From patchwork Wed May 5 11:33:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12239801 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 34CEDC433ED for ; Wed, 5 May 2021 11:35:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 005ED6109E for ; Wed, 5 May 2021 11:35:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233002AbhEELgI (ORCPT ); Wed, 5 May 2021 07:36:08 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3013 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232993AbhEELgH (ORCPT ); Wed, 5 May 2021 07:36:07 -0400 Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4FZvVh60b6z6wkQf; Wed, 5 May 2021 19:24:12 +0800 (CST) Received: from roberto-ThinkStation-P620.huawei.com (10.204.62.217) 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 15.1.2176.2; Wed, 5 May 2021 13:35:09 +0200 From: Roberto Sassu To: , CC: , , , Roberto Sassu Subject: [PATCH v6 10/11] ima: Introduce template field evmsig and write to field sig as fallback Date: Wed, 5 May 2021 13:33:28 +0200 Message-ID: <20210505113329.1410943-6-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210505112935.1410679-1-roberto.sassu@huawei.com> References: <20210505112935.1410679-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.62.217] X-ClientProxiedBy: lhreml752-chm.china.huawei.com (10.201.108.202) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: 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 4e081e650047..7a60848c04a5 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 */