Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * Copyright (C) 2006 IBM Corporation
4 : *
5 : * Author: Serge Hallyn <serue@us.ibm.com>
6 : *
7 : * Jun 2006 - namespaces support
8 : * OpenVZ, SWsoft Inc.
9 : * Pavel Emelianov <xemul@openvz.org>
10 : */
11 :
12 : #include <linux/slab.h>
13 : #include <linux/export.h>
14 : #include <linux/nsproxy.h>
15 : #include <linux/init_task.h>
16 : #include <linux/mnt_namespace.h>
17 : #include <linux/utsname.h>
18 : #include <linux/pid_namespace.h>
19 : #include <net/net_namespace.h>
20 : #include <linux/ipc_namespace.h>
21 : #include <linux/time_namespace.h>
22 : #include <linux/fs_struct.h>
23 : #include <linux/proc_fs.h>
24 : #include <linux/proc_ns.h>
25 : #include <linux/file.h>
26 : #include <linux/syscalls.h>
27 : #include <linux/cgroup.h>
28 : #include <linux/perf_event.h>
29 :
30 : static struct kmem_cache *nsproxy_cachep;
31 :
32 : struct nsproxy init_nsproxy = {
33 : .count = ATOMIC_INIT(1),
34 : .uts_ns = &init_uts_ns,
35 : #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
36 : .ipc_ns = &init_ipc_ns,
37 : #endif
38 : .mnt_ns = NULL,
39 : .pid_ns_for_children = &init_pid_ns,
40 : #ifdef CONFIG_NET
41 : .net_ns = &init_net,
42 : #endif
43 : #ifdef CONFIG_CGROUPS
44 : .cgroup_ns = &init_cgroup_ns,
45 : #endif
46 : #ifdef CONFIG_TIME_NS
47 : .time_ns = &init_time_ns,
48 : .time_ns_for_children = &init_time_ns,
49 : #endif
50 : };
51 :
52 : static inline struct nsproxy *create_nsproxy(void)
53 : {
54 : struct nsproxy *nsproxy;
55 :
56 0 : nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
57 0 : if (nsproxy)
58 0 : atomic_set(&nsproxy->count, 1);
59 : return nsproxy;
60 : }
61 :
62 : /*
63 : * Create new nsproxy and all of its the associated namespaces.
64 : * Return the newly created nsproxy. Do not attach this to the task,
65 : * leave it to the caller to do proper locking and attach it to task.
66 : */
67 0 : static struct nsproxy *create_new_namespaces(unsigned long flags,
68 : struct task_struct *tsk, struct user_namespace *user_ns,
69 : struct fs_struct *new_fs)
70 : {
71 : struct nsproxy *new_nsp;
72 : int err;
73 :
74 0 : new_nsp = create_nsproxy();
75 0 : if (!new_nsp)
76 : return ERR_PTR(-ENOMEM);
77 :
78 0 : new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
79 0 : if (IS_ERR(new_nsp->mnt_ns)) {
80 0 : err = PTR_ERR(new_nsp->mnt_ns);
81 : goto out_ns;
82 : }
83 :
84 0 : new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
85 0 : if (IS_ERR(new_nsp->uts_ns)) {
86 0 : err = PTR_ERR(new_nsp->uts_ns);
87 : goto out_uts;
88 : }
89 :
90 0 : new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
91 0 : if (IS_ERR(new_nsp->ipc_ns)) {
92 0 : err = PTR_ERR(new_nsp->ipc_ns);
93 : goto out_ipc;
94 : }
95 :
96 0 : new_nsp->pid_ns_for_children =
97 0 : copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
98 0 : if (IS_ERR(new_nsp->pid_ns_for_children)) {
99 0 : err = PTR_ERR(new_nsp->pid_ns_for_children);
100 : goto out_pid;
101 : }
102 :
103 0 : new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
104 0 : tsk->nsproxy->cgroup_ns);
105 0 : if (IS_ERR(new_nsp->cgroup_ns)) {
106 0 : err = PTR_ERR(new_nsp->cgroup_ns);
107 : goto out_cgroup;
108 : }
109 :
110 0 : new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
