summaryrefslogtreecommitdiff
path: root/src/bus-proxyd/proxy.c
blob: 425af658734ce6b39bd178a8a22f45809cc166f5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering
  Copyright 2013 Daniel Mack
  Copyright 2014 Kay Sievers
  Copyright 2014 David Herrmann

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <sys/socket.h>
#include <sys/types.h>
#include <string.h>
#include <errno.h>
#include <poll.h>

#include "log.h"
#include "util.h"
#include "sd-daemon.h"
#include "sd-bus.h"
#include "bus-internal.h"
#include "bus-message.h"
#include "bus-util.h"
#include "strv.h"
#include "bus-control.h"
#include "set.h"
#include "bus-xml-policy.h"
#include "driver.h"
#include "proxy.h"
#include "synthesize.h"
#include "formats-util.h"

static int proxy_create_destination(Proxy *p, const char *destination, const char *local_sec, bool negotiate_fds) {
        _cleanup_bus_flush_close_unref_ sd_bus *b = NULL;
        int r;

        r = sd_bus_new(&b);
        if (r < 0)
                return log_error_errno(r, "Failed to allocate bus: %m");

        r = sd_bus_set_description(b, "sd-proxy");
        if (r < 0)
                return log_error_errno(r, "Failed to set bus name: %m");

        r = sd_bus_set_address(b, destination);
        if (r < 0)
                return log_error_errno(r, "Failed to set address to connect to: %m");

        r = sd_bus_negotiate_fds(b, negotiate_fds);
        if (r < 0)
                return log_error_errno(r, "Failed to set FD negotiation: %m");

        r = sd_bus_negotiate_creds(b, true, SD_BUS_CREDS_EUID|SD_BUS_CREDS_PID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_SELINUX_CONTEXT);
        if (r < 0)
                return log_error_errno(r, "Failed to set credential negotiation: %m");

        if (p->local_creds.pid > 0) {
                b->fake_pids.pid = p->local_creds.pid;
                b->fake_pids_valid = true;

                b->fake_creds.uid = UID_INVALID;
                b->fake_creds.euid = p->local_creds.uid;
                b->fake_creds.suid = UID_INVALID;
                b->fake_creds.fsuid = UID_INVALID;
                b->fake_creds.gid = GID_INVALID;
                b->fake_creds.egid = p->local_creds.gid;
                b->fake_creds.sgid = GID_INVALID;
                b->fake_creds.fsgid = GID_INVALID;
                b->fake_creds_valid = true;
        }

        if (local_sec) {
                b->fake_label = strdup(local_sec);
                if (!b->fake_label)
                        return log_oom();
        }

        b->manual_peer_interface = true;

        r = sd_bus_start(b);
        if (r < 0)
                return log_error_errno(r, "Failed to start bus client: %m");

        p->destination_bus = b;
        b = NULL;
        return 0;
}

static int proxy_create_local(Proxy *p, int in_fd, int out_fd, bool negotiate_fds) {
        _cleanup_bus_flush_close_unref_ sd_bus *b = NULL;
        sd_id128_t server_id;
        int r;

        r = sd_bus_new(&b);
        if (r < 0)
                return log_error_errno(r, "Failed to allocate bus: %m");

        r = sd_bus_set_fd(b, in_fd, out_fd);
        if (r < 0)
                return log_error_errno(r, "Failed to set fds: %m");

        r = sd_bus_get_bus_id(p->destination_bus, &server_id);
        if (r < 0)
                return log_error_errno(r, "Failed to get server ID: %m");

        r = sd_bus_set_server(b, 1, server_id);
        if (r < 0)
                return log_error_errno(r, "Failed to set server mode: %m");

        r = sd_bus_negotiate_fds(b, negotiate_fds);
        if (r < 0)
                return log_error_errno(r, "Failed to set FD negotiation: %m");

        r = sd_bus_negotiate_creds(b, true, SD_BUS_CREDS_EUID|SD_BUS_CREDS_PID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_SELINUX_CONTEXT);
        if (r < 0)
                return log_error_errno(r, "Failed to set credential negotiation: %m");

        r = sd_bus_set_anonymous(b, true);
        if (r < 0)
                return log_error_errno(r, "Failed to set anonymous authentication: %m");

        b->manual_peer_interface = true;

        r = sd_bus_start(b);
        if (r < 0)
                return log_error_errno(r, "Failed to start bus client: %m");

        p->local_bus = b;
        b = NULL;
        return 0;
}

static int proxy_match_synthetic(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        Proxy *p = userdata;

        p->synthetic_matched = true;
        return 0; /* make sure to continue processing it in further handlers */
}

