src/journal/journal-authenticate.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <fcntl.h>
   4 #include <sys/mman.h>
   5
   6 #include "fd-util.h"
   7 #include "fsprg.h"
   8 #include "gcrypt-util.h"
   9 #include "hexdecoct.h"
  10 #include "journal-authenticate.h"
  11 #include "journal-def.h"
  12 #include "journal-file.h"
  13 #include "memory-util.h"
  14 #include "time-util.h"
  15
  16 static uint64_t journal_file_tag_seqnum(JournalFile *f) {
  17         uint64_t r;
  18
  19         assert(f);
  20
  21         r = le64toh(f->header->n_tags) + 1;
  22         f->header->n_tags = htole64(r);
  23
  24         return r;
  25 }
  26
  27 int journal_file_append_tag(JournalFile *f) {
  28         Object *o;
  29         uint64_t p;
  30         int r;
  31
  32         assert(f);
  33
  34         if (!f->seal)
  35                 return 0;
  36
  37         if (!f->hmac_running)
  38                 return 0;
  39
  40         assert(f->hmac);
  41
  42         r = journal_file_append_object(f, OBJECT_TAG, sizeof(struct TagObject), &o, &p);
  43         if (r < 0)
  44                 return r;
  45
  46         o->tag.seqnum = htole64(journal_file_tag_seqnum(f));
  47         o->tag.epoch = htole64(FSPRG_GetEpoch(f->fsprg_state));
  48
  49         log_debug("Writing tag %"PRIu64" for epoch %"PRIu64"",
  50                   le64toh(o->tag.seqnum),
  51                   FSPRG_GetEpoch(f->fsprg_state));
  52
  53         /* Add the tag object itself, so that we can protect its
  54          * header. This will exclude the actual hash value in it */
  55         r = journal_file_hmac_put_object(f, OBJECT_TAG, o, p);
  56         if (r < 0)
  57                 return r;
  58
  59         /* Get the HMAC tag and store it in the object */
  60         memcpy(o->tag.tag, gcry_md_read(f->hmac, 0), TAG_LENGTH);
  61         f->hmac_running = false;
  62
  63         return 0;
  64 }
  65
  66 int journal_file_hmac_start(JournalFile *f) {
  67         uint8_t key[256 / 8]; /* Let's pass 256 bit from FSPRG to HMAC */
  68         assert(f);
  69
  70         if (!f->seal)
  71                 return 0;
  72
  73         if (f->hmac_running)
  74                 return 0;
  75
  76         /* Prepare HMAC for next cycle */
  77         gcry_md_reset(f->hmac);
  78         FSPRG_GetKey(f->fsprg_state, key, sizeof(key), 0);
  79         gcry_md_setkey(f->hmac, key, sizeof(key));
  80
  81         f->hmac_running = true;
  82
  83         return 0;
  84 }
  85
  86 static int journal_file_get_epoch(JournalFile *f, uint64_t realtime, uint64_t *epoch) {
  87         uint64_t t;
  88
  89         assert(f);
  90         assert(epoch);
  91         assert(f->seal);
  92
  93         if (f->fss_start_usec == 0 ||
  94             f->fss_interval_usec == 0)
  95                 return -EOPNOTSUPP;
  96
  97         if (realtime < f->fss_start_usec)
  98                 return -ESTALE;
  99
 100         t = realtime - f->fss_start_usec;
 101         t = t / f->fss_interval_usec;
 102
 103         *epoch = t;
 104         return 0;
 105 }
 106
 107 static int journal_file_fsprg_need_evolve(JournalFile *f, uint64_t realtime) {
 108         uint64_t goal, epoch;
 109         int r;
 110         assert(f);
 111
 112         if (!f->seal)
 113                 return 0;
 114
 115         r = journal_file_get_epoch(f, realtime, &goal);
 116         if (r < 0)
 117                 return r;
 118
 119         epoch = FSPRG_GetEpoch(f->fsprg_state);
 120         if (epoch > goal)
 121                 return -ESTALE;
 122
 123         return epoch != goal;
 124 }
 125
 126 int journal_file_fsprg_evolve(JournalFile *f, uint64_t realtime) {
 127         uint64_t goal, epoch;
 128         int r;
 129
 130         assert(f);
 131
 132         if (!f->seal)
 133                 return 0;
 134
 135         r = journal_file_get_epoch(f, realtime, &goal);
 136         if (r < 0)
 137                 return r;
 138
 139         epoch = FSPRG_GetEpoch(f->fsprg_state);
 140         if (epoch < goal)
 141                 log_debug("Evolving FSPRG key from epoch %"PRIu64" to %"PRIu64".", epoch, goal);
 142
 143         for (;;) {
 144                 if (epoch > goal)
