src/libsystemd/sd-journal/journal-authenticate.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   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         gcry_error_t err;
  69
  70         assert(f);
  71
  72         if (!f->seal)
  73                 return 0;
  74
  75         if (f->hmac_running)
  76                 return 0;
  77
  78         /* Prepare HMAC for next cycle */
  79         gcry_md_reset(f->hmac);
  80         FSPRG_GetKey(f->fsprg_state, key, sizeof(key), 0);
  81         err = gcry_md_setkey(f->hmac, key, sizeof(key));
  82         if (gcry_err_code(err) != GPG_ERR_NO_ERROR)
  83                 return log_debug_errno(SYNTHETIC_ERRNO(EIO),
  84                                        "gcry_md_setkey() failed with error code: %d",
  85                                        gcry_err_code(err));
  86
  87         f->hmac_running = true;
  88
  89         return 0;
  90 }
  91
  92 static int journal_file_get_epoch(JournalFile *f, uint64_t realtime, uint64_t *epoch) {
  93         uint64_t t;
  94
  95         assert(f);
  96         assert(epoch);
  97         assert(f->seal);
  98
  99         if (f->fss_start_usec == 0 ||
 100             f->fss_interval_usec == 0)
 101                 return -EOPNOTSUPP;
 102
 103         if (realtime < f->fss_start_usec)
 104                 return -ESTALE;
 105
 106         t = realtime - f->fss_start_usec;
 107         t = t / f->fss_interval_usec;
 108
 109         *epoch = t;
 110         return 0;
 111 }
 112
 113 static int journal_file_fsprg_need_evolve(JournalFile *f, uint64_t realtime) {
 114         uint64_t goal, epoch;
 115         int r;
 116         assert(f);
 117
 118         if (!f->seal)
 119                 return 0;
 120
 121         r = journal_file_get_epoch(f, realtime, &goal);
 122         if (r < 0)
 123                 return r;
 124
 125         epoch = FSPRG_GetEpoch(f->fsprg_state);
 126         if (epoch > goal)
 127                 return -ESTALE;
 128
 129         return epoch != goal;
 130 }
 131
 132 int journal_file_fsprg_evolve(JournalFile *f, uint64_t realtime) {
 133         uint64_t goal, epoch;
 134         int r;
 135
 136         assert(f);
 137
 138         if (!f->seal)
 139                 return 0;
 140
 141         r = journal_file_get_epoch(f, realtime, &goal);
 142         if (r < 0)
 143                 return r;
 144
 145         epoch = FSPRG_GetEpoch(f->fsprg_state);
 146         if (epoch < goal)
 147                 log_debug("Evolving FSPRG key from epoch %"PRIu64" to %"PRIu64".", epoch, goal);
 148
 149         for (;;) {
 150                 if (epoch > goal)
 151                         return -ESTALE;
 152                 if (epoch == goal)
 153                         return 0;
 154
 155                 FSPRG_Evolve(f->fsprg_state);
 156                 epoch = FSPRG_GetEpoch(f->fsprg_state);
 157         }
 158 }
 159
 160 int journal_file_fsprg_seek(JournalFile *f, uint64_t goal) {
 161         void *msk;
 162         uint64_t epoch;
 163
 164         assert(f);
 165
 166         if (!f->seal)
 167                 return 0;
 168
 169         assert(f->fsprg_seed);
 170
 171         if (f->fsprg_state) {
 172                 /* Cheaper... */
 173
 174                 epoch = FSPRG_GetEpoch(f->fsprg_state);
 175                 if (goal == epoch)
 176                         return 0;
 177
 178                 if (goal == epoch+1) {
 179                         FSPRG_Evolve(f->fsprg_state);
 180                         return 0;
 181                 }
 182         } else {
 183                 f->fsprg_state_size = FSPRG_stateinbytes(FSPRG_RECOMMENDED_SECPAR);
 184                 f->fsprg_state = malloc(f->fsprg_state_size);
 185                 if (!f->fsprg_state)
 186                         return -ENOMEM;
 187         }
 188
