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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 BE341C43463 for ; Mon, 21 Sep 2020 12:30:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85D0420739 for ; Mon, 21 Sep 2020 12:30:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726475AbgIUMa6 (ORCPT ); Mon, 21 Sep 2020 08:30:58 -0400 Received: from mga12.intel.com ([192.55.52.136]:41366 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726456AbgIUMa6 (ORCPT ); Mon, 21 Sep 2020 08:30:58 -0400 IronPort-SDR: /+MrVm/4+jCAslV3p6f8KtAdT731YblHCCeHM3eXVUz4zgaBXlABgsjuiW7TBXcGP0CCOdaYv4 XTfuRsHR3e6g== X-IronPort-AV: E=McAfee;i="6000,8403,9750"; a="139861733" X-IronPort-AV: E=Sophos;i="5.77,286,1596524400"; d="scan'208";a="139861733" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2020 05:28:33 -0700 IronPort-SDR: uuvW00qyo7NJoJvm1ajmNpK1USV0vARV+F/Rif7giE1iBFv73ds22JNjbzJYKfh86utnfC6OIG ucwlxwAaqJxQ== X-IronPort-AV: E=Sophos;i="5.77,286,1596524400"; d="scan'208";a="454024277" Received: from clairemo-mobl.ger.corp.intel.com (HELO localhost) ([10.252.43.50]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2020 05:28:25 -0700 Date: Mon, 21 Sep 2020 15:28:23 +0300 From: Jarkko Sakkinen To: Borislav Petkov Cc: x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, Jethro Beekman , Haitao Huang , Chunyang Hui , Jordan Hand , Nathaniel McCallum , Seth Moore , Darren Kenny , Sean Christopherson , Suresh Siddha , akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com, asapek@google.com, cedric.xing@intel.com, chenalexchen@google.com, conradparker@google.com, cyhanish@google.com, dave.hansen@intel.com, haitao.huang@intel.com, josh@joshtriplett.org, kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com, ludloff@google.com, luto@kernel.org, nhorman@redhat.com, puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de, yaozhangx@google.com Subject: Re: [PATCH v38 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Message-ID: <20200921122823.GE6038@linux.intel.com> References: <20200915112842.897265-1-jarkko.sakkinen@linux.intel.com> <20200915112842.897265-13-jarkko.sakkinen@linux.intel.com> <20200921100356.GB5901@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200921100356.GB5901@zn.tnic> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Mon, Sep 21, 2020 at 12:03:56PM +0200, Borislav Petkov wrote: > On Tue, Sep 15, 2020 at 02:28:30PM +0300, Jarkko Sakkinen wrote: > > +static int sgx_validate_secs(const struct sgx_secs *secs) > > +{ > > + u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ? > > + sgx_encl_size_max_64 : sgx_encl_size_max_32; > > + > > + if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size)) > > + return -EINVAL; > > + > > + if (secs->base & (secs->size - 1)) > > + return -EINVAL; > > + > > + if (secs->miscselect & sgx_misc_reserved_mask || > > + secs->attributes & sgx_attributes_reserved_mask || > > + secs->xfrm & sgx_xfrm_reserved_mask) > > + return -EINVAL; > > + > > + if (secs->size > max_size) > > + return -EINVAL; > > + > > + if (!(secs->xfrm & XFEATURE_MASK_FP) || > > + !(secs->xfrm & XFEATURE_MASK_SSE) || > > + (((secs->xfrm >> XFEATURE_BNDREGS) & 1) != > > + ((secs->xfrm >> XFEATURE_BNDCSR) & 1))) > > Let that last line stick out so that you have each statement on a single line. > > > + return -EINVAL; > > + > > + if (!secs->ssa_frame_size) > > + return -EINVAL; > > + > > + if (sgx_calc_ssa_frame_size(secs->miscselect, secs->xfrm) > > > + secs->ssa_frame_size) > > Let that stick out. > > > + return -EINVAL; > > + > > + if (memchr_inv(secs->reserved1, 0, sizeof(secs->reserved1)) || > > + memchr_inv(secs->reserved2, 0, sizeof(secs->reserved2)) || > > + memchr_inv(secs->reserved3, 0, sizeof(secs->reserved3)) || > > + memchr_inv(secs->reserved4, 0, sizeof(secs->reserved4))) > > + return -EINVAL; > > + > > + return 0; > > +} > > + > > +static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) > > +{ > > + unsigned long encl_size = secs->size + PAGE_SIZE; > > You're still using secs->size before validation. I know, we will return > early if sgx_validate_secs() fails but pls move that addition after the > validation call. Is this appropriate: /* The extra page in swap space goes to SECS. */ encl_size = secs->size + PAGE_SIZE; backing = shmem_file_setup("SGX backing", encl_size + (encl_size >> 5), VM_NORESERVE); if (IS_ERR(backing)) { ret = PTR_ERR(backing); goto err_out_shrink; } > ... > > > +/** > > + * sgx_ioc_enclave_create - handler for %SGX_IOC_ENCLAVE_CREATE > > + * @filep: open file to /dev/sgx > > Dammit, how many times do I have to type this comment here?! > > "That's > > @encl: enclave pointer > > or so." > > There's no filep - there is an encl! I'm not actually sure what has happened. As you can easily grep, the rename is done in five other sites. I also see a similar problem in EINIT, which I will fix. git grep "enclave pointer" arch/x86/kernel/cpu/sgx/ | wc -l 5 > > + * @arg: userspace pointer to a struct sgx_enclave_create instance > > + * > > + * Allocate kernel data structures for a new enclave and execute ECREATE after > > + * verifying the correctness of the provided SECS. > > ... which is done in sgx_validate_secs()." > > Yes, spell it out, otherwise one has to wonder where that validation is > happening in the function *below* because the comment is over it - not > over sgx_validate_secs(). > > And yes, you need to spell stuff like that out because this SGX crap is > complex and it better be properly documented! I agree with this but I also think it would make sense to rephrase "verifying the correctness of the provided SECS" with something more informative. I would rephrase as: "... after checking that the provided data for SECS meets the expectations of ENCLS[ECREATE] for an unitialized enclave and size of the address space does not surpass the platform expectations. This validation is executed by sgx_validate_secs()." Is this sufficient for you, or do you have further suggestions? > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette /Jarkko