src/dbus-common.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <assert.h>
  23 #include <sys/socket.h>
  24 #include <errno.h>
  25 #include <unistd.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <dbus/dbus.h>
  29 #include <string.h>
  30
  31 #include "log.h"
  32 #include "dbus-common.h"
  33 #include "util.h"
  34 #include "def.h"
  35 #include "strv.h"
  36
  37 int bus_check_peercred(DBusConnection *c) {
  38         int fd;
  39         struct ucred ucred;
  40         socklen_t l;
  41
  42         assert(c);
  43
  44         assert_se(dbus_connection_get_unix_fd(c, &fd));
  45
  46         l = sizeof(struct ucred);
  47         if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &l) < 0) {
  48                 log_error("SO_PEERCRED failed: %m");
  49                 return -errno;
  50         }
  51
  52         if (l != sizeof(struct ucred)) {
  53                 log_error("SO_PEERCRED returned wrong size.");
  54                 return -E2BIG;
  55         }
  56
  57         if (ucred.uid != 0)
  58                 return -EPERM;
  59
  60         return 1;
  61 }
  62
  63 static int sync_auth(DBusConnection *bus, DBusError *error) {
  64         usec_t begin, tstamp;
  65
  66         assert(bus);
  67
  68         /* This complexity should probably move into D-Bus itself:
  69          *
  70          * https://bugs.freedesktop.org/show_bug.cgi?id=35189 */
  71
  72         begin = tstamp = now(CLOCK_MONOTONIC);
  73         for (;;) {
  74
  75                 if (tstamp > begin + DEFAULT_TIMEOUT_USEC)
  76                         break;
  77
  78                 if (dbus_connection_get_is_authenticated(bus))
  79                         break;
  80
  81                 if (!dbus_connection_read_write_dispatch(bus, ((begin + DEFAULT_TIMEOUT_USEC - tstamp) + USEC_PER_MSEC - 1) / USEC_PER_MSEC))
  82                         break;
  83
  84                 tstamp = now(CLOCK_MONOTONIC);
  85         }
  86
  87         if (!dbus_connection_get_is_connected(bus)) {
  88                 dbus_set_error_const(error, DBUS_ERROR_NO_SERVER, "Connection terminated during authentication.");
  89                 return -ECONNREFUSED;
  90         }
  91
  92         if (!dbus_connection_get_is_authenticated(bus)) {
  93                 dbus_set_error_const(error, DBUS_ERROR_TIMEOUT, "Failed to authenticate in time.");
  94                 return -EACCES;
  95         }
  96
  97         return 0;
  98 }
  99
 100 int bus_connect(DBusBusType t, DBusConnection **_bus, bool *private, DBusError *error) {
 101         DBusConnection *bus;
 102         int r;
 103
 104         assert(_bus);
 105
 106         /* If we are root, then let's not go via the bus */
 107         if (geteuid() == 0 && t == DBUS_BUS_SYSTEM) {
 108
 109                 if (!(bus = dbus_connection_open_private("unix:path=/run/systemd/private", error))) {
 110 #ifndef LEGACY
 111                         dbus_error_free(error);
 112
 113                         /* Retry with the pre v21 socket name, to ease upgrades */
 114                         if (!(bus = dbus_connection_open_private("unix:abstract=/org/freedesktop/systemd1/private", error)))
 115 #endif
 116                                 return -EIO;
 117                 }
 118
 119                 dbus_connection_set_exit_on_disconnect(bus, FALSE);
 120
 121                 if (bus_check_peercred(bus) < 0) {
 122                         dbus_connection_close(bus);
 123                         dbus_connection_unref(bus);
 124
 125                         dbus_set_error_const(error, DBUS_ERROR_ACCESS_DENIED, "Failed to verify owner of bus.");
 126                         return -EACCES;
 127                 }
 128
 129                 if (private)
 130                         *private = true;
 131
 132         } else {
 133                 if (!(bus = dbus_bus_get_private(t, error)))
 134                         return -EIO;
 135
 136                 dbus_connection_set_exit_on_disconnect(bus, FALSE);
 137
 138                 if (private)
 139                         *private = false;
 140         }
 141
 142         if ((r = sync_auth(bus, error)) < 0) {
 143                 dbus_connection_close(bus);
 144                 dbus_connection_unref(bus);
 145                 return r;
 146         }
 147
 148         *_bus = bus;
 149         return 0;
 150 }
 151
 152 int bus_connect_system_ssh(const char *user, const char *host, DBusConnection **_bus, DBusError *error) {
 153         DBusConnection *bus;
 154         char *p = NULL;
 155         int r;
 156
 157         assert(_bus);
 158         assert(user || host);
 159
 160         if (user && host)
 161                 asprintf(&p, "exec:path=ssh,argv1=-xT,argv2=%s@%s,argv3=systemd-stdio-bridge", user, host);
 162         else if (user)
 163                 asprintf(&p, "exec:path=ssh,argv1=-xT,argv2=%s@localhost,argv3=systemd-stdio-bridge", user);
