fix: scope group share child permission updates to usergroup

Signed-off-by: kristian-zendato <kristian.zendato@nextcloud.com>

Author: kristian-zendato

build/integration/sharing_features/sharing-v1-part3.feature

@@ -607,6 +607,6 @@ Feature: sharing
       | id | A_NUMBER |
       | item_source | A_NUMBER |
       | share_type | 3 |
-      | permissions | 23 |
+      | permissions | 31 |
       | file_target | /subfolder |
       | expireDate  |            |

lib/private/Share20/DefaultShareProvider.php

@@ -257,11 +257,13 @@ public function update(\OCP\Share\IShare $share) {
 				->executeStatement();
 
 			/*
-			 * Now update the permissions for all children that have not set it to 0
+			 * Now update the permissions for all user-group children that have not set it to 0.
+			 * Link shares also use parent for display (Manager::setLinkParent) and must be excluded.
 			 */
 			$qb = $this->dbConn->getQueryBuilder();
 			$qb->update('share')
 				->where($qb->expr()->eq('parent', $qb->createNamedParameter($share->getId())))
+				->andWhere($qb->expr()->eq('share_type', $qb->createNamedParameter(IShare::TYPE_USERGROUP)))
 				->andWhere($qb->expr()->neq('permissions', $qb->createNamedParameter(0)))
 				->set('permissions', $qb->createNamedParameter($share->getPermissions()))
 				->set('attributes', $qb->createNamedParameter($shareAttributes))