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// SPDX-License-Identifier: GPL-2.0-only
/*
* VMware VMCI Driver
*
* Copyright (C) 2012 VMware, Inc. All rights reserved.
*/
#include <linux/vmw_vmci_defs.h>
#include <linux/vmw_vmci_api.h>
#include "vmci_context.h"
#include "vmci_driver.h"
#include "vmci_route.h"
/*
* Make a routing decision for the given source and destination handles.
* This will try to determine the route using the handles and the available
* devices. Will set the source context if it is invalid.
*/
int vmci_route(struct vmci_handle *src,
const struct vmci_handle *dst,
bool from_guest,
enum vmci_route *route)
{
bool has_host_device = vmci_host_code_active();
bool has_guest_device = vmci_guest_code_active();
*route = VMCI_ROUTE_NONE;
/*
* "from_guest" is only ever set to true by
* IOCTL_VMCI_DATAGRAM_SEND (or by the vmkernel equivalent),
* which comes from the VMX, so we know it is coming from a
* guest.
*
* To avoid inconsistencies, test these once. We will test
* them again when we do the actual send to ensure that we do
* not touch a non-existent device.
*/
/* Must have a valid destination context. */
if (VMCI_INVALID_ID == dst->context)
return VMCI_ERROR_INVALID_ARGS;
/* Anywhere to hypervisor. */
if (VMCI_HYPERVISOR_CONTEXT_ID == dst->context) {
/*
* If this message already came from a guest then we
* cannot send it to the hypervisor. It must come
* from a local client.
*/
if (from_guest)
return VMCI_ERROR_DST_UNREACHABLE;
/*
* We must be acting as a guest in order to send to
* the hypervisor.
*/
if (!has_guest_device)
return VMCI_ERROR_DEVICE_NOT_FOUND;
/* And we cannot send if the source is the host context. */
if (VMCI_HOST_CONTEXT_ID == src->context)
return VMCI_ERROR_INVALID_ARGS;
/*
* If the client passed the ANON source handle then
* respect it (both context and resource are invalid).
* However, if they passed only an invalid context,
* then they probably mean ANY, in which case we
* should set the real context here before passing it
* down.
*/
if (VMCI_INVALID_ID == src->context &&
VMCI_INVALID_ID != src->resource)
src->context = vmci_get_context_id();
/* Send from local client down to the hypervisor. */
*route = VMCI_ROUTE_AS_GUEST;
return VMCI_SUCCESS;
}
/* Anywhere to local client on host. */
if (VMCI_HOST_CONTEXT_ID == dst->context) {
/*
* If it is not from a guest but we are acting as a
* guest, then we need to send it down to the host.
* Note that if we are also acting as a host then this
* will prevent us from sending from local client to
* local client, but we accept that restriction as a
* way to remove any ambiguity from the host context.
*/
if (src->context == VMCI_HYPERVISOR_CONTEXT_ID) {
/*
* If the hypervisor is the source, this is
* host local communication. The hypervisor
* may send vmci event datagrams to the host
* itself, but it will never send datagrams to
* an "outer host" through the guest device.
*/
if (has_host_device) {
*route = VMCI_ROUTE_AS_HOST;
return VMCI_SUCCESS;
} else {
return VMCI_ERROR_DEVICE_NOT_FOUND;
}
}
if (!from_guest && has_guest_device) {
/* If no source context then use the current. */
if (VMCI_INVALID_ID == src->context)
src->context = vmci_get_context_id();
/* Send it from local client down to the host. */
*route = VMCI_ROUTE_AS_GUEST;
return VMCI_SUCCESS;
}
/*
* Otherwise we already received it from a guest and
* it is destined for a local client on this host, or
* it is from another local client on this host. We
* must be acting as a host to service it.
*/
if (!has_host_device)
return VMCI_ERROR_DEVICE_NOT_FOUND;
if (VMCI_INVALID_ID == src->context) {
/*
* If it came from a guest then it must have a
* valid context. Otherwise we can use the
* host context.
*/
if (from_guest)
return VMCI_ERROR_INVALID_ARGS;
src->context = VMCI_HOST_CONTEXT_ID;
}
/* Route to local client. */
*route = VMCI_ROUTE_AS_HOST;
return VMCI_SUCCESS;
}
/*
* If we are acting as a host then this might be destined for
* a guest.
*/
if (has_host_device) {
/* It will have a context if it is meant for a guest. */
if (vmci_ctx_exists(dst->context)) {
if (VMCI_INVALID_ID == src->context) {
/*
* If it came from a guest then it
* must have a valid context.
* Otherwise we can use the host
* context.
*/
if (from_guest)
return VMCI_ERROR_INVALID_ARGS;
src->context = VMCI_HOST_CONTEXT_ID;
} else if (VMCI_CONTEXT_IS_VM(src->context) &&
src->context != dst->context) {
/*
* VM to VM communication is not
* allowed. Since we catch all
* communication destined for the host
* above, this must be destined for a
* VM since there is a valid context.
*/
return VMCI_ERROR_DST_UNREACHABLE;
}
/* Pass it up to the guest. */
*route = VMCI_ROUTE_AS_HOST;
return VMCI_SUCCESS;
} else if (!has_guest_device) {
/*
* The host is attempting to reach a CID
* without an active context, and we can't
* send it down, since we have no guest
* device.
*/
return VMCI_ERROR_DST_UNREACHABLE;
}
}
/*
* We must be a guest trying to send to another guest, which means
* we need to send it down to the host. We do not filter out VM to
* VM communication here, since we want to be able to use the guest
* driver on older versions that do support VM to VM communication.
*/
if (!has_guest_device) {
/*
* Ending up here means we have neither guest nor host
* device.
*/
return VMCI_ERROR_DEVICE_NOT_FOUND;
}
/* If no source context then use the current context. */
if (VMCI_INVALID_ID == src->context)
src->context = vmci_get_context_id();
/*
* Send it from local client down to the host, which will
* route it to the other guest for us.
*/
*route = VMCI_ROUTE_AS_GUEST;
return VMCI_SUCCESS;
}
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