drivers: power: report battery voltage in AOSP compatible format
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / user_namespace.c
1 /*
2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License as
4 * published by the Free Software Foundation, version 2 of the
5 * License.
6 */
7
8 #include <linux/export.h>
9 #include <linux/nsproxy.h>
10 #include <linux/slab.h>
11 #include <linux/user_namespace.h>
12 #include <linux/proc_ns.h>
13 #include <linux/highuid.h>
14 #include <linux/cred.h>
15 #include <linux/securebits.h>
16 #include <linux/keyctl.h>
17 #include <linux/key-type.h>
18 #include <keys/user-type.h>
19 #include <linux/seq_file.h>
20 #include <linux/fs.h>
21 #include <linux/uaccess.h>
22 #include <linux/ctype.h>
23 #include <linux/projid.h>
24 #include <linux/fs_struct.h>
25
26 static struct kmem_cache *user_ns_cachep __read_mostly;
27 static DEFINE_MUTEX(userns_state_mutex);
28
29 static bool new_idmap_permitted(const struct file *file,
30 struct user_namespace *ns, int cap_setid,
31 struct uid_gid_map *map);
32
33 static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns)
34 {
35 /* Start with the same capabilities as init but useless for doing
36 * anything as the capabilities are bound to the new user namespace.
37 */
38 cred->securebits = SECUREBITS_DEFAULT;
39 cred->cap_inheritable = CAP_EMPTY_SET;
40 cred->cap_permitted = CAP_FULL_SET;
41 cred->cap_effective = CAP_FULL_SET;
42 cred->cap_bset = CAP_FULL_SET;
43 #ifdef CONFIG_KEYS
44 key_put(cred->request_key_auth);
45 cred->request_key_auth = NULL;
46 #endif
47 /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
48 cred->user_ns = user_ns;
49 }
50
51 /*
52 * Create a new user namespace, deriving the creator from the user in the
53 * passed credentials, and replacing that user with the new root user for the
54 * new namespace.
55 *
56 * This is called by copy_creds(), which will finish setting the target task's
57 * credentials.
58 */
59 int create_user_ns(struct cred *new)
60 {
61 struct user_namespace *ns, *parent_ns = new->user_ns;
62 kuid_t owner = new->euid;
63 kgid_t group = new->egid;
64 int ret;
65
66 if (parent_ns->level > 32)
67 return -EUSERS;
68
69 /*
70 * Verify that we can not violate the policy of which files
71 * may be accessed that is specified by the root directory,
72 * by verifing that the root directory is at the root of the
73 * mount namespace which allows all files to be accessed.
74 */
75 if (current_chrooted())
76 return -EPERM;
77
78 /* The creator needs a mapping in the parent user namespace
79 * or else we won't be able to reasonably tell userspace who
80 * created a user_namespace.
81 */
82 if (!kuid_has_mapping(parent_ns, owner) ||
83 !kgid_has_mapping(parent_ns, group))
84 return -EPERM;
85
86 ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL);
87 if (!ns)
88 return -ENOMEM;
89
90 ret = proc_alloc_inum(&ns->proc_inum);
91 if (ret) {
92 kmem_cache_free(user_ns_cachep, ns);
93 return ret;
94 }
95
96 atomic_set(&ns->count, 1);
97 /* Leave the new->user_ns reference with the new user namespace. */
98 ns->parent = parent_ns;
99 ns->level = parent_ns->level + 1;
100 ns->owner = owner;
101 ns->group = group;
102
103 /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
104 mutex_lock(&userns_state_mutex);
105 ns->flags = parent_ns->flags;
106 mutex_unlock(&userns_state_mutex);
107
108 set_cred_user_ns(new, ns);
109
110 update_mnt_policy(ns);
111
112 return 0;
113 }
114
115 int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
116 {
117 struct cred *cred;
118 int err = -ENOMEM;
119
120 if (!(unshare_flags & CLONE_NEWUSER))
121 return 0;
122
123 cred = prepare_creds();
124 if (cred) {
125 err = create_user_ns(cred);
126 if (err)
127 put_cred(cred);
128 else
129 *new_cred = cred;
130 }
131
132 return err;
133 }
134
135 void free_user_ns(struct user_namespace *ns)
136 {
137 struct user_namespace *parent;
138
139 do {
140 parent = ns->parent;
141 proc_free_inum(ns->proc_inum);
142 kmem_cache_free(user_ns_cachep, ns);
143 ns = parent;
144 } while (atomic_dec_and_test(&parent->count));
145 }
146 EXPORT_SYMBOL(free_user_ns);
147
148 static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
149 {
150 unsigned idx, extents;
151 u32 first, last, id2;
152
153 id2 = id + count - 1;
154
155 /* Find the matching extent */
156 extents = map->nr_extents;
157 smp_rmb();
158 for (idx = 0; idx < extents; idx++) {
159 first = map->extent[idx].first;
160 last = first + map->extent[idx].count - 1;
161 if (id >= first && id <= last &&
162 (id2 >= first && id2 <= last))
163 break;
164 }
165 /* Map the id or note failure */
166 if (idx < extents)
167 id = (id - first) + map->extent[idx].lower_first;
168 else
169 id = (u32) -1;
170
171 return id;
172 }
173
174 static u32 map_id_down(struct uid_gid_map *map, u32 id)
175 {
176 unsigned idx, extents;
177 u32 first, last;
178
179 /* Find the matching extent */
180 extents = map->nr_extents;
181 smp_rmb();
182 for (idx = 0; idx < extents; idx++) {
183 first = map->extent[idx].first;
184 last = first + map->extent[idx].count - 1;
185 if (id >= first && id <= last)
186 break;
187 }
188 /* Map the id or note failure */
189 if (idx < extents)
190 id = (id - first) + map->extent[idx].lower_first;
191 else
192 id = (u32) -1;
193
194 return id;
195 }
196
197 static u32 map_id_up(struct uid_gid_map *map, u32 id)
198 {
199 unsigned idx, extents;
200 u32 first, last;
201
202 /* Find the matching extent */
203 extents = map->nr_extents;
204 smp_rmb();
205 for (idx = 0; idx < extents; idx++) {
206 first = map->extent[idx].lower_first;
207 last = first + map->extent[idx].count - 1;
208 if (id >= first && id <= last)
209 break;
210 }
211 /* Map the id or note failure */
212 if (idx < extents)
213 id = (id - first) + map->extent[idx].first;
214 else
215 id = (u32) -1;
216
217 return id;
218 }
219
220 /**
221 * make_kuid - Map a user-namespace uid pair into a kuid.
222 * @ns: User namespace that the uid is in
223 * @uid: User identifier
224 *
225 * Maps a user-namespace uid pair into a kernel internal kuid,
226 * and returns that kuid.
227 *
228 * When there is no mapping defined for the user-namespace uid
229 * pair INVALID_UID is returned. Callers are expected to test
230 * for and handle handle INVALID_UID being returned. INVALID_UID
231 * may be tested for using uid_valid().
232 */
233 kuid_t make_kuid(struct user_namespace *ns, uid_t uid)
234 {
235 /* Map the uid to a global kernel uid */
236 return KUIDT_INIT(map_id_down(&ns->uid_map, uid));
237 }
238 EXPORT_SYMBOL(make_kuid);
239
240 /**
241 * from_kuid - Create a uid from a kuid user-namespace pair.
242 * @targ: The user namespace we want a uid in.
243 * @kuid: The kernel internal uid to start with.
244 *
245 * Map @kuid into the user-namespace specified by @targ and
246 * return the resulting uid.
247 *
248 * There is always a mapping into the initial user_namespace.
249 *
250 * If @kuid has no mapping in @targ (uid_t)-1 is returned.
251 */
252 uid_t from_kuid(struct user_namespace *targ, kuid_t kuid)
253 {
254 /* Map the uid from a global kernel uid */
255 return map_id_up(&targ->uid_map, __kuid_val(kuid));
256 }
257 EXPORT_SYMBOL(from_kuid);
258
259 /**
260 * from_kuid_munged - Create a uid from a kuid user-namespace pair.
261 * @targ: The user namespace we want a uid in.
262 * @kuid: The kernel internal uid to start with.
263 *
264 * Map @kuid into the user-namespace specified by @targ and
265 * return the resulting uid.
266 *
267 * There is always a mapping into the initial user_namespace.
268 *
269 * Unlike from_kuid from_kuid_munged never fails and always
270 * returns a valid uid. This makes from_kuid_munged appropriate
271 * for use in syscalls like stat and getuid where failing the
272 * system call and failing to provide a valid uid are not an
273 * options.
274 *
275 * If @kuid has no mapping in @targ overflowuid is returned.
276 */
277 uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid)
278 {
279 uid_t uid;
280 uid = from_kuid(targ, kuid);
281
282 if (uid == (uid_t) -1)
283 uid = overflowuid;
284 return uid;
285 }
286 EXPORT_SYMBOL(from_kuid_munged);
287
288 /**
289 * make_kgid - Map a user-namespace gid pair into a kgid.
290 * @ns: User namespace that the gid is in
291 * @uid: group identifier
292 *
293 * Maps a user-namespace gid pair into a kernel internal kgid,
294 * and returns that kgid.
295 *
296 * When there is no mapping defined for the user-namespace gid
297 * pair INVALID_GID is returned. Callers are expected to test
298 * for and handle INVALID_GID being returned. INVALID_GID may be
299 * tested for using gid_valid().
300 */
301 kgid_t make_kgid(struct user_namespace *ns, gid_t gid)
302 {
303 /* Map the gid to a global kernel gid */
304 return KGIDT_INIT(map_id_down(&ns->gid_map, gid));
305 }
306 EXPORT_SYMBOL(make_kgid);
307
308 /**
309 * from_kgid - Create a gid from a kgid user-namespace pair.
310 * @targ: The user namespace we want a gid in.
311 * @kgid: The kernel internal gid to start with.
312 *
313 * Map @kgid into the user-namespace specified by @targ and
314 * return the resulting gid.
315 *
316 * There is always a mapping into the initial user_namespace.
317 *
318 * If @kgid has no mapping in @targ (gid_t)-1 is returned.
319 */
320 gid_t from_kgid(struct user_namespace *targ, kgid_t kgid)
321 {
322 /* Map the gid from a global kernel gid */
323 return map_id_up(&targ->gid_map, __kgid_val(kgid));
324 }
325 EXPORT_SYMBOL(from_kgid);
326
327 /**
328 * from_kgid_munged - Create a gid from a kgid user-namespace pair.
329 * @targ: The user namespace we want a gid in.
330 * @kgid: The kernel internal gid to start with.
331 *
332 * Map @kgid into the user-namespace specified by @targ and
333 * return the resulting gid.
334 *
335 * There is always a mapping into the initial user_namespace.
336 *
337 * Unlike from_kgid from_kgid_munged never fails and always
338 * returns a valid gid. This makes from_kgid_munged appropriate
339 * for use in syscalls like stat and getgid where failing the
340 * system call and failing to provide a valid gid are not options.
341 *
342 * If @kgid has no mapping in @targ overflowgid is returned.
343 */
344 gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid)
345 {
346 gid_t gid;
347 gid = from_kgid(targ, kgid);
348
349 if (gid == (gid_t) -1)
350 gid = overflowgid;
351 return gid;
352 }
353 EXPORT_SYMBOL(from_kgid_munged);
354
355 /**
356 * make_kprojid - Map a user-namespace projid pair into a kprojid.
357 * @ns: User namespace that the projid is in
358 * @projid: Project identifier
359 *
360 * Maps a user-namespace uid pair into a kernel internal kuid,
361 * and returns that kuid.
362 *
363 * When there is no mapping defined for the user-namespace projid
364 * pair INVALID_PROJID is returned. Callers are expected to test
365 * for and handle handle INVALID_PROJID being returned. INVALID_PROJID
366 * may be tested for using projid_valid().
