1/*
  2 * Pid namespaces
  3 *
  4 * Authors:
  5 *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
  6 *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
  7 *     Many thanks to Oleg Nesterov for comments and help
  8 *
  9 */
 10
 11#include <linux/pid.h>
 12#include <linux/pid_namespace.h>
 13#include <linux/user_namespace.h>
 14#include <linux/syscalls.h>
 
 15#include <linux/err.h>
 16#include <linux/acct.h>
 17#include <linux/slab.h>
 18#include <linux/proc_ns.h>
 19#include <linux/reboot.h>
 20#include <linux/export.h>
 
 
 
 
 
 21
 22struct pid_cache {
 23	int nr_ids;
 24	char name[16];
 25	struct kmem_cache *cachep;
 26	struct list_head list;
 27};
 28
 29static LIST_HEAD(pid_caches_lh);
 30static DEFINE_MUTEX(pid_caches_mutex);
 31static struct kmem_cache *pid_ns_cachep;
 
 
 32
 33/*
 34 * creates the kmem cache to allocate pids from.
 35 * @nr_ids: the number of numerical ids this pid will have to carry
 36 */
 37
 38static struct kmem_cache *create_pid_cachep(int nr_ids)
 39{
 40	struct pid_cache *pcache;
 41	struct kmem_cache *cachep;
 
 
 
 
 
 
 
 42
 
 
 43	mutex_lock(&pid_caches_mutex);
 44	list_for_each_entry(pcache, &pid_caches_lh, list)
 45		if (pcache->nr_ids == nr_ids)
 46			goto out;
 47
 48	pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
 49	if (pcache == NULL)
 50		goto err_alloc;
 51
 52	snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
 53	cachep = kmem_cache_create(pcache->name,
 54			sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
 55			0, SLAB_HWCACHE_ALIGN, NULL);
 56	if (cachep == NULL)
 57		goto err_cachep;
 58
 59	pcache->nr_ids = nr_ids;
 60	pcache->cachep = cachep;
 61	list_add(&pcache->list, &pid_caches_lh);
 62out:
 63	mutex_unlock(&pid_caches_mutex);
 64	return pcache->cachep;
 65
 66err_cachep:
 67	kfree(pcache);
 68err_alloc:
 69	mutex_unlock(&pid_caches_mutex);
 70	return NULL;
 
 71}
 72
 73static void proc_cleanup_work(struct work_struct *work)
 74{
 75	struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
 76	pid_ns_release_proc(ns);
 77}
 78
 79/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
 80#define MAX_PID_NS_LEVEL 32
 
 
 81
 82static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
 83	struct pid_namespace *parent_pid_ns)
 84{
 85	struct pid_namespace *ns;
 86	unsigned int level = parent_pid_ns->level + 1;
 87	int i;
 88	int err;
 89
 90	if (level > MAX_PID_NS_LEVEL) {
 91		err = -EINVAL;
 
 
 
 
 
 
 
 92		goto out;
 93	}
 94
 95	err = -ENOMEM;
 96	ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
 97	if (ns == NULL)
 98		goto out;
 99
100	ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
101	if (!ns->pidmap[0].page)
102		goto out_free;
103
104	ns->pid_cachep = create_pid_cachep(level + 1);
105	if (ns->pid_cachep == NULL)
106		goto out_free_map;
107
108	err = ns_alloc_inum(&ns->ns);
109	if (err)
110		goto out_free_map;
111	ns->ns.ops = &pidns_operations;
112
113	kref_init(&ns->kref);
114	ns->level = level;
115	ns->parent = get_pid_ns(parent_pid_ns);
116	ns->user_ns = get_user_ns(user_ns);
117	ns->nr_hashed = PIDNS_HASH_ADDING;
118	INIT_WORK(&ns->proc_work, proc_cleanup_work);
119
120	set_bit(0, ns->pidmap[0].page);
121	atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
122
123	for (i = 1; i < PIDMAP_ENTRIES; i++)
124		atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
125
126	return ns;
127
128out_free_map:
129	kfree(ns->pidmap[0].page);
130out_free:
131	kmem_cache_free(pid_ns_cachep, ns);
 
