tree 3b0970946789c4adceebd2c2b5ef531ea486922d
parent d965aca981b2c5e4a58dcc77aafbf5ccfdf1e751
author Kirill A. Shutemov <kirill.shutemov@linux.intel.com> 1452636928 -0500
committer Yuan Lin <yualin@google.com> 1452636928 -0500

BACKPORT: pagemap: do not leak physical addresses to non-privileged userspace

(cherry pick from commit ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce)

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 ]

Change-Id: I26bcfef2a0d4d3d02da4c522b29615d8ec694600
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>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 26038496