From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752183AbeCNUUt (ORCPT ); Wed, 14 Mar 2018 16:20:49 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50112 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752081AbeCNUUr (ORCPT ); Wed, 14 Mar 2018 16:20:47 -0400 From: Thiago Jung Bauermann To: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, James Morris , "Serge E. Hallyn" , Mimi Zohar , Dmitry Kasatkin , Thiago Jung Bauermann Subject: [PATCH 3/4] ima: Improvements in ima_appraise_measurement() Date: Wed, 14 Mar 2018 17:20:19 -0300 X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180314202020.3794-1-bauerman@linux.vnet.ibm.com> References: <20180314202020.3794-1-bauerman@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18031420-0056-0000-0000-0000042D8CC5 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008674; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000254; SDB=6.01003063; UDB=6.00510447; IPR=6.00782394; MB=3.00020035; MTD=3.00000008; XFM=3.00000015; UTC=2018-03-14 20:20:44 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18031420-0057-0000-0000-0000086F8DCB Message-Id: <20180314202020.3794-4-bauerman@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-14_11:,, 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 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803140218 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mimi Zohar Replace nested ifs in the EVM xattr verification logic with a switch statement, making the code easier to understand. Also, add comments to the if statements in the out section and constify the cause variable. Signed-off-by: Mimi Zohar Signed-off-by: Thiago Jung Bauermann --- security/integrity/ima/ima_appraise.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 0c5f94b7b9c3..dd10ecbdce45 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -215,7 +215,7 @@ int ima_appraise_measurement(enum ima_hooks func, int xattr_len, int opened) { static const char op[] = "appraise_data"; - char *cause = "unknown"; + const char *cause = "unknown"; struct dentry *dentry = file_dentry(file); struct inode *inode = d_backing_inode(dentry); enum integrity_status status = INTEGRITY_UNKNOWN; @@ -241,16 +241,20 @@ int ima_appraise_measurement(enum ima_hooks func, } status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint); - if ((status != INTEGRITY_PASS) && - (status != INTEGRITY_PASS_IMMUTABLE) && - (status != INTEGRITY_UNKNOWN)) { - if ((status == INTEGRITY_NOLABEL) - || (status == INTEGRITY_NOXATTRS)) - cause = "missing-HMAC"; - else if (status == INTEGRITY_FAIL) - cause = "invalid-HMAC"; + switch (status) { + case INTEGRITY_PASS: + case INTEGRITY_PASS_IMMUTABLE: + case INTEGRITY_UNKNOWN: + break; + case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ + case INTEGRITY_NOLABEL: /* No security.evm xattr. */ + cause = "missing-HMAC"; + goto out; + case INTEGRITY_FAIL: /* Invalid HMAC/signature. */ + cause = "invalid-HMAC"; goto out; } + switch (xattr_value->type) { case IMA_XATTR_DIGEST_NG: /* first byte contains algorithm id */ @@ -316,17 +320,20 @@ int ima_appraise_measurement(enum ima_hooks func, integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, op, cause, rc, 0); } else if (status != INTEGRITY_PASS) { + /* Fix mode, but don't replace file signatures. */ if ((ima_appraise & IMA_APPRAISE_FIX) && (!xattr_value || xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { if (!ima_fix_xattr(dentry, iint)) status = INTEGRITY_PASS; - } else if ((inode->i_size == 0) && - (iint->flags & IMA_NEW_FILE) && - (xattr_value && - xattr_value->type == EVM_IMA_XATTR_DIGSIG)) { + } + + /* Permit new files with file signatures, but without data. */ + if (inode->i_size == 0 && iint->flags & IMA_NEW_FILE && + xattr_value && xattr_value->type == EVM_IMA_XATTR_DIGSIG) { status = INTEGRITY_PASS; } + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, op, cause, rc, 0); } else {