From patchwork Thu Jul 18 19:44:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11049471 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 97E49746 for ; Thu, 18 Jul 2019 19:45:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 85991288AD for ; Thu, 18 Jul 2019 19:45:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 76EC12889C; Thu, 18 Jul 2019 19:45:01 +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 18A932883B for ; Thu, 18 Jul 2019 19:45:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403828AbfGRTo4 (ORCPT ); Thu, 18 Jul 2019 15:44:56 -0400 Received: from mail-pf1-f202.google.com ([209.85.210.202]:39322 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403817AbfGRTo4 (ORCPT ); Thu, 18 Jul 2019 15:44:56 -0400 Received: by mail-pf1-f202.google.com with SMTP id 6so17219150pfi.6 for ; Thu, 18 Jul 2019 12:44:55 -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=RmH/lQXgmHpT1wDdkDviRnHZue3oZYbqIfCTXvy7fCM=; b=sr+U+0BUhfEnXadfS3Td1uoyOy7MyzT1cfjoaE68UBw1WhRqNJMBFgpLkQFYR8CYek KMLLN+smdCN2smIEcLzxglZftb5hu87OZDSnHoh58j9iUJ9WtMY8gtatqIWRzLoReE4k rOXwOJJUY3pNC9LTVR+45zWViuky5wZ5OsqQmEH21XbkAZ2iczTBIY0BDe0O6ftn+0Nd N8VHxUEL9vzNp13MjZ/HenFMfJvjHjVq4+s9MH40Hv98la5iFc/+chgCT/UbR25vQQo8 f1K5mSd6Q5IDsOeHHgZ8Jj3sZRtyFkxD9BOWOQoOTJwCQ5ZkVLIwSvMUjWHIe2vcYKG3 IrqQ== 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=RmH/lQXgmHpT1wDdkDviRnHZue3oZYbqIfCTXvy7fCM=; b=icHRuK/m3iPlP7kIDl3paC9eodZmqzTmsYUgndHoc9f1bO4E0DaSxTQzNk/vBXt3gV lyaYrCijTdr26oDIE+JS2llCMkmzPpb/nMD5D7RXKSnYQywoT61hxiGm7vWsjkBVdqMP lvJjWC/C9veOIjaQG0RvKw6Un1J76J7nQ6lxzr5X5nEfdlZeIT/AdmNY+5nEWWsdm9TX tfwjlD+3ZiI4unpoXr4FyDkoXdZyejet+hoqaWiXAQEkKqhMwws+TEJL8aZNwD8DRR3w 2RO6tP4Dc8fu+t89cKxBWlP0dQs0I0oJg7ydc5Pp7d5RGOvKrVGWctK4BSBoGnCHlzX0 fUeg== X-Gm-Message-State: APjAAAXW1jn7LcO3PRT9nHzfItDzUr1NIFpYxhn1bD60HqBJFqaaoz/u kRdjlIZyg7qaTomnwFCy6SUTSlFYm6Nf6x1VViXQ5g== X-Google-Smtp-Source: APXvYqyeJB/q+rqGISfS2YyA1gmULiVA9NiMn8MYvGu0Kh+AP7Ivcdvfi4JVaIEOuKfNlKBPpuhBRNRFf/1QBiVgkwqkhQ== X-Received: by 2002:a63:460c:: with SMTP id t12mr49204271pga.69.1563479094865; Thu, 18 Jul 2019 12:44:54 -0700 (PDT) Date: Thu, 18 Jul 2019 12:44:00 -0700 In-Reply-To: <20190718194415.108476-1-matthewgarrett@google.com> Message-Id: <20190718194415.108476-15-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190718194415.108476-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.510.g264f2c817a-goog Subject: [PATCH V36 14/29] 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, linux-api@vger.kernel.org, Matthew Garrett , Matthew Garrett , David Howells , Kees Cook , linux-acpi@vger.kernel.org Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP 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: Kees Cook cc: linux-acpi@vger.kernel.org --- drivers/acpi/custom_method.c | 6 ++++++ include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 3 files changed, 8 insertions(+) diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index b2ef4c2ec955..7031307becd7 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "internal.h" @@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + int ret; + + ret = security_locked_down(LOCKDOWN_ACPI_TABLES); + if (ret) + return ret; if (!(*ppos)) { /* parse the table header to get the table length */ diff --git a/include/linux/security.h b/include/linux/security.h index 155ff026eca4..1c32522b3c5a 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -110,6 +110,7 @@ enum lockdown_reason { LOCKDOWN_PCI_ACCESS, LOCKDOWN_IOPORT, LOCKDOWN_MSR, + LOCKDOWN_ACPI_TABLES, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index d99c0bee739d..ecb51b1a5c03 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -25,6 +25,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_PCI_ACCESS] = "direct PCI access", [LOCKDOWN_IOPORT] = "raw io port access", [LOCKDOWN_MSR] = "raw MSR access", + [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };