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TOMOYO Linux Cross Reference
Linux/kernel/user_namespace.c

Version: ~ [ linux-5.1-rc2 ] ~ [ linux-5.0.4 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.31 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.108 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.165 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.177 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.137 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.63 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  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/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 
 29 static struct kmem_cache *user_ns_cachep __read_mostly;
 30 static DEFINE_MUTEX(userns_state_mutex);
 31 
 32 static bool new_idmap_permitted(const struct file *file,
 33                                 struct user_namespace *ns, int cap_setid,
 34                                 struct uid_gid_map *map);
 35 static void free_user_ns(struct work_struct *work);
 36 
 37 static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid)
 38 {
 39         return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES);
 40 }
 41 
 42 static void dec_user_namespaces(struct ucounts *ucounts)
 43 {
 44         return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES);
 45 }
 46 
 47 static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns)
 48 {
 49         /* Start with the same capabilities as init but useless for doing
 50          * anything as the capabilities are bound to the new user namespace.
 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         /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
 63         cred->user_ns = user_ns;
 64 }
 65 
 66 /*
 67  * Create a new user namespace, deriving the creator from the user in the
 68  * passed credentials, and replacing that user with the new root user for the
 69  * new namespace.
 70  *
 71  * This is called by copy_creds(), which will finish setting the target task's
 72  * credentials.
 73  */
 74 int 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          * Verify that we can not violate the policy of which files
 92          * may be accessed that is specified by the root directory,
 93          * by verifing that the root directory is at the root of the
 94          * mount namespace which allows all files to be accessed.
 95          */
 96         ret = -EPERM;
 97         if (current_chrooted())
 98                 goto fail_dec;
 99 
100         /* The creator needs a mapping in the parent user namespace
101          * or else we won't be able to reasonably tell userspace who
102          * created a user_namespace.
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         /* Leave the new->user_ns reference with the new user namespace. */
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         /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
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;
145 fail_keyring:
146 #ifdef CONFIG_PERSISTENT_KEYRINGS
147         key_put(ns->persistent_keyring_register);
148 #endif
149         ns_free_inum(&ns->ns);
150 fail_free:
151         kmem_cache_free(user_ns_cachep, ns);
152 fail_dec:
153         dec_user_namespaces(ucounts);
154 fail:
155         return ret;
156 }
157 
158 int 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 
178 static 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 
209 void __put_user_ns(struct user_namespace *ns)
210 {
211         schedule_work(&ns->work);
212 }
213 EXPORT_SYMBOL(__put_user_ns);
214 
215 /**
216  * idmap_key struct holds the information necessary to find an idmapping in a
217  * sorted idmap array. It is passed to cmp_map_id() as first argument.
218  */
219 struct idmap_key {
220         bool map_up; /* true  -> id from kid; false -> kid from id */
221         u32 id; /* id to find */
222         u32 count; /* == 0 unless used with map_id_range_down() */
223 };
224 
225 /**
226  * cmp_map_id - Function to be passed to bsearch() to find the requested
227  * idmapping. Expects struct idmap_key to be passed via @k.
228  */
229 static 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         /* handle map_id_{down,up}() */
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  * map_id_range_down_max - Find idmap via binary search in ordered idmap array.
257  * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
258  */
259 static struct uid_gid_extent *
260 map_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  * map_id_range_down_base - Find idmap via binary search in static extent array.
274  * Can only be called if number of mappings is equal or less than
275  * UID_GID_MAP_MAX_BASE_EXTENTS.
276  */
277 static struct uid_gid_extent *
278 map_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         /* Find the matching extent */
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 
296 static 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         /* Map the id or note failure */
308         if (extent)
309                 id = (id - extent->first) + extent->lower_first;
310         else
311                 id = (u32) -1;
312 
313         return id;
314 }
315 
316 static 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  * map_id_up_base - Find idmap via binary search in static extent array.
323  * Can only be called if number of mappings is equal or less than
324  * UID_GID_MAP_MAX_BASE_EXTENTS.
