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b886d83c | 1 | // SPDX-License-Identifier: GPL-2.0-only |
acce292c | 2 | |
9984de1a | 3 | #include <linux/export.h> |
acce292c | 4 | #include <linux/nsproxy.h> |
1aeb272c | 5 | #include <linux/slab.h> |
3f07c014 | 6 | #include <linux/sched/signal.h> |
acce292c | 7 | #include <linux/user_namespace.h> |
0bb80f24 | 8 | #include <linux/proc_ns.h> |
5c1469de | 9 | #include <linux/highuid.h> |
18b6e041 | 10 | #include <linux/cred.h> |
973c5914 | 11 | #include <linux/securebits.h> |
22d917d8 EB |
12 | #include <linux/keyctl.h> |
13 | #include <linux/key-type.h> | |
14 | #include <keys/user-type.h> | |
15 | #include <linux/seq_file.h> | |
16 | #include <linux/fs.h> | |
17 | #include <linux/uaccess.h> | |
18 | #include <linux/ctype.h> | |
f76d207a | 19 | #include <linux/projid.h> |
e66eded8 | 20 | #include <linux/fs_struct.h> |
6397fac4 CB |
21 | #include <linux/bsearch.h> |
22 | #include <linux/sort.h> | |
acce292c | 23 | |
6164281a | 24 | static struct kmem_cache *user_ns_cachep __read_mostly; |
f0d62aec | 25 | static DEFINE_MUTEX(userns_state_mutex); |
6164281a | 26 | |
6708075f EB |
27 | static bool new_idmap_permitted(const struct file *file, |
28 | struct user_namespace *ns, int cap_setid, | |
22d917d8 | 29 | struct uid_gid_map *map); |
b032132c | 30 | static void free_user_ns(struct work_struct *work); |
22d917d8 | 31 | |
25f9c081 EB |
32 | static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid) |
33 | { | |
34 | return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES); | |
35 | } | |
36 | ||
37 | static void dec_user_namespaces(struct ucounts *ucounts) | |
38 | { | |
39 | return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES); | |
40 | } | |
41 | ||
cde1975b EB |
42 | static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns) |
43 | { | |
44 | /* Start with the same capabilities as init but useless for doing | |
45 | * anything as the capabilities are bound to the new user namespace. | |
46 | */ | |
47 | cred->securebits = SECUREBITS_DEFAULT; | |
48 | cred->cap_inheritable = CAP_EMPTY_SET; | |
49 | cred->cap_permitted = CAP_FULL_SET; | |
50 | cred->cap_effective = CAP_FULL_SET; | |
58319057 | 51 | cred->cap_ambient = CAP_EMPTY_SET; |
cde1975b EB |
52 | cred->cap_bset = CAP_FULL_SET; |
53 | #ifdef CONFIG_KEYS | |
54 | key_put(cred->request_key_auth); | |
55 | cred->request_key_auth = NULL; | |
56 | #endif | |
57 | /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ | |
58 | cred->user_ns = user_ns; | |
59 | } | |
60 | ||
0ac983f5 EB |
61 | static unsigned long enforced_nproc_rlimit(void) |
62 | { | |
63 | unsigned long limit = RLIM_INFINITY; | |
64 | ||
65 | /* Is RLIMIT_NPROC currently enforced? */ | |
66 | if (!uid_eq(current_uid(), GLOBAL_ROOT_UID) || | |
67 | (current_user_ns() != &init_user_ns)) | |
68 | limit = rlimit(RLIMIT_NPROC); | |
69 | ||
70 | return limit; | |
71 | } | |
72 | ||
77ec739d | 73 | /* |
18b6e041 SH |
74 | * Create a new user namespace, deriving the creator from the user in the |
75 | * passed credentials, and replacing that user with the new root user for the | |
76 | * new namespace. | |
77 | * | |
78 | * This is called by copy_creds(), which will finish setting the target task's | |
79 | * credentials. | |
77ec739d | 80 | */ |
18b6e041 | 81 | int create_user_ns(struct cred *new) |
77ec739d | 82 | { |
0093ccb6 | 83 | struct user_namespace *ns, *parent_ns = new->user_ns; |
078de5f7 EB |
84 | kuid_t owner = new->euid; |
85 | kgid_t group = new->egid; | |
f6b2db1a | 86 | struct ucounts *ucounts; |
25f9c081 | 87 | int ret, i; |
783291e6 | 88 | |
df75e774 | 89 | ret = -ENOSPC; |
8742f229 | 90 | if (parent_ns->level > 32) |
b376c3e1 EB |
91 | goto fail; |
92 | ||
f6b2db1a EB |
93 | ucounts = inc_user_namespaces(parent_ns, owner); |
94 | if (!ucounts) | |
b376c3e1 | 95 | goto fail; |
8742f229 | 96 | |
3151527e EB |
97 | /* |
98 | * Verify that we can not violate the policy of which files | |
99 | * may be accessed that is specified by the root directory, | |
a12f4f85 | 100 | * by verifying that the root directory is at the root of the |
3151527e EB |
101 | * mount namespace which allows all files to be accessed. |
102 | */ | |
b376c3e1 | 103 | ret = -EPERM; |
3151527e | 104 | if (current_chrooted()) |
b376c3e1 | 105 | goto fail_dec; |
3151527e | 106 | |
783291e6 EB |
107 | /* The creator needs a mapping in the parent user namespace |
108 | * or else we won't be able to reasonably tell userspace who | |
109 | * created a user_namespace. | |
110 | */ | |
b376c3e1 | 111 | ret = -EPERM; |
783291e6 EB |
112 | if (!kuid_has_mapping(parent_ns, owner) || |
113 | !kgid_has_mapping(parent_ns, group)) | |
b376c3e1 | 114 | goto fail_dec; |
77ec739d | 115 | |
b376c3e1 | 116 | ret = -ENOMEM; |
22d917d8 | 117 | ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL); |
77ec739d | 118 | if (!ns) |
b376c3e1 | 119 | goto fail_dec; |
77ec739d | 120 | |
db2e718a | 121 | ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP); |
6344c433 | 122 | ret = ns_alloc_inum(&ns->ns); |
b376c3e1 EB |
123 | if (ret) |
124 | goto fail_free; | |
33c42940 | 125 | ns->ns.ops = &userns_operations; |
98f842e6 | 126 | |
265cbd62 | 127 | refcount_set(&ns->ns.count, 1); |
cde1975b | 128 | /* Leave the new->user_ns reference with the new user namespace. */ |
aeb3ae9d | 129 | ns->parent = parent_ns; |
8742f229 | 130 | ns->level = parent_ns->level + 1; |
783291e6 EB |
131 | ns->owner = owner; |
132 | ns->group = group; | |
b032132c | 133 | INIT_WORK(&ns->work, free_user_ns); |
21d1c5e3 | 134 | for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) { |
25f9c081 EB |
135 | ns->ucount_max[i] = INT_MAX; |
136 | } | |
0ac983f5 | 137 | set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_NPROC, enforced_nproc_rlimit()); |
c1ada3dc AG |
138 | set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_MSGQUEUE, rlimit(RLIMIT_MSGQUEUE)); |
139 | set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_SIGPENDING, rlimit(RLIMIT_SIGPENDING)); | |
140 | set_rlimit_ucount_max(ns, UCOUNT_RLIMIT_MEMLOCK, rlimit(RLIMIT_MEMLOCK)); | |
f6b2db1a | 141 | ns->ucounts = ucounts; |
22d917d8 | 142 | |
9cc46516 EB |
143 | /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ |
144 | mutex_lock(&userns_state_mutex); | |
145 | ns->flags = parent_ns->flags; | |
146 | mutex_unlock(&userns_state_mutex); | |
147 | ||
b206f281 DH |
148 | #ifdef CONFIG_KEYS |
149 | INIT_LIST_HEAD(&ns->keyring_name_list); | |
0f44e4d9 | 150 | init_rwsem(&ns->keyring_sem); |
f36f8c75 | 151 | #endif |
dbec2846 EB |
152 | ret = -ENOMEM; |
