drivers/misc/vmw_vmci/vmci_datagram.c

   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 #include <linux/module.h>
  11 #include <linux/sched.h>
  12 #include <linux/slab.h>
  13 #include <linux/bug.h>
  14
  15 #include "vmci_datagram.h"
  16 #include "vmci_resource.h"
  17 #include "vmci_context.h"
  18 #include "vmci_driver.h"
  19 #include "vmci_event.h"
  20 #include "vmci_route.h"
  21
  22 /*
  23  * struct datagram_entry describes the datagram entity. It is used for datagram
  24  * entities created only on the host.
  25  */
  26 struct datagram_entry {
  27         struct vmci_resource resource;
  28         u32 flags;
  29         bool run_delayed;
  30         vmci_datagram_recv_cb recv_cb;
  31         void *client_data;
  32         u32 priv_flags;
  33 };
  34
  35 struct delayed_datagram_info {
  36         struct datagram_entry *entry;
  37         struct work_struct work;
  38         bool in_dg_host_queue;
  39         /* msg and msg_payload must be together. */
  40         struct vmci_datagram msg;
  41         u8 msg_payload[];
  42 };
  43
  44 /* Number of in-flight host->host datagrams */
  45 static atomic_t delayed_dg_host_queue_size = ATOMIC_INIT(0);
  46
  47 /*
  48  * Create a datagram entry given a handle pointer.
  49  */
  50 static int dg_create_handle(u32 resource_id,
  51                             u32 flags,
  52                             u32 priv_flags,
  53                             vmci_datagram_recv_cb recv_cb,
  54                             void *client_data, struct vmci_handle *out_handle)
  55 {
  56         int result;
  57         u32 context_id;
  58         struct vmci_handle handle;
  59         struct datagram_entry *entry;
  60
  61         if ((flags & VMCI_FLAG_WELLKNOWN_DG_HND) != 0)
  62                 return VMCI_ERROR_INVALID_ARGS;
  63
  64         if ((flags & VMCI_FLAG_ANYCID_DG_HND) != 0) {
  65                 context_id = VMCI_INVALID_ID;
  66         } else {
  67                 context_id = vmci_get_context_id();
  68                 if (context_id == VMCI_INVALID_ID)
  69                         return VMCI_ERROR_NO_RESOURCES;
  70         }
  71
  72         handle = vmci_make_handle(context_id, resource_id);
  73
  74         entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  75         if (!entry) {
  76                 pr_warn("Failed allocating memory for datagram entry\n");
  77                 return VMCI_ERROR_NO_MEM;
  78         }
  79
  80         entry->run_delayed = (flags & VMCI_FLAG_DG_DELAYED_CB) ? true : false;
  81         entry->flags = flags;
  82         entry->recv_cb = recv_cb;
  83         entry->client_data = client_data;
  84         entry->priv_flags = priv_flags;
  85
  86         /* Make datagram resource live. */
  87         result = vmci_resource_add(&entry->resource,
  88                                    VMCI_RESOURCE_TYPE_DATAGRAM,
  89                                    handle);
  90         if (result != VMCI_SUCCESS) {
  91                 pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d\n",
  92                         handle.context, handle.resource, result);
  93                 kfree(entry);
  94                 return result;
  95         }
  96
  97         *out_handle = vmci_resource_handle(&entry->resource);
  98         return VMCI_SUCCESS;
  99 }
 100
 101 /*
 102  * Internal utility function with the same purpose as
 103  * vmci_datagram_get_priv_flags that also takes a context_id.
