linux-kernel - Re: [PATCH 5/4] ipc/mqueue: revert bump up DFLT

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Date:	Thu, 27 Oct 2011 12:41:08 -0400
From:	Joe Korty <joe.korty@...r.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
Cc:	"dledford@...hat.com" <dledford@...hat.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"amwang@...hat.com" <amwang@...hat.com>
Subject: Re: [PATCH 5/4] ipc/mqueue: revert bump up DFLT_*MAX

On Wed, Oct 26, 2011 at 11:37:10AM -0400, KOSAKI Motohiro wrote:
> Mqueue limitation is slightly naieve parameter likes other ipcs
> because unprivileged user can consume kernel memory by using ipcs.
> 
> Thus, too aggressive raise bring us security issue. Example,
> current setting allow evil unprivileged user use 256GB (= 256
> * 1024 * 1024*1024) and it's enough large to system will belome
> unresponsive. Don't do that.
> 
> Instead, every admin should adjust the knobs for their own systems.
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...il.com>
> Cc: Doug Ledford <dledford@...hat.com>
> Cc: Amerigo Wang <amwang@...hat.com>
> Cc: Serge E. Hallyn <serue@...ibm.com>
> Cc: Jiri Slaby <jslaby@...e.cz>
> Cc: Joe Korty <joe.korty@...r.com>
> ---
>  include/linux/ipc_namespace.h |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
> index e2bac00..2d7c5e0 100644
> --- a/include/linux/ipc_namespace.h
> +++ b/include/linux/ipc_namespace.h
> @@ -118,12 +118,12 @@ extern int mq_init_ns(struct ipc_namespace *ns);
>  #define DFLT_QUEUESMAX		      256
>  #define HARD_QUEUESMAX		     1024
>  #define MIN_MSGMAX			1
> -#define DFLT_MSG		       64U
> -#define DFLT_MSGMAX		     1024
> +#define DFLT_MSG		       10U
> +#define DFLT_MSGMAX		       10
>  #define HARD_MSGMAX		    65536
>  #define MIN_MSGSIZEMAX		      128
>  #define DFLT_MSGSIZE		     8192U
> -#define DFLT_MSGSIZEMAX		(1024*1024)
> +#define DFLT_MSGSIZEMAX		     8192
>  #define HARD_MSGSIZEMAX	     (16*1024*1024)
>  #else
>  static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }
> -- 
> 1.7.5.2

Acked-by: Joe Korty <joe.korty@...r.com>

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