367 */
368 kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid)
369 {
370 /* Map the uid to a global kernel uid */
371 return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid));
372 }
373 EXPORT_SYMBOL(make_kprojid);
374
375 /**
376 * from_kprojid - Create a projid from a kprojid user-namespace pair.
377 * @targ: The user namespace we want a projid in.
378 * @kprojid: The kernel internal project identifier to start with.
379 *
380 * Map @kprojid into the user-namespace specified by @targ and
381 * return the resulting projid.
382 *
383 * There is always a mapping into the initial user_namespace.
384 *
385 * If @kprojid has no mapping in @targ (projid_t)-1 is returned.
386 */
387 projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid)
388 {
389 /* Map the uid from a global kernel uid */
390 return map_id_up(&targ->projid_map, __kprojid_val(kprojid));
391 }
392 EXPORT_SYMBOL(from_kprojid);
393
394 /**
395 * from_kprojid_munged - Create a projiid from a kprojid user-namespace pair.
396 * @targ: The user namespace we want a projid in.
397 * @kprojid: The kernel internal projid to start with.
398 *
399 * Map @kprojid into the user-namespace specified by @targ and
400 * return the resulting projid.
401 *
402 * There is always a mapping into the initial user_namespace.
403 *
404 * Unlike from_kprojid from_kprojid_munged never fails and always
405 * returns a valid projid. This makes from_kprojid_munged
406 * appropriate for use in syscalls like stat and where
407 * failing the system call and failing to provide a valid projid are
408 * not an options.
409 *
410 * If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned.
411 */
412 projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid)
413 {
414 projid_t projid;
415 projid = from_kprojid(targ, kprojid);
416
417 if (projid == (projid_t) -1)
418 projid = OVERFLOW_PROJID;
419 return projid;
420 }
421 EXPORT_SYMBOL(from_kprojid_munged);
422
423
424 static int uid_m_show(struct seq_file *seq, void *v)
425 {
426 struct user_namespace *ns = seq->private;
427 struct uid_gid_extent *extent = v;
428 struct user_namespace *lower_ns;
429 uid_t lower;
430
431 lower_ns = seq_user_ns(seq);
432 if ((lower_ns == ns) && lower_ns->parent)
433 lower_ns = lower_ns->parent;
434
435 lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first));
436
437 seq_printf(seq, "%10u %10u %10u\n",
438 extent->first,
439 lower,
440 extent->count);
441
442 return 0;
443 }
444
445 static int gid_m_show(struct seq_file *seq, void *v)
446 {
447 struct user_namespace *ns = seq->private;
448 struct uid_gid_extent *extent = v;
449 struct user_namespace *lower_ns;
450 gid_t lower;
451
452 lower_ns = seq_user_ns(seq);
453 if ((lower_ns == ns) && lower_ns->parent)
454 lower_ns = lower_ns->parent;
455
456 lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first));
457
458 seq_printf(seq, "%10u %10u %10u\n",
459 extent->first,
460 lower,
461 extent->count);
462
463 return 0;
464 }
465
466 static int projid_m_show(struct seq_file *seq, void *v)
467 {
468 struct user_namespace *ns = seq->private;
469 struct uid_gid_extent *extent = v;
470 struct user_namespace *lower_ns;
471 projid_t lower;
472
473 lower_ns = seq_user_ns(seq);
474 if ((lower_ns == ns) && lower_ns->parent)
475 lower_ns = lower_ns->parent;
476
477 lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first));
478
479 seq_printf(seq, "%10u %10u %10u\n",
480 extent->first,
481 lower,
482 extent->count);
483
484 return 0;
485 }
486
487 static void *m_start(struct seq_file *seq, loff_t *ppos, struct uid_gid_map *map)
488 {
489 struct uid_gid_extent *extent = NULL;
490 loff_t pos = *ppos;
491
