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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> |
7cd4c5c2 | 12 | #include <linux/security.h> |
22d917d8 EB |
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> | |
f76d207a | 20 | #include <linux/projid.h> |
e66eded8 | 21 | #include <linux/fs_struct.h> |
6397fac4 CB |
22 | #include <linux/bsearch.h> |
23 | #include <linux/sort.h> | |
acce292c | 24 | |
68279f9c | 25 | static struct kmem_cache *user_ns_cachep __ro_after_init; |
f0d62aec | 26 | static DEFINE_MUTEX(userns_state_mutex); |
6164281a | 27 | |
6708075f EB |
28 | static bool new_idmap_permitted(const struct file *file, |
29 | struct user_namespace *ns, int cap_setid, | |
22d917d8 | 30 | struct uid_gid_map *map); |
b032132c | 31 | static void free_user_ns(struct work_struct *work); |
22d917d8 | 32 | |
25f9c081 EB |
33 | static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid) |
34 | { | |
35 | return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES); | |
36 | } | |
37 | ||
38 | static void dec_user_namespaces(struct ucounts *ucounts) | |
39 | { | |
40 | return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES); | |
41 | } | |
42 | ||
cde1975b EB |
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; | |
58319057 | 52 | cred->cap_ambient = CAP_EMPTY_SET; |
cde1975b EB |
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 | ||
0ac983f5 EB |
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 | ||
77ec739d | 74 | /* |
18b6e041 SH |
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. | |
77ec739d | 81 | */ |
18b6e041 | 82 | int create_user_ns(struct cred *new) |
77ec739d | 83 | { |
0093ccb6 | 84 | struct user_namespace *ns, *parent_ns = new->user_ns; |
078de5f7 EB |
85 | kuid_t owner = new->euid; |
86 | kgid_t group = new->egid; | |
f6b2db1a | 87 | struct ucounts *ucounts; |
25f9c081 | 88 | int ret, i; |
783291e6 | 89 | |
df75e774 | 90 | ret = -ENOSPC; |
8742f229 | 91 | if (parent_ns->level > 32) |
b376c3e1 EB |
92 | goto fail; |
93 | ||
f6b2db1a EB |
94 | ucounts = inc_user_namespaces(parent_ns, owner); |
95 | if (!ucounts) | |
b376c3e1 | 96 | goto fail; |
8742f229 | 97 | |
3151527e EB |
98 | /* |
99 | * Verify that we can not violate the policy of which files | |
100 | * may be accessed that is specified by the root directory, | |
a12f4f85 | 101 | * by verifying that the root directory is at the root of the |
3151527e EB |
102 | * mount namespace which allows all files to be accessed. |
103 | */ | |
b376c3e1 | 104 | ret = -EPERM; |
3151527e | 105 | if (current_chrooted()) |
b376c3e1 | 106 | goto fail_dec; |
3151527e | 107 | |
783291e6 EB |
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 | */ | |
b376c3e1 | 112 | ret = -EPERM; |
783291e6 EB |
113 | if (!kuid_has_mapping(parent_ns, owner) || |
114 | !kgid_has_mapping(parent_ns, group)) | |
b376c3e1 | 115 | goto fail_dec; |
77ec739d | 116 | |
7cd4c5c2 FL |
117 | ret = security_create_user_ns(new); |
118 | if (ret < 0) | |
119 | goto fail_dec; | |
120 | ||
b376c3e1 | 121 | ret = -ENOMEM; |
22d917d8 | 122 | ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL); |
77ec739d | 123 | if (!ns) |
b376c3e1 | 124 | goto fail_dec; |
77ec739d | 125 | |
db2e718a | 126 | ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP); |
6344c433 | 127 | ret = ns_alloc_inum(&ns->ns); |
b376c3e1 EB |
128 | if (ret) |
129 | goto fail_free; | |
33c42940 | 130 | ns->ns.ops = &userns_operations; |
98f842e6 | 131 | |
265cbd62 | 132 | refcount_set(&ns->ns.count, 1); |
cde1975b | 133 | /* Leave the new->user_ns reference with the new user namespace. */ |
aeb3ae9d | 134 | ns->parent = parent_ns; |
