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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 863FCC433E2 for ; Mon, 7 Sep 2020 10:26:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 498A421481 for ; Mon, 7 Sep 2020 10:26:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728509AbgIGK03 (ORCPT ); Mon, 7 Sep 2020 06:26:29 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:59727 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728721AbgIGKQX (ORCPT ); Mon, 7 Sep 2020 06:16:23 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kFECA-0005WP-VQ; Mon, 07 Sep 2020 10:16:19 +0000 Date: Mon, 7 Sep 2020 12:16:18 +0200 From: Christian Brauner To: Gabriel Krisman Bertazi Cc: luto@kernel.org, tglx@linutronix.de, keescook@chromium.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, willy@infradead.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, kernel@collabora.com Subject: Re: [PATCH v6 2/9] kernel: entry: Support TIF_SYSCAL_INTERCEPT on common entry code Message-ID: <20200907101618.dnxv5n4x4vty73hr@wittgenstein> References: <20200904203147.2908430-1-krisman@collabora.com> <20200904203147.2908430-3-krisman@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200904203147.2908430-3-krisman@collabora.com> Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Fri, Sep 04, 2020 at 04:31:40PM -0400, Gabriel Krisman Bertazi wrote: > Syscalls that use common entry code (x86 at the moment of this writing) > need to have their defines updated inside this commit. This added a > measureable overhead of 1ns to seccomp_benchmark selftests on a > bare-metal AMD system. > > Signed-off-by: Gabriel Krisman Bertazi > --- > arch/x86/include/asm/thread_info.h | 4 ++-- > include/linux/entry-common.h | 6 +----- > kernel/entry/common.c | 24 +++++++++++++++++++++--- > 3 files changed, 24 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h > index 267701ae3d86..cf723181e1f2 100644 > --- a/arch/x86/include/asm/thread_info.h > +++ b/arch/x86/include/asm/thread_info.h > @@ -82,7 +82,7 @@ struct thread_info { > #define TIF_SSBD 5 /* Speculative store bypass disable */ > #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ > #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ > -#define TIF_SECCOMP 8 /* secure computing */ > +#define TIF_SYSCALL_INTERCEPT 8 /* Intercept system call */ > #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */ > #define TIF_SPEC_FORCE_UPDATE 10 /* Force speculation MSR update in context switch */ > #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ > @@ -112,7 +112,7 @@ struct thread_info { > #define _TIF_SSBD (1 << TIF_SSBD) > #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) > #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) > -#define _TIF_SECCOMP (1 << TIF_SECCOMP) > +#define _TIF_SYSCALL_INTERCEPT (1 << TIF_SYSCALL_INTERCEPT) > #define _TIF_SPEC_IB (1 << TIF_SPEC_IB) > #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) > #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index efebbffcd5cc..72ce9ca860c6 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -21,10 +21,6 @@ > # define _TIF_SYSCALL_TRACEPOINT (0) > #endif > > -#ifndef _TIF_SECCOMP > -# define _TIF_SECCOMP (0) > -#endif > - > #ifndef _TIF_SYSCALL_AUDIT > # define _TIF_SYSCALL_AUDIT (0) > #endif > @@ -45,7 +41,7 @@ > #endif > > #define SYSCALL_ENTER_WORK \ > - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \ > + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_INTERCEPT | \ > _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \ > ARCH_SYSCALL_ENTER_WORK) > > diff --git a/kernel/entry/common.c b/kernel/entry/common.c > index fcae019158ca..44fd089d59da 100644 > --- a/kernel/entry/common.c > +++ b/kernel/entry/common.c > @@ -4,6 +4,7 @@ > #include > #include > #include > +#include > > #define CREATE_TRACE_POINTS > #include > @@ -41,6 +42,20 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) > } > } > > +static inline long do_syscall_intercept(struct pt_regs *regs) Hey Gabriel, I think you can drop the pt_regs argument and just have this be static inline do_syscall_intercept(void) otherwise Acked-by: Christian Brauner > +{ > + int sysint_work = READ_ONCE(current->syscall_intercept); > + int ret; > + > + if (sysint_work & SYSINT_SECCOMP) { > + ret = __secure_computing(NULL); > + if (ret == -1L) > + return ret; > + } > + > + return 0; > +} > + > static long syscall_trace_enter(struct pt_regs *regs, long syscall, > unsigned long ti_work) > { > @@ -53,9 +68,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, > return -1L; > } > > - /* Do seccomp after ptrace, to catch any tracer changes. */ > - if (ti_work & _TIF_SECCOMP) { > - ret = __secure_computing(NULL); > + /* > + * Do syscall interception like seccomp after ptrace, to catch > + * any tracer changes. > + */ > + if (ti_work & _TIF_SYSCALL_INTERCEPT) { > + ret = do_syscall_intercept(regs); > if (ret == -1L) > return ret; > } > -- > 2.28.0