/*
 * We always need NameOwnerChanged so we can synthesize NameLost and
 * NameAcquired. Furthermore, dbus-1 always passes unicast-signals through, so
 * subscribe unconditionally.
 */
static int proxy_prepare_matches(Proxy *p) {
        _cleanup_free_ char *match = NULL;
        const char *unique;
        int r;

        if (!p->destination_bus->is_kernel)
                return 0;

        r = sd_bus_get_unique_name(p->destination_bus, &unique);
        if (r < 0)
                return log_error_errno(r, "Failed to get unique name: %m");

        match = strjoin("type='signal',"
                        "sender='org.freedesktop.DBus',"
                        "path='/org/freedesktop/DBus',"
                        "interface='org.freedesktop.DBus',"
                        "member='NameOwnerChanged',"
                        "arg1='",
                        unique,
                        "'",
                        NULL);
        if (!match)
                return log_oom();

        r = sd_bus_add_match(p->destination_bus, NULL, match, proxy_match_synthetic, p);
        if (r < 0)
                return log_error_errno(r, "Failed to add match for NameLost: %m");

        free(match);
        match = strjoin("type='signal',"
                        "sender='org.freedesktop.DBus',"
                        "path='/org/freedesktop/DBus',"
                        "interface='org.freedesktop.DBus',"
                        "member='NameOwnerChanged',"
                        "arg2='",
                        unique,
                        "'",
                        NULL);
        if (!match)
                return log_oom();

        r = sd_bus_add_match(p->destination_bus, NULL, match, proxy_match_synthetic, p);
        if (r < 0)
                return log_error_errno(r, "Failed to add match for NameAcquired: %m");

        free(match);
        match = strjoin("type='signal',"
                        "destination='",
                        unique,
                        "'",
                        NULL);
        if (!match)
                return log_oom();

        r = sd_bus_add_match(p->destination_bus, NULL, match, proxy_match_synthetic, p);
        if (r < 0)
                log_error_errno(r, "Failed to add match for directed signals: %m");
                /* FIXME: temporarily ignore error to support older kdbus versions */

        return 0;
}

int proxy_new(Proxy **out, int in_fd, int out_fd, const char *destination) {
        _cleanup_(proxy_freep) Proxy *p = NULL;
        _cleanup_free_ char *local_sec = NULL;
        bool is_unix;
        int r;

        p = new0(Proxy, 1);
        if (!p)
                return log_oom();

        p->local_in = in_fd;
        p->local_out = out_fd;

        p->owned_names = set_new(&string_hash_ops);
        if (!p->owned_names)
                return log_oom();

        is_unix = sd_is_socket(in_fd, AF_UNIX, 0, 0) > 0 &&
                  sd_is_socket(out_fd, AF_UNIX, 0, 0) > 0;

        if (is_unix) {
                (void) getpeercred(in_fd, &p->local_creds);
                (void) getpeersec(in_fd, &local_sec);
        }

        r = proxy_create_destination(p, destination, local_sec, is_unix);
        if (r < 0)
                return r;

        r = proxy_create_local(p, in_fd, out_fd, is_unix);
        if (r < 0)
                return r;

        r = proxy_prepare_matches(p);
        if (r < 0)
                return r;

        *out = p;
        p = NULL;
        return 0;
}

Proxy *proxy_free(Proxy *p) {
        if (!p)
                return NULL;

        sd_bus_flush_close_unref(p->local_bus);
        sd_bus_flush_close_unref(p->destination_bus);
        set_free_free(p->owned_names);
        free(p);

        return NULL;
}

int proxy_set_policy(Proxy *p, SharedPolicy *sp, char **configuration) {
        _cleanup_strv_free_ char **strv = NULL;
        Policy *policy;
        int r;

        assert(p);
        assert(sp);

