linux-kernel - Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking

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Message-ID: <4CE7B1CF.8060300@redhat.com>
Date:	Sat, 20 Nov 2010 13:32:31 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Kyle Moffett <kyle@...fetthome.net>
CC:	Marcus Meissner <meissner@...e.de>, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org, tj@...nel.org, akpm@...l.org,
	hpa@...or.com, mingo@...e.hu, w@....eu, alan@...rguk.ukuu.org.uk
Subject: Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of
 attacking

On 11/17/2010 07:40 AM, Kyle Moffett wrote:
>    (1) For 99%+ of all the computers out there you can get a 90%+
> accurate guess for what kernel is running by looking at the version of
> libc installed on the system.  All you have to do for those computers
> is download a bunch of distro kernels and look at the libc packages
> and build a table of "libc6-SOMEVERSION =>  0xADDRESS", etc.  Because
> of how all the vendors backport and track versions, "SOMEVERSION"
> usually includes something wonderfully helpful like "el5" or "squeeze"
> or whatever.  This does *nothing* for those users, and it's not clear
> that it ever *could*.

Isn't the kernel relocatable these days?  We can randomize the kernel 
load address at boot time and make this information useless.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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