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 X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1CFBC433E6 for ; Thu, 11 Mar 2021 05:56:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B3E464F9F for ; Thu, 11 Mar 2021 05:56:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229702AbhCKF4X (ORCPT ); Thu, 11 Mar 2021 00:56:23 -0500 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:29126 "EHLO out4436.biz.mail.alibaba.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229637AbhCKFzx (ORCPT ); Thu, 11 Mar 2021 00:55:53 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=zhang.jia@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0URPRUq5_1615442150; Received: from ali-6c96cfd98fb5.local(mailfrom:zhang.jia@linux.alibaba.com fp:SMTPD_---0URPRUq5_1615442150) by smtp.aliyun-inc.com(127.0.0.1); Thu, 11 Mar 2021 13:55:51 +0800 Subject: Re: [PATCH] selftests/sgx: fix EINIT failure dueto SGX_INVALID_SIGNATURE To: Jarkko Sakkinen Cc: Andy Lutomirski , Tianjia Zhang , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Sean Christopherson , Shuah Khan , X86 ML , linux-sgx@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , LKML References: <20210301051836.30738-1-tianjia.zhang@linux.alibaba.com> <3bcdcf04-4bed-ed95-84b6-790675f18240@linux.alibaba.com> <1f5c2375-39e2-65a8-3ad3-8dc43422f568@linux.alibaba.com> <20ef1254-007d-04ce-8df5-5122ffd4d8d3@linux.alibaba.com> From: Jia Zhang Message-ID: <1c1c5b03-883d-8d37-aed1-cdad230d87e4@linux.alibaba.com> Date: Thu, 11 Mar 2021 13:55:50 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On 2021/3/11 上午11:42, Jarkko Sakkinen wrote: > On Thu, Mar 11, 2021 at 10:47:50AM +0800, Jia Zhang wrote: >> >> >> On 2021/3/11 上午5:39, Jarkko Sakkinen wrote: >>> On Wed, Mar 10, 2021 at 08:44:44PM +0800, Jia Zhang wrote: >>>> >>>> >>>> On 2021/3/2 下午9:47, Jarkko Sakkinen wrote: >>>>> On Mon, Mar 01, 2021 at 09:54:37PM -0800, Andy Lutomirski wrote: >>>>>> On Mon, Mar 1, 2021 at 9:06 PM Tianjia Zhang >>>>>> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 3/1/21 5:54 PM, Jarkko Sakkinen wrote: >>>>>>>> On Mon, Mar 01, 2021 at 01:18:36PM +0800, Tianjia Zhang wrote: >>>>>>>>> q2 is not always 384-byte length. Sometimes it only has 383-byte. >>>>>>>> >>>>>>>> What does determine this? >>>>>>>> >>>>>>>>> In this case, the valid portion of q2 is reordered reversely for >>>>>>>>> little endian order, and the remaining portion is filled with zero. >>>>>>>> >>>>>>>> I'm presuming that you want to say "In this case, q2 needs to be reversed because...". >>>>>>>> >>>>>>>> I'm lacking these details: >>>>>>>> >>>>>>>> 1. Why the length of Q2 can vary? >>>>>>>> 2. Why reversing the bytes is the correct measure to counter-measure >>>>>>>> this variation? >>>>>>>> >>>>>>>> /Jarkko >>>>>>>> >>>>>>> >>>>>>> When use openssl to generate a key instead of using the built-in >>>>>>> sign_key.pem, there is a probability that will encounter this problem. >>>>>>> >>>>>>> Here is a problematic key I encountered. The calculated q1 and q2 of >>>>>>> this key are both 383 bytes, If the length is not processed, the >>>>>>> hardware signature will fail. >>>>>> >>>>>> Presumably the issue is that some keys have parameters that have >>>>>> enough leading 0 bits to be effectively shorter. The openssl API >>>>>> (and, sadly, a bunch of the ASN.1 stuff) treats these parameters as >>>>>> variable-size integers. >>>>> >>>>> But the test uses a static key. It used to generate a key on fly but >>>> >>>> IMO even though the test code, it comes from the linux kernel, meaning >>>> that its quality has a certain guarantee and it is a good reference, so >>>> the test code still needs to ensure its correctness. >>> >>> Hmm... what is working incorrectly then? >> >> In current implementation, it is working well, after all the static key >> can derive the full 384-byte length of q1 and q2. As mentioned above, if >> someone refers to the design of signing tool from selftest code, it is >> quite possible that the actual implementation will use dynamical or >> external signing key deriving shorter q1 and/or q2 in length. > > A self-test needs is not meant to be generic to be directly used in 3rd > party code. With the current key there is not issue => there is no issue. Alright. So what we should do is to add a comment to explain why the selfcode does something wrong and essentially it is intended. Jia > >> >> Going back the technical background, I'm not a crypto expert, so I >> choose to check the code, doc and make experiment. >> >> Accorindg to intel sdm vol3 37.14: >> >> ``` >> SIGSTRUCT includes four 3072-bit integers (MODULUS, SIGNATURE, Q1, Q2). >> Each such integer is represented as a byte strings of length 384, with >> the most significant byte at the position “offset + 383”, and the least >> significant byte at position “offset”. >> >> ... >> >> The 3072-bit integers Q1 and Q2 are defined by: >> q1 = floor(Signature^2 / Modulus); >> q2 = floor((Signature^3 - q1 * Signature * Modulus) / Modulus); >> ``` >> >> and the implementation of singing tool from Intel SGX SDK >> (https://github.com/intel/linux-sgx/blob/master/sdk/sign_tool/SignTool/sign_tool.cpp#L381 >> ), the most significant byte shuld be at the position “offset + >> q1/q2_actuall_len”, and the padding portion should be filled with zero, >> and don't involve the order reverse, but the selftest code always does. >> This is the root cause of SGX_INVALID_SIGNATURE. >> >> Just simplily enforce size_q1 and size_q2 to SE_KEY_SIZE, and generate >> randome siging key with `openssl genrsa -3 -out signing_key.pem 3072`, >> the SGX_INVALID_SIGNATURE error will appear up quickly. >> >> Jia >> >>> >>> /Jarkko >>> >> > > /Jarkko >