325  */
326 static struct uid_gid_extent *
327 map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id)
328 {
329         unsigned idx;
330         u32 first, last;
331 
332         /* Find the matching extent */
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  * map_id_up_max - Find idmap via binary search in ordered idmap array.
344  * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
345  */
346 static struct uid_gid_extent *
347 map_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 
359 static 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         /* Map the id or note failure */
371         if (extent)
372                 id = (id - extent->lower_first) + extent->first;
373         else
374                 id = (u32) -1;
375 
376         return id;
377 }
378 
379 /**
380  *      make_kuid - Map a user-namespace uid pair into a kuid.
381  *      @ns:  User namespace that the uid is in
382  *      @uid: User identifier
383  *
384  *      Maps a user-namespace uid pair into a kernel internal kuid,
385  *      and returns that kuid.
386  *
387  *      When there is no mapping defined for the user-namespace uid
388  *      pair INVALID_UID is returned.  Callers are expected to test
389  *      for and handle INVALID_UID being returned.  INVALID_UID
390  *      may be tested for using uid_valid().
391  */
392 kuid_t make_kuid(struct user_namespace *ns, uid_t uid)
393 {
394         /* Map the uid to a global kernel uid */
395         return KUIDT_INIT(map_id_down(&ns->uid_map, uid));
396 }
397 EXPORT_SYMBOL(make_kuid);
398 
399 /**
400  *      from_kuid - Create a uid from a kuid user-namespace pair.
401  *      @targ: The user namespace we want a uid in.
402  *      @kuid: The kernel internal uid to start with.
403  *
404  *      Map @kuid into the user-namespace specified by @targ and
405  *      return the resulting uid.
406  *
407  *      There is always a mapping into the initial user_namespace.
408  *
409  *      If @kuid has no mapping in @targ (uid_t)-1 is returned.
410  */
411 uid_t from_kuid(struct user_namespace *targ, kuid_t kuid)
412 {
413         /* Map the uid from a global kernel uid */
414         return map_id_up(&targ->uid_map, __kuid_val(kuid));
415 }
416 EXPORT_SYMBOL(from_kuid);
417 
418 /**
419  *      from_kuid_munged - Create a uid from a kuid user-namespace pair.
420  *      @targ: The user namespace we want a uid in.
421  *      @kuid: The kernel internal uid to start with.
422  *
423  *      Map @kuid into the user-namespace specified by @targ and
424  *      return the resulting uid.
425  *
426  *      There is always a mapping into the initial user_namespace.
427  *
428  *      Unlike from_kuid from_kuid_munged never fails and always
429  *      returns a valid uid.  This makes from_kuid_munged appropriate
430  *      for use in syscalls like stat and getuid where failing the
431  *      system call and failing to provide a valid uid are not an
432  *      options.
433  *
434  *      If @kuid has no mapping in @targ overflowuid is returned.
435  */
436 uid_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 }
445 EXPORT_SYMBOL(from_kuid_munged);
446 
447 /**
448  *      make_kgid - Map a user-namespace gid pair into a kgid.
449  *      @ns:  User namespace that the gid is in
450  *      @gid: group identifier
451  *
452  *      Maps a user-namespace gid pair into a kernel internal kgid,
453  *      and returns that kgid.
454  *
455  *      When there is no mapping defined for the user-namespace gid
456  *      pair INVALID_GID is returned.  Callers are expected to test
457  *      for and handle INVALID_GID being returned.  INVALID_GID may be
458  *      tested for using gid_valid().
459  */
460 kgid_t make_kgid(struct user_namespace *ns, gid_t gid)
461 {
462         /* Map the gid to a global kernel gid */
463         return KGIDT_INIT(map_id_down(&ns->gid_map, gid));
464 }
465 EXPORT_SYMBOL(make_kgid);
466 
467 /**
468  *      from_kgid - Create a gid from a kgid user-namespace pair.
469  *      @targ: The user namespace we want a gid in.
470  *      @kgid: The kernel internal gid to start with.
471  *
472  *      Map @kgid into the user-namespace specified by @targ and
473  *      return the resulting gid.
