src/libelogind/sd-bus/bus-convenience.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2013 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include "bus-internal.h"
  21 #include "bus-message.h"
  22 #include "bus-signature.h"
  23 #include "bus-type.h"
  24 #include "bus-util.h"
  25 #include "string-util.h"
  26
  27 _public_ int sd_bus_emit_signal(
  28                 sd_bus *bus,
  29                 const char *path,
  30                 const char *interface,
  31                 const char *member,
  32                 const char *types, ...) {
  33
  34         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  35         int r;
  36
  37         assert_return(bus, -EINVAL);
  38         assert_return(!bus_pid_changed(bus), -ECHILD);
  39
  40         if (!BUS_IS_OPEN(bus->state))
  41                 return -ENOTCONN;
  42
  43         r = sd_bus_message_new_signal(bus, &m, path, interface, member);
  44         if (r < 0)
  45                 return r;
  46
  47         if (!isempty(types)) {
  48                 va_list ap;
  49
  50                 va_start(ap, types);
  51                 r = sd_bus_message_appendv(m, types, ap);
  52                 va_end(ap);
  53                 if (r < 0)
  54                         return r;
  55         }
  56
  57         return sd_bus_send(bus, m, NULL);
  58 }
  59
  60 #if 0 /// UNNEEDED by elogind
  61 _public_ int sd_bus_call_method_async(
  62                 sd_bus *bus,
  63                 sd_bus_slot **slot,
  64                 const char *destination,
  65                 const char *path,
  66                 const char *interface,
  67                 const char *member,
  68                 sd_bus_message_handler_t callback,
  69                 void *userdata,
  70                 const char *types, ...) {
  71
  72         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
  73         int r;
  74
  75         assert_return(bus, -EINVAL);
  76         assert_return(!bus_pid_changed(bus), -ECHILD);
  77
  78         if (!BUS_IS_OPEN(bus->state))
  79                 return -ENOTCONN;
  80
  81         r = sd_bus_message_new_method_call(bus, &m, destination, path, interface, member);
  82         if (r < 0)
  83                 return r;
  84
  85         if (!isempty(types)) {
  86                 va_list ap;
  87
  88                 va_start(ap, types);
  89                 r = sd_bus_message_appendv(m, types, ap);
  90                 va_end(ap);
  91                 if (r < 0)
  92                         return r;
  93         }
  94
  95         return sd_bus_call_async(bus, slot, m, callback, userdata, 0);
  96 }
  97 #endif // 0
  98
  99 _public_ int sd_bus_call_method(
 100                 sd_bus *bus,
 101                 const char *destination,
 102                 const char *path,
 103                 const char *interface,
 104                 const char *member,
 105                 sd_bus_error *error,
 106                 sd_bus_message **reply,
 107                 const char *types, ...) {
 108
 109         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 110         int r;
 111
 112         bus_assert_return(bus, -EINVAL, error);
 113         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 114
 115         if (!BUS_IS_OPEN(bus->state)) {
 116                 r = -ENOTCONN;
 117                 goto fail;
 118         }
 119
 120         r = sd_bus_message_new_method_call(bus, &m, destination, path, interface, member);
 121         if (r < 0)
 122                 goto fail;
 123
 124         if (!isempty(types)) {
 125                 va_list ap;
 126
 127                 va_start(ap, types);
 128                 r = sd_bus_message_appendv(m, types, ap);
 129                 va_end(ap);
 130                 if (r < 0)
 131                         goto fail;
 132         }
 133
 134         return sd_bus_call(bus, m, 0, error, reply);
 135
 136 fail:
 137         return sd_bus_error_set_errno(error, r);
 138 }
 139
 140 _public_ int sd_bus_reply_method_return(
 141                 sd_bus_message *call,
 142                 const char *types, ...) {
 143
 144         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 145         int r;
 146
 147         assert_return(call, -EINVAL);
 148         assert_return(call->sealed, -EPERM);
 149         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 150         assert_return(call->bus, -EINVAL);
