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.h>
  11 #include <env_internal.h>
  12 #include <hexdump.h>
  13 #include <malloc.h>
  14 #include <rtc.h>
  15 #include <search.h>
  16 #include <uuid.h>
  17 #include <crypto/pkcs7_parser.h>
  18 #include <linux/bitops.h>
  19 #include <linux/compat.h>
  20 #include <u-boot/crc.h>
  21
  22 enum efi_secure_mode {
  23         EFI_MODE_SETUP,
  24         EFI_MODE_USER,
  25         EFI_MODE_AUDIT,
  26         EFI_MODE_DEPLOYED,
  27 };
  28
  29 const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
  30 static bool efi_secure_boot;
  31 static int efi_secure_mode;
  32 static u8 efi_vendor_keys;
  33
  34 #define READ_ONLY BIT(31)
  35
  36 static efi_status_t efi_get_variable_common(u16 *variable_name,
  37                                             const efi_guid_t *vendor,
  38                                             u32 *attributes,
  39                                             efi_uintn_t *data_size, void *data);
  40
  41 static efi_status_t efi_set_variable_common(u16 *variable_name,
  42                                             const efi_guid_t *vendor,
  43                                             u32 attributes,
  44                                             efi_uintn_t data_size,
  45                                             const void *data,
  46                                             bool ro_check);
  47
  48 /*
  49  * Mapping between EFI variables and u-boot variables:
  50  *
  51  *   efi_$guid_$varname = {attributes}(type)value
  52  *
  53  * For example:
  54  *
  55  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
  56  *      "{ro,boot,run}(blob)0000000000000000"
  57  *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
  58  *      "(blob)00010000"
  59  *
  60  * The attributes are a comma separated list of these possible
  61  * attributes:
  62  *
  63  *   + ro   - read-only
  64  *   + boot - boot-services access
  65  *   + run  - runtime access
  66  *
  67  * NOTE: with current implementation, no variables are available after
  68  * ExitBootServices, and all are persisted (if possible).
  69  *
  70  * If not specified, the attributes default to "{boot}".
  71  *
  72  * The required type is one of:
  73  *
  74  *   + utf8 - raw utf8 string
  75  *   + blob - arbitrary length hex string
  76  *
  77  * Maybe a utf16 type would be useful to for a string value to be auto
  78  * converted to utf16?
  79  */
  80
  81 #define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_"))
  82
  83 /**
  84  * efi_to_native() - convert the UEFI variable name and vendor GUID to U-Boot
  85  *                   variable name
  86  *
  87  * The U-Boot variable name is a concatenation of prefix 'efi', the hexstring
  88  * encoded vendor GUID, and the UTF-8 encoded UEFI variable name separated by
  89  * underscores, e.g. 'efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder'.
  90  *
  91  * @native:             pointer to pointer to U-Boot variable name
  92  * @variable_name:      UEFI variable name
  93  * @vendor:             vendor GUID
  94  * Return:              status code
  95  */
  96 static efi_status_t efi_to_native(char **native, const u16 *variable_name,
  97                                   const efi_guid_t *vendor)
  98 {
  99         size_t len;
 100         char *pos;
 101
 102         len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
 103         *native = malloc(len);
 104         if (!*native)
 105                 return EFI_OUT_OF_RESOURCES;
 106
 107         pos = *native;
 108         pos += sprintf(pos, "efi_%pUl_", vendor);
 109         utf16_utf8_strcpy(&pos, variable_name);
 110
 111         return EFI_SUCCESS;
 112 }
 113
 114 /**
 115  * prefix() - skip over prefix
 116  *
 117  * Skip over a prefix string.
 118  *
 119  * @str:        string with prefix
 120  * @prefix:     prefix string
 121  * Return:      string without prefix, or NULL if prefix not found
 122  */
 123 static const char *prefix(const char *str, const char *prefix)
 124 {
 125         size_t n = strlen(prefix);
 126         if (!strncmp(prefix, str, n))
 127                 return str + n;
 128         return NULL;
 129 }
 130
 131 /**
 132  * parse_attr() - decode attributes part of variable value
 133  *
 134  * Convert the string encoded attributes of a UEFI variable to a bit mask.
 135  * TODO: Several attributes are not supported.
 136  *
 137  * @str:        value of U-Boot variable
 138  * @attrp:      pointer to UEFI attributes
 139  * @timep:      pointer to time attribute
 140  * Return:      pointer to remainder of U-Boot variable value
 141  */
 142 static const char *parse_attr(const char *str, u32 *attrp, u64 *timep)
 143 {
 144         u32 attr = 0;
 145         char sep = '{';
 146
 147         if (*str != '{') {
 148                 *attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
 149                 return str;
 150         }
 151
 152         while (*str == sep) {
 153                 const char *s;
 154
 155                 str++;
 156
 157                 if ((s = prefix(str, "ro"))) {
 158                         attr |= READ_ONLY;
 159                 } else if ((s = prefix(str, "nv"))) {
 160                         attr |= EFI_VARIABLE_NON_VOLATILE;
 161                 } else if ((s = prefix(str, "boot"))) {
 162                         attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
 163                 } else if ((s = prefix(str, "run"))) {
 164                         attr |= EFI_VARIABLE_RUNTIME_ACCESS;
 165                 } else if ((s = prefix(str, "time="))) {
 166                         attr |= EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS;
 167                         hex2bin((u8 *)timep, s, sizeof(*timep));
 168                         s += sizeof(*timep) * 2;
 169                 } else if (*str == '}') {
 170                         break;
 171                 } else {
 172                         printf("invalid attribute: %s\n", str);
 173                         break;
 174                 }
 175
 176                 str = s;
 177                 sep = ',';
 178         }
 179
 180         str++;
 181
 182         *attrp = attr;
 183
 184         return str;
 185 }
 186
 187 /**
 188  * efi_set_secure_state - modify secure boot state variables
 189  * @sec_boot:           value of SecureBoot
 190  * @setup_mode:         value of SetupMode
 191  * @audit_mode:         value of AuditMode
 192  * @deployed_mode:      value of DeployedMode
 193  *
 194  * Modify secure boot stat-related variables as indicated.
