src/import/pull-common.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2015 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <sys/prctl.h>
  21
  22 #include "alloc-util.h"
  23 #include "btrfs-util.h"
  24 #include "capability-util.h"
  25 #include "copy.h"
  26 #include "dirent-util.h"
  27 #include "escape.h"
  28 #include "fd-util.h"
  29 #include "io-util.h"
  30 #include "path-util.h"
  31 #include "process-util.h"
  32 #include "pull-common.h"
  33 #include "pull-job.h"
  34 #include "rm-rf.h"
  35 #include "signal-util.h"
  36 #include "siphash24.h"
  37 #include "string-util.h"
  38 #include "strv.h"
  39 #include "util.h"
  40 #include "web-util.h"
  41
  42 #define FILENAME_ESCAPE "/.#\"\'"
  43 #define HASH_URL_THRESHOLD_LENGTH (_POSIX_PATH_MAX - 16)
  44
  45 int pull_find_old_etags(
  46                 const char *url,
  47                 const char *image_root,
  48                 int dt,
  49                 const char *prefix,
  50                 const char *suffix,
  51                 char ***etags) {
  52
  53         _cleanup_free_ char *escaped_url = NULL;
  54         _cleanup_closedir_ DIR *d = NULL;
  55         _cleanup_strv_free_ char **l = NULL;
  56         struct dirent *de;
  57         int r;
  58
  59         assert(url);
  60         assert(etags);
  61
  62         if (!image_root)
  63                 image_root = "/var/lib/machines";
  64
  65         escaped_url = xescape(url, FILENAME_ESCAPE);
  66         if (!escaped_url)
  67                 return -ENOMEM;
  68
  69         d = opendir(image_root);
  70         if (!d) {
  71                 if (errno == ENOENT) {
  72                         *etags = NULL;
  73                         return 0;
  74                 }
  75
  76                 return -errno;
  77         }
  78
  79         FOREACH_DIRENT_ALL(de, d, return -errno) {
  80                 const char *a, *b;
  81                 char *u;
  82
  83                 if (de->d_type != DT_UNKNOWN &&
  84                     de->d_type != dt)
  85                         continue;
  86
  87                 if (prefix) {
  88                         a = startswith(de->d_name, prefix);
  89                         if (!a)
  90                                 continue;
  91                 } else
  92                         a = de->d_name;
  93
  94                 a = startswith(a, escaped_url);
  95                 if (!a)
  96                         continue;
  97
  98                 a = startswith(a, ".");
  99                 if (!a)
 100                         continue;
 101
 102                 if (suffix) {
 103                         b = endswith(de->d_name, suffix);
 104                         if (!b)
 105                                 continue;
 106                 } else
 107                         b = strchr(de->d_name, 0);
 108
 109                 if (a >= b)
 110                         continue;
 111
 112                 r = cunescape_length(a, b - a, 0, &u);
 113                 if (r < 0)
 114                         return r;
 115
 116                 if (!http_etag_is_valid(u)) {
 117                         free(u);
 118                         continue;
 119                 }
 120
 121                 r = strv_consume(&l, u);
 122                 if (r < 0)
 123                         return r;
 124         }
 125
 126         *etags = l;
 127         l = NULL;
 128
 129         return 0;
 130 }
 131
 132 int pull_make_local_copy(const char *final, const char *image_root, const char *local, bool force_local) {
 133         const char *p;
 134         int r;
 135
 136         assert(final);
 137         assert(local);
 138
 139         if (!image_root)
 140                 image_root = "/var/lib/machines";
 141
 142         p = strjoina(image_root, "/", local);
 143
 144         if (force_local)
 145                 (void) rm_rf(p, REMOVE_ROOT|REMOVE_PHYSICAL|REMOVE_SUBVOLUME);
 146
 147         r = btrfs_subvol_snapshot(final, p,