8742f229 | 135 | ns->level = parent_ns->level + 1; |
783291e6 EB |
136 | ns->owner = owner; |
137 | ns->group = group; | |
b032132c | 138 | INIT_WORK(&ns->work, free_user_ns); |
de399236 | 139 | for (i = 0; i < UCOUNT_COUNTS; i++) { |
25f9c081 EB |
140 | ns->ucount_max[i] = INT_MAX; |
141 | } | |
de399236 AG |
142 | set_userns_rlimit_max(ns, UCOUNT_RLIMIT_NPROC, enforced_nproc_rlimit()); |
143 | set_userns_rlimit_max(ns, UCOUNT_RLIMIT_MSGQUEUE, rlimit(RLIMIT_MSGQUEUE)); | |
144 | set_userns_rlimit_max(ns, UCOUNT_RLIMIT_SIGPENDING, rlimit(RLIMIT_SIGPENDING)); | |
145 | set_userns_rlimit_max(ns, UCOUNT_RLIMIT_MEMLOCK, rlimit(RLIMIT_MEMLOCK)); | |
f6b2db1a | 146 | ns->ucounts = ucounts; |
22d917d8 | 147 | |
9cc46516 EB |
148 | /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ |
149 | mutex_lock(&userns_state_mutex); | |
150 | ns->flags = parent_ns->flags; | |
151 | mutex_unlock(&userns_state_mutex); | |
152 | ||
b206f281 DH |
153 | #ifdef CONFIG_KEYS |
154 | INIT_LIST_HEAD(&ns->keyring_name_list); | |
0f44e4d9 | 155 | init_rwsem(&ns->keyring_sem); |
f36f8c75 | 156 | #endif |
dbec2846 EB |
157 | ret = -ENOMEM; |
158 | if (!setup_userns_sysctls(ns)) | |
159 | goto fail_keyring; | |
160 | ||
161 | set_cred_user_ns(new, ns); | |
18b6e041 | 162 | return 0; |
dbec2846 EB |
163 | fail_keyring: |
164 | #ifdef CONFIG_PERSISTENT_KEYRINGS | |
165 | key_put(ns->persistent_keyring_register); | |
166 | #endif | |
167 | ns_free_inum(&ns->ns); | |
b376c3e1 | 168 | fail_free: |
dbec2846 | 169 | kmem_cache_free(user_ns_cachep, ns); |
b376c3e1 | 170 | fail_dec: |
f6b2db1a | 171 | dec_user_namespaces(ucounts); |
b376c3e1 | 172 | fail: |
dbec2846 | 173 | return ret; |
acce292c CLG |
174 | } |
175 | ||
b2e0d987 EB |
176 | int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) |
177 | { | |
178 | struct cred *cred; | |
6160968c | 179 | int err = -ENOMEM; |
b2e0d987 EB |
180 | |
181 | if (!(unshare_flags & CLONE_NEWUSER)) | |
182 | return 0; | |
183 | ||
184 | cred = prepare_creds(); | |
6160968c ON |
185 | if (cred) { |
186 | err = create_user_ns(cred); | |
187 | if (err) | |
188 | put_cred(cred); | |
189 | else | |
190 | *new_cred = cred; | |
191 | } | |
b2e0d987 | 192 | |
6160968c | 193 | return err; |
b2e0d987 EB |
194 | } |
195 | ||
b032132c | 196 | static void free_user_ns(struct work_struct *work) |
acce292c | 197 | { |
b032132c EB |
198 | struct user_namespace *parent, *ns = |
199 | container_of(work, struct user_namespace, work); | |
783291e6 | 200 | |
c61a2810 | 201 | do { |
f6b2db1a | 202 | struct ucounts *ucounts = ns->ucounts; |
c61a2810 | 203 | parent = ns->parent; |
6397fac4 CB |
204 | if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
205 | kfree(ns->gid_map.forward); | |
206 | kfree(ns->gid_map.reverse); | |
207 | } | |
208 | if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { | |
209 | kfree(ns->uid_map.forward); | |
210 | kfree(ns->uid_map.reverse); | |
211 | } | |
212 | if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { | |
213 | kfree(ns->projid_map.forward); | |
214 | kfree(ns->projid_map.reverse); | |
215 | } | |
21ca59b3 CB |
216 | #if IS_ENABLED(CONFIG_BINFMT_MISC) |
217 | kfree(ns->binfmt_misc); | |
218 | #endif | |
dbec2846 | 219 | retire_userns_sysctls(ns); |
b206f281 | 220 | key_free_user_ns(ns); |
6344c433 | 221 | ns_free_inum(&ns->ns); |
c61a2810 | 222 | kmem_cache_free(user_ns_cachep, ns); |
f6b2db1a | 223 | dec_user_namespaces(ucounts); |
c61a2810 | 224 | ns = parent; |
265cbd62 | 225 | } while (refcount_dec_and_test(&parent->ns.count)); |
acce292c | 226 | } |
b032132c EB |
227 | |
228 | void __put_user_ns(struct user_namespace *ns) | |
