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Wed, 26 Aug 2020 13:46:24 +0000 (UTC) IronPort-SDR: 1D/RsY/NQz2qcbSk5g+fm78kb3epFzKIDW6CSse+ApSCUhhDJ5NIpp+ui2QqvF2+Z251YBgxQi tiT5l//V+Vgg== X-IronPort-AV: E=McAfee;i="6000,8403,9724"; a="241105390" X-IronPort-AV: E=Sophos;i="5.76,355,1592895600"; d="scan'208";a="241105390" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2020 06:46:23 -0700 IronPort-SDR: SrajiWtghCwhFesXaobYHfK2TrmzSgDEqOKZWwYhaEIkr/popCwDt/A7yuvPhcUc7InUiOPDzb 4X/tDtDDyYQw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,355,1592895600"; d="scan'208";a="444051308" Received: from kempfs-mobl1.ger.corp.intel.com (HELO localhost) ([10.252.55.157]) by orsmga004.jf.intel.com with ESMTP; 26 Aug 2020 06:46:07 -0700 Date: Wed, 26 Aug 2020 16:46:06 +0300 From: Jarkko Sakkinen To: Borislav Petkov Cc: x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Jethro Beekman , Haitao Huang , Chunyang Hui , Jordan Hand , Nathaniel McCallum , Seth Moore , Sean Christopherson , Suresh Siddha , 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 v36 11/24] x86/sgx: Add SGX enclave driver Message-ID: <20200826134606.GC6532@linux.intel.com> References: <20200716135303.276442-1-jarkko.sakkinen@linux.intel.com> <20200716135303.276442-12-jarkko.sakkinen@linux.intel.com> <20200825164412.GF12107@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200825164412.GF12107@zn.tnic> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo X-Rspamd-Queue-Id: 6A2061004A09B X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 25, 2020 at 06:44:12PM +0200, Borislav Petkov wrote: > On Thu, Jul 16, 2020 at 04:52:50PM +0300, Jarkko Sakkinen wrote: > > Just minor things below - I'm not even going to pretend I fully > understand what's going on but FWICT, it looks non-threateningly ok to > me. > > > diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c > > new file mode 100644 > > index 000000000000..b52520407f5b > > --- /dev/null > > +++ b/arch/x86/kernel/cpu/sgx/driver.c > > @@ -0,0 +1,177 @@ > > +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) > > +// Copyright(c) 2016-18 Intel Corporation. > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include "driver.h" > > +#include "encl.h" > > + > > +MODULE_DESCRIPTION("Intel SGX Enclave Driver"); > > +MODULE_AUTHOR("Jarkko Sakkinen "); > > +MODULE_LICENSE("Dual BSD/GPL"); > > That boilerplate stuff usually goes to the end of the file. These all are cruft from the times when we still had a kernel module. I.e. I'll just remove them. > > ... > > > +static struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, > > + unsigned long addr) > > +{ > > + struct sgx_encl_page *entry; > > + unsigned int flags; > > + > > + /* If process was forked, VMA is still there but vm_private_data is set > > + * to NULL. > > + */ > > + if (!encl) > > + return ERR_PTR(-EFAULT); > > + > > + flags = atomic_read(&encl->flags); > > + > > ^ Superfluous newline. > > > + if ((flags & SGX_ENCL_DEAD) || !(flags & SGX_ENCL_INITIALIZED)) > > + return ERR_PTR(-EFAULT); > > + > > + entry = xa_load(&encl->page_array, PFN_DOWN(addr)); > > + if (!entry) > > + return ERR_PTR(-EFAULT); > > + > > + /* Page is already resident in the EPC. */ > > + if (entry->epc_page) > > + return entry; > > + > > + return ERR_PTR(-EFAULT); > > +} > > + > > +static void sgx_mmu_notifier_release(struct mmu_notifier *mn, > > + struct mm_struct *mm) > > +{ > > + struct sgx_encl_mm *encl_mm = > > + container_of(mn, struct sgx_encl_mm, mmu_notifier); > > Just let it stick out. > > > + struct sgx_encl_mm *tmp = NULL; > > + > > + /* > > + * The enclave itself can remove encl_mm. Note, objects can't be moved > > + * off an RCU protected list, but deletion is ok. > > + */ > > + spin_lock(&encl_mm->encl->mm_lock); > > + list_for_each_entry(tmp, &encl_mm->encl->mm_list, list) { > > + if (tmp == encl_mm) { > > + list_del_rcu(&encl_mm->list); > > + break; > > + } > > + } > > + spin_unlock(&encl_mm->encl->mm_lock); > > + > > + if (tmp == encl_mm) { > > + synchronize_srcu(&encl_mm->encl->srcu); > > + mmu_notifier_put(mn); > > + } > > +} > > + > > +static void sgx_mmu_notifier_free(struct mmu_notifier *mn) > > +{ > > + struct sgx_encl_mm *encl_mm = > > + container_of(mn, struct sgx_encl_mm, mmu_notifier); > > Ditto. > > ... > > > +/** > > + * sgx_encl_may_map() - Check if a requested VMA mapping is allowed > > + * @encl: an enclave > > + * @start: lower bound of the address range, inclusive > > + * @end: upper bound of the address range, exclusive > > + * @vm_prot_bits: requested protections of the address range > > + * > > + * Iterate through the enclave pages contained within [@start, @end) to verify > > + * the permissions requested by @vm_prot_bits do not exceed that of any enclave > > + * page to be mapped. > > + * > > + * Return: > > + * 0 on success, > > + * -EACCES if VMA permissions exceed enclave page permissions > > + */ > > +int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start, > > + unsigned long end, unsigned long vm_flags) > > +{ > > + unsigned long vm_prot_bits = vm_flags & (VM_READ | VM_WRITE | VM_EXEC); > > + unsigned long idx_start = PFN_DOWN(start); > > + unsigned long idx_end = PFN_DOWN(end - 1); > > + struct sgx_encl_page *page; > > + XA_STATE(xas, &encl->page_array, idx_start); > > + > > + /* > > + * Disallow RIE tasks as their VMA permissions might conflict with the > > "RIE", hmm what is that? > > /me looks at the test > > Aaah, READ_IMPLIES_EXEC. Is "RIE" some widely accepted acronym I'm not > aware of? I think it was used in some email discussions related to this piece of code but I'm happy to write it as READ_IMPLIES_EXEC :-) > > > + * enclave page permissions. > > + */ > > + if (!!(current->personality & READ_IMPLIES_EXEC)) > > The "!!" is not really needed - you're in boolean context. > > ... > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette Thanks for the remarks. /Jarkko