From patchwork Thu Jul 9 06:19:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 11653429 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 9885613B1 for ; Thu, 9 Jul 2020 06:20:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A69D206C3 for ; Thu, 9 Jul 2020 06:20:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="aJKK1MaG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726410AbgGIGUF (ORCPT ); Thu, 9 Jul 2020 02:20:05 -0400 Received: from linux.microsoft.com ([13.77.154.182]:38020 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726196AbgGIGUE (ORCPT ); Thu, 9 Jul 2020 02:20:04 -0400 Received: from sequoia.work.tihix.com (162-237-133-238.lightspeed.rcsntx.sbcglobal.net [162.237.133.238]) by linux.microsoft.com (Postfix) with ESMTPSA id 5A5A120B490A; Wed, 8 Jul 2020 23:20:03 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5A5A120B490A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1594275604; bh=z5BEppbXhpdSAyDudc6kYWlfCNHPdX4otoJgm257sFU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aJKK1MaGaR61+T37x4NLFrTDg7UzgxY0bbvDNRKTeO0N00x56mP6ZuB9w0Ri0uvr3 UxXXsGpThVKOY+Fz0po2J1zTGi76glRbydOf7jY8ne+uemlI5bKRPSJOMuzCC0nvtG f/VeQXvFJkeUU50VyYVvW8MN0JKJlcRS1202n82w= From: Tyler Hicks To: Mimi Zohar , Dmitry Kasatkin Cc: James Morris , "Serge E . Hallyn" , Lakshmi Ramasubramanian , Prakhar Srivastava , linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v3 05/12] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond Date: Thu, 9 Jul 2020 01:19:04 -0500 Message-Id: <20200709061911.954326-6-tyhicks@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200709061911.954326-1-tyhicks@linux.microsoft.com> References: <20200709061911.954326-1-tyhicks@linux.microsoft.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: The KEXEC_CMDLINE hook function only supports the pcr conditional. Make this clear at policy load so that IMA policy authors don't assume that other conditionals are supported. Since KEXEC_CMDLINE's inception, ima_match_rules() has always returned true on any loaded KEXEC_CMDLINE rule without any consideration for other conditionals present in the rule. Make it clear that pcr is the only supported KEXEC_CMDLINE conditional by returning an error during policy load. An example of why this is a problem can be explained with the following rule: dont_measure func=KEXEC_CMDLINE obj_type=foo_t An IMA policy author would have assumed that rule is valid because the parser accepted it but the result was that measurements for all KEXEC_CMDLINE operations would be disabled. Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments") Signed-off-by: Tyler Hicks Reviewed-by: Mimi Zohar Reviewed-by: Lakshmi Ramasubramanian --- * v3 - Adjust for the indentation change introduced in patch #4 - Added Lakshmi's Reviewed-by * v2 - Added Mimi's Reviewed-by security/integrity/ima/ima_policy.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 40c28f1a6a5a..1c64bd6f1728 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -343,6 +343,17 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry) return 0; } +static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry) +{ + int i; + + for (i = 0; i < MAX_LSM_RULES; i++) + if (entry->lsm[i].args_p) + return true; + + return false; +} + /* * The LSM policy can be reloaded, leaving the IMA LSM based rules referring * to the old, stale LSM policy. Update the IMA LSM based rules to reflect @@ -998,6 +1009,16 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) /* Validation of these hook functions is in ima_parse_rule() */ break; case KEXEC_CMDLINE: + if (entry->action & ~(MEASURE | DONT_MEASURE)) + return false; + + if (entry->flags & ~(IMA_FUNC | IMA_PCR)) + return false; + + if (ima_rule_contains_lsm_cond(entry)) + return false; + + break; case KEY_CHECK: if (entry->action & ~(MEASURE | DONT_MEASURE)) return false;