From patchwork Fri Apr 9 11:43:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12193919 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0872C43603 for ; Fri, 9 Apr 2021 11:43:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD13661005 for ; Fri, 9 Apr 2021 11:43:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233293AbhDILn7 (ORCPT ); Fri, 9 Apr 2021 07:43:59 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:2820 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231611AbhDILn6 (ORCPT ); Fri, 9 Apr 2021 07:43:58 -0400 Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4FGwy76S3wz685bH; Fri, 9 Apr 2021 19:34:07 +0800 (CST) Received: from fraphisprd00473.huawei.com (7.182.8.141) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Fri, 9 Apr 2021 13:43:43 +0200 From: Roberto Sassu To: CC: , , , Roberto Sassu Subject: [PATCH 2/7] ima: Add meta_immutable appraisal type Date: Fri, 9 Apr 2021 13:43:08 +0200 Message-ID: <20210409114313.4073-3-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210409114313.4073-1-roberto.sassu@huawei.com> References: <20210409114313.4073-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [7.182.8.141] X-ClientProxiedBy: lhreml754-chm.china.huawei.com (10.201.108.204) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Currently, IMA supports the appraise_type=imasig option in the policy to require signed file content or metadata. This patch introduces the new option appraise_type=meta_immutable to require that file metadata is also immutable, i.e. it cannot have been produced by the system itself but only from a vendor whose signing key is trusted by the kernel. Currently, this requirement can be satisfied only by portable signatures. The main purpose of this option is to ensure a proper label transition during binary execution, when the target label depends on the label of the binary being executed. Without it, an administrator might obtain a different target label by changing the label of the executable. Signed-off-by: Roberto Sassu --- Documentation/ABI/testing/ima_policy | 2 +- security/integrity/ima/ima_appraise.c | 9 +++++++++ security/integrity/ima/ima_policy.c | 13 ++++++++++--- security/integrity/integrity.h | 1 + 4 files changed, 21 insertions(+), 4 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 070779e8d836..bc6597db7c78 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -42,7 +42,7 @@ Description: fowner:= decimal value lsm: are LSM specific option: - appraise_type:= [imasig] [imasig|modsig] + appraise_type:= [imasig] [imasig|modsig] [meta_immutable] appraise_flag:= [check_blacklist] Currently, blacklist check is only for files signed with appended signature. diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 45e244fc2ef2..5814b8cbe86c 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -430,6 +430,15 @@ int ima_appraise_measurement(enum ima_hooks func, WARN_ONCE(true, "Unexpected integrity status %d\n", status); } + if ((iint->flags & IMA_META_IMMUTABLE_REQUIRED) && + status != INTEGRITY_PASS_IMMUTABLE) { + status = INTEGRITY_FAIL; + cause = "metadata-modifiable"; + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, + filename, op, cause, rc, 0); + goto out; + } + if (xattr_value) rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, &cause); diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 4f8cb155e4fd..33b5133645b3 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -1079,7 +1079,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) return false; if (entry->action != APPRAISE && - entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST)) + entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED | + IMA_CHECK_BLACKLIST | IMA_META_IMMUTABLE_REQUIRED)) return false; /* @@ -1109,7 +1110,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) IMA_UID | IMA_FOWNER | IMA_FSUUID | IMA_INMASK | IMA_EUID | IMA_PCR | IMA_FSNAME | IMA_DIGSIG_REQUIRED | - IMA_PERMIT_DIRECTIO)) + IMA_PERMIT_DIRECTIO | + IMA_META_IMMUTABLE_REQUIRED)) return false; break; @@ -1121,7 +1123,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) IMA_INMASK | IMA_EUID | IMA_PCR | IMA_FSNAME | IMA_DIGSIG_REQUIRED | IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED | - IMA_CHECK_BLACKLIST)) + IMA_CHECK_BLACKLIST | + IMA_META_IMMUTABLE_REQUIRED)) return false; break; @@ -1495,6 +1498,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) strcmp(args[0].from, "imasig|modsig") == 0) entry->flags |= IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED; + else if (strcmp(args[0].from, "meta_immutable") == 0) + entry->flags |= IMA_META_IMMUTABLE_REQUIRED; else result = -EINVAL; break; @@ -1850,6 +1855,8 @@ int ima_policy_show(struct seq_file *m, void *v) } if (entry->flags & IMA_CHECK_BLACKLIST) seq_puts(m, "appraise_flag=check_blacklist "); + if (entry->flags & IMA_META_IMMUTABLE_REQUIRED) + seq_puts(m, "appraise_type=meta_immutable "); 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 547425c20e11..be501a63ae30 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -39,6 +39,7 @@ #define IMA_FAIL_UNVERIFIABLE_SIGS 0x10000000 #define IMA_MODSIG_ALLOWED 0x20000000 #define IMA_CHECK_BLACKLIST 0x40000000 +#define IMA_META_IMMUTABLE_REQUIRED 0x80000000 #define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \ IMA_HASH | IMA_APPRAISE_SUBMASK)