hv_netvsc: Restrict configurations on isolated guests

Restrict the NVSP protocol version(s) that will be negotiated with the
host to be NVSP_PROTOCOL_VERSION_61 or greater if the guest is running
isolated.  Moreover, do not advertise the SR-IOV capability and ignore
NVSP_MSG_4_TYPE_SEND_VF_ASSOCIATION messages in isolated guests, which
are not supposed to support SR-IOV.  This reduces the footprint of the
code that will be exercised by Confidential VMs and hence the exposure
to bugs and vulnerabilities.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210201144814.2701-5-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 1510a23..51005f2 100644 (file)
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -22,6 +22,7 @@
 #include <linux/prefetch.h>
 
 #include <asm/sync_bitops.h>
+#include <asm/mshyperv.h>
 
 #include "hyperv_net.h"
 #include "netvsc_trace.h"
@@ -544,7 +545,10 @@ static int negotiate_nvsp_ver(struct hv_device *device,
        init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1;
 
        if (nvsp_ver >= NVSP_PROTOCOL_VERSION_5) {
-               init_packet->msg.v2_msg.send_ndis_config.capability.sriov = 1;
+               if (hv_is_isolation_supported())
+                       netdev_info(ndev, "SR-IOV not advertised by guests on the host supporting isolation\n");
+               else
+                       init_packet->msg.v2_msg.send_ndis_config.capability.sriov = 1;
 
                /* Teaming bit is needed to receive link speed updates */
                init_packet->msg.v2_msg.send_ndis_config.capability.teaming = 1;
@@ -591,6 +595,13 @@ static int netvsc_connect_vsp(struct hv_device *device,
                goto cleanup;
        }
 
+       if (hv_is_isolation_supported() && net_device->nvsp_version < NVSP_PROTOCOL_VERSION_61) {
+               netdev_err(ndev, "Invalid NVSP version 0x%x (expected >= 0x%x) from the host supporting isolation\n",
+                          net_device->nvsp_version, NVSP_PROTOCOL_VERSION_61);
+               ret = -EPROTO;
+               goto cleanup;
+       }
+
        pr_debug("Negotiated NVSP version:%x\n", net_device->nvsp_version);
 
        /* Send the ndis version */
@@ -1357,7 +1368,10 @@ static void netvsc_receive_inband(struct net_device *ndev,
                break;
 
        case NVSP_MSG4_TYPE_SEND_VF_ASSOCIATION:
-               netvsc_send_vf(ndev, nvmsg, msglen);
+               if (hv_is_isolation_supported())
+                       netdev_err(ndev, "Ignore VF_ASSOCIATION msg from the host supporting isolation\n");
+               else
+                       netvsc_send_vf(ndev, nvmsg, msglen);
                break;
        }
 }