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Message-ID: <MWHPR21MB1593C3DF86DB6B15628F2D67D7B69@MWHPR21MB1593.namprd21.prod.outlook.com>
Date: Mon, 1 Feb 2021 17:46:50 +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>
Subject: RE: [PATCH v3 hyperv-next 2/4] Drivers: hv: vmbus: Restrict
vmbus_devices on isolated guests
From: Andrea Parri (Microsoft) <parri.andrea@...il.com> Sent: Monday, February 1, 2021 6:48 AM
>
> Only the VSCs or ICs that have been hardened and that are critical for
> the successful adoption of Confidential VMs should be allowed if the
> guest is running isolated. This change 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>
> ---
> drivers/hv/channel_mgmt.c | 38 ++++++++++++++++++++++++++++++++++++++
> include/linux/hyperv.h | 1 +
> 2 files changed, 39 insertions(+)
>
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index 68950a1e4b638..f0ed730e2e4e4 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -31,101 +31,118 @@ const struct vmbus_device vmbus_devs[] = {
> { .dev_type = HV_IDE,
> HV_IDE_GUID,
> .perf_device = true,
> + .allowed_in_isolated = false,
> },
>
> /* SCSI */
> { .dev_type = HV_SCSI,
> HV_SCSI_GUID,
> .perf_device = true,
> + .allowed_in_isolated = true,
> },
>
> /* Fibre Channel */
> { .dev_type = HV_FC,
> HV_SYNTHFC_GUID,
> .perf_device = true,
> + .allowed_in_isolated = false,
> },
>
> /* Synthetic NIC */
> { .dev_type = HV_NIC,
> HV_NIC_GUID,
> .perf_device = true,
> + .allowed_in_isolated = true,
> },
>
> /* Network Direct */
> { .dev_type = HV_ND,
> HV_ND_GUID,
> .perf_device = true,
> + .allowed_in_isolated = false,
> },
>
> /* PCIE */
> { .dev_type = HV_PCIE,
> HV_PCIE_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Synthetic Frame Buffer */
> { .dev_type = HV_FB,
> HV_SYNTHVID_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Synthetic Keyboard */
> { .dev_type = HV_KBD,
> HV_KBD_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Synthetic MOUSE */
> { .dev_type = HV_MOUSE,
> HV_MOUSE_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* KVP */
> { .dev_type = HV_KVP,
> HV_KVP_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Time Synch */
> { .dev_type = HV_TS,
> HV_TS_GUID,
> .perf_device = false,
> + .allowed_in_isolated = true,
> },
>
> /* Heartbeat */
> { .dev_type = HV_HB,
> HV_HEART_BEAT_GUID,
> .perf_device = false,
> + .allowed_in_isolated = true,
> },
>
> /* Shutdown */
> { .dev_type = HV_SHUTDOWN,
> HV_SHUTDOWN_GUID,
> .perf_device = false,
> + .allowed_in_isolated = true,
> },
>
> /* File copy */
> { .dev_type = HV_FCOPY,
> HV_FCOPY_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Backup */
> { .dev_type = HV_BACKUP,
> HV_VSS_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Dynamic Memory */
> { .dev_type = HV_DM,
> HV_DM_GUID,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
>
> /* Unknown GUID */
> { .dev_type = HV_UNKNOWN,
> .perf_device = false,
> + .allowed_in_isolated = false,
> },
> };
>
> @@ -903,6 +920,20 @@ find_primary_channel_by_offer(const struct
> vmbus_channel_offer_channel *offer)
> return channel;
> }
>
> +static bool vmbus_is_valid_device(const guid_t *guid)
> +{
> + u16 i;
> +
> + if (!hv_is_isolation_supported())
> + return true;
> +
> + for (i = 0; i < ARRAY_SIZE(vmbus_devs); i++) {
> + if (guid_equal(guid, &vmbus_devs[i].guid))
> + return vmbus_devs[i].allowed_in_isolated;
> + }
> + return false;
> +}
> +
> /*
> * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.
> *
> @@ -917,6 +948,13 @@ static void vmbus_onoffer(struct
> vmbus_channel_message_header *hdr)
>
> trace_vmbus_onoffer(offer);
>
> + if (!vmbus_is_valid_device(&offer->offer.if_type)) {
> + pr_err_ratelimited("Invalid offer %d from the host supporting isolation\n",
> + offer->child_relid);
> + atomic_dec(&vmbus_connection.offer_in_progress);
> + return;
> + }
> +
> oldchannel = find_primary_channel_by_offer(offer);
>
> if (oldchannel != NULL) {
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index f0d48a368f131..e3426f8c12db9 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -789,6 +789,7 @@ struct vmbus_device {
> u16 dev_type;
> guid_t guid;
> bool perf_device;
> + bool allowed_in_isolated;
> };
>
> #define VMBUS_DEFAULT_MAX_PKT_SIZE 4096
> --
> 2.25.1
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
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