474  *
475  *      There is always a mapping into the initial user_namespace.
476  *
477  *      If @kgid has no mapping in @targ (gid_t)-1 is returned.
478  */
479 gid_t from_kgid(struct user_namespace *targ, kgid_t kgid)
480 {
481         /* Map the gid from a global kernel gid */
482         return map_id_up(&targ->gid_map, __kgid_val(kgid));
483 }
484 EXPORT_SYMBOL(from_kgid);
485 
486 /**
487  *      from_kgid_munged - Create a gid from a kgid user-namespace pair.
488  *      @targ: The user namespace we want a gid in.
489  *      @kgid: The kernel internal gid to start with.
490  *
491  *      Map @kgid into the user-namespace specified by @targ and
492  *      return the resulting gid.
493  *
494  *      There is always a mapping into the initial user_namespace.
495  *
496  *      Unlike from_kgid from_kgid_munged never fails and always
497  *      returns a valid gid.  This makes from_kgid_munged appropriate
498  *      for use in syscalls like stat and getgid where failing the
499  *      system call and failing to provide a valid gid are not options.
500  *
501  *      If @kgid has no mapping in @targ overflowgid is returned.
502  */
503 gid_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 }
512 EXPORT_SYMBOL(from_kgid_munged);
513 
514 /**
515  *      make_kprojid - Map a user-namespace projid pair into a kprojid.
516  *      @ns:  User namespace that the projid is in
517  *      @projid: Project identifier
518  *
519  *      Maps a user-namespace uid pair into a kernel internal kuid,
520  *      and returns that kuid.
521  *
522  *      When there is no mapping defined for the user-namespace projid
523  *      pair INVALID_PROJID is returned.  Callers are expected to test
524  *      for and handle handle INVALID_PROJID being returned.  INVALID_PROJID
525  *      may be tested for using projid_valid().
526  */
527 kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid)
528 {
529         /* Map the uid to a global kernel uid */
530         return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid));
531 }
532 EXPORT_SYMBOL(make_kprojid);
533 
534 /**
535  *      from_kprojid - Create a projid from a kprojid user-namespace pair.
536  *      @targ: The user namespace we want a projid in.
537  *      @kprojid: The kernel internal project identifier to start with.
538  *
539  *      Map @kprojid into the user-namespace specified by @targ and
540  *      return the resulting projid.
541  *
542  *      There is always a mapping into the initial user_namespace.
543  *
544  *      If @kprojid has no mapping in @targ (projid_t)-1 is returned.
545  */
546 projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid)
547 {
548         /* Map the uid from a global kernel uid */
549         return map_id_up(&targ->projid_map, __kprojid_val(kprojid));
550 }
551 EXPORT_SYMBOL(from_kprojid);
552 
553 /**
554  *      from_kprojid_munged - Create a projiid from a kprojid user-namespace pair.
555  *      @targ: The user namespace we want a projid in.
556  *      @kprojid: The kernel internal projid to start with.
557  *
558  *      Map @kprojid into the user-namespace specified by @targ and
559  *      return the resulting projid.
560  *
561  *      There is always a mapping into the initial user_namespace.
562  *
563  *      Unlike from_kprojid from_kprojid_munged never fails and always
564  *      returns a valid projid.  This makes from_kprojid_munged
565  *      appropriate for use in syscalls like stat and where
566  *      failing the system call and failing to provide a valid projid are
567  *      not an options.
568  *
569  *      If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned.
