From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wtarreau.pck.nerim.net ([62.212.114.60]:36261 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934137AbbEOIQQ (ORCPT ); Fri, 15 May 2015 04:16:16 -0400 Message-Id: <20150515080532.108984825@1wt.eu> Date: Fri, 15 May 2015 10:06:13 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Kirill A. Shutemov" , Konstantin Khlebnikov , Andy Lutomirski , Pavel Emelyanov , Andrew Morton , Mark Seaborn , Linus Torvalds , mancha security , Ben Hutchings , Willy Tarreau Subject: [ 43/48] pagemap: do not leak physical addresses to non-privileged userspace MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 In-Reply-To: <9c2783dfae10ef2d1e9b08bcc1e562c5@local> Sender: stable-owner@vger.kernel.org List-ID: 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: "Kirill A. Shutemov" 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 Acked-by: Konstantin Khlebnikov Acked-by: Andy Lutomirski Cc: Pavel Emelyanov Cc: Andrew Morton Cc: Mark Seaborn Signed-off-by: Linus Torvalds [mancha security: Backported to 3.10] Signed-off-by: mancha security Signed-off-by: Ben Hutchings (cherry picked from commit 1ffc3cd9a36b504c20ce98fe5eeb5463f389e1ac) Signed-off-by: Willy Tarreau --- fs/proc/task_mmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 3b7b82a..73db5a6 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -773,9 +773,19 @@ out: return ret; } +static int pagemap_open(struct inode *inode, struct file *file) +{ + /* do not disclose physical addresses to unprivileged + userspace (closes a rowhammer attack vector) */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + return 0; +} + const struct file_operations proc_pagemap_operations = { .llseek = mem_lseek, /* borrow this */ .read = pagemap_read, + .open = pagemap_open, }; #endif /* CONFIG_PROC_PAGE_MONITOR */ -- 1.7.12.2.21.g234cd45.dirty