 195  *
 196  * Return:              status code
 197  */
 198 static efi_status_t efi_set_secure_state(int sec_boot, int setup_mode,
 199                                          int audit_mode, int deployed_mode)
 200 {
 201         u32 attributes;
 202         efi_status_t ret;
 203
 204         attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
 205                      EFI_VARIABLE_RUNTIME_ACCESS |
 206                      READ_ONLY;
 207         ret = efi_set_variable_common(L"SecureBoot", &efi_global_variable_guid,
 208                                       attributes, sizeof(sec_boot), &sec_boot,
 209                                       false);
 210         if (ret != EFI_SUCCESS)
 211                 goto err;
 212
 213         ret = efi_set_variable_common(L"SetupMode", &efi_global_variable_guid,
 214                                       attributes, sizeof(setup_mode),
 215                                       &setup_mode, false);
 216         if (ret != EFI_SUCCESS)
 217                 goto err;
 218
 219         ret = efi_set_variable_common(L"AuditMode", &efi_global_variable_guid,
 220                                       attributes, sizeof(audit_mode),
 221                                       &audit_mode, false);
 222         if (ret != EFI_SUCCESS)
 223                 goto err;
 224
 225         ret = efi_set_variable_common(L"DeployedMode",
 226                                       &efi_global_variable_guid, attributes,
 227                                       sizeof(deployed_mode), &deployed_mode,
 228                                       false);
 229 err:
 230         return ret;
 231 }
 232
 233 /**
 234  * efi_transfer_secure_state - handle a secure boot state transition
 235  * @mode:       new state
 236  *
 237  * Depending on @mode, secure boot related variables are updated.
 238  * Those variables are *read-only* for users, efi_set_variable_common()
 239  * is called here.
 240  *
 241  * Return:      status code
 242  */
 243 static efi_status_t efi_transfer_secure_state(enum efi_secure_mode mode)
 244 {
 245         efi_status_t ret;
 246
 247         debug("Switching secure state from %d to %d\n", efi_secure_mode, mode);
 248
 249         if (mode == EFI_MODE_DEPLOYED) {
 250                 ret = efi_set_secure_state(1, 0, 0, 1);
 251                 if (ret != EFI_SUCCESS)
 252                         goto err;
 253
 254                 efi_secure_boot = true;
 255         } else if (mode == EFI_MODE_AUDIT) {
 256                 ret = efi_set_variable_common(L"PK", &efi_global_variable_guid,
 257                                               EFI_VARIABLE_BOOTSERVICE_ACCESS |
 258                                               EFI_VARIABLE_RUNTIME_ACCESS,
 259                                               0, NULL, false);
 260                 if (ret != EFI_SUCCESS)
 261                         goto err;
 262
 263                 ret = efi_set_secure_state(0, 1, 1, 0);
 264                 if (ret != EFI_SUCCESS)
 265                         goto err;
 266
 267                 efi_secure_boot = true;
 268         } else if (mode == EFI_MODE_USER) {
 269                 ret = efi_set_secure_state(1, 0, 0, 0);
 270                 if (ret != EFI_SUCCESS)
 271                         goto err;
 272
 273                 efi_secure_boot = true;
 274         } else if (mode == EFI_MODE_SETUP) {
 275                 ret = efi_set_secure_state(0, 1, 0, 0);
 276                 if (ret != EFI_SUCCESS)
 277                         goto err;
 278         } else {
 279                 return EFI_INVALID_PARAMETER;
 280         }
 281
 282         efi_secure_mode = mode;
 283
 284         return EFI_SUCCESS;
 285
 286 err:
 287         /* TODO: What action should be taken here? */
 288         printf("ERROR: Secure state transition failed\n");
 289         return ret;
 290 }
 291
 292 /**
 293  * efi_init_secure_state - initialize secure boot state
 294  *
 295  * Return:      status code
 296  */
 297 static efi_status_t efi_init_secure_state(void)
 298 {
 299         enum efi_secure_mode mode;
 300         efi_uintn_t size;
 301         efi_status_t ret;
 302
 303         /*
 304          * TODO:
 305          * Since there is currently no "platform-specific" installation
 306          * method of Platform Key, we can't say if VendorKeys is 0 or 1
 307          * precisely.
