From patchwork Wed Jan 26 00:06:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mimi Zohar X-Patchwork-Id: 12724384 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 9EDD5C636CF for ; Wed, 26 Jan 2022 00:07:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235144AbiAZAH3 (ORCPT ); Tue, 25 Jan 2022 19:07:29 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:51280 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235179AbiAZAHZ (ORCPT ); Tue, 25 Jan 2022 19:07:25 -0500 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 20Q05qdx009016; 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=R7R5foVU/Im5PGylEF0xbOzDNnjoBVKtWXh3C22nZII=; b=JcdDF6gXce4CmD/mwjnuvkThl2DuV7vBHDUmNJuCSoauuEw25geb0Hwxij61ZLI+FbTC vTcbwvFj9Omg8MPQtq9mYl8Fui63HRnQZgKdM3x0ijVFk0iRo1WG7RPN3M1Ort9W0Yo5 xKkL/zk7+SbDyIr3RvYofpuSzcIsgq7YwTUEHxPeBwlJ36Y5dvkGzJoPx17NyK0hun2V V69+Zg+1egDqprlDVfjwQfbcBXI4aOuJgt7qf0cLk4D1aOdO87D5ng+DyGzmegeDFA5X 4Sm0dp7FWiVCmEhWzfVAcpLyGeFWrRebMSO9TfI598c4MhlwZXC27lGIktPgsAW0tnPw NQ== Received: from ppma01fra.de.ibm.com (46.49.7a9f.ip4.static.sl-reverse.com [159.122.73.70]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dttae950b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 Jan 2022 00:07:21 +0000 Received: from pps.filterd (ppma01fra.de.ibm.com [127.0.0.1]) by ppma01fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 20Q03V2P003644; Wed, 26 Jan 2022 00:07:19 GMT Received: from b06avi18626390.portsmouth.uk.ibm.com (b06avi18626390.portsmouth.uk.ibm.com [9.149.26.192]) by ppma01fra.de.ibm.com with ESMTP id 3dr9j9gr2f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 Jan 2022 00:07:19 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 20PNvfd032440794 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 25 Jan 2022 23:57:42 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C5ECC4C040; Wed, 26 Jan 2022 00:07:15 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CDD144C044; Wed, 26 Jan 2022 00:07:14 +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 00:07:14 +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 7/8] ima: support fs-verity file digest based version 3 signatures Date: Tue, 25 Jan 2022 19:06:57 -0500 Message-Id: <20220126000658.138345-8-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: YAdKyRFYUFj1WVUzXswdT9B1ttZES040 X-Proofpoint-ORIG-GUID: YAdKyRFYUFj1WVUzXswdT9B1ttZES040 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 clxscore=1015 mlxscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 suspectscore=0 mlxlogscore=999 adultscore=0 phishscore=0 impostorscore=0 spamscore=0 priorityscore=1501 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 Instead of calculating a file hash and verifying the signature stored in the security.ima xattr against the calculated file hash, verify fs-verity's signature (version 3). To differentiate between a regular file hash and an fs-verity file digest based signature stored as security.ima xattr, define a new signature type named IMA_VERITY_DIGSIG. Update the 'ima-sig' template field to display the new fs-verity signature type as well. For example: appraise func=BPRM_CHECK digest_type=hash|verity Signed-off-by: Mimi Zohar --- Documentation/ABI/testing/ima_policy | 10 +++++ Documentation/security/IMA-templates.rst | 4 +- security/integrity/ima/ima_appraise.c | 49 ++++++++++++++++++++++- security/integrity/ima/ima_template_lib.c | 3 +- security/integrity/integrity.h | 5 ++- 5 files changed, 65 insertions(+), 6 deletions(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 444bb7ccbe03..fadf90dde289 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -151,6 +151,16 @@ Description: appraise func=SETXATTR_CHECK appraise_algos=sha256,sha384,sha512 + Example of measure and appraise rules allowing fs-verity + signed digests on a particular filesystem identified by + it's fsuuid: + + measure func=BPRM_CHECK digest_type=hash|verity \ + fsuuid=... template=ima-sig + appraise func=BPRM_CHECK digest_type=hash|verity \ + fsuuid=... + + Example of measure rule allowing fs-verity's digests on a particular filesystem with indication of type of digest. diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index 5e31513e8ec4..390936810ebc 