 104  */
 105 static int vmci_datagram_get_priv_flags(u32 context_id,
 106                                         struct vmci_handle handle,
 107                                         u32 *priv_flags)
 108 {
 109         if (context_id == VMCI_INVALID_ID)
 110                 return VMCI_ERROR_INVALID_ARGS;
 111
 112         if (context_id == VMCI_HOST_CONTEXT_ID) {
 113                 struct datagram_entry *src_entry;
 114                 struct vmci_resource *resource;
 115
 116                 resource = vmci_resource_by_handle(handle,
 117                                                    VMCI_RESOURCE_TYPE_DATAGRAM);
 118                 if (!resource)
 119                         return VMCI_ERROR_INVALID_ARGS;
 120
 121                 src_entry = container_of(resource, struct datagram_entry,
 122                                          resource);
 123                 *priv_flags = src_entry->priv_flags;
 124                 vmci_resource_put(resource);
 125         } else if (context_id == VMCI_HYPERVISOR_CONTEXT_ID)
 126                 *priv_flags = VMCI_MAX_PRIVILEGE_FLAGS;
 127         else
 128                 *priv_flags = vmci_context_get_priv_flags(context_id);
 129
 130         return VMCI_SUCCESS;
 131 }
 132
 133 /*
 134  * Calls the specified callback in a delayed context.
 135  */
 136 static void dg_delayed_dispatch(struct work_struct *work)
 137 {
 138         struct delayed_datagram_info *dg_info =
 139                         container_of(work, struct delayed_datagram_info, work);
 140
 141         dg_info->entry->recv_cb(dg_info->entry->client_data, &dg_info->msg);
 142
 143         vmci_resource_put(&dg_info->entry->resource);
 144
 145         if (dg_info->in_dg_host_queue)
 146                 atomic_dec(&delayed_dg_host_queue_size);
 147
 148         kfree(dg_info);
 149 }
 150
 151 /*
 152  * Dispatch datagram as a host, to the host, or other vm context. This
 153  * function cannot dispatch to hypervisor context handlers. This should
 154  * have been handled before we get here by vmci_datagram_dispatch.
 155  * Returns number of bytes sent on success, error code otherwise.
 156  */
 157 static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
 158 {
 159         int retval;
 160         size_t dg_size;
 161         u32 src_priv_flags;
 162
 163         dg_size = VMCI_DG_SIZE(dg);
 164
 165         /* Host cannot send to the hypervisor. */
 166         if (dg->dst.context == VMCI_HYPERVISOR_CONTEXT_ID)
 167                 return VMCI_ERROR_DST_UNREACHABLE;
 168
 169         /* Check that source handle matches sending context. */
 170         if (dg->src.context != context_id) {
 171                 pr_devel("Sender context (ID=0x%x) is not owner of src datagram entry (handle=0x%x:0x%x)\n",
 172                          context_id, dg->src.context, dg->src.resource);
 173                 return VMCI_ERROR_NO_ACCESS;
 174         }
 175
 176         /* Get hold of privileges of sending endpoint. */
 177         retval = vmci_datagram_get_priv_flags(context_id, dg->src,
 178                                               &src_priv_flags);
 179         if (retval != VMCI_SUCCESS) {
 180                 pr_warn("Couldn't get privileges (handle=0x%x:0x%x)\n",
 181                         dg->src.context, dg->src.resource);
 182                 return retval;
 183         }
 184
 185         /* Determine if we should route to host or guest destination. */
 186         if (dg->dst.context == VMCI_HOST_CONTEXT_ID) {
 187                 /* Route to host datagram entry. */
 188                 struct datagram_entry *dst_entry;
 189                 struct vmci_resource *resource;
 190
 191                 if (dg->src.context == VMCI_HYPERVISOR_CONTEXT_ID &&
 192                     dg->dst.resource == VMCI_EVENT_HANDLER) {
 193                         return vmci_event_dispatch(dg);
 194                 }
 195
 196                 resource = vmci_resource_by_handle(dg->dst,
 197                                                    VMCI_RESOURCE_TYPE_DATAGRAM);
 198                 if (!resource) {
 199                         pr_devel("Sending to invalid destination (handle=0x%x:0x%x)\n",
 200                                  dg->dst.context, dg->dst.resource);
 201                         return VMCI_ERROR_INVALID_RESOURCE;
 202                 }
 203                 dst_entry = container_of(resource, struct datagram_entry,
 204                                          resource);
 205                 if (vmci_deny_interaction(src_priv_flags,
 206                                           dst_entry->priv_flags)) {
 207                         vmci_resource_put(resource);
 208                         return VMCI_ERROR_NO_ACCESS;
 209                 }
 210
 211                 /*
 212                  * If a VMCI datagram destined for the host is also sent by the
 213                  * host, we always run it delayed. This ensures that no locks
 214                  * are held when the datagram callback runs.