570  */
571 projid_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 }
580 EXPORT_SYMBOL(from_kprojid_munged);
581 
582 
583 static 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 
604 static 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 
625 static 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 
646 static 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 
662 static 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 
669 static 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 
676 static 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 
683 static void *m_next(struct seq_file *seq, void *v, loff_t *pos)
684 {
685         (*pos)++;
686         return seq->op->start(seq, pos);
687 }
688 
689 static void m_stop(struct seq_file *seq, void *v)
690 {
691         return;
692 }
693 
694 const 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 
701 const 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 
708 const 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 
715 static 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                 /* Does the upper range intersect a previous extent? */
742                 if ((prev_upper_first <= upper_last) &&
743                     (prev_upper_last >= upper_first))
744                         return true;
745 
746                 /* Does the lower range intersect a previous extent? */
747                 if ((prev_lower_first <= lower_last) &&
748                     (prev_lower_last >= lower_first))
749                         return true;
750         }
751         return false;
752 }
753 
754 /**
755  * insert_extent - Safely insert a new idmap extent into struct uid_gid_map.
756  * Takes care to allocate a 4K block of memory if the number of mappings exceeds
757  * UID_GID_MAP_MAX_BASE_EXTENTS.
758  */
759 static 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                 /* Allocate memory for 340 mappings. */
767                 forward = kmalloc(sizeof(struct uid_gid_extent) *
768                                  UID_GID_MAP_MAX_EXTENTS, GFP_KERNEL);
769                 if (!forward)
770                         return -ENOMEM;
771 
772                 /* Copy over memory. Only set up memory for the forward pointer.
773                  * Defer the memory setup for the reverse pointer.
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 /* cmp function to sort() forward mappings */
793 static 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 /* cmp function to sort() reverse mappings */
808 static 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  * sort_idmaps - Sorts an array of idmap entries.
824  * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS.
825  */
826 static 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         /* Sort forward array. */
832         sort(map->forward, map->nr_extents, sizeof(struct uid_gid_extent),
833              cmp_extents_forward, NULL);
834 
835         /* Only copy the memory from forward we actually need. */
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         /* Sort reverse array. */
843         sort(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent),
844              cmp_extents_reverse, NULL);
845 
846         return 0;
847 }
848 
849 static 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          * The userns_state_mutex serializes all writes to any given map.
865          *
866          * Any map is only ever written once.
867          *
868          * An id map fits within 1 cache line on most architectures.
869          *
870          * On read nothing needs to be done unless you are on an
871          * architecture with a crazy cache coherency model like alpha.
872          *
873          * There is a one time data dependency between reading the
874          * count of the extents and the values of the extents.  The
875          * desired behavior is to see the values of the extents that
876          * were written before the count of the extents.
877          *
878          * To achieve this smp_wmb() is used on guarantee the write
879          * order and smp_rmb() is guaranteed that we don't have crazy
880          * architectures returning stale data.
881          */
882         mutex_lock(&userns_state_mutex);
883 
884         memset(&new_map, 0, sizeof(struct uid_gid_map));
885 
886         ret = -EPERM;
887         /* Only allow one successful write to the map */
888         if (map->nr_extents != 0)
889                 goto out;
890 
891         /*
892          * Adjusting namespace settings requires capabilities on the target.
893          */
894         if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
895                 goto out;
896 
897         /* Only allow < page size writes at the beginning of the file */
898         ret = -EINVAL;
899         if ((*ppos != 0) || (count >= PAGE_SIZE))
900                 goto out;
901 
902         /* Slurp in the user data */
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         /* Parse the user data */
911         ret = -EINVAL;
912         pos = kbuf;
913         for (; pos; pos = next_line) {
914 
915                 /* Find the end of line and ensure I don't look past it */
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                 /* Verify there is not trailing junk on the line */
940                 pos = skip_spaces(pos);
941                 if (*pos != '\0')
942                         goto out;
943 
944                 /* Verify we have been given valid starting values */
945                 if ((extent.first == (u32) -1) ||
946                     (extent.lower_first == (u32) -1))
947                         goto out;
948 
949                 /* Verify count is not zero and does not cause the
950                  * extent to wrap
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                 /* Do the ranges in extent overlap any previous extents? */
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         /* Be very certaint the new map actually exists */
972         if (new_map.nr_extents == 0)
973                 goto out;
974 
975         ret = -EPERM;
976         /* Validate the user is allowed to use user id's mapped to. */
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         /* Map the lower ids from the parent user namespace to the
986          * kernel global id space.
