Re: [PATCH 01/13] y2038: cobalt: Introduce some itimerspec64 related helpers

[Jan Kiszka <jan.kiszka@siemens.com>]

On 08.05.23 10:13, Florian Bezdeka wrote:
> The introduced helpers will be used by the timer and timerfd y2038
> related services for reading/writing itimerspec from/to userspace.
> 
> Signed-off-by: Florian Bezdeka <florian.bezdeka@siemens.com>
> ---
>  include/cobalt/kernel/time.h | 21 +++++++++++++++++++++
>  kernel/cobalt/time.c         | 38 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 59 insertions(+)
> 
> diff --git a/include/cobalt/kernel/time.h b/include/cobalt/kernel/time.h
> index a55398068..e348cf9b8 100644
> --- a/include/cobalt/kernel/time.h
> +++ b/include/cobalt/kernel/time.h
> @@ -28,4 +28,25 @@ int cobalt_get_timespec64(struct timespec64 *ts,
>  int cobalt_put_timespec64(const struct timespec64 *ts,
>  			  struct __kernel_timespec __user *uts);
>  
> +/**
> + * Read struct __kernel_itimerspec from userspace and convert to
> + * struct itimerspec64
> + *
> + * @param dst The destination, will be filled
> + * @param src The source, provided by an application
> + * @return 0 on success, -EFAULT otherwise
> + */
> +int cobalt_get_itimerspec64(struct itimerspec64 *dst,
> +			    const struct __kernel_itimerspec __user *src);
> +
> +/**
> + * Convert struct itimerspec64 to struct __kernel_itimerspec and copy to user
> + * space
> + * @param dst The destination, will be filled, provided by an application
> + * @param src The source, provided by the kernel
> + * @return 0 un success, -EFAULT otherwise
> + */
> +int cobalt_put_itimerspec64(struct __kernel_itimerspec __user *dst,
> +			    const struct itimerspec64 *src);
> +
>  #endif //_COBALT_KERNEL_TIME_H
> diff --git a/kernel/cobalt/time.c b/kernel/cobalt/time.c
> index 27dbf8290..716223dc5 100644
> --- a/kernel/cobalt/time.c
> +++ b/kernel/cobalt/time.c
> @@ -36,3 +36,41 @@ int cobalt_put_timespec64(const struct timespec64 *ts,
>  
>  	return cobalt_copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
>  }
> +
> +int cobalt_get_itimerspec64(struct itimerspec64 *dst,
> +			    const struct __kernel_itimerspec __user *src)
> +{
> +	struct timespec64 interval, value;
> +	int ret;
> +
> +	if (!src)

Can that be enough to validate the pointer? Or is it even needed? We
must validate it via cobalt_get_timespec64 anyway, no?

> +		return -EFAULT;
> +
> +	ret = cobalt_get_timespec64(&interval, &src->it_interval);
> +	if (ret)
> +		return ret;
> +
> +	ret = cobalt_get_timespec64(&value, &src->it_value);
> +	if (ret)
> +		return ret;
> +
> +	dst->it_interval.tv_sec = interval.tv_sec;
> +	dst->it_interval.tv_nsec = interval.tv_nsec;
> +	dst->it_value.tv_sec = value.tv_sec;
> +	dst->it_value.tv_nsec = value.tv_nsec;
> +
> +	return 0;
> +}
> +
> +int cobalt_put_itimerspec64(struct __kernel_itimerspec __user *dst,
> +			    const struct itimerspec64 *src)
> +{
> +	struct __kernel_itimerspec kits = {
> +		.it_interval.tv_sec = src->it_interval.tv_sec,
> +		.it_interval.tv_nsec = src->it_interval.tv_nsec,
> +		.it_value.tv_sec = src->it_value.tv_sec,
> +		.it_value.tv_nsec = src->it_value.tv_nsec
> +	};
> +
> +	return cobalt_copy_to_user(dst, &kits, sizeof(kits));
> +}
> 

Jan

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