 189         log_debug("Seeking FSPRG key to %"PRIu64".", goal);
 190
 191         msk = alloca_safe(FSPRG_mskinbytes(FSPRG_RECOMMENDED_SECPAR));
 192         FSPRG_GenMK(msk, NULL, f->fsprg_seed, f->fsprg_seed_size, FSPRG_RECOMMENDED_SECPAR);
 193         FSPRG_Seek(f->fsprg_state, goal, msk, f->fsprg_seed, f->fsprg_seed_size);
 194         return 0;
 195 }
 196
 197 int journal_file_maybe_append_tag(JournalFile *f, uint64_t realtime) {
 198         int r;
 199
 200         assert(f);
 201
 202         if (!f->seal)
 203                 return 0;
 204
 205         if (realtime <= 0)
 206                 realtime = now(CLOCK_REALTIME);
 207
 208         r = journal_file_fsprg_need_evolve(f, realtime);
 209         if (r <= 0)
 210                 return 0;
 211
 212         r = journal_file_append_tag(f);
 213         if (r < 0)
 214                 return r;
 215
 216         r = journal_file_fsprg_evolve(f, realtime);
 217         if (r < 0)
 218                 return r;
 219
 220         return 0;
 221 }
 222
 223 int journal_file_hmac_put_object(JournalFile *f, ObjectType type, Object *o, uint64_t p) {
 224         int r;
 225
 226         assert(f);
 227
 228         if (!f->seal)
 229                 return 0;
 230
 231         r = journal_file_hmac_start(f);
 232         if (r < 0)
 233                 return r;
 234
 235         if (!o) {
 236                 r = journal_file_move_to_object(f, type, p, &o);
 237                 if (r < 0)
 238                         return r;
 239         } else {
 240                 if (type > OBJECT_UNUSED && o->object.type != type)
 241                         return -EBADMSG;
 242         }
 243
 244         gcry_md_write(f->hmac, o, offsetof(ObjectHeader, payload));
 245
 246         switch (o->object.type) {
 247
 248         case OBJECT_DATA:
 249                 /* All but hash and payload are mutable */
 250                 gcry_md_write(f->hmac, &o->data.hash, sizeof(o->data.hash));
 251                 gcry_md_write(f->hmac, o->data.payload, le64toh(o->object.size) - offsetof(Object, data.payload));
 252                 break;
 253
 254         case OBJECT_FIELD:
 255                 /* Same here */
 256                 gcry_md_write(f->hmac, &o->field.hash, sizeof(o->field.hash));
 257                 gcry_md_write(f->hmac, o->field.payload, le64toh(o->object.size) - offsetof(Object, field.payload));
 258                 break;
 259
 260         case OBJECT_ENTRY:
 261                 /* All */
 262                 gcry_md_write(f->hmac, &o->entry.seqnum, le64toh(o->object.size) - offsetof(Object, entry.seqnum));
 263                 break;
 264
 265         case OBJECT_FIELD_HASH_TABLE:
 266         case OBJECT_DATA_HASH_TABLE:
 267         case OBJECT_ENTRY_ARRAY:
 268                 /* Nothing: everything is mutable */
 269                 break;
 270
 271         case OBJECT_TAG:
 272                 /* All but the tag itself */
 273                 gcry_md_write(f->hmac, &o->tag.seqnum, sizeof(o->tag.seqnum));
 274                 gcry_md_write(f->hmac, &o->tag.epoch, sizeof(o->tag.epoch));
 275                 break;
 276         default:
 277                 return -EINVAL;
 278         }
 279
 280         return 0;
 281 }
 282
 283 int journal_file_hmac_put_header(JournalFile *f) {
 284         int r;
 285
 286         assert(f);
 287
 288         if (!f->seal)
 289                 return 0;
 290
 291         r = journal_file_hmac_start(f);
 292         if (r < 0)
 293                 return r;
 294
 295         /* All but state+reserved, boot_id, arena_size,
 296          * tail_object_offset, n_objects, n_entries,
 297          * tail_entry_seqnum, head_entry_seqnum, entry_array_offset,
 298          * head_entry_realtime, tail_entry_realtime,
 299          * tail_entry_monotonic, n_data, n_fields, n_tags,
