1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * VMware VMCI Driver |
4 | * |
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 available |
18 | * devices. Will set the source context if it is invalid. |
19 | */ |
20 | int 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 by |
32 | * IOCTL_VMCI_DATAGRAM_SEND (or by the vmkernel equivalent), |
33 | * which comes from the VMX, so we know it is coming from a |
34 | * guest. |
35 | * |
36 | * To avoid inconsistencies, test these once. We will test |
37 | * them again when we do the actual send to ensure that we do |
38 | * 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 we |
50 | * cannot send it to the hypervisor. It must come |
51 | * 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 to |
58 | * 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 then |
69 | * 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 we |
72 | * should set the real context here before passing it |
73 | * 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 a |
88 | * guest, then we need to send it down to the host. |
89 | * Note that if we are also acting as a host then this |
90 | * will prevent us from sending from local client to |
91 | * local client, but we accept that restriction as a |
92 | * 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 is |
97 | * host local communication. The hypervisor |
98 | * may send vmci event datagrams to the host |
99 | * itself, but it will never send datagrams to |
100 | * 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 and |
123 | * it is destined for a local client on this host, or |
124 | * it is from another local client on this host. We |
125 | * 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 a |
133 | * valid context. Otherwise we can use the |
134 | * 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 for |
149 | * 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(cid: dst->context)) { |
154 | if (VMCI_INVALID_ID == src->context) { |
155 | /* |
156 | * If it came from a guest then it |
157 | * must have a valid context. |
158 | * Otherwise we can use the host |
159 | * 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 not |
170 | * allowed. Since we catch all |
171 | * communication destined for the host |
172 | * above, this must be destined for a |
173 | * 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 CID |
185 | * without an active context, and we can't |
186 | * send it down, since we have no guest |
187 | * 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 means |
196 | * we need to send it down to the host. We do not filter out VM to |
197 | * VM communication here, since we want to be able to use the guest |
198 | * 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 host |
203 | * 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 will |
214 | * route it to the other guest for us. |
215 | */ |
216 | *route = VMCI_ROUTE_AS_GUEST; |
217 | return VMCI_SUCCESS; |
218 | } |
219 | |