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splice: move permission hook out of splice_file_to_pipe()

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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>
Link: https://lore.kernel.org/r/20231122122715.2561213-5-amir73il@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Amir Goldstein 2023-11-22 14:27:03 +02:00 committed by Christian Brauner
parent feebea75bd
commit b70d8e2b8c
1 changed files with 5 additions and 1 deletions
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6
fs/splice.c
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@ -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;