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Commit | Line | Data |
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acce292c CLG |
1 | /* |
2 | * This program is free software; you can redistribute it and/or | |
3 | * modify it under the terms of the GNU General Public License as | |
4 | * published by the Free Software Foundation, version 2 of the | |
5 | * License. | |
6 | */ | |
7 | ||
9984de1a | 8 | #include <linux/export.h> |
acce292c | 9 | #include <linux/nsproxy.h> |
1aeb272c | 10 | #include <linux/slab.h> |
3f07c014 | 11 | #include <linux/sched/signal.h> |
acce292c | 12 | #include <linux/user_namespace.h> |
0bb80f24 | 13 | #include <linux/proc_ns.h> |
5c1469de | 14 | #include <linux/highuid.h> |
18b6e041 | 15 | #include <linux/cred.h> |
973c5914 | 16 | #include <linux/securebits.h> |
22d917d8 EB |
17 | #include <linux/keyctl.h> |
18 | #include <linux/key-type.h> | |
19 | #include <keys/user-type.h> | |
20 | #include <linux/seq_file.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/uaccess.h> | |
23 | #include <linux/ctype.h> | |
f76d207a | 24 | #include <linux/projid.h> |
e66eded8 | 25 | #include <linux/fs_struct.h> |
6397fac4 CB |
26 | #include <linux/bsearch.h> |
27 | #include <linux/sort.h> | |
acce292c | 28 | |
6164281a | 29 | static struct kmem_cache *user_ns_cachep __read_mostly; |
f0d62aec | 30 | static DEFINE_MUTEX(userns_state_mutex); |
6164281a | 31 | |
6708075f EB |
32 | static bool new_idmap_permitted(const struct file *file, |
33 | struct user_namespace *ns, int cap_setid, | |
22d917d8 | 34 | struct uid_gid_map *map); |
b032132c | 35 | static void free_user_ns(struct work_struct *work); |
22d917d8 | 36 | |
25f9c081 EB |
37 | static struct ucounts *inc_user_namespaces(struct user_namespace *ns, kuid_t uid) |
38 | { | |
39 | return inc_ucount(ns, uid, UCOUNT_USER_NAMESPACES); | |
40 | } | |
41 | ||
42 | static void dec_user_namespaces(struct ucounts *ucounts) | |
43 | { | |
44 | return dec_ucount(ucounts, UCOUNT_USER_NAMESPACES); | |
45 | } | |
46 | ||
cde1975b EB |
47 | static void set_cred_user_ns(struct cred *cred, struct user_namespace *user_ns) |
48 | { | |
49 | /* Start with the same capabilities as init but useless for doing | |
50 | * anything as the capabilities are bound to the new user namespace. | |
51 | */ | |
52 | cred->securebits = SECUREBITS_DEFAULT; | |
53 | cred->cap_inheritable = CAP_EMPTY_SET; | |
54 | cred->cap_permitted = CAP_FULL_SET; | |
55 | cred->cap_effective = CAP_FULL_SET; | |
58319057 | 56 | cred->cap_ambient = CAP_EMPTY_SET; |
cde1975b EB |
57 | cred->cap_bset = CAP_FULL_SET; |
58 | #ifdef CONFIG_KEYS | |
59 | key_put(cred->request_key_auth); | |
60 | cred->request_key_auth = NULL; | |
61 | #endif | |
62 | /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ | |
63 | cred->user_ns = user_ns; | |
64 | } | |
65 | ||
77ec739d | 66 | /* |
18b6e041 SH |
67 | * Create a new user namespace, deriving the creator from the user in the |
68 | * passed credentials, and replacing that user with the new root user for the | |
69 | * new namespace. | |
70 | * | |
71 | * This is called by copy_creds(), which will finish setting the target task's | |
72 | * credentials. | |
77ec739d | 73 | */ |
18b6e041 | 74 | int create_user_ns(struct cred *new) |
77ec739d | 75 | { |
0093ccb6 | 76 | struct user_namespace *ns, *parent_ns = new->user_ns; |
078de5f7 EB |
77 | kuid_t owner = new->euid; |
78 | kgid_t group = new->egid; | |
f6b2db1a | 79 | struct ucounts *ucounts; |
25f9c081 | 80 | int ret, i; |
783291e6 | 81 | |
df75e774 | 82 | ret = -ENOSPC; |
8742f229 | 83 | if (parent_ns->level > 32) |
b376c3e1 EB |
84 | goto fail; |
85 | ||
f6b2db1a EB |
86 | ucounts = inc_user_namespaces(parent_ns, owner); |
87 | if (!ucounts) | |
b376c3e1 | 88 | goto fail; |
8742f229 | 89 | |
3151527e EB |
90 | /* |
91 | * Verify that we can not violate the policy of which files | |
92 | * may be accessed that is specified by the root directory, | |
93 | * by verifing that the root directory is at the root of the | |
94 | * mount namespace which allows all files to be accessed. | |
95 | */ | |
b376c3e1 | 96 | ret = -EPERM; |
3151527e | 97 | if (current_chrooted()) |
b376c3e1 | 98 | goto fail_dec; |
3151527e | 99 | |
783291e6 EB |
100 | /* The creator needs a mapping in the parent user namespace |
101 | * or else we won't be able to reasonably tell userspace who | |
102 | * created a user_namespace. | |
103 | */ | |
b376c3e1 | 104 | ret = -EPERM; |
783291e6 EB |
105 | if (!kuid_has_mapping(parent_ns, owner) || |
106 | !kgid_has_mapping(parent_ns, group)) | |
b376c3e1 | 107 | goto fail_dec; |
77ec739d | 108 | |
b376c3e1 | 109 | ret = -ENOMEM; |
22d917d8 | 110 | ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL); |
77ec739d | 111 | if (!ns) |
b376c3e1 | 112 | goto fail_dec; |
77ec739d | 113 | |
6344c433 | 114 | ret = ns_alloc_inum(&ns->ns); |
b376c3e1 EB |
115 | if (ret) |
116 | goto fail_free; | |
33c42940 | 117 | ns->ns.ops = &userns_operations; |
98f842e6 | 118 | |
c61a2810 | 119 | atomic_set(&ns->count, 1); |
cde1975b | 120 | /* Leave the new->user_ns reference with the new user namespace. */ |
aeb3ae9d | 121 | ns->parent = parent_ns; |
8742f229 | 122 | ns->level = parent_ns->level + 1; |
783291e6 EB |
123 | ns->owner = owner; |
124 | ns->group = group; | |
b032132c | 125 | INIT_WORK(&ns->work, free_user_ns); |
25f9c081 EB |
126 | for (i = 0; i < UCOUNT_COUNTS; i++) { |
127 | ns->ucount_max[i] = INT_MAX; | |
128 | } | |
f6b2db1a | 129 | ns->ucounts = ucounts; |
22d917d8 | 130 | |
9cc46516 EB |
131 | /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ |
132 | mutex_lock(&userns_state_mutex); | |
133 | ns->flags = parent_ns->flags; | |
134 | mutex_unlock(&userns_state_mutex); | |
135 | ||
f36f8c75 DH |
136 | #ifdef CONFIG_PERSISTENT_KEYRINGS |
137 | init_rwsem(&ns->persistent_keyring_register_sem); | |
138 | #endif | |
dbec2846 EB |
139 | ret = -ENOMEM; |
140 | if (!setup_userns_sysctls(ns)) | |
141 | goto fail_keyring; | |
142 | ||
143 | set_cred_user_ns(new, ns); | |
18b6e041 | 144 | return 0; |
dbec2846 EB |
145 | fail_keyring: |
146 | #ifdef CONFIG_PERSISTENT_KEYRINGS | |
147 | key_put(ns->persistent_keyring_register); | |
148 | #endif | |
