-
-
Notifications
You must be signed in to change notification settings - Fork 389
/
flatpak-instance.c
1204 lines (1033 loc) · 38.7 KB
/
flatpak-instance.c
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
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* vi:set et sw=2 sts=2 cin cino=t0,f0,(0,{s,>2s,n-s,^-s,e-s:
* Copyright © 2018 Red Hat, Inc
*
* This program 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.
*
* This library 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 this library. If not, see <http:https://www.gnu.org/licenses/>.
*
* Authors:
* Matthias Clasen <[email protected]>
*/
#include "config.h"
#include <fcntl.h>
#include <unistd.h>
#include "flatpak-json-backports-private.h"
#include "flatpak-metadata-private.h"
#include "flatpak-utils-base-private.h"
#include "flatpak-utils-private.h"
#include "flatpak-instance.h"
#include "flatpak-instance-private.h"
#include "flatpak-enum-types.h"
#include <glib/gi18n-lib.h>
/**
* SECTION:flatpak-instance
* @Title: FlatpakInstance
* @Short_description: Information about a running sandbox
*
* A FlatpakInstance refers to a running sandbox, and contains
* some basic information about the sandbox setup, such as the
* application and runtime used inside the sandbox.
*
* Importantly, it also gives access to the PID of the main
* processes in the sandbox.
*
* One way to obtain FlatpakInstances is to use flatpak_instance_get_all().
* Another way is to use flatpak_installation_launch_full().
*
* Note that process lifecycle tracking is fundamentally racy.
* You have to be prepared for the sandbox and the processes
* represented by a FlatpakInstance to not be around anymore.
*
* The FlatpakInstance api was added in Flatpak 1.1.
*/
typedef struct _FlatpakInstancePrivate FlatpakInstancePrivate;
struct _FlatpakInstancePrivate
{
char *id;
char *dir;
char *private_dir;
GKeyFile *info;
char *app;
char *arch;
char *branch;
char *commit;
char *runtime;
char *runtime_commit;
int pid;
int child_pid;
};
G_DEFINE_TYPE_WITH_PRIVATE (FlatpakInstance, flatpak_instance, G_TYPE_OBJECT)
static void
flatpak_instance_finalize (GObject *object)
{
FlatpakInstance *self = FLATPAK_INSTANCE (object);
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
g_free (priv->id);
g_free (priv->dir);
g_free (priv->private_dir);
g_free (priv->app);
g_free (priv->arch);
g_free (priv->branch);
g_free (priv->commit);
g_free (priv->runtime);
g_free (priv->runtime_commit);
if (priv->info)
g_key_file_unref (priv->info);
G_OBJECT_CLASS (flatpak_instance_parent_class)->finalize (object);
}
static void
flatpak_instance_class_init (FlatpakInstanceClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->finalize = flatpak_instance_finalize;
}
static void
flatpak_instance_init (FlatpakInstance *self)
{
}
/**
* flatpak_instance_get_id:
* @self: a #FlatpakInstance
*
* Gets the instance ID. The ID is used by Flatpak for bookkeeping
* purposes and has no further relevance.
*
* Returns: the instance ID
*
* Since: 1.1
*/
const char *
flatpak_instance_get_id (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->id;
}
/**
* flatpak_instance_get_app:
* @self: a #FlatpakInstance
*
* Gets the application ID of the application running in the instance.
*
* Note that this may return %NULL for sandboxes that don't have an application.
*
* Returns: (nullable): the application ID or %NULL
*
* Since: 1.1
*/
const char *
flatpak_instance_get_app (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->app;
}
/**
* flatpak_instance_get_arch:
* @self: a #FlatpakInstance
*
* Gets the architecture of the application running in the instance.
*
* Returns: the architecture
*
* Since: 1.1
*/
const char *
flatpak_instance_get_arch (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->arch;
}
/**
* flatpak_instance_get_branch:
* @self: a #FlatpakInstance
*
* Gets the branch of the application running in the instance.
*
* Returns: the architecture
*
* Since: 1.1
*/
const char *
flatpak_instance_get_branch (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->branch;
}
/**
* flatpak_instance_get_commit:
* @self: a #FlatpakInstance
*
* Gets the commit of the application running in the instance.
