From patchwork Thu Jun 18 16:01:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 11612767 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6166192A for ; Thu, 18 Jun 2020 16:04:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 532E9208B8 for ; Thu, 18 Jun 2020 16:04:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731810AbgFRQE0 (ORCPT ); Thu, 18 Jun 2020 12:04:26 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2333 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731753AbgFRQEZ (ORCPT ); Thu, 18 Jun 2020 12:04:25 -0400 Received: from lhreml734-chm.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id BE2AC619E696DA4357FB; Thu, 18 Jun 2020 17:04:23 +0100 (IST) Received: from fraeml714-chm.china.huawei.com (10.206.15.33) by lhreml734-chm.china.huawei.com (10.201.108.85) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Thu, 18 Jun 2020 17:04:23 +0100 Received: from roberto-HP-EliteDesk-800-G2-DM-65W.huawei.com (10.204.65.160) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1913.5; Thu, 18 Jun 2020 18:04:22 +0200 From: Roberto Sassu To: , CC: , , , Roberto Sassu , Subject: [PATCH 04/11] evm: Check size of security.evm before using it Date: Thu, 18 Jun 2020 18:01:26 +0200 Message-ID: <20200618160133.937-4-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200618160133.937-1-roberto.sassu@huawei.com> References: <20200618160133.937-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.65.160] X-ClientProxiedBy: lhreml704-chm.china.huawei.com (10.201.108.53) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org This patch checks the size for the EVM_IMA_XATTR_DIGSIG and EVM_XATTR_PORTABLE_DIGSIG types to ensure that the algorithm is read from the buffer returned by vfs_getxattr_alloc(). Cc: stable@vger.kernel.org # 4.19.x Fixes: 5feeb61183dde ("evm: Allow non-SHA1 digital signatures") Signed-off-by: Roberto Sassu Reviewed-by: Mimi Zohar --- security/integrity/evm/evm_main.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 744c105b48d1..4e9f5e8b21d5 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -181,6 +181,12 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, break; case EVM_IMA_XATTR_DIGSIG: case EVM_XATTR_PORTABLE_DIGSIG: + /* accept xattr with non-empty signature field */ + if (xattr_len <= sizeof(struct signature_v2_hdr)) { + evm_status = INTEGRITY_FAIL; + goto out; + } + hdr = (struct signature_v2_hdr *)xattr_data; digest.hdr.algo = hdr->hash_algo; rc = evm_calc_hash(dentry, xattr_name, xattr_value,