[v11.3.x] Alerting: Fix per-receiver RBAC for receivers with long names (#95165)

Alerting: Fix per-receiver RBAC for receivers with long names (#95084)

* Implement uidToResourceID

* add middleware

* Move uidToResourceID to alerting package

* Only hash uid if it's too long

* Use hashed uid in access control

* Move ReceiverUidToResourceId to ScopeProvider

* resolve uid in middleware only if param exists

* Tests

* Linting

---------

Co-authored-by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>
(cherry picked from commit 4aad44e848)

Co-authored-by: Matthew Jacobson <matthew.jacobson@grafana.com>

pkg/services/ngalert/accesscontrol/receivers.go

@@ -2,10 +2,14 @@ package accesscontrol
 
 import (
 	"context"
+	// #nosec G505 Used only for shortening the uid, not for security purposes.
+	"crypto/sha1"
+	"encoding/hex"
 
 	"github.com/grafana/grafana/pkg/apimachinery/identity"
 	ac "github.com/grafana/grafana/pkg/services/accesscontrol"
 	"github.com/grafana/grafana/pkg/services/ngalert/models"
+	"github.com/grafana/grafana/pkg/util"
 )
 
 const (
@@ -13,10 +17,30 @@ const (
 )
 
 var (
-	ScopeReceiversProvider = ac.NewScopeProvider(ScopeReceiversRoot)
+	ScopeReceiversProvider = ReceiverScopeProvider{ac.NewScopeProvider(ScopeReceiversRoot)}
 	ScopeReceiversAll      = ScopeReceiversProvider.GetResourceAllScope()
 )
 
+type ReceiverScopeProvider struct {
+	ac.ScopeProvider
+}
+
+func (p ReceiverScopeProvider) GetResourceScopeUID(uid string) string {
+	return ScopeReceiversProvider.ScopeProvider.GetResourceScopeUID(p.GetResourceIDFromUID(uid))
+}
+
+// GetResourceIDFromUID converts a receiver uid to a resource id. This is necessary as resource ids are limited to 40 characters.
+// If the uid is already less than or equal to 40 characters, it is returned as is.
+func (p ReceiverScopeProvider) GetResourceIDFromUID(uid string) string {
+	if len(uid) <= util.MaxUIDLength {
+		return uid
+	}
+	// #nosec G505 Used only for shortening the uid, not for security purposes.
+	h := sha1.New()
+	h.Write([]byte(uid))
+	return hex.EncodeToString(h.Sum(nil))
+}
+
 // ReceiverPermission is a type for representing a receiver permission.
 type ReceiverPermission string