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 "memstream-util.h"
  24 #include "path-util.h"
  25 #include "socket-util.h"
  26 #include "stdio-util.h"
  27
  28 static int name_owner_change_callback(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
  29         sd_event *e = ASSERT_PTR(userdata);
  30
  31         assert(m);
  32
  33         sd_bus_close(sd_bus_message_get_bus(m));
  34         sd_event_exit(e, 0);
  35
  36         return 1;
  37 }
  38
  39 int bus_log_address_error(int r, BusTransport transport) {
  40         bool hint = transport == BUS_TRANSPORT_LOCAL && r == -ENOMEDIUM;
  41
  42         return log_error_errno(r,
  43                                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)" :
  44                                       "Failed to set bus address: %m");
  45 }
  46
  47 int bus_log_connect_error(int r, BusTransport transport) {
  48         bool hint_vars = transport == BUS_TRANSPORT_LOCAL && r == -ENOMEDIUM,
  49              hint_addr = transport == BUS_TRANSPORT_LOCAL && ERRNO_IS_PRIVILEGE(r);
  50
  51         return log_error_errno(r,
  52                                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)" :
  53                                r == hint_addr ? "Failed to connect to bus: Operation not permitted (consider using --machine=<user>@.host --user to connect to bus of other user)" :
  54                                                 "Failed to connect to bus: %m");
  55 }
  56
  57 int bus_async_unregister_and_exit(sd_event *e, sd_bus *bus, const char *name) {
  58         const char *match;
  59         const char *unique;
  60         int r;
  61
  62         assert(e);
  63         assert(bus);
  64         assert(name);
  65
  66         /* We unregister the name here and then wait for the
  67          * NameOwnerChanged signal for this event to arrive before we
  68          * quit. We do this in order to make sure that any queued
  69          * requests are still processed before we really exit. */
  70
  71         r = sd_bus_get_unique_name(bus, &unique);
  72         if (r < 0)
  73                 return r;
  74
  75         match = strjoina(
  76                         "sender='org.freedesktop.DBus',"
  77                         "type='signal',"
  78                         "interface='org.freedesktop.DBus',"
  79                         "member='NameOwnerChanged',"
  80                         "path='/org/freedesktop/DBus',"
  81                         "arg0='", name, "',",
  82                         "arg1='", unique, "',",
  83                         "arg2=''");
  84
  85         r = sd_bus_add_match_async(bus, NULL, match, name_owner_change_callback, NULL, e);
  86         if (r < 0)
  87                 return r;
  88
  89         r = sd_bus_release_name_async(bus, NULL, name, NULL, NULL);
  90         if (r < 0)
  91                 return r;
  92
  93         return 0;
  94 }
  95
  96 int bus_event_loop_with_idle(
  97                 sd_event *e,
  98                 sd_bus *bus,
  99                 const char *name,
 100                 usec_t timeout,
 101                 check_idle_t check_idle,
 102                 void *userdata) {
 103
 104         bool exiting = false;
 105         int r, code;
 106
 107         assert(e);
 108         assert(bus);
 109         assert(name);
 110
 111         for (;;) {
 112                 bool idle;
 113
 114                 r = sd_event_get_state(e);
 115                 if (r < 0)
 116                         return r;
 117                 if (r == SD_EVENT_FINISHED)
 118                         break;
 119
 120                 if (check_idle)
 121                         idle = check_idle(userdata);
 122                 else
 123                         idle = true;
 124
 125                 r = sd_event_run(e, exiting || !idle ? UINT64_MAX : timeout);
 126                 if (r < 0)
 127                         return r;
 128
 129                 if (r == 0 && !exiting && idle) {
 130                         /* Inform the service manager that we are going down, so that it will queue all
 131                          * further start requests, instead of assuming we are already running. */
 132                         sd_notify(false, "STOPPING=1");
 133
 134                         r = bus_async_unregister_and_exit(e, bus, name);
 135                         if (r < 0)
 136                                 return r;
 137
 138                         exiting = true;
