lib/efi_loader/efi_variable.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  EFI utils
   4  *
   5  *  Copyright (c) 2017 Rob Clark
   6  */
   7
   8 #include <env.h>
   9 #include <malloc.h>
  10 #include <charset.h>
  11 #include <efi_loader.h>
  12 #include <hexdump.h>
  13 #include <env_internal.h>
  14 #include <search.h>
  15 #include <uuid.h>
  16
  17 #define READ_ONLY BIT(31)
  18
  19 /*
  20  * Mapping between EFI variables and u-boot variables:
  21  *
  22  *   efi_$guid_$varname = {attributes}(type)value
  23  *
  24  * For example:
  25  *
  26  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
  27  *      "{ro,boot,run}(blob)0000000000000000"
  28  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
  29  *      "(blob)00010000"
  30  *
  31  * The attributes are a comma separated list of these possible
  32  * attributes:
  33  *
  34  *   + ro   - read-only
  35  *   + boot - boot-services access
  36  *   + run  - runtime access
  37  *
  38  * NOTE: with current implementation, no variables are available after
  39  * ExitBootServices, and all are persisted (if possible).
  40  *
  41  * If not specified, the attributes default to "{boot}".
  42  *
  43  * The required type is one of:
  44  *
  45  *   + utf8 - raw utf8 string
  46  *   + blob - arbitrary length hex string
  47  *
  48  * Maybe a utf16 type would be useful to for a string value to be auto
  49  * converted to utf16?
  50  */
  51
  52 #define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_"))
  53
  54 /**
  55  * efi_to_native() - convert the UEFI variable name and vendor GUID to U-Boot
  56  *                   variable name
  57  *
  58  * The U-Boot variable name is a concatenation of prefix 'efi', the hexstring
  59  * encoded vendor GUID, and the UTF-8 encoded UEFI variable name separated by
  60  * underscores, e.g. 'efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder'.
  61  *
  62  * @native:             pointer to pointer to U-Boot variable name
  63  * @variable_name:      UEFI variable name
  64  * @vendor:             vendor GUID
  65  * Return:              status code
  66  */
  67 static efi_status_t efi_to_native(char **native, const u16 *variable_name,
  68                                   const efi_guid_t *vendor)
  69 {
  70         size_t len;
  71         char *pos;
  72
  73         len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
  74         *native = malloc(len);
  75         if (!*native)
  76                 return EFI_OUT_OF_RESOURCES;
  77
  78         pos = *native;
  79         pos += sprintf(pos, "efi_%pUl_", vendor);
  80         utf16_utf8_strcpy(&pos, variable_name);
  81
  82         return EFI_SUCCESS;
  83 }
  84
  85 /**
  86  * prefix() - skip over prefix
  87  *
  88  * Skip over a prefix string.
  89  *
  90  * @str:        string with prefix
  91  * @prefix:     prefix string
  92  * Return:      string without prefix, or NULL if prefix not found
  93  */
  94 static const char *prefix(const char *str, const char *prefix)
  95 {
  96         size_t n = strlen(prefix);
  97         if (!strncmp(prefix, str, n))
  98                 return str + n;
  99         return NULL;
 100 }
 101
 102 /**
 103  * parse_attr() - decode attributes part of variable value
 104  *
 105  * Convert the string encoded attributes of a UEFI variable to a bit mask.
 106  * TODO: Several attributes are not supported.
 107  *
 108  * @str:        value of U-Boot variable
 109  * @attrp:      pointer to UEFI attributes
 110  * Return:      pointer to remainder of U-Boot variable value
 111  */
 112 static const char *parse_attr(const char *str, u32 *attrp)
 113 {
 114         u32 attr = 0;
 115         char sep = '{';
 116
 117         if (*str != '{') {
 118                 *attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
 119                 return str;
 120         }
 121
 122         while (*str == sep) {
 123                 const char *s;
 124
 125                 str++;
 126
 127                 if ((s = prefix(str, "ro"))) {
 128                         attr |= READ_ONLY;
 129                 } else if ((s = prefix(str, "nv"))) {
 130                         attr |= EFI_VARIABLE_NON_VOLATILE;
 131                 } else if ((s = prefix(str, "boot"))) {
 132                         attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
 133                 } else if ((s = prefix(str, "run"))) {
 134                         attr |= EFI_VARIABLE_RUNTIME_ACCESS;
 135                 } else {
 136                         printf("invalid attribute: %s\n", str);
 137                         break;
 138                 }
 139
 140                 str = s;
 141                 sep = ',';
 142         }
 143
 144         str++;
 145
 146         *attrp = attr;
 147
 148         return str;
 149 }
 150
 151 /**
 152  * efi_get_variable() - retrieve value of a UEFI variable
 153  *
 154  * This function implements the GetVariable runtime service.
