RE: [PATCH 4/4] hv_netvsc: Restrict configurations on isolated guests

-----Original Message-----
From: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Sent: Tuesday, January 19, 2021 12:59 PM
To: linux-kernel@vger.kernel.org
Cc: KY Srinivasan <kys@microsoft.com>; Haiyang Zhang
[off-list ref]; Stephen Hemminger
[off-list ref]; Wei Liu [off-list ref]; Michael Kelley
[off-list ref]; Tianyu Lan [off-list ref];
Saruhan Karademir [off-list ref]; Juan Vazquez
[off-list ref]; linux-hyperv@vger.kernel.org; Andrea Parri
(Microsoft) [off-list ref]; David S. Miller
[off-list ref]; Jakub Kicinski [off-list ref];
netdev@vger.kernel.org
Subject: [PATCH 4/4] 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>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
---
 drivers/net/hyperv/netvsc.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 1510a236aa341..8027d553cb67d 100644
--- 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 +545,8 @@ 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())
+			init_packet-

quoted

msg.v2_msg.send_ndis_config.capability.sriov = 1;

 		/* Teaming bit is needed to receive link speed updates */
 		init_packet-

quoted

msg.v2_msg.send_ndis_config.capability.teaming = 1;

@@ -563,6 +565,13 @@ static int negotiate_nvsp_ver(struct hv_device

*device,
 	return ret;
 }

+static bool nvsp_is_valid_version(u32 version)
+{
+       if (hv_is_isolation_supported())
+               return version >= NVSP_PROTOCOL_VERSION_61;
+       return true;

+}
+
 static int netvsc_connect_vsp(struct hv_device *device,
 			      struct netvsc_device *net_device,
 			      const struct netvsc_device_info *device_info)

@@ -579,12 +588,17 @@ static int netvsc_connect_vsp(struct hv_device

*device,
 	init_packet = &net_device->channel_init_pkt;

 	/* Negotiate the latest NVSP protocol supported */
-	for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--)
+	for (i = ARRAY_SIZE(ver_list) - 1; i >= 0; i--) {
+		if (!nvsp_is_valid_version(ver_list[i])) {
+			ret = -EPROTO;
+			goto cleanup;
+		}

 		if (negotiate_nvsp_ver(device, net_device, init_packet,
 				       ver_list[i])  == 0) {
 			net_device->nvsp_version = ver_list[i];
 			break;
 		}
+	}

 	if (i < 0) {
 		ret = -EPROTO;

@@ -1357,7 +1371,8 @@ 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())
+			netvsc_send_vf(ndev, nvmsg, msglen);