From patchwork Thu May 24 11:09:35 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 10424245 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C3D4D6032A for ; Thu, 24 May 2018 11:11:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C56522939A for ; Thu, 24 May 2018 11:11:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BA37B293A0; Thu, 24 May 2018 11:11:29 +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 2630F293B6 for ; Thu, 24 May 2018 11:11:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968143AbeEXLL1 (ORCPT ); Thu, 24 May 2018 07:11:27 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:54452 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1033067AbeEXLKq (ORCPT ); Thu, 24 May 2018 07:10:46 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w4OB08of114052 for ; Thu, 24 May 2018 07:10:46 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0b-001b2d01.pphosted.com with ESMTP id 2j5s7xr9vd-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 24 May 2018 07:10:44 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 24 May 2018 12:10:39 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w4OBAciW5570916; Thu, 24 May 2018 11:10:38 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EB80011C04A; Thu, 24 May 2018 12:01:42 +0100 (BST) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8F5B111C050; Thu, 24 May 2018 12:01:41 +0100 (BST) Received: from localhost.ibm.com (unknown [9.80.85.225]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 24 May 2018 12:01:41 +0100 (BST) From: Mimi Zohar To: linux-integrity@vger.kernel.org Cc: Mimi Zohar , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, David Howells , "Luis R . Rodriguez" , Eric Biederman , kexec@lists.infradead.org, Andres Rodriguez , Greg Kroah-Hartman , Ard Biesheuvel Subject: [PATCH v3 6/7] ima: add build time policy Date: Thu, 24 May 2018 07:09:35 -0400 X-Mailer: git-send-email 2.7.5 In-Reply-To: <1527160176-29269-1-git-send-email-zohar@linux.vnet.ibm.com> References: <1527160176-29269-1-git-send-email-zohar@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18052411-0012-0000-0000-000005DA20ED X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18052411-0013-0000-0000-000019576FA0 Message-Id: <1527160176-29269-7-git-send-email-zohar@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-05-24_03:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805240132 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP IMA by default does not measure, appraise or audit files, but can be enabled at runtime by specifying a builtin policy on the boot command line or by loading a custom policy. This patch defines a build time policy, which verifies kernel modules, firmware, kexec image, and/or the IMA policy signatures. This build time policy is automatically enabled at runtime. The build time policy rules persist after loading a custom policy. Signed-off-by: Mimi Zohar --- security/integrity/ima/Kconfig | 58 +++++++++++++++++++++++++++++++++++++ security/integrity/ima/ima_policy.c | 46 +++++++++++++++++++++++++++-- 2 files changed, 101 insertions(+), 3 deletions(-) diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index 6a8f67714c83..004919d9bf09 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -156,6 +156,64 @@ config IMA_APPRAISE If unsure, say N. +config IMA_APPRAISE_BUILD_POLICY + bool "IMA build time configured policy rules" + depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS + default n + help + This option defines an IMA appraisal policy at build time, which + is enforced at run time without having to specify a builtin + policy name on the boot command line. The build time appraisal + policy rules persist after loading a custom policy. + + Depending on the rules configured, this policy may require kernel + modules, firmware, the kexec kernel image, and/or the IMA policy + to be signed. Unsigned files might prevent the system from + booting or applications from working properly. + +config IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS + bool "Appraise firmware signatures" + depends on IMA_APPRAISE_BUILD_POLICY + default n + help + This option defines a policy requiring all firmware to be signed, + including the regulatory.db. If both this option and + CFG80211_REQUIRE_SIGNED_REGDB are enabled, then both signature + verification methods are necessary. + +config IMA_APPRAISE_REQUIRE_KEXEC_SIGS + bool "Appraise kexec kernel image signatures" + depends on IMA_APPRAISE_BUILD_POLICY + default n + help + Enabling this rule will require all kexec'ed kernel images to + be signed and verified by a public key on the trusted IMA + keyring. + + Kernel image signatures can not be verified by the original + kexec_load syscall. Enabling this rule will prevent its + usage. + +config IMA_APPRAISE_REQUIRE_MODULE_SIGS + bool "Appraise kernel modules signatures" + depends on IMA_APPRAISE_BUILD_POLICY + default n + help + Enabling this rule will require all kernel modules to be signed + and verified by a public key on the trusted IMA keyring. + + Kernel module signatures can only be verified by IMA-appraisal, + via the finit_module syscall. Enabling this rule will prevent + the usage of the init_module syscall. + +config IMA_APPRAISE_REQUIRE_POLICY_SIGS + bool "Appraise IMA policy signature" + depends on IMA_APPRAISE_BUILD_POLICY + default n + help + Enabling this rule will require the IMA policy to be signed and + and verified by a key on the trusted IMA keyring. + config IMA_APPRAISE_BOOTPARAM bool "ima_appraise boot parameter" depends on IMA_APPRAISE diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index c27f6993b07a..3c0bc8a1a88e 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -49,6 +49,7 @@ int ima_policy_flag; static int temp_ima_appraise; +static int build_ima_appraise __ro_after_init; #define MAX_LSM_RULES 6 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE, @@ -162,6 +163,25 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = { #endif }; +static struct ima_rule_entry build_appraise_rules[] __ro_after_init = { +#ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS + {.action = APPRAISE, .func = MODULE_CHECK, + .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, +#endif +#ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS + {.action = APPRAISE, .func = FIRMWARE_CHECK, + .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, +#endif +#ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS + {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK, + .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, +#endif +#ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS + {.action = APPRAISE, .func = POLICY_CHECK, + .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, +#endif +}; + static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { {.action = APPRAISE, .func = MODULE_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, @@ -435,7 +455,7 @@ void ima_update_policy_flag(void) ima_policy_flag |= entry->action; } - ima_appraise |= temp_ima_appraise; + ima_appraise |= (build_ima_appraise | temp_ima_appraise); if (!ima_appraise) ima_policy_flag &= ~IMA_APPRAISE; } @@ -488,8 +508,8 @@ void __init ima_init_policy(void) } /* - * Insert the appraise rules requiring file signatures, prior to - * any other appraise rules. + * Insert the builtin "secure_boot" policy rules requiring file + * signatures, prior to any other appraise rules. */ for (i = 0; i < secure_boot_entries; i++) { list_add_tail(&secure_boot_rules[i].list, &ima_default_rules); @@ -497,6 +517,26 @@ void __init ima_init_policy(void) ima_appraise_flag(secure_boot_rules[i].func); } + /* + * Insert the build time appraise rules requiring file signatures + * for both the initial and custom policies, prior to other appraise + * rules. + */ + for (i = 0; i < ARRAY_SIZE(build_appraise_rules); i++) { + struct ima_rule_entry *entry; + + if (!secure_boot_entries) + list_add_tail(&build_appraise_rules[i].list, + &ima_default_rules); + + entry = kmemdup(&build_appraise_rules[i], sizeof(*entry), + GFP_KERNEL); + if (entry) + list_add_tail(&entry->list, &ima_policy_rules); + build_ima_appraise |= + ima_appraise_flag(build_appraise_rules[i].func); + } + for (i = 0; i < appraise_entries; i++) { list_add_tail(&default_appraise_rules[i].list, &ima_default_rules);