root/drivers/greybus/manifest.c

DEFINITIONS

1. get_descriptor_type_string
2. release_manifest_descriptor
3. release_manifest_descriptors
4. release_cport_descriptors
5. get_next_bundle_desc
6. identify_descriptor
7. gb_string_get
8. gb_manifest_parse_cports
9. gb_manifest_parse_bundles
10. gb_manifest_parse_interface
11. gb_manifest_parse

   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 <linux/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", size,
 108                         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", cport_id);
 268                                 goto exit;
 269                         }
 270                 }
 271                 list_move_tail(&desc->links, &list);
 272                 count++;
 273         }
 274 
 275         if (!count)
 276                 return 0;
 277 
 278         bundle->cport_desc = kcalloc(count, sizeof(*bundle->cport_desc),
 279                                      GFP_KERNEL);
 280         if (!bundle->cport_desc)
 281                 goto exit;
 282 
 283         bundle->num_cports = count;
 284 
 285         i = 0;
 286         list_for_each_entry_safe(desc, next, &list, links) {
 287                 desc_cport = desc->data;
 288                 memcpy(&bundle->cport_desc[i++], desc_cport,
 289                        sizeof(*desc_cport));
 290 
 291                 /* Release the cport descriptor */
 292                 release_manifest_descriptor(desc);
 293         }
 294 
 295         return count;
 296 exit:
 297         release_cport_descriptors(&list, bundle_id);
 298         /*
 299          * Free all cports for this bundle to avoid 'excess descriptors'
 300          * warnings.
 301          */
 302         release_cport_descriptors(&intf->manifest_descs, bundle_id);
 303 
 304         return 0;       /* Error; count should also be 0 */
 305 }
 306 
 307 /*
 308  * Find bundle descriptors in the manifest and set up their data
 309  * structures.  Returns the number of bundles set up for the
 310  * given interface.
 311  */
 312 static u32 gb_manifest_parse_bundles(struct gb_interface *intf)
 313 {
 314         struct manifest_desc *desc;
 315         struct gb_bundle *bundle;
 316         struct gb_bundle *bundle_next;
 317         u32 count = 0;
 318         u8 bundle_id;
 319         u8 class;
 320 
 321         while ((desc = get_next_bundle_desc(intf))) {
 322                 struct greybus_descriptor_bundle *desc_bundle;
 323 
 324                 /* Found one.  Set up its bundle structure*/
 325                 desc_bundle = desc->data;
 326                 bundle_id = desc_bundle->id;
 327                 class = desc_bundle->class;
 328 
 329                 /* Done with this bundle descriptor */
 330                 release_manifest_descriptor(desc);
 331 
 332                 /* Ignore any legacy control bundles */
 333                 if (bundle_id == GB_CONTROL_BUNDLE_ID) {
 334                         dev_dbg(&intf->dev, "%s - ignoring control bundle\n",
 335                                 __func__);
 336                         release_cport_descriptors(&intf->manifest_descs,
 337                                                   bundle_id);
 338                         continue;
 339                 }
 340 
 341                 /* Nothing else should have its class set to control class */
 342                 if (class == GREYBUS_CLASS_CONTROL) {
 343                         dev_err(&intf->dev,
 344                                 "bundle %u cannot use control class\n",
 345                                 bundle_id);
 346                         goto cleanup;
 347                 }
 348 
 349                 bundle = gb_bundle_create(intf, bundle_id, class);
 350                 if (!bundle)
 351                         goto cleanup;
 352 
 353                 /*
 354                  * Now go set up this bundle's functions and cports.
 355                  *
 356                  * A 'bundle' represents a device in greybus. It may require
 357                  * multiple cports for its functioning. If we fail to setup any
 358                  * cport of a bundle, we better reject the complete bundle as
 359                  * the device may not be able to function properly then.
 360                  *
 361                  * But, failing to setup a cport of bundle X doesn't mean that
 362                  * the device corresponding to bundle Y will not work properly.
 363                  * Bundles should be treated as separate independent devices.
 364                  *
 365                  * While parsing manifest for an interface, treat bundles as
 366                  * separate entities and don't reject entire interface and its
 367                  * bundles on failing to initialize a cport. But make sure the
 368                  * bundle which needs the cport, gets destroyed properly.
 369                  */
 370                 if (!gb_manifest_parse_cports(bundle)) {
 371                         gb_bundle_destroy(bundle);
 372                         continue;
 373                 }
 374 
 375                 count++;
 376         }
 377 
 378         return count;
 379 cleanup:
 380         /* An error occurred; undo any changes we've made */
 381         list_for_each_entry_safe(bundle, bundle_next, &intf->bundles, links) {
 382                 gb_bundle_destroy(bundle);
 383                 count--;
 384         }
 385         return 0;       /* Error; count should also be 0 */
 386 }
 387 
 388 static bool gb_manifest_parse_interface(struct gb_interface *intf,
 389                                         struct manifest_desc *interface_desc)
 390 {
 391         struct greybus_descriptor_interface *desc_intf = interface_desc->data;