 145                         return -ESTALE;
 146                 if (epoch == goal)
 147                         return 0;
 148
 149                 FSPRG_Evolve(f->fsprg_state);
 150                 epoch = FSPRG_GetEpoch(f->fsprg_state);
 151         }
 152 }
 153
 154 int journal_file_fsprg_seek(JournalFile *f, uint64_t goal) {
 155         void *msk;
 156         uint64_t epoch;
 157
 158         assert(f);
 159
 160         if (!f->seal)
 161                 return 0;
 162
 163         assert(f->fsprg_seed);
 164
 165         if (f->fsprg_state) {
 166                 /* Cheaper... */
 167
 168                 epoch = FSPRG_GetEpoch(f->fsprg_state);
 169                 if (goal == epoch)
 170                         return 0;
 171
 172                 if (goal == epoch+1) {
 173                         FSPRG_Evolve(f->fsprg_state);
 174                         return 0;
 175                 }
 176         } else {
 177                 f->fsprg_state_size = FSPRG_stateinbytes(FSPRG_RECOMMENDED_SECPAR);
 178                 f->fsprg_state = malloc(f->fsprg_state_size);
 179
 180                 if (!f->fsprg_state)
 181                         return -ENOMEM;
 182         }
 183
 184         log_debug("Seeking FSPRG key to %"PRIu64".", goal);
 185
 186         msk = alloca(FSPRG_mskinbytes(FSPRG_RECOMMENDED_SECPAR));
 187         FSPRG_GenMK(msk, NULL, f->fsprg_seed, f->fsprg_seed_size, FSPRG_RECOMMENDED_SECPAR);
 188         FSPRG_Seek(f->fsprg_state, goal, msk, f->fsprg_seed, f->fsprg_seed_size);
 189         return 0;
 190 }
 191
 192 int journal_file_maybe_append_tag(JournalFile *f, uint64_t realtime) {
 193         int r;
 194
 195         assert(f);
 196
 197         if (!f->seal)
 198                 return 0;
 199
 200         if (realtime <= 0)
 201                 realtime = now(CLOCK_REALTIME);
 202
 203         r = journal_file_fsprg_need_evolve(f, realtime);
 204         if (r <= 0)
 205                 return 0;
 206
 207         r = journal_file_append_tag(f);
 208         if (r < 0)
 209                 return r;
 210
 211         r = journal_file_fsprg_evolve(f, realtime);
 212         if (r < 0)
 213                 return r;
 214
 215         return 0;
 216 }
 217
 218 int journal_file_hmac_put_object(JournalFile *f, ObjectType type, Object *o, uint64_t p) {
 219         int r;
 220
 221         assert(f);
 222
 223         if (!f->seal)
 224                 return 0;
 225
 226         r = journal_file_hmac_start(f);
 227         if (r < 0)
 228                 return r;
 229
 230         if (!o) {
 231                 r = journal_file_move_to_object(f, type, p, &o);
 232                 if (r < 0)
 233                         return r;
 234         } else {
 235                 if (type > OBJECT_UNUSED && o->object.type != type)
 236                         return -EBADMSG;
 237         }
 238
 239         gcry_md_write(f->hmac, o, offsetof(ObjectHeader, payload));
 240
 241         switch (o->object.type) {
 242
 243         case OBJECT_DATA:
 244                 /* All but hash and payload are mutable */
 245                 gcry_md_write(f->hmac, &o->data.hash, sizeof(o->data.hash));
 246                 gcry_md_write(f->hmac, o->data.payload, le64toh(o->object.size) - offsetof(DataObject, payload));
 247                 break;
 248
 249         case OBJECT_FIELD:
 250                 /* Same here */
 251                 gcry_md_write(f->hmac, &o->field.hash, sizeof(o->field.hash));
 252                 gcry_md_write(f->hmac, o->field.payload, le64toh(o->object.size) - offsetof(FieldObject, payload));
 253                 break;
 254
 255         case OBJECT_ENTRY:
 256                 /* All */
 257                 gcry_md_write(f->hmac, &o->entry.seqnum, le64toh(o->object.size) - offsetof(EntryObject, seqnum));
 258                 break;
 259
 260         case OBJECT_FIELD_HASH_TABLE:
 261         case OBJECT_DATA_HASH_TABLE:
 262         case OBJECT_ENTRY_ARRAY:
 263                 /* Nothing: everything is mutable */
 264                 break;
 265
 266         case OBJECT_TAG:
 267                 /* All but the tag itself */
 268                 gcry_md_write(f->hmac, &o->tag.seqnum, sizeof(o->tag.seqnum));