 148                                   BTRFS_SNAPSHOT_QUOTA|
 149                                   BTRFS_SNAPSHOT_FALLBACK_COPY|
 150                                   BTRFS_SNAPSHOT_FALLBACK_DIRECTORY|
 151                                   BTRFS_SNAPSHOT_RECURSIVE);
 152         if (r < 0)
 153                 return log_error_errno(r, "Failed to create local image: %m");
 154
 155         log_info("Created new local image '%s'.", local);
 156
 157         return 0;
 158 }
 159
 160 static int hash_url(const char *url, char **ret) {
 161         uint64_t h;
 162         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);
 163
 164         assert(url);
 165
 166         h = siphash24(url, strlen(url), k.bytes);
 167         if (asprintf(ret, "%"PRIx64, h) < 0)
 168                 return -ENOMEM;
 169
 170         return 0;
 171 }
 172
 173 int pull_make_path(const char *url, const char *etag, const char *image_root, const char *prefix, const char *suffix, char **ret) {
 174         _cleanup_free_ char *escaped_url = NULL, *escaped_etag = NULL;
 175         char *path;
 176
 177         assert(url);
 178         assert(ret);
 179
 180         if (!image_root)
 181                 image_root = "/var/lib/machines";
 182
 183         escaped_url = xescape(url, FILENAME_ESCAPE);
 184         if (!escaped_url)
 185                 return -ENOMEM;
 186
 187         if (etag) {
 188                 escaped_etag = xescape(etag, FILENAME_ESCAPE);
 189                 if (!escaped_etag)
 190                         return -ENOMEM;
 191         }
 192
 193         path = strjoin(image_root, "/", strempty(prefix), escaped_url, escaped_etag ? "." : "",
 194                        strempty(escaped_etag), strempty(suffix), NULL);
 195         if (!path)
 196                 return -ENOMEM;
 197
 198         /* URLs might make the path longer than the maximum allowed length for a file name.
 199          * When that happens, a URL hash is used instead. Paths returned by this function
 200          * can be later used with tempfn_random() which adds 16 bytes to the resulting name. */
 201         if (strlen(path) >= HASH_URL_THRESHOLD_LENGTH) {
 202                 _cleanup_free_ char *hash = NULL;
 203                 int r;
 204
 205                 free(path);
 206
 207                 r = hash_url(url, &hash);
 208                 if (r < 0)
 209                         return r;
 210
 211                 path = strjoin(image_root, "/", strempty(prefix), hash, escaped_etag ? "." : "",
 212                                strempty(escaped_etag), strempty(suffix), NULL);
 213                 if (!path)
 214                         return -ENOMEM;
 215         }
 216
 217         *ret = path;
 218         return 0;
 219 }
 220
 221 int pull_make_auxiliary_job(
 222                 PullJob **ret,
 223                 const char *url,
 224                 int (*strip_suffixes)(const char *name, char **ret),
 225                 const char *suffix,
 226                 CurlGlue *glue,
 227                 PullJobFinished on_finished,
 228                 void *userdata) {
 229
 230         _cleanup_free_ char *last_component = NULL, *ll = NULL, *auxiliary_url = NULL;
 231         _cleanup_(pull_job_unrefp) PullJob *job = NULL;
 232         const char *q;
 233         int r;
 234
 235         assert(ret);
 236         assert(url);
 237         assert(strip_suffixes);
 238         assert(glue);
 239
 240         r = import_url_last_component(url, &last_component);
 241         if (r < 0)
 242                 return r;
 243
 244         r = strip_suffixes(last_component, &ll);
 245         if (r < 0)
 246                 return r;
 247
 248         q = strjoina(ll, suffix);
 249
 250         r = import_url_change_last_component(url, q, &auxiliary_url);
 251         if (r < 0)
 252                 return r;
 253
 254         r = pull_job_new(&job, auxiliary_url, glue, userdata);
 255         if (r < 0)