 164         else if (host)
 165                 asprintf(&p, "exec:path=ssh,argv1=-xT,argv2=%s,argv3=systemd-stdio-bridge", host);
 166
 167         if (!p) {
 168                 dbus_set_error_const(error, DBUS_ERROR_NO_MEMORY, NULL);
 169                 return -ENOMEM;
 170         }
 171
 172         bus = dbus_connection_open_private(p, error);
 173         free(p);
 174
 175         if (!bus)
 176                 return -EIO;
 177
 178         dbus_connection_set_exit_on_disconnect(bus, FALSE);
 179
 180         if ((r = sync_auth(bus, error)) < 0) {
 181                 dbus_connection_close(bus);
 182                 dbus_connection_unref(bus);
 183                 return r;
 184         }
 185
 186         if (!dbus_bus_register(bus, error)) {
 187                 dbus_connection_close(bus);
 188                 dbus_connection_unref(bus);
 189                 return r;
 190         }
 191
 192         *_bus = bus;
 193         return 0;
 194 }
 195
 196 int bus_connect_system_polkit(DBusConnection **_bus, DBusError *error) {
 197         DBusConnection *bus;
 198         int r;
 199
 200         assert(_bus);
 201
 202         /* Don't bother with PolicyKit if we are root */
 203         if (geteuid() == 0)
 204                 return bus_connect(DBUS_BUS_SYSTEM, _bus, NULL, error);
 205
 206         if (!(bus = dbus_connection_open_private("exec:path=pkexec,argv1=" SYSTEMD_STDIO_BRIDGE_BINARY_PATH, error)))
 207                 return -EIO;
 208
 209         dbus_connection_set_exit_on_disconnect(bus, FALSE);
 210
 211         if ((r = sync_auth(bus, error)) < 0) {
 212                 dbus_connection_close(bus);
 213                 dbus_connection_unref(bus);
 214                 return r;
 215         }
 216
 217         if (!dbus_bus_register(bus, error)) {
 218                 dbus_connection_close(bus);
 219                 dbus_connection_unref(bus);
 220                 return r;
 221         }
 222
 223         *_bus = bus;
 224         return 0;
 225 }
 226
 227 const char *bus_error_message(const DBusError *error) {
 228         assert(error);
 229
 230         /* Sometimes the D-Bus server is a little bit too verbose with
 231          * its error messages, so let's override them here */
 232         if (dbus_error_has_name(error, DBUS_ERROR_ACCESS_DENIED))
 233                 return "Access denied";
 234
 235         return error->message;
 236 }
 237
 238 DBusHandlerResult bus_default_message_handler(
 239                 DBusConnection *c,
 240                 DBusMessage *message,
 241                 const char *introspection,
 242                 const char *interfaces,
 243                 const BusProperty *properties) {
 244
 245         DBusError error;
 246         DBusMessage *reply = NULL;
 247         int r;
 248
 249         assert(c);
 250         assert(message);
 251
 252         dbus_error_init(&error);
 253
 254         if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Introspectable", "Introspect") && introspection) {
 255
 256                 if (!(reply = dbus_message_new_method_return(message)))
 257                         goto oom;
 258
 259                 if (!dbus_message_append_args(reply, DBUS_TYPE_STRING, &introspection, DBUS_TYPE_INVALID))
 260                         goto oom;
 261
 262         } else if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Properties", "Get") && properties) {
 263                 const char *interface, *property;
 264                 const BusProperty *p;
 265
 266                 if (!dbus_message_get_args(
 267                             message,
 268                             &error,
 269                             DBUS_TYPE_STRING, &interface,
 270                             DBUS_TYPE_STRING, &property,
 271                             DBUS_TYPE_INVALID))
 272                         return bus_send_error_reply(c, message, &error, -EINVAL);
 273
 274                 for (p = properties; p->property; p++)
 275                         if (streq(p->interface, interface) && streq(p->property, property))
 276                                 break;
 277
 278                 if (p->property) {
 279                         DBusMessageIter iter, sub;
 280
 281                         if (!(reply = dbus_message_new_method_return(message)))
 282                                 goto oom;
 283
 284                         dbus_message_iter_init_append(reply, &iter);
 285
 286                         if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_VARIANT, p->signature, &sub))
 287                                 goto oom;
 288
 289                         if ((r = p->append(&sub, property, (void*) p->data)) < 0) {
 290
 291                                 if (r == -ENOMEM)
 292                                         goto oom;
 293
 294                                 dbus_message_unref(reply);