 
132out:
133	return ERR_PTR(err);
134}
135
136static void delayed_free_pidns(struct rcu_head *p)
137{
138	kmem_cache_free(pid_ns_cachep,
139			container_of(p, struct pid_namespace, rcu));
 
 
 
 
140}
141
142static void destroy_pid_namespace(struct pid_namespace *ns)
143{
144	int i;
145
146	ns_free_inum(&ns->ns);
147	for (i = 0; i < PIDMAP_ENTRIES; i++)
148		kfree(ns->pidmap[i].page);
149	put_user_ns(ns->user_ns);
150	call_rcu(&ns->rcu, delayed_free_pidns);
151}
152
153struct pid_namespace *copy_pid_ns(unsigned long flags,
154	struct user_namespace *user_ns, struct pid_namespace *old_ns)
155{
156	if (!(flags & CLONE_NEWPID))
157		return get_pid_ns(old_ns);
158	if (task_active_pid_ns(current) != old_ns)
159		return ERR_PTR(-EINVAL);
160	return create_pid_namespace(user_ns, old_ns);
161}
162
163static void free_pid_ns(struct kref *kref)
164{
165	struct pid_namespace *ns;
166
167	ns = container_of(kref, struct pid_namespace, kref);
168	destroy_pid_namespace(ns);
169}
170
171void put_pid_ns(struct pid_namespace *ns)
172{
173	struct pid_namespace *parent;
174
175	while (ns != &init_pid_ns) {
176		parent = ns->parent;
177		if (!kref_put(&ns->kref, free_pid_ns))
178			break;
 
179		ns = parent;
180	}
181}
182EXPORT_SYMBOL_GPL(put_pid_ns);
183
184void zap_pid_ns_processes(struct pid_namespace *pid_ns)
185{
186	int nr;
187	int rc;
188	struct task_struct *task, *me = current;
189	int init_pids = thread_group_leader(me) ? 1 : 2;
 
190
191	/* Don't allow any more processes into the pid namespace */
192	disable_pid_allocation(pid_ns);
193
194	/*
195	 * Ignore SIGCHLD causing any terminated children to autoreap.
196	 * This speeds up the namespace shutdown, plus see the comment
197	 * below.
198	 */
199	spin_lock_irq(&me->sighand->siglock);
200	me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
201	spin_unlock_irq(&me->sighand->siglock);
202
203	/*
204	 * The last thread in the cgroup-init thread group is terminating.
205	 * Find remaining pid_ts in the namespace, signal and wait for them
206	 * to exit.
207	 *
208	 * Note:  This signals each threads in the namespace - even those that
209	 * 	  belong to the same thread group, To avoid this, we would have
210	 * 	  to walk the entire tasklist looking a processes in this
211	 * 	  namespace, but that could be unnecessarily expensive if the
212	 * 	  pid namespace has just a few processes. Or we need to
213	 * 	  maintain a tasklist for each pid namespace.
214	 *
215	 */
 
216	read_lock(&tasklist_lock);
217	nr = next_pidmap(pid_ns, 1);
218	while (nr > 0) {
219		rcu_read_lock();
220
221		task = pid_task(find_vpid(nr), PIDTYPE_PID);
222		if (task && !__fatal_signal_pending(task))
223			send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
224
225		rcu_read_unlock();
226
227		nr = next_pidmap(pid_ns, nr);
228	}
229	read_unlock(&tasklist_lock);
 
230
231	/*
232	 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
233	 * sys_wait4() will also block until our children traced from the
234	 * parent namespace are detached and become EXIT_DEAD.
235	 */
236	do {
237		clear_thread_flag(TIF_SIGPENDING);
238		rc = sys_wait4(-1, NULL, __WALL, NULL);
 
