From patchwork Wed Jun 19 22:23:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 11005439 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E161028DC for ; Wed, 19 Jun 2019 22:24:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D0433286AE for ; Wed, 19 Jun 2019 22:24:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CD757288BA; Wed, 19 Jun 2019 22:24:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 72CB8288AA for ; Wed, 19 Jun 2019 22:24:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726246AbfFSWYP (ORCPT ); Wed, 19 Jun 2019 18:24:15 -0400 Received: from mga18.intel.com ([134.134.136.126]:40155 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730747AbfFSWYP (ORCPT ); Wed, 19 Jun 2019 18:24:15 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Jun 2019 15:24:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,394,1557212400"; d="scan'208";a="150743761" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.36]) by orsmga007.jf.intel.com with ESMTP; 19 Jun 2019 15:24:13 -0700 From: Sean Christopherson To: Jarkko Sakkinen Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, Bill Roberts , Casey Schaufler , James Morris , Dave Hansen , Cedric Xing , Andy Lutomirski , Jethro Beekman , "Dr . Greg Wettstein" , Stephen Smalley Subject: [RFC PATCH v4 05/12] x86/sgx: Enforce noexec filesystem restriction for enclaves Date: Wed, 19 Jun 2019 15:23:54 -0700 Message-Id: <20190619222401.14942-6-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190619222401.14942-1-sean.j.christopherson@intel.com> References: <20190619222401.14942-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Do not allow an enclave page to be mapped with PROT_EXEC if the source vma does not have VM_MAYEXEC. This effectively enforces noexec as do_mmap() clears VM_MAYEXEC if the vma is being loaded from a noexec path, i.e. prevents executing a file by loading it into an enclave. Signed-off-by: Sean Christopherson --- arch/x86/kernel/cpu/sgx/driver/ioctl.c | 42 +++++++++++++++++++++++--- 1 file changed, 37 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c index e18d2afd2aad..1fca70a36ce3 100644 --- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c @@ -564,6 +564,39 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long addr, return ret; } +static int sgx_encl_page_copy(void *dst, unsigned long src, unsigned long prot) +{ + struct vm_area_struct *vma; + int ret; + + /* Hold mmap_sem across copy_from_user() to avoid a TOCTOU race. */ + down_read(¤t->mm->mmap_sem); + + /* Query vma's VM_MAYEXEC as an indirect path_noexec() check. */ + if (prot & PROT_EXEC) { + vma = find_vma(current->mm, src); + if (!vma) { + ret = -EFAULT; + goto out; + } + + if (!(vma->vm_flags & VM_MAYEXEC)) { + ret = -EACCES; + goto out; + } + } + + if (copy_from_user(dst, (void __user *)src, PAGE_SIZE)) + ret = -EFAULT; + else + ret = 0; + +out: + up_read(¤t->mm->mmap_sem); + + return ret; +} + /** * sgx_ioc_enclave_add_page - handler for %SGX_IOC_ENCLAVE_ADD_PAGE * @@ -604,13 +637,12 @@ static long sgx_ioc_enclave_add_page(struct file *filep, void __user *arg) data = kmap(data_page); - if (copy_from_user((void *)data, (void __user *)addp.src, PAGE_SIZE)) { - ret = -EFAULT; - goto out; - } - prot = addp.prot & (PROT_READ | PROT_WRITE | PROT_EXEC); + ret = sgx_encl_page_copy(data, addp.src, prot); + if (ret) + goto out; + ret = sgx_encl_add_page(encl, addp.addr, data, &secinfo, addp.mrmask, prot); if (ret)