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From:   Russell Coker <russell@coker.com.au>
To:     Topi Miettinen <toiwoton@gmail.com>
Reply-To: russell@coker.com.au
Cc:     selinux-refpolicy@vger.kernel.org
Subject: Re: Access to raw memory: remove or make boolean?
Date:   Tue, 25 Feb 2020 11:27:22 +1100
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On Tuesday, 25 February 2020 2:56:01 AM AEDT Topi Miettinen wrote:
> The PR would make all these conditional to new boolean,
> allow_raw_memory_access.

So if someone needs one of those many accesses (klogd_t or hald_t seems 
likely) then they also get access for things that aren't needed on most 
systems nowadays (EG xserver_t) and things that never made any sense (such as 
colord_t).

I think it would be best to remove most of those /dev/mem access rules and add 
them back only after testing with recent software and comments about why they 
are needed.

> > A quick grep of the latest policy turned up the above access to /dev/mem. 
> > Do ddcprobe_t, vbetool_t, and the X server still do that?  mcelog_t, and
> > klogd_t might have good uses, as might sosreport_t (don't even know what
> > it does but guessing it's like klogd_t).  rpm_t should maybe transition
> > to a different domain for whatever it was doing and the same for kudzo_t.
> >  Vmware  is a bit ugly, so vmware_t might actually do that.  iscsi_t,
> > mdadm_t, colord_t, and initrc_t should never have needed that.  hald_t,
> > hald_mac_t and
> > devicekit_disk_t might have needed it, but hopefully that was fixed a long
> > time ago.
> > 
> > Interestingly bootloader_t doesn't have such access even though a quick
> > inspection of the LILO source code shows that it still probes the boot
> > order by directly reading the BIOS memory.  I guess no-one uses LILO with
> > SE Linux.
> I also don't know most of these programs. Direct memory access was
> probably needed for X server during SVGA times, at least NVIDIA driver
> on my system does not seem to need it.

I think it was needed before KMS.  Is it even possible to run without KMS 
nowadays?

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