1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | |
3 | #include <linux/export.h> |
4 | #include <linux/nsproxy.h> |
5 | #include <linux/slab.h> |
6 | #include <linux/sched/signal.h> |
7 | #include <linux/user_namespace.h> |
8 | #include <linux/proc_ns.h> |
9 | #include <linux/highuid.h> |
10 | #include <linux/cred.h> |
11 | #include <linux/securebits.h> |
12 | #include <linux/security.h> |
13 | #include <linux/keyctl.h> |
14 | #include <linux/key-type.h> |
15 | #include <keys/user-type.h> |
16 | #include <linux/seq_file.h> |
17 | #include <linux/fs.h> |
18 | #include <linux/uaccess.h> |
19 | #include <linux/ctype.h> |
20 | #include <linux/projid.h> |
21 | #include <linux/fs_struct.h> |
22 | #include <linux/bsearch.h> |
23 | #include <linux/sort.h> |
24 | |
25 | static struct kmem_cache *user_ns_cachep __ro_after_init; |
26 | static DEFINE_MUTEX(userns_state_mutex); |
27 | |
28 | static bool new_idmap_permitted(const struct file *file, |
29 | struct user_namespace *ns, int cap_setid, |
30 | struct uid_gid_map *map); |
31 | static void free_user_ns(struct work_struct *work); |
32 | |
33 | static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid) |
34 | { |
35 | return inc_ucount(ns, uid, type: UCOUNT_USER_NAMESPACES); |
36 | } |
37 | |
38 | static void dec_user_namespaces(struct ucounts *ucounts) |
39 | { |
40 | return dec_ucount(ucounts, type: UCOUNT_USER_NAMESPACES); |
41 | } |
42 | |
43 | static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns) |
44 | { |
45 | /* Start with the same capabilities as init but useless for doing |
46 | * anything as the capabilities are bound to the new user namespace. |
47 | */ |
48 | cred->securebits = SECUREBITS_DEFAULT; |
49 | cred->cap_inheritable = CAP_EMPTY_SET; |
50 | cred->cap_permitted = CAP_FULL_SET; |
51 | cred->cap_effective = CAP_FULL_SET; |
52 | cred->cap_ambient = CAP_EMPTY_SET; |
53 | cred->cap_bset = CAP_FULL_SET; |
54 | #ifdef CONFIG_KEYS |
55 | key_put(cred->request_key_auth); |
56 | cred->request_key_auth = NULL; |
57 | #endif |
58 | /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ |
59 | cred->user_ns = user_ns; |
60 | } |
61 | |
62 | static unsigned long enforced_nproc_rlimit(void) |
63 | { |
64 | unsigned long limit = RLIM_INFINITY; |
65 | |
66 | /* Is RLIMIT_NPROC currently enforced? */ |
67 | if (!uid_eq(current_uid(), GLOBAL_ROOT_UID) || |
68 | (current_user_ns() != &init_user_ns)) |
69 | limit = rlimit(RLIMIT_NPROC); |
70 | |
71 | return limit; |
72 | } |
73 | |
74 | /* |
75 | * Create a new user namespace, deriving the creator from the user in the |
76 | * passed credentials, and replacing that user with the new root user for the |
77 | * new namespace. |
78 | * |
79 | * This is called by copy_creds(), which will finish setting the target task's |
80 | * credentials. |
81 | */ |
82 | int create_user_ns(struct cred *new) |
83 | { |
84 | struct user_namespace *ns, *parent_ns = new->user_ns; |
85 | kuid_t owner = new->euid; |
86 | kgid_t group = new->egid; |
87 | struct ucounts *ucounts; |
88 | int ret, i; |
89 | |
90 | ret = -ENOSPC; |
91 | if (parent_ns->level > 32) |
92 | goto fail; |
93 | |
94 | ucounts = inc_user_namespaces(ns: parent_ns, uid: owner); |
95 | if (!ucounts) |
96 | goto fail; |
97 | |
98 | /* |
99 | * Verify that we can not violate the policy of which files |
100 | * may be accessed that is specified by the root directory, |
101 | * by verifying that the root directory is at the root of the |
102 | * mount namespace which allows all files to be accessed. |
103 | */ |
104 | ret = -EPERM; |
105 | if (current_chrooted()) |
106 | goto fail_dec; |
107 | |
108 | /* The creator needs a mapping in the parent user namespace |
109 | * or else we won't be able to reasonably tell userspace who |
110 | * created a user_namespace. |
111 | */ |
112 | ret = -EPERM; |
113 | if (!kuid_has_mapping(ns: parent_ns, uid: owner) || |
114 | !kgid_has_mapping(ns: parent_ns, gid: group)) |
115 | goto fail_dec; |
116 | |
117 | ret = security_create_user_ns(cred: new); |
118 | if (ret < 0) |
119 | goto fail_dec; |
120 | |
121 | ret = -ENOMEM; |
122 | ns = kmem_cache_zalloc(k: user_ns_cachep, GFP_KERNEL); |
123 | if (!ns) |
124 | goto fail_dec; |
125 | |
126 | ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP); |
127 | ret = ns_alloc_inum(ns: &ns->ns); |
128 | if (ret) |
129 | goto fail_free; |
130 | ns->ns.ops = &userns_operations; |
131 | |
132 | refcount_set(r: &ns->ns.count, n: 1); |
133 | /* Leave the new->user_ns reference with the new user namespace. */ |
134 | ns->parent = parent_ns; |
135 | ns->level = parent_ns->level + 1; |
136 | ns->owner = owner; |
137 | ns->group = group; |
138 | INIT_WORK(&ns->work, free_user_ns); |
139 | for (i = 0; i < UCOUNT_COUNTS; i++) { |
140 | ns->ucount_max[i] = INT_MAX; |
141 | } |
142 | set_userns_rlimit_max(ns, type: UCOUNT_RLIMIT_NPROC, max: enforced_nproc_rlimit()); |
143 | set_userns_rlimit_max(ns, type: UCOUNT_RLIMIT_MSGQUEUE, max: rlimit(RLIMIT_MSGQUEUE)); |
144 | set_userns_rlimit_max(ns, type: UCOUNT_RLIMIT_SIGPENDING, max: rlimit(RLIMIT_SIGPENDING)); |
145 | set_userns_rlimit_max(ns, type: UCOUNT_RLIMIT_MEMLOCK, max: rlimit(RLIMIT_MEMLOCK)); |
146 | ns->ucounts = ucounts; |
147 | |
148 | /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ |
149 | mutex_lock(&userns_state_mutex); |
150 | ns->flags = parent_ns->flags; |
151 | mutex_unlock(lock: &userns_state_mutex); |
152 | |
153 | #ifdef CONFIG_KEYS |
154 | INIT_LIST_HEAD(list: &ns->keyring_name_list); |
155 | init_rwsem(&ns->keyring_sem); |
156 | #endif |
157 | ret = -ENOMEM; |
158 | if (!setup_userns_sysctls(ns)) |
159 | goto fail_keyring; |
160 | |
161 | set_cred_user_ns(cred: new, user_ns: ns); |
162 | return 0; |
163 | fail_keyring: |
164 | #ifdef CONFIG_PERSISTENT_KEYRINGS |
