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, BTRFS_SNAPSHOT_QUOTA);
 148         if (r == -ENOTTY) {
 149                 r = copy_tree(final, p, false);
 150                 if (r < 0)
 151                         return log_error_errno(r, "Failed to copy image: %m");
 152         } else 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_settings_job(
 222                 PullJob **ret,
 223                 const char *url,
 224                 CurlGlue *glue,
 225                 PullJobFinished on_finished,
 226                 void *userdata) {
 227
 228         _cleanup_free_ char *last_component = NULL, *ll = NULL, *settings_url = NULL;
 229         _cleanup_(pull_job_unrefp) PullJob *job = NULL;
 230         const char *q;
 231         int r;
 232
 233         assert(ret);
 234         assert(url);
 235         assert(glue);
 236
 237         r = import_url_last_component(url, &last_component);
 238         if (r < 0)
 239                 return r;
 240
 241         r = tar_strip_suffixes(last_component, &ll);
 242         if (r < 0)
 243                 return r;
 244
 245         q = strjoina(ll, ".nspawn");
 246
 247         r = import_url_change_last_component(url, q, &settings_url);
 248         if (r < 0)
 249                 return r;
 250
 251         r = pull_job_new(&job, settings_url, glue, userdata);
 252         if (r < 0)
 253                 return r;
 254
 255         job->on_finished = on_finished;
 256         job->compressed_max = job->uncompressed_max = 1ULL * 1024ULL * 1024ULL;
 257
 258         *ret = job;
 259         job = NULL;
 260
 261         return 0;
 262 }
 263
 264 int pull_make_verification_jobs(
 265                 PullJob **ret_checksum_job,
 266                 PullJob **ret_signature_job,
 267                 ImportVerify verify,
 268                 const char *url,
 269                 CurlGlue *glue,
 270                 PullJobFinished on_finished,
 271                 void *userdata) {
 272
 273         _cleanup_(pull_job_unrefp) PullJob *checksum_job = NULL, *signature_job = NULL;
 274         int r;
 275
 276         assert(ret_checksum_job);
 277         assert(ret_signature_job);
 278         assert(verify >= 0);
 279         assert(verify < _IMPORT_VERIFY_MAX);
 280         assert(url);
 281         assert(glue);
 282
 283         if (verify != IMPORT_VERIFY_NO) {
 284                 _cleanup_free_ char *checksum_url = NULL;
 285
 286                 /* Queue job for the SHA256SUMS file for the image */
 287                 r = import_url_change_last_component(url, "SHA256SUMS", &checksum_url);
 288                 if (r < 0)
 289                         return r;
 290
 291                 r = pull_job_new(&checksum_job, checksum_url, glue, userdata);
 292                 if (r < 0)
 293                         return r;
 294
 295                 checksum_job->on_finished = on_finished;
 296                 checksum_job->uncompressed_max = checksum_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 297         }
 298
 299         if (verify == IMPORT_VERIFY_SIGNATURE) {
 300                 _cleanup_free_ char *signature_url = NULL;
 301
 302                 /* Queue job for the SHA256SUMS.gpg file for the image. */
 303                 r = import_url_change_last_component(url, "SHA256SUMS.gpg", &signature_url);
 304                 if (r < 0)
 305                         return r;
 306
 307                 r = pull_job_new(&signature_job, signature_url, glue, userdata);
 308                 if (r < 0)
 309                         return r;
 310
 311                 signature_job->on_finished = on_finished;
 312                 signature_job->uncompressed_max = signature_job->compressed_max = 1ULL * 1024ULL * 1024ULL;
 313         }
 314
 315         *ret_checksum_job = checksum_job;
 316         *ret_signature_job = signature_job;
 317
 318         checksum_job = signature_job = NULL;
 319
 320         return 0;
 321 }
 322
 323 int pull_verify(PullJob *main_job,
 324                 PullJob *settings_job,
 325                 PullJob *checksum_job,
 326                 PullJob *signature_job) {
 327
 328         _cleanup_close_pair_ int gpg_pipe[2] = { -1, -1 };
 329         _cleanup_free_ char *fn = NULL;
 330         _cleanup_close_ int sig_file = -1;
 331         const char *p, *line;