153 | if (!setup_userns_sysctls(ns)) | |
154 | goto fail_keyring; | |
155 | ||
156 | set_cred_user_ns(new, ns); | |
18b6e041 | 157 | return 0; |
dbec2846 EB |
158 | fail_keyring: |
159 | #ifdef CONFIG_PERSISTENT_KEYRINGS | |
160 | key_put(ns->persistent_keyring_register); | |
161 | #endif | |
162 | ns_free_inum(&ns->ns); | |
b376c3e1 | 163 | fail_free: |
dbec2846 | 164 | kmem_cache_free(user_ns_cachep, ns); |
b376c3e1 | 165 | fail_dec: |
f6b2db1a | 166 | dec_user_namespaces(ucounts); |
b376c3e1 | 167 | fail: |
dbec2846 | 168 | return ret; |
acce292c CLG |
169 | } |
170 | ||
b2e0d987 EB |
171 | int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) |
172 | { | |
173 | struct cred *cred; | |
6160968c | 174 | int err = -ENOMEM; |
b2e0d987 EB |
175 | |
176 | if (!(unshare_flags & CLONE_NEWUSER)) | |
177 | return 0; | |
178 | ||
179 | cred = prepare_creds(); | |
6160968c ON |
180 | if (cred) { |
181 | err = create_user_ns(cred); | |
182 | if (err) | |
183 | put_cred(cred); | |
184 | else | |
185 | *new_cred = cred; | |
186 | } | |
b2e0d987 | 187 | |
6160968c | 188 | return err; |
b2e0d987 EB |
189 | } |
190 | ||
b032132c | 191 | static void free_user_ns(struct work_struct *work) |
acce292c | 192 | { |
b032132c EB |
193 | struct user_namespace *parent, *ns = |
194 | container_of(work, struct user_namespace, work); | |
783291e6 | 195 | |
c61a2810 | 196 | do { |
f6b2db1a | 197 | struct ucounts *ucounts = ns->ucounts; |
c61a2810 | 198 | parent = ns->parent; |
6397fac4 CB |
199 | if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
200 | kfree(ns->gid_map.forward); | |
201 | kfree(ns->gid_map.reverse); | |
202 | } | |
203 | if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { | |
204 | kfree(ns->uid_map.forward); | |
205 | kfree(ns->uid_map.reverse); | |
206 | } | |
207 | if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { | |
208 | kfree(ns->projid_map.forward); | |
209 | kfree(ns->projid_map.reverse); | |
210 | } | |
dbec2846 | 211 | retire_userns_sysctls(ns); |
b206f281 | 212 | key_free_user_ns(ns); |
6344c433 | 213 | ns_free_inum(&ns->ns); |
c61a2810 | 214 | kmem_cache_free(user_ns_cachep, ns); |
f6b2db1a | 215 | dec_user_namespaces(ucounts); |
c61a2810 | 216 | ns = parent; |
265cbd62 | 217 | } while (refcount_dec_and_test(&parent->ns.count)); |
acce292c | 218 | } |
b032132c EB |
219 | |
220 | void __put_user_ns(struct user_namespace *ns) | |
221 | { | |
222 | schedule_work(&ns->work); | |
223 | } | |
224 | EXPORT_SYMBOL(__put_user_ns); | |
5c1469de | 225 | |
6397fac4 CB |
226 | /** |
227 | * idmap_key struct holds the information necessary to find an idmapping in a | |
228 | * sorted idmap array. It is passed to cmp_map_id() as first argument. | |
229 | */ | |
230 | struct idmap_key { | |
231 | bool map_up; /* true -> id from kid; false -> kid from id */ | |
232 | u32 id; /* id to find */ | |
233 | u32 count; /* == 0 unless used with map_id_range_down() */ | |
234 | }; | |
235 | ||
236 | /** | |
237 | * cmp_map_id - Function to be passed to bsearch() to find the requested | |
238 | * idmapping. Expects struct idmap_key to be passed via @k. | |
239 | */ | |
240 | static int cmp_map_id(const void *k, const void *e) | |
241 | { | |
242 | u32 first, last, id2; | |
243 | const struct idmap_key *key = k; | |
244 | const struct uid_gid_extent *el = e; | |
245 | ||
11a8b927 | 246 | id2 = key->id + key->count - 1; |
6397fac4 CB |
247 | |
248 | /* handle map_id_{down,up}() */ | |
249 | if (key->map_up) | |
250 | first = el->lower_first; | |
251 | else | |
252 | first = el->first; | |
253 | ||
254 | last = first + el->count - 1; | |
255 | ||
256 | if (key->id >= first && key->id <= last && | |
257 | (id2 >= first && id2 <= last)) | |
258 | return 0; | |
259 | ||
260 | if (key->id < first || id2 < first) | |
261 | return -1; | |
262 | ||
263 | return 1; | |
264 | } | |
265 | ||
266 | /** | |
267 | * map_id_range_down_max - Find idmap via binary search in ordered idmap array. | |
268 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. | |
269 | */ | |
3edf652f EB |
270 | static struct uid_gid_extent * |
271 | map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) | |
5c1469de | 272 | { |
6397fac4 CB |
273 | struct idmap_key key; |
274 | ||
275 | key.map_up = false; | |
276 | key.count = count; | |
277 | key.id = id; | |
278 | ||
3edf652f EB |
279 | return bsearch(&key, map->forward, extents, |
280 | sizeof(struct uid_gid_extent), cmp_map_id); | |
6397fac4 CB |
281 | } |
282 | ||
283 | /** | |
284 | * map_id_range_down_base - Find idmap via binary search in static extent array. | |
285 | * Can only be called if number of mappings is equal or less than | |
286 | * UID_GID_MAP_MAX_BASE_EXTENTS. | |
287 | */ | |
3edf652f EB |
288 | static struct uid_gid_extent * |
289 | map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) | |
5c1469de | 290 | { |
3edf652f | 291 | unsigned idx; |
22d917d8 | 292 | u32 first, last, id2; |
5c1469de | 293 | |
22d917d8 | 294 | id2 = id + count - 1; |
5c1469de | 295 | |
22d917d8 | 296 | /* Find the matching extent */ |
22d917d8 EB |
297 | for (idx = 0; idx < extents; idx++) { |
298 | first = map->extent[idx].first; | |
299 | last = first + map->extent[idx].count - 1; | |
300 | if (id >= first && id <= last && | |
301 | (id2 >= first && id2 <= last)) | |
3edf652f | 302 | return &map->extent[idx]; |
22d917d8 | 303 | } |
3edf652f | 304 | return NULL; |
22d917d8 EB |
305 | } |
306 | ||
6397fac4 CB |
307 | static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count) |
308 | { | |
3edf652f EB |
309 | struct uid_gid_extent *extent; |
310 | unsigned extents = map->nr_extents; | |
6397fac4 CB |
311 | smp_rmb(); |
312 | ||
313 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
3edf652f EB |
314 | extent = map_id_range_down_base(extents, map, id, count); |
315 | else | |
316 | extent = map_id_range_down_max(extents, map, id, count); | |
317 | ||
22d917d8 | 318 | /* Map the id or note failure */ |
3edf652f EB |
319 | if (extent) |
320 | id = (id - extent->first) + extent->lower_first; | |
22d917d8 EB |
321 | else |
322 | id = (u32) -1; | |
323 | ||
324 | return id; | |
325 | } | |
326 | ||
327 | static u32 map_id_down(struct uid_gid_map *map, u32 id) | |
328 | { | |
ece66133 | 329 | return map_id_range_down(map, id, 1); |
6397fac4 CB |
330 | } |
331 | ||
332 | /** | |
333 | * map_id_up_base - Find idmap via binary search in static extent array. | |
334 | * Can only be called if number of mappings is equal or less than | |
335 | * UID_GID_MAP_MAX_BASE_EXTENTS. | |
336 | */ | |
3edf652f EB |
337 | static struct uid_gid_extent * |
