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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham 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 DEAAAC61DD8 for ; Mon, 16 Nov 2020 14:47:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5814222E8 for ; Mon, 16 Nov 2020 14:47:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="GB9am0Zm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730463AbgKPOrX (ORCPT ); Mon, 16 Nov 2020 09:47:23 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:56054 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730436AbgKPOrT (ORCPT ); Mon, 16 Nov 2020 09:47:19 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0AGEjbPE034277; Mon, 16 Nov 2020 14:47:01 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2020-01-29; bh=2EBmytMCHjHJfGitFZo/Hxec1iwHbVcdNqowhvn1ZAE=; b=GB9am0Zmj6+40DYpQnudsbnP4zUFqYrfiXMNspvMypuhH/uldXlU8eI2yFQ/KYtEm2Hc 5HoHQXRdoDJNtN2tr3LesdBgvRE8eKFfitxBb28kAjaXZY7etMZDM2GnOZ2B7+kGJe7K MB9ovjflbdM1TrlEv8RyMPRUnvWn7beB2RO1JvZN7OWKUFZixHsvD/W9KW0hJIgEgXWM +gNGmZTvDln8s5+UNDmv4u5hxy+38Z1RTotE+jJp8YULR64yF+ylyD9FmeNPdsvmGzfb PEO2Z6GDgVSUW7R8sXw4gT8gOAjg0a5bo+Ce6qmRZX855z3Odxxq2XahXBkSitYu2Vc1 Wg== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 34t7vmwaw5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 16 Nov 2020 14:47:01 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0AGEjVWj056120; Mon, 16 Nov 2020 14:47:00 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 34usps3tex-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 16 Nov 2020 14:47:00 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 0AGEkxkX025156; Mon, 16 Nov 2020 14:46:59 GMT Received: from localhost.localdomain (/92.157.91.83) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 16 Nov 2020 06:46:59 -0800 From: Alexandre Chartre To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, thomas.lendacky@amd.com, jroedel@suse.de Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com, junaids@google.com, oweisse@google.com, rppt@linux.vnet.ibm.com, graf@amazon.de, mgross@linux.intel.com, kuzuno@gmail.com, alexandre.chartre@oracle.com Subject: [RFC][PATCH v2 13/21] x86/pti: Execute syscall functions on the kernel stack Date: Mon, 16 Nov 2020 15:47:49 +0100 Message-Id: <20201116144757.1920077-14-alexandre.chartre@oracle.com> X-Mailer: git-send-email 2.18.4 In-Reply-To: <20201116144757.1920077-1-alexandre.chartre@oracle.com> References: <20201116144757.1920077-1-alexandre.chartre@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9806 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 mlxscore=0 bulkscore=0 suspectscore=0 adultscore=0 spamscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011160090 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9806 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 suspectscore=0 malwarescore=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 spamscore=0 adultscore=0 mlxscore=0 priorityscore=1501 phishscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011160090 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During a syscall, the kernel is entered and it switches the stack to the PTI stack which is mapped both in the kernel and in the user page-table. When executing the syscall function, switch to the kernel stack (which is mapped only in the kernel page-table) so that no kernel data leak to the userland through the stack. Signed-off-by: Alexandre Chartre --- arch/x86/entry/common.c | 11 ++++++++++- arch/x86/entry/entry_64.S | 1 + arch/x86/include/asm/irq_stack.h | 3 +++ 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 7ee15a12c115..1aba02ecb806 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -56,10 +56,19 @@ __visible noinstr void return_from_fork(struct pt_regs *regs, static __always_inline void run_syscall(sys_call_ptr_t sysfunc, struct pt_regs *regs) { + unsigned long stack; + if (!sysfunc) return; - regs->ax = sysfunc(regs); + if (!pti_enabled()) { + regs->ax = sysfunc(regs); + return; + } + + stack = (unsigned long)task_top_of_kernel_stack(current); + regs->ax = asm_call_syscall_on_stack((void *)(stack - 8), + sysfunc, regs); } #ifdef CONFIG_X86_64 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 29beab46bedd..6b88a0eb8975 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -771,6 +771,7 @@ SYM_FUNC_START(asm_call_on_stack_2) SYM_FUNC_START(asm_call_on_stack_3) SYM_INNER_LABEL(asm_call_sysvec_on_stack, SYM_L_GLOBAL) SYM_INNER_LABEL(asm_call_irq_on_stack, SYM_L_GLOBAL) +SYM_INNER_LABEL(asm_call_syscall_on_stack, SYM_L_GLOBAL) /* * Save the frame pointer unconditionally. This allows the ORC * unwinder to handle the stack switch. diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h index 359427216336..108d9da7c01c 100644 --- a/arch/x86/include/asm/irq_stack.h +++ b/arch/x86/include/asm/irq_stack.h @@ -5,6 +5,7 @@ #include #include +#include #ifdef CONFIG_X86_64 static __always_inline bool irqstack_active(void) @@ -25,6 +26,8 @@ void asm_call_sysvec_on_stack(void *sp, void (*func)(struct pt_regs *regs), struct pt_regs *regs); void asm_call_irq_on_stack(void *sp, void (*func)(struct irq_desc *desc), struct irq_desc *desc); +long asm_call_syscall_on_stack(void *sp, sys_call_ptr_t func, + struct pt_regs *regs); static __always_inline void __run_on_irqstack(void (*func)(void)) { -- 2.18.4