 155  *
 156  * See the Unified Extensible Firmware Interface (UEFI) specification for
 157  * details.
 158  *
 159  * @variable_name:      name of the variable
 160  * @vendor:             vendor GUID
 161  * @attributes:         attributes of the variable
 162  * @data_size:          size of the buffer to which the variable value is copied
 163  * @data:               buffer to which the variable value is copied
 164  * Return:              status code
 165  */
 166 efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
 167                                      const efi_guid_t *vendor, u32 *attributes,
 168                                      efi_uintn_t *data_size, void *data)
 169 {
 170         char *native_name;
 171         efi_status_t ret;
 172         unsigned long in_size;
 173         const char *val, *s;
 174         u32 attr;
 175
 176         EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
 177                   data_size, data);
 178
 179         if (!variable_name || !vendor || !data_size)
 180                 return EFI_EXIT(EFI_INVALID_PARAMETER);
 181
 182         ret = efi_to_native(&native_name, variable_name, vendor);
 183         if (ret)
 184                 return EFI_EXIT(ret);
 185
 186         EFI_PRINT("get '%s'\n", native_name);
 187
 188         val = env_get(native_name);
 189         free(native_name);
 190         if (!val)
 191                 return EFI_EXIT(EFI_NOT_FOUND);
 192
 193         val = parse_attr(val, &attr);
 194
 195         in_size = *data_size;
 196
 197         if ((s = prefix(val, "(blob)"))) {
 198                 size_t len = strlen(s);
 199
 200                 /* number of hexadecimal digits must be even */
 201                 if (len & 1)
 202                         return EFI_EXIT(EFI_DEVICE_ERROR);
 203
 204                 /* two characters per byte: */
 205                 len /= 2;
 206                 *data_size = len;
 207
 208                 if (in_size < len) {
 209                         ret = EFI_BUFFER_TOO_SMALL;
 210                         goto out;
 211                 }
 212
 213                 if (!data)
 214                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 215
 216                 if (hex2bin(data, s, len))
 217                         return EFI_EXIT(EFI_DEVICE_ERROR);
 218
 219                 EFI_PRINT("got value: \"%s\"\n", s);
 220         } else if ((s = prefix(val, "(utf8)"))) {
 221                 unsigned len = strlen(s) + 1;
 222
 223                 *data_size = len;
 224
 225                 if (in_size < len) {
 226                         ret = EFI_BUFFER_TOO_SMALL;
 227                         goto out;
 228                 }
 229
 230                 if (!data)
 231                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 232
 233                 memcpy(data, s, len);
 234                 ((char *)data)[len] = '\0';
 235
 236                 EFI_PRINT("got value: \"%s\"\n", (char *)data);
 237         } else {
 238                 EFI_PRINT("invalid value: '%s'\n", val);
 239                 return EFI_EXIT(EFI_DEVICE_ERROR);
 240         }
 241
 242 out:
 243         if (attributes)
 244                 *attributes = attr & EFI_VARIABLE_MASK;
 245
 246         return EFI_EXIT(ret);
 247 }
 248
 249 static char *efi_variables_list;
 250 static char *efi_cur_variable;
 251
 252 /**
 253  * parse_uboot_variable() - parse a u-boot variable and get uefi-related
 254  *                          information
 255  * @variable:           whole data of u-boot variable (ie. name=value)
 256  * @variable_name_size: size of variable_name buffer in byte
 257  * @variable_name:      name of uefi variable in u16, null-terminated
 258  * @vendor:             vendor's guid
 259  * @attributes:         attributes
 260  *
 261  * A uefi variable is encoded into a u-boot variable as described above.
