From patchwork Mon Aug 30 18:15:25 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: 12465773 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 83070C432BE for ; Mon, 30 Aug 2021 18:17:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 34F2C60F57 for ; Mon, 30 Aug 2021 18:17:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 34F2C60F57 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 9113D6B00A0; Mon, 30 Aug 2021 14:16:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8C0388D0001; Mon, 30 Aug 2021 14:16:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 78AE56B00A2; Mon, 30 Aug 2021 14:16:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0218.hostedemail.com [216.40.44.218]) by kanga.kvack.org (Postfix) with ESMTP id 5D0586B00A0 for ; Mon, 30 Aug 2021 14:16:28 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0D1901D984 for ; Mon, 30 Aug 2021 18:16:28 +0000 (UTC) X-FDA: 78532552056.23.8C74022 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf05.hostedemail.com (Postfix) with ESMTP id 743EF503D044 for ; Mon, 30 Aug 2021 18:16:25 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10092"; a="205545902" X-IronPort-AV: E=Sophos;i="5.84,364,1620716400"; d="scan'208";a="205545902" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Aug 2021 11:16:22 -0700 X-IronPort-AV: E=Sophos;i="5.84,364,1620716400"; d="scan'208";a="530533370" 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; 30 Aug 2021 11:16:22 -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" , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang , Rick P Edgecombe Cc: Yu-cheng Yu Subject: [PATCH v30 29/32] x86/cet/shstk: Add arch_prctl functions for shadow stack Date: Mon, 30 Aug 2021 11:15:25 -0700 Message-Id: <20210830181528.1569-30-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210830181528.1569-1-yu-cheng.yu@intel.com> References: <20210830181528.1569-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Authentication-Results: imf05.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf05.hostedemail.com: domain of yu-cheng.yu@intel.com has no SPF policy when checking 134.134.136.20) smtp.mailfrom=yu-cheng.yu@intel.com X-Stat-Signature: bkuspm6joooa1jch83uznbzjie4446ne X-Rspamd-Queue-Id: 743EF503D044 X-Rspamd-Server: rspam04 X-HE-Tag: 1630347385-688546 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: arch_prctl(ARCH_X86_CET_STATUS, u64 *args) Get CET feature status. The parameter 'args' is a pointer to a user buffer. The kernel returns the following information: *args = shadow stack/IBT status *(args + 1) = shadow stack base address *(args + 2) = shadow stack size 32-bit binaries use the same interface, but only lower 32-bits of each item. arch_prctl(ARCH_X86_CET_DISABLE, unsigned int features) Disable CET features specified in 'features'. Return -EPERM if CET is locked. arch_prctl(ARCH_X86_CET_LOCK) Lock in CET features. Also change do_arch_prctl_common()'s parameter 'cpuid_enabled' to 'arg2', as it is now also passed to prctl_cet(). Signed-off-by: Yu-cheng Yu Reviewed-by: Kees Cook --- arch/x86/include/asm/cet.h | 7 ++++ arch/x86/include/uapi/asm/prctl.h | 4 +++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/cet_prctl.c | 60 +++++++++++++++++++++++++++++++ arch/x86/kernel/process.c | 6 ++-- 5 files changed, 75 insertions(+), 3 deletions(-) create mode 100644 arch/x86/kernel/cet_prctl.c diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h index 90e84a45b80d..fb32cb093ebb 100644 --- a/arch/x86/include/asm/cet.h +++ b/arch/x86/include/asm/cet.h @@ -10,6 +10,7 @@ struct task_struct; struct thread_shstk { u64 base; u64 size; + u64 locked:1; }; #ifdef CONFIG_X86_SHADOW_STACK @@ -38,6 +39,12 @@ static inline int setup_signal_shadow_stack(int proc32, void __user *restorer) { static inline int restore_signal_shadow_stack(void) { return 0; } #endif +#ifdef CONFIG_X86_SHADOW_STACK +int prctl_cet(int option, u64 arg2); +#else +static inline int prctl_cet(int option, u64 arg2) { return -EINVAL; } +#endif + #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_CET_H */ diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h index 5a6aac9fa41f..9245bf629120 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -14,4 +14,8 @@ #define ARCH_MAP_VDSO_32 0x2002 #define ARCH_MAP_VDSO_64 0x2003 +#define ARCH_X86_CET_STATUS 0x3001 +#define ARCH_X86_CET_DISABLE 0x3002 +#define ARCH_X86_CET_LOCK 0x3003 + #endif /* _ASM_X86_PRCTL_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 9e064845e497..39e826b5cabd 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -151,6 +151,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += sev.o obj-$(CONFIG_X86_SHADOW_STACK) += shstk.o +obj-$(CONFIG_X86_SHADOW_STACK) += shstk.o cet_prctl.o ### # 64 bit specific files ifeq ($(CONFIG_X86_64),y) diff --git a/arch/x86/kernel/cet_prctl.c b/arch/x86/kernel/cet_prctl.c new file mode 100644 index 000000000000..b426d200e070 --- /dev/null +++ b/arch/x86/kernel/cet_prctl.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* See Documentation/x86/intel_cet.rst. */ + +static int cet_copy_status_to_user(struct thread_shstk *shstk, u64 __user *ubuf) +{ + u64 buf[3] = {}; + + if (shstk->size) { + buf[0] |= GNU_PROPERTY_X86_FEATURE_1_SHSTK; + buf[1] = shstk->base; + buf[2] = shstk->size; + } + + return copy_to_user(ubuf, buf, sizeof(buf)); +} + +int prctl_cet(int option, u64 arg2) +{ + struct thread_shstk *shstk; + + if (!cpu_feature_enabled(X86_FEATURE_SHSTK)) + return -ENOTSUPP; + + shstk = ¤t->thread.shstk; + + if (option == ARCH_X86_CET_STATUS) + return cet_copy_status_to_user(shstk, (u64 __user *)arg2); + + switch (option) { + case ARCH_X86_CET_DISABLE: + if (shstk->locked) + return -EPERM; + + if (arg2 & ~GNU_PROPERTY_X86_FEATURE_1_VALID) + return -EINVAL; + if (arg2 & GNU_PROPERTY_X86_FEATURE_1_SHSTK) + shstk_disable(); + return 0; + + case ARCH_X86_CET_LOCK: + if (arg2) + return -EINVAL; + shstk->locked = 1; + return 0; + + default: + return -ENOSYS; + } +} diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index bade6a594d63..7d8ccebdcab1 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -1006,14 +1006,14 @@ unsigned long get_wchan(struct task_struct *p) } long do_arch_prctl_common(struct task_struct *task, int option, - unsigned long cpuid_enabled) + unsigned long arg2) { switch (option) { case ARCH_GET_CPUID: return get_cpuid_mode(); case ARCH_SET_CPUID: - return set_cpuid_mode(task, cpuid_enabled); + return set_cpuid_mode(task, arg2); } - return -EINVAL; + return prctl_cet(option, arg2); }