338 | map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id) | |
22d917d8 | 339 | { |
3edf652f | 340 | unsigned idx; |
22d917d8 EB |
341 | u32 first, last; |
342 | ||
343 | /* Find the matching extent */ | |
22d917d8 | 344 | for (idx = 0; idx < extents; idx++) { |
22d917d8 | 345 | first = map->extent[idx].lower_first; |
22d917d8 EB |
346 | last = first + map->extent[idx].count - 1; |
347 | if (id >= first && id <= last) | |
3edf652f | 348 | return &map->extent[idx]; |
22d917d8 | 349 | } |
3edf652f | 350 | return NULL; |
22d917d8 | 351 | } |
22d917d8 | 352 | |
6397fac4 CB |
353 | /** |
354 | * map_id_up_max - Find idmap via binary search in ordered idmap array. | |
355 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. | |
356 | */ | |
3edf652f EB |
357 | static struct uid_gid_extent * |
358 | map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id) | |
6397fac4 | 359 | { |
6397fac4 CB |
360 | struct idmap_key key; |
361 | ||
362 | key.map_up = true; | |
11a8b927 | 363 | key.count = 1; |
6397fac4 CB |
364 | key.id = id; |
365 | ||
3edf652f EB |
366 | return bsearch(&key, map->reverse, extents, |
367 | sizeof(struct uid_gid_extent), cmp_map_id); | |
22d917d8 EB |
368 | } |
369 | ||
370 | static u32 map_id_up(struct uid_gid_map *map, u32 id) | |
371 | { | |
3edf652f EB |
372 | struct uid_gid_extent *extent; |
373 | unsigned extents = map->nr_extents; | |
e79323bd | 374 | smp_rmb(); |
6397fac4 | 375 | |
3edf652f EB |
376 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
377 | extent = map_id_up_base(extents, map, id); | |
378 | else | |
379 | extent = map_id_up_max(extents, map, id); | |
380 | ||
22d917d8 | 381 | /* Map the id or note failure */ |
6397fac4 CB |
382 | if (extent) |
383 | id = (id - extent->lower_first) + extent->first; | |
22d917d8 EB |
384 | else |
385 | id = (u32) -1; | |
386 | ||
387 | return id; | |
388 | } | |
389 | ||
390 | /** | |
391 | * make_kuid - Map a user-namespace uid pair into a kuid. | |
392 | * @ns: User namespace that the uid is in | |
393 | * @uid: User identifier | |
394 | * | |
395 | * Maps a user-namespace uid pair into a kernel internal kuid, | |
396 | * and returns that kuid. | |
397 | * | |
398 | * When there is no mapping defined for the user-namespace uid | |
399 | * pair INVALID_UID is returned. Callers are expected to test | |
b080e047 | 400 | * for and handle INVALID_UID being returned. INVALID_UID |
22d917d8 EB |
401 | * may be tested for using uid_valid(). |
402 | */ | |
403 | kuid_t make_kuid(struct user_namespace *ns, uid_t uid) | |
404 | { | |
405 | /* Map the uid to a global kernel uid */ | |
406 | return KUIDT_INIT(map_id_down(&ns->uid_map, uid)); | |
407 | } | |
408 | EXPORT_SYMBOL(make_kuid); | |
409 | ||
410 | /** | |
411 | * from_kuid - Create a uid from a kuid user-namespace pair. | |
412 | * @targ: The user namespace we want a uid in. | |
413 | * @kuid: The kernel internal uid to start with. | |
414 | * | |
415 | * Map @kuid into the user-namespace specified by @targ and | |
416 | * return the resulting uid. | |
417 | * | |
418 | * There is always a mapping into the initial user_namespace. | |
419 | * | |
420 | * If @kuid has no mapping in @targ (uid_t)-1 is returned. | |
421 | */ | |
422 | uid_t from_kuid(struct user_namespace *targ, kuid_t kuid) | |
423 | { | |
424 | /* Map the uid from a global kernel uid */ | |
425 | return map_id_up(&targ->uid_map, __kuid_val(kuid)); | |
426 | } | |
427 | EXPORT_SYMBOL(from_kuid); | |
428 | ||
429 | /** | |
430 | * from_kuid_munged - Create a uid from a kuid user-namespace pair. | |
431 | * @targ: The user namespace we want a uid in. | |
432 | * @kuid: The kernel internal uid to start with. | |
433 | * | |
434 | * Map @kuid into the user-namespace specified by @targ and | |
435 | * return the resulting uid. | |
436 | * | |
437 | * There is always a mapping into the initial user_namespace. | |
438 | * | |
439 | * Unlike from_kuid from_kuid_munged never fails and always | |
440 | * returns a valid uid. This makes from_kuid_munged appropriate | |
441 | * for use in syscalls like stat and getuid where failing the | |
442 | * system call and failing to provide a valid uid are not an | |
443 | * options. | |
444 | * | |
445 | * If @kuid has no mapping in @targ overflowuid is returned. | |
446 | */ | |
447 | uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid) | |
448 | { | |
449 | uid_t uid; | |
450 | uid = from_kuid(targ, kuid); | |
451 | ||
452 | if (uid == (uid_t) -1) | |
453 | uid = overflowuid; | |
454 | return uid; | |
455 | } | |
456 | EXPORT_SYMBOL(from_kuid_munged); | |
457 | ||
458 | /** | |
459 | * make_kgid - Map a user-namespace gid pair into a kgid. | |
460 | * @ns: User namespace that the gid is in | |
68a9a435 | 461 | * @gid: group identifier |
22d917d8 EB |
462 | * |
463 | * Maps a user-namespace gid pair into a kernel internal kgid, | |
464 | * and returns that kgid. | |
465 | * | |
466 | * When there is no mapping defined for the user-namespace gid | |
467 | * pair INVALID_GID is returned. Callers are expected to test | |
468 | * for and handle INVALID_GID being returned. INVALID_GID may be | |
469 | * tested for using gid_valid(). | |
470 | */ | |
471 | kgid_t make_kgid(struct user_namespace *ns, gid_t gid) | |
472 | { | |
473 | /* Map the gid to a global kernel gid */ | |
474 | return KGIDT_INIT(map_id_down(&ns->gid_map, gid)); | |
475 | } | |
476 | EXPORT_SYMBOL(make_kgid); | |
477 | ||
478 | /** | |
479 | * from_kgid - Create a gid from a kgid user-namespace pair. | |
480 | * @targ: The user namespace we want a gid in. | |
481 | * @kgid: The kernel internal gid to start with. | |
482 | * | |
483 | * Map @kgid into the user-namespace specified by @targ and | |
484 | * return the resulting gid. | |
485 | * | |
486 | * There is always a mapping into the initial user_namespace. | |
487 | * | |
488 | * If @kgid has no mapping in @targ (gid_t)-1 is returned. | |
489 | */ | |
490 | gid_t from_kgid(struct user_namespace *targ, kgid_t kgid) | |
491 | { | |
492 | /* Map the gid from a global kernel gid */ | |
493 | return map_id_up(&targ->gid_map, __kgid_val(kgid)); | |
494 | } | |
495 | EXPORT_SYMBOL(from_kgid); | |
496 | ||
497 | /** | |
498 | * from_kgid_munged - Create a gid from a kgid user-namespace pair. | |
499 | * @targ: The user namespace we want a gid in. | |
500 | * @kgid: The kernel internal gid to start with. | |
501 | * | |
502 | * Map @kgid into the user-namespace specified by @targ and | |
503 | * return the resulting gid. | |
504 | * | |
505 | * There is always a mapping into the initial user_namespace. | |
506 | * | |
