From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E27AC6778F for ; Fri, 27 Jul 2018 22:27:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0006720647 for ; Fri, 27 Jul 2018 22:27:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0006720647 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388845AbeG0Xvd (ORCPT ); Fri, 27 Jul 2018 19:51:33 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:41350 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730850AbeG0Xvd (ORCPT ); Fri, 27 Jul 2018 19:51:33 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 35AB34025063; Fri, 27 Jul 2018 22:27:36 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-116.rdu2.redhat.com [10.10.120.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 408602156701; Fri, 27 Jul 2018 22:27:35 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <153271267980.9458.7640156373438016898.stgit@warthog.procyon.org.uk> <153271287586.9458.6001928723332685410.stgit@warthog.procyon.org.uk> <7034.1532728300@warthog.procyon.org.uk> To: Andy Lutomirski Cc: dhowells@redhat.com, Al Viro , Linux API , Linus Torvalds , Linux FS Devel , LKML Subject: Re: [PATCH 29/38] vfs: syscall: Add fsconfig() for configuring and managing a context [ver #10] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <11037.1532730454.1@warthog.procyon.org.uk> Date: Fri, 27 Jul 2018 23:27:34 +0100 Message-ID: <11038.1532730454@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 27 Jul 2018 22:27:36 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 27 Jul 2018 22:27:36 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dhowells@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Lutomirski wrote: > > [*] Not without a 6-arg syscall or some other way of passing it. > > Are there still architectures that have problems with 6-arg syscalls? As I understand it, 6-arg syscalls are frowned upon. > I suppose that, as long as there is never a case where fsconfig_set_path and > fsconfig_set_fd both succeed, then it's not a big deal. fsconfig_set_path/path_empty requires the 'value' argument to point to a string, possibly "", and fsconfig_set_fd requires it to be NULL. I can't stop you from doing: fd = open("/some/path", O_PATH); fsconfig(fsfd, fsconfig_set_fd, "fd", NULL, fd); or: fd = open("/dev/sda6", O_RDWR); fsconfig(fsfd, fsconfig_set_path_empty, "foo", "", fd); The first should fail because I'm using fget() not fget_raw() and the second will pass the string and fd number to the filesystem, which will presumably then call fs_lookup_param() to invoke pathwalk upon it - which will likely also fail. David