149 | ns_free_inum(&ns->ns); | |
b376c3e1 | 150 | fail_free: |
dbec2846 | 151 | kmem_cache_free(user_ns_cachep, ns); |
b376c3e1 | 152 | fail_dec: |
f6b2db1a | 153 | dec_user_namespaces(ucounts); |
b376c3e1 | 154 | fail: |
dbec2846 | 155 | return ret; |
acce292c CLG |
156 | } |
157 | ||
b2e0d987 EB |
158 | int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) |
159 | { | |
160 | struct cred *cred; | |
6160968c | 161 | int err = -ENOMEM; |
b2e0d987 EB |
162 | |
163 | if (!(unshare_flags & CLONE_NEWUSER)) | |
164 | return 0; | |
165 | ||
166 | cred = prepare_creds(); | |
6160968c ON |
167 | if (cred) { |
168 | err = create_user_ns(cred); | |
169 | if (err) | |
170 | put_cred(cred); | |
171 | else | |
172 | *new_cred = cred; | |
173 | } | |
b2e0d987 | 174 | |
6160968c | 175 | return err; |
b2e0d987 EB |
176 | } |
177 | ||
b032132c | 178 | static void free_user_ns(struct work_struct *work) |
acce292c | 179 | { |
b032132c EB |
180 | struct user_namespace *parent, *ns = |
181 | container_of(work, struct user_namespace, work); | |
783291e6 | 182 | |
c61a2810 | 183 | do { |
f6b2db1a | 184 | struct ucounts *ucounts = ns->ucounts; |
c61a2810 | 185 | parent = ns->parent; |
6397fac4 CB |
186 | if (ns->gid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
187 | kfree(ns->gid_map.forward); | |
188 | kfree(ns->gid_map.reverse); | |
189 | } | |
190 | if (ns->uid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { | |
191 | kfree(ns->uid_map.forward); | |
192 | kfree(ns->uid_map.reverse); | |
193 | } | |
194 | if (ns->projid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { | |
195 | kfree(ns->projid_map.forward); | |
196 | kfree(ns->projid_map.reverse); | |
197 | } | |
dbec2846 | 198 | retire_userns_sysctls(ns); |
f36f8c75 DH |
199 | #ifdef CONFIG_PERSISTENT_KEYRINGS |
200 | key_put(ns->persistent_keyring_register); | |
201 | #endif | |
6344c433 | 202 | ns_free_inum(&ns->ns); |
c61a2810 | 203 | kmem_cache_free(user_ns_cachep, ns); |
f6b2db1a | 204 | dec_user_namespaces(ucounts); |
c61a2810 EB |
205 | ns = parent; |
206 | } while (atomic_dec_and_test(&parent->count)); | |
acce292c | 207 | } |
b032132c EB |
208 | |
209 | void __put_user_ns(struct user_namespace *ns) | |
210 | { | |
211 | schedule_work(&ns->work); | |
212 | } | |
213 | EXPORT_SYMBOL(__put_user_ns); | |
5c1469de | 214 | |
6397fac4 CB |
215 | /** |
216 | * idmap_key struct holds the information necessary to find an idmapping in a | |
217 | * sorted idmap array. It is passed to cmp_map_id() as first argument. | |
218 | */ | |
219 | struct idmap_key { | |
220 | bool map_up; /* true -> id from kid; false -> kid from id */ | |
221 | u32 id; /* id to find */ | |
222 | u32 count; /* == 0 unless used with map_id_range_down() */ | |
223 | }; | |
224 | ||
225 | /** | |
226 | * cmp_map_id - Function to be passed to bsearch() to find the requested | |
227 | * idmapping. Expects struct idmap_key to be passed via @k. | |
228 | */ | |
229 | static int cmp_map_id(const void *k, const void *e) | |
230 | { | |
231 | u32 first, last, id2; | |
232 | const struct idmap_key *key = k; | |
233 | const struct uid_gid_extent *el = e; | |
234 | ||
11a8b927 | 235 | id2 = key->id + key->count - 1; |
6397fac4 CB |
236 | |
237 | /* handle map_id_{down,up}() */ | |
238 | if (key->map_up) | |
239 | first = el->lower_first; | |
240 | else | |
241 | first = el->first; | |
242 | ||
243 | last = first + el->count - 1; | |
244 | ||
245 | if (key->id >= first && key->id <= last && | |
246 | (id2 >= first && id2 <= last)) | |
247 | return 0; | |
248 | ||
249 | if (key->id < first || id2 < first) | |
250 | return -1; | |
251 | ||
252 | return 1; | |
253 | } | |
254 | ||
255 | /** | |
256 | * map_id_range_down_max - Find idmap via binary search in ordered idmap array. | |
257 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. | |
258 | */ | |
3edf652f EB |
259 | static struct uid_gid_extent * |
260 | map_id_range_down_max(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) | |
5c1469de | 261 | { |
6397fac4 CB |
262 | struct idmap_key key; |
263 | ||
264 | key.map_up = false; | |
265 | key.count = count; | |
266 | key.id = id; | |
267 | ||
3edf652f EB |
268 | return bsearch(&key, map->forward, extents, |
269 | sizeof(struct uid_gid_extent), cmp_map_id); | |
6397fac4 CB |
270 | } |
271 | ||
272 | /** | |
273 | * map_id_range_down_base - Find idmap via binary search in static extent array. | |
274 | * Can only be called if number of mappings is equal or less than | |
275 | * UID_GID_MAP_MAX_BASE_EXTENTS. | |
276 | */ | |
3edf652f EB |
277 | static struct uid_gid_extent * |
278 | map_id_range_down_base(unsigned extents, struct uid_gid_map *map, u32 id, u32 count) | |
5c1469de | 279 | { |
3edf652f | 280 | unsigned idx; |
22d917d8 | 281 | u32 first, last, id2; |
5c1469de | 282 | |
22d917d8 | 283 | id2 = id + count - 1; |
5c1469de | 284 | |
22d917d8 | 285 | /* Find the matching extent */ |
22d917d8 EB |
286 | for (idx = 0; idx < extents; idx++) { |
287 | first = map->extent[idx].first; | |
288 | last = first + map->extent[idx].count - 1; | |
289 | if (id >= first && id <= last && | |
290 | (id2 >= first && id2 <= last)) | |
3edf652f | 291 | return &map->extent[idx]; |
22d917d8 | 292 | } |
3edf652f | 293 | return NULL; |
22d917d8 EB |
294 | } |
295 | ||
6397fac4 CB |
296 | static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count) |
297 | { | |
3edf652f EB |
298 | struct uid_gid_extent *extent; |
299 | unsigned extents = map->nr_extents; | |
6397fac4 CB |
300 | smp_rmb(); |
301 | ||
302 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
3edf652f EB |
303 | extent = map_id_range_down_base(extents, map, id, count); |
304 | else | |
305 | extent = map_id_range_down_max(extents, map, id, count); | |
306 | ||
22d917d8 | 307 | /* Map the id or note failure */ |
3edf652f EB |
308 | if (extent) |
309 | id = (id - extent->first) + extent->lower_first; | |
22d917d8 EB |
310 | else |
311 | id = (u32) -1; | |
312 | ||
313 | return id; | |
314 | } | |
315 | ||
316 | static u32 map_id_down(struct uid_gid_map *map, u32 id) | |
317 | { | |
ece66133 | 318 | return map_id_range_down(map, id, 1); |
6397fac4 CB |
319 | } |
320 | ||
321 | /** | |
322 | * map_id_up_base - Find idmap via binary search in static extent array. | |