 215                  */
 216                 if (dst_entry->run_delayed ||
 217                     dg->src.context == VMCI_HOST_CONTEXT_ID) {
 218                         struct delayed_datagram_info *dg_info;
 219
 220                         if (atomic_add_return(1, &delayed_dg_host_queue_size)
 221                             == VMCI_MAX_DELAYED_DG_HOST_QUEUE_SIZE) {
 222                                 atomic_dec(&delayed_dg_host_queue_size);
 223                                 vmci_resource_put(resource);
 224                                 return VMCI_ERROR_NO_MEM;
 225                         }
 226
 227                         dg_info = kmalloc(sizeof(*dg_info) +
 228                                     (size_t) dg->payload_size, GFP_ATOMIC);
 229                         if (!dg_info) {
 230                                 atomic_dec(&delayed_dg_host_queue_size);
 231                                 vmci_resource_put(resource);
 232                                 return VMCI_ERROR_NO_MEM;
 233                         }
 234
 235                         dg_info->in_dg_host_queue = true;
 236                         dg_info->entry = dst_entry;
 237                         memcpy(&dg_info->msg, dg, dg_size);
 238
 239                         INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 240                         schedule_work(&dg_info->work);
 241                         retval = VMCI_SUCCESS;
 242
 243                 } else {
 244                         retval = dst_entry->recv_cb(dst_entry->client_data, dg);
 245                         vmci_resource_put(resource);
 246                         if (retval < VMCI_SUCCESS)
 247                                 return retval;
 248                 }
 249         } else {
 250                 /* Route to destination VM context. */
 251                 struct vmci_datagram *new_dg;
 252
 253                 if (context_id != dg->dst.context) {
 254                         if (vmci_deny_interaction(src_priv_flags,
 255                                                   vmci_context_get_priv_flags
 256                                                   (dg->dst.context))) {
 257                                 return VMCI_ERROR_NO_ACCESS;
 258                         } else if (VMCI_CONTEXT_IS_VM(context_id)) {
 259                                 /*
 260                                  * If the sending context is a VM, it
 261                                  * cannot reach another VM.
 262                                  */
 263
 264                                 pr_devel("Datagram communication between VMs not supported (src=0x%x, dst=0x%x)\n",
 265                                          context_id, dg->dst.context);
 266                                 return VMCI_ERROR_DST_UNREACHABLE;
 267                         }
 268                 }
 269
 270                 /* We make a copy to enqueue. */
 271                 new_dg = kmemdup(dg, dg_size, GFP_KERNEL);
 272                 if (new_dg == NULL)
 273                         return VMCI_ERROR_NO_MEM;
 274
 275                 retval = vmci_ctx_enqueue_datagram(dg->dst.context, new_dg);
 276                 if (retval < VMCI_SUCCESS) {
 277                         kfree(new_dg);
 278                         return retval;
 279                 }
 280         }
 281
 282         /*
 283          * We currently truncate the size to signed 32 bits. This doesn't
 284          * matter for this handler as it only support 4Kb messages.
 285          */
 286         return (int)dg_size;
 287 }
 288
 289 /*
 290  * Dispatch datagram as a guest, down through the VMX and potentially to
 291  * the host.
 292  * Returns number of bytes sent on success, error code otherwise.
 293  */
 294 static int dg_dispatch_as_guest(struct vmci_datagram *dg)
 295 {
 296         int retval;
 297         struct vmci_resource *resource;
 298
 299         resource = vmci_resource_by_handle(dg->src,
 300                                            VMCI_RESOURCE_TYPE_DATAGRAM);
 301         if (!resource)
 302                 return VMCI_ERROR_NO_HANDLE;
 303
 304         retval = vmci_send_datagram(dg);
 305         vmci_resource_put(resource);
 306         return retval;
 307 }
 308
 309 /*
 310  * Dispatch datagram.  This will determine the routing for the datagram
 311  * and dispatch it accordingly.
