src/import/pull-common.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <sys/prctl.h>
   4
   5 #include "alloc-util.h"
   6 #include "btrfs-util.h"
   7 #include "capability-util.h"
   8 #include "copy.h"
   9 #include "dirent-util.h"
  10 #include "escape.h"
  11 #include "fd-util.h"
  12 #include "hostname-util.h"
  13 #include "io-util.h"
  14 #include "memory-util.h"
  15 #include "path-util.h"
  16 #include "process-util.h"
  17 #include "pull-common.h"
  18 #include "pull-job.h"
  19 #include "rlimit-util.h"
  20 #include "rm-rf.h"
  21 #include "signal-util.h"
  22 #include "siphash24.h"
  23 #include "string-util.h"
  24 #include "strv.h"
  25 #include "util.h"
  26 #include "web-util.h"
  27
  28 #define FILENAME_ESCAPE "/.#\"\'"
  29 #define HASH_URL_THRESHOLD_LENGTH (_POSIX_PATH_MAX - 16)
  30
  31 int pull_find_old_etags(
  32                 const char *url,
  33                 const char *image_root,
  34                 int dt,
  35                 const char *prefix,
  36                 const char *suffix,
  37                 char ***etags) {
  38
  39         int r;
  40
  41         assert(url);
  42         assert(etags);
  43
  44         if (!image_root)
  45                 image_root = "/var/lib/machines";
  46
  47         _cleanup_free_ char *escaped_url = xescape(url, FILENAME_ESCAPE);
  48         if (!escaped_url)
  49                 return -ENOMEM;
  50
  51         _cleanup_closedir_ DIR *d = opendir(image_root);
  52         if (!d) {
  53                 if (errno == ENOENT) {
  54                         *etags = NULL;
  55                         return 0;
  56                 }
  57
  58                 return -errno;
  59         }
  60
  61         _cleanup_strv_free_ char **ans = NULL;
  62
  63         FOREACH_DIRENT_ALL(de, d, return -errno) {
  64                 _cleanup_free_ char *u = NULL;
  65                 const char *a, *b;
  66
  67                 if (de->d_type != DT_UNKNOWN &&
  68                     de->d_type != dt)
  69                         continue;
  70
  71                 if (prefix) {
  72                         a = startswith(de->d_name, prefix);
  73                         if (!a)
  74                                 continue;
  75                 } else
  76                         a = de->d_name;
  77
  78                 a = startswith(a, escaped_url);
  79                 if (!a)
  80                         continue;
  81
  82                 a = startswith(a, ".");
  83                 if (!a)
  84                         continue;
  85
  86                 if (suffix) {
  87                         b = endswith(de->d_name, suffix);
  88                         if (!b)
  89                                 continue;
  90                 } else
  91                         b = strchr(de->d_name, 0);
  92
  93                 if (a >= b)
  94                         continue;
  95
  96                 ssize_t l = cunescape_length(a, b - a, 0, &u);
  97                 if (l < 0) {
  98                         assert(l >= INT8_MIN);
  99                         return l;
 100                 }
 101
 102                 if (!http_etag_is_valid(u))
 103                         continue;
 104
 105                 r = strv_consume(&ans, TAKE_PTR(u));
 106                 if (r < 0)
 107                         return r;
 108         }
 109
 110         *etags = TAKE_PTR(ans);
 111
 112         return 0;
 113 }
 114
 115 static int hash_url(const char *url, char **ret) {
 116         uint64_t h;
 117         static const sd_id128_t k = SD_ID128_ARRAY(df,89,16,87,01,cc,42,30,98,ab,4a,19,a6,a5,63,4f);
 118
 119         assert(url);
 120
 121         h = siphash24(url, strlen(url), k.bytes);
 122         if (asprintf(ret, "%"PRIx64, h) < 0)
 123                 return -ENOMEM;
 124
 125         return 0;
 126 }
 127
 128 int pull_make_path(const char *url, const char *etag, const char *image_root, const char *prefix, const char *suffix, char **ret) {
 129         _cleanup_free_ char *escaped_url = NULL, *escaped_etag = NULL;
 130         char *path;
 131
 132         assert(url);
 133         assert(ret);
 134
 135         if (!image_root)
 136                 image_root = "/var/lib/machines";
 137
 138         escaped_url = xescape(url, FILENAME_ESCAPE);
 139         if (!escaped_url)
 140                 return -ENOMEM;
 141
 142         if (etag) {
 143                 escaped_etag = xescape(etag, FILENAME_ESCAPE);
 144                 if (!escaped_etag)
 145                         return -ENOMEM;
 146         }
 147
 148         path = strjoin(image_root, "/", strempty(prefix), escaped_url, escaped_etag ? "." : "",
 149                        strempty(escaped_etag), strempty(suffix));
 150         if (!path)
 151                 return -ENOMEM;
 152
 153         /* URLs might make the path longer than the maximum allowed length for a file name.