*
* Returns: the commit
*
* Since: 1.1
*/
const char *
flatpak_instance_get_commit (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->commit;
}
/**
* flatpak_instance_get_runtime:
* @self: a #FlatpakInstance
*
* Gets the ref of the runtime used in the instance.
*
* Returns: the runtime ref
*
* Since: 1.1
*/
const char *
flatpak_instance_get_runtime (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->runtime;
}
/**
* flatpak_instance_get_runtime_commit:
* @self: a #FlatpakInstance
*
* Gets the commit of the runtime used in the instance.
*
* Returns: the runtime commit
*
* Since: 1.1
*/
const char *
flatpak_instance_get_runtime_commit (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->runtime_commit;
}
/**
* flatpak_instance_get_pid:
* @self: a #FlatpakInstance
*
* Gets the PID of the outermost process in the sandbox. This is not the
* application process itself, but a bubblewrap 'babysitter' process.
*
* See flatpak_instance_get_child_pid().
*
* Returns: the outermost process PID
*
* Since: 1.1
*/
int
flatpak_instance_get_pid (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->pid;
}
static int get_child_pid (const char *dir);
/**
* flatpak_instance_get_child_pid:
* @self: a #FlatpakInstance
*
* Gets the PID of the application process in the sandbox.
*
* See flatpak_instance_get_pid().
*
* Note that this function may return 0 immediately after launching
* a sandbox, for a short amount of time.
*
* Returns: the application process PID
*
* Since: 1.1
*/
int
flatpak_instance_get_child_pid (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
if (priv->child_pid == 0)
priv->child_pid = get_child_pid (priv->dir);
return priv->child_pid;
}
/**
* flatpak_instance_get_info:
* @self: a #FlatpakInstance
*
* Gets a keyfile that holds information about the running sandbox.
*
* This file is available as /.flatpak-info inside the sandbox as well.
*
* The most important data in the keyfile is available with separate getters,
* but there may be more information in the keyfile.
*
* Returns: the flatpak-info keyfile
*
* Since: 1.1
*/
GKeyFile *
flatpak_instance_get_info (FlatpakInstance *self)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
return priv->info;
}
GStrv
flatpak_instance_get_run_environ (FlatpakInstance *self, GError **error)
{
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
g_autofree char *file = NULL;
g_autofree char *environ_data = NULL;
gsize environ_size;
g_auto(GStrv) env_vars = NULL;
file = g_build_filename (priv->private_dir, "run-environ", NULL);
if (!g_file_get_contents (file, &environ_data, &environ_size, error))
return NULL;
env_vars = flatpak_parse_env_block (environ_data, environ_size, error);
if (env_vars == NULL)
return NULL;
return g_steal_pointer (&env_vars);
}
static GKeyFile *
get_instance_info (const char *dir)
{
g_autofree char *file = NULL;
g_autoptr(GKeyFile) key_file = NULL;
g_autoptr(GError) error = NULL;
file = g_build_filename (dir, "info", NULL);
key_file = g_key_file_new ();
if (!g_key_file_load_from_file (key_file, file, G_KEY_FILE_NONE, &error))
{
g_info ("Failed to load instance info file '%s': %s", file, error->message);
return NULL;
}
return g_steal_pointer (&key_file);
}
static int
get_child_pid (const char *dir)
{
g_autofree char *file = NULL;
g_autofree char *contents = NULL;
gsize length;
g_autoptr(GError) error = NULL;
g_autoptr(JsonParser) parser = NULL;
JsonNode *node;
JsonObject *obj;
file = g_build_filename (dir, "bwrapinfo.json", NULL);
if (!g_file_get_contents (file, &contents, &length, &error))
{
g_info ("Failed to load bwrapinfo.json file '%s': %s", file, error->message);
return 0;
}
parser = json_parser_new ();
if (!json_parser_load_from_data (parser, contents, length, &error))
{
g_info ("Failed to parse bwrapinfo.json file '%s': %s", file, error->message);
return 0;
}
node = json_parser_get_root (parser);
if (!node)
{
g_info ("Failed to parse bwrapinfo.json file '%s': %s", file, "empty");
return 0;
}
obj = json_node_get_object (node);
return json_object_get_int_member (obj, "child-pid");
}
static int
get_pid (const char *dir)
{
g_autofree char *file = NULL;
g_autofree char *contents = NULL;
g_autoptr(GError) error = NULL;
file = g_build_filename (dir, "pid", NULL);
if (!g_file_get_contents (file, &contents, NULL, &error))
