drivers/misc/vmw_vmci/vmci_datagram.c

   1 /*
   2  * VMware VMCI Driver
   3  *
   4  * Copyright (C) 2012 VMware, Inc. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation version 2 and no later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * for more details.
  14  */
  15
  16 #include <linux/vmw_vmci_defs.h>
  17 #include <linux/vmw_vmci_api.h>
  18 #include <linux/module.h>
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/bug.h>
  22
  23 #include "vmci_datagram.h"
  24 #include "vmci_resource.h"
  25 #include "vmci_context.h"
  26 #include "vmci_driver.h"
  27 #include "vmci_event.h"
  28 #include "vmci_route.h"
  29
  30 /*
  31  * struct datagram_entry describes the datagram entity. It is used for datagram
  32  * entities created only on the host.
  33  */
  34 struct datagram_entry {
  35         struct vmci_resource resource;
  36         u32 flags;
  37         bool run_delayed;
  38         vmci_datagram_recv_cb recv_cb;
  39         void *client_data;
  40         u32 priv_flags;
  41 };
  42
  43 struct delayed_datagram_info {
  44         struct datagram_entry *entry;
  45         struct vmci_datagram msg;
  46         struct work_struct work;
  47         bool in_dg_host_queue;
  48 };
  49
  50 /* Number of in-flight host->host datagrams */
  51 static atomic_t delayed_dg_host_queue_size = ATOMIC_INIT(0);
  52
  53 /*
  54  * Create a datagram entry given a handle pointer.
  55  */
  56 static int dg_create_handle(u32 resource_id,
  57                             u32 flags,
  58                             u32 priv_flags,
  59                             vmci_datagram_recv_cb recv_cb,
  60                             void *client_data, struct vmci_handle *out_handle)
  61 {
  62         int result;
  63         u32 context_id;
  64         struct vmci_handle handle;
  65         struct datagram_entry *entry;
  66
  67         if ((flags & VMCI_FLAG_WELLKNOWN_DG_HND) != 0)
  68                 return VMCI_ERROR_INVALID_ARGS;
  69
  70         if ((flags & VMCI_FLAG_ANYCID_DG_HND) != 0) {
  71                 context_id = VMCI_INVALID_ID;
  72         } else {
  73                 context_id = vmci_get_context_id();
  74                 if (context_id == VMCI_INVALID_ID)
  75                         return VMCI_ERROR_NO_RESOURCES;
  76         }
  77
  78         handle = vmci_make_handle(context_id, resource_id);
  79
  80         entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  81         if (!entry) {
  82                 pr_warn("Failed allocating memory for datagram entry\n");
  83                 return VMCI_ERROR_NO_MEM;
  84         }
  85
  86         entry->run_delayed = (flags & VMCI_FLAG_DG_DELAYED_CB) ? true : false;
  87         entry->flags = flags;
  88         entry->recv_cb = recv_cb;
  89         entry->client_data = client_data;
  90         entry->priv_flags = priv_flags;
  91
  92         /* Make datagram resource live. */
  93         result = vmci_resource_add(&entry->resource,
  94                                    VMCI_RESOURCE_TYPE_DATAGRAM,
  95                                    handle);
  96         if (result != VMCI_SUCCESS) {
  97                 pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d\n",
  98                         handle.context, handle.resource, result);
  99                 kfree(entry);
 100                 return result;
 101         }
 102
 103         *out_handle = vmci_resource_handle(&entry->resource);
 104         return VMCI_SUCCESS;
 105 }
 106
 107 /*
 108  * Internal utility function with the same purpose as
 109  * vmci_datagram_get_priv_flags that also takes a context_id.
