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* [RFC, PATCH] pagemap: do not leak physical addresses to non-privileged userspace
@ 2015-03-09 21:11 Kirill A. Shutemov
  2015-03-09 21:20 ` Pavel Emelyanov
                   ` (3 more replies)
  0 siblings, 4 replies; 15+ messages in thread
From: Kirill A. Shutemov @ 2015-03-09 21:11 UTC (permalink / raw)
  To: linux-mm, linux-kernel, Andrew Morton, Linus Torvalds
  Cc: Kirill A. Shutemov, Pavel Emelyanov, Konstantin Khlebnikov,
	Mark Seaborn, Andy Lutomirski

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

As pointed by recent post[1] on exploiting DRAM physical imperfection,
/proc/PID/pagemap exposes sensitive information which can be used to do
attacks.

This is RFC patch which disallow anybody without CAP_SYS_ADMIN to read
the pagemap.

Any comments?

[1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Seaborn <mseaborn@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
---
 fs/proc/task_mmu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 246eae84b13b..b72b36e64286 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1322,6 +1322,9 @@ out:
 
 static int pagemap_open(struct inode *inode, struct file *file)
 {
+	/* do not disclose physical addresses: attack vector */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
 	pr_warn_once("Bits 55-60 of /proc/PID/pagemap entries are about "
 			"to stop being page-shift some time soon. See the "
 			"linux/Documentation/vm/pagemap.txt for details.\n");
-- 
2.3.1

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^ permalink raw reply	[flat|nested] 15+ messages in thread

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Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-03-09 21:11 [RFC, PATCH] pagemap: do not leak physical addresses to non-privileged userspace Kirill A. Shutemov
2015-03-09 21:20 ` Pavel Emelyanov
2015-03-09 22:09 ` Konstantin Khlebnikov
2015-03-10  0:11 ` Kees Cook
2015-03-10  0:19   ` Andy Lutomirski
2015-03-10  2:36     ` Dave Hansen
2015-03-16 21:11 ` Pavel Machek
2015-03-17  0:49   ` Mark Seaborn
2015-03-17  1:21     ` Andy Lutomirski
2015-03-17 11:16       ` rowhammer and pagemap (was Re: [RFC, PATCH] pagemap: do not leak physical addresses to non-privileged userspace) Pavel Machek
2015-03-17 17:58         ` One Thousand Gnomes
2015-03-23 21:26           ` Pavel Machek
2015-03-19 12:51       ` [RFC, PATCH] pagemap: do not leak physical addresses to non-privileged userspace Vlastimil Babka
2015-03-23 21:26         ` Pavel Machek
2015-03-23 22:36           ` Vlastimil Babka

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