src/shared/bus-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <inttypes.h>
   6 #include <stdlib.h>
   7 #include <sys/ioctl.h>
   8 #include <sys/resource.h>
   9 #include <sys/socket.h>
  10 #include <unistd.h>
  11
  12 #include "sd-bus.h"
  13 #include "sd-daemon.h"
  14 #include "sd-event.h"
  15 #include "sd-id128.h"
  16
  17 #include "bus-common-errors.h"
  18 #include "bus-internal.h"
  19 #include "bus-label.h"
  20 #include "bus-util.h"
  21 #include "data-fd-util.h"
  22 #include "fd-util.h"
  23 #include "path-util.h"
  24 #include "socket-util.h"
  25 #include "stdio-util.h"
  26
  27 static int name_owner_change_callback(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
  28         sd_event *e = ASSERT_PTR(userdata);
  29
  30         assert(m);
  31
  32         sd_bus_close(sd_bus_message_get_bus(m));
  33         sd_event_exit(e, 0);
  34
  35         return 1;
  36 }
  37
  38 int bus_log_address_error(int r, BusTransport transport) {
  39         bool hint = transport == BUS_TRANSPORT_LOCAL && r == -ENOMEDIUM;
  40
  41         return log_error_errno(r,
  42                                hint ? "Failed to set bus address: $DBUS_SESSION_BUS_ADDRESS and $XDG_RUNTIME_DIR not defined (consider using --machine=<user>@.host --user to connect to bus of other user)" :
  43                                       "Failed to set bus address: %m");
  44 }
  45
  46 int bus_log_connect_error(int r, BusTransport transport) {
  47         bool hint_vars = transport == BUS_TRANSPORT_LOCAL && r == -ENOMEDIUM,
  48              hint_addr = transport == BUS_TRANSPORT_LOCAL && ERRNO_IS_PRIVILEGE(r);
  49
  50         return log_error_errno(r,
  51                                r == hint_vars ? "Failed to connect to bus: $DBUS_SESSION_BUS_ADDRESS and $XDG_RUNTIME_DIR not defined (consider using --machine=<user>@.host --user to connect to bus of other user)" :
  52                                r == hint_addr ? "Failed to connect to bus: Operation not permitted (consider using --machine=<user>@.host --user to connect to bus of other user)" :
  53                                                 "Failed to connect to bus: %m");
  54 }
  55
  56 int bus_async_unregister_and_exit(sd_event *e, sd_bus *bus, const char *name) {
  57         const char *match;
  58         const char *unique;
  59         int r;
  60
  61         assert(e);
  62         assert(bus);
  63         assert(name);
  64
  65         /* We unregister the name here and then wait for the
  66          * NameOwnerChanged signal for this event to arrive before we
  67          * quit. We do this in order to make sure that any queued
  68          * requests are still processed before we really exit. */
  69
  70         r = sd_bus_get_unique_name(bus, &unique);
  71         if (r < 0)
  72                 return r;
  73
  74         match = strjoina(
  75                         "sender='org.freedesktop.DBus',"
  76                         "type='signal',"
  77                         "interface='org.freedesktop.DBus',"
  78                         "member='NameOwnerChanged',"
  79                         "path='/org/freedesktop/DBus',"
  80                         "arg0='", name, "',",
  81                         "arg1='", unique, "',",
  82                         "arg2=''");
  83
  84         r = sd_bus_add_match_async(bus, NULL, match, name_owner_change_callback, NULL, e);
  85         if (r < 0)
  86                 return r;
  87
  88         r = sd_bus_release_name_async(bus, NULL, name, NULL, NULL);
  89         if (r < 0)
  90                 return r;
  91
  92         return 0;
  93 }
  94
  95 int bus_event_loop_with_idle(
  96                 sd_event *e,
  97                 sd_bus *bus,
  98                 const char *name,
  99                 usec_t timeout,
 100                 check_idle_t check_idle,
 101                 void *userdata) {
 102
 103         bool exiting = false;
 104         int r, code;
 105
 106         assert(e);
 107         assert(bus);
 108         assert(name);
 109
 110         for (;;) {
 111                 bool idle;
 112
 113                 r = sd_event_get_state(e);
 114                 if (r < 0)
 115                         return r;
 116                 if (r == SD_EVENT_FINISHED)
 117                         break;
 118
 119                 if (check_idle)