        /* no need to load legacy policy if destination is not kdbus */
        if (!p->destination_bus->is_kernel)
                return 0;

        p->policy = sp;

        policy = shared_policy_acquire(sp);
        if (policy) {
                /* policy already pre-loaded */
                shared_policy_release(sp, policy);
                return 0;
        }

        if (!configuration) {
                const char *scope;

                r = sd_bus_get_scope(p->destination_bus, &scope);
                if (r < 0)
                        return log_error_errno(r, "Couldn't determine bus scope: %m");

                if (streq(scope, "system"))
                        strv = strv_new("/usr/share/dbus-1/system.conf",
                                        "/etc/dbus-1/system.conf",
                                        "/usr/share/dbus-1/system.d/",
                                        "/etc/dbus-1/system.d/",
                                        "/etc/dbus-1/system-local.conf",
                                        NULL);
                else if (streq(scope, "user"))
                        strv = strv_new("/usr/share/dbus-1/session.conf",
                                        "/etc/dbus-1/session.conf",
                                        "/usr/share/dbus-1/session.d/",
                                        "/etc/dbus-1/session.d/",
                                        "/etc/dbus-1/session-local.conf",
                                        NULL);
                else
                        return log_error("Unknown scope %s, don't know which policy to load. Refusing.", scope);

                if (!strv)
                        return log_oom();

                configuration = strv;
        }

        return shared_policy_preload(sp, configuration);
}

int proxy_hello_policy(Proxy *p, uid_t original_uid) {
        Policy *policy;
        int r = 0;

        assert(p);

        if (!p->policy)
                return 0;

        policy = shared_policy_acquire(p->policy);

        if (p->local_creds.uid == original_uid)
                log_debug("Permitting access, since bus owner matches bus client.");
        else if (policy_check_hello(policy, p->local_creds.uid, p->local_creds.gid))
                log_debug("Permitting access due to XML policy.");
        else
                r = log_error_errno(EPERM, "Policy denied connection.");

        shared_policy_release(p->policy, policy);

        return r;
}

static int proxy_wait(Proxy *p) {
        uint64_t timeout_destination, timeout_local, t;
        int events_destination, events_local, fd;
        struct timespec _ts, *ts;
        struct pollfd *pollfd;
        int r;

        assert(p);

        fd = sd_bus_get_fd(p->destination_bus);
        if (fd < 0)
                return log_error_errno(fd, "Failed to get fd: %m");

        events_destination = sd_bus_get_events(p->destination_bus);
        if (events_destination < 0)
                return log_error_errno(events_destination, "Failed to get events mask: %m");

        r = sd_bus_get_timeout(p->destination_bus, &timeout_destination);
        if (r < 0)
                return log_error_errno(r, "Failed to get timeout: %m");

        events_local = sd_bus_get_events(p->local_bus);
        if (events_local < 0)
                return log_error_errno(events_local, "Failed to get events mask: %m");

        r = sd_bus_get_timeout(p->local_bus, &timeout_local);
        if (r < 0)
                return log_error_errno(r, "Failed to get timeout: %m");

        t = timeout_destination;
        if (t == (uint64_t) -1 || (timeout_local != (uint64_t) -1 && timeout_local < timeout_destination))
                t = timeout_local;

        if (t == (uint64_t) -1)
                ts = NULL;
        else {
                usec_t nw;

                nw = now(CLOCK_MONOTONIC);
                if (t > nw)
                        t -= nw;
                else
                        t = 0;

                ts = timespec_store(&_ts, t);
        }

        pollfd = (struct pollfd[3]) {
                { .fd = fd,           .events = events_destination,     },
                { .fd = p->local_in,  .events = events_local & POLLIN,  },
                { .fd = p->local_out, .events = events_local & POLLOUT, },
        };

        r = ppoll(pollfd, 3, ts, NULL);
        if (r < 0)
                return log_error_errno(errno, "ppoll() failed: %m");

        return 0;
}

static int handle_policy_error(sd_bus_message *m, int r) {
        if (r == -ESRCH || r == -ENXIO)
                return synthetic_reply_method_errorf(m, SD_BUS_ERROR_NAME_HAS_NO_OWNER, "Name %s is currently not owned by anyone.", m->destination);

        return r;
}

static int process_policy_unlocked(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *policy, const struct ucred *our_ucred, Set *owned_names) {
        int r;

        assert(from);
        assert(to);
        assert(m);

        if (!policy)
                return 0;

