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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 A793DC04E53 for ; Wed, 15 May 2019 12:05:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FEFD20657 for ; Wed, 15 May 2019 12:05:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557921908; bh=ljqYy/Z9kslG+EL17A7e1VuFNCzcXOpz/hNK9vQqN4c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mm6sy+zdzpTfUNfVtzDHaigQRZZWVOOwuGnNX/RpSc/RcKiL6aslu4X6Gr5Otws0F Dr2WTtZNs4reYNihwwtEi4auAbfS7MXJLBV2bxDx1LnRUrsU28zD3+V0U5ZNbwZ4uo aiFJdxnY4f62X0L9Bss8x4KXxpxx5nq2pTNddvpY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729525AbfEOMFH (ORCPT ); Wed, 15 May 2019 08:05:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:45678 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729151AbfEOLLQ (ORCPT ); Wed, 15 May 2019 07:11:16 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 824F52084E; Wed, 15 May 2019 11:11:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557918675; bh=ljqYy/Z9kslG+EL17A7e1VuFNCzcXOpz/hNK9vQqN4c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0PZdUtnkGqwEn977jz/63jrBz2xpjDWAaAMcUGbRuPhUXY5MxDWqVGScsUm3LcvRS hBb95l56JKl8lwgfLkhJtjYLCP5M+AsRZEqM09Aca+ovKgXUIvOatp1aXNgl30Fw/e b8WgwFYq55JwKsRbUoTOVSYQ4lL3mUXJY2B58kJM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tim Chen , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Andy Lutomirski , Linus Torvalds , Jiri Kosina , Tom Lendacky , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , Waiman Long , Dave Stewart , Kees Cook , Ben Hutchings Subject: [PATCH 4.4 223/266] x86/speculation: Add prctl() control for indirect branch speculation Date: Wed, 15 May 2019 12:55:30 +0200 Message-Id: <20190515090730.539243783@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090722.696531131@linuxfoundation.org> References: <20190515090722.696531131@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner commit 9137bb27e60e554dab694eafa4cca241fa3a694f upstream. Add the PR_SPEC_INDIRECT_BRANCH option for the PR_GET_SPECULATION_CTRL and PR_SET_SPECULATION_CTRL prctls to allow fine grained per task control of indirect branch speculation via STIBP and IBPB. Invocations: Check indirect branch speculation status with - prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, 0, 0, 0); Enable indirect branch speculation with - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_ENABLE, 0, 0); Disable indirect branch speculation with - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_DISABLE, 0, 0); Force disable indirect branch speculation with - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_FORCE_DISABLE, 0, 0); See Documentation/userspace-api/spec_ctrl.rst. Signed-off-by: Tim Chen Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Jiri Kosina Cc: Tom Lendacky Cc: Josh Poimboeuf Cc: Andrea Arcangeli Cc: David Woodhouse Cc: Andi Kleen Cc: Dave Hansen Cc: Casey Schaufler Cc: Asit Mallick Cc: Arjan van de Ven Cc: Jon Masters Cc: Waiman Long Cc: Greg KH Cc: Dave Stewart Cc: Kees Cook Link: https://lkml.kernel.org/r/20181125185005.866780996@linutronix.de [bwh: Backported to 4.4: - Renumber the PFA flags - Drop changes in tools/include/uapi/linux/prctl.h - Adjust filename] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- Documentation/spec_ctrl.txt | 9 ++++ arch/x86/include/asm/nospec-branch.h | 1 arch/x86/kernel/cpu/bugs.c | 67 +++++++++++++++++++++++++++++++++++ arch/x86/kernel/process.c | 5 ++ include/linux/sched.h | 9 ++++ include/uapi/linux/prctl.h | 1 6 files changed, 92 insertions(+) --- a/Documentation/spec_ctrl.txt +++ b/Documentation/spec_ctrl.txt @@ -92,3 +92,12 @@ Speculation misfeature controls * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_FORCE_DISABLE, 0, 0); + +- PR_SPEC_INDIR_BRANCH: Indirect Branch Speculation in User Processes + (Mitigate Spectre V2 style attacks against user processes) + + Invocations: + * prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, 0, 0, 0); + * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_ENABLE, 0, 0); + * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_DISABLE, 0, 0); + * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_FORCE_DISABLE, 0, 0); --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -178,6 +178,7 @@ enum spectre_v2_mitigation { enum spectre_v2_user_mitigation { SPECTRE_V2_USER_NONE, SPECTRE_V2_USER_STRICT, + SPECTRE_V2_USER_PRCTL, }; /* The Speculative Store Bypass disable variants */ --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -561,6 +561,8 @@ void arch_smt_update(void) case SPECTRE_V2_USER_STRICT: update_stibp_strict(); break; + case SPECTRE_V2_USER_PRCTL: + break; } mutex_unlock(&spec_ctrl_mutex); @@ -747,12 +749,50 @@ static int ssb_prctl_set(struct task_str return 0; } +static int ib_prctl_set(struct task_struct *task, unsigned long ctrl) +{ + switch (ctrl) { + case PR_SPEC_ENABLE: + if (spectre_v2_user == SPECTRE_V2_USER_NONE) + return 0; + /* + * Indirect branch speculation is always disabled in strict + * mode. + */ + if (spectre_v2_user == SPECTRE_V2_USER_STRICT) + return -EPERM; + task_clear_spec_ib_disable(task); + task_update_spec_tif(task); + break; + case PR_SPEC_DISABLE: + case PR_SPEC_FORCE_DISABLE: + /* + * Indirect branch speculation is always allowed when + * mitigation is force disabled. + */ + if (spectre_v2_user == SPECTRE_V2_USER_NONE) + return -EPERM; + if (spectre_v2_user == SPECTRE_V2_USER_STRICT) + return 0; + task_set_spec_ib_disable(task); + if (ctrl == PR_SPEC_FORCE_DISABLE) + task_set_spec_ib_force_disable(task); + task_update_spec_tif(task); + break; + default: + return -ERANGE; + } + return 0; +} + int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which, unsigned long ctrl) { switch (which) { case PR_SPEC_STORE_BYPASS: return ssb_prctl_set(task, ctrl); + case PR_SPEC_INDIRECT_BRANCH: + return ib_prctl_set(task, ctrl); default: return -ENODEV; } @@ -785,11 +825,34 @@ static int ssb_prctl_get(struct task_str } } +static int ib_prctl_get(struct task_struct *task) +{ + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) + return PR_SPEC_NOT_AFFECTED; + + switch (spectre_v2_user) { + case SPECTRE_V2_USER_NONE: + return PR_SPEC_ENABLE; + case SPECTRE_V2_USER_PRCTL: + if (task_spec_ib_force_disable(task)) + return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE; + if (task_spec_ib_disable(task)) + return PR_SPEC_PRCTL | PR_SPEC_DISABLE; + return PR_SPEC_PRCTL | PR_SPEC_ENABLE; + case SPECTRE_V2_USER_STRICT: + return PR_SPEC_DISABLE; + default: + return PR_SPEC_NOT_AFFECTED; + } +} + int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which) { switch (which) { case PR_SPEC_STORE_BYPASS: return ssb_prctl_get(task); + case PR_SPEC_INDIRECT_BRANCH: + return ib_prctl_get(task); default: return -ENODEV; } @@ -886,6 +949,8 @@ static char *stibp_state(void) return ", STIBP: disabled"; case SPECTRE_V2_USER_STRICT: return ", STIBP: forced"; + case SPECTRE_V2_USER_PRCTL: + return ""; } return ""; } @@ -898,6 +963,8 @@ static char *ibpb_state(void) return ", IBPB: disabled"; case SPECTRE_V2_USER_STRICT: return ", IBPB: always-on"; + case SPECTRE_V2_USER_PRCTL: + return ""; } } return ""; --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -372,6 +372,11 @@ static unsigned long speculation_ctrl_up set_tsk_thread_flag(tsk, TIF_SSBD); else clear_tsk_thread_flag(tsk, TIF_SSBD); + + if (task_spec_ib_disable(tsk)) + set_tsk_thread_flag(tsk, TIF_SPEC_IB); + else + clear_tsk_thread_flag(tsk, TIF_SPEC_IB); } /* Return the updated threadinfo flags*/ return task_thread_info(tsk)->flags; --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2169,6 +2169,8 @@ static inline void memalloc_noio_restore #define PFA_SPREAD_SLAB 2 /* Spread some slab caches over cpuset */ #define PFA_SPEC_SSB_DISABLE 4 /* Speculative Store Bypass disabled */ #define PFA_SPEC_SSB_FORCE_DISABLE 5 /* Speculative Store Bypass force disabled*/ +#define PFA_SPEC_IB_DISABLE 6 /* Indirect branch speculation restricted */ +#define PFA_SPEC_IB_FORCE_DISABLE 7 /* Indirect branch speculation permanently restricted */ #define TASK_PFA_TEST(name, func) \ @@ -2199,6 +2201,13 @@ TASK_PFA_CLEAR(SPEC_SSB_DISABLE, spec_ss TASK_PFA_TEST(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable) TASK_PFA_SET(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable) +TASK_PFA_TEST(SPEC_IB_DISABLE, spec_ib_disable) +TASK_PFA_SET(SPEC_IB_DISABLE, spec_ib_disable) +TASK_PFA_CLEAR(SPEC_IB_DISABLE, spec_ib_disable) + +TASK_PFA_TEST(SPEC_IB_FORCE_DISABLE, spec_ib_force_disable) +TASK_PFA_SET(SPEC_IB_FORCE_DISABLE, spec_ib_force_disable) + /* * task->jobctl flags */ --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -202,6 +202,7 @@ struct prctl_mm_map { #define PR_SET_SPECULATION_CTRL 53 /* Speculation control variants */ # define PR_SPEC_STORE_BYPASS 0 +# define PR_SPEC_INDIRECT_BRANCH 1 /* Return and control values for PR_SET/GET_SPECULATION_CTRL */ # define PR_SPEC_NOT_AFFECTED 0 # define PR_SPEC_PRCTL (1UL << 0)