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Re: [PATCH 04/13] libsemanage: split final files into /var/lib/selinux/tmp
From: James Carter <jwcart2_at_nospam>Date: Fri Jan 08 2010 - 15:07:56 GMT
To: Stephen Smalley <sds@tycho.nsa.gov>
On Fri, 2010-01-08 at 09:30 -0500, Stephen Smalley wrote:
> On Wed, 2009-12-23 at 18:25 -0500, Caleb Case wrote:
> > This patch moves the final files from inside
> > /var/lib/selinux/<store>/[active|previous|tmp] to
> > /var/lib/selinux/tmp/<store>. The move is done to facilitate using
> > source control management on the /var/lib/selinux/<store> directory. If
> > these files remain in /var/lib/selinux/<store> they will pose a size
> > problem if an SCM like git is used as we'd be storing lots of binary
> > diffs. We are suggesting making this change now, rather than later when
> > source policy, SCM, and CIL[1] support are available, to ease the
> > migration burden.
> >
> > These are the files that have been moved:
> >
> > /var/lib/selinux/<store>/active/... /var/lib/selinux/tmp/<store>/...
> >
> > file_contexts contexts/files/file_contexts
> > file_contexts.homedirs contexts/files/file_contexts.homedirs
> > file_contexts.local contexts/files/file_contexts.local
> > netfilter_contexts contexts/netfilter_contexts
> > policy.kern policy/policy.<policyversion>
> > seusers.final seusers
> >
> > The layout of these files in /var/lib/selinux/tmp/<store> is designed to
> > mirror their locations in /etc/selinux/<store>. This should help clarify
> > the relationship between these final files and the files installed in
> > etc.
> >
> > One consequence of this move is that reverting to the previous policy
> > version requires a policy rebuild. Currently you can revert without
> > rebuilding.
>
> That seems a little worrisome to me, as a rebuild might fail, e.g. what
> happens if we abort a transaction due to a lack of disk space and then
> try to revert, requiring a rebuild, only to run out of space during the
> rebuild?
>
If the transaction is aborted then the policy hasn't actually been
changed, so I don't think that this example would be a problem. It is
only after the transaction is complete that everything is written to the
final location. Or am I missing something?
It would be a problem only if changes were made to the policy, that policy loaded, there were problems, and then the rebuild of the previous policy fails. -- James Carter <jwcart2@tycho.nsa.gov> National Security Agency -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@tycho.nsa.gov with the words "unsubscribe selinux" without quotes as the message.