summaryrefslogtreecommitdiffstats
path: root/src/shared/mount-util.c
blob: 4f2acce513d4109ee0061f57d70a6111089fabbd (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
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <errno.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <unistd.h>
#include <linux/loop.h>
#if WANT_LINUX_FS_H
#include <linux/fs.h>
#endif

#include "alloc-util.h"
#include "chase.h"
#include "dissect-image.h"
#include "exec-util.h"
#include "extract-word.h"
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "glyph-util.h"
#include "hashmap.h"
#include "initrd-util.h"
#include "label-util.h"
#include "libmount-util.h"
#include "missing_mount.h"
#include "missing_syscall.h"
#include "mkdir-label.h"
#include "mount-util.h"
#include "mountpoint-util.h"
#include "namespace-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "set.h"
#include "sort-util.h"
#include "stat-util.h"
#include "stdio-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "tmpfile-util.h"
#include "user-util.h"

int umount_recursive_full(const char *prefix, int flags, char **keep) {
        _cleanup_fclose_ FILE *f = NULL;
        int n = 0, r;

        /* Try to umount everything recursively below a directory. Also, take care of stacked mounts, and
         * keep unmounting them until they are gone. */

        f = fopen("/proc/self/mountinfo", "re"); /* Pin the file, in case we unmount /proc/ as part of the logic here */
        if (!f)
                return log_debug_errno(errno, "Failed to open /proc/self/mountinfo: %m");

        for (;;) {
                _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
                _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
                bool again = false;

                r = libmount_parse("/proc/self/mountinfo", f, &table, &iter);
                if (r < 0)
                        return log_debug_errno(r, "Failed to parse /proc/self/mountinfo: %m");

                for (;;) {
                        bool shall_keep = false;
                        struct libmnt_fs *fs;
                        const char *path;

                        r = mnt_table_next_fs(table, iter, &fs);
                        if (r == 1)
                                break;
                        if (r < 0)
                                return log_debug_errno(r, "Failed to get next entry from /proc/self/mountinfo: %m");

                        path = mnt_fs_get_target(fs);
                        if (!path)
                                continue;

                        if (prefix && !path_startswith(path, prefix)) {
                                log_trace("Not unmounting %s, outside of prefix: %s", path, prefix);
                                continue;
                        }

                        STRV_FOREACH(k, keep)
                                /* Match against anything in the path to the dirs to keep, or below the dirs to keep */
                                if (path_startswith(path, *k) || path_startswith(*k, path)) {
                                        shall_keep = true;
                                        break;
                                }
                        if (shall_keep) {
                                log_debug("Not unmounting %s, referenced by keep list.", path);
                                continue;
                        }

                        if (umount2(path, flags | UMOUNT_NOFOLLOW) < 0) {
                                log_debug_errno(errno, "Failed to umount %s, ignoring: %m", path);
                                continue;
                        }

                        log_trace("Successfully unmounted %s", path);

                        again = true;
                        n++;

                        break;
                }

                if (!again)
                        break;

                rewind(f);
        }

        return n;
}

#define MS_CONVERTIBLE_FLAGS (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_NOSYMFOLLOW)

static uint64_t ms_flags_to_mount_attr(unsigned long a) {
        uint64_t f = 0;

        if (FLAGS_SET(a, MS_RDONLY))
                f |= MOUNT_ATTR_RDONLY;

        if (FLAGS_SET(a, MS_NOSUID))
                f |= MOUNT_ATTR_NOSUID;

        if (FLAGS_SET(a, MS_NODEV))
                f |= MOUNT_ATTR_NODEV;

        if (FLAGS_SET(a, MS_NOEXEC))
                f |= MOUNT_ATTR_NOEXEC;

        if (FLAGS_SET(a, MS_NOSYMFOLLOW))
                f |= MOUNT_ATTR_NOSYMFOLLOW;

        return f;
}

static bool skip_mount_set_attr = false;

/* Use this function only if you do not have direct access to /proc/self/mountinfo but the caller can open it
 * for you. This is the case when /proc is masked or not mounted. Otherwise, use bind_remount_recursive. */
int bind_remount_recursive_with_mountinfo(
                const char *prefix,
                unsigned long new_flags,
                unsigned long flags_mask,
                char **deny_list,
                FILE *proc_self_mountinfo) {

        _cleanup_fclose_ FILE *proc_self_mountinfo_opened = NULL;
        _cleanup_set_free_ Set *done = NULL;
        unsigned n_tries = 0;
        int r;

        assert(prefix);

        if ((flags_mask & ~MS_CONVERTIBLE_FLAGS) == 0 && strv_isempty(deny_list) && !skip_mount_set_attr) {
                /* Let's take a shortcut for all the flags we know how to convert into mount_setattr() flags */

                if (mount_setattr(AT_FDCWD, prefix, AT_SYMLINK_NOFOLLOW|AT_RECURSIVE,
                                  &(struct mount_attr) {
                                          .attr_set = ms_flags_to_mount_attr(new_flags & flags_mask),
                                          .attr_clr = ms_flags_to_mount_attr(~new_flags & flags_mask),
                                  }, MOUNT_ATTR_SIZE_VER0) < 0) {

                        log_debug_errno(errno, "mount_setattr() failed, falling back to classic remounting: %m");

                        /* We fall through to classic behaviour if not supported (i.e. kernel < 5.12). We
                         * also do this for all other kinds of errors since they are so many different, and
                         * mount_setattr() has no graceful mode where it continues despite seeing errors one
                         * some mounts, but we want that. Moreover mount_setattr() only works on the mount
                         * point inode itself, not a non-mount point inode, and we want to support arbitrary
                         * prefixes here. */

                        if (ERRNO_IS_NOT_SUPPORTED(errno)) /* if not supported, then don't bother at all anymore */
                                skip_mount_set_attr = true;
                } else
                        return 0; /* Nice, this worked! */
        }

        if (!proc_self_mountinfo) {
                r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo_opened);
                if (r < 0)
                        return r;

                proc_self_mountinfo = proc_self_mountinfo_opened;
        }

        /* Recursively remount a directory (and all its submounts) with desired flags (MS_READONLY,
         * MS_NOSUID, MS_NOEXEC). If the directory is already mounted, we reuse the mount and simply mark it
         * MS_BIND|MS_RDONLY (or remove the MS_RDONLY for read-write operation), ditto for other flags. If it
         * isn't we first make it one. Afterwards we apply (or remove) the flags to all submounts we can
         * access, too. When mounts are stacked on the same mount point we only care for each individual
         * "top-level" mount on each point, as we cannot influence/access the underlying mounts anyway. We do
         * not have any effect on future submounts that might get propagated, they might be writable
         * etc. This includes future submounts that have been triggered via autofs. Also note that we can't
         * operate atomically here. Mounts established while we process the tree might or might not get
         * noticed and thus might or might not be covered.
         *
         * If the "deny_list" parameter is specified it may contain a list of subtrees to exclude from the
         * remount operation. Note that we'll ignore the deny list for the top-level path. */

        for (;;) {
                _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
                _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
                _cleanup_hashmap_free_ Hashmap *todo = NULL;
                bool top_autofs = false;

                if (n_tries++ >= 32) /* Let's not retry this loop forever */
                        return -EBUSY;

                rewind(proc_self_mountinfo);

                r = libmount_parse("/proc/self/mountinfo", proc_self_mountinfo, &table, &iter);
                if (r < 0)
                        return log_debug_errno(r, "Failed to parse /proc/self/mountinfo: %m");

                for (;;) {
                        _cleanup_free_ char *d = NULL;
                        const char *path, *type, *opts;
                        unsigned long flags = 0;
                        struct libmnt_fs *fs;

                        r = mnt_table_next_fs(table, iter, &fs);
                        if (r == 1) /* EOF */
                                break;
                        if (r < 0)
                                return log_debug_errno(r, "Failed to get next entry from /proc/self/mountinfo: %m");

                        path = mnt_fs_get_target(fs);
                        if (!path)
                                continue;

                        if (!path_startswith(path, prefix))
                                continue;

