Messages in this thread | | | Date | Mon, 19 Sep 2011 21:58:56 +0400 | From | Vasiliy Kulikov <> | Subject | Re: [kernel-hardening] Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo |
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On Mon, Sep 19, 2011 at 20:51 +0300, Pekka Enberg wrote: > On Mon, Sep 19, 2011 at 8:35 PM, Vasiliy Kulikov <segoon@openwall.com> wrote: > >> Yes, but there's no way for users to know where the allocations came from > >> if you mix them up with other kmalloc-128 call-sites. That way the number > >> of private files will stay private to the user, no? Doesn't that give you even > >> better protection against the infoleak? > > > > No, what it gives us is an obscurity, not a protection. I'm sure it > > highly depends on the specific situation whether an attacker is able to > > identify whether the call is from e.g. ecryptfs or from VFS. Also the > > correlation between the number in slabinfo and the real private actions > > still exists. > > How is the attacker able to identify that we kmalloc()'d from ecryptfs or > VFS based on non-root /proc/slabinfo when the slab allocator itself does > not have that sort of information if you mix up the allocations?
How can you _guarantee_ that they mix?
> Isn't this > much stronger protection especially if you combine that with /proc/slabinfo > restriction?
I don't see any reason to change allocators if we close slabinfo.
Thanks,
-- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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