drivers/staging/greybus/manifest.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Greybus manifest parsing
   4  *
   5  * Copyright 2014-2015 Google Inc.
   6  * Copyright 2014-2015 Linaro Ltd.
   7  */
   8
   9 #include "greybus.h"
  10
  11 static const char *get_descriptor_type_string(u8 type)
  12 {
  13         switch (type) {
  14         case GREYBUS_TYPE_INVALID:
  15                 return "invalid";
  16         case GREYBUS_TYPE_STRING:
  17                 return "string";
  18         case GREYBUS_TYPE_INTERFACE:
  19                 return "interface";
  20         case GREYBUS_TYPE_CPORT:
  21                 return "cport";
  22         case GREYBUS_TYPE_BUNDLE:
  23                 return "bundle";
  24         default:
  25                 WARN_ON(1);
  26                 return "unknown";
  27         }
  28 }
  29
  30 /*
  31  * We scan the manifest once to identify where all the descriptors
  32  * are.  The result is a list of these manifest_desc structures.  We
  33  * then pick through them for what we're looking for (starting with
  34  * the interface descriptor).  As each is processed we remove it from
  35  * the list.  When we're done the list should (probably) be empty.
  36  */
  37 struct manifest_desc {
  38         struct list_head                links;
  39
  40         size_t                          size;
  41         void                            *data;
  42         enum greybus_descriptor_type    type;
  43 };
  44
  45 static void release_manifest_descriptor(struct manifest_desc *descriptor)
  46 {
  47         list_del(&descriptor->links);
  48         kfree(descriptor);
  49 }
  50
  51 static void release_manifest_descriptors(struct gb_interface *intf)
  52 {
  53         struct manifest_desc *descriptor;
  54         struct manifest_desc *next;
  55
  56         list_for_each_entry_safe(descriptor, next, &intf->manifest_descs, links)
  57                 release_manifest_descriptor(descriptor);
  58 }
  59
  60 static void release_cport_descriptors(struct list_head *head, u8 bundle_id)
  61 {
  62         struct manifest_desc *desc, *tmp;
  63         struct greybus_descriptor_cport *desc_cport;
  64
  65         list_for_each_entry_safe(desc, tmp, head, links) {
  66                 desc_cport = desc->data;
  67
  68                 if (desc->type != GREYBUS_TYPE_CPORT)
  69                         continue;
  70
  71                 if (desc_cport->bundle == bundle_id)
  72                         release_manifest_descriptor(desc);
  73         }
  74 }
  75
  76 static struct manifest_desc *get_next_bundle_desc(struct gb_interface *intf)
  77 {
  78         struct manifest_desc *descriptor;
  79         struct manifest_desc *next;
  80
  81         list_for_each_entry_safe(descriptor, next, &intf->manifest_descs, links)
  82                 if (descriptor->type == GREYBUS_TYPE_BUNDLE)
  83                         return descriptor;
  84
  85         return NULL;
  86 }
  87
  88 /*
  89  * Validate the given descriptor.  Its reported size must fit within
  90  * the number of bytes remaining, and it must have a recognized
  91  * type.  Check that the reported size is at least as big as what
  92  * we expect to see.  (It could be bigger, perhaps for a new version
  93  * of the format.)
  94  *
  95  * Returns the (non-zero) number of bytes consumed by the descriptor,
  96  * or a negative errno.
  97  */
  98 static int identify_descriptor(struct gb_interface *intf,
  99                                struct greybus_descriptor *desc, size_t size)
 100 {
 101         struct greybus_descriptor_header *desc_header = &desc->header;
 102         struct manifest_desc *descriptor;
 103         size_t desc_size;
 104         size_t expected_size;
 105
 106         if (size < sizeof(*desc_header)) {
 107                 dev_err(&intf->dev, "manifest too small (%zu < %zu)\n",
 108                                 size, sizeof(*desc_header));
 109                 return -EINVAL;         /* Must at least have header */
 110         }
 111
 112         desc_size = le16_to_cpu(desc_header->size);
 113         if (desc_size > size) {
 114                 dev_err(&intf->dev, "descriptor too big (%zu > %zu)\n",
 115                                 desc_size, size);
 116                 return -EINVAL;
 117         }
 118
 119         /* Descriptor needs to at least have a header */
 120         expected_size = sizeof(*desc_header);
 121
 122         switch (desc_header->type) {
 123         case GREYBUS_TYPE_STRING:
 124                 expected_size += sizeof(struct greybus_descriptor_string);
 125                 expected_size += desc->string.length;
 126
 127                 /* String descriptors are padded to 4 byte boundaries */
 128                 expected_size = ALIGN(expected_size, 4);
 129                 break;
 130         case GREYBUS_TYPE_INTERFACE:
 131                 expected_size += sizeof(struct greybus_descriptor_interface);
 132                 break;
 133         case GREYBUS_TYPE_BUNDLE:
 134                 expected_size += sizeof(struct greybus_descriptor_bundle);
 135                 break;
 136         case GREYBUS_TYPE_CPORT:
 137                 expected_size += sizeof(struct greybus_descriptor_cport);
 138                 break;
 139         case GREYBUS_TYPE_INVALID:
 140         default:
 141                 dev_err(&intf->dev, "invalid descriptor type (%u)\n",
 142                                 desc_header->type);
 143                 return -EINVAL;
 144         }
 145
 146         if (desc_size < expected_size) {
 147                 dev_err(&intf->dev, "%s descriptor too small (%zu < %zu)\n",
 148                                 get_descriptor_type_string(desc_header->type),
 149                                 desc_size, expected_size);
 150                 return -EINVAL;
 151         }
 152
 153         /* Descriptor bigger than what we expect */
 154         if (desc_size > expected_size) {
 155                 dev_warn(&intf->dev, "%s descriptor size mismatch (want %zu got %zu)\n",
 156                                 get_descriptor_type_string(desc_header->type),
 157                                 expected_size, desc_size);
 158         }
 159
 160         descriptor = kzalloc(sizeof(*descriptor), GFP_KERNEL);
 161         if (!descriptor)
 162                 return -ENOMEM;
 163
 164         descriptor->size = desc_size;
 165         descriptor->data = (char *)desc + sizeof(*desc_header);
 166         descriptor->type = desc_header->type;
 167         list_add_tail(&descriptor->links, &intf->manifest_descs);
 168
 169         /* desc_size is positive and is known to fit in a signed int */
 170
 171         return desc_size;
 172 }
 173
 174 /*
 175  * Find the string descriptor having the given id, validate it, and
 176  * allocate a duplicate copy of it.  The duplicate has an extra byte
 177  * which guarantees the returned string is NUL-terminated.
 178  *
 179  * String index 0 is valid (it represents "no string"), and for
 180  * that a null pointer is returned.
 181  *
 182  * Otherwise returns a pointer to a newly-allocated copy of the
 183  * descriptor string, or an error-coded pointer on failure.
 184  */
 185 static char *gb_string_get(struct gb_interface *intf, u8 string_id)
 186 {
 187         struct greybus_descriptor_string *desc_string;
 188         struct manifest_desc *descriptor;
 189         bool found = false;
 190         char *string;
 191
 192         /* A zero string id means no string (but no error) */
 193         if (!string_id)
 194                 return NULL;
 195
 196         list_for_each_entry(descriptor, &intf->manifest_descs, links) {
 197                 if (descriptor->type != GREYBUS_TYPE_STRING)
 198                         continue;
 199
 200                 desc_string = descriptor->data;
 201                 if (desc_string->id == string_id) {
 202                         found = true;
 203                         break;
 204                 }
 205         }
 206         if (!found)
 207                 return ERR_PTR(-ENOENT);
 208
 209         /* Allocate an extra byte so we can guarantee it's NUL-terminated */
 210         string = kmemdup(&desc_string->string, desc_string->length + 1,
 211                                 GFP_KERNEL);
 212         if (!string)
 213                 return ERR_PTR(-ENOMEM);
 214         string[desc_string->length] = '\0';
 215
 216         /* Ok we've used this string, so we're done with it */
 217         release_manifest_descriptor(descriptor);
 218
 219         return string;
 220 }
 221
 222 /*
 223  * Find cport descriptors in the manifest associated with the given
 224  * bundle, and set up data structures for the functions that use
 225  * them.  Returns the number of cports set up for the bundle, or 0
 226  * if there is an error.
