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7
8#include <linux/export.h>
9#include <linux/nsproxy.h>
10#include <linux/slab.h>
11#include <linux/sched/signal.h>
12#include <linux/user_namespace.h>
13#include <linux/proc_ns.h>
14#include <linux/highuid.h>
15#include <linux/cred.h>
16#include <linux/securebits.h>
17#include <linux/keyctl.h>
18#include <linux/key-type.h>
19#include <keys/user-type.h>
20#include <linux/seq_file.h>
21#include <linux/fs.h>
22#include <linux/uaccess.h>
23#include <linux/ctype.h>
24#include <linux/projid.h>
25#include <linux/fs_struct.h>
26#include <linux/bsearch.h>
27#include <linux/sort.h>
28
29static struct kmem_cache *user_ns_cachep __read_mostly;
30static DEFINE_MUTEX(userns_state_mutex);
31
32static bool new_idmap_permitted(const struct file *file,
33 struct user_namespace *ns, int cap_setid,
34 struct uid_gid_map *map);
35static void free_user_ns(struct work_struct *work);
36
37static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid)
38{
39 return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES);
40}
41
42static void dec_user_namespaces(struct ucounts *ucounts)
43{
44 return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES);
45}
46
47static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns)
48{
49
50
51
52 cred->securebits = SECUREBITS_DEFAULT;
53 cred->cap_inheritable = CAP_EMPTY_SET;
54 cred->cap_permitted = CAP_FULL_SET;
55 cred->cap_effective = CAP_FULL_SET;
56 cred->cap_ambient = CAP_EMPTY_SET;
57 cred->cap_bset = CAP_FULL_SET;
58#ifdef CONFIG_KEYS
59 key_put(cred->request_key_auth);
60 cred->request_key_auth = NULL;
61#endif
62
63 cred->user_ns = user_ns;
64}
65
66
67
68
69
70
71
72
73
74int create_user_ns(struct cred *new)
75{
76 struct user_namespace *ns, *parent_ns = new->user_ns;
77 kuid_t owner = new->euid;
78 kgid_t group = new->egid;
79 struct ucounts *ucounts;
80 int ret, i;
81
82 ret = -ENOSPC;
83 if (parent_ns->level > 32)
84 goto fail;
85
86 ucounts = inc_user_namespaces(parent_ns, owner);
87 if (!ucounts)
88 goto fail;
89
90
91
92
93
94
95
96 ret = -EPERM;
97 if (current_chrooted())
98 goto fail_dec;
99
100
101
102
103
104 ret = -EPERM;
105 if (!kuid_has_mapping(parent_ns, owner) ||
106 !kgid_has_mapping(parent_ns, group))
107 goto fail_dec;
108
109 ret = -ENOMEM;
110 ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL);
111 if (!ns)
112 goto fail_dec;
113
114 ret = ns_alloc_inum(&ns->ns);
115 if (ret)
116 goto fail_free;
117 ns->ns.ops = &userns_operations;
118
119 atomic_set(&ns->count, 1);
120
121 ns->parent = parent_ns;
122 ns->level = parent_ns->level + 1;
123 ns->owner = owner;
124 ns->group = group;
125 INIT_WORK(&ns->work, free_user_ns);
126 for (i = 0; i < UCOUNT_COUNTS; i++) {
127 ns->ucount_max[i] = INT_MAX;
128 }
129 ns->ucounts = ucounts;
130
131
132 mutex_lock(&userns_state_mutex);
133 ns->flags = parent_ns->flags;
134 mutex_unlock(&userns_state_mutex);
135
136#ifdef CONFIG_PERSISTENT_KEYRINGS
137 init_rwsem(&ns->persistent_keyring_register_sem);
138#endif
139 ret = -ENOMEM;
140 if (!setup_userns_sysctls(ns))
141 goto fail_keyring;
142
143 set_cred_user_ns(new, ns);
144 return 0;
145fail_keyring:
146#ifdef CONFIG_PERSISTENT_KEYRINGS
147 key_put(ns->persistent_keyring_register);
148#endif
149 ns_free_inum(&ns->ns);
150fail_free:
151 kmem_cache_free(user_ns_cachep, ns);
152fail_dec:
153 dec_user_namespaces(ucounts);
154fail:
155 return ret;
