lib/efi_loader/efi_variable.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * UEFI runtime variable services
   4  *
   5  * Copyright (c) 2017 Rob Clark
   6  */
   7
   8 #include <common.h>
   9 #include <efi_loader.h>
  10 #include <env_internal.h>
  11 #include <hexdump.h>
  12 #include <malloc.h>
  13 #include <rtc.h>
  14 #include <search.h>
  15 #include <crypto/pkcs7_parser.h>
  16 #include <linux/compat.h>
  17 #include <u-boot/crc.h>
  18
  19 enum efi_secure_mode {
  20         EFI_MODE_SETUP,
  21         EFI_MODE_USER,
  22         EFI_MODE_AUDIT,
  23         EFI_MODE_DEPLOYED,
  24 };
  25
  26 const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
  27 static bool efi_secure_boot;
  28 static int efi_secure_mode;
  29 static u8 efi_vendor_keys;
  30
  31 #define READ_ONLY BIT(31)
  32
  33 static efi_status_t efi_get_variable_common(u16 *variable_name,
  34                                             const efi_guid_t *vendor,
  35                                             u32 *attributes,
  36                                             efi_uintn_t *data_size, void *data);
  37
  38 static efi_status_t efi_set_variable_common(u16 *variable_name,
  39                                             const efi_guid_t *vendor,
  40                                             u32 attributes,
  41                                             efi_uintn_t data_size,
  42                                             const void *data,
  43                                             bool ro_check);
  44
  45 /*
  46  * Mapping between EFI variables and u-boot variables:
  47  *
  48  *   efi_$guid_$varname = {attributes}(type)value
  49  *
  50  * For example:
  51  *
  52  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
  53  *      "{ro,boot,run}(blob)0000000000000000"
  54  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
  55  *      "(blob)00010000"
  56  *
  57  * The attributes are a comma separated list of these possible
  58  * attributes:
  59  *
  60  *   + ro   - read-only
  61  *   + boot - boot-services access
  62  *   + run  - runtime access
  63  *
  64  * NOTE: with current implementation, no variables are available after
  65  * ExitBootServices, and all are persisted (if possible).
  66  *
  67  * If not specified, the attributes default to "{boot}".
  68  *
  69  * The required type is one of:
  70  *
  71  *   + utf8 - raw utf8 string
  72  *   + blob - arbitrary length hex string
  73  *
  74  * Maybe a utf16 type would be useful to for a string value to be auto
  75  * converted to utf16?
  76  */
  77
  78 #define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_"))
  79
  80 /**
  81  * efi_to_native() - convert the UEFI variable name and vendor GUID to U-Boot
  82  *                   variable name
  83  *
  84  * The U-Boot variable name is a concatenation of prefix 'efi', the hexstring
  85  * encoded vendor GUID, and the UTF-8 encoded UEFI variable name separated by
  86  * underscores, e.g. 'efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder'.
  87  *
  88  * @native:             pointer to pointer to U-Boot variable name
  89  * @variable_name:      UEFI variable name
  90  * @vendor:             vendor GUID
  91  * Return:              status code
  92  */
  93 static efi_status_t efi_to_native(char **native, const u16 *variable_name,
  94                                   const efi_guid_t *vendor)
  95 {
  96         size_t len;
  97         char *pos;
  98
  99         len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
 100         *native = malloc(len);
 101         if (!*native)
 102                 return EFI_OUT_OF_RESOURCES;
 103
 104         pos = *native;
 105         pos += sprintf(pos, "efi_%pUl_", vendor);
 106         utf16_utf8_strcpy(&pos, variable_name);
 107
 108         return EFI_SUCCESS;
 109 }
 110
 111 /**
 112  * prefix() - skip over prefix
 113  *
 114  * Skip over a prefix string.
 115  *
 116  * @str:        string with prefix
 117  * @prefix:     prefix string
 118  * Return:      string without prefix, or NULL if prefix not found
 119  */
 120 static const char *prefix(const char *str, const char *prefix)
 121 {
 122         size_t n = strlen(prefix);
 123         if (!strncmp(prefix, str, n))
 124                 return str + n;
 125         return NULL;
 126 }
 127
 128 /**
 129  * parse_attr() - decode attributes part of variable value
 130  *
 131  * Convert the string encoded attributes of a UEFI variable to a bit mask.
 132  * TODO: Several attributes are not supported.
 133  *
 134  * @str:        value of U-Boot variable
 135  * @attrp:      pointer to UEFI attributes
 136  * @timep:      pointer to time attribute
 137  * Return:      pointer to remainder of U-Boot variable value
 138  */
 139 static const char *parse_attr(const char *str, u32 *attrp, u64 *timep)
 140 {
 141         u32 attr = 0;
 142         char sep = '{';
 143
 144         if (*str != '{') {
 145                 *attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
 146                 return str;
 147         }
 148
 149         while (*str == sep) {
 150                 const char *s;
 151
 152                 str++;
 153
 154                 if ((s = prefix(str, "ro"))) {
 155                         attr |= READ_ONLY;
 156                 } else if ((s = prefix(str, "nv"))) {
 157                         attr |= EFI_VARIABLE_NON_VOLATILE;
 158                 } else if ((s = prefix(str, "boot"))) {
 159                         attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
 160                 } else if ((s = prefix(str, "run"))) {
 161                         attr |= EFI_VARIABLE_RUNTIME_ACCESS;
 162                 } else if ((s = prefix(str, "time="))) {
 163                         attr |= EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS;
 164                         hex2bin((u8 *)timep, s, sizeof(*timep));
 165                         s += sizeof(*timep) * 2;
 166                 } else if (*str == '}') {
 167                         break;
 168                 } else {
 169                         printf("invalid attribute: %s\n", str);
 170                         break;
 171                 }
 172
 173                 str = s;
 174                 sep = ',';
 175         }
 176
 177         str++;
 178
 179         *attrp = attr;
 180
 181         return str;
 182 }
 183
 184 /**
 185  * efi_set_secure_state - modify secure boot state variables
 186  * @sec_boot:           value of SecureBoot
 187  * @setup_mode:         value of SetupMode
 188  * @audit_mode:         value of AuditMode
 189  * @deployed_mode:      value of DeployedMode
 190  *
 191  * Modify secure boot stat-related variables as indicated.
