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         bool exiting = false;
 103         int r, code;
 104
 105         assert(e);
 106         assert(bus);
 107         assert(name);
 108
 109         for (;;) {
 110                 bool idle;
 111
 112                 r = sd_event_get_state(e);
 113                 if (r < 0)
 114                         return r;
 115                 if (r == SD_EVENT_FINISHED)
 116                         break;
 117
 118                 if (check_idle)
 119                         idle = check_idle(userdata);
 120                 else
 121                         idle = true;
 122
 123                 r = sd_event_run(e, exiting || !idle ? UINT64_MAX : timeout);
 124                 if (r < 0)
 125                         return r;
 126
 127                 if (r == 0 && !exiting && idle) {
 128                         /* Inform the service manager that we are going down, so that it will queue all
 129                          * further start requests, instead of assuming we are already running. */
 130                         sd_notify(false, "STOPPING=1");
 131
 132                         r = bus_async_unregister_and_exit(e, bus, name);
 133                         if (r < 0)
 134                                 return r;
 135
 136                         exiting = true;
 137                         continue;
 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                 bool user,
 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 || !user, -EOPNOTSUPP);
 284
 285         switch (transport) {
 286
 287         case BUS_TRANSPORT_LOCAL:
 288                 if (user)
 289                         r = sd_bus_default_user(&bus);
 290                 else {
 291                         if (sd_booted() <= 0)
 292                                 /* Print a friendly message when the local system is actually not running systemd as PID 1. */
 293                                 return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
 294                                                        "System has not been booted with systemd as init system (PID 1). Can't operate.");
 295                         r = sd_bus_default_system(&bus);
 296                 }
 297                 break;
 298
 299         case BUS_TRANSPORT_REMOTE:
 300                 r = sd_bus_open_system_remote(&bus, host);
 301                 break;
 302
 303         case BUS_TRANSPORT_MACHINE:
 304                 if (user)
 305                         r = sd_bus_open_user_machine(&bus, host);
 306                 else
 307                         r = sd_bus_open_system_machine(&bus, host);
 308                 break;
 309
 310         default:
 311                 assert_not_reached();
 312         }
 313         if (r < 0)
 314                 return r;
 315
 316         r = sd_bus_set_exit_on_disconnect(bus, true);
 317         if (r < 0)
 318                 return r;
 319
 320         *ret = TAKE_PTR(bus);
 321         return 0;
 322 }
 323
 324 int bus_connect_transport_systemd(BusTransport transport, const char *host, bool user, sd_bus **bus) {
 325         assert(transport >= 0);
 326         assert(transport < _BUS_TRANSPORT_MAX);
 327         assert(bus);
 328
 329         assert_return((transport == BUS_TRANSPORT_LOCAL) == !host, -EINVAL);
 330         assert_return(transport == BUS_TRANSPORT_LOCAL || !user, -EOPNOTSUPP);
 331
 332         switch (transport) {
 333
 334         case BUS_TRANSPORT_LOCAL:
 335                 if (user)
 336                         return bus_connect_user_systemd(bus);
 337
 338                 if (sd_booted() <= 0)
 339                         /* Print a friendly message when the local system is actually not running systemd as PID 1. */
 340                         return log_error_errno(SYNTHETIC_ERRNO(EHOSTDOWN),
 341                                                "System has not been booted with systemd as init system (PID 1). Can't operate.");
 342                 return bus_connect_system_systemd(bus);
 343
 344         case BUS_TRANSPORT_REMOTE:
 345                 return sd_bus_open_system_remote(bus, host);
 346
 347         case BUS_TRANSPORT_MACHINE:
 348                 return sd_bus_open_system_machine(bus, host);
 349
 350         default:
 351                 assert_not_reached();
 352         }
 353 }
 354
 355 /**
 356  * bus_path_encode_unique() - encode unique object path
 357  * @b: bus connection or NULL
 358  * @prefix: object path prefix
 359  * @sender_id: unique-name of client, or NULL
 360  * @external_id: external ID to be chosen by client, or NULL
 361  * @ret_path: storage for encoded object path pointer
 362  *
 363  * Whenever we provide a bus API that allows clients to create and manage
 364  * server-side objects, we need to provide a unique name for these objects. If
 365  * we let the server choose the name, we suffer from a race condition: If a
 366  * client creates an object asynchronously, it cannot destroy that object until
 367  * it received the method reply. It cannot know the name of the new object,
 368  * thus, it cannot destroy it. Furthermore, it enforces a round-trip.
 369  *
 370  * Therefore, many APIs allow the client to choose the unique name for newly
 371  * created objects. There're two problems to solve, though:
 372  *    1) Object names are usually defined via dbus object paths, which are
 373  *       usually globally namespaced. Therefore, multiple clients must be able
 374  *       to choose unique object names without interference.