323 | * Can only be called if number of mappings is equal or less than | |
324 | * UID_GID_MAP_MAX_BASE_EXTENTS. | |
325 | */ | |
3edf652f EB |
326 | static struct uid_gid_extent * |
327 | map_id_up_base(unsigned extents, struct uid_gid_map *map, u32 id) | |
22d917d8 | 328 | { |
3edf652f | 329 | unsigned idx; |
22d917d8 EB |
330 | u32 first, last; |
331 | ||
332 | /* Find the matching extent */ | |
22d917d8 | 333 | for (idx = 0; idx < extents; idx++) { |
22d917d8 | 334 | first = map->extent[idx].lower_first; |
22d917d8 EB |
335 | last = first + map->extent[idx].count - 1; |
336 | if (id >= first && id <= last) | |
3edf652f | 337 | return &map->extent[idx]; |
22d917d8 | 338 | } |
3edf652f | 339 | return NULL; |
22d917d8 | 340 | } |
22d917d8 | 341 | |
6397fac4 CB |
342 | /** |
343 | * map_id_up_max - Find idmap via binary search in ordered idmap array. | |
344 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. | |
345 | */ | |
3edf652f EB |
346 | static struct uid_gid_extent * |
347 | map_id_up_max(unsigned extents, struct uid_gid_map *map, u32 id) | |
6397fac4 | 348 | { |
6397fac4 CB |
349 | struct idmap_key key; |
350 | ||
351 | key.map_up = true; | |
11a8b927 | 352 | key.count = 1; |
6397fac4 CB |
353 | key.id = id; |
354 | ||
3edf652f EB |
355 | return bsearch(&key, map->reverse, extents, |
356 | sizeof(struct uid_gid_extent), cmp_map_id); | |
22d917d8 EB |
357 | } |
358 | ||
359 | static u32 map_id_up(struct uid_gid_map *map, u32 id) | |
360 | { | |
3edf652f EB |
361 | struct uid_gid_extent *extent; |
362 | unsigned extents = map->nr_extents; | |
e79323bd | 363 | smp_rmb(); |
6397fac4 | 364 | |
3edf652f EB |
365 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
366 | extent = map_id_up_base(extents, map, id); | |
367 | else | |
368 | extent = map_id_up_max(extents, map, id); | |
369 | ||
22d917d8 | 370 | /* Map the id or note failure */ |
6397fac4 CB |
371 | if (extent) |
372 | id = (id - extent->lower_first) + extent->first; | |
22d917d8 EB |
373 | else |
374 | id = (u32) -1; | |
375 | ||
376 | return id; | |
377 | } | |
378 | ||
379 | /** | |
380 | * make_kuid - Map a user-namespace uid pair into a kuid. | |
381 | * @ns: User namespace that the uid is in | |
382 | * @uid: User identifier | |
383 | * | |
384 | * Maps a user-namespace uid pair into a kernel internal kuid, | |
385 | * and returns that kuid. | |
386 | * | |
387 | * When there is no mapping defined for the user-namespace uid | |
388 | * pair INVALID_UID is returned. Callers are expected to test | |
b080e047 | 389 | * for and handle INVALID_UID being returned. INVALID_UID |
22d917d8 EB |
390 | * may be tested for using uid_valid(). |
391 | */ | |
392 | kuid_t make_kuid(struct user_namespace *ns, uid_t uid) | |
393 | { | |
394 | /* Map the uid to a global kernel uid */ | |
395 | return KUIDT_INIT(map_id_down(&ns->uid_map, uid)); | |
396 | } | |
397 | EXPORT_SYMBOL(make_kuid); | |
398 | ||
399 | /** | |
400 | * from_kuid - Create a uid from a kuid user-namespace pair. | |
401 | * @targ: The user namespace we want a uid in. | |
402 | * @kuid: The kernel internal uid to start with. | |
403 | * | |
404 | * Map @kuid into the user-namespace specified by @targ and | |
405 | * return the resulting uid. | |
406 | * | |
407 | * There is always a mapping into the initial user_namespace. | |
408 | * | |
409 | * If @kuid has no mapping in @targ (uid_t)-1 is returned. | |
410 | */ | |
411 | uid_t from_kuid(struct user_namespace *targ, kuid_t kuid) | |
412 | { | |
413 | /* Map the uid from a global kernel uid */ | |
414 | return map_id_up(&targ->uid_map, __kuid_val(kuid)); | |
415 | } | |
416 | EXPORT_SYMBOL(from_kuid); | |
417 | ||
418 | /** | |
419 | * from_kuid_munged - Create a uid from a kuid user-namespace pair. | |
420 | * @targ: The user namespace we want a uid in. | |
421 | * @kuid: The kernel internal uid to start with. | |
422 | * | |
423 | * Map @kuid into the user-namespace specified by @targ and | |
424 | * return the resulting uid. | |
425 | * | |
426 | * There is always a mapping into the initial user_namespace. | |
427 | * | |
428 | * Unlike from_kuid from_kuid_munged never fails and always | |
429 | * returns a valid uid. This makes from_kuid_munged appropriate | |
430 | * for use in syscalls like stat and getuid where failing the | |
431 | * system call and failing to provide a valid uid are not an | |
432 | * options. | |
433 | * | |
434 | * If @kuid has no mapping in @targ overflowuid is returned. | |
435 | */ | |
436 | uid_t from_kuid_munged(struct user_namespace *targ, kuid_t kuid) | |
437 | { | |
438 | uid_t uid; | |
439 | uid = from_kuid(targ, kuid); | |
440 | ||
441 | if (uid == (uid_t) -1) | |
442 | uid = overflowuid; | |
443 | return uid; | |
444 | } | |
445 | EXPORT_SYMBOL(from_kuid_munged); | |
446 | ||
447 | /** | |
448 | * make_kgid - Map a user-namespace gid pair into a kgid. | |
449 | * @ns: User namespace that the gid is in | |
68a9a435 | 450 | * @gid: group identifier |
22d917d8 EB |
451 | * |
452 | * Maps a user-namespace gid pair into a kernel internal kgid, | |
453 | * and returns that kgid. | |
454 | * | |
455 | * When there is no mapping defined for the user-namespace gid | |
456 | * pair INVALID_GID is returned. Callers are expected to test | |
457 | * for and handle INVALID_GID being returned. INVALID_GID may be | |
458 | * tested for using gid_valid(). | |
459 | */ | |
460 | kgid_t make_kgid(struct user_namespace *ns, gid_t gid) | |
461 | { | |
462 | /* Map the gid to a global kernel gid */ | |
463 | return KGIDT_INIT(map_id_down(&ns->gid_map, gid)); | |
464 | } | |
465 | EXPORT_SYMBOL(make_kgid); | |
466 | ||
467 | /** | |
468 | * from_kgid - Create a gid from a kgid user-namespace pair. | |
469 | * @targ: The user namespace we want a gid in. | |
470 | * @kgid: The kernel internal gid to start with. | |
471 | * | |
472 | * Map @kgid into the user-namespace specified by @targ and | |
473 | * return the resulting gid. | |
474 | * | |
475 | * There is always a mapping into the initial user_namespace. | |
476 | * | |
477 | * If @kgid has no mapping in @targ (gid_t)-1 is returned. | |
478 | */ | |
479 | gid_t from_kgid(struct user_namespace *targ, kgid_t kgid) | |
