Merge tag 'x86-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-microblaze.git] / kernel / nsproxy.c
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         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  */
67 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         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
126 out_time:
127         put_net(new_nsp->net_ns);
128 out_net:
129         put_cgroup_ns(new_nsp->cgroup_ns);
130 out_cgroup:
131         if (new_nsp->pid_ns_for_children)
132                 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         if (new_nsp->uts_ns)
138                 put_uts_ns(new_nsp->uts_ns);
139 out_uts:
140         if (new_nsp->mnt_ns)
141                 put_mnt_ns(new_nsp->mnt_ns);
142 out_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  */
151 int 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         int ret;
157
158         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
159                               CLONE_NEWPID | CLONE_NEWNET |
160                               CLONE_NEWCGROUP | CLONE_NEWTIME)))) {
161                 if (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         ret = timens_on_fork(new_ns, tsk);
184         if (ret) {
185                 free_nsproxy(new_ns);
186                 return ret;
187         }
188
189         tsk->nsproxy = new_ns;
190         return 0;
191 }
192
193 void free_nsproxy(struct nsproxy *ns)
194 {
195         if (ns->mnt_ns)
196                 put_mnt_ns(ns->mnt_ns);
197         if (ns->uts_ns)
198                 put_uts_ns(ns->uts_ns);
199         if (ns->ipc_ns)
200                 put_ipc_ns(ns->ipc_ns);
201         if (ns->pid_ns_for_children)
202                 put_pid_ns(ns->pid_ns_for_children);
203         if (ns->time_ns)
204                 put_time_ns(ns->time_ns);
205         if (ns->time_ns_for_children)
206                 put_time_ns(ns->time_ns_for_children);
207         put_cgroup_ns(ns->cgroup_ns);
208         put_net(ns->net_ns);
209         kmem_cache_free(nsproxy_cachep, ns);
210 }
211
212 /*
213  * Called from unshare. Unshare all the namespaces part of nsproxy.
214  * On success, returns the new nsproxy.
215  */
216 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
217         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
218 {
219         struct user_namespace *user_ns;
220         int err = 0;
221
222         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
223                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
224                                CLONE_NEWTIME)))
225                 return 0;
226
227         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
228         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
229                 return -EPERM;
230
231         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
232                                          new_fs ? new_fs : current->fs);
233         if (IS_ERR(*new_nsp)) {
234                 err = PTR_ERR(*new_nsp);
235                 goto out;
236         }
237
238 out:
239         return err;
240 }
241
242 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
243 {
244         struct nsproxy *ns;
245
246         might_sleep();
247
248         task_lock(p);
249         ns = p->nsproxy;
250         p->nsproxy = new;
251         task_unlock(p);
252
253         if (ns && atomic_dec_and_test(&ns->count))
254                 free_nsproxy(ns);
255 }
256
257 void exit_task_namespaces(struct task_struct *p)
258 {
259         switch_task_namespaces(p, NULL);
260 }
261
262 static int check_setns_flags(unsigned long flags)
263 {
264         if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
265                                  CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
266                                  CLONE_NEWPID | CLONE_NEWCGROUP)))
267                 return -EINVAL;
268
269 #ifndef CONFIG_USER_NS
270         if (flags & CLONE_NEWUSER)
271                 return -EINVAL;
272 #endif
273 #ifndef CONFIG_PID_NS
274         if (flags & CLONE_NEWPID)
275                 return -EINVAL;
276 #endif
277 #ifndef CONFIG_UTS_NS
278         if (flags & CLONE_NEWUTS)
279                 return -EINVAL;
280 #endif
281 #ifndef CONFIG_IPC_NS
282         if (flags & CLONE_NEWIPC)
283                 return -EINVAL;
284 #endif
285 #ifndef CONFIG_CGROUPS
286         if (flags & CLONE_NEWCGROUP)
287                 return -EINVAL;
288 #endif
289 #ifndef CONFIG_NET_NS
290         if (flags & CLONE_NEWNET)
291                 return -EINVAL;
292 #endif
293 #ifndef CONFIG_TIME_NS
294         if (flags & CLONE_NEWTIME)
295                 return -EINVAL;
296 #endif
297
298         return 0;
299 }
300
301 static void put_nsset(struct nsset *nsset)
302 {
303         unsigned flags = nsset->flags;
304
305         if (flags & CLONE_NEWUSER)
306                 put_cred(nsset_cred(nsset));
307         /*
308          * We only created a temporary copy if we attached to more than just
309          * the mount namespace.