 308          */
 309
 310         size = 0;
 311         ret = efi_get_variable_common(L"PK", &efi_global_variable_guid,
 312                                       NULL, &size, NULL);
 313         if (ret == EFI_BUFFER_TOO_SMALL) {
 314                 if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT))
 315                         mode = EFI_MODE_USER;
 316                 else
 317                         mode = EFI_MODE_SETUP;
 318
 319                 efi_vendor_keys = 0;
 320         } else if (ret == EFI_NOT_FOUND) {
 321                 mode = EFI_MODE_SETUP;
 322                 efi_vendor_keys = 1;
 323         } else {
 324                 goto err;
 325         }
 326
 327         ret = efi_transfer_secure_state(mode);
 328         if (ret == EFI_SUCCESS)
 329                 ret = efi_set_variable_common(L"VendorKeys",
 330                                               &efi_global_variable_guid,
 331                                               EFI_VARIABLE_BOOTSERVICE_ACCESS |
 332                                               EFI_VARIABLE_RUNTIME_ACCESS |
 333                                               READ_ONLY,
 334                                               sizeof(efi_vendor_keys),
 335                                               &efi_vendor_keys, false);
 336
 337 err:
 338         return ret;
 339 }
 340
 341 /**
 342  * efi_secure_boot_enabled - return if secure boot is enabled or not
 343  *
 344  * Return:      true if enabled, false if disabled
 345  */
 346 bool efi_secure_boot_enabled(void)
 347 {
 348         return efi_secure_boot;
 349 }
 350
 351 #ifdef CONFIG_EFI_SECURE_BOOT
 352 static u8 pkcs7_hdr[] = {
 353         /* SEQUENCE */
 354         0x30, 0x82, 0x05, 0xc7,
 355         /* OID: pkcs7-signedData */
 356         0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x02,
 357         /* Context Structured? */
 358         0xa0, 0x82, 0x05, 0xb8,
 359 };
 360
 361 /**
 362  * efi_variable_parse_signature - parse a signature in variable
 363  * @buf:        Pointer to variable's value
 364  * @buflen:     Length of @buf
 365  *
 366  * Parse a signature embedded in variable's value and instantiate
 367  * a pkcs7_message structure. Since pkcs7_parse_message() accepts only
 368  * pkcs7's signedData, some header needed be prepended for correctly
 369  * parsing authentication data, particularly for variable's.
 370  *
 371  * Return:      Pointer to pkcs7_message structure on success, NULL on error
 372  */
 373 static struct pkcs7_message *efi_variable_parse_signature(const void *buf,
 374                                                           size_t buflen)
 375 {
 376         u8 *ebuf;
 377         size_t ebuflen, len;
 378         struct pkcs7_message *msg;
 379
 380         /*
 381          * This is the best assumption to check if the binary is
 382          * already in a form of pkcs7's signedData.
 383          */
 384         if (buflen > sizeof(pkcs7_hdr) &&
 385             !memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) {
 386                 msg = pkcs7_parse_message(buf, buflen);
 387                 goto out;
 388         }
 389
 390         /*
 391          * Otherwise, we should add a dummy prefix sequence for pkcs7
 392          * message parser to be able to process.
 393          * NOTE: EDK2 also uses similar hack in WrapPkcs7Data()
 394          * in CryptoPkg/Library/BaseCryptLib/Pk/CryptPkcs7VerifyCommon.c
 395          * TODO:
 396          * The header should be composed in a more refined manner.
 397          */
 398         debug("Makeshift prefix added to authentication data\n");
 399         ebuflen = sizeof(pkcs7_hdr) + buflen;
 400         if (ebuflen <= 0x7f) {
 401                 debug("Data is too short\n");
 402                 return NULL;
 403         }
 404
 405         ebuf = malloc(ebuflen);
 406         if (!ebuf) {
 407                 debug("Out of memory\n");
 408                 return NULL;
 409         }
 410
 411         memcpy(ebuf, pkcs7_hdr, sizeof(pkcs7_hdr));
 412         memcpy(ebuf + sizeof(pkcs7_hdr), buf, buflen);
 413         len = ebuflen - 4;
 414         ebuf[2] = (len >> 8) & 0xff;
 415         ebuf[3] = len & 0xff;
 416         len = ebuflen - 0x13;
 417         ebuf[0x11] = (len >> 8) & 0xff;
 418         ebuf[0x12] = len & 0xff;
 419
 420         msg = pkcs7_parse_message(ebuf, ebuflen);
 421
 422         free(ebuf);
 423
 424 out:
 425         if (IS_ERR(msg))
 426                 return NULL;
 427
 428         return msg;
 429 }
 430
 431 /**
 432  * efi_variable_authenticate - authenticate a variable
 433  * @variable:   Variable name in u16
 434  * @vendor:     Guid of variable
 435  * @data_size:  Size of @data
 436  * @data:       Pointer to variable's value
 437  * @given_attr: Attributes to be given at SetVariable()
 438  * @env_attr:   Attributes that an existing variable holds
 439  * @time:       signed time that an existing variable holds
 440  *
 441  * Called by efi_set_variable() to verify that the input is correct.
 442  * Will replace the given data pointer with another that points to
 443  * the actual data to store in the internal memory.
 444  * On success, @data and @data_size will be replaced with variable's
 445  * actual data, excluding authentication data, and its size, and variable's
 446  * attributes and signed time will also be returned in @env_attr and @time,
 447  * respectively.
 448  *
 449  * Return:      status code
 450  */
 451 static efi_status_t efi_variable_authenticate(u16 *variable,
 452                                               const efi_guid_t *vendor,
 453                                               efi_uintn_t *data_size,
 454                                               const void **data, u32 given_attr,
 455                                               u32 *env_attr, u64 *time)
 456 {
 457         const struct efi_variable_authentication_2 *auth;
 458         struct efi_signature_store *truststore, *truststore2;
 459         struct pkcs7_message *var_sig;
 460         struct efi_image_regions *regs;
 461         struct efi_time timestamp;
 462         struct rtc_time tm;
 463         u64 new_time;
 464         efi_status_t ret;
 465
 466         var_sig = NULL;
 467         truststore = NULL;
 468         truststore2 = NULL;
 469         regs = NULL;
 470         ret = EFI_SECURITY_VIOLATION;
 471
 472         if (*data_size < sizeof(struct efi_variable_authentication_2))
 473                 goto err;
 474
 475         /* authentication data */
 476         auth = *data;
 477         if (*data_size < (sizeof(auth->time_stamp)
 478                                 + auth->auth_info.hdr.dwLength))
 479                 goto err;
 480
 481         if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
 482                 goto err;
 483
 484         *data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
 485         *data_size -= (sizeof(auth->time_stamp)
 486                                 + auth->auth_info.hdr.dwLength);
 487
 488         memcpy(&timestamp, &auth->time_stamp, sizeof(timestamp));
 489         memset(&tm, 0, sizeof(tm));
 490         tm.tm_year = timestamp.year;
 491         tm.tm_mon = timestamp.month;
 492         tm.tm_mday = timestamp.day;
 493         tm.tm_hour = timestamp.hour;
 494         tm.tm_min = timestamp.minute;
 495         tm.tm_sec = timestamp.second;
 496         new_time = rtc_mktime(&tm);
 497
 498         if (!efi_secure_boot_enabled()) {
 499                 /* finished checking */
 500                 *time = new_time;
 501                 return EFI_SUCCESS;
 502         }
 503
 504         if (new_time <= *time)
 505                 goto err;
 506
 507         /* data to be digested */
 508         regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 5, 1);
 509         if (!regs)
 510                 goto err;
 511         regs->max = 5;
 512         efi_image_region_add(regs, (uint8_t *)variable,
 513                              (uint8_t *)variable
 514                                 + u16_strlen(variable) * sizeof(u16), 1);
 515         efi_image_region_add(regs, (uint8_t *)vendor,
 516                              (uint8_t *)vendor + sizeof(*vendor), 1);
 517         efi_image_region_add(regs, (uint8_t *)&given_attr,
 518                              (uint8_t *)&given_attr + sizeof(given_attr), 1);
 519         efi_image_region_add(regs, (uint8_t *)&timestamp,
 520                              (uint8_t *)&timestamp + sizeof(timestamp), 1);
 521         efi_image_region_add(regs, (uint8_t *)*data,
 522                              (uint8_t *)*data + *data_size, 1);
 523
 524         /* variable's signature list */
 525         if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info))
 526                 goto err;
 527         var_sig = efi_variable_parse_signature(auth->auth_info.cert_data,
 528                                                auth->auth_info.hdr.dwLength
 529                                                    - sizeof(auth->auth_info));
 530         if (!var_sig) {
 531                 debug("Parsing variable's signature failed\n");
 532                 goto err;
 533         }
 534
 535         /* signature database used for authentication */
 536         if (u16_strcmp(variable, L"PK") == 0 ||
 537             u16_strcmp(variable, L"KEK") == 0) {
 538                 /* with PK */
 539                 truststore = efi_sigstore_parse_sigdb(L"PK");
 540                 if (!truststore)
 541                         goto err;
 542         } else if (u16_strcmp(variable, L"db") == 0 ||
 543                    u16_strcmp(variable, L"dbx") == 0) {
 544                 /* with PK and KEK */
 545                 truststore = efi_sigstore_parse_sigdb(L"KEK");
 546                 truststore2 = efi_sigstore_parse_sigdb(L"PK");
 547
 548                 if (!truststore) {
 549                         if (!truststore2)
 550                                 goto err;
 551
 552                         truststore = truststore2;
 553                         truststore2 = NULL;
 554                 }
 555         } else {
 556                 /* TODO: support private authenticated variables */
 557                 goto err;
 558         }
 559
 560         /* verify signature */
 561         if (efi_signature_verify_with_sigdb(regs, var_sig, truststore, NULL)) {
 562                 debug("Verified\n");
 563         } else {
 564                 if (truststore2 &&
 565                     efi_signature_verify_with_sigdb(regs, var_sig,
 566                                                     truststore2, NULL)) {
 567                         debug("Verified\n");
 568                 } else {
 569                         debug("Verifying variable's signature failed\n");
 570                         goto err;
 571                 }
 572         }
 573
 574         /* finished checking */
 575         *time = rtc_mktime(&tm);
 576         ret = EFI_SUCCESS;
 577
 578 err:
 579         efi_sigstore_free(truststore);
 580         efi_sigstore_free(truststore2);
 581         pkcs7_free_message(var_sig);
 582         free(regs);
 583
 584         return ret;
 585 }
 586 #else
 587 static efi_status_t efi_variable_authenticate(u16 *variable,
 588                                               const efi_guid_t *vendor,
 589                                               efi_uintn_t *data_size,
 590                                               const void **data, u32 given_attr,
 591                                               u32 *env_attr, u64 *time)
 592 {
 593         return EFI_SUCCESS;
 594 }
 595 #endif /* CONFIG_EFI_SECURE_BOOT */
 596
 597 static efi_status_t efi_get_variable_common(u16 *variable_name,
 598                                             const efi_guid_t *vendor,
 599                                             u32 *attributes,
 600                                             efi_uintn_t *data_size, void *data)
 601 {
 602         char *native_name;
 603         efi_status_t ret;
 604         unsigned long in_size;
 605         const char *val = NULL, *s;
 606         u64 time = 0;
 607         u32 attr;
 608
 609         if (!variable_name || !vendor || !data_size)
 610                 return EFI_EXIT(EFI_INVALID_PARAMETER);
 611
 612         ret = efi_to_native(&native_name, variable_name, vendor);
 613         if (ret)
 614                 return ret;
 615
 616         EFI_PRINT("get '%s'\n", native_name);
 617
 618         val = env_get(native_name);
 619         free(native_name);
 620         if (!val)
 621                 return EFI_NOT_FOUND;
 622
 623         val = parse_attr(val, &attr, &time);
 624
 625         in_size = *data_size;
 626
 627         if ((s = prefix(val, "(blob)"))) {
 628                 size_t len = strlen(s);
 629
 630                 /* number of hexadecimal digits must be even */
 631                 if (len & 1)
 632                         return EFI_DEVICE_ERROR;
 633
 634                 /* two characters per byte: */
 635                 len /= 2;
 636                 *data_size = len;
 637
 638                 if (in_size < len) {
 639                         ret = EFI_BUFFER_TOO_SMALL;
 640                         goto out;
 641                 }
 642
 643                 if (!data) {
 644                         debug("Variable with no data shouldn't exist.\n");
 645                         return EFI_INVALID_PARAMETER;
 646                 }
 647
 648                 if (hex2bin(data, s, len))
 649                         return EFI_DEVICE_ERROR;
 650
 651                 EFI_PRINT("got value: \"%s\"\n", s);
 652         } else if ((s = prefix(val, "(utf8)"))) {
 653                 unsigned len = strlen(s) + 1;
 654
 655                 *data_size = len;
 656
 657                 if (in_size < len) {
 658                         ret = EFI_BUFFER_TOO_SMALL;
 659                         goto out;
 660                 }
 661
 662                 if (!data) {
 663                         debug("Variable with no data shouldn't exist.\n");
 664                         return EFI_INVALID_PARAMETER;
 665                 }
 666
 667                 memcpy(data, s, len);
 668                 ((char *)data)[len] = '\0';
 669
 670                 EFI_PRINT("got value: \"%s\"\n", (char *)data);
 671         } else {
 672                 EFI_PRINT("invalid value: '%s'\n", val);
 673                 return EFI_DEVICE_ERROR;
 674         }
 675
 676 out:
 677         if (attributes)
 678                 *attributes = attr & EFI_VARIABLE_MASK;
 679
 680         return ret;
 681 }
 682
 683 /**
 684  * efi_efi_get_variable() - retrieve value of a UEFI variable
 685  *
 686  * This function implements the GetVariable runtime service.
 687  *
 688  * See the Unified Extensible Firmware Interface (UEFI) specification for
 689  * details.
 690  *
 691  * @variable_name:      name of the variable
 692  * @vendor:             vendor GUID
 693  * @attributes:         attributes of the variable
 694  * @data_size:          size of the buffer to which the variable value is copied
 695  * @data:               buffer to which the variable value is copied
 696  * Return:              status code
 697  */
 698 efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
 699                                      const efi_guid_t *vendor, u32 *attributes,
 700                                      efi_uintn_t *data_size, void *data)
 701 {
 702         efi_status_t ret;
 703
 704         EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
 705                   data_size, data);
 706
 707         ret = efi_get_variable_common(variable_name, vendor, attributes,
 708                                       data_size, data);
 709         return EFI_EXIT(ret);
 710 }
 711
 712 static char *efi_variables_list;
 713 static char *efi_cur_variable;
 714
 715 /**
 716  * parse_uboot_variable() - parse a u-boot variable and get uefi-related
 717  *                          information
 718  * @variable:           whole data of u-boot variable (ie. name=value)
 719  * @variable_name_size: size of variable_name buffer in byte
 720  * @variable_name:      name of uefi variable in u16, null-terminated
 721  * @vendor:             vendor's guid
 722  * @attributes:         attributes
 723  *
 724  * A uefi variable is encoded into a u-boot variable as described above.
 725  * This function parses such a u-boot variable and retrieve uefi-related
 726  * information into respective parameters. In return, variable_name_size
 727  * is the size of variable name including NULL.
 728  *
 729  * Return:              EFI_SUCCESS if parsing is OK, EFI_NOT_FOUND when
 730  *                      the entire variable list has been returned,
 731  *                      otherwise non-zero status code
 732  */
 733 static efi_status_t parse_uboot_variable(char *variable,
 734                                          efi_uintn_t *variable_name_size,
 735                                          u16 *variable_name,
 736                                          const efi_guid_t *vendor,
 737                                          u32 *attributes)
 738 {
 739         char *guid, *name, *end, c;
 740         size_t name_len;
 741         efi_uintn_t old_variable_name_size;
 742         u64 time;
 743         u16 *p;
 744
 745         guid = strchr(variable, '_');
 746         if (!guid)
 747                 return EFI_INVALID_PARAMETER;
 748         guid++;
 749         name = strchr(guid, '_');
 750         if (!name)
 751                 return EFI_INVALID_PARAMETER;
 752         name++;
 753         end = strchr(name, '=');
 754         if (!end)
 755                 return EFI_INVALID_PARAMETER;
 756
 757         name_len = end - name;
 758         old_variable_name_size = *variable_name_size;
 759         *variable_name_size = sizeof(u16) * (name_len + 1);
 760         if (old_variable_name_size < *variable_name_size)
 761                 return EFI_BUFFER_TOO_SMALL;
 762
 763         end++; /* point to value */
 764
 765         /* variable name */
 766         p = variable_name;
 767         utf8_utf16_strncpy(&p, name, name_len);
 768         variable_name[name_len] = 0;
 769
 770         /* guid */
 771         c = *(name - 1);
 772         *(name - 1) = '\0'; /* guid need be null-terminated here */
 773         if (uuid_str_to_bin(guid, (unsigned char *)vendor,
 774                             UUID_STR_FORMAT_GUID))
 775                 /* The only error would be EINVAL. */
 776                 return EFI_INVALID_PARAMETER;
 777         *(name - 1) = c;
 778
 779         /* attributes */
 780         parse_attr(end, attributes, &time);
 781
 782         return EFI_SUCCESS;
 783 }
 784
 785 /**
 786  * efi_get_next_variable_name() - enumerate the current variable names
 787  *
 788  * @variable_name_size: size of variable_name buffer in byte
 789  * @variable_name:      name of uefi variable's name in u16
 790  * @vendor:             vendor's guid
 791  *
 792  * This function implements the GetNextVariableName service.
 793  *
 794  * See the Unified Extensible Firmware Interface (UEFI) specification for
 795  * details.
 796  *
 797  * Return: status code
 798  */
 799 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
 800                                                u16 *variable_name,
 801                                                efi_guid_t *vendor)
 802 {
 803         char *native_name, *variable;
 804         ssize_t name_len, list_len;
 805         char regex[256];
 806         char * const regexlist[] = {regex};
 807         u32 attributes;
 808         int i;
 809         efi_status_t ret;
 810
 811         EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
 812
 813         if (!variable_name_size || !variable_name || !vendor)
 814                 return EFI_EXIT(EFI_INVALID_PARAMETER);
 815
 816         if (variable_name[0]) {
 817                 /* check null-terminated string */
 818                 for (i = 0; i < *variable_name_size; i++)
 819                         if (!variable_name[i])
 820                                 break;
 821                 if (i >= *variable_name_size)
 822                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 823
 824                 /* search for the last-returned variable */
 825                 ret = efi_to_native(&native_name, variable_name, vendor);
 826                 if (ret)
 827                         return EFI_EXIT(ret);
 828
 829                 name_len = strlen(native_name);
 830                 for (variable = efi_variables_list; variable && *variable;) {
 831                         if (!strncmp(variable, native_name, name_len) &&
 832                             variable[name_len] == '=')
 833                                 break;
 834
 835                         variable = strchr(variable, '\n');
 836                         if (variable)
 837                                 variable++;
 838                 }
 839
 840                 free(native_name);
 841                 if (!(variable && *variable))
 842                         return EFI_EXIT(EFI_INVALID_PARAMETER);
 843
 844                 /* next variable */
 845                 variable = strchr(variable, '\n');
 846                 if (variable)
 847                         variable++;
 848                 if (!(variable && *variable))
 849                         return EFI_EXIT(EFI_NOT_FOUND);
 850         } else {
 851                 /*
 852                  *new search: free a list used in the previous search
 853                  */
 854                 free(efi_variables_list);
 855                 efi_variables_list = NULL;
 856                 efi_cur_variable = NULL;
 857
 858                 snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_.*");
 859                 list_len = hexport_r(&env_htab, '\n',
 860                                      H_MATCH_REGEX | H_MATCH_KEY,
 861                                      &efi_variables_list, 0, 1, regexlist);
 862
 863                 if (list_len <= 1)
 864                         return EFI_EXIT(EFI_NOT_FOUND);
 865
 866                 variable = efi_variables_list;
 867         }
 868
 869         ret = parse_uboot_variable(variable, variable_name_size, variable_name,
 870                                    vendor, &attributes);
 871
 872         return EFI_EXIT(ret);
 873 }
 874
 875 static efi_status_t efi_set_variable_common(u16 *variable_name,
 876                                             const efi_guid_t *vendor,
 877                                             u32 attributes,
 878                                             efi_uintn_t data_size,
 879                                             const void *data,
 880                                             bool ro_check)
 881 {
 882         char *native_name = NULL, *old_data = NULL, *val = NULL, *s;
 883         efi_uintn_t old_size;
 884         bool append, delete;
 885         u64 time = 0;
 886         u32 attr;
 887         efi_status_t ret = EFI_SUCCESS;
 888
 889         if (!variable_name || !*variable_name || !vendor ||
 890             ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
 891              !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS))) {
 892                 ret = EFI_INVALID_PARAMETER;
 893                 goto err;
 894         }
 895
 896         ret = efi_to_native(&native_name, variable_name, vendor);
 897         if (ret)
 898                 goto err;
 899
 900         /* check if a variable exists */
 901         old_size = 0;
 902         attr = 0;
 903         ret = efi_get_variable_common(variable_name, vendor, &attr,
 904                                       &old_size, NULL);
 905         append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
 906         attributes &= ~(u32)EFI_VARIABLE_APPEND_WRITE;
 907         delete = !append && (!data_size || !attributes);
 908
 909         /* check attributes */
 910         if (old_size) {
 911                 if (ro_check && (attr & READ_ONLY)) {
 912                         ret = EFI_WRITE_PROTECTED;
 913                         goto err;
 914                 }
 915
 916                 /* attributes won't be changed */
 917                 if (!delete &&
 918                     ((ro_check && attr != attributes) ||
 919                      (!ro_check && ((attr & ~(u32)READ_ONLY)
 920                                     != (attributes & ~(u32)READ_ONLY))))) {
 921                         ret = EFI_INVALID_PARAMETER;
 922                         goto err;
 923                 }
 924         } else {
 925                 if (delete || append) {
 926                         /*
 927                          * Trying to delete or to update a non-existent
 928                          * variable.
 929                          */
 930                         ret = EFI_NOT_FOUND;
 931                         goto err;
 932                 }
 933         }
 934
 935         if (((!u16_strcmp(variable_name, L"PK") ||
 936               !u16_strcmp(variable_name, L"KEK")) &&
 937                 !guidcmp(vendor, &efi_global_variable_guid)) ||
 938             ((!u16_strcmp(variable_name, L"db") ||
 939               !u16_strcmp(variable_name, L"dbx")) &&
 940                 !guidcmp(vendor, &efi_guid_image_security_database))) {
 941                 /* authentication is mandatory */
 942                 if (!(attributes &
 943                       EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
 944                         debug("%ls: AUTHENTICATED_WRITE_ACCESS required\n",
 945                               variable_name);
 946                         ret = EFI_INVALID_PARAMETER;
 947                         goto err;
 948                 }
 949         }
 950
 951         /* authenticate a variable */
 952         if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT)) {
 953                 if (attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS) {
 954                         ret = EFI_INVALID_PARAMETER;
 955                         goto err;
 956                 }
 957                 if (attributes &
 958                     EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
 959                         ret = efi_variable_authenticate(variable_name, vendor,
 960                                                         &data_size, &data,
 961                                                         attributes, &attr,
 962                                                         &time);
 963                         if (ret != EFI_SUCCESS)
 964                                 goto err;
 965
 966                         /* last chance to check for delete */
 967                         if (!data_size)
 968                                 delete = true;
 969                 }
 970         } else {
 971                 if (attributes &
 972                     (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS |
 973                      EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
 974                         debug("Secure boot is not configured\n");
 975                         ret = EFI_INVALID_PARAMETER;
 976                         goto err;
 977                 }
 978         }
 979
 980         /* delete a variable */
 981         if (delete) {
 982                 /* !old_size case has been handled before */
 983                 val = NULL;
 984                 ret = EFI_SUCCESS;
 985                 goto out;
 986         }
 987
 988         if (append) {
 989                 old_data = malloc(old_size);
 990                 if (!old_data) {
 991                         ret = EFI_OUT_OF_RESOURCES;
 992                         goto err;
 993                 }
 994                 ret = efi_get_variable_common(variable_name, vendor,
 995                                               &attr, &old_size, old_data);
 996                 if (ret != EFI_SUCCESS)
 997                         goto err;
 998         } else {
 999                 old_size = 0;
1000         }
1001
1002         val = malloc(2 * old_size + 2 * data_size
1003                      + strlen("{ro,run,boot,nv,time=0123456701234567}(blob)")
1004                      + 1);
1005         if (!val) {
1006                 ret = EFI_OUT_OF_RESOURCES;
1007                 goto err;
1008         }
1009
1010         s = val;
1011
1012         /*
1013          * store attributes
1014          */
1015         attributes &= (READ_ONLY |
1016                        EFI_VARIABLE_NON_VOLATILE |
1017                        EFI_VARIABLE_BOOTSERVICE_ACCESS |
1018                        EFI_VARIABLE_RUNTIME_ACCESS |
1019                        EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS);
1020         s += sprintf(s, "{");
1021         while (attributes) {
1022                 attr = 1 << (ffs(attributes) - 1);
1023
1024                 if (attr == READ_ONLY) {
1025                         s += sprintf(s, "ro");
1026                 } else if (attr == EFI_VARIABLE_NON_VOLATILE) {
1027                         s += sprintf(s, "nv");
1028                 } else if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS) {
1029                         s += sprintf(s, "boot");
1030                 } else if (attr == EFI_VARIABLE_RUNTIME_ACCESS) {
1031                         s += sprintf(s, "run");
1032                 } else if (attr ==
1033                            EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
1034                         s += sprintf(s, "time=");
1035                         s = bin2hex(s, (u8 *)&time, sizeof(time));
1036                 }
1037
1038                 attributes &= ~attr;
1039                 if (attributes)
1040                         s += sprintf(s, ",");
1041         }
1042         s += sprintf(s, "}");
1043         s += sprintf(s, "(blob)");
1044
1045         /* store payload: */
1046         if (append)
1047                 s = bin2hex(s, old_data, old_size);
1048         s = bin2hex(s, data, data_size);
1049         *s = '\0';
1050
1051         EFI_PRINT("setting: %s=%s\n", native_name, val);
1052
1053 out:
1054         if (env_set(native_name, val)) {
1055                 ret = EFI_DEVICE_ERROR;
1056         } else {
1057                 bool vendor_keys_modified = false;
1058
1059                 if ((u16_strcmp(variable_name, L"PK") == 0 &&
1060                      guidcmp(vendor, &efi_global_variable_guid) == 0)) {
1061                         ret = efi_transfer_secure_state(
1062                                         (delete ? EFI_MODE_SETUP :
1063                                                   EFI_MODE_USER));
1064                         if (ret != EFI_SUCCESS)
1065                                 goto err;
1066
1067                         if (efi_secure_mode != EFI_MODE_SETUP)
1068                                 vendor_keys_modified = true;
1069                 } else if ((u16_strcmp(variable_name, L"KEK") == 0 &&
1070                      guidcmp(vendor, &efi_global_variable_guid) == 0)) {
1071                         if (efi_secure_mode != EFI_MODE_SETUP)
1072                                 vendor_keys_modified = true;
1073                 }
1074
1075                 /* update VendorKeys */
1076                 if (vendor_keys_modified & efi_vendor_keys) {
1077                         efi_vendor_keys = 0;
1078                         ret = efi_set_variable_common(
1079                                                 L"VendorKeys",
1080                                                 &efi_global_variable_guid,
1081                                                 EFI_VARIABLE_BOOTSERVICE_ACCESS
1082                                                  | EFI_VARIABLE_RUNTIME_ACCESS
1083                                                  | READ_ONLY,
1084                                                 sizeof(efi_vendor_keys),
1085                                                 &efi_vendor_keys,
1086                                                 false);
1087                 } else {
1088                         ret = EFI_SUCCESS;
1089                 }
1090         }
1091
1092 err:
1093         free(native_name);
1094         free(old_data);
1095         free(val);
1096
1097         return ret;
1098 }
1099
1100 /**
1101  * efi_set_variable() - set value of a UEFI variable
1102  *
1103  * This function implements the SetVariable runtime service.