 110  */
 111 static int vmci_datagram_get_priv_flags(u32 context_id,
 112                                         struct vmci_handle handle,
 113                                         u32 *priv_flags)
 114 {
 115         if (context_id == VMCI_INVALID_ID)
 116                 return VMCI_ERROR_INVALID_ARGS;
 117
 118         if (context_id == VMCI_HOST_CONTEXT_ID) {
 119                 struct datagram_entry *src_entry;
 120                 struct vmci_resource *resource;
 121
 122                 resource = vmci_resource_by_handle(handle,
 123                                                    VMCI_RESOURCE_TYPE_DATAGRAM);
 124                 if (!resource)
 125                         return VMCI_ERROR_INVALID_ARGS;
 126
 127                 src_entry = container_of(resource, struct datagram_entry,
 128                                          resource);
 129                 *priv_flags = src_entry->priv_flags;
 130                 vmci_resource_put(resource);
 131         } else if (context_id == VMCI_HYPERVISOR_CONTEXT_ID)
 132                 *priv_flags = VMCI_MAX_PRIVILEGE_FLAGS;
 133         else
 134                 *priv_flags = vmci_context_get_priv_flags(context_id);
 135
 136         return VMCI_SUCCESS;
 137 }
 138
 139 /*
 140  * Calls the specified callback in a delayed context.
 141  */
 142 static void dg_delayed_dispatch(struct work_struct *work)
 143 {
 144         struct delayed_datagram_info *dg_info =
 145                         container_of(work, struct delayed_datagram_info, work);
 146
 147         dg_info->entry->recv_cb(dg_info->entry->client_data, &dg_info->msg);
 148
 149         vmci_resource_put(&dg_info->entry->resource);
 150
 151         if (dg_info->in_dg_host_queue)
 152                 atomic_dec(&delayed_dg_host_queue_size);
 153
 154         kfree(dg_info);
 155 }
 156
 157 /*
 158  * Dispatch datagram as a host, to the host, or other vm context. This
 159  * function cannot dispatch to hypervisor context handlers. This should
 160  * have been handled before we get here by vmci_datagram_dispatch.
 161  * Returns number of bytes sent on success, error code otherwise.
 162  */
 163 static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
 164 {
 165         int retval;
 166         size_t dg_size;
 167         u32 src_priv_flags;
 168
 169         dg_size = VMCI_DG_SIZE(dg);
 170
 171         /* Host cannot send to the hypervisor. */
 172         if (dg->dst.context == VMCI_HYPERVISOR_CONTEXT_ID)
 173                 return VMCI_ERROR_DST_UNREACHABLE;
 174
 175         /* Check that source handle matches sending context. */
 176         if (dg->src.context != context_id) {
 177                 pr_devel("Sender context (ID=0x%x) is not owner of src datagram entry (handle=0x%x:0x%x)\n",
 178                          context_id, dg->src.context, dg->src.resource);
 179                 return VMCI_ERROR_NO_ACCESS;
 180         }
 181
 182         /* Get hold of privileges of sending endpoint. */
 183         retval = vmci_datagram_get_priv_flags(context_id, dg->src,
 184                                               &src_priv_flags);
 185         if (retval != VMCI_SUCCESS) {
 186                 pr_warn("Couldn't get privileges (handle=0x%x:0x%x)\n",
 187                         dg->src.context, dg->src.resource);
 188                 return retval;
 189         }
 190
 191         /* Determine if we should route to host or guest destination. */
 192         if (dg->dst.context == VMCI_HOST_CONTEXT_ID) {
 193                 /* Route to host datagram entry. */
 194                 struct datagram_entry *dst_entry;
 195                 struct vmci_resource *resource;
 196
 197                 if (dg->src.context == VMCI_HYPERVISOR_CONTEXT_ID &&
 198                     dg->dst.resource == VMCI_EVENT_HANDLER) {
 199                         return vmci_event_dispatch(dg);
 200                 }
 201
 202                 resource = vmci_resource_by_handle(dg->dst,
 203                                                    VMCI_RESOURCE_TYPE_DATAGRAM);
 204                 if (!resource) {
 205                         pr_devel("Sending to invalid destination (handle=0x%x:0x%x)\n",
 206                                  dg->dst.context, dg->dst.resource);
 207                         return VMCI_ERROR_INVALID_RESOURCE;
 208                 }
 209                 dst_entry = container_of(resource, struct datagram_entry,
 210                                          resource);
 211                 if (vmci_deny_interaction(src_priv_flags,
 212                                           dst_entry->priv_flags)) {
 213                         vmci_resource_put(resource);
 214                         return VMCI_ERROR_NO_ACCESS;
 215                 }
 216
 217                 /*
 218                  * If a VMCI datagram destined for the host is also sent by the
 219                  * host, we always run it delayed. This ensures that no locks
 220                  * are held when the datagram callback runs.
