linux-kernel - Re: [RFC 0/4] make call_usermodehelper a bit more "safe"

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Message-ID: <alpine.LRH.2.00.1612191428060.15543@gjva.wvxbf.pm>
Date:   Mon, 19 Dec 2016 14:34:00 +0100 (CET)
From:   Jiri Kosina <jikos@...nel.org>
To:     Greg KH <gregkh@...uxfoundation.org>
cc:     NeilBrown <neilb@...e.com>, kernel-hardening@...ts.openwall.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC 0/4] make call_usermodehelper a bit more "safe"

On Fri, 16 Dec 2016, Greg KH wrote:

> > You seem to be targeting a situation where the kernel memory can be
> > easily changed, but filesystem content cannot (if it could - the
> > attacker would simply replace /sbin/hotplug).
> 
> Correct, like an embedded system with a read-only system partition, or
> for when some kernel bug allows for random memory writes, yet privilege
> escalation is hard to achieve for your process.

Sorry, I really don't get this.

If kernel memory can be easily changed (which is assumed here), why bother 
with all this? I'll just set current->uid to 0 and be done.

-- 
Jiri Kosina
SUSE Labs