                        type = mnt_fs_get_fstype(fs);
                        if (!type)
                                continue;

                        /* Let's ignore autofs mounts. If they aren't triggered yet, we want to avoid
                         * triggering them, as we don't make any guarantees for future submounts anyway. If
                         * they are already triggered, then we will find another entry for this. */
                        if (streq(type, "autofs")) {
                                top_autofs = top_autofs || path_equal(path, prefix);
                                continue;
                        }

                        if (set_contains(done, path))
                                continue;

                        /* Ignore this mount if it is deny-listed, but only if it isn't the top-level mount
                         * we shall operate on. */
                        if (!path_equal(path, prefix)) {
                                bool deny_listed = false;

                                STRV_FOREACH(i, deny_list) {
                                        if (path_equal(*i, prefix))
                                                continue;

                                        if (!path_startswith(*i, prefix))
                                                continue;

                                        if (path_startswith(path, *i)) {
                                                deny_listed = true;
                                                log_trace("Not remounting %s deny-listed by %s, called for %s", path, *i, prefix);
                                                break;
                                        }
                                }

                                if (deny_listed)
                                        continue;
                        }

                        opts = mnt_fs_get_vfs_options(fs);
                        if (opts) {
                                r = mnt_optstr_get_flags(opts, &flags, mnt_get_builtin_optmap(MNT_LINUX_MAP));
                                if (r < 0)
                                        log_debug_errno(r, "Could not get flags for '%s', ignoring: %m", path);
                        }

                        d = strdup(path);
                        if (!d)
                                return -ENOMEM;

                        r = hashmap_ensure_put(&todo, &path_hash_ops_free, d, ULONG_TO_PTR(flags));
                        if (r == -EEXIST)
                                /* If the same path was recorded, but with different mount flags, update it:
                                 * it means a mount point is overmounted, and libmount returns the "bottom" (or
                                 * older one) first, but we want to reapply the flags from the "top" (or newer
                                 * one). See: https://github.com/systemd/systemd/issues/20032
                                 * Note that this shouldn't really fail, as we were just told that the key
                                 * exists, and it's an update so we want 'd' to be freed immediately. */
                                r = hashmap_update(todo, d, ULONG_TO_PTR(flags));
                        if (r < 0)
                                return r;
                        if (r > 0)
                                TAKE_PTR(d);
                }

                /* Check if the top-level directory was among what we have seen so far. For that check both
                 * 'done' and 'todo'. Also check 'top_autofs' because if the top-level dir is an autofs we'll
                 * not include it in either set but will set this bool. */
                if (!set_contains(done, prefix) &&
                    !(top_autofs || hashmap_contains(todo, prefix))) {

                        /* The prefix directory itself is not yet a mount, make it one. */
                        r = mount_nofollow(prefix, prefix, NULL, MS_BIND|MS_REC, NULL);
                        if (r < 0)
                                return r;

                        /* Immediately rescan, so that we pick up the new mount's flags */
                        continue;
                }

                /* If we have no submounts to process anymore, we are done */
                if (hashmap_isempty(todo))
                        return 0;

                for (;;) {
                        unsigned long flags;
                        char *x = NULL;

                        /* Take the first mount from our list of mounts to still process */
                        flags = PTR_TO_ULONG(hashmap_steal_first_key_and_value(todo, (void**) &x));
                        if (!x)
                                break;

                        r = set_ensure_consume(&done, &path_hash_ops_free, x);
                        if (IN_SET(r, 0, -EEXIST))
                                continue; /* Already done */
                        if (r < 0)
                                return r;

                        /* Now, remount this with the new flags set, but exclude MS_RELATIME from it. (It's
                         * the default anyway, thus redundant, and in userns we'll get an error if we try to
                         * explicitly enable it) */
                        r = mount_nofollow(NULL, x, NULL, ((flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags) & ~MS_RELATIME, NULL);
                        if (r < 0) {
                                int q;

                                /* OK, so the remount of this entry failed. We'll ultimately ignore this in
                                 * almost all cases (there are simply so many reasons why this can fail,
                                 * think autofs, NFS, FUSE, …), but let's generate useful debug messages at
                                 * the very least. */

                                q = path_is_mount_point(x, NULL, 0);
                                if (IN_SET(q, 0, -ENOENT)) {
                                        /* Hmm, whaaaa? The mount point is not actually a mount point? Then
                                         * it is either obstructed by a later mount or somebody has been
                                         * racing against us and removed it. Either way the mount point
                                         * doesn't matter to us, let's ignore it hence. */
                                        log_debug_errno(r, "Mount point '%s' to remount is not a mount point anymore, ignoring remount failure: %m", x);
                                        continue;
                                }
                                if (q < 0) /* Any other error on this? Just log and continue */
                                        log_debug_errno(q, "Failed to determine whether '%s' is a mount point or not, ignoring: %m", x);

                                if (((flags ^ new_flags) & flags_mask & ~MS_RELATIME) == 0) { /* ignore MS_RELATIME while comparing */
                                        log_debug_errno(r, "Couldn't remount '%s', but the flags already match what we want, hence ignoring: %m", x);
                                        continue;
                                }

                                /* Make this fatal if this is the top-level mount */
                                if (path_equal(x, prefix))
                                        return r;

                                /* If this is not the top-level mount, then handle this gracefully: log but
                                 * otherwise ignore. With NFS, FUSE, autofs there are just too many reasons
                                 * this might fail without a chance for us to do anything about it, let's
                                 * hence be strict on the top-level mount and lenient on the inner ones. */
                                log_debug_errno(r, "Couldn't remount submount '%s' for unexpected reason, ignoring: %m", x);
                                continue;
                        }

                        log_trace("Remounted %s.", x);
                }
        }
}

int bind_remount_one_with_mountinfo(
                const char *path,
                unsigned long new_flags,
                unsigned long flags_mask,
                FILE *proc_self_mountinfo) {

        _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
        unsigned long flags = 0;
        struct libmnt_fs *fs;
        const char *opts;
        int r;

        assert(path);
        assert(proc_self_mountinfo);

        if ((flags_mask & ~MS_CONVERTIBLE_FLAGS) == 0 && !skip_mount_set_attr) {
                /* Let's take a shortcut for all the flags we know how to convert into mount_setattr() flags */

                if (mount_setattr(AT_FDCWD, path, AT_SYMLINK_NOFOLLOW,
                                  &(struct mount_attr) {
                                          .attr_set = ms_flags_to_mount_attr(new_flags & flags_mask),
                                          .attr_clr = ms_flags_to_mount_attr(~new_flags & flags_mask),
                                  }, MOUNT_ATTR_SIZE_VER0) < 0) {

                        log_debug_errno(errno, "mount_setattr() didn't work, falling back to classic remounting: %m");

                        if (ERRNO_IS_NOT_SUPPORTED(errno)) /* if not supported, then don't bother at all anymore */
                                skip_mount_set_attr = true;
                } else
                        return 0; /* Nice, this worked! */
        }

        rewind(proc_self_mountinfo);

        table = mnt_new_table();
        if (!table)
                return -ENOMEM;

        r = mnt_table_parse_stream(table, proc_self_mountinfo, "/proc/self/mountinfo");
        if (r < 0)
                return r;

        fs = mnt_table_find_target(table, path, MNT_ITER_FORWARD);
        if (!fs) {
                if (laccess(path, F_OK) < 0) /* Hmm, it's not in the mount table, but does it exist at all? */
                        return -errno;

                return -EINVAL; /* Not a mount point we recognize */
        }

        opts = mnt_fs_get_vfs_options(fs);
        if (opts) {
                r = mnt_optstr_get_flags(opts, &flags, mnt_get_builtin_optmap(MNT_LINUX_MAP));
                if (r < 0)
                        log_debug_errno(r, "Could not get flags for '%s', ignoring: %m", path);
        }

        r = mount_nofollow(NULL, path, NULL, ((flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags) & ~MS_RELATIME, NULL);
        if (r < 0) {
                if (((flags ^ new_flags) & flags_mask & ~MS_RELATIME) != 0) /* Ignore MS_RELATIME again,
                                                                             * since kernel adds it in
                                                                             * everywhere, because it's the
                                                                             * default. */
                        return r;