 139                 }
 140         }
 141
 142         r = sd_event_get_exit_code(e, &code);
 143         if (r < 0)
 144                 return r;
 145
 146         return code;
 147 }
 148
 149 int bus_name_has_owner(sd_bus *c, const char *name, sd_bus_error *error) {
 150         _cleanup_(sd_bus_message_unrefp) sd_bus_message *rep = NULL;
 151         int r, has_owner = 0;
 152
 153         assert(c);
 154         assert(name);
 155
 156         r = sd_bus_call_method(c,
 157                                "org.freedesktop.DBus",
 158                                "/org/freedesktop/dbus",
 159                                "org.freedesktop.DBus",
 160                                "NameHasOwner",
 161                                error,
 162                                &rep,
 163                                "s",
 164                                name);
 165         if (r < 0)
 166                 return r;
 167
 168         r = sd_bus_message_read_basic(rep, 'b', &has_owner);
 169         if (r < 0)
 170                 return sd_bus_error_set_errno(error, r);
 171
 172         return has_owner;
 173 }
 174
 175 bool bus_error_is_unknown_service(const sd_bus_error *error) {
 176         return sd_bus_error_has_names(error,
 177                                       SD_BUS_ERROR_SERVICE_UNKNOWN,
 178                                       SD_BUS_ERROR_NAME_HAS_NO_OWNER,
 179                                       BUS_ERROR_NO_SUCH_UNIT);
 180 }
 181
 182 int bus_check_peercred(sd_bus *c) {
 183         struct ucred ucred;
 184         int fd, r;
 185
 186         assert(c);
 187
 188         fd = sd_bus_get_fd(c);
 189         if (fd < 0)
 190                 return fd;
 191
 192         r = getpeercred(fd, &ucred);
 193         if (r < 0)
 194                 return r;
 195
 196         if (ucred.uid != 0 && ucred.uid != geteuid())
 197                 return -EPERM;
 198
 199         return 1;
 200 }
 201
 202 int bus_connect_system_systemd(sd_bus **ret_bus) {
 203         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 204         int r;
 205
 206         assert(ret_bus);
 207
 208         if (geteuid() != 0)
 209                 return sd_bus_default_system(ret_bus);
 210
 211         /* If we are root then let's talk directly to the system
 212          * instance, instead of going via the bus */
 213
 214         r = sd_bus_new(&bus);
 215         if (r < 0)
 216                 return r;
 217
 218         r = sd_bus_set_address(bus, "unix:path=/run/systemd/private");
 219         if (r < 0)
 220                 return r;
 221
 222         r = sd_bus_start(bus);
 223         if (r < 0)
 224                 return sd_bus_default_system(ret_bus);
 225
 226         r = bus_check_peercred(bus);
 227         if (r < 0)
 228                 return r;
 229
 230         *ret_bus = TAKE_PTR(bus);
 231         return 0;
 232 }
 233
 234 int bus_connect_user_systemd(sd_bus **ret_bus) {
 235         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 236         _cleanup_free_ char *ee = NULL;
 237         const char *e;
 238         int r;
 239
 240         assert(ret_bus);
 241
 242         e = secure_getenv("XDG_RUNTIME_DIR");
 243         if (!e)
 244                 return sd_bus_default_user(ret_bus);
 245
 246         ee = bus_address_escape(e);
 247         if (!ee)
 248                 return -ENOMEM;
 249
 250         r = sd_bus_new(&bus);
 251         if (r < 0)
 252                 return r;
 253
 254         bus->address = strjoin("unix:path=", ee, "/systemd/private");
 255         if (!bus->address)
 256                 return -ENOMEM;
 257
 258         r = sd_bus_start(bus);
 259         if (r < 0)
 260                 return sd_bus_default_user(ret_bus);
 261
 262         r = bus_check_peercred(bus);
 263         if (r < 0)
 264                 return r;
 265
 266         *ret_bus = TAKE_PTR(bus);
 267         return 0;
 268 }
 269
 270 int bus_connect_transport(
 271                 BusTransport transport,
 272                 const char *host,
 273                 RuntimeScope runtime_scope,
 274                 sd_bus **ret) {
 275
 276         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 277         int r;
 278
 279         assert(transport >= 0);
 280         assert(transport < _BUS_TRANSPORT_MAX);
 281         assert(ret);
 282
 283         assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
 284         assert_return(transport != BUS_TRANSPORT_REMOTE || runtime_scope == RUNTIME_SCOPE_SYSTEM, -EOPNOTSUPP);