 256                 return r;
 257
 258         job->on_finished = on_finished;
 259         job->compressed_max = job->uncompressed_max = 1ULL * 1024ULL * 1024ULL;
 260
 261         *ret = job;
 262         job = NULL;
 263
 264         return 0;
 265 }
 266
 267 int pull_make_verification_jobs(
 268                 PullJob **ret_checksum_job,
 269                 PullJob **ret_signature_job,
 270                 ImportVerify verify,
 271                 const char *url,
 272                 CurlGlue *glue,
 273                 PullJobFinished on_finished,
 274                 void *userdata) {
 275
 276         _cleanup_(pull_job_unrefp) PullJob *checksum_job = NULL, *signature_job = NULL;
 277         int r;
 278         const char *chksums = NULL;
 279
 280         assert(ret_checksum_job);
 281         assert(ret_signature_job);
 282         assert(verify >= 0);
 283         assert(verify < _IMPORT_VERIFY_MAX);
 284         assert(url);
 285         assert(glue);
 286
 287         if (verify != IMPORT_VERIFY_NO) {
 288                 _cleanup_free_ char *checksum_url = NULL, *fn = NULL;
 289
 290                 /* Queue jobs for the checksum file for the image. */
 291                 r = import_url_last_component(url, &fn);
 292                 if (r < 0)
 293                         return r;
 294
 295                 chksums = strjoina(fn, ".sha256");
 296
 297                 r = import_url_change_last_component(url, chksums, &checksum_url);
 298                 if (r < 0)
 299                         return r;
 300
 301                 r = pull_job_new(&checksum_job, checksum_url, glue, userdata);
 302                 if (r < 0)
 303                         return r;
 304
 305                 checksum_job->on_finished = on_finished;
 306                 checksum_job->uncompressed_max = checksum_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 307         }
 308
 309         if (verify == IMPORT_VERIFY_SIGNATURE) {
 310                 _cleanup_free_ char *signature_url = NULL;
 311
 312                 /* Queue job for the SHA256SUMS.gpg file for the image. */
 313                 r = import_url_change_last_component(url, "SHA256SUMS.gpg", &signature_url);
 314                 if (r < 0)
 315                         return r;
 316
 317                 r = pull_job_new(&signature_job, signature_url, glue, userdata);
 318                 if (r < 0)
 319                         return r;
 320
 321                 signature_job->on_finished = on_finished;
 322                 signature_job->uncompressed_max = signature_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 323         }
 324
 325         *ret_checksum_job = checksum_job;
 326         *ret_signature_job = signature_job;
 327
 328         checksum_job = signature_job = NULL;
 329
 330         return 0;
 331 }
 332
 333 static int verify_one(PullJob *checksum_job, PullJob *job) {
 334         _cleanup_free_ char *fn = NULL;
 335         const char *line, *p;
 336         int r;
 337
 338         assert(checksum_job);
 339
 340         if (!job)
 341                 return 0;
 342
 343         assert(IN_SET(job->state, PULL_JOB_DONE, PULL_JOB_FAILED));
 344
 345         /* Don't verify the checksum if we didn't actually successfully download something new */
 346         if (job->state != PULL_JOB_DONE)
 347                 return 0;
 348         if (job->error != 0)
 349                 return 0;
 350         if (job->etag_exists)
 351                 return 0;
 352
 353         assert(job->calc_checksum);
 354         assert(job->checksum);
 355
 356         r = import_url_last_component(job->url, &fn);
 357         if (r < 0)
 358                 return log_oom();
 359
 360         if (!filename_is_valid(fn)) {
 361                 log_error("Cannot verify checksum, could not determine server-side file name.");
 362                 return -EBADMSG;
 363         }
 364
 365         line = strjoina(job->checksum, " *", fn, "\n");
 366