 192  *
 193  * Return:              status code
 194  */
 195 static efi_status_t efi_set_secure_state(int sec_boot, int setup_mode,
 196                                          int audit_mode, int deployed_mode)
 197 {
 198         u32 attributes;
 199         efi_status_t ret;
 200
 201         attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
 202                      EFI_VARIABLE_RUNTIME_ACCESS |
 203                      READ_ONLY;
 204         ret = efi_set_variable_common(L"SecureBoot", &efi_global_variable_guid,
 205                                       attributes, sizeof(sec_boot), &sec_boot,
 206                                       false);
 207         if (ret != EFI_SUCCESS)
 208                 goto err;
 209
 210         ret = efi_set_variable_common(L"SetupMode", &efi_global_variable_guid,
 211                                       attributes, sizeof(setup_mode),
 212                                       &setup_mode, false);
 213         if (ret != EFI_SUCCESS)
 214                 goto err;
 215
 216         ret = efi_set_variable_common(L"AuditMode", &efi_global_variable_guid,
 217                                       attributes, sizeof(audit_mode),
 218                                       &audit_mode, false);
 219         if (ret != EFI_SUCCESS)
 220                 goto err;
 221
 222         ret = efi_set_variable_common(L"DeployedMode",
 223                                       &efi_global_variable_guid, attributes,
 224                                       sizeof(deployed_mode), &deployed_mode,
 225                                       false);
 226 err:
 227         return ret;
 228 }
 229
 230 /**
 231  * efi_transfer_secure_state - handle a secure boot state transition
 232  * @mode:       new state
 233  *
 234  * Depending on @mode, secure boot related variables are updated.
 235  * Those variables are *read-only* for users, efi_set_variable_common()
 236  * is called here.
 237  *
 238  * Return:      status code
 239  */
 240 static efi_status_t efi_transfer_secure_state(enum efi_secure_mode mode)
 241 {
 242         efi_status_t ret;
 243
 244         debug("Switching secure state from %d to %d\n", efi_secure_mode, mode);
 245
 246         if (mode == EFI_MODE_DEPLOYED) {
 247                 ret = efi_set_secure_state(1, 0, 0, 1);
 248                 if (ret != EFI_SUCCESS)
 249                         goto err;
 250
 251                 efi_secure_boot = true;
 252         } else if (mode == EFI_MODE_AUDIT) {
 253                 ret = efi_set_variable_common(L"PK", &efi_global_variable_guid,
 254                                               EFI_VARIABLE_BOOTSERVICE_ACCESS |
 255                                               EFI_VARIABLE_RUNTIME_ACCESS,
 256                                               0, NULL, false);
 257                 if (ret != EFI_SUCCESS)
 258                         goto err;
 259
 260                 ret = efi_set_secure_state(0, 1, 1, 0);
 261                 if (ret != EFI_SUCCESS)
 262                         goto err;
 263
 264                 efi_secure_boot = true;
 265         } else if (mode == EFI_MODE_USER) {
 266                 ret = efi_set_secure_state(1, 0, 0, 0);
 267                 if (ret != EFI_SUCCESS)
 268                         goto err;
 269
 270                 efi_secure_boot = true;
 271         } else if (mode == EFI_MODE_SETUP) {
 272                 ret = efi_set_secure_state(0, 1, 0, 0);
 273                 if (ret != EFI_SUCCESS)
 274                         goto err;
 275         } else {
 276                 return EFI_INVALID_PARAMETER;
 277         }
 278
 279         efi_secure_mode = mode;
 280
 281         return EFI_SUCCESS;
 282
 283 err:
 284         /* TODO: What action should be taken here? */
 285         printf("ERROR: Secure state transition failed\n");
 286         return ret;
 287 }
 288
 289 /**
 290  * efi_init_secure_state - initialize secure boot state
 291  *
 292  * Return:      status code
 293  */
 294 static efi_status_t efi_init_secure_state(void)
 295 {
 296         enum efi_secure_mode mode;
 297         efi_uintn_t size;
 298         efi_status_t ret;
 299
 300         /*
 301          * TODO:
 302          * Since there is currently no "platform-specific" installation
 303          * method of Platform Key, we can't say if VendorKeys is 0 or 1
 304          * precisely.