 285
 286         switch (transport) {
 287
 288         case BUS_TRANSPORT_LOCAL:
 289
 290                 switch (runtime_scope) {
 291
 292                 case RUNTIME_SCOPE_USER:
 293                         r = sd_bus_default_user(&bus);
 294                         break;
 295
 296                 case RUNTIME_SCOPE_SYSTEM:
 297                         if (sd_booted() <= 0)
 298                                 /* Print a friendly message when the local system is actually not running systemd as PID 1. */
 299                                 return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
 300                                                        "System has not been booted with systemd as init system (PID 1). Can't operate.");
 301                         r = sd_bus_default_system(&bus);
 302                         break;
 303
 304                 default:
 305                         assert_not_reached();
 306                 }
 307                 break;
 308
 309         case BUS_TRANSPORT_REMOTE:
 310                 r = sd_bus_open_system_remote(&bus, host);
 311                 break;
 312
 313         case BUS_TRANSPORT_MACHINE:
 314
 315                 switch (runtime_scope) {
 316
 317                 case RUNTIME_SCOPE_USER:
 318                         r = sd_bus_open_user_machine(&bus, host);
 319                         break;
 320
 321                 case RUNTIME_SCOPE_SYSTEM:
 322                         r = sd_bus_open_system_machine(&bus, host);
 323                         break;
 324
 325                 default:
 326                         assert_not_reached();
 327                 }
 328
 329                 break;
 330
 331         default:
 332                 assert_not_reached();
 333         }
 334         if (r < 0)
 335                 return r;
 336
 337         r = sd_bus_set_exit_on_disconnect(bus, true);
 338         if (r < 0)
 339                 return r;
 340
 341         *ret = TAKE_PTR(bus);
 342         return 0;
 343 }
 344
 345 int bus_connect_transport_systemd(BusTransport transport, const char *host, RuntimeScope runtime_scope, sd_bus **bus) {
 346         assert(transport >= 0);
 347         assert(transport < _BUS_TRANSPORT_MAX);
 348         assert(bus);
 349
 350         assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
 351         assert_return(transport == BUS_TRANSPORT_LOCAL || runtime_scope == RUNTIME_SCOPE_SYSTEM, -EOPNOTSUPP);
 352
 353         switch (transport) {
 354
 355         case BUS_TRANSPORT_LOCAL:
 356                 switch (runtime_scope) {
 357
 358                 case RUNTIME_SCOPE_USER:
 359                         return bus_connect_user_systemd(bus);
 360
 361                 case RUNTIME_SCOPE_SYSTEM:
 362                         if (sd_booted() <= 0)
 363                                 /* Print a friendly message when the local system is actually not running systemd as PID 1. */
 364                                 return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
 365                                                        "System has not been booted with systemd as init system (PID 1). Can't operate.");
 366                         return bus_connect_system_systemd(bus);
 367
 368                 default:
 369                         assert_not_reached();
 370                 }
 371
 372                 break;
 373
 374         case BUS_TRANSPORT_REMOTE:
 375                 return sd_bus_open_system_remote(bus, host);
 376
 377         case BUS_TRANSPORT_MACHINE:
 378                 return sd_bus_open_system_machine(bus, host);
 379
 380         default:
 381                 assert_not_reached();
 382         }
 383 }
 384
 385 /**
 386  * bus_path_encode_unique() - encode unique object path
 387  * @b: bus connection or NULL
 388  * @prefix: object path prefix
 389  * @sender_id: unique-name of client, or NULL
 390  * @external_id: external ID to be chosen by client, or NULL
 391  * @ret_path: storage for encoded object path pointer
 392  *
 393  * Whenever we provide a bus API that allows clients to create and manage
 394  * server-side objects, we need to provide a unique name for these objects. If
 395  * we let the server choose the name, we suffer from a race condition: If a
 396  * client creates an object asynchronously, it cannot destroy that object until
 397  * it received the method reply. It cannot know the name of the new object,
 398  * thus, it cannot destroy it. Furthermore, it enforces a round-trip.