229 | { | |
230 | schedule_work(&ns->work); | |
231 | } | |
232 | EXPORT_SYMBOL(__put_user_ns); | |
5c1469de | 233 | |
f73f6181 | 234 | /* |
e227db4d | 235 | * struct idmap_key - holds the information necessary to find an idmapping in a |
6397fac4 CB |
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 | ||
f73f6181 | 244 | /* |
6397fac4 CB |
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 | ||
11a8b927 | 254 | id2 = key->id + key->count - 1; |
6397fac4 CB |
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 | ||
f73f6181 | 274 | /* |
6397fac4 CB |
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 | */ | |
3edf652f EB |
278 | static struct uid_gid_extent * |
279 | map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) | |
5c1469de | 280 | { |
6397fac4 CB |
281 | struct idmap_key key; |
282 | ||
283 | key.map_up = false; | |
284 | key.count = count; | |
285 | key.id = id; | |
286 | ||
3edf652f EB |
287 | return bsearch(&key, map->forward, extents, |
288 | sizeof(struct uid_gid_extent), cmp_map_id); | |
6397fac4 CB |
289 | } |
290 | ||
f73f6181 | 291 | /* |
6397fac4 CB |
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 | */ | |
3edf652f EB |
296 | static struct uid_gid_extent * |
297 | map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) | |
5c1469de | 298 | { |
3edf652f | 299 | unsigned idx; |
22d917d8 | 300 | u32 first, last, id2; |
5c1469de | 301 | |
22d917d8 | 302 | id2 = id + count - 1; |
5c1469de | 303 | |
22d917d8 | 304 | /* Find the matching extent */ |
22d917d8 EB |
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)) | |
3edf652f | 310 | return &map->extent[idx]; |
22d917d8 | 311 | } |
3edf652f | 312 | return NULL; |
22d917d8 EB |
313 | } |
314 | ||
6397fac4 CB |
315 | static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count) |
316 | { | |
3edf652f EB |
317 | struct uid_gid_extent *extent; |
318 | unsigned extents = map->nr_extents; | |
6397fac4 CB |
319 | smp_rmb(); |
320 | ||
321 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
3edf652f EB |
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 | ||
22d917d8 | 326 | /* Map the id or note failure */ |
3edf652f EB |
327 | if (extent) |
328 | id = (id - extent->first) + extent->lower_first; | |
22d917d8 EB |
329 | else |
330 | id = (u32) -1; | |
331 | ||
332 | return id; | |
333 | } | |
334 | ||
783822e4 | 335 | u32 map_id_down(struct uid_gid_map *map, u32 id) |
22d917d8 | 336 | { |
ece66133 | 337 | return map_id_range_down(map, id, 1); |
6397fac4 CB |
338 | } |
339 | ||
f73f6181 | 340 | /* |
6397fac4 CB |
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 | */ | |
3edf652f EB |
345 | static struct uid_gid_extent * |
346 | map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id) | |
22d917d8 | 347 | { |
3edf652f | 348 | unsigned idx; |
22d917d8 EB |
349 | u32 first, last; |
350 | ||
351 | /* Find the matching extent */ | |
22d917d8 | 352 | for (idx = 0; idx < extents; idx++) { |
22d917d8 | 353 | first = map->extent[idx].lower_first; |
22d917d8 EB |
354 | last = first + map->extent[idx].count - 1; |
355 | if (id >= first && id <= last) | |
3edf652f | 356 | return &map->extent[idx]; |
22d917d8 | 357 | } |
3edf652f | 358 | return NULL; |
22d917d8 | 359 | } |
22d917d8 | 360 | |
f73f6181 | 361 | /* |
6397fac4 CB |
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 | */ | |
3edf652f EB |
365 | static struct uid_gid_extent * |
366 | map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id) | |
6397fac4 | 367 | { |
6397fac4 CB |
368 | struct idmap_key key; |
369 | ||
370 | key.map_up = true; | |
11a8b927 | 371 | key.count = 1; |
