src/shared/efivars.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <dirent.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <limits.h>
   7 #include <linux/fs.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <sys/stat.h>
  12 #include <unistd.h>
  13
  14 #include "sd-id128.h"
  15
  16 #include "alloc-util.h"
  17 #include "chattr-util.h"
  18 #include "dirent-util.h"
  19 #include "efivars.h"
  20 #include "fd-util.h"
  21 #include "io-util.h"
  22 #include "macro.h"
  23 #include "parse-util.h"
  24 #include "stdio-util.h"
  25 #include "strv.h"
  26 #include "time-util.h"
  27 #include "utf8.h"
  28 #include "util.h"
  29 #include "virt.h"
  30
  31 #if ENABLE_EFI
  32
  33 #define LOAD_OPTION_ACTIVE            0x00000001
  34 #define MEDIA_DEVICE_PATH                   0x04
  35 #define MEDIA_HARDDRIVE_DP                  0x01
  36 #define MEDIA_FILEPATH_DP                   0x04
  37 #define SIGNATURE_TYPE_GUID                 0x02
  38 #define MBR_TYPE_EFI_PARTITION_TABLE_HEADER 0x02
  39 #define END_DEVICE_PATH_TYPE                0x7f
  40 #define END_ENTIRE_DEVICE_PATH_SUBTYPE      0xff
  41 #define EFI_OS_INDICATIONS_BOOT_TO_FW_UI    0x0000000000000001
  42
  43 struct boot_option {
  44         uint32_t attr;
  45         uint16_t path_len;
  46         uint16_t title[];
  47 } _packed_;
  48
  49 struct drive_path {
  50         uint32_t part_nr;
  51         uint64_t part_start;
  52         uint64_t part_size;
  53         char signature[16];
  54         uint8_t mbr_type;
  55         uint8_t signature_type;
  56 } _packed_;
  57
  58 struct device_path {
  59         uint8_t type;
  60         uint8_t sub_type;
  61         uint16_t length;
  62         union {
  63                 uint16_t path[0];
  64                 struct drive_path drive;
  65         };
  66 } _packed_;
  67
  68 bool is_efi_boot(void) {
  69         if (detect_container() > 0)
  70                 return false;
  71
  72         return access("/sys/firmware/efi/", F_OK) >= 0;
  73 }
  74
  75 static int read_flag(const char *varname) {
  76         _cleanup_free_ void *v = NULL;
  77         uint8_t b;
  78         size_t s;
  79         int r;
  80
  81         if (!is_efi_boot()) /* If this is not an EFI boot, assume the queried flags are zero */
  82                 return 0;
  83
  84         r = efi_get_variable(EFI_VENDOR_GLOBAL, varname, NULL, &v, &s);
  85         if (r < 0)
  86                 return r;
  87
  88         if (s != 1)
  89                 return -EINVAL;
  90
  91         b = *(uint8_t *)v;
  92         return !!b;
  93 }
  94
  95 bool is_efi_secure_boot(void) {
  96         return read_flag("SecureBoot") > 0;
  97 }
  98
  99 bool is_efi_secure_boot_setup_mode(void) {
 100         return read_flag("SetupMode") > 0;
 101 }
 102
 103 int efi_reboot_to_firmware_supported(void) {
 104         _cleanup_free_ void *v = NULL;
 105         uint64_t b;
 106         size_t s;
 107         int r;
 108
 109         if (!is_efi_boot())
 110                 return -EOPNOTSUPP;
 111
 112         r = efi_get_variable(EFI_VENDOR_GLOBAL, "OsIndicationsSupported", NULL, &v, &s);
 113         if (r == -ENOENT) /* variable doesn't exist? it's not supported then */
 114                 return -EOPNOTSUPP;
 115         if (r < 0)
 116                 return r;
 117         if (s != sizeof(uint64_t))
 118                 return -EINVAL;
 119
 120         b = *(uint64_t*) v;
 121         if (!(b & EFI_OS_INDICATIONS_BOOT_TO_FW_UI))
 122                 return -EOPNOTSUPP; /* bit unset? it's not supported then */
 123
 124         return 0;
 125 }
 126
 127 static int get_os_indications(uint64_t *os_indication) {
 128         _cleanup_free_ void *v = NULL;
 129         size_t s;
 130         int r;
 131
 132         /* Let's verify general support first */
 133         r = efi_reboot_to_firmware_supported();
 134         if (r < 0)
 135                 return r;
 136