{
g_info ("Failed to load pid file '%s': %s", file, error->message);
return 0;
}
return (int) g_ascii_strtoll (contents, NULL, 10);
}
FlatpakInstance *
flatpak_instance_new (const char *dir)
{
FlatpakInstance *self = g_object_new (flatpak_instance_get_type (), NULL);
FlatpakInstancePrivate *priv = flatpak_instance_get_instance_private (self);
priv->dir = g_strdup (dir);
priv->private_dir = g_strdup_printf ("%s-private", dir);
priv->id = g_path_get_basename (dir);
priv->pid = get_pid (priv->dir);
priv->child_pid = get_child_pid (priv->dir);
priv->info = get_instance_info (priv->dir);
if (priv->info)
{
if (g_key_file_has_group (priv->info, FLATPAK_METADATA_GROUP_APPLICATION))
{
priv->app = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_APPLICATION, FLATPAK_METADATA_KEY_NAME, NULL);
priv->runtime = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_APPLICATION, FLATPAK_METADATA_KEY_RUNTIME, NULL);
}
else
{
priv->runtime = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_RUNTIME, FLATPAK_METADATA_KEY_RUNTIME, NULL);
}
priv->arch = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_INSTANCE, FLATPAK_METADATA_KEY_ARCH, NULL);
priv->branch = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_INSTANCE, FLATPAK_METADATA_KEY_BRANCH, NULL);
priv->commit = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_INSTANCE, FLATPAK_METADATA_KEY_APP_COMMIT, NULL);
priv->runtime_commit = g_key_file_get_string (priv->info,
FLATPAK_METADATA_GROUP_INSTANCE, FLATPAK_METADATA_KEY_RUNTIME_COMMIT, NULL);
}
return self;
}
/*
* Return the directory in which we create a numbered subdirectory per
* instance.
*
* This directory is not shared with Flatpak apps, and we rely on this
* for the sandbox boundary.
*
* This is currently the same as the
* flatpak_instance_get_apps_directory(). We can distinguish between
* instance IDs and app-IDs because instances are integers, and app-IDs
* always contain at least one dot.
*/
char *
flatpak_instance_get_instances_directory (void)
{
g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();
return g_build_filename (user_runtime_dir, ".flatpak", NULL);
}
/*
* Return the directory in which we create a subdirectory per
* concurrently running Flatpak app-ID to store app-specific data that
* is common to all instances of the same app.
*
* This directory is not shared with Flatpak apps, and we rely on this
* for the sandbox boundary.
*
* This is currently the same as the
* flatpak_instance_get_instances_directory(). We can distinguish between
* instance IDs and app-IDs because instances are integers, and app-IDs
* always contain at least one dot.
*/
char *
flatpak_instance_get_apps_directory (void)
{
return flatpak_instance_get_instances_directory ();
}
/*
* @app_id: $FLATPAK_ID
* @lock_fd_out: (out) (not optional): Used to return a lock on the
* per-app directories
* @lock_path_out: (out) (not optional): Used to return the path to the
* lock file, suitable for bind-mounting into the container
*
* Create a per-app directory and take out a lock on it.
*/
gboolean
flatpak_instance_ensure_per_app_dir (const char *app_id,
int *lock_fd_out,
char **lock_path_out,
GError **error)
{
glnx_autofd int lock_fd = -1;
g_autofree char *lock_path = NULL;
g_autofree char *per_app_parent = NULL;
g_autofree char *per_app_dir = NULL;
struct flock non_exclusive_lock =
{
.l_type = F_RDLCK,
.l_whence = SEEK_SET,
.l_start = 0,
.l_len = 0
};
g_return_val_if_fail (app_id != NULL, FALSE);
g_return_val_if_fail (lock_fd_out != NULL, FALSE);
g_return_val_if_fail (*lock_fd_out == -1, FALSE);
g_return_val_if_fail (lock_path_out != NULL, FALSE);
g_return_val_if_fail (*lock_path_out == NULL, FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
per_app_parent = flatpak_instance_get_apps_directory ();
per_app_dir = g_build_filename (per_app_parent, app_id, NULL);
lock_path = g_build_filename (per_app_dir, ".ref", NULL);
if (g_mkdir_with_parents (per_app_dir, 0700) != 0)
return glnx_throw_errno_prefix (error,
_("Unable to create directory %s"),
per_app_dir);
/* Take a file lock inside the shared directory, and hold it during
* setup and in bwrap. We never delete the directory itself, or the
* lock file that it contains (that would defeat the locking scheme).