6397fac4 CB |
372 | key.id = id; |
373 | ||
3edf652f EB |
374 | return bsearch(&key, map->reverse, extents, |
375 | sizeof(struct uid_gid_extent), cmp_map_id); | |
22d917d8 EB |
376 | } |
377 | ||
783822e4 | 378 | u32 map_id_up(struct uid_gid_map *map, u32 id) |
22d917d8 | 379 | { |
3edf652f EB |
380 | struct uid_gid_extent *extent; |
381 | unsigned extents = map->nr_extents; | |
e79323bd | 382 | smp_rmb(); |
6397fac4 | 383 | |
3edf652f EB |
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 | ||
22d917d8 | 389 | /* Map the id or note failure */ |
6397fac4 CB |
390 | if (extent) |
391 | id = (id - extent->lower_first) + extent->first; | |
22d917d8 EB |
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 | |
b080e047 | 408 | * for and handle INVALID_UID being returned. INVALID_UID |
22d917d8 EB |
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(&targ->uid_map, __kuid_val(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 | |
68a9a435 | 469 | * @gid: group identifier |
22d917d8 EB |
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(&targ->gid_map, __kgid_val(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 | ||
f76d207a EB |
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 | |
7b7b8a2c | 543 | * for and handle INVALID_PROJID being returned. INVALID_PROJID |
f76d207a EB |
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(&targ->projid_map, __kprojid_val(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 | ||
22d917d8 EB |
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; | |
5c1469de | 608 | |
c450f371 | 609 | lower_ns = seq_user_ns(seq); |
22d917d8 EB |
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(seq, "%10u %10u %10u\n", | |
616 | extent->first, | |
617 | lower, | |
618 | extent->count); | |
619 | ||
620 | return 0; | |
5c1469de EB |
621 | } |
622 | ||
22d917d8 | 623 | static int gid_m_show(struct seq_file *seq, void *v) |
5c1469de | 624 | { |
22d917d8 EB |
625 | struct user_namespace *ns = seq->private; |
626 | struct uid_gid_extent *extent = v; | |
627 | struct user_namespace *lower_ns; | |
628 | gid_t lower; | |
5c1469de | 629 | |
c450f371 | 630 | lower_ns = seq_user_ns(seq); |
22d917d8 EB |
631 | if ((lower_ns == ns) && lower_ns->parent) |
632 | lower_ns = lower_ns->parent; | |
5c1469de | 633 | |
22d917d8 EB |
634 | lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); |
635 | ||
636 | seq_printf(seq, "%10u %10u %10u\n", | |
637 | extent->first, | |
638 | lower, | |
639 | extent->count); | |
640 | ||
641 | return 0; | |
642 | } | |
643 | ||
f76d207a EB |
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(seq, "%10u %10u %10u\n", | |
658 | extent->first, | |
659 | lower, | |
660 | extent->count); | |
661 | ||
662 | return 0; | |
663 | } | |
664 | ||
68a9a435 FF |
665 | static void *m_start(struct seq_file *seq, loff_t *ppos, |
666 | struct uid_gid_map *map) | |
22d917d8 | 667 | { |
22d917d8 | 668 | loff_t pos = *ppos; |
d5e7b3c5 EB |
669 | unsigned extents = map->nr_extents; |
670 | smp_rmb(); | |
22d917d8 | 671 | |
d5e7b3c5 | 672 | if (pos >= extents) |
6397fac4 | 673 | return NULL; |
22d917d8 | 674 | |
d5e7b3c5 | 675 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
6397fac4 | 676 | return &map->extent[pos]; |
22d917d8 | 677 | |
6397fac4 | 678 | return &map->forward[pos]; |
22d917d8 EB |
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, &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, &ns->gid_map); | |
693 | } | |
694 | ||
f76d207a EB |
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, &ns->projid_map); | |
700 | } | |
701 | ||
22d917d8 EB |
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 | ||