 332         char sig_file_path[] = "/tmp/sigXXXXXX", gpg_home[] = "/tmp/gpghomeXXXXXX";
 333         _cleanup_sigkill_wait_ pid_t pid = 0;
 334         bool gpg_home_created = false;
 335         int r;
 336
 337         assert(main_job);
 338         assert(main_job->state == PULL_JOB_DONE);
 339
 340         if (!checksum_job)
 341                 return 0;
 342
 343         assert(main_job->calc_checksum);
 344         assert(main_job->checksum);
 345         assert(checksum_job->state == PULL_JOB_DONE);
 346
 347         if (!checksum_job->payload || checksum_job->payload_size <= 0) {
 348                 log_error("Checksum is empty, cannot verify.");
 349                 return -EBADMSG;
 350         }
 351
 352         r = import_url_last_component(main_job->url, &fn);
 353         if (r < 0)
 354                 return log_oom();
 355
 356         if (!filename_is_valid(fn)) {
 357                 log_error("Cannot verify checksum, could not determine valid server-side file name.");
 358                 return -EBADMSG;
 359         }
 360
 361         line = strjoina(main_job->checksum, " *", fn, "\n");
 362
 363         p = memmem(checksum_job->payload,
 364                    checksum_job->payload_size,
 365                    line,
 366                    strlen(line));
 367
 368         if (!p || (p != (char*) checksum_job->payload && p[-1] != '\n')) {
 369                 log_error("DOWNLOAD INVALID: Checksum did not check out, payload has been tampered with.");
 370                 return -EBADMSG;
 371         }
 372
 373         log_info("SHA256 checksum of %s is valid.", main_job->url);
 374
 375         assert(!settings_job || IN_SET(settings_job->state, PULL_JOB_DONE, PULL_JOB_FAILED));
 376
 377         if (settings_job &&
 378             settings_job->state == PULL_JOB_DONE &&
 379             settings_job->error == 0 &&
 380             !settings_job->etag_exists) {
 381
 382                 _cleanup_free_ char *settings_fn = NULL;
 383
 384                 assert(settings_job->calc_checksum);
 385                 assert(settings_job->checksum);
 386
 387                 r = import_url_last_component(settings_job->url, &settings_fn);
 388                 if (r < 0)
 389                         return log_oom();
 390
 391                 if (!filename_is_valid(settings_fn)) {
 392                         log_error("Cannot verify checksum, could not determine server-side settings file name.");
 393                         return -EBADMSG;
 394                 }
 395
 396                 line = strjoina(settings_job->checksum, " *", settings_fn, "\n");
 397
 398                 p = memmem(checksum_job->payload,
 399                            checksum_job->payload_size,
 400                            line,
 401                            strlen(line));
 402
 403                 if (!p || (p != (char*) checksum_job->payload && p[-1] != '\n')) {
 404                         log_error("DOWNLOAD INVALID: Checksum of settings file did not checkout, settings file has been tampered with.");
 405                         return -EBADMSG;
 406                 }
 407
 408                 log_info("SHA256 checksum of %s is valid.", settings_job->url);
 409         }
 410
 411         if (!signature_job)
 412                 return 0;
 413
 414         assert(signature_job->state == PULL_JOB_DONE);
 415
 416         if (!signature_job->payload || signature_job->payload_size <= 0) {
 417                 log_error("Signature is empty, cannot verify.");
 418                 return -EBADMSG;
 419         }
 420
 421         r = pipe2(gpg_pipe, O_CLOEXEC);
 422         if (r < 0)
 423                 return log_error_errno(errno, "Failed to create pipe for gpg: %m");
 424
 425         sig_file = mkostemp(sig_file_path, O_RDWR);
 426         if (sig_file < 0)
 427                 return log_error_errno(errno, "Failed to create temporary file: %m");
 428
 429         r = loop_write(sig_file, signature_job->payload, signature_job->payload_size, false);
 430         if (r < 0) {
 431                 log_error_errno(r, "Failed to write to temporary file: %m");
 432                 goto finish;
 433         }
 434
 435         if (!mkdtemp(gpg_home)) {
 436                 r = log_error_errno(errno, "Failed to create tempory home for gpg: %m");
 437                 goto finish;
 438         }
 439
 440         gpg_home_created = true;