 269                 gcry_md_write(f->hmac, &o->tag.epoch, sizeof(o->tag.epoch));
 270                 break;
 271         default:
 272                 return -EINVAL;
 273         }
 274
 275         return 0;
 276 }
 277
 278 int journal_file_hmac_put_header(JournalFile *f) {
 279         int r;
 280
 281         assert(f);
 282
 283         if (!f->seal)
 284                 return 0;
 285
 286         r = journal_file_hmac_start(f);
 287         if (r < 0)
 288                 return r;
 289
 290         /* All but state+reserved, boot_id, arena_size,
 291          * tail_object_offset, n_objects, n_entries,
 292          * tail_entry_seqnum, head_entry_seqnum, entry_array_offset,
 293          * head_entry_realtime, tail_entry_realtime,
 294          * tail_entry_monotonic, n_data, n_fields, n_tags,
 295          * n_entry_arrays. */
 296
 297         gcry_md_write(f->hmac, f->header->signature, offsetof(Header, state) - offsetof(Header, signature));
 298         gcry_md_write(f->hmac, &f->header->file_id, offsetof(Header, boot_id) - offsetof(Header, file_id));
 299         gcry_md_write(f->hmac, &f->header->seqnum_id, offsetof(Header, arena_size) - offsetof(Header, seqnum_id));
 300         gcry_md_write(f->hmac, &f->header->data_hash_table_offset, offsetof(Header, tail_object_offset) - offsetof(Header, data_hash_table_offset));
 301
 302         return 0;
 303 }
 304
 305 int journal_file_fss_load(JournalFile *f) {
 306         int r, fd = -1;
 307         char *p = NULL;
 308         struct stat st;
 309         FSSHeader *m = NULL;
 310         sd_id128_t machine;
 311
 312         assert(f);
 313
 314         if (!f->seal)
 315                 return 0;
 316
 317         r = sd_id128_get_machine(&machine);
 318         if (r < 0)
 319                 return r;
 320
 321         if (asprintf(&p, "/var/log/journal/" SD_ID128_FORMAT_STR "/fss",
 322                      SD_ID128_FORMAT_VAL(machine)) < 0)
 323                 return -ENOMEM;
 324
 325         fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
 326         if (fd < 0) {
 327                 if (errno != ENOENT)
 328                         log_error_errno(errno, "Failed to open %s: %m", p);
 329
 330                 r = -errno;
 331                 goto finish;
 332         }
 333
 334         if (fstat(fd, &st) < 0) {
 335                 r = -errno;
 336                 goto finish;
 337         }
 338
 339         if (st.st_size < (off_t) sizeof(FSSHeader)) {
 340                 r = -ENODATA;
 341                 goto finish;
 342         }
 343
 344         m = mmap(NULL, PAGE_ALIGN(sizeof(FSSHeader)), PROT_READ, MAP_SHARED, fd, 0);
 345         if (m == MAP_FAILED) {
 346                 m = NULL;
 347                 r = -errno;
 348                 goto finish;
 349         }
 350
 351         if (memcmp(m->signature, FSS_HEADER_SIGNATURE, 8) != 0) {
 352                 r = -EBADMSG;
 353                 goto finish;
 354         }
 355
 356         if (m->incompatible_flags != 0) {
 357                 r = -EPROTONOSUPPORT;
 358                 goto finish;
 359         }
 360
 361         if (le64toh(m->header_size) < sizeof(FSSHeader)) {
 362                 r = -EBADMSG;
 363                 goto finish;
 364         }
 365
 366         if (le64toh(m->fsprg_state_size) != FSPRG_stateinbytes(le16toh(m->fsprg_secpar))) {
 367                 r = -EBADMSG;
 368                 goto finish;
 369         }
 370
 371         f->fss_file_size = le64toh(m->header_size) + le64toh(m->fsprg_state_size);
 372         if ((uint64_t) st.st_size < f->fss_file_size) {
 373                 r = -ENODATA;
 374                 goto finish;
 375         }
 376
 377         if (!sd_id128_equal(machine, m->machine_id)) {
 378                 r = -EHOSTDOWN;
 379                 goto finish;
 380         }
 381
 382         if (le64toh(m->start_usec) <= 0 ||
 383             le64toh(m->interval_usec) <= 0) {
 384                 r = -EBADMSG;
 385                 goto finish;
 386         }
 387
 388         f->fss_file = mmap(NULL, PAGE_ALIGN(f->fss_file_size), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 389         if (f->fss_file == MAP_FAILED) {
 390                 f->fss_file = NULL;
