Merge pull request #109 from andrewbuss/keycache_active_evict

Fix "invalid key size 0" when decrypting after a delegation expires

cryptor/cryptor.go

@@ -396,9 +396,9 @@ func (encrypted *EncryptedData) wrapKey(records *passvault.Records, clearKey []b
 // unwrapKey decrypts first key in keys whose encryption keys are in keycache
 func (encrypted *EncryptedData) unwrapKey(cache *keycache.Cache, user string) (unwrappedKey []byte, names []string, err error) {
 	var (
-		keyFound  error
-		fullMatch bool = false
-		nameSet        = map[string]bool{}
+		decryptErr error
+		fullMatch  bool = false
+		nameSet         = map[string]bool{}
 	)
 
 	if len(encrypted.Predicate) == 0 {
@@ -427,7 +427,7 @@ func (encrypted *EncryptedData) unwrapKey(cache *keycache.Cache, user string) (u
 				tmpKeyValue := mwKey.Key
 				for _, mwName := range mwKey.Name {
 					pubEncrypted := encrypted.KeySetRSA[mwName]
-					if tmpKeyValue, keyFound = cache.DecryptKey(tmpKeyValue, mwName, user, encrypted.Labels, pubEncrypted.Key); keyFound != nil {
+					if tmpKeyValue, decryptErr = cache.DecryptKey(tmpKeyValue, mwName, user, encrypted.Labels, pubEncrypted.Key); decryptErr != nil {
 						break
 					}
 				}
@@ -438,7 +438,12 @@ func (encrypted *EncryptedData) unwrapKey(cache *keycache.Cache, user string) (u
 
 		if !fullMatch {
 			err = errors.New("Need more delegated keys")
-			names = nil
+			return
+		}
+
+		if decryptErr != nil {
+			err = errors.New("Failed to decrypt with all keys in keyset")
+			return
 		}
 
 		names = make([]string, 0, len(nameSet))

keycache/keycache.go

@@ -133,7 +133,11 @@ func (cache *Cache) MatchUser(name, user string, labels []string) (ActiveUser, s
 func (cache *Cache) useKey(name, user, slot string, labels []string) {
 	if val, slot, present := cache.MatchUser(name, user, labels); present {
 		val.Usage.Uses -= 1
-		cache.setUser(val, name, slot)
+		if val.Usage.Uses <= 0 {
+			delete(cache.UserKeys, DelegateIndex{name, slot})
+		} else {
+			cache.setUser(val, name, slot)
+		}
 	}
 }
 
@@ -160,7 +164,7 @@ func (cache *Cache) FlushCache() {
 // Refresh purges all expired or used up keys.
 func (cache *Cache) Refresh() {
 	for d, active := range cache.UserKeys {
-		if active.Usage.Expiry.Before(time.Now()) || active.Usage.Uses <= 0 {
+		if active.Usage.Expiry.Before(time.Now()) {
 			log.Println("Record expired", d.Name, d.Slot, active.Usage.Users, active.Usage.Labels, active.Usage.Expiry)
 			delete(cache.UserKeys, d)
 		}

keycache/keycache_test.go

@@ -70,7 +70,6 @@ func TestUsesFlush(t *testing.T) {
 		t.Fatalf("%v", err)
 	}
 
-	cache.Refresh()
 	if len(cache.UserKeys) != 0 {
 		t.Fatalf("Error in number of live keys %v", cache.UserKeys)
 	}