From: "Richard W.M. Jones" <rjones@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: berrange@redhat.com, vsementsov@virtuozzo.com, eblake@redhat.com,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [PATCH v2] nbd/server: Add --selinux-label option
Date: Fri, 23 Jul 2021 17:34:42 +0100 [thread overview]
Message-ID: <20210723163442.GO26415@redhat.com> (raw)
In-Reply-To: <YPrr72N494WKnJA5@redhat.com>
On Fri, Jul 23, 2021 at 06:18:55PM +0200, Kevin Wolf wrote:
> Am 23.07.2021 um 12:33 hat Richard W.M. Jones geschrieben:
> > Under SELinux, Unix domain sockets have two labels. One is on the
> > disk and can be set with commands such as chcon(1). There is a
> > different label stored in memory (called the process label). This can
> > only be set by the process creating the socket. When using SELinux +
> > SVirt and wanting qemu to be able to connect to a qemu-nbd instance,
> > you must set both labels correctly first.
> >
> > For qemu-nbd the options to set the second label are awkward. You can
> > create the socket in a wrapper program and then exec into qemu-nbd.
> > Or you could try something with LD_PRELOAD.
> >
> > This commit adds the ability to set the label straightforwardly on the
> > command line, via the new --selinux-label flag. (The name of the flag
> > is the same as the equivalent nbdkit option.)
> >
> > A worked example showing how to use the new option can be found in
> > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
> >
> > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
> > Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
>
> I suppose this would also be relevant for the built-in NBD server,
> especially in the context of qemu-storage-daemon?
>
> If so, is this something specific to NBD sockets, or would it actually
> make sense to have it as a generic option in UnixSocketAddress?
For other NBD sockets, most likely. I'm not sure about Unix sockets
in general (as in: I know they also have the two label thing, but I
don't know if there's a situation where SVirt protects other sockets
apart from NBD sockets). I'm sure Dan will know ...
By the way although it appears that setsockcreatecon_raw is setting a
global flag, it seems to actually use a thread-local variable, so
implementing this (although still ugly) would not require locks.
https://github.com/SELinuxProject/selinux/blob/32611aea6543e3a8f32635857e37b4332b0b5c99/libselinux/src/procattr.c#L347
Rich.
--
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Read my programming and virtualization blog: http://rwmj.wordpress.com
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next prev parent reply other threads:[~2021-07-23 17:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 10:33 [PATCH v2] nbd/server: Add --selinux-label option Richard W.M. Jones
2021-07-23 10:33 ` Richard W.M. Jones
2021-07-23 10:47 ` Daniel P. Berrangé
2021-07-26 14:22 ` Eric Blake
2021-07-23 16:18 ` Kevin Wolf
2021-07-23 16:34 ` Richard W.M. Jones [this message]
2021-07-23 16:38 ` Daniel P. Berrangé
2021-08-25 19:35 ` Eric Blake
2021-09-24 19:23 ` Eric Blake
2021-09-27 12:48 ` Vladimir Sementsov-Ogievskiy
2021-09-27 12:55 ` Daniel P. Berrangé
2021-09-27 21:18 ` Eric Blake
2021-09-27 21:39 ` Richard W.M. Jones
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