 262  * This function parses such a u-boot variable and retrieve uefi-related
 263  * information into respective parameters. In return, variable_name_size
 264  * is the size of variable name including NULL.
 265  *
 266  * Return:              EFI_SUCCESS if parsing is OK, EFI_NOT_FOUND when
 267  *                      the entire variable list has been returned,
 268  *                      otherwise non-zero status code
 269  */
 270 static efi_status_t parse_uboot_variable(char *variable,
 271                                          efi_uintn_t *variable_name_size,
 272                                          u16 *variable_name,
 273                                          const efi_guid_t *vendor,
 274                                          u32 *attributes)
 275 {
 276         char *guid, *name, *end, c;
 277         unsigned long name_len;
 278         u16 *p;
 279
 280         guid = strchr(variable, '_');
 281         if (!guid)
 282                 return EFI_INVALID_PARAMETER;
 283         guid++;
 284         name = strchr(guid, '_');
 285         if (!name)
 286                 return EFI_INVALID_PARAMETER;
 287         name++;
 288         end = strchr(name, '=');
 289         if (!end)
 290                 return EFI_INVALID_PARAMETER;
 291
 292         name_len = end - name;
 293         if (*variable_name_size < (name_len + 1)) {
 294                 *variable_name_size = name_len + 1;
 295                 return EFI_BUFFER_TOO_SMALL;
 296         }
 297         end++; /* point to value */
 298
 299         /* variable name */
 300         p = variable_name;
 301         utf8_utf16_strncpy(&p, name, name_len);
 302         variable_name[name_len] = 0;
 303         *variable_name_size = name_len + 1;
 304
 305         /* guid */
 306         c = *(name - 1);
 307         *(name - 1) = '\0'; /* guid need be null-terminated here */
 308         uuid_str_to_bin(guid, (unsigned char *)vendor, UUID_STR_FORMAT_GUID);
 309         *(name - 1) = c;
 310
 311         /* attributes */
 312         parse_attr(end, attributes);
 313
 314         return EFI_SUCCESS;
 315 }
 316
 317 /**
 318  * efi_get_next_variable_name() - enumerate the current variable names
 319  *
 320  * @variable_name_size: size of variable_name buffer in byte
 321  * @variable_name:      name of uefi variable's name in u16
 322  * @vendor:             vendor's guid
 323  *
 324  * This function implements the GetNextVariableName service.
 325  *
 326  * See the Unified Extensible Firmware Interface (UEFI) specification for
 327  * details.
 328  *
 329  * Return: status code
 330  */
 331 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
 332                                                u16 *variable_name,
 333                                                const efi_guid_t *vendor)
 334 {
 335         char *native_name, *variable;
 336         ssize_t name_len, list_len;
 337         char regex[256];
 338         char * const regexlist[] = {regex};
 339         u32 attributes;
 340         int i;
 341         efi_status_t ret;
 342
 343         EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
 344
 345         if (!variable_name_size || !variable_name || !vendor)
 346                 return EFI_EXIT(EFI_INVALID_PARAMETER);
 347
 348         if (variable_name[0]) {
 349                 /* check null-terminated string */
 350                 for (i = 0; i < *variable_name_size; i++)
 351                         if (!variable_name[i])
 352                                 break;
 353                 if (i >= *variable_name_size)
 354                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 355
 356                 /* search for the last-returned variable */
 357                 ret = efi_to_native(&native_name, variable_name, vendor);
 358                 if (ret)
 359                         return EFI_EXIT(ret);
 360
 361                 name_len = strlen(native_name);
 362                 for (variable = efi_variables_list; variable && *variable;) {
 363                         if (!strncmp(variable, native_name, name_len) &&
 364                             variable[name_len] == '=')
 365                                 break;
 366
 367                         variable = strchr(variable, '\n');
 368                         if (variable)
 369                                 variable++;
 370                 }
 371
 372                 free(native_name);
 373                 if (!(variable && *variable))
 374                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 375
 376                 /* next variable */
 377                 variable = strchr(variable, '\n');
 378                 if (variable)
 379                         variable++;
 380                 if (!(variable && *variable))
 381                         return EFI_EXIT(EFI_NOT_FOUND);
 382         } else {
 383                 /*
 384                  *new search: free a list used in the previous search
 385                  */
 386                 free(efi_variables_list);
 387                 efi_variables_list = NULL;
 388                 efi_cur_variable = NULL;
 389
 390                 snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_.*");
 391                 list_len = hexport_r(&env_htab, '\n',
 392                                      H_MATCH_REGEX | H_MATCH_KEY,
 393                                      &efi_variables_list, 0, 1, regexlist);
 394                 /* 1 indicates that no match was found */
 395                 if (list_len <= 1)
 396                         return EFI_EXIT(EFI_NOT_FOUND);
 397
 398                 variable = efi_variables_list;
 399         }
 400
 401         ret = parse_uboot_variable(variable, variable_name_size, variable_name,
 402                                    vendor, &attributes);
 403
 404         return EFI_EXIT(ret);
 405 }
 406
 407 /**
 408  * efi_set_variable() - set value of a UEFI variable
 409  *
 410  * This function implements the SetVariable runtime service.