 120                         idle = check_idle(userdata);
 121                 else
 122                         idle = true;
 123
 124                 r = sd_event_run(e, exiting || !idle ? UINT64_MAX : timeout);
 125                 if (r < 0)
 126                         return r;
 127
 128                 if (r == 0 && !exiting && idle) {
 129                         /* Inform the service manager that we are going down, so that it will queue all
 130                          * further start requests, instead of assuming we are already running. */
 131                         sd_notify(false, "STOPPING=1");
 132
 133                         r = bus_async_unregister_and_exit(e, bus, name);
 134                         if (r < 0)
 135                                 return r;
 136
 137                         exiting = true;
 138                 }
 139         }
 140
 141         r = sd_event_get_exit_code(e, &code);
 142         if (r < 0)
 143                 return r;
 144
 145         return code;
 146 }
 147
 148 int bus_name_has_owner(sd_bus *c, const char *name, sd_bus_error *error) {
 149         _cleanup_(sd_bus_message_unrefp) sd_bus_message *rep = NULL;
 150         int r, has_owner = 0;
 151
 152         assert(c);
 153         assert(name);
 154
 155         r = sd_bus_call_method(c,
 156                                "org.freedesktop.DBus",
 157                                "/org/freedesktop/dbus",
 158                                "org.freedesktop.DBus",
 159                                "NameHasOwner",
 160                                error,
 161                                &rep,
 162                                "s",
 163                                name);
 164         if (r < 0)
 165                 return r;
 166
 167         r = sd_bus_message_read_basic(rep, 'b', &has_owner);
 168         if (r < 0)
 169                 return sd_bus_error_set_errno(error, r);
 170
 171         return has_owner;
 172 }
 173
 174 bool bus_error_is_unknown_service(const sd_bus_error *error) {
 175         return sd_bus_error_has_names(error,
 176                                       SD_BUS_ERROR_SERVICE_UNKNOWN,
 177                                       SD_BUS_ERROR_NAME_HAS_NO_OWNER,
 178                                       BUS_ERROR_NO_SUCH_UNIT);
 179 }
 180
 181 int bus_check_peercred(sd_bus *c) {
 182         struct ucred ucred;
 183         int fd, r;
 184
 185         assert(c);
 186
 187         fd = sd_bus_get_fd(c);
 188         if (fd < 0)
 189                 return fd;
 190
 191         r = getpeercred(fd, &ucred);
 192         if (r < 0)
 193                 return r;
 194
 195         if (ucred.uid != 0 && ucred.uid != geteuid())
 196                 return -EPERM;
 197
 198         return 1;
 199 }
 200
 201 int bus_connect_system_systemd(sd_bus **ret_bus) {
 202         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 203         int r;
 204
 205         assert(ret_bus);
 206
 207         if (geteuid() != 0)
 208                 return sd_bus_default_system(ret_bus);
 209
 210         /* If we are root then let's talk directly to the system
 211          * instance, instead of going via the bus */
 212
 213         r = sd_bus_new(&bus);
 214         if (r < 0)
 215                 return r;
 216
 217         r = sd_bus_set_address(bus, "unix:path=/run/systemd/private");
 218         if (r < 0)
 219                 return r;
 220
 221         r = sd_bus_start(bus);
 222         if (r < 0)
 223                 return sd_bus_default_system(ret_bus);
 224
 225         r = bus_check_peercred(bus);
 226         if (r < 0)
 227                 return r;
 228
 229         *ret_bus = TAKE_PTR(bus);
 230         return 0;
 231 }
 232
 233 int bus_connect_user_systemd(sd_bus **ret_bus) {
 234         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 235         _cleanup_free_ char *ee = NULL;
 236         const char *e;
 237         int r;
 238
 239         assert(ret_bus);
 240
 241         e = secure_getenv("XDG_RUNTIME_DIR");
 242         if (!e)
 243                 return sd_bus_default_user(ret_bus);
 244
 245         ee = bus_address_escape(e);
 246         if (!ee)
 247                 return -ENOMEM;
 248
 249         r = sd_bus_new(&bus);
 250         if (r < 0)
 251                 return r;
 252