 367         p = memmem(checksum_job->payload,
 368                    checksum_job->payload_size,
 369                    line,
 370                    strlen(line));
 371
 372         if (!p) {
 373                 line = strjoina(job->checksum, "  ", fn, "\n");
 374
 375                 p = memmem(checksum_job->payload,
 376                         checksum_job->payload_size,
 377                         line,
 378                         strlen(line));
 379         }
 380
 381         if (!p || (p != (char*) checksum_job->payload && p[-1] != '\n')) {
 382                 log_error("DOWNLOAD INVALID: Checksum of %s file did not checkout, file has been tampered with.", fn);
 383                 return -EBADMSG;
 384         }
 385
 386         log_info("SHA256 checksum of %s is valid.", job->url);
 387         return 1;
 388 }
 389
 390 int pull_verify(PullJob *main_job,
 391                 PullJob *roothash_job,
 392                 PullJob *settings_job,
 393                 PullJob *checksum_job,
 394                 PullJob *signature_job) {
 395
 396         _cleanup_close_pair_ int gpg_pipe[2] = { -1, -1 };
 397         _cleanup_free_ char *fn = NULL;
 398         _cleanup_close_ int sig_file = -1;
 399         char sig_file_path[] = "/tmp/sigXXXXXX", gpg_home[] = "/tmp/gpghomeXXXXXX";
 400         _cleanup_(sigkill_waitp) pid_t pid = 0;
 401         bool gpg_home_created = false;
 402         int r;
 403
 404         assert(main_job);
 405         assert(main_job->state == PULL_JOB_DONE);
 406
 407         if (!checksum_job)
 408                 return 0;
 409
 410         assert(main_job->calc_checksum);
 411         assert(main_job->checksum);
 412
 413         assert(checksum_job->state == PULL_JOB_DONE);
 414
 415         if (!checksum_job->payload || checksum_job->payload_size <= 0) {
 416                 log_error("Checksum is empty, cannot verify.");
 417                 return -EBADMSG;
 418         }
 419
 420         r = verify_one(checksum_job, main_job);
 421         if (r < 0)
 422                 return r;
 423
 424         r = verify_one(checksum_job, roothash_job);
 425         if (r < 0)
 426                 return r;
 427
 428         r = verify_one(checksum_job, settings_job);
 429         if (r < 0)
 430                 return r;
 431
 432         if (!signature_job)
 433                 return 0;
 434
 435         if (checksum_job->style == VERIFICATION_PER_FILE)
 436                 signature_job = checksum_job;
 437
 438         assert(signature_job->state == PULL_JOB_DONE);
 439
 440         if (!signature_job->payload || signature_job->payload_size <= 0) {
 441                 log_error("Signature is empty, cannot verify.");
 442                 return -EBADMSG;
 443         }
 444
 445         r = pipe2(gpg_pipe, O_CLOEXEC);
 446         if (r < 0)
 447                 return log_error_errno(errno, "Failed to create pipe for gpg: %m");
 448
 449         sig_file = mkostemp(sig_file_path, O_RDWR);
 450         if (sig_file < 0)
 451                 return log_error_errno(errno, "Failed to create temporary file: %m");
 452
 453         r = loop_write(sig_file, signature_job->payload, signature_job->payload_size, false);
 454         if (r < 0) {
 455                 log_error_errno(r, "Failed to write to temporary file: %m");
 456                 goto finish;
 457         }
 458
 459         if (!mkdtemp(gpg_home)) {
 460                 r = log_error_errno(errno, "Failed to create tempory home for gpg: %m");
 461                 goto finish;
 462         }
 463
 464         gpg_home_created = true;
 465
 466         pid = fork();
 467         if (pid < 0)
 468                 return log_error_errno(errno, "Failed to fork off gpg: %m");
 469         if (pid == 0) {
 470                 const char *cmd[] = {
 471                         "gpg",
 472                         "--no-options",
 473                         "--no-default-keyring",
 474                         "--no-auto-key-locate",