ccf94f1b | 713 | const struct seq_operations proc_uid_seq_operations = { |
22d917d8 EB |
714 | .start = uid_m_start, |
715 | .stop = m_stop, | |
716 | .next = m_next, | |
717 | .show = uid_m_show, | |
718 | }; | |
719 | ||
ccf94f1b | 720 | const struct seq_operations proc_gid_seq_operations = { |
22d917d8 EB |
721 | .start = gid_m_start, |
722 | .stop = m_stop, | |
723 | .next = m_next, | |
724 | .show = gid_m_show, | |
725 | }; | |
726 | ||
ccf94f1b | 727 | const struct seq_operations proc_projid_seq_operations = { |
f76d207a EB |
728 | .start = projid_m_start, |
729 | .stop = m_stop, | |
730 | .next = m_next, | |
731 | .show = projid_m_show, | |
732 | }; | |
733 | ||
68a9a435 FF |
734 | static bool mappings_overlap(struct uid_gid_map *new_map, |
735 | struct uid_gid_extent *extent) | |
0bd14b4f EB |
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 | ||
6397fac4 CB |
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]; | |
0bd14b4f EB |
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 | ||
f73f6181 | 773 | /* |
6397fac4 CB |
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 | { | |
3fda0e73 | 780 | struct uid_gid_extent *dest; |
6397fac4 CB |
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. */ | |
6da2ec56 KC |
786 | forward = kmalloc_array(UID_GID_MAP_MAX_EXTENTS, |
787 | sizeof(struct uid_gid_extent), | |
788 | GFP_KERNEL); | |
6397fac4 CB |
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 | ||
3fda0e73 EB |
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++; | |
6397fac4 CB |
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 | ||
f73f6181 | 842 | /* |
6397fac4 CB |
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(map->forward, map->nr_extents, sizeof(struct uid_gid_extent), | |
853 | cmp_extents_forward, NULL); | |
854 | ||
855 | /* Only copy the memory from forward we actually need. */ | |
856 | map->reverse = kmemdup(map->forward, | |
857 | 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(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent), | |
864 | cmp_extents_reverse, NULL); | |
865 | ||
866 | return 0; | |
867 | } | |
868 | ||
db2e718a SH |
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, map_ns->parent, CAP_SETFCAP)) | |
917 | return false; | |
918 | } | |
919 | ||
920 | return true; | |
921 | } | |
922 | ||
22d917d8 EB |
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; | |
db2e718a | 930 | struct user_namespace *map_ns = seq->private; |
22d917d8 EB |
931 | struct uid_gid_map new_map; |
932 | unsigned idx; | |
6397fac4 | 933 | struct uid_gid_extent extent; |
6db9d317 | 934 | char *kbuf, *pos, *next_line; |
5820f140 JH |
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(kbuf)) | |
944 | return PTR_ERR(kbuf); | |
22d917d8 EB |
945 | |
946 | /* | |
f0d62aec | 947 | * The userns_state_mutex serializes all writes to any given map. |
22d917d8 EB |
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 | |
e79323bd MP |
962 | * order and smp_rmb() is guaranteed that we don't have crazy |
963 | * architectures returning stale data. | |
22d917d8 | 964 | */ |
f0d62aec | 965 | mutex_lock(&userns_state_mutex); |
22d917d8 | 966 | |
6397fac4 CB |
967 | memset(&new_map, 0, sizeof(struct uid_gid_map)); |
968 | ||
22d917d8 EB |
969 | ret = -EPERM; |
970 | /* Only allow one successful write to the map */ | |
971 | if (map->nr_extents != 0) | |
972 | goto out; | |
973 | ||
41c21e35 AL |
974 | /* |
975 | * Adjusting namespace settings requires capabilities on the target. | |
5c1469de | 976 | */ |
db2e718a | 977 | if (cap_valid(cap_setid) && !file_ns_capable(file, map_ns, CAP_SYS_ADMIN)) |