 253         bus->address = strjoin("unix:path=", ee, "/systemd/private");
 254         if (!bus->address)
 255                 return -ENOMEM;
 256
 257         r = sd_bus_start(bus);
 258         if (r < 0)
 259                 return sd_bus_default_user(ret_bus);
 260
 261         r = bus_check_peercred(bus);
 262         if (r < 0)
 263                 return r;
 264
 265         *ret_bus = TAKE_PTR(bus);
 266         return 0;
 267 }
 268
 269 int bus_connect_transport(
 270                 BusTransport transport,
 271                 const char *host,
 272                 RuntimeScope runtime_scope,
 273                 sd_bus **ret) {
 274
 275         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 276         int r;
 277
 278         assert(transport >= 0);
 279         assert(transport < _BUS_TRANSPORT_MAX);
 280         assert(ret);
 281
 282         assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
 283         assert_return(transport != BUS_TRANSPORT_REMOTE || runtime_scope == RUNTIME_SCOPE_SYSTEM, -EOPNOTSUPP);
 284
 285         switch (transport) {
 286
 287         case BUS_TRANSPORT_LOCAL:
 288
 289                 switch (runtime_scope) {
 290
 291                 case RUNTIME_SCOPE_USER:
 292                         r = sd_bus_default_user(&bus);
 293                         break;
 294
 295                 case RUNTIME_SCOPE_SYSTEM:
 296                         if (sd_booted() <= 0)
 297                                 /* Print a friendly message when the local system is actually not running systemd as PID 1. */
 298                                 return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
 299                                                        "System has not been booted with systemd as init system (PID 1). Can't operate.");
 300                         r = sd_bus_default_system(&bus);
 301                         break;
 302
 303                 default:
 304                         assert_not_reached();
 305                 }
 306                 break;
 307
 308         case BUS_TRANSPORT_REMOTE:
 309                 r = sd_bus_open_system_remote(&bus, host);
 310                 break;
 311
 312         case BUS_TRANSPORT_MACHINE:
 313
 314                 switch (runtime_scope) {
 315
 316                 case RUNTIME_SCOPE_USER:
 317                         r = sd_bus_open_user_machine(&bus, host);
 318                         break;
 319
 320                 case RUNTIME_SCOPE_SYSTEM:
 321                         r = sd_bus_open_system_machine(&bus, host);
 322                         break;
 323
 324                 default:
 325                         assert_not_reached();
 326                 }
 327
 328                 break;
 329
 330         default:
 331                 assert_not_reached();
 332         }
 333         if (r < 0)
 334                 return r;
 335
 336         r = sd_bus_set_exit_on_disconnect(bus, true);
 337         if (r < 0)
 338                 return r;
 339
 340         *ret = TAKE_PTR(bus);
 341         return 0;
 342 }
 343
 344 int bus_connect_transport_systemd(BusTransport transport, const char *host, RuntimeScope runtime_scope, sd_bus **bus) {
 345         assert(transport >= 0);
 346         assert(transport < _BUS_TRANSPORT_MAX);
 347         assert(bus);
 348
 349         assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
 350         assert_return(transport == BUS_TRANSPORT_LOCAL || runtime_scope == RUNTIME_SCOPE_SYSTEM, -EOPNOTSUPP);
 351
 352         switch (transport) {
 353
 354         case BUS_TRANSPORT_LOCAL:
 355                 switch (runtime_scope) {
 356
 357                 case RUNTIME_SCOPE_USER:
 358                         return bus_connect_user_systemd(bus);
 359
 360                 case RUNTIME_SCOPE_SYSTEM:
 361                         if (sd_booted() <= 0)
 362                                 /* Print a friendly message when the local system is actually not running systemd as PID 1. */
 363                                 return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
 364                                                        "System has not been booted with systemd as init system (PID 1). Can't operate.");
 365                         return bus_connect_system_systemd(bus);
 366
 367                 default:
 368                         assert_not_reached();
