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