 411  *
 412  * See the Unified Extensible Firmware Interface (UEFI) specification for
 413  * details.
 414  *
 415  * @variable_name:      name of the variable
 416  * @vendor:             vendor GUID
 417  * @attributes:         attributes of the variable
 418  * @data_size:          size of the buffer with the variable value
 419  * @data:               buffer with the variable value
 420  * Return:              status code
 421  */
 422 efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
 423                                      const efi_guid_t *vendor, u32 attributes,
 424                                      efi_uintn_t data_size, const void *data)
 425 {
 426         char *native_name = NULL, *val = NULL, *s;
 427         efi_status_t ret = EFI_SUCCESS;
 428         u32 attr;
 429
 430         EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
 431                   data_size, data);
 432
 433         /* TODO: implement APPEND_WRITE */
 434         if (!variable_name || !*variable_name || !vendor ||
 435             ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
 436              !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)) ||
 437             (attributes & EFI_VARIABLE_APPEND_WRITE)) {
 438                 ret = EFI_INVALID_PARAMETER;
 439                 goto out;
 440         }
 441
 442         ret = efi_to_native(&native_name, variable_name, vendor);
 443         if (ret)
 444                 goto out;
 445
 446 #define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)
 447
 448         if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
 449                 /* delete the variable: */
 450                 env_set(native_name, NULL);
 451                 ret = EFI_SUCCESS;
 452                 goto out;
 453         }
 454
 455         val = env_get(native_name);
 456         if (val) {
 457                 parse_attr(val, &attr);
 458
 459                 /* We should not free val */
 460                 val = NULL;
 461                 if (attr & READ_ONLY) {
 462                         ret = EFI_WRITE_PROTECTED;
 463                         goto out;
 464                 }
 465
 466                 /*
 467                  * attributes won't be changed
 468                  * TODO: take care of APPEND_WRITE once supported
 469                  */
 470                 if (attr != attributes) {
 471                         ret = EFI_INVALID_PARAMETER;
 472                         goto out;
 473                 }
 474         }
 475
 476         val = malloc(2 * data_size + strlen("{ro,run,boot,nv}(blob)") + 1);
 477         if (!val) {
 478                 ret = EFI_OUT_OF_RESOURCES;
 479                 goto out;
 480         }
 481
 482         s = val;
 483
 484         /*
 485          * store attributes
 486          * TODO: several attributes are not supported
 487          */
 488         attributes &= (EFI_VARIABLE_NON_VOLATILE |
 489                        EFI_VARIABLE_BOOTSERVICE_ACCESS |
 490                        EFI_VARIABLE_RUNTIME_ACCESS);
 491         s += sprintf(s, "{");
 492         while (attributes) {
 493                 u32 attr = 1 << (ffs(attributes) - 1);
 494
 495                 if (attr == EFI_VARIABLE_NON_VOLATILE)
 496                         s += sprintf(s, "nv");
 497                 else if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
 498                         s += sprintf(s, "boot");
 499                 else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
 500                         s += sprintf(s, "run");
 501
 502                 attributes &= ~attr;
 503                 if (attributes)
 504                         s += sprintf(s, ",");
 505         }
 506         s += sprintf(s, "}");
 507
 508         /* store payload: */
 509         s += sprintf(s, "(blob)");
 510         s = bin2hex(s, data, data_size);
 511         *s = '\0';
 512
 513         EFI_PRINT("setting: %s=%s\n", native_name, val);
 514
 515         if (env_set(native_name, val))
 516                 ret = EFI_DEVICE_ERROR;
 517
 518 out:
 519         free(native_name);
 520         free(val);
 521
 522         return EFI_EXIT(ret);
 523 }
 524
 525 /**
 526  * efi_query_variable_info() - get information about EFI variables
 527  *
 528  * This function implements the QueryVariableInfo() runtime service.
