linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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 5/5] arm64: compat: vdso: Use legacy syscalls as fallback
Date: Sun, 28 Jul 2019 16:35:44 +0100	[thread overview]
Message-ID: <68c3f5ca-6c38-4a82-4586-6b33fd54390a@arm.com> (raw)
In-Reply-To: <20190728131648.971361611@linutronix.de>

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 <vincenzo.frascino@arm.com>
Tested-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: 00b26474c2f1 ("lib/vdso: Provide generic VDSO implementation")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> 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

  reply	other threads:[~2019-07-28 15:34 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
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 [this message]
2019-07-30 22:22   ` [tip:timers/urgent] " tip-bot for Thomas Gleixner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=68c3f5ca-6c38-4a82-4586-6b33fd54390a@arm.com \
    --to=vincenzo.frascino@arm.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=pebolle@tiscali.nl \
    --cc=sean.j.christopherson@intel.com \
    --cc=tglx@linutronix.de \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    --subject='Re: [patch 5/5] arm64: compat: vdso: Use legacy syscalls as fallback' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox