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OCPBUGS-84534: fix concurrent map race in project authorization cache #642

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1ec6f99
project: fix concurrent map race in authorization cache
sanchezl May 7, 2026
10ef6dd
project: atomic store pointer swap during cache invalidation
sanchezl May 7, 2026
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69 changes: 43 additions & 26 deletions pkg/project/auth/cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import (
"fmt"
"strings"
"sync"
"sync/atomic"
"time"

"k8s.io/klog/v2"
Expand Down Expand Up @@ -173,6 +174,14 @@ func (l syncedClusterRoleBindingLister) LastSyncResourceVersion() string {
return l.versioner.LastSyncResourceVersion()
}

// authorizationCacheStores groups the three cache stores so they can be
// swapped atomically during full cache invalidation.
type authorizationCacheStores struct {
reviewRecordStore cache.Store
userSubjectRecordStore cache.Store
groupSubjectRecordStore cache.Store
}

// AuthorizationCache maintains a cache on the set of namespaces a user or group can access.
type AuthorizationCache struct {
// allKnownNamespaces we track all the known namespaces, so we can detect deletes.
Expand All @@ -187,9 +196,7 @@ type AuthorizationCache struct {
roleBindingNamespacer SyncedRoleBindingLister
roleLastSyncResourceVersioner LastSyncResourceVersioner

reviewRecordStore cache.Store
userSubjectRecordStore cache.Store
groupSubjectRecordStore cache.Store
stores atomic.Pointer[authorizationCacheStores]

clusterBindingResourceVersions sets.String
clusterRoleResourceVersions sets.String
Expand Down Expand Up @@ -255,10 +262,6 @@ func NewAuthorizationCache(
roleBindingNamespacer: srbLister,
roleLastSyncResourceVersioner: unionLastSyncResourceVersioner{scrLister, scrbLister, srLister, srbLister},

reviewRecordStore: cache.NewStore(reviewRecordKeyFn),
userSubjectRecordStore: cache.NewStore(subjectRecordKeyFn),
groupSubjectRecordStore: cache.NewStore(subjectRecordKeyFn),

reviewer: reviewer,
skip: &neverSkipSynchronizer{},

Expand All @@ -268,6 +271,11 @@ func NewAuthorizationCache(
lastCacheInvalidation: realClock.Now(),
maxCacheLifespan: defaultMaxCacheLifespan,
}
ac.stores.Store(&authorizationCacheStores{
reviewRecordStore: cache.NewStore(reviewRecordKeyFn),
userSubjectRecordStore: cache.NewStore(subjectRecordKeyFn),
groupSubjectRecordStore: cache.NewStore(subjectRecordKeyFn),
})
ac.lastSyncResourceVersioner = namespaceLastSyncResourceVersioner
ac.syncHandler = ac.syncRequest
return ac
Expand Down Expand Up @@ -424,7 +432,7 @@ func (ac *AuthorizationCache) invalidateCache(expired bool) bool {
return invalidateCache
}

// synchronize runs a a full synchronization over the cache data. it must be run in a single-writer model, it's not thread-safe by design.
// synchronize runs a full synchronization over the cache data. It must be run in a single-writer model, it's not thread-safe by design.
func (ac *AuthorizationCache) synchronize() {
expired := ac.cacheHasExpired()
// if none of our internal reflectors changed, then we can skip reviewing the cache
Expand All @@ -434,9 +442,10 @@ func (ac *AuthorizationCache) synchronize() {
}

// by default, we update our current caches and do an incremental change
userSubjectRecordStore := ac.userSubjectRecordStore
groupSubjectRecordStore := ac.groupSubjectRecordStore
reviewRecordStore := ac.reviewRecordStore
currentStores := ac.stores.Load()
userSubjectRecordStore := currentStores.userSubjectRecordStore
groupSubjectRecordStore := currentStores.groupSubjectRecordStore
reviewRecordStore := currentStores.reviewRecordStore

