linux-kernel - Re: [PATCH 3/4] security: capabilities patch (version 0.4.4), part 3/4: introduce new capabilities

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Message-ID: <20060917181422.GC2225@elf.ucw.cz>
Date:	Sun, 17 Sep 2006 20:14:22 +0200
From:	Pavel Machek <pavel@....cz>
To:	Joshua Brindle <method@...too.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	David Madore <david.madore@....fr>,
	Linux Kernel mailing-list <linux-kernel@...r.kernel.org>,
	LSM mailing-list <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH 3/4] security: capabilities patch (version 0.4.4), part 3/4: introduce new capabilities

Hi!

> >>Introduce six new "regular" (=on-by-default) capabilities:
> >>
> >> * CAP_REG_FORK, CAP_REG_OPEN, CAP_REG_EXEC allow access to the
> >>   fork(), open() and exec() syscalls,
> >>    
> >
> >CAP_REG_EXEC seems meaningless, I can do the same with mmap by hand for
> >most types of binary execution except setuid (which is separate it
> >seems)
> >
> >Given the capability model is accepted as inferior to things like
> >SELinux policies why do we actually want to fix this anyway. It's
> >unfortunate we can't discard the existing capabilities model (which has
> >flaws) as well really.

> To expand on this a little, some of the capabilities you are looking to 
> add are of very little if any use without being able to specify objects. 
> For example, CAP_REG_OPEN is whether the process can open any file 
> instead of specific ones. How many applications open no files whatsoever 
> in practice? 

Filters, for example. gzip -9 - and such stuff does not need to open
any files. These should be easy to lock down, and still very useful.

More applications could be made lock-down-aware, and for example ask
master daemon to open files for them over a (already opened) socket.

								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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