 154          * When that happens, a URL hash is used instead. Paths returned by this function
 155          * can be later used with tempfn_random() which adds 16 bytes to the resulting name. */
 156         if (strlen(path) >= HASH_URL_THRESHOLD_LENGTH) {
 157                 _cleanup_free_ char *hash = NULL;
 158                 int r;
 159
 160                 free(path);
 161
 162                 r = hash_url(url, &hash);
 163                 if (r < 0)
 164                         return r;
 165
 166                 path = strjoin(image_root, "/", strempty(prefix), hash, escaped_etag ? "." : "",
 167                                strempty(escaped_etag), strempty(suffix));
 168                 if (!path)
 169                         return -ENOMEM;
 170         }
 171
 172         *ret = path;
 173         return 0;
 174 }
 175
 176 int pull_make_auxiliary_job(
 177                 PullJob **ret,
 178                 const char *url,
 179                 int (*strip_suffixes)(const char *name, char **ret),
 180                 const char *suffix,
 181                 ImportVerify verify,
 182                 CurlGlue *glue,
 183                 PullJobOpenDisk on_open_disk,
 184                 PullJobFinished on_finished,
 185                 void *userdata) {
 186
 187         _cleanup_free_ char *last_component = NULL, *ll = NULL, *auxiliary_url = NULL;
 188         _cleanup_(pull_job_unrefp) PullJob *job = NULL;
 189         const char *q;
 190         int r;
 191
 192         assert(ret);
 193         assert(url);
 194         assert(strip_suffixes);
 195         assert(glue);
 196
 197         r = import_url_last_component(url, &last_component);
 198         if (r < 0)
 199                 return r;
 200
 201         r = strip_suffixes(last_component, &ll);
 202         if (r < 0)
 203                 return r;
 204
 205         q = strjoina(ll, suffix);
 206
 207         r = import_url_change_last_component(url, q, &auxiliary_url);
 208         if (r < 0)
 209                 return r;
 210
 211         r = pull_job_new(&job, auxiliary_url, glue, userdata);
 212         if (r < 0)
 213                 return r;
 214
 215         job->on_open_disk = on_open_disk;
 216         job->on_finished = on_finished;
 217         job->compressed_max = job->uncompressed_max = 1ULL * 1024ULL * 1024ULL;
 218         job->calc_checksum = IN_SET(verify, IMPORT_VERIFY_CHECKSUM, IMPORT_VERIFY_SIGNATURE);
 219
 220         *ret = TAKE_PTR(job);
 221         return 0;
 222 }
 223
 224 static bool is_checksum_file(const char *fn) {
 225         /* Returns true if the specified filename refers to a checksum file we grok */
 226
 227         if (!fn)
 228                 return false;
 229
 230         return streq(fn, "SHA256SUMS") || endswith(fn, ".sha256");
 231 }
 232
 233 static bool is_signature_file(const char *fn) {
 234         /* Returns true if the specified filename refers to a signature file we grok (reminder:
 235          * suse-style .sha256 files are inline signed) */
 236
 237         if (!fn)
 238                 return false;
 239
 240         return streq(fn, "SHA256SUMS.gpg") || endswith(fn, ".sha256");
 241 }
 242
 243 int pull_make_verification_jobs(
 244                 PullJob **ret_checksum_job,
 245                 PullJob **ret_signature_job,
 246                 ImportVerify verify,
 247                 const char *checksum, /* set if literal checksum verification is requested, in which case 'verify' is set to _IMPORT_VERIFY_INVALID */
 248                 const char *url,
 249                 CurlGlue *glue,
 250                 PullJobFinished on_finished,
 251                 void *userdata) {
 252
 253         _cleanup_(pull_job_unrefp) PullJob *checksum_job = NULL, *signature_job = NULL;
 254         _cleanup_free_ char *fn = NULL;
 255         int r;
 256
 257         assert(ret_checksum_job);
 258         assert(ret_signature_job);
 259         assert(verify == _IMPORT_VERIFY_INVALID || verify < _IMPORT_VERIFY_MAX);
 260         assert(verify == _IMPORT_VERIFY_INVALID || verify >= 0);
 261         assert((verify < 0) || !checksum);
 262         assert(url);
 263         assert(glue);
 264
 265         /* If verification is turned off, or if the checksum to validate is already specified we don't need
 266          * to download a checksum file or signature, hence shortcut things */
