From 1cd3d374b25ba7e9934be66781ff7fc4513a2b09 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Mon, 9 Mar 2015 23:11:12 +0200 Subject: [PATCH] pagemap: do not leak physical addresses to non-privileged userspace [ Upstream 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 Acked-by: Konstantin Khlebnikov Acked-by: Andy Lutomirski Cc: Pavel Emelyanov Cc: Andrew Morton Cc: Mark Seaborn Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- 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 e8972bc..69aa378 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1291,6 +1291,9 @@ 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"); -- 2.7.4