 369                 }
 370
 371                 break;
 372
 373         case BUS_TRANSPORT_REMOTE:
 374                 return sd_bus_open_system_remote(bus, host);
 375
 376         case BUS_TRANSPORT_MACHINE:
 377                 return sd_bus_open_system_machine(bus, host);
 378
 379         default:
 380                 assert_not_reached();
 381         }
 382 }
 383
 384 /**
 385  * bus_path_encode_unique() - encode unique object path
 386  * @b: bus connection or NULL
 387  * @prefix: object path prefix
 388  * @sender_id: unique-name of client, or NULL
 389  * @external_id: external ID to be chosen by client, or NULL
 390  * @ret_path: storage for encoded object path pointer
 391  *
 392  * Whenever we provide a bus API that allows clients to create and manage
 393  * server-side objects, we need to provide a unique name for these objects. If
 394  * we let the server choose the name, we suffer from a race condition: If a
 395  * client creates an object asynchronously, it cannot destroy that object until
 396  * it received the method reply. It cannot know the name of the new object,
 397  * thus, it cannot destroy it. Furthermore, it enforces a round-trip.
 398  *
 399  * Therefore, many APIs allow the client to choose the unique name for newly
 400  * created objects. There're two problems to solve, though:
 401  *    1) Object names are usually defined via dbus object paths, which are
 402  *       usually globally namespaced. Therefore, multiple clients must be able
 403  *       to choose unique object names without interference.
 404  *    2) If multiple libraries share the same bus connection, they must be
 405  *       able to choose unique object names without interference.
 406  * The first problem is solved easily by prefixing a name with the
 407  * unique-bus-name of a connection. The server side must enforce this and
 408  * reject any other name. The second problem is solved by providing unique
 409  * suffixes from within sd-bus.
 410  *
 411  * This helper allows clients to create unique object-paths. It uses the
 412  * template '/prefix/sender_id/external_id' and returns the new path in
 413  * @ret_path (must be freed by the caller).
 414  * If @sender_id is NULL, the unique-name of @b is used. If @external_id is
 415  * NULL, this function allocates a unique suffix via @b (by requesting a new
 416  * cookie). If both @sender_id and @external_id are given, @b can be passed as
 417  * NULL.
 418  *
 419  * Returns: 0 on success, negative error code on failure.
 420  */
 421 int bus_path_encode_unique(sd_bus *b, const char *prefix, const char *sender_id, const char *external_id, char **ret_path) {
 422         _cleanup_free_ char *sender_label = NULL, *external_label = NULL;
 423         char external_buf[DECIMAL_STR_MAX(uint64_t)], *p;
 424         int r;
 425
 426         assert_return(b || (sender_id && external_id), -EINVAL);
 427         assert_return(sd_bus_object_path_is_valid(prefix), -EINVAL);
 428         assert_return(ret_path, -EINVAL);
 429
 430         if (!sender_id) {
 431                 r = sd_bus_get_unique_name(b, &sender_id);
 432                 if (r < 0)
 433                         return r;
 434         }
 435
 436         if (!external_id) {
 437                 xsprintf(external_buf, "%"PRIu64, ++b->cookie);
 438                 external_id = external_buf;
 439         }
 440
 441         sender_label = bus_label_escape(sender_id);
 442         if (!sender_label)
 443                 return -ENOMEM;
 444
 445         external_label = bus_label_escape(external_id);
 446         if (!external_label)
 447                 return -ENOMEM;
 448
 449         p = path_join(prefix, sender_label, external_label);
 450         if (!p)
 451                 return -ENOMEM;
 452
 453         *ret_path = p;
 454         return 0;
 455 }
 456
 457 /**
 458  * bus_path_decode_unique() - decode unique object path
 459  * @path: object path to decode
 460  * @prefix: object path prefix
 461  * @ret_sender: output parameter for sender-id label
 462  * @ret_external: output parameter for external-id label
 463  *
 464  * This does the reverse of bus_path_encode_unique() (see its description for
 465  * details). Both trailing labels, sender-id and external-id, are unescaped and
 466  * returned in the given output parameters (the caller must free them).