1104  *
1105  * See the Unified Extensible Firmware Interface (UEFI) specification for
1106  * details.
1107  *
1108  * @variable_name:      name of the variable
1109  * @vendor:             vendor GUID
1110  * @attributes:         attributes of the variable
1111  * @data_size:          size of the buffer with the variable value
1112  * @data:               buffer with the variable value
1113  * Return:              status code
1114  */
1115 efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
1116                                      const efi_guid_t *vendor, u32 attributes,
1117                                      efi_uintn_t data_size, const void *data)
1118 {
1119         EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
1120                   data_size, data);
1121
1122         /* READ_ONLY bit is not part of API */
1123         attributes &= ~(u32)READ_ONLY;
1124
1125         return EFI_EXIT(efi_set_variable_common(variable_name, vendor,
1126                                                 attributes, data_size, data,
1127                                                 true));
1128 }
1129
1130 /**
1131  * efi_query_variable_info() - get information about EFI variables
1132  *
1133  * This function implements the QueryVariableInfo() runtime service.
1134  *
1135  * See the Unified Extensible Firmware Interface (UEFI) specification for
1136  * details.
1137  *
1138  * @attributes:                         bitmask to select variables to be
1139  *                                      queried
1140  * @maximum_variable_storage_size:      maximum size of storage area for the
1141  *                                      selected variable types
1142  * @remaining_variable_storage_size:    remaining size of storage are for the
1143  *                                      selected variable types
1144  * @maximum_variable_size:              maximum size of a variable of the
1145  *                                      selected type
1146  * Returns:                             status code
1147  */
1148 efi_status_t __efi_runtime EFIAPI efi_query_variable_info(
1149                         u32 attributes,
1150                         u64 *maximum_variable_storage_size,
1151                         u64 *remaining_variable_storage_size,
1152                         u64 *maximum_variable_size)
1153 {
1154         return EFI_UNSUPPORTED;
1155 }
1156
1157 /**
1158  * efi_get_variable_runtime() - runtime implementation of GetVariable()
1159  *
1160  * @variable_name:      name of the variable
1161  * @vendor:             vendor GUID
1162  * @attributes:         attributes of the variable
1163  * @data_size:          size of the buffer to which the variable value is copied
1164  * @data:               buffer to which the variable value is copied
1165  * Return:              status code
1166  */
1167 static efi_status_t __efi_runtime EFIAPI
1168 efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
1169                          u32 *attributes, efi_uintn_t *data_size, void *data)
1170 {
1171         return EFI_UNSUPPORTED;
1172 }
1173
1174 /**
1175  * efi_get_next_variable_name_runtime() - runtime implementation of
1176  *                                        GetNextVariable()
1177  *
1178  * @variable_name_size: size of variable_name buffer in byte
1179  * @variable_name:      name of uefi variable's name in u16
1180  * @vendor:             vendor's guid
1181  * Return: status code
1182  */
1183 static efi_status_t __efi_runtime EFIAPI
1184 efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
1185                                    u16 *variable_name, efi_guid_t *vendor)
1186 {
1187         return EFI_UNSUPPORTED;
1188 }
1189
1190 /**
1191  * efi_set_variable_runtime() - runtime implementation of SetVariable()
1192  *
1193  * @variable_name:      name of the variable
1194  * @vendor:             vendor GUID
1195  * @attributes:         attributes of the variable
1196  * @data_size:          size of the buffer with the variable value
1197  * @data:               buffer with the variable value
1198  * Return:              status code
1199  */
1200 static efi_status_t __efi_runtime EFIAPI
1201 efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
1202                          u32 attributes, efi_uintn_t data_size,
1203                          const void *data)
1204 {
1205         return EFI_UNSUPPORTED;
1206 }
1207
1208 /**
1209  * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
1210  */
1211 void efi_variables_boot_exit_notify(void)
1212 {
1213         efi_runtime_services.get_variable = efi_get_variable_runtime;
1214         efi_runtime_services.get_next_variable_name =
1215                                 efi_get_next_variable_name_runtime;
1216         efi_runtime_services.set_variable = efi_set_variable_runtime;
1217         efi_update_table_header_crc32(&efi_runtime_services.hdr);
1218 }
1219
1220 /**
1221  * efi_init_variables() - initialize variable services
1222  *
1223  * Return:      status code
1224  */
1225 efi_status_t efi_init_variables(void)
1226 {
1227         efi_status_t ret;
1228
1229         ret = efi_init_secure_state();
1230
1231         return ret;
1232 }