239	} while (rc != -ECHILD);
240
241	/*
242	 * sys_wait4() above can't reap the EXIT_DEAD children but we do not
243	 * really care, we could reparent them to the global init. We could
244	 * exit and reap ->child_reaper even if it is not the last thread in
245	 * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
246	 * pid_ns can not go away until proc_kill_sb() drops the reference.
247	 *
248	 * But this ns can also have other tasks injected by setns()+fork().
249	 * Again, ignoring the user visible semantics we do not really need
250	 * to wait until they are all reaped, but they can be reparented to
251	 * us and thus we need to ensure that pid->child_reaper stays valid
252	 * until they all go away. See free_pid()->wake_up_process().
253	 *
254	 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
255	 * if reparented.
 
 
 
 
 
 
 
 
 
 
256	 */
257	for (;;) {
258		set_current_state(TASK_UNINTERRUPTIBLE);
259		if (pid_ns->nr_hashed == init_pids)
260			break;
261		schedule();
262	}
263	__set_current_state(TASK_RUNNING);
264
265	if (pid_ns->reboot)
266		current->signal->group_exit_code = pid_ns->reboot;
267
268	acct_exit_ns(pid_ns);
269	return;
270}
271
272#ifdef CONFIG_CHECKPOINT_RESTORE
273static int pid_ns_ctl_handler(struct ctl_table *table, int write,
274		void __user *buffer, size_t *lenp, loff_t *ppos)
275{
276	struct pid_namespace *pid_ns = task_active_pid_ns(current);
277	struct ctl_table tmp = *table;
 
278
279	if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
280		return -EPERM;
281
282	/*
283	 * Writing directly to ns' last_pid field is OK, since this field
284	 * is volatile in a living namespace anyway and a code writing to
285	 * it should synchronize its usage with external means.
286	 */
 
287
288	tmp.data = &pid_ns->last_pid;
289	return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
290}
291
292extern int pid_max;
293static int zero = 0;
294static struct ctl_table pid_ns_ctl_table[] = {
295	{
296		.procname = "ns_last_pid",
297		.maxlen = sizeof(int),
298		.mode = 0666, /* permissions are checked in the handler */
299		.proc_handler = pid_ns_ctl_handler,
300		.extra1 = &zero,
301		.extra2 = &pid_max,
302	},
303	{ }
304};
305static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
306#endif	/* CONFIG_CHECKPOINT_RESTORE */
307
308int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
309{
310	if (pid_ns == &init_pid_ns)
311		return 0;
312
313	switch (cmd) {
314	case LINUX_REBOOT_CMD_RESTART2:
315	case LINUX_REBOOT_CMD_RESTART:
316		pid_ns->reboot = SIGHUP;
317		break;
318
319	case LINUX_REBOOT_CMD_POWER_OFF:
320	case LINUX_REBOOT_CMD_HALT:
321		pid_ns->reboot = SIGINT;
322		break;
323	default:
324		return -EINVAL;
325	}
326
327	read_lock(&tasklist_lock);
328	force_sig(SIGKILL, pid_ns->child_reaper);
329	read_unlock(&tasklist_lock);
330
331	do_exit(0);
332
333	/* Not reached */
334	return 0;
335}
336
337static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
338{
339	return container_of(ns, struct pid_namespace, ns);
340}
341
342static struct ns_common *pidns_get(struct task_struct *task)
343{
344	struct pid_namespace *ns;
345
346	rcu_read_lock();
347	ns = task_active_pid_ns(task);
348	if (ns)
349		get_pid_ns(ns);
350	rcu_read_unlock();
351
352	return ns ? &ns->ns : NULL;
353}
354
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
355static void pidns_put(struct ns_common *ns)
356{
357	put_pid_ns(to_pid_ns(ns));
358}
359
360static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
361{
 