507 | * Unlike from_kgid from_kgid_munged never fails and always | |
508 | * returns a valid gid. This makes from_kgid_munged appropriate | |
509 | * for use in syscalls like stat and getgid where failing the | |
510 | * system call and failing to provide a valid gid are not options. | |
511 | * | |
512 | * If @kgid has no mapping in @targ overflowgid is returned. | |
513 | */ | |
514 | gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid) | |
515 | { | |
516 | gid_t gid; | |
517 | gid = from_kgid(targ, kgid); | |
518 | ||
519 | if (gid == (gid_t) -1) | |
520 | gid = overflowgid; | |
521 | return gid; | |
522 | } | |
523 | EXPORT_SYMBOL(from_kgid_munged); | |
524 | ||
f76d207a EB |
525 | /** |
526 | * make_kprojid - Map a user-namespace projid pair into a kprojid. | |
527 | * @ns: User namespace that the projid is in | |
528 | * @projid: Project identifier | |
529 | * | |
530 | * Maps a user-namespace uid pair into a kernel internal kuid, | |
531 | * and returns that kuid. | |
532 | * | |
533 | * When there is no mapping defined for the user-namespace projid | |
534 | * pair INVALID_PROJID is returned. Callers are expected to test | |
7b7b8a2c | 535 | * for and handle INVALID_PROJID being returned. INVALID_PROJID |
f76d207a EB |
536 | * may be tested for using projid_valid(). |
537 | */ | |
538 | kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid) | |
539 | { | |
540 | /* Map the uid to a global kernel uid */ | |
541 | return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid)); | |
542 | } | |
543 | EXPORT_SYMBOL(make_kprojid); | |
544 | ||
545 | /** | |
546 | * from_kprojid - Create a projid from a kprojid user-namespace pair. | |
547 | * @targ: The user namespace we want a projid in. | |
548 | * @kprojid: The kernel internal project identifier to start with. | |
549 | * | |
550 | * Map @kprojid into the user-namespace specified by @targ and | |
551 | * return the resulting projid. | |
552 | * | |
553 | * There is always a mapping into the initial user_namespace. | |
554 | * | |
555 | * If @kprojid has no mapping in @targ (projid_t)-1 is returned. | |
556 | */ | |
557 | projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid) | |
558 | { | |
559 | /* Map the uid from a global kernel uid */ | |
560 | return map_id_up(&targ->projid_map, __kprojid_val(kprojid)); | |
561 | } | |
562 | EXPORT_SYMBOL(from_kprojid); | |
563 | ||
564 | /** | |
565 | * from_kprojid_munged - Create a projiid from a kprojid user-namespace pair. | |
566 | * @targ: The user namespace we want a projid in. | |
567 | * @kprojid: The kernel internal projid to start with. | |
568 | * | |
569 | * Map @kprojid into the user-namespace specified by @targ and | |
570 | * return the resulting projid. | |
571 | * | |
572 | * There is always a mapping into the initial user_namespace. | |
573 | * | |
574 | * Unlike from_kprojid from_kprojid_munged never fails and always | |
575 | * returns a valid projid. This makes from_kprojid_munged | |
576 | * appropriate for use in syscalls like stat and where | |
577 | * failing the system call and failing to provide a valid projid are | |
578 | * not an options. | |
579 | * | |
580 | * If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned. | |
581 | */ | |
582 | projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid) | |
583 | { | |
584 | projid_t projid; | |
585 | projid = from_kprojid(targ, kprojid); | |
586 | ||
587 | if (projid == (projid_t) -1) | |
588 | projid = OVERFLOW_PROJID; | |
589 | return projid; | |
590 | } | |
591 | EXPORT_SYMBOL(from_kprojid_munged); | |
592 | ||
593 | ||
22d917d8 EB |
594 | static int uid_m_show(struct seq_file *seq, void *v) |
595 | { | |
596 | struct user_namespace *ns = seq->private; | |
597 | struct uid_gid_extent *extent = v; | |
598 | struct user_namespace *lower_ns; | |
599 | uid_t lower; | |
5c1469de | 600 | |
c450f371 | 601 | lower_ns = seq_user_ns(seq); |
22d917d8 EB |
602 | if ((lower_ns == ns) && lower_ns->parent) |
603 | lower_ns = lower_ns->parent; | |
604 | ||
605 | lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first)); | |
606 | ||
607 | seq_printf(seq, "%10u %10u %10u\n", | |
608 | extent->first, | |
609 | lower, | |
610 | extent->count); | |
611 | ||
612 | return 0; | |
5c1469de EB |
613 | } |
614 | ||
22d917d8 | 615 | static int gid_m_show(struct seq_file *seq, void *v) |
5c1469de | 616 | { |
22d917d8 EB |
617 | struct user_namespace *ns = seq->private; |
618 | struct uid_gid_extent *extent = v; | |
619 | struct user_namespace *lower_ns; | |
620 | gid_t lower; | |
5c1469de | 621 | |
c450f371 | 622 | lower_ns = seq_user_ns(seq); |
22d917d8 EB |
623 | if ((lower_ns == ns) && lower_ns->parent) |
624 | lower_ns = lower_ns->parent; | |
5c1469de | 625 | |
22d917d8 EB |
626 | lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); |
627 | ||
628 | seq_printf(seq, "%10u %10u %10u\n", | |
629 | extent->first, | |
630 | lower, | |
631 | extent->count); | |
632 | ||
633 | return 0; | |
634 | } | |
635 | ||
f76d207a EB |
636 | static int projid_m_show(struct seq_file *seq, void *v) |
637 | { | |
638 | struct user_namespace *ns = seq->private; | |
639 | struct uid_gid_extent *extent = v; | |
640 | struct user_namespace *lower_ns; | |
641 | projid_t lower; | |
642 | ||
643 | lower_ns = seq_user_ns(seq); | |
644 | if ((lower_ns == ns) && lower_ns->parent) | |
645 | lower_ns = lower_ns->parent; | |
646 | ||
647 | lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first)); | |
648 | ||
649 | seq_printf(seq, "%10u %10u %10u\n", | |
650 | extent->first, | |
651 | lower, | |
652 | extent->count); | |
653 | ||
654 | return 0; | |
655 | } | |
656 | ||
68a9a435 FF |
657 | static void *m_start(struct seq_file *seq, loff_t *ppos, |
658 | struct uid_gid_map *map) | |
22d917d8 | 659 | { |
22d917d8 | 660 | loff_t pos = *ppos; |
d5e7b3c5 EB |
661 | unsigned extents = map->nr_extents; |
662 | smp_rmb(); | |
22d917d8 | 663 | |
d5e7b3c5 | 664 | if (pos >= extents) |
6397fac4 | 665 | return NULL; |
22d917d8 | 666 | |
d5e7b3c5 | 667 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
6397fac4 | 668 | return &map->extent[pos]; |
22d917d8 | 669 | |
6397fac4 | 670 | return &map->forward[pos]; |
22d917d8 EB |
671 | } |
672 | ||
673 | static void *uid_m_start(struct seq_file *seq, loff_t *ppos) | |
674 | { | |
675 | struct user_namespace *ns = seq->private; | |
676 | ||
677 | return m_start(seq, ppos, &ns->uid_map); | |
678 | } | |
679 | ||
680 | static void *gid_m_start(struct seq_file *seq, loff_t *ppos) | |
681 | { | |
682 | struct user_namespace *ns = seq->private; | |
683 | ||
684 | return m_start(seq, ppos, &ns->gid_map); | |
