From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753774Ab3LTGbb (ORCPT ); Fri, 20 Dec 2013 01:31:31 -0500 Received: from spork.scientician.org ([66.228.35.160]:42442 "EHLO spork.scientician.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752434Ab3LTGb3 (ORCPT ); Fri, 20 Dec 2013 01:31:29 -0500 X-Greylist: delayed 714 seconds by postgrey-1.27 at vger.kernel.org; Fri, 20 Dec 2013 01:31:29 EST X-Submitted: to spork.scientician.org (Postfix) with ESMTPSA id 85909488E1 X-Submitted: to mail.scientician.org (Postfix) with ESMTPSA id 4D1D220167 Message-ID: <52B3E16F.7070409@rhansen.org> Date: Fri, 20 Dec 2013 01:19:27 -0500 From: Richard Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: "Darrick J. Wong" CC: Miklos Szeredi , Alexander Viro , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net, Aurelien Jarno , Christoph Hellwig , "Theodore Ts'o" Subject: Re: [PATCH] fuse: Fix IOC_[GS]ETFLAGS argument size brokenness References: <20131219232739.GA10192@birch.djwong.org> In-Reply-To: <20131219232739.GA10192@birch.djwong.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2013-12-19 18:27, Darrick J. Wong wrote: > The IOC_[GS]ETFLAGS ioctls, despite being defined to take a "long" > parameter, actually take "int" parameters. FUSE unfortunately assumed > that the ioctl definitions never lie, and transfers a long's worth of > data in and out of userspace, which causes stack smashing in chattr, > and other bugs elsewhere. > > So, special-case this in FUSE, and document this int/long quirk in > include/uapi/linux/fs.h. > > Signed-off-by: Darrick J. Wong > --- > fs/fuse/file.c | 11 +++++++++++ > include/uapi/linux/fs.h | 1 + > 2 files changed, 12 insertions(+) > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 7e70506..5fa8181 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -2385,6 +2385,17 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg, > iov->iov_base = (void __user *)arg; > iov->iov_len = _IOC_SIZE(cmd); > > + /* > + * The IOC_[GS]ETFLAGS ioctls take int parameters even though > + * the ioctl definition specifies long. Userland has been > + * expecting int for ages (and chattr segfaults on FUSE > + * filesystems), so special case that here. The IOC32 > + * variants were declared with int, so they don't need this. > + */ > + if (cmd == FS_IOC_GETFLAGS || cmd == FS_IOC_SETFLAGS) { > + iov->iov_len = sizeof(int); > + } > + > if (_IOC_DIR(cmd) & _IOC_WRITE) { > in_iov = iov; > in_iovs = 1; > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h > index 6c28b61..bc8aa8e 100644 > --- a/include/uapi/linux/fs.h > +++ b/include/uapi/linux/fs.h > @@ -154,6 +154,7 @@ struct inodes_stat_t { > #define FITHAW _IOWR('X', 120, int) /* Thaw */ > #define FITRIM _IOWR('X', 121, struct fstrim_range) /* Trim */ > > +/* IOC_[GS]ETFLAGS take an int argument despite being defined to take long. */ > #define FS_IOC_GETFLAGS _IOR('f', 1, long) > #define FS_IOC_SETFLAGS _IOW('f', 2, long) > #define FS_IOC_GETVERSION _IOR('v', 1, long) This change to include/uapi/linux/fs.h is similar to but not as thorough as: http://mid.gmane.org/1385548839-16617-1-git-send-email-aurelien@aurel32.net https://lkml.org/lkml/2013/11/27/93 (The above linked patch is the patch Aurelien referenced in the "Argument type for FS_IOC_GETFLAGS/FS_IOC_SETFLAGS ioctls" thread on linux-fsdevel; see .) -Richard