227 lines
6.3 KiB
C
227 lines
6.3 KiB
C
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/*
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* VMware VMCI Driver
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*
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* Copyright (C) 2012 VMware, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation version 2 and no later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <linux/vmw_vmci_defs.h>
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#include <linux/vmw_vmci_api.h>
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#include "vmci_context.h"
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#include "vmci_driver.h"
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#include "vmci_route.h"
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/*
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* Make a routing decision for the given source and destination handles.
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* This will try to determine the route using the handles and the available
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* devices. Will set the source context if it is invalid.
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*/
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int vmci_route(struct vmci_handle *src,
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const struct vmci_handle *dst,
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bool from_guest,
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enum vmci_route *route)
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{
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bool has_host_device = vmci_host_code_active();
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bool has_guest_device = vmci_guest_code_active();
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*route = VMCI_ROUTE_NONE;
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/*
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* "from_guest" is only ever set to true by
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* IOCTL_VMCI_DATAGRAM_SEND (or by the vmkernel equivalent),
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* which comes from the VMX, so we know it is coming from a
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* guest.
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*
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* To avoid inconsistencies, test these once. We will test
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* them again when we do the actual send to ensure that we do
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* not touch a non-existent device.
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*/
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/* Must have a valid destination context. */
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if (VMCI_INVALID_ID == dst->context)
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return VMCI_ERROR_INVALID_ARGS;
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/* Anywhere to hypervisor. */
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if (VMCI_HYPERVISOR_CONTEXT_ID == dst->context) {
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/*
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* If this message already came from a guest then we
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* cannot send it to the hypervisor. It must come
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* from a local client.
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*/
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if (from_guest)
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return VMCI_ERROR_DST_UNREACHABLE;
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/*
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* We must be acting as a guest in order to send to
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* the hypervisor.
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*/
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if (!has_guest_device)
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return VMCI_ERROR_DEVICE_NOT_FOUND;
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/* And we cannot send if the source is the host context. */
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if (VMCI_HOST_CONTEXT_ID == src->context)
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return VMCI_ERROR_INVALID_ARGS;
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/*
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* If the client passed the ANON source handle then
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* respect it (both context and resource are invalid).
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* However, if they passed only an invalid context,
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* then they probably mean ANY, in which case we
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* should set the real context here before passing it
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* down.
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*/
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if (VMCI_INVALID_ID == src->context &&
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VMCI_INVALID_ID != src->resource)
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src->context = vmci_get_context_id();
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/* Send from local client down to the hypervisor. */
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*route = VMCI_ROUTE_AS_GUEST;
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return VMCI_SUCCESS;
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}
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/* Anywhere to local client on host. */
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if (VMCI_HOST_CONTEXT_ID == dst->context) {
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/*
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* If it is not from a guest but we are acting as a
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* guest, then we need to send it down to the host.
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* Note that if we are also acting as a host then this
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* will prevent us from sending from local client to
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* local client, but we accept that restriction as a
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* way to remove any ambiguity from the host context.
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*/
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if (src->context == VMCI_HYPERVISOR_CONTEXT_ID) {
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/*
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* If the hypervisor is the source, this is
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* host local communication. The hypervisor
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* may send vmci event datagrams to the host
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* itself, but it will never send datagrams to
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* an "outer host" through the guest device.
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*/
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if (has_host_device) {
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*route = VMCI_ROUTE_AS_HOST;
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return VMCI_SUCCESS;
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} else {
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return VMCI_ERROR_DEVICE_NOT_FOUND;
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}
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}
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if (!from_guest && has_guest_device) {
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/* If no source context then use the current. */
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if (VMCI_INVALID_ID == src->context)
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src->context = vmci_get_context_id();
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/* Send it from local client down to the host. */
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*route = VMCI_ROUTE_AS_GUEST;
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return VMCI_SUCCESS;
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}
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/*
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* Otherwise we already received it from a guest and
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* it is destined for a local client on this host, or
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* it is from another local client on this host. We
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* must be acting as a host to service it.
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*/
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if (!has_host_device)
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return VMCI_ERROR_DEVICE_NOT_FOUND;
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if (VMCI_INVALID_ID == src->context) {
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/*
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* If it came from a guest then it must have a
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* valid context. Otherwise we can use the
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* host context.
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*/
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if (from_guest)
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return VMCI_ERROR_INVALID_ARGS;
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src->context = VMCI_HOST_CONTEXT_ID;
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}
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/* Route to local client. */
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*route = VMCI_ROUTE_AS_HOST;
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return VMCI_SUCCESS;
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}
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/*
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* If we are acting as a host then this might be destined for
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* a guest.
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*/
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if (has_host_device) {
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/* It will have a context if it is meant for a guest. */
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if (vmci_ctx_exists(dst->context)) {
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if (VMCI_INVALID_ID == src->context) {
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/*
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* If it came from a guest then it
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* must have a valid context.
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* Otherwise we can use the host
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* context.
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*/
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if (from_guest)
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return VMCI_ERROR_INVALID_ARGS;
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src->context = VMCI_HOST_CONTEXT_ID;
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} else if (VMCI_CONTEXT_IS_VM(src->context) &&
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src->context != dst->context) {
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/*
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* VM to VM communication is not
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* allowed. Since we catch all
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* communication destined for the host
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* above, this must be destined for a
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* VM since there is a valid context.
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*/
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return VMCI_ERROR_DST_UNREACHABLE;
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}
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/* Pass it up to the guest. */
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*route = VMCI_ROUTE_AS_HOST;
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return VMCI_SUCCESS;
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} else if (!has_guest_device) {
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/*
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* The host is attempting to reach a CID
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* without an active context, and we can't
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* send it down, since we have no guest
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* device.
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*/
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return VMCI_ERROR_DST_UNREACHABLE;
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}
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}
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/*
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* We must be a guest trying to send to another guest, which means
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* we need to send it down to the host. We do not filter out VM to
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* VM communication here, since we want to be able to use the guest
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* driver on older versions that do support VM to VM communication.
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*/
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if (!has_guest_device) {
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/*
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* Ending up here means we have neither guest nor host
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* device.
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*/
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return VMCI_ERROR_DEVICE_NOT_FOUND;
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}
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/* If no source context then use the current context. */
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if (VMCI_INVALID_ID == src->context)
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src->context = vmci_get_context_id();
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/*
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* Send it from local client down to the host, which will
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* route it to the other guest for us.
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*/
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*route = VMCI_ROUTE_AS_GUEST;
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return VMCI_SUCCESS;
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}
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