 151         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 152
 153         if (!BUS_IS_OPEN(call->bus->state))
 154                 return -ENOTCONN;
 155
 156         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 157                 return 0;
 158
 159         r = sd_bus_message_new_method_return(call, &m);
 160         if (r < 0)
 161                 return r;
 162
 163         if (!isempty(types)) {
 164                 va_list ap;
 165
 166                 va_start(ap, types);
 167                 r = sd_bus_message_appendv(m, types, ap);
 168                 va_end(ap);
 169                 if (r < 0)
 170                         return r;
 171         }
 172
 173         return sd_bus_send(call->bus, m, NULL);
 174 }
 175
 176 _public_ int sd_bus_reply_method_error(
 177                 sd_bus_message *call,
 178                 const sd_bus_error *e) {
 179
 180         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 181         int r;
 182
 183         assert_return(call, -EINVAL);
 184         assert_return(call->sealed, -EPERM);
 185         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 186         assert_return(sd_bus_error_is_set(e), -EINVAL);
 187         assert_return(call->bus, -EINVAL);
 188         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 189
 190         if (!BUS_IS_OPEN(call->bus->state))
 191                 return -ENOTCONN;
 192
 193         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 194                 return 0;
 195
 196         r = sd_bus_message_new_method_error(call, &m, e);
 197         if (r < 0)
 198                 return r;
 199
 200         return sd_bus_send(call->bus, m, NULL);
 201 }
 202
 203 _public_ int sd_bus_reply_method_errorf(
 204                 sd_bus_message *call,
 205                 const char *name,
 206                 const char *format,
 207                 ...) {
 208
 209         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
 210         va_list ap;
 211
 212         assert_return(call, -EINVAL);
 213         assert_return(call->sealed, -EPERM);
 214         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 215         assert_return(call->bus, -EINVAL);
 216         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 217
 218         if (!BUS_IS_OPEN(call->bus->state))
 219                 return -ENOTCONN;
 220
 221         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 222                 return 0;
 223
 224         va_start(ap, format);
 225         bus_error_setfv(&error, name, format, ap);
 226         va_end(ap);
 227
 228         return sd_bus_reply_method_error(call, &error);
 229 }
 230
 231 _public_ int sd_bus_reply_method_errno(
 232                 sd_bus_message *call,
 233                 int error,
 234                 const sd_bus_error *p) {
 235
 236         _cleanup_(sd_bus_error_free) sd_bus_error berror = SD_BUS_ERROR_NULL;
 237
 238         assert_return(call, -EINVAL);
 239         assert_return(call->sealed, -EPERM);
 240         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 241         assert_return(call->bus, -EINVAL);
 242         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 243
 244         if (!BUS_IS_OPEN(call->bus->state))
 245                 return -ENOTCONN;
 246
 247         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 248                 return 0;
 249
 250         if (sd_bus_error_is_set(p))
 251                 return sd_bus_reply_method_error(call, p);
 252
 253         sd_bus_error_set_errno(&berror, error);
 254
 255         return sd_bus_reply_method_error(call, &berror);
 256 }
 257
 258 #if 0 /// UNNEEDED by elogind
 259 _public_ int sd_bus_reply_method_errnof(
 260                 sd_bus_message *call,
 261                 int error,
 262                 const char *format,
 263                 ...) {
 264
 265         _cleanup_(sd_bus_error_free) sd_bus_error berror = SD_BUS_ERROR_NULL;
 266         va_list ap;
 267
 268         assert_return(call, -EINVAL);
 269         assert_return(call->sealed, -EPERM);
 270         assert_return(call->header->type == SD_BUS_MESSAGE_METHOD_CALL, -EINVAL);
 271         assert_return(call->bus, -EINVAL);
 272         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 273
 274         if (!BUS_IS_OPEN(call->bus->state))
 275                 return -ENOTCONN;
 276
 277         if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
 278                 return 0;
 279
