From patchwork Wed Feb 17 22:27:24 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: 12092537 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=-16.7 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 71B61C433DB for ; Wed, 17 Feb 2021 22:28:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0F4CF64E33 for ; Wed, 17 Feb 2021 22:28:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F4CF64E33 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 CA1238D000F; Wed, 17 Feb 2021 17:28:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C04818D000B; Wed, 17 Feb 2021 17:28:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7B598D000F; Wed, 17 Feb 2021 17:28:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0193.hostedemail.com [216.40.44.193]) by kanga.kvack.org (Postfix) with ESMTP id 871A78D000B for ; Wed, 17 Feb 2021 17:28:08 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5774B3626 for ; Wed, 17 Feb 2021 22:28:08 +0000 (UTC) X-FDA: 77829199056.17.cup64_4b136b827650 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 3E873180D0180 for ; Wed, 17 Feb 2021 22:28:08 +0000 (UTC) X-HE-Tag: cup64_4b136b827650 X-Filterd-Recvd-Size: 8520 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Wed, 17 Feb 2021 22:28:06 +0000 (UTC) IronPort-SDR: sar1UroqgpEZlaMKIsitUKG9EA4/Y3bhzyz5YOkXW8alf9ie4a//UXfLm+0RI55mi/OOSK934S 21xb5deT530g== X-IronPort-AV: E=McAfee;i="6000,8403,9898"; a="170994069" X-IronPort-AV: E=Sophos;i="5.81,185,1610438400"; d="scan'208";a="170994069" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Feb 2021 14:28:05 -0800 IronPort-SDR: Xli2ufXk495OxF9xjTM+LFfqTrIIjRL+nFOmUbC7ij1emZXxrdiuohBD1YhFTn5YtIYcWq2NjR QdejM792/DQQ== X-IronPort-AV: E=Sophos;i="5.81,185,1610438400"; d="scan'208";a="400172676" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Feb 2021 14:28:05 -0800 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 v21 20/26] x86/cet/shstk: User-mode shadow stack support Date: Wed, 17 Feb 2021 14:27:24 -0800 Message-Id: <20210217222730.15819-21-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210217222730.15819-1-yu-cheng.yu@intel.com> References: <20210217222730.15819-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 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_SHSTK flag and has a fixed size of min(RLIMIT_STACK, 4GB). Signed-off-by: Yu-cheng Yu Reviewed-by: Kees Cook --- arch/x86/include/asm/cet.h | 28 ++++++ arch/x86/include/asm/processor.h | 5 ++ arch/x86/kernel/Makefile | 2 + arch/x86/kernel/cet.c | 147 +++++++++++++++++++++++++++++++ 4 files changed, 182 insertions(+) create mode 100644 arch/x86/include/asm/cet.h create mode 100644 arch/x86/kernel/cet.c diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h new file mode 100644 index 000000000000..5750fbcbb952 --- /dev/null +++ b/arch/x86/include/asm/cet.h @@ -0,0 +1,28 @@ +/* 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_CET +int cet_setup_shstk(void); +void cet_disable_shstk(void); +void cet_free_shstk(struct task_struct *p); +#else +static inline void cet_disable_shstk(void) {} +static inline void cet_free_shstk(struct task_struct *p) {} +#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 c20a52b5534b..51158c6beb4f 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 @@ -536,6 +537,10 @@ struct thread_struct { unsigned int sig_on_uaccess_err:1; +#ifdef CONFIG_X86_CET + 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 5eeb808eb024..4a9a7e7d00dc 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -151,6 +151,8 @@ 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_CET) += cet.o + ### # 64 bit specific files ifeq ($(CONFIG_X86_64),y) diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c new file mode 100644 index 000000000000..d25a03215984 --- /dev/null +++ b/arch/x86/kernel/cet.c @@ -0,0 +1,147 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * cet.c - Control-flow Enforcement (CET) + * + * Copyright (c) 2019, Intel Corporation. + * Yu-cheng Yu + */ + +#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 cet_get_shstk_addr(void) +{ + struct fpu *fpu = ¤t->thread.fpu; + unsigned long ssp = 0; + + fpregs_lock(); + + if (fpregs_state_valid(fpu, smp_processor_id())) { + rdmsrl(MSR_IA32_PL3_SSP, ssp); + } else { + struct cet_user_state *p; + + p = get_xsave_addr(&fpu->state.xsave, XFEATURE_CET_USER); + if (p) + ssp = p->user_ssp; + } + + fpregs_unlock(); + return ssp; +} + +static unsigned long alloc_shstk(unsigned long size, int flags) +{ + struct mm_struct *mm = current->mm; + unsigned long addr, populate; + + /* VM_SHSTK requires MAP_ANONYMOUS, MAP_PRIVATE */ + flags |= MAP_ANONYMOUS | MAP_PRIVATE; + + mmap_write_lock(mm); + addr = do_mmap(NULL, 0, size, PROT_READ, flags, VM_SHSTK, 0, + &populate, NULL); + mmap_write_unlock(mm); + + if (populate) + mm_populate(addr, populate); + + return addr; +} + +int cet_setup_shstk(void) +{ + unsigned long addr, size; + struct cet_status *cet = ¤t->thread.cet; + + if (!static_cpu_has(X86_FEATURE_SHSTK)) + return -EOPNOTSUPP; + + size = round_up(min(rlimit(RLIMIT_STACK), 1UL << 32), PAGE_SIZE); + addr = alloc_shstk(size, 0); + + 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 cet_disable_shstk(void) +{ + struct cet_status *cet = ¤t->thread.cet; + u64 msr_val; + + if (!static_cpu_has(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(); + + cet_free_shstk(current); +} + +void cet_free_shstk(struct task_struct *tsk) +{ + struct cet_status *cet = &tsk->thread.cet; + + if (!static_cpu_has(X86_FEATURE_SHSTK) || + !cet->shstk_size || !cet->shstk_base) + return; + + if (!tsk->mm || tsk->mm != current->mm) + return; + + while (1) { + int r; + + r = vm_munmap(cet->shstk_base, cet->shstk_size); + + /* + * Retry if mmap_lock is not available. + */ + if (r == -EINTR) { + cond_resched(); + continue; + } + + WARN_ON_ONCE(r); + break; + } + + cet->shstk_base = 0; + cet->shstk_size = 0; +}