 399  *
 400  * Therefore, many APIs allow the client to choose the unique name for newly
 401  * created objects. There're two problems to solve, though:
 402  *    1) Object names are usually defined via dbus object paths, which are
 403  *       usually globally namespaced. Therefore, multiple clients must be able
 404  *       to choose unique object names without interference.
 405  *    2) If multiple libraries share the same bus connection, they must be
 406  *       able to choose unique object names without interference.
 407  * The first problem is solved easily by prefixing a name with the
 408  * unique-bus-name of a connection. The server side must enforce this and
 409  * reject any other name. The second problem is solved by providing unique
 410  * suffixes from within sd-bus.
 411  *
 412  * This helper allows clients to create unique object-paths. It uses the
 413  * template '/prefix/sender_id/external_id' and returns the new path in
 414  * @ret_path (must be freed by the caller).
 415  * If @sender_id is NULL, the unique-name of @b is used. If @external_id is
 416  * NULL, this function allocates a unique suffix via @b (by requesting a new
 417  * cookie). If both @sender_id and @external_id are given, @b can be passed as
 418  * NULL.
 419  *
 420  * Returns: 0 on success, negative error code on failure.
 421  */
 422 int bus_path_encode_unique(sd_bus *b, const char *prefix, const char *sender_id, const char *external_id, char **ret_path) {
 423         _cleanup_free_ char *sender_label = NULL, *external_label = NULL;
 424         char external_buf[DECIMAL_STR_MAX(uint64_t)], *p;
 425         int r;
 426
 427         assert_return(b || (sender_id && external_id), -EINVAL);
 428         assert_return(sd_bus_object_path_is_valid(prefix), -EINVAL);
 429         assert_return(ret_path, -EINVAL);
 430
 431         if (!sender_id) {
 432                 r = sd_bus_get_unique_name(b, &sender_id);
 433                 if (r < 0)
 434                         return r;
 435         }
 436
 437         if (!external_id) {
 438                 xsprintf(external_buf, "%"PRIu64, ++b->cookie);
 439                 external_id = external_buf;
 440         }
 441
 442         sender_label = bus_label_escape(sender_id);
 443         if (!sender_label)
 444                 return -ENOMEM;
 445
 446         external_label = bus_label_escape(external_id);
 447         if (!external_label)
 448                 return -ENOMEM;
 449
 450         p = path_join(prefix, sender_label, external_label);
 451         if (!p)
 452                 return -ENOMEM;
 453
 454         *ret_path = p;
 455         return 0;
 456 }
 457
 458 /**
 459  * bus_path_decode_unique() - decode unique object path
 460  * @path: object path to decode
 461  * @prefix: object path prefix
 462  * @ret_sender: output parameter for sender-id label
 463  * @ret_external: output parameter for external-id label
 464  *
 465  * This does the reverse of bus_path_encode_unique() (see its description for
 466  * details). Both trailing labels, sender-id and external-id, are unescaped and
 467  * returned in the given output parameters (the caller must free them).