 441
 442         pid = fork();
 443         if (pid < 0)
 444                 return log_error_errno(errno, "Failed to fork off gpg: %m");
 445         if (pid == 0) {
 446                 const char *cmd[] = {
 447                         "gpg",
 448                         "--no-options",
 449                         "--no-default-keyring",
 450                         "--no-auto-key-locate",
 451                         "--no-auto-check-trustdb",
 452                         "--batch",
 453                         "--trust-model=always",
 454                         NULL, /* --homedir=  */
 455                         NULL, /* --keyring= */
 456                         NULL, /* --verify */
 457                         NULL, /* signature file */
 458                         NULL, /* dash */
 459                         NULL  /* trailing NULL */
 460                 };
 461                 unsigned k = ELEMENTSOF(cmd) - 6;
 462                 int null_fd;
 463
 464                 /* Child */
 465
 466                 (void) reset_all_signal_handlers();
 467                 (void) reset_signal_mask();
 468                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
 469
 470                 gpg_pipe[1] = safe_close(gpg_pipe[1]);
 471
 472                 if (dup2(gpg_pipe[0], STDIN_FILENO) != STDIN_FILENO) {
 473                         log_error_errno(errno, "Failed to dup2() fd: %m");
 474                         _exit(EXIT_FAILURE);
 475                 }
 476
 477                 if (gpg_pipe[0] != STDIN_FILENO)
 478                         gpg_pipe[0] = safe_close(gpg_pipe[0]);
 479
 480                 null_fd = open("/dev/null", O_WRONLY|O_NOCTTY);
 481                 if (null_fd < 0) {
 482                         log_error_errno(errno, "Failed to open /dev/null: %m");
 483                         _exit(EXIT_FAILURE);
 484                 }
 485
 486                 if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) {
 487                         log_error_errno(errno, "Failed to dup2() fd: %m");
 488                         _exit(EXIT_FAILURE);
 489                 }
 490
 491                 if (null_fd != STDOUT_FILENO)
 492                         null_fd = safe_close(null_fd);
 493
 494                 cmd[k++] = strjoina("--homedir=", gpg_home);
 495
 496                 /* We add the user keyring only to the command line
 497                  * arguments, if it's around since gpg fails
 498                  * otherwise. */
 499                 if (access(USER_KEYRING_PATH, F_OK) >= 0)
 500                         cmd[k++] = "--keyring=" USER_KEYRING_PATH;
 501                 else
 502                         cmd[k++] = "--keyring=" VENDOR_KEYRING_PATH;
 503
 504                 cmd[k++] = "--verify";
 505                 cmd[k++] = sig_file_path;
 506                 cmd[k++] = "-";
 507                 cmd[k++] = NULL;
 508
 509                 fd_cloexec(STDIN_FILENO, false);
 510                 fd_cloexec(STDOUT_FILENO, false);
 511                 fd_cloexec(STDERR_FILENO, false);
 512
 513                 execvp("gpg2", (char * const *) cmd);
 514                 execvp("gpg", (char * const *) cmd);
 515                 log_error_errno(errno, "Failed to execute gpg: %m");
 516                 _exit(EXIT_FAILURE);
 517         }
 518
 519         gpg_pipe[0] = safe_close(gpg_pipe[0]);
 520
 521         r = loop_write(gpg_pipe[1], checksum_job->payload, checksum_job->payload_size, false);
 522         if (r < 0) {
 523                 log_error_errno(r, "Failed to write to pipe: %m");
 524                 goto finish;
 525         }
 526
 527         gpg_pipe[1] = safe_close(gpg_pipe[1]);
 528
 529         r = wait_for_terminate_and_warn("gpg", pid, true);
 530         pid = 0;
 531         if (r < 0)
 532                 goto finish;
 533         if (r > 0) {
 534                 log_error("DOWNLOAD INVALID: Signature verification failed.");
 535                 r = -EBADMSG;
 536         } else {
 537                 log_info("Signature verification succeeded.");
 538                 r = 0;
 539         }
 540
 541 finish:
 542         if (sig_file >= 0)
 543                 (void) unlink(sig_file_path);
 544
 545         if (gpg_home_created)
 546                 (void) rm_rf(gpg_home, REMOVE_ROOT|REMOVE_PHYSICAL);
 547
 548         return r;
 549 }