310          */
311         if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
312                 free_fs_struct(nsset->fs);
313         if (nsset->nsproxy)
314                 free_nsproxy(nsset->nsproxy);
315 }
316
317 static int prepare_nsset(unsigned flags, struct nsset *nsset)
318 {
319         struct task_struct *me = current;
320
321         nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
322         if (IS_ERR(nsset->nsproxy))
323                 return PTR_ERR(nsset->nsproxy);
324
325         if (flags & CLONE_NEWUSER)
326                 nsset->cred = prepare_creds();
327         else
328                 nsset->cred = current_cred();
329         if (!nsset->cred)
330                 goto out;
331
332         /* Only create a temporary copy of fs_struct if we really need to. */
333         if (flags == CLONE_NEWNS) {
334                 nsset->fs = me->fs;
335         } else if (flags & CLONE_NEWNS) {
336                 nsset->fs = copy_fs_struct(me->fs);
337                 if (!nsset->fs)
338                         goto out;
339         }
340
341         nsset->flags = flags;
342         return 0;
343
344 out:
345         put_nsset(nsset);
346         return -ENOMEM;
347 }
348
349 static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
350 {
351         return ns->ops->install(nsset, ns);
352 }
353
354 /*
355  * This is the inverse operation to unshare().
356  * Ordering is equivalent to the standard ordering used everywhere else
357  * during unshare and process creation. The switch to the new set of
358  * namespaces occurs at the point of no return after installation of
359  * all requested namespaces was successful in commit_nsset().
360  */
361 static int validate_nsset(struct nsset *nsset, struct pid *pid)
362 {
363         int ret = 0;
364         unsigned flags = nsset->flags;
365         struct user_namespace *user_ns = NULL;
366         struct pid_namespace *pid_ns = NULL;
367         struct nsproxy *nsp;
368         struct task_struct *tsk;
369
370         /* Take a "snapshot" of the target task's namespaces. */
371         rcu_read_lock();
372         tsk = pid_task(pid, PIDTYPE_PID);
373         if (!tsk) {
374                 rcu_read_unlock();
375                 return -ESRCH;
376         }
377
378         if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
379                 rcu_read_unlock();
380                 return -EPERM;
381         }
382
383         task_lock(tsk);
384         nsp = tsk->nsproxy;
385         if (nsp)
386                 get_nsproxy(nsp);
387         task_unlock(tsk);
388         if (!nsp) {
389                 rcu_read_unlock();
390                 return -ESRCH;
391         }
392
393 #ifdef CONFIG_PID_NS
394         if (flags & CLONE_NEWPID) {
395                 pid_ns = task_active_pid_ns(tsk);
396                 if (unlikely(!pid_ns)) {
397                         rcu_read_unlock();
398                         ret = -ESRCH;
399                         goto out;
400                 }
401                 get_pid_ns(pid_ns);
402         }
403 #endif
404
405 #ifdef CONFIG_USER_NS
406         if (flags & CLONE_NEWUSER)
407                 user_ns = get_user_ns(__task_cred(tsk)->user_ns);
408 #endif
409         rcu_read_unlock();
410
411         /*
412          * Install requested namespaces. The caller will have
413          * verified earlier that the requested namespaces are
414          * supported on this kernel. We don't report errors here
415          * if a namespace is requested that isn't supported.