                /* Let's handle redundant remounts gracefully */
                log_debug_errno(r, "Failed to remount '%s' but flags already match what we want, ignoring: %m", path);
        }

        return 0;
}

static int mount_switch_root_pivot(int fd_newroot, const char *path) {
        assert(fd_newroot >= 0);
        assert(path);

        /* Change into the new rootfs. */
        if (fchdir(fd_newroot) < 0)
                return log_debug_errno(errno, "Failed to chdir into new rootfs '%s': %m", path);

        /* Let the kernel tuck the new root under the old one. */
        if (pivot_root(".", ".") < 0)
                return log_debug_errno(errno, "Failed to pivot root to new rootfs '%s': %m", path);

        /* Get rid of the old root and reveal our brand new root. (This will always operate on the top-most
         * mount on our cwd, regardless what our current directory actually points to.) */
        if (umount2(".", MNT_DETACH) < 0)
                return log_debug_errno(errno, "Failed to unmount old rootfs: %m");

        return 0;
}

static int mount_switch_root_move(int fd_newroot, const char *path) {
        assert(fd_newroot >= 0);
        assert(path);

        /* Change into the new rootfs. */
        if (fchdir(fd_newroot) < 0)
                return log_debug_errno(errno, "Failed to chdir into new rootfs '%s': %m", path);

        /* Move the new root fs */
        if (mount(".", "/", NULL, MS_MOVE, NULL) < 0)
                return log_debug_errno(errno, "Failed to move new rootfs '%s': %m", path);

        /* Also change root dir */
        if (chroot(".") < 0)
                return log_debug_errno(errno, "Failed to chroot to new rootfs '%s': %m", path);

        return 0;
}

int mount_switch_root_full(const char *path, unsigned long mount_propagation_flag, bool force_ms_move) {
        _cleanup_close_ int fd_newroot = -EBADF;
        int r;

        assert(path);
        assert(mount_propagation_flag_is_valid(mount_propagation_flag));

        fd_newroot = open(path, O_PATH|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
        if (fd_newroot < 0)
                return log_debug_errno(errno, "Failed to open new rootfs '%s': %m", path);

        if (!force_ms_move) {
                r = mount_switch_root_pivot(fd_newroot, path);
                if (r < 0) {
                        log_debug_errno(r, "Failed to pivot into new rootfs '%s', will try to use MS_MOVE instead: %m", path);
                        force_ms_move = true;
                }
        }
        if (force_ms_move) {
                /* Failed to pivot_root() fallback to MS_MOVE. For example, this may happen if the rootfs is
                 * an initramfs in which case pivot_root() isn't supported. */
                r = mount_switch_root_move(fd_newroot, path);
                if (r < 0)
                        return log_debug_errno(r, "Failed to switch to new rootfs '%s' with MS_MOVE: %m", path);
        }

        /* Finally, let's establish the requested propagation flags. */
        if (mount_propagation_flag == 0)
                return 0;

        if (mount(NULL, ".", NULL, mount_propagation_flag | MS_REC, 0) < 0)
                return log_debug_errno(errno, "Failed to turn new rootfs '%s' into %s mount: %m",
                                       mount_propagation_flag_to_string(mount_propagation_flag), path);

        return 0;
}

int repeat_unmount(const char *path, int flags) {
        bool done = false;

        assert(path);

        /* If there are multiple mounts on a mount point, this
         * removes them all */

        for (;;) {
                if (umount2(path, flags) < 0) {

                        if (errno == EINVAL)
                                return done;

                        return -errno;
                }

                done = true;
        }
}

int mode_to_inaccessible_node(
                const char *runtime_dir,
                mode_t mode,
                char **ret) {

        /* This function maps a node type to a corresponding inaccessible file node. These nodes are created
         * during early boot by PID 1. In some cases we lacked the privs to create the character and block
         * devices (maybe because we run in an userns environment, or miss CAP_SYS_MKNOD, or run with a
         * devices policy that excludes device nodes with major and minor of 0), but that's fine, in that
         * case we use an AF_UNIX file node instead, which is not the same, but close enough for most
         * uses. And most importantly, the kernel allows bind mounts from socket nodes to any non-directory
         * file nodes, and that's the most important thing that matters.
         *
         * Note that the runtime directory argument shall be the top-level runtime directory, i.e. /run/ if
         * we operate in system context and $XDG_RUNTIME_DIR if we operate in user context. */

        _cleanup_free_ char *d = NULL;
        const char *node;

        assert(ret);

        if (!runtime_dir)
                runtime_dir = "/run";

        if (S_ISLNK(mode))
                return -EINVAL;

        node = inode_type_to_string(mode);
        if (!node)
                return -EINVAL;

        d = path_join(runtime_dir, "systemd/inaccessible", node);
        if (!d)
                return -ENOMEM;

        /* On new kernels unprivileged users are permitted to create 0:0 char device nodes (because they also
         * act as whiteout inode for overlayfs), but no other char or block device nodes. On old kernels no
         * device node whatsoever may be created by unprivileged processes. Hence, if the caller asks for the
         * inaccessible block device node let's see if the block device node actually exists, and if not,
         * fall back to the character device node. From there fall back to the socket device node. This means
         * in the best case we'll get the right device node type — but if not we'll hopefully at least get a
         * device node at all. */

        if (S_ISBLK(mode) &&
            access(d, F_OK) < 0 && errno == ENOENT) {
                free(d);
                d = path_join(runtime_dir, "/systemd/inaccessible/chr");
                if (!d)
                        return -ENOMEM;
        }

        if (IN_SET(mode & S_IFMT, S_IFBLK, S_IFCHR) &&
            access(d, F_OK) < 0 && errno == ENOENT) {
                free(d);
                d = path_join(runtime_dir, "/systemd/inaccessible/sock");
                if (!d)
                        return -ENOMEM;
        }

        *ret = TAKE_PTR(d);
        return 0;
}

int mount_flags_to_string(unsigned long flags, char **ret) {
        static const struct {
                unsigned long flag;
                const char *name;
        } map[] = {
                { .flag = MS_RDONLY,      .name = "MS_RDONLY",      },
                { .flag = MS_NOSUID,      .name = "MS_NOSUID",      },
                { .flag = MS_NODEV,       .name = "MS_NODEV",       },
                { .flag = MS_NOEXEC,      .name = "MS_NOEXEC",      },
                { .flag = MS_SYNCHRONOUS, .name = "MS_SYNCHRONOUS", },
                { .flag = MS_REMOUNT,     .name = "MS_REMOUNT",     },
                { .flag = MS_MANDLOCK,    .name = "MS_MANDLOCK",    },
                { .flag = MS_DIRSYNC,     .name = "MS_DIRSYNC",     },
                { .flag = MS_NOSYMFOLLOW, .name = "MS_NOSYMFOLLOW", },
                { .flag = MS_NOATIME,     .name = "MS_NOATIME",     },
                { .flag = MS_NODIRATIME,  .name = "MS_NODIRATIME",  },
                { .flag = MS_BIND,        .name = "MS_BIND",        },
                { .flag = MS_MOVE,        .name = "MS_MOVE",        },
                { .flag = MS_REC,         .name = "MS_REC",         },
                { .flag = MS_SILENT,      .name = "MS_SILENT",      },
                { .flag = MS_POSIXACL,    .name = "MS_POSIXACL",    },
                { .flag = MS_UNBINDABLE,  .name = "MS_UNBINDABLE",  },
                { .flag = MS_PRIVATE,     .name = "MS_PRIVATE",     },
                { .flag = MS_SLAVE,       .name = "MS_SLAVE",       },
                { .flag = MS_SHARED,      .name = "MS_SHARED",      },
                { .flag = MS_RELATIME,    .name = "MS_RELATIME",    },
                { .flag = MS_KERNMOUNT,   .name = "MS_KERNMOUNT",   },
                { .flag = MS_I_VERSION,   .name = "MS_I_VERSION",   },
                { .flag = MS_STRICTATIME, .name = "MS_STRICTATIME", },
                { .flag = MS_LAZYTIME,    .name = "MS_LAZYTIME",    },
        };
        _cleanup_free_ char *str = NULL;

        assert(ret);

        for (size_t i = 0; i < ELEMENTSOF(map); i++)
                if (flags & map[i].flag) {
                        if (!strextend_with_separator(&str, "|", map[i].name))
                                return -ENOMEM;
                        flags &= ~map[i].flag;
                }

        if (!str || flags != 0)
                if (strextendf_with_separator(&str, "|", "%lx", flags) < 0)
                        return -ENOMEM;

