linux-kernel - RE: [PATCH v3 hyperv-next 4/4] hv_netvsc: Restrict configurations on isolated guests

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Message-ID: <MWHPR21MB1593CB2AA09DA302FA2EC5D0D7B69@MWHPR21MB1593.namprd21.prod.outlook.com>
Date:   Mon, 1 Feb 2021 17:48:55 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     "Andrea Parri (Microsoft)" <parri.andrea@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        Saruhan Karademir <skarade@...rosoft.com>,
        Juan Vazquez <juvazq@...rosoft.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH v3 hyperv-next 4/4] hv_netvsc: Restrict configurations on
 isolated guests

From: Andrea Parri (Microsoft) <parri.andrea@...il.com> Sent: Monday, February 1, 2021 6:48 AM
> 
> 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@...il.com>
> Acked-by: Jakub Kicinski <kuba@...nel.org>
> Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: netdev@...r.kernel.org
> ---
>  drivers/net/hyperv/netvsc.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 1510a236aa341..51005f2d4a821 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 +545,10 @@ 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;
>  	}
>  }
> --
> 2.25.1

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>