156}
157
158int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
159{
160 struct cred *cred;
161 int err = -ENOMEM;
162
163 if (!(unshare_flags & CLONE_NEWUSER))
164 return 0;
165
166 cred = prepare_creds();
167 if (cred) {
168 err = create_user_ns(cred);
169 if (err)
170 put_cred(cred);
171 else
172 *new_cred = cred;
173 }
174
175 return err;
176}
177
178static void free_user_ns(struct work_struct *work)
179{
180 struct user_namespace *parent, *ns =
181 container_of(work, struct user_namespace, work);
182
183 do {
184 struct ucounts *ucounts = ns->ucounts;
185 parent = ns->parent;
186 if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
187 kfree(ns->gid_map.forward);
188 kfree(ns->gid_map.reverse);
189 }
190 if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
191 kfree(ns->uid_map.forward);
192 kfree(ns->uid_map.reverse);
193 }
194 if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
195 kfree(ns->projid_map.forward);
196 kfree(ns->projid_map.reverse);
197 }
198 retire_userns_sysctls(ns);
199#ifdef CONFIG_PERSISTENT_KEYRINGS
200 key_put(ns->persistent_keyring_register);
201#endif
202 ns_free_inum(&ns->ns);
203 kmem_cache_free(user_ns_cachep, ns);
204 dec_user_namespaces(ucounts);
205 ns = parent;
206 } while (atomic_dec_and_test(&parent->count));
207}
208
209void __put_user_ns(struct user_namespace *ns)
210{
211 schedule_work(&ns->work);
212}
213EXPORT_SYMBOL(__put_user_ns);
214
215
216
217
218
219struct idmap_key {
220 bool map_up;
221 u32 id;
222 u32 count;
223};
224
225
226
227
228
229static int cmp_map_id(const void *k, const void *e)
230{
231 u32 first, last, id2;
232 const struct idmap_key *key = k;
233 const struct uid_gid_extent *el = e;
234
235 id2 = key->id + key->count - 1;
236
237
238 if (key->map_up)
239 first = el->lower_first;
240 else
241 first = el->first;
242
243 last = first + el->count - 1;
244
245 if (key->id >= first && key->id <= last &&
246 (id2 >= first && id2 <= last))
247 return 0;
248
249 if (key->id < first || id2 < first)
250 return -1;
251
252 return 1;
253}
254
255
256
257
258
259static struct uid_gid_extent *
260map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
261{
262 struct idmap_key key;
263
264 key.map_up = false;
265 key.count = count;
266 key.id = id;
267
268 return bsearch(&key, map->forward, extents,
269 sizeof(struct uid_gid_extent), cmp_map_id);
270}
271
272
273
274
275
276
277static struct uid_gid_extent *
278map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count)
279{
280 unsigned idx;
281 u32 first, last, id2;
282
283 id2 = id + count - 1;
284
285
286 for (idx = 0; idx < extents; idx++) {
287 first = map->extent[idx].first;
288 last = first + map->extent[idx].count - 1;
289 if (id >= first && id <= last &&
290 (id2 >= first && id2 <= last))
291 return &map->extent[idx];
292 }
293 return NULL;
294}
295
296static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
297{
298 struct uid_gid_extent *extent;
299 unsigned extents = map->nr_extents;
300 smp_rmb();
301
302 if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
303 extent = map_id_range_down_base(extents, map, id, count);
304 else
305 extent = map_id_range_down_max(extents, map, id, count);
306
307
308 if (extent)
309 id = (id - extent->first) + extent->lower_first;
310 else
311 id = (u32) -1;
312
313 return id;
314}
315
316static u32 map_id_down(struct uid_gid_map *map, u32 id)
317{