        *ret = TAKE_PTR(str);
        return 0;
}

int mount_verbose_full(
                int error_log_level,
                const char *what,
                const char *where,
                const char *type,
                unsigned long flags,
                const char *options,
                bool follow_symlink) {

        _cleanup_free_ char *fl = NULL, *o = NULL;
        unsigned long f;
        int r;

        r = mount_option_mangle(options, flags, &f, &o);
        if (r < 0)
                return log_full_errno(error_log_level, r,
                                      "Failed to mangle mount options %s: %m",
                                      strempty(options));

        (void) mount_flags_to_string(f, &fl);

        if (FLAGS_SET(f, MS_REMOUNT|MS_BIND))
                log_debug("Changing mount flags %s (%s \"%s\")...",
                          where, strnull(fl), strempty(o));
        else if (f & MS_REMOUNT)
                log_debug("Remounting superblock %s (%s \"%s\")...",
                          where, strnull(fl), strempty(o));
        else if (f & (MS_SHARED|MS_PRIVATE|MS_SLAVE|MS_UNBINDABLE))
                log_debug("Changing mount propagation %s (%s \"%s\")",
                          where, strnull(fl), strempty(o));
        else if (f & MS_BIND)
                log_debug("Bind-mounting %s on %s (%s \"%s\")...",
                          what, where, strnull(fl), strempty(o));
        else if (f & MS_MOVE)
                log_debug("Moving mount %s %s %s (%s \"%s\")...",
                          what, special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), where, strnull(fl), strempty(o));
        else
                log_debug("Mounting %s (%s) on %s (%s \"%s\")...",
                          strna(what), strna(type), where, strnull(fl), strempty(o));

        if (follow_symlink)
                r = RET_NERRNO(mount(what, where, type, f, o));
        else
                r = mount_nofollow(what, where, type, f, o);
        if (r < 0)
                return log_full_errno(error_log_level, r,
                                      "Failed to mount %s (type %s) on %s (%s \"%s\"): %m",
                                      strna(what), strna(type), where, strnull(fl), strempty(o));
        return 0;
}

int umount_verbose(
                int error_log_level,
                const char *what,
                int flags) {

        assert(what);

        log_debug("Umounting %s...", what);

        if (umount2(what, flags) < 0)
                return log_full_errno(error_log_level, errno,
                                      "Failed to unmount %s: %m", what);

        return 0;
}

int mount_exchange_graceful(int fsmount_fd, const char *dest, bool mount_beneath) {
        int r;

        assert(fsmount_fd >= 0);
        assert(dest);

        /* First, try to mount beneath an existing mount point, and if that works, umount the old mount,
         * which is now at the top. This will ensure we can atomically replace a mount. Note that this works
         * also in the case where there are submounts down the tree. Mount propagation is allowed but
         * restricted to layouts that don't end up propagation the new mount on top of the mount stack.  If
         * this is not supported (minimum kernel v6.5), or if there is no mount on the mountpoint, we get
         * -EINVAL and then we fallback to normal mounting. */

        r = RET_NERRNO(move_mount(
                        fsmount_fd,
                        /* from_path= */ "",
                        /* to_fd= */ -EBADF,
                        dest,
                        MOVE_MOUNT_F_EMPTY_PATH | (mount_beneath ? MOVE_MOUNT_BENEATH : 0)));
        if (mount_beneath) {
                if (r == -EINVAL) { /* Fallback if mount_beneath is not supported */
                        log_debug_errno(r,
                                        "Failed to mount beneath '%s', falling back to overmount",
                                        dest);
                        return RET_NERRNO(move_mount(
                                        fsmount_fd,
                                        /* from_path= */ "",
                                        /* to_fd= */ -EBADF,
                                        dest,
                                        MOVE_MOUNT_F_EMPTY_PATH));
                }

                if (r >= 0) /* If it is, now remove the old mount */
                        return umount_verbose(LOG_DEBUG, dest, UMOUNT_NOFOLLOW|MNT_DETACH);
        }

        return r;
}

int mount_option_mangle(
                const char *options,
                unsigned long mount_flags,
                unsigned long *ret_mount_flags,
                char **ret_remaining_options) {

        const struct libmnt_optmap *map;
        _cleanup_free_ char *ret = NULL;
        int r;

        /* This extracts mount flags from the mount options, and stores
         * non-mount-flag options to '*ret_remaining_options'.
         * E.g.,
         * "rw,nosuid,nodev,relatime,size=1630748k,mode=0700,uid=1000,gid=1000"
         * is split to MS_NOSUID|MS_NODEV|MS_RELATIME and
         * "size=1630748k,mode=0700,uid=1000,gid=1000".
         * See more examples in test-mount-util.c.
         *
         * If 'options' does not contain any non-mount-flag options,
         * then '*ret_remaining_options' is set to NULL instead of empty string.
         * The validity of options stored in '*ret_remaining_options' is not checked.
         * If 'options' is NULL, this just copies 'mount_flags' to *ret_mount_flags. */

        assert(ret_mount_flags);
        assert(ret_remaining_options);

        map = mnt_get_builtin_optmap(MNT_LINUX_MAP);
        if (!map)
                return -EINVAL;

        for (const char *p = options;;) {
                _cleanup_free_ char *word = NULL;
                const struct libmnt_optmap *ent;

                r = extract_first_word(&p, &word, ",", EXTRACT_KEEP_QUOTE);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;

                for (ent = map; ent->name; ent++) {
                        /* All entries in MNT_LINUX_MAP do not take any argument.
                         * Thus, ent->name does not contain "=" or "[=]". */
                        if (!streq(word, ent->name))
                                continue;

                        if (!(ent->mask & MNT_INVERT))
                                mount_flags |= ent->id;
                        else if (mount_flags & ent->id)
                                mount_flags ^= ent->id;

                        break;
                }

                /* If 'word' is not a mount flag, then store it in '*ret_remaining_options'. */
                if (!ent->name &&
                    !startswith_no_case(word, "x-") &&
                    !strextend_with_separator(&ret, ",", word))
                        return -ENOMEM;
        }

        *ret_mount_flags = mount_flags;
        *ret_remaining_options = TAKE_PTR(ret);

        return 0;
}

static int mount_in_namespace_legacy(
                const char *chased_src_path,
                int chased_src_fd,
                struct stat *chased_src_st,
                const char *propagate_path,
                const char *incoming_path,
                const char *dest,
                int pidns_fd,
                int mntns_fd,
                int root_fd,
                bool read_only,
                bool make_file_or_directory,
                const MountOptions *options,
                const ImagePolicy *image_policy,
                bool is_image) {

        _cleanup_close_pair_ int errno_pipe_fd[2] = EBADF_PAIR;
        char mount_slave[] = "/tmp/propagate.XXXXXX", *mount_tmp, *mount_outside, *p;
        bool mount_slave_created = false, mount_slave_mounted = false,
                mount_tmp_created = false, mount_tmp_mounted = false,
                mount_outside_created = false, mount_outside_mounted = false;
        pid_t child;
        int r;

        assert(chased_src_path);
        assert(chased_src_fd >= 0);
        assert(chased_src_st);
        assert(propagate_path);
        assert(incoming_path);
        assert(dest);
        assert(pidns_fd >= 0);
        assert(mntns_fd >= 0);
        assert(root_fd >= 0);
        assert(!options || is_image);

        p = strjoina(propagate_path, "/");
        r = laccess(p, F_OK);
        if (r < 0)
                return log_debug_errno(r == -ENOENT ? SYNTHETIC_ERRNO(EOPNOTSUPP) : r, "Target does not allow propagation of mount points");

        /* Our goal is to install a new bind mount into the container,
           possibly read-only. This is irritatingly complex
           unfortunately, currently.

