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