 305          */
 306
 307         size = 0;
 308         ret = efi_get_variable_common(L"PK", &efi_global_variable_guid,
 309                                       NULL, &size, NULL);
 310         if (ret == EFI_BUFFER_TOO_SMALL) {
 311                 if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT))
 312                         mode = EFI_MODE_USER;
 313                 else
 314                         mode = EFI_MODE_SETUP;
 315
 316                 efi_vendor_keys = 0;
 317         } else if (ret == EFI_NOT_FOUND) {
 318                 mode = EFI_MODE_SETUP;
 319                 efi_vendor_keys = 1;
 320         } else {
 321                 goto err;
 322         }
 323
 324         ret = efi_transfer_secure_state(mode);
 325         if (ret == EFI_SUCCESS)
 326                 ret = efi_set_variable_common(L"VendorKeys",
 327                                               &efi_global_variable_guid,
 328                                               EFI_VARIABLE_BOOTSERVICE_ACCESS |
 329                                               EFI_VARIABLE_RUNTIME_ACCESS |
 330                                               READ_ONLY,
 331                                               sizeof(efi_vendor_keys),
 332                                               &efi_vendor_keys, false);
 333
 334 err:
 335         return ret;
 336 }
 337
 338 /**
 339  * efi_secure_boot_enabled - return if secure boot is enabled or not
 340  *
 341  * Return:      true if enabled, false if disabled
 342  */
 343 bool efi_secure_boot_enabled(void)
 344 {
 345         return efi_secure_boot;
 346 }
 347
 348 #ifdef CONFIG_EFI_SECURE_BOOT
 349 static u8 pkcs7_hdr[] = {
 350         /* SEQUENCE */
 351         0x30, 0x82, 0x05, 0xc7,
 352         /* OID: pkcs7-signedData */
 353         0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x02,
 354         /* Context Structured? */
 355         0xa0, 0x82, 0x05, 0xb8,
 356 };
 357
 358 /**
 359  * efi_variable_parse_signature - parse a signature in variable
 360  * @buf:        Pointer to variable's value
 361  * @buflen:     Length of @buf
 362  *
 363  * Parse a signature embedded in variable's value and instantiate
 364  * a pkcs7_message structure. Since pkcs7_parse_message() accepts only
 365  * pkcs7's signedData, some header needed be prepended for correctly
 366  * parsing authentication data, particularly for variable's.
 367  *
 368  * Return:      Pointer to pkcs7_message structure on success, NULL on error
 369  */
 370 static struct pkcs7_message *efi_variable_parse_signature(const void *buf,
 371                                                           size_t buflen)
 372 {
 373         u8 *ebuf;
 374         size_t ebuflen, len;
 375         struct pkcs7_message *msg;
 376
 377         /*
 378          * This is the best assumption to check if the binary is
 379          * already in a form of pkcs7's signedData.
 380          */
 381         if (buflen > sizeof(pkcs7_hdr) &&
 382             !memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) {
 383                 msg = pkcs7_parse_message(buf, buflen);
 384                 goto out;
 385         }
 386
 387         /*
 388          * Otherwise, we should add a dummy prefix sequence for pkcs7
 389          * message parser to be able to process.
 390          * NOTE: EDK2 also uses similar hack in WrapPkcs7Data()
 391          * in CryptoPkg/Library/BaseCryptLib/Pk/CryptPkcs7VerifyCommon.c
 392          * TODO:
 393          * The header should be composed in a more refined manner.
 394          */
 395         debug("Makeshift prefix added to authentication data\n");
 396         ebuflen = sizeof(pkcs7_hdr) + buflen;
 397         if (ebuflen <= 0x7f) {
 398                 debug("Data is too short\n");
 399                 return NULL;
 400         }
 401
 402         ebuf = malloc(ebuflen);
 403         if (!ebuf) {
 404                 debug("Out of memory\n");
 405                 return NULL;
 406         }
 407
 408         memcpy(ebuf, pkcs7_hdr, sizeof(pkcs7_hdr));
 409         memcpy(ebuf + sizeof(pkcs7_hdr), buf, buflen);
 410         len = ebuflen - 4;
 411         ebuf[2] = (len >> 8) & 0xff;
 412         ebuf[3] = len & 0xff;
 413         len = ebuflen - 0x13;
 414         ebuf[0x11] = (len >> 8) & 0xff;
 415         ebuf[0x12] = len & 0xff;
 416
 417         msg = pkcs7_parse_message(ebuf, ebuflen);
 418
 419         free(ebuf);
 420
 421 out:
 422         if (IS_ERR(msg))
 423                 return NULL;
 424
 425         return msg;
 426 }
 427
 428 /**
 429  * efi_variable_authenticate - authenticate a variable
 430  * @variable:   Variable name in u16
 431  * @vendor:     Guid of variable
 432  * @data_size:  Size of @data
 433  * @data:       Pointer to variable's value
 434  * @given_attr: Attributes to be given at SetVariable()
 435  * @env_attr:   Attributes that an existing variable holds
 436  * @time:       signed time that an existing variable holds
 437  *
 438  * Called by efi_set_variable() to verify that the input is correct.
 439  * Will replace the given data pointer with another that points to
 440  * the actual data to store in the internal memory.
 441  * On success, @data and @data_size will be replaced with variable's
 442  * actual data, excluding authentication data, and its size, and variable's
 443  * attributes and signed time will also be returned in @env_attr and @time,
 444  * respectively.