22d917d8 EB |
978 | goto out; |
979 | ||
22d917d8 EB |
980 | /* Parse the user data */ |
981 | ret = -EINVAL; | |
982 | pos = kbuf; | |
68a9a435 | 983 | for (; pos; pos = next_line) { |
22d917d8 EB |
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; | |
5c1469de | 992 | } |
22d917d8 EB |
993 | |
994 | pos = skip_spaces(pos); | |
6397fac4 | 995 | extent.first = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
996 | if (!isspace(*pos)) |
997 | goto out; | |
998 | ||
999 | pos = skip_spaces(pos); | |
6397fac4 | 1000 | extent.lower_first = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
1001 | if (!isspace(*pos)) |
1002 | goto out; | |
1003 | ||
1004 | pos = skip_spaces(pos); | |
6397fac4 | 1005 | extent.count = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
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 */ | |
6397fac4 CB |
1015 | if ((extent.first == (u32) -1) || |
1016 | (extent.lower_first == (u32) -1)) | |
22d917d8 EB |
1017 | goto out; |
1018 | ||
68a9a435 FF |
1019 | /* Verify count is not zero and does not cause the |
1020 | * extent to wrap | |
1021 | */ | |
6397fac4 | 1022 | if ((extent.first + extent.count) <= extent.first) |
22d917d8 | 1023 | goto out; |
6397fac4 CB |
1024 | if ((extent.lower_first + extent.count) <= |
1025 | extent.lower_first) | |
22d917d8 EB |
1026 | goto out; |
1027 | ||
0bd14b4f | 1028 | /* Do the ranges in extent overlap any previous extents? */ |
6397fac4 | 1029 | if (mappings_overlap(&new_map, &extent)) |
22d917d8 EB |
1030 | goto out; |
1031 | ||
6397fac4 | 1032 | if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS && |
22d917d8 EB |
1033 | (next_line != NULL)) |
1034 | goto out; | |
6397fac4 CB |
1035 | |
1036 | ret = insert_extent(&new_map, &extent); | |
1037 | if (ret < 0) | |
1038 | goto out; | |
1039 | ret = -EINVAL; | |
5c1469de | 1040 | } |
a12f4f85 | 1041 | /* Be very certain the new map actually exists */ |
22d917d8 EB |
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. */ | |
db2e718a | 1047 | if (!new_idmap_permitted(file, map_ns, cap_setid, &new_map)) |
22d917d8 EB |
1048 | goto out; |
1049 | ||
6397fac4 | 1050 | ret = -EPERM; |
22d917d8 EB |
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++) { | |
6397fac4 | 1055 | struct uid_gid_extent *e; |
22d917d8 | 1056 | u32 lower_first; |
6397fac4 CB |
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]; | |
22d917d8 EB |
1062 | |
1063 | lower_first = map_id_range_down(parent_map, | |
6397fac4 CB |
1064 | e->lower_first, |
1065 | e->count); | |
22d917d8 EB |
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 | ||
6397fac4 | 1073 | e->lower_first = lower_first; |
22d917d8 EB |
1074 | } |
1075 | ||
d2f007db JH |
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(&new_map); | |
1081 | if (ret < 0) | |
1082 | goto out; | |
1083 | ||
22d917d8 | 1084 | /* Install the map */ |
6397fac4 CB |
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 | } | |
22d917d8 EB |
1092 | smp_wmb(); |
1093 | map->nr_extents = new_map.nr_extents; | |
1094 | ||
1095 | *ppos = count; | |
1096 | ret = count; | |
1097 | out: | |
6397fac4 CB |
1098 | if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
1099 | kfree(new_map.forward); | |
1100 | kfree(new_map.reverse); | |
1101 | map->forward = NULL; | |
1102 | map->reverse = NULL; | |
1103 | map->nr_extents = 0; | |
1104 | } | |
1105 | ||
f0d62aec | 1106 | mutex_unlock(&userns_state_mutex); |
70f6cbb6 | 1107 | kfree(kbuf); |
22d917d8 EB |
1108 | return ret; |
1109 | } | |
1110 | ||
68a9a435 FF |
1111 | ssize_t proc_uid_map_write(struct file *file, const char __user *buf, |