480 | { | |
481 | /* Map the gid from a global kernel gid */ | |
482 | return map_id_up(&targ->gid_map, __kgid_val(kgid)); | |
483 | } | |
484 | EXPORT_SYMBOL(from_kgid); | |
485 | ||
486 | /** | |
487 | * from_kgid_munged - Create a gid from a kgid user-namespace pair. | |
488 | * @targ: The user namespace we want a gid in. | |
489 | * @kgid: The kernel internal gid to start with. | |
490 | * | |
491 | * Map @kgid into the user-namespace specified by @targ and | |
492 | * return the resulting gid. | |
493 | * | |
494 | * There is always a mapping into the initial user_namespace. | |
495 | * | |
496 | * Unlike from_kgid from_kgid_munged never fails and always | |
497 | * returns a valid gid. This makes from_kgid_munged appropriate | |
498 | * for use in syscalls like stat and getgid where failing the | |
499 | * system call and failing to provide a valid gid are not options. | |
500 | * | |
501 | * If @kgid has no mapping in @targ overflowgid is returned. | |
502 | */ | |
503 | gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid) | |
504 | { | |
505 | gid_t gid; | |
506 | gid = from_kgid(targ, kgid); | |
507 | ||
508 | if (gid == (gid_t) -1) | |
509 | gid = overflowgid; | |
510 | return gid; | |
511 | } | |
512 | EXPORT_SYMBOL(from_kgid_munged); | |
513 | ||
f76d207a EB |
514 | /** |
515 | * make_kprojid - Map a user-namespace projid pair into a kprojid. | |
516 | * @ns: User namespace that the projid is in | |
517 | * @projid: Project identifier | |
518 | * | |
519 | * Maps a user-namespace uid pair into a kernel internal kuid, | |
520 | * and returns that kuid. | |
521 | * | |
522 | * When there is no mapping defined for the user-namespace projid | |
523 | * pair INVALID_PROJID is returned. Callers are expected to test | |
524 | * for and handle handle INVALID_PROJID being returned. INVALID_PROJID | |
525 | * may be tested for using projid_valid(). | |
526 | */ | |
527 | kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid) | |
528 | { | |
529 | /* Map the uid to a global kernel uid */ | |
530 | return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid)); | |
531 | } | |
532 | EXPORT_SYMBOL(make_kprojid); | |
533 | ||
534 | /** | |
535 | * from_kprojid - Create a projid from a kprojid user-namespace pair. | |
536 | * @targ: The user namespace we want a projid in. | |
537 | * @kprojid: The kernel internal project identifier to start with. | |
538 | * | |
539 | * Map @kprojid into the user-namespace specified by @targ and | |
540 | * return the resulting projid. | |
541 | * | |
542 | * There is always a mapping into the initial user_namespace. | |
543 | * | |
544 | * If @kprojid has no mapping in @targ (projid_t)-1 is returned. | |
545 | */ | |
546 | projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid) | |
547 | { | |
548 | /* Map the uid from a global kernel uid */ | |
549 | return map_id_up(&targ->projid_map, __kprojid_val(kprojid)); | |
550 | } | |
551 | EXPORT_SYMBOL(from_kprojid); | |
552 | ||
553 | /** | |
554 | * from_kprojid_munged - Create a projiid from a kprojid user-namespace pair. | |
555 | * @targ: The user namespace we want a projid in. | |
556 | * @kprojid: The kernel internal projid to start with. | |
557 | * | |
558 | * Map @kprojid into the user-namespace specified by @targ and | |
559 | * return the resulting projid. | |
560 | * | |
561 | * There is always a mapping into the initial user_namespace. | |
562 | * | |
563 | * Unlike from_kprojid from_kprojid_munged never fails and always | |
564 | * returns a valid projid. This makes from_kprojid_munged | |
565 | * appropriate for use in syscalls like stat and where | |
566 | * failing the system call and failing to provide a valid projid are | |
567 | * not an options. | |
568 | * | |
569 | * If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned. | |
570 | */ | |
571 | projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid) | |
572 | { | |
573 | projid_t projid; | |
574 | projid = from_kprojid(targ, kprojid); | |
575 | ||
576 | if (projid == (projid_t) -1) | |
577 | projid = OVERFLOW_PROJID; | |
578 | return projid; | |
579 | } | |
580 | EXPORT_SYMBOL(from_kprojid_munged); | |
581 | ||
582 | ||
22d917d8 EB |
583 | static int uid_m_show(struct seq_file *seq, void *v) |
584 | { | |
585 | struct user_namespace *ns = seq->private; | |
586 | struct uid_gid_extent *extent = v; | |
587 | struct user_namespace *lower_ns; | |
588 | uid_t lower; | |
5c1469de | 589 | |
c450f371 | 590 | lower_ns = seq_user_ns(seq); |
22d917d8 EB |
591 | if ((lower_ns == ns) && lower_ns->parent) |
592 | lower_ns = lower_ns->parent; | |
593 | ||
594 | lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first)); | |
595 | ||
596 | seq_printf(seq, "%10u %10u %10u\n", | |
597 | extent->first, | |
598 | lower, | |
599 | extent->count); | |
600 | ||
601 | return 0; | |
5c1469de EB |
602 | } |
603 | ||
22d917d8 | 604 | static int gid_m_show(struct seq_file *seq, void *v) |
5c1469de | 605 | { |
22d917d8 EB |
606 | struct user_namespace *ns = seq->private; |
607 | struct uid_gid_extent *extent = v; | |
608 | struct user_namespace *lower_ns; | |
609 | gid_t lower; | |
5c1469de | 610 | |
c450f371 | 611 | lower_ns = seq_user_ns(seq); |
22d917d8 EB |
612 | if ((lower_ns == ns) && lower_ns->parent) |
613 | lower_ns = lower_ns->parent; | |
5c1469de | 614 | |
22d917d8 EB |
615 | lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); |
616 | ||
617 | seq_printf(seq, "%10u %10u %10u\n", | |
618 | extent->first, | |
619 | lower, | |
620 | extent->count); | |
621 | ||
622 | return 0; | |
623 | } | |
624 | ||
f76d207a EB |
625 | static int projid_m_show(struct seq_file *seq, void *v) |
626 | { | |
627 | struct user_namespace *ns = seq->private; | |
628 | struct uid_gid_extent *extent = v; | |
629 | struct user_namespace *lower_ns; | |
630 | projid_t lower; | |
631 | ||
632 | lower_ns = seq_user_ns(seq); | |
633 | if ((lower_ns == ns) && lower_ns->parent) | |
634 | lower_ns = lower_ns->parent; | |
635 | ||
636 | lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first)); | |
637 | ||
638 | seq_printf(seq, "%10u %10u %10u\n", | |
639 | extent->first, | |
640 | lower, | |
641 | extent->count); | |
642 | ||
