feat: Implement LDAP interface-specific provisioning filters (#642)

* Implement LDAP filter-based access control for interface provisioning

* test: add unit tests for LDAP interface filtering logic

* smaller improvements / cleanup

---------

Co-authored-by: jc <37738506+theguy147@users.noreply.github.com>
Co-authored-by: Christoph Haas <christoph.h@sprinternet.at>

internal/app/wireguard/wireguard_peers.go

@@ -93,6 +93,10 @@ func (m Manager) PreparePeer(ctx context.Context, id domain.InterfaceIdentifier)
 
 	currentUser := domain.GetUserInfo(ctx)
 
+	if err := m.checkInterfaceAccess(ctx, id); err != nil {
+		return nil, err
+	}
+
 	iface, err := m.db.GetInterface(ctx, id)
 	if err != nil {
 		return nil, fmt.Errorf("unable to find interface %s: %w", id, err)
@@ -188,6 +192,9 @@ func (m Manager) CreatePeer(ctx context.Context, peer *domain.Peer) (*domain.Pee
 		if err := domain.ValidateUserAccessRights(ctx, peer.UserIdentifier); err != nil {
 			return nil, err
 		}
+		if err := m.checkInterfaceAccess(ctx, peer.InterfaceIdentifier); err != nil {
+			return nil, err
+		}
 	}
 
 	sessionUser := domain.GetUserInfo(ctx)
@@ -304,6 +311,10 @@ func (m Manager) UpdatePeer(ctx context.Context, peer *domain.Peer) (*domain.Pee
 		return nil, err
 	}
 
+	if err := m.checkInterfaceAccess(ctx, existingPeer.InterfaceIdentifier); err != nil {
+		return nil, err
+	}
+
 	if err := m.validatePeerModifications(ctx, existingPeer, peer); err != nil {
 		return nil, fmt.Errorf("update not allowed: %w", err)
 	}
@@ -373,6 +384,10 @@ func (m Manager) DeletePeer(ctx context.Context, id domain.PeerIdentifier) error
 		return err
 	}
 
+	if err := m.checkInterfaceAccess(ctx, peer.InterfaceIdentifier); err != nil {
+		return err
+	}
+
 	if err := m.validatePeerDeletion(ctx, peer); err != nil {
 		return fmt.Errorf("delete not allowed: %w", err)
 	}
@@ -606,4 +621,22 @@ func (m Manager) validatePeerDeletion(ctx context.Context, _ *domain.Peer) error
 	return nil
 }
 
+func (m Manager) checkInterfaceAccess(ctx context.Context, id domain.InterfaceIdentifier) error {
+	user := domain.GetUserInfo(ctx)
+	if user.IsAdmin {
+		return nil
+	}
+
+	iface, err := m.db.GetInterface(ctx, id)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %s: %w", id, err)
+	}
+
+	if !iface.IsUserAllowed(user.Id, m.cfg) {
+		return fmt.Errorf("user %s is not allowed to access interface %s: %w", user.Id, id, domain.ErrNoPermission)
+	}
+
+	return nil
+}
+
 // endregion helper-functions