From nobody Sun Sep 14 18:15:08 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 EB159C71133 for ; Thu, 19 Jan 2023 21:42:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230361AbjASVmk (ORCPT ); Thu, 19 Jan 2023 16:42:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230092AbjASViK (ORCPT ); Thu, 19 Jan 2023 16:38:10 -0500 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 036F24ABC2; Thu, 19 Jan 2023 13:27:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674163673; x=1705699673; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=vY8qQFdDU3u0a0tvehCZCS7MwIYptOrO+eN8SXLOirs=; b=gQkrwrQ4Dn6lvzoLLIOoZj6nwoj2pw+qVTv02bXHhd7Ix3u3k+bemd5x rU+E9ClBPy78ZtArP0KQsxrnzNb6tTAHA9Y/SEKAlWK9koXLa5HXJbPGi qWxbgBmvMelkQn8oKtx+j8iN0sBZHhD06SowEv5I0JbSIOxjEa+y4Y3sH AQX9ilJQHkJpUpRfLXZnbFTL70uf5vUsxV54O04OjTILRJCU6gH4bafYi MUrsUq68uyoDsLTYQMnRGXhze0S940xweCwcmJs6sfe5DfdDOSO18tyte 9sb7unTi272m62rH+56a7SC4OP9ONC/0X8o88JBaqoNBAb9sQrwVaMrfF A==; X-IronPort-AV: E=McAfee;i="6500,9779,10595"; a="323119970" X-IronPort-AV: E=Sophos;i="5.97,230,1669104000"; d="scan'208";a="323119970" 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 13:24:17 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10595"; a="989139169" X-IronPort-AV: E=Sophos;i="5.97,230,1669104000"; d="scan'208";a="989139169" 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 13:24:16 -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 33/39] x86: Expose thread features in /proc/$PID/status Date: Thu, 19 Jan 2023 13:23:11 -0800 Message-Id: <20230119212317.8324-34-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230119212317.8324-1-rick.p.edgecombe@intel.com> References: <20230119212317.8324-1-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Applications and loaders can have logic to decide whether to enable shadow stack. They usually don't report whether shadow stack has been enabled or not, so there is no way to verify whether an application actually is protected by shadow stack. Add two lines in /proc/$PID/status to report enabled and locked features. Since, this involves referring to arch specific defines in asm/prctl.h, implement an arch breakout to emit the feature lines. Reviewed-by: Kees Cook Tested-by: Pengfei Xu Tested-by: John Allen Signed-off-by: Kirill A. Shutemov [Switched to CET, added to commit log] Signed-off-by: Rick Edgecombe --- v4: - Remove "CET" references v3: - Move to /proc/pid/status (Kees) v2: - New patch arch/x86/kernel/cpu/proc.c | 23 +++++++++++++++++++++++ fs/proc/array.c | 6 ++++++ include/linux/proc_fs.h | 2 ++ 3 files changed, 31 insertions(+) diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c index 099b6f0d96bd..31c0e68f6227 100644 --- a/arch/x86/kernel/cpu/proc.c +++ b/arch/x86/kernel/cpu/proc.c @@ -4,6 +4,8 @@ #include #include #include +#include +#include =20 #include "cpu.h" =20 @@ -175,3 +177,24 @@ const struct seq_operations cpuinfo_op =3D { .stop =3D c_stop, .show =3D show_cpuinfo, }; + +#ifdef CONFIG_X86_USER_SHADOW_STACK +static void dump_x86_features(struct seq_file *m, unsigned long features) +{ + if (features & ARCH_SHSTK_SHSTK) + seq_puts(m, "shstk "); + if (features & ARCH_SHSTK_WRSS) + seq_puts(m, "wrss "); +} + +void arch_proc_pid_thread_features(struct seq_file *m, struct task_struct = *task) +{ + seq_puts(m, "x86_Thread_features:\t"); + dump_x86_features(m, task->thread.features); + seq_putc(m, '\n'); + + seq_puts(m, "x86_Thread_features_locked:\t"); + dump_x86_features(m, task->thread.features_locked); + seq_putc(m, '\n'); +} +#endif /* CONFIG_X86_USER_SHADOW_STACK */ diff --git a/fs/proc/array.c b/fs/proc/array.c index 49283b8103c7..7ac43ecda1c2 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -428,6 +428,11 @@ static inline void task_thp_status(struct seq_file *m,= struct mm_struct *mm) seq_printf(m, "THP_enabled:\t%d\n", thp_enabled); } =20 +__weak void arch_proc_pid_thread_features(struct seq_file *m, + struct task_struct *task) +{ +} + int proc_pid_status(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { @@ -451,6 +456,7 @@ int proc_pid_status(struct seq_file *m, struct pid_name= space *ns, task_cpus_allowed(m, task); cpuset_task_status_allowed(m, task); task_context_switch_counts(m, task); + arch_proc_pid_thread_features(m, task); return 0; } =20 diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 0260f5ea98fe..80ff8e533cbd 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -158,6 +158,8 @@ int proc_pid_arch_status(struct seq_file *m, struct pid= _namespace *ns, struct pid *pid, struct task_struct *task); #endif /* CONFIG_PROC_PID_ARCH_STATUS */ =20 +void arch_proc_pid_thread_features(struct seq_file *m, struct task_struct = *task); + #else /* CONFIG_PROC_FS */ =20 static inline void proc_root_init(void) --=20 2.17.1