111 0 : if (IS_ERR(new_nsp->net_ns)) {
112 0 : err = PTR_ERR(new_nsp->net_ns);
113 : goto out_net;
114 : }
115 :
116 0 : new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns,
117 : tsk->nsproxy->time_ns_for_children);
118 0 : if (IS_ERR(new_nsp->time_ns_for_children)) {
119 0 : err = PTR_ERR(new_nsp->time_ns_for_children);
120 : goto out_time;
121 : }
122 0 : new_nsp->time_ns = get_time_ns(tsk->nsproxy->time_ns);
123 :
124 : return new_nsp;
125 :
126 : out_time:
127 0 : put_net(new_nsp->net_ns);
128 : out_net:
129 0 : put_cgroup_ns(new_nsp->cgroup_ns);
130 : out_cgroup:
131 0 : if (new_nsp->pid_ns_for_children)
132 0 : put_pid_ns(new_nsp->pid_ns_for_children);
133 : out_pid:
134 : if (new_nsp->ipc_ns)
135 : put_ipc_ns(new_nsp->ipc_ns);
136 : out_ipc:
137 0 : if (new_nsp->uts_ns)
138 0 : put_uts_ns(new_nsp->uts_ns);
139 : out_uts:
140 0 : if (new_nsp->mnt_ns)
141 0 : put_mnt_ns(new_nsp->mnt_ns);
142 : out_ns:
143 0 : kmem_cache_free(nsproxy_cachep, new_nsp);
144 0 : return ERR_PTR(err);
145 : }
146 :
147 : /*
148 : * called from clone. This now handles copy for nsproxy and all
149 : * namespaces therein.
150 : */
151 340 : int copy_namespaces(unsigned long flags, struct task_struct *tsk)
152 : {
153 340 : struct nsproxy *old_ns = tsk->nsproxy;
154 680 : struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
155 : struct nsproxy *new_ns;
156 :
157 340 : if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
158 : CLONE_NEWPID | CLONE_NEWNET |
159 : CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
160 340 : if ((flags & CLONE_VM) ||
161 0 : likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
162 340 : get_nsproxy(old_ns);
163 340 : return 0;
164 : }
165 0 : } else if (!ns_capable(user_ns, CAP_SYS_ADMIN))
166 : return -EPERM;
167 :
168 : /*
169 : * CLONE_NEWIPC must detach from the undolist: after switching
170 : * to a new ipc namespace, the semaphore arrays from the old
171 : * namespace are unreachable. In clone parlance, CLONE_SYSVSEM
172 : * means share undolist with parent, so we must forbid using
173 : * it along with CLONE_NEWIPC.
174 : */
175 0 : if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
176 : (CLONE_NEWIPC | CLONE_SYSVSEM))
177 : return -EINVAL;
178 :
179 0 : new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
180 0 : if (IS_ERR(new_ns))
181 0 : return PTR_ERR(new_ns);
182 :
183 : if ((flags & CLONE_VM) == 0)
184 : timens_on_fork(new_ns, tsk);
185 :
186 0 : tsk->nsproxy = new_ns;
187 0 : return 0;
188 : }
189 :
190 0 : void free_nsproxy(struct nsproxy *ns)
191 : {
192 0 : if (ns->mnt_ns)
193 0 : put_mnt_ns(ns->mnt_ns);
194 0 : if (ns->uts_ns)
195 0 : put_uts_ns(ns->uts_ns);
196 : if (ns->ipc_ns)
197 : put_ipc_ns(ns->ipc_ns);
198 0 : if (ns->pid_ns_for_children)
199 0 : put_pid_ns(ns->pid_ns_for_children);
200 : if (ns->time_ns)
201 : put_time_ns(ns->time_ns);
202 : if (ns->time_ns_for_children)
203 : put_time_ns(ns->time_ns_for_children);
204 0 : put_cgroup_ns(ns->cgroup_ns);
205 0 : put_net(ns->net_ns);
206 0 : kmem_cache_free(nsproxy_cachep, ns);
207 0 : }
208 :
209 : /*
210 : * Called from unshare. Unshare all the namespaces part of nsproxy.
211 : * On success, returns the new nsproxy.