* Anyone cleaning up other members of per_app_dir must first verify
* that it contains the lock file .ref, and take out an exclusive lock
* on it. */
lock_fd = open (lock_path, O_RDWR | O_CREAT | O_CLOEXEC, 0600);
/* As with the per-instance directories, there's a race here, because
* we can't atomically open and lock the lockfile. We work around
* that by only doing GC if the lockfile is "old".
*
* If we can't get the lock immediately, that'll be because some other
* process is trying to carry out garbage-collection, so we wait
* for it to finish. */
if (lock_fd < 0 ||
fcntl (lock_fd, F_SETLKW, &non_exclusive_lock) != 0)
return glnx_throw_errno_prefix (error,
_("Unable to lock %s"),
lock_path);
*lock_fd_out = g_steal_fd (&lock_fd);
*lock_path_out = g_steal_pointer (&lock_path);
return TRUE;
}
/*
* @app_id: $FLATPAK_ID
* @per_app_dir_lock_fd: Used to prove that we have already taken out
* a per-app non-exclusive lock to stop this directory from being
* garbage-collected
* @shared_tmp: (out) (not optional): Used to return the path to the
* shared /dev/shm
*
* Create the per-app /dev/shm.
*/
gboolean
flatpak_instance_ensure_per_app_dev_shm (const char *app_id,
int per_app_dir_lock_fd,
char **shared_dev_shm_out,
GError **error)
{
/* This function is actually generic, since we might well want to
* offload other directories in the same way - but the only directory
* we do this for right now is /dev/shm. */
static const char link_name[] = "dev-shm";
static const char parent[] = "/dev/shm";
g_autofree gchar *flag_file = NULL;
g_autofree gchar *path = NULL;
g_autofree gchar *per_app_parent = NULL;
g_autofree gchar *per_app_dir = NULL;
glnx_autofd int flag_fd = -1;
glnx_autofd int per_app_dir_fd = -1;
g_return_val_if_fail (app_id != NULL, FALSE);
g_return_val_if_fail (per_app_dir_lock_fd >= 0, FALSE);
g_return_val_if_fail (shared_dev_shm_out != NULL, FALSE);
g_return_val_if_fail (*shared_dev_shm_out == NULL, FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
per_app_parent = flatpak_instance_get_apps_directory ();
per_app_dir = g_build_filename (per_app_parent, app_id, NULL);
if (!glnx_opendirat (AT_FDCWD, per_app_dir, TRUE,
&per_app_dir_fd,
error))
return FALSE;
/* If there's an existing symlink to a suitable directory, we can
* reuse it (carefully). This gives us the sharing we wanted between
* multiple instances of the same app, and between app and subsandbox. */
if (flatpak_instance_claim_per_app_temp_directory (app_id,
per_app_dir_lock_fd,
per_app_dir_fd,
link_name,
parent,
&path,
NULL))
{
*shared_dev_shm_out = g_steal_pointer (&path);
return TRUE;
}
/* Otherwise create a new directory in @parent, and make @link_name
* a symlink to it. */
/* /dev/shm/flatpak-$FLATPAK_ID-XXXXXX */
path = g_strdup_printf ("%s/flatpak-%s-XXXXXX", parent, app_id);
if (g_mkdtemp (path) == NULL)
return glnx_throw_errno_prefix (error,
_("Unable to create temporary directory in %s"),
parent);
/* This marks this directory as an expendable temp directory, and is
* inspired by the use of .testtmp in libostree. */
flag_file = g_build_filename (path, ".flatpak-tmpdir", NULL);
flag_fd = openat (AT_FDCWD, flag_file,
O_RDONLY | O_CREAT | O_EXCL | O_CLOEXEC | O_ | O_NOCTTY,
0600);
if (flag_fd < 0)
return glnx_throw_errno_prefix (error,
_("Unable to create file %s"),
path);
/* Replace the symlink */
if ((unlinkat (per_app_dir_fd, link_name, 0) < 0 && errno != ENOENT) ||
symlinkat (path, per_app_dir_fd, link_name) < 0)
return glnx_throw_errno_prefix (error,
_("Unable to update symbolic link %s/%s"),
per_app_dir, link_name);
*shared_dev_shm_out = g_steal_pointer (&path);
return TRUE;
}
/*
* @app_id: $FLATPAK_ID
* @per_app_dir_lock_fd: Used to prove that we have already taken out
* a per-app non-exclusive lock to stop this directory from being
* garbage-collected
* @shared_tmp: (out) (not optional) (not nullable): Used to return
* the path to the shared /tmp
*
* Create the per-app /tmp.
