From patchwork Fri Aug 28 01:57:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tushar Sugandhi X-Patchwork-Id: 11742043 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 209E313B1 for ; Fri, 28 Aug 2020 01:57:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 081DF20848 for ; Fri, 28 Aug 2020 01:57:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="Cyz/YHC3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728363AbgH1B5Y (ORCPT ); Thu, 27 Aug 2020 21:57:24 -0400 Received: from linux.microsoft.com ([13.77.154.182]:38500 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728353AbgH1B5V (ORCPT ); Thu, 27 Aug 2020 21:57:21 -0400 Received: from tusharsu-Ubuntu.lan (c-71-197-163-6.hsd1.wa.comcast.net [71.197.163.6]) by linux.microsoft.com (Postfix) with ESMTPSA id 5BEF120C27C5; Thu, 27 Aug 2020 18:57:20 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5BEF120C27C5 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1598579840; bh=/oNkgUW9zSIuVV9hzhJDu+lqIFChEKC0BuHbXmW5m3Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cyz/YHC3WltXaOC2W1Hu7dvdzMKlVlrik0OyrAKvc3bYjiBOWarXk/sMLKG5Rg302 fbDJaPYrLp1qHtc2FhixkEyPt5aRcJ9BDsKfLQZuW7svV2PjA1czuY27qzJ0eRdFwn TEcJ+5giT+ILXTcXHTRG3KaEqEnPdHzOp8Y6cqDM= From: Tushar Sugandhi To: zohar@linux.ibm.com, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com, gmazyland@gmail.com Cc: tyhicks@linux.microsoft.com, sashal@kernel.org, jmorris@namei.org, nramas@linux.microsoft.com, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com Subject: [PATCH v3 6/6] IMA: validate supported kernel data sources before measurement Date: Thu, 27 Aug 2020 18:57:04 -0700 Message-Id: <20200828015704.6629-7-tusharsu@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200828015704.6629-1-tusharsu@linux.microsoft.com> References: <20200828015704.6629-1-tusharsu@linux.microsoft.com> Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org Currently, IMA does not restrict random data sources from measuring their data using ima_measure_critical_data(). Any kernel data source can call the function, and it's data will get measured as long as the input event_data_source is part of the IMA policy - CRITICAL_DATA+critical_kernel_data_sources. This may result in IMA log getting bloated by random data sources. Supporting random data sources at run-time may also impact the reliability of the system. To ensure that only data from supported sources are measured, the kernel component needs to be added to a compile-time list of supported sources (an "allowed list of components") in ima.h. IMA then validates the input parameter - event_data_source passed to ima_measure_critical_data() against this allowed list at run-time. Provide an infrastructure for kernel data sources to be added to the supported data sources list at compile-time. Update ima_measure_critical_data() to validate, at run-time, that the data source is supported before measuring the data. Signed-off-by: Tushar Sugandhi --- security/integrity/ima/ima.h | 29 +++++++++++++++++++++++++++++ security/integrity/ima/ima_main.c | 3 +++ 2 files changed, 32 insertions(+) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 00b84052c8f1..ecb0a1e7378f 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -228,6 +228,35 @@ extern const char *const func_tokens[]; struct modsig; +#define __ima_supported_kernel_data_sources(source) \ + source(MIN_SOURCE, min_source) \ + source(MAX_SOURCE, max_source) + +#define __ima_enum_stringify(ENUM, str) (#str), + +enum ima_supported_kernel_data_sources { + __ima_supported_kernel_data_sources(__ima_hook_enumify) +}; + +static const char * const ima_supported_kernel_data_sources_str[] = { + __ima_supported_kernel_data_sources(__ima_enum_stringify) +}; + +static inline bool ima_kernel_data_source_is_supported(const char *source) +{ + int i; + + if (!source) + return false; + + for (i = MIN_SOURCE + 1; i < MAX_SOURCE; i++) { + if (!strcmp(ima_supported_kernel_data_sources_str[i], source)) + return true; + } + + return false; +} + #ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS /* * To track keys that need to be measured. diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index a889bf40cb7e..41be4d1d839e 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -888,6 +888,9 @@ int ima_measure_critical_data(const char *event_name, if (!event_name || !event_data_source || !buf || !buf_len) return -EINVAL; + if (!ima_kernel_data_source_is_supported(event_data_source)) + return -EPERM; + return process_buffer_measurement(NULL, buf, buf_len, event_name, CRITICAL_DATA, 0, event_data_source, measure_buf_hash);