212 : */
213 0 : int unshare_nsproxy_namespaces(unsigned long unshare_flags,
214 : struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
215 : {
216 : struct user_namespace *user_ns;
217 0 : int err = 0;
218 :
219 0 : if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
220 : CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
221 : CLONE_NEWTIME)))
222 : return 0;
223 :
224 0 : user_ns = new_cred ? new_cred->user_ns : current_user_ns();
225 0 : if (!ns_capable(user_ns, CAP_SYS_ADMIN))
226 : return -EPERM;
227 :
228 0 : *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
229 0 : new_fs ? new_fs : current->fs);
230 0 : if (IS_ERR(*new_nsp)) {
231 0 : err = PTR_ERR(*new_nsp);
232 0 : goto out;
233 : }
234 :
235 : out:
236 : return err;
237 : }
238 :
239 0 : void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
240 : {
241 : struct nsproxy *ns;
242 :
243 : might_sleep();
244 :
245 325 : task_lock(p);
246 325 : ns = p->nsproxy;
247 325 : p->nsproxy = new;
248 325 : task_unlock(p);
249 :
250 325 : if (ns)
251 : put_nsproxy(ns);
252 0 : }
253 :
254 325 : void exit_task_namespaces(struct task_struct *p)
255 : {
256 325 : switch_task_namespaces(p, NULL);
257 325 : }
258 :
259 0 : int exec_task_namespaces(void)
260 : {
261 0 : struct task_struct *tsk = current;
262 : struct nsproxy *new;
263 :
264 0 : if (tsk->nsproxy->time_ns_for_children == tsk->nsproxy->time_ns)
265 : return 0;
266 :
267 0 : new = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
268 0 : if (IS_ERR(new))
269 0 : return PTR_ERR(new);
270 :
271 0 : timens_on_fork(new, tsk);
272 : switch_task_namespaces(tsk, new);
273 : return 0;
274 : }
275 :
276 0 : static int check_setns_flags(unsigned long flags)
277 : {
278 0 : if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
279 : CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
280 : CLONE_NEWPID | CLONE_NEWCGROUP)))
281 : return -EINVAL;
282 :
283 : #ifndef CONFIG_USER_NS
284 0 : if (flags & CLONE_NEWUSER)
285 : return -EINVAL;
286 : #endif
287 : #ifndef CONFIG_PID_NS
288 : if (flags & CLONE_NEWPID)
289 : return -EINVAL;
290 : #endif
291 : #ifndef CONFIG_UTS_NS
292 : if (flags & CLONE_NEWUTS)
293 : return -EINVAL;
294 : #endif
295 : #ifndef CONFIG_IPC_NS
296 0 : if (flags & CLONE_NEWIPC)
297 : return -EINVAL;
298 : #endif
299 : #ifndef CONFIG_CGROUPS
300 0 : if (flags & CLONE_NEWCGROUP)
301 : return -EINVAL;
302 : #endif
303 : #ifndef CONFIG_NET_NS
304 0 : if (flags & CLONE_NEWNET)
305 : return -EINVAL;
306 : #endif
307 : #ifndef CONFIG_TIME_NS
308 0 : if (flags & CLONE_NEWTIME)
309 : return -EINVAL;
310 : #endif
311 :
312 0 : return 0;
313 : }
314 :
315 0 : static void put_nsset(struct nsset *nsset)
316 : {
317 0 : unsigned flags = nsset->flags;
318 :
319 0 : if (flags & CLONE_NEWUSER)
320 0 : put_cred(nsset_cred(nsset));
321 : /*
322 : * We only created a temporary copy if we attached to more than just
323 : * the mount namespace.
324 : */
325 0 : if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
326 0 : free_fs_struct(nsset->fs);
327 0 : if (nsset->nsproxy)
328 0 : free_nsproxy(nsset->nsproxy);
329 0 : }
330 :
331 0 : static int prepare_nsset(unsigned flags, struct nsset *nsset)
332 : {
333 0 : struct task_struct *me = current;
334 :
335 0 : nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
336 0 : if (IS_ERR(nsset->nsproxy))
337 0 : return PTR_ERR(nsset->nsproxy);
338 :
339 0 : if (flags & CLONE_NEWUSER)
340 0 : nsset->cred = prepare_creds();
341 : else
342 0 : nsset->cred = current_cred();
343 0 : if (!nsset->cred)
344 : goto out;
345 :
346 : /* Only create a temporary copy of fs_struct if we really need to. */
347 0 : if (flags == CLONE_NEWNS) {
348 0 : nsset->fs = me->fs;
349 0 : } else if (flags & CLONE_NEWNS) {
350 0 : nsset->fs = copy_fs_struct(me->fs);
351 0 : if (!nsset->fs)
352 : goto out;
353 : }
354 :
355 0 : nsset->flags = flags;
356 0 : return 0;
357 :
358 : out:
359 0 : put_nsset(nsset);
360 0 : return -ENOMEM;
361 : }
362 :
363 : static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
364 : {
365 0 : return ns->ops->install(nsset, ns);
366 : }
367 :
368 : /*
369 : * This is the inverse operation to unshare().