 467  *
 468  * Note that this function returns 0 if the path does not match the template
 469  * (see bus_path_encode_unique()), 1 if it matched.
 470  *
 471  * Returns: Negative error code on failure, 0 if the given object path does not
 472  *          match the template (return parameters are set to NULL), 1 if it was
 473  *          parsed successfully (return parameters contain allocated labels).
 474  */
 475 int bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external) {
 476         const char *p, *q;
 477         char *sender, *external;
 478
 479         assert(sd_bus_object_path_is_valid(path));
 480         assert(sd_bus_object_path_is_valid(prefix));
 481         assert(ret_sender);
 482         assert(ret_external);
 483
 484         p = object_path_startswith(path, prefix);
 485         if (!p) {
 486                 *ret_sender = NULL;
 487                 *ret_external = NULL;
 488                 return 0;
 489         }
 490
 491         q = strchr(p, '/');
 492         if (!q) {
 493                 *ret_sender = NULL;
 494                 *ret_external = NULL;
 495                 return 0;
 496         }
 497
 498         sender = bus_label_unescape_n(p, q - p);
 499         external = bus_label_unescape(q + 1);
 500         if (!sender || !external) {
 501                 free(sender);
 502                 free(external);
 503                 return -ENOMEM;
 504         }
 505
 506         *ret_sender = sender;
 507         *ret_external = external;
 508         return 1;
 509 }
 510
 511 int bus_track_add_name_many(sd_bus_track *t, char **l) {
 512         int r = 0;
 513
 514         assert(t);
 515
 516         /* Continues adding after failure, and returns the first failure. */
 517
 518         STRV_FOREACH(i, l) {
 519                 int k;
 520
 521                 k = sd_bus_track_add_name(t, *i);
 522                 if (k < 0 && r >= 0)
 523                         r = k;
 524         }
 525
 526         return r;
 527 }
 528
 529 int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description) {
 530         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 531         const char *e;
 532         int r;
 533
 534         assert(ret);
 535
 536         /* Match like sd_bus_open_system(), but with the "watch_bind" feature and the Connected() signal
 537          * turned on. */
 538
 539         r = sd_bus_new(&bus);
 540         if (r < 0)
 541                 return r;
 542
 543         if (description) {
 544                 r = sd_bus_set_description(bus, description);
 545                 if (r < 0)
 546                         return r;
 547         }
 548
 549         e = secure_getenv("DBUS_SYSTEM_BUS_ADDRESS");
 550         if (!e)
 551                 e = DEFAULT_SYSTEM_BUS_ADDRESS;
 552
 553         r = sd_bus_set_address(bus, e);
 554         if (r < 0)
 555                 return r;
 556
 557         r = sd_bus_set_bus_client(bus, true);
 558         if (r < 0)
 559                 return r;
 560
 561         r = sd_bus_negotiate_creds(bus, true, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS);
 562         if (r < 0)
 563                 return r;
 564
 565         r = sd_bus_set_watch_bind(bus, true);
 566         if (r < 0)
 567                 return r;
 568
 569         r = sd_bus_set_connected_signal(bus, true);
 570         if (r < 0)
 571                 return r;
 572
 573         r = sd_bus_start(bus);
 574         if (r < 0)
 575                 return r;
 576
 577         *ret = TAKE_PTR(bus);
 578
 579         return 0;
 580 }
 581
