ubsan: disable UBSAN_TRAP for all*config
[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
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         timens_on_fork(new_ns, tsk);
183
184         tsk->nsproxy = new_ns;
185         return 0;
186 }
187
188 void free_nsproxy(struct nsproxy *ns)
189 {
190         if (ns->mnt_ns)
191                 put_mnt_ns(ns->mnt_ns);
192         if (ns->uts_ns)
193                 put_uts_ns(ns->uts_ns);
194         if (ns->ipc_ns)
195                 put_ipc_ns(ns->ipc_ns);
196         if (ns->pid_ns_for_children)
197                 put_pid_ns(ns->pid_ns_for_children);
198         if (ns->time_ns)
199                 put_time_ns(ns->time_ns);
200         if (ns->time_ns_for_children)
201                 put_time_ns(ns->time_ns_for_children);
202         put_cgroup_ns(ns->cgroup_ns);
203         put_net(ns->net_ns);
204         kmem_cache_free(nsproxy_cachep, ns);
205 }
206
207 /*
208  * Called from unshare. Unshare all the namespaces part of nsproxy.
209  * On success, returns the new nsproxy.
210  */
211 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
212         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
213 {
214         struct user_namespace *user_ns;
215         int err = 0;
216
217         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
218                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP |
219                                CLONE_NEWTIME)))
220                 return 0;
221
222         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
223         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
224                 return -EPERM;
225
226         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
227                                          new_fs ? new_fs : current->fs);
228         if (IS_ERR(*new_nsp)) {
229                 err = PTR_ERR(*new_nsp);
230                 goto out;
231         }
232
233 out:
234         return err;
235 }
236
237 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
238 {
239         struct nsproxy *ns;
240
241         might_sleep();
242
243         task_lock(p);
244         ns = p->nsproxy;
245         p->nsproxy = new;
246         task_unlock(p);
247
248         if (ns)
249                 put_nsproxy(ns);
250 }
251
252 void exit_task_namespaces(struct task_struct *p)
253 {
254         switch_task_namespaces(p, NULL);
255 }
256
257 static int check_setns_flags(unsigned long flags)
258 {
259         if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
260                                  CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
261                                  CLONE_NEWPID | CLONE_NEWCGROUP)))
262                 return -EINVAL;
263
264 #ifndef CONFIG_USER_NS
265         if (flags & CLONE_NEWUSER)
266                 return -EINVAL;
267 #endif
268 #ifndef CONFIG_PID_NS
269         if (flags & CLONE_NEWPID)
270                 return -EINVAL;
271 #endif
272 #ifndef CONFIG_UTS_NS
273         if (flags & CLONE_NEWUTS)
274                 return -EINVAL;
275 #endif
276 #ifndef CONFIG_IPC_NS
277         if (flags & CLONE_NEWIPC)
278                 return -EINVAL;
279 #endif
280 #ifndef CONFIG_CGROUPS
281         if (flags & CLONE_NEWCGROUP)
282                 return -EINVAL;
283 #endif
284 #ifndef CONFIG_NET_NS
285         if (flags & CLONE_NEWNET)
286                 return -EINVAL;
287 #endif
288 #ifndef CONFIG_TIME_NS
289         if (flags & CLONE_NEWTIME)
290                 return -EINVAL;
291 #endif
292
293         return 0;
294 }
295
296 static void put_nsset(struct nsset *nsset)
297 {
298         unsigned flags = nsset->flags;
299
300         if (flags & CLONE_NEWUSER)
301                 put_cred(nsset_cred(nsset));
302         /*
303          * We only created a temporary copy if we attached to more than just
304          * the mount namespace.
