Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161400Ab1FBM0v (ORCPT ); Thu, 2 Jun 2011 08:26:51 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:56345 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161176Ab1FBMZo (ORCPT ); Thu, 2 Jun 2011 08:25:44 -0400 From: Mimi Zohar To: linux-security-module@vger.kernel.org Cc: Dmitry Kasatkin , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, James Morris , David Safford , Andrew Morton , Greg KH , Dmitry Kasatkin , Mimi Zohar Subject: [PATCH v6 17/20] evm: evm_verify_hmac must not return INTEGRITY_UNKNOWN Date: Thu, 2 Jun 2011 08:23:40 -0400 Message-Id: <1307017423-15093-18-git-send-email-zohar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.4 In-Reply-To: <1307017423-15093-1-git-send-email-zohar@linux.vnet.ibm.com> References: <1307017423-15093-1-git-send-email-zohar@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2302 Lines: 65 From: Dmitry Kasatkin If EVM is not supported or enabled, evm_verify_hmac() returns INTEGRITY_UNKNOWN, which ima_appraise_measurement() ignores and sets the appraisal status based solely on the security.ima verification. evm_verify_hmac() also returns INTEGRITY_UNKNOWN for other failures, such as temporary failures like -ENOMEM, resulting in possible attack vectors. This patch changes the default return code for temporary/unexpected failures, like -ENOMEM, from INTEGRITY_UNKNOWN to INTEGRITY_FAIL, making evm_verify_hmac() fail safe. As a result, failures need to be re-evaluated in order to catch both temporary errors, such as the -ENOMEM, as well as errors that have been resolved in fix mode. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_main.c | 11 +++++------ 1 files changed, 5 insertions(+), 6 deletions(-) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 14fbd38..9abe75b 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -56,13 +56,15 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, struct evm_ima_xattr_data xattr_data; int rc; - if (iint->hmac_status != INTEGRITY_UNKNOWN) + if (iint->hmac_status == INTEGRITY_PASS) return iint->hmac_status; + /* if status is not PASS, try to check again - against -ENOMEM */ + rc = evm_calc_hmac(dentry, xattr_name, xattr_value, xattr_value_len, xattr_data.digest); if (rc < 0) - return INTEGRITY_UNKNOWN; + goto err_out; xattr_data.type = EVM_XATTR_HMAC; rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, (u8 *)&xattr_data, @@ -77,11 +79,8 @@ err_out: case -ENODATA: /* file not labelled */ iint->hmac_status = INTEGRITY_NOLABEL; break; - case -EINVAL: - iint->hmac_status = INTEGRITY_FAIL; - break; default: - iint->hmac_status = INTEGRITY_UNKNOWN; + iint->hmac_status = INTEGRITY_FAIL; } return iint->hmac_status; } -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/