        /*
         * dbus-1 distinguishes expected and non-expected replies by tracking
         * method-calls and timeouts. By default, DENY rules are *NEVER* applied
         * on expected replies, unless explicitly specified. But we dont track
         * method-calls, thus, we cannot know whether a reply is expected.
         * Fortunately, the kdbus forbids non-expected replies, so we can safely
         * ignore any policy on those and let the kernel deal with it.
         *
         * TODO: To be correct, we should only ignore policy-tags that are
         * applied on non-expected replies. However, so far we don't parse those
         * tags so we let everything pass. I haven't seen a DENY policy tag on
         * expected-replies, ever, so don't bother..
         */
        if (m->reply_cookie > 0)
                return 0;

        if (from->is_kernel) {
                uid_t sender_uid = UID_INVALID;
                gid_t sender_gid = GID_INVALID;
                char **sender_names = NULL;

                /* Driver messages are always OK */
                if (streq_ptr(m->sender, "org.freedesktop.DBus"))
                        return 0;

                /* The message came from the kernel, and is sent to our legacy client. */
                (void) sd_bus_creds_get_well_known_names(&m->creds, &sender_names);

                (void) sd_bus_creds_get_euid(&m->creds, &sender_uid);
                (void) sd_bus_creds_get_egid(&m->creds, &sender_gid);

                if (sender_uid == UID_INVALID || sender_gid == GID_INVALID) {
                        _cleanup_bus_creds_unref_ sd_bus_creds *sender_creds = NULL;

                        /* If the message came from another legacy
                         * client, then the message creds will be
                         * missing, simply because on legacy clients
                         * per-message creds were unknown. In this
                         * case, query the creds of the peer
                         * instead. */

                        r = bus_get_name_creds_kdbus(from, m->sender, SD_BUS_CREDS_EUID|SD_BUS_CREDS_EGID, true, &sender_creds);
                        if (r < 0)
                                return handle_policy_error(m, r);

                        (void) sd_bus_creds_get_euid(sender_creds, &sender_uid);
                        (void) sd_bus_creds_get_egid(sender_creds, &sender_gid);
                }

                /* First check whether the sender can send the message to our name */
                if (policy_check_send(policy, sender_uid, sender_gid, m->header->type, owned_names, NULL, m->path, m->interface, m->member, false, NULL) &&
                    policy_check_recv(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, sender_names, m->path, m->interface, m->member, false))
                        return 0;

                /* Return an error back to the caller */
                if (m->header->type == SD_BUS_MESSAGE_METHOD_CALL)
                        return synthetic_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML receiver policy.");

                /* Return 1, indicating that the message shall not be processed any further */
                return 1;
        }

        if (to->is_kernel) {
                _cleanup_bus_creds_unref_ sd_bus_creds *destination_creds = NULL;
                uid_t destination_uid = UID_INVALID;
                gid_t destination_gid = GID_INVALID;
                const char *destination_unique = NULL;
                char **destination_names = NULL;
                char *n;

                /* Driver messages are always OK */
                if (streq_ptr(m->destination, "org.freedesktop.DBus"))
                        return 0;

                /* The message came from the legacy client, and is sent to kdbus. */
                if (m->destination) {
                        r = bus_get_name_creds_kdbus(to, m->destination,
                                                     SD_BUS_CREDS_WELL_KNOWN_NAMES|SD_BUS_CREDS_UNIQUE_NAME|
                                                     SD_BUS_CREDS_EUID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_PID,
                                                     true, &destination_creds);
                        if (r < 0)
                                return handle_policy_error(m, r);

                        r = sd_bus_creds_get_unique_name(destination_creds, &destination_unique);
                        if (r < 0)
                                return handle_policy_error(m, r);

                        (void) sd_bus_creds_get_well_known_names(destination_creds, &destination_names);

                        (void) sd_bus_creds_get_euid(destination_creds, &destination_uid);
                        (void) sd_bus_creds_get_egid(destination_creds, &destination_gid);
                }