643 | return 0; | |
644 | } | |
645 | ||
68a9a435 FF |
646 | static void *m_start(struct seq_file *seq, loff_t *ppos, |
647 | struct uid_gid_map *map) | |
22d917d8 | 648 | { |
22d917d8 | 649 | loff_t pos = *ppos; |
d5e7b3c5 EB |
650 | unsigned extents = map->nr_extents; |
651 | smp_rmb(); | |
22d917d8 | 652 | |
d5e7b3c5 | 653 | if (pos >= extents) |
6397fac4 | 654 | return NULL; |
22d917d8 | 655 | |
d5e7b3c5 | 656 | if (extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
6397fac4 | 657 | return &map->extent[pos]; |
22d917d8 | 658 | |
6397fac4 | 659 | return &map->forward[pos]; |
22d917d8 EB |
660 | } |
661 | ||
662 | static void *uid_m_start(struct seq_file *seq, loff_t *ppos) | |
663 | { | |
664 | struct user_namespace *ns = seq->private; | |
665 | ||
666 | return m_start(seq, ppos, &ns->uid_map); | |
667 | } | |
668 | ||
669 | static void *gid_m_start(struct seq_file *seq, loff_t *ppos) | |
670 | { | |
671 | struct user_namespace *ns = seq->private; | |
672 | ||
673 | return m_start(seq, ppos, &ns->gid_map); | |
674 | } | |
675 | ||
f76d207a EB |
676 | static void *projid_m_start(struct seq_file *seq, loff_t *ppos) |
677 | { | |
678 | struct user_namespace *ns = seq->private; | |
679 | ||
680 | return m_start(seq, ppos, &ns->projid_map); | |
681 | } | |
682 | ||
22d917d8 EB |
683 | static void *m_next(struct seq_file *seq, void *v, loff_t *pos) |
684 | { | |
685 | (*pos)++; | |
686 | return seq->op->start(seq, pos); | |
687 | } | |
688 | ||
689 | static void m_stop(struct seq_file *seq, void *v) | |
690 | { | |
691 | return; | |
692 | } | |
693 | ||
ccf94f1b | 694 | const struct seq_operations proc_uid_seq_operations = { |
22d917d8 EB |
695 | .start = uid_m_start, |
696 | .stop = m_stop, | |
697 | .next = m_next, | |
698 | .show = uid_m_show, | |
699 | }; | |
700 | ||
ccf94f1b | 701 | const struct seq_operations proc_gid_seq_operations = { |
22d917d8 EB |
702 | .start = gid_m_start, |
703 | .stop = m_stop, | |
704 | .next = m_next, | |
705 | .show = gid_m_show, | |
706 | }; | |
707 | ||
ccf94f1b | 708 | const struct seq_operations proc_projid_seq_operations = { |
f76d207a EB |
709 | .start = projid_m_start, |
710 | .stop = m_stop, | |
711 | .next = m_next, | |
712 | .show = projid_m_show, | |
713 | }; | |
714 | ||
68a9a435 FF |
715 | static bool mappings_overlap(struct uid_gid_map *new_map, |
716 | struct uid_gid_extent *extent) | |
0bd14b4f EB |
717 | { |
718 | u32 upper_first, lower_first, upper_last, lower_last; | |
719 | unsigned idx; | |
720 | ||
721 | upper_first = extent->first; | |
722 | lower_first = extent->lower_first; | |
723 | upper_last = upper_first + extent->count - 1; | |
724 | lower_last = lower_first + extent->count - 1; | |
725 | ||
726 | for (idx = 0; idx < new_map->nr_extents; idx++) { | |
727 | u32 prev_upper_first, prev_lower_first; | |
728 | u32 prev_upper_last, prev_lower_last; | |
729 | struct uid_gid_extent *prev; | |
730 | ||
6397fac4 CB |
731 | if (new_map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) |
732 | prev = &new_map->extent[idx]; | |
733 | else | |
734 | prev = &new_map->forward[idx]; | |
0bd14b4f EB |
735 | |
736 | prev_upper_first = prev->first; | |
737 | prev_lower_first = prev->lower_first; | |
738 | prev_upper_last = prev_upper_first + prev->count - 1; | |
739 | prev_lower_last = prev_lower_first + prev->count - 1; | |
740 | ||
741 | /* Does the upper range intersect a previous extent? */ | |
742 | if ((prev_upper_first <= upper_last) && | |
743 | (prev_upper_last >= upper_first)) | |
744 | return true; | |
745 | ||
746 | /* Does the lower range intersect a previous extent? */ | |
747 | if ((prev_lower_first <= lower_last) && | |
748 | (prev_lower_last >= lower_first)) | |
749 | return true; | |
750 | } | |
751 | return false; | |
752 | } | |
753 | ||
6397fac4 CB |
754 | /** |
755 | * insert_extent - Safely insert a new idmap extent into struct uid_gid_map. | |
756 | * Takes care to allocate a 4K block of memory if the number of mappings exceeds | |
757 | * UID_GID_MAP_MAX_BASE_EXTENTS. | |
758 | */ | |
759 | static int insert_extent(struct uid_gid_map *map, struct uid_gid_extent *extent) | |
760 | { | |
3fda0e73 | 761 | struct uid_gid_extent *dest; |
6397fac4 CB |
762 | |
763 | if (map->nr_extents == UID_GID_MAP_MAX_BASE_EXTENTS) { | |
764 | struct uid_gid_extent *forward; | |
765 | ||
766 | /* Allocate memory for 340 mappings. */ | |
767 | forward = kmalloc(sizeof(struct uid_gid_extent) * | |
768 | UID_GID_MAP_MAX_EXTENTS, GFP_KERNEL); | |
769 | if (!forward) | |
770 | return -ENOMEM; | |
771 | ||
772 | /* Copy over memory. Only set up memory for the forward pointer. | |
773 | * Defer the memory setup for the reverse pointer. | |
774 | */ | |
775 | memcpy(forward, map->extent, | |
776 | map->nr_extents * sizeof(map->extent[0])); | |
777 | ||
778 | map->forward = forward; | |
779 | map->reverse = NULL; | |
780 | } | |
781 | ||
3fda0e73 EB |
782 | if (map->nr_extents < UID_GID_MAP_MAX_BASE_EXTENTS) |
783 | dest = &map->extent[map->nr_extents]; | |
784 | else | |
785 | dest = &map->forward[map->nr_extents]; | |
786 | ||
787 | *dest = *extent; | |
788 | map->nr_extents++; | |
6397fac4 CB |
789 | return 0; |
790 | } | |
791 | ||
792 | /* cmp function to sort() forward mappings */ | |
793 | static int cmp_extents_forward(const void *a, const void *b) | |
794 | { | |
795 | const struct uid_gid_extent *e1 = a; | |
796 | const struct uid_gid_extent *e2 = b; | |
797 | ||
798 | if (e1->first < e2->first) | |
799 | return -1; | |
800 | ||
801 | if (e1->first > e2->first) | |
802 | return 1; | |
803 | ||
804 | return 0; | |
805 | } | |
806 | ||
807 | /* cmp function to sort() reverse mappings */ | |
808 | static int cmp_extents_reverse(const void *a, const void *b) | |
809 | { | |
810 | const struct uid_gid_extent *e1 = a; | |
811 | const struct uid_gid_extent *e2 = b; | |
812 | ||
813 | if (e1->lower_first < e2->lower_first) | |
814 | return -1; | |
815 | ||
816 | if (e1->lower_first > e2->lower_first) | |
817 | return 1; | |
818 | ||
819 | return 0; | |
820 | } | |
821 | ||
822 | /** | |
823 | * sort_idmaps - Sorts an array of idmap entries. | |
824 | * Can only be called if number of mappings exceeds UID_GID_MAP_MAX_BASE_EXTENTS. | |