318 return map_id_range_down(map, id, 1);
319}
320
321
322
323
324
325
326static struct uid_gid_extent *
327map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id)
328{
329 unsigned idx;
330 u32 first, last;
331
332
333 for (idx = 0; idx < extents; idx++) {
334 first = map->extent[idx].lower_first;
335 last = first + map->extent[idx].count - 1;
336 if (id >= first && id <= last)
337 return &map->extent[idx];
338 }
339 return NULL;
340}
341
342
343
344
345
346static struct uid_gid_extent *
347map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id)
348{
349 struct idmap_key key;
350
351 key.map_up = true;
352 key.count = 1;
353 key.id = id;
354
355 return bsearch(&key, map->reverse, extents,
356 sizeof(struct uid_gid_extent), cmp_map_id);
357}
358
359static u32 map_id_up(struct uid_gid_map *map, u32 id)
360{
361 struct uid_gid_extent *extent;
362 unsigned extents = map->nr_extents;
363 smp_rmb();
364
365 if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
366 extent = map_id_up_base(extents, map, id);
367 else
368 extent = map_id_up_max(extents, map, id);
369
370
371 if (extent)
372 id = (id - extent->lower_first) + extent->first;
373 else
374 id = (u32) -1;
375
376 return id;
377}
378
379
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389
390
391
392kuid_t make_kuid(struct user_namespace *ns, uid_t uid)
393{
394
395 return KUIDT_INIT(map_id_down(&ns->uid_map, uid));
396}
397EXPORT_SYMBOL(make_kuid);
398
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409
410
411uid_t from_kuid(struct user_namespace *targ, kuid_t kuid)
412{
413
414 return map_id_up(&targ->uid_map, __kuid_val(kuid));
415}
416EXPORT_SYMBOL(from_kuid);
417
418
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434
435
436uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid)
437{
438 uid_t uid;
439 uid = from_kuid(targ, kuid);
440
441 if (uid == (uid_t) -1)
442 uid = overflowuid;
443 return uid;
444}
445EXPORT_SYMBOL(from_kuid_munged);
446
447
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451
452
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456
457
458
459
460kgid_t make_kgid(struct user_namespace *ns, gid_t gid)
461{
462
463 return KGIDT_INIT(map_id_down(&ns->gid_map, gid));
464}
465EXPORT_SYMBOL(make_kgid);
466
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477
478
479gid_t from_kgid(struct user_namespace *targ, kgid_t kgid)
480{
481
482 return map_id_up(&targ->gid_map, __kgid_val(kgid));
483}
484EXPORT_SYMBOL(from_kgid);
485
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502
503gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid)
504{
505 gid_t gid;
506 gid = from_kgid(targ, kgid);
507
508 if (gid == (gid_t) -1)
509 gid = overflowgid;
510 return gid;
511}
512EXPORT_SYMBOL(from_kgid_munged);
513
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519
520
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524
525
526
527kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid)
528{
529
530 return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid));
531}
532EXPORT_SYMBOL(make_kprojid);
533
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541
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543
544
545
546projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid)
547{
548
549 return map_id_up(&targ->projid_map, __kprojid_val(kprojid));
550}
551EXPORT_SYMBOL(from_kprojid);
552
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570
571projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid)
572{
573 projid_t projid;
574 projid = from_kprojid(targ, kprojid);
575
576 if (projid == (projid_t) -1)
577 projid = OVERFLOW_PROJID;
578 return projid;
579}
580EXPORT_SYMBOL(from_kprojid_munged);
581
582
583static int uid_m_show(struct seq_file *seq, void *v)
584{
585 struct user_namespace *ns = seq->private;
586 struct uid_gid_extent *extent = v;
587 struct user_namespace *lower_ns;
588 uid_t lower;
589
590 lower_ns = seq_user_ns(seq);
591 if ((lower_ns == ns) && lower_ns->parent)
592 lower_ns = lower_ns->parent;
593
594 lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first));
595
596 seq_printf(seq, "%10u %10u %10u\n",
597 extent->first,
598 lower,
599 extent->count);
600
601 return 0;
602}
603
604static int gid_m_show(struct seq_file *seq, void *v)
605{
606 struct user_namespace *ns = seq->private;
607 struct uid_gid_extent *extent = v;
608 struct user_namespace *lower_ns;
609 gid_t lower;
610
611 lower_ns = seq_user_ns(seq);
612 if ((lower_ns == ns) && lower_ns->parent)
613 lower_ns = lower_ns->parent;
614
615 lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first));
616
617 seq_printf(seq, "%10u %10u %10u\n",
618 extent->first,
619 lower,
620 extent->count);
621
622 return 0;
623}
624
625static int projid_m_show(struct seq_file *seq, void *v)
626{
627 struct user_namespace *ns = seq->private;
628 struct uid_gid_extent *extent = v;
629 struct user_namespace *lower_ns;
630 projid_t lower;
631
632 lower_ns = seq_user_ns(seq);
633 if ((lower_ns == ns) && lower_ns->parent)
634 lower_ns = lower_ns->parent;
635
636 lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first));
637
638 seq_printf(seq, "%10u %10u %10u\n",
639 extent->first,
640 lower,
641 extent->count);
642
643 return 0;
644}
645
646static void *m_start(struct seq_file *seq, loff_t *ppos,
647 struct uid_gid_map *map)
648{
649 loff_t pos = *ppos;
650 unsigned extents = map->nr_extents;
651 smp_rmb();
652
653 if (pos >= extents)
654 return NULL;
655
656 if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
657 return &map->extent[pos];
658
659 return &map->forward[pos];
660}
661
662static void *uid_m_start(struct seq_file *seq, loff_t *ppos)
663{
664 struct user_namespace *ns = seq->private;
665
666 return m_start(seq, ppos, &ns->uid_map);
667}
668
669static void *gid_m_start(struct seq_file *seq, loff_t *ppos)
670{
671 struct user_namespace *ns = seq->private;
672
673 return m_start(seq, ppos, &ns->gid_map);
674}
675
676static void *projid_m_start(struct seq_file *seq, loff_t *ppos)
677{
678 struct user_namespace *ns = seq->private;
679
680 return m_start(seq, ppos, &ns->projid_map);
681}
682
683static void *m_next(struct seq_file *seq, void *v, loff_t *pos)
684{
685 (*pos)++;
686 return seq->op->start(seq, pos);
687}
688
689static void m_stop(struct seq_file *seq, void *v)
690{
691 return;
692}
693
694const struct seq_operations proc_uid_seq_operations = {
695 .start = uid_m_start,
696 .stop = m_stop,
697 .next = m_next,
698 .show = uid_m_show,
699};
700
701const struct seq_operations proc_gid_seq_operations = {
702 .start = gid_m_start,
703 .stop = m_stop,
704 .next = m_next,
705 .show = gid_m_show,
706};
707
708const struct seq_operations proc_projid_seq_operations = {
709 .start = projid_m_start,
710 .stop = m_stop,
711 .next = m_next,
712 .show = projid_m_show,