*/
gboolean
flatpak_instance_ensure_per_app_tmp (const char *app_id,
int per_app_dir_lock_fd,
char **shared_tmp_out,
GError **error)
{
g_autofree char *per_app_parent = NULL;
g_autofree char *shared_tmp = NULL;
g_return_val_if_fail (app_id != NULL, FALSE);
g_return_val_if_fail (shared_tmp_out != NULL, FALSE);
g_return_val_if_fail (*shared_tmp_out == NULL, FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
/* We don't actually do anything with this, we just pass it in here as
* proof that we already set up the directory that contains the lock
* file for per-app things, to force us to get the sequence right */
g_return_val_if_fail (per_app_dir_lock_fd >= 0, FALSE);
per_app_parent = flatpak_instance_get_apps_directory ();
shared_tmp = g_build_filename (per_app_parent, app_id, "tmp", NULL);
if (g_mkdir_with_parents (shared_tmp, 0700) != 0)
return glnx_throw_errno_prefix (error,
_("Unable to create directory %s"),
shared_tmp);
*shared_tmp_out = g_steal_pointer (&shared_tmp);
return TRUE;
}
/*
* @app_id: $FLATPAK_ID
* @per_app_dir_lock_fd: Used to prove that we have already taken out
* a per-app non-exclusive lock to stop this directory from being
* garbage-collected
* @shared_dir_out: (out) (not optional) (not nullable): Used to return
* the path to the shared $XDG_RUNTIME_DIR
*
* Create a per-app $XDG_RUNTIME_DIR.
*/
gboolean
flatpak_instance_ensure_per_app_xdg_runtime_dir (const char *app_id,
int per_app_dir_lock_fd,
char **shared_dir_out,
GError **error)
{
g_autofree char *per_app_parent = NULL;
g_autofree char *shared_dir = NULL;
g_return_val_if_fail (app_id != NULL, FALSE);
g_return_val_if_fail (shared_dir_out != NULL, FALSE);
g_return_val_if_fail (*shared_dir_out == NULL, FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
/* We don't actually do anything with this, we just pass it in here as
* proof that we already set up the directory that contains the lock
* file for per-app things, to force us to get the sequence right */
g_return_val_if_fail (per_app_dir_lock_fd >= 0, FALSE);
per_app_parent = flatpak_instance_get_apps_directory ();
shared_dir = g_build_filename (per_app_parent, app_id, "xdg-run", NULL);
if (g_mkdir_with_parents (shared_dir, 0700) != 0)
return glnx_throw_errno_prefix (error,
_("Unable to create directory %s"),
shared_dir);
*shared_dir_out = g_steal_pointer (&shared_dir);
return TRUE;
}
static int
flatpak_instance_create_lock_file (const char *instance_dir)
{
g_autofree char *lock_file = g_build_filename (instance_dir, ".ref", NULL);
glnx_autofd int lock_fd = -1;
struct flock l = {
.l_type = F_RDLCK,
.l_whence = SEEK_SET,
.l_start = 0,
.l_len = 0
};
/* Take a file lock inside the dir, hold that during setup
* and in bwrap. Anyone trying to clean up unused directories
* need to first verify that there is a .ref file and take a
* write lock on .ref to ensure it is not in use.
*/
lock_fd = open (lock_file, O_RDWR | O_CREAT | O_CLOEXEC, 0644);
/* There is a tiny race here between the open creating the file and the lock succeeding.