 267         if (verify == IMPORT_VERIFY_NO || checksum) {
 268                 *ret_checksum_job = *ret_signature_job = NULL;
 269                 return 0;
 270         }
 271
 272         r = import_url_last_component(url, &fn);
 273         if (r < 0 && r != -EADDRNOTAVAIL) /* EADDRNOTAVAIL means there was no last component, which is OK for
 274                                            * us, we'll just assume it's not a checksum/signature file */
 275                 return r;
 276
 277         /* Acquire the checksum file if verification or signature verification is requested and the main file
 278          * to acquire isn't a checksum or signature file anyway */
 279         if (verify != IMPORT_VERIFY_NO && !is_checksum_file(fn) && !is_signature_file(fn)) {
 280                 _cleanup_free_ char *checksum_url = NULL;
 281                 const char *suffixed = NULL;
 282
 283                 /* Queue jobs for the checksum file for the image. */
 284
 285                 if (fn)
 286                         suffixed = strjoina(fn, ".sha256"); /* Start with the suse-style checksum (if there's a base filename) */
 287                 else
 288                         suffixed = "SHA256SUMS";
 289
 290                 r = import_url_change_last_component(url, suffixed, &checksum_url);
 291                 if (r < 0)
 292                         return r;
 293
 294                 r = pull_job_new(&checksum_job, checksum_url, glue, userdata);
 295                 if (r < 0)
 296                         return r;
 297
 298                 checksum_job->on_finished = on_finished;
 299                 checksum_job->uncompressed_max = checksum_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 300                 checksum_job->on_not_found = pull_job_restart_with_sha256sum; /* if this fails, look for ubuntu-style checksum */
 301         }
 302
 303         if (verify == IMPORT_VERIFY_SIGNATURE && !is_signature_file(fn)) {
 304                 _cleanup_free_ char *signature_url = NULL;
 305
 306                 /* Queue job for the SHA256SUMS.gpg file for the image. */
 307                 r = import_url_change_last_component(url, "SHA256SUMS.gpg", &signature_url);
 308                 if (r < 0)
 309                         return r;
 310
 311                 r = pull_job_new(&signature_job, signature_url, glue, userdata);
 312                 if (r < 0)
 313                         return r;
 314
 315                 signature_job->on_finished = on_finished;
 316                 signature_job->uncompressed_max = signature_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 317         }
 318
 319         *ret_checksum_job = TAKE_PTR(checksum_job);
 320         *ret_signature_job = TAKE_PTR(signature_job);
 321         return 0;
 322 }
 323
 324 static int verify_one(PullJob *checksum_job, PullJob *job) {
 325         _cleanup_free_ char *fn = NULL;
 326         const char *line, *p;
 327         int r;
 328
 329         assert(checksum_job);
 330
 331         if (!job)
 332                 return 0;
 333
 334         assert(IN_SET(job->state, PULL_JOB_DONE, PULL_JOB_FAILED));
 335
 336         /* Don't verify the checksum if we didn't actually successfully download something new */
 337         if (job->state != PULL_JOB_DONE)
 338                 return 0;
 339         if (job->error != 0)
 340                 return 0;
 341         if (job->etag_exists)
 342                 return 0;
 343
 344         assert(job->calc_checksum);
 345         assert(job->checksum);
 346
 347         r = import_url_last_component(job->url, &fn);
 348         if (r < 0)
 349                 return log_error_errno(r, "Failed to extract filename from URL '%s': %m", job->url);
 350
 351         if (!filename_is_valid(fn))
 352                 return log_error_errno(SYNTHETIC_ERRNO(EBADMSG),
 353                                        "Cannot verify checksum, could not determine server-side file name.");
 354
 355         if (is_checksum_file(fn) || is_signature_file(fn)) /* We cannot verify checksum files or signature files with a checksum file */
 356                 return log_error_errno(SYNTHETIC_ERRNO(ELOOP),
 357                                        "Cannot verify checksum/signature files via themselves.");
 358
 359         line = strjoina(job->checksum, " *", fn, "\n"); /* string for binary mode */
