From patchwork Tue Jun 23 00:32:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 11619471 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 8EC5C90 for ; Tue, 23 Jun 2020 00:34:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7688E2053B for ; Tue, 23 Jun 2020 00:34:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="BayDO+uA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731984AbgFWAeX (ORCPT ); Mon, 22 Jun 2020 20:34:23 -0400 Received: from linux.microsoft.com ([13.77.154.182]:47504 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731927AbgFWAeW (ORCPT ); Mon, 22 Jun 2020 20:34:22 -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 B433620B7192; Mon, 22 Jun 2020 17:34:20 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com B433620B7192 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1592872461; bh=ezz4s3uOPz8Mcn01u6sEHjTUJKKCcNFUFhLQPxlyvX4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BayDO+uAqIG1o1otFsdXeto+CR9kn3dWZuJJ9u2WvmB+3LlQU6SaEMdNQHGm//30b bOSPCvK/JLV1Wqr+BYC78CnVaX6Ot1bBkLQ98R1REseKpWF/yahNw/vszo4dZcuyle tqdCnxnPcjBJDEQJanSyhJpEm9ncqAOyD+hocUms= 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 06/12] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond Date: Mon, 22 Jun 2020 19:32:30 -0500 Message-Id: <20200623003236.830149-7-tyhicks@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200623003236.830149-1-tyhicks@linux.microsoft.com> References: <20200623003236.830149-1-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 --- 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 ecc234b956a2..83975ad22907 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -349,6 +349,17 @@ 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 @@ -999,6 +1010,16 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) case POLICY_CHECK: 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;