165 | key_put(key: ns->persistent_keyring_register); |
166 | #endif |
167 | ns_free_inum(&ns->ns); |
168 | fail_free: |
169 | kmem_cache_free(s: user_ns_cachep, objp: ns); |
170 | fail_dec: |
171 | dec_user_namespaces(ucounts); |
172 | fail: |
173 | return ret; |
174 | } |
175 | |
176 | int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) |
177 | { |
178 | struct cred *cred; |
179 | int err = -ENOMEM; |
180 | |
181 | if (!(unshare_flags & CLONE_NEWUSER)) |
182 | return 0; |
183 | |
184 | cred = prepare_creds(); |
185 | if (cred) { |
186 | err = create_user_ns(new: cred); |
187 | if (err) |
188 | put_cred(cred); |
189 | else |
190 | *new_cred = cred; |
191 | } |
192 | |
193 | return err; |
194 | } |
195 | |
196 | static void free_user_ns(struct work_struct *work) |
197 | { |
198 | struct user_namespace *parent, *ns = |
199 | container_of(work, struct user_namespace, work); |
200 | |
201 | do { |
202 | struct ucounts *ucounts = ns->ucounts; |
203 | parent = ns->parent; |
204 | if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
205 | kfree(objp: ns->gid_map.forward); |
206 | kfree(objp: ns->gid_map.reverse); |
207 | } |
208 | if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
209 | kfree(objp: ns->uid_map.forward); |
210 | kfree(objp: ns->uid_map.reverse); |
211 | } |
212 | if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
213 | kfree(objp: ns->projid_map.forward); |
214 | kfree(objp: ns->projid_map.reverse); |
215 | } |
216 | #if IS_ENABLED(CONFIG_BINFMT_MISC) |
217 | kfree(objp: ns->binfmt_misc); |
218 | #endif |
219 | retire_userns_sysctls(ns); |
220 | key_free_user_ns(ns); |
221 | ns_free_inum(&ns->ns); |
222 | kmem_cache_free(s: user_ns_cachep, objp: ns); |
223 | dec_user_namespaces(ucounts); |
224 | ns = parent; |
225 | } while (refcount_dec_and_test(r: &parent->ns.count)); |
226 | } |
227 | |
228 | void __put_user_ns(struct user_namespace *ns) |
229 | { |
230 | schedule_work(work: &ns->work); |
231 | } |
232 | EXPORT_SYMBOL(__put_user_ns); |
233 | |
234 | /* |
235 | * struct idmap_key - holds the information necessary to find an idmapping in a |
236 | * sorted idmap array. It is passed to cmp_map_id() as first argument. |
237 | */ |
238 | struct idmap_key { |
239 | bool map_up; /* true -> id from kid; false -> kid from id */ |
240 | u32 id; /* id to find */ |
241 | u32 count; /* == 0 unless used with map_id_range_down() */ |
242 | }; |
243 | |
244 | /* |
245 | * cmp_map_id - Function to be passed to bsearch() to find the requested |
246 | * idmapping. Expects struct idmap_key to be passed via @k. |
247 | */ |
248 | static int cmp_map_id(const void *k, const void *e) |
249 | { |
250 | u32 first, last, id2; |
251 | const struct idmap_key *key = k; |
252 | const struct uid_gid_extent *el = e; |
253 | |
254 | id2 = key->id + key->count - 1; |
255 | |
256 | /* handle map_id_{down,up}() */ |
257 | if (key->map_up) |
258 | first = el->lower_first; |
259 | else |
260 | first = el->first; |
261 | |
262 | last = first + el->count - 1; |
263 | |
264 | if (key->id >= first && key->id <= last && |
265 | (id2 >= first && id2 <= last)) |
266 | return 0; |
267 | |
268 | if (key->id < first || id2 < first) |
269 | return -1; |
270 | |
271 | return 1; |
272 | } |
273 | |
274 | /* |
275 | * map_id_range_down_max - Find idmap via binary search in ordered idmap array. |
276 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. |
277 | */ |
278 | static struct uid_gid_extent * |
279 | map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) |
280 | { |
281 | struct idmap_key key; |
282 | |
283 | key.map_up = false; |
284 | key.count = count; |
285 | key.id = id; |
286 | |
287 | return bsearch(key: &key, base: map->forward, num: extents, |
288 | size: sizeof(struct uid_gid_extent), cmp: cmp_map_id); |
289 | } |
290 | |
291 | /* |
292 | * map_id_range_down_base - Find idmap via binary search in static extent array. |
293 | * Can only be called if number of mappings is equal or less than |
294 | * UID_GID_MAP_MAX_BASE_EXTENTS. |
295 | */ |
296 | static struct uid_gid_extent * |
297 | map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) |
298 | { |
299 | unsigned idx; |
300 | u32 first, last, id2; |
301 | |
302 | id2 = id + count - 1; |
303 | |
304 | /* Find the matching extent */ |
305 | for (idx = 0; idx < extents; idx++) { |
306 | first = map->extent[idx].first; |
307 | last = first + map->extent[idx].count - 1; |
308 | if (id >= first && id <= last && |
309 | (id2 >= first && id2 <= last)) |
310 | return &map->extent[idx]; |
311 | } |
312 | return NULL; |
313 | } |
314 | |
315 | static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count) |
316 | { |
317 | struct uid_gid_extent *extent; |
318 | unsigned extents = map->nr_extents; |
319 | smp_rmb(); |
320 | |
321 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
322 | extent = map_id_range_down_base(extents, map, id, count); |
323 | else |
324 | extent = map_id_range_down_max(extents, map, id, count); |
325 | |
326 | /* Map the id or note failure */ |
327 | if (extent) |
328 | id = (id - extent->first) + extent->lower_first; |
329 | else |
330 | id = (u32) -1; |
331 | |
332 | return id; |
333 | } |
334 | |
335 | u32 map_id_down(struct uid_gid_map *map, u32 id) |
336 | { |
337 | return map_id_range_down(map, id, count: 1); |
338 | } |
339 | |
340 | /* |
341 | * map_id_up_base - Find idmap via binary search in static extent array. |
342 | * Can only be called if number of mappings is equal or less than |
343 | * UID_GID_MAP_MAX_BASE_EXTENTS. |
344 | */ |
345 | static struct uid_gid_extent * |
346 | map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id) |
347 | { |
348 | unsigned idx; |
349 | u32 first, last; |
350 | |
351 | /* Find the matching extent */ |
