linux-kernel - Re: [3.1 patch] x86: default to vsyscall=native

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Date:	Sun, 9 Oct 2011 16:45:40 +0300
From:	Adrian Bunk <bunk@...sta.de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Andrew Lutomirski <luto@....edu>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm00@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [3.1 patch] x86: default to vsyscall=native

On Thu, Oct 06, 2011 at 12:01:44AM +0200, Thomas Gleixner wrote:
>...
> We might need better dmesg output, e.g.
> 
>    printk_once("you might run something which requires
>    		vsyscall=native, but be aware that you are
> 		opening a security hole. See Documentation/....")
> 
> That's fine, but making the defaults insecure is just ass backwards.

Better dmesg output is in any case a better idea, patch is coming.

I stayed with warn_bad_vsyscall() instead of printk_once() for
the following reasons:
- _once is bad for something that might indicate exploit attempts,
  warn_bad_vsyscall() is already ratelimited
- the name and pid of the process should be shown
- the additional output of warn_bad_vsyscall() can help determine
  what caused it

> Thanks,
> 
> 	tglx

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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