src/import/pull-common.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2015 Lennart Poettering
   6 ***/
   7
   8 #include <sys/prctl.h>
   9
  10 #include "alloc-util.h"
  11 #include "btrfs-util.h"
  12 #include "capability-util.h"
  13 #include "copy.h"
  14 #include "dirent-util.h"
  15 #include "escape.h"
  16 #include "fd-util.h"
  17 #include "io-util.h"
  18 #include "path-util.h"
  19 #include "process-util.h"
  20 #include "pull-common.h"
  21 #include "pull-job.h"
  22 #include "rm-rf.h"
  23 #include "signal-util.h"
  24 #include "siphash24.h"
  25 #include "string-util.h"
  26 #include "strv.h"
  27 #include "util.h"
  28 #include "web-util.h"
  29
  30 #define FILENAME_ESCAPE "/.#\"\'"
  31 #define HASH_URL_THRESHOLD_LENGTH (_POSIX_PATH_MAX - 16)
  32
  33 int pull_find_old_etags(
  34                 const char *url,
  35                 const char *image_root,
  36                 int dt,
  37                 const char *prefix,
  38                 const char *suffix,
  39                 char ***etags) {
  40
  41         _cleanup_free_ char *escaped_url = NULL;
  42         _cleanup_closedir_ DIR *d = NULL;
  43         _cleanup_strv_free_ char **l = NULL;
  44         struct dirent *de;
  45         int r;
  46
  47         assert(url);
  48         assert(etags);
  49
  50         if (!image_root)
  51                 image_root = "/var/lib/machines";
  52
  53         escaped_url = xescape(url, FILENAME_ESCAPE);
  54         if (!escaped_url)
  55                 return -ENOMEM;
  56
  57         d = opendir(image_root);
  58         if (!d) {
  59                 if (errno == ENOENT) {
  60                         *etags = NULL;
  61                         return 0;
  62                 }
  63
  64                 return -errno;
  65         }
  66
  67         FOREACH_DIRENT_ALL(de, d, return -errno) {
  68                 const char *a, *b;
  69                 char *u;
  70
  71                 if (de->d_type != DT_UNKNOWN &&
  72                     de->d_type != dt)
  73                         continue;
  74
  75                 if (prefix) {
  76                         a = startswith(de->d_name, prefix);
  77                         if (!a)
  78                                 continue;
  79                 } else
  80                         a = de->d_name;
  81
  82                 a = startswith(a, escaped_url);
  83                 if (!a)
  84                         continue;
  85
  86                 a = startswith(a, ".");
  87                 if (!a)
  88                         continue;
  89
  90                 if (suffix) {
  91                         b = endswith(de->d_name, suffix);
  92                         if (!b)
  93                                 continue;
  94                 } else
  95                         b = strchr(de->d_name, 0);
  96
  97                 if (a >= b)
  98                         continue;
  99
 100                 r = cunescape_length(a, b - a, 0, &u);
 101                 if (r < 0)
 102                         return r;
 103
 104                 if (!http_etag_is_valid(u)) {
 105                         free(u);
 106                         continue;
 107                 }
 108
 109                 r = strv_consume(&l, u);
 110                 if (r < 0)
 111                         return r;
 112         }
 113
 114         *etags = TAKE_PTR(l);
 115
 116         return 0;
 117 }
 118
 119 int pull_make_local_copy(const char *final, const char *image_root, const char *local, bool force_local) {
 120         const char *p;
 121         int r;
 122
 123         assert(final);
 124         assert(local);
 125
 126         if (!image_root)
 127                 image_root = "/var/lib/machines";
 128
 129         p = strjoina(image_root, "/", local);
 130
 131         if (force_local)
 132                 (void) rm_rf(p, REMOVE_ROOT|REMOVE_PHYSICAL|REMOVE_SUBVOLUME);
 133
 134         r = btrfs_subvol_snapshot(final, p,
 135                                   BTRFS_SNAPSHOT_QUOTA|
 136                                   BTRFS_SNAPSHOT_FALLBACK_COPY|
 137                                   BTRFS_SNAPSHOT_FALLBACK_DIRECTORY|
 138                                   BTRFS_SNAPSHOT_RECURSIVE);
 139         if (r < 0)
 140                 return log_error_errno(r, "Failed to create local image: %m");
 141
 142         log_info("Created new local image '%s'.", local);
 143
 144         return 0;
 145 }
 146
 147 static int hash_url(const char *url, char **ret) {
 148         uint64_t h;
 149         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);
 150
 151         assert(url);
 152
 153         h = siphash24(url, strlen(url), k.bytes);
 154         if (asprintf(ret, "%"PRIx64, h) < 0)
 155                 return -ENOMEM;
 156
 157         return 0;
 158 }
 159
 160 int pull_make_path(const char *url, const char *etag, const char *image_root, const char *prefix, const char *suffix, char **ret) {
 161         _cleanup_free_ char *escaped_url = NULL, *escaped_etag = NULL;
 162         char *path;
 163
 164         assert(url);
 165         assert(ret);
 166
 167         if (!image_root)
 168                 image_root = "/var/lib/machines";
 169
 170         escaped_url = xescape(url, FILENAME_ESCAPE);
 171         if (!escaped_url)
 172                 return -ENOMEM;
 173
 174         if (etag) {
 175                 escaped_etag = xescape(etag, FILENAME_ESCAPE);
 176                 if (!escaped_etag)
 177                         return -ENOMEM;
 178         }
 179
 180         path = strjoin(image_root, "/", strempty(prefix), escaped_url, escaped_etag ? "." : "",
 181                        strempty(escaped_etag), strempty(suffix));
 182         if (!path)
 183                 return -ENOMEM;
 184
 185         /* URLs might make the path longer than the maximum allowed length for a file name.