 468  *
 469  * Note that this function returns 0 if the path does not match the template
 470  * (see bus_path_encode_unique()), 1 if it matched.
 471  *
 472  * Returns: Negative error code on failure, 0 if the given object path does not
 473  *          match the template (return parameters are set to NULL), 1 if it was
 474  *          parsed successfully (return parameters contain allocated labels).
 475  */
 476 int bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external) {
 477         const char *p, *q;
 478         char *sender, *external;
 479
 480         assert(sd_bus_object_path_is_valid(path));
 481         assert(sd_bus_object_path_is_valid(prefix));
 482         assert(ret_sender);
 483         assert(ret_external);
 484
 485         p = object_path_startswith(path, prefix);
 486         if (!p) {
 487                 *ret_sender = NULL;
 488                 *ret_external = NULL;
 489                 return 0;
 490         }
 491
 492         q = strchr(p, '/');
 493         if (!q) {
 494                 *ret_sender = NULL;
 495                 *ret_external = NULL;
 496                 return 0;
 497         }
 498
 499         sender = bus_label_unescape_n(p, q - p);
 500         external = bus_label_unescape(q + 1);
 501         if (!sender || !external) {
 502                 free(sender);
 503                 free(external);
 504                 return -ENOMEM;
 505         }
 506
 507         *ret_sender = sender;
 508         *ret_external = external;
 509         return 1;
 510 }
 511
 512 int bus_track_add_name_many(sd_bus_track *t, char **l) {
 513         int r = 0;
 514
 515         assert(t);
 516
 517         /* Continues adding after failure, and returns the first failure. */
 518
 519         STRV_FOREACH(i, l)
 520                 RET_GATHER(r, sd_bus_track_add_name(t, *i));
 521         return r;
 522 }
 523
 524 int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description) {
 525         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 526         const char *e;
 527         int r;
 528
 529         assert(ret);
 530
 531         /* Match like sd_bus_open_system(), but with the "watch_bind" feature and the Connected() signal
 532          * turned on. */
 533
 534         r = sd_bus_new(&bus);
 535         if (r < 0)
 536                 return r;
 537
 538         if (description) {
 539                 r = sd_bus_set_description(bus, description);
 540                 if (r < 0)
 541                         return r;
 542         }
 543
 544         e = secure_getenv("DBUS_SYSTEM_BUS_ADDRESS");
 545         if (!e)
 546                 e = DEFAULT_SYSTEM_BUS_ADDRESS;
 547
 548         r = sd_bus_set_address(bus, e);
 549         if (r < 0)
 550                 return r;
 551
 552         r = sd_bus_set_bus_client(bus, true);
 553         if (r < 0)
 554                 return r;
 555
 556         r = sd_bus_negotiate_creds(bus, true, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS);
 557         if (r < 0)
 558                 return r;
 559
 560         r = sd_bus_set_watch_bind(bus, true);
 561         if (r < 0)
 562                 return r;
 563
 564         r = sd_bus_set_connected_signal(bus, true);
 565         if (r < 0)
 566                 return r;
 567
 568         r = sd_bus_start(bus);
 569         if (r < 0)
 570                 return r;
 571
 572         *ret = TAKE_PTR(bus);
 573
 574         return 0;
 575 }
 576
 577 int bus_reply_pair_array(sd_bus_message *m, char **l) {
 578         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 579         int r;
 580
 581         assert(m);
 582
 583         /* Reply to the specified message with a message containing a dictionary put together from the
 584          * specified strv */
 585
 586         r = sd_bus_message_new_method_return(m, &reply);
 587         if (r < 0)
 588                 return r;
 589
 590         r = sd_bus_message_open_container(reply, 'a', "{ss}");
 591         if (r < 0)
 592                 return r;