685 | } | |
686 | ||
f76d207a EB |
687 | static void *projid_m_start(struct seq_file *seq, loff_t *ppos) |
688 | { | |
689 | struct user_namespace *ns = seq->private; | |
690 | ||
691 | return m_start(seq, ppos, &ns->projid_map); | |
692 | } | |
693 | ||
22d917d8 EB |
694 | static void *m_next(struct seq_file *seq, void *v, loff_t *pos) |
695 | { | |
696 | (*pos)++; | |
697 | return seq->op->start(seq, pos); | |
698 | } | |
699 | ||
700 | static void m_stop(struct seq_file *seq, void *v) | |
701 | { | |
702 | return; | |
703 | } | |
704 | ||
ccf94f1b | 705 | const struct seq_operations proc_uid_seq_operations = { |
22d917d8 EB |
706 | .start = uid_m_start, |
707 | .stop = m_stop, | |
708 | .next = m_next, | |
709 | .show = uid_m_show, | |
710 | }; | |
711 | ||
ccf94f1b | 712 | const struct seq_operations proc_gid_seq_operations = { |
22d917d8 EB |
713 | .start = gid_m_start, |
714 | .stop = m_stop, | |
715 | .next = m_next, | |
716 | .show = gid_m_show, | |
717 | }; | |
718 | ||
ccf94f1b | 719 | const struct seq_operations proc_projid_seq_operations = { |
f76d207a EB |
720 | .start = projid_m_start, |
721 | .stop = m_stop, | |
722 | .next = m_next, | |
723 | .show = projid_m_show, | |
724 | }; | |
725 | ||
68a9a435 FF |
726 | static bool mappings_overlap(struct uid_gid_map *new_map, |
727 | struct uid_gid_extent *extent) | |
0bd14b4f EB |
728 | { |
729 | u32 upper_first, lower_first, upper_last, lower_last; | |
730 | unsigned idx; | |
731 | ||
732 | upper_first = extent->first; | |
733 | lower_first = extent->lower_first; | |
734 | upper_last = upper_first + extent->count - 1; | |
735 | lower_last = lower_first + extent->count - 1; | |
736 | ||
737 | for (idx = 0; idx < new_map->nr_extents; idx++) { | |
738 | u32 prev_upper_first, prev_lower_first; | |
739 | u32 prev_upper_last, prev_lower_last; | |
740 | struct uid_gid_extent *prev; | |
741 | ||
6397fac4 CB |
742 | if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
743 | prev = &new_map->extent[idx]; | |
744 | else | |
745 | prev = &new_map->forward[idx]; | |
0bd14b4f EB |
746 | |
747 | prev_upper_first = prev->first; | |
748 | prev_lower_first = prev->lower_first; | |
749 | prev_upper_last = prev_upper_first + prev->count - 1; | |
750 | prev_lower_last = prev_lower_first + prev->count - 1; | |
751 | ||
752 | /* Does the upper range intersect a previous extent? */ | |
753 | if ((prev_upper_first <= upper_last) && | |
754 | (prev_upper_last >= upper_first)) | |
755 | return true; | |
756 | ||
757 | /* Does the lower range intersect a previous extent? */ | |
758 | if ((prev_lower_first <= lower_last) && | |
759 | (prev_lower_last >= lower_first)) | |
760 | return true; | |
761 | } | |
762 | return false; | |
763 | } | |
764 | ||
6397fac4 CB |
765 | /** |
766 | * insert_extent - Safely insert a new idmap extent into struct uid_gid_map. | |
767 | * Takes care to allocate a 4K block of memory if the number of mappings exceeds | |
768 | * UID_GID_MAP_MAX_BASE_EXTENTS. | |
769 | */ | |
770 | static int insert_extent(struct uid_gid_map *map, struct uid_gid_extent *extent) | |
771 | { | |
3fda0e73 | 772 | struct uid_gid_extent *dest; |
6397fac4 CB |
773 | |
774 | if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) { | |
775 | struct uid_gid_extent *forward; | |
776 | ||
777 | /* Allocate memory for 340 mappings. */ | |
6da2ec56 KC |
778 | forward = kmalloc_array(UID_GID_MAP_MAX_EXTENTS, |
779 | sizeof(struct uid_gid_extent), | |
780 | GFP_KERNEL); | |
6397fac4 CB |
781 | if (!forward) |
782 | return -ENOMEM; | |
783 | ||
784 | /* Copy over memory. Only set up memory for the forward pointer. | |
785 | * Defer the memory setup for the reverse pointer. | |
786 | */ | |
787 | memcpy(forward, map->extent, | |
788 | map->nr_extents * sizeof(map->extent[0])); | |
789 | ||
790 | map->forward = forward; | |
791 | map->reverse = NULL; | |
792 | } | |
793 | ||
3fda0e73 EB |
794 | if (map->nr_extents < UID_GID_MAP_MAX_BASE_EXTENTS) |
795 | dest = &map->extent[map->nr_extents]; | |
796 | else | |
797 | dest = &map->forward[map->nr_extents]; | |
798 | ||
799 | *dest = *extent; | |
800 | map->nr_extents++; | |
6397fac4 CB |
801 | return 0; |
802 | } | |
803 | ||
804 | /* cmp function to sort() forward mappings */ | |
805 | static int cmp_extents_forward(const void *a, const void *b) | |
806 | { | |
807 | const struct uid_gid_extent *e1 = a; | |
808 | const struct uid_gid_extent *e2 = b; | |
809 | ||
810 | if (e1->first < e2->first) | |
811 | return -1; | |
812 | ||
813 | if (e1->first > e2->first) | |
814 | return 1; | |
815 | ||
816 | return 0; | |
817 | } | |
818 | ||
819 | /* cmp function to sort() reverse mappings */ | |
820 | static int cmp_extents_reverse(const void *a, const void *b) | |
821 | { | |
822 | const struct uid_gid_extent *e1 = a; | |
823 | const struct uid_gid_extent *e2 = b; | |
824 | ||
825 | if (e1->lower_first < e2->lower_first) | |
826 | return -1; | |
827 | ||
828 | if (e1->lower_first > e2->lower_first) | |
829 | return 1; | |
830 | ||
831 | return 0; | |
832 | } | |
833 | ||
834 | /** | |
835 | * sort_idmaps - Sorts an array of idmap entries. | |
836 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. | |
837 | */ | |
838 | static int sort_idmaps(struct uid_gid_map *map) | |
839 | { | |
840 | if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
841 | return 0; | |
842 | ||
843 | /* Sort forward array. */ | |
844 | sort(map->forward, map->nr_extents, sizeof(struct uid_gid_extent), | |
845 | cmp_extents_forward, NULL); | |
846 | ||
847 | /* Only copy the memory from forward we actually need. */ | |
848 | map->reverse = kmemdup(map->forward, | |
849 | map->nr_extents * sizeof(struct uid_gid_extent), | |
850 | GFP_KERNEL); | |
851 | if (!map->reverse) | |
852 | return -ENOMEM; | |
853 | ||
854 | /* Sort reverse array. */ | |
855 | sort(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent), | |
856 | cmp_extents_reverse, NULL); | |
857 | ||
858 | return 0; | |
859 | } | |
860 | ||
db2e718a SH |
861 | /** |
862 | * verify_root_map() - check the uid 0 mapping | |
863 | * @file: idmapping file | |
864 | * @map_ns: user namespace of the target process | |
865 | * @new_map: requested idmap | |
866 | * | |
867 | * If a process requests mapping parent uid 0 into the new ns, verify that the | |
868 | * process writing the map had the CAP_SETFCAP capability as the target process | |
869 | * will be able to write fscaps that are valid in ancestor user namespaces. | |
870 | * | |
871 | * Return: true if the mapping is allowed, false if not. | |
872 | */ | |
873 | static bool verify_root_map(const struct file *file, | |
874 | struct user_namespace *map_ns, | |
875 | struct uid_gid_map *new_map) | |
876 | { | |
877 | int idx; | |
878 | const struct user_namespace *file_ns = file->f_cred->user_ns; | |
879 | struct uid_gid_extent *extent0 = NULL; | |
880 | ||
881 | for (idx = 0; idx < new_map->nr_extents; idx++) { | |
882 | if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
883 | extent0 = &new_map->extent[idx]; | |
884 | else | |
885 | extent0 = &new_map->forward[idx]; | |
886 | if (extent0->lower_first == 0) | |
887 | break; | |
888 | ||
889 | extent0 = NULL; | |
890 | } | |
891 | ||
892 | if (!extent0) | |
893 | return true; | |
894 | ||
895 | if (map_ns == file_ns) { | |
896 | /* The process unshared its ns and is writing to its own | |
897 | * /proc/self/uid_map. User already has full capabilites in | |
898 | * the new namespace. Verify that the parent had CAP_SETFCAP | |
899 | * when it unshared. | |
900 | * */ | |
901 | if (!file_ns->parent_could_setfcap) | |
902 | return false; | |
903 | } else { | |
904 | /* Process p1 is writing to uid_map of p2, who is in a child | |
905 | * user namespace to p1's. Verify that the opener of the map | |
906 | * file has CAP_SETFCAP against the parent of the new map | |
907 | * namespace */ | |
908 | if (!file_ns_capable(file, map_ns->parent, CAP_SETFCAP)) | |
909 | return false; | |
910 | } | |
911 | ||
912 | return true; | |
913 | } | |
914 | ||
22d917d8 EB |
915 | static ssize_t map_write(struct file *file, const char __user *buf, |
916 | size_t count, loff_t *ppos, | |
917 | int cap_setid, | |
918 | struct uid_gid_map *map, | |
919 | struct uid_gid_map *parent_map) | |
920 | { | |
921 | struct seq_file *seq = file->private_data; | |
db2e718a | 922 | struct user_namespace *map_ns = seq->private; |
22d917d8 EB |
923 | struct uid_gid_map new_map; |
924 | unsigned idx; | |
6397fac4 | 925 | struct uid_gid_extent extent; |
70f6cbb6 | 926 | char *kbuf = NULL, *pos, *next_line; |
5820f140 JH |
927 | ssize_t ret; |
928 | ||
929 | /* Only allow < page size writes at the beginning of the file */ | |
930 | if ((*ppos != 0) || (count >= PAGE_SIZE)) | |
931 | return -EINVAL; | |
932 | ||
933 | /* Slurp in the user data */ | |
934 | kbuf = memdup_user_nul(buf, count); | |
935 | if (IS_ERR(kbuf)) | |
936 | return PTR_ERR(kbuf); | |
22d917d8 EB |
937 | |
938 | /* | |
f0d62aec | 939 | * The userns_state_mutex serializes all writes to any given map. |
22d917d8 EB |
940 | * |
941 | * Any map is only ever written once. | |
942 | * | |
943 | * An id map fits within 1 cache line on most architectures. | |
944 | * | |
945 | * On read nothing needs to be done unless you are on an | |
946 | * architecture with a crazy cache coherency model like alpha. | |
947 | * | |
948 | * There is a one time data dependency between reading the | |
949 | * count of the extents and the values of the extents. The | |
950 | * desired behavior is to see the values of the extents that | |
951 | * were written before the count of the extents. | |
952 | * | |
953 | * To achieve this smp_wmb() is used on guarantee the write | |
e79323bd MP |
954 | * order and smp_rmb() is guaranteed that we don't have crazy |
955 | * architectures returning stale data. | |
22d917d8 | 956 | */ |
f0d62aec | 957 | mutex_lock(&userns_state_mutex); |
22d917d8 | 958 | |
6397fac4 CB |
959 | memset(&new_map, 0, sizeof(struct uid_gid_map)); |
960 | ||
22d917d8 EB |
961 | ret = -EPERM; |
962 | /* Only allow one successful write to the map */ | |
963 | if (map->nr_extents != 0) | |
964 | goto out; | |
965 | ||
41c21e35 AL |
966 | /* |
967 | * Adjusting namespace settings requires capabilities on the target. | |
5c1469de | 968 | */ |
db2e718a | 969 | if (cap_valid(cap_setid) && !file_ns_capable(file, map_ns, CAP_SYS_ADMIN)) |
22d917d8 EB |
970 | goto out; |
971 | ||
22d917d8 EB |
972 | /* Parse the user data */ |
973 | ret = -EINVAL; | |
974 | pos = kbuf; | |
68a9a435 | 975 | for (; pos; pos = next_line) { |
22d917d8 EB |
976 | |
977 | /* Find the end of line and ensure I don't look past it */ | |
978 | next_line = strchr(pos, '\n'); | |
979 | if (next_line) { | |
980 | *next_line = '\0'; | |
981 | next_line++; | |
982 | if (*next_line == '\0') | |
983 | next_line = NULL; | |
5c1469de | 984 | } |
22d917d8 EB |
985 | |
986 | pos = skip_spaces(pos); | |
6397fac4 | 987 | extent.first = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
988 | if (!isspace(*pos)) |
989 | goto out; | |
990 | ||
991 | pos = skip_spaces(pos); | |
6397fac4 | 992 | extent.lower_first = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
993 | if (!isspace(*pos)) |
994 | goto out; | |
995 | ||
996 | pos = skip_spaces(pos); | |
6397fac4 | 997 | extent.count = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
998 | if (*pos && !isspace(*pos)) |
999 | goto out; | |
1000 | ||
1001 | /* Verify there is not trailing junk on the line */ | |
1002 | pos = skip_spaces(pos); | |
1003 | if (*pos != '\0') | |
1004 | goto out; | |
1005 | ||
1006 | /* Verify we have been given valid starting values */ | |
6397fac4 CB |
1007 | if ((extent.first == (u32) -1) || |
1008 | (extent.lower_first == (u32) -1)) | |
22d917d8 EB |
1009 | goto out; |
1010 | ||
68a9a435 FF |
1011 | /* Verify count is not zero and does not cause the |
1012 | * extent to wrap | |
1013 | */ | |
6397fac4 | 1014 | if ((extent.first + extent.count) <= extent.first) |
22d917d8 | 1015 | goto out; |
6397fac4 CB |
1016 | if ((extent.lower_first + extent.count) <= |
1017 | extent.lower_first) | |
22d917d8 EB |
1018 | goto out; |
1019 | ||
0bd14b4f | 1020 | /* Do the ranges in extent overlap any previous extents? */ |
6397fac4 | 1021 | if (mappings_overlap(&new_map, &extent)) |
22d917d8 EB |
1022 | goto out; |
1023 | ||
6397fac4 | 1024 | if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS && |
22d917d8 EB |
1025 | (next_line != NULL)) |
1026 | goto out; | |
6397fac4 CB |
1027 | |
1028 | ret = insert_extent(&new_map, &extent); | |
1029 | if (ret < 0) | |
1030 | goto out; | |
1031 | ret = -EINVAL; | |
5c1469de | 1032 | } |
a12f4f85 | 1033 | /* Be very certain the new map actually exists */ |
22d917d8 EB |
1034 | if (new_map.nr_extents == 0) |
1035 | goto out; | |
1036 | ||
1037 | ret = -EPERM; | |
1038 | /* Validate the user is allowed to use user id's mapped to. */ | |
db2e718a | 1039 | if (!new_idmap_permitted(file, map_ns, cap_setid, &new_map)) |
22d917d8 EB |
1040 | goto out; |
1041 | ||
6397fac4 | 1042 | ret = -EPERM; |
22d917d8 EB |
1043 | /* Map the lower ids from the parent user namespace to the |
1044 | * kernel global id space. | |
1045 | */ | |
1046 | for (idx = 0; idx < new_map.nr_extents; idx++) { | |
6397fac4 | 1047 | struct uid_gid_extent *e; |
22d917d8 | 1048 | u32 lower_first; |
6397fac4 CB |
1049 | |
1050 | if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
1051 | e = &new_map.extent[idx]; | |
1052 | else | |
1053 | e = &new_map.forward[idx]; | |
22d917d8 EB |
1054 | |
1055 | lower_first = map_id_range_down(parent_map, | |
6397fac4 CB |
1056 | e->lower_first, |
1057 | e->count); | |
22d917d8 EB |
1058 | |
1059 | /* Fail if we can not map the specified extent to | |
1060 | * the kernel global id space. | |
1061 | */ | |
1062 | if (lower_first == (u32) -1) | |
1063 | goto out; | |
1064 | ||
6397fac4 | 1065 | e->lower_first = lower_first; |
22d917d8 EB |
1066 | } |
1067 | ||
d2f007db JH |
1068 | /* |
1069 | * If we want to use binary search for lookup, this clones the extent | |
1070 | * array and sorts both copies. | |
1071 | */ | |
1072 | ret = sort_idmaps(&new_map); | |
1073 | if (ret < 0) | |
1074 | goto out; | |
1075 | ||
22d917d8 | 1076 | /* Install the map */ |
6397fac4 CB |
1077 | if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { |
1078 | memcpy(map->extent, new_map.extent, | |
1079 | new_map.nr_extents * sizeof(new_map.extent[0])); | |
1080 | } else { | |
1081 | map->forward = new_map.forward; | |
1082 | map->reverse = new_map.reverse; | |
1083 | } | |
22d917d8 EB |
1084 | smp_wmb(); |
1085 | map->nr_extents = new_map.nr_extents; | |
1086 | ||
1087 | *ppos = count; | |
1088 | ret = count; | |
1089 | out: | |
6397fac4 CB |
1090 | if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
1091 | kfree(new_map.forward); | |
1092 | kfree(new_map.reverse); | |
1093 | map->forward = NULL; | |
1094 | map->reverse = NULL; | |
1095 | map->nr_extents = 0; | |
1096 | } | |
1097 | ||
f0d62aec | 1098 | mutex_unlock(&userns_state_mutex); |
70f6cbb6 | 1099 | kfree(kbuf); |
22d917d8 EB |
1100 | return ret; |
1101 | } | |
1102 | ||
68a9a435 FF |
1103 | ssize_t proc_uid_map_write(struct file *file, const char __user *buf, |
1104 | size_t size, loff_t *ppos) | |
22d917d8 EB |
1105 | { |
1106 | struct seq_file *seq = file->private_data; | |
1107 | struct user_namespace *ns = seq->private; | |
c450f371 | 1108 | struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d8 EB |
1109 | |
1110 | if (!ns->parent) | |
1111 | return -EPERM; | |
1112 | ||
c450f371 EB |
1113 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1114 | return -EPERM; | |
1115 | ||
22d917d8 EB |
1116 | return map_write(file, buf, size, ppos, CAP_SETUID, |
1117 | &ns->uid_map, &ns->parent->uid_map); | |
1118 | } | |
1119 | ||
68a9a435 FF |
1120 | ssize_t proc_gid_map_write(struct file *file, const char __user *buf, |
1121 | size_t size, loff_t *ppos) | |
22d917d8 EB |
1122 | { |
1123 | struct seq_file *seq = file->private_data; | |
1124 | struct user_namespace *ns = seq->private; | |
c450f371 | 1125 | struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d8 EB |
1126 | |
1127 | if (!ns->parent) | |
1128 | return -EPERM; | |
1129 | ||
c450f371 EB |
1130 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1131 | return -EPERM; | |
1132 | ||
22d917d8 EB |
1133 | return map_write(file, buf, size, ppos, CAP_SETGID, |
1134 | &ns->gid_map, &ns->parent->gid_map); | |
1135 | } | |
1136 | ||
68a9a435 FF |
1137 | ssize_t proc_projid_map_write(struct file *file, const char __user *buf, |
1138 | size_t size, loff_t *ppos) | |
f76d207a EB |
1139 | { |
1140 | struct seq_file *seq = file->private_data; | |
1141 | struct user_namespace *ns = seq->private; | |
1142 | struct user_namespace *seq_ns = seq_user_ns(seq); | |
1143 | ||
1144 | if (!ns->parent) | |
1145 | return -EPERM; | |
1146 | ||
1147 | if ((seq_ns != ns) && (seq_ns != ns->parent)) | |
1148 | return -EPERM; | |
1149 | ||
1150 | /* Anyone can set any valid project id no capability needed */ | |
1151 | return map_write(file, buf, size, ppos, -1, | |
1152 | &ns->projid_map, &ns->parent->projid_map); | |
1153 | } | |
1154 | ||
68a9a435 | 1155 | static bool new_idmap_permitted(const struct file *file, |
6708075f | 1156 | struct user_namespace *ns, int cap_setid, |
22d917d8 EB |
1157 | struct uid_gid_map *new_map) |
1158 | { | |
f95d7918 | 1159 | const struct cred *cred = file->f_cred; |
db2e718a SH |
1160 | |
1161 | if (cap_setid == CAP_SETUID && !verify_root_map(file, ns, new_map)) | |
1162 | return false; | |
1163 | ||
0542f17b EB |
1164 | /* Don't allow mappings that would allow anything that wouldn't |
1165 | * be allowed without the establishment of unprivileged mappings. | |
1166 | */ | |
f95d7918 EB |
1167 | if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) && |
1168 | uid_eq(ns->owner, cred->euid)) { | |
37657da3 EB |
1169 | u32 id = new_map->extent[0].lower_first; |
1170 | if (cap_setid == CAP_SETUID) { | |
1171 | kuid_t uid = make_kuid(ns->parent, id); | |
f95d7918 | 1172 | if (uid_eq(uid, cred->euid)) |
37657da3 | 1173 | return true; |
68a9a435 | 1174 | } else if (cap_setid == CAP_SETGID) { |
37657da3 | 1175 | kgid_t gid = make_kgid(ns->parent, id); |
66d2f338 EB |
1176 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && |
1177 | gid_eq(gid, cred->egid)) | |
37657da3 EB |
1178 | return true; |
1179 | } | |
1180 | } | |
1181 | ||
f76d207a EB |
1182 | /* Allow anyone to set a mapping that doesn't require privilege */ |
1183 | if (!cap_valid(cap_setid)) | |
1184 | return true; | |
1185 | ||
22d917d8 EB |
1186 | /* Allow the specified ids if we have the appropriate capability |
1187 | * (CAP_SETUID or CAP_SETGID) over the parent user namespace. | |
a12f4f85 | 1188 | * And the opener of the id file also has the appropriate capability. |
22d917d8 | 1189 | */ |
6708075f EB |
1190 | if (ns_capable(ns->parent, cap_setid) && |
1191 | file_ns_capable(file, ns->parent, cap_setid)) | |
22d917d8 | 1192 | return true; |
5c1469de | 1193 | |
22d917d8 | 1194 | return false; |
5c1469de | 1195 | } |
6164281a | 1196 | |
9cc46516 EB |
1197 | int proc_setgroups_show(struct seq_file *seq, void *v) |
1198 | { | |
1199 | struct user_namespace *ns = seq->private; | |
6aa7de05 | 1200 | unsigned long userns_flags = READ_ONCE(ns->flags); |
9cc46516 EB |
1201 | |
1202 | seq_printf(seq, "%s\n", | |
1203 | (userns_flags & USERNS_SETGROUPS_ALLOWED) ? | |
1204 | "allow" : "deny"); | |
1205 | return 0; | |
1206 | } | |
1207 | ||
1208 | ssize_t proc_setgroups_write(struct file *file, const char __user *buf, | |
1209 | size_t count, loff_t *ppos) | |
1210 | { | |
1211 | struct seq_file *seq = file->private_data; | |
1212 | struct user_namespace *ns = seq->private; | |
1213 | char kbuf[8], *pos; | |
1214 | bool setgroups_allowed; | |
1215 | ssize_t ret; | |
1216 | ||
1217 | /* Only allow a very narrow range of strings to be written */ | |
1218 | ret = -EINVAL; | |
1219 | if ((*ppos != 0) || (count >= sizeof(kbuf))) | |
1220 | goto out; | |
1221 | ||
1222 | /* What was written? */ | |
1223 | ret = -EFAULT; | |
1224 | if (copy_from_user(kbuf, buf, count)) | |
1225 | goto out; | |
1226 | kbuf[count] = '\0'; | |
1227 | pos = kbuf; | |
1228 | ||
1229 | /* What is being requested? */ | |
1230 | ret = -EINVAL; | |
1231 | if (strncmp(pos, "allow", 5) == 0) { | |
1232 | pos += 5; | |
1233 | setgroups_allowed = true; | |
1234 | } | |
1235 | else if (strncmp(pos, "deny", 4) == 0) { | |
1236 | pos += 4; | |
1237 | setgroups_allowed = false; | |
1238 | } | |
1239 | else | |
1240 | goto out; | |
1241 | ||
1242 | /* Verify there is not trailing junk on the line */ | |
1243 | pos = skip_spaces(pos); | |
1244 | if (*pos != '\0') | |
1245 | goto out; | |
1246 | ||
1247 | ret = -EPERM; | |
1248 | mutex_lock(&userns_state_mutex); | |
1249 | if (setgroups_allowed) { | |
1250 | /* Enabling setgroups after setgroups has been disabled | |
1251 | * is not allowed. | |
1252 | */ | |
1253 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED)) | |
1254 | goto out_unlock; | |
1255 | } else { | |
1256 | /* Permanently disabling setgroups after setgroups has | |
1257 | * been enabled by writing the gid_map is not allowed. | |
1258 | */ | |
1259 | if (ns->gid_map.nr_extents != 0) | |
1260 | goto out_unlock; | |
1261 | ns->flags &= ~USERNS_SETGROUPS_ALLOWED; | |
1262 | } | |
1263 | mutex_unlock(&userns_state_mutex); | |
1264 | ||
1265 | /* Report a successful write */ | |
1266 | *ppos = count; | |
1267 | ret = count; | |
1268 | out: | |
1269 | return ret; | |
1270 | out_unlock: | |
1271 | mutex_unlock(&userns_state_mutex); | |
1272 | goto out; | |
1273 | } | |
1274 | ||
273d2c67 EB |
1275 | bool userns_may_setgroups(const struct user_namespace *ns) |
1276 | { | |
1277 | bool allowed; | |
1278 | ||
f0d62aec | 1279 | mutex_lock(&userns_state_mutex); |
273d2c67 EB |
1280 | /* It is not safe to use setgroups until a gid mapping in |
1281 | * the user namespace has been established. | |
1282 | */ | |
1283 | allowed = ns->gid_map.nr_extents != 0; | |
9cc46516 EB |
1284 | /* Is setgroups allowed? */ |
1285 | allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED); | |
f0d62aec | 1286 | mutex_unlock(&userns_state_mutex); |
273d2c67 EB |
1287 | |
1288 | return allowed; | |
1289 | } | |
1290 | ||
d07b846f | 1291 | /* |
a2b42626 EB |
1292 | * Returns true if @child is the same namespace or a descendant of |
1293 | * @ancestor. | |
d07b846f | 1294 | */ |
a2b42626 EB |
1295 | bool in_userns(const struct user_namespace *ancestor, |
1296 | const struct user_namespace *child) | |
1297 | { | |
1298 | const struct user_namespace *ns; | |
1299 | for (ns = child; ns->level > ancestor->level; ns = ns->parent) | |
1300 | ; | |
1301 | return (ns == ancestor); | |
1302 | } | |
1303 | ||
d07b846f SF |
1304 | bool current_in_userns(const struct user_namespace *target_ns) |
1305 | { | |
a2b42626 | 1306 | return in_userns(target_ns, current_user_ns()); |
d07b846f | 1307 | } |
73f03c2b | 1308 | EXPORT_SYMBOL(current_in_userns); |
d07b846f | 1309 | |
3c041184 AV |
1310 | static inline struct user_namespace *to_user_ns(struct ns_common *ns) |
1311 | { | |
1312 | return container_of(ns, struct user_namespace, ns); | |
1313 | } | |
1314 | ||
64964528 | 1315 | static struct ns_common *userns_get(struct task_struct *task) |
cde1975b EB |
1316 | { |
1317 | struct user_namespace *user_ns; | |
1318 | ||
1319 | rcu_read_lock(); | |
1320 | user_ns = get_user_ns(__task_cred(task)->user_ns); | |
1321 | rcu_read_unlock(); | |
1322 | ||
3c041184 | 1323 | return user_ns ? &user_ns->ns : NULL; |
cde1975b EB |
1324 | } |
1325 | ||
64964528 | 1326 | static void userns_put(struct ns_common *ns) |
cde1975b | 1327 | { |
3c041184 | 1328 | put_user_ns(to_user_ns(ns)); |
cde1975b EB |
1329 | } |
1330 | ||
f2a8d52e | 1331 | static int userns_install(struct nsset *nsset, struct ns_common *ns) |
cde1975b | 1332 | { |
3c041184 | 1333 | struct user_namespace *user_ns = to_user_ns(ns); |
cde1975b EB |
1334 | struct cred *cred; |
1335 | ||
1336 | /* Don't allow gaining capabilities by reentering | |
1337 | * the same user namespace. | |
1338 | */ | |
1339 | if (user_ns == current_user_ns()) | |
1340 | return -EINVAL; | |
1341 | ||
faf00da5 EB |
1342 | /* Tasks that share a thread group must share a user namespace */ |
1343 | if (!thread_group_empty(current)) | |
cde1975b EB |
1344 | return -EINVAL; |
1345 | ||
e66eded8 EB |
1346 | if (current->fs->users != 1) |
1347 | return -EINVAL; | |
1348 | ||
cde1975b EB |
1349 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
1350 | return -EPERM; | |
1351 | ||
f2a8d52e | 1352 | cred = nsset_cred(nsset); |
cde1975b | 1353 | if (!cred) |
f2a8d52e | 1354 | return -EINVAL; |
cde1975b EB |
1355 | |
1356 | put_user_ns(cred->user_ns); | |
1357 | set_cred_user_ns(cred, get_user_ns(user_ns)); | |
1358 | ||
905ae01c AG |
1359 | if (set_cred_ucounts(cred) < 0) |
1360 | return -EINVAL; | |
1361 | ||
f2a8d52e | 1362 | return 0; |
cde1975b EB |
1363 | } |
1364 | ||
bcac25a5 AV |
1365 | struct ns_common *ns_get_owner(struct ns_common *ns) |
1366 | { | |
1367 | struct user_namespace *my_user_ns = current_user_ns(); | |
1368 | struct user_namespace *owner, *p; | |
1369 | ||
1370 | /* See if the owner is in the current user namespace */ | |
1371 | owner = p = ns->ops->owner(ns); | |
1372 | for (;;) { | |
1373 | if (!p) | |
1374 | return ERR_PTR(-EPERM); | |
1375 | if (p == my_user_ns) | |
1376 | break; | |
1377 | p = p->parent; | |
1378 | } | |
1379 | ||
1380 | return &get_user_ns(owner)->ns; | |
1381 | } | |
1382 | ||
1383 | static struct user_namespace *userns_owner(struct ns_common *ns) | |
1384 | { | |
1385 | return to_user_ns(ns)->parent; | |
1386 | } | |
1387 | ||
cde1975b EB |
1388 | const struct proc_ns_operations userns_operations = { |
1389 | .name = "user", | |
1390 | .type = CLONE_NEWUSER, | |
1391 | .get = userns_get, | |
1392 | .put = userns_put, | |
1393 | .install = userns_install, | |
bcac25a5 | 1394 | .owner = userns_owner, |
a7306ed8 | 1395 | .get_parent = ns_get_owner, |
cde1975b EB |
1396 | }; |
1397 | ||
6164281a PE |
1398 | static __init int user_namespaces_init(void) |
1399 | { | |
30acd0bd | 1400 | user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC | SLAB_ACCOUNT); |
6164281a PE |
1401 | return 0; |
1402 | } | |
c96d6660 | 1403 | subsys_initcall(user_namespaces_init); |