From patchwork Wed Jan 26 00:06:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 12724383 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 2F13AC636C8 for ; Wed, 26 Jan 2022 00:07:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235171AbiAZAH2 (ORCPT ); Tue, 25 Jan 2022 19:07:28 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:7122 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S235177AbiAZAHZ (ORCPT ); Tue, 25 Jan 2022 19:07:25 -0500 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 20PNklpW015377; Wed, 26 Jan 2022 00:07:22 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=B+NdcKPHFPZZgDawrfKFq6M17fFn4ErIyjO6KR4BsVw=; b=sFXUo5JSMF0ynqhEZKQNFfp1idwR86vjG5aPiZQfVZkiNzb8XhVCurfYARrcPwUILNcR iMZkPnac0w46I0tTV3I4HRXA6rMyP4P0udMGeE7UtyPUK7NSkKm2ZSjpuO4fh44EGEQf MymviRrSxglHJRCZKfffS6RnAz616RD7cowaw8mlGGBhp82gJVwQcS11O4W7XLgpxKn6 XzP+eQfsIZUwzz8KmsMv66RvIgEaMujX9CvLd8OJvaXRya211gXbSjsqr6gMDftMOLe4 u2Af2A6BuJIDbsS7+pt0GagwwBzVujcs66vk0G9Kqoq/74tv4vwZfaIo6nR/F848xCZ9 CA== Received: from ppma06fra.de.ibm.com (48.49.7a9f.ip4.static.sl-reverse.com [159.122.73.72]) by mx0b-001b2d01.pphosted.com with ESMTP id 3dtu66r9bt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 Jan 2022 00:07:22 +0000 Received: from pps.filterd (ppma06fra.de.ibm.com [127.0.0.1]) by ppma06fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 20Q07K3G004940; Wed, 26 Jan 2022 00:07:20 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma06fra.de.ibm.com with ESMTP id 3dr96jgv3c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 Jan 2022 00:07:20 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 20Q07E7m43516414 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jan 2022 00:07:14 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4EBDB4C04E; Wed, 26 Jan 2022 00:07:14 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 753064C044; Wed, 26 Jan 2022 00:07:13 +0000 (GMT) Received: from li-f45666cc-3089-11b2-a85c-c57d1a57929f.ibm.com.com (unknown [9.65.78.94]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 26 Jan 2022 00:07:13 +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 v3 6/8] ima: define signature version 3 Date: Tue, 25 Jan 2022 19:06:56 -0500 Message-Id: <20220126000658.138345-7-zohar@linux.ibm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220126000658.138345-1-zohar@linux.ibm.com> References: <20220126000658.138345-1-zohar@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 3efVHz3QjSMeL0EfX-5n5j4L1nClqyUr X-Proofpoint-ORIG-GUID: 3efVHz3QjSMeL0EfX-5n5j4L1nClqyUr 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=2022-01-25_06,2022-01-25_02,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 priorityscore=1501 mlxscore=0 bulkscore=0 impostorscore=0 spamscore=0 mlxlogscore=999 phishscore=0 suspectscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201250145 Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org To disambiguate the signed data, instead of directly signing the file data hash, signature version 3 signs 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 a996d4fa7be3..ed4966d943e9 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 */