Commit ae6fcfbf authored by Stefano Garzarella's avatar Stefano Garzarella Committed by David S. Miller
Browse files

vsock/virtio: discard packets if credit is not respected 



If the remote peer doesn't respect the credit information
(buf_alloc, fwd_cnt), sending more data than it can send,
we should drop the packets to prevent a malicious peer
from using all of our memory.

This is patch follows the VIRTIO spec: "VIRTIO_VSOCK_OP_RW data
packets MUST only be transmitted when the peer has sufficient
free buffer space for the payload"

Signed-off-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ec3359b6

net/vmw_vsock/virtio_transport_common.c

+11 −3
Original line number Diff line number Diff line
@@ -204,10 +204,14 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, 
	return virtio_transport_get_ops()->send_pkt(pkt);

}



static void virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,

static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,

					struct virtio_vsock_pkt *pkt)

{

	if (vvs->rx_bytes + pkt->len > vvs->buf_alloc)

		return false;



	vvs->rx_bytes += pkt->len;

	return true;

}



static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
@@ -879,14 +883,18 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk, 
			      struct virtio_vsock_pkt *pkt)

{

	struct virtio_vsock_sock *vvs = vsk->trans;

	bool free_pkt = false;

	bool can_enqueue, free_pkt = false;



	pkt->len = le32_to_cpu(pkt->hdr.len);

	pkt->off = 0;



	spin_lock_bh(&vvs->rx_lock);



	virtio_transport_inc_rx_pkt(vvs, pkt);

	can_enqueue = virtio_transport_inc_rx_pkt(vvs, pkt);

	if (!can_enqueue) {

		free_pkt = true;

		goto out;

	}



	/* Try to copy small packets into the buffer of last packet queued,

	 * to avoid wasting memory queueing the entire buffer with a small

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