305          */
306         if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS))
307                 free_fs_struct(nsset->fs);
308         if (nsset->nsproxy)
309                 free_nsproxy(nsset->nsproxy);
310 }
311
312 static int prepare_nsset(unsigned flags, struct nsset *nsset)
313 {
314         struct task_struct *me = current;
315
316         nsset->nsproxy = create_new_namespaces(0, me, current_user_ns(), me->fs);
317         if (IS_ERR(nsset->nsproxy))
318                 return PTR_ERR(nsset->nsproxy);
319
320         if (flags & CLONE_NEWUSER)
321                 nsset->cred = prepare_creds();
322         else
323                 nsset->cred = current_cred();
324         if (!nsset->cred)
325                 goto out;
326
327         /* Only create a temporary copy of fs_struct if we really need to. */
328         if (flags == CLONE_NEWNS) {
329                 nsset->fs = me->fs;
330         } else if (flags & CLONE_NEWNS) {
331                 nsset->fs = copy_fs_struct(me->fs);
332                 if (!nsset->fs)
333                         goto out;
334         }
335
336         nsset->flags = flags;
337         return 0;
338
339 out:
340         put_nsset(nsset);
341         return -ENOMEM;
342 }
343
344 static inline int validate_ns(struct nsset *nsset, struct ns_common *ns)
345 {
346         return ns->ops->install(nsset, ns);
347 }
348
349 /*
350  * This is the inverse operation to unshare().
351  * Ordering is equivalent to the standard ordering used everywhere else
352  * during unshare and process creation. The switch to the new set of
353  * namespaces occurs at the point of no return after installation of
354  * all requested namespaces was successful in commit_nsset().
355  */
356 static int validate_nsset(struct nsset *nsset, struct pid *pid)
357 {
358         int ret = 0;
359         unsigned flags = nsset->flags;
360         struct user_namespace *user_ns = NULL;
361         struct pid_namespace *pid_ns = NULL;
362         struct nsproxy *nsp;
363         struct task_struct *tsk;
364
365         /* Take a "snapshot" of the target task's namespaces. */
366         rcu_read_lock();
367         tsk = pid_task(pid, PIDTYPE_PID);
368         if (!tsk) {
369                 rcu_read_unlock();
370                 return -ESRCH;
371         }
372
373         if (!ptrace_may_access(tsk, PTRACE_MODE_READ_REALCREDS)) {
374                 rcu_read_unlock();
375                 return -EPERM;
376         }
377
378         task_lock(tsk);
379         nsp = tsk->nsproxy;
380         if (nsp)
381                 get_nsproxy(nsp);
382         task_unlock(tsk);
383         if (!nsp) {
384                 rcu_read_unlock();
385                 return -ESRCH;
386         }
387
388 #ifdef CONFIG_PID_NS
389         if (flags & CLONE_NEWPID) {
390                 pid_ns = task_active_pid_ns(tsk);
391                 if (unlikely(!pid_ns)) {
392                         rcu_read_unlock();
393                         ret = -ESRCH;
394                         goto out;
395                 }
396                 get_pid_ns(pid_ns);
397         }
398 #endif
399
400 #ifdef CONFIG_USER_NS
401         if (flags & CLONE_NEWUSER)
402                 user_ns = get_user_ns(__task_cred(tsk)->user_ns);
403 #endif
404         rcu_read_unlock();
405
406         /*
407          * Install requested namespaces. The caller will have
408          * verified earlier that the requested namespaces are
409          * supported on this kernel. We don't report errors here
410          * if a namespace is requested that isn't supported.