352 | for (idx = 0; idx < extents; idx++) { |
353 | first = map->extent[idx].lower_first; |
354 | last = first + map->extent[idx].count - 1; |
355 | if (id >= first && id <= last) |
356 | return &map->extent[idx]; |
357 | } |
358 | return NULL; |
359 | } |
360 | |
361 | /* |
362 | * map_id_up_max - Find idmap via binary search in ordered idmap array. |
363 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. |
364 | */ |
365 | static struct uid_gid_extent * |
366 | map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id) |
367 | { |
368 | struct idmap_key key; |
369 | |
370 | key.map_up = true; |
371 | key.count = 1; |
372 | key.id = id; |
373 | |
374 | return bsearch(key: &key, base: map->reverse, num: extents, |
375 | size: sizeof(struct uid_gid_extent), cmp: cmp_map_id); |
376 | } |
377 | |
378 | u32 map_id_up(struct uid_gid_map *map, u32 id) |
379 | { |
380 | struct uid_gid_extent *extent; |
381 | unsigned extents = map->nr_extents; |
382 | smp_rmb(); |
383 | |
384 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
385 | extent = map_id_up_base(extents, map, id); |
386 | else |
387 | extent = map_id_up_max(extents, map, id); |
388 | |
389 | /* Map the id or note failure */ |
390 | if (extent) |
391 | id = (id - extent->lower_first) + extent->first; |
392 | else |
393 | id = (u32) -1; |
394 | |
395 | return id; |
396 | } |
397 | |
398 | /** |
399 | * make_kuid - Map a user-namespace uid pair into a kuid. |
400 | * @ns: User namespace that the uid is in |
401 | * @uid: User identifier |
402 | * |
403 | * Maps a user-namespace uid pair into a kernel internal kuid, |
404 | * and returns that kuid. |
405 | * |
406 | * When there is no mapping defined for the user-namespace uid |
407 | * pair INVALID_UID is returned. Callers are expected to test |
408 | * for and handle INVALID_UID being returned. INVALID_UID |
409 | * may be tested for using uid_valid(). |
410 | */ |
411 | kuid_t make_kuid(struct user_namespace *ns, uid_t uid) |
412 | { |
413 | /* Map the uid to a global kernel uid */ |
414 | return KUIDT_INIT(map_id_down(&ns->uid_map, uid)); |
415 | } |
416 | EXPORT_SYMBOL(make_kuid); |
417 | |
418 | /** |
419 | * from_kuid - 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 | * If @kuid has no mapping in @targ (uid_t)-1 is returned. |
429 | */ |
430 | uid_t from_kuid(struct user_namespace *targ, kuid_t kuid) |
431 | { |
432 | /* Map the uid from a global kernel uid */ |
433 | return map_id_up(map: &targ->uid_map, id: __kuid_val(uid: kuid)); |
434 | } |
435 | EXPORT_SYMBOL(from_kuid); |
436 | |
437 | /** |
438 | * from_kuid_munged - Create a uid from a kuid user-namespace pair. |
439 | * @targ: The user namespace we want a uid in. |
440 | * @kuid: The kernel internal uid to start with. |
441 | * |
442 | * Map @kuid into the user-namespace specified by @targ and |
443 | * return the resulting uid. |
444 | * |
445 | * There is always a mapping into the initial user_namespace. |
446 | * |
447 | * Unlike from_kuid from_kuid_munged never fails and always |
448 | * returns a valid uid. This makes from_kuid_munged appropriate |
449 | * for use in syscalls like stat and getuid where failing the |
450 | * system call and failing to provide a valid uid are not an |
451 | * options. |
452 | * |
453 | * If @kuid has no mapping in @targ overflowuid is returned. |
454 | */ |
455 | uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid) |
456 | { |
457 | uid_t uid; |
458 | uid = from_kuid(targ, kuid); |
459 | |
460 | if (uid == (uid_t) -1) |
461 | uid = overflowuid; |
462 | return uid; |
463 | } |
464 | EXPORT_SYMBOL(from_kuid_munged); |
465 | |
466 | /** |
467 | * make_kgid - Map a user-namespace gid pair into a kgid. |
468 | * @ns: User namespace that the gid is in |
469 | * @gid: group identifier |
470 | * |
471 | * Maps a user-namespace gid pair into a kernel internal kgid, |
472 | * and returns that kgid. |
473 | * |
474 | * When there is no mapping defined for the user-namespace gid |
475 | * pair INVALID_GID is returned. Callers are expected to test |
476 | * for and handle INVALID_GID being returned. INVALID_GID may be |
477 | * tested for using gid_valid(). |
478 | */ |
479 | kgid_t make_kgid(struct user_namespace *ns, gid_t gid) |
480 | { |
481 | /* Map the gid to a global kernel gid */ |
482 | return KGIDT_INIT(map_id_down(&ns->gid_map, gid)); |
483 | } |
484 | EXPORT_SYMBOL(make_kgid); |
485 | |
486 | /** |
487 | * from_kgid - 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 | * If @kgid has no mapping in @targ (gid_t)-1 is returned. |
497 | */ |
498 | gid_t from_kgid(struct user_namespace *targ, kgid_t kgid) |
499 | { |
500 | /* Map the gid from a global kernel gid */ |
501 | return map_id_up(map: &targ->gid_map, id: __kgid_val(gid: kgid)); |
502 | } |
503 | EXPORT_SYMBOL(from_kgid); |
504 | |
505 | /** |
506 | * from_kgid_munged - Create a gid from a kgid user-namespace pair. |
507 | * @targ: The user namespace we want a gid in. |
508 | * @kgid: The kernel internal gid to start with. |
509 | * |
510 | * Map @kgid into the user-namespace specified by @targ and |
511 | * return the resulting gid. |
512 | * |
513 | * There is always a mapping into the initial user_namespace. |
514 | * |
515 | * Unlike from_kgid from_kgid_munged never fails and always |
516 | * returns a valid gid. This makes from_kgid_munged appropriate |
517 | * for use in syscalls like stat and getgid where failing the |
518 | * system call and failing to provide a valid gid are not options. |
519 | * |
520 | * If @kgid has no mapping in @targ overflowgid is returned. |
521 | */ |
522 | gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid) |
523 | { |
524 | gid_t gid; |
525 | gid = from_kgid(targ, kgid); |
526 | |
527 | if (gid == (gid_t) -1) |
528 | gid = overflowgid; |