492 if (pos < map->nr_extents)
493 extent = &map->extent[pos];
494
495 return extent;
496 }
497
498 static void *uid_m_start(struct seq_file *seq, loff_t *ppos)
499 {
500 struct user_namespace *ns = seq->private;
501
502 return m_start(seq, ppos, &ns->uid_map);
503 }
504
505 static void *gid_m_start(struct seq_file *seq, loff_t *ppos)
506 {
507 struct user_namespace *ns = seq->private;
508
509 return m_start(seq, ppos, &ns->gid_map);
510 }
511
512 static void *projid_m_start(struct seq_file *seq, loff_t *ppos)
513 {
514 struct user_namespace *ns = seq->private;
515
516 return m_start(seq, ppos, &ns->projid_map);
517 }
518
519 static void *m_next(struct seq_file *seq, void *v, loff_t *pos)
520 {
521 (*pos)++;
522 return seq->op->start(seq, pos);
523 }
524
525 static void m_stop(struct seq_file *seq, void *v)
526 {
527 return;
528 }
529
530 struct seq_operations proc_uid_seq_operations = {
531 .start = uid_m_start,
532 .stop = m_stop,
533 .next = m_next,
534 .show = uid_m_show,
535 };
536
537 struct seq_operations proc_gid_seq_operations = {
538 .start = gid_m_start,
539 .stop = m_stop,
540 .next = m_next,
541 .show = gid_m_show,
542 };
543
544 struct seq_operations proc_projid_seq_operations = {
545 .start = projid_m_start,
546 .stop = m_stop,
547 .next = m_next,
548 .show = projid_m_show,
549 };
550
551 static bool mappings_overlap(struct uid_gid_map *new_map, struct uid_gid_extent *extent)
552 {
553 u32 upper_first, lower_first, upper_last, lower_last;
554 unsigned idx;
555
556 upper_first = extent->first;
557 lower_first = extent->lower_first;
558 upper_last = upper_first + extent->count - 1;
559 lower_last = lower_first + extent->count - 1;
560
561 for (idx = 0; idx < new_map->nr_extents; idx++) {
562 u32 prev_upper_first, prev_lower_first;
563 u32 prev_upper_last, prev_lower_last;
564 struct uid_gid_extent *prev;
565
566 prev = &new_map->extent[idx];
567
568 prev_upper_first = prev->first;
569 prev_lower_first = prev->lower_first;
570 prev_upper_last = prev_upper_first + prev->count - 1;
571 prev_lower_last = prev_lower_first + prev->count - 1;
572
573 /* Does the upper range intersect a previous extent? */
574 if ((prev_upper_first <= upper_last) &&
575 (prev_upper_last >= upper_first))
576 return true;
577
578 /* Does the lower range intersect a previous extent? */
579 if ((prev_lower_first <= lower_last) &&
580 (prev_lower_last >= lower_first))
581 return true;
582 }
583 return false;
584 }
585
586 static ssize_t map_write(struct file *file, const char __user *buf,
587 size_t count, loff_t *ppos,
588 int cap_setid,
589 struct uid_gid_map *map,
590 struct uid_gid_map *parent_map)
591 {
592 struct seq_file *seq = file->private_data;
593 struct user_namespace *ns = seq->private;
594 struct uid_gid_map new_map;
595 unsigned idx;
596 struct uid_gid_extent *extent = NULL;
597 unsigned long page = 0;
598 char *kbuf, *pos, *next_line;
599 ssize_t ret = -EINVAL;
600
601 /*
602 * The userns_state_mutex serializes all writes to any given map.
603 *
604 * Any map is only ever written once.
605 *
606 * An id map fits within 1 cache line on most architectures.
607 *
608 * On read nothing needs to be done unless you are on an
609 * architecture with a crazy cache coherency model like alpha.
610 *
611 * There is a one time data dependency between reading the
612 * count of the extents and the values of the extents. The
613 * desired behavior is to see the values of the extents that
614 * were written before the count of the extents.
615 *
616 * To achieve this smp_wmb() is used on guarantee the write
617 * order and smp_rmb() is guaranteed that we don't have crazy
618 * architectures returning stale data.