 221                  */
 222                 if (dst_entry->run_delayed ||
 223                     dg->src.context == VMCI_HOST_CONTEXT_ID) {
 224                         struct delayed_datagram_info *dg_info;
 225
 226                         if (atomic_add_return(1, &delayed_dg_host_queue_size)
 227                             == VMCI_MAX_DELAYED_DG_HOST_QUEUE_SIZE) {
 228                                 atomic_dec(&delayed_dg_host_queue_size);
 229                                 vmci_resource_put(resource);
 230                                 return VMCI_ERROR_NO_MEM;
 231                         }
 232
 233                         dg_info = kmalloc(sizeof(*dg_info) +
 234                                     (size_t) dg->payload_size, GFP_ATOMIC);
 235                         if (!dg_info) {
 236                                 atomic_dec(&delayed_dg_host_queue_size);
 237                                 vmci_resource_put(resource);
 238                                 return VMCI_ERROR_NO_MEM;
 239                         }
 240
 241                         dg_info->in_dg_host_queue = true;
 242                         dg_info->entry = dst_entry;
 243                         memcpy(&dg_info->msg, dg, dg_size);
 244
 245                         INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 246                         schedule_work(&dg_info->work);
 247                         retval = VMCI_SUCCESS;
 248
 249                 } else {
 250                         retval = dst_entry->recv_cb(dst_entry->client_data, dg);
 251                         vmci_resource_put(resource);
 252                         if (retval < VMCI_SUCCESS)
 253                                 return retval;
 254                 }
 255         } else {
 256                 /* Route to destination VM context. */
 257                 struct vmci_datagram *new_dg;
 258
 259                 if (context_id != dg->dst.context) {
 260                         if (vmci_deny_interaction(src_priv_flags,
 261                                                   vmci_context_get_priv_flags
 262                                                   (dg->dst.context))) {
 263                                 return VMCI_ERROR_NO_ACCESS;
 264                         } else if (VMCI_CONTEXT_IS_VM(context_id)) {
 265                                 /*
 266                                  * If the sending context is a VM, it
 267                                  * cannot reach another VM.
 268                                  */
 269
 270                                 pr_devel("Datagram communication between VMs not supported (src=0x%x, dst=0x%x)\n",
 271                                          context_id, dg->dst.context);
 272                                 return VMCI_ERROR_DST_UNREACHABLE;
 273                         }
 274                 }
 275
 276                 /* We make a copy to enqueue. */
 277                 new_dg = kmalloc(dg_size, GFP_KERNEL);
 278                 if (new_dg == NULL)
 279                         return VMCI_ERROR_NO_MEM;
 280
 281                 memcpy(new_dg, dg, dg_size);
 282                 retval = vmci_ctx_enqueue_datagram(dg->dst.context, new_dg);
 283                 if (retval < VMCI_SUCCESS) {
 284                         kfree(new_dg);
 285                         return retval;
 286                 }
 287         }
 288
 289         /*
 290          * We currently truncate the size to signed 32 bits. This doesn't
 291          * matter for this handler as it only support 4Kb messages.
 292          */
 293         return (int)dg_size;
 294 }
 295
 296 /*
 297  * Dispatch datagram as a guest, down through the VMX and potentially to
 298  * the host.
 299  * Returns number of bytes sent on success, error code otherwise.
 300  */
 301 static int dg_dispatch_as_guest(struct vmci_datagram *dg)
 302 {
 303         int retval;
 304         struct vmci_resource *resource;
 305
 306         resource = vmci_resource_by_handle(dg->src,
 307                                            VMCI_RESOURCE_TYPE_DATAGRAM);
 308         if (!resource)
 309                 return VMCI_ERROR_NO_HANDLE;
 310
 311         retval = vmci_send_datagram(dg);
 312         vmci_resource_put(resource);
 313         return retval;
 314 }
 315
 316 /*
 317  * Dispatch datagram.  This will determine the routing for the datagram
 318  * and dispatch it accordingly.