713};
714
715static bool mappings_overlap(struct uid_gid_map *new_map,
716 struct uid_gid_extent *extent)
717{
718 u32 upper_first, lower_first, upper_last, lower_last;
719 unsigned idx;
720
721 upper_first = extent->first;
722 lower_first = extent->lower_first;
723 upper_last = upper_first + extent->count - 1;
724 lower_last = lower_first + extent->count - 1;
725
726 for (idx = 0; idx < new_map->nr_extents; idx++) {
727 u32 prev_upper_first, prev_lower_first;
728 u32 prev_upper_last, prev_lower_last;
729 struct uid_gid_extent *prev;
730
731 if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
732 prev = &new_map->extent[idx];
733 else
734 prev = &new_map->forward[idx];
735
736 prev_upper_first = prev->first;
737 prev_lower_first = prev->lower_first;
738 prev_upper_last = prev_upper_first + prev->count - 1;
739 prev_lower_last = prev_lower_first + prev->count - 1;
740
741
742 if ((prev_upper_first <= upper_last) &&
743 (prev_upper_last >= upper_first))
744 return true;
745
746
747 if ((prev_lower_first <= lower_last) &&
748 (prev_lower_last >= lower_first))
749 return true;
750 }
751 return false;
752}
753
754
755
756
757
758
759static int insert_extent(struct uid_gid_map *map, struct uid_gid_extent *extent)
760{
761 struct uid_gid_extent *dest;
762
763 if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) {
764 struct uid_gid_extent *forward;
765
766
767 forward = kmalloc(sizeof(struct uid_gid_extent) *
768 UID_GID_MAP_MAX_EXTENTS, GFP_KERNEL);
769 if (!forward)
770 return -ENOMEM;
771
772
773
774
775 memcpy(forward, map->extent,
776 map->nr_extents * sizeof(map->extent[0]));
777
778 map->forward = forward;
779 map->reverse = NULL;
780 }
781
782 if (map->nr_extents < UID_GID_MAP_MAX_BASE_EXTENTS)
783 dest = &map->extent[map->nr_extents];
784 else
785 dest = &map->forward[map->nr_extents];
786
787 *dest = *extent;
788 map->nr_extents++;
789 return 0;
790}
791
792
793static int cmp_extents_forward(const void *a, const void *b)
794{
795 const struct uid_gid_extent *e1 = a;
796 const struct uid_gid_extent *e2 = b;
797
798 if (e1->first < e2->first)
799 return -1;
800
801 if (e1->first > e2->first)
802 return 1;
803
804 return 0;
805}
806
807
808static int cmp_extents_reverse(const void *a, const void *b)
809{
810 const struct uid_gid_extent *e1 = a;
811 const struct uid_gid_extent *e2 = b;
812
813 if (e1->lower_first < e2->lower_first)
814 return -1;
815
816 if (e1->lower_first > e2->lower_first)
817 return 1;
818
819 return 0;
820}
821
822
823
824
825
826static int sort_idmaps(struct uid_gid_map *map)
827{
828 if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
829 return 0;
830
831
832 sort(map->forward, map->nr_extents, sizeof(struct uid_gid_extent),
833 cmp_extents_forward, NULL);
834
835
836 map->reverse = kmemdup(map->forward,
837 map->nr_extents * sizeof(struct uid_gid_extent),
838 GFP_KERNEL);
839 if (!map->reverse)
840 return -ENOMEM;
841
842
843 sort(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent),
844 cmp_extents_reverse, NULL);
845
846 return 0;
847}
848
849static ssize_t map_write(struct file *file, const char __user *buf,
850 size_t count, loff_t *ppos,
851 int cap_setid,
852 struct uid_gid_map *map,
853 struct uid_gid_map *parent_map)
854{
855 struct seq_file *seq = file->private_data;
856 struct user_namespace *ns = seq->private;
857 struct uid_gid_map new_map;
858 unsigned idx;
859 struct uid_gid_extent extent;