825 | */ | |
826 | static int sort_idmaps(struct uid_gid_map *map) | |
827 | { | |
828 | if (map->nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
829 | return 0; | |
830 | ||
831 | /* Sort forward array. */ | |
832 | sort(map->forward, map->nr_extents, sizeof(struct uid_gid_extent), | |
833 | cmp_extents_forward, NULL); | |
834 | ||
835 | /* Only copy the memory from forward we actually need. */ | |
836 | map->reverse = kmemdup(map->forward, | |
837 | map->nr_extents * sizeof(struct uid_gid_extent), | |
838 | GFP_KERNEL); | |
839 | if (!map->reverse) | |
840 | return -ENOMEM; | |
841 | ||
842 | /* Sort reverse array. */ | |
843 | sort(map->reverse, map->nr_extents, sizeof(struct uid_gid_extent), | |
844 | cmp_extents_reverse, NULL); | |
845 | ||
846 | return 0; | |
847 | } | |
848 | ||
22d917d8 EB |
849 | static ssize_t map_write(struct file *file, const char __user *buf, |
850 | size_t count, loff_t *ppos, | |
851 | int cap_setid, | |
852 | struct uid_gid_map *map, | |
853 | struct uid_gid_map *parent_map) | |
854 | { | |
855 | struct seq_file *seq = file->private_data; | |
856 | struct user_namespace *ns = seq->private; | |
857 | struct uid_gid_map new_map; | |
858 | unsigned idx; | |
6397fac4 | 859 | struct uid_gid_extent extent; |
70f6cbb6 | 860 | char *kbuf = NULL, *pos, *next_line; |
22d917d8 EB |
861 | ssize_t ret = -EINVAL; |
862 | ||
863 | /* | |
f0d62aec | 864 | * The userns_state_mutex serializes all writes to any given map. |
22d917d8 EB |
865 | * |
866 | * Any map is only ever written once. | |
867 | * | |
868 | * An id map fits within 1 cache line on most architectures. | |
869 | * | |
870 | * On read nothing needs to be done unless you are on an | |
871 | * architecture with a crazy cache coherency model like alpha. | |
872 | * | |
873 | * There is a one time data dependency between reading the | |
874 | * count of the extents and the values of the extents. The | |
875 | * desired behavior is to see the values of the extents that | |
876 | * were written before the count of the extents. | |
877 | * | |
878 | * To achieve this smp_wmb() is used on guarantee the write | |
e79323bd MP |
879 | * order and smp_rmb() is guaranteed that we don't have crazy |
880 | * architectures returning stale data. | |
22d917d8 | 881 | */ |
f0d62aec | 882 | mutex_lock(&userns_state_mutex); |
22d917d8 | 883 | |
6397fac4 CB |
884 | memset(&new_map, 0, sizeof(struct uid_gid_map)); |
885 | ||
22d917d8 EB |
886 | ret = -EPERM; |
887 | /* Only allow one successful write to the map */ | |
888 | if (map->nr_extents != 0) | |
889 | goto out; | |
890 | ||
41c21e35 AL |
891 | /* |
892 | * Adjusting namespace settings requires capabilities on the target. | |
5c1469de | 893 | */ |
41c21e35 | 894 | if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN)) |
22d917d8 EB |
895 | goto out; |
896 | ||
36476bea | 897 | /* Only allow < page size writes at the beginning of the file */ |
22d917d8 EB |
898 | ret = -EINVAL; |
899 | if ((*ppos != 0) || (count >= PAGE_SIZE)) | |
900 | goto out; | |
901 | ||
902 | /* Slurp in the user data */ | |
70f6cbb6 AV |
903 | kbuf = memdup_user_nul(buf, count); |
904 | if (IS_ERR(kbuf)) { | |
905 | ret = PTR_ERR(kbuf); | |
906 | kbuf = NULL; | |
22d917d8 | 907 | goto out; |
70f6cbb6 | 908 | } |
22d917d8 EB |
909 | |
910 | /* Parse the user data */ | |
911 | ret = -EINVAL; | |
912 | pos = kbuf; | |
68a9a435 | 913 | for (; pos; pos = next_line) { |
22d917d8 EB |
914 | |
915 | /* Find the end of line and ensure I don't look past it */ | |
916 | next_line = strchr(pos, '\n'); | |
917 | if (next_line) { | |
918 | *next_line = '\0'; | |
919 | next_line++; | |
920 | if (*next_line == '\0') | |
921 | next_line = NULL; | |
5c1469de | 922 | } |
22d917d8 EB |
923 | |
924 | pos = skip_spaces(pos); | |
6397fac4 | 925 | extent.first = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
926 | if (!isspace(*pos)) |
927 | goto out; | |
928 | ||
929 | pos = skip_spaces(pos); | |
6397fac4 | 930 | extent.lower_first = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
931 | if (!isspace(*pos)) |
932 | goto out; | |
933 | ||
934 | pos = skip_spaces(pos); | |
6397fac4 | 935 | extent.count = simple_strtoul(pos, &pos, 10); |
22d917d8 EB |
936 | if (*pos && !isspace(*pos)) |
937 | goto out; | |
938 | ||
939 | /* Verify there is not trailing junk on the line */ | |
940 | pos = skip_spaces(pos); | |
941 | if (*pos != '\0') | |
942 | goto out; | |
943 | ||
944 | /* Verify we have been given valid starting values */ | |
6397fac4 CB |
945 | if ((extent.first == (u32) -1) || |
946 | (extent.lower_first == (u32) -1)) | |
22d917d8 EB |
947 | goto out; |
948 | ||
68a9a435 FF |
949 | /* Verify count is not zero and does not cause the |
950 | * extent to wrap | |
951 | */ | |
6397fac4 | 952 | if ((extent.first + extent.count) <= extent.first) |
22d917d8 | 953 | goto out; |
6397fac4 CB |
954 | if ((extent.lower_first + extent.count) <= |
955 | extent.lower_first) | |
22d917d8 EB |
956 | goto out; |
957 | ||
0bd14b4f | 958 | /* Do the ranges in extent overlap any previous extents? */ |
6397fac4 | 959 | if (mappings_overlap(&new_map, &extent)) |
22d917d8 EB |
960 | goto out; |
961 | ||
6397fac4 | 962 | if ((new_map.nr_extents + 1) == UID_GID_MAP_MAX_EXTENTS && |
22d917d8 EB |
963 | (next_line != NULL)) |
964 | goto out; | |
6397fac4 CB |
965 | |
966 | ret = insert_extent(&new_map, &extent); | |
967 | if (ret < 0) | |
968 | goto out; | |
969 | ret = -EINVAL; | |
5c1469de | 970 | } |
22d917d8 EB |
971 | /* Be very certaint the new map actually exists */ |
972 | if (new_map.nr_extents == 0) | |
973 | goto out; | |
974 | ||
975 | ret = -EPERM; | |
976 | /* Validate the user is allowed to use user id's mapped to. */ | |
6708075f | 977 | if (!new_idmap_permitted(file, ns, cap_setid, &new_map)) |
22d917d8 EB |
978 | goto out; |
979 | ||
6397fac4 CB |
980 | ret = sort_idmaps(&new_map); |
981 | if (ret < 0) | |
982 | goto out; | |
983 | ||
984 | ret = -EPERM; | |
22d917d8 EB |
985 | /* Map the lower ids from the parent user namespace to the |
986 | * kernel global id space. | |
987 | */ | |
988 | for (idx = 0; idx < new_map.nr_extents; idx++) { | |
6397fac4 | 989 | struct uid_gid_extent *e; |