416          */
417 #ifdef CONFIG_USER_NS
418         if (flags & CLONE_NEWUSER) {
419                 ret = validate_ns(nsset, &user_ns->ns);
420                 if (ret)
421                         goto out;
422         }
423 #endif
424
425         if (flags & CLONE_NEWNS) {
426                 ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
427                 if (ret)
428                         goto out;
429         }
430
431 #ifdef CONFIG_UTS_NS
432         if (flags & CLONE_NEWUTS) {
433                 ret = validate_ns(nsset, &nsp->uts_ns->ns);
434                 if (ret)
435                         goto out;
436         }
437 #endif
438
439 #ifdef CONFIG_IPC_NS
440         if (flags & CLONE_NEWIPC) {
441                 ret = validate_ns(nsset, &nsp->ipc_ns->ns);
442                 if (ret)
443                         goto out;
444         }
445 #endif
446
447 #ifdef CONFIG_PID_NS
448         if (flags & CLONE_NEWPID) {
449                 ret = validate_ns(nsset, &pid_ns->ns);
450                 if (ret)
451                         goto out;
452         }
453 #endif
454
455 #ifdef CONFIG_CGROUPS
456         if (flags & CLONE_NEWCGROUP) {
457                 ret = validate_ns(nsset, &nsp->cgroup_ns->ns);
458                 if (ret)
459                         goto out;
460         }
461 #endif
462
463 #ifdef CONFIG_NET_NS
464         if (flags & CLONE_NEWNET) {
465                 ret = validate_ns(nsset, &nsp->net_ns->ns);
466                 if (ret)
467                         goto out;
468         }
469 #endif
470
471 #ifdef CONFIG_TIME_NS
472         if (flags & CLONE_NEWTIME) {
473                 ret = validate_ns(nsset, &nsp->time_ns->ns);
474                 if (ret)
475                         goto out;
476         }
477 #endif
478
479 out:
480         if (pid_ns)
481                 put_pid_ns(pid_ns);
482         if (nsp)
483                 put_nsproxy(nsp);
484         put_user_ns(user_ns);
485
486         return ret;
487 }
488
489 /*
490  * This is the point of no return. There are just a few namespaces
491  * that do some actual work here and it's sufficiently minimal that
492  * a separate ns_common operation seems unnecessary for now.
493  * Unshare is doing the same thing. If we'll end up needing to do
494  * more in a given namespace or a helper here is ultimately not
495  * exported anymore a simple commit handler for each namespace
496  * should be added to ns_common.
497  */
498 static void commit_nsset(struct nsset *nsset)
499 {
500         unsigned flags = nsset->flags;
501         struct task_struct *me = current;
502
503 #ifdef CONFIG_USER_NS
504         if (flags & CLONE_NEWUSER) {
505                 /* transfer ownership */
506                 commit_creds(nsset_cred(nsset));
507                 nsset->cred = NULL;
508         }
509 #endif
510
511         /* We only need to commit if we have used a temporary fs_struct. */
512         if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
513                 set_fs_root(me->fs, &nsset->fs->root);
514                 set_fs_pwd(me->fs, &nsset->fs->pwd);
515         }
516
517 #ifdef CONFIG_IPC_NS
518         if (flags & CLONE_NEWIPC)
519                 exit_sem(me);
520 #endif
521
522 #ifdef CONFIG_TIME_NS
523         if (flags & CLONE_NEWTIME)
524                 timens_commit(me, nsset->nsproxy->time_ns);
525 #endif
526
527         /* transfer ownership */
528         switch_task_namespaces(me, nsset->nsproxy);
529         nsset->nsproxy = NULL;
530 }
531
532 SYSCALL_DEFINE2(setns, int, fd, int, flags)
533 {
534         struct file *file;
535         struct ns_common *ns = NULL;
536         struct nsset nsset = {};
537         int err = 0;
538
539         file = fget(fd);
540         if (!file)
541                 return -EBADF;
542
543         if (proc_ns_file(file)) {
544                 ns = get_proc_ns(file_inode(file));
545                 if (flags && (ns->ops->type != flags))
546                         err = -EINVAL;
547                 flags = ns->ops->type;
548         } else if (!IS_ERR(pidfd_pid(file))) {
549                 err = check_setns_flags(flags);
550         } else {
551                 err = -EINVAL;
552         }
553         if (err)
554                 goto out;
555
556         err = prepare_nsset(flags, &nsset);
557         if (err)
558                 goto out;
559
560         if (proc_ns_file(file))
561                 err = validate_ns(&nsset, ns);
562         else
563                 err = validate_nsset(&nsset, file->private_data);
564         if (!err) {
565                 commit_nsset(&nsset);
566                 perf_event_namespaces(current);
567         }
568         put_nsset(&nsset);
569 out:
570         fput(file);
571         return err;
572 }
573
574 int __init nsproxy_cache_init(void)
575 {
576         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
577         return 0;
578 }