Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1165225AbdDXFQV (ORCPT ); Mon, 24 Apr 2017 01:16:21 -0400 Received: from relay2-d.mail.gandi.net ([217.70.183.194]:51398 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1164996AbdDXFP4 (ORCPT ); Mon, 24 Apr 2017 01:15:56 -0400 X-Originating-IP: 72.66.113.207 From: Matt Brown To: serge@hallyn.com, jmorris@namei.org, gregkh@linuxfoundation.org, jslaby@suse.com, corbet@lwn.net, keescook@chromium.org Cc: akpm@linux-foundation.org, jannh@google.com, kernel-hardening@lists.openwall.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Matt Brown Subject: [PATCH v4 1/2] tiocsti-restrict : Add owner user namespace to tty_struct Date: Mon, 24 Apr 2017 01:15:11 -0400 Message-Id: <20170424051512.20420-2-matt@nmatt.com> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20170424051512.20420-1-matt@nmatt.com> References: <20170424051512.20420-1-matt@nmatt.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1843 Lines: 62 This patch adds struct user_namespace *owner_user_ns to the tty_struct. Then it is set to current_user_ns() in the alloc_tty_struct function. This is done to facilitate capability checks against the original user namespace that allocated the tty. E.g. ns_capable(tty->owner_user_ns,CAP_SYS_ADMIN) This combined with the use of user namespace's will allow hardening protections to be built to mitigate container escapes that utilize TTY ioctls such as TIOCSTI. See: https://bugzilla.redhat.com/show_bug.cgi?id=1411256 Signed-off-by: Matt Brown --- drivers/tty/tty_io.c | 2 ++ include/linux/tty.h | 2 ++ 2 files changed, 4 insertions(+) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index e6d1a65..c276814 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -171,6 +171,7 @@ static void free_tty_struct(struct tty_struct *tty) put_device(tty->dev); kfree(tty->write_buf); tty->magic = 0xDEADDEAD; + put_user_ns(tty->owner_user_ns); kfree(tty); } @@ -3191,6 +3192,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx) tty->index = idx; tty_line_name(driver, idx, tty->name); tty->dev = tty_get_device(tty); + tty->owner_user_ns = get_user_ns(current_user_ns()); return tty; } diff --git a/include/linux/tty.h b/include/linux/tty.h index 1017e904..d902d42 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -12,6 +12,7 @@ #include #include #include +#include /* @@ -333,6 +334,7 @@ struct tty_struct { /* If the tty has a pending do_SAK, queue it here - akpm */ struct work_struct SAK_work; struct tty_port *port; + struct user_namespace *owner_user_ns; }; /* Each of a tty's open files has private_data pointing to tty_file_private */ -- 2.10.2