370 : * Ordering is equivalent to the standard ordering used everywhere else
371 : * during unshare and process creation. The switch to the new set of
372 : * namespaces occurs at the point of no return after installation of
373 : * all requested namespaces was successful in commit_nsset().
374 : */
375 0 : static int validate_nsset(struct nsset *nsset, struct pid *pid)
376 : {
377 0 : int ret = 0;
378 0 : unsigned flags = nsset->flags;
379 0 : struct user_namespace *user_ns = NULL;
380 0 : struct pid_namespace *pid_ns = NULL;
381 : struct nsproxy *nsp;
382 : struct task_struct *tsk;
383 :
384 : /* Take a "snapshot" of the target task's namespaces. */
385 : rcu_read_lock();
386 0 : tsk = pid_task(pid, PIDTYPE_PID);
387 0 : if (!tsk) {
388 : rcu_read_unlock();
389 0 : return -ESRCH;
390 : }
391 :
392 0 : if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
393 : rcu_read_unlock();
394 0 : return -EPERM;
395 : }
396 :
397 0 : task_lock(tsk);
398 0 : nsp = tsk->nsproxy;
399 0 : if (nsp)
400 : get_nsproxy(nsp);
401 0 : task_unlock(tsk);
402 0 : if (!nsp) {
403 : rcu_read_unlock();
404 0 : return -ESRCH;
405 : }
406 :
407 : #ifdef CONFIG_PID_NS
408 0 : if (flags & CLONE_NEWPID) {
409 0 : pid_ns = task_active_pid_ns(tsk);
410 0 : if (unlikely(!pid_ns)) {
411 : rcu_read_unlock();
412 0 : ret = -ESRCH;
413 0 : goto out;
414 : }
415 : get_pid_ns(pid_ns);
416 : }
417 : #endif
418 :
419 : #ifdef CONFIG_USER_NS
420 : if (flags & CLONE_NEWUSER)
421 : user_ns = get_user_ns(__task_cred(tsk)->user_ns);
422 : #endif
423 : rcu_read_unlock();
424 :
425 : /*
426 : * Install requested namespaces. The caller will have
427 : * verified earlier that the requested namespaces are
428 : * supported on this kernel. We don't report errors here
429 : * if a namespace is requested that isn't supported.
430 : */
431 : #ifdef CONFIG_USER_NS
432 : if (flags & CLONE_NEWUSER) {
433 : ret = validate_ns(nsset, &user_ns->ns);
434 : if (ret)
435 : goto out;
436 : }
437 : #endif
438 :
439 0 : if (flags & CLONE_NEWNS) {
440 0 : ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
441 0 : if (ret)
442 : goto out;
443 : }
444 :
445 : #ifdef CONFIG_UTS_NS
446 0 : if (flags & CLONE_NEWUTS) {
447 0 : ret = validate_ns(nsset, &nsp->uts_ns->ns);
448 0 : if (ret)
449 : goto out;
450 : }
451 : #endif
452 :
453 : #ifdef CONFIG_IPC_NS
454 : if (flags & CLONE_NEWIPC) {
455 : ret = validate_ns(nsset, &nsp->ipc_ns->ns);
456 : if (ret)
457 : goto out;
458 : }
459 : #endif
460 :
461 : #ifdef CONFIG_PID_NS
462 0 : if (flags & CLONE_NEWPID) {
463 0 : ret = validate_ns(nsset, &pid_ns->ns);
464 : if (ret)
465 : goto out;
466 : }
467 : #endif
468 :
469 : #ifdef CONFIG_CGROUPS
470 : if (flags & CLONE_NEWCGROUP) {
471 : ret = validate_ns(nsset, &nsp->cgroup_ns->ns);
472 : if (ret)
473 : goto out;
474 : }
475 : #endif
476 :
477 : #ifdef CONFIG_NET_NS
478 : if (flags & CLONE_NEWNET) {
479 : ret = validate_ns(nsset, &nsp->net_ns->ns);
480 : if (ret)
481 : goto out;
482 : }
483 : #endif
484 :
485 : #ifdef CONFIG_TIME_NS
486 : if (flags & CLONE_NEWTIME) {
487 : ret = validate_ns(nsset, &nsp->time_ns->ns);
488 : if (ret)
489 : goto out;
490 : }
491 : #endif
492 :
493 : out:
494 0 : if (pid_ns)
495 0 : put_pid_ns(pid_ns);
496 : if (nsp)
497 : put_nsproxy(nsp);
498 : put_user_ns(user_ns);
499 :
500 : return ret;
501 : }
502 :
503 : /*
504 : * This is the point of no return. There are just a few namespaces
505 : * that do some actual work here and it's sufficiently minimal that
506 : * a separate ns_common operation seems unnecessary for now.