 582 int bus_reply_pair_array(sd_bus_message *m, char **l) {
 583         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 584         int r;
 585
 586         assert(m);
 587
 588         /* Reply to the specified message with a message containing a dictionary put together from the
 589          * specified strv */
 590
 591         r = sd_bus_message_new_method_return(m, &reply);
 592         if (r < 0)
 593                 return r;
 594
 595         r = sd_bus_message_open_container(reply, 'a', "{ss}");
 596         if (r < 0)
 597                 return r;
 598
 599         STRV_FOREACH_PAIR(k, v, l) {
 600                 r = sd_bus_message_append(reply, "{ss}", *k, *v);
 601                 if (r < 0)
 602                         return r;
 603         }
 604
 605         r = sd_bus_message_close_container(reply);
 606         if (r < 0)
 607                 return r;
 608
 609         return sd_bus_send(NULL, reply, NULL);
 610 }
 611
 612 static int method_dump_memory_state_by_fd(sd_bus_message *message, void *userdata, sd_bus_error *ret_error) {
 613         _cleanup_free_ char *dump = NULL; /* keep this above dump_file, so that it's freed after */
 614         _cleanup_fclose_ FILE *dump_file = NULL;
 615         _cleanup_close_ int fd = -EBADF;
 616         size_t dump_size;
 617         int r;
 618
 619         assert(message);
 620
 621         dump_file = open_memstream(&dump, &dump_size);
 622         if (!dump_file)
 623                 return -ENOMEM;
 624
 625         r = RET_NERRNO(malloc_info(/* options= */ 0, dump_file));
 626         if (r < 0)
 627                 return r;
 628
 629         dump_file = safe_fclose(dump_file);
 630
 631         if (!dump)
 632                 return -ENOMEM;
 633
 634         fd = acquire_data_fd(dump, dump_size, 0);
 635         if (fd < 0)
 636                 return fd;
 637
 638         r = sd_bus_reply_method_return(message, "h", fd);
 639         if (r < 0)
 640                 return r;
 641
 642         return 1; /* Stop further processing */
 643 }
 644
 645 /* The default install callback will fail and disconnect the bus if it cannot register the match, but this
 646  * is only a debug method, we definitely don't want to fail in case there's some permission issue. */
 647 static int dummy_install_callback(sd_bus_message *message, void *userdata, sd_bus_error *ret_error) {
 648         return 1;
 649 }
 650
 651 int bus_register_malloc_status(sd_bus *bus, const char *destination) {
 652         const char *match;
 653         int r;
 654
 655         assert(bus);
 656         assert(!isempty(destination));
 657
 658         match = strjoina("type='method_call',"
 659                          "interface='org.freedesktop.MemoryAllocation1',"
 660                          "path='/org/freedesktop/MemoryAllocation1',"
 661                          "destination='", destination, "',",
 662                          "member='GetMallocInfo'");
 663
 664         r = sd_bus_add_match_async(bus, NULL, match, method_dump_memory_state_by_fd, dummy_install_callback, NULL);
 665         if (r < 0)
 666                 return log_debug_errno(r, "Failed to subscribe to GetMallocInfo() calls on MemoryAllocation1 interface: %m");
 667
 668         return 0;
 669 }
 670
 671 static void bus_message_unref_wrapper(void *m) {
 672         sd_bus_message_unref(m);
 673 }
 674
 675 const struct hash_ops bus_message_hash_ops = {
 676         .hash = trivial_hash_func,
 677         .compare = trivial_compare_func,
 678         .free_value = bus_message_unref_wrapper,
 679 };