From patchwork Fri Jun 28 02:19:33 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thiago Jung Bauermann X-Patchwork-Id: 11021139 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E1A571398 for ; Fri, 28 Jun 2019 02:21:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D46B928748 for ; Fri, 28 Jun 2019 02:21:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C7EE82874E; Fri, 28 Jun 2019 02:21:06 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 49F1A28748 for ; Fri, 28 Jun 2019 02:21:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726881AbfF1CUl (ORCPT ); Thu, 27 Jun 2019 22:20:41 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:21966 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726862AbfF1CUi (ORCPT ); Thu, 27 Jun 2019 22:20:38 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5S2GWG2098000 for ; Thu, 27 Jun 2019 22:20:38 -0400 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0a-001b2d01.pphosted.com with ESMTP id 2td9m2rx3b-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 27 Jun 2019 22:20:38 -0400 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 28 Jun 2019 03:20:32 +0100 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5S2KVww23790076 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 28 Jun 2019 02:20:31 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9327D112062; Fri, 28 Jun 2019 02:20:31 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F2D26112061; Fri, 28 Jun 2019 02:20:27 +0000 (GMT) Received: from morokweng.localdomain.com (unknown [9.85.218.134]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 28 Jun 2019 02:20:27 +0000 (GMT) From: Thiago Jung Bauermann To: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Mimi Zohar , Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , David Howells , David Woodhouse , Jessica Yu , Herbert Xu , "David S. Miller" , Jonathan Corbet , "AKASHI, Takahiro" , Thiago Jung Bauermann Subject: [PATCH v12 10/11] ima: Store the measurement again when appraising a modsig Date: Thu, 27 Jun 2019 23:19:33 -0300 X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190628021934.4260-1-bauerman@linux.ibm.com> References: <20190628021934.4260-1-bauerman@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 x-cbid: 19062802-2213-0000-0000-000003A60F53 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011344; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01224269; UDB=6.00644348; IPR=6.01005460; MB=3.00027497; MTD=3.00000008; XFM=3.00000015; UTC=2019-06-28 02:20:36 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19062802-2214-0000-0000-00005F061081 Message-Id: <20190628021934.4260-11-bauerman@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-27_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906280019 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP If the IMA template contains the "modsig" or "d-modsig" field, then the modsig should be added to the measurement list when the file is appraised. And that is what normally happens, but if a measurement rule caused a file containing a modsig to be measured before a different rule causes it to be appraised, the resulting measurement entry will not contain the modsig because it is only fetched during appraisal. When the appraisal rule triggers, it won't store a new measurement containing the modsig because the file was already measured. We need to detect that situation and store an additional measurement with the modsig. This is done by adding an IMA_MEASURE action flag if we read a modsig and the IMA template contains a modsig field. Suggested-by: Mimi Zohar Signed-off-by: Thiago Jung Bauermann --- security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_api.c | 19 +++++++++++++++---- security/integrity/ima/ima_main.c | 15 ++++++++++++--- security/integrity/ima/ima_template.c | 19 +++++++++++++++++++ 4 files changed, 47 insertions(+), 7 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 3293dd07b6c9..01a7a140bb4a 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -154,6 +154,7 @@ int template_desc_init_fields(const char *template_fmt, int *num_fields); struct ima_template_desc *ima_template_desc_current(void); struct ima_template_desc *lookup_template_desc(const char *name); +bool ima_template_has_modsig(const struct ima_template_desc *ima_template); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 9d1fe712a6cc..3a78373d835c 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -223,6 +223,14 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, char digest[IMA_MAX_DIGEST_SIZE]; } hash; + /* + * Always collect the modsig, because IMA might have already collected + * the file digest without collecting the modsig in a previous + * measurement rule. + */ + if (modsig) + ima_collect_modsig(modsig, buf, size); + if (iint->flags & IMA_COLLECTED) goto out; @@ -256,9 +264,6 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, memcpy(iint->ima_hash, &hash, length); iint->version = i_version; - if (modsig) - ima_collect_modsig(modsig, buf, size); - /* Possibly temporary failure due to type of read (eg. O_DIRECT) */ if (!result) iint->flags |= IMA_COLLECTED; @@ -308,7 +313,13 @@ void ima_store_measurement(struct integrity_iint_cache *iint, .modsig = modsig }; int violation = 0; - if (iint->measured_pcrs & (0x1 << pcr)) + /* + * We still need to store the measurement in the case of MODSIG because + * we only have its contents to put in the list at the time of + * appraisal, but a file measurement from earlier might already exist in + * the measurement list. + */ + if (iint->measured_pcrs & (0x1 << pcr) && !modsig) return; result = ima_alloc_init_template(&event_data, &entry, template_desc); diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 8b35a200e0cc..e855a4658425 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -311,9 +311,18 @@ static int process_measurement(struct file *file, const struct cred *cred, /* read 'security.ima' */ xattr_len = ima_read_xattr(file_dentry(file), &xattr_value); - /* Read the appended modsig if allowed by the policy. */ - if (iint->flags & IMA_MODSIG_ALLOWED) - ima_read_modsig(func, buf, size, &modsig); + /* + * Read the appended modsig if allowed by the policy, and allow + * an additional measurement list entry, if needed, based on the + * template format and whether the file was already measured. + */ + if (iint->flags & IMA_MODSIG_ALLOWED) { + rc = ima_read_modsig(func, buf, size, &modsig); + + if (!rc && ima_template_has_modsig(template_desc) && + iint->flags & IMA_MEASURED) + action |= IMA_MEASURE; + } } hash_algo = ima_get_hash_algo(xattr_value, xattr_len); diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index ac526b34973f..536205735456 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -62,6 +62,25 @@ static const struct ima_template_field supported_fields[] = { static struct ima_template_desc *ima_template; +/** + * ima_template_has_modsig - Check whether template has modsig-related fields. + * @ima_template: IMA template to check. + * + * Tells whether the given template has fields referencing a file's appended + * signature. + */ +bool ima_template_has_modsig(const struct ima_template_desc *ima_template) +{ + int i; + + for (i = 0; i < ima_template->num_fields; i++) + if (!strcmp(ima_template->fields[i]->field_id, "modsig") || + !strcmp(ima_template->fields[i]->field_id, "d-modsig")) + return true; + + return false; +} + static int __init ima_template_setup(char *str) { struct ima_template_desc *template_desc;