Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76D25C433EF for ; Tue, 7 Dec 2021 16:11:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239520AbhLGQPB (ORCPT ); Tue, 7 Dec 2021 11:15:01 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:46005 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234629AbhLGQO7 (ORCPT ); Tue, 7 Dec 2021 11:14:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1638893488; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=q14zqMaClWT6A6pjsZ9r/kKotJ2Nm5bDx7Gi7LWBtyI=; b=LYD0u2jtFpVoW+a55U9gyxzCudDqIEnVga7fWi3DNlvEGxJ0OH6LY7WIMhwfsGj9fczZM0 meZqb2mqJmqfO3+wN5WUb0iLuNWhF8kcapgjRdXU0Vuw2zIMBr7THCOeLU1hzN95UtNMF3 vcqQXGGsIlMegUsTjHck3gth7EKpAAg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-505-BdX3DYBpO-KAjRBFDzmJRA-1; Tue, 07 Dec 2021 11:11:25 -0500 X-MC-Unique: BdX3DYBpO-KAjRBFDzmJRA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 106B31006AA2; Tue, 7 Dec 2021 16:11:21 +0000 (UTC) Received: from rhtmp (unknown [10.39.192.202]) by smtp.corp.redhat.com (Postfix) with ESMTP id D0F241972E; Tue, 7 Dec 2021 16:11:14 +0000 (UTC) Date: Tue, 7 Dec 2021 17:11:12 +0100 From: Philipp Rudo To: Michal Suchanek Cc: keyrings@vger.kernel.org, kexec@lists.infradead.org, Mimi Zohar , Nayna , Rob Herring , linux-s390@vger.kernel.org, Vasily Gorbik , Lakshmi Ramasubramanian , Heiko Carstens , Jessica Yu , linux-kernel@vger.kernel.org, David Howells , Christian Borntraeger , Luis Chamberlain , Paul Mackerras , Hari Bathini , Alexander Gordeev , linuxppc-dev@lists.ozlabs.org, Frank van der Linden , Thiago Jung Bauermann , Daniel Axtens , buendgen@de.ibm.com, Michael Ellerman , Benjamin Herrenschmidt , Christian Borntraeger , Herbert Xu , "David S. Miller" , Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , Sven Schnelle , Baoquan He , linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v2 4/6] module: strip the signature marker in the verification function. Message-ID: <20211207171112.03850036@rhtmp> In-Reply-To: <0f9bbbc4800d5329485b6bdabbbe1ef3b2169b02.1637862358.git.msuchanek@suse.de> References: <0f9bbbc4800d5329485b6bdabbbe1ef3b2169b02.1637862358.git.msuchanek@suse.de> Organization: Red Hat inc. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Michal, On Thu, 25 Nov 2021 19:02:42 +0100 Michal Suchanek wrote: > It is stripped by each caller separately. > > Signed-off-by: Michal Suchanek > --- > arch/powerpc/kexec/elf_64.c | 9 --------- > arch/s390/kernel/machine_kexec_file.c | 9 --------- > kernel/module.c | 7 +------ > kernel/module_signing.c | 12 ++++++++++-- kernel/module_signing.c is only compiled with MODULE_SIG enabled but KEXEC_SIG only selects MODULE_SIG_FORMAT. In the unlikely case that KEXEC_SIG is enabled but MODULE_SIG isn't this causes a build breakage. So you need to update KEXEC_SIG to select MODULE_SIG instead of MODULE_SIG_FORMAT for s390 and ppc. Thanks Philipp > 4 files changed, 11 insertions(+), 26 deletions(-) > > diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c > index 266cb26d3ca0..63634c95265d 100644 > --- a/arch/powerpc/kexec/elf_64.c > +++ b/arch/powerpc/kexec/elf_64.c > @@ -156,15 +156,6 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, > int elf64_verify_sig(const char *kernel, unsigned long length) > { > size_t kernel_len = length; > - const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1; > - > - if (marker_len > kernel_len) > - return -EKEYREJECTED; > - > - if (memcmp(kernel + kernel_len - marker_len, MODULE_SIG_STRING, > - marker_len)) > - return -EKEYREJECTED; > - kernel_len -= marker_len; > > return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING, > "kexec_file"); > diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c > index 432797249db3..c4632c1a1b59 100644 > --- a/arch/s390/kernel/machine_kexec_file.c > +++ b/arch/s390/kernel/machine_kexec_file.c > @@ -27,20 +27,11 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { > int s390_verify_sig(const char *kernel, unsigned long length) > { > size_t kernel_len = length; > - const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1; > > /* Skip signature verification when not secure IPLed. */ > if (!ipl_secure_flag) > return 0; > > - if (marker_len > kernel_len) > - return -EKEYREJECTED; > - > - if (memcmp(kernel + kernel_len - marker_len, MODULE_SIG_STRING, > - marker_len)) > - return -EKEYREJECTED; > - kernel_len -= marker_len; > - > return verify_appended_signature(kernel, &kernel_len, VERIFY_USE_PLATFORM_KEYRING, > "kexec_file"); > } > diff --git a/kernel/module.c b/kernel/module.c > index 8481933dfa92..d91ca0f93a40 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2882,7 +2882,6 @@ static inline void kmemleak_load_module(const struct module *mod, > static int module_sig_check(struct load_info *info, int flags) > { > int err = -ENODATA; > - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > const char *reason; > const void *mod = info->hdr; > > @@ -2890,11 +2889,7 @@ static int module_sig_check(struct load_info *info, int flags) > * Require flags == 0, as a module with version information > * removed is no longer the module that was signed > */ > - if (flags == 0 && > - info->len > markerlen && > - memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) { > - /* We truncate the module to discard the signature */ > - info->len -= markerlen; > + if (flags == 0) { > err = verify_appended_signature(mod, &info->len, > VERIFY_USE_SECONDARY_KEYRING, "module"); > if (!err) { > diff --git a/kernel/module_signing.c b/kernel/module_signing.c > index f492e410564d..4c28cb55275f 100644 > --- a/kernel/module_signing.c > +++ b/kernel/module_signing.c > @@ -15,8 +15,7 @@ > #include "module-internal.h" > > /** > - * verify_appended_signature - Verify the signature on a module with the > - * signature marker stripped. > + * verify_appended_signature - Verify the signature on a module > * @data: The data to be verified > * @len: Size of @data. > * @trusted_keys: Keyring to use for verification > @@ -25,12 +24,21 @@ > int verify_appended_signature(const void *data, size_t *len, > struct key *trusted_keys, const char *what) > { > + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > struct module_signature ms; > size_t sig_len, modlen = *len; > int ret; > > pr_devel("==>%s(,%zu)\n", __func__, modlen); > > + if (markerlen > modlen) > + return -ENODATA; > + > + if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING, > + markerlen)) > + return -ENODATA; > + modlen -= markerlen; > + > if (modlen <= sizeof(ms)) > return -EBADMSG; >