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rule_translate.go
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rule_translate.go
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// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Cilium
package k8s
import (
"fmt"
"net"
"net/netip"
"github.com/cilium/cilium/pkg/k8s/slim/k8s/apis/labels"
"github.com/cilium/cilium/pkg/policy"
"github.com/cilium/cilium/pkg/policy/api"
)
var _ policy.Translator = RuleTranslator{}
// RuleTranslator implements pkg/policy.Translator interface
// Translate populates/depopulates given rule with ToCIDR rules
// Based on provided service/endpoint
type RuleTranslator struct {
Service ServiceID
Endpoint Endpoints
ServiceLabels map[string]string
Revert bool
AllocatePrefixes bool
}
// Translate calls TranslateEgress on all r.Egress rules
func (k RuleTranslator) Translate(r *api.Rule, result *policy.TranslationResult) error {
for egressIndex := range r.Egress {
err := k.TranslateEgress(&r.Egress[egressIndex], result)
if err != nil {
return err
}
}
return nil
}
// TranslateEgress populates/depopulates egress rules with ToCIDR entries based
// on toService entries
func (k RuleTranslator) TranslateEgress(r *api.EgressRule, result *policy.TranslationResult) error {
defer r.SetAggregatedSelectors()
err := k.depopulateEgress(r, result)
if err != nil {
return err
}
if !k.Revert {
err := k.populateEgress(r, result)
if err != nil {
return err
}
}
return nil
}
func (k RuleTranslator) populateEgress(r *api.EgressRule, result *policy.TranslationResult) error {
for _, service := range r.ToServices {
if k.serviceMatches(service) {
if backendPrefixes, err := k.generateToCidrFromEndpoint(r, k.Endpoint, k.AllocatePrefixes); err != nil {
return err
} else {
result.PrefixesToAdd = append(result.PrefixesToAdd, backendPrefixes...)
}
// TODO: generateToPortsFromEndpoint when ToPorts and ToCIDR are compatible
}
}
return nil
}
func (k RuleTranslator) depopulateEgress(r *api.EgressRule, result *policy.TranslationResult) error {
for _, service := range r.ToServices {
// NumToServicesRules are only counted in depopulate to avoid
// counting rules twice
result.NumToServicesRules++
if k.serviceMatches(service) {
if prefixesToRelease, err := k.deleteToCidrFromEndpoint(r, k.Endpoint, k.AllocatePrefixes); err != nil {
return err
} else {
result.PrefixesToRelease = append(result.PrefixesToRelease, prefixesToRelease...)
}
// TODO: generateToPortsFromEndpoint when ToPorts and ToCIDR are compatible
}
}
return nil
}
func (k RuleTranslator) serviceMatches(service api.Service) bool {
if service.K8sServiceSelector != nil {
es := api.EndpointSelector(service.K8sServiceSelector.Selector)
es.SyncRequirementsWithLabelSelector()
esMatches := es.Matches(labels.Set(k.ServiceLabels))
return esMatches &&
(service.K8sServiceSelector.Namespace == k.Service.Namespace || service.K8sServiceSelector.Namespace == "")
}
if service.K8sService != nil {
return service.K8sService.ServiceName == k.Service.Name &&
(service.K8sService.Namespace == k.Service.Namespace || service.K8sService.Namespace == "")
}
return false
}
// generateToCidrFromEndpoint takes an egress rule and populates it with
// ToCIDR rules based on provided endpoint object
func (k RuleTranslator) generateToCidrFromEndpoint(
egress *api.EgressRule,
endpoint Endpoints,
allocatePrefixes bool) ([]netip.Prefix, error) {
var prefixes []netip.Prefix
// allocatePrefixes if true here implies that this translation is
// occurring after policy import. This means that the CIDRs were not
// known at that time, so the IPCache hasn't been informed about them.