 186          * When that happens, a URL hash is used instead. Paths returned by this function
 187          * can be later used with tempfn_random() which adds 16 bytes to the resulting name. */
 188         if (strlen(path) >= HASH_URL_THRESHOLD_LENGTH) {
 189                 _cleanup_free_ char *hash = NULL;
 190                 int r;
 191
 192                 free(path);
 193
 194                 r = hash_url(url, &hash);
 195                 if (r < 0)
 196                         return r;
 197
 198                 path = strjoin(image_root, "/", strempty(prefix), hash, escaped_etag ? "." : "",
 199                                strempty(escaped_etag), strempty(suffix));
 200                 if (!path)
 201                         return -ENOMEM;
 202         }
 203
 204         *ret = path;
 205         return 0;
 206 }
 207
 208 int pull_make_auxiliary_job(
 209                 PullJob **ret,
 210                 const char *url,
 211                 int (*strip_suffixes)(const char *name, char **ret),
 212                 const char *suffix,
 213                 CurlGlue *glue,
 214                 PullJobFinished on_finished,
 215                 void *userdata) {
 216
 217         _cleanup_free_ char *last_component = NULL, *ll = NULL, *auxiliary_url = NULL;
 218         _cleanup_(pull_job_unrefp) PullJob *job = NULL;
 219         const char *q;
 220         int r;
 221
 222         assert(ret);
 223         assert(url);
 224         assert(strip_suffixes);
 225         assert(glue);
 226
 227         r = import_url_last_component(url, &last_component);
 228         if (r < 0)
 229                 return r;
 230
 231         r = strip_suffixes(last_component, &ll);
 232         if (r < 0)
 233                 return r;
 234
 235         q = strjoina(ll, suffix);
 236
 237         r = import_url_change_last_component(url, q, &auxiliary_url);
 238         if (r < 0)
 239                 return r;
 240
 241         r = pull_job_new(&job, auxiliary_url, glue, userdata);
 242         if (r < 0)
 243                 return r;
 244
 245         job->on_finished = on_finished;
 246         job->compressed_max = job->uncompressed_max = 1ULL * 1024ULL * 1024ULL;
 247
 248         *ret = TAKE_PTR(job);
 249
 250         return 0;
 251 }
 252
 253 int pull_make_verification_jobs(
 254                 PullJob **ret_checksum_job,
 255                 PullJob **ret_signature_job,
 256                 ImportVerify verify,
 257                 const char *url,
 258                 CurlGlue *glue,
 259                 PullJobFinished on_finished,
 260                 void *userdata) {
 261
 262         _cleanup_(pull_job_unrefp) PullJob *checksum_job = NULL, *signature_job = NULL;
 263         int r;
 264         const char *chksums = NULL;
 265
 266         assert(ret_checksum_job);
 267         assert(ret_signature_job);
 268         assert(verify >= 0);
 269         assert(verify < _IMPORT_VERIFY_MAX);
 270         assert(url);
 271         assert(glue);
 272
 273         if (verify != IMPORT_VERIFY_NO) {
 274                 _cleanup_free_ char *checksum_url = NULL, *fn = NULL;
 275
 276                 /* Queue jobs for the checksum file for the image. */
 277                 r = import_url_last_component(url, &fn);
 278                 if (r < 0)
 279                         return r;
 280
 281                 chksums = strjoina(fn, ".sha256");
 282
 283                 r = import_url_change_last_component(url, chksums, &checksum_url);
 284                 if (r < 0)
 285                         return r;
 286
 287                 r = pull_job_new(&checksum_job, checksum_url, glue, userdata);
 288                 if (r < 0)
 289                         return r;
 290
 291                 checksum_job->on_finished = on_finished;
 292                 checksum_job->uncompressed_max = checksum_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 293         }
 294
 295         if (verify == IMPORT_VERIFY_SIGNATURE) {
 296                 _cleanup_free_ char *signature_url = NULL;
 297
 298                 /* Queue job for the SHA256SUMS.gpg file for the image. */
 299                 r = import_url_change_last_component(url, "SHA256SUMS.gpg", &signature_url);
 300                 if (r < 0)
 301                         return r;
 302
