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Drivers: hv: vmbus: Restrict vmbus_devices on isolated guests

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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@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210201144814.2701-3-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Andrea Parri (Microsoft) 2021-02-01 15:48:12 +01:00 committed by Wei Liu
parent a6c76bb08d
commit 21a4e356d3
2 changed files with 39 additions and 0 deletions
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38
drivers/hv/channel_mgmt.c
View File

@ -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) {

1
include/linux/hyperv.h
View File

@ -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