We work around that by only gc:ing "old" .ref files */
if (lock_fd == -1 || fcntl (lock_fd, F_SETLK, &l) != 0)
return -1;
return g_steal_fd (&lock_fd);
}
/*
* @host_dir_out: (not optional): used to return the directory on the host
* system representing this instance
* @lock_fd_out: (not optional): used to return a non-exclusive (read) lock
* on the lockdirectory on the host-file
*/
char *
flatpak_instance_allocate_id (char **host_dir_out,
char **host_private_dir_out,
int *lock_fd_out)
{
g_autofree char *base_dir = flatpak_instance_get_instances_directory ();
int count;
g_return_val_if_fail (host_dir_out != NULL, NULL);
g_return_val_if_fail (*host_dir_out == NULL, NULL);
g_return_val_if_fail (host_private_dir_out != NULL, NULL);
g_return_val_if_fail (*host_private_dir_out == NULL, NULL);
g_return_val_if_fail (lock_fd_out != NULL, NULL);
g_return_val_if_fail (*lock_fd_out == -1, NULL);
if (g_mkdir_with_parents (base_dir, 0755) != 0)
return NULL;
flatpak_instance_iterate_all_and_gc (NULL);
for (count = 0; count < 1000; count++)
{
g_autofree char *instance_id = NULL;
g_autofree char *instance_dir = NULL;
g_autofree char *instance_private_dir = NULL;
glnx_autofd int lock_fd = -1;
instance_id = g_strdup_printf ("%u", g_random_int ());
instance_dir = g_build_filename (base_dir, instance_id, NULL);
instance_private_dir = g_strdup_printf ("%s-private", instance_dir);
/* We use an atomic mkdir to ensure the instance id is unique */
if (mkdir (instance_dir, 0755) != 0)
continue;
lock_fd = flatpak_instance_create_lock_file (instance_dir);
if (lock_fd == -1)
continue;
if (mkdir (instance_private_dir, 0700) != 0)
{
g_warning ("Could not create private instance directory '%s': %s",
instance_private_dir, g_strerror (errno));
continue;
}
*lock_fd_out = g_steal_fd (&lock_fd);
g_info ("Allocated instance id %s", instance_id);
*host_dir_out = g_steal_pointer (&instance_dir);
*host_private_dir_out = g_steal_pointer (&instance_private_dir);
return g_steal_pointer (&instance_id);
}
return NULL;
}
FlatpakInstance *
flatpak_instance_new_for_id (const char *id)
{
g_autofree char *base_dir = flatpak_instance_get_instances_directory ();
g_autofree char *dir = NULL;
dir = g_build_filename (base_dir, id, NULL);
return flatpak_instance_new (dir);
}
/*
* flatpak_instance_claim_per_app_temp_directory:
* @app_id: $FLATPAK_ID
* @per_app_dir_lock_fd: Lock representing shared or exclusive access
* to directories created for @app_id
* @at_fd: Directory in which to look up @link_path
* @link_path: Path of a symbolic link to a subdirectory of @parent
* @parent: The directory in which we created the temporary directory,
* such as /dev/shm or /tmp
* @path_out: (out) (not optional): Return the path to the directory
* referenced by @link_path
*
* Try to take control of an existing per-app temporary directory
* referenced by @link_path, either for reuse or for deletion.
* Return %TRUE if we can.
*
* This is currently only used for /dev/shm, but it's designed to be
* equally usable for other non-user-owned directories like /tmp.
*
* We have to be careful here, because @link_path might be left over
* from a previous boot, and it probably points into a directory like
* /dev/shm or /tmp, where an attacker might recreate our directories,
* for example as symbolic links to somewhere they control. As a result,
* this function is security-sensitive, and needs to follow a policy of
* failing when an unexpected situation is detected.
*
* @error is not normally user-visible, and is mostly present to support
* debugging and unit testing.
*
* Returns: %TRUE if @link_path points to a suitable directory,
* or %FALSE with @error set if it does not.
