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From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Kees Cook <keescook@chromium.org>,
	Paul Bolle <pebolle@tiscali.nl>, Will Deacon <will@kernel.org>
Subject: Re: [patch 4/5] x86/vdso/32: Use 32bit syscall fallback
Date: Mon, 29 Jul 2019 12:23:03 +0100	[thread overview]
Message-ID: <3baf0efb-dcae-4953-66aa-06c5ee9fbdf7@arm.com> (raw)
In-Reply-To: <20190728131648.879156507@linutronix.de>

On 28/07/2019 14:12, 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 <vincenzo.frascino@arm.com>

> Reported-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Reported-by: Paul Bolle <pebolle@tiscali.nl>
> Suggested-by: Andy Lutomirski <luto@kernel.org>
> Fixes: 7ac870747988 ("x86/vdso: Switch to generic vDSO implementation")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  arch/x86/include/asm/vdso/gettimeofday.h |   36 +++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> --- a/arch/x86/include/asm/vdso/gettimeofday.h
> +++ b/arch/x86/include/asm/vdso/gettimeofday.h
> @@ -96,6 +96,8 @@ long clock_getres_fallback(clockid_t _cl
>  
>  #else
>  
> +#define VDSO_HAS_32BIT_FALLBACK	1
> +
>  static __always_inline
>  long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
>  {
> @@ -114,6 +116,23 @@ long clock_gettime_fallback(clockid_t _c
>  }
>  
>  static __always_inline
> +long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
> +{
> +	long ret;
> +
> +	asm (
> +		"mov %%ebx, %%edx \n"
> +		"mov %[clock], %%ebx \n"
> +		"call __kernel_vsyscall \n"
> +		"mov %%edx, %%ebx \n"
> +		: "=a" (ret), "=m" (*_ts)
> +		: "0" (__NR_clock_gettime), [clock] "g" (_clkid), "c" (_ts)
> +		: "edx");
> +
> +	return ret;
> +}
> +
> +static __always_inline
>  long gettimeofday_fallback(struct __kernel_old_timeval *_tv,
>  			   struct timezone *_tz)
>  {
> @@ -146,6 +165,23 @@ clock_getres_fallback(clockid_t _clkid,
>  		: "edx");
>  
>  	return ret;
> +}
> +
> +static __always_inline
> +long clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
> +{
> +	long ret;
> +
> +	asm (
> +		"mov %%ebx, %%edx \n"
> +		"mov %[clock], %%ebx \n"
> +		"call __kernel_vsyscall \n"
> +		"mov %%edx, %%ebx \n"
> +		: "=a" (ret), "=m" (*_ts)
> +		: "0" (__NR_clock_getres), [clock] "g" (_clkid), "c" (_ts)
> +		: "edx");
> +
> +	return ret;
>  }
>  
>  #endif
> 
> 

-- 
Regards,
Vincenzo

  parent reply	other threads:[~2019-07-29 11:23 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-28 13:12 [patch 0/5] lib/vdso, x86/vdso: Fix fallout from generic VDSO conversion Thomas Gleixner
2019-07-28 13:12 ` [patch 1/5] lib/vdso/32: Remove inconsistent NULL pointer checks Thomas Gleixner
2019-07-28 14:33   ` Andy Lutomirski
2019-07-28 14:42     ` Thomas Gleixner
2019-07-28 15:30   ` Vincenzo Frascino
2019-07-29 14:52   ` Sean Christopherson
2019-07-30 22:19   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 2/5] lib/vdso: Move fallback invocation to the callers Thomas Gleixner
2019-07-28 14:37   ` Andy Lutomirski
2019-07-28 15:31   ` Vincenzo Frascino
2019-07-30 22:19   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 3/5] lib/vdso/32: Provide legacy syscall fallbacks Thomas Gleixner
2019-07-28 14:39   ` Andy Lutomirski
2019-07-28 15:33   ` Vincenzo Frascino
2019-07-29 14:48   ` Sean Christopherson
2019-07-30  9:38     ` [patch V2 " Thomas Gleixner
2019-07-30 14:28       ` Sean Christopherson
2019-07-30 20:09       ` Andy Lutomirski
2019-07-30 20:14         ` Thomas Gleixner
2019-07-30 22:20       ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 4/5] x86/vdso/32: Use 32bit syscall fallback Thomas Gleixner
2019-07-28 14:50   ` Andy Lutomirski
2019-07-29 11:23   ` Vincenzo Frascino [this message]
2019-07-29 14:51   ` Sean Christopherson
2019-07-30 22:21   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2019-07-28 13:12 ` [patch 5/5] arm64: compat: vdso: Use legacy syscalls as fallback Thomas Gleixner
2019-07-28 15:35   ` Vincenzo Frascino
2019-07-30 22:22   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner

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