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                 /* Fail if we can not map the specified extent to
1002                  * the kernel global id space.
1003                  */
1004                 if (lower_first == (u32) -1)
1005                         goto out;
1006 
1007                 e->lower_first = lower_first;
1008         }
1009 
1010         /* Install the map */
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;
1023 out:
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 
1037 ssize_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 
1054 ssize_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 
1071 ssize_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         /* Anyone can set any valid project id no capability needed */
1085         return map_write(file, buf, size, ppos, -1,
1086                          &ns->projid_map, &ns->parent->projid_map);
1087 }
1088 
1089 static 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         /* Don't allow mappings that would allow anything that wouldn't
1095          * be allowed without the establishment of unprivileged mappings.
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         /* Allow anyone to set a mapping that doesn't require privilege */
1113         if (!cap_valid(cap_setid))
1114                 return true;
1115 
1116         /* Allow the specified ids if we have the appropriate capability
1117          * (CAP_SETUID or CAP_SETGID) over the parent user namespace.
1118          * And the opener of the id file also had the approprpiate capability.
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 
1127 int 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 
1138 ssize_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         /* Only allow a very narrow range of strings to be written */
1148         ret = -EINVAL;
1149         if ((*ppos != 0) || (count >= sizeof(kbuf)))
1150                 goto out;
1151 
1152         /* What was written? */
1153         ret = -EFAULT;
1154         if (copy_from_user(kbuf, buf, count))
1155                 goto out;
1156         kbuf[count] = '\0';
1157         pos = kbuf;
1158 
1159         /* What is being requested? */
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         /* Verify there is not trailing junk on the line */
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                 /* Enabling setgroups after setgroups has been disabled
1181                  * is not allowed.
1182                  */
1183                 if (!(ns->flags & USERNS_SETGROUPS_ALLOWED))
1184                         goto out_unlock;
1185         } else {
1186                 /* Permanently disabling setgroups after setgroups has
1187                  * been enabled by writing the gid_map is not allowed.
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         /* Report a successful write */
1196         *ppos = count;
1197         ret = count;
1198 out:
1199         return ret;
1200 out_unlock:
1201         mutex_unlock(&userns_state_mutex);
1202         goto out;
1203 }
1204 
1205 bool userns_may_setgroups(const struct user_namespace *ns)
1206 {
1207         bool allowed;
1208 
1209         mutex_lock(&userns_state_mutex);
1210         /* It is not safe to use setgroups until a gid mapping in
1211          * the user namespace has been established.
1212          */
1213         allowed = ns->gid_map.nr_extents != 0;
1214         /* Is setgroups allowed? */
1215         allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED);
1216         mutex_unlock(&userns_state_mutex);
1217 
1218         return allowed;
1219 }
1220 
1221 /*
1222  * Returns true if @child is the same namespace or a descendant of
1223  * @ancestor.
1224  */
1225 bool 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 
1234 bool current_in_userns(const struct user_namespace *target_ns)
1235 {
1236         return in_userns(target_ns, current_user_ns());
1237 }
1238 
1239 static inline struct user_namespace *to_user_ns(struct ns_common *ns)
1240 {
1241         return container_of(ns, struct user_namespace, ns);
1242 }
1243 
1244 static 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 
1255 static void userns_put(struct ns_common *ns)
1256 {
1257         put_user_ns(to_user_ns(ns));
1258 }
1259 
1260 static 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         /* Don't allow gaining capabilities by reentering
1266          * the same user namespace.
1267          */
1268         if (user_ns == current_user_ns())
1269                 return -EINVAL;
1270 
1271         /* Tasks that share a thread group must share a user namespace */
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 
1291 struct 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         /* See if the owner is in the current user namespace */
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 
1309 static struct user_namespace *userns_owner(struct ns_common *ns)
1310 {
1311         return to_user_ns(ns)->parent;
1312 }
1313 
1314 const 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 
1324 static __init int user_namespaces_init(void)
1325 {
1326         user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
1327         return 0;
1328 }
1329 subsys_initcall(user_namespaces_init);
1330 

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