projects/linux·blob v6.0-rc2 · refs

574 lines · 12.8 KiB

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