// if there was a global change that forced complete invalidation, we rebuild our cache and do a fast swap at end
invalidateCache := ac.invalidateCache(expired)
Expand All @@ -453,11 +462,13 @@ func (ac *AuthorizationCache) synchronize() {
ac.synchronizeRoleBindings(userSubjectRecordStore, groupSubjectRecordStore, reviewRecordStore)
ac.purgeDeletedNamespaces(ac.allKnownNamespaces, newKnownNamespaces, userSubjectRecordStore, groupSubjectRecordStore, reviewRecordStore)

// if we did a full rebuild, now we swap the fully rebuilt cache
// if we did a full rebuild, now we swap the fully rebuilt cache atomically
if invalidateCache {
ac.userSubjectRecordStore = userSubjectRecordStore
ac.groupSubjectRecordStore = groupSubjectRecordStore
ac.reviewRecordStore = reviewRecordStore
ac.stores.Store(&authorizationCacheStores{
userSubjectRecordStore: userSubjectRecordStore,
groupSubjectRecordStore: groupSubjectRecordStore,
reviewRecordStore: reviewRecordStore,
})
}
ac.allKnownNamespaces = newKnownNamespaces

Expand Down Expand Up @@ -511,14 +522,17 @@ func (ac *AuthorizationCache) List(userInfo user.Info, selector labels.Selector)
user := userInfo.GetName()
groups := userInfo.GetGroups()

obj, exists, _ := ac.userSubjectRecordStore.GetByKey(user)
// snapshot the stores pointer once so we read from a consistent pair
stores := ac.stores.Load()

obj, exists, _ := stores.userSubjectRecordStore.GetByKey(user)
if exists {
subjectRecord := obj.(*subjectRecord)
keys.Insert(subjectRecord.namespaces.List()...)
}

for _, group := range groups {
obj, exists, _ := ac.groupSubjectRecordStore.GetByKey(group)
obj, exists, _ := stores.groupSubjectRecordStore.GetByKey(group)
if exists {
subjectRecord := obj.(*subjectRecord)
keys.Insert(subjectRecord.namespaces.List()...)
Expand Down Expand Up @@ -600,10 +614,13 @@ func deleteNamespaceFromSubjects(subjectRecordStore cache.Store, subjects []stri
for _, subject := range subjects {
obj, exists, _ := subjectRecordStore.GetByKey(subject)
if exists {
subjectRecord := obj.(*subjectRecord)
delete(subjectRecord.namespaces, namespace)
if len(subjectRecord.namespaces) == 0 {
subjectRecordStore.Delete(subjectRecord)
old := obj.(*subjectRecord)
newNamespaces := sets.NewString(old.namespaces.UnsortedList()...)
newNamespaces.Delete(namespace)
if len(newNamespaces) == 0 {
subjectRecordStore.Delete(old)
} else {
subjectRecordStore.Update(&subjectRecord{subject: subject, namespaces: newNamespaces})
}
}
}
Expand All @@ -612,15 +629,15 @@ func deleteNamespaceFromSubjects(subjectRecordStore cache.Store, subjects []stri
// addSubjectsToNamespace adds the specified namespace to each subject
func addSubjectsToNamespace(subjectRecordStore cache.Store, subjects []string, namespace string) {
for _, subject := range subjects {
var item *subjectRecord
obj, exists, _ := subjectRecordStore.GetByKey(subject)
if exists {
item = obj.(*subjectRecord)
old := obj.(*subjectRecord)
newNamespaces := sets.NewString(old.namespaces.UnsortedList()...)
newNamespaces.Insert(namespace)
subjectRecordStore.Update(&subjectRecord{subject: subject, namespaces: newNamespaces})
} else {
item = &subjectRecord{subject: subject, namespaces: sets.NewString()}
subjectRecordStore.Add(item)
subjectRecordStore.Add(&subjectRecord{subject: subject, namespaces: sets.NewString(namespace)})
}
item.namespaces.Insert(namespace)
}
}