 445  *
 446  * Return:      status code
 447  */
 448 static efi_status_t efi_variable_authenticate(u16 *variable,
 449                                               const efi_guid_t *vendor,
 450                                               efi_uintn_t *data_size,
 451                                               const void **data, u32 given_attr,
 452                                               u32 *env_attr, u64 *time)
 453 {
 454         const struct efi_variable_authentication_2 *auth;
 455         struct efi_signature_store *truststore, *truststore2;
 456         struct pkcs7_message *var_sig;
 457         struct efi_image_regions *regs;
 458         struct efi_time timestamp;
 459         struct rtc_time tm;
 460         u64 new_time;
 461         efi_status_t ret;
 462
 463         var_sig = NULL;
 464         truststore = NULL;
 465         truststore2 = NULL;
 466         regs = NULL;
 467         ret = EFI_SECURITY_VIOLATION;
 468
 469         if (*data_size < sizeof(struct efi_variable_authentication_2))
 470                 goto err;
 471
 472         /* authentication data */
 473         auth = *data;
 474         if (*data_size < (sizeof(auth->time_stamp)
 475                                 + auth->auth_info.hdr.dwLength))
 476                 goto err;
 477
 478         if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
 479                 goto err;
 480
 481         *data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
 482         *data_size -= (sizeof(auth->time_stamp)
 483                                 + auth->auth_info.hdr.dwLength);
 484
 485         memcpy(&timestamp, &auth->time_stamp, sizeof(timestamp));
 486         memset(&tm, 0, sizeof(tm));
 487         tm.tm_year = timestamp.year;
 488         tm.tm_mon = timestamp.month;
 489         tm.tm_mday = timestamp.day;
 490         tm.tm_hour = timestamp.hour;
 491         tm.tm_min = timestamp.minute;
 492         tm.tm_sec = timestamp.second;
 493         new_time = rtc_mktime(&tm);
 494
 495         if (!efi_secure_boot_enabled()) {
 496                 /* finished checking */
 497                 *time = new_time;
 498                 return EFI_SUCCESS;
 499         }
 500
 501         if (new_time <= *time)
 502                 goto err;
 503
 504         /* data to be digested */
 505         regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 5, 1);
 506         if (!regs)
 507                 goto err;
 508         regs->max = 5;
 509         efi_image_region_add(regs, (uint8_t *)variable,
 510                              (uint8_t *)variable
 511                                 + u16_strlen(variable) * sizeof(u16), 1);
 512         efi_image_region_add(regs, (uint8_t *)vendor,
 513                              (uint8_t *)vendor + sizeof(*vendor), 1);
 514         efi_image_region_add(regs, (uint8_t *)&given_attr,
 515                              (uint8_t *)&given_attr + sizeof(given_attr), 1);
 516         efi_image_region_add(regs, (uint8_t *)&timestamp,
 517                              (uint8_t *)&timestamp + sizeof(timestamp), 1);
 518         efi_image_region_add(regs, (uint8_t *)*data,
 519                              (uint8_t *)*data + *data_size, 1);
 520
 521         /* variable's signature list */
 522         if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info))
 523                 goto err;
 524         var_sig = efi_variable_parse_signature(auth->auth_info.cert_data,
 525                                                auth->auth_info.hdr.dwLength
 526                                                    - sizeof(auth->auth_info));
 527         if (IS_ERR(var_sig)) {
 528                 debug("Parsing variable's signature failed\n");
 529                 var_sig = NULL;
 530                 goto err;
 531         }
 532
 533         /* signature database used for authentication */
 534         if (u16_strcmp(variable, L"PK") == 0 ||
 535             u16_strcmp(variable, L"KEK") == 0) {
 536                 /* with PK */
 537                 truststore = efi_sigstore_parse_sigdb(L"PK");
 538                 if (!truststore)
 539                         goto err;
 540         } else if (u16_strcmp(variable, L"db") == 0 ||
 541                    u16_strcmp(variable, L"dbx") == 0) {
 542                 /* with PK and KEK */
 543                 truststore = efi_sigstore_parse_sigdb(L"KEK");
 544                 truststore2 = efi_sigstore_parse_sigdb(L"PK");
 545
 546                 if (!truststore) {
 547                         if (!truststore2)
 548                                 goto err;
 549
 550                         truststore = truststore2;
 551                         truststore2 = NULL;
 552                 }
 553         } else {
 554                 /* TODO: support private authenticated variables */
 555                 goto err;
 556         }
 557
 558         /* verify signature */
 559         if (efi_signature_verify_with_sigdb(regs, var_sig, truststore, NULL)) {
 560                 debug("Verified\n");
 561         } else {
 562                 if (truststore2 &&
 563                     efi_signature_verify_with_sigdb(regs, var_sig,
 564                                                     truststore2, NULL)) {
 565                         debug("Verified\n");
 566                 } else {
 567                         debug("Verifying variable's signature failed\n");
 568                         goto err;
 569                 }
 570         }
 571
 572         /* finished checking */
 573         *time = rtc_mktime(&tm);
 574         ret = EFI_SUCCESS;
 575
 576 err:
 577         efi_sigstore_free(truststore);
 578         efi_sigstore_free(truststore2);
 579         pkcs7_free_message(var_sig);
 580         free(regs);
 581
 582         return ret;
 583 }
 584 #else
 585 static efi_status_t efi_variable_authenticate(u16 *variable,
 586                                               const efi_guid_t *vendor,
 587                                               efi_uintn_t *data_size,
 588                                               const void **data, u32 given_attr,
 589                                               u32 *env_attr, u64 *time)
 590 {
 591         return EFI_SUCCESS;
 592 }
 593 #endif /* CONFIG_EFI_SECURE_BOOT */
 594
 595 static efi_status_t efi_get_variable_common(u16 *variable_name,
 596                                             const efi_guid_t *vendor,
 597                                             u32 *attributes,
 598                                             efi_uintn_t *data_size, void *data)
 599 {
 600         char *native_name;
 601         efi_status_t ret;
 602         unsigned long in_size;
 603         const char *val = NULL, *s;
 604         u64 time = 0;
 605         u32 attr;
