From patchwork Tue Feb 8 01:41:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 12738041 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B0C3C35274 for ; Tue, 8 Feb 2022 01:48:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243313AbiBHBsE (ORCPT ); Mon, 7 Feb 2022 20:48:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34784 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344968AbiBHBmb (ORCPT ); Mon, 7 Feb 2022 20:42:31 -0500 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EB3B1C043181; Mon, 7 Feb 2022 17:42:30 -0800 (PST) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 217MZQnW025115; Tue, 8 Feb 2022 01:42:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=GXju7EEK3Cz6A2AIspO4Y3DS6ZtSGgC1yD1hXV9wP50=; b=NbKbcUQ5vd4JUlDQhxANqIv8GnzI931ma9ZYSKlK/vHnP1mSVQUThTiYaYfen/1yvFiN 4Ljwa/u+KqYSEtuFeMLzFFZ4QytLAGLUMrOYOHDA6WkUPf6bdRKKw/bKhn5t6SPXCHhe aCl5qsMFVe09XPMldID6bTfRXbxPJhlvIf443uXrGGkagMpqruNIaTopqu+GmpEAJplM b8thCBu/9Ce1Uc2LdCOoxfpKq8BWgg9iWETUGyk/k45tdhnIPF2zOhe9bgznpgIwfLob JhcidavOxw3hlFy+Ujx3k51RYUgBy7jUrAv0Cei0F+wrmiPhHpot146ocau6oG03nPhy +Q== Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 3e22tr4jvn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 08 Feb 2022 01:42:29 +0000 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 2181WgVK028927; Tue, 8 Feb 2022 01:42:27 GMT Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by ppma04ams.nl.ibm.com with ESMTP id 3e1gv91k7h-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 08 Feb 2022 01:42:26 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 2181gK9841877888 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 8 Feb 2022 01:42:20 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 39ABDA4055; Tue, 8 Feb 2022 01:42:20 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5D9CAA405B; Tue, 8 Feb 2022 01:42:19 +0000 (GMT) Received: from li-f45666cc-3089-11b2-a85c-c57d1a57929f.ibm.com.com (unknown [9.65.90.153]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 8 Feb 2022 01:42:19 +0000 (GMT) From: Mimi Zohar To: linux-integrity@vger.kernel.org Cc: Mimi Zohar , Eric Biggers , Stefan Berger , linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 6/8] ima: define signature version 3 Date: Mon, 7 Feb 2022 20:41:38 -0500 Message-Id: <20220208014140.483447-7-zohar@linux.ibm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220208014140.483447-1-zohar@linux.ibm.com> References: <20220208014140.483447-1-zohar@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: A3IvOQR_YHaoE0XrROrvJPCAZwZVaUDv X-Proofpoint-GUID: A3IvOQR_YHaoE0XrROrvJPCAZwZVaUDv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-02-07_07,2022-02-07_02,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 mlxlogscore=999 impostorscore=0 phishscore=0 suspectscore=0 malwarescore=0 mlxscore=0 spamscore=0 priorityscore=1501 clxscore=1015 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202080006 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org To disambiguate the signed data stored in the 'security.ima' xattr, define signature version 3 as the hash of the ima_file_id structure. Signed-off-by: Mimi Zohar --- security/integrity/digsig.c | 3 ++- security/integrity/ima/ima_appraise.c | 36 +++++++++++++++++++++++++++ security/integrity/integrity.h | 20 +++++++++++++-- 3 files changed, 56 insertions(+), 3 deletions(-) diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c index 3b06a01bd0fd..fd8f77d92a62 100644 --- a/security/integrity/digsig.c +++ b/security/integrity/digsig.c @@ -74,7 +74,8 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, /* v1 API expect signature without xattr type */ return digsig_verify(keyring, sig + 1, siglen - 1, digest, digestlen); - case 2: + case 2: /* regular file data hash based sginature */ + case 3: /* struct ima_file_id data base signature */ return asymmetric_verify(keyring, sig, siglen, digest, digestlen); } diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 17232bbfb9f9..7bc180bd808e 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -225,6 +225,34 @@ int ima_read_xattr(struct dentry *dentry, return ret; } +/* + * calc_file_id_hash - calculate the hash of the ima_file_id struct data + * @type: xattr type [enum evm_ima_xattr_type] + * @algo: hash algorithm [enum hash_algo] + * @digest: pointer to the digest to be hashed + * @hash: (out) pointer to the hash + * + * IMA signature version 3 disambiguates the data that is signed by + * indirectly signing the hash of the ima_file_id structure data. + * + * Return 0 on success, error code otherwise. + */ +static int calc_file_id_hash(enum evm_ima_xattr_type type, + enum hash_algo algo, const u8 *digest, + struct ima_max_digest_data *hash) +{ + struct ima_file_id file_id = {.hash_algorithm = algo}; + uint unused = HASH_MAX_DIGESTSIZE - hash_digest_size[algo]; + + memcpy(file_id.hash, digest, hash_digest_size[algo]); + + hash->algo = algo; + hash->length = hash_digest_size[algo]; + + return ima_calc_buffer_hash(&file_id, sizeof(file_id) - unused, + (struct ima_digest_data *)hash); +} + /* * xattr_verify - verify xattr digest or signature * @@ -236,6 +264,7 @@ static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, struct evm_ima_xattr_data *xattr_value, int xattr_len, enum integrity_status *status, const char **cause) { + struct signature_v2_hdr *sig; int rc = -EINVAL, hash_start = 0; switch (xattr_value->type) { @@ -274,6 +303,13 @@ static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, break; case EVM_IMA_XATTR_DIGSIG: set_bit(IMA_DIGSIG, &iint->atomic_flags); + + sig = (typeof(sig))xattr_value; + if (sig->version != 2) { + *cause = "invalid-signature-version"; + *status = INTEGRITY_FAIL; + break; + } rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, (const char *)xattr_value, xattr_len, diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index cbc41d4288ed..f59f83527c0c 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -94,7 +94,7 @@ struct evm_xattr { u8 digest[SHA1_DIGEST_SIZE]; } __packed; -#define IMA_MAX_DIGEST_SIZE 64 +#define IMA_MAX_DIGEST_SIZE HASH_MAX_DIGESTSIZE struct ima_digest_data { u8 algo; @@ -137,7 +137,11 @@ struct ima_max_digest_data { } __packed; /* - * signature format v2 - for using with asymmetric keys + * signature header format v2 - for using with asymmetric keys + * + * signature format: + * version 2: regular file data hash based signature + * version 3: struct ima_file_id data based signature */ struct signature_v2_hdr { uint8_t type; /* xattr type */ @@ -148,6 +152,18 @@ struct signature_v2_hdr { uint8_t sig[]; /* signature payload */ } __packed; +/* + * IMA signature version 3 disambiguates the data that is signed, by + * indirectly signing the hash of the ima_file_id structure data. + * + * (The hash of the ima_file_id structure is only of the portion used.) + */ +struct ima_file_id { + __u8 hash_type; /* xattr type [enum evm_ima_xattr_type] */ + __u8 hash_algorithm; /* Digest algorithm [enum hash_algo] */ + __u8 hash[HASH_MAX_DIGESTSIZE]; +} __packed; + /* integrity data associated with an inode */ struct integrity_iint_cache { struct rb_node rb_node; /* rooted in integrity_iint_tree */