From mboxrd@z Thu Jan 1 00:00:00 1970 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 8826DC05027 for ; Fri, 17 Feb 2023 21:11:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229563AbjBQVLQ (ORCPT ); Fri, 17 Feb 2023 16:11:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbjBQVLQ (ORCPT ); Fri, 17 Feb 2023 16:11:16 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90AC55DE35 for ; Fri, 17 Feb 2023 13:11:15 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2CEB9B82DAD for ; Fri, 17 Feb 2023 21:11:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1880AC433EF; Fri, 17 Feb 2023 21:11:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676668272; bh=M89NsS7YL8O/JdOW3Xa33cOkhkNkUMhH+6zfZ1uQJCo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cPpZ/Xlvi3BZUBbHp6K4JpjNT/ixS6xgIEhlwk91lZZqBW2dKcWFMZNlsRF9ItnXd LWK7v82mbdV7ptIJjQJCaGUM4e0GRP7OanIP/gtP4/BmE4An2IgxyzDwzemvb6Uykk JsKvvcm+/4A3Q9ysVAqC7/zxjP6y/JOPwbTwI12ARKnUt0r/UBiSe3K3S2odLqWJ0y xMtuihSEfhIKec3H34oOl1vc2ahkavJJr+7nABO5JiNmy4hqlmFRsoBwF9Kgz2UrV3 9/Sn70HSBQfdFh3FSzef4J4XC0Gue3ddC4T+9KYWlWqvCOTfVElpve5xLyEdn23eGm tt8d3o6kNRSWA== Date: Fri, 17 Feb 2023 23:11:07 +0200 From: Jarkko Sakkinen To: Robbie Harwood Cc: keyrings@vger.kernel.org, David Howells Subject: Re: [PATCH v1 1/2] verify_pefile: relax wrapper length check Message-ID: References: <20230217201435.39784-1-rharwood@redhat.com> <20230217201435.39784-2-rharwood@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230217201435.39784-2-rharwood@redhat.com> Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org On Fri, Feb 17, 2023 at 03:14:34PM -0500, Robbie Harwood wrote: > The PE Format Specification (section "The Attribute Certificate Table > (Image Only)") states that `dwLength` is to be rounded up to 8-byte > alignment when used for traversal. Therefore, the field is not required > to be an 8-byte multiple in the first place. > > Accordingly, pesign has not performed this alignment since version > 0.110. This causes kexec failure on pesign'd binaries with "PEFILE: > Signature wrapper len wrong". Update the comment and relax the check. > > See-also: https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#the-attribute-certificate-table-image-only > See-also: https://github.com/rhboot/pesign > Signed-off-by: Robbie Harwood OK, makes sense but what does relaxing this bring up to the table? I.e. I do get the argument but do not see the motivation. > --- > crypto/asymmetric_keys/verify_pefile.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c > index 7553ab18db89..fe1bb374239d 100644 > --- a/crypto/asymmetric_keys/verify_pefile.c > +++ b/crypto/asymmetric_keys/verify_pefile.c > @@ -135,11 +135,15 @@ static int pefile_strip_sig_wrapper(const void *pebuf, > pr_debug("sig wrapper = { %x, %x, %x }\n", > wrapper.length, wrapper.revision, wrapper.cert_type); > > - /* Both pesign and sbsign round up the length of certificate table > - * (in optional header data directories) to 8 byte alignment. > + /* sbsign rounds up the length of certificate table (in optional > + * header data directories) to 8 byte alignment. However, the PE > + * specification states that while entries are 8-byte aligned, this is > + * not included in their length, and as a result, pesign has not > + * rounded up since 0.110. > */ > - if (round_up(wrapper.length, 8) != ctx->sig_len) { > - pr_debug("Signature wrapper len wrong\n"); > + if (wrapper.length > ctx->sig_len) { > + pr_debug("Signature wrapper bigger than sig len (%x > %x)\n", > + ctx->sig_len, wrapper.length); > return -ELIBBAD; > } > if (wrapper.revision != WIN_CERT_REVISION_2_0) { > -- > 2.39.1 > BR, Jarkko