 300          * n_entry_arrays. */
 301
 302         gcry_md_write(f->hmac, f->header->signature, offsetof(Header, state) - offsetof(Header, signature));
 303         gcry_md_write(f->hmac, &f->header->file_id, offsetof(Header, boot_id) - offsetof(Header, file_id));
 304         gcry_md_write(f->hmac, &f->header->seqnum_id, offsetof(Header, arena_size) - offsetof(Header, seqnum_id));
 305         gcry_md_write(f->hmac, &f->header->data_hash_table_offset, offsetof(Header, tail_object_offset) - offsetof(Header, data_hash_table_offset));
 306
 307         return 0;
 308 }
 309
 310 int journal_file_fss_load(JournalFile *f) {
 311         int r, fd = -1;
 312         char *p = NULL;
 313         struct stat st;
 314         FSSHeader *m = NULL;
 315         sd_id128_t machine;
 316
 317         assert(f);
 318
 319         if (!f->seal)
 320                 return 0;
 321
 322         r = sd_id128_get_machine(&machine);
 323         if (r < 0)
 324                 return r;
 325
 326         if (asprintf(&p, "/var/log/journal/" SD_ID128_FORMAT_STR "/fss",
 327                      SD_ID128_FORMAT_VAL(machine)) < 0)
 328                 return -ENOMEM;
 329
 330         fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
 331         if (fd < 0) {
 332                 if (errno != ENOENT)
 333                         log_error_errno(errno, "Failed to open %s: %m", p);
 334
 335                 r = -errno;
 336                 goto finish;
 337         }
 338
 339         if (fstat(fd, &st) < 0) {
 340                 r = -errno;
 341                 goto finish;
 342         }
 343
 344         if (st.st_size < (off_t) sizeof(FSSHeader)) {
 345                 r = -ENODATA;
 346                 goto finish;
 347         }
 348
 349         m = mmap(NULL, PAGE_ALIGN(sizeof(FSSHeader)), PROT_READ, MAP_SHARED, fd, 0);
 350         if (m == MAP_FAILED) {
 351                 m = NULL;
 352                 r = -errno;
 353                 goto finish;
 354         }
 355
 356         if (memcmp(m->signature, FSS_HEADER_SIGNATURE, 8) != 0) {
 357                 r = -EBADMSG;
 358                 goto finish;
 359         }
 360
 361         if (m->incompatible_flags != 0) {
 362                 r = -EPROTONOSUPPORT;
 363                 goto finish;
 364         }
 365
 366         if (le64toh(m->header_size) < sizeof(FSSHeader)) {
 367                 r = -EBADMSG;
 368                 goto finish;
 369         }
 370
 371         if (le64toh(m->fsprg_state_size) != FSPRG_stateinbytes(le16toh(m->fsprg_secpar))) {
 372                 r = -EBADMSG;
 373                 goto finish;
 374         }
 375
 376         f->fss_file_size = le64toh(m->header_size) + le64toh(m->fsprg_state_size);
 377         if ((uint64_t) st.st_size < f->fss_file_size) {
 378                 r = -ENODATA;
 379                 goto finish;
 380         }
 381
 382         if (!sd_id128_equal(machine, m->machine_id)) {
 383                 r = -EHOSTDOWN;
 384                 goto finish;
 385         }
 386
 387         if (le64toh(m->start_usec) <= 0 ||
 388             le64toh(m->interval_usec) <= 0) {
 389                 r = -EBADMSG;
 390                 goto finish;
 391         }
 392
 393         f->fss_file = mmap(NULL, PAGE_ALIGN(f->fss_file_size), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 394         if (f->fss_file == MAP_FAILED) {
 395                 f->fss_file = NULL;
 396                 r = -errno;
 397                 goto finish;
 398         }
 399
 400         f->fss_start_usec = le64toh(f->fss_file->start_usec);
 401         f->fss_interval_usec = le64toh(f->fss_file->interval_usec);
 402
 403         f->fsprg_state = (uint8_t*) f->fss_file + le64toh(f->fss_file->header_size);
 404         f->fsprg_state_size = le64toh(f->fss_file->fsprg_state_size);
