Re: [PATCH v2 04/16] splice: move permission hook out of splice_file_to_pipe()

[Jan Kara <jack@suse.cz>]

On Wed 22-11-23 14:27:03, Amir Goldstein wrote:
> vfs_splice_read() has a permission hook inside rw_verify_area() and
> it is called from splice_file_to_pipe(), which is called from
> do_splice() and do_sendfile().
> 
> do_sendfile() already has a rw_verify_area() check for the entire range.
> do_splice() has a rw_verify_check() for the splice to file case, not for
> the splice from file case.
> 
> Add the rw_verify_area() check for splice from file case in do_splice()
> and use a variant of vfs_splice_read() without rw_verify_area() check
> in splice_file_to_pipe() to avoid the redundant rw_verify_area() checks.
> 
> This is needed for fanotify "pre content" events.
> 
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/splice.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index 6fc2c27e9520..d4fdd44c0b32 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -1239,7 +1239,7 @@ long splice_file_to_pipe(struct file *in,
>  	pipe_lock(opipe);
>  	ret = wait_for_space(opipe, flags);
>  	if (!ret)
> -		ret = vfs_splice_read(in, offset, opipe, len, flags);
> +		ret = do_splice_read(in, offset, opipe, len, flags);
>  	pipe_unlock(opipe);
>  	if (ret > 0)
>  		wakeup_pipe_readers(opipe);
> @@ -1316,6 +1316,10 @@ long do_splice(struct file *in, loff_t *off_in, struct file *out,
>  			offset = in->f_pos;
>  		}
>  
> +		ret = rw_verify_area(READ, in, &offset, len);
> +		if (unlikely(ret < 0))
> +			return ret;
> +
>  		if (out->f_flags & O_NONBLOCK)
>  			flags |= SPLICE_F_NONBLOCK;
>  
> -- 
> 2.34.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR