From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70B2CC43381 for ; Thu, 7 Mar 2019 00:00:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D0DB20663 for ; Thu, 7 Mar 2019 00:00:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="i/MjTXb7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726579AbfCGAAH (ORCPT ); Wed, 6 Mar 2019 19:00:07 -0500 Received: from mail-qt1-f202.google.com ([209.85.160.202]:44158 "EHLO mail-qt1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726539AbfCGAAD (ORCPT ); Wed, 6 Mar 2019 19:00:03 -0500 Received: by mail-qt1-f202.google.com with SMTP id c9so13386596qte.11 for ; Wed, 06 Mar 2019 16:00:02 -0800 (PST) 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=RLZYCznt91X7Gql2FLJuA+D6Xq8z59q436/ddkparrE=; b=i/MjTXb7CbOG6UdkkS0vRNZvfV6iqT+SJUy26kVbxvGCwjfn8jRCtI1zQO9vj5H2ak apfgI4/baSkKebqMBSvCMvYYCd4lYbo5ztim2Tyika6/fTfhgxfiyzwCe6U8SXuxUH/A QMXQD8oXCYd6+d5dhpHO9MT8ekx8Nhcac8L3GeVKmleZ3xJNOFmMJqTs6o1aMOa/SvMi gfGhsbLGZLzEnc36jFQIkNfeaKcX77AgJBYVu2/DvzZJ1oXI4NCpFzcTHoMVU38SfSl7 DH+AH9U/Yw0/Mu1nSxhw0CQM0XKEcmhK6zNTjbEdD41qts+TJNBsuwJNo9oPQByKvGkt DkxA== 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=RLZYCznt91X7Gql2FLJuA+D6Xq8z59q436/ddkparrE=; b=e/fTOXdpDxzbG+171Z6UL2Y2q76b5+7Dk4jU5PRbzCH5qJ9BgCgHcChGvotQtwhREi s4YMsaSMgy6TUzgjKrrGiRsu3PYAc+SyEP2K84VGWCYbopr2Ve+CO6EjYQr0JAWWSpGa XYUoLNTBXKpUb0mUmg7WlxWYtUG79HfdCEAhPhTSx5/fcGJ6a3FrHDHqrR1rXCERYDqq Sf84UnJEFicGLOfSxAhkfGaI/d9yiaeSm9pT/QbCHsGHmChcO/15QpIaeXK2azfpRZpJ 3V/q/Cxf6JVHc0UCfQy8WxF9X0QpsJHeXR+4FGUGcD0Yn9i8PZWl5yE49jydU3Ws28CK VgIA== X-Gm-Message-State: APjAAAXOl7I2aG2ESOjUr7iDYR1ko1NhmPJkKfHixJ7rBq2Ze6TraKlW KNZ1nQY6BBNVMYybZk4rmz/HVWdJwPkUS70Vc0pdWQ== X-Google-Smtp-Source: APXvYqyg65IJHTLLH/dejwTsjoNanUPirYo+pqDWCoJN7KCkY2ggEVBCzFT/3DLvioXGAP9kW6hrdz8OII58UGrorWamGQ== X-Received: by 2002:a0c:b91c:: with SMTP id u28mr5950718qvf.45.1551916802349; Wed, 06 Mar 2019 16:00:02 -0800 (PST) Date: Wed, 6 Mar 2019 15:59:00 -0800 In-Reply-To: <20190306235913.6631-1-matthewgarrett@google.com> Message-Id: <20190306235913.6631-15-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190306235913.6631-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.352.gf09ad66450-goog Subject: [PATCH 14/27] ACPI: Limit access to custom_method when the kernel is locked down From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthew Garrett custom_method effectively allows arbitrary access to system memory, making it possible for an attacker to circumvent restrictions on module loading. Disable it if the kernel is locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells Reviewed-by: "Lee, Chun-Yi" cc: linux-acpi@vger.kernel.org Signed-off-by: Matthew Garrett --- drivers/acpi/custom_method.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index 4451877f83b6..ac8a90dc7096 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + if (kernel_is_locked_down("ACPI custom methods")) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header)) -- 2.21.0.352.gf09ad66450-goog