 303                 r = pull_job_new(&signature_job, signature_url, glue, userdata);
 304                 if (r < 0)
 305                         return r;
 306
 307                 signature_job->on_finished = on_finished;
 308                 signature_job->uncompressed_max = signature_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 309         }
 310
 311         *ret_checksum_job = checksum_job;
 312         *ret_signature_job = signature_job;
 313
 314         checksum_job = signature_job = NULL;
 315
 316         return 0;
 317 }
 318
 319 static int verify_one(PullJob *checksum_job, PullJob *job) {
 320         _cleanup_free_ char *fn = NULL;
 321         const char *line, *p;
 322         int r;
 323
 324         assert(checksum_job);
 325
 326         if (!job)
 327                 return 0;
 328
 329         assert(IN_SET(job->state, PULL_JOB_DONE, PULL_JOB_FAILED));
 330
 331         /* Don't verify the checksum if we didn't actually successfully download something new */
 332         if (job->state != PULL_JOB_DONE)
 333                 return 0;
 334         if (job->error != 0)
 335                 return 0;
 336         if (job->etag_exists)
 337                 return 0;
 338
 339         assert(job->calc_checksum);
 340         assert(job->checksum);
 341
 342         r = import_url_last_component(job->url, &fn);
 343         if (r < 0)
 344                 return log_oom();
 345
 346         if (!filename_is_valid(fn)) {
 347                 log_error("Cannot verify checksum, could not determine server-side file name.");
 348                 return -EBADMSG;
 349         }
 350
 351         line = strjoina(job->checksum, " *", fn, "\n");
 352
 353         p = memmem(checksum_job->payload,
 354                    checksum_job->payload_size,
 355                    line,
 356                    strlen(line));
 357
 358         if (!p) {
 359                 line = strjoina(job->checksum, "  ", fn, "\n");
 360
 361                 p = memmem(checksum_job->payload,
 362                         checksum_job->payload_size,
 363                         line,
 364                         strlen(line));
 365         }
 366
 367         if (!p || (p != (char*) checksum_job->payload && p[-1] != '\n')) {
 368                 log_error("DOWNLOAD INVALID: Checksum of %s file did not checkout, file has been tampered with.", fn);
 369                 return -EBADMSG;
 370         }
 371
 372         log_info("SHA256 checksum of %s is valid.", job->url);
 373         return 1;
 374 }
 375
 376 int pull_verify(PullJob *main_job,
 377                 PullJob *roothash_job,
 378                 PullJob *settings_job,
 379                 PullJob *checksum_job,
 380                 PullJob *signature_job) {
 381
 382         _cleanup_close_pair_ int gpg_pipe[2] = { -1, -1 };
 383         _cleanup_close_ int sig_file = -1;
 384         char sig_file_path[] = "/tmp/sigXXXXXX", gpg_home[] = "/tmp/gpghomeXXXXXX";
 385         _cleanup_(sigkill_waitp) pid_t pid = 0;
 386         bool gpg_home_created = false;
 387         int r;
 388
 389         assert(main_job);
 390         assert(main_job->state == PULL_JOB_DONE);
 391
 392         if (!checksum_job)
 393                 return 0;
 394
 395         assert(main_job->calc_checksum);
 396         assert(main_job->checksum);
 397
 398         assert(checksum_job->state == PULL_JOB_DONE);
 399
 400         if (!checksum_job->payload || checksum_job->payload_size <= 0) {
 401                 log_error("Checksum is empty, cannot verify.");
 402                 return -EBADMSG;
 403         }
 404
 405         r = verify_one(checksum_job, main_job);
 406         if (r < 0)
 407                 return r;
 408
 409         r = verify_one(checksum_job, roothash_job);
 410         if (r < 0)
 411                 return r;
 412
 413         r = verify_one(checksum_job, settings_job);
 414         if (r < 0)
 415                 return r;
 416
 417         if (!signature_job)
 418                 return 0;
 419
 420         if (checksum_job->style == VERIFICATION_PER_FILE)
 421                 signature_job = checksum_job;
 422
 423         assert(signature_job->state == PULL_JOB_DONE);
 424
 425         if (!signature_job->payload || signature_job->payload_size <= 0) {
 426                 log_error("Signature is empty, cannot verify.");
