From nobody Sun Sep 14 18:06:41 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4772C004D4 for ; Thu, 19 Jan 2023 21:44:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231334AbjASVoG (ORCPT ); Thu, 19 Jan 2023 16:44:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231180AbjASViy (ORCPT ); Thu, 19 Jan 2023 16:38:54 -0500 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F0FF7C875; Thu, 19 Jan 2023 13:28:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674163680; x=1705699680; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=Q/roafiLg5FWGNhLb00ov8wc44ATIJKREdVQC5GYlS4=; b=ipgO3ufEFgEAo7SYyiJvYCPkVOXpWCDkMo3S8b3DAyLtfV57O8wkMZuo siVy1P5kxgXiI7i4DcMjfiji+smZpsdlh8QUtoyAiTp0OKuH7ZAoJ3n6F nUPRDX9oBvR6AjuXgphJQSPSWUzYXZamr7mg9rfaS7H4hNvfeCT85ZABu RMC/5FZWgxKrzcjUOLXrhITPQZQhI1VrQjp8SlQTpQpgA/kicoyEELClg q5iYS2D21V7wMttoEvG1uO8RuSLgb9QbJp/RzD8mgFqTbTqYXOYiivSIe P4QQ2rzlsD+9fUzvsNFeKxNq1/G4jaU0SkLuHdEz5Xa1lrDCvt9jekpgA A==; X-IronPort-AV: E=McAfee;i="6500,9779,10595"; a="323120102" X-IronPort-AV: E=Sophos;i="5.97,230,1669104000"; d="scan'208";a="323120102" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jan 2023 13:24:27 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10595"; a="989139201" X-IronPort-AV: E=Sophos;i="5.97,230,1669104000"; d="scan'208";a="989139201" Received: from hossain3-mobl.amr.corp.intel.com (HELO rpedgeco-desk.amr.corp.intel.com) ([10.252.128.187]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jan 2023 13:24:25 -0800 From: Rick Edgecombe 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 , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Andrew.Cooper3@citrix.com, christina.schimpe@intel.com Cc: rick.p.edgecombe@intel.com Subject: [PATCH v5 39/39] x86/shstk: Add ARCH_SHSTK_STATUS Date: Thu, 19 Jan 2023 13:23:17 -0800 Message-Id: <20230119212317.8324-40-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230119212317.8324-1-rick.p.edgecombe@intel.com> References: <20230119212317.8324-1-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" CRIU and GDB need to get the current shadow stack and WRSS enablement status. This information is already available via /proc/pid/status, but this is inconvenient for CRIU because it involves parsing the text output in an area of the code where this is difficult. Provide a status arch_prctl(), ARCH_SHSTK_STATUS for retrieving the status. Have arg2 be a userspace address, and make the new arch_prctl simply copy the features out to userspace. Tested-by: Pengfei Xu Suggested-by: Mike Rapoport Signed-off-by: Rick Edgecombe Reviewed-by: Kees Cook --- v5: - Fix typo in commit log v4: - New patch Documentation/x86/shstk.rst | 6 ++++++ arch/x86/include/asm/shstk.h | 4 ++-- arch/x86/include/uapi/asm/prctl.h | 1 + arch/x86/kernel/process_64.c | 1 + arch/x86/kernel/shstk.c | 8 +++++++- 5 files changed, 17 insertions(+), 3 deletions(-) diff --git a/Documentation/x86/shstk.rst b/Documentation/x86/shstk.rst index e8ed5fc0f7ae..7f4af798794e 100644 --- a/Documentation/x86/shstk.rst +++ b/Documentation/x86/shstk.rst @@ -77,6 +77,11 @@ arch_prctl(ARCH_SHSTK_UNLOCK, unsigned long features) Unlock features. 'features' is a mask of all features to unlock. All bits set are processed, unset bits are ignored. Only works via ptrace. =20 +arch_prctl(ARCH_SHSTK_STATUS, unsigned long addr) + Copy the currently enabled features to the address passed in addr. The + features are described using the bits passed into the others in + 'features'. + The return values are as follows. On success, return 0. On error, errno can be:: =20 @@ -84,6 +89,7 @@ be:: -ENOTSUPP if the feature is not supported by the hardware or kernel. -EINVAL arguments (non existing feature, etc) + -EFAULT if could not copy information back to userspace =20 The feature's bits supported are:: =20 diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h index 746c040f7cb6..73de995f55ca 100644 --- a/arch/x86/include/asm/shstk.h +++ b/arch/x86/include/asm/shstk.h @@ -14,7 +14,7 @@ struct thread_shstk { u64 size; }; =20 -long shstk_prctl(struct task_struct *task, int option, unsigned long featu= res); +long shstk_prctl(struct task_struct *task, int option, unsigned long arg2); void reset_thread_features(void); int shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_fl= ags, unsigned long stack_size, @@ -24,7 +24,7 @@ int setup_signal_shadow_stack(struct ksignal *ksig); int restore_signal_shadow_stack(void); #else static inline long shstk_prctl(struct task_struct *task, int option, - unsigned long features) { return -EINVAL; } + unsigned long arg2) { return -EINVAL; } static inline void reset_thread_features(void) {} static inline int shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags, diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/= prctl.h index 200efbbe5809..1b85bc876c2d 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -26,6 +26,7 @@ #define ARCH_SHSTK_DISABLE 0x5002 #define ARCH_SHSTK_LOCK 0x5003 #define ARCH_SHSTK_UNLOCK 0x5004 +#define ARCH_SHSTK_STATUS 0x5005 =20 /* ARCH_SHSTK_ features bits */ #define ARCH_SHSTK_SHSTK (1ULL << 0) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index d368854fa9c4..dde43caf196e 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -836,6 +836,7 @@ long do_arch_prctl_64(struct task_struct *task, int opt= ion, unsigned long arg2) case ARCH_SHSTK_DISABLE: case ARCH_SHSTK_LOCK: case ARCH_SHSTK_UNLOCK: + case ARCH_SHSTK_STATUS: return shstk_prctl(task, option, arg2); default: ret =3D -EINVAL; diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c index a639119a21c5..3b1433bd63c7 100644 --- a/arch/x86/kernel/shstk.c +++ b/arch/x86/kernel/shstk.c @@ -445,8 +445,14 @@ SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr,= unsigned long, size, unsi return alloc_shstk(addr, aligned_size, size, set_tok); } =20 -long shstk_prctl(struct task_struct *task, int option, unsigned long featu= res) +long shstk_prctl(struct task_struct *task, int option, unsigned long arg2) { + unsigned long features =3D arg2; + + if (option =3D=3D ARCH_SHSTK_STATUS) { + return put_user(task->thread.features, (unsigned long __user *)arg2); + } + if (option =3D=3D ARCH_SHSTK_LOCK) { task->thread.features_locked |=3D features; return 0; --=20 2.17.1