529 | return gid; |
530 | } |
531 | EXPORT_SYMBOL(from_kgid_munged); |
532 | |
533 | /** |
534 | * make_kprojid - Map a user-namespace projid pair into a kprojid. |
535 | * @ns: User namespace that the projid is in |
536 | * @projid: Project identifier |
537 | * |
538 | * Maps a user-namespace uid pair into a kernel internal kuid, |
539 | * and returns that kuid. |
540 | * |
541 | * When there is no mapping defined for the user-namespace projid |
542 | * pair INVALID_PROJID is returned. Callers are expected to test |
543 | * for and handle INVALID_PROJID being returned. INVALID_PROJID |
544 | * may be tested for using projid_valid(). |
545 | */ |
546 | kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid) |
547 | { |
548 | /* Map the uid to a global kernel uid */ |
549 | return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid)); |
550 | } |
551 | EXPORT_SYMBOL(make_kprojid); |
552 | |
553 | /** |
554 | * from_kprojid - Create a projid from a kprojid user-namespace pair. |
555 | * @targ: The user namespace we want a projid in. |
556 | * @kprojid: The kernel internal project identifier 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 | * If @kprojid has no mapping in @targ (projid_t)-1 is returned. |
564 | */ |
565 | projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid) |
566 | { |
567 | /* Map the uid from a global kernel uid */ |
568 | return map_id_up(map: &targ->projid_map, id: __kprojid_val(projid: kprojid)); |
569 | } |
570 | EXPORT_SYMBOL(from_kprojid); |
571 | |
572 | /** |
573 | * from_kprojid_munged - Create a projiid from a kprojid user-namespace pair. |
574 | * @targ: The user namespace we want a projid in. |
575 | * @kprojid: The kernel internal projid to start with. |
576 | * |
577 | * Map @kprojid into the user-namespace specified by @targ and |
578 | * return the resulting projid. |
579 | * |
580 | * There is always a mapping into the initial user_namespace. |
581 | * |
582 | * Unlike from_kprojid from_kprojid_munged never fails and always |
583 | * returns a valid projid. This makes from_kprojid_munged |
584 | * appropriate for use in syscalls like stat and where |
585 | * failing the system call and failing to provide a valid projid are |
586 | * not an options. |
587 | * |
588 | * If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned. |
589 | */ |
590 | projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid) |
591 | { |
592 | projid_t projid; |
593 | projid = from_kprojid(targ, kprojid); |
594 | |
595 | if (projid == (projid_t) -1) |
596 | projid = OVERFLOW_PROJID; |
597 | return projid; |
598 | } |
599 | EXPORT_SYMBOL(from_kprojid_munged); |
600 | |
601 | |
602 | static int uid_m_show(struct seq_file *seq, void *v) |
603 | { |
604 | struct user_namespace *ns = seq->private; |
605 | struct uid_gid_extent *extent = v; |
606 | struct user_namespace *lower_ns; |
607 | uid_t lower; |
608 | |
609 | lower_ns = seq_user_ns(seq); |
610 | if ((lower_ns == ns) && lower_ns->parent) |
611 | lower_ns = lower_ns->parent; |
612 | |
613 | lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first)); |
614 | |
615 | seq_printf(m: seq, fmt: "%10u %10u %10u\n" , |
616 | extent->first, |
617 | lower, |
618 | extent->count); |
619 | |
620 | return 0; |
621 | } |
622 | |
623 | static int gid_m_show(struct seq_file *seq, void *v) |
624 | { |
625 | struct user_namespace *ns = seq->private; |
626 | struct uid_gid_extent *extent = v; |
627 | struct user_namespace *lower_ns; |
628 | gid_t lower; |
629 | |
630 | lower_ns = seq_user_ns(seq); |
631 | if ((lower_ns == ns) && lower_ns->parent) |
632 | lower_ns = lower_ns->parent; |
633 | |
634 | lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); |
635 | |
636 | seq_printf(m: seq, fmt: "%10u %10u %10u\n" , |
637 | extent->first, |
638 | lower, |
639 | extent->count); |
640 | |
641 | return 0; |
642 | } |
643 | |
644 | static int projid_m_show(struct seq_file *seq, void *v) |
645 | { |
646 | struct user_namespace *ns = seq->private; |
647 | struct uid_gid_extent *extent = v; |
648 | struct user_namespace *lower_ns; |
649 | projid_t lower; |
650 | |
651 | lower_ns = seq_user_ns(seq); |
652 | if ((lower_ns == ns) && lower_ns->parent) |
653 | lower_ns = lower_ns->parent; |
654 | |
655 | lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first)); |
656 | |
657 | seq_printf(m: seq, fmt: "%10u %10u %10u\n" , |
658 | extent->first, |
659 | lower, |
660 | extent->count); |
661 | |
662 | return 0; |
663 | } |
664 | |
665 | static void *m_start(struct seq_file *seq, loff_t *ppos, |
666 | struct uid_gid_map *map) |
667 | { |
668 | loff_t pos = *ppos; |
669 | unsigned extents = map->nr_extents; |
670 | smp_rmb(); |
671 | |
672 | if (pos >= extents) |
673 | return NULL; |
674 | |
675 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
676 | return &map->extent[pos]; |
677 | |
678 | return &map->forward[pos]; |
679 | } |
680 | |
681 | static void *uid_m_start(struct seq_file *seq, loff_t *ppos) |
682 | { |
683 | struct user_namespace *ns = seq->private; |
684 | |
685 | return m_start(seq, ppos, map: &ns->uid_map); |
686 | } |
687 | |
688 | static void *gid_m_start(struct seq_file *seq, loff_t *ppos) |
689 | { |
690 | struct user_namespace *ns = seq->private; |
691 | |
692 | return m_start(seq, ppos, map: &ns->gid_map); |
693 | } |
694 | |
695 | static void *projid_m_start(struct seq_file *seq, loff_t *ppos) |
696 | { |
697 | struct user_namespace *ns = seq->private; |
698 | |
699 | return m_start(seq, ppos, map: &ns->projid_map); |
700 | } |
701 | |
702 | static void *m_next(struct seq_file *seq, void *v, loff_t *pos) |
703 | { |
704 | (*pos)++; |
705 | return seq->op->start(seq, pos); |
706 | } |
707 | |
708 | static void m_stop(struct seq_file *seq, void *v) |
709 | { |
710 | return; |
711 | } |