 392         struct gb_control *control = intf->control;
 393         char *str;
 394 
 395         /* Handle the strings first--they can fail */
 396         str = gb_string_get(intf, desc_intf->vendor_stringid);
 397         if (IS_ERR(str))
 398                 return false;
 399         control->vendor_string = str;
 400 
 401         str = gb_string_get(intf, desc_intf->product_stringid);
 402         if (IS_ERR(str))
 403                 goto out_free_vendor_string;
 404         control->product_string = str;
 405 
 406         /* Assign feature flags communicated via manifest */
 407         intf->features = desc_intf->features;
 408 
 409         /* Release the interface descriptor, now that we're done with it */
 410         release_manifest_descriptor(interface_desc);
 411 
 412         /* An interface must have at least one bundle descriptor */
 413         if (!gb_manifest_parse_bundles(intf)) {
 414                 dev_err(&intf->dev, "manifest bundle descriptors not valid\n");
 415                 goto out_err;
 416         }
 417 
 418         return true;
 419 out_err:
 420         kfree(control->product_string);
 421         control->product_string = NULL;
 422 out_free_vendor_string:
 423         kfree(control->vendor_string);
 424         control->vendor_string = NULL;
 425 
 426         return false;
 427 }
 428 
 429 /*
 430  * Parse a buffer containing an interface manifest.
 431  *
 432  * If we find anything wrong with the content/format of the buffer
 433  * we reject it.
 434  *
 435  * The first requirement is that the manifest's version is
 436  * one we can parse.
 437  *
 438  * We make an initial pass through the buffer and identify all of
 439  * the descriptors it contains, keeping track for each its type
 440  * and the location size of its data in the buffer.
 441  *
 442  * Next we scan the descriptors, looking for an interface descriptor;
 443  * there must be exactly one of those.  When found, we record the
 444  * information it contains, and then remove that descriptor (and any
 445  * string descriptors it refers to) from further consideration.
 446  *
 447  * After that we look for the interface's bundles--there must be at
 448  * least one of those.
 449  *
 450  * Returns true if parsing was successful, false otherwise.
 451  */
 452 bool gb_manifest_parse(struct gb_interface *intf, void *data, size_t size)
 453 {
 454         struct greybus_manifest *manifest;
 455         struct greybus_manifest_header *header;
 456         struct greybus_descriptor *desc;
 457         struct manifest_desc *descriptor;
 458         struct manifest_desc *interface_desc = NULL;
 459         u16 manifest_size;
 460         u32 found = 0;
 461         bool result;
 462 
 463         /* Manifest descriptor list should be empty here */
 464         if (WARN_ON(!list_empty(&intf->manifest_descs)))
 465                 return false;
 466 
 467         /* we have to have at _least_ the manifest header */
 468         if (size < sizeof(*header)) {
 469                 dev_err(&intf->dev, "short manifest (%zu < %zu)\n",
 470                         size, sizeof(*header));
 471                 return false;
 472         }
 473 
 474         /* Make sure the size is right */
 475         manifest = data;
 476         header = &manifest->header;
 477         manifest_size = le16_to_cpu(header->size);
 478         if (manifest_size != size) {
 479                 dev_err(&intf->dev, "manifest size mismatch (%zu != %u)\n",
 480                         size, manifest_size);
 481                 return false;
 482         }
 483 
 484         /* Validate major/minor number */
 485         if (header->version_major > GREYBUS_VERSION_MAJOR) {
 486                 dev_err(&intf->dev, "manifest version too new (%u.%u > %u.%u)\n",
 487                         header->version_major, header->version_minor,
 488                         GREYBUS_VERSION_MAJOR, GREYBUS_VERSION_MINOR);
 489                 return false;
 490         }
 491 
 492         /* OK, find all the descriptors */
 493         desc = manifest->descriptors;
 494         size -= sizeof(*header);
 495         while (size) {
 496                 int desc_size;
 497 
 498                 desc_size = identify_descriptor(intf, desc, size);
 499                 if (desc_size < 0) {
 500                         result = false;
 501                         goto out;
 502                 }
 503                 desc = (struct greybus_descriptor *)((char *)desc + desc_size);
 504                 size -= desc_size;
 505         }
 506 
 507         /* There must be a single interface descriptor */
 508         list_for_each_entry(descriptor, &intf->manifest_descs, links) {
 509                 if (descriptor->type == GREYBUS_TYPE_INTERFACE)
 510                         if (!found++)
 511                                 interface_desc = descriptor;
 512         }
 513         if (found != 1) {
 514                 dev_err(&intf->dev, "manifest must have 1 interface descriptor (%u found)\n",
 515                         found);
 516                 result = false;
 517                 goto out;
 518         }
 519 
 520         /* Parse the manifest, starting with the interface descriptor */
 521         result = gb_manifest_parse_interface(intf, interface_desc);
 522 
 523         /*
 524          * We really should have no remaining descriptors, but we
 525          * don't know what newer format manifests might leave.
 526          */
 527         if (result && !list_empty(&intf->manifest_descs))
 528                 dev_info(&intf->dev, "excess descriptors in interface manifest\n");
 529 out:
 530         release_manifest_descriptors(intf);
 531 
 532         return result;
 533 }