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[3.13.y-ckt,131/156] pagemap: do not leak physical addresses to non-privileged userspace

Message ID 1428447093-3282-132-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa April 7, 2015, 10:51 p.m. UTC 
3.13.11-ckt19 -stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce upstream.

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 disallows anybody without CAP_SYS_ADMIN to read the pagemap.

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

[ Eventually we might want to do anything more finegrained, but for now
  this is the simple model.   - Linus ]

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

Patch

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 903c19f..b5f508d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1249,6 +1249,9 @@  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");