 606
 607         if (!variable_name || !vendor || !data_size)
 608                 return EFI_EXIT(EFI_INVALID_PARAMETER);
 609
 610         ret = efi_to_native(&native_name, variable_name, vendor);
 611         if (ret)
 612                 return ret;
 613
 614         EFI_PRINT("get '%s'\n", native_name);
 615
 616         val = env_get(native_name);
 617         free(native_name);
 618         if (!val)
 619                 return EFI_NOT_FOUND;
 620
 621         val = parse_attr(val, &attr, &time);
 622
 623         in_size = *data_size;
 624
 625         if ((s = prefix(val, "(blob)"))) {
 626                 size_t len = strlen(s);
 627
 628                 /* number of hexadecimal digits must be even */
 629                 if (len & 1)
 630                         return EFI_DEVICE_ERROR;
 631
 632                 /* two characters per byte: */
 633                 len /= 2;
 634                 *data_size = len;
 635
 636                 if (in_size < len) {
 637                         ret = EFI_BUFFER_TOO_SMALL;
 638                         goto out;
 639                 }
 640
 641                 if (!data) {
 642                         debug("Variable with no data shouldn't exist.\n");
 643                         return EFI_INVALID_PARAMETER;
 644                 }
 645
 646                 if (hex2bin(data, s, len))
 647                         return EFI_DEVICE_ERROR;
 648
 649                 EFI_PRINT("got value: \"%s\"\n", s);
 650         } else if ((s = prefix(val, "(utf8)"))) {
 651                 unsigned len = strlen(s) + 1;
 652
 653                 *data_size = len;
 654
 655                 if (in_size < len) {
 656                         ret = EFI_BUFFER_TOO_SMALL;
 657                         goto out;
 658                 }
 659
 660                 if (!data) {
 661                         debug("Variable with no data shouldn't exist.\n");
 662                         return EFI_INVALID_PARAMETER;
 663                 }
 664
 665                 memcpy(data, s, len);
 666                 ((char *)data)[len] = '\0';
 667
 668                 EFI_PRINT("got value: \"%s\"\n", (char *)data);
 669         } else {
 670                 EFI_PRINT("invalid value: '%s'\n", val);
 671                 return EFI_DEVICE_ERROR;
 672         }
 673
 674 out:
 675         if (attributes)
 676                 *attributes = attr & EFI_VARIABLE_MASK;
 677
 678         return ret;
 679 }
 680
 681 /**
 682  * efi_efi_get_variable() - retrieve value of a UEFI variable
 683  *
 684  * This function implements the GetVariable runtime service.
 685  *
 686  * See the Unified Extensible Firmware Interface (UEFI) specification for
 687  * details.
 688  *
 689  * @variable_name:      name of the variable
 690  * @vendor:             vendor GUID
 691  * @attributes:         attributes of the variable
 692  * @data_size:          size of the buffer to which the variable value is copied
 693  * @data:               buffer to which the variable value is copied
 694  * Return:              status code
 695  */
 696 efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
 697                                      const efi_guid_t *vendor, u32 *attributes,
 698                                      efi_uintn_t *data_size, void *data)
 699 {
 700         efi_status_t ret;
 701
 702         EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
 703                   data_size, data);
 704
 705         ret = efi_get_variable_common(variable_name, vendor, attributes,
 706                                       data_size, data);
 707         return EFI_EXIT(ret);
 708 }
 709
 710 static char *efi_variables_list;
 711 static char *efi_cur_variable;
 712
 713 /**
 714  * parse_uboot_variable() - parse a u-boot variable and get uefi-related
 715  *                          information
 716  * @variable:           whole data of u-boot variable (ie. name=value)
 717  * @variable_name_size: size of variable_name buffer in byte
 718  * @variable_name:      name of uefi variable in u16, null-terminated
 719  * @vendor:             vendor's guid
 720  * @attributes:         attributes
 721  *
 722  * A uefi variable is encoded into a u-boot variable as described above.
 723  * This function parses such a u-boot variable and retrieve uefi-related
 724  * information into respective parameters. In return, variable_name_size
 725  * is the size of variable name including NULL.
 726  *
 727  * Return:              EFI_SUCCESS if parsing is OK, EFI_NOT_FOUND when
 728  *                      the entire variable list has been returned,
 729  *                      otherwise non-zero status code
 730  */
 731 static efi_status_t parse_uboot_variable(char *variable,
 732                                          efi_uintn_t *variable_name_size,
 733                                          u16 *variable_name,
 734                                          const efi_guid_t *vendor,
 735                                          u32 *attributes)
 736 {
 737         char *guid, *name, *end, c;
 738         size_t name_len;
 739         efi_uintn_t old_variable_name_size;
 740         u64 time;
 741         u16 *p;
 742
 743         guid = strchr(variable, '_');
 744         if (!guid)
 745                 return EFI_INVALID_PARAMETER;
 746         guid++;
 747         name = strchr(guid, '_');
 748         if (!name)
 749                 return EFI_INVALID_PARAMETER;
 750         name++;
 751         end = strchr(name, '=');
 752         if (!end)
 753                 return EFI_INVALID_PARAMETER;
 754
 755         name_len = end - name;
 756         old_variable_name_size = *variable_name_size;
 757         *variable_name_size = sizeof(u16) * (name_len + 1);
 758         if (old_variable_name_size < *variable_name_size)
 759                 return EFI_BUFFER_TOO_SMALL;
 760
 761         end++; /* point to value */
 762
 763         /* variable name */
 764         p = variable_name;
 765         utf8_utf16_strncpy(&p, name, name_len);
 766         variable_name[name_len] = 0;
 767
 768         /* guid */
 769         c = *(name - 1);
 770         *(name - 1) = '\0'; /* guid need be null-terminated here */
 771         uuid_str_to_bin(guid, (unsigned char *)vendor, UUID_STR_FORMAT_GUID);
 772         *(name - 1) = c;
 773
 774         /* attributes */
 775         parse_attr(end, attributes, &time);
 776
 777         return EFI_SUCCESS;
 778 }
 779
 780 /**
 781  * efi_get_next_variable_name() - enumerate the current variable names
 782  *
 783  * @variable_name_size: size of variable_name buffer in byte
 784  * @variable_name:      name of uefi variable's name in u16
 785  * @vendor:             vendor's guid
 786  *
 787  * This function implements the GetNextVariableName service.
