[PATCH 1/2] io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly

Jens Axboe
2022-03-23T15:39:55Z

We currently don't attempt to get the full asked for length even if
MSG_WAITALL is set, if we get a partial receive. If we do see a partial
receive, then just note how many bytes we did and return -EAGAIN to
get it retried.

The iov is advanced appropriately for the vector based case, and we
manually bump the buffer and remainder for the non-vector case.

Cc: stable@vger.kernel.org
Reported-by: Constantine Gavrilov <constantine.gavrilov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f41d91ce1fd0..2cd67b4ff924 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -612,6 +612,7 @@ struct io_sr_msg {
int msg_flags;
int bgid;
size_t len;
+ size_t done_io;
};

struct io_open {
@@ -5417,12 +5418,14 @@ static int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (req->ctx->compat)
sr->msg_flags |= MSG_CMSG_COMPAT;
#endif
+ sr->done_io = 0;
return 0;
}

static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_async_msghdr iomsg, *kmsg;
+ struct io_sr_msg *sr = &req->sr_msg;
struct socket *sock;
struct io_buffer *kbuf;
unsigned flags;
@@ -5465,6 +5468,10 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
return io_setup_async_msg(req, kmsg);
if (ret == -ERESTARTSYS)
ret = -EINTR;
+ if (ret > 0 && flags & MSG_WAITALL) {
+ sr->done_io += ret;
+ return io_setup_async_msg(req, kmsg);
+ }
req_set_fail(req);
} else if ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
req_set_fail(req);
@@ -5474,6 +5481,10 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
if (kmsg->free_iov)
kfree(kmsg->free_iov);
req->flags &= ~REQ_F_NEED_CLEANUP;
+ if (ret >= 0)
+ ret += sr->done_io;
+ else if (sr->done_io)
+ ret = sr->done_io;
__io_req_complete(req, issue_flags, ret, io_put_kbuf(req, issue_flags));
return 0;
}
@@ -5524,12 +5535,22 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
return -EAGAIN;
if (ret == -ERESTARTSYS)
ret = -EINTR;
+ if (ret > 0 && flags & MSG_WAITALL) {
+ sr->len -= ret;
+ sr->buf += ret;
+ sr->done_io += ret;
+ return -EAGAIN;
+ }
req_set_fail(req);
} else if ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
out_free:
req_set_fail(req);
}

+ if (ret >= 0)
+ ret += sr->done_io;
+ else if (sr->done_io)
+ ret = sr->done_io;
__io_req_complete(req, issue_flags, ret, io_put_kbuf(req, issue_flags));
return 0;
}
--
2.35.1