| From | Jiri Slaby <> | Subject | [PATCH 3.12 060/155] pagemap: do not leak physical addresses to non-privileged userspace | Date | Tue, 7 Apr 2015 14:50:29 +0200 |
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From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
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: Jiri Slaby <jslaby@suse.cz> --- 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 7724fbdf443f..1db8ce0086ed 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1230,6 +1230,9 @@ 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"); -- 2.3.4
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