1112 | size_t size, loff_t *ppos) | |
22d917d8 EB |
1113 | { |
1114 | struct seq_file *seq = file->private_data; | |
1115 | struct user_namespace *ns = seq->private; | |
c450f371 | 1116 | struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d8 EB |
1117 | |
1118 | if (!ns->parent) | |
1119 | return -EPERM; | |
1120 | ||
c450f371 EB |
1121 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1122 | return -EPERM; | |
1123 | ||
22d917d8 EB |
1124 | return map_write(file, buf, size, ppos, CAP_SETUID, |
1125 | &ns->uid_map, &ns->parent->uid_map); | |
1126 | } | |
1127 | ||
68a9a435 FF |
1128 | ssize_t proc_gid_map_write(struct file *file, const char __user *buf, |
1129 | size_t size, loff_t *ppos) | |
22d917d8 EB |
1130 | { |
1131 | struct seq_file *seq = file->private_data; | |
1132 | struct user_namespace *ns = seq->private; | |
c450f371 | 1133 | struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d8 EB |
1134 | |
1135 | if (!ns->parent) | |
1136 | return -EPERM; | |
1137 | ||
c450f371 EB |
1138 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1139 | return -EPERM; | |
1140 | ||
22d917d8 EB |
1141 | return map_write(file, buf, size, ppos, CAP_SETGID, |
1142 | &ns->gid_map, &ns->parent->gid_map); | |
1143 | } | |
1144 | ||
68a9a435 FF |
1145 | ssize_t proc_projid_map_write(struct file *file, const char __user *buf, |
1146 | size_t size, loff_t *ppos) | |
f76d207a EB |
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, size, ppos, -1, | |
1160 | &ns->projid_map, &ns->parent->projid_map); | |
1161 | } | |
1162 | ||
68a9a435 | 1163 | static bool new_idmap_permitted(const struct file *file, |
6708075f | 1164 | struct user_namespace *ns, int cap_setid, |
22d917d8 EB |
1165 | struct uid_gid_map *new_map) |
1166 | { | |
f95d7918 | 1167 | const struct cred *cred = file->f_cred; |
db2e718a SH |
1168 | |
1169 | if (cap_setid == CAP_SETUID && !verify_root_map(file, ns, new_map)) | |
1170 | return false; | |
1171 | ||
0542f17b EB |
1172 | /* Don't allow mappings that would allow anything that wouldn't |
1173 | * be allowed without the establishment of unprivileged mappings. | |
1174 | */ | |
f95d7918 EB |
1175 | if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) && |
1176 | uid_eq(ns->owner, cred->euid)) { | |
37657da3 EB |
1177 | u32 id = new_map->extent[0].lower_first; |
1178 | if (cap_setid == CAP_SETUID) { | |
1179 | kuid_t uid = make_kuid(ns->parent, id); | |
f95d7918 | 1180 | if (uid_eq(uid, cred->euid)) |
37657da3 | 1181 | return true; |
68a9a435 | 1182 | } else if (cap_setid == CAP_SETGID) { |
37657da3 | 1183 | kgid_t gid = make_kgid(ns->parent, id); |
66d2f338 EB |
1184 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && |
1185 | gid_eq(gid, cred->egid)) | |
37657da3 EB |
1186 | return true; |
1187 | } | |
1188 | } | |
1189 | ||
f76d207a EB |
1190 | /* Allow anyone to set a mapping that doesn't require privilege */ |
1191 | if (!cap_valid(cap_setid)) | |
1192 | return true; | |
1193 | ||
22d917d8 EB |
1194 | /* Allow the specified ids if we have the appropriate capability |
1195 | * (CAP_SETUID or CAP_SETGID) over the parent user namespace. | |
a12f4f85 | 1196 | * And the opener of the id file also has the appropriate capability. |
22d917d8 | 1197 | */ |
6708075f EB |
1198 | if (ns_capable(ns->parent, cap_setid) && |
1199 | file_ns_capable(file, ns->parent, cap_setid)) | |
22d917d8 | 1200 | return true; |
5c1469de | 1201 | |
22d917d8 | 1202 | return false; |
5c1469de | 1203 | } |
6164281a | 1204 | |
9cc46516 EB |
1205 | int proc_setgroups_show(struct seq_file *seq, void *v) |
1206 | { | |
1207 | struct user_namespace *ns = seq->private; | |
