From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755556Ab3LTXMM (ORCPT ); Fri, 20 Dec 2013 18:12:12 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:16664 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752362Ab3LTXMJ (ORCPT ); Fri, 20 Dec 2013 18:12:09 -0500 Date: Fri, 20 Dec 2013 15:10:04 -0800 From: "Darrick J. Wong" To: Richard Hansen 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 Message-ID: <20131220231004.GB10192@birch.djwong.org> References: <20131219232739.GA10192@birch.djwong.org> <52B3E16F.7070409@rhansen.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52B3E16F.7070409@rhansen.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 20, 2013 at 01:19:27AM -0500, Richard Hansen wrote: > 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 > .) Aha! I thought I'd seen something like that on the list, though it doesn't seem to be in -rc. Thank you for pointing that out. And yes, now that I look at all the [GS]ETVERSION implementations, I think FUSE could special-case those two ioctls too. --D > > -Richard > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html