619 */
620 mutex_lock(&userns_state_mutex);
621
622 ret = -EPERM;
623 /* Only allow one successful write to the map */
624 if (map->nr_extents != 0)
625 goto out;
626
627 /*
628 * Adjusting namespace settings requires capabilities on the target.
629 */
630 if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
631 goto out;
632
633 /* Get a buffer */
634 ret = -ENOMEM;
635 page = __get_free_page(GFP_TEMPORARY);
636 kbuf = (char *) page;
637 if (!page)
638 goto out;
639
640 /* Only allow <= page size writes at the beginning of the file */
641 ret = -EINVAL;
642 if ((*ppos != 0) || (count >= PAGE_SIZE))
643 goto out;
644
645 /* Slurp in the user data */
646 ret = -EFAULT;
647 if (copy_from_user(kbuf, buf, count))
648 goto out;
649 kbuf[count] = '\0';
650
651 /* Parse the user data */
652 ret = -EINVAL;
653 pos = kbuf;
654 new_map.nr_extents = 0;
655 for (;pos; pos = next_line) {
656 extent = &new_map.extent[new_map.nr_extents];
657
658 /* Find the end of line and ensure I don't look past it */
659 next_line = strchr(pos, '\n');
660 if (next_line) {
661 *next_line = '\0';
662 next_line++;
663 if (*next_line == '\0')
664 next_line = NULL;
665 }
666
667 pos = skip_spaces(pos);
668 extent->first = simple_strtoul(pos, &pos, 10);
669 if (!isspace(*pos))
670 goto out;
671
672 pos = skip_spaces(pos);
673 extent->lower_first = simple_strtoul(pos, &pos, 10);
674 if (!isspace(*pos))
675 goto out;
676
677 pos = skip_spaces(pos);
678 extent->count = simple_strtoul(pos, &pos, 10);
679 if (*pos && !isspace(*pos))
680 goto out;
681
682 /* Verify there is not trailing junk on the line */
683 pos = skip_spaces(pos);
684 if (*pos != '\0')
685 goto out;
686
687 /* Verify we have been given valid starting values */
688 if ((extent->first == (u32) -1) ||
689 (extent->lower_first == (u32) -1 ))
690 goto out;
691
692 /* Verify count is not zero and does not cause the extent to wrap */
693 if ((extent->first + extent->count) <= extent->first)
694 goto out;
695 if ((extent->lower_first + extent->count) <= extent->lower_first)
696 goto out;
697
698 /* Do the ranges in extent overlap any previous extents? */
699 if (mappings_overlap(&new_map, extent))
700 goto out;
701
702 new_map.nr_extents++;
703
704 /* Fail if the file contains too many extents */
705 if ((new_map.nr_extents == UID_GID_MAP_MAX_EXTENTS) &&
706 (next_line != NULL))
707 goto out;
708 }
709 /* Be very certaint the new map actually exists */
710 if (new_map.nr_extents == 0)
711 goto out;
712
713 ret = -EPERM;
714 /* Validate the user is allowed to use user id's mapped to. */
715 if (!new_idmap_permitted(file, ns, cap_setid, &new_map))
716 goto out;
717
718 /* Map the lower ids from the parent user namespace to the
719 * kernel global id space.
720 */
721 for (idx = 0; idx < new_map.nr_extents; idx++) {
722 u32 lower_first;
723 extent = &new_map.extent[idx];
724
725 lower_first = map_id_range_down(parent_map,
726 extent->lower_first,
727 extent->count);
728
729 /* Fail if we can not map the specified extent to
730 * the kernel global id space.