 227  */
 228 static u32 gb_manifest_parse_cports(struct gb_bundle *bundle)
 229 {
 230         struct gb_interface *intf = bundle->intf;
 231         struct greybus_descriptor_cport *desc_cport;
 232         struct manifest_desc *desc, *next, *tmp;
 233         LIST_HEAD(list);
 234         u8 bundle_id = bundle->id;
 235         u16 cport_id;
 236         u32 count = 0;
 237         int i;
 238
 239         /* Set up all cport descriptors associated with this bundle */
 240         list_for_each_entry_safe(desc, next, &intf->manifest_descs, links) {
 241                 if (desc->type != GREYBUS_TYPE_CPORT)
 242                         continue;
 243
 244                 desc_cport = desc->data;
 245                 if (desc_cport->bundle != bundle_id)
 246                         continue;
 247
 248                 cport_id = le16_to_cpu(desc_cport->id);
 249                 if (cport_id > CPORT_ID_MAX)
 250                         goto exit;
 251
 252                 /* Nothing else should have its cport_id as control cport id */
 253                 if (cport_id == GB_CONTROL_CPORT_ID) {
 254                         dev_err(&bundle->dev, "invalid cport id found (%02u)\n",
 255                                 cport_id);
 256                         goto exit;
 257                 }
 258
 259                 /*
 260                  * Found one, move it to our temporary list after checking for
 261                  * duplicates.
 262                  */
 263                 list_for_each_entry(tmp, &list, links) {
 264                         desc_cport = tmp->data;
 265                         if (cport_id == le16_to_cpu(desc_cport->id)) {
 266                                 dev_err(&bundle->dev,
 267                                                 "duplicate CPort %u found\n",
 268                                                 cport_id);
 269                                 goto exit;
 270                         }
 271                 }
 272                 list_move_tail(&desc->links, &list);
 273                 count++;
 274         }
 275
 276         if (!count)
 277                 return 0;
 278
 279         bundle->cport_desc = kcalloc(count, sizeof(*bundle->cport_desc),
 280                                         GFP_KERNEL);
 281         if (!bundle->cport_desc)
 282                 goto exit;
 283
 284         bundle->num_cports = count;
 285
 286         i = 0;
 287         list_for_each_entry_safe(desc, next, &list, links) {
 288                 desc_cport = desc->data;
 289                 memcpy(&bundle->cport_desc[i++], desc_cport,
 290                                 sizeof(*desc_cport));
 291
 292                 /* Release the cport descriptor */
 293                 release_manifest_descriptor(desc);
 294         }
 295
 296         return count;
 297 exit:
 298         release_cport_descriptors(&list, bundle_id);
 299         /*
 300          * Free all cports for this bundle to avoid 'excess descriptors'
 301          * warnings.
 302          */
 303         release_cport_descriptors(&intf->manifest_descs, bundle_id);
 304
 305         return 0;       /* Error; count should also be 0 */
 306 }
 307
 308 /*
 309  * Find bundle descriptors in the manifest and set up their data
 310  * structures.  Returns the number of bundles set up for the
 311  * given interface.