           First, we start by creating a private playground in /tmp,
           that we can mount MS_SLAVE. (Which is necessary, since
           MS_MOVE cannot be applied to mounts with MS_SHARED parent
           mounts.) */

        if (!mkdtemp(mount_slave))
                return log_debug_errno(errno, "Failed to create playground %s: %m", mount_slave);

        mount_slave_created = true;

        r = mount_nofollow_verbose(LOG_DEBUG, mount_slave, mount_slave, NULL, MS_BIND, NULL);
        if (r < 0)
                goto finish;

        mount_slave_mounted = true;

        r = mount_nofollow_verbose(LOG_DEBUG, NULL, mount_slave, NULL, MS_SLAVE, NULL);
        if (r < 0)
                goto finish;

        /* Second, we mount the source file or directory to a directory inside of our MS_SLAVE playground. */
        mount_tmp = strjoina(mount_slave, "/mount");
        if (is_image)
                r = mkdir_p(mount_tmp, 0700);
        else
                r = make_mount_point_inode_from_stat(chased_src_st, mount_tmp, 0700);
        if (r < 0) {
                log_debug_errno(r, "Failed to create temporary mount point %s: %m", mount_tmp);
                goto finish;
        }

        mount_tmp_created = true;

        if (is_image)
                r = verity_dissect_and_mount(
                                chased_src_fd,
                                chased_src_path,
                                mount_tmp,
                                options,
                                image_policy,
                                /* required_host_os_release_id= */ NULL,
                                /* required_host_os_release_version_id= */ NULL,
                                /* required_host_os_release_sysext_level= */ NULL,
                                /* required_host_os_release_confext_level= */ NULL,
                                /* required_sysext_scope= */ NULL,
                                /* ret_image= */ NULL);
        else
                r = mount_follow_verbose(LOG_DEBUG, FORMAT_PROC_FD_PATH(chased_src_fd), mount_tmp, NULL, MS_BIND, NULL);
        if (r < 0)
                goto finish;

        mount_tmp_mounted = true;

        /* Third, we remount the new bind mount read-only if requested. */
        if (read_only) {
                r = mount_nofollow_verbose(LOG_DEBUG, NULL, mount_tmp, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
                if (r < 0)
                        goto finish;
        }

        /* Fourth, we move the new bind mount into the propagation directory. This way it will appear there read-only
         * right-away. */

        mount_outside = strjoina(propagate_path, "/XXXXXX");
        if (is_image || S_ISDIR(chased_src_st->st_mode))
                r = mkdtemp(mount_outside) ? 0 : -errno;
        else {
                r = mkostemp_safe(mount_outside);
                safe_close(r);
        }
        if (r < 0) {
                log_debug_errno(r, "Cannot create propagation file or directory %s: %m", mount_outside);
                goto finish;
        }

        mount_outside_created = true;

        r = mount_nofollow_verbose(LOG_DEBUG, mount_tmp, mount_outside, NULL, MS_MOVE, NULL);
        if (r < 0)
                goto finish;

        mount_outside_mounted = true;
        mount_tmp_mounted = false;

        if (is_image || S_ISDIR(chased_src_st->st_mode))
                (void) rmdir(mount_tmp);
        else
                (void) unlink(mount_tmp);
        mount_tmp_created = false;

        (void) umount_verbose(LOG_DEBUG, mount_slave, UMOUNT_NOFOLLOW);
        mount_slave_mounted = false;

        (void) rmdir(mount_slave);
        mount_slave_created = false;

        if (pipe2(errno_pipe_fd, O_CLOEXEC|O_NONBLOCK) < 0) {
                log_debug_errno(errno, "Failed to create pipe: %m");
                goto finish;
        }

        r = namespace_fork("(sd-bindmnt)", "(sd-bindmnt-inner)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM,
                           pidns_fd, mntns_fd, -1, -1, root_fd, &child);
        if (r < 0)
                goto finish;
        if (r == 0) {
                _cleanup_free_ char *mount_outside_fn = NULL, *mount_inside = NULL;

                errno_pipe_fd[0] = safe_close(errno_pipe_fd[0]);

                if (make_file_or_directory) {
                        if (!is_image) {
                                (void) mkdir_parents(dest, 0755);
                                (void) make_mount_point_inode_from_stat(chased_src_st, dest, 0700);
                        } else
                                (void) mkdir_p(dest, 0755);
                }

                /* Fifth, move the mount to the right place inside */
                r = path_extract_filename(mount_outside, &mount_outside_fn);
                if (r < 0) {
                        log_debug_errno(r, "Failed to extract filename from propagation file or directory '%s': %m", mount_outside);
                        goto child_fail;
                }

                mount_inside = path_join(incoming_path, mount_outside_fn);
                if (!mount_inside) {
                        r = log_oom_debug();
                        goto child_fail;
                }

                r = mount_nofollow_verbose(LOG_DEBUG, mount_inside, dest, NULL, MS_MOVE, NULL);
                if (r < 0)
                        goto child_fail;

                _exit(EXIT_SUCCESS);

        child_fail:
                (void) write(errno_pipe_fd[1], &r, sizeof(r));
                errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);

                _exit(EXIT_FAILURE);
        }

        errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);

        r = wait_for_terminate_and_check("(sd-bindmnt)", child, 0);
        if (r < 0) {
                log_debug_errno(r, "Failed to wait for child: %m");
                goto finish;
        }
        if (r != EXIT_SUCCESS) {
                if (read(errno_pipe_fd[0], &r, sizeof(r)) == sizeof(r))
                        log_debug_errno(r, "Failed to mount: %m");
                else
                        log_debug("Child failed.");
                goto finish;
        }

finish:
        if (mount_outside_mounted)
                (void) umount_verbose(LOG_DEBUG, mount_outside, UMOUNT_NOFOLLOW);
        if (mount_outside_created) {
                if (is_image || S_ISDIR(chased_src_st->st_mode))
                        (void) rmdir(mount_outside);
                else
                        (void) unlink(mount_outside);
        }

        if (mount_tmp_mounted)
                (void) umount_verbose(LOG_DEBUG, mount_tmp, UMOUNT_NOFOLLOW);
        if (mount_tmp_created) {
                if (is_image || S_ISDIR(chased_src_st->st_mode))
                        (void) rmdir(mount_tmp);
                else
                        (void) unlink(mount_tmp);
        }

        if (mount_slave_mounted)
                (void) umount_verbose(LOG_DEBUG, mount_slave, UMOUNT_NOFOLLOW);
        if (mount_slave_created)
                (void) rmdir(mount_slave);

        return r;
}

static int mount_in_namespace(
                const PidRef *target,
                const char *propagate_path,
                const char *incoming_path,
                const char *src,
                const char *dest,
                bool read_only,
                bool make_file_or_directory,
                const MountOptions *options,
                const ImagePolicy *image_policy,
                bool is_image) {