860 char *kbuf = NULL, *pos, *next_line;
861 ssize_t ret = -EINVAL;
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882 mutex_lock(&userns_state_mutex);
883
884 memset(&new_map, 0, sizeof(struct uid_gid_map));
885
886 ret = -EPERM;
887
888 if (map->nr_extents != 0)
889 goto out;
890
891
892
893
894 if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
895 goto out;
896
897
898 ret = -EINVAL;
899 if ((*ppos != 0) || (count >= PAGE_SIZE))
900 goto out;
901
902
903 kbuf = memdup_user_nul(buf, count);
904 if (IS_ERR(kbuf)) {
905 ret = PTR_ERR(kbuf);
906 kbuf = NULL;
907 goto out;
908 }
909
910
911 ret = -EINVAL;
912 pos = kbuf;
913 for (; pos; pos = next_line) {
914
915
916 next_line = strchr(pos, '\n');
917 if (next_line) {
918 *next_line = '\0';
919 next_line++;
920 if (*next_line == '\0')
921 next_line = NULL;
922 }
923
924 pos = skip_spaces(pos);
925 extent.first = simple_strtoul(pos, &pos, 10);
926 if (!isspace(*pos))
927 goto out;
928
929 pos = skip_spaces(pos);
930 extent.lower_first = simple_strtoul(pos, &pos, 10);
931 if (!isspace(*pos))
932 goto out;
933
934 pos = skip_spaces(pos);
935 extent.count = simple_strtoul(pos, &pos, 10);
936 if (*pos && !isspace(*pos))
937 goto out;
938
939
940 pos = skip_spaces(pos);
941 if (*pos != '\0')
942 goto out;
943
944
945 if ((extent.first == (u32) -1) ||
946 (extent.lower_first == (u32) -1))
947 goto out;
948
949
950
951
952 if ((extent.first + extent.count) <= extent.first)
953 goto out;
954 if ((extent.lower_first + extent.count) <=
955 extent.lower_first)
956 goto out;
957
958
959 if (mappings_overlap(&new_map, &extent))
960 goto out;
961
962 if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS &&
963 (next_line != NULL))
964 goto out;
965
966 ret = insert_extent(&new_map, &extent);
967 if (ret < 0)
968 goto out;
969 ret = -EINVAL;
970 }
971
972 if (new_map.nr_extents == 0)
973 goto out;
974
975 ret = -EPERM;
976
977 if (!new_idmap_permitted(file, ns, cap_setid, &new_map))
978 goto out;
979
980 ret = sort_idmaps(&new_map);
981 if (ret < 0)
982 goto out;
983
984 ret = -EPERM;
985
986
987
988 for (idx = 0; idx < new_map.nr_extents; idx++) {
989 struct uid_gid_extent *e;
990 u32 lower_first;
991
992 if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS)
993 e = &new_map.extent[idx];
994 else
995 e = &new_map.forward[idx];
996
997 lower_first = map_id_range_down(parent_map,
998 e->lower_first,
999 e->count);
1000
1001
1002
1003
1004 if (lower_first == (u32) -1)
1005 goto out;
1006
1007 e->lower_first = lower_first;
1008 }
1009
1010
1011 if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) {
1012 memcpy(map->extent, new_map.extent,
1013 new_map.nr_extents * sizeof(new_map.extent[0]));
1014 } else {
1015 map->forward = new_map.forward;
1016 map->reverse = new_map.reverse;
1017 }
1018 smp_wmb();
1019 map->nr_extents = new_map.nr_extents;
1020
1021 *ppos = count;
1022 ret = count;
1023out:
1024 if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) {
1025 kfree(new_map.forward);
1026 kfree(new_map.reverse);
1027 map->forward = NULL;
1028 map->reverse = NULL;
1029 map->nr_extents = 0;
1030 }
1031
1032 mutex_unlock(&userns_state_mutex);
1033 kfree(kbuf);
1034 return ret;
1035}
1036
1037ssize_t proc_uid_map_write(struct file *file, const char __user *buf,
1038 size_t size, loff_t *ppos)
1039{
1040 struct seq_file *seq = file->private_data;
1041 struct user_namespace *ns = seq->private;
