From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:44254 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752158AbeCNUUr (ORCPT ); Wed, 14 Mar 2018 16:20:47 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w2EKJrIO018794 for ; Wed, 14 Mar 2018 16:20:47 -0400 Received: from e19.ny.us.ibm.com (e19.ny.us.ibm.com [129.33.205.209]) by mx0b-001b2d01.pphosted.com with ESMTP id 2gq67xkpj8-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Wed, 14 Mar 2018 16:20:47 -0400 Received: from localhost by e19.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 14 Mar 2018 16:20:45 -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 In-Reply-To: <20180314202020.3794-1-bauerman@linux.vnet.ibm.com> References: <20180314202020.3794-1-bauerman@linux.vnet.ibm.com> Message-Id: <20180314202020.3794-4-bauerman@linux.vnet.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: 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 {