 360         p = memmem_safe(checksum_job->payload,
 361                         checksum_job->payload_size,
 362                         line,
 363                         strlen(line));
 364         if (!p) {
 365                 line = strjoina(job->checksum, "  ", fn, "\n"); /* string for text mode */
 366                 p = memmem_safe(checksum_job->payload,
 367                                 checksum_job->payload_size,
 368                                 line,
 369                                 strlen(line));
 370         }
 371
 372         /* Only counts if found at beginning of a line */
 373         if (!p || (p != (char*) checksum_job->payload && p[-1] != '\n'))
 374                 return log_error_errno(SYNTHETIC_ERRNO(EBADMSG),
 375                                        "DOWNLOAD INVALID: Checksum of %s file did not check out, file has been tampered with.", fn);
 376
 377         log_info("SHA256 checksum of %s is valid.", job->url);
 378         return 1;
 379 }
 380
 381 static int verify_gpg(
 382                 const void *payload, size_t payload_size,
 383                 const void *signature, size_t signature_size) {
 384
 385         _cleanup_close_pair_ int gpg_pipe[2] = { -1, -1 };
 386         char sig_file_path[] = "/tmp/sigXXXXXX", gpg_home[] = "/tmp/gpghomeXXXXXX";
 387         _cleanup_(sigkill_waitp) pid_t pid = 0;
 388         bool gpg_home_created = false;
 389         int r;
 390
 391         assert(payload || payload_size == 0);
 392         assert(signature || signature_size == 0);
 393
 394         r = pipe2(gpg_pipe, O_CLOEXEC);
 395         if (r < 0)
 396                 return log_error_errno(errno, "Failed to create pipe for gpg: %m");
 397
 398         if (signature_size > 0) {
 399                 _cleanup_close_ int sig_file = -1;
 400
 401                 sig_file = mkostemp(sig_file_path, O_RDWR);
 402                 if (sig_file < 0)
 403                         return log_error_errno(errno, "Failed to create temporary file: %m");
 404
 405                 r = loop_write(sig_file, signature, signature_size, false);
 406                 if (r < 0) {
 407                         log_error_errno(r, "Failed to write to temporary file: %m");
 408                         goto finish;
 409                 }
 410         }
 411
 412         if (!mkdtemp(gpg_home)) {
 413                 r = log_error_errno(errno, "Failed to create temporary home for gpg: %m");
 414                 goto finish;
 415         }
 416
 417         gpg_home_created = true;
 418
 419         r = safe_fork("(gpg)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pid);
 420         if (r < 0)
 421                 return r;
 422         if (r == 0) {
 423                 const char *cmd[] = {
 424                         "gpg",
 425                         "--no-options",
 426                         "--no-default-keyring",
 427                         "--no-auto-key-locate",
 428                         "--no-auto-check-trustdb",
 429                         "--batch",
 430                         "--trust-model=always",
 431                         NULL, /* --homedir=  */
 432                         NULL, /* --keyring= */
 433                         NULL, /* --verify */
 434                         NULL, /* signature file */
 435                         NULL, /* dash */
 436                         NULL  /* trailing NULL */
 437                 };
 438                 size_t k = ELEMENTSOF(cmd) - 6;
 439
 440                 /* Child */
 441
 442                 gpg_pipe[1] = safe_close(gpg_pipe[1]);
 443
 444                 r = rearrange_stdio(TAKE_FD(gpg_pipe[0]), -1, STDERR_FILENO);
 445                 if (r < 0) {
 446                         log_error_errno(r, "Failed to rearrange stdin/stdout: %m");
 447                         _exit(EXIT_FAILURE);
 448                 }
 449
 450                 (void) rlimit_nofile_safe();
 451
 452                 cmd[k++] = strjoina("--homedir=", gpg_home);
 453
 454                 /* We add the user keyring only to the command line arguments, if it's around since gpg fails
 455                  * otherwise. */
 456                 if (access(USER_KEYRING_PATH, F_OK) >= 0)
 457                         cmd[k++] = "--keyring=" USER_KEYRING_PATH;
 458                 else
 459                         cmd[k++] = "--keyring=" VENDOR_KEYRING_PATH;
 460