1042 struct user_namespace *seq_ns = seq_user_ns(seq);
1043
1044 if (!ns->parent)
1045 return -EPERM;
1046
1047 if ((seq_ns != ns) && (seq_ns != ns->parent))
1048 return -EPERM;
1049
1050 return map_write(file, buf, size, ppos, CAP_SETUID,
1051 &ns->uid_map, &ns->parent->uid_map);
1052}
1053
1054ssize_t proc_gid_map_write(struct file *file, const char __user *buf,
1055 size_t size, loff_t *ppos)
1056{
1057 struct seq_file *seq = file->private_data;
1058 struct user_namespace *ns = seq->private;
1059 struct user_namespace *seq_ns = seq_user_ns(seq);
1060
1061 if (!ns->parent)
1062 return -EPERM;
1063
1064 if ((seq_ns != ns) && (seq_ns != ns->parent))
1065 return -EPERM;
1066
1067 return map_write(file, buf, size, ppos, CAP_SETGID,
1068 &ns->gid_map, &ns->parent->gid_map);
1069}
1070
1071ssize_t proc_projid_map_write(struct file *file, const char __user *buf,
1072 size_t size, loff_t *ppos)
1073{
1074 struct seq_file *seq = file->private_data;
1075 struct user_namespace *ns = seq->private;
1076 struct user_namespace *seq_ns = seq_user_ns(seq);
1077
1078 if (!ns->parent)
1079 return -EPERM;
1080
1081 if ((seq_ns != ns) && (seq_ns != ns->parent))
1082 return -EPERM;
1083
1084
1085 return map_write(file, buf, size, ppos, -1,
1086 &ns->projid_map, &ns->parent->projid_map);
1087}
1088
1089static bool new_idmap_permitted(const struct file *file,
1090 struct user_namespace *ns, int cap_setid,
1091 struct uid_gid_map *new_map)
1092{
1093 const struct cred *cred = file->f_cred;
1094
1095
1096
1097 if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) &&
1098 uid_eq(ns->owner, cred->euid)) {
1099 u32 id = new_map->extent[0].lower_first;
1100 if (cap_setid == CAP_SETUID) {
1101 kuid_t uid = make_kuid(ns->parent, id);
1102 if (uid_eq(uid, cred->euid))
1103 return true;
1104 } else if (cap_setid == CAP_SETGID) {
1105 kgid_t gid = make_kgid(ns->parent, id);
1106 if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) &&
1107 gid_eq(gid, cred->egid))
1108 return true;
1109 }
1110 }
1111
1112
1113 if (!cap_valid(cap_setid))
1114 return true;
1115
1116
1117
1118
1119
1120 if (ns_capable(ns->parent, cap_setid) &&
1121 file_ns_capable(file, ns->parent, cap_setid))
1122 return true;
1123
1124 return false;
1125}
1126
1127int proc_setgroups_show(struct seq_file *seq, void *v)
1128{
1129 struct user_namespace *ns = seq->private;
1130 unsigned long userns_flags = READ_ONCE(ns->flags);
1131
1132 seq_printf(seq, "%s\n",
1133 (userns_flags & USERNS_SETGROUPS_ALLOWED) ?
1134 "allow" : "deny");
1135 return 0;
1136}
1137
1138ssize_t proc_setgroups_write(struct file *file, const char __user *buf,
1139 size_t count, loff_t *ppos)
1140{
1141 struct seq_file *seq = file->private_data;
1142 struct user_namespace *ns = seq->private;
1143 char kbuf[8], *pos;
1144 bool setgroups_allowed;
1145 ssize_t ret;
1146
1147
1148 ret = -EINVAL;
1149 if ((*ppos != 0) || (count >= sizeof(kbuf)))
1150 goto out;
1151
1152
1153 ret = -EFAULT;
1154 if (copy_from_user(kbuf, buf, count))
1155 goto out;
1156 kbuf[count] = '\0';
1157 pos = kbuf;
1158
1159
1160 ret = -EINVAL;
1161 if (strncmp(pos, "allow", 5) == 0) {
1162 pos += 5;
1163 setgroups_allowed = true;
1164 }
1165 else if (strncmp(pos, "deny", 4) == 0) {
1166 pos += 4;
1167 setgroups_allowed = false;
1168 }
1169 else
1170 goto out;
1171
1172
1173 pos = skip_spaces(pos);
1174 if (*pos != '\0')
1175 goto out;