 312  */
 313 static u32 gb_manifest_parse_bundles(struct gb_interface *intf)
 314 {
 315         struct manifest_desc *desc;
 316         struct gb_bundle *bundle;
 317         struct gb_bundle *bundle_next;
 318         u32 count = 0;
 319         u8 bundle_id;
 320         u8 class;
 321
 322         while ((desc = get_next_bundle_desc(intf))) {
 323                 struct greybus_descriptor_bundle *desc_bundle;
 324
 325                 /* Found one.  Set up its bundle structure*/
 326                 desc_bundle = desc->data;
 327                 bundle_id = desc_bundle->id;
 328                 class = desc_bundle->class;
 329
 330                 /* Done with this bundle descriptor */
 331                 release_manifest_descriptor(desc);
 332
 333                 /* Ignore any legacy control bundles */
 334                 if (bundle_id == GB_CONTROL_BUNDLE_ID) {
 335                         dev_dbg(&intf->dev, "%s - ignoring control bundle\n",
 336                                         __func__);
 337                         release_cport_descriptors(&intf->manifest_descs,
 338                                                                 bundle_id);
 339                         continue;
 340                 }
 341
 342                 /* Nothing else should have its class set to control class */
 343                 if (class == GREYBUS_CLASS_CONTROL) {
 344                         dev_err(&intf->dev,
 345                                 "bundle %u cannot use control class\n",
 346                                 bundle_id);
 347                         goto cleanup;
 348                 }
 349
 350                 bundle = gb_bundle_create(intf, bundle_id, class);
 351                 if (!bundle)
 352                         goto cleanup;
 353
 354                 /*
 355                  * Now go set up this bundle's functions and cports.
 356                  *
 357                  * A 'bundle' represents a device in greybus. It may require
 358                  * multiple cports for its functioning. If we fail to setup any
 359                  * cport of a bundle, we better reject the complete bundle as
 360                  * the device may not be able to function properly then.
 361                  *
 362                  * But, failing to setup a cport of bundle X doesn't mean that
 363                  * the device corresponding to bundle Y will not work properly.
 364                  * Bundles should be treated as separate independent devices.
 365                  *
 366                  * While parsing manifest for an interface, treat bundles as
 367                  * separate entities and don't reject entire interface and its
 368                  * bundles on failing to initialize a cport. But make sure the
 369                  * bundle which needs the cport, gets destroyed properly.
 370                  */
 371                 if (!gb_manifest_parse_cports(bundle)) {
 372                         gb_bundle_destroy(bundle);
 373                         continue;
 374                 }
 375
 376                 count++;
 377         }
 378
 379         return count;
 380 cleanup:
 381         /* An error occurred; undo any changes we've made */
 382         list_for_each_entry_safe(bundle, bundle_next, &intf->bundles, links) {
 383                 gb_bundle_destroy(bundle);
 384                 count--;
 385         }
 386         return 0;       /* Error; count should also be 0 */
 387 }
 388
 389 static bool gb_manifest_parse_interface(struct gb_interface *intf,
 390                                         struct manifest_desc *interface_desc)
 391 {
 392         struct greybus_descriptor_interface *desc_intf = interface_desc->data;
 393         struct gb_control *control = intf->control;
 394         char *str;
 395
 396         /* Handle the strings first--they can fail */
 397         str = gb_string_get(intf, desc_intf->vendor_stringid);
 398         if (IS_ERR(str))
 399                 return false;
 400         control->vendor_string = str;
 401
 402         str = gb_string_get(intf, desc_intf->product_stringid);
 403         if (IS_ERR(str))
 404                 goto out_free_vendor_string;
 405         control->product_string = str;
 406
 407         /* Assign feature flags communicated via manifest */
 408         intf->features = desc_intf->features;
 409
 410         /* Release the interface descriptor, now that we're done with it */
 411         release_manifest_descriptor(interface_desc);
 412
 413         /* An interface must have at least one bundle descriptor */
 414         if (!gb_manifest_parse_bundles(intf)) {
 415                 dev_err(&intf->dev, "manifest bundle descriptors not valid\n");
 416                 goto out_err;
 417         }
 418
 419         return true;
 420 out_err:
 421         kfree(control->product_string);
 422         control->product_string = NULL;
 423 out_free_vendor_string:
 424         kfree(control->vendor_string);
 425         control->vendor_string = NULL;
 426
 427         return false;
 428 }
 429
 430 /*
 431  * Parse a buffer containing an interface manifest.
