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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 1A1B7C433E7 for ; Fri, 16 Oct 2020 17:07:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A80BC20848 for ; Fri, 16 Oct 2020 17:07:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436550AbgJPRHu (ORCPT ); Fri, 16 Oct 2020 13:07:50 -0400 Received: from mga07.intel.com ([134.134.136.100]:20142 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436535AbgJPRHu (ORCPT ); Fri, 16 Oct 2020 13:07:50 -0400 IronPort-SDR: iD2+VMyOQtNcG+zoF6akva/K8sdnDrNkGnLu21ZZmR7jorMD6/KuLaaNfx2+WYaGIVd2CehUc7 YnToIqUN0DkQ== X-IronPort-AV: E=McAfee;i="6000,8403,9776"; a="230837698" X-IronPort-AV: E=Sophos;i="5.77,383,1596524400"; d="scan'208";a="230837698" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2020 10:07:49 -0700 IronPort-SDR: CKcKzCFr/TCW1QuctRed3/fLjyTHmwbnAsp/TbSr0AX+WyfJwSVFoHZtJ07OELERO5OjSl5Hek 8lNqQf7oS48Q== X-IronPort-AV: E=Sophos;i="5.77,383,1596524400"; d="scan'208";a="358154015" Received: from weetchel-mobl.amr.corp.intel.com (HELO [10.209.40.189]) ([10.209.40.189]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2020 10:07:48 -0700 Subject: Re: [PATCH v39 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE To: Jarkko Sakkinen , x86@kernel.org, linux-sgx@vger.kernel.org Cc: 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, bp@alien8.de, cedric.xing@intel.com, chenalexchen@google.com, conradparker@google.com, cyhanish@google.com, haitao.huang@intel.com, 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, mikko.ylinen@intel.com References: <20201003045059.665934-1-jarkko.sakkinen@linux.intel.com> <20201003045059.665934-13-jarkko.sakkinen@linux.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201003045059.665934-13-jarkko.sakkinen@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +static u32 sgx_calc_ssa_frame_size(u32 miscselect, u64 xfrm) > +{ > + u32 size_max = PAGE_SIZE; > + u32 size; > + int i; > + > + for (i = 2; i < 64; i++) { Should this be: for (i = XFEATURE_YMM; i < XFEATURE_MAX; i++) { Basically, does this need to be 64, or should it be limited to the kernel-known XFEATURES? Or, should this be looping through all the bits set in xfeatures_mask_user(). > + if (!((1 << i) & xfrm)) > + continue; > + > + size = SGX_SSA_GPRS_SIZE + sgx_xsave_size_tbl[i]; > + > + if (miscselect & SGX_MISC_EXINFO) > + size += SGX_SSA_MISC_EXINFO_SIZE; > + > + if (size > size_max) > + size_max = size; > + } > + > + return PFN_UP(size_max); > +} > + > +static int sgx_validate_secs(const struct sgx_secs *secs) > +{ What's the overall point of this function? Does it avoid a #GP from an instruction later? Does all of the 'secs' content come from userspace? > + 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))) > + return -EINVAL; > + > + if (!secs->ssa_frame_size) > + return -EINVAL; > + > + if (sgx_calc_ssa_frame_size(secs->miscselect, secs->xfrm) > secs->ssa_frame_size) > + 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; > +} I think it would be nice to at least have one comment per condition to explain what's going on there. > +static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) > +{ > + struct sgx_epc_page *secs_epc; > + struct sgx_pageinfo pginfo; > + struct sgx_secinfo secinfo; > + unsigned long encl_size; > + struct file *backing; > + long ret; > + > + if (sgx_validate_secs(secs)) { > + pr_debug("invalid SECS\n"); > + return -EINVAL; > + } > + > + /* The extra page goes to SECS. */ > + encl_size = secs->size + PAGE_SIZE; > + > + backing = shmem_file_setup("SGX backing", encl_size + (encl_size >> 5), > + VM_NORESERVE); What's the >>5 adjustment for? > + if (IS_ERR(backing)) > + return PTR_ERR(backing); > + > + encl->backing = backing; > + > + secs_epc = __sgx_alloc_epc_page(); > + if (IS_ERR(secs_epc)) { > + ret = PTR_ERR(secs_epc); > + goto err_out_backing; > + } > + > + encl->secs.epc_page = secs_epc; > + > + pginfo.addr = 0; > + pginfo.contents = (unsigned long)secs; > + pginfo.metadata = (unsigned long)&secinfo; > + pginfo.secs = 0; > + memset(&secinfo, 0, sizeof(secinfo)); > + > + ret = __ecreate((void *)&pginfo, sgx_get_epc_addr(secs_epc)); > + if (ret) { > + pr_debug("ECREATE returned %ld\n", ret); > + goto err_out; > + } > + > + if (secs->attributes & SGX_ATTR_DEBUG) > + atomic_or(SGX_ENCL_DEBUG, &encl->flags); > + > + encl->secs.encl = encl; > + encl->base = secs->base; > + encl->size = secs->size; > + encl->ssaframesize = secs->ssa_frame_size; > + > + /* > + * Set SGX_ENCL_CREATED only after the enclave is fully prepped. This > + * allows setting and checking enclave creation without having to take > + * encl->lock. > + */ > + atomic_or(SGX_ENCL_CREATED, &encl->flags); I'm wondering what the impact of setting this flag is. That's hard to figure out because the flag isn't documented. It's also unusual to have atomic_or() used like this. The normal set_bit()/clear_bit() that you can use on an unsigned long are actually implemented as atomics. I'm curious both why this needs to be atomics, *and* why the atomic_or() interface is being used. > + return 0; > + > +err_out: > + sgx_free_epc_page(encl->secs.epc_page); > + encl->secs.epc_page = NULL; > + > +err_out_backing: > + fput(encl->backing); > + encl->backing = NULL; > + > + return ret; > +} > + > +/** > + * sgx_ioc_enclave_create - handler for %SGX_IOC_ENCLAVE_CREATE > + * @encl: an enclave pointer > + * @arg: userspace pointer to a struct sgx_enclave_create instance > + * > + * Allocate kernel data structures for a new enclave and execute ECREATE after > + * checking that the provided data for SECS meets the expectations of ECREATE > + * for an uninitialized enclave and size of the address space does not surpass the > + * platform expectations. This validation is done by sgx_validate_secs(). > + * > + * Return: > + * 0 on success, > + * -errno otherwise > + */ > +static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg) > +{ > + struct sgx_enclave_create ecreate; > + struct page *secs_page; > + struct sgx_secs *secs; > + int ret; > + > + if (atomic_read(&encl->flags) & SGX_ENCL_CREATED) > + return -EINVAL; > + > + if (copy_from_user(&ecreate, arg, sizeof(ecreate))) > + return -EFAULT; > + > + secs_page = alloc_page(GFP_KERNEL); > + if (!secs_page) > + return -ENOMEM; > + > + secs = kmap(secs_page); GFP_KERNEL pages are in low memory and don't need to be kmap()'d. This can just be: secs = __get_free_page(GFP_KERNEL); if (copy_from_user(secs, (void __user *)ecreate.src,... and forget about the kmapping. You also need to change __free_pages() to free_pages(). The other alternative would be to just kmalloc() it. kmalloc() guarantees alignment in a stronger way than it used to. > + if (copy_from_user(secs, (void __user *)ecreate.src, sizeof(*secs))) { > + ret = -EFAULT; > + goto out; > + } > + > + ret = sgx_encl_create(encl, secs); > + > +out: > + kunmap(secs_page); > + __free_page(secs_page); > + return ret; > +} > + > +long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) > +{ > + struct sgx_encl *encl = filep->private_data; > + int ret, encl_flags; > + > + encl_flags = atomic_fetch_or(SGX_ENCL_IOCTL, &encl->flags); > + if (encl_flags & SGX_ENCL_IOCTL) > + return -EBUSY; Is the SGX_ENCL_IOCTL bit essentially just a lock to single-thread ioctl()s? Should we name it as such? > + if (encl_flags & SGX_ENCL_DEAD) { > + ret = -EFAULT; > + goto out; > + } > + > + switch (cmd) { > + case SGX_IOC_ENCLAVE_CREATE: > + ret = sgx_ioc_enclave_create(encl, (void __user *)arg); > + break; > + default: > + ret = -ENOIOCTLCMD; > + break; > + } > + > +out: > + atomic_andnot(SGX_ENCL_IOCTL, &encl->flags); > + return ret; > +} >