From patchwork Fri May 5 23:20:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matt Brown X-Patchwork-Id: 9714473 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C09A56034B for ; Fri, 5 May 2017 23:21:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AF90A28687 for ; Fri, 5 May 2017 23:21:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A45072869A; Fri, 5 May 2017 23:21:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id D331528687 for ; Fri, 5 May 2017 23:21:44 +0000 (UTC) Received: (qmail 21866 invoked by uid 550); 5 May 2017 23:21:40 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 20285 invoked from network); 5 May 2017 23:21:35 -0000 X-Virus-Scanned: Debian amavisd-new at mfilter11-d.gandi.net X-Originating-IP: 72.66.113.207 From: Matt Brown To: serge@hallyn.com, gregkh@linuxfoundation.org, jslaby@suse.com, akpm@linux-foundation.org, jannh@google.com, keescook@chromium.org Cc: jmorris@namei.org, kernel-hardening@lists.openwall.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Matt Brown Date: Fri, 5 May 2017 19:20:17 -0400 Message-Id: <20170505232018.28846-2-matt@nmatt.com> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20170505232018.28846-1-matt@nmatt.com> References: <20170505232018.28846-1-matt@nmatt.com> Subject: [kernel-hardening] [PATCH v6 1/2] security: tty: Add owner user namespace to tty_struct X-Virus-Scanned: ClamAV using ClamSMTP 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 Acked-by: Serge Hallyn Reviewed-by: Kees Cook 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 */