This is a note to let you know that I've just added the patch titled
fs: check FMODE_LSEEK to control internal pipe splicing
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-check-fmode_lseek-to-control-internal-pipe-splici.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 42eb7ea9b9b0285baaa106cba62df51bfda33647
Author: Jason A. Donenfeld <Jason@xxxxxxxxx>
Date: Wed Jun 29 15:06:58 2022 +0200
fs: check FMODE_LSEEK to control internal pipe splicing
[ Upstream commit 97ef77c52b789ec1411d360ed99dca1efe4b2c81 ]
The original direct splicing mechanism from Jens required the input to
be a regular file because it was avoiding the special socket case. It
also recognized blkdevs as being close enough to a regular file. But it
forgot about chardevs, which behave the same way and work fine here.
This is an okayish heuristic, but it doesn't totally work. For example,
a few chardevs should be spliceable here. And a few regular files
shouldn't. This patch fixes this by instead checking whether FMODE_LSEEK
is set, which represents decently enough what we need rewinding for when
splicing to internal pipes.
Fixes: b92ce5589374 ("[PATCH] splice: add direct fd <-> fd splicing support")
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/splice.c b/fs/splice.c
index fd28c7da3c83..ef1604e307f1 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -899,17 +899,15 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
{
struct pipe_inode_info *pipe;
long ret, bytes;
- umode_t i_mode;
size_t len;
int i, flags, more;
/*
- * We require the input being a regular file, as we don't want to
- * randomly drop data for eg socket -> socket splicing. Use the
- * piped splicing for that!
+ * We require the input to be seekable, as we don't want to randomly
+ * drop data for eg socket -> socket splicing. Use the piped splicing
+ * for that!
*/
- i_mode = file_inode(in)->i_mode;
- if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
+ if (unlikely(!(in->f_mode & FMODE_LSEEK)))
return -EINVAL;
/*
