From patchwork Fri Mar 5 15:19:22 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12118719 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=unavailable 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 37DCDC432C3 for ; Fri, 5 Mar 2021 15:23:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CBB36508D for ; Fri, 5 Mar 2021 15:23:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229798AbhCEPWn (ORCPT ); Fri, 5 Mar 2021 10:22:43 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2633 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229848AbhCEPWY (ORCPT ); Fri, 5 Mar 2021 10:22:24 -0500 Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4DsWZj40t7z67ty2; Fri, 5 Mar 2021 23:18:05 +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_CBC_SHA256) id 15.1.2106.2; Fri, 5 Mar 2021 16:22:21 +0100 From: Roberto Sassu To: , CC: , , , , Roberto Sassu Subject: [PATCH v4 10/11] ima: Introduce template field evmsig and write to field sig as fallback Date: Fri, 5 Mar 2021 16:19:22 +0100 Message-ID: <20210305151923.29039-11-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210305151923.29039-1-roberto.sassu@huawei.com> References: <20210305151923.29039-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [7.182.8.141] X-ClientProxiedBy: lhreml707-chm.china.huawei.com (10.201.108.56) 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 With the patch to accept EVM portable signatures when the appraise_type=imasig requirement is specified in the policy, appraisal can be successfully done even if the file does not have an IMA signature. However, remote attestation would not see that a different signature type was used, as only IMA signatures can be included in the measurement list. This patch solves the issue by introducing the new template field 'evmsig' to show EVM portable signatures and by including its value in the existing field 'sig' if the IMA signature is not found. Signed-off-by: Roberto Sassu Suggested-by: Mimi Zohar --- Documentation/security/IMA-templates.rst | 4 ++- security/integrity/ima/ima_template.c | 2 ++ security/integrity/ima/ima_template_lib.c | 33 ++++++++++++++++++++++- security/integrity/ima/ima_template_lib.h | 2 ++ 4 files changed, 39 insertions(+), 2 deletions(-) diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index c5a8432972ef..9f3e86ab028a 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -70,9 +70,11 @@ descriptors by adding their identifier to the format string prefix is shown only if the hash algorithm is not SHA1 or MD5); - 'd-modsig': the digest of the event without the appended modsig; - 'n-ng': the name of the event, without size limitations; - - 'sig': the file signature; + - 'sig': the file signature, or the EVM portable signature if the file + signature is not found; - 'modsig' the appended file signature; - 'buf': the buffer data that was used to generate the hash without size limitations; + - 'evmsig': the EVM portable signature; Below, there is the list of defined template descriptors: diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index e22e510ae92d..90e8a8282927 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -45,6 +45,8 @@ static const struct ima_template_field supported_fields[] = { .field_show = ima_show_template_digest_ng}, {.field_id = "modsig", .field_init = ima_eventmodsig_init, .field_show = ima_show_template_sig}, + {.field_id = "evmsig", .field_init = ima_eventevmsig_init, + .field_show = ima_show_template_sig}, }; /* diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index c022ee9e2a4e..4314d9a3514c 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -10,6 +10,7 @@ */ #include "ima_template_lib.h" +#include static bool ima_template_hash_algo_allowed(u8 algo) { @@ -438,7 +439,7 @@ int ima_eventsig_init(struct ima_event_data *event_data, struct evm_ima_xattr_data *xattr_value = event_data->xattr_value; if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG)) - return 0; + return ima_eventevmsig_init(event_data, field_data); return ima_write_template_field_data(xattr_value, event_data->xattr_len, DATA_FMT_HEX, field_data); @@ -484,3 +485,33 @@ int ima_eventmodsig_init(struct ima_event_data *event_data, return ima_write_template_field_data(data, data_len, DATA_FMT_HEX, field_data); } + +/* + * ima_eventevmsig_init - include the EVM portable signature as part of the + * template data + */ +int ima_eventevmsig_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + struct evm_ima_xattr_data *xattr_data = NULL; + int rc = 0; + + if (!event_data->file) + return 0; + + rc = vfs_getxattr_alloc(&init_user_ns, file_dentry(event_data->file), + XATTR_NAME_EVM, (char **)&xattr_data, 0, + GFP_NOFS); + if (rc <= 0) + return 0; + + if (xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG) { + kfree(xattr_data); + return 0; + } + + rc = ima_write_template_field_data((char *)xattr_data, rc, DATA_FMT_HEX, + field_data); + kfree(xattr_data); + return rc; +} diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h index 6b3b880637a0..f4b2a2056d1d 100644 --- a/security/integrity/ima/ima_template_lib.h +++ b/security/integrity/ima/ima_template_lib.h @@ -46,4 +46,6 @@ int ima_eventbuf_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventmodsig_init(struct ima_event_data *event_data, struct ima_field_data *field_data); +int ima_eventevmsig_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); #endif /* __LINUX_IMA_TEMPLATE_LIB_H */