6aa7de05 | 1208 | unsigned long userns_flags = READ_ONCE(ns->flags); |
9cc46516 EB |
1209 | |
1210 | seq_printf(seq, "%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(kbuf, buf, 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(&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(&userns_state_mutex); | |
1280 | goto out; | |
1281 | } | |
1282 | ||
273d2c67 EB |
1283 | bool userns_may_setgroups(const struct user_namespace *ns) |
1284 | { | |
1285 | bool allowed; | |
1286 | ||
f0d62aec | 1287 | mutex_lock(&userns_state_mutex); |
273d2c67 EB |
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; | |
9cc46516 EB |
1292 | /* Is setgroups allowed? */ |
1293 | allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED); | |
f0d62aec | 1294 | mutex_unlock(&userns_state_mutex); |
273d2c67 EB |
1295 | |
1296 | return allowed; | |
1297 | } | |
1298 | ||
d07b846f | 1299 | /* |
a2b42626 EB |
1300 | * Returns true if @child is the same namespace or a descendant of |
1301 | * @ancestor. | |
d07b846f | 1302 | */ |
a2b42626 EB |
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 | ||
d07b846f SF |
1312 | bool current_in_userns(const struct user_namespace *target_ns) |
1313 | { | |
a2b42626 | 1314 | return in_userns(target_ns, current_user_ns()); |
d07b846f | 1315 | } |
73f03c2b | 1316 | EXPORT_SYMBOL(current_in_userns); |
d07b846f | 1317 | |
3c041184 AV |
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 | ||
64964528 | 1323 | static struct ns_common *userns_get(struct task_struct *task) |
cde1975b EB |
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 | ||
3c041184 | 1331 | return user_ns ? &user_ns->ns : NULL; |
cde1975b EB |
1332 | } |
1333 | ||
64964528 | 1334 | static void userns_put(struct ns_common *ns) |
cde1975b | 1335 | { |
3c041184 | 1336 | put_user_ns(to_user_ns(ns)); |
cde1975b EB |
1337 | } |
1338 | ||
f2a8d52e | 1339 | static int userns_install(struct nsset *nsset, struct ns_common *ns) |
cde1975b | 1340 | { |
3c041184 | 1341 | struct user_namespace *user_ns = to_user_ns(ns); |
cde1975b EB |
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 | ||
faf00da5 EB |
1350 | /* Tasks that share a thread group must share a user namespace */ |
1351 | if (!thread_group_empty(current)) | |
cde1975b EB |
1352 | return -EINVAL; |
1353 | ||
e66eded8 EB |
1354 | if (current->fs->users != 1) |
1355 | return -EINVAL; | |
1356 | ||
cde1975b EB |
1357 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
1358 | return -EPERM; | |
1359 | ||
f2a8d52e | 1360 | cred = nsset_cred(nsset); |
cde1975b | 1361 | if (!cred) |
f2a8d52e | 1362 | return -EINVAL; |
cde1975b EB |
1363 | |
1364 | put_user_ns(cred->user_ns); | |
1365 | set_cred_user_ns(cred, get_user_ns(user_ns)); | |
1366 | ||
905ae01c AG |
1367 | if (set_cred_ucounts(cred) < 0) |
1368 | return -EINVAL; | |
1369 | ||
f2a8d52e | 1370 | return 0; |
cde1975b EB |
1371 | } |
1372 | ||
bcac25a5 AV |
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(-EPERM); | |
1383 | if (p == my_user_ns) | |
1384 | break; | |
1385 | p = p->parent; | |
1386 | } | |
1387 | ||
1388 | return &get_user_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 | ||
cde1975b EB |
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, | |
bcac25a5 | 1402 | .owner = userns_owner, |
a7306ed8 | 1403 | .get_parent = ns_get_owner, |
cde1975b EB |
1404 | }; |
1405 | ||
6164281a PE |
1406 | static __init int user_namespaces_init(void) |
1407 | { | |
30acd0bd | 1408 | user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC | SLAB_ACCOUNT); |
6164281a PE |
1409 | return 0; |
1410 | } | |
c96d6660 | 1411 | subsys_initcall(user_namespaces_init); |