From patchwork Thu Dec 13 02:08:54 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thiago Jung Bauermann X-Patchwork-Id: 10727543 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 174E216B1 for ; Thu, 13 Dec 2018 02:11:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0795C2B994 for ; Thu, 13 Dec 2018 02:11:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 04ECB2B9EB; Thu, 13 Dec 2018 02:11:05 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3F2902B994 for ; Thu, 13 Dec 2018 02:11:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726618AbeLMCLD (ORCPT ); Wed, 12 Dec 2018 21:11:03 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:46900 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726445AbeLMCLC (ORCPT ); Wed, 12 Dec 2018 21:11:02 -0500 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wBD23g1W041854 for ; Wed, 12 Dec 2018 21:11:01 -0500 Received: from e36.co.us.ibm.com (e36.co.us.ibm.com [32.97.110.154]) by mx0a-001b2d01.pphosted.com with ESMTP id 2pbdgcaa6c-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 12 Dec 2018 21:11:01 -0500 Received: from localhost by e36.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 13 Dec 2018 02:10:54 -0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp08028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wBD2Arjx19792050 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 13 Dec 2018 02:10:53 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D9351C6057; Thu, 13 Dec 2018 02:10:52 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C5104C605B; Thu, 13 Dec 2018 02:10:48 +0000 (GMT) Received: from morokweng.localdomain.com (unknown [9.80.227.60]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 13 Dec 2018 02:10:48 +0000 (GMT) From: Thiago Jung Bauermann To: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Mimi Zohar , Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , David Howells , David Woodhouse , Jessica Yu , Herbert Xu , "David S. Miller" , Jonathan Corbet , "AKASHI, Takahiro" , Thiago Jung Bauermann Subject: [PATCH v9 01/14] MODSIGN: Export module signature definitions Date: Thu, 13 Dec 2018 00:08:54 -0200 X-Mailer: git-send-email 2.17.2 In-Reply-To: <20181213020907.13601-1-bauerman@linux.ibm.com> References: <20181213020907.13601-1-bauerman@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18121302-0020-0000-0000-00000E98FB52 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010217; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01130951; UDB=6.00587714; IPR=6.00911085; MB=3.00024674; MTD=3.00000008; XFM=3.00000015; UTC=2018-12-13 02:10:58 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18121302-0021-0000-0000-000064081C09 Message-Id: <20181213020907.13601-2-bauerman@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-12-12_04:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812130017 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP IMA will use the module_signature format for append signatures, so export the relevant definitions and factor out the code which verifies that the appended signature trailer is valid. Also, create a CONFIG_MODULE_SIG_FORMAT option so that IMA can select it and be able to use mod_check_sig() without having to depend on CONFIG_MODULE_SIG. Signed-off-by: Thiago Jung Bauermann Reviewed-by: Mimi Zohar Cc: Jessica Yu --- include/linux/module.h | 3 -- include/linux/module_signature.h | 47 ++++++++++++++++++ init/Kconfig | 6 ++- kernel/Makefile | 2 +- kernel/module.c | 1 + kernel/module_signing.c | 82 ++++++++++++++------------------ 6 files changed, 91 insertions(+), 50 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index fce6b4335e36..e49bbc5c66ef 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -25,9 +25,6 @@ #include #include -/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ -#define MODULE_SIG_STRING "~Module signature appended~\n" - /* Not Yet Implemented */ #define MODULE_SUPPORTED_DEVICE(name) diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h new file mode 100644 index 000000000000..a3a629fc8c13 --- /dev/null +++ b/include/linux/module_signature.h @@ -0,0 +1,47 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Module signature handling. + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#ifndef _LINUX_MODULE_SIGNATURE_H +#define _LINUX_MODULE_SIGNATURE_H + +/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ +#define MODULE_SIG_STRING "~Module signature appended~\n" + +enum pkey_id_type { + PKEY_ID_PGP, /* OpenPGP generated key ID */ + PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ + PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ +}; + +/* + * Module signature information block. + * + * The constituents of the signature section are, in order: + * + * - Signer's name + * - Key identifier + * - Signature data + * - Information block + */ +struct module_signature { + u8 algo; /* Public-key crypto algorithm [0] */ + u8 hash; /* Digest algorithm [0] */ + u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ + u8 signer_len; /* Length of signer's name [0] */ + u8 key_id_len; /* Length of key identifier [0] */ + u8 __pad[3]; + __be32 sig_len; /* Length of signature data */ +}; + +struct load_info; + +int mod_check_sig(const struct module_signature *ms, size_t file_len, + const char *name); +int mod_verify_sig(const void *mod, struct load_info *info); + +#endif /* _LINUX_MODULE_SIGNATURE_H */ diff --git a/init/Kconfig b/init/Kconfig index a4112e95724a..cd31593525ee 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1864,7 +1864,7 @@ config MODULE_SRCVERSION_ALL config MODULE_SIG bool "Module signature verification" depends on MODULES - select SYSTEM_DATA_VERIFICATION + select MODULE_SIG_FORMAT help Check modules for valid signatures upon load: the signature is simply appended to the module. For more information see @@ -1879,6 +1879,10 @@ config MODULE_SIG debuginfo strip done by some packagers (such as rpmbuild) and inclusion into an initramfs that wants the module size reduced. +config MODULE_SIG_FORMAT + def_bool n + select SYSTEM_DATA_VERIFICATION + config MODULE_SIG_FORCE bool "Require modules to be validly signed" depends on MODULE_SIG diff --git a/kernel/Makefile b/kernel/Makefile index 7343b3a9bff0..e56842571348 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -59,7 +59,7 @@ obj-y += up.o endif obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += module.o -obj-$(CONFIG_MODULE_SIG) += module_signing.o +obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signing.o obj-$(CONFIG_KALLSYMS) += kallsyms.o obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o obj-$(CONFIG_CRASH_CORE) += crash_core.o diff --git a/kernel/module.c b/kernel/module.c index 49a405891587..205c9eefd08d 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include diff --git a/kernel/module_signing.c b/kernel/module_signing.c index f2075ce8e4b3..5624e59981b4 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -11,36 +11,44 @@ #include #include +#include #include #include #include #include "module-internal.h" -enum pkey_id_type { - PKEY_ID_PGP, /* OpenPGP generated key ID */ - PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ - PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ -}; - -/* - * Module signature information block. +/** + * mod_check_sig - check that the given signature is sane * - * The constituents of the signature section are, in order: - * - * - Signer's name - * - Key identifier - * - Signature data - * - Information block + * @ms: Signature to check. + * @file_len: Size of the file to which @ms is appended. */ -struct module_signature { - u8 algo; /* Public-key crypto algorithm [0] */ - u8 hash; /* Digest algorithm [0] */ - u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ - u8 signer_len; /* Length of signer's name [0] */ - u8 key_id_len; /* Length of key identifier [0] */ - u8 __pad[3]; - __be32 sig_len; /* Length of signature data */ -}; +int mod_check_sig(const struct module_signature *ms, size_t file_len, + const char *name) +{ + if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms)) + return -EBADMSG; + + if (ms->id_type != PKEY_ID_PKCS7) { + pr_err("%s: Module is not signed with expected PKCS#7 message\n", + name); + return -ENOPKG; + } + + if (ms->algo != 0 || + ms->hash != 0 || + ms->signer_len != 0 || + ms->key_id_len != 0 || + ms->__pad[0] != 0 || + ms->__pad[1] != 0 || + ms->__pad[2] != 0) { + pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n", + name); + return -EBADMSG; + } + + return 0; +} /* * Verify the signature on a module. @@ -49,6 +57,7 @@ int mod_verify_sig(const void *mod, struct load_info *info) { struct module_signature ms; size_t sig_len, modlen = info->len; + int ret; pr_devel("==>%s(,%zu)\n", __func__, modlen); @@ -56,32 +65,15 @@ int mod_verify_sig(const void *mod, struct load_info *info) return -EBADMSG; memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms)); - modlen -= sizeof(ms); + + ret = mod_check_sig(&ms, modlen, info->name); + if (ret) + return ret; sig_len = be32_to_cpu(ms.sig_len); - if (sig_len >= modlen) - return -EBADMSG; - modlen -= sig_len; + modlen -= sig_len + sizeof(ms); info->len = modlen; - if (ms.id_type != PKEY_ID_PKCS7) { - pr_err("%s: Module is not signed with expected PKCS#7 message\n", - info->name); - return -ENOPKG; - } - - if (ms.algo != 0 || - ms.hash != 0 || - ms.signer_len != 0 || - ms.key_id_len != 0 || - ms.__pad[0] != 0 || - ms.__pad[1] != 0 || - ms.__pad[2] != 0) { - pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n", - info->name); - return -EBADMSG; - } - return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len, NULL, VERIFYING_MODULE_SIGNATURE, NULL, NULL);