 280         va_start(ap, format);
 281         sd_bus_error_set_errnofv(&berror, error, format, ap);
 282         va_end(ap);
 283
 284         return sd_bus_reply_method_error(call, &berror);
 285 }
 286 #endif // 0
 287
 288 _public_ int sd_bus_get_property(
 289                 sd_bus *bus,
 290                 const char *destination,
 291                 const char *path,
 292                 const char *interface,
 293                 const char *member,
 294                 sd_bus_error *error,
 295                 sd_bus_message **reply,
 296                 const char *type) {
 297
 298         sd_bus_message *rep = NULL;
 299         int r;
 300
 301         bus_assert_return(bus, -EINVAL, error);
 302         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 303         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 304         bus_assert_return(reply, -EINVAL, error);
 305         bus_assert_return(signature_is_single(type, false), -EINVAL, error);
 306         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 307
 308         if (!BUS_IS_OPEN(bus->state)) {
 309                 r = -ENOTCONN;
 310                 goto fail;
 311         }
 312
 313         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &rep, "ss", strempty(interface), member);
 314         if (r < 0)
 315                 return r;
 316
 317         r = sd_bus_message_enter_container(rep, 'v', type);
 318         if (r < 0) {
 319                 sd_bus_message_unref(rep);
 320                 goto fail;
 321         }
 322
 323         *reply = rep;
 324         return 0;
 325
 326 fail:
 327         return sd_bus_error_set_errno(error, r);
 328 }
 329
 330 _public_ int sd_bus_get_property_trivial(
 331                 sd_bus *bus,
 332                 const char *destination,
 333                 const char *path,
 334                 const char *interface,
 335                 const char *member,
 336                 sd_bus_error *error,
 337                 char type, void *ptr) {
 338
 339         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 340         int r;
 341
 342         bus_assert_return(bus, -EINVAL, error);
 343         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 344         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 345         bus_assert_return(bus_type_is_trivial(type), -EINVAL, error);
 346         bus_assert_return(ptr, -EINVAL, error);
 347         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 348
 349         if (!BUS_IS_OPEN(bus->state)) {
 350                 r = -ENOTCONN;
 351                 goto fail;
 352         }
 353
 354         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
 355         if (r < 0)
 356                 return r;
 357
 358         r = sd_bus_message_enter_container(reply, 'v', CHAR_TO_STR(type));
 359         if (r < 0)
 360                 goto fail;
 361
 362         r = sd_bus_message_read_basic(reply, type, ptr);
 363         if (r < 0)
 364                 goto fail;
 365
 366         return 0;
 367
 368 fail:
 369         return sd_bus_error_set_errno(error, r);
 370 }
 371
 372 _public_ int sd_bus_get_property_string(
 373                 sd_bus *bus,
 374                 const char *destination,
 375                 const char *path,
 376                 const char *interface,
 377                 const char *member,
 378                 sd_bus_error *error,
 379                 char **ret) {
 380
 381         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 382         const char *s;
 383         char *n;
 384         int r;
 385
 386         bus_assert_return(bus, -EINVAL, error);
 387         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 388         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 389         bus_assert_return(ret, -EINVAL, error);
 390         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 391
 392         if (!BUS_IS_OPEN(bus->state)) {
 393                 r = -ENOTCONN;
 394                 goto fail;
 395         }
 396
 397         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
 398         if (r < 0)
 399                 return r;
 400
 401         r = sd_bus_message_enter_container(reply, 'v', "s");
 402         if (r < 0)
 403                 goto fail;
 404
 405         r = sd_bus_message_read_basic(reply, 's', &s);
 406         if (r < 0)
 407                 goto fail;
 408
 409         n = strdup(s);
 410         if (!n) {
 411                 r = -ENOMEM;
