From patchwork Thu Dec 13 02:09:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thiago Jung Bauermann X-Patchwork-Id: 10727577 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 0274514BD for ; Thu, 13 Dec 2018 02:12:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E7F812BA47 for ; Thu, 13 Dec 2018 02:12:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DC72B2BA46; Thu, 13 Dec 2018 02:12:01 +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=unavailable 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 498922BA42 for ; Thu, 13 Dec 2018 02:12:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726997AbeLMCLy (ORCPT ); Wed, 12 Dec 2018 21:11:54 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47544 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726988AbeLMCLy (ORCPT ); Wed, 12 Dec 2018 21:11:54 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wBD23jSm116315 for ; Wed, 12 Dec 2018 21:11:53 -0500 Received: from e36.co.us.ibm.com (e36.co.us.ibm.com [32.97.110.154]) by mx0b-001b2d01.pphosted.com with ESMTP id 2pb8ku75r6-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 12 Dec 2018 21:11:53 -0500 Received: from localhost by e36.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 13 Dec 2018 02:11:47 -0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wBD2BjIT17301516 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 13 Dec 2018 02:11:45 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A4638C6057; Thu, 13 Dec 2018 02:11:45 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 40D82C605B; Thu, 13 Dec 2018 02:11:41 +0000 (GMT) Received: from morokweng.localdomain.com (unknown [9.80.227.60]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 13 Dec 2018 02:11:41 +0000 (GMT) From: Thiago Jung Bauermann To: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Mimi Zohar , Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , David Howells , David Woodhouse , Jessica Yu , Herbert Xu , "David S. Miller" , Jonathan Corbet , "AKASHI, Takahiro" , Thiago Jung Bauermann Subject: [PATCH v9 10/14] ima: Add modsig appraise_type option for module-style appended signatures Date: Thu, 13 Dec 2018 00:09:03 -0200 X-Mailer: git-send-email 2.17.2 In-Reply-To: <20181213020907.13601-1-bauerman@linux.ibm.com> References: <20181213020907.13601-1-bauerman@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18121302-0020-0000-0000-00000E98FB71 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010217; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01130951; UDB=6.00587714; IPR=6.00911085; MB=3.00024674; MTD=3.00000008; XFM=3.00000015; UTC=2018-12-13 02:11:51 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18121302-0021-0000-0000-000064081CE2 Message-Id: <20181213020907.13601-11-bauerman@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-12-12_04:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812130017 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Introduce the modsig keyword to the IMA policy syntax to specify that a given hook should expect the file to have the IMA signature appended to it. Here is how it can be used in a rule: appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig With this rule, IMA will accept either a signature stored in the extended attribute or an appended signature. For now, the rule above will behave exactly the same as if appraise_type=imasig was specified. The actual modsig implementation will be introduced separately. Suggested-by: Mimi Zohar Signed-off-by: Thiago Jung Bauermann --- Documentation/ABI/testing/ima_policy | 6 +++++- security/integrity/ima/Kconfig | 10 +++++++++ security/integrity/ima/Makefile | 1 + security/integrity/ima/ima.h | 9 ++++++++ security/integrity/ima/ima_modsig.c | 31 ++++++++++++++++++++++++++++ security/integrity/ima/ima_policy.c | 12 +++++++++-- security/integrity/integrity.h | 1 + 7 files changed, 67 insertions(+), 3 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 74c6702de74e..9d1dfd0a8891 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -37,7 +37,7 @@ Description: euid:= decimal value fowner:= decimal value lsm: are LSM specific - option: appraise_type:= [imasig] + option: appraise_type:= [imasig] [imasig|modsig] pcr:= decimal