[RFC PATCH v6 14/22] virtio/vsock: rest of SOCK_SEQPACKET support

[Arseny Krasnov <arseny.krasnov@kaspersky.com>]

This adds rest of logic for SEQPACKET:
1) SEQPACKET specific functions which send SEQ_BEGIN/SEQ_END.
   Note that both functions may sleep to wait enough space for
   SEQPACKET header.
2) SEQ_BEGIN/SEQ_END in TAP packet capture.
3) Send SHUTDOWN on socket close for SEQPACKET type.
4) Set SEQPACKET packet type during send.
5) Set MSG_EOR in flags for SEQPACKET during send.
6) 'seqpacket_allow' flag to virtio transport.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 include/linux/virtio_vsock.h            |  8 +++
 net/vmw_vsock/virtio_transport_common.c | 87 ++++++++++++++++++++++++-
 2 files changed, 93 insertions(+), 2 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index d7edcfeb4cd2..6b45a8b98226 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -22,6 +22,7 @@ struct virtio_vsock_seqpack_state {
 	u32 user_read_seq_len;
 	u32 user_read_copied;
 	u32 curr_rx_msg_id;
+	u32 next_tx_msg_id;
 };
 
 /* Per-socket state (accessed via vsk->trans) */
@@ -76,6 +77,8 @@ struct virtio_transport {
 
 	/* Takes ownership of the packet */
 	int (*send_pkt)(struct virtio_vsock_pkt *pkt);
+
+	bool seqpacket_allow;
 };
 
 ssize_t
@@ -90,6 +93,11 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
 
 size_t virtio_transport_seqpacket_seq_get_len(struct vsock_sock *vsk);
 int
+virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   int flags,
+				   size_t len);
+int
 virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
 				   struct msghdr *msg,
 				   int flags,
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 9d86375935ce..8e9fdd8aba5d 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -139,6 +139,8 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
 		break;
 	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
 	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
+	case VIRTIO_VSOCK_OP_SEQ_BEGIN:
+	case VIRTIO_VSOCK_OP_SEQ_END:
 		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
 		break;
 	default:
@@ -187,7 +189,12 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
 	struct virtio_vsock_pkt *pkt;
 	u32 pkt_len = info->pkt_len;
 
-	info->type = VIRTIO_VSOCK_TYPE_STREAM;
+	info->type = virtio_transport_get_type(sk_vsock(vsk));
+
+	if (info->type == VIRTIO_VSOCK_TYPE_SEQPACKET &&
+	    info->msg &&
+	    info->msg->msg_flags & MSG_EOR)
+		info->flags |= VIRTIO_VSOCK_RW_EOR;
 
 	t_ops = virtio_transport_get_ops(vsk);
 	if (unlikely(!t_ops))
@@ -401,6 +408,43 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
 	return err;
 }
 
+static int virtio_transport_seqpacket_send_ctrl(struct vsock_sock *vsk,
+						int type,
+						size_t len,
+						int flags)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	struct virtio_vsock_pkt_info info = {
+		.op = type,
+		.vsk = vsk,
+		.pkt_len = sizeof(struct virtio_vsock_seq_hdr)
+	};
+
+	struct virtio_vsock_seq_hdr seq_hdr = {
+		.msg_id = cpu_to_le32(vvs->seqpacket_state.next_tx_msg_id),
+		.msg_len = cpu_to_le32(len)
+	};
+
+	struct kvec seq_hdr_kiov = {
+		.iov_base = (void *)&seq_hdr,
+		.iov_len = sizeof(struct virtio_vsock_seq_hdr)
+	};
+
+	struct msghdr msg = {0};
+
+	//XXX: do we need 'vsock_transport_send_notify_data' pointer?
+	if (vsock_wait_space(sk_vsock(vsk),
+			     sizeof(struct virtio_vsock_seq_hdr),
+			     flags, NULL))
+		return -1;
+
+	iov_iter_kvec(&msg.msg_iter, WRITE, &seq_hdr_kiov, 1, sizeof(seq_hdr));
+
+	info.msg = &msg;
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
 static inline void virtio_transport_remove_pkt(struct virtio_vsock_pkt *pkt)
 {
 	list_del(&pkt->list);
@@ -582,6 +626,45 @@ virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
 }
 EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
 
+int
+virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   int flags,
+				   size_t len)
+{
+	int written;
+
+	if (msg->msg_iter.iov_offset == 0) {
+		/* Send SEQBEGIN. */
+		if (virtio_transport_seqpacket_send_ctrl(vsk,
+							 VIRTIO_VSOCK_OP_SEQ_BEGIN,
+							 len,
+							 flags) < 0)
+			return -1;
+	}
+
+	written = virtio_transport_stream_enqueue(vsk, msg, len);
+
+	if (written < 0)
+		return -1;
+
+	if (msg->msg_iter.count == 0) {
+		struct virtio_vsock_sock *vvs = vsk->trans;
+
+		/* Send SEQEND. */
+		if (virtio_transport_seqpacket_send_ctrl(vsk,
+							 VIRTIO_VSOCK_OP_SEQ_END,
+							 0,
+							 flags) < 0)
+			return -1;
+
+		vvs->seqpacket_state.next_tx_msg_id++;
+	}
+
+	return written;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
+
 int
 virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
 			       struct msghdr *msg,
@@ -1001,7 +1084,7 @@ void virtio_transport_release(struct vsock_sock *vsk)
 	struct sock *sk = &vsk->sk;
 	bool remove_sock = true;
 
-	if (sk->sk_type == SOCK_STREAM)
+	if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
 		remove_sock = virtio_transport_close(vsk);
 
 	list_for_each_entry_safe(pkt, tmp, &vvs->rx_queue, list) {
-- 
2.25.1