1176
1177 ret = -EPERM;
1178 mutex_lock(&userns_state_mutex);
1179 if (setgroups_allowed) {
1180
1181
1182
1183 if (!(ns->flags & USERNS_SETGROUPS_ALLOWED))
1184 goto out_unlock;
1185 } else {
1186
1187
1188
1189 if (ns->gid_map.nr_extents != 0)
1190 goto out_unlock;
1191 ns->flags &= ~USERNS_SETGROUPS_ALLOWED;
1192 }
1193 mutex_unlock(&userns_state_mutex);
1194
1195
1196 *ppos = count;
1197 ret = count;
1198out:
1199 return ret;
1200out_unlock:
1201 mutex_unlock(&userns_state_mutex);
1202 goto out;
1203}
1204
1205bool userns_may_setgroups(const struct user_namespace *ns)
1206{
1207 bool allowed;
1208
1209 mutex_lock(&userns_state_mutex);
1210
1211
1212
1213 allowed = ns->gid_map.nr_extents != 0;
1214
1215 allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED);
1216 mutex_unlock(&userns_state_mutex);
1217
1218 return allowed;
1219}
1220
1221
1222
1223
1224
1225bool in_userns(const struct user_namespace *ancestor,
1226 const struct user_namespace *child)
1227{
1228 const struct user_namespace *ns;
1229 for (ns = child; ns->level > ancestor->level; ns = ns->parent)
1230 ;
1231 return (ns == ancestor);
1232}
1233
1234bool current_in_userns(const struct user_namespace *target_ns)
1235{
1236 return in_userns(target_ns, current_user_ns());
1237}
1238
1239static inline struct user_namespace *to_user_ns(struct ns_common *ns)
1240{
1241 return container_of(ns, struct user_namespace, ns);
1242}
1243
1244static struct ns_common *userns_get(struct task_struct *task)
1245{
1246 struct user_namespace *user_ns;
1247
1248 rcu_read_lock();
1249 user_ns = get_user_ns(__task_cred(task)->user_ns);
1250 rcu_read_unlock();
1251
1252 return user_ns ? &user_ns->ns : NULL;
1253}
1254
1255static void userns_put(struct ns_common *ns)
1256{
1257 put_user_ns(to_user_ns(ns));
1258}
1259
1260static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
1261{
1262 struct user_namespace *user_ns = to_user_ns(ns);
1263 struct cred *cred;
1264
1265
1266
1267
1268 if (user_ns == current_user_ns())
1269 return -EINVAL;
1270
1271
1272 if (!thread_group_empty(current))
1273 return -EINVAL;
1274
1275 if (current->fs->users != 1)
1276 return -EINVAL;
1277
1278 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
1279 return -EPERM;
1280
1281 cred = prepare_creds();
1282 if (!cred)
1283 return -ENOMEM;
1284
1285 put_user_ns(cred->user_ns);
1286 set_cred_user_ns(cred, get_user_ns(user_ns));
1287
1288 return commit_creds(cred);
1289}
1290
1291struct ns_common *ns_get_owner(struct ns_common *ns)
1292{
1293 struct user_namespace *my_user_ns = current_user_ns();
1294 struct user_namespace *owner, *p;
1295
1296
1297 owner = p = ns->ops->owner(ns);
1298 for (;;) {
1299 if (!p)
1300 return ERR_PTR(-EPERM);
1301 if (p == my_user_ns)
1302 break;
1303 p = p->parent;
1304 }
1305
1306 return &get_user_ns(owner)->ns;
1307}
1308
1309static struct user_namespace *userns_owner(struct ns_common *ns)
1310{
1311 return to_user_ns(ns)->parent;
1312}
1313
1314const struct proc_ns_operations userns_operations = {
1315 .name = "user",
1316 .type = CLONE_NEWUSER,
1317 .get = userns_get,
1318 .put = userns_put,
1319 .install = userns_install,
1320 .owner = userns_owner,
1321 .get_parent = ns_get_owner,
1322};
1323
1324static __init int user_namespaces_init(void)
1325{
1326 user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
1327 return 0;
1328}
1329subsys_initcall(user_namespaces_init);
1330