From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Vyukov <dvyukov@google.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Amir Goldstein <amir73il@gmail.com>,
Mimi Zohar <zohar@linux.ibm.com>,
syzbot+ae82084b07d0297e566b@syzkaller.appspotmail.com,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
linux-integrity@vger.kernel.org,
overlayfs <linux-unionfs@vger.kernel.org>
Subject: Re: [PATCH] fs: Evaluate O_WRONLY | O_RDWR to O_RDWR
Date: Thu, 13 Dec 2018 08:05:21 -0600 [thread overview]
Message-ID: <20181213140521.f3wbfrnh3zwk24td@merlin> (raw)
In-Reply-To: <20181213123444.GN2217@ZenIV.linux.org.uk>
On 12:34 13/12, Al Viro wrote:
> On Thu, Dec 13, 2018 at 01:16:45PM +0100, Dmitry Vyukov wrote:
> > On Thu, Dec 13, 2018 at 1:10 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> > >
> > > On Thu, Dec 13, 2018 at 05:57:17AM -0600, Goldwyn Rodrigues wrote:
> > > > A user can open(O_WRONLY | O_RDWR) and the options are valid.
> > > > However, OPEN_FMODE() evaluates both FMODE_READ and FMODE_WRITE,
> > > > as negative. We also need to protect the lower layers from this
> > > > anomaly.
> > > >
> > > > Solve it by dropping O_WRONLY, so O_RDWR takes precedence.
> > >
> > > Congratulations, you've broken fdutils... Passing 3 in lower bits
> > > of open() flags is *not* the same as O_RDWR; behaiviour is
> > > different and deliberately chosen by existing userland code.
> > >
> > > IOW, NAK.
> >
> > I am eager to hear what it means then.
>
> Open for ioctls, basically. No read/write allowed, no checks for
> media writability, etc. done at open() time, both read and write
> *permissions* required from device node.
>
> Think of the things like formatting a floppy, for example...
Sorry, I was not aware of the ioctl usage. Thanks.
--
Goldwyn
prev parent reply other threads:[~2018-12-13 14:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 11:57 [PATCH] fs: Evaluate O_WRONLY | O_RDWR to O_RDWR Goldwyn Rodrigues
2018-12-13 12:10 ` Al Viro
2018-12-13 12:16 ` Amir Goldstein
2018-12-13 12:16 ` Dmitry Vyukov
2018-12-13 12:34 ` Al Viro
2018-12-13 14:05 ` Goldwyn Rodrigues [this message]
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