diff mbox series

[v2,02/16] splice: remove permission hook from do_splice_direct()

Message ID 20231122122715.2561213-3-amir73il@gmail.com (mailing list archive)
State New, archived
Headers show
Series Tidy up file permission hooks | expand

Commit Message

Amir Goldstein Nov. 22, 2023, 12:27 p.m. UTC
All callers of do_splice_direct() have a call to rw_verify_area() for
the entire range that is being copied, e.g. by vfs_copy_file_range() or
do_sendfile() before calling do_splice_direct().

The rw_verify_area() check inside do_splice_direct() is redundant and
is called after sb_start_write(), so it is not "start-write-safe".
Remove this redundant check.

This is needed for fanotify "pre content" events.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/splice.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

Comments

Christoph Hellwig Nov. 23, 2023, 7:36 a.m. UTC | #1
Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
Jan Kara Nov. 23, 2023, 4:28 p.m. UTC | #2
On Wed 22-11-23 14:27:01, Amir Goldstein wrote:
> All callers of do_splice_direct() have a call to rw_verify_area() for
> the entire range that is being copied, e.g. by vfs_copy_file_range() or
> do_sendfile() before calling do_splice_direct().
> 
> The rw_verify_area() check inside do_splice_direct() is redundant and
> is called after sb_start_write(), so it is not "start-write-safe".
> Remove this redundant check.
> 
> 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 | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index d983d375ff11..6e917db6f49a 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -1166,6 +1166,7 @@ static void direct_file_splice_eof(struct splice_desc *sd)
>   *    (splice in + splice out, as compared to just sendfile()). So this helper
>   *    can splice directly through a process-private pipe.
>   *
> + * Callers already called rw_verify_area() on the entire range.
>   */
>  long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
>  		      loff_t *opos, size_t len, unsigned int flags)
> @@ -1187,10 +1188,6 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
>  	if (unlikely(out->f_flags & O_APPEND))
>  		return -EINVAL;
>  
> -	ret = rw_verify_area(WRITE, out, opos, len);
> -	if (unlikely(ret < 0))
> -		return ret;
> -
>  	ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
>  	if (ret > 0)
>  		*ppos = sd.pos;
> -- 
> 2.34.1
>
diff mbox series

Patch

diff --git a/fs/splice.c b/fs/splice.c
index d983d375ff11..6e917db6f49a 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1166,6 +1166,7 @@  static void direct_file_splice_eof(struct splice_desc *sd)
  *    (splice in + splice out, as compared to just sendfile()). So this helper
  *    can splice directly through a process-private pipe.
  *
+ * Callers already called rw_verify_area() on the entire range.
  */
 long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
 		      loff_t *opos, size_t len, unsigned int flags)
@@ -1187,10 +1188,6 @@  long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
 	if (unlikely(out->f_flags & O_APPEND))
 		return -EINVAL;
 
-	ret = rw_verify_area(WRITE, out, opos, len);
-	if (unlikely(ret < 0))
-		return ret;
-
 	ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
 	if (ret > 0)
 		*ppos = sd.pos;