 391                 r = -errno;
 392                 goto finish;
 393         }
 394
 395         f->fss_start_usec = le64toh(f->fss_file->start_usec);
 396         f->fss_interval_usec = le64toh(f->fss_file->interval_usec);
 397
 398         f->fsprg_state = (uint8_t*) f->fss_file + le64toh(f->fss_file->header_size);
 399         f->fsprg_state_size = le64toh(f->fss_file->fsprg_state_size);
 400
 401         r = 0;
 402
 403 finish:
 404         if (m)
 405                 munmap(m, PAGE_ALIGN(sizeof(FSSHeader)));
 406
 407         safe_close(fd);
 408         free(p);
 409
 410         return r;
 411 }
 412
 413 int journal_file_hmac_setup(JournalFile *f) {
 414         gcry_error_t e;
 415
 416         if (!f->seal)
 417                 return 0;
 418
 419         initialize_libgcrypt(true);
 420
 421         e = gcry_md_open(&f->hmac, GCRY_MD_SHA256, GCRY_MD_FLAG_HMAC);
 422         if (e != 0)
 423                 return -EOPNOTSUPP;
 424
 425         return 0;
 426 }
 427
 428 int journal_file_append_first_tag(JournalFile *f) {
 429         int r;
 430         uint64_t p;
 431
 432         if (!f->seal)
 433                 return 0;
 434
 435         log_debug("Calculating first tag...");
 436
 437         r = journal_file_hmac_put_header(f);
 438         if (r < 0)
 439                 return r;
 440
 441         p = le64toh(f->header->field_hash_table_offset);
 442         if (p < offsetof(Object, hash_table.items))
 443                 return -EINVAL;
 444         p -= offsetof(Object, hash_table.items);
 445
 446         r = journal_file_hmac_put_object(f, OBJECT_FIELD_HASH_TABLE, NULL, p);
 447         if (r < 0)
 448                 return r;
 449
 450         p = le64toh(f->header->data_hash_table_offset);
 451         if (p < offsetof(Object, hash_table.items))
 452                 return -EINVAL;
 453         p -= offsetof(Object, hash_table.items);
 454
 455         r = journal_file_hmac_put_object(f, OBJECT_DATA_HASH_TABLE, NULL, p);
 456         if (r < 0)
 457                 return r;
 458
 459         r = journal_file_append_tag(f);
 460         if (r < 0)
 461                 return r;
 462
 463         return 0;
 464 }
 465
 466 int journal_file_parse_verification_key(JournalFile *f, const char *key) {
 467         uint8_t *seed;
 468         size_t seed_size, c;
 469         const char *k;
 470         int r;
 471         unsigned long long start, interval;
 472
 473         seed_size = FSPRG_RECOMMENDED_SEEDLEN;
 474         seed = malloc(seed_size);
 475         if (!seed)
 476                 return -ENOMEM;
 477
 478         k = key;
 479         for (c = 0; c < seed_size; c++) {
 480                 int x, y;
 481
 482                 while (*k == '-')
 483                         k++;
 484
 485                 x = unhexchar(*k);
 486                 if (x < 0) {
 487                         free(seed);
 488                         return -EINVAL;
 489                 }
 490                 k++;
 491                 y = unhexchar(*k);
 492                 if (y < 0) {
 493                         free(seed);
 494                         return -EINVAL;
 495                 }
 496                 k++;
 497
 498                 seed[c] = (uint8_t) (x * 16 + y);
 499         }
 500
 501         if (*k != '/') {
 502                 free(seed);
 503                 return -EINVAL;
 504         }
 505         k++;
 506
 507         r = sscanf(k, "%llx-%llx", &start, &interval);
 508         if (r != 2) {
 509                 free(seed);
 510                 return -EINVAL;
 511         }
 512
 513         f->fsprg_seed = seed;
 514         f->fsprg_seed_size = seed_size;
 515
 516         f->fss_start_usec = start * interval;
 517         f->fss_interval_usec = interval;
 518
 519         return 0;
 520 }
 521
 522 bool journal_file_next_evolve_usec(JournalFile *f, usec_t *u) {
 523         uint64_t epoch;
 524
 525         assert(f);
 526         assert(u);
 527
 528         if (!f->seal)
 529                 return false;
 530
 531         epoch = FSPRG_GetEpoch(f->fsprg_state);
 532
 533         *u = (usec_t) (f->fss_start_usec + f->fss_interval_usec * epoch + f->fss_interval_usec);
 534
 535         return true;
 536 }