 475                         "--no-auto-check-trustdb",
 476                         "--batch",
 477                         "--trust-model=always",
 478                         NULL, /* --homedir=  */
 479                         NULL, /* --keyring= */
 480                         NULL, /* --verify */
 481                         NULL, /* signature file */
 482                         NULL, /* dash */
 483                         NULL  /* trailing NULL */
 484                 };
 485                 unsigned k = ELEMENTSOF(cmd) - 6;
 486                 int null_fd;
 487
 488                 /* Child */
 489
 490                 (void) reset_all_signal_handlers();
 491                 (void) reset_signal_mask();
 492                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
 493
 494                 gpg_pipe[1] = safe_close(gpg_pipe[1]);
 495
 496                 if (dup2(gpg_pipe[0], STDIN_FILENO) != STDIN_FILENO) {
 497                         log_error_errno(errno, "Failed to dup2() fd: %m");
 498                         _exit(EXIT_FAILURE);
 499                 }
 500
 501                 if (gpg_pipe[0] != STDIN_FILENO)
 502                         gpg_pipe[0] = safe_close(gpg_pipe[0]);
 503
 504                 null_fd = open("/dev/null", O_WRONLY|O_NOCTTY);
 505                 if (null_fd < 0) {
 506                         log_error_errno(errno, "Failed to open /dev/null: %m");
 507                         _exit(EXIT_FAILURE);
 508                 }
 509
 510                 if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) {
 511                         log_error_errno(errno, "Failed to dup2() fd: %m");
 512                         _exit(EXIT_FAILURE);
 513                 }
 514
 515                 if (null_fd != STDOUT_FILENO)
 516                         null_fd = safe_close(null_fd);
 517
 518                 cmd[k++] = strjoina("--homedir=", gpg_home);
 519
 520                 /* We add the user keyring only to the command line
 521                  * arguments, if it's around since gpg fails
 522                  * otherwise. */
 523                 if (access(USER_KEYRING_PATH, F_OK) >= 0)
 524                         cmd[k++] = "--keyring=" USER_KEYRING_PATH;
 525                 else
 526                         cmd[k++] = "--keyring=" VENDOR_KEYRING_PATH;
 527
 528                 cmd[k++] = "--verify";
 529                 if (checksum_job->style == VERIFICATION_PER_DIRECTORY) {
 530                         cmd[k++] = sig_file_path;
 531                         cmd[k++] = "-";
 532                         cmd[k++] = NULL;
 533                 }
 534
 535                 stdio_unset_cloexec();
 536
 537                 execvp("gpg2", (char * const *) cmd);
 538                 execvp("gpg", (char * const *) cmd);
 539                 log_error_errno(errno, "Failed to execute gpg: %m");
 540                 _exit(EXIT_FAILURE);
 541         }
 542
 543         gpg_pipe[0] = safe_close(gpg_pipe[0]);
 544
 545         r = loop_write(gpg_pipe[1], checksum_job->payload, checksum_job->payload_size, false);
 546         if (r < 0) {
 547                 log_error_errno(r, "Failed to write to pipe: %m");
 548                 goto finish;
 549         }
 550
 551         gpg_pipe[1] = safe_close(gpg_pipe[1]);
 552
 553         r = wait_for_terminate_and_warn("gpg", pid, true);
 554         pid = 0;
 555         if (r < 0)
 556                 goto finish;
 557         if (r > 0) {
 558                 log_error("DOWNLOAD INVALID: Signature verification failed.");
 559                 r = -EBADMSG;
 560         } else {
 561                 log_info("Signature verification succeeded.");
 562                 r = 0;
 563         }
 564
 565 finish:
 566         if (sig_file >= 0)
 567                 (void) unlink(sig_file_path);
 568
 569         if (gpg_home_created)
 570                 (void) rm_rf(gpg_home, REMOVE_ROOT|REMOVE_PHYSICAL);
 571
 572         return r;
 573 }