io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly

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>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f41d91ce1fd0482a620605c984c5613422f48d50..a70de170aea11f2f4831ed98d9709e964babf6a8 100644 (file)
--- 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 +5418,21 @@ 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 bool io_net_retry(struct socket *sock, int flags)
+{
+       if (!(flags & MSG_WAITALL))
+               return false;
+       return sock->type == SOCK_STREAM || sock->type == SOCK_SEQPACKET;
+}
+
 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 +5475,10 @@ 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 && io_net_retry(sock, flags)) {
+                       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 +5488,10 @@ 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 +5542,22 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
                        return -EAGAIN;
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
+               if (ret > 0 && io_net_retry(sock, flags)) {
+                       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;
 }