From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755849AbeEANtB (ORCPT ); Tue, 1 May 2018 09:49:01 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:46400 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755751AbeEANs5 (ORCPT ); Tue, 1 May 2018 09:48:57 -0400 From: Mimi Zohar To: linux-integrity@vger.kernel.org Cc: Hans de Goede , Ard Biesheuvel , Peter Jones , Mimi Zohar , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, David Howells , "Luis R . Rodriguez" , "Luis R . Rodriguez" , Kees Cook , "Serge E . Hallyn" , Stephen Boyd Subject: [RFC PATCH 6/6] ima: prevent loading firmware into a pre-allocated buffer Date: Tue, 1 May 2018 09:48:23 -0400 X-Mailer: git-send-email 2.7.5 In-Reply-To: <1525182503-13849-1-git-send-email-zohar@linux.vnet.ibm.com> References: <1525182503-13849-1-git-send-email-zohar@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18050113-0040-0000-0000-00000434CDA3 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18050113-0041-0000-0000-00002638E68E Message-Id: <1525182503-13849-7-git-send-email-zohar@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-01_07:,, 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-1805010138 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Question: can the device access the pre-allocated buffer at any time? By allowing devices to request firmware be loaded directly into a pre-allocated buffer, will this allow the device access to the firmware before the kernel has verified the firmware signature? Is it dependent on the type of buffer allocated (eg. DMA)? For example, qcom_mdt_load() -> qcom_scm_pas_init_image() -> dma_alloc_coherent(). With an IMA policy requiring signed firmware, this patch would prevent loading firmware into a pre-allocated buffer. Signed-off-by: Mimi Zohar Cc: Luis R. Rodriguez Cc: David Howells Cc: Kees Cook Cc: Serge E. Hallyn Cc: Stephen Boyd --- security/integrity/ima/ima_main.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index eb9c273ab81d..3098131f77c4 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -454,6 +454,15 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id) return 0; } + if (read_id == READING_FIRMWARE_PREALLOC_BUFFER) { + if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && + (ima_appraise & IMA_APPRAISE_ENFORCE)) { + pr_err("Prevent device from accessing firmware prior to verifying the firmware signature.\n"); + return -EACCES; + } + return 0; + } + if (read_id == READING_FIRMWARE_FALLBACK) { if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && (ima_appraise & IMA_APPRAISE_ENFORCE)) { -- 2.7.5