Re: [PATCH 5/4] ipc/mqueue: revert bump up DFLT_*MAX

From: Joe Korty
Date: Thu Oct 27 2011 - 12:55:44 EST


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@xxxxxxxxx>
> Cc: Doug Ledford <dledford@xxxxxxxxxx>
> Cc: Amerigo Wang <amwang@xxxxxxxxxx>
> Cc: Serge E. Hallyn <serue@xxxxxxxxxx>
> Cc: Jiri Slaby <jslaby@xxxxxxx>
> Cc: Joe Korty <joe.korty@xxxxxxxx>
> ---
> 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@xxxxxxxx>

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