Expand Down
131 changes: 131 additions & 0 deletions pkg/project/auth/cache_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package auth
import (
"fmt"
"strconv"
"sync"
"testing"
"time"

Expand Down Expand Up @@ -436,3 +437,133 @@ func TestAuthorizationCache_invalidateCache(t *testing.T) {
})
}
}

func TestAuthorizationCacheRace(t *testing.T) {
namespaceList := corev1.NamespaceList{
Items: []corev1.Namespace{
{ObjectMeta: metav1.ObjectMeta{Name: "foo", ResourceVersion: "1"}},
{ObjectMeta: metav1.ObjectMeta{Name: "bar", ResourceVersion: "2"}},
{ObjectMeta: metav1.ObjectMeta{Name: "baz", ResourceVersion: "3"}},
},
}
mockKubeClient := fake.NewSimpleClientset(&namespaceList)

reviewer := &mockReviewer{
expectedResults: map[string]*mockReview{
"foo": {
users: []string{alice.GetName(), bob.GetName()},
groups: eve.GetGroups(),
},
"bar": {
users: []string{frank.GetName(), eve.GetName()},
groups: []string{"random"},
},
"baz": {
users: []string{alice.GetName()},
groups: []string{"employee"},
},
},
}

informers := informers.NewSharedInformerFactory(mockKubeClient, controller.NoResyncPeriodFunc())
nsIndexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{})
nsLister := corev1listers.NewNamespaceLister(nsIndexer)

authorizationCache := NewAuthorizationCache(
nsLister,
informers.Core().V1().Namespaces().Informer(),
reviewer,
informers.Rbac().V1(),
)
for i := range namespaceList.Items {
nsIndexer.Add(&namespaceList.Items[i])
}

// seed the cache
authorizationCache.synchronize()

stop := make(chan struct{})
var wg sync.WaitGroup

// writer goroutine: continuously synchronize, toggling access
wg.Add(1)
go func() {
defer wg.Done()
rv := 10
for {
select {
case <-stop:
return
default:
}
// toggle access patterns to force map mutations
if rv%2 == 0 {
reviewer.expectedResults["foo"] = &mockReview{
users: []string{alice.GetName(), bob.GetName()},
groups: eve.GetGroups(),
}
reviewer.expectedResults["baz"] = &mockReview{
users: []string{frank.GetName()},
groups: []string{},
}
} else {
reviewer.expectedResults["foo"] = &mockReview{
users: []string{frank.GetName()},
groups: []string{"random"},
}
reviewer.expectedResults["baz"] = &mockReview{
users: []string{alice.GetName(), eve.GetName()},
groups: []string{"employee"},
}
}
rv++
for i := range namespaceList.Items {
ns := namespaceList.Items[i]
ns.ResourceVersion = strconv.Itoa(rv)
nsIndexer.Update(&ns)
}
authorizationCache.synchronize()
}
}()

// reader goroutines: continuously call List
users := []user.Info{alice, bob, eve, frank}
for _, u := range users {
u := u
wg.Add(1)
go func() {
defer wg.Done()
for {
select {
case <-stop:
return
default:
}
_, err := authorizationCache.List(u, labels.Everything())
if err != nil {
t.Errorf("List(%s) returned error: %v", u.GetName(), err)
return
}
}
}()
}

time.Sleep(2 * time.Second)
close(stop)
wg.Wait()
}

func BenchmarkAddSubjectsToNamespace(b *testing.B) {
for _, namespaceCount := range []int{10, 100, 1000} {
b.Run(fmt.Sprintf("namespaces=%d", namespaceCount), func(b *testing.B) {
subjects := []string{"alice", "bob", "eve", "frank", "grace"}
b.ResetTimer()
for i := 0; i < b.N; i++ {
store := cache.NewStore(subjectRecordKeyFn)
for ns := 0; ns < namespaceCount; ns++ {
addSubjectsToNamespace(store, subjects, fmt.Sprintf("namespace-%d", ns))
}
}
})
}
}