Re: [PATCH 1/3] inotify: Provide function for name length rounding

[Jan Kara <jack@suse.cz>]

On Fri 22-11-13 00:36:57, Jan Kara wrote:
> Rounding of name length when passing it to userspace was done in several
> places. Provide a function to do it and use it in all places.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
  Ping? Any opinion on this patchset?

								Honza

> ---
>  fs/notify/inotify/inotify_user.c | 41 ++++++++++++++++++++--------------------
>  1 file changed, 21 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
> index 60f954a891ab..1bb6dc8eaf1c 100644
> --- a/fs/notify/inotify/inotify_user.c
> +++ b/fs/notify/inotify/inotify_user.c
> @@ -124,6 +124,13 @@ static unsigned int inotify_poll(struct file *file, poll_table *wait)
>  	return ret;
>  }
>  
> +static int round_event_name_len(struct fsnotify_event *event)
> +{
> +	if (!event->name_len)
> +		return 0;
> +	return roundup(event->name_len + 1, sizeof(struct inotify_event));
> +}
> +
>  /*
>   * Get an inotify_kernel_event if one exists and is small
>   * enough to fit in "count". Return an error pointer if
> @@ -144,9 +151,7 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
>  
>  	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
>  
> -	if (event->name_len)
> -		event_size += roundup(event->name_len + 1, event_size);
> -
> +	event_size += round_event_name_len(event);
>  	if (event_size > count)
>  		return ERR_PTR(-EINVAL);
>  
> @@ -171,7 +176,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
>  	struct fsnotify_event_private_data *fsn_priv;
>  	struct inotify_event_private_data *priv;
>  	size_t event_size = sizeof(struct inotify_event);
> -	size_t name_len = 0;
> +	size_t name_len;
> +	size_t pad_name_len;
>  
>  	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
>  
> @@ -189,14 +195,13 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
>  		inotify_free_event_priv(fsn_priv);
>  	}
>  
> +	name_len = event->name_len;
>  	/*
> -	 * round up event->name_len so it is a multiple of event_size
> +	 * round up name length so it is a multiple of event_size
>  	 * plus an extra byte for the terminating '\0'.
>  	 */
> -	if (event->name_len)
> -		name_len = roundup(event->name_len + 1, event_size);
> -	inotify_event.len = name_len;
> -
> +	pad_name_len = round_event_name_len(event);
> +	inotify_event.len = pad_name_len;
>  	inotify_event.mask = inotify_mask_to_arg(event->mask);
>  	inotify_event.cookie = event->sync_cookie;
>  
> @@ -209,20 +214,18 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
>  	/*
>  	 * fsnotify only stores the pathname, so here we have to send the pathname
>  	 * and then pad that pathname out to a multiple of sizeof(inotify_event)
> -	 * with zeros.  I get my zeros from the nul_inotify_event.
> +	 * with zeros.
>  	 */
> -	if (name_len) {
> -		unsigned int len_to_zero = name_len - event->name_len;
> +	if (pad_name_len) {
>  		/* copy the path name */
> -		if (copy_to_user(buf, event->file_name, event->name_len))
> +		if (copy_to_user(buf, event->file_name, name_len))
>  			return -EFAULT;
> -		buf += event->name_len;
> +		buf += name_len;
>  
>  		/* fill userspace with 0's */
> -		if (clear_user(buf, len_to_zero))
> +		if (clear_user(buf, pad_name_len - name_len))
>  			return -EFAULT;
> -		buf += len_to_zero;
> -		event_size += name_len;
> +		event_size += pad_name_len;
>  	}
>  
>  	return event_size;
> @@ -314,9 +317,7 @@ static long inotify_ioctl(struct file *file, unsigned int cmd,
>  		list_for_each_entry(holder, &group->notification_list, event_list) {
>  			event = holder->event;
>  			send_len += sizeof(struct inotify_event);
> -			if (event->name_len)
> -				send_len += roundup(event->name_len + 1,
> -						sizeof(struct inotify_event));
> +			send_len += round_event_name_len(event);
>  		}
>  		mutex_unlock(&group->notification_mutex);
>  		ret = put_user(send_len, (int __user *) p);
> -- 
> 1.8.1.4
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR