From patchwork Wed May 29 13:30:34 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 10967127 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 9E52F1398 for ; Wed, 29 May 2019 13:35:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 90559205A4 for ; Wed, 29 May 2019 13:35:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8294A28517; Wed, 29 May 2019 13:35:43 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI 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 06A4D286C1 for ; Wed, 29 May 2019 13:35:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727081AbfE2Nfm (ORCPT ); Wed, 29 May 2019 09:35:42 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:32973 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726702AbfE2Nfm (ORCPT ); Wed, 29 May 2019 09:35:42 -0400 Received: from lhreml709-cah.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id A920149401E1EF5D8FE5; Wed, 29 May 2019 14:35:40 +0100 (IST) Received: from roberto-HP-EliteDesk-800-G2-DM-65W.huawei.com (10.204.65.154) by smtpsuk.huawei.com (10.201.108.32) with Microsoft SMTP Server (TLS) id 14.3.408.0; Wed, 29 May 2019 14:35:34 +0100 From: Roberto Sassu To: , , CC: , , , , , Roberto Sassu , Subject: [PATCH v2 2/3] ima: don't ignore INTEGRITY_UNKNOWN EVM status Date: Wed, 29 May 2019 15:30:34 +0200 Message-ID: <20190529133035.28724-3-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190529133035.28724-1-roberto.sassu@huawei.com> References: <20190529133035.28724-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.65.154] X-CFilter-Loop: Reflected Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Currently, ima_appraise_measurement() ignores the EVM status when evm_verifyxattr() returns INTEGRITY_UNKNOWN. If a file has a valid security.ima xattr with type IMA_XATTR_DIGEST or IMA_XATTR_DIGEST_NG, ima_appraise_measurement() returns INTEGRITY_PASS regardless of the EVM status. The problem is that the EVM status is overwritten with the appraisal status. This patch mitigates the issue by selecting signature verification as the only method allowed for appraisal when EVM is not initialized. Since the new behavior might break user space, it must be turned on by adding the '-evm' suffix to the value of the ima_appraise= kernel option. Fixes: 2fe5d6def1672 ("ima: integrity appraisal extension") Signed-off-by: Roberto Sassu Cc: stable@vger.kernel.org --- Documentation/admin-guide/kernel-parameters.txt | 3 ++- security/integrity/ima/ima_appraise.c | 8 ++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 138f6664b2e2..d84a2e612b93 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1585,7 +1585,8 @@ Set number of hash buckets for inode cache. ima_appraise= [IMA] appraise integrity measurements - Format: { "off" | "enforce" | "fix" | "log" } + Format: { "off" | "enforce" | "fix" | "log" | + "enforce-evm" | "log-evm" } default: "enforce" ima_appraise_tcb [IMA] Deprecated. Use ima_policy= instead. diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 5fb7127bbe68..afef06e10fb9 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -18,6 +18,7 @@ #include "ima.h" +static bool ima_appraise_req_evm __ro_after_init; static int __init default_appraise_setup(char *str) { #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM @@ -28,6 +29,9 @@ static int __init default_appraise_setup(char *str) else if (strncmp(str, "fix", 3) == 0) ima_appraise = IMA_APPRAISE_FIX; #endif + if (strcmp(str, "enforce-evm") == 0 || + strcmp(str, "log-evm") == 0) + ima_appraise_req_evm = true; return 1; } @@ -245,7 +249,11 @@ int ima_appraise_measurement(enum ima_hooks func, switch (status) { case INTEGRITY_PASS: case INTEGRITY_PASS_IMMUTABLE: + break; case INTEGRITY_UNKNOWN: + if (ima_appraise_req_evm && + xattr_value->type != EVM_IMA_XATTR_DIGSIG) + goto out; break; case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ case INTEGRITY_NOLABEL: /* No security.evm xattr. */