 788  *
 789  * See the Unified Extensible Firmware Interface (UEFI) specification for
 790  * details.
 791  *
 792  * Return: status code
 793  */
 794 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
 795                                                u16 *variable_name,
 796                                                efi_guid_t *vendor)
 797 {
 798         char *native_name, *variable;
 799         ssize_t name_len, list_len;
 800         char regex[256];
 801         char * const regexlist[] = {regex};
 802         u32 attributes;
 803         int i;
 804         efi_status_t ret;
 805
 806         EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
 807
 808         if (!variable_name_size || !variable_name || !vendor)
 809                 return EFI_EXIT(EFI_INVALID_PARAMETER);
 810
 811         if (variable_name[0]) {
 812                 /* check null-terminated string */
 813                 for (i = 0; i < *variable_name_size; i++)
 814                         if (!variable_name[i])
 815                                 break;
 816                 if (i >= *variable_name_size)
 817                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 818
 819                 /* search for the last-returned variable */
 820                 ret = efi_to_native(&native_name, variable_name, vendor);
 821                 if (ret)
 822                         return EFI_EXIT(ret);
 823
 824                 name_len = strlen(native_name);
 825                 for (variable = efi_variables_list; variable && *variable;) {
 826                         if (!strncmp(variable, native_name, name_len) &&
 827                             variable[name_len] == '=')
 828                                 break;
 829
 830                         variable = strchr(variable, '\n');
 831                         if (variable)
 832                                 variable++;
 833                 }
 834
 835                 free(native_name);
 836                 if (!(variable && *variable))
 837                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 838
 839                 /* next variable */
 840                 variable = strchr(variable, '\n');
 841                 if (variable)
 842                         variable++;
 843                 if (!(variable && *variable))
 844                         return EFI_EXIT(EFI_NOT_FOUND);
 845         } else {
 846                 /*
 847                  *new search: free a list used in the previous search
 848                  */
 849                 free(efi_variables_list);
 850                 efi_variables_list = NULL;
 851                 efi_cur_variable = NULL;
 852
 853                 snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_.*");
 854                 list_len = hexport_r(&env_htab, '\n',
 855                                      H_MATCH_REGEX | H_MATCH_KEY,
 856                                      &efi_variables_list, 0, 1, regexlist);
 857
 858                 if (list_len <= 1)
 859                         return EFI_EXIT(EFI_NOT_FOUND);
 860
 861                 variable = efi_variables_list;
 862         }
 863
 864         ret = parse_uboot_variable(variable, variable_name_size, variable_name,
 865                                    vendor, &attributes);
 866
 867         return EFI_EXIT(ret);
 868 }
 869
 870 static efi_status_t efi_set_variable_common(u16 *variable_name,
 871                                             const efi_guid_t *vendor,
 872                                             u32 attributes,
 873                                             efi_uintn_t data_size,
 874                                             const void *data,
 875                                             bool ro_check)
 876 {
 877         char *native_name = NULL, *old_data = NULL, *val = NULL, *s;
 878         efi_uintn_t old_size;
 879         bool append, delete;
 880         u64 time = 0;
 881         u32 attr;
 882         efi_status_t ret = EFI_SUCCESS;
 883
 884         debug("%s: set '%s'\n", __func__, native_name);
 885
 886         if (!variable_name || !*variable_name || !vendor ||
 887             ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
 888              !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS))) {
 889                 ret = EFI_INVALID_PARAMETER;
 890                 goto err;
 891         }
 892
 893         ret = efi_to_native(&native_name, variable_name, vendor);
 894         if (ret)
 895                 goto err;
 896
 897         /* check if a variable exists */
 898         old_size = 0;
 899         attr = 0;
 900         ret = efi_get_variable_common(variable_name, vendor, &attr,
 901                                       &old_size, NULL);
 902         append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
 903         attributes &= ~(u32)EFI_VARIABLE_APPEND_WRITE;
 904         delete = !append && (!data_size || !attributes);
 905
 906         /* check attributes */
 907         if (old_size) {
 908                 if (ro_check && (attr & READ_ONLY)) {
 909                         ret = EFI_WRITE_PROTECTED;
 910                         goto err;
 911                 }
 912
 913                 /* attributes won't be changed */
 914                 if (!delete &&
 915                     ((ro_check && attr != attributes) ||
 916                      (!ro_check && ((attr & ~(u32)READ_ONLY)
 917                                     != (attributes & ~(u32)READ_ONLY))))) {
 918                         ret = EFI_INVALID_PARAMETER;
 919                         goto err;
 920                 }
 921         } else {
 922                 if (delete || append) {
 923                         /*
 924                          * Trying to delete or to update a non-existent
 925                          * variable.