411          */
412 #ifdef CONFIG_USER_NS
413         if (flags & CLONE_NEWUSER) {
414                 ret = validate_ns(nsset, &user_ns->ns);
415                 if (ret)
416                         goto out;
417         }
418 #endif
419
420         if (flags & CLONE_NEWNS) {
421                 ret = validate_ns(nsset, from_mnt_ns(nsp->mnt_ns));
422                 if (ret)
423                         goto out;
424         }
425
426 #ifdef CONFIG_UTS_NS
427         if (flags & CLONE_NEWUTS) {
428                 ret = validate_ns(nsset, &nsp->uts_ns->ns);
429                 if (ret)
430                         goto out;
431         }
432 #endif
433
434 #ifdef CONFIG_IPC_NS
435         if (flags & CLONE_NEWIPC) {
436                 ret = validate_ns(nsset, &nsp->ipc_ns->ns);
437                 if (ret)
438                         goto out;
439         }
440 #endif
441
442 #ifdef CONFIG_PID_NS
443         if (flags & CLONE_NEWPID) {
444                 ret = validate_ns(nsset, &pid_ns->ns);
445                 if (ret)
446                         goto out;
447         }
448 #endif
449
450 #ifdef CONFIG_CGROUPS
451         if (flags & CLONE_NEWCGROUP) {
452                 ret = validate_ns(nsset, &nsp->cgroup_ns->ns);
453                 if (ret)
454                         goto out;
455         }
456 #endif
457
458 #ifdef CONFIG_NET_NS
459         if (flags & CLONE_NEWNET) {
460                 ret = validate_ns(nsset, &nsp->net_ns->ns);
461                 if (ret)
462                         goto out;
463         }
464 #endif
465
466 #ifdef CONFIG_TIME_NS
467         if (flags & CLONE_NEWTIME) {
468                 ret = validate_ns(nsset, &nsp->time_ns->ns);
469                 if (ret)
470                         goto out;
471         }
472 #endif
473
474 out:
475         if (pid_ns)
476                 put_pid_ns(pid_ns);
477         if (nsp)
478                 put_nsproxy(nsp);
479         put_user_ns(user_ns);
480
481         return ret;
482 }
483
484 /*
485  * This is the point of no return. There are just a few namespaces
486  * that do some actual work here and it's sufficiently minimal that
487  * a separate ns_common operation seems unnecessary for now.
488  * Unshare is doing the same thing. If we'll end up needing to do
489  * more in a given namespace or a helper here is ultimately not
490  * exported anymore a simple commit handler for each namespace
491  * should be added to ns_common.
492  */
493 static void commit_nsset(struct nsset *nsset)
494 {
495         unsigned flags = nsset->flags;
496         struct task_struct *me = current;
497
498 #ifdef CONFIG_USER_NS
499         if (flags & CLONE_NEWUSER) {
500                 /* transfer ownership */
501                 commit_creds(nsset_cred(nsset));
502                 nsset->cred = NULL;
503         }
504 #endif
505
506         /* We only need to commit if we have used a temporary fs_struct. */
507         if ((flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) {
508                 set_fs_root(me->fs, &nsset->fs->root);
509                 set_fs_pwd(me->fs, &nsset->fs->pwd);
510         }
511
512 #ifdef CONFIG_IPC_NS
513         if (flags & CLONE_NEWIPC)
514                 exit_sem(me);
515 #endif
516
517 #ifdef CONFIG_TIME_NS
518         if (flags & CLONE_NEWTIME)
519                 timens_commit(me, nsset->nsproxy->time_ns);
520 #endif
521
522         /* transfer ownership */
523         switch_task_namespaces(me, nsset->nsproxy);
524         nsset->nsproxy = NULL;
525 }
526
527 SYSCALL_DEFINE2(setns, int, fd, int, flags)
528 {
529         struct file *file;
530         struct ns_common *ns = NULL;
531         struct nsset nsset = {};
532         int err = 0;
533
534         file = fget(fd);
535         if (!file)
536                 return -EBADF;
537
538         if (proc_ns_file(file)) {
539                 ns = get_proc_ns(file_inode(file));
540                 if (flags && (ns->ops->type != flags))
541                         err = -EINVAL;
542                 flags = ns->ops->type;
543         } else if (!IS_ERR(pidfd_pid(file))) {
544                 err = check_setns_flags(flags);
545         } else {
546                 err = -EINVAL;
547         }
548         if (err)
549                 goto out;
550
551         err = prepare_nsset(flags, &nsset);
552         if (err)
553                 goto out;
554
555         if (proc_ns_file(file))
556                 err = validate_ns(&nsset, ns);
557         else
558                 err = validate_nsset(&nsset, file->private_data);
559         if (!err) {
560                 commit_nsset(&nsset);
561                 perf_event_namespaces(current);
562         }
563         put_nsset(&nsset);
564 out:
565         fput(file);
566         return err;
567 }
568
569 int __init nsproxy_cache_init(void)
570 {
571         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
572         return 0;
573 }