[Rpm-maint] [PATCH RFC] Package script(let)s SELinux execution context

Panu Matilainen pmatilai at laiskiainen.org
Tue Nov 20 17:27:58 UTC 2012

On 11/20/2012 05:27 PM, Guillem Jover wrote:
> Hi!
> Some context for the rpm folks. While looking into improving SELinux
> support in dpkg, I noticed that dpkg is not setting a new execution
> context when running the package maintainer scripts (package scriptlets
> in rpm lingo, I think). And when checking how to implement it, it seemed
> that reusing something like the current rpm_execcon() would be best,
> and Stephen seemed to agree. For more details, see the thread starting
> at <http://marc.info/?t=135236358700001&r=1&w=2>.
> Having checked the rpm code, and the mailing list, it seems like this
> new function would make it easy to be used there too for stuff like
> the Lua scriptlets (if desired), and might make it easier also to
> switch to the new rpm plugins framework (?).

> I've discarded the verified argument for the new function because that
> seemed best handled from the rpm side, and in any case seemed unrelated
> to the execution context. I'm not entirely convinced about the function
> name though, as it could be confused as applying a context to a path on
> the filesystem. And I've not marked rpm_execcon() as deprecated because
> it might be annoying at the beginning, but would change that if you think
> it makes sense.
> In any case, here's a patch adding such new function. For dpkg, given
> that it has never set a new context up to now, I'd only make use of the
> function if it's available in libselinux, as I don't think it's worth it
> to ship an embedded copy. For rpm, I guess it could switch to use the
> function also if available and fallback to rpm_execcon() otherwise. After
> a while the rpm_execcon() function could be removed from libselinux, on
> the next ABI break, as I understand was the plan anyway (?).
> (The patch might not apply w/o the man page cleanup series.)
> So, what do you think?

No objections to replacing and/or axing rpm_execcon(), AFAIR its simply 
a convenience-function around setexeccon() and one that rpm will (have 
to) cease to use in near future anyway in order to move all the selinux 
specifics into a plugin.

I dont have objections for the suggested interface as such either, it'd 
be convenient for what rpm will need for regular scriptlets. It wont 
help with rpm's embedded Lua-scriptlets as they run in-process though. 
Rpm might well start forking their execution, but even then the 
transition to another selinux context (or similar security mechanism) 
needs to happen without an exec() for the embedded scripts.

	- Panu -

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