 926                          */
 927                         ret = EFI_NOT_FOUND;
 928                         goto err;
 929                 }
 930         }
 931
 932         if (((!u16_strcmp(variable_name, L"PK") ||
 933               !u16_strcmp(variable_name, L"KEK")) &&
 934                 !guidcmp(vendor, &efi_global_variable_guid)) ||
 935             ((!u16_strcmp(variable_name, L"db") ||
 936               !u16_strcmp(variable_name, L"dbx")) &&
 937                 !guidcmp(vendor, &efi_guid_image_security_database))) {
 938                 /* authentication is mandatory */
 939                 if (!(attributes &
 940                       EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
 941                         debug("%ls: AUTHENTICATED_WRITE_ACCESS required\n",
 942                               variable_name);
 943                         ret = EFI_INVALID_PARAMETER;
 944                         goto err;
 945                 }
 946         }
 947
 948         /* authenticate a variable */
 949         if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT)) {
 950                 if (attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS) {
 951                         ret = EFI_INVALID_PARAMETER;
 952                         goto err;
 953                 }
 954                 if (attributes &
 955                     EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
 956                         ret = efi_variable_authenticate(variable_name, vendor,
 957                                                         &data_size, &data,
 958                                                         attributes, &attr,
 959                                                         &time);
 960                         if (ret != EFI_SUCCESS)
 961                                 goto err;
 962
 963                         /* last chance to check for delete */
 964                         if (!data_size)
 965                                 delete = true;
 966                 }
 967         } else {
 968                 if (attributes &
 969                     (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS |
 970                      EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
 971                         debug("Secure boot is not configured\n");
 972                         ret = EFI_INVALID_PARAMETER;
 973                         goto err;
 974                 }
 975         }
 976
 977         /* delete a variable */
 978         if (delete) {
 979                 /* !old_size case has been handled before */
 980                 val = NULL;
 981                 ret = EFI_SUCCESS;
 982                 goto out;
 983         }
 984
 985         if (append) {
 986                 old_data = malloc(old_size);
 987                 if (!old_data) {
 988                         ret = EFI_OUT_OF_RESOURCES;
 989                         goto err;
 990                 }
 991                 ret = efi_get_variable_common(variable_name, vendor,
 992                                               &attr, &old_size, old_data);
 993                 if (ret != EFI_SUCCESS)
 994                         goto err;
 995         } else {
 996                 old_size = 0;
 997         }
 998
 999         val = malloc(2 * old_size + 2 * data_size
1000                      + strlen("{ro,run,boot,nv,time=0123456701234567}(blob)")
1001                      + 1);
1002         if (!val) {
1003                 ret = EFI_OUT_OF_RESOURCES;
1004                 goto err;
1005         }
1006
1007         s = val;
1008
1009         /*
1010          * store attributes
1011          */
1012         attributes &= (READ_ONLY |
1013                        EFI_VARIABLE_NON_VOLATILE |
1014                        EFI_VARIABLE_BOOTSERVICE_ACCESS |
1015                        EFI_VARIABLE_RUNTIME_ACCESS |
1016                        EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS);
1017         s += sprintf(s, "{");
1018         while (attributes) {
1019                 attr = 1 << (ffs(attributes) - 1);
1020
1021                 if (attr == READ_ONLY) {
1022                         s += sprintf(s, "ro");
1023                 } else if (attr == EFI_VARIABLE_NON_VOLATILE) {
1024                         s += sprintf(s, "nv");
1025                 } else if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS) {
1026                         s += sprintf(s, "boot");
1027                 } else if (attr == EFI_VARIABLE_RUNTIME_ACCESS) {
1028                         s += sprintf(s, "run");
1029                 } else if (attr ==
1030                            EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
1031                         s += sprintf(s, "time=");
1032                         s = bin2hex(s, (u8 *)&time, sizeof(time));
1033                 }
1034
1035                 attributes &= ~attr;
1036                 if (attributes)
1037                         s += sprintf(s, ",");
1038         }
1039         s += sprintf(s, "}");
1040         s += sprintf(s, "(blob)");
1041
1042         /* store payload: */
1043         if (append)
1044                 s = bin2hex(s, old_data, old_size);
1045         s = bin2hex(s, data, data_size);
1046         *s = '\0';
1047
1048         EFI_PRINT("setting: %s=%s\n", native_name, val);
1049
1050 out:
1051         if (env_set(native_name, val)) {
1052                 ret = EFI_DEVICE_ERROR;
1053         } else {
1054                 bool vendor_keys_modified = false;
1055
1056                 if ((u16_strcmp(variable_name, L"PK") == 0 &&
1057                      guidcmp(vendor, &efi_global_variable_guid) == 0)) {
1058                         ret = efi_transfer_secure_state(
1059                                         (delete ? EFI_MODE_SETUP :
1060                                                   EFI_MODE_USER));
1061                         if (ret != EFI_SUCCESS)
1062                                 goto err;
1063
1064                         if (efi_secure_mode != EFI_MODE_SETUP)
1065                                 vendor_keys_modified = true;
1066                 } else if ((u16_strcmp(variable_name, L"KEK") == 0 &&
1067                      guidcmp(vendor, &efi_global_variable_guid) == 0)) {
1068                         if (efi_secure_mode != EFI_MODE_SETUP)
1069                                 vendor_keys_modified = true;
1070                 }
1071
1072                 /* update VendorKeys */
1073                 if (vendor_keys_modified & efi_vendor_keys) {
1074                         efi_vendor_keys = 0;
1075                         ret = efi_set_variable_common(
1076                                                 L"VendorKeys",
1077                                                 &efi_global_variable_guid,
1078                                                 EFI_VARIABLE_BOOTSERVICE_ACCESS
1079                                                  | EFI_VARIABLE_RUNTIME_ACCESS
1080                                                  | READ_ONLY,
1081                                                 sizeof(efi_vendor_keys),
1082                                                 &efi_vendor_keys,
1083                                                 false);
1084                 } else {
1085                         ret = EFI_SUCCESS;
1086                 }
1087         }
1088
1089 err:
1090         free(native_name);
1091         free(old_data);
1092         free(val);
1093
1094         return ret;
1095 }
1096
1097 /**
1098  * efi_set_variable() - set value of a UEFI variable
1099  *
1100  * This function implements the SetVariable runtime service.