        _cleanup_(dissected_image_unrefp) DissectedImage *img = NULL;
        _cleanup_close_pair_ int errno_pipe_fd[2] = EBADF_PAIR;
        _cleanup_close_ int mntns_fd = -EBADF, root_fd = -EBADF, pidns_fd = -EBADF, chased_src_fd = -EBADF,
                            new_mount_fd = -EBADF;
        _cleanup_free_ char *chased_src_path = NULL;
        struct stat st;
        pid_t child;
        int r;

        assert(propagate_path);
        assert(incoming_path);
        assert(src);
        assert(dest);
        assert(!options || is_image);

        if (!pidref_is_set(target))
                return -ESRCH;

        r = namespace_open(target->pid, &pidns_fd, &mntns_fd, NULL, NULL, &root_fd);
        if (r < 0)
                return log_debug_errno(r, "Failed to retrieve FDs of the target process' namespace: %m");

        r = in_same_namespace(target->pid, 0, NAMESPACE_MOUNT);
        if (r < 0)
                return log_debug_errno(r, "Failed to determine if mount namespaces are equal: %m");
        /* We can't add new mounts at runtime if the process wasn't started in a namespace */
        if (r > 0)
                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to activate bind mount in target, not running in a mount namespace");

        r = pidref_verify(target);
        if (r < 0)
                return log_debug_errno(r, "Failed to verify target process '" PID_FMT "': %m", target->pid);

        r = chase(src, NULL, 0, &chased_src_path, &chased_src_fd);
        if (r < 0)
                return log_debug_errno(r, "Failed to resolve source path of %s: %m", src);
        log_debug("Chased source path of %s to %s", src, chased_src_path);

        if (fstat(chased_src_fd, &st) < 0)
                return log_debug_errno(errno, "Failed to stat() resolved source path %s: %m", src);
        if (S_ISLNK(st.st_mode)) /* This shouldn't really happen, given that we just chased the symlinks above, but let's better be safe… */
                return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "Source directory %s can't be a symbolic link", src);

        if (!mount_new_api_supported()) /* Fallback if we can't use the new mount API */
                return mount_in_namespace_legacy(
                                chased_src_path,
                                chased_src_fd,
                                &st,
                                propagate_path,
                                incoming_path,
                                dest,
                                pidns_fd,
                                mntns_fd,
                                root_fd,
                                read_only,
                                make_file_or_directory,
                                options,
                                image_policy,
                                is_image);

        if (is_image) {
                r = verity_dissect_and_mount(
                                chased_src_fd,
                                chased_src_path,
                                /* dest= */ NULL,
                                options,
                                image_policy,
                                /* required_host_os_release_id= */ NULL,
                                /* required_host_os_release_version_id= */ NULL,
                                /* required_host_os_release_sysext_level= */ NULL,
                                /* required_host_os_release_confext_level= */ NULL,
                                /* required_sysext_scope= */ NULL,
                                &img);
                if (r < 0)
                        return log_debug_errno(
                                        r,
                                        "Failed to dissect and mount image %s: %m",
                                        chased_src_path);
        } else {
                new_mount_fd = open_tree(
                                chased_src_fd,
                                "",
                                OPEN_TREE_CLONE|OPEN_TREE_CLOEXEC|AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH);
                if (new_mount_fd < 0)
                        return log_debug_errno(
                                        errno,
                                        "Failed to open mount point \"%s\": %m",
                                        chased_src_path);

                if (read_only && mount_setattr(new_mount_fd, "", AT_EMPTY_PATH,
                                               &(struct mount_attr) {
                                                       .attr_set = MOUNT_ATTR_RDONLY,
                                               }, MOUNT_ATTR_SIZE_VER0) < 0)
                        return log_debug_errno(
                                        errno,
                                        "Failed to set mount flags for \"%s\": %m",
                                        chased_src_path);
        }

        if (pipe2(errno_pipe_fd, O_CLOEXEC|O_NONBLOCK) < 0)
                return log_debug_errno(errno, "Failed to create pipe: %m");

        r = namespace_fork("(sd-bindmnt)",
                           "(sd-bindmnt-inner)",
                           /* except_fds= */ NULL,
                           /* n_except_fds= */ 0,
                           FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM,
                           pidns_fd,
                           mntns_fd,
                           /* netns_fd= */ -1,
                           /* userns_fd= */ -1,
                           root_fd,
                           &child);
        if (r < 0)
                return log_debug_errno(r, "Failed to fork off: %m");
        if (r == 0) {
                errno_pipe_fd[0] = safe_close(errno_pipe_fd[0]);

                if (make_file_or_directory)
                        (void) mkdir_parents(dest, 0755);

                if (img) {
                        DissectImageFlags f = DISSECT_IMAGE_TRY_ATOMIC_MOUNT_EXCHANGE;

                        if (make_file_or_directory)
                                f |= DISSECT_IMAGE_MKDIR;

                        if (read_only)
                                f |= DISSECT_IMAGE_READ_ONLY;

                        r = dissected_image_mount(
                                        img,
                                        dest,
                                        /* uid_shift= */ UID_INVALID,
                                        /* uid_range= */ UID_INVALID,
                                        /* userns_fd= */ -EBADF,
                                        f);
                } else {
                        if (make_file_or_directory)
                                (void) make_mount_point_inode_from_stat(&st, dest, 0700);

                        r = mount_exchange_graceful(new_mount_fd, dest, /* mount_beneath= */ true);
                }
                if (r < 0) {
                        (void) write(errno_pipe_fd[1], &r, sizeof(r));
                        errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);

                        _exit(EXIT_FAILURE);
                }

                _exit(EXIT_SUCCESS);
        }

        errno_pipe_fd[1] = safe_close(errno_pipe_fd[1]);

        r = wait_for_terminate_and_check("(sd-bindmnt)", child, 0);
        if (r < 0)
                return log_debug_errno(r, "Failed to wait for child: %m");
        if (r != EXIT_SUCCESS) {
                if (read(errno_pipe_fd[0], &r, sizeof(r)) == sizeof(r))
                        return log_debug_errno(r, "Failed to mount: %m");

                return log_debug_errno(SYNTHETIC_ERRNO(EPROTO), "Child failed.");
        }

        return 0;
}

int bind_mount_in_namespace(
                PidRef * target,
                const char *propagate_path,
                const char *incoming_path,
                const char *src,
                const char *dest,
                bool read_only,
                bool make_file_or_directory) {

        return mount_in_namespace(target, propagate_path, incoming_path, src, dest, read_only, make_file_or_directory, /* options= */ NULL, /* image_policy= */ NULL, /* is_image= */ false);
}

int mount_image_in_namespace(
                PidRef * target,
                const char *propagate_path,
                const char *incoming_path,
                const char *src,
                const char *dest,
                bool read_only,
                bool make_file_or_directory,
                const MountOptions *options,
                const ImagePolicy *image_policy) {

        return mount_in_namespace(target, propagate_path, incoming_path, src, dest, read_only, make_file_or_directory, options, image_policy, /* is_image=*/ true);
}

int make_mount_point(const char *path) {
        int r;

        assert(path);

        /* If 'path' is already a mount point, does nothing and returns 0. If it is not it makes it one, and returns 1. */

        r = path_is_mount_point(path, NULL, 0);
        if (r < 0)
                return log_debug_errno(r, "Failed to determine whether '%s' is a mount point: %m", path);
        if (r > 0)
                return 0;

        r = mount_nofollow_verbose(LOG_DEBUG, path, path, NULL, MS_BIND|MS_REC, NULL);
        if (r < 0)
                return r;

        return 1;
}

int fd_make_mount_point(int fd) {
        int r;

        assert(fd >= 0);

        r = fd_is_mount_point(fd, NULL, 0);
        if (r < 0)
                return log_debug_errno(r, "Failed to determine whether file descriptor is a mount point: %m");
        if (r > 0)
                return 0;

        r = mount_follow_verbose(LOG_DEBUG, FORMAT_PROC_FD_PATH(fd), FORMAT_PROC_FD_PATH(fd), NULL, MS_BIND|MS_REC, NULL);
        if (r < 0)
                return r;

        return 1;
}

int make_userns(uid_t uid_shift, uid_t uid_range, uid_t owner, RemountIdmapping idmapping) {
        _cleanup_close_ int userns_fd = -EBADF;
        _cleanup_free_ char *line = NULL;

        /* Allocates a userns file descriptor with the mapping we need. For this we'll fork off a child
         * process whose only purpose is to give us a new user namespace. It's killed when we got it. */

        if (!userns_shift_range_valid(uid_shift, uid_range))
                return -EINVAL;

        if (IN_SET(idmapping, REMOUNT_IDMAPPING_NONE, REMOUNT_IDMAPPING_HOST_ROOT)) {
                if (asprintf(&line, UID_FMT " " UID_FMT " " UID_FMT "\n", 0u, uid_shift, uid_range) < 0)
                        return log_oom_debug();