 295                                 return bus_send_error_reply(c, message, NULL, r);
 296                         }
 297
 298                         if (!dbus_message_iter_close_container(&iter, &sub))
 299                                 goto oom;
 300                 } else {
 301                         if (!nulstr_contains(interfaces, interface))
 302                                 dbus_set_error_const(&error, DBUS_ERROR_UNKNOWN_INTERFACE, "Unknown interface");
 303                         else
 304                                 dbus_set_error_const(&error, DBUS_ERROR_UNKNOWN_PROPERTY, "Unknown property");
 305
 306                         return bus_send_error_reply(c, message, &error, -EINVAL);
 307                 }
 308
 309         } else if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Properties", "GetAll") && properties) {
 310                 const char *interface;
 311                 const BusProperty *p;
 312                 DBusMessageIter iter, sub, sub2, sub3;
 313
 314                 if (!dbus_message_get_args(
 315                             message,
 316                             &error,
 317                             DBUS_TYPE_STRING, &interface,
 318                             DBUS_TYPE_INVALID))
 319                         return bus_send_error_reply(c, message, &error, -EINVAL);
 320
 321                 if (interface[0] && !nulstr_contains(interfaces, interface)) {
 322                         dbus_set_error_const(&error, DBUS_ERROR_UNKNOWN_INTERFACE, "Unknown interface");
 323                         return bus_send_error_reply(c, message, &error, -EINVAL);
 324                 }
 325
 326                 if (!(reply = dbus_message_new_method_return(message)))
 327                         goto oom;
 328
 329                 dbus_message_iter_init_append(reply, &iter);
 330
 331                 if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, "{sv}", &sub))
 332                         goto oom;
 333
 334                 for (p = properties; p->property; p++) {
 335                         if (interface[0] && !streq(p->interface, interface))
 336                                 continue;
 337
 338                         if (!dbus_message_iter_open_container(&sub, DBUS_TYPE_DICT_ENTRY, NULL, &sub2) ||
 339                             !dbus_message_iter_append_basic(&sub2, DBUS_TYPE_STRING, &p->property) ||
 340                             !dbus_message_iter_open_container(&sub2, DBUS_TYPE_VARIANT, p->signature, &sub3))
 341                                 goto oom;
 342
 343                         if ((r = p->append(&sub3, p->property, (void*) p->data)) < 0) {
 344
 345                                 if (r == -ENOMEM)
 346                                         goto oom;
 347
 348                                 dbus_message_unref(reply);
 349                                 return bus_send_error_reply(c, message, NULL, r);
 350                         }
 351
 352                         if (!dbus_message_iter_close_container(&sub2, &sub3) ||
 353                             !dbus_message_iter_close_container(&sub, &sub2))
 354                                 goto oom;
 355                 }
 356
 357                 if (!dbus_message_iter_close_container(&iter, &sub))
 358                         goto oom;
 359
 360         } else if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Properties", "Set") && properties) {
 361                 const char *interface, *property;
 362                 DBusMessageIter iter;
 363                 const BusProperty *p;
 364
 365                 if (!dbus_message_iter_init(message, &iter) ||
 366                     dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_STRING)
 367                         return bus_send_error_reply(c, message, NULL, -EINVAL);
 368
 369                 dbus_message_iter_get_basic(&iter, &interface);
 370
 371                 if (!dbus_message_iter_next(&iter) ||
 372                     dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_STRING)
 373                         return bus_send_error_reply(c, message, NULL, -EINVAL);
 374
 375                 dbus_message_iter_get_basic(&iter, &property);
 376
 377                 if (!dbus_message_iter_next(&iter) ||
 378                     dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT ||
 379                     dbus_message_iter_has_next(&iter))
 380                         return bus_send_error_reply(c, message, NULL, -EINVAL);
 381
 382                 for (p = properties; p->property; p++)
 383                         if (streq(p->interface, interface) && streq(p->property, property))
 384                                 break;
 385
 386                 if (p->set) {
 387                         DBusMessageIter sub;
 388                         char *sig;
 389
 390                         dbus_message_iter_recurse(&iter, &sub);