 312  * Returns number of bytes sent on success, error code otherwise.
 313  */
 314 int vmci_datagram_dispatch(u32 context_id,
 315                            struct vmci_datagram *dg, bool from_guest)
 316 {
 317         int retval;
 318         enum vmci_route route;
 319
 320         BUILD_BUG_ON(sizeof(struct vmci_datagram) != 24);
 321
 322         if (dg->payload_size > VMCI_MAX_DG_SIZE ||
 323             VMCI_DG_SIZE(dg) > VMCI_MAX_DG_SIZE) {
 324                 pr_devel("Payload (size=%llu bytes) too big to send\n",
 325                          (unsigned long long)dg->payload_size);
 326                 return VMCI_ERROR_INVALID_ARGS;
 327         }
 328
 329         retval = vmci_route(&dg->src, &dg->dst, from_guest, &route);
 330         if (retval < VMCI_SUCCESS) {
 331                 pr_devel("Failed to route datagram (src=0x%x, dst=0x%x, err=%d)\n",
 332                          dg->src.context, dg->dst.context, retval);
 333                 return retval;
 334         }
 335
 336         if (VMCI_ROUTE_AS_HOST == route) {
 337                 if (VMCI_INVALID_ID == context_id)
 338                         context_id = VMCI_HOST_CONTEXT_ID;
 339                 return dg_dispatch_as_host(context_id, dg);
 340         }
 341
 342         if (VMCI_ROUTE_AS_GUEST == route)
 343                 return dg_dispatch_as_guest(dg);
 344
 345         pr_warn("Unknown route (%d) for datagram\n", route);
 346         return VMCI_ERROR_DST_UNREACHABLE;
 347 }
 348
 349 /*
 350  * Invoke the handler for the given datagram.  This is intended to be
 351  * called only when acting as a guest and receiving a datagram from the
 352  * virtual device.
 353  */
 354 int vmci_datagram_invoke_guest_handler(struct vmci_datagram *dg)
 355 {
 356         struct vmci_resource *resource;
 357         struct datagram_entry *dst_entry;
 358
 359         resource = vmci_resource_by_handle(dg->dst,
 360                                            VMCI_RESOURCE_TYPE_DATAGRAM);
 361         if (!resource) {
 362                 pr_devel("destination (handle=0x%x:0x%x) doesn't exist\n",
 363                          dg->dst.context, dg->dst.resource);
 364                 return VMCI_ERROR_NO_HANDLE;
 365         }
 366
 367         dst_entry = container_of(resource, struct datagram_entry, resource);
 368         if (dst_entry->run_delayed) {
 369                 struct delayed_datagram_info *dg_info;
 370
 371                 dg_info = kmalloc(sizeof(*dg_info) + (size_t)dg->payload_size,
 372                                   GFP_ATOMIC);
 373                 if (!dg_info) {
 374                         vmci_resource_put(resource);
 375                         return VMCI_ERROR_NO_MEM;
 376                 }
 377
 378                 dg_info->in_dg_host_queue = false;
 379                 dg_info->entry = dst_entry;
 380                 memcpy(&dg_info->msg, dg, VMCI_DG_SIZE(dg));
 381
 382                 INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 383                 schedule_work(&dg_info->work);
 384         } else {
 385                 dst_entry->recv_cb(dst_entry->client_data, dg);
 386                 vmci_resource_put(resource);
 387         }
 388
 389         return VMCI_SUCCESS;
 390 }
 391
 392 /*
 393  * vmci_datagram_create_handle_priv() - Create host context datagram endpoint
 394  * @resource_id:        The resource ID.
 395  * @flags:      Datagram Flags.
 396  * @priv_flags: Privilege Flags.
 397  * @recv_cb:    Callback when receiving datagrams.
 398  * @client_data:        Pointer for a datagram_entry struct
 399  * @out_handle: vmci_handle that is populated as a result of this function.
