRs []string, clientCIDRs []string, portMappings []nlbPortMapping) error {
 	if c.cfg.Global.DisableSecurityGroupIngress {
 		return nil
 	}
@@ -787,14 +766,10 @@ func (c *Cloud) updateInstanceSecurityGroupsForNLB(lbName string, instances map[
 		}
 		clientRuleAnnotation := fmt.Sprintf("%s=%s", NLBClientRuleDescription, lbName)
 		healthRuleAnnotation := fmt.Sprintf("%s=%s", NLBHealthCheckRuleDescription, lbName)
-		vpcCIDRs, err := c.getVpcCidrBlocks()
-		if err != nil {
-			return err
-		}
 		for sgID, sg := range clusterSGs {
 			sgPerms := NewIPPermissionSet(sg.IpPermissions...).Ungroup()
 			if desiredSGIDs.Has(sgID) {
-				if err := c.updateInstanceSecurityGroupForNLBTraffic(sgID, sgPerms, healthRuleAnnotation, "tcp", healthCheckPorts, vpcCIDRs); err != nil {
+				if err := c.updateInstanceSecurityGroupForNLBTraffic(sgID, sgPerms, healthRuleAnnotation, "tcp", healthCheckPorts, subnetCIDRs); err != nil {
 					return err
 				}
 				if err := c.updateInstanceSecurityGroupForNLBTraffic(sgID, sgPerms, clientRuleAnnotation, clientProtocol, clientPorts, clientCIDRs); err != nil {