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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 19D22C7618B for ; Sun, 28 Jul 2019 15:34:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED3602087C for ; Sun, 28 Jul 2019 15:34:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726178AbfG1Pef (ORCPT ); Sun, 28 Jul 2019 11:34:35 -0400 Received: from foss.arm.com ([217.140.110.172]:33594 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726067AbfG1Pef (ORCPT ); Sun, 28 Jul 2019 11:34:35 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 59211344; Sun, 28 Jul 2019 08:34:34 -0700 (PDT) Received: from [10.37.12.40] (unknown [10.37.12.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0E3663F71F; Sun, 28 Jul 2019 08:34:32 -0700 (PDT) Subject: Re: [patch 5/5] arm64: compat: vdso: Use legacy syscalls as fallback To: Thomas Gleixner , LKML Cc: x86@kernel.org, Andy Lutomirski , Sean Christopherson , Kees Cook , Paul Bolle , Will Deacon References: <20190728131251.622415456@linutronix.de> <20190728131648.971361611@linutronix.de> From: Vincenzo Frascino Message-ID: <68c3f5ca-6c38-4a82-4586-6b33fd54390a@arm.com> Date: Sun, 28 Jul 2019 16:35:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190728131648.971361611@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/28/19 2:12 PM, Thomas Gleixner wrote: > The generic VDSO implementation uses the Y2038 safe clock_gettime64() and > clock_getres_time64() syscalls as fallback for 32bit VDSO. This breaks > seccomp setups because these syscalls might be not (yet) allowed. > > Implement the 32bit variants which use the legacy syscalls and select the > variant in the core library. > > The 64bit time variants are not removed because they are required for the > time64 based vdso accessors. > Reviewed-by: Vincenzo Frascino Tested-by: Vincenzo Frascino > Reported-by: Sean Christopherson > Reported-by: Paul Bolle > Suggested-by: Andy Lutomirski > Fixes: 00b26474c2f1 ("lib/vdso: Provide generic VDSO implementation") > Signed-off-by: Thomas Gleixner > --- > Note: > > The NULL pointer check in the getres/getres32() fallbacks is just wrong. > The proper return code for a NULL pointer is -EFAULT. How did this ever > pass any posix test? Also it just should go away because any other invalid > pointer will be caught in the syscall anyway. The clockid check is also > part of the syscall so no point in having it here again. Handling calls > with invalid arguments is not really a performance critical operation. > > --- > arch/arm64/include/asm/vdso/compat_gettimeofday.h | 40 ++++++++++++++++++++++ > 1 file changed, 40 insertions(+) > > --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h > +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h > @@ -16,6 +16,8 @@ > > #define VDSO_HAS_CLOCK_GETRES 1 > > +#define VDSO_HAS_32BIT_FALLBACK 1 > + > static __always_inline > int gettimeofday_fallback(struct __kernel_old_timeval *_tv, > struct timezone *_tz) > @@ -52,6 +54,23 @@ long clock_gettime_fallback(clockid_t _c > } > > static __always_inline > +long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) > +{ > + register struct old_timespec32 *ts asm("r1") = _ts; > + register clockid_t clkid asm("r0") = _clkid; > + register long ret asm ("r0"); > + register long nr asm("r7") = __NR_compat_clock_gettime; > + > + asm volatile( > + " swi #0\n" > + : "=r" (ret) > + : "r" (clkid), "r" (ts), "r" (nr) > + : "memory"); > + > + return ret; > +} > + > +static __always_inline > int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) > { > register struct __kernel_timespec *ts asm("r1") = _ts; > @@ -61,6 +80,27 @@ int clock_getres_fallback(clockid_t _clk > > /* The checks below are required for ABI consistency with arm */ > if ((_clkid >= MAX_CLOCKS) && (_ts == NULL)) > + return -EINVAL; > + > + asm volatile( > + " swi #0\n" > + : "=r" (ret) > + : "r" (clkid), "r" (ts), "r" (nr) > + : "memory"); > + > + return ret; > +} > + > +static __always_inline > +int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) > +{ > + register struct old_timespec32 *ts asm("r1") = _ts; > + register clockid_t clkid asm("r0") = _clkid; > + register long ret asm ("r0"); > + register long nr asm("r7") = __NR_compat_clock_getres; > + > + /* The checks below are required for ABI consistency with arm */ > + if ((_clkid >= MAX_CLOCKS) && (_ts == NULL)) > return -EINVAL; > > asm volatile( > > -- Regards, Vincenzo