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=-12.7 required=3.0 tests=BAYES_00, 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 5EA6FC61DD8 for ; Tue, 10 Nov 2020 16:23:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D0EE020780 for ; Tue, 10 Nov 2020 16:23:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0EE020780 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 D255A6B0095; Tue, 10 Nov 2020 11:22:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B83406B009A; Tue, 10 Nov 2020 11:22:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 540BF6B0099; Tue, 10 Nov 2020 11:22:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0151.hostedemail.com [216.40.44.151]) by kanga.kvack.org (Postfix) with ESMTP id BD74C6B0096 for ; Tue, 10 Nov 2020 11:22:58 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 671C0181AEF10 for ; Tue, 10 Nov 2020 16:22:58 +0000 (UTC) X-FDA: 77469027636.08.lead98_4413569272f6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id 4C5751819E766 for ; Tue, 10 Nov 2020 16:22:58 +0000 (UTC) X-HE-Tag: lead98_4413569272f6 X-Filterd-Recvd-Size: 11412 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Tue, 10 Nov 2020 16:22:57 +0000 (UTC) IronPort-SDR: wJNedO3hBSbokfy0sKhG3UoyzxO/RuY3IUmGWkVs4PVa/A0vZkIb1XfH9L3pHg4b3ZQZ5HSOk+ kkRF0uVUESwA== X-IronPort-AV: E=McAfee;i="6000,8403,9801"; a="170110980" X-IronPort-AV: E=Sophos;i="5.77,466,1596524400"; d="scan'208";a="170110980" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Nov 2020 08:22:54 -0800 IronPort-SDR: p8fQqqYozSDnTxMFjAdHCMh0tw8haGOCp/RWCo6Go/IK23rwqrFoa9Vazc4TzsVAa5SkML1tPg 75U3jxoTYdzA== X-IronPort-AV: E=Sophos;i="5.77,466,1596524400"; d="scan'208";a="365572907" 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; 10 Nov 2020 08:22:54 -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 Cc: Yu-cheng Yu Subject: [PATCH v15 20/26] x86/cet/shstk: User-mode shadow stack support Date: Tue, 10 Nov 2020 08:22:05 -0800 Message-Id: <20201110162211.9207-21-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20201110162211.9207-1-yu-cheng.yu@intel.com> References: <20201110162211.9207-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: This patch adds basic shadow stack enabling/disabling 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 --- arch/x86/include/asm/cet.h | 28 +++++ arch/x86/include/asm/disabled-features.h | 8 +- arch/x86/include/asm/processor.h | 5 + arch/x86/kernel/Makefile | 2 + arch/x86/kernel/cet.c | 147 +++++++++++++++++++++++ arch/x86/kernel/cpu/common.c | 28 +++++ arch/x86/kernel/process.c | 1 + 7 files changed, 218 insertions(+), 1 deletion(-) 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/disabled-features.h b/arch/x86/include/= asm/disabled-features.h index 5861d34f9771..6a9fb7f9bc01 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -62,6 +62,12 @@ # define DISABLE_ENQCMD (1 << (X86_FEATURE_ENQCMD & 31)) #endif =20 +#ifdef CONFIG_X86_SHADOW_STACK_USER +#define DISABLE_SHSTK 0 +#else +#define DISABLE_SHSTK (1 << (X86_FEATURE_SHSTK & 31)) +#endif + /* * Make sure to add features to the correct mask */ @@ -82,7 +88,7 @@ #define DISABLED_MASK14 0 #define DISABLED_MASK15 0 #define DISABLED_MASK16 (DISABLE_PKU|DISABLE_OSPKE|DISABLE_LA57|DISABLE_= UMIP| \ - DISABLE_ENQCMD) + DISABLE_ENQCMD|DISABLE_SHSTK) #define DISABLED_MASK17 0 #define DISABLED_MASK18 0 #define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS !=3D 19) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/proc= essor.h index 82a08b585818..2e0d9286f6cf 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 =20 #include #include @@ -536,6 +537,10 @@ struct thread_struct { =20 unsigned int sig_on_uaccess_err:1; =20 +#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 68608bd892c0..4a89d0f3792e 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -151,6 +151,8 @@ obj-$(CONFIG_UNWINDER_FRAME_POINTER) +=3D unwind_fram= e.o obj-$(CONFIG_UNWINDER_GUESS) +=3D unwind_guess.o =20 obj-$(CONFIG_AMD_MEM_ENCRYPT) +=3D sev-es.o +obj-$(CONFIG_X86_CET) +=3D 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..f8b0a077594f --- /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 =3D ¤t->thread.fpu; + unsigned long ssp =3D 0; + + fpregs_lock(); + + if (fpregs_state_valid(fpu, smp_processor_id())) { + rdmsrl(MSR_IA32_PL3_SSP, ssp); + } else { + struct cet_user_state *p; + + p =3D get_xsave_addr(&fpu->state.xsave, XFEATURE_CET_USER); + if (p) + ssp =3D p->user_ssp; + } + + fpregs_unlock(); + return ssp; +} + +static unsigned long alloc_shstk(unsigned long size, int flags) +{ + struct mm_struct *mm =3D current->mm; + unsigned long addr, populate; + + /* VM_SHSTK requires MAP_ANONYMOUS, MAP_PRIVATE */ + flags |=3D MAP_ANONYMOUS | MAP_PRIVATE; + + mmap_write_lock(mm); + addr =3D 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 =3D ¤t->thread.cet; + + if (!static_cpu_has(X86_FEATURE_SHSTK)) + return -EOPNOTSUPP; + + size =3D round_up(min(rlimit(RLIMIT_STACK), 1UL << 32), PAGE_SIZE); + addr =3D alloc_shstk(size, 0); + + if (IS_ERR_VALUE(addr)) + return PTR_ERR((void *)addr); + + cet->shstk_base =3D addr; + cet->shstk_size =3D 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 =3D ¤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 =3D &tsk->thread.cet; + + if (!static_cpu_has(X86_FEATURE_SHSTK) || + !cet->shstk_size || !cet->shstk_base) + return; + + if (!tsk->mm || (tsk->mm !=3D current->mm)) + return; + + while (1) { + int r; + + r =3D vm_munmap(cet->shstk_base, cet->shstk_size); + + /* + * Retry if mmap_lock is not available. + */ + if (r =3D=3D -EINTR) { + cond_resched(); + continue; + } + + WARN_ON_ONCE(r); + break; + } + + cet->shstk_base =3D 0; + cet->shstk_size =3D 0; +} diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 35ad8480c464..3d38ae02d9d3 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -57,6 +57,7 @@ #include #include #include +#include #include =20 #include "cpu.h" @@ -510,6 +511,32 @@ static __init int setup_disable_pku(char *arg) __setup("nopku", setup_disable_pku); #endif /* CONFIG_X86_64 */ =20 +static __always_inline void setup_cet(struct cpuinfo_x86 *c) +{ + if (!cpu_feature_enabled(X86_FEATURE_SHSTK) && + !cpu_feature_enabled(X86_FEATURE_IBT)) + return; + + cr4_set_bits(X86_CR4_CET); +} + +#ifdef CONFIG_X86_SHADOW_STACK_USER +static __init int setup_disable_shstk(char *s) +{ + /* require an exact match without trailing characters */ + if (s[0] !=3D '\0') + return 0; + + if (!boot_cpu_has(X86_FEATURE_SHSTK)) + return 1; + + setup_clear_cpu_cap(X86_FEATURE_SHSTK); + pr_info("x86: 'no_user_shstk' specified, disabling user Shadow Stack\n"= ); + return 1; +} +__setup("no_user_shstk", setup_disable_shstk); +#endif + /* * Some CPU features depend on higher CPUID levels, which may not always * be available due to CPUID level capping or broken virtualization @@ -1591,6 +1618,7 @@ static void identify_cpu(struct cpuinfo_x86 *c) =20 x86_init_rdrand(c); setup_pku(c); + setup_cet(c); =20 /* * Clear/Set all flags overridden by options, need do it diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index ba4593a913fa..ff3b44d6740b 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -43,6 +43,7 @@ #include #include #include +#include =20 #include "process.h" =20 --=20 2.21.0