 593
 594         STRV_FOREACH_PAIR(k, v, l) {
 595                 r = sd_bus_message_append(reply, "{ss}", *k, *v);
 596                 if (r < 0)
 597                         return r;
 598         }
 599
 600         r = sd_bus_message_close_container(reply);
 601         if (r < 0)
 602                 return r;
 603
 604         return sd_bus_send(NULL, reply, NULL);
 605 }
 606
 607 static int method_dump_memory_state_by_fd(sd_bus_message *message, void *userdata, sd_bus_error *ret_error) {
 608         _cleanup_(memstream_done) MemStream m = {};
 609         _cleanup_free_ char *dump = NULL;
 610         _cleanup_close_ int fd = -EBADF;
 611         size_t dump_size;
 612         FILE *f;
 613         int r;
 614
 615         assert(message);
 616
 617         f = memstream_init(&m);
 618         if (!f)
 619                 return -ENOMEM;
 620
 621         r = RET_NERRNO(malloc_info(/* options= */ 0, f));
 622         if (r < 0)
 623                 return r;
 624
 625         r = memstream_finalize(&m, &dump, &dump_size);
 626         if (r < 0)
 627                 return r;
 628
 629         fd = acquire_data_fd(dump, dump_size, 0);
 630         if (fd < 0)
 631                 return fd;
 632
 633         r = sd_bus_reply_method_return(message, "h", fd);
 634         if (r < 0)
 635                 return r;
 636
 637         return 1; /* Stop further processing */
 638 }
 639
 640 /* The default install callback will fail and disconnect the bus if it cannot register the match, but this
 641  * is only a debug method, we definitely don't want to fail in case there's some permission issue. */
 642 static int dummy_install_callback(sd_bus_message *message, void *userdata, sd_bus_error *ret_error) {
 643         return 1;
 644 }
 645
 646 int bus_register_malloc_status(sd_bus *bus, const char *destination) {
 647         const char *match;
 648         int r;
 649
 650         assert(bus);
 651         assert(!isempty(destination));
 652
 653         match = strjoina("type='method_call',"
 654                          "interface='org.freedesktop.MemoryAllocation1',"
 655                          "path='/org/freedesktop/MemoryAllocation1',"
 656                          "destination='", destination, "',",
 657                          "member='GetMallocInfo'");
 658
 659         r = sd_bus_add_match_async(bus, NULL, match, method_dump_memory_state_by_fd, dummy_install_callback, NULL);
 660         if (r < 0)
 661                 return log_debug_errno(r, "Failed to subscribe to GetMallocInfo() calls on MemoryAllocation1 interface: %m");
 662
 663         return 0;
 664 }
 665
 666 static void bus_message_unref_wrapper(void *m) {
 667         sd_bus_message_unref(m);
 668 }
 669
 670 const struct hash_ops bus_message_hash_ops = {
 671         .hash = trivial_hash_func,
 672         .compare = trivial_compare_func,
 673         .free_value = bus_message_unref_wrapper,
 674 };
 675
 676 int bus_message_append_string_set(sd_bus_message *m, Set *set) {
 677         const char *s;
 678         int r;
 679
 680         assert(m);
 681
 682         r = sd_bus_message_open_container(m, 'a', "s");
 683         if (r < 0)
 684                 return r;
 685
 686         SET_FOREACH(s, set) {
 687                 r = sd_bus_message_append(m, "s", s);
 688                 if (r < 0)
 689                         return r;
 690         }
 691
 692         return sd_bus_message_close_container(m);
 693 }
 694
 695 int bus_property_get_string_set(
 696                 sd_bus *bus,
 697                 const char *path,
 698                 const char *interface,
 699                 const char *property,
 700                 sd_bus_message *reply,
 701                 void *userdata,
 702                 sd_bus_error *error) {
 703
 704         Set **s = ASSERT_PTR(userdata);
 705
 706         assert(bus);
 707         assert(property);
 708         assert(reply);
 709
 710         return bus_message_append_string_set(reply, *s);
 711 }