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=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=unavailable 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 7D684C04AB1 for ; Sat, 11 May 2019 08:40:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58307217D6 for ; Sat, 11 May 2019 08:40:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727935AbfEKIkb (ORCPT ); Sat, 11 May 2019 04:40:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37374 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725887AbfEKIkb (ORCPT ); Sat, 11 May 2019 04:40:31 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4FA053092654; Sat, 11 May 2019 08:40:31 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-61.rdu2.redhat.com [10.10.120.61]) by smtp.corp.redhat.com (Postfix) with ESMTP id DAC1F27CC9; Sat, 11 May 2019 08:40:29 +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: <20190509155801.8369-1-christian@brauner.io> References: <20190509155801.8369-1-christian@brauner.io> To: Christian Brauner Cc: dhowells@redhat.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] fs: make all new mount api fds cloexec by default MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <9331.1557564029.1@warthog.procyon.org.uk> Date: Sat, 11 May 2019 09:40:29 +0100 Message-ID: <9333.1557564029@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Sat, 11 May 2019 08:40:31 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Christian Brauner wrote: > This makes all file descriptors returned from new syscalls of the new mount > api cloexec by default. > > From a userspace perspective it is rarely the case that fds are supposed to > be inherited across exec. Having them not cloexec by default forces > userspace to remember to pass the _CLOEXEC flag along or to > invoke fcntl() on the fd to prevent leaking it. And leaking the fd is a > much bigger issue than forgetting to remove the cloexec flag and failing to > inherit the fd. > For old fd types we can't break userspace. But for new ones we should > whenever reasonable make them cloexec by default (Examples of this policy > are the new seccomp notify fds and also pidfds.). If userspace wants to > inherit fds across exec they can remove the O_CLOEXEC flag and so opt in to > inheritance explicitly. > > This patch also has the advantage that we can get rid of all the special > flags per file descriptor type for the new mount api. In total this lets us > remove 4 flags: > - FSMOUNT_CLOEXEC > - FSOPEN_CLOEXEC > - FSPICK_CLOEXEC > - OPEN_TREE_CLOEXEC > > Signed-off-by: Christian Brauner Fine by me. Reviewed-by: David Howells