731 */
732 if (lower_first == (u32) -1)
733 goto out;
734
735 extent->lower_first = lower_first;
736 }
737
738 /* Install the map */
739 memcpy(map->extent, new_map.extent,
740 new_map.nr_extents*sizeof(new_map.extent[0]));
741 smp_wmb();
742 map->nr_extents = new_map.nr_extents;
743
744 *ppos = count;
745 ret = count;
746 out:
747 mutex_unlock(&userns_state_mutex);
748 if (page)
749 free_page(page);
750 return ret;
751 }
752
753 ssize_t proc_uid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos)
754 {
755 struct seq_file *seq = file->private_data;
756 struct user_namespace *ns = seq->private;
757 struct user_namespace *seq_ns = seq_user_ns(seq);
758
759 if (!ns->parent)
760 return -EPERM;
761
762 if ((seq_ns != ns) && (seq_ns != ns->parent))
763 return -EPERM;
764
765 return map_write(file, buf, size, ppos, CAP_SETUID,
766 &ns->uid_map, &ns->parent->uid_map);
767 }
768
769 ssize_t proc_gid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos)
770 {
771 struct seq_file *seq = file->private_data;
772 struct user_namespace *ns = seq->private;
773 struct user_namespace *seq_ns = seq_user_ns(seq);
774
775 if (!ns->parent)
776 return -EPERM;
777
778 if ((seq_ns != ns) && (seq_ns != ns->parent))
779 return -EPERM;
780
781 return map_write(file, buf, size, ppos, CAP_SETGID,
782 &ns->gid_map, &ns->parent->gid_map);
783 }
784
785 ssize_t proc_projid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos)
786 {
787 struct seq_file *seq = file->private_data;
788 struct user_namespace *ns = seq->private;
789 struct user_namespace *seq_ns = seq_user_ns(seq);
790
791 if (!ns->parent)
792 return -EPERM;
793
794 if ((seq_ns != ns) && (seq_ns != ns->parent))
795 return -EPERM;
796
797 /* Anyone can set any valid project id no capability needed */
798 return map_write(file, buf, size, ppos, -1,
799 &ns->projid_map, &ns->parent->projid_map);
800 }
801
802 static bool new_idmap_permitted(const struct file *file,
803 struct user_namespace *ns, int cap_setid,
804 struct uid_gid_map *new_map)
805 {
806 const struct cred *cred = file->f_cred;
807 /* Don't allow mappings that would allow anything that wouldn't
808 * be allowed without the establishment of unprivileged mappings.
809 */
810 if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) &&
811 uid_eq(ns->owner, cred->euid)) {
812 u32 id = new_map->extent[0].lower_first;
813 if (cap_setid == CAP_SETUID) {
814 kuid_t uid = make_kuid(ns->parent, id);
815 if (uid_eq(uid, cred->euid))
816 return true;
817 } else if (cap_setid == CAP_SETGID) {
818 kgid_t gid = make_kgid(ns->parent, id);
819 if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) &&
820 gid_eq(gid, cred->egid))
821 return true;
822 }
823 }
824
825 /* Allow anyone to set a mapping that doesn't require privilege */
826 if (!cap_valid(cap_setid))
827 return true;
828
829 /* Allow the specified ids if we have the appropriate capability
830 * (CAP_SETUID or CAP_SETGID) over the parent user namespace.
831 * And the opener of the id file also had the approprpiate capability.
832 */
833 if (ns_capable(ns->parent, cap_setid) &&
834 file_ns_capable(file, ns->parent, cap_setid))
835 return true;
836
837 return false;
838 }
839
840 int proc_setgroups_show(struct seq_file *seq, void *v)
841 {
842 struct user_namespace *ns = seq->private;
843 unsigned long userns_flags = ACCESS_ONCE(ns->flags);
844
845 seq_printf(seq, "%s\n",
846 (userns_flags & USERNS_SETGROUPS_ALLOWED) ?