 400  *
 401  * Creates a host context datagram endpoint and returns a handle to it.
 402  */
 403 int vmci_datagram_create_handle_priv(u32 resource_id,
 404                                      u32 flags,
 405                                      u32 priv_flags,
 406                                      vmci_datagram_recv_cb recv_cb,
 407                                      void *client_data,
 408                                      struct vmci_handle *out_handle)
 409 {
 410         if (out_handle == NULL)
 411                 return VMCI_ERROR_INVALID_ARGS;
 412
 413         if (recv_cb == NULL) {
 414                 pr_devel("Client callback needed when creating datagram\n");
 415                 return VMCI_ERROR_INVALID_ARGS;
 416         }
 417
 418         if (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS)
 419                 return VMCI_ERROR_INVALID_ARGS;
 420
 421         return dg_create_handle(resource_id, flags, priv_flags, recv_cb,
 422                                 client_data, out_handle);
 423 }
 424 EXPORT_SYMBOL_GPL(vmci_datagram_create_handle_priv);
 425
 426 /*
 427  * vmci_datagram_create_handle() - Create host context datagram endpoint
 428  * @resource_id:        Resource ID.
 429  * @flags:      Datagram Flags.
 430  * @recv_cb:    Callback when receiving datagrams.
 431  * @client_ata: Pointer for a datagram_entry struct
 432  * @out_handle: vmci_handle that is populated as a result of this function.
 433  *
 434  * Creates a host context datagram endpoint and returns a handle to
 435  * it.  Same as vmci_datagram_create_handle_priv without the priviledge
 436  * flags argument.
 437  */
 438 int vmci_datagram_create_handle(u32 resource_id,
 439                                 u32 flags,
 440                                 vmci_datagram_recv_cb recv_cb,
 441                                 void *client_data,
 442                                 struct vmci_handle *out_handle)
 443 {
 444         return vmci_datagram_create_handle_priv(
 445                 resource_id, flags,
 446                 VMCI_DEFAULT_PROC_PRIVILEGE_FLAGS,
 447                 recv_cb, client_data,
 448                 out_handle);
 449 }
 450 EXPORT_SYMBOL_GPL(vmci_datagram_create_handle);
 451
 452 /*
 453  * vmci_datagram_destroy_handle() - Destroys datagram handle
 454  * @handle:     vmci_handle to be destroyed and reaped.
 455  *
 456  * Use this function to destroy any datagram handles created by
 457  * vmci_datagram_create_handle{,Priv} functions.
 458  */
 459 int vmci_datagram_destroy_handle(struct vmci_handle handle)
 460 {
 461         struct datagram_entry *entry;
 462         struct vmci_resource *resource;
 463
 464         resource = vmci_resource_by_handle(handle, VMCI_RESOURCE_TYPE_DATAGRAM);
 465         if (!resource) {
 466                 pr_devel("Failed to destroy datagram (handle=0x%x:0x%x)\n",
 467                          handle.context, handle.resource);
 468                 return VMCI_ERROR_NOT_FOUND;
 469         }
 470
 471         entry = container_of(resource, struct datagram_entry, resource);
 472
 473         vmci_resource_put(&entry->resource);
 474         vmci_resource_remove(&entry->resource);
 475         kfree(entry);
 476
 477         return VMCI_SUCCESS;
 478 }
 479 EXPORT_SYMBOL_GPL(vmci_datagram_destroy_handle);
 480
 481 /*
 482  * vmci_datagram_send() - Send a datagram
 483  * @msg:        The datagram to send.
 484  *
 485  * Sends the provided datagram on its merry way.
 486  */
 487 int vmci_datagram_send(struct vmci_datagram *msg)
 488 {
 489         if (msg == NULL)
 490                 return VMCI_ERROR_INVALID_ARGS;
 491
 492         return vmci_datagram_dispatch(VMCI_INVALID_ID, msg, false);
 493 }
 494 EXPORT_SYMBOL_GPL(vmci_datagram_send);