712 | |
713 | const struct seq_operations proc_uid_seq_operations = { |
714 | .start = uid_m_start, |
715 | .stop = m_stop, |
716 | .next = m_next, |
717 | .show = uid_m_show, |
718 | }; |
719 | |
720 | const struct seq_operations proc_gid_seq_operations = { |
721 | .start = gid_m_start, |
722 | .stop = m_stop, |
723 | .next = m_next, |
724 | .show = gid_m_show, |
725 | }; |
726 | |
727 | const struct seq_operations proc_projid_seq_operations = { |
728 | .start = projid_m_start, |
729 | .stop = m_stop, |
730 | .next = m_next, |
731 | .show = projid_m_show, |
732 | }; |
733 | |
734 | static bool mappings_overlap(struct uid_gid_map *new_map, |
735 | struct uid_gid_extent *extent) |
736 | { |
737 | u32 upper_first, lower_first, upper_last, lower_last; |
738 | unsigned idx; |
739 | |
740 | upper_first = extent->first; |
741 | lower_first = extent->lower_first; |
742 | upper_last = upper_first + extent->count - 1; |
743 | lower_last = lower_first + extent->count - 1; |
744 | |
745 | for (idx = 0; idx < new_map->nr_extents; idx++) { |
746 | u32 prev_upper_first, prev_lower_first; |
747 | u32 prev_upper_last, prev_lower_last; |
748 | struct uid_gid_extent *prev; |
749 | |
750 | if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
751 | prev = &new_map->extent[idx]; |
752 | else |
753 | prev = &new_map->forward[idx]; |
754 | |
755 | prev_upper_first = prev->first; |
756 | prev_lower_first = prev->lower_first; |
757 | prev_upper_last = prev_upper_first + prev->count - 1; |
758 | prev_lower_last = prev_lower_first + prev->count - 1; |
759 | |
760 | /* Does the upper range intersect a previous extent? */ |
761 | if ((prev_upper_first <= upper_last) && |
762 | (prev_upper_last >= upper_first)) |
763 | return true; |
764 | |
765 | /* Does the lower range intersect a previous extent? */ |
766 | if ((prev_lower_first <= lower_last) && |
767 | (prev_lower_last >= lower_first)) |
768 | return true; |
769 | } |
770 | return false; |
771 | } |
772 | |
773 | /* |
774 | * insert_extent - Safely insert a new idmap extent into struct uid_gid_map. |
775 | * Takes care to allocate a 4K block of memory if the number of mappings exceeds |
776 | * UID_GID_MAP_MAX_BASE_EXTENTS. |
777 | */ |
778 | static int insert_extent(struct uid_gid_map *map, struct uid_gid_extent *extent) |
779 | { |
780 | struct uid_gid_extent *dest; |
781 | |
782 | if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) { |
783 | struct uid_gid_extent *forward; |
784 | |
785 | /* Allocate memory for 340 mappings. */ |
786 | forward = kmalloc_array(UID_GID_MAP_MAX_EXTENTS, |
787 | size: sizeof(struct uid_gid_extent), |
788 | GFP_KERNEL); |
789 | if (!forward) |
790 | return -ENOMEM; |
791 | |
792 | /* Copy over memory. Only set up memory for the forward pointer. |
793 | * Defer the memory setup for the reverse pointer. |
794 | */ |
795 | memcpy(forward, map->extent, |
796 | map->nr_extents * sizeof(map->extent[0])); |
797 | |
798 | map->forward = forward; |
799 | map->reverse = NULL; |
800 | } |
801 | |
802 | if (map->nr_extents < UID_GID_MAP_MAX_BASE_EXTENTS) |
803 | dest = &map->extent[map->nr_extents]; |
804 | else |
805 | dest = &map->forward[map->nr_extents]; |
806 | |
807 | *dest = *extent; |
808 | map->nr_extents++; |
809 | return 0; |
810 | } |
811 | |
812 | /* cmp function to sort() forward mappings */ |
813 | static int cmp_extents_forward(const void *a, const void *b) |
814 | { |
815 | const struct uid_gid_extent *e1 = a; |
816 | const struct uid_gid_extent *e2 = b; |
817 | |
818 | if (e1->first < e2->first) |
819 | return -1; |
820 | |
821 | if (e1->first > e2->first) |
822 | return 1; |
823 | |
824 | return 0; |
825 | } |
826 | |
827 | /* cmp function to sort() reverse mappings */ |
828 | static int cmp_extents_reverse(const void *a, const void *b) |
829 | { |
830 | const struct uid_gid_extent *e1 = a; |
831 | const struct uid_gid_extent *e2 = b; |
832 | |
833 | if (e1->lower_first < e2->lower_first) |
834 | return -1; |
835 | |
836 | if (e1->lower_first > e2->lower_first) |
837 | return 1; |
838 | |
839 | return 0; |
840 | } |
841 | |
842 | /* |
843 | * sort_idmaps - Sorts an array of idmap entries. |
844 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. |
845 | */ |
846 | static int sort_idmaps(struct uid_gid_map *map) |
847 | { |
848 | if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
849 | return 0; |
850 | |
851 | /* Sort forward array. */ |
852 | sort(base: map->forward, num: map->nr_extents, size: sizeof(struct uid_gid_extent), |
853 | cmp_func: cmp_extents_forward, NULL); |
854 | |
855 | /* Only copy the memory from forward we actually need. */ |
856 | map->reverse = kmemdup(p: map->forward, |
857 | size: map->nr_extents * sizeof(struct uid_gid_extent), |
858 | GFP_KERNEL); |
859 | if (!map->reverse) |
860 | return -ENOMEM; |
861 | |
862 | /* Sort reverse array. */ |
863 | sort(base: map->reverse, num: map->nr_extents, size: sizeof(struct uid_gid_extent), |
864 | cmp_func: cmp_extents_reverse, NULL); |
865 | |
866 | return 0; |
867 | } |
868 | |
869 | /** |
870 | * verify_root_map() - check the uid 0 mapping |
871 | * @file: idmapping file |
872 | * @map_ns: user namespace of the target process |
873 | * @new_map: requested idmap |
874 | * |
875 | * If a process requests mapping parent uid 0 into the new ns, verify that the |
876 | * process writing the map had the CAP_SETFCAP capability as the target process |
877 | * will be able to write fscaps that are valid in ancestor user namespaces. |
878 | * |
879 | * Return: true if the mapping is allowed, false if not. |
880 | */ |
881 | static bool verify_root_map(const struct file *file, |
882 | struct user_namespace *map_ns, |
883 | struct uid_gid_map *new_map) |
884 | { |
885 | int idx; |
