From patchwork Tue Feb 11 13:52:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joerg Roedel X-Patchwork-Id: 11375605 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 30E9192A for ; Tue, 11 Feb 2020 13:56:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A5F42467C for ; Tue, 11 Feb 2020 13:56:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729582AbgBKN4P (ORCPT ); Tue, 11 Feb 2020 08:56:15 -0500 Received: from 8bytes.org ([81.169.241.247]:52198 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729544AbgBKNxZ (ORCPT ); Tue, 11 Feb 2020 08:53:25 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 09D04E82; Tue, 11 Feb 2020 14:53:13 +0100 (CET) From: Joerg Roedel To: x86@kernel.org Cc: hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Joerg Roedel , Joerg Roedel Subject: [PATCH 38/62] x86/sev-es: Handle instruction fetches from user-space Date: Tue, 11 Feb 2020 14:52:32 +0100 Message-Id: <20200211135256.24617-39-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200211135256.24617-1-joro@8bytes.org> References: <20200211135256.24617-1-joro@8bytes.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Joerg Roedel When a #VC exception is triggered by user-space the instruction decoder needs to read the instruction bytes from user addresses. Enhance es_fetch_insn_byte() to safely fetch kernel and user instruction bytes. Signed-off-by: Joerg Roedel --- arch/x86/kernel/sev-es.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 2a801919e7c0..f5bff4219f6f 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -61,13 +61,29 @@ static enum es_result es_fetch_insn_byte(struct es_em_ctxt *ctxt, unsigned int offset, char *buffer) { - char *rip = (char *)ctxt->regs->ip; - - /* More checks are needed when we boot to user-space */ - if (!check_kernel(ctxt->regs)) - return ES_UNSUPPORTED; - - buffer[offset] = rip[offset]; + if (user_mode(ctxt->regs)) { + unsigned long addr = ctxt->regs->ip + offset; + char __user *rip = (char __user *)addr; + + if (unlikely(addr >= TASK_SIZE_MAX)) + return ES_UNSUPPORTED; + + if (copy_from_user(buffer + offset, rip, 1)) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.cr2 = addr; + ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER; + return ES_EXCEPTION; + } + } else { + char *rip = (char *)ctxt->regs->ip + offset; + + if (probe_kernel_read(buffer + offset, rip, 1) != 0) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.cr2 = (unsigned long)rip; + ctxt->fi.error_code = X86_PF_INSTR; + return ES_EXCEPTION; + } + } return ES_OK; }