Match against share target and node path

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/private/Share20/Manager.php

@@ -52,6 +52,7 @@
 use OCP\Files\IRootFolder;
 use OCP\Files\Mount\IMountManager;
 use OCP\Files\Node;
+use OCP\Files\NotFoundException;
 use OCP\HintException;
 use OCP\IConfig;
 use OCP\IGroupManager;
@@ -292,10 +293,18 @@ protected function generalCreateChecks(IShare $share) {
 		$permissions = 0;
 
 		if (!$isFederatedShare && $share->getNode()->getOwner() && $share->getNode()->getOwner()->getUID() !== $share->getSharedBy()) {
-			$userMounts = array_filter($userFolder->getById($share->getNode()->getId()), function ($mount) use ($share) {
+			try {
+				$targetNode = $share->getTarget() ? $userFolder->get($share->getTarget()) : null;
+			} catch (NotFoundException $e) {
+				$targetNode = null;
+			}
+			$userMounts = array_filter($userFolder->getById($share->getNode()->getId()), function ($mount) use ($share, $targetNode) {
 				// We need to filter since there might be other mountpoints that contain the file
 				// e.g. if the user has access to the same external storage that the file is originating from
-				return $mount->getStorage()->instanceOfStorage(ISharedStorage::class) && $mount->getPath() === $share->getNode()->getPath();
+				return $mount->getStorage()->instanceOfStorage(ISharedStorage::class) && (
+					$targetNode ? $targetNode->getPath() === $mount->getPath() :
+						$mount->getPath() === $share->getNode()->getPath()
+				);
 			});
 			$userMount = array_shift($userMounts);
 			if ($userMount === null) {