From patchwork Tue Aug 20 00:17:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11102383 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 04EFB1395 for ; Tue, 20 Aug 2019 00:18:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D898C22CF5 for ; Tue, 20 Aug 2019 00:18:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="BO4kQ093" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729053AbfHTASs (ORCPT ); Mon, 19 Aug 2019 20:18:48 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:51867 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729043AbfHTASr (ORCPT ); Mon, 19 Aug 2019 20:18:47 -0400 Received: by mail-qk1-f201.google.com with SMTP id y188so5199909qke.18 for ; Mon, 19 Aug 2019 17:18:47 -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=cqqNQcjxZKCBbJrhwZmXlaL29Q1qsVjTwEkp4+lUxdU=; b=BO4kQ0935/Y6yDgFnhcP8U6VvEnTvdTFa/3/fszoNSnRJF6dFBqhAjx6db960YfW0K qw9yz47/8ZyE7El9zyKrpX6FxYTqfCOL/KV4sKWwPji/sOlAKKSZJGMnIfy08kBE/oZj 5Ow1ygy8tsS7ANpFzOe7Kp1U16F48xU8m+P1WFrA1xc3bLm6Jgh5b9hFkkh5oaITb+Ji sWSWe0i1edcvaMRxj6V14kv8WeQFfDfQM3JvK0bj3fESox4Fnq9hVhynGXjBbP3l99Ut R8L+pMW90KxNobngtePTakpHnAIOlPcoCK4QFSrTWkmEbbuLhqiAbOcS0Cx5ErD3vfgm UIiQ== 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=cqqNQcjxZKCBbJrhwZmXlaL29Q1qsVjTwEkp4+lUxdU=; b=SzK14z93Ga09suLioAGfhSnAwaSUEqG7bkcKLXaPoffush8354ySLWI9ivmmxY4eN+ NtMLu3LXY00Q46d0m4dXHde8rsCobeMlmfNozeeImOsorFATPjBNLaMFVDqN6MfwvGjI /EG19oDugywuSD9b48hlFTVhwzWd8fJsigvr7udwTDTLPZTrhda/acU7xIPCWPYWtymQ xFR0gGYsHpdcABs69N5lfZJvbSCoeF4JGgK/HUMM+pALr4f5Gf62yY7+2N5tO8Ipr25T qvTB//t/bePDa4pO95n2epJPqtcEMYvA2bbwdCS60rEMCHCSPRtCdUZELkVFt3vzKJRO dmMw== X-Gm-Message-State: APjAAAXXNhL7n95kKH2yUJoUXs2fZ3Nic5UsuofROW/cgXh5KXdhAwgb y9NVxAh6CqHRxDjH2rGbOaenmkz3/kbNy4TjeQJA9A== X-Google-Smtp-Source: APXvYqxswIM8pnBZTf4JSFzJH5iVwegnGiEXZPza+6Bn5dQaguOlalUfABkzQuHVZ7Yhx2xki+lP2+gvBt9AxTPDA6C5Hw== X-Received: by 2002:a05:620a:1413:: with SMTP id d19mr23052964qkj.341.1566260326602; Mon, 19 Aug 2019 17:18:46 -0700 (PDT) Date: Mon, 19 Aug 2019 17:17:50 -0700 In-Reply-To: <20190820001805.241928-1-matthewgarrett@google.com> Message-Id: <20190820001805.241928-15-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190820001805.241928-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.23.0.rc1.153.gdeed80330f-goog Subject: [PATCH V40 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: 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 Signed-off-by: James Morris Acked-by: Rafael J. Wysocki --- 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 010637a79eac..390e39395112 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 b1c1c72440d5..6d44db0ddffa 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", };