// In this case, it's the job of this Translator to notify the IPCache.
if allocatePrefixes {
prefixes = endpoint.Prefixes()
}
// This will generate one-address CIDRs consisting of endpoint backend ip
for addrCluster := range endpoint.Backends {
epIP := addrCluster.Addr()
found := false
for _, c := range egress.ToCIDRSet {
prefix, err := netip.ParsePrefix(string(c.Cidr))
if err != nil {
return nil, err
}
if prefix.Contains(epIP) {
found = true
break
}
}
if !found {
mask := 32
if epIP.Is6() {
mask = 128
}
cidr := netip.PrefixFrom(epIP, mask)
egress.ToCIDRSet = append(egress.ToCIDRSet, api.CIDRRule{
Cidr: api.CIDR(cidr.String()),
Generated: true,
})
}
}
return prefixes, nil
}
// deleteToCidrFromEndpoint takes an egress rule and removes ToCIDR rules
// matching endpoint. Returns an error if any of the backends are malformed.
//
// If all backends are valid, returns any CIDR mappings that are being removed
// from the policy. The caller must attempt to release this via the IPCache
// identity release functions.
func (k RuleTranslator) deleteToCidrFromEndpoint(
egress *api.EgressRule,
endpoint Endpoints,
releasePrefixes bool) ([]netip.Prefix, error) {
var toReleasePrefixes []netip.Prefix
delCIDRRules := make(map[int]*api.CIDRRule, len(egress.ToCIDRSet))
for addrCluster := range endpoint.Backends {
ipStr := addrCluster.Addr().String()
epIP := net.ParseIP(ipStr)
if epIP == nil {
return nil, fmt.Errorf("unable to parse ip: %s", ipStr)
}
for i, c := range egress.ToCIDRSet {
if _, ok := delCIDRRules[i]; ok {
// it's already going to be deleted so we can continue
continue
}
_, cidr, err := net.ParseCIDR(string(c.Cidr))
if err != nil {
return nil, err
}
// delete all generated CIDRs for a CIDR that match the given
// endpoint
if c.Generated && cidr.Contains(epIP) {
delCIDRRules[i] = &egress.ToCIDRSet[i]
}
}
if len(delCIDRRules) == len(egress.ToCIDRSet) {
break
}
}
// If no rules were deleted we can do an early return here and avoid doing
// the useless operations below.
if len(delCIDRRules) == 0 {
return toReleasePrefixes, nil
}
if releasePrefixes {
delSlice := make([]api.CIDRRule, 0, len(egress.ToCIDRSet))
for _, delCIDRRule := range delCIDRRules {
delSlice = append(delSlice, *delCIDRRule)
}
toReleasePrefixes = policy.GetPrefixesFromCIDRSet(delSlice)
}
// if endpoint is not in CIDR or it's not generated it's ok to retain it
newCIDRRules := make([]api.CIDRRule, 0, len(egress.ToCIDRSet)-len(delCIDRRules))
for i, c := range egress.ToCIDRSet {
// If the rule was deleted then it shouldn't be re-added
if _, ok := delCIDRRules[i]; ok {
continue
}
newCIDRRules = append(newCIDRRules, c)
}
egress.ToCIDRSet = newCIDRRules
return toReleasePrefixes, nil
}
// PreprocessRules translates rules that apply to headless services
func PreprocessRules(r api.Rules, cache *ServiceCache) error {
cache.mutex.Lock()
defer cache.mutex.Unlock()
for _, rule := range r {
// Translate only handles egress rules
if rule.Egress == nil {
continue
}
for ns, ep := range cache.endpoints {
svc, ok := cache.services[ns]
if ok && svc.IsExternal() {
eps := ep.GetEndpoints()
if eps != nil {
t := NewK8sTranslator(ns, *eps, false, svc.Labels, false)
// We don't need to check the translation result here because the k8s
// RuleTranslator above sets allocatePrefixes to be false.
err := t.Translate(rule, &policy.TranslationResult{})
if err != nil {
return err
}
}
}
}
}
return nil
}
// NewK8sTranslator returns RuleTranslator.
// If allocatePrefixes is set to true, then translation calls will return
// prefixes that need to be allocated or deallocated.
func NewK8sTranslator(
serviceInfo ServiceID,
endpoint Endpoints,
revert bool,
labels map[string]string,
allocatePrefixes bool) RuleTranslator {
return RuleTranslator{
Service: serviceInfo,
Endpoint: endpoint,
ServiceLabels: labels,
Revert: revert,
AllocatePrefixes: allocatePrefixes,
}
}