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Restrict access to EC2 metadata #22826

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merged 1 commit into from
May 16, 2019
Merged

Restrict access to EC2 metadata #22826

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7 changes: 6 additions & 1 deletion cmd/sdn-cni-plugin/openshift-sdn_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -120,10 +120,15 @@ func (p *cniPlugin) testCmdAdd(args *skel.CmdArgs) (types.Result, error) {
}

var iptablesCommands = [][]string{
// Block MCS
{"-A", "OUTPUT", "-p", "tcp", "-m", "tcp", "--dport", "22623", "-j", "REJECT"},
{"-A", "OUTPUT", "-p", "tcp", "-m", "tcp", "--dport", "22624", "-j", "REJECT"},
{"-A", "FORWARD", "-p", "tcp", "-m", "tcp", "--dport", "22623", "-j", "REJECT"},
{"-A", "FORWARD", "-p", "tcp", "-m", "tcp", "--dport", "22624", "-j", "REJECT"},

// Block cloud metadata IP
{"-A", "OUTPUT", "-d", "169.254.169.254", "-j", "REJECT"},
{"-A", "FORWARD", "-d", "169.254.169.254", "-j", "REJECT"},
}

func (p *cniPlugin) CmdAdd(args *skel.CmdArgs) error {
Expand Down Expand Up @@ -234,7 +239,7 @@ func (p *cniPlugin) CmdAdd(args *skel.CmdArgs) error {
}
}

// HACK: block access to MCS until we can secure it properly
// Block access to certain things
for _, args := range iptablesCommands {
out, err := exec.Command("iptables", args...).CombinedOutput()
if err != nil {
Expand Down
32 changes: 21 additions & 11 deletions pkg/network/admission/restrictedendpoints/endpoint_admission.go
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Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,6 @@ type restrictedEndpointsAdmission struct {

authorizer authorizer.Authorizer
restrictedNetworks []*net.IPNet
restrictedPorts []kapi.EndpointPort
}

var _ = initializer.WantsAuthorizer(&restrictedEndpointsAdmission{})
Expand All @@ -87,10 +86,6 @@ func NewRestrictedEndpointsAdmission(restrictedNetworks []*net.IPNet) *restricte
return &restrictedEndpointsAdmission{
Handler: admission.NewHandler(admission.Create, admission.Update),
restrictedNetworks: restrictedNetworks,
restrictedPorts: []kapi.EndpointPort{
{Protocol: kapi.ProtocolTCP, Port: 22623},
{Protocol: kapi.ProtocolTCP, Port: 22624},
},
}
}

Expand All @@ -105,14 +100,26 @@ func (r *restrictedEndpointsAdmission) ValidateInitialization() error {
return nil
}

func (r *restrictedEndpointsAdmission) findRestrictedIP(ep *kapi.Endpoints) error {
var (
defaultRestrictedPorts = []kapi.EndpointPort{
// MCS ports
{Protocol: kapi.ProtocolTCP, Port: 22623},
{Protocol: kapi.ProtocolTCP, Port: 22624},
}
defaultRestrictedNetworks = []*net.IPNet{
// IPv4 link-local range 169.254.0.0/16 (including cloud metadata IP)
{IP: net.ParseIP("169.254.0.0"), Mask: net.CIDRMask(16, 32)},
}
)

func (r *restrictedEndpointsAdmission) findRestrictedIP(ep *kapi.Endpoints, restricted []*net.IPNet) error {
for _, subset := range ep.Subsets {
for _, addr := range subset.Addresses {
ip := net.ParseIP(addr.IP)
if ip == nil {
continue
}
for _, net := range r.restrictedNetworks {
for _, net := range restricted {
if net.Contains(ip) {
return fmt.Errorf("endpoint address %s is not allowed", addr.IP)
}
Expand All @@ -122,10 +129,10 @@ func (r *restrictedEndpointsAdmission) findRestrictedIP(ep *kapi.Endpoints) erro
return nil
}

func (r *restrictedEndpointsAdmission) findRestrictedPort(ep *kapi.Endpoints) error {
func (r *restrictedEndpointsAdmission) findRestrictedPort(ep *kapi.Endpoints, restricted []kapi.EndpointPort) error {
for _, subset := range ep.Subsets {
for _, port := range subset.Ports {
for _, restricted := range r.restrictedPorts {
for _, restricted := range restricted {
if port.Protocol == restricted.Protocol && port.Port == restricted.Port {
return fmt.Errorf("endpoint port %s:%d is not allowed", string(port.Protocol), port.Port)
}
Expand Down Expand Up @@ -164,9 +171,12 @@ func (r *restrictedEndpointsAdmission) Validate(a admission.Attributes) error {
return nil
}

restrictedErr := r.findRestrictedIP(ep)
restrictedErr := r.findRestrictedIP(ep, r.restrictedNetworks)
if restrictedErr == nil {
restrictedErr = r.findRestrictedIP(ep, defaultRestrictedNetworks)
}
if restrictedErr == nil {
restrictedErr = r.findRestrictedPort(ep)
restrictedErr = r.findRestrictedPort(ep, defaultRestrictedPorts)
}
if restrictedErr == nil {
return nil
Expand Down
3 changes: 3 additions & 0 deletions pkg/network/node/ovscontroller.go
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Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,9 @@ func (oc *ovsController) SetupOVS(clusterNetworkCIDR []string, serviceNetworkCID
otx.AddFlow("table=30, priority=100, ip, nw_dst=%s, actions=goto_table:90", clusterCIDR)
}

// Link-local traffic
otx.AddFlow("table=30, priority=75, ip, nw_dst=169.254.0.0/16, actions=drop")

// Multicast coming from the VXLAN
otx.AddFlow("table=30, priority=50, in_port=1, ip, nw_dst=224.0.0.0/4, actions=goto_table:120")
// Multicast coming from local pods
Expand Down