847 "allow" : "deny");
848 return 0;
849 }
850
851 ssize_t proc_setgroups_write(struct file *file, const char __user *buf,
852 size_t count, loff_t *ppos)
853 {
854 struct seq_file *seq = file->private_data;
855 struct user_namespace *ns = seq->private;
856 char kbuf[8], *pos;
857 bool setgroups_allowed;
858 ssize_t ret;
859
860 /* Only allow a very narrow range of strings to be written */
861 ret = -EINVAL;
862 if ((*ppos != 0) || (count >= sizeof(kbuf)))
863 goto out;
864
865 /* What was written? */
866 ret = -EFAULT;
867 if (copy_from_user(kbuf, buf, count))
868 goto out;
869 kbuf[count] = '\0';
870 pos = kbuf;
871
872 /* What is being requested? */
873 ret = -EINVAL;
874 if (strncmp(pos, "allow", 5) == 0) {
875 pos += 5;
876 setgroups_allowed = true;
877 }
878 else if (strncmp(pos, "deny", 4) == 0) {
879 pos += 4;
880 setgroups_allowed = false;
881 }
882 else
883 goto out;
884
885 /* Verify there is not trailing junk on the line */
886 pos = skip_spaces(pos);
887 if (*pos != '\0')
888 goto out;
889
890 ret = -EPERM;
891 mutex_lock(&userns_state_mutex);
892 if (setgroups_allowed) {
893 /* Enabling setgroups after setgroups has been disabled
894 * is not allowed.
895 */
896 if (!(ns->flags & USERNS_SETGROUPS_ALLOWED))
897 goto out_unlock;
898 } else {
899 /* Permanently disabling setgroups after setgroups has
900 * been enabled by writing the gid_map is not allowed.
901 */
902 if (ns->gid_map.nr_extents != 0)
903 goto out_unlock;
904 ns->flags &= ~USERNS_SETGROUPS_ALLOWED;
905 }
906 mutex_unlock(&userns_state_mutex);
907
908 /* Report a successful write */
909 *ppos = count;
910 ret = count;
911 out:
912 return ret;
913 out_unlock:
914 mutex_unlock(&userns_state_mutex);
915 goto out;
916 }
917
918 bool userns_may_setgroups(const struct user_namespace *ns)
919 {
920 bool allowed;
921
922 mutex_lock(&userns_state_mutex);
923 /* It is not safe to use setgroups until a gid mapping in
924 * the user namespace has been established.
925 */
926 allowed = ns->gid_map.nr_extents != 0;
927 /* Is setgroups allowed? */
928 allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED);
929 mutex_unlock(&userns_state_mutex);
930
931 return allowed;
932 }
933
934 static void *userns_get(struct task_struct *task)
935 {
936 struct user_namespace *user_ns;
937
938 rcu_read_lock();
939 user_ns = get_user_ns(__task_cred(task)->user_ns);
940 rcu_read_unlock();
941
942 return user_ns;
943 }
944
945 static void userns_put(void *ns)
946 {
947 put_user_ns(ns);
948 }
949
950 static int userns_install(struct nsproxy *nsproxy, void *ns)
951 {
952 struct user_namespace *user_ns = ns;
953 struct cred *cred;
954
955 /* Don't allow gaining capabilities by reentering
956 * the same user namespace.
957 */
958 if (user_ns == current_user_ns())
959 return -EINVAL;
960
961 /* Threaded processes may not enter a different user namespace */
962 if (atomic_read(&current->mm->mm_users) > 1)
963 return -EINVAL;
964
965 if (current->fs->users != 1)
966 return -EINVAL;
967
968 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
969 return -EPERM;
970
971 cred = prepare_creds();
972 if (!cred)
973 return -ENOMEM;
974
975 put_user_ns(cred->user_ns);
976 set_cred_user_ns(cred, get_user_ns(user_ns));
977
978 return commit_creds(cred);
979 }
980
981 static unsigned int userns_inum(void *ns)
982 {
983 struct user_namespace *user_ns = ns;
984 return user_ns->proc_inum;
985 }
986
987 const struct proc_ns_operations userns_operations = {
988 .name = "user",
989 .type = CLONE_NEWUSER,
990 .get = userns_get,
991 .put = userns_put,
992 .install = userns_install,
993 .inum = userns_inum,
994 };
995
996 static __init int user_namespaces_init(void)
997 {
998 user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
999 return 0;
1000 }
1001 module_init(user_namespaces_init);