 319  * Returns number of bytes sent on success, error code otherwise.
 320  */
 321 int vmci_datagram_dispatch(u32 context_id,
 322                            struct vmci_datagram *dg, bool from_guest)
 323 {
 324         int retval;
 325         enum vmci_route route;
 326
 327         BUILD_BUG_ON(sizeof(struct vmci_datagram) != 24);
 328
 329         if (VMCI_DG_SIZE(dg) > VMCI_MAX_DG_SIZE) {
 330                 pr_devel("Payload (size=%llu bytes) too big to send\n",
 331                          (unsigned long long)dg->payload_size);
 332                 return VMCI_ERROR_INVALID_ARGS;
 333         }
 334
 335         retval = vmci_route(&dg->src, &dg->dst, from_guest, &route);
 336         if (retval < VMCI_SUCCESS) {
 337                 pr_devel("Failed to route datagram (src=0x%x, dst=0x%x, err=%d)\n",
 338                          dg->src.context, dg->dst.context, retval);
 339                 return retval;
 340         }
 341
 342         if (VMCI_ROUTE_AS_HOST == route) {
 343                 if (VMCI_INVALID_ID == context_id)
 344                         context_id = VMCI_HOST_CONTEXT_ID;
 345                 return dg_dispatch_as_host(context_id, dg);
 346         }
 347
 348         if (VMCI_ROUTE_AS_GUEST == route)
 349                 return dg_dispatch_as_guest(dg);
 350
 351         pr_warn("Unknown route (%d) for datagram\n", route);
 352         return VMCI_ERROR_DST_UNREACHABLE;
 353 }
 354
 355 /*
 356  * Invoke the handler for the given datagram.  This is intended to be
 357  * called only when acting as a guest and receiving a datagram from the
 358  * virtual device.
 359  */
 360 int vmci_datagram_invoke_guest_handler(struct vmci_datagram *dg)
 361 {
 362         struct vmci_resource *resource;
 363         struct datagram_entry *dst_entry;
 364
 365         resource = vmci_resource_by_handle(dg->dst,
 366                                            VMCI_RESOURCE_TYPE_DATAGRAM);
 367         if (!resource) {
 368                 pr_devel("destination (handle=0x%x:0x%x) doesn't exist\n",
 369                          dg->dst.context, dg->dst.resource);
 370                 return VMCI_ERROR_NO_HANDLE;
 371         }
 372
 373         dst_entry = container_of(resource, struct datagram_entry, resource);
 374         if (dst_entry->run_delayed) {
 375                 struct delayed_datagram_info *dg_info;
 376
 377                 dg_info = kmalloc(sizeof(*dg_info) + (size_t)dg->payload_size,
 378                                   GFP_ATOMIC);
 379                 if (!dg_info) {
 380                         vmci_resource_put(resource);
 381                         return VMCI_ERROR_NO_MEM;
 382                 }
 383
 384                 dg_info->in_dg_host_queue = false;
 385                 dg_info->entry = dst_entry;
 386                 memcpy(&dg_info->msg, dg, VMCI_DG_SIZE(dg));
 387
 388                 INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 389                 schedule_work(&dg_info->work);
 390         } else {
 391                 dst_entry->recv_cb(dst_entry->client_data, dg);
 392                 vmci_resource_put(resource);
 393         }
 394
 395         return VMCI_SUCCESS;
 396 }
 397
 398 /*
 399  * vmci_datagram_create_handle_priv() - Create host context datagram endpoint
 400  * @resource_id:        The resource ID.
 401  * @flags:      Datagram Flags.
 402  * @priv_flags: Privilege Flags.
 403  * @recv_cb:    Callback when receiving datagrams.
