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
next prev parent 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
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