 432  *
 433  * If we find anything wrong with the content/format of the buffer
 434  * we reject it.
 435  *
 436  * The first requirement is that the manifest's version is
 437  * one we can parse.
 438  *
 439  * We make an initial pass through the buffer and identify all of
 440  * the descriptors it contains, keeping track for each its type
 441  * and the location size of its data in the buffer.
 442  *
 443  * Next we scan the descriptors, looking for an interface descriptor;
 444  * there must be exactly one of those.  When found, we record the
 445  * information it contains, and then remove that descriptor (and any
 446  * string descriptors it refers to) from further consideration.
 447  *
 448  * After that we look for the interface's bundles--there must be at
 449  * least one of those.
 450  *
 451  * Returns true if parsing was successful, false otherwise.
 452  */
 453 bool gb_manifest_parse(struct gb_interface *intf, void *data, size_t size)
 454 {
 455         struct greybus_manifest *manifest;
 456         struct greybus_manifest_header *header;
 457         struct greybus_descriptor *desc;
 458         struct manifest_desc *descriptor;
 459         struct manifest_desc *interface_desc = NULL;
 460         u16 manifest_size;
 461         u32 found = 0;
 462         bool result;
 463
 464         /* Manifest descriptor list should be empty here */
 465         if (WARN_ON(!list_empty(&intf->manifest_descs)))
 466                 return false;
 467
 468         /* we have to have at _least_ the manifest header */
 469         if (size < sizeof(*header)) {
 470                 dev_err(&intf->dev, "short manifest (%zu < %zu)\n",
 471                                 size, sizeof(*header));
 472                 return false;
 473         }
 474
 475         /* Make sure the size is right */
 476         manifest = data;
 477         header = &manifest->header;
 478         manifest_size = le16_to_cpu(header->size);
 479         if (manifest_size != size) {
 480                 dev_err(&intf->dev, "manifest size mismatch (%zu != %u)\n",
 481                                 size, manifest_size);
 482                 return false;
 483         }
 484
 485         /* Validate major/minor number */
 486         if (header->version_major > GREYBUS_VERSION_MAJOR) {
 487                 dev_err(&intf->dev, "manifest version too new (%u.%u > %u.%u)\n",
 488                                 header->version_major, header->version_minor,
 489                                 GREYBUS_VERSION_MAJOR, GREYBUS_VERSION_MINOR);
 490                 return false;
 491         }
 492
 493         /* OK, find all the descriptors */
 494         desc = manifest->descriptors;
 495         size -= sizeof(*header);
 496         while (size) {
 497                 int desc_size;
 498
 499                 desc_size = identify_descriptor(intf, desc, size);
 500                 if (desc_size < 0) {
 501                         result = false;
 502                         goto out;
 503                 }
 504                 desc = (struct greybus_descriptor *)((char *)desc + desc_size);
 505                 size -= desc_size;
 506         }
 507
 508         /* There must be a single interface descriptor */
 509         list_for_each_entry(descriptor, &intf->manifest_descs, links) {
 510                 if (descriptor->type == GREYBUS_TYPE_INTERFACE)
 511                         if (!found++)
 512                                 interface_desc = descriptor;
 513         }
 514         if (found != 1) {
 515                 dev_err(&intf->dev, "manifest must have 1 interface descriptor (%u found)\n",
 516                                 found);
 517                 result = false;
 518                 goto out;
 519         }
 520
 521         /* Parse the manifest, starting with the interface descriptor */
 522         result = gb_manifest_parse_interface(intf, interface_desc);
 523
 524         /*
 525          * We really should have no remaining descriptors, but we
 526          * don't know what newer format manifests might leave.
 527          */
 528         if (result && !list_empty(&intf->manifest_descs))
 529                 dev_info(&intf->dev, "excess descriptors in interface manifest\n");
 530 out:
 531         release_manifest_descriptors(intf);
 532
 533         return result;
 534 }