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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 3AA97C55185 for ; Thu, 23 Apr 2020 00:44:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 21FEE2075A for ; Thu, 23 Apr 2020 00:44:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725895AbgDWAoS (ORCPT ); Wed, 22 Apr 2020 20:44:18 -0400 Received: from relay11.mail.gandi.net ([217.70.178.231]:48805 "EHLO relay11.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725846AbgDWAoS (ORCPT ); Wed, 22 Apr 2020 20:44:18 -0400 Received: from localhost (50-39-163-217.bvtn.or.frontiernet.net [50.39.163.217]) (Authenticated sender: josh@joshtriplett.org) by relay11.mail.gandi.net (Postfix) with ESMTPSA id 40A4B100002; Thu, 23 Apr 2020 00:44:10 +0000 (UTC) Date: Wed, 22 Apr 2020 17:44:07 -0700 From: Josh Triplett To: Florian Weimer Cc: Mark Wielaard , io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mtk.manpages@gmail.com, Alexander Viro , Arnd Bergmann , Jens Axboe , Aleksa Sarai , linux-man@vger.kernel.org Subject: Re: [PATCH v5 3/3] fs: pipe2: Support O_SPECIFIC_FD Message-ID: <20200423004407.GB161058@localhost> References: <2bb2e92c688b97247f644fe8220054d6c6b66b65.1587531463.git.josh@joshtriplett.org> <877dy7ikyh.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877dy7ikyh.fsf@mid.deneb.enyo.de> Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Wed, Apr 22, 2020 at 05:44:38PM +0200, Florian Weimer wrote: > * Josh Triplett: > > This allows the caller of pipe2 to specify one or both file descriptors > > rather than having them automatically use the lowest available file > > descriptor. The caller can specify either file descriptor as -1 to > > allow that file descriptor to use the lowest available. > > > > Signed-off-by: Josh Triplett > > --- > > fs/pipe.c | 16 ++++++++++++---- > > 1 file changed, 12 insertions(+), 4 deletions(-) > > > > diff --git a/fs/pipe.c b/fs/pipe.c > > index 16fb72e9abf7..4681a0d1d587 100644 > > --- a/fs/pipe.c > > +++ b/fs/pipe.c > > @@ -936,19 +936,19 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags) > > int error; > > int fdw, fdr; > > > > - if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT)) > > + if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_SPECIFIC_FD)) > > return -EINVAL; > > > > error = create_pipe_files(files, flags); > > if (error) > > return error; > > > > - error = get_unused_fd_flags(flags); > > + error = get_specific_unused_fd_flags(fd[0], flags); > > if (error < 0) > > goto err_read_pipe; > > fdr = error; > > > > - error = get_unused_fd_flags(flags); > > + error = get_specific_unused_fd_flags(fd[1], flags); > > if (error < 0) > > goto err_fdr; > > fdw = error; > > @@ -969,7 +969,11 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags) > > int do_pipe_flags(int *fd, int flags) > > { > > struct file *files[2]; > > - int error = __do_pipe_flags(fd, files, flags); > > + int error; > > + > > + if (flags & O_SPECIFIC_FD) > > + return -EINVAL; > > + error = __do_pipe_flags(fd, files, flags); > > if (!error) { > > fd_install(fd[0], files[0]); > > fd_install(fd[1], files[1]); > > @@ -987,6 +991,10 @@ static int do_pipe2(int __user *fildes, int flags) > > int fd[2]; > > int error; > > > > + if (flags & O_SPECIFIC_FD) > > + if (copy_from_user(fd, fildes, sizeof(fd))) > > + return -EFAULT; > > + > > error = __do_pipe_flags(fd, files, flags); > > if (!error) { > > if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) { > > Mark, I think this will need (or at least benefit from) some valgrind > changes. Yes, this makes pipe2 read the memory of its first argument from userspace, if and only if its second argument contains the O_SPECIFIC_FD flag. - Josh Triplett