22d917d8 | 990 | u32 lower_first; |
6397fac4 CB |
991 | |
992 | if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) | |
993 | e = &new_map.extent[idx]; | |
994 | else | |
995 | e = &new_map.forward[idx]; | |
22d917d8 EB |
996 | |
997 | lower_first = map_id_range_down(parent_map, | |
6397fac4 CB |
998 | e->lower_first, |
999 | e->count); | |
22d917d8 EB |
1000 | |
1001 | /* Fail if we can not map the specified extent to | |
1002 | * the kernel global id space. | |
1003 | */ | |
1004 | if (lower_first == (u32) -1) | |
1005 | goto out; | |
1006 | ||
6397fac4 | 1007 | e->lower_first = lower_first; |
22d917d8 EB |
1008 | } |
1009 | ||
1010 | /* Install the map */ | |
6397fac4 CB |
1011 | if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) { |
1012 | memcpy(map->extent, new_map.extent, | |
1013 | new_map.nr_extents * sizeof(new_map.extent[0])); | |
1014 | } else { | |
1015 | map->forward = new_map.forward; | |
1016 | map->reverse = new_map.reverse; | |
1017 | } | |
22d917d8 EB |
1018 | smp_wmb(); |
1019 | map->nr_extents = new_map.nr_extents; | |
1020 | ||
1021 | *ppos = count; | |
1022 | ret = count; | |
1023 | out: | |
6397fac4 CB |
1024 | if (ret < 0 && new_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { |
1025 | kfree(new_map.forward); | |
1026 | kfree(new_map.reverse); | |
1027 | map->forward = NULL; | |
1028 | map->reverse = NULL; | |
1029 | map->nr_extents = 0; | |
1030 | } | |
1031 | ||
f0d62aec | 1032 | mutex_unlock(&userns_state_mutex); |
70f6cbb6 | 1033 | kfree(kbuf); |
22d917d8 EB |
1034 | return ret; |
1035 | } | |
1036 | ||
68a9a435 FF |
1037 | ssize_t proc_uid_map_write(struct file *file, const char __user *buf, |
1038 | size_t size, loff_t *ppos) | |
22d917d8 EB |
1039 | { |
1040 | struct seq_file *seq = file->private_data; | |
1041 | struct user_namespace *ns = seq->private; | |
c450f371 | 1042 | struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d8 EB |
1043 | |
1044 | if (!ns->parent) | |
1045 | return -EPERM; | |
1046 | ||
c450f371 EB |
1047 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1048 | return -EPERM; | |
1049 | ||
22d917d8 EB |
1050 | return map_write(file, buf, size, ppos, CAP_SETUID, |
1051 | &ns->uid_map, &ns->parent->uid_map); | |
1052 | } | |
1053 | ||
68a9a435 FF |
1054 | ssize_t proc_gid_map_write(struct file *file, const char __user *buf, |
1055 | size_t size, loff_t *ppos) | |
22d917d8 EB |
1056 | { |
1057 | struct seq_file *seq = file->private_data; | |
1058 | struct user_namespace *ns = seq->private; | |
c450f371 | 1059 | struct user_namespace *seq_ns = seq_user_ns(seq); |
22d917d8 EB |
1060 | |
1061 | if (!ns->parent) | |
1062 | return -EPERM; | |
1063 | ||
c450f371 EB |
1064 | if ((seq_ns != ns) && (seq_ns != ns->parent)) |
1065 | return -EPERM; | |
1066 | ||
22d917d8 EB |
1067 | return map_write(file, buf, size, ppos, CAP_SETGID, |
1068 | &ns->gid_map, &ns->parent->gid_map); | |
1069 | } | |
1070 | ||
68a9a435 FF |
1071 | ssize_t proc_projid_map_write(struct file *file, const char __user *buf, |
1072 | size_t size, loff_t *ppos) | |
f76d207a EB |
1073 | { |
1074 | struct seq_file *seq = file->private_data; | |
1075 | struct user_namespace *ns = seq->private; | |
1076 | struct user_namespace *seq_ns = seq_user_ns(seq); | |
1077 | ||
1078 | if (!ns->parent) | |
1079 | return -EPERM; | |
1080 | ||
1081 | if ((seq_ns != ns) && (seq_ns != ns->parent)) | |
1082 | return -EPERM; | |
1083 | ||
1084 | /* Anyone can set any valid project id no capability needed */ | |
1085 | return map_write(file, buf, size, ppos, -1, | |
1086 | &ns->projid_map, &ns->parent->projid_map); | |
1087 | } | |
1088 | ||
68a9a435 | 1089 | static bool new_idmap_permitted(const struct file *file, |
6708075f | 1090 | struct user_namespace *ns, int cap_setid, |
22d917d8 EB |
1091 | struct uid_gid_map *new_map) |
1092 | { | |
f95d7918 | 1093 | const struct cred *cred = file->f_cred; |
0542f17b EB |
1094 | /* Don't allow mappings that would allow anything that wouldn't |
1095 | * be allowed without the establishment of unprivileged mappings. | |
1096 | */ | |
f95d7918 EB |
1097 | if ((new_map->nr_extents == 1) && (new_map->extent[0].count == 1) && |
1098 | uid_eq(ns->owner, cred->euid)) { | |
37657da3 EB |
1099 | u32 id = new_map->extent[0].lower_first; |
1100 | if (cap_setid == CAP_SETUID) { | |
1101 | kuid_t uid = make_kuid(ns->parent, id); | |
f95d7918 | 1102 | if (uid_eq(uid, cred->euid)) |
37657da3 | 1103 | return true; |
68a9a435 | 1104 | } else if (cap_setid == CAP_SETGID) { |
37657da3 | 1105 | kgid_t gid = make_kgid(ns->parent, id); |
66d2f338 EB |
1106 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && |
1107 | gid_eq(gid, cred->egid)) | |
37657da3 EB |
1108 | return true; |
1109 | } | |
1110 | } | |
1111 | ||
f76d207a EB |
1112 | /* Allow anyone to set a mapping that doesn't require privilege */ |
1113 | if (!cap_valid(cap_setid)) | |
1114 | return true; | |
1115 | ||
22d917d8 EB |
1116 | /* Allow the specified ids if we have the appropriate capability |
1117 | * (CAP_SETUID or CAP_SETGID) over the parent user namespace. | |
6708075f | 1118 | * And the opener of the id file also had the approprpiate capability. |
22d917d8 | 1119 | */ |
6708075f EB |
1120 | if (ns_capable(ns->parent, cap_setid) && |
1121 | file_ns_capable(file, ns->parent, cap_setid)) | |
22d917d8 | 1122 | return true; |
5c1469de | 1123 | |
22d917d8 | 1124 | return false; |
5c1469de | 1125 | } |
6164281a | 1126 | |
9cc46516 EB |
1127 | int proc_setgroups_show(struct seq_file *seq, void *v) |
1128 | { | |
1129 | struct user_namespace *ns = seq->private; | |
6aa7de05 | 1130 | unsigned long userns_flags = READ_ONCE(ns->flags); |
9cc46516 EB |
1131 | |
1132 | seq_printf(seq, "%s\n", | |
1133 | (userns_flags & USERNS_SETGROUPS_ALLOWED) ? | |
1134 | "allow" : "deny"); | |
1135 | return 0; | |
1136 | } | |
1137 | ||
1138 | ssize_t proc_setgroups_write(struct file *file, const char __user *buf, | |
1139 | size_t count, loff_t *ppos) | |
1140 | { | |
1141 | struct seq_file *seq = file->private_data; | |
1142 | struct user_namespace *ns = seq->private; | |
1143 | char kbuf[8], *pos; | |
1144 | bool setgroups_allowed; | |
1145 | ssize_t ret; | |
1146 | ||
1147 | /* Only allow a very narrow range of strings to be written */ | |
