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

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Date:	Fri, 5 Nov 2010 01:20:50 +0100 (CET)
From:	Jesper Juhl <jj@...osbits.net>
To:	Marcus Meissner <meissner@...e.de>
cc:	linux-kernel@...r.kernel.org, jason.wessel@...driver.com,
	fweisbec@...il.com, tj@...nel.org, mort@....com, akpm@...l.org,
	security@...nel.org
Subject: Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of
 attacking

On Thu, 4 Nov 2010, Marcus Meissner wrote:

> 
> Hi,
> 
> Making /proc/kallsyms readable only for root makes it harder
> for attackers to write generic kernel exploits by removing
> one source of knowledge where things are in the kernel.
> 
> Signed-off-by: Marcus Meissner <meissner@...e.de>
> ---
>  kernel/kallsyms.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index 6f6d091..a8db257 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
> @@ -546,7 +546,7 @@ static const struct file_operations kallsyms_operations = {
>  
>  static int __init kallsyms_init(void)
>  {
> -	proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
> +	proc_create("kallsyms", 0400, NULL, &kallsyms_operations);
>  	return 0;
>  }
>  device_initcall(kallsyms_init);
> 

This doesn't harden things much, but a little is better than nothing.
This makes sense to me and looks OK.

Reviewed-by: Jesper Juhl <jj@...osbits.net>


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