                /* First check if we (the sender) can send to this name */
                if (sd_bus_message_is_signal(m, NULL, NULL)) {
                        /* If we forward a signal from dbus-1 to kdbus, we have
                         * no idea who the recipient is. Therefore, we cannot
                         * apply any dbus-1 policies that match on receiver
                         * credentials. We know sd-bus always sets
                         * KDBUS_MSG_SIGNAL, so the kernel applies policies to
                         * the message. Therefore, skip policy checks in this
                         * case. */
                        return 0;
                } else if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, destination_names, m->path, m->interface, m->member, true, &n)) {
                        if (n) {
                                /* If we made a receiver decision, then remember which
                                 * name's policy we used, and to which unique ID it
                                 * mapped when we made the decision. Then, let's pass
                                 * this to the kernel when sending the message, so that
                                 * it refuses the operation should the name and unique
                                 * ID not map to each other anymore. */

                                r = free_and_strdup(&m->destination_ptr, n);
                                if (r < 0)
                                        return r;

                                r = bus_kernel_parse_unique_name(destination_unique, &m->verify_destination_id);
                                if (r < 0)
                                        return r;
                        }

                        if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, owned_names, NULL, m->path, m->interface, m->member, true))
                                return 0;
                }

                /* Return an error back to the caller */
                if (m->header->type == SD_BUS_MESSAGE_METHOD_CALL)
                        return synthetic_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML sender policy.");

                /* Return 1, indicating that the message shall not be processed any further */
                return 1;
        }

        return 0;
}

static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, SharedPolicy *sp, const struct ucred *our_ucred, Set *owned_names) {
        Policy *policy;
        int r;

        assert(sp);

        policy = shared_policy_acquire(sp);
        r = process_policy_unlocked(from, to, m, policy, our_ucred, owned_names);
        shared_policy_release(sp, policy);

        return r;
}

static int process_hello(Proxy *p, sd_bus_message *m) {
        _cleanup_bus_message_unref_ sd_bus_message *n = NULL;
        bool is_hello;
        int r;

        assert(p);
        assert(m);

        /* As reaction to hello we need to respond with two messages:
         * the callback reply and the NameAcquired for the unique
         * name, since hello is otherwise obsolete on kdbus. */

        is_hello =
                sd_bus_message_is_method_call(m, "org.freedesktop.DBus", "Hello") &&
                streq_ptr(m->destination, "org.freedesktop.DBus");

        if (!is_hello) {
                if (p->got_hello)
                        return 0;

                return log_error_errno(EIO, "First packet isn't hello (it's %s.%s), aborting.", m->interface, m->member);
        }

        if (p->got_hello)
                return log_error_errno(EIO, "Got duplicate hello, aborting.");

        p->got_hello = true;

        if (!p->destination_bus->is_kernel)
                return 0;

        r = sd_bus_message_new_method_return(m, &n);
        if (r < 0)
                return log_error_errno(r, "Failed to generate HELLO reply: %m");

        r = sd_bus_message_append(n, "s", p->destination_bus->unique_name);
        if (r < 0)
                return log_error_errno(r, "Failed to append unique name to HELLO reply: %m");

        r = bus_message_append_sender(n, "org.freedesktop.DBus");
        if (r < 0)
                return log_error_errno(r, "Failed to append sender to HELLO reply: %m");

        r = bus_seal_synthetic_message(p->local_bus, n);
        if (r < 0)
                return log_error_errno(r, "Failed to seal HELLO reply: %m");

        r = sd_bus_send(p->local_bus, n, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to send HELLO reply: %m");

        n = sd_bus_message_unref(n);
        r = sd_bus_message_new_signal(
                        p->local_bus,
                        &n,
                        "/org/freedesktop/DBus",
                        "org.freedesktop.DBus",
                        "NameAcquired");
        if (r < 0)
                return log_error_errno(r, "Failed to allocate initial NameAcquired message: %m");

        r = sd_bus_message_append(n, "s", p->destination_bus->unique_name);
        if (r < 0)
                return log_error_errno(r, "Failed to append unique name to NameAcquired message: %m");

        r = bus_message_append_sender(n, "org.freedesktop.DBus");
        if (r < 0)
                return log_error_errno(r, "Failed to append sender to NameAcquired message: %m");

        r = sd_bus_message_set_destination(n, p->destination_bus->unique_name);
        if (r < 0)
                return log_error_errno(r, "Failed to set destination for NameAcquired message: %m");

        r = bus_seal_synthetic_message(p->local_bus, n);
        if (r < 0)
                return log_error_errno(r, "Failed to seal NameAcquired message: %m");

        r = sd_bus_send(p->local_bus, n, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to send NameAcquired message: %m");

        return 1;
}

static int patch_sender(sd_bus *a, sd_bus_message *m) {
        char **well_known = NULL;
        sd_bus_creds *c;
        int r;

        assert(a);
        assert(m);

        if (!a->is_kernel)
                return 0;

