From patchwork Thu Apr 15 22:14:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu-cheng Yu X-Patchwork-Id: 12206161 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 CFC3EC433B4 for ; Thu, 15 Apr 2021 22:16:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 73A8C61074 for ; Thu, 15 Apr 2021 22:16:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 73A8C61074 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8C7808E0009; Thu, 15 Apr 2021 18:15:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5824F8E0006; Thu, 15 Apr 2021 18:15:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1ECDC8E0005; Thu, 15 Apr 2021 18:15:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0198.hostedemail.com [216.40.44.198]) by kanga.kvack.org (Postfix) with ESMTP id D9B4D8E0009 for ; Thu, 15 Apr 2021 18:15:42 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 9D8274DB2 for ; Thu, 15 Apr 2021 22:15:42 +0000 (UTC) X-FDA: 78036009324.11.DD797F1 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf11.hostedemail.com (Postfix) with ESMTP id CA4DC2000250 for ; Thu, 15 Apr 2021 22:15:31 +0000 (UTC) IronPort-SDR: VWWe1QqRYi0j1DbGOq1mDJB7EFS9w7xi4SFCLNMIoFOpB9Ee99/zgHBsvKrOSIOxr5Lu+578fL FXYhK/8QvU2g== X-IronPort-AV: E=McAfee;i="6200,9189,9955"; a="191764360" X-IronPort-AV: E=Sophos;i="5.82,225,1613462400"; d="scan'208";a="191764360" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Apr 2021 15:15:39 -0700 IronPort-SDR: L0ERRbeNh2MfSfyXl7QXsXYtpH159o4fM46f9MXp5SQVwX5Oi6xjt7NgFzdiT8SStB7EUdAzlX wFIU3IACA77g== X-IronPort-AV: E=Sophos;i="5.82,225,1613462400"; d="scan'208";a="451270936" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Apr 2021 15:15:39 -0700 From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Cc: Yu-cheng Yu Subject: [PATCH v25 22/30] x86/cet/shstk: Add user-mode shadow stack support Date: Thu, 15 Apr 2021 15:14:11 -0700 Message-Id: <20210415221419.31835-23-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210415221419.31835-1-yu-cheng.yu@intel.com> References: <20210415221419.31835-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 X-Stat-Signature: nf9zyy9hzp9tigrorjgq6igs48idcxiq X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: CA4DC2000250 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mga11.intel.com; client-ip=192.55.52.93 X-HE-DKIM-Result: none/none X-HE-Tag: 1618524931-31241 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: Introduce basic shadow stack enabling/disabling/allocation routines. A task's shadow stack is allocated from memory with VM_SHADOW_STACK flag and has a fixed size of min(RLIMIT_STACK, 4GB). Signed-off-by: Yu-cheng Yu Cc: Kees Cook --- v25: - Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK. - Update alloc_shstk(), remove unused input flags. v24: - Rename cet.c to shstk.c, update related areas accordingly. arch/x86/include/asm/cet.h | 29 ++++++++ arch/x86/include/asm/processor.h | 5 ++ arch/x86/kernel/Makefile | 2 + arch/x86/kernel/shstk.c | 123 +++++++++++++++++++++++++++++++ 4 files changed, 159 insertions(+) create mode 100644 arch/x86/include/asm/cet.h create mode 100644 arch/x86/kernel/shstk.c diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h new file mode 100644 index 000000000000..aa85d599b184 --- /dev/null +++ b/arch/x86/include/asm/cet.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_CET_H +#define _ASM_X86_CET_H + +#ifndef __ASSEMBLY__ +#include + +struct task_struct; +/* + * Per-thread CET status + */ +struct cet_status { + unsigned long shstk_base; + unsigned long shstk_size; +}; + +#ifdef CONFIG_X86_SHADOW_STACK +int shstk_setup(void); +void shstk_free(struct task_struct *p); +void shstk_disable(void); +#else +static inline int shstk_setup(void) { return 0; } +static inline void shstk_free(struct task_struct *p) {} +static inline void shstk_disable(void) {} +#endif + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_X86_CET_H */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f1b9ed5efaa9..3690b78e55bb 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -27,6 +27,7 @@ struct vm86; #include #include #include +#include #include #include @@ -535,6 +536,10 @@ struct thread_struct { unsigned int sig_on_uaccess_err:1; +#ifdef CONFIG_X86_SHADOW_STACK + struct cet_status cet; +#endif + /* Floating point and extended processor state */ struct fpu fpu; /* diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 2ddf08351f0b..0f99b093f350 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -150,6 +150,8 @@ obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += sev-es.o +obj-$(CONFIG_X86_SHADOW_STACK) += shstk.o + ### # 64 bit specific files ifeq ($(CONFIG_X86_64),y) diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c new file mode 100644 index 000000000000..c815c7507830 --- /dev/null +++ b/arch/x86/kernel/shstk.c @@ -0,0 +1,123 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * shstk.c - Intel shadow stack support + * + * Copyright (c) 2021, Intel Corporation. + * Yu-cheng Yu + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void start_update_msrs(void) +{ + fpregs_lock(); + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + __fpregs_load_activate(); +} + +static void end_update_msrs(void) +{ + fpregs_unlock(); +} + +static unsigned long alloc_shstk(unsigned long size) +{ + struct mm_struct *mm = current->mm; + unsigned long addr, populate; + int flags = MAP_ANONYMOUS | MAP_PRIVATE; + + mmap_write_lock(mm); + addr = do_mmap(NULL, 0, size, PROT_READ, flags, VM_SHADOW_STACK, 0, + &populate, NULL); + mmap_write_unlock(mm); + + return addr; +} + +int shstk_setup(void) +{ + unsigned long addr, size; + struct cet_status *cet = ¤t->thread.cet; + + if (!cpu_feature_enabled(X86_FEATURE_SHSTK)) + return -EOPNOTSUPP; + + size = round_up(min_t(unsigned long long, rlimit(RLIMIT_STACK), SZ_4G), PAGE_SIZE); + addr = alloc_shstk(size); + if (IS_ERR_VALUE(addr)) + return PTR_ERR((void *)addr); + + cet->shstk_base = addr; + cet->shstk_size = size; + + start_update_msrs(); + wrmsrl(MSR_IA32_PL3_SSP, addr + size); + wrmsrl(MSR_IA32_U_CET, CET_SHSTK_EN); + end_update_msrs(); + return 0; +} + +void shstk_free(struct task_struct *tsk) +{ + struct cet_status *cet = &tsk->thread.cet; + + if (!cpu_feature_enabled(X86_FEATURE_SHSTK) || + !cet->shstk_size || + !cet->shstk_base) + return; + + if (!tsk->mm) + return; + + while (1) { + int r; + + r = vm_munmap(cet->shstk_base, cet->shstk_size); + + /* + * vm_munmap() returns -EINTR when mmap_lock is held by + * something else, and that lock should not be held for a + * long time. Retry it for the case. + */ + if (r == -EINTR) { + cond_resched(); + continue; + } + break; + } + + cet->shstk_base = 0; + cet->shstk_size = 0; +} + +void shstk_disable(void) +{ + struct cet_status *cet = ¤t->thread.cet; + u64 msr_val; + + if (!cpu_feature_enabled(X86_FEATURE_SHSTK) || + !cet->shstk_size || + !cet->shstk_base) + return; + + start_update_msrs(); + rdmsrl(MSR_IA32_U_CET, msr_val); + wrmsrl(MSR_IA32_U_CET, msr_val & ~CET_SHSTK_EN); + wrmsrl(MSR_IA32_PL3_SSP, 0); + end_update_msrs(); + + shstk_free(current); +}