 427                 return -EBADMSG;
 428         }
 429
 430         r = pipe2(gpg_pipe, O_CLOEXEC);
 431         if (r < 0)
 432                 return log_error_errno(errno, "Failed to create pipe for gpg: %m");
 433
 434         sig_file = mkostemp(sig_file_path, O_RDWR);
 435         if (sig_file < 0)
 436                 return log_error_errno(errno, "Failed to create temporary file: %m");
 437
 438         r = loop_write(sig_file, signature_job->payload, signature_job->payload_size, false);
 439         if (r < 0) {
 440                 log_error_errno(r, "Failed to write to temporary file: %m");
 441                 goto finish;
 442         }
 443
 444         if (!mkdtemp(gpg_home)) {
 445                 r = log_error_errno(errno, "Failed to create tempory home for gpg: %m");
 446                 goto finish;
 447         }
 448
 449         gpg_home_created = true;
 450
 451         r = safe_fork("(gpg)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pid);
 452         if (r < 0)
 453                 return r;
 454         if (r == 0) {
 455                 const char *cmd[] = {
 456                         "gpg",
 457                         "--no-options",
 458                         "--no-default-keyring",
 459                         "--no-auto-key-locate",
 460                         "--no-auto-check-trustdb",
 461                         "--batch",
 462                         "--trust-model=always",
 463                         NULL, /* --homedir=  */
 464                         NULL, /* --keyring= */
 465                         NULL, /* --verify */
 466                         NULL, /* signature file */
 467                         NULL, /* dash */
 468                         NULL  /* trailing NULL */
 469                 };
 470                 unsigned k = ELEMENTSOF(cmd) - 6;
 471
 472                 /* Child */
 473
 474                 gpg_pipe[1] = safe_close(gpg_pipe[1]);
 475
 476                 r = rearrange_stdio(gpg_pipe[0], -1, STDERR_FILENO);
 477                 if (r < 0) {
 478                         log_error_errno(r, "Failed to rearrange stdin/stdout: %m");
 479                         _exit(EXIT_FAILURE);
 480                 }
 481
 482                 cmd[k++] = strjoina("--homedir=", gpg_home);
 483
 484                 /* We add the user keyring only to the command line
 485                  * arguments, if it's around since gpg fails
 486                  * otherwise. */
 487                 if (access(USER_KEYRING_PATH, F_OK) >= 0)
 488                         cmd[k++] = "--keyring=" USER_KEYRING_PATH;
 489                 else
 490                         cmd[k++] = "--keyring=" VENDOR_KEYRING_PATH;
 491
 492                 cmd[k++] = "--verify";
 493                 if (checksum_job->style == VERIFICATION_PER_DIRECTORY) {
 494                         cmd[k++] = sig_file_path;
 495                         cmd[k++] = "-";
 496                         cmd[k++] = NULL;
 497                 }
 498
 499                 execvp("gpg2", (char * const *) cmd);
 500                 execvp("gpg", (char * const *) cmd);
 501                 log_error_errno(errno, "Failed to execute gpg: %m");
 502                 _exit(EXIT_FAILURE);
 503         }
 504
 505         gpg_pipe[0] = safe_close(gpg_pipe[0]);
 506
 507         r = loop_write(gpg_pipe[1], checksum_job->payload, checksum_job->payload_size, false);
 508         if (r < 0) {
 509                 log_error_errno(r, "Failed to write to pipe: %m");
 510                 goto finish;
 511         }
 512
 513         gpg_pipe[1] = safe_close(gpg_pipe[1]);
 514
 515         r = wait_for_terminate_and_check("gpg", pid, WAIT_LOG_ABNORMAL);
 516         pid = 0;
 517         if (r < 0)
 518                 goto finish;
 519         if (r != EXIT_SUCCESS) {
 520                 log_error("DOWNLOAD INVALID: Signature verification failed.");
 521                 r = -EBADMSG;
 522         } else {
 523                 log_info("Signature verification succeeded.");
 524                 r = 0;
 525         }
 526
 527 finish:
 528         if (sig_file >= 0)
 529                 (void) unlink(sig_file_path);
 530
 531         if (gpg_home_created)
 532                 (void) rm_rf(gpg_home, REMOVE_ROOT|REMOVE_PHYSICAL);
 533
 534         return r;
 535 }