 391
 392                         if (!(sig = dbus_message_iter_get_signature(&sub)))
 393                                 goto oom;
 394
 395                         if (!streq(sig, p->signature)) {
 396                                 dbus_free(sig);
 397                                 return bus_send_error_reply(c, message, NULL, -EINVAL);
 398                         }
 399
 400                         dbus_free(sig);
 401
 402                         if ((r = p->set(&sub, property)) < 0) {
 403                                 if (r == -ENOMEM)
 404                                         goto oom;
 405                                 return bus_send_error_reply(c, message, NULL, r);
 406                         }
 407
 408                         if (!(reply = dbus_message_new_method_return(message)))
 409                                 goto oom;
 410                 } else {
 411                         if (p->property)
 412                                 dbus_set_error_const(&error, DBUS_ERROR_PROPERTY_READ_ONLY, "Property read-only");
 413                         else if (!nulstr_contains(interfaces, interface))
 414                                 dbus_set_error_const(&error, DBUS_ERROR_UNKNOWN_INTERFACE, "Unknown interface");
 415                         else
 416                                 dbus_set_error_const(&error, DBUS_ERROR_UNKNOWN_PROPERTY, "Unknown property");
 417
 418                         return bus_send_error_reply(c, message, &error, -EINVAL);
 419                 }
 420
 421         } else if (!nulstr_contains(interfaces, dbus_message_get_interface(message))) {
 422                 dbus_set_error_const(&error, DBUS_ERROR_UNKNOWN_INTERFACE, "Unknown interface");
 423                 return bus_send_error_reply(c, message, &error, -EINVAL);
 424         }
 425
 426         if (reply) {
 427                 if (!dbus_connection_send(c, reply, NULL))
 428                         goto oom;
 429
 430                 dbus_message_unref(reply);
 431                 return DBUS_HANDLER_RESULT_HANDLED;
 432         }
 433
 434         return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 435
 436 oom:
 437         if (reply)
 438                 dbus_message_unref(reply);
 439
 440         dbus_error_free(&error);
 441
 442         return DBUS_HANDLER_RESULT_NEED_MEMORY;
 443 }
 444
 445 int bus_property_append_string(DBusMessageIter *i, const char *property, void *data) {
 446         const char *t = data;
 447
 448         assert(i);
 449         assert(property);
 450
 451         if (!t)
 452                 t = "";
 453
 454         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_STRING, &t))
 455                 return -ENOMEM;
 456
 457         return 0;
 458 }
 459
 460 int bus_property_append_strv(DBusMessageIter *i, const char *property, void *data) {
 461         DBusMessageIter sub;
 462         char **t = data;
 463
 464         assert(i);
 465         assert(property);
 466
 467         if (!dbus_message_iter_open_container(i, DBUS_TYPE_ARRAY, "s", &sub))
 468                 return -ENOMEM;
 469
 470         STRV_FOREACH(t, t)
 471                 if (!dbus_message_iter_append_basic(&sub, DBUS_TYPE_STRING, t))
 472                         return -ENOMEM;
 473
 474         if (!dbus_message_iter_close_container(i, &sub))
 475                 return -ENOMEM;
 476
 477         return 0;
 478 }
 479
 480 int bus_property_append_bool(DBusMessageIter *i, const char *property, void *data) {
 481         bool *b = data;
 482         dbus_bool_t db;
 483
 484         assert(i);
 485         assert(property);
 486         assert(b);
 487
 488         db = *b;
 489
 490         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_BOOLEAN, &db))
 491                 return -ENOMEM;
 492
 493         return 0;
 494 }
 495
 496 int bus_property_append_uint64(DBusMessageIter *i, const char *property, void *data) {
 497         assert(i);
 498         assert(property);
 499         assert(data);
 500
 501         /* Let's ensure that pid_t is actually 64bit, and hence this
 502          * function can be used for usec_t */
 503         assert_cc(sizeof(uint64_t) == sizeof(usec_t));
 504
 505         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_UINT64, data))
 506                 return -ENOMEM;
 507
 508         return 0;
 509 }
 510
 511 int bus_property_append_uint32(DBusMessageIter *i, const char *property, void *data) {
 512         assert(i);
 513         assert(property);
 514         assert(data);
 515
 516         /* Let's ensure that pid_t and mode_t is actually 32bit, and
 517          * hence this function can be used for pid_t/mode_t */
 518         assert_cc(sizeof(uint32_t) == sizeof(pid_t));
 519         assert_cc(sizeof(uint32_t) == sizeof(mode_t));
 520         assert_cc(sizeof(uint32_t) == sizeof(unsigned));
 521
