Re: [PATCH] fanotify: do not allow setting FAN_RENAME on non-dir

[Matthew Bobrowski <repnop@google.com>]

On Fri, May 06, 2022 at 04:46:26AM +0300, Amir Goldstein wrote:
> The desired sematics of this action are not clear, so for now deny
> this action.  We may relax it when we decide on the semantics and
> implement them.
> 
> Fixes: 8cc3b1ccd930 ("fanotify: wire up FAN_RENAME event")
> Link: https://lore.kernel.org/linux-fsdevel/20220505133057.zm5t6vumc4xdcnsg@quack3.lan/
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Thanks for sending this patch through Amir, LGTM.

Feel free to add:

Reviewed-by: Matthew Bobrowski <repnop@google.com>

> ---
>  fs/notify/fanotify/fanotify_user.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index edad67d674dc..ae0c27fac651 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1695,6 +1695,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
>  	else
>  		mnt = path.mnt;
>  
> +	/* FAN_RENAME is not allowed on non-dir (for now) */
> +	ret = -EINVAL;
> +	if (inode && (mask & FAN_RENAME) && !S_ISDIR(inode->i_mode))
> +		goto path_put_and_out;
> +
>  	/* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */
>  	if (mnt || !S_ISDIR(inode->i_mode)) {
>  		mask &= ~FAN_EVENT_ON_CHILD;
> -- 
> 2.25.1

/M