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -71,8 +71,8 @@ descriptors by adding their identifier to the format string - 'd-modsig': the digest of the event without the appended modsig; - 'd-type': the type of file digest (e.g. hash, verity[1]); - 'n-ng': the name of the event, without size limitations; - - 'sig': the file signature, or the EVM portable signature if the file - signature is not found; + - 'sig': the file signature, based on either the file's/fsverity's digest[1], + 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; diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 7bc180bd808e..68376c56feff 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -13,7 +13,9 @@ #include #include #include +#include #include +#include #include "ima.h" @@ -183,13 +185,18 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value, return ima_hash_algo; switch (xattr_value->type) { + case IMA_VERITY_DIGSIG: + sig = (typeof(sig))xattr_value; + if (sig->version != 3 || xattr_len <= sizeof(*sig) || + sig->hash_algo >= HASH_ALGO__LAST) + return ima_hash_algo; + return sig->hash_algo; case EVM_IMA_XATTR_DIGSIG: sig = (typeof(sig))xattr_value; if (sig->version != 2 || xattr_len <= sizeof(*sig) || sig->hash_algo >= HASH_ALGO__LAST) return ima_hash_algo; return sig->hash_algo; - break; case IMA_XATTR_DIGEST_NG: /* first byte contains algorithm id */ ret = xattr_value->data[0]; @@ -235,15 +242,22 @@ int ima_read_xattr(struct dentry *dentry, * IMA signature version 3 disambiguates the data that is signed by * indirectly signing the hash of the ima_file_id structure data. * + * Signing the ima_file_id struct is currently only supported for + * IMA_VERITY_DIGSIG type xattrs. + * * 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}; + struct ima_file_id file_id = { + .hash_type = IMA_VERITY_DIGSIG, .hash_algorithm = algo}; uint unused = HASH_MAX_DIGESTSIZE - hash_digest_size[algo]; + if (type != IMA_VERITY_DIGSIG) + return -EINVAL; + memcpy(file_id.hash, digest, hash_digest_size[algo]); hash->algo = algo; @@ -264,6 +278,7 @@ 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 ima_max_digest_data hash; struct signature_v2_hdr *sig; int rc = -EINVAL, hash_start = 0; @@ -332,6 +347,36 @@ static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, } else { *status = INTEGRITY_PASS; } + break; + case IMA_VERITY_DIGSIG: + set_bit(IMA_DIGSIG, &iint->atomic_flags); + + sig = (typeof(sig))xattr_value; + if (sig->version != 3) { + *cause = "invalid-verity-version"; + *status = INTEGRITY_FAIL; + break; + } + + rc = calc_file_id_hash(IMA_VERITY_DIGSIG, iint->ima_hash->algo, + iint->ima_hash->digest, &hash); + if (rc) { + *cause = "verity-hashing-error"; + *status = INTEGRITY_FAIL; + break; + } + + rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, + (const char *)xattr_value, + xattr_len, hash.digest, + hash.length); + if (rc) { + *cause = "invalid-verity-signature"; + *status = INTEGRITY_FAIL; + } else { + *status = INTEGRITY_PASS; + } + break; default: *status = INTEGRITY_UNKNOWN; diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index 44e57d7e5fed..0d4bbb4da59a 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -499,7 +499,8 @@ 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)) + if (!xattr_value || + !(xattr_value->type & (EVM_IMA_XATTR_DIGSIG | IMA_VERITY_DIGSIG))) return ima_eventevmsig_init(event_data, field_data); return ima_write_template_field_data(xattr_value, event_data->xattr_len, diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index ed4966d943e9..5b1aa8b7d61c 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -80,6 +80,7 @@ enum evm_ima_xattr_type { EVM_IMA_XATTR_DIGSIG, IMA_XATTR_DIGEST_NG, EVM_XATTR_PORTABLE_DIGSIG, + IMA_VERITY_DIGSIG, IMA_XATTR_LAST }; @@ -154,7 +155,9 @@ struct signature_v2_hdr { /* * IMA signature version 3 disambiguates the data that is signed, by - * indirectly signing the hash of the ima_file_id structure data. + * indirectly signing the hash of the ima_file_id structure data, + * containing either the fsverity_descriptor struct digest or, in the + * future, the regular IMA file hash. * * (The hash of the ima_file_id structure is only of the portion used.) */