[PATCH 7.1.y 2/6] fuse-uring: refactor io-uring header copying from ring

[Sasha Levin <sashal@kernel.org>]

From: Joanne Koong <joannelkoong@gmail.com>

[ Upstream commit ba7d47897fd895533c19af436ca7fc4f6b171238 ]

Move header copying from ring logic into a new copy_header_from_ring()
function. This makes the copy_from_user() logic more clear and
centralizes error handling / rate-limited logging.

Reviewed-by: Bernd Schubert <bschubert@ddn.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Baokun Li <libaokun@linux.alibaba.com>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Stable-dep-of: fd10f40af314 ("fuse: copy request headers via a stack buffer for io-uring")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/fuse/dev_uring.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index df19a580c200a..6468a72de6644 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -587,6 +587,18 @@ static __always_inline int copy_header_to_ring(void __user *ring,
 	return 0;
 }
 
+static __always_inline int copy_header_from_ring(void *header,
+						 const void __user *ring,
+						 size_t header_size)
+{
+	if (copy_from_user(header, ring, header_size)) {
+		pr_info_ratelimited("Copying header from ring failed.\n");
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
 static int fuse_uring_copy_from_ring(struct fuse_ring *ring,
 				     struct fuse_req *req,
 				     struct fuse_ring_ent *ent)
@@ -597,10 +609,10 @@ static int fuse_uring_copy_from_ring(struct fuse_ring *ring,
 	int err;
 	struct fuse_uring_ent_in_out ring_in_out;
 
-	err = copy_from_user(&ring_in_out, &ent->headers->ring_ent_in_out,
-			     sizeof(ring_in_out));
+	err = copy_header_from_ring(&ring_in_out, &ent->headers->ring_ent_in_out,
+				    sizeof(ring_in_out));
 	if (err)
-		return -EFAULT;
+		return err;
 
 	err = import_ubuf(ITER_SOURCE, ent->payload, ring->max_payload_sz,
 			  &iter);
@@ -836,8 +848,8 @@ static void fuse_uring_commit(struct fuse_ring_ent *ent, struct fuse_req *req,
 	struct fuse_conn *fc = ring->fc;
 	ssize_t err = -EFAULT;
 
-	if (copy_from_user(&req->out.h, &ent->headers->in_out,
-			   sizeof(req->out.h)))
+	if (copy_header_from_ring(&req->out.h, &ent->headers->in_out,
+				  sizeof(req->out.h)))
 		goto out;
 
 	err = fuse_uring_out_header_has_err(&req->out.h, req, fc);
-- 
2.53.0