 412                 goto fail;
 413         }
 414
 415         *ret = n;
 416         return 0;
 417
 418 fail:
 419         return sd_bus_error_set_errno(error, r);
 420 }
 421
 422 #if 0 /// UNNEEDED by elogind
 423 _public_ int sd_bus_get_property_strv(
 424                 sd_bus *bus,
 425                 const char *destination,
 426                 const char *path,
 427                 const char *interface,
 428                 const char *member,
 429                 sd_bus_error *error,
 430                 char ***ret) {
 431
 432         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
 433         int r;
 434
 435         bus_assert_return(bus, -EINVAL, error);
 436         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 437         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 438         bus_assert_return(ret, -EINVAL, error);
 439         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 440
 441         if (!BUS_IS_OPEN(bus->state)) {
 442                 r = -ENOTCONN;
 443                 goto fail;
 444         }
 445
 446         r = sd_bus_call_method(bus, destination, path, "org.freedesktop.DBus.Properties", "Get", error, &reply, "ss", strempty(interface), member);
 447         if (r < 0)
 448                 return r;
 449
 450         r = sd_bus_message_enter_container(reply, 'v', NULL);
 451         if (r < 0)
 452                 goto fail;
 453
 454         r = sd_bus_message_read_strv(reply, ret);
 455         if (r < 0)
 456                 goto fail;
 457
 458         return 0;
 459
 460 fail:
 461         return sd_bus_error_set_errno(error, r);
 462 }
 463
 464 _public_ int sd_bus_set_property(
 465                 sd_bus *bus,
 466                 const char *destination,
 467                 const char *path,
 468                 const char *interface,
 469                 const char *member,
 470                 sd_bus_error *error,
 471                 const char *type, ...) {
 472
 473         _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 474         va_list ap;
 475         int r;
 476
 477         bus_assert_return(bus, -EINVAL, error);
 478         bus_assert_return(isempty(interface) || interface_name_is_valid(interface), -EINVAL, error);
 479         bus_assert_return(member_name_is_valid(member), -EINVAL, error);
 480         bus_assert_return(signature_is_single(type, false), -EINVAL, error);
 481         bus_assert_return(!bus_pid_changed(bus), -ECHILD, error);
 482
 483         if (!BUS_IS_OPEN(bus->state)) {
 484                 r = -ENOTCONN;
 485                 goto fail;
 486         }
 487
 488         r = sd_bus_message_new_method_call(bus, &m, destination, path, "org.freedesktop.DBus.Properties", "Set");
 489         if (r < 0)
 490                 goto fail;
 491
 492         r = sd_bus_message_append(m, "ss", strempty(interface), member);
 493         if (r < 0)
 494                 goto fail;
 495
 496         r = sd_bus_message_open_container(m, 'v', type);
 497         if (r < 0)
 498                 goto fail;
 499
 500         va_start(ap, type);
 501         r = sd_bus_message_appendv(m, type, ap);
 502         va_end(ap);
 503         if (r < 0)
 504                 goto fail;
 505
 506         r = sd_bus_message_close_container(m);
 507         if (r < 0)
 508                 goto fail;
 509
 510         return sd_bus_call(bus, m, 0, error, NULL);
 511
 512 fail:
 513         return sd_bus_error_set_errno(error, r);
 514 }
 515 #endif // 0
 516
 517 _public_ int sd_bus_query_sender_creds(sd_bus_message *call, uint64_t mask, sd_bus_creds **creds) {
 518         sd_bus_creds *c;
 519
 520         assert_return(call, -EINVAL);
 521         assert_return(call->sealed, -EPERM);
 522         assert_return(call->bus, -EINVAL);
 523         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 524
 525         if (!BUS_IS_OPEN(call->bus->state))
 526                 return -ENOTCONN;
 527
 528         c = sd_bus_message_get_creds(call);
 529
 530         /* All data we need? */
 531         if (c && (mask & ~c->mask) == 0) {
 532                 *creds = sd_bus_creds_ref(c);
 533                 return 0;
 534         }
 535
 536         /* No data passed? Or not enough data passed to retrieve the missing bits? */
 537         if (!c || !(c->mask & SD_BUS_CREDS_PID)) {
 538                 /* We couldn't read anything from the call, let's try
 539                  * to get it from the sender or peer. */
