From nobody Sun Feb 8 22:58:17 2026 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 3E86CC7EE43 for ; Tue, 13 Jun 2023 00:20:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239183AbjFMAUr (ORCPT ); Mon, 12 Jun 2023 20:20:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239447AbjFMASa (ORCPT ); Mon, 12 Jun 2023 20:18:30 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AC003C1B; Mon, 12 Jun 2023 17:14:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686615273; x=1718151273; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=MIQ1pWvE/RoBE8pKawMdEBQM6Q57ao+KDpsn7QGopL8=; b=QQ9X1yvEzmGzuyIHxFih972HlZMFv/ydI62a38WGtKVXsRctmlFgC+kM x3p9Z6E/pTCwhwVTuvamy4j4G5YxtLsz00mec9bkGVisvezERjAE41ny4 LnBYVirsMrB0DN3IDKRm22i45rN9qc/Y2JUBNq/5hNTr6sNIeHfk9tykd Keztd6faDV/GqJ9qKUFLDM1Mw/KdMEmTpX+m6yqxoYYq8r6jceUZSSkzN Ym0hnGOxRLue5gmD9IRkNGRu6SecQmNMWoc70nxt8a748hJK03HgC4Elz kjamzrkpqYdlaas38sZCXKCHBKh1A7IJh7U3cIQXp/cvip05wXKS5fGPE A==; X-IronPort-AV: E=McAfee;i="6600,9927,10739"; a="361557660" X-IronPort-AV: E=Sophos;i="6.00,238,1681196400"; d="scan'208";a="361557660" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jun 2023 17:12:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10739"; a="835671189" X-IronPort-AV: E=Sophos;i="6.00,238,1681196400"; d="scan'208";a="835671189" Received: from almeisch-mobl1.amr.corp.intel.com (HELO rpedgeco-desk4.amr.corp.intel.com) ([10.209.42.242]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jun 2023 17:12:43 -0700 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, david@redhat.com, debug@rivosinc.com, szabolcs.nagy@arm.com, torvalds@linux-foundation.org, broonie@kernel.org Cc: rick.p.edgecombe@intel.com, Pengfei Xu Subject: [PATCH v9 42/42] x86/shstk: Add ARCH_SHSTK_STATUS Date: Mon, 12 Jun 2023 17:11:08 -0700 Message-Id: <20230613001108.3040476-43-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230613001108.3040476-1-rick.p.edgecombe@intel.com> References: <20230613001108.3040476-1-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Suggested-by: Mike Rapoport Signed-off-by: Rick Edgecombe Reviewed-by: Borislav Petkov (AMD) Reviewed-by: Kees Cook Acked-by: Mike Rapoport (IBM) Tested-by: Pengfei Xu Tested-by: John Allen Tested-by: Kees Cook --- Documentation/arch/x86/shstk.rst | 6 ++++++ arch/x86/include/asm/shstk.h | 2 +- arch/x86/include/uapi/asm/prctl.h | 1 + arch/x86/kernel/process_64.c | 1 + arch/x86/kernel/shstk.c | 8 +++++++- 5 files changed, 16 insertions(+), 2 deletions(-) diff --git a/Documentation/arch/x86/shstk.rst b/Documentation/arch/x86/shst= k.rst index f3553cc8c758..60260e809baf 100644 --- a/Documentation/arch/x86/shstk.rst +++ b/Documentation/arch/x86/shstk.rst @@ -79,6 +79,11 @@ 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 @@ -86,6 +91,7 @@ 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 ecb23a8ca47d..42fee8959df7 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); unsigned long shstk_alloc_thread_stack(struct task_struct *p, unsigned lon= g clone_flags, unsigned long stack_size); diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/= prctl.h index 3189c4a96468..384e2cc6ac19 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -34,6 +34,7 @@ #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 e6db21c470aa..33b268747bb7 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -900,6 +900,7 @@ 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 d43b7a9c57ce..b26810c7cd1c 100644 --- a/arch/x86/kernel/shstk.c +++ b/arch/x86/kernel/shstk.c @@ -482,8 +482,14 @@ 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 2.34.1