value default policy: @@ -103,3 +103,7 @@ Description: measure func=KEXEC_KERNEL_CHECK pcr=4 measure func=KEXEC_INITRAMFS_CHECK pcr=5 + + Example of appraise rule allowing modsig appended signatures: + + appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index a18f8c6d13b5..bba19f9ea184 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -231,6 +231,16 @@ config IMA_APPRAISE_BOOTPARAM This option enables the different "ima_appraise=" modes (eg. fix, log) from the boot command line. +config IMA_APPRAISE_MODSIG + bool "Support module-style signatures for appraisal" + depends on IMA_APPRAISE + default n + help + Adds support for signatures appended to files. The format of the + appended signature is the same used for signed kernel modules. + The modsig keyword can be used in the IMA policy to allow a hook + to accept such signatures. + config IMA_TRUSTED_KEYRING bool "Require all keys on the .ima keyring be signed (deprecated)" depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile index d921dc4f9eb0..31d57cdf2421 100644 --- a/security/integrity/ima/Makefile +++ b/security/integrity/ima/Makefile @@ -9,5 +9,6 @@ obj-$(CONFIG_IMA) += ima.o ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \ ima_policy.o ima_template.o ima_template_lib.o ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o +ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index f0bc2a182cbf..69c06e2d7bd6 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -299,6 +299,15 @@ static inline int ima_read_xattr(struct dentry *dentry, #endif /* CONFIG_IMA_APPRAISE */ +#ifdef CONFIG_IMA_APPRAISE_MODSIG +bool ima_hook_supports_modsig(enum ima_hooks func); +#else +static inline bool ima_hook_supports_modsig(enum ima_hooks func) +{ + return false; +} +#endif /* CONFIG_IMA_APPRAISE_MODSIG */ + /* LSM based policy rules require audit */ #ifdef CONFIG_IMA_LSM_RULES diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c new file mode 100644 index 000000000000..08182bd7f445 --- /dev/null +++ b/security/integrity/ima/ima_modsig.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * IMA support for appraising module-style appended signatures. + * + * Copyright (C) 2018 IBM Corporation + * + * Author: + * Thiago Jung Bauermann + */ + +#include "ima.h" + +/** + * ima_hook_supports_modsig - can the policy allow modsig for this hook? + * + * modsig is only supported by hooks using ima_post_read_file, because only they + * preload the contents of the file in a buffer. FILE_CHECK does that in some + * cases, but not when reached from vfs_open. POLICY_CHECK can support it, but + * it's not useful in practice because it's a text file so deny. + */ +bool ima_hook_supports_modsig(enum ima_hooks func) +{ + switch (func) { + case KEXEC_KERNEL_CHECK: + case KEXEC_INITRAMFS_CHECK: + case MODULE_CHECK: + return true; + default: + return false; + } +} diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index b7ee342fbe4a..c38a63f56b7b 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -1036,6 +1036,10 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) ima_log_string(ab, "appraise_type", args[0].from); if ((strcmp(args[0].from, "imasig")) == 0) entry->flags |= IMA_DIGSIG_REQUIRED; + else if (ima_hook_supports_modsig(entry->func) && + strcmp(args[0].from, "imasig|modsig") == 0) + entry->flags |= IMA_DIGSIG_REQUIRED + | IMA_MODSIG_ALLOWED; else result = -EINVAL; break; @@ -1328,8 +1332,12 @@ int ima_policy_show(struct seq_file *m, void *v) } } } - if (entry->flags & IMA_DIGSIG_REQUIRED) - seq_puts(m, "appraise_type=imasig "); + if (entry->flags & IMA_DIGSIG_REQUIRED) { + if (entry->flags & IMA_MODSIG_ALLOWED) + seq_puts(m, "appraise_type=imasig|modsig "); + else + seq_puts(m, "appraise_type=imasig "); + } if (entry->flags & IMA_PERMIT_DIRECTIO) seq_puts(m, "permit_directio "); rcu_read_unlock(); diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index dec5ab8cf9e9..4549488a048a 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -36,6 +36,7 @@ #define IMA_NEW_FILE 0x04000000 #define EVM_IMMUTABLE_DIGSIG 0x08000000 #define IMA_FAIL_UNVERIFIABLE_SIGS 0x10000000 +#define IMA_MODSIG_ALLOWED 0x20000000 #define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \ IMA_HASH | IMA_APPRAISE_SUBMASK)