                /* If requested we'll include an entry in the mapping so that the host root user can make
                 * changes to the uidmapped mount like it normally would. Specifically, we'll map the user
                 * with UID_MAPPED_ROOT on the backing fs to UID 0. This is useful, since nspawn code wants
                 * to create various missing inodes in the OS tree before booting into it, and this becomes
                 * very easy and straightforward to do if it can just do it under its own regular UID. Note
                 * that in that case the container's runtime uidmap (i.e. the one the container payload
                 * processes run in) will leave this UID unmapped, i.e. if we accidentally leave files owned
                 * by host root in the already uidmapped tree around they'll show up as owned by 'nobody',
                 * which is safe. (Of course, we shouldn't leave such inodes around, but always chown() them
                 * to the container's own UID range, but it's good to have a safety net, in case we
                 * forget it.) */
                if (idmapping == REMOUNT_IDMAPPING_HOST_ROOT)
                        if (strextendf(&line,
                                       UID_FMT " " UID_FMT " " UID_FMT "\n",
                                       UID_MAPPED_ROOT, 0u, 1u) < 0)
                                return log_oom_debug();
        }

        if (idmapping == REMOUNT_IDMAPPING_HOST_OWNER) {
                /* Remap the owner of the bind mounted directory to the root user within the container. This
                 * way every file written by root within the container to the bind-mounted directory will
                 * be owned by the original user. All other user will remain unmapped. */
                if (asprintf(&line, UID_FMT " " UID_FMT " " UID_FMT "\n", owner, uid_shift, 1u) < 0)
                        return log_oom_debug();
        }

        /* We always assign the same UID and GID ranges */
        userns_fd = userns_acquire(line, line);
        if (userns_fd < 0)
                return log_debug_errno(userns_fd, "Failed to acquire new userns: %m");

        return TAKE_FD(userns_fd);
}

int remount_idmap_fd(
                char **paths,
                int userns_fd) {

        int r;

        assert(userns_fd >= 0);

        /* This remounts all specified paths with the specified userns as idmap. It will do so in in the
         * order specified in the strv: the expectation is that the top-level directories are at the
         * beginning, and nested directories in the right, so that the tree can be built correctly from left
         * to right. */

        size_t n = strv_length(paths);
        if (n == 0) /* Nothing to do? */
                return 0;

        int *mount_fds = NULL;
        size_t n_mounts_fds = 0;

        mount_fds = new(int, n);
        if (!mount_fds)
                return log_oom_debug();

        CLEANUP_ARRAY(mount_fds, n_mounts_fds, close_many_and_free);

        for (size_t i = 0; i < n; i++) {
                int mntfd;

                /* Clone the mount point */
                mntfd = mount_fds[n_mounts_fds] = open_tree(-EBADF, paths[i], OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
                if (mount_fds[n_mounts_fds] < 0)
                        return log_debug_errno(errno, "Failed to open tree of mounted filesystem '%s': %m", paths[i]);

                n_mounts_fds++;

                /* Set the user namespace mapping attribute on the cloned mount point */
                if (mount_setattr(mntfd, "", AT_EMPTY_PATH,
                                  &(struct mount_attr) {
                                          .attr_set = MOUNT_ATTR_IDMAP,
                                          .userns_fd = userns_fd,
                                  }, sizeof(struct mount_attr)) < 0)
                        return log_debug_errno(errno, "Failed to change bind mount attributes for clone of '%s': %m", paths[i]);
        }

        for (size_t i = n; i > 0; i--) { /* Unmount the paths right-to-left */
                /* Remove the old mount points now that we have a idmapped mounts as replacement for all of them */
                r = umount_verbose(LOG_DEBUG, paths[i-1], UMOUNT_NOFOLLOW);
                if (r < 0)
                        return r;
        }

        for (size_t i = 0; i < n; i++) { /* Mount the replacement mounts left-to-right */
                /* And place the cloned version in its place */
                log_debug("Mounting idmapped fs to '%s'", paths[i]);
                if (move_mount(mount_fds[i], "", -EBADF, paths[i], MOVE_MOUNT_F_EMPTY_PATH) < 0)
                        return log_debug_errno(errno, "Failed to attach UID mapped mount to '%s': %m", paths[i]);
        }

        return 0;
}

int remount_idmap(char **p, uid_t uid_shift, uid_t uid_range, uid_t owner, RemountIdmapping idmapping) {
        _cleanup_close_ int userns_fd = -EBADF;

        userns_fd = make_userns(uid_shift, uid_range, owner, idmapping);
        if (userns_fd < 0)
                return userns_fd;

        return remount_idmap_fd(p, userns_fd);
}

typedef struct SubMount {
        char *path;
        int mount_fd;
} SubMount;

static void sub_mount_clear(SubMount *s) {
        assert(s);

        s->path = mfree(s->path);
        s->mount_fd = safe_close(s->mount_fd);
}

static void sub_mount_array_free(SubMount *s, size_t n) {
        assert(s || n == 0);

        for (size_t i = 0; i < n; i++)
                sub_mount_clear(s + i);

        free(s);
}

static int sub_mount_compare(const SubMount *a, const SubMount *b) {
        assert(a);
        assert(b);
        assert(a->path);
        assert(b->path);

        return path_compare(a->path, b->path);
}

static void sub_mount_drop(SubMount *s, size_t n) {
        assert(s || n == 0);

        for (size_t m = 0, i = 1; i < n; i++) {
                if (path_startswith(s[i].path, s[m].path))
                        sub_mount_clear(s + i);
                else
                        m = i;
        }
}

static int get_sub_mounts(
                const char *prefix,
                SubMount **ret_mounts,
                size_t *ret_n_mounts) {
        _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
        _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
        SubMount *mounts = NULL;
        size_t n = 0;
        int r;

        CLEANUP_ARRAY(mounts, n, sub_mount_array_free);

        assert(prefix);
        assert(ret_mounts);
        assert(ret_n_mounts);

        r = libmount_parse("/proc/self/mountinfo", NULL, &table, &iter);
        if (r < 0)
                return log_debug_errno(r, "Failed to parse /proc/self/mountinfo: %m");

        for (;;) {
                _cleanup_close_ int mount_fd = -EBADF;
                _cleanup_free_ char *p = NULL;
                struct libmnt_fs *fs;
                const char *path;
                int id1, id2;

                r = mnt_table_next_fs(table, iter, &fs);
                if (r == 1)
                        break; /* EOF */
                if (r < 0)
                        return log_debug_errno(r, "Failed to get next entry from /proc/self/mountinfo: %m");

                path = mnt_fs_get_target(fs);
                if (!path)
                        continue;

                if (isempty(path_startswith(path, prefix)))
                        continue;

                id1 = mnt_fs_get_id(fs);
                r = path_get_mnt_id(path, &id2);
                if (r < 0) {
                        log_debug_errno(r, "Failed to get mount ID of '%s', ignoring: %m", path);
                        continue;
                }
                if (id1 != id2) {
                        /* The path may be hidden by another over-mount or already remounted. */
                        log_debug("The mount IDs of '%s' obtained by libmount and path_get_mnt_id() are different (%i vs %i), ignoring.",
                                  path, id1, id2);
                        continue;
                }

                mount_fd = open(path, O_CLOEXEC|O_PATH);
                if (mount_fd < 0) {
                        if (errno == ENOENT) /* The path may be hidden by another over-mount or already unmounted. */
                                continue;

                        return log_debug_errno(errno, "Failed to open subtree of mounted filesystem '%s': %m", path);
                }

                p = strdup(path);
                if (!p)
                        return log_oom_debug();

                if (!GREEDY_REALLOC(mounts, n + 1))
                        return log_oom_debug();

                mounts[n++] = (SubMount) {
                        .path = TAKE_PTR(p),
                        .mount_fd = TAKE_FD(mount_fd),
                };
        }

        typesafe_qsort(mounts, n, sub_mount_compare);
        sub_mount_drop(mounts, n);

