From patchwork Sat Jun 22 00:03:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11010995 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 77B1B76 for ; Sat, 22 Jun 2019 00:04:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6809926E3D for ; Sat, 22 Jun 2019 00:04:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5BF1728BB1; Sat, 22 Jun 2019 00:04:52 +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=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DEC3326E3D for ; Sat, 22 Jun 2019 00:04:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726851AbfFVAEt (ORCPT ); Fri, 21 Jun 2019 20:04:49 -0400 Received: from mail-pl1-f201.google.com ([209.85.214.201]:51341 "EHLO mail-pl1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726853AbfFVAEs (ORCPT ); Fri, 21 Jun 2019 20:04:48 -0400 Received: by mail-pl1-f201.google.com with SMTP id d2so4458194pla.18 for ; Fri, 21 Jun 2019 17:04:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=7XUJQ2WWQgV+58iwM6R5lnhVlgjpfti3qggxZNIjvHc=; b=YbOGu6X3QdBGGGe8faHuFUYcFb8svwX0Yxl+CKZAFfrIXqI87gpdCYLkBy1RaGPta6 yrXHUhg6AvScoTY4m1Odo+/d3z9d7LUQVs7GrNeE9mFjrvxC0jFRRG0WFDmeARdHINoL 9EcWj34vMERn+3r+itQyO16RcWcpEpm9Lf6JNPHsvRDe46Q5sI5yk8mvHp3AbTMt9oeY Eovet+DRjjFBtgQyhhJsO/zVZP74OIBcPT7f8KuZ2LtAAHjxLB0tATATujAR/MbaUZZ4 Pm/32Y/fZlVXUWXMUQoLA+3vWhjjyHix9KSTINraPHgkYVJQZgEicVTLVGsYT3pskJn6 egvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=7XUJQ2WWQgV+58iwM6R5lnhVlgjpfti3qggxZNIjvHc=; b=qmEfKm+gzxWS/wq3I9OZ/Jf9bOdUxsH3FIyYAleNbEuE6Gz8e+6LiblIe966qpVMIi 8p7nXHXW2mYyZMhd5uguCFSqzhjmm2lQGaNpKyiCWK6LZLzVirGvMGFF9edT2T6FUYPL JMCCQ4yGP98DcfjmhJIE3i9eUzyz3jfKZp6miWQgtob8L+zAAA2AZIQeODAia0etXbcP tPBC+JaMe5P5sWCh070ckJe6ZKwnK2EzUjiBlHm5279fcRQP53lsQ2HUilfLTj27YmXv 9uzCe6hcGoA/u9Ap+NRr+8q3RCcZ8JtclPySf4yYwwnTvQmWl05a8gPBKqhLypop5OqP yajg== X-Gm-Message-State: APjAAAVfv6iVmtvNqozDHtYOKiTZy/u6ROt3u0L0qqtglnpxMTAvW7nY S19isD6r7IcDiVSUEWwSjf5bvLd6fbX0bbWZK4uR0w== X-Google-Smtp-Source: APXvYqwX0BWadWUzKD1pGC6iismXRYFWPwCnDuU+HcsvZA1gPfoXYPu6NOPQ3UQf1f2qQnXsIVTWV1ab1WpwKnLIpbDK9g== X-Received: by 2002:a63:f70b:: with SMTP id x11mr21395458pgh.212.1561161887383; Fri, 21 Jun 2019 17:04:47 -0700 (PDT) Date: Fri, 21 Jun 2019 17:03:47 -0700 In-Reply-To: <20190622000358.19895-1-matthewgarrett@google.com> Message-Id: <20190622000358.19895-19-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190622000358.19895-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH V34 18/29] Lock down TIOCSSERIAL From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, David Howells , Greg Kroah-Hartman , Matthew Garrett , Jiri Slaby , linux-serial@vger.kernel.org Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: David Howells Lock down TIOCSSERIAL as that can be used to change the ioport and irq settings on a serial port. This only appears to be an issue for the serial drivers that use the core serial code. All other drivers seem to either ignore attempts to change port/irq or give an error. Reported-by: Greg Kroah-Hartman Signed-off-by: David Howells Signed-off-by: Matthew Garrett cc: Jiri Slaby Cc: linux-serial@vger.kernel.org Reviewed-by: Kees Cook --- drivers/tty/serial/serial_core.c | 5 +++++ include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 3 files changed, 7 insertions(+) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 351843f847c0..a84f231a5df4 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -852,6 +853,10 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, new_flags = (__force upf_t)new_info->flags; old_custom_divisor = uport->custom_divisor; + retval = security_locked_down(LOCKDOWN_TIOCSSERIAL); + if (retval && (change_port || change_irq)) + goto exit; + if (!capable(CAP_SYS_ADMIN)) { retval = -EPERM; if (change_irq || change_port || diff --git a/include/linux/security.h b/include/linux/security.h index 03c125b277ca..61e3f4a62d16 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -91,6 +91,7 @@ enum lockdown_reason { LOCKDOWN_MSR, LOCKDOWN_ACPI_TABLES, LOCKDOWN_PCMCIA_CIS, + LOCKDOWN_TIOCSSERIAL, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 7be3e8fb5847..c89046dc2155 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -27,6 +27,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_MSR] = "raw MSR access", [LOCKDOWN_ACPI_TABLES] = "modified ACPI tables", [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", + [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };