Michael Kelley (LINUX)
2022-Apr-15 03:33 UTC
[RFC PATCH 2/6] hv_sock: Copy packets sent by Hyper-V out of the ring buffer
From: Andrea Parri (Microsoft) <parri.andrea at gmail.com> Sent: Wednesday, April 13, 2022 1:48 PM> > Pointers to VMbus packets sent by Hyper-V are used by the hv_sock driver > within the gues VM. Hyper-V can send packets with erroneous values ors/gues/guest/> modify packet fields after they are processed by the guest. To defend > against these scenarios, copy the incoming packet after validating its > length and offset fields using hv_pkt_iter_{first,next}(). In this way, > the packet can no longer be modified by the host. > > Signed-off-by: Andrea Parri (Microsoft) <parri.andrea at gmail.com> > --- > net/vmw_vsock/hyperv_transport.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c > index 943352530936e..8c37d07017fc4 100644 > --- a/net/vmw_vsock/hyperv_transport.c > +++ b/net/vmw_vsock/hyperv_transport.c > @@ -78,6 +78,9 @@ struct hvs_send_buf { > ALIGN((payload_len), 8) + \ > VMBUS_PKT_TRAILER_SIZE) > > +/* Upper bound on the size of a VMbus packet for hv_sock */ > +#define HVS_MAX_PKT_SIZE HVS_PKT_LEN(HVS_MTU_SIZE) > + > union hvs_service_id { > guid_t srv_id; > > @@ -378,6 +381,8 @@ static void hvs_open_connection(struct vmbus_channel *chan) > rcvbuf = ALIGN(rcvbuf, HV_HYP_PAGE_SIZE); > } > > + chan->max_pkt_size = HVS_MAX_PKT_SIZE; > + > ret = vmbus_open(chan, sndbuf, rcvbuf, NULL, 0, hvs_channel_cb, > conn_from_host ? new : sk); > if (ret != 0) { > @@ -602,7 +607,7 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, > return -EOPNOTSUPP; > > if (need_refill) { > - hvs->recv_desc = hv_pkt_iter_first_raw(hvs->chan); > + hvs->recv_desc = hv_pkt_iter_first(hvs->chan); > if (!hvs->recv_desc) > return -ENOBUFS; > ret = hvs_update_recv_data(hvs); > @@ -618,7 +623,7 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, > struct msghdr *msg, > > hvs->recv_data_len -= to_read; > if (hvs->recv_data_len == 0) { > - hvs->recv_desc = hv_pkt_iter_next_raw(hvs->chan, hvs->recv_desc); > + hvs->recv_desc = hv_pkt_iter_next(hvs->chan, hvs->recv_desc); > if (hvs->recv_desc) { > ret = hvs_update_recv_data(hvs); > if (ret) > -- > 2.25.1