tree b3398c39cc067dbe76e598266f11dab861c39740
parent 70665a2f99f1d71238f338b3e6740fa753f4cd7e
author Kirill A. Shutemov <kirill.shutemov@linux.intel.com> 1425935472 +0200
committer Jin Qian <jinqian@google.com> 1453420196 -0800

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 ]

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: 25739721
Change-Id: I5582c993dbeb0b7287e6d41b57e494d123d33083