886 | const struct user_namespace *file_ns = file->f_cred->user_ns; |
887 | struct uid_gid_extent *extent0 = NULL; |
888 | |
889 | for (idx = 0; idx < new_map->nr_extents; idx++) { |
890 | if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
891 | extent0 = &new_map->extent[idx]; |
892 | else |
893 | extent0 = &new_map->forward[idx]; |
894 | if (extent0->lower_first == 0) |
895 | break; |
896 | |
897 | extent0 = NULL; |
898 | } |
899 | |
900 | if (!extent0) |
901 | return true; |
902 | |
903 | if (map_ns == file_ns) { |
904 | /* The process unshared its ns and is writing to its own |
905 | * /proc/self/uid_map. User already has full capabilites in |
906 | * the new namespace. Verify that the parent had CAP_SETFCAP |
907 | * when it unshared. |
908 | * */ |
909 | if (!file_ns->parent_could_setfcap) |
910 | return false; |
911 | } else { |
912 | /* Process p1 is writing to uid_map of p2, who is in a child |
913 | * user namespace to p1's. Verify that the opener of the map |
914 | * file has CAP_SETFCAP against the parent of the new map |
915 | * namespace */ |
916 | if (!file_ns_capable(file, ns: map_ns->parent, CAP_SETFCAP)) |
917 | return false; |
918 | } |
919 | |
920 | return true; |
921 | } |
922 | |
923 | static ssize_t map_write(struct file *file, const char __user *buf, |
924 | size_t count, loff_t *ppos, |
925 | int cap_setid, |
926 | struct uid_gid_map *map, |
927 | struct uid_gid_map *parent_map) |
928 | { |
929 | struct seq_file *seq = file->private_data; |
930 | struct user_namespace *map_ns = seq->private; |
931 | struct uid_gid_map new_map; |
932 | unsigned idx; |
933 | struct uid_gid_extent extent; |
934 | char *kbuf, *pos, *next_line; |
935 | ssize_t ret; |
936 | |
937 | /* Only allow < page size writes at the beginning of the file */ |
938 | if ((*ppos != 0) || (count >= PAGE_SIZE)) |
939 | return -EINVAL; |
940 | |
941 | /* Slurp in the user data */ |
942 | kbuf = memdup_user_nul(buf, count); |
943 | if (IS_ERR(ptr: kbuf)) |
944 | return PTR_ERR(ptr: kbuf); |
945 | |
946 | /* |
947 | * The userns_state_mutex serializes all writes to any given map. |
948 | * |
949 | * Any map is only ever written once. |
950 | * |
951 | * An id map fits within 1 cache line on most architectures. |
952 | * |
953 | * On read nothing needs to be done unless you are on an |
954 | * architecture with a crazy cache coherency model like alpha. |
955 | * |
956 | * There is a one time data dependency between reading the |
957 | * count of the extents and the values of the extents. The |
958 | * desired behavior is to see the values of the extents that |
959 | * were written before the count of the extents. |
960 | * |
961 | * To achieve this smp_wmb() is used on guarantee the write |
962 | * order and smp_rmb() is guaranteed that we don't have crazy |
963 | * architectures returning stale data. |
964 | */ |
965 | mutex_lock(&userns_state_mutex); |
966 | |
967 | memset(&new_map, 0, sizeof(struct uid_gid_map)); |
968 | |
969 | ret = -EPERM; |
970 | /* Only allow one successful write to the map */ |
971 | if (map->nr_extents != 0) |
972 | goto out; |
973 | |
974 | /* |
975 | * Adjusting namespace settings requires capabilities on the target. |
976 | */ |
977 | if (cap_valid(cap_setid) && !file_ns_capable(file, ns: map_ns, CAP_SYS_ADMIN)) |
978 | goto out; |
979 | |
980 | /* Parse the user data */ |
981 | ret = -EINVAL; |
982 | pos = kbuf; |
983 | for (; pos; pos = next_line) { |
984 | |
985 | /* Find the end of line and ensure I don't look past it */ |
986 | next_line = strchr(pos, '\n'); |
987 | if (next_line) { |
988 | *next_line = '\0'; |
989 | next_line++; |
990 | if (*next_line == '\0') |
991 | next_line = NULL; |
992 | } |
993 | |
994 | pos = skip_spaces(pos); |
995 | extent.first = simple_strtoul(pos, &pos, 10); |
996 | if (!isspace(*pos)) |
997 | goto out; |
998 | |
999 | pos = skip_spaces(pos); |
1000 | extent.lower_first = simple_strtoul(pos, &pos, 10); |
1001 | if (!isspace(*pos)) |
1002 | goto out; |
1003 | |
1004 | pos = skip_spaces(pos); |
1005 | extent.count = simple_strtoul(pos, &pos, 10); |
1006 | if (*pos && !isspace(*pos)) |
1007 | goto out; |
1008 | |
1009 | /* Verify there is not trailing junk on the line */ |
1010 | pos = skip_spaces(pos); |
1011 | if (*pos != '\0') |
1012 | goto out; |
1013 | |
1014 | /* Verify we have been given valid starting values */ |
1015 | if ((extent.first == (u32) -1) || |
1016 | (extent.lower_first == (u32) -1)) |
1017 | goto out; |
1018 | |
1019 | /* Verify count is not zero and does not cause the |
1020 | * extent to wrap |
1021 | */ |
1022 | if ((extent.first + extent.count) <= extent.first) |
1023 | goto out; |
1024 | if ((extent.lower_first + extent.count) <= |
1025 | extent.lower_first) |
1026 | goto out; |
1027 | |
1028 | /* Do the ranges in extent overlap any previous extents? */ |
1029 | if (mappings_overlap(new_map: &new_map, extent: &extent)) |
1030 | goto out; |
1031 | |
1032 | if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS && |
1033 | (next_line != NULL)) |
1034 | goto out; |
1035 | |
1036 | ret = insert_extent(map: &new_map, extent: &extent); |
1037 | if (ret < 0) |
1038 | goto out; |
1039 | ret = -EINVAL; |
1040 | } |
1041 | /* Be very certain the new map actually exists */ |
1042 | if (new_map.nr_extents == 0) |
1043 | goto out; |
1044 | |
1045 | ret = -EPERM; |
1046 | /* Validate the user is allowed to use user id's mapped to. */ |
1047 | if (!new_idmap_permitted(file, ns: map_ns, cap_setid, map: &new_map)) |
1048 | goto out; |
1049 | |
1050 | ret = -EPERM; |
1051 | /* Map the lower ids from the parent user namespace to the |
1052 | * kernel global id space. |
1053 | */ |
1054 | for (idx = 0; idx < new_map.nr_extents; idx++) { |
1055 | struct uid_gid_extent *e; |
1056 | u32 lower_first; |
1057 | |