 529  *
 530  * See the Unified Extensible Firmware Interface (UEFI) specification for
 531  * details.
 532  *
 533  * @attributes:                         bitmask to select variables to be
 534  *                                      queried
 535  * @maximum_variable_storage_size:      maximum size of storage area for the
 536  *                                      selected variable types
 537  * @remaining_variable_storage_size:    remaining size of storage are for the
 538  *                                      selected variable types
 539  * @maximum_variable_size:              maximum size of a variable of the
 540  *                                      selected type
 541  * Returns:                             status code
 542  */
 543 efi_status_t __efi_runtime EFIAPI efi_query_variable_info(
 544                         u32 attributes,
 545                         u64 *maximum_variable_storage_size,
 546                         u64 *remaining_variable_storage_size,
 547                         u64 *maximum_variable_size)
 548 {
 549         return EFI_UNSUPPORTED;
 550 }
 551
 552 /**
 553  * efi_get_variable_runtime() - runtime implementation of GetVariable()
 554  *
 555  * @variable_name:      name of the variable
 556  * @vendor:             vendor GUID
 557  * @attributes:         attributes of the variable
 558  * @data_size:          size of the buffer to which the variable value is copied
 559  * @data:               buffer to which the variable value is copied
 560  * Return:              status code
 561  */
 562 static efi_status_t __efi_runtime EFIAPI
 563 efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
 564                          u32 *attributes, efi_uintn_t *data_size, void *data)
 565 {
 566         return EFI_UNSUPPORTED;
 567 }
 568
 569 /**
 570  * efi_get_next_variable_name_runtime() - runtime implementation of
 571  *                                        GetNextVariable()
 572  *
 573  * @variable_name_size: size of variable_name buffer in byte
 574  * @variable_name:      name of uefi variable's name in u16
 575  * @vendor:             vendor's guid
 576  * Return: status code
 577  */
 578 static efi_status_t __efi_runtime EFIAPI
 579 efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
 580                                    u16 *variable_name, const efi_guid_t *vendor)
 581 {
 582         return EFI_UNSUPPORTED;
 583 }
 584
 585 /**
 586  * efi_set_variable_runtime() - runtime implementation of SetVariable()
 587  *
 588  * @variable_name:      name of the variable
 589  * @vendor:             vendor GUID
 590  * @attributes:         attributes of the variable
 591  * @data_size:          size of the buffer with the variable value
 592  * @data:               buffer with the variable value
 593  * Return:              status code
 594  */
 595 static efi_status_t __efi_runtime EFIAPI
 596 efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
 597                          u32 attributes, efi_uintn_t data_size,
 598                          const void *data)
 599 {
 600         return EFI_UNSUPPORTED;
 601 }
 602
 603 /**
 604  * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
 605  */
 606 void efi_variables_boot_exit_notify(void)
 607 {
 608         efi_runtime_services.get_variable = efi_get_variable_runtime;
 609         efi_runtime_services.get_next_variable_name =
 610                                 efi_get_next_variable_name_runtime;
 611         efi_runtime_services.set_variable = efi_set_variable_runtime;
 612         efi_update_table_header_crc32(&efi_runtime_services.hdr);
 613 }
 614
 615 /**
 616  * efi_init_variables() - initialize variable services
 617  *
 618  * Return:      status code
 619  */
 620 efi_status_t efi_init_variables(void)
 621 {
 622         return EFI_SUCCESS;
 623 }