 461                 cmd[k++] = "--verify";
 462                 if (signature) {
 463                         cmd[k++] = sig_file_path;
 464                         cmd[k++] = "-";
 465                         cmd[k++] = NULL;
 466                 }
 467
 468                 execvp("gpg2", (char * const *) cmd);
 469                 execvp("gpg", (char * const *) cmd);
 470                 log_error_errno(errno, "Failed to execute gpg: %m");
 471                 _exit(EXIT_FAILURE);
 472         }
 473
 474         gpg_pipe[0] = safe_close(gpg_pipe[0]);
 475
 476         r = loop_write(gpg_pipe[1], payload, payload_size, false);
 477         if (r < 0) {
 478                 log_error_errno(r, "Failed to write to pipe: %m");
 479                 goto finish;
 480         }
 481
 482         gpg_pipe[1] = safe_close(gpg_pipe[1]);
 483
 484         r = wait_for_terminate_and_check("gpg", TAKE_PID(pid), WAIT_LOG_ABNORMAL);
 485         if (r < 0)
 486                 goto finish;
 487         if (r != EXIT_SUCCESS)
 488                 r = log_error_errno(SYNTHETIC_ERRNO(EBADMSG),
 489                                     "DOWNLOAD INVALID: Signature verification failed.");
 490         else {
 491                 log_info("Signature verification succeeded.");
 492                 r = 0;
 493         }
 494
 495 finish:
 496         if (signature_size > 0)
 497                 (void) unlink(sig_file_path);
 498
 499         if (gpg_home_created)
 500                 (void) rm_rf(gpg_home, REMOVE_ROOT|REMOVE_PHYSICAL);
 501
 502         return r;
 503 }
 504
 505 int pull_verify(ImportVerify verify,
 506                 const char *checksum, /* Verify with literal checksum */
 507                 PullJob *main_job,
 508                 PullJob *checksum_job,
 509                 PullJob *signature_job,
 510                 PullJob *settings_job,
 511                 PullJob *roothash_job,
 512                 PullJob *roothash_signature_job,
 513                 PullJob *verity_job) {
 514
 515         _cleanup_free_ char *fn = NULL;
 516         VerificationStyle style;
 517         PullJob *verify_job;
 518         int r;
 519
 520         assert(verify == _IMPORT_VERIFY_INVALID || verify < _IMPORT_VERIFY_MAX);
 521         assert(verify == _IMPORT_VERIFY_INVALID || verify >= 0);
 522         assert((verify < 0) || !checksum);
 523         assert(main_job);
 524         assert(main_job->state == PULL_JOB_DONE);
 525
 526         if (verify == IMPORT_VERIFY_NO) /* verification turned off */
 527                 return 0;
 528
 529         if (checksum) {
 530                 /* Verification by literal checksum */
 531                 assert(!checksum_job);
 532                 assert(!signature_job);
 533                 assert(!settings_job);
 534                 assert(!roothash_job);
 535                 assert(!roothash_signature_job);
 536                 assert(!verity_job);
 537
 538                 assert(main_job->calc_checksum);
 539                 assert(main_job->checksum);
 540
 541                 if (!strcaseeq(checksum, main_job->checksum))
 542                         return log_error_errno(SYNTHETIC_ERRNO(EBADMSG),
 543                                                "DOWNLOAD INVALID: Checksum of %s file did not check out, file has been tampered with.",
 544                                                main_job->url);
 545
 546                 return 0;
 547         }
 548
 549         r = import_url_last_component(main_job->url, &fn);
 550         if (r < 0)
 551                 return log_error_errno(r, "Failed to extract filename from URL '%s': %m", main_job->url);
 552
 553         if (is_signature_file(fn))
 554                 return log_error_errno(SYNTHETIC_ERRNO(ELOOP),
 555                                        "Main download is a signature file, can't verify it.");
 556
 557         if (is_checksum_file(fn)) {
 558                 log_debug("Main download is a checksum file, can't validate its checksum with itself, skipping.");
 559                 verify_job = main_job;
 560         } else {
 561                 PullJob *j;
 562                 assert(main_job->calc_checksum);
 563                 assert(main_job->checksum);
 564                 assert(checksum_job);
 565                 assert(checksum_job->state == PULL_JOB_DONE);
 566
 567                 if (!checksum_job->payload || checksum_job->payload_size <= 0)
