linux-kernel - [PATCH 2/2] mm: restrict access to /proc/meminfo

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Message-ID: <20110927175642.GA3432@albatros>
Date:	Tue, 27 Sep 2011 21:56:42 +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: [PATCH 2/2] mm: restrict access to /proc/meminfo

/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

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);
--
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