1058 | if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
1059 | e = &new_map.extent[idx]; |
1060 | else |
1061 | e = &new_map.forward[idx]; |
1062 | |
1063 | lower_first = map_id_range_down(map: parent_map, |
1064 | id: e->lower_first, |
1065 | count: e->count); |
1066 | |
1067 | /* Fail if we can not map the specified extent to |
1068 | * the kernel global id space. |
1069 | */ |
1070 | if (lower_first == (u32) -1) |
1071 | goto out; |
1072 | |
1073 | e->lower_first = lower_first; |
1074 | } |
1075 | |
1076 | /* |
1077 | * If we want to use binary search for lookup, this clones the extent |
1078 | * array and sorts both copies. |
1079 | */ |
1080 | ret = sort_idmaps(map: &new_map); |
1081 | if (ret < 0) |
1082 | goto out; |
1083 | |
1084 | /* Install the map */ |
1085 | if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { |
1086 | memcpy(map->extent, new_map.extent, |
1087 | new_map.nr_extents * sizeof(new_map.extent[0])); |
1088 | } else { |
1089 | map->forward = new_map.forward; |
1090 | map->reverse = new_map.reverse; |
1091 | } |
1092 | smp_wmb(); |
1093 | map->nr_extents = new_map.nr_extents; |
1094 | |
1095 | *ppos = count; |
1096 | ret = count; |
1097 | out: |
1098 | if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
1099 | kfree(objp: new_map.forward); |
1100 | kfree(objp: new_map.reverse); |
1101 | map->forward = NULL; |
1102 | map->reverse = NULL; |
1103 | map->nr_extents = 0; |
1104 | } |
1105 | |
1106 | mutex_unlock(lock: &userns_state_mutex); |
1107 | kfree(objp: kbuf); |
1108 | return ret; |
1109 | } |
1110 | |
1111 | ssize_t proc_uid_map_write(struct file *file, const char __user *buf, |
1112 | size_t size, loff_t *ppos) |
1113 | { |
1114 | struct seq_file *seq = file->private_data; |
1115 | struct user_namespace *ns = seq->private; |
1116 | struct user_namespace *seq_ns = seq_user_ns(seq); |
1117 | |
1118 | if (!ns->parent) |
1119 | return -EPERM; |
1120 | |
1121 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1122 | return -EPERM; |
1123 | |
1124 | return map_write(file, buf, count: size, ppos, CAP_SETUID, |
1125 | map: &ns->uid_map, parent_map: &ns->parent->uid_map); |
1126 | } |
1127 | |
1128 | ssize_t proc_gid_map_write(struct file *file, const char __user *buf, |
1129 | size_t size, loff_t *ppos) |
1130 | { |
1131 | struct seq_file *seq = file->private_data; |
1132 | struct user_namespace *ns = seq->private; |
1133 | struct user_namespace *seq_ns = seq_user_ns(seq); |
1134 | |
1135 | if (!ns->parent) |
1136 | return -EPERM; |
1137 | |
1138 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1139 | return -EPERM; |
1140 | |
1141 | return map_write(file, buf, count: size, ppos, CAP_SETGID, |
1142 | map: &ns->gid_map, parent_map: &ns->parent->gid_map); |
1143 | } |
1144 | |
1145 | ssize_t proc_projid_map_write(struct file *file, const char __user *buf, |
1146 | size_t size, loff_t *ppos) |
1147 | { |
1148 | struct seq_file *seq = file->private_data; |
1149 | struct user_namespace *ns = seq->private; |
1150 | struct user_namespace *seq_ns = seq_user_ns(seq); |
1151 | |
1152 | if (!ns->parent) |
1153 | return -EPERM; |
1154 | |
1155 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1156 | return -EPERM; |
1157 | |
1158 | /* Anyone can set any valid project id no capability needed */ |
1159 | return map_write(file, buf, count: size, ppos, cap_setid: -1, |
1160 | map: &ns->projid_map, parent_map: &ns->parent->projid_map); |
1161 | } |
1162 | |
1163 | static bool new_idmap_permitted(const struct file *file, |
1164 | struct user_namespace *ns, int cap_setid, |
1165 | struct uid_gid_map *new_map) |
1166 | { |
1167 | const struct cred *cred = file->f_cred; |
1168 | |
1169 | if (cap_setid == CAP_SETUID && !verify_root_map(file, map_ns: ns, new_map)) |
1170 | return false; |
1171 | |
1172 | /* Don't allow mappings that would allow anything that wouldn't |
1173 | * be allowed without the establishment of unprivileged mappings. |
1174 | */ |
1175 | if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) && |
1176 | uid_eq(left: ns->owner, right: cred->euid)) { |
1177 | u32 id = new_map->extent[0].lower_first; |
1178 | if (cap_setid == CAP_SETUID) { |
1179 | kuid_t uid = make_kuid(ns->parent, id); |
1180 | if (uid_eq(left: uid, right: cred->euid)) |
1181 | return true; |
1182 | } else if (cap_setid == CAP_SETGID) { |
1183 | kgid_t gid = make_kgid(ns->parent, id); |
1184 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && |
1185 | gid_eq(left: gid, right: cred->egid)) |
1186 | return true; |
1187 | } |
1188 | } |
1189 | |
1190 | /* Allow anyone to set a mapping that doesn't require privilege */ |
1191 | if (!cap_valid(cap_setid)) |
1192 | return true; |
1193 | |
1194 | /* Allow the specified ids if we have the appropriate capability |
1195 | * (CAP_SETUID or CAP_SETGID) over the parent user namespace. |
1196 | * And the opener of the id file also has the appropriate capability. |
1197 | */ |
1198 | if (ns_capable(ns: ns->parent, cap: cap_setid) && |
1199 | file_ns_capable(file, ns: ns->parent, cap: cap_setid)) |
1200 | return true; |
1201 | |
1202 | return false; |
1203 | } |
1204 | |
1205 | int proc_setgroups_show(struct seq_file *seq, void *v) |
1206 | { |
1207 | struct user_namespace *ns = seq->private; |
1208 | unsigned long userns_flags = READ_ONCE(ns->flags); |
1209 | |
1210 | seq_printf(m: seq, fmt: "%s\n" , |
1211 | (userns_flags & USERNS_SETGROUPS_ALLOWED) ? |
1212 | "allow" : "deny" ); |
1213 | return 0; |
1214 | } |
1215 | |
1216 | ssize_t proc_setgroups_write(struct file *file, const char __user *buf, |
1217 | size_t count, loff_t *ppos) |
1218 | { |
1219 | struct seq_file *seq = file->private_data; |
1220 | struct user_namespace *ns = seq->private; |
1221 | char kbuf[8], *pos; |
1222 | bool setgroups_allowed; |
1223 | ssize_t ret; |
1224 | |
1225 | /* Only allow a very narrow range of strings to be written */ |
1226 | ret = -EINVAL; |
1227 | if ((*ppos != 0) || (count >= sizeof(kbuf))) |
1228 | goto out; |
1229 | |
1230 | /* What was written? */ |
1231 | ret = -EFAULT; |
1232 | if (copy_from_user(to: kbuf, from: buf, n: count)) |
1233 | goto out; |
1234 | kbuf[count] = '\0'; |
1235 | pos = kbuf; |
1236 | |
1237 | /* What is being requested? */ |
1238 | ret = -EINVAL; |
1239 | if (strncmp(pos, "allow" , 5) == 0) { |
1240 | pos += 5; |
1241 | setgroups_allowed = true; |
1242 | } |
1243 | else if (strncmp(pos, "deny" , 4) == 0) { |
1244 | pos += 4; |
1245 | setgroups_allowed = false; |
1246 | } |
1247 | else |
1248 | goto out; |
1249 | |
1250 | /* Verify there is not trailing junk on the line */ |
1251 | pos = skip_spaces(pos); |
1252 | if (*pos != '\0') |
1253 | goto out; |
1254 | |
1255 | ret = -EPERM; |
1256 | mutex_lock(&userns_state_mutex); |
1257 | if (setgroups_allowed) { |
1258 | /* Enabling setgroups after setgroups has been disabled |
1259 | * is not allowed. |
1260 | */ |
1261 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED)) |
1262 | goto out_unlock; |
1263 | } else { |
1264 | /* Permanently disabling setgroups after setgroups has |
1265 | * been enabled by writing the gid_map is not allowed. |
1266 | */ |
1267 | if (ns->gid_map.nr_extents != 0) |
1268 | goto out_unlock; |
1269 | ns->flags &= ~USERNS_SETGROUPS_ALLOWED; |
1270 | } |
1271 | mutex_unlock(lock: &userns_state_mutex); |
1272 | |
1273 | /* Report a successful write */ |
1274 | *ppos = count; |
1275 | ret = count; |
1276 | out: |
1277 | return ret; |
1278 | out_unlock: |
1279 | mutex_unlock(lock: &userns_state_mutex); |
1280 | goto out; |
1281 | } |
1282 | |
1283 | bool userns_may_setgroups(const struct user_namespace *ns) |
1284 | { |
1285 | bool allowed; |
1286 | |
1287 | mutex_lock(&userns_state_mutex); |
1288 | /* It is not safe to use setgroups until a gid mapping in |
1289 | * the user namespace has been established. |
1290 | */ |
1291 | allowed = ns->gid_map.nr_extents != 0; |
1292 | /* Is setgroups allowed? */ |
1293 | allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED); |
1294 | mutex_unlock(lock: &userns_state_mutex); |
1295 | |
1296 | return allowed; |
1297 | } |
1298 | |
1299 | /* |
1300 | * Returns true if @child is the same namespace or a descendant of |
1301 | * @ancestor. |
1302 | */ |
1303 | bool in_userns(const struct user_namespace *ancestor, |
1304 | const struct user_namespace *child) |
1305 | { |
1306 | const struct user_namespace *ns; |
1307 | for (ns = child; ns->level > ancestor->level; ns = ns->parent) |
1308 | ; |
1309 | return (ns == ancestor); |
1310 | } |
1311 | |
1312 | bool current_in_userns(const struct user_namespace *target_ns) |
1313 | { |
1314 | return in_userns(ancestor: target_ns, current_user_ns()); |
1315 | } |
1316 | EXPORT_SYMBOL(current_in_userns); |
1317 | |
1318 | static inline struct user_namespace *to_user_ns(struct ns_common *ns) |
1319 | { |
1320 | return container_of(ns, struct user_namespace, ns); |
1321 | } |
1322 | |
1323 | static struct ns_common *userns_get(struct task_struct *task) |
1324 | { |
1325 | struct user_namespace *user_ns; |
1326 | |
1327 | rcu_read_lock(); |
1328 | user_ns = get_user_ns(__task_cred(task)->user_ns); |
1329 | rcu_read_unlock(); |
1330 | |
1331 | return user_ns ? &user_ns->ns : NULL; |
1332 | } |
1333 | |
1334 | static void userns_put(struct ns_common *ns) |
1335 | { |
1336 | put_user_ns(ns: to_user_ns(ns)); |
1337 | } |
1338 | |
1339 | static int userns_install(struct nsset *nsset, struct ns_common *ns) |
1340 | { |
1341 | struct user_namespace *user_ns = to_user_ns(ns); |
1342 | struct cred *cred; |
1343 | |
1344 | /* Don't allow gaining capabilities by reentering |
1345 | * the same user namespace. |
1346 | */ |
1347 | if (user_ns == current_user_ns()) |
1348 | return -EINVAL; |
1349 | |
1350 | /* Tasks that share a thread group must share a user namespace */ |
1351 | if (!thread_group_empty(current)) |
1352 | return -EINVAL; |
1353 | |
1354 | if (current->fs->users != 1) |
1355 | return -EINVAL; |
1356 | |
1357 | if (!ns_capable(ns: user_ns, CAP_SYS_ADMIN)) |
1358 | return -EPERM; |
1359 | |
1360 | cred = nsset_cred(set: nsset); |
1361 | if (!cred) |
1362 | return -EINVAL; |
1363 | |
1364 | put_user_ns(ns: cred->user_ns); |
1365 | set_cred_user_ns(cred, user_ns: get_user_ns(ns: user_ns)); |
1366 | |
1367 | if (set_cred_ucounts(cred) < 0) |
1368 | return -EINVAL; |
1369 | |
1370 | return 0; |
1371 | } |
1372 | |
1373 | struct ns_common *ns_get_owner(struct ns_common *ns) |
1374 | { |
1375 | struct user_namespace *my_user_ns = current_user_ns(); |
1376 | struct user_namespace *owner, *p; |
1377 | |
1378 | /* See if the owner is in the current user namespace */ |
1379 | owner = p = ns->ops->owner(ns); |
1380 | for (;;) { |
1381 | if (!p) |
1382 | return ERR_PTR(error: -EPERM); |
1383 | if (p == my_user_ns) |
1384 | break; |
1385 | p = p->parent; |
1386 | } |
1387 | |
1388 | return &get_user_ns(ns: owner)->ns; |
1389 | } |
1390 | |
1391 | static struct user_namespace *userns_owner(struct ns_common *ns) |
1392 | { |
1393 | return to_user_ns(ns)->parent; |
1394 | } |
1395 | |
1396 | const struct proc_ns_operations userns_operations = { |
1397 | .name = "user" , |
1398 | .type = CLONE_NEWUSER, |
1399 | .get = userns_get, |
1400 | .put = userns_put, |
1401 | .install = userns_install, |
1402 | .owner = userns_owner, |
1403 | .get_parent = ns_get_owner, |
1404 | }; |
1405 | |
1406 | static __init int user_namespaces_init(void) |
1407 | { |
1408 | user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC | SLAB_ACCOUNT); |
1409 | return 0; |
1410 | } |
1411 | subsys_initcall(user_namespaces_init); |
1412 | |