From: Vivek Goyal <vgoyal@redhat.com>
To: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Ondrej Mosnacek <omosnace@redhat.com>,
"J. Bruce Fields" <bfields@fieldses.org>,
Mark Salyzyn <salyzyn@android.com>,
Paul Moore <paul@paul-moore.com>,
linux-kernel@vger.kernel.org,
overlayfs <linux-unionfs@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org,
Daniel J Walsh <dwalsh@redhat.com>
Subject: Re: overlayfs access checks on underlying layers
Date: Tue, 4 Dec 2018 11:17:47 -0500 [thread overview]
Message-ID: <20181204161747.GC16818@redhat.com> (raw)
In-Reply-To: <665ec6f3-f16d-681f-30d5-eface14c9808@tycho.nsa.gov>
On Tue, Dec 04, 2018 at 11:05:46AM -0500, Stephen Smalley wrote:
> On 12/4/18 10:42 AM, Vivek Goyal wrote:
> > On Tue, Dec 04, 2018 at 04:31:09PM +0100, Miklos Szeredi wrote:
> > > On Tue, Dec 4, 2018 at 4:22 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> > >
> > > > Having said that, this still create little anomaly when mknod to client
> > > > is not allowed on context label. So a device file, which is on lower
> > > > and client can not open it for read/write on host, it can now be opened
> > > > for read/write because mounter will allow access. So why it is different
> > > > that regular copy up. Well, in regular copy up, we created a copy of
> > > > the original object and allowed writing to that object (cp --preserve=all)
> > > > model. But in case of device file, writes will go to same original
> > > > object. (And not a separate copy).
> > >
> > > That's true.
> > >
> > > In that sense copy up of special file should result in upper having
> > > the same label as of lower, right?
> >
> > I guess that might be reasonable (if this behavior is a concern). So even
> > after copy up, client will not be able to read/write a device if it was
> > not allowed on lower.
> >
> > Stephen, what do you think about retaining label of lower for device
> > files during copy up. What about socket/fifo.
>
> We don't check client task access to the upper inode label, only to the
> overlay, right? So the client is still free to access the device through
> the overlay even if we preserve the lower inode label on the upper inode?
> What do we gain?
That's only with latest code and Miklos said he will revert it for 4.20.
IOW, I am assuming that we will continue to check access to a file
on upper in the context of mounter. Otherwise, client will be able to access
files on upper/ which even mounter can't access.
Thanks
Vivek
next prev parent reply other threads:[~2018-12-04 16:18 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 19:55 overlayfs access checks on underlying layers Miklos Szeredi
2018-11-27 19:58 ` Miklos Szeredi
2018-11-27 21:05 ` Vivek Goyal
2018-11-28 10:00 ` Miklos Szeredi
2018-11-28 17:03 ` Vivek Goyal
2018-11-28 19:34 ` Stephen Smalley
2018-11-28 20:24 ` Miklos Szeredi
2018-11-28 21:46 ` Stephen Smalley
2018-11-29 11:04 ` Miklos Szeredi
2018-11-29 13:49 ` Vivek Goyal
2019-03-04 17:01 ` Mark Salyzyn
2019-03-04 17:56 ` Casey Schaufler
2019-03-04 18:44 ` Stephen Smalley
2019-03-04 19:21 ` Amir Goldstein
2018-11-29 16:16 ` Stephen Smalley
2018-11-29 16:22 ` Stephen Smalley
2018-11-29 19:47 ` Miklos Szeredi
2018-11-29 21:03 ` Stephen Smalley
2018-11-29 21:19 ` Stephen Smalley
2018-12-04 13:32 ` Miklos Szeredi
2018-12-04 14:30 ` Stephen Smalley
2018-12-04 14:45 ` Miklos Szeredi
2018-12-04 15:35 ` Stephen Smalley
2018-12-04 15:39 ` Miklos Szeredi
2018-12-11 15:50 ` Paul Moore
2018-12-04 15:15 ` Vivek Goyal
2018-12-04 15:22 ` Vivek Goyal
2018-12-04 15:31 ` Miklos Szeredi
2018-12-04 15:42 ` Vivek Goyal
2018-12-04 16:05 ` Stephen Smalley
2018-12-04 16:17 ` Vivek Goyal [this message]
2018-12-04 16:49 ` Stephen Smalley
2018-12-05 13:43 ` Vivek Goyal
2018-12-06 20:26 ` Stephen Smalley
2018-12-11 21:48 ` Vivek Goyal
2018-12-12 14:51 ` Stephen Smalley
2018-12-13 14:58 ` Vivek Goyal
2018-12-13 16:12 ` Stephen Smalley
2018-12-13 18:54 ` Vivek Goyal
2018-12-13 20:09 ` Stephen Smalley
2018-12-13 20:26 ` Vivek Goyal
2018-12-04 15:42 ` Stephen Smalley
2018-12-04 16:15 ` Vivek Goyal
2018-11-29 22:22 ` Daniel Walsh
2018-12-03 23:27 ` Paul Moore
2018-12-04 14:43 ` Stephen Smalley
2018-12-04 23:01 ` Paul Moore
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181204161747.GC16818@redhat.com \
--to=vgoyal@redhat.com \
--cc=bfields@fieldses.org \
--cc=dwalsh@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-unionfs@vger.kernel.org \
--cc=miklos@szeredi.hu \
--cc=omosnace@redhat.com \
--cc=paul@paul-moore.com \
--cc=salyzyn@android.com \
--cc=sds@tycho.nsa.gov \
--cc=selinux@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).