507 : * Unshare is doing the same thing. If we'll end up needing to do
508 : * more in a given namespace or a helper here is ultimately not
509 : * exported anymore a simple commit handler for each namespace
510 : * should be added to ns_common.
511 : */
512 0 : static void commit_nsset(struct nsset *nsset)
513 : {
514 0 : unsigned flags = nsset->flags;
515 0 : struct task_struct *me = current;
516 :
517 : #ifdef CONFIG_USER_NS
518 : if (flags & CLONE_NEWUSER) {
519 : /* transfer ownership */
520 : commit_creds(nsset_cred(nsset));
521 : nsset->cred = NULL;
522 : }
523 : #endif
524 :
525 : /* We only need to commit if we have used a temporary fs_struct. */
526 0 : if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
527 0 : set_fs_root(me->fs, &nsset->fs->root);
528 0 : set_fs_pwd(me->fs, &nsset->fs->pwd);
529 : }
530 :
531 : #ifdef CONFIG_IPC_NS
532 : if (flags & CLONE_NEWIPC)
533 : exit_sem(me);
534 : #endif
535 :
536 : #ifdef CONFIG_TIME_NS
537 : if (flags & CLONE_NEWTIME)
538 : timens_commit(me, nsset->nsproxy->time_ns);
539 : #endif
540 :
541 : /* transfer ownership */
542 0 : switch_task_namespaces(me, nsset->nsproxy);
543 0 : nsset->nsproxy = NULL;
544 0 : }
545 :
546 0 : SYSCALL_DEFINE2(setns, int, fd, int, flags)
547 : {
548 : struct file *file;
549 0 : struct ns_common *ns = NULL;
550 0 : struct nsset nsset = {};
551 0 : int err = 0;
552 :
553 0 : file = fget(fd);
554 0 : if (!file)
555 : return -EBADF;
556 :
557 0 : if (proc_ns_file(file)) {
558 0 : ns = get_proc_ns(file_inode(file));
559 0 : if (flags && (ns->ops->type != flags))
560 0 : err = -EINVAL;
561 0 : flags = ns->ops->type;
562 0 : } else if (!IS_ERR(pidfd_pid(file))) {
563 0 : err = check_setns_flags(flags);
564 : } else {
565 : err = -EINVAL;
566 : }
567 0 : if (err)
568 : goto out;
569 :
570 0 : err = prepare_nsset(flags, &nsset);
571 0 : if (err)
572 : goto out;
573 :
574 0 : if (proc_ns_file(file))
575 0 : err = validate_ns(&nsset, ns);
576 : else
577 0 : err = validate_nsset(&nsset, file->private_data);
578 0 : if (!err) {
579 0 : commit_nsset(&nsset);
580 0 : perf_event_namespaces(current);
581 : }
582 0 : put_nsset(&nsset);
583 : out:
584 0 : fput(file);
585 0 : return err;
586 : }
587 :
588 1 : int __init nsproxy_cache_init(void)
589 : {
590 1 : nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC|SLAB_ACCOUNT);
591 1 : return 0;
592 : }
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