linux-kernel - Re: [AppArmor 38/45] AppArmor: Module and LSM hooks

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Date:	Tue, 12 Jun 2007 14:00:47 -0500
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	Karl MacMillan <kmacmill@...hat.com>
Cc:	"Serge E. Hallyn" <serue@...ibm.com>,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Andreas Gruenbacher <agruen@...e.de>,
	Pavel Machek <pavel@....cz>, jjohansen@...e.de,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [AppArmor 38/45] AppArmor: Module and LSM hooks

Quoting Karl MacMillan (kmacmill@...hat.com):
> On Tue, 2007-06-12 at 10:34 -0500, Serge E. Hallyn wrote:
> > Quoting Stephen Smalley (sds@...ho.nsa.gov):
> 
> [...]
> 
> > > 
> > > If we added support for named type transitions to SELinux, as proposed
> > > earlier by Kyle Moffett during this discussion, wouldn't that address
> > > that issue without needing a DTE-like approach?  The concept is to add
> > 
> > Haven't read his message, but based on what you laid out here sure, that
> > sounds good.  It still, like my dte approach, might have some trouble
> > with the wildcard/regex rules AA allows.  And while it might perfectly
> > reproduce my original DTE behavior, I don't think it does what AA wants
> > on bind mounts.  (Whether what AA wants for bind mounts makes sense I'm
> > still not convinced, especially with user mounts coming soon (or already
> > here?), but I'm staying out of that discussion for now)
> > 
> > > the last component name as a further input to the labeling decision for
> > > new files, in addition to the existing use of the creating process'
> > > label, the parent directory label, and the kind of file.  Then, you
> > > could have something like:
> > > type_transition <domain> var_log_hosts_t:file "messages" messages_t;
> > > 
> > > The last component name is already available, so that doesn't require
> > > any changes to LSM, and it would be a straightforward extension of
> > > SELinux to support the above - it doesn't change the model at all, just
> > > adds a further input to the new file labeling logic.
> > 
> > And eliminates the need for restorecond?
> > 
> 
> Unlikely in the short term - restorecond is also used to reset contexts
> on critical files in /etc that might loose the context because tools
> used to update them are not correctly preserving contexts
> (e.g., /etc/mtab, etc/resolv.conf).

Confused - why wouldn't the new type_transition rule extension handle
that?

thanks,
-serge

> Actually - this whole notion restorecond as a critical component of
> SELinux because of a "new file problem" is pretty overblown. The default
> config file ships with:
> 
> /etc/resolv.conf
> /etc/samba/secrets.tdb
> /etc/mtab
> /var/run/utmp
> /var/log/wtmp
> ~/public_html
> ~/.mozilla/plugins/libflashplayer.so
> 
> So the only things that would be helped by type_transition rules with a 
> name component would be public_html and libflashplayer.so.
> 
> Karl
> 
> -
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