 522         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_UINT32, data))
 523                 return -ENOMEM;
 524
 525         return 0;
 526 }
 527
 528 int bus_property_append_int32(DBusMessageIter *i, const char *property, void *data) {
 529         assert(i);
 530         assert(property);
 531         assert(data);
 532
 533         assert_cc(sizeof(int32_t) == sizeof(int));
 534
 535         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_INT32, data))
 536                 return -ENOMEM;
 537
 538         return 0;
 539 }
 540
 541 int bus_property_append_size(DBusMessageIter *i, const char *property, void *data) {
 542         uint64_t u;
 543
 544         assert(i);
 545         assert(property);
 546         assert(data);
 547
 548         u = (uint64_t) *(size_t*) data;
 549
 550         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_UINT64, &u))
 551                 return -ENOMEM;
 552
 553         return 0;
 554 }
 555
 556 int bus_property_append_ul(DBusMessageIter *i, const char *property, void *data) {
 557         uint64_t u;
 558
 559         assert(i);
 560         assert(property);
 561         assert(data);
 562
 563         u = (uint64_t) *(unsigned long*) data;
 564
 565         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_UINT64, &u))
 566                 return -ENOMEM;
 567
 568         return 0;
 569 }
 570
 571 const char *bus_errno_to_dbus(int error) {
 572
 573         switch(error) {
 574
 575         case -EINVAL:
 576                 return DBUS_ERROR_INVALID_ARGS;
 577
 578         case -ENOMEM:
 579                 return DBUS_ERROR_NO_MEMORY;
 580
 581         case -EPERM:
 582         case -EACCES:
 583                 return DBUS_ERROR_ACCESS_DENIED;
 584
 585         case -ESRCH:
 586                 return DBUS_ERROR_UNIX_PROCESS_ID_UNKNOWN;
 587
 588         case -ENOENT:
 589                 return DBUS_ERROR_FILE_NOT_FOUND;
 590
 591         case -EEXIST:
 592                 return DBUS_ERROR_FILE_EXISTS;
 593
 594         case -ETIMEDOUT:
 595         case -ETIME:
 596                 return DBUS_ERROR_TIMEOUT;
 597
 598         case -EIO:
 599                 return DBUS_ERROR_IO_ERROR;
 600
 601         case -ENETRESET:
 602         case -ECONNABORTED:
 603         case -ECONNRESET:
 604                 return DBUS_ERROR_DISCONNECTED;
 605         }
 606
 607         return DBUS_ERROR_FAILED;
 608 }
 609
 610 DBusHandlerResult bus_send_error_reply(DBusConnection *c, DBusMessage *message, DBusError *berror, int error) {
 611         DBusMessage *reply = NULL;
 612         const char *name, *text;
 613
 614         if (berror && dbus_error_is_set(berror)) {
 615                 name = berror->name;
 616                 text = berror->message;
 617         } else {
 618                 name = bus_errno_to_dbus(error);
 619                 text = strerror(-error);
 620         }
 621
 622         if (!(reply = dbus_message_new_error(message, name, text)))
 623                 goto oom;
 624
 625         if (!dbus_connection_send(c, reply, NULL))
 626                 goto oom;
 627
 628         dbus_message_unref(reply);
 629
 630         if (berror)
 631                 dbus_error_free(berror);
 632
 633         return DBUS_HANDLER_RESULT_HANDLED;
 634
 635 oom:
 636         if (reply)
 637                 dbus_message_unref(reply);
 638
 639         if (berror)
 640                 dbus_error_free(berror);
 641
 642         return DBUS_HANDLER_RESULT_NEED_MEMORY;
 643 }
 644
 645 DBusMessage* bus_properties_changed_new(const char *path, const char *interface, const char *properties) {
 646         DBusMessage *m;
 647         DBusMessageIter iter, sub;
 648         const char *i;
 649
 650         assert(interface);
 651         assert(properties);
 652
 653         if (!(m = dbus_message_new_signal(path, "org.freedesktop.DBus.Properties", "PropertiesChanged")))
 654                 goto oom;
 655
 656         dbus_message_iter_init_append(m, &iter);
 657
 658         /* We won't send any property values, since they might be
 659          * large and sometimes not cheap to generated */
 660
 661         if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &interface) ||
 662             !dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, "{sv}", &sub) ||
 663             !dbus_message_iter_close_container(&iter, &sub) ||
 664             !dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, "s", &sub))
 665                 goto oom;
 666
 667         NULSTR_FOREACH(i, properties)
 668                 if (!dbus_message_iter_append_basic(&sub, DBUS_TYPE_STRING, &i))
 669                         goto oom;
 670
 671         if (!dbus_message_iter_close_container(&iter, &sub))
 672                 goto oom;
 673
 674         return m;
 675
 676 oom:
 677         if (m)
 678                 dbus_message_unref(m);
 679
 680         return NULL;
 681 }