1148 | ret = -EINVAL; | |
1149 | if ((*ppos != 0) || (count >= sizeof(kbuf))) | |
1150 | goto out; | |
1151 | ||
1152 | /* What was written? */ | |
1153 | ret = -EFAULT; | |
1154 | if (copy_from_user(kbuf, buf, count)) | |
1155 | goto out; | |
1156 | kbuf[count] = '\0'; | |
1157 | pos = kbuf; | |
1158 | ||
1159 | /* What is being requested? */ | |
1160 | ret = -EINVAL; | |
1161 | if (strncmp(pos, "allow", 5) == 0) { | |
1162 | pos += 5; | |
1163 | setgroups_allowed = true; | |
1164 | } | |
1165 | else if (strncmp(pos, "deny", 4) == 0) { | |
1166 | pos += 4; | |
1167 | setgroups_allowed = false; | |
1168 | } | |
1169 | else | |
1170 | goto out; | |
1171 | ||
1172 | /* Verify there is not trailing junk on the line */ | |
1173 | pos = skip_spaces(pos); | |
1174 | if (*pos != '\0') | |
1175 | goto out; | |
1176 | ||
1177 | ret = -EPERM; | |
1178 | mutex_lock(&userns_state_mutex); | |
1179 | if (setgroups_allowed) { | |
1180 | /* Enabling setgroups after setgroups has been disabled | |
1181 | * is not allowed. | |
1182 | */ | |
1183 | if (!(ns->flags & USERNS_SETGROUPS_ALLOWED)) | |
1184 | goto out_unlock; | |
1185 | } else { | |
1186 | /* Permanently disabling setgroups after setgroups has | |
1187 | * been enabled by writing the gid_map is not allowed. | |
1188 | */ | |
1189 | if (ns->gid_map.nr_extents != 0) | |
1190 | goto out_unlock; | |
1191 | ns->flags &= ~USERNS_SETGROUPS_ALLOWED; | |
1192 | } | |
1193 | mutex_unlock(&userns_state_mutex); | |
1194 | ||
1195 | /* Report a successful write */ | |
1196 | *ppos = count; | |
1197 | ret = count; | |
1198 | out: | |
1199 | return ret; | |
1200 | out_unlock: | |
1201 | mutex_unlock(&userns_state_mutex); | |
1202 | goto out; | |
1203 | } | |
1204 | ||
273d2c67 EB |
1205 | bool userns_may_setgroups(const struct user_namespace *ns) |
1206 | { | |
1207 | bool allowed; | |
1208 | ||
f0d62aec | 1209 | mutex_lock(&userns_state_mutex); |
273d2c67 EB |
1210 | /* It is not safe to use setgroups until a gid mapping in |
1211 | * the user namespace has been established. | |
1212 | */ | |
1213 | allowed = ns->gid_map.nr_extents != 0; | |
9cc46516 EB |
1214 | /* Is setgroups allowed? */ |
1215 | allowed = allowed && (ns->flags & USERNS_SETGROUPS_ALLOWED); | |
f0d62aec | 1216 | mutex_unlock(&userns_state_mutex); |
273d2c67 EB |
1217 | |
1218 | return allowed; | |
1219 | } | |
1220 | ||
d07b846f | 1221 | /* |
a2b42626 EB |
1222 | * Returns true if @child is the same namespace or a descendant of |
1223 | * @ancestor. | |
d07b846f | 1224 | */ |
a2b42626 EB |
1225 | bool in_userns(const struct user_namespace *ancestor, |
1226 | const struct user_namespace *child) | |
1227 | { | |
1228 | const struct user_namespace *ns; | |
1229 | for (ns = child; ns->level > ancestor->level; ns = ns->parent) | |
1230 | ; | |
1231 | return (ns == ancestor); | |
1232 | } | |
1233 | ||
d07b846f SF |
1234 | bool current_in_userns(const struct user_namespace *target_ns) |
1235 | { | |
a2b42626 | 1236 | return in_userns(target_ns, current_user_ns()); |
d07b846f SF |
1237 | } |
1238 | ||
3c041184 AV |
1239 | static inline struct user_namespace *to_user_ns(struct ns_common *ns) |
1240 | { | |
1241 | return container_of(ns, struct user_namespace, ns); | |
1242 | } | |
1243 | ||
64964528 | 1244 | static struct ns_common *userns_get(struct task_struct *task) |
cde1975b EB |
1245 | { |
1246 | struct user_namespace *user_ns; | |
1247 | ||
1248 | rcu_read_lock(); | |
1249 | user_ns = get_user_ns(__task_cred(task)->user_ns); | |
1250 | rcu_read_unlock(); | |
1251 | ||
3c041184 | 1252 | return user_ns ? &user_ns->ns : NULL; |
cde1975b EB |
1253 | } |
1254 | ||
64964528 | 1255 | static void userns_put(struct ns_common *ns) |
cde1975b | 1256 | { |
3c041184 | 1257 | put_user_ns(to_user_ns(ns)); |
cde1975b EB |
1258 | } |
1259 | ||
64964528 | 1260 | static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
cde1975b | 1261 | { |
3c041184 | 1262 | struct user_namespace *user_ns = to_user_ns(ns); |
cde1975b EB |
1263 | struct cred *cred; |
1264 | ||
1265 | /* Don't allow gaining capabilities by reentering | |
1266 | * the same user namespace. | |
1267 | */ | |
1268 | if (user_ns == current_user_ns()) | |
1269 | return -EINVAL; | |
1270 | ||
faf00da5 EB |
1271 | /* Tasks that share a thread group must share a user namespace */ |
1272 | if (!thread_group_empty(current)) | |
cde1975b EB |
1273 | return -EINVAL; |
1274 | ||
e66eded8 EB |
1275 | if (current->fs->users != 1) |
1276 | return -EINVAL; | |
1277 | ||
cde1975b EB |
1278 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
1279 | return -EPERM; | |
1280 | ||
1281 | cred = prepare_creds(); | |
1282 | if (!cred) | |
1283 | return -ENOMEM; | |
1284 | ||
1285 | put_user_ns(cred->user_ns); | |
1286 | set_cred_user_ns(cred, get_user_ns(user_ns)); | |
1287 | ||
1288 | return commit_creds(cred); | |
1289 | } | |
1290 | ||
bcac25a5 AV |
1291 | struct ns_common *ns_get_owner(struct ns_common *ns) |
1292 | { | |
1293 | struct user_namespace *my_user_ns = current_user_ns(); | |
1294 | struct user_namespace *owner, *p; | |
1295 | ||
1296 | /* See if the owner is in the current user namespace */ | |
1297 | owner = p = ns->ops->owner(ns); | |
1298 | for (;;) { | |
1299 | if (!p) | |
1300 | return ERR_PTR(-EPERM); | |
1301 | if (p == my_user_ns) | |
1302 | break; | |
1303 | p = p->parent; | |
1304 | } | |
1305 | ||
1306 | return &get_user_ns(owner)->ns; | |
1307 | } | |
1308 | ||
1309 | static struct user_namespace *userns_owner(struct ns_common *ns) | |
1310 | { | |
1311 | return to_user_ns(ns)->parent; | |
1312 | } | |
1313 | ||
cde1975b EB |
1314 | const struct proc_ns_operations userns_operations = { |
1315 | .name = "user", | |
1316 | .type = CLONE_NEWUSER, | |
1317 | .get = userns_get, | |
1318 | .put = userns_put, | |
1319 | .install = userns_install, | |
bcac25a5 | 1320 | .owner = userns_owner, |
a7306ed8 | 1321 | .get_parent = ns_get_owner, |
cde1975b EB |
1322 | }; |
1323 | ||
6164281a PE |
1324 | static __init int user_namespaces_init(void) |
1325 | { | |
1326 | user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC); | |
1327 | return 0; | |
1328 | } | |
c96d6660 | 1329 | subsys_initcall(user_namespaces_init); |