219 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * VMware VMCI Driver4 *5 * Copyright (C) 2012 VMware, Inc. All rights reserved.6 */7 8#include <linux/vmw_vmci_defs.h>9#include <linux/vmw_vmci_api.h>10 11#include "vmci_context.h"12#include "vmci_driver.h"13#include "vmci_route.h"14 15/*16 * Make a routing decision for the given source and destination handles.17 * This will try to determine the route using the handles and the available18 * devices. Will set the source context if it is invalid.19 */20int vmci_route(struct vmci_handle *src,21 const struct vmci_handle *dst,22 bool from_guest,23 enum vmci_route *route)24{25 bool has_host_device = vmci_host_code_active();26 bool has_guest_device = vmci_guest_code_active();27 28 *route = VMCI_ROUTE_NONE;29 30 /*31 * "from_guest" is only ever set to true by32 * IOCTL_VMCI_DATAGRAM_SEND (or by the vmkernel equivalent),33 * which comes from the VMX, so we know it is coming from a34 * guest.35 *36 * To avoid inconsistencies, test these once. We will test37 * them again when we do the actual send to ensure that we do38 * not touch a non-existent device.39 */40 41 /* Must have a valid destination context. */42 if (VMCI_INVALID_ID == dst->context)43 return VMCI_ERROR_INVALID_ARGS;44 45 /* Anywhere to hypervisor. */46 if (VMCI_HYPERVISOR_CONTEXT_ID == dst->context) {47 48 /*49 * If this message already came from a guest then we50 * cannot send it to the hypervisor. It must come51 * from a local client.52 */53 if (from_guest)54 return VMCI_ERROR_DST_UNREACHABLE;55 56 /*57 * We must be acting as a guest in order to send to58 * the hypervisor.59 */60 if (!has_guest_device)61 return VMCI_ERROR_DEVICE_NOT_FOUND;62 63 /* And we cannot send if the source is the host context. */64 if (VMCI_HOST_CONTEXT_ID == src->context)65 return VMCI_ERROR_INVALID_ARGS;66 67 /*68 * If the client passed the ANON source handle then69 * respect it (both context and resource are invalid).70 * However, if they passed only an invalid context,71 * then they probably mean ANY, in which case we72 * should set the real context here before passing it73 * down.74 */75 if (VMCI_INVALID_ID == src->context &&76 VMCI_INVALID_ID != src->resource)77 src->context = vmci_get_context_id();78 79 /* Send from local client down to the hypervisor. */80 *route = VMCI_ROUTE_AS_GUEST;81 return VMCI_SUCCESS;82 }83 84 /* Anywhere to local client on host. */85 if (VMCI_HOST_CONTEXT_ID == dst->context) {86 /*87 * If it is not from a guest but we are acting as a88 * guest, then we need to send it down to the host.89 * Note that if we are also acting as a host then this90 * will prevent us from sending from local client to91 * local client, but we accept that restriction as a92 * way to remove any ambiguity from the host context.93 */94 if (src->context == VMCI_HYPERVISOR_CONTEXT_ID) {95 /*96 * If the hypervisor is the source, this is97 * host local communication. The hypervisor98 * may send vmci event datagrams to the host99 * itself, but it will never send datagrams to100 * an "outer host" through the guest device.101 */102 103 if (has_host_device) {104 *route = VMCI_ROUTE_AS_HOST;105 return VMCI_SUCCESS;106 } else {107 return VMCI_ERROR_DEVICE_NOT_FOUND;108 }109 }110 111 if (!from_guest && has_guest_device) {112 /* If no source context then use the current. */113 if (VMCI_INVALID_ID == src->context)114 src->context = vmci_get_context_id();115 116 /* Send it from local client down to the host. */117 *route = VMCI_ROUTE_AS_GUEST;118 return VMCI_SUCCESS;119 }120 121 /*122 * Otherwise we already received it from a guest and123 * it is destined for a local client on this host, or124 * it is from another local client on this host. We125 * must be acting as a host to service it.126 */127 if (!has_host_device)128 return VMCI_ERROR_DEVICE_NOT_FOUND;129 130 if (VMCI_INVALID_ID == src->context) {131 /*132 * If it came from a guest then it must have a133 * valid context. Otherwise we can use the134 * host context.135 */136 if (from_guest)137 return VMCI_ERROR_INVALID_ARGS;138 139 src->context = VMCI_HOST_CONTEXT_ID;140 }141 142 /* Route to local client. */143 *route = VMCI_ROUTE_AS_HOST;144 return VMCI_SUCCESS;145 }146 147 /*148 * If we are acting as a host then this might be destined for149 * a guest.150 */151 if (has_host_device) {152 /* It will have a context if it is meant for a guest. */153 if (vmci_ctx_exists(dst->context)) {154 if (VMCI_INVALID_ID == src->context) {155 /*156 * If it came from a guest then it157 * must have a valid context.158 * Otherwise we can use the host159 * context.160 */161 162 if (from_guest)163 return VMCI_ERROR_INVALID_ARGS;164 165 src->context = VMCI_HOST_CONTEXT_ID;166 } else if (VMCI_CONTEXT_IS_VM(src->context) &&167 src->context != dst->context) {168 /*169 * VM to VM communication is not170 * allowed. Since we catch all171 * communication destined for the host172 * above, this must be destined for a173 * VM since there is a valid context.174 */175 176 return VMCI_ERROR_DST_UNREACHABLE;177 }178 179 /* Pass it up to the guest. */180 *route = VMCI_ROUTE_AS_HOST;181 return VMCI_SUCCESS;182 } else if (!has_guest_device) {183 /*184 * The host is attempting to reach a CID185 * without an active context, and we can't186 * send it down, since we have no guest187 * device.188 */189 190 return VMCI_ERROR_DST_UNREACHABLE;191 }192 }193 194 /*195 * We must be a guest trying to send to another guest, which means196 * we need to send it down to the host. We do not filter out VM to197 * VM communication here, since we want to be able to use the guest198 * driver on older versions that do support VM to VM communication.199 */200 if (!has_guest_device) {201 /*202 * Ending up here means we have neither guest nor host203 * device.204 */205 return VMCI_ERROR_DEVICE_NOT_FOUND;206 }207 208 /* If no source context then use the current context. */209 if (VMCI_INVALID_ID == src->context)210 src->context = vmci_get_context_id();211 212 /*213 * Send it from local client down to the host, which will214 * route it to the other guest for us.215 */216 *route = VMCI_ROUTE_AS_GUEST;217 return VMCI_SUCCESS;218}219