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
30static struct kmem_cache *nsproxy_cachep;
31
32struct nsproxy init_nsproxy = {
33	.count			= REFCOUNT_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		refcount_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 ((flags & CLONE_VM) ||
161		    likely(old_ns->time_ns_for_children == old_ns->time_ns)) {
162			get_nsproxy(old_ns);
163			return 0;
164		}
165	} 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	if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
176		(CLONE_NEWIPC | CLONE_SYSVSEM))
177		return -EINVAL;
178
179	new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
180	if (IS_ERR(new_ns))
181		return  PTR_ERR(new_ns);
182
183	if ((flags & CLONE_VM) == 0)
184		timens_on_fork(new_ns, tsk);
185
186	tsk->nsproxy = new_ns;
187	return 0;
188}
189
190void free_nsproxy(struct nsproxy *ns)
191{
192	if (ns->mnt_ns)
193		put_mnt_ns(ns->mnt_ns);
194	if (ns->uts_ns)
195		put_uts_ns(ns->uts_ns);
196	if (ns->ipc_ns)
197		put_ipc_ns(ns->ipc_ns);
198	if (ns->pid_ns_for_children)
199		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	put_cgroup_ns(ns->cgroup_ns);
205	put_net(ns->net_ns);
206	kmem_cache_free(nsproxy_cachep, ns);
207}
208
209/*
210 * Called from unshare. Unshare all the namespaces part of nsproxy.
211 * On success, returns the new nsproxy.
212 */
213int 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	int err = 0;
218
219	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
220			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
221			       CLONE_NEWTIME)))
222		return 0;
223
224	user_ns = new_cred ? new_cred->user_ns : current_user_ns();
225	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
226		return -EPERM;
227
228	*new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
229					 new_fs ? new_fs : current->fs);
230	if (IS_ERR(*new_nsp)) {
231		err = PTR_ERR(*new_nsp);
232		goto out;
233	}
234
235out:
236	return err;
237}
238
239void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
240{
241	struct nsproxy *ns;
242
243	might_sleep();
244
245	task_lock(p);
246	ns = p->nsproxy;
247	p->nsproxy = new;
248	task_unlock(p);
249
250	if (ns)
251		put_nsproxy(ns);
252}
253
254void exit_task_namespaces(struct task_struct *p)
255{
256	switch_task_namespaces(p, NULL);
257}
258
259int exec_task_namespaces(void)
260{
261	struct task_struct *tsk = current;
262	struct nsproxy *new;
263
264	if (tsk->nsproxy->time_ns_for_children == tsk->nsproxy->time_ns)
265		return 0;
266
267	new = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
268	if (IS_ERR(new))
269		return PTR_ERR(new);
270
271	timens_on_fork(new, tsk);
272	switch_task_namespaces(tsk, new);
273	return 0;
274}
275
276static int check_setns_flags(unsigned long flags)
277{
278	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	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	if (flags & CLONE_NEWIPC)
297		return -EINVAL;
298#endif
299#ifndef CONFIG_CGROUPS
300	if (flags & CLONE_NEWCGROUP)
301		return -EINVAL;
302#endif
303#ifndef CONFIG_NET_NS
304	if (flags & CLONE_NEWNET)
305		return -EINVAL;
306#endif
307#ifndef CONFIG_TIME_NS
308	if (flags & CLONE_NEWTIME)
309		return -EINVAL;
310#endif
311
312	return 0;
313}
314
315static void put_nsset(struct nsset *nsset)
316{
317	unsigned flags = nsset->flags;
318
319	if (flags & CLONE_NEWUSER)
320		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	if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
326		free_fs_struct(nsset->fs);
327	if (nsset->nsproxy)
328		free_nsproxy(nsset->nsproxy);
329}
330
331static int prepare_nsset(unsigned flags, struct nsset *nsset)
332{
333	struct task_struct *me = current;
334
335	nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
336	if (IS_ERR(nsset->nsproxy))
337		return PTR_ERR(nsset->nsproxy);
338
339	if (flags & CLONE_NEWUSER)
340		nsset->cred = prepare_creds();
341	else
342		nsset->cred = current_cred();
343	if (!nsset->cred)
344		goto out;
345
346	/* Only create a temporary copy of fs_struct if we really need to. */
347	if (flags == CLONE_NEWNS) {
348		nsset->fs = me->fs;
349	} else if (flags & CLONE_NEWNS) {
350		nsset->fs = copy_fs_struct(me->fs);
351		if (!nsset->fs)
352			goto out;
353	}
354
355	nsset->flags = flags;
356	return 0;
357
358out:
359	put_nsset(nsset);
360	return -ENOMEM;
361}
362
363static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
364{
365	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 */
375static int validate_nsset(struct nsset *nsset, struct pid *pid)
376{
377	int ret = 0;
378	unsigned flags = nsset->flags;
379	struct user_namespace *user_ns = NULL;
380	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	tsk = pid_task(pid, PIDTYPE_PID);
387	if (!tsk) {
388		rcu_read_unlock();
389		return -ESRCH;
390	}
391
392	if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
393		rcu_read_unlock();
394		return -EPERM;
395	}
396
397	task_lock(tsk);
398	nsp = tsk->nsproxy;
399	if (nsp)
400		get_nsproxy(nsp);
401	task_unlock(tsk);
402	if (!nsp) {
403		rcu_read_unlock();
404		return -ESRCH;
405	}
406
407#ifdef CONFIG_PID_NS
408	if (flags & CLONE_NEWPID) {
409		pid_ns = task_active_pid_ns(tsk);
410		if (unlikely(!pid_ns)) {
411			rcu_read_unlock();
412			ret = -ESRCH;
413			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	if (flags & CLONE_NEWNS) {
440		ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
441		if (ret)
442			goto out;
443	}
444
445#ifdef CONFIG_UTS_NS
446	if (flags & CLONE_NEWUTS) {
447		ret = validate_ns(nsset, &nsp->uts_ns->ns);
448		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	if (flags & CLONE_NEWPID) {
463		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
493out:
494	if (pid_ns)
495		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 */
512static void commit_nsset(struct nsset *nsset)
513{
514	unsigned flags = nsset->flags;
515	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	if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
527		set_fs_root(me->fs, &nsset->fs->root);
528		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	switch_task_namespaces(me, nsset->nsproxy);
543	nsset->nsproxy = NULL;
544}
545
546SYSCALL_DEFINE2(setns, int, fd, int, flags)
547{
548	struct fd f = fdget(fd);
549	struct ns_common *ns = NULL;
550	struct nsset nsset = {};
551	int err = 0;
552
553	if (!f.file)
554		return -EBADF;
555
556	if (proc_ns_file(f.file)) {
557		ns = get_proc_ns(file_inode(f.file));
558		if (flags && (ns->ops->type != flags))
559			err = -EINVAL;
560		flags = ns->ops->type;
561	} else if (!IS_ERR(pidfd_pid(f.file))) {
562		err = check_setns_flags(flags);
563	} else {
564		err = -EINVAL;
565	}
566	if (err)
567		goto out;
568
569	err = prepare_nsset(flags, &nsset);
570	if (err)
571		goto out;
572
573	if (proc_ns_file(f.file))
574		err = validate_ns(&nsset, ns);
575	else
576		err = validate_nsset(&nsset, pidfd_pid(f.file));
577	if (!err) {
578		commit_nsset(&nsset);
579		perf_event_namespaces(current);
580	}
581	put_nsset(&nsset);
582out:
583	fdput(f);
584	return err;
585}
586
587int __init nsproxy_cache_init(void)
588{
589	nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC|SLAB_ACCOUNT);
590	return 0;
591}
592