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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 309FACA9EC2 for ; Mon, 28 Oct 2019 21:04:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0FE00217D6 for ; Mon, 28 Oct 2019 21:04:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388964AbfJ1VET (ORCPT ); Mon, 28 Oct 2019 17:04:19 -0400 Received: from mga11.intel.com ([192.55.52.93]:5917 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388873AbfJ1VES (ORCPT ); Mon, 28 Oct 2019 17:04:18 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Oct 2019 14:04:18 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,241,1569308400"; d="scan'208";a="224759429" Received: from shrehore-mobl1.ti.intel.com (HELO localhost) ([10.251.82.5]) by fmsmga004.fm.intel.com with ESMTP; 28 Oct 2019 14:04:10 -0700 From: Jarkko Sakkinen To: linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org Cc: akpm@linux-foundation.org, dave.hansen@intel.com, sean.j.christopherson@intel.com, nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com, shay.katz-zamir@intel.com, haitao.huang@intel.com, andriy.shevchenko@linux.intel.com, tglx@linutronix.de, kai.svahn@intel.com, bp@alien8.de, josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com, puiterwijk@redhat.com, Jarkko Sakkinen Subject: [PATCH v23 04/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Date: Mon, 28 Oct 2019 23:03:04 +0200 Message-Id: <20191028210324.12475-5-jarkko.sakkinen@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191028210324.12475-1-jarkko.sakkinen@linux.intel.com> References: <20191028210324.12475-1-jarkko.sakkinen@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sean Christopherson Include SGX bit to the PF error codes and throw SIGSEGV with PF_SGX when a #PF with SGX set happens. CPU throws a #PF with the SGX bit in the event of Enclave Page Cache Map (EPCM) conflict. The EPCM is a CPU-internal table, which describes the properties for a enclave page. Enclaves are measured and signed software entities, which SGX hosts. [1] Although the primary purpose of the EPCM conflict checks is to prevent malicious accesses to an enclave, an illegit access can happen also for legit reasons. All SGX reserved memory, including EPCM is encrypted with a transient key that does not survive from the power transition. Throwing a SIGSEGV allows user space software react when this happens (e.g. rec-create the enclave, which was invalidated). [1] Intel SDM: 36.5.1 Enclave Page Cache Map (EPCM) Signed-off-by: Sean Christopherson Signed-off-by: Jarkko Sakkinen --- arch/x86/include/asm/traps.h | 1 + arch/x86/mm/fault.c | 13 +++++++++++++ 2 files changed, 14 insertions(+) diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index b25e633033c3..81472cae4024 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -171,5 +171,6 @@ enum x86_pf_error_code { X86_PF_RSVD = 1 << 3, X86_PF_INSTR = 1 << 4, X86_PF_PK = 1 << 5, + X86_PF_SGX = 1 << 15, }; #endif /* _ASM_X86_TRAPS_H */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9ceacd1156db..b1f0060b263f 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1178,6 +1178,19 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) if (error_code & X86_PF_PK) return 1; + /* + * Access is blocked by the Enclave Page Cache Map (EPCM), i.e. the + * access is allowed by the PTE but not the EPCM. This usually happens + * when the EPCM is yanked out from under us, e.g. by hardware after a + * suspend/resume cycle. In any case, software, i.e. the kernel, can't + * fix the source of the fault as the EPCM can't be directly modified by + * software. Handle the fault as an access error in order to signal + * userspace so that userspace can rebuild their enclave(s), even though + * userspace may not have actually violated access permissions. + */ + if (unlikely(error_code & X86_PF_SGX)) + return 1; + /* * Make sure to check the VMA so that we do not perform * faults just to hit a X86_PF_PK as soon as we fill in a -- 2.20.1