 375  *    2) If multiple libraries share the same bus connection, they must be
 376  *       able to choose unique object names without interference.
 377  * The first problem is solved easily by prefixing a name with the
 378  * unique-bus-name of a connection. The server side must enforce this and
 379  * reject any other name. The second problem is solved by providing unique
 380  * suffixes from within sd-bus.
 381  *
 382  * This helper allows clients to create unique object-paths. It uses the
 383  * template '/prefix/sender_id/external_id' and returns the new path in
 384  * @ret_path (must be freed by the caller).
 385  * If @sender_id is NULL, the unique-name of @b is used. If @external_id is
 386  * NULL, this function allocates a unique suffix via @b (by requesting a new
 387  * cookie). If both @sender_id and @external_id are given, @b can be passed as
 388  * NULL.
 389  *
 390  * Returns: 0 on success, negative error code on failure.
 391  */
 392 int bus_path_encode_unique(sd_bus *b, const char *prefix, const char *sender_id, const char *external_id, char **ret_path) {
 393         _cleanup_free_ char *sender_label = NULL, *external_label = NULL;
 394         char external_buf[DECIMAL_STR_MAX(uint64_t)], *p;
 395         int r;
 396
 397         assert_return(b || (sender_id && external_id), -EINVAL);
 398         assert_return(sd_bus_object_path_is_valid(prefix), -EINVAL);
 399         assert_return(ret_path, -EINVAL);
 400
 401         if (!sender_id) {
 402                 r = sd_bus_get_unique_name(b, &sender_id);
 403                 if (r < 0)
 404                         return r;
 405         }
 406
 407         if (!external_id) {
 408                 xsprintf(external_buf, "%"PRIu64, ++b->cookie);
 409                 external_id = external_buf;
 410         }
 411
 412         sender_label = bus_label_escape(sender_id);
 413         if (!sender_label)
 414                 return -ENOMEM;
 415
 416         external_label = bus_label_escape(external_id);
 417         if (!external_label)
 418                 return -ENOMEM;
 419
 420         p = path_join(prefix, sender_label, external_label);
 421         if (!p)
 422                 return -ENOMEM;
 423
 424         *ret_path = p;
 425         return 0;
 426 }
 427
 428 /**
 429  * bus_path_decode_unique() - decode unique object path
 430  * @path: object path to decode
 431  * @prefix: object path prefix
 432  * @ret_sender: output parameter for sender-id label
 433  * @ret_external: output parameter for external-id label
 434  *
 435  * This does the reverse of bus_path_encode_unique() (see its description for
 436  * details). Both trailing labels, sender-id and external-id, are unescaped and
 437  * returned in the given output parameters (the caller must free them).
 438  *
 439  * Note that this function returns 0 if the path does not match the template
 440  * (see bus_path_encode_unique()), 1 if it matched.
 441  *
 442  * Returns: Negative error code on failure, 0 if the given object path does not
 443  *          match the template (return parameters are set to NULL), 1 if it was
 444  *          parsed successfully (return parameters contain allocated labels).
 445  */
 446 int bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external) {
 447         const char *p, *q;
 448         char *sender, *external;
 449
 450         assert(sd_bus_object_path_is_valid(path));
 451         assert(sd_bus_object_path_is_valid(prefix));
 452         assert(ret_sender);
 453         assert(ret_external);
 454
 455         p = object_path_startswith(path, prefix);
 456         if (!p) {
 457                 *ret_sender = NULL;
 458                 *ret_external = NULL;
 459                 return 0;
 460         }
 461
 462         q = strchr(p, '/');
 463         if (!q) {
 464                 *ret_sender = NULL;
 465                 *ret_external = NULL;
 466                 return 0;
 467         }
 468
 469         sender = bus_label_unescape_n(p, q - p);
 470         external = bus_label_unescape(q + 1);
 471         if (!sender || !external) {
 472                 free(sender);
 473                 free(external);
 474                 return -ENOMEM;
 475         }
 476
 477         *ret_sender = sender;
 478         *ret_external = external;
 479         return 1;
 480 }
 481
 482 int bus_track_add_name_many(sd_bus_track *t, char **l) {
 483         int r = 0;
 484
 485         assert(t);
 486
 487         /* Continues adding after failure, and returns the first failure. */
 488
 489         STRV_FOREACH(i, l) {
 490                 int k;
 491
 492                 k = sd_bus_track_add_name(t, *i);
 493                 if (k < 0 && r >= 0)
 494                         r = k;
 495         }
 496
 497         return r;
 498 }
 499
 500 int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description) {
 501         _cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