*/
gboolean
flatpak_instance_claim_per_app_temp_directory (const char *app_id,
int per_app_dir_lock_fd,
int at_fd,
const char *link_path,
const char *parent,
char **path_out,
GError **error)
{
g_autofree char *reuse_path = NULL;
glnx_autofd int dfd = -1;
glnx_autofd int flag_fd = -1;
struct stat statbuf;
const char *slash;
const char *rest;
at_fd = glnx_dirfd_canonicalize (at_fd);
g_return_val_if_fail (app_id != NULL, FALSE);
g_return_val_if_fail (per_app_dir_lock_fd >= 0, FALSE);
g_return_val_if_fail (at_fd == AT_FDCWD || at_fd >= 0, FALSE);
g_return_val_if_fail (link_path != NULL, FALSE);
g_return_val_if_fail (parent != NULL, FALSE);
g_return_val_if_fail (path_out != NULL, FALSE);
g_return_val_if_fail (*path_out == NULL, FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
reuse_path = glnx_readlinkat_malloc (at_fd, link_path, NULL, error);
if (reuse_path == NULL)
return FALSE;
/* If we're going to use it as /dev/shm, the directory on the
* host should match /dev/shm/flatpak-$FLATPAK_ID-XXXXXX */
if (!g_str_has_prefix (reuse_path, parent))
return glnx_throw (error, "%s does not start with %s",
reuse_path, parent);
/* /flatpak-$FLATPAK_ID-XXXXXX */
slash = reuse_path + strlen (parent);
if (*slash != '/')
return glnx_throw (error, "%s does not start with %s/",
reuse_path, parent);
/* flatpak-$FLATPAK_ID-XXXXXX */
rest = slash + 1;
if (!g_str_has_prefix (rest, "flatpak-"))
return glnx_throw (error, "%s does not start with %s/flatpak-",
reuse_path, parent);
if (strchr (rest, '/') != NULL)
return glnx_throw (error, "%s has too many directory separators",
reuse_path);
if (!g_str_has_prefix (rest + strlen ("flatpak-"), app_id))
return glnx_throw (error, "%s does not start with %s/flatpak-%s",
reuse_path, parent, app_id);
if (rest[strlen ("flatpak-") + strlen (app_id)] != '-')
return glnx_throw (error, "%s does not start with %s/flatpak-%s-",
reuse_path, parent, app_id);
/* Avoid symlink attacks by not following symlinks */
if (!glnx_opendirat (AT_FDCWD, reuse_path, FALSE,
&dfd,
error))
return FALSE;
if (fstat (dfd, &statbuf) < 0)
return glnx_throw_errno_prefix (error, "fstat %s", reuse_path);
/* We certainly don't want to reuse someone else's directory */
if (statbuf.st_uid != geteuid ())
return glnx_throw (error, "%s does not belong to this user", reuse_path);
flag_fd = openat (dfd, ".flatpak-tmpdir",
O_RDONLY | O_CLOEXEC | O_ | O_NOCTTY);
/* If we can't open the flag file, the most likely reason is that it
* isn't a directory that we created */
if (flag_fd < 0)
return glnx_throw_errno_prefix (error, "opening flag file %s/.flatpak-tmpdir",
reuse_path);
*path_out = g_steal_pointer (&reuse_path);
return TRUE;
}
/*
* The @error is not intended to be user-facing, and is there for
* testing/debugging.
*/
static gboolean
flatpak_instance_gc_per_app_dirs (const char *instance_id,
GError **error)
{
g_autofree char *per_instance_parent = NULL;
g_autofree char *per_app_parent = NULL;
g_autofree char *app_id = NULL;
g_autofree char *instance_dir = NULL;
g_autofree char *per_app_dir = NULL;
glnx_autofd int per_app_dir_fd = -1;
glnx_autofd int per_app_dir_lock_fd = -1;
g_autoptr(GError) local_error = NULL;
g_autoptr(GKeyFile) key_file = NULL;
struct flock exclusive_lock =
{
.l_type = F_WRLCK,
.l_whence = SEEK_SET,
.l_start = 0,
.l_len = 0,
};
struct stat statbuf;
per_instance_parent = flatpak_instance_get_instances_directory ();
per_app_parent = flatpak_instance_get_apps_directory ();
instance_dir = g_build_filename (per_instance_parent, instance_id, NULL);
key_file = get_instance_info (instance_dir);
if (key_file == NULL)
return glnx_throw (error, "Unable to load keyfile %s/info", instance_dir);
if (g_key_file_has_group (key_file, FLATPAK_METADATA_GROUP_APPLICATION))
app_id = g_key_file_get_string (key_file,
FLATPAK_METADATA_GROUP_APPLICATION,
FLATPAK_METADATA_KEY_NAME, error);
else
app_id = g_key_file_get_string (key_file,
FLATPAK_METADATA_GROUP_RUNTIME,
FLATPAK_METADATA_KEY_RUNTIME, error);
if (app_id == NULL)