Messages in this thread | | | Date | Wed, 17 Sep 2008 09:42:06 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 12/13] hrtimer: create a "timer_slack" field in the task struct |
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On Sun 2008-09-14 09:04:08, Ulrich Drepper wrote: > On Sun, Sep 14, 2008 at 8:57 AM, Pavel Machek <pavel@suse.cz> wrote: > >> LD_PRELOAD and other variables are ignored in security-relevant > >> contexts and environments are cleared in many situations. Sure, you > > > > ...but that's okay, right? You would not want passwd to inherit huge > > slack specified by attacker...? > > No, it's not OK. There are enough apps which are privileged and need > to be handled this way. Take the X server, for instance.
_Need_ to be handled? They are not handled that way today, and it still seems to work ok.
(Plus X is no longer setuid on new distros...)
So -- how do you prevent user from setting excessively high slack and interfering with ping or passwd?
> > Well, it is not too much, but... is the cost for userspace really > > significant? You'd clearly want it stored in environment, not > > filesystem... > > You cannot really use the environment for anything meaningful. > Especially for this case, you couldn't change the setting for a > running process. What a fully-userlevel implementation would have
Is this important enough to warrant setting for already-running processes? I don't think so... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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