 540
 541                 if (call->sender)
 542                         /* There's a sender, but the creds are
 543                          * missing. This means we are talking via
 544                          * dbus1, or are getting a message that was
 545                          * sent to us via kdbus, but was converted
 546                          * from a dbus1 message by the bus-proxy and
 547                          * thus also lacks the creds. */
 548                         return sd_bus_get_name_creds(call->bus, call->sender, mask, creds);
 549                 else
 550                         /* There's no sender, hence we are on a dbus1
 551                          * direct connection. For direct connections
 552                          * the credentials of the AF_UNIX peer matter,
 553                          * which may be queried via
 554                          * sd_bus_get_owner_creds(). */
 555                         return sd_bus_get_owner_creds(call->bus, mask, creds);
 556         }
 557
 558         return bus_creds_extend_by_pid(c, mask, creds);
 559 }
 560
 561 _public_ int sd_bus_query_sender_privilege(sd_bus_message *call, int capability) {
 562         _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
 563         uid_t our_uid;
 564         bool know_caps = false;
 565         int r;
 566
 567         assert_return(call, -EINVAL);
 568         assert_return(call->sealed, -EPERM);
 569         assert_return(call->bus, -EINVAL);
 570         assert_return(!bus_pid_changed(call->bus), -ECHILD);
 571
 572         if (!BUS_IS_OPEN(call->bus->state))
 573                 return -ENOTCONN;
 574
 575         if (capability >= 0) {
 576
 577                 r = sd_bus_query_sender_creds(call, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_EFFECTIVE_CAPS, &creds);
 578                 if (r < 0)
 579                         return r;
 580
 581                 /* We cannot use augmented caps for authorization,
 582                  * since then data is acquired raceful from
 583                  * /proc. This can never actually happen, but let's
 584                  * better be safe than sorry, and do an extra check
 585                  * here. */
 586                 assert_return((sd_bus_creds_get_augmented_mask(creds) & SD_BUS_CREDS_EFFECTIVE_CAPS) == 0, -EPERM);
 587
 588                 /* Note that not even on kdbus we might have the caps
 589                  * field, due to faked identities, or namespace
 590                  * translation issues. */
 591                 r = sd_bus_creds_has_effective_cap(creds, capability);
 592                 if (r > 0)
 593                         return 1;
 594                 if (r == 0)
 595                         know_caps = true;
 596         } else {
 597                 r = sd_bus_query_sender_creds(call, SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID, &creds);
 598                 if (r < 0)
 599                         return r;
 600         }
 601
 602         /* Now, check the UID, but only if the capability check wasn't
 603          * sufficient */
 604         our_uid = getuid();
 605         if (our_uid != 0 || !know_caps || capability < 0) {
 606                 uid_t sender_uid;
 607
 608                 /* We cannot use augmented uid/euid for authorization,
 609                  * since then data is acquired raceful from
 610                  * /proc. This can never actually happen, but let's
 611                  * better be safe than sorry, and do an extra check
 612                  * here. */
 613                 assert_return((sd_bus_creds_get_augmented_mask(creds) & (SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID)) == 0, -EPERM);
 614
 615                 /* Try to use the EUID, if we have it. */
 616                 r = sd_bus_creds_get_euid(creds, &sender_uid);
 617                 if (r < 0)
 618                         r = sd_bus_creds_get_uid(creds, &sender_uid);
 619
 620                 if (r >= 0) {
 621                         /* Sender has same UID as us, then let's grant access */
 622                         if (sender_uid == our_uid)
 623                                 return 1;
 624
 625                         /* Sender is root, we are not root. */
 626                         if (our_uid != 0 && sender_uid == 0)
 627                                 return 1;
 628                 }
 629         }
 630
 631         return 0;
 632 }