 568                         return log_error_errno(SYNTHETIC_ERRNO(EBADMSG),
 569                                                "Checksum is empty, cannot verify.");
 570
 571                 FOREACH_POINTER(j, main_job, settings_job, roothash_job, roothash_signature_job, verity_job) {
 572                         r = verify_one(checksum_job, j);
 573                         if (r < 0)
 574                                 return r;
 575                 }
 576
 577                 verify_job = checksum_job;
 578         }
 579
 580         if (verify != IMPORT_VERIFY_SIGNATURE)
 581                 return 0;
 582
 583         assert(verify_job);
 584
 585         r = verification_style_from_url(verify_job->url, &style);
 586         if (r < 0)
 587                 return log_error_errno(r, "Failed to determine verification style from URL '%s': %m", verify_job->url);
 588
 589         if (style == VERIFICATION_PER_DIRECTORY) {
 590                 assert(signature_job);
 591                 assert(signature_job->state == PULL_JOB_DONE);
 592
 593                 if (!signature_job->payload || signature_job->payload_size <= 0)
 594                         return log_error_errno(SYNTHETIC_ERRNO(EBADMSG),
 595                                                "Signature is empty, cannot verify.");
 596
 597                 return verify_gpg(verify_job->payload, verify_job->payload_size, signature_job->payload, signature_job->payload_size);
 598         } else
 599                 return verify_gpg(verify_job->payload, verify_job->payload_size, NULL, 0);
 600 }
 601
 602 int verification_style_from_url(const char *url, VerificationStyle *ret) {
 603         _cleanup_free_ char *last = NULL;
 604         int r;
 605
 606         assert(url);
 607         assert(ret);
 608
 609         /* Determines which kind of verification style is appropriate for this url */
 610
 611         r = import_url_last_component(url, &last);
 612         if (r < 0)
 613                 return r;
 614
 615         if (streq(last, "SHA256SUMS")) {
 616                 *ret = VERIFICATION_PER_DIRECTORY;
 617                 return 0;
 618         }
 619
 620         if (endswith(last, ".sha256")) {
 621                 *ret = VERIFICATION_PER_FILE;
 622                 return 0;
 623         }
 624
 625         return -EINVAL;
 626 }
 627
 628 int pull_job_restart_with_sha256sum(PullJob *j, char **ret) {
 629         VerificationStyle style;
 630         int r;
 631
 632         assert(j);
 633
 634         /* Generic implementation of a PullJobNotFound handler, that restarts the job requesting SHA256SUMS */
 635
 636         r = verification_style_from_url(j->url, &style);
 637         if (r < 0)
 638                 return log_error_errno(r, "Failed to determine verification style of URL '%s': %m", j->url);
 639
 640         if (style == VERIFICATION_PER_DIRECTORY) /* Nothing to do anymore */
 641                 return 0;
 642
 643         assert(style == VERIFICATION_PER_FILE); /* This must have been .sha256 style URL before */
 644
 645         log_debug("Got 404 for %s, now trying to get SHA256SUMS instead.", j->url);
 646
 647         r = import_url_change_last_component(j->url, "SHA256SUMS", ret);
 648         if (r < 0)
 649                 return log_error_errno(r, "Failed to replace SHA256SUMS suffix: %m");
 650
 651         return 1;
 652 }
 653
 654 bool pull_validate_local(const char *name, PullFlags flags) {
 655
 656         if (FLAGS_SET(flags, PULL_DIRECT))
 657                 return path_is_valid(name);
 658
 659         return hostname_is_valid(name, 0);
 660 }
 661
 662 int pull_url_needs_checksum(const char *url) {
 663         _cleanup_free_ char *fn = NULL;
 664         int r;
 665
 666         /* Returns true if we need to validate this resource via a hash value. This returns true for all
 667          * files — except for gpg signature files and SHA256SUMS files and the like, which are validated with
 668          * a validation tool like gpg. */
 669
 670         r = import_url_last_component(url, &fn);
 671         if (r == -EADDRNOTAVAIL) /* no last component? then let's assume it's not a signature/checksum file */
 672                 return false;
 673         if (r < 0)
 674                 return r;
 675
 676         return !is_checksum_file(fn) && !is_signature_file(fn);
 677 }