        /* We will change the sender of messages from the bus driver
         * so that they originate from the bus driver. This is a
         * speciality originating from dbus1, where the bus driver did
         * not have a unique id, but only the well-known name. */

        c = sd_bus_message_get_creds(m);
        if (!c)
                return 0;

        r = sd_bus_creds_get_well_known_names(c, &well_known);
        if (r < 0)
                return r;

        if (strv_contains(well_known, "org.freedesktop.DBus"))
                m->sender = "org.freedesktop.DBus";

        return 0;
}

static int proxy_process_destination_to_local(Proxy *p) {
        _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
        bool matched, matched_synthetic;
        int r;

        assert(p);

        /*
         * Usually, we would just take any message that the bus passes to us
         * and forward it to the local connection. However, there are actually
         * applications that fail if they receive broadcasts that they didn't
         * subscribe to. Therefore, we actually emulate a real broadcast
         * matching here, and discard any broadcasts that weren't matched. Our
         * match-handlers remembers whether a message was matched by any rule,
         * by marking it in @p->message_matched.
         */

        r = sd_bus_process(p->destination_bus, &m);

        matched = p->message_matched;
        matched_synthetic = p->synthetic_matched;
        p->message_matched = false;
        p->synthetic_matched = false;

        if (r == -ECONNRESET || r == -ENOTCONN) /* Treat 'connection reset by peer' as clean exit condition */
                return r;
        if (r < 0) {
                log_error_errno(r, "Failed to process destination bus: %m");
                return r;
        }
        if (r == 0)
                return 0;
        if (!m)
                return 1;

        /* We officially got EOF, let's quit */
        if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected"))
                return -ECONNRESET;

        r = synthesize_name_acquired(p, p->destination_bus, p->local_bus, m);
        if (r == -ECONNRESET || r == -ENOTCONN)
                return r;
        if (r < 0)
                return log_error_errno(r, "Failed to synthesize message: %m");

        /* discard broadcasts that were not matched by any MATCH rule */
        if (!matched && !sd_bus_message_get_destination(m)) {
                if (!matched_synthetic)
                        log_debug("Dropped unmatched broadcast: uid=" UID_FMT " gid=" GID_FMT " pid=" PID_FMT " message=%s path=%s interface=%s member=%s sender=%s destination=%s",
                                  p->local_creds.uid, p->local_creds.gid, p->local_creds.pid, bus_message_type_to_string(m->header->type),
                                  strna(m->path), strna(m->interface), strna(m->member), strna(m->sender), strna(m->destination));
                return 1;
        }

        patch_sender(p->destination_bus, m);

        if (p->policy) {
                r = process_policy(p->destination_bus, p->local_bus, m, p->policy, &p->local_creds, p->owned_names);
                if (r == -ECONNRESET || r == -ENOTCONN)
                        return r;
                if (r < 0)
                        return log_error_errno(r, "Failed to process policy: %m");
                if (r > 0)
                        return 1;
        }

        r = sd_bus_send(p->local_bus, m, NULL);
        if (r < 0) {
                if (r == -ECONNRESET || r == -ENOTCONN)
                        return r;

                /* If the peer tries to send a reply and it is
                 * rejected with EPERM by the kernel, we ignore the
                 * error. This catches cases where the original
                 * method-call didn't had EXPECT_REPLY set, but the
                 * proxy-peer still sends a reply. This is allowed in
                 * dbus1, but not in kdbus. We don't want to track
                 * reply-windows in the proxy, so we simply ignore
                 * EPERM for all replies. The only downside is, that
                 * callers are no longer notified if their replies are
                 * dropped. However, this is equivalent to the
                 * caller's timeout to expire, so this should be
                 * acceptable. Nobody sane sends replies without a
                 * matching method-call, so nobody should care. */
                if (r == -EPERM && m->reply_cookie > 0)
                        return 1;