 502         const char *e;
 503         int r;
 504
 505         assert(ret);
 506
 507         /* Match like sd_bus_open_system(), but with the "watch_bind" feature and the Connected() signal
 508          * turned on. */
 509
 510         r = sd_bus_new(&bus);
 511         if (r < 0)
 512                 return r;
 513
 514         if (description) {
 515                 r = sd_bus_set_description(bus, description);
 516                 if (r < 0)
 517                         return r;
 518         }
 519
 520         e = secure_getenv("DBUS_SYSTEM_BUS_ADDRESS");
 521         if (!e)
 522                 e = DEFAULT_SYSTEM_BUS_ADDRESS;
 523
 524         r = sd_bus_set_address(bus, e);
 525         if (r < 0)
 526                 return r;
 527
 528         r = sd_bus_set_bus_client(bus, true);
 529         if (r < 0)
 530                 return r;
 531
 532         r = sd_bus_negotiate_creds(bus, true, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS);
 533         if (r < 0)
 534                 return r;
 535
 536         r = sd_bus_set_watch_bind(bus, true);
 537         if (r < 0)
 538                 return r;
 539
 540         r = sd_bus_set_connected_signal(bus, true);
 541         if (r < 0)
 542                 return r;
 543
 544         r = sd_bus_start(bus);
 545         if (r < 0)
 546                 return r;
 547
 548         *ret = TAKE_PTR(bus);
 549
 550         return 0;
 551 }
 552
 553 int bus_reply_pair_array(sd_bus_message *m, char **l) {
 554         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 555         int r;
 556
 557         assert(m);
 558
 559         /* Reply to the specified message with a message containing a dictionary put together from the
 560          * specified strv */
 561
 562         r = sd_bus_message_new_method_return(m, &reply);
 563         if (r < 0)
 564                 return r;
 565
 566         r = sd_bus_message_open_container(reply, 'a', "{ss}");
 567         if (r < 0)
 568                 return r;
 569
 570         STRV_FOREACH_PAIR(k, v, l) {
 571                 r = sd_bus_message_append(reply, "{ss}", *k, *v);
 572                 if (r < 0)
 573                         return r;
 574         }
 575
 576         r = sd_bus_message_close_container(reply);
 577         if (r < 0)
 578                 return r;
 579
 580         return sd_bus_send(NULL, reply, NULL);
 581 }
 582
 583 static int method_dump_memory_state_by_fd(sd_bus_message *message, void *userdata, sd_bus_error *ret_error) {
 584         _cleanup_free_ char *dump = NULL; /* keep this above dump_file, so that it's freed after */
 585         _cleanup_fclose_ FILE *dump_file = NULL;
 586         _cleanup_close_ int fd = -EBADF;
 587         size_t dump_size;
 588         int r;
 589
 590         assert(message);
 591
 592         dump_file = open_memstream(&dump, &dump_size);
 593         if (!dump_file)
 594                 return -ENOMEM;
 595
 596         r = RET_NERRNO(malloc_info(/* options= */ 0, dump_file));
 597         if (r < 0)
 598                 return r;
 599
 600         dump_file = safe_fclose(dump_file);
 601
 602         fd = acquire_data_fd(dump, dump_size, 0);
 603         if (fd < 0)
 604                 return fd;
 605
 606         r = sd_bus_reply_method_return(message, "h", fd);
 607         if (r < 0)
 608                 return r;
 609
 610         return 1; /* Stop further processing */
 611 }
 612
 613 /* The default install callback will fail and disconnect the bus if it cannot register the match, but this
 614  * is only a debug method, we definitely don't want to fail in case there's some permission issue. */
 615 static int dummy_install_callback(sd_bus_message *message, void *userdata, sd_bus_error *ret_error) {
 616         return 1;
 617 }
 618
 619 int bus_register_malloc_status(sd_bus *bus, const char *destination) {
 620         const char *match;
 621         int r;
 622
 623         assert(bus);
 624         assert(!isempty(destination));
 625
 626         match = strjoina("type='method_call',"
 627                          "interface='org.freedesktop.MemoryAllocation1',"
 628                          "path='/org/freedesktop/MemoryAllocation1',"
 629                          "destination='", destination, "',",
 630                          "member='GetMallocInfo'");
 631
 632         r = sd_bus_add_match_async(bus, NULL, match, method_dump_memory_state_by_fd, dummy_install_callback, NULL);
 633         if (r < 0)
 634                 return log_debug_errno(r, "Failed to subscribe to GetMallocInfo() calls on MemoryAllocation1 interface: %m");
 635
 636         return 0;
 637 }
 638
 639 static void bus_message_unref_wrapper(void *m) {
 640         sd_bus_message_unref(m);
 641 }
 642
 643 const struct hash_ops bus_message_hash_ops = {
 644         .hash = trivial_hash_func,
 645         .compare = trivial_compare_func,
 646         .free_value = bus_message_unref_wrapper,
 647 };