[Rpm-maint] FSM hooks for rpm plugin

Panu Matilainen pmatilai at laiskiainen.org
Thu Mar 7 18:05:57 UTC 2013

On 03/07/2013 07:55 PM, Panu Matilainen wrote:
> On 03/07/2013 04:27 PM, Reshetova, Elena wrote:
>>   If instead of hook 2) we have a post fsm commit hook that with proper
>> parameter, I think it can be serving the same purpose. The only thing
>> is that
>> setting permissions before rpm does it isn't really possible in this
>> case,
>> because before fsmcommit() file isn't in final location yet. But again, I
>> guess rpm would always trust its own plugins by a nature of a system
>> setup, so
>> we can assume that plugins won't try to change permissions that would
>> break
>> rpm query or they would break their own system in that case.
> Yup, rpm pretty much has to trust its plugins. OTOH... this made me
> think of another related issue: it would actually be better to set the
> permissions etc before moving the file to its final location. Currently
> we first move the file and then start setting permissions, which means
> executables and all will for a short period of time have totally
> incorrect permissions, labels and all. So if you happen to execute that
> binary during that period, who knows what will happen: it could fail to
> execute at all, execute with wrong capabilities / labels etc.
> Setting the permissions before moving would fix that and also avoid
> replacing a previous file at all in case we fail to in one of the
> metadata steps. For the stock metadata the actual path makes no
> difference, but for security labels you'd want the final path though (to
> avoid having to figure out and strip the temp extension from the file),
> so it'd require passing two paths to the pre-commit hook: current and
> final.

...or we could open an fd to the temporary file and pass that along with 
the final pathname. At least all the standard metadata + file 
capabilities + selinux labels are settable via file descriptor as well 
as by path so for those the fd approach wouldn't be a problem.

	- Panu -

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