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Date: Tue, 27 Sep 2011 23:38:10 +0400
From: Vasiliy Kulikov <segoon@...nwall.com>
To: kernel-hardening@...ts.openwall.com,
Christoph Lameter <cl@...ux-foundation.org>,
Pekka Enberg <penberg@...nel.org>, Matt Mackall <mpm@...enic.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, Kees Cook <kees@...ntu.com>,
Dave Hansen <dave@...ux.vnet.ibm.com>, Valdis.Kletnieks@...edu,
Linus Torvalds <torvalds@...ux-foundation.org>,
David Rientjes <rientjes@...gle.com>,
Alan Cox <alan@...ux.intel.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mm: restrict access to /proc/meminfo
On Tue, Sep 27, 2011 at 21:56 +0400, Vasiliy Kulikov wrote:
> /proc/meminfo stores information related to memory pages usage, which
> may be used to monitor the number of objects in specific caches (and/or
> the changes of these numbers). This might reveal private information
> similar to /proc/slabinfo infoleaks. To remove the infoleak, just
> restrict meminfo to root. If it is used by unprivileged daemons,
> meminfo permissions can be altered the same way as slabinfo:
>
> groupadd meminfo
> usermod -a -G meminfo $MONITOR_USER
> chmod g+r /proc/meminfo
> chgrp meminfo /proc/meminfo
Just to make it clear: since this patch breaks "free", I don't propose
it anymore.
> Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
> CC: Kees Cook <kees@...ntu.com>
> CC: Dave Hansen <dave@...ux.vnet.ibm.com>
> CC: Christoph Lameter <cl@...two.org>
> CC: Pekka Enberg <penberg@...helsinki.fi>
> CC: Valdis.Kletnieks@...edu
> CC: Linus Torvalds <torvalds@...ux-foundation.org>
> CC: David Rientjes <rientjes@...gle.com>
> CC: Alan Cox <alan@...ux.intel.com>
> ---
> fs/proc/meminfo.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> --
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index 5861741..949bdee 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -187,7 +187,7 @@ static const struct file_operations meminfo_proc_fops = {
>
> static int __init proc_meminfo_init(void)
> {
> - proc_create("meminfo", 0, NULL, &meminfo_proc_fops);
> + proc_create("meminfo", S_IFREG | S_IRUSR, NULL, &meminfo_proc_fops);
> return 0;
> }
> module_init(proc_meminfo_init);
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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