1101  *
1102  * See the Unified Extensible Firmware Interface (UEFI) specification for
1103  * details.
1104  *
1105  * @variable_name:      name of the variable
1106  * @vendor:             vendor GUID
1107  * @attributes:         attributes of the variable
1108  * @data_size:          size of the buffer with the variable value
1109  * @data:               buffer with the variable value
1110  * Return:              status code
1111  */
1112 efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
1113                                      const efi_guid_t *vendor, u32 attributes,
1114                                      efi_uintn_t data_size, const void *data)
1115 {
1116         EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
1117                   data_size, data);
1118
1119         /* READ_ONLY bit is not part of API */
1120         attributes &= ~(u32)READ_ONLY;
1121
1122         return EFI_EXIT(efi_set_variable_common(variable_name, vendor,
1123                                                 attributes, data_size, data,
1124                                                 true));
1125 }
1126
1127 /**
1128  * efi_query_variable_info() - get information about EFI variables
1129  *
1130  * This function implements the QueryVariableInfo() runtime service.
1131  *
1132  * See the Unified Extensible Firmware Interface (UEFI) specification for
1133  * details.
1134  *
1135  * @attributes:                         bitmask to select variables to be
1136  *                                      queried
1137  * @maximum_variable_storage_size:      maximum size of storage area for the
1138  *                                      selected variable types
1139  * @remaining_variable_storage_size:    remaining size of storage are for the
1140  *                                      selected variable types
1141  * @maximum_variable_size:              maximum size of a variable of the
1142  *                                      selected type
1143  * Returns:                             status code
1144  */
1145 efi_status_t __efi_runtime EFIAPI efi_query_variable_info(
1146                         u32 attributes,
1147                         u64 *maximum_variable_storage_size,
1148                         u64 *remaining_variable_storage_size,
1149                         u64 *maximum_variable_size)
1150 {
1151         return EFI_UNSUPPORTED;
1152 }
1153
1154 /**
1155  * efi_get_variable_runtime() - runtime implementation of GetVariable()
1156  *
1157  * @variable_name:      name of the variable
1158  * @vendor:             vendor GUID
1159  * @attributes:         attributes of the variable
1160  * @data_size:          size of the buffer to which the variable value is copied
1161  * @data:               buffer to which the variable value is copied
1162  * Return:              status code
1163  */
1164 static efi_status_t __efi_runtime EFIAPI
1165 efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
1166                          u32 *attributes, efi_uintn_t *data_size, void *data)
1167 {
1168         return EFI_UNSUPPORTED;
1169 }
1170
1171 /**
1172  * efi_get_next_variable_name_runtime() - runtime implementation of
1173  *                                        GetNextVariable()
1174  *
1175  * @variable_name_size: size of variable_name buffer in byte
1176  * @variable_name:      name of uefi variable's name in u16
1177  * @vendor:             vendor's guid
1178  * Return: status code
1179  */
1180 static efi_status_t __efi_runtime EFIAPI
1181 efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
1182                                    u16 *variable_name, efi_guid_t *vendor)
1183 {
1184         return EFI_UNSUPPORTED;
1185 }
1186
1187 /**
1188  * efi_set_variable_runtime() - runtime implementation of SetVariable()
1189  *
1190  * @variable_name:      name of the variable
1191  * @vendor:             vendor GUID
1192  * @attributes:         attributes of the variable
1193  * @data_size:          size of the buffer with the variable value
1194  * @data:               buffer with the variable value
1195  * Return:              status code
1196  */
1197 static efi_status_t __efi_runtime EFIAPI
1198 efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
1199                          u32 attributes, efi_uintn_t data_size,
1200                          const void *data)
1201 {
1202         return EFI_UNSUPPORTED;
1203 }
1204
1205 /**
1206  * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
1207  */
1208 void efi_variables_boot_exit_notify(void)
1209 {
1210         efi_runtime_services.get_variable = efi_get_variable_runtime;
1211         efi_runtime_services.get_next_variable_name =
1212                                 efi_get_next_variable_name_runtime;
1213         efi_runtime_services.set_variable = efi_set_variable_runtime;
1214         efi_update_table_header_crc32(&efi_runtime_services.hdr);
1215 }
1216
1217 /**
1218  * efi_init_variables() - initialize variable services
1219  *
1220  * Return:      status code
1221  */
1222 efi_status_t efi_init_variables(void)
1223 {
1224         efi_status_t ret;
1225
1226         ret = efi_init_secure_state();
1227
1228         return ret;
1229 }