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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 27 Jan 2020 21:31:41 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 00RLVevM30605340 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 27 Jan 2020 21:31:40 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B427C11C052; Mon, 27 Jan 2020 21:31:40 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 239DE11C04A; Mon, 27 Jan 2020 21:31:40 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.185.238]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 27 Jan 2020 21:31:40 +0000 (GMT) Subject: Re: [PATCH 1/2] ima: use the IMA configured hash algo to calculate the boot aggregate From: Mimi Zohar To: Jerry Snitselaar Cc: linux-integrity@vger.kernel.org, James Bottomley , linux-kernel@vger.kernel.org Date: Mon, 27 Jan 2020 16:31:39 -0500 In-Reply-To: <20200127204941.2ewman4y5nzvkjqe@cantor> References: <1580140919-6127-1-git-send-email-zohar@linux.ibm.com> <20200127204941.2ewman4y5nzvkjqe@cantor> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 (3.20.5-1.fc24) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 20012721-0016-0000-0000-000002E13180 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20012721-0017-0000-0000-00003343EFBE Message-Id: <1580160699.5088.64.camel@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-01-27_07:2020-01-24,2020-01-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 bulkscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 lowpriorityscore=0 mlxscore=0 clxscore=1015 phishscore=0 impostorscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1911200001 definitions=main-2001270168 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-01-27 at 13:49 -0700, Jerry Snitselaar wrote: > On Mon Jan 27 20, Mimi Zohar wrote: > >The boot aggregate is a cumulative SHA1 hash over TPM registers 0 - 7. > >NIST has depreciated the usage of SHA1 in most instances. Instead of > >continuing to use SHA1 to calculate the boot_aggregate, use the > >configured IMA default hash algorithm. > > > >Although the IMA measurement list boot_aggregate template data contains > >the hash algorithm followed by the digest, allowing verifiers (e.g. > >attesttaion servers) to calculate and verify the boot_aggregate, the > >verifiers might not have the knowledge of what constitutes a good value > >based on a different hash algorithm. > > > >Signed-off-by: Mimi Zohar > >--- > > security/integrity/ima/ima_init.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > >diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c > >index 195cb4079b2b..b1b334fe0db5 100644 > >--- a/security/integrity/ima/ima_init.c > >+++ b/security/integrity/ima/ima_init.c > >@@ -27,7 +27,7 @@ struct tpm_chip *ima_tpm_chip; > > /* Add the boot aggregate to the IMA measurement list and extend > > * the PCR register. > > * > >- * Calculate the boot aggregate, a SHA1 over tpm registers 0-7, > >+ * Calculate the boot aggregate, a hash over tpm registers 0-7, > > * assuming a TPM chip exists, and zeroes if the TPM chip does not > > * exist. Add the boot aggregate measurement to the measurement > > * list and extend the PCR register. > >@@ -51,14 +51,14 @@ static int __init ima_add_boot_aggregate(void) > > int violation = 0; > > struct { > > struct ima_digest_data hdr; > >- char digest[TPM_DIGEST_SIZE]; > >+ char digest[TPM_MAX_DIGEST_SIZE]; > > } hash; > > > > memset(iint, 0, sizeof(*iint)); > > memset(&hash, 0, sizeof(hash)); > > iint->ima_hash = &hash.hdr; > >- iint->ima_hash->algo = HASH_ALGO_SHA1; > >- iint->ima_hash->length = SHA1_DIGEST_SIZE; > >+ iint->ima_hash->algo = ima_hash_algo; > >+ iint->ima_hash->length = hash_digest_size[ima_hash_algo]; > > > > if (ima_tpm_chip) { > > result = ima_calc_boot_aggregate(&hash.hdr); > >-- > >2.7.5 > > > > Tested the patches on the Dell and no longer spits out the error messages on boot. > /sys/kernel/security/ima/ascii_runtime_measurements shows the boot aggregate. > > Is there something else I should look at to verify it is functioning properly? The original LTP ima_boot_aggregate.c test needed to be updated to support TPM 2.0 before this change.  For TPM 2.0, the PCRs are not exported.  With this change, the kernel could be reading PCRs from a TPM bank other than SHA1 and calculating the boot_aggregate based on a different hash algorithm as well.  I'm not sure how a remote verifier would know which TPM bank was read, when calculating the boot- aggregate. At the moment, the only test would be to make sure that the LTP test still works for TPM 1.2 properly. Mimi