                /* Return the error to the client, if we can */
                synthetic_reply_method_errnof(m, r, "Failed to forward message we got from destination: %m");
                if (r == -ENOBUFS) {
                        /* if local dbus1 peer does not dispatch its queue, warn only once */
                        if (!p->queue_overflow)
                                log_error("Dropped messages due to queue overflow of local peer (pid: "PID_FMT" uid: "UID_FMT")", p->local_creds.pid, p->local_creds.uid);
                        p->queue_overflow = true;
                } else
                        log_error_errno(r,
                                 "Failed to forward message we got from destination: uid=" UID_FMT " gid=" GID_FMT" message=%s destination=%s path=%s interface=%s member=%s: %m",
                                 p->local_creds.uid, p->local_creds.gid, bus_message_type_to_string(m->header->type),
                                 strna(m->destination), strna(m->path), strna(m->interface), strna(m->member));

                return 1;
        }

        p->queue_overflow = false;
        return 1;
}

static int proxy_process_local_to_destination(Proxy *p) {
        _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
        int r;

        assert(p);

        r = sd_bus_process(p->local_bus, &m);
        if (r == -ECONNRESET || r == -ENOTCONN) /* Treat 'connection reset by peer' as clean exit condition */
                return r;
        if (r < 0) {
                log_error_errno(r, "Failed to process local bus: %m");
                return r;
        }
        if (r == 0)
                return 0;
        if (!m)
                return 1;

        /* We officially got EOF, let's quit */
        if (sd_bus_message_is_signal(m, "org.freedesktop.DBus.Local", "Disconnected"))
                return -ECONNRESET;

        r = process_hello(p, m);
        if (r == -ECONNRESET || r == -ENOTCONN)
                return r;
        if (r < 0)
                return log_error_errno(r, "Failed to process HELLO: %m");
        if (r > 0)
                return 1;

        r = bus_proxy_process_driver(p, p->destination_bus, p->local_bus, m, p->policy, &p->local_creds, p->owned_names);
        if (r == -ECONNRESET || r == -ENOTCONN)
                return r;
        if (r < 0)
                return log_error_errno(r, "Failed to process driver calls: %m");
        if (r > 0)
                return 1;

        for (;;) {
                if (p->policy) {
                        r = process_policy(p->local_bus, p->destination_bus, m, p->policy, &p->local_creds, p->owned_names);
                        if (r == -ECONNRESET || r == -ENOTCONN)
                                return r;
                        if (r < 0)
                                return log_error_errno(r, "Failed to process policy: %m");
                        if (r > 0)
                                return 1;
                }

                r = sd_bus_send(p->destination_bus, m, NULL);
                if (r < 0) {
                        if (r == -ECONNRESET || r == -ENOTCONN)
                                return r;

                        /* The name database changed since the policy check, hence let's check again */
                        if (r == -EREMCHG)
                                continue;

                        /* see above why EPERM is ignored for replies */
                        if (r == -EPERM && m->reply_cookie > 0)
                                return 1;

                        synthetic_reply_method_errnof(m, r, "Failed to forward message we got from local: %m");
                        log_error_errno(r,
                                 "Failed to forward message we got from local: uid=" UID_FMT " gid=" GID_FMT" message=%s destination=%s path=%s interface=%s member=%s: %m",
                                 p->local_creds.uid, p->local_creds.gid, bus_message_type_to_string(m->header->type),
                                 strna(m->destination), strna(m->path), strna(m->interface), strna(m->member));
                        return 1;
                }

                break;
        }

        return 1;
}

int proxy_match(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        Proxy *p = userdata;

        p->message_matched = true;
        return 0; /* make sure to continue processing it in further handlers */
}

int proxy_run(Proxy *p) {
        int r;

        assert(p);

        for (;;) {
                bool busy = false;

                if (p->got_hello) {
                        /* Read messages from bus, to pass them on to our client */
                        r = proxy_process_destination_to_local(p);
                        if (r == -ECONNRESET || r == -ENOTCONN)
                                return 0;
                        if (r < 0)
                                return r;
                        if (r > 0)
                                busy = true;
                }

                /* Read messages from our client, to pass them on to the bus */
                r = proxy_process_local_to_destination(p);
                if (r == -ECONNRESET || r == -ENOTCONN)
                        return 0;
                if (r < 0)
                        return r;
                if (r > 0)
                        busy = true;

                if (!busy) {
                        r = proxy_wait(p);
                        if (r == -ECONNRESET || r == -ENOTCONN)
                                return 0;
                        if (r < 0)
                                return r;
                }
        }

        return 0;
}