From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Kirill A. Shutemov" , Konstantin Khlebnikov , Andy Lutomirski , Pavel Emelyanov , Andrew Morton , Mark Seaborn , Linus Torvalds , mancha security Subject: [PATCH 3.10 34/34] pagemap: do not leak physical addresses to non-privileged userspace Date: Fri, 17 Apr 2015 15:29:06 +0200 Message-Id: <20150417132555.829442114@linuxfoundation.org> In-Reply-To: <20150417132553.751904098@linuxfoundation.org> References: <20150417132553.751904098@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable 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 Signed-off-by: mancha security Signed-off-by: Greg Kroah-Hartman --- fs/proc/task_mmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1110,9 +1110,19 @@ 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 */