 405
 406         r = 0;
 407
 408 finish:
 409         if (m)
 410                 munmap(m, PAGE_ALIGN(sizeof(FSSHeader)));
 411
 412         safe_close(fd);
 413         free(p);
 414
 415         return r;
 416 }
 417
 418 int journal_file_hmac_setup(JournalFile *f) {
 419         gcry_error_t e;
 420
 421         if (!f->seal)
 422                 return 0;
 423
 424         initialize_libgcrypt(true);
 425
 426         e = gcry_md_open(&f->hmac, GCRY_MD_SHA256, GCRY_MD_FLAG_HMAC);
 427         if (e != 0)
 428                 return -EOPNOTSUPP;
 429
 430         return 0;
 431 }
 432
 433 int journal_file_append_first_tag(JournalFile *f) {
 434         int r;
 435         uint64_t p;
 436
 437         if (!f->seal)
 438                 return 0;
 439
 440         log_debug("Calculating first tag...");
 441
 442         r = journal_file_hmac_put_header(f);
 443         if (r < 0)
 444                 return r;
 445
 446         p = le64toh(f->header->field_hash_table_offset);
 447         if (p < offsetof(Object, hash_table.items))
 448                 return -EINVAL;
 449         p -= offsetof(Object, hash_table.items);
 450
 451         r = journal_file_hmac_put_object(f, OBJECT_FIELD_HASH_TABLE, NULL, p);
 452         if (r < 0)
 453                 return r;
 454
 455         p = le64toh(f->header->data_hash_table_offset);
 456         if (p < offsetof(Object, hash_table.items))
 457                 return -EINVAL;
 458         p -= offsetof(Object, hash_table.items);
 459
 460         r = journal_file_hmac_put_object(f, OBJECT_DATA_HASH_TABLE, NULL, p);
 461         if (r < 0)
 462                 return r;
 463
 464         r = journal_file_append_tag(f);
 465         if (r < 0)
 466                 return r;
 467
 468         return 0;
 469 }
 470
 471 int journal_file_parse_verification_key(JournalFile *f, const char *key) {
 472         uint8_t *seed;
 473         size_t seed_size, c;
 474         const char *k;
 475         int r;
 476         unsigned long long start, interval;
 477
 478         seed_size = FSPRG_RECOMMENDED_SEEDLEN;
 479         seed = malloc(seed_size);
 480         if (!seed)
 481                 return -ENOMEM;
 482
 483         k = key;
 484         for (c = 0; c < seed_size; c++) {
 485                 int x, y;
 486
 487                 while (*k == '-')
 488                         k++;
 489
 490                 x = unhexchar(*k);
 491                 if (x < 0) {
 492                         free(seed);
 493                         return -EINVAL;
 494                 }
 495                 k++;
 496                 y = unhexchar(*k);
 497                 if (y < 0) {
 498                         free(seed);
 499                         return -EINVAL;
 500                 }
 501                 k++;
 502
 503                 seed[c] = (uint8_t) (x * 16 + y);
 504         }
 505
 506         if (*k != '/') {
 507                 free(seed);
 508                 return -EINVAL;
 509         }
 510         k++;
 511
 512         r = sscanf(k, "%llx-%llx", &start, &interval);
 513         if (r != 2) {
 514                 free(seed);
 515                 return -EINVAL;
 516         }
 517
 518         f->fsprg_seed = seed;
 519         f->fsprg_seed_size = seed_size;
 520
 521         f->fss_start_usec = start * interval;
 522         f->fss_interval_usec = interval;
 523
 524         return 0;
 525 }
 526
 527 bool journal_file_next_evolve_usec(JournalFile *f, usec_t *u) {
 528         uint64_t epoch;
 529
 530         assert(f);
 531         assert(u);
 532
 533         if (!f->seal)
 534                 return false;
 535
 536         epoch = FSPRG_GetEpoch(f->fsprg_state);
 537
 538         *u = (usec_t) (f->fss_start_usec + f->fss_interval_usec * epoch + f->fss_interval_usec);
 539
 540         return true;
 541 }