 404  * @client_data:        Pointer for a datagram_entry struct
 405  * @out_handle: vmci_handle that is populated as a result of this function.
 406  *
 407  * Creates a host context datagram endpoint and returns a handle to it.
 408  */
 409 int vmci_datagram_create_handle_priv(u32 resource_id,
 410                                      u32 flags,
 411                                      u32 priv_flags,
 412                                      vmci_datagram_recv_cb recv_cb,
 413                                      void *client_data,
 414                                      struct vmci_handle *out_handle)
 415 {
 416         if (out_handle == NULL)
 417                 return VMCI_ERROR_INVALID_ARGS;
 418
 419         if (recv_cb == NULL) {
 420                 pr_devel("Client callback needed when creating datagram\n");
 421                 return VMCI_ERROR_INVALID_ARGS;
 422         }
 423
 424         if (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS)
 425                 return VMCI_ERROR_INVALID_ARGS;
 426
 427         return dg_create_handle(resource_id, flags, priv_flags, recv_cb,
 428                                 client_data, out_handle);
 429 }
 430 EXPORT_SYMBOL_GPL(vmci_datagram_create_handle_priv);
 431
 432 /*
 433  * vmci_datagram_create_handle() - Create host context datagram endpoint
 434  * @resource_id:        Resource ID.
 435  * @flags:      Datagram Flags.
 436  * @recv_cb:    Callback when receiving datagrams.
 437  * @client_ata: Pointer for a datagram_entry struct
 438  * @out_handle: vmci_handle that is populated as a result of this function.
 439  *
 440  * Creates a host context datagram endpoint and returns a handle to
 441  * it.  Same as vmci_datagram_create_handle_priv without the priviledge
 442  * flags argument.
 443  */
 444 int vmci_datagram_create_handle(u32 resource_id,
 445                                 u32 flags,
 446                                 vmci_datagram_recv_cb recv_cb,
 447                                 void *client_data,
 448                                 struct vmci_handle *out_handle)
 449 {
 450         return vmci_datagram_create_handle_priv(
 451                 resource_id, flags,
 452                 VMCI_DEFAULT_PROC_PRIVILEGE_FLAGS,
 453                 recv_cb, client_data,
 454                 out_handle);
 455 }
 456 EXPORT_SYMBOL_GPL(vmci_datagram_create_handle);
 457
 458 /*
 459  * vmci_datagram_destroy_handle() - Destroys datagram handle
 460  * @handle:     vmci_handle to be destroyed and reaped.
 461  *
 462  * Use this function to destroy any datagram handles created by
 463  * vmci_datagram_create_handle{,Priv} functions.
 464  */
 465 int vmci_datagram_destroy_handle(struct vmci_handle handle)
 466 {
 467         struct datagram_entry *entry;
 468         struct vmci_resource *resource;
 469
 470         resource = vmci_resource_by_handle(handle, VMCI_RESOURCE_TYPE_DATAGRAM);
 471         if (!resource) {
 472                 pr_devel("Failed to destroy datagram (handle=0x%x:0x%x)\n",
 473                          handle.context, handle.resource);
 474                 return VMCI_ERROR_NOT_FOUND;
 475         }
 476
 477         entry = container_of(resource, struct datagram_entry, resource);
 478
 479         vmci_resource_put(&entry->resource);
 480         vmci_resource_remove(&entry->resource);
 481         kfree(entry);
 482
 483         return VMCI_SUCCESS;
 484 }
 485 EXPORT_SYMBOL_GPL(vmci_datagram_destroy_handle);
 486
 487 /*
 488  * vmci_datagram_send() - Send a datagram
 489  * @msg:        The datagram to send.
 490  *
 491  * Sends the provided datagram on its merry way.
 492  */
 493 int vmci_datagram_send(struct vmci_datagram *msg)
 494 {
 495         if (msg == NULL)
 496                 return VMCI_ERROR_INVALID_ARGS;
 497
 498         return vmci_datagram_dispatch(VMCI_INVALID_ID, msg, false);
 499 }
 500 EXPORT_SYMBOL_GPL(vmci_datagram_send);