 137         r = efi_get_variable(EFI_VENDOR_GLOBAL, "OsIndications", NULL, &v, &s);
 138         if (r == -ENOENT) {
 139                 /* Some firmware implementations that do support OsIndications and report that with
 140                  * OsIndicationsSupported will remove the OsIndications variable when it is unset. Let's pretend it's 0
 141                  * then, to hide this implementation detail. Note that this call will return -ENOENT then only if the
 142                  * support for OsIndications is missing entirely, as determined by efi_reboot_to_firmware_supported()
 143                  * above. */
 144                 *os_indication = 0;
 145                 return 0;
 146         } else if (r < 0)
 147                 return r;
 148         else if (s != sizeof(uint64_t))
 149                 return -EINVAL;
 150
 151         *os_indication = *(uint64_t *)v;
 152         return 0;
 153 }
 154
 155 int efi_get_reboot_to_firmware(void) {
 156         int r;
 157         uint64_t b;
 158
 159         r = get_os_indications(&b);
 160         if (r < 0)
 161                 return r;
 162
 163         return !!(b & EFI_OS_INDICATIONS_BOOT_TO_FW_UI);
 164 }
 165
 166 int efi_set_reboot_to_firmware(bool value) {
 167         int r;
 168         uint64_t b, b_new;
 169
 170         r = get_os_indications(&b);
 171         if (r < 0)
 172                 return r;
 173
 174         if (value)
 175                 b_new = b | EFI_OS_INDICATIONS_BOOT_TO_FW_UI;
 176         else
 177                 b_new = b & ~EFI_OS_INDICATIONS_BOOT_TO_FW_UI;
 178
 179         /* Avoid writing to efi vars store if we can due to firmware bugs. */
 180         if (b != b_new)
 181                 return efi_set_variable(EFI_VENDOR_GLOBAL, "OsIndications", &b_new, sizeof(uint64_t));
 182
 183         return 0;
 184 }
 185
 186 int efi_get_variable(
 187                 sd_id128_t vendor,
 188                 const char *name,
 189                 uint32_t *attribute,
 190                 void **value,
 191                 size_t *size) {
 192
 193         _cleanup_close_ int fd = -1;
 194         _cleanup_free_ char *p = NULL;
 195         uint32_t a;
 196         ssize_t n;
 197         struct stat st;
 198         _cleanup_free_ void *buf = NULL;
 199
 200         assert(name);
 201         assert(value);
 202         assert(size);
 203
 204         if (asprintf(&p,
 205                      "/sys/firmware/efi/efivars/%s-%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 206                      name, SD_ID128_FORMAT_VAL(vendor)) < 0)
 207                 return -ENOMEM;
 208
 209         fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC);
 210         if (fd < 0)
 211                 return -errno;
 212
 213         if (fstat(fd, &st) < 0)
 214                 return -errno;
 215         if (st.st_size < 4)
 216                 return -EIO;
 217         if (st.st_size > 4*1024*1024 + 4)
 218                 return -E2BIG;
 219
 220         n = read(fd, &a, sizeof(a));
 221         if (n < 0)
 222                 return -errno;
 223         if (n != sizeof(a))
 224                 return -EIO;
 225
 226         buf = malloc(st.st_size - 4 + 2);
 227         if (!buf)
 228                 return -ENOMEM;
 229
 230         n = read(fd, buf, (size_t) st.st_size - 4);
 231         if (n < 0)
 232                 return -errno;
 233         if (n != (ssize_t) st.st_size - 4)
 234                 return -EIO;
 235
 236         /* Always NUL terminate (2 bytes, to protect UTF-16) */
 237         ((char*) buf)[st.st_size - 4] = 0;
 238         ((char*) buf)[st.st_size - 4 + 1] = 0;
 239
 240         *value = TAKE_PTR(buf);
 241         *size = (size_t) st.st_size - 4;
 242
 243         if (attribute)
 244                 *attribute = a;
 245
 246         return 0;
 247 }
 248
 249 int efi_set_variable(
 250                 sd_id128_t vendor,
 251                 const char *name,
 252                 const void *value,
 253                 size_t size) {
 254
 255         struct var {
 256                 uint32_t attr;
 257                 char buf[];
 258         } _packed_ * _cleanup_free_ buf = NULL;
 259         _cleanup_free_ char *p = NULL;
 260         _cleanup_close_ int fd = -1;
 261         bool saved_flags_valid = false;
 262         unsigned saved_flags;
 263         int r;
 264
 265         assert(name);
 266         assert(value || size == 0);
 267
 268         if (asprintf(&p,
 269                      "/sys/firmware/efi/efivars/%s-%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 270                      name, SD_ID128_FORMAT_VAL(vendor)) < 0)
 271                 return -ENOMEM;
 272
 273         /* Newer efivarfs protects variables that are not in a whitelist with FS_IMMUTABLE_FL by default, to protect
 274          * them for accidental removal and modification. We are not changing these variables accidentally however,
 275          * hence let's unset the bit first. */
 276
 277         r = chattr_path(p, 0, FS_IMMUTABLE_FL, &saved_flags);
 278         if (r < 0 && r != -ENOENT)
 279                 log_debug_errno(r, "Failed to drop FS_IMMUTABLE_FL flag from '%s', ignoring: %m", p);
 280
 281         saved_flags_valid = r >= 0;
 282
 283         if (size == 0) {
 284                 if (unlink(p) < 0) {
 285                         r = -errno;
 286                         goto finish;
 287                 }
 288
 289                 return 0;
 290         }
 291
 292         fd = open(p, O_WRONLY|O_CREAT|O_NOCTTY|O_CLOEXEC, 0644);
 293         if (fd < 0) {
 294                 r = -errno;
 295                 goto finish;
 296         }
 297
 298         buf = malloc(sizeof(uint32_t) + size);
 299         if (!buf) {
 300                 r = -ENOMEM;
 301                 goto finish;
 302         }
 303
 304         buf->attr = EFI_VARIABLE_NON_VOLATILE|EFI_VARIABLE_BOOTSERVICE_ACCESS|EFI_VARIABLE_RUNTIME_ACCESS;
 305         memcpy(buf->buf, value, size);
 306
 307         r = loop_write(fd, buf, sizeof(uint32_t) + size, false);
 308         if (r < 0)
 309                 goto finish;
 310
 311         r = 0;
 312
 313 finish:
 314         if (saved_flags_valid) {
 315                 int q;
 316
 317                 /* Restore the original flags field, just in case */
 318                 if (fd < 0)
 319                         q = chattr_path(p, saved_flags, FS_IMMUTABLE_FL, NULL);
 320                 else
 321                         q = chattr_fd(fd, saved_flags, FS_IMMUTABLE_FL, NULL);
 322                 if (q < 0)
 323                         log_debug_errno(q, "Failed to restore FS_IMMUTABLE_FL on '%s', ignoring: %m", p);
 324         }
 325
 326         return r;
 327 }
 328
 329 int efi_get_variable_string(sd_id128_t vendor, const char *name, char **p) {
 330         _cleanup_free_ void *s = NULL;
 331         size_t ss = 0;
 332         int r;
 333         char *x;
 334
 335         r = efi_get_variable(vendor, name, NULL, &s, &ss);
 336         if (r < 0)
 337                 return r;
 338
 339         x = utf16_to_utf8(s, ss);
 340         if (!x)
 341                 return -ENOMEM;
 342
 343         *p = x;
 344         return 0;
 345 }
 346
 347 static size_t utf16_size(const uint16_t *s) {
 348         size_t l = 0;
 349
 350         while (s[l] > 0)
 351                 l++;
 352
 353         return (l+1) * sizeof(uint16_t);
 354 }
 355
 356 static void efi_guid_to_id128(const void *guid, sd_id128_t *id128) {
 357         struct uuid {
 358                 uint32_t u1;
 359                 uint16_t u2;
 360                 uint16_t u3;
 361                 uint8_t u4[8];
 362         } _packed_;
 363         const struct uuid *uuid = guid;
 364
 365         id128->bytes[0] = (uuid->u1 >> 24) & 0xff;
 366         id128->bytes[1] = (uuid->u1 >> 16) & 0xff;
 367         id128->bytes[2] = (uuid->u1 >> 8) & 0xff;
 368         id128->bytes[3] = (uuid->u1) & 0xff;
 369         id128->bytes[4] = (uuid->u2 >> 8) & 0xff;
 370         id128->bytes[5] = (uuid->u2) & 0xff;
 371         id128->bytes[6] = (uuid->u3 >> 8) & 0xff;
 372         id128->bytes[7] = (uuid->u3) & 0xff;
 373         memcpy(&id128->bytes[8], uuid->u4, sizeof(uuid->u4));
 374 }
 375
 376 int efi_get_boot_option(
 377                 uint16_t id,
 378                 char **title,
 379                 sd_id128_t *part_uuid,
 380                 char **path,
 381                 bool *active) {
 382
 383         char boot_id[9];
 384         _cleanup_free_ uint8_t *buf = NULL;
 385         size_t l;
 386         struct boot_option *header;
 387         size_t title_size;
 388         _cleanup_free_ char *s = NULL, *p = NULL;
 389         sd_id128_t p_uuid = SD_ID128_NULL;
 390         int r;
 391
 392         if (!is_efi_boot())
 393                 return -EOPNOTSUPP;
 394
 395         xsprintf(boot_id, "Boot%04X", id);
 396         r = efi_get_variable(EFI_VENDOR_GLOBAL, boot_id, NULL, (void **)&buf, &l);
 397         if (r < 0)
 398                 return r;
 399         if (l < sizeof(struct boot_option))
 400                 return -ENOENT;
 401
 402         header = (struct boot_option *)buf;
 403         title_size = utf16_size(header->title);
 404         if (title_size > l - offsetof(struct boot_option, title))
 405                 return -EINVAL;
 406
 407         if (title) {
 408                 s = utf16_to_utf8(header->title, title_size);
 409                 if (!s)
 410                         return -ENOMEM;
 411         }
 412
 413         if (header->path_len > 0) {
 414                 uint8_t *dbuf;
 415                 size_t dnext, doff;
 416
 417                 doff = offsetof(struct boot_option, title) + title_size;
 418                 dbuf = buf + doff;
 419                 if (header->path_len > l - doff)
 420                         return -EINVAL;
 421
 422                 dnext = 0;
 423                 while (dnext < header->path_len) {
 424                         struct device_path *dpath;
 425
 426                         dpath = (struct device_path *)(dbuf + dnext);
 427                         if (dpath->length < 4)
 428                                 break;
 429
 430                         /* Type 0x7F – End of Hardware Device Path, Sub-Type 0xFF – End Entire Device Path */
 431                         if (dpath->type == END_DEVICE_PATH_TYPE && dpath->sub_type == END_ENTIRE_DEVICE_PATH_SUBTYPE)
 432                                 break;
 433
 434                         dnext += dpath->length;
 435
 436                         /* Type 0x04 – Media Device Path */
 437                         if (dpath->type != MEDIA_DEVICE_PATH)
 438                                 continue;
 439
 440                         /* Sub-Type 1 – Hard Drive */
 441                         if (dpath->sub_type == MEDIA_HARDDRIVE_DP) {
 442                                 /* 0x02 – GUID Partition Table */
 443                                 if (dpath->drive.mbr_type != MBR_TYPE_EFI_PARTITION_TABLE_HEADER)
 444                                         continue;
 445
 446                                 /* 0x02 – GUID signature */
 447                                 if (dpath->drive.signature_type != SIGNATURE_TYPE_GUID)
 448                                         continue;
 449
 450                                 if (part_uuid)
 451                                         efi_guid_to_id128(dpath->drive.signature, &p_uuid);
 452                                 continue;
 453                         }
 454
 455                         /* Sub-Type 4 – File Path */
 456                         if (dpath->sub_type == MEDIA_FILEPATH_DP && !p && path) {
 457                                 p = utf16_to_utf8(dpath->path, dpath->length-4);
 458                                 if (!p)
 459                                         return  -ENOMEM;
 460
 461                                 efi_tilt_backslashes(p);
 462                                 continue;
 463                         }
 464                 }
 465         }
 466
 467         if (title)
 468                 *title = TAKE_PTR(s);
 469         if (part_uuid)
 470                 *part_uuid = p_uuid;
 471         if (path)
 472                 *path = TAKE_PTR(p);
 473         if (active)
 474                 *active = !!(header->attr & LOAD_OPTION_ACTIVE);
 475
 476         return 0;
 477 }
 478
 479 static void to_utf16(uint16_t *dest, const char *src) {
 480         int i;
 481
 482         for (i = 0; src[i] != '\0'; i++)
 483                 dest[i] = src[i];
 484         dest[i] = '\0';
 485 }
 486
 487 struct guid {
 488         uint32_t u1;
 489         uint16_t u2;
 490         uint16_t u3;
 491         uint8_t u4[8];
 492 } _packed_;
 493
 494 static void id128_to_efi_guid(sd_id128_t id, void *guid) {
 495         struct guid *uuid = guid;
 496
 497         uuid->u1 = id.bytes[0] << 24 | id.bytes[1] << 16 | id.bytes[2] << 8 | id.bytes[3];
 498         uuid->u2 = id.bytes[4] << 8 | id.bytes[5];
 499         uuid->u3 = id.bytes[6] << 8 | id.bytes[7];
 500         memcpy(uuid->u4, id.bytes+8, sizeof(uuid->u4));
 501 }
 502
 503 static uint16_t *tilt_slashes(uint16_t *s) {
 504         uint16_t *p;
 505
 506         for (p = s; *p; p++)
 507                 if (*p == '/')
 508                         *p = '\\';
 509
 510         return s;
 511 }
 512
 513 int efi_add_boot_option(
 514                 uint16_t id,
 515                 const char *title,
 516                 uint32_t part,
 517                 uint64_t pstart,
 518                 uint64_t psize,
 519                 sd_id128_t part_uuid,
 520                 const char *path) {
 521
 522         size_t size, title_len, path_len;
 523         _cleanup_free_ char *buf = NULL;
 524         struct boot_option *option;
 525         struct device_path *devicep;
 526         char boot_id[9];
 527
 528         if (!is_efi_boot())
 529                 return -EOPNOTSUPP;
 530
 531         title_len = (strlen(title)+1) * 2;
 532         path_len = (strlen(path)+1) * 2;
 533
 534         buf = malloc0(sizeof(struct boot_option) + title_len +
 535                       sizeof(struct drive_path) +
 536                       sizeof(struct device_path) + path_len);
 537         if (!buf)
 538                 return -ENOMEM;
 539
 540         /* header */
 541         option = (struct boot_option *)buf;
 542         option->attr = LOAD_OPTION_ACTIVE;
 543         option->path_len = offsetof(struct device_path, drive) + sizeof(struct drive_path) +
 544                            offsetof(struct device_path, path) + path_len +
 545                            offsetof(struct device_path, path);
 546         to_utf16(option->title, title);
 547         size = offsetof(struct boot_option, title) + title_len;
 548
 549         /* partition info */
 550         devicep = (struct device_path *)(buf + size);
 551         devicep->type = MEDIA_DEVICE_PATH;
 552         devicep->sub_type = MEDIA_HARDDRIVE_DP;
 553         devicep->length = offsetof(struct device_path, drive) + sizeof(struct drive_path);
 554         devicep->drive.part_nr = part;
 555         devicep->drive.part_start = pstart;
 556         devicep->drive.part_size = psize;
 557         devicep->drive.signature_type = SIGNATURE_TYPE_GUID;
 558         devicep->drive.mbr_type = MBR_TYPE_EFI_PARTITION_TABLE_HEADER;
 559         id128_to_efi_guid(part_uuid, devicep->drive.signature);
 560         size += devicep->length;
 561
 562         /* path to loader */
 563         devicep = (struct device_path *)(buf + size);
 564         devicep->type = MEDIA_DEVICE_PATH;
 565         devicep->sub_type = MEDIA_FILEPATH_DP;
 566         devicep->length = offsetof(struct device_path, path) + path_len;
 567         to_utf16(devicep->path, path);
 568         tilt_slashes(devicep->path);
 569         size += devicep->length;
 570
 571         /* end of path */
 572         devicep = (struct device_path *)(buf + size);
 573         devicep->type = END_DEVICE_PATH_TYPE;
 574         devicep->sub_type = END_ENTIRE_DEVICE_PATH_SUBTYPE;
 575         devicep->length = offsetof(struct device_path, path);
 576         size += devicep->length;
 577
 578         xsprintf(boot_id, "Boot%04X", id);
 579         return efi_set_variable(EFI_VENDOR_GLOBAL, boot_id, buf, size);
 580 }
 581
 582 int efi_remove_boot_option(uint16_t id) {
 583         char boot_id[9];
 584
 585         if (!is_efi_boot())
 586                 return -EOPNOTSUPP;
 587
 588         xsprintf(boot_id, "Boot%04X", id);
 589         return efi_set_variable(EFI_VENDOR_GLOBAL, boot_id, NULL, 0);
 590 }
 591
 592 int efi_get_boot_order(uint16_t **order) {
 593         _cleanup_free_ void *buf = NULL;
 594         size_t l;
 595         int r;
 596
 597         if (!is_efi_boot())
 598                 return -EOPNOTSUPP;
 599
 600         r = efi_get_variable(EFI_VENDOR_GLOBAL, "BootOrder", NULL, &buf, &l);
 601         if (r < 0)
 602                 return r;
 603
 604         if (l <= 0)
 605                 return -ENOENT;
 606
 607         if (l % sizeof(uint16_t) > 0 ||
 608             l / sizeof(uint16_t) > INT_MAX)
 609                 return -EINVAL;
 610
 611         *order = TAKE_PTR(buf);
 612         return (int) (l / sizeof(uint16_t));
 613 }
 614
 615 int efi_set_boot_order(uint16_t *order, size_t n) {
 616
 617         if (!is_efi_boot())
 618                 return -EOPNOTSUPP;
 619
 620         return efi_set_variable(EFI_VENDOR_GLOBAL, "BootOrder", order, n * sizeof(uint16_t));
 621 }
 622
 623 static int boot_id_hex(const char s[4]) {
 624         int id = 0, i;
 625
 626         for (i = 0; i < 4; i++)
 627                 if (s[i] >= '0' && s[i] <= '9')
 628                         id |= (s[i] - '0') << (3 - i) * 4;
 629                 else if (s[i] >= 'A' && s[i] <= 'F')
 630                         id |= (s[i] - 'A' + 10) << (3 - i) * 4;
 631                 else
 632                         return -EINVAL;
 633
 634         return id;
 635 }
 636
 637 static int cmp_uint16(const uint16_t *a, const uint16_t *b) {
 638         return CMP(*a, *b);
 639 }
 640
 641 int efi_get_boot_options(uint16_t **options) {
 642         _cleanup_closedir_ DIR *dir = NULL;
 643         _cleanup_free_ uint16_t *list = NULL;
 644         struct dirent *de;
 645         size_t alloc = 0;
 646         int count = 0;
 647
 648         assert(options);
 649
 650         if (!is_efi_boot())
 651                 return -EOPNOTSUPP;
 652
 653         dir = opendir("/sys/firmware/efi/efivars/");
 654         if (!dir)
 655                 return -errno;
 656
 657         FOREACH_DIRENT(de, dir, return -errno) {
 658                 int id;
 659
 660                 if (strncmp(de->d_name, "Boot", 4) != 0)
 661                         continue;
 662
 663                 if (strlen(de->d_name) != 45)
 664                         continue;
 665
 666                 if (strcmp(de->d_name + 8, "-8be4df61-93ca-11d2-aa0d-00e098032b8c") != 0)
 667                         continue;
 668
 669                 id = boot_id_hex(de->d_name + 4);
 670                 if (id < 0)
 671                         continue;
 672
 673                 if (!GREEDY_REALLOC(list, alloc, count + 1))
 674                         return -ENOMEM;
 675
 676                 list[count++] = id;
 677         }
 678
 679         typesafe_qsort(list, count, cmp_uint16);
 680
 681         *options = TAKE_PTR(list);
 682
 683         return count;
 684 }
 685
 686 static int read_usec(sd_id128_t vendor, const char *name, usec_t *u) {
 687         _cleanup_free_ char *j = NULL;
 688         int r;
 689         uint64_t x = 0;
 690
 691         assert(name);
 692         assert(u);
 693
 694         r = efi_get_variable_string(EFI_VENDOR_LOADER, name, &j);
 695         if (r < 0)
 696                 return r;
 697
 698         r = safe_atou64(j, &x);
 699         if (r < 0)
 700                 return r;
 701
 702         *u = x;
 703         return 0;
 704 }
 705
 706 int efi_loader_get_boot_usec(usec_t *firmware, usec_t *loader) {
 707         uint64_t x, y;
 708         int r;
 709
 710         assert(firmware);
 711         assert(loader);
 712
 713         if (!is_efi_boot())
 714                 return -EOPNOTSUPP;
 715
 716         r = read_usec(EFI_VENDOR_LOADER, "LoaderTimeInitUSec", &x);
 717         if (r < 0)
 718                 return r;
 719
 720         r = read_usec(EFI_VENDOR_LOADER, "LoaderTimeExecUSec", &y);
 721         if (r < 0)
 722                 return r;
 723
 724         if (y == 0 || y < x)
 725                 return -EIO;
 726
 727         if (y > USEC_PER_HOUR)
 728                 return -EIO;
 729
 730         *firmware = x;
 731         *loader = y;
 732
 733         return 0;
 734 }
 735
 736 int efi_loader_get_device_part_uuid(sd_id128_t *u) {
 737         _cleanup_free_ char *p = NULL;
 738         int r, parsed[16];
 739
 740         if (!is_efi_boot())
 741                 return -EOPNOTSUPP;
 742
 743         r = efi_get_variable_string(EFI_VENDOR_LOADER, "LoaderDevicePartUUID", &p);
 744         if (r < 0)
 745                 return r;
 746
 747         if (sscanf(p, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 748                    &parsed[0], &parsed[1], &parsed[2], &parsed[3],
 749                    &parsed[4], &parsed[5], &parsed[6], &parsed[7],
 750                    &parsed[8], &parsed[9], &parsed[10], &parsed[11],
 751                    &parsed[12], &parsed[13], &parsed[14], &parsed[15]) != 16)
 752                 return -EIO;
 753
 754         if (u) {
 755                 unsigned i;
 756
 757                 for (i = 0; i < ELEMENTSOF(parsed); i++)
 758                         u->bytes[i] = parsed[i];
 759         }
 760
 761         return 0;
 762 }
 763
 764 int efi_loader_get_entries(char ***ret) {
 765         _cleanup_free_ char16_t *entries = NULL;
 766         _cleanup_strv_free_ char **l = NULL;
 767         size_t size, i, start;
 768         int r;
 769
 770         assert(ret);
 771
 772         if (!is_efi_boot())
 773                 return -EOPNOTSUPP;
 774
 775         r = efi_get_variable(EFI_VENDOR_LOADER, "LoaderEntries", NULL, (void**) &entries, &size);
 776         if (r < 0)
 777                 return r;
 778
 779         /* The variable contains a series of individually NUL terminated UTF-16 strings. */
 780
 781         for (i = 0, start = 0;; i++) {
 782                 char *decoded;
 783                 bool end;
 784
 785                 /* Is this the end of the variable's data? */
 786                 end = i * sizeof(char16_t) >= size;
 787
 788                 /* Are we in the middle of a string? (i.e. not at the end of the variable, nor at a NUL terminator?) If
 789                  * so, let's go to the next entry. */
 790                 if (!end && entries[i] != 0)
 791                         continue;
 792
 793                 /* We reached the end of a string, let's decode it into UTF-8 */
 794                 decoded = utf16_to_utf8(entries + start, (i - start) * sizeof(char16_t));
 795                 if (!decoded)
 796                         return -ENOMEM;
 797
 798                 r = strv_consume(&l, decoded);
 799                 if (r < 0)
 800                         return r;
 801
 802                 /* We reached the end of the variable */
 803                 if (end)
 804                         break;
 805
 806                 /* Continue after the NUL byte */
 807                 start = i + 1;
 808         }
 809
 810         *ret = TAKE_PTR(l);
 811         return 0;
 812 }
 813
 814 #endif
 815
 816 char *efi_tilt_backslashes(char *s) {
 817         char *p;
 818
 819         for (p = s; *p; p++)
 820                 if (*p == '\\')
 821                         *p = '/';
 822
 823         return s;
 824 }