        *ret_mounts = TAKE_PTR(mounts);
        *ret_n_mounts = n;
        return 0;
}

int bind_mount_submounts(
                const char *source,
                const char *target) {

        SubMount *mounts = NULL;
        size_t n = 0;
        int ret = 0, r;

        /* Bind mounts all child mounts of 'source' to 'target'. Useful when setting up a new procfs instance
         * with new mount options to copy the original submounts over. */

        assert(source);
        assert(target);

        CLEANUP_ARRAY(mounts, n, sub_mount_array_free);

        r = get_sub_mounts(source, &mounts, &n);
        if (r < 0)
                return r;

        FOREACH_ARRAY(m, mounts, n) {
                _cleanup_free_ char *t = NULL;
                const char *suffix;

                if (isempty(m->path))
                        continue;

                assert_se(suffix = path_startswith(m->path, source));

                t = path_join(target, suffix);
                if (!t)
                        return -ENOMEM;

                r = path_is_mount_point(t, NULL, 0);
                if (r < 0) {
                        log_debug_errno(r, "Failed to detect if '%s' already is a mount point, ignoring: %m", t);
                        continue;
                }
                if (r > 0) {
                        log_debug("Not bind mounting '%s' from '%s' to '%s', since there's already a mountpoint.", suffix, source, target);
                        continue;
                }

                r = mount_follow_verbose(LOG_DEBUG, FORMAT_PROC_FD_PATH(m->mount_fd), t, NULL, MS_BIND|MS_REC, NULL);
                if (r < 0 && ret == 0)
                        ret = r;
        }

        return ret;
}

int make_mount_point_inode_from_stat(const struct stat *st, const char *dest, mode_t mode) {
        assert(st);
        assert(dest);

        if (S_ISDIR(st->st_mode))
                return mkdir_label(dest, mode);
        else
                return RET_NERRNO(mknod(dest, S_IFREG|(mode & ~0111), 0));
}

int make_mount_point_inode_from_path(const char *source, const char *dest, mode_t mode) {
        struct stat st;

        assert(source);
        assert(dest);

        if (stat(source, &st) < 0)
                return -errno;

        return make_mount_point_inode_from_stat(&st, dest, mode);
}

int trigger_automount_at(int dir_fd, const char *path) {
        _cleanup_free_ char *nested = NULL;

        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);

        nested = path_join(path, "a");
        if (!nested)
                return -ENOMEM;

        (void) faccessat(dir_fd, nested, F_OK, 0);

        return 0;
}

unsigned long credentials_fs_mount_flags(bool ro) {
        /* A tight set of mount flags for credentials mounts */
        return MS_NODEV|MS_NOEXEC|MS_NOSUID|ms_nosymfollow_supported()|(ro ? MS_RDONLY : 0);
}

int mount_credentials_fs(const char *path, size_t size, bool ro) {
        _cleanup_free_ char *opts = NULL;
        int r, noswap_supported;

        /* Mounts a file system we can place credentials in, i.e. with tight access modes right from the
         * beginning, and ideally swapping turned off. In order of preference:
         *
         *      1. tmpfs if it supports "noswap"
         *      2. ramfs
         *      3. tmpfs if it doesn't support "noswap"
         */

        noswap_supported = mount_option_supported("tmpfs", "noswap", NULL); /* Check explicitly to avoid kmsg noise */
        if (noswap_supported > 0) {
                _cleanup_free_ char *noswap_opts = NULL;

                if (asprintf(&noswap_opts, "mode=0700,nr_inodes=1024,size=%zu,noswap", size) < 0)
                        return -ENOMEM;

                /* Best case: tmpfs with noswap (needs kernel >= 6.3) */

                r = mount_nofollow_verbose(
                                LOG_DEBUG,
                                "tmpfs",
                                path,
                                "tmpfs",
                                credentials_fs_mount_flags(ro),
                                noswap_opts);
                if (r >= 0)
                        return r;
        }

        r = mount_nofollow_verbose(
                        LOG_DEBUG,
                        "ramfs",
                        path,
                        "ramfs",
                        credentials_fs_mount_flags(ro),
                        "mode=0700");
        if (r >= 0)
                return r;

        if (asprintf(&opts, "mode=0700,nr_inodes=1024,size=%zu", size) < 0)
                return -ENOMEM;

        return mount_nofollow_verbose(
                        LOG_DEBUG,
                        "tmpfs",
                        path,
                        "tmpfs",
                        credentials_fs_mount_flags(ro),
                        opts);
}

int make_fsmount(
                int error_log_level,
                const char *what,
                const char *type,
                unsigned long flags,
                const char *options,
                int userns_fd) {

        _cleanup_close_ int fs_fd = -EBADF, mnt_fd = -EBADF;
        _cleanup_free_ char *o = NULL;
        unsigned long f;
        int r;

        assert(type);
        assert(what);

        r = mount_option_mangle(options, flags, &f, &o);
        if (r < 0)
                return log_full_errno(
                                error_log_level, r, "Failed to mangle mount options %s: %m",
                                strempty(options));

        if (DEBUG_LOGGING) {
                _cleanup_free_ char *fl = NULL;
                (void) mount_flags_to_string(f, &fl);

                log_debug("Creating mount fd for %s (%s) (%s \"%s\")...",
                        strna(what), strna(type), strnull(fl), strempty(o));
        }

        fs_fd = fsopen(type, FSOPEN_CLOEXEC);
        if (fs_fd < 0)
                return log_full_errno(error_log_level, errno, "Failed to open superblock for \"%s\": %m", type);

        if (fsconfig(fs_fd, FSCONFIG_SET_STRING, "source", what, 0) < 0)
                return log_full_errno(error_log_level, errno, "Failed to set mount source for \"%s\" to \"%s\": %m", type, what);

        if (FLAGS_SET(f, MS_RDONLY))
                if (fsconfig(fs_fd, FSCONFIG_SET_FLAG, "ro", NULL, 0) < 0)
                        return log_full_errno(error_log_level, errno, "Failed to set read only mount flag for \"%s\": %m", type);

        for (const char *p = o;;) {
                _cleanup_free_ char *word = NULL;
                char *eq;

                r = extract_first_word(&p, &word, ",", EXTRACT_KEEP_QUOTE);
                if (r < 0)
                        return log_full_errno(error_log_level, r, "Failed to parse mount option string \"%s\": %m", o);
                if (r == 0)
                        break;

                eq = strchr(word, '=');
                if (eq) {
                        *eq = 0;
                        eq++;

                        if (fsconfig(fs_fd, FSCONFIG_SET_STRING, word, eq, 0) < 0)
                                return log_full_errno(error_log_level, errno, "Failed to set mount option \"%s=%s\" for \"%s\": %m", word, eq, type);
                } else {
                        if (fsconfig(fs_fd, FSCONFIG_SET_FLAG, word, NULL, 0) < 0)
                                return log_full_errno(error_log_level, errno, "Failed to set mount flag \"%s\" for \"%s\": %m", word, type);
                }
        }

        if (fsconfig(fs_fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0) < 0)
                return log_full_errno(error_log_level, errno, "Failed to realize fs fd for \"%s\" (\"%s\"): %m", what, type);

        mnt_fd = fsmount(fs_fd, FSMOUNT_CLOEXEC, 0);
        if (mnt_fd < 0)
                return log_full_errno(error_log_level, errno, "Failed to create mount fd for \"%s\" (\"%s\"): %m", what, type);

        if (mount_setattr(mnt_fd, "", AT_EMPTY_PATH|AT_RECURSIVE,
                          &(struct mount_attr) {
                                  .attr_set = ms_flags_to_mount_attr(f) | (userns_fd >= 0 ? MOUNT_ATTR_IDMAP : 0),
                                  .userns_fd = userns_fd,
                          }, MOUNT_ATTR_SIZE_VER0) < 0)
                return log_full_errno(error_log_level,
                                      errno,
                                      "Failed to set mount flags for \"%s\" (\"%s\"): %m",
                                      what,
                                      type);

        return TAKE_FD(mnt_fd);
}