362	struct pid_namespace *active = task_active_pid_ns(current);
363	struct pid_namespace *ancestor, *new = to_pid_ns(ns);
364
365	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
366	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
367		return -EPERM;
368
369	/*
370	 * Only allow entering the current active pid namespace
371	 * or a child of the current active pid namespace.
372	 *
373	 * This is required for fork to return a usable pid value and
374	 * this maintains the property that processes and their
375	 * children can not escape their current pid namespace.
376	 */
377	if (new->level < active->level)
378		return -EINVAL;
379
380	ancestor = new;
381	while (ancestor->level > active->level)
382		ancestor = ancestor->parent;
383	if (ancestor != active)
384		return -EINVAL;
385
386	put_pid_ns(nsproxy->pid_ns_for_children);
387	nsproxy->pid_ns_for_children = get_pid_ns(new);
388	return 0;
389}
390
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
391const struct proc_ns_operations pidns_operations = {
392	.name		= "pid",
393	.type		= CLONE_NEWPID,
394	.get		= pidns_get,
395	.put		= pidns_put,
396	.install	= pidns_install,
 
 
 
 
 
 
 
 
 
 
 
 
 
397};
398
399static __init int pid_namespaces_init(void)
400{
401	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
402
403#ifdef CONFIG_CHECKPOINT_RESTORE
404	register_sysctl_paths(kern_path, pid_ns_ctl_table);
405#endif
 
 
406	return 0;
407}
408
409__initcall(pid_namespaces_init);

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Pid namespaces
  4 *
  5 * Authors:
  6 *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
  7 *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
  8 *     Many thanks to Oleg Nesterov for comments and help
  9 *
 10 */
 11
 12#include <linux/pid.h>
 13#include <linux/pid_namespace.h>
 14#include <linux/user_namespace.h>
 15#include <linux/syscalls.h>
 16#include <linux/cred.h>
 17#include <linux/err.h>
 18#include <linux/acct.h>
 19#include <linux/slab.h>
 20#include <linux/proc_ns.h>
 21#include <linux/reboot.h>
 22#include <linux/export.h>
 23#include <linux/sched/task.h>
 24#include <linux/sched/signal.h>
 25#include <linux/idr.h>
 26#include <uapi/linux/wait.h>
 27#include "pid_sysctl.h"
 28
 
 
 
 
 
 
 
 
 29static DEFINE_MUTEX(pid_caches_mutex);
 30static struct kmem_cache *pid_ns_cachep;
 31/* Write once array, filled from the beginning. */
 32static struct kmem_cache *pid_cache[MAX_PID_NS_LEVEL];
 33
 34/*
 35 * creates the kmem cache to allocate pids from.
 36 * @level: pid namespace level
 37 */
 38
 39static struct kmem_cache *create_pid_cachep(unsigned int level)
 40{
 41	/* Level 0 is init_pid_ns.pid_cachep */
 42	struct kmem_cache **pkc = &pid_cache[level - 1];
 43	struct kmem_cache *kc;
 44	char name[4 + 10 + 1];
 45	unsigned int len;
 46
 47	kc = READ_ONCE(*pkc);
 48	if (kc)
 49		return kc;
 50
 51	snprintf(name, sizeof(name), "pid_%u", level + 1);
 52	len = struct_size_t(struct pid, numbers, level + 1);
 53	mutex_lock(&pid_caches_mutex);
 54	/* Name collision forces to do allocation under mutex. */
 55	if (!*pkc)
 56		*pkc = kmem_cache_create(name, len, 0,
 57					 SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 58	mutex_unlock(&pid_caches_mutex);
 59	/* current can fail, but someone else can succeed. */
 60	return READ_ONCE(*pkc);
 61}
 62
 63static struct ucounts *inc_pid_namespaces(struct user_namespace *ns)
 64{
 65	return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
 
 66}
 67
 68static void dec_pid_namespaces(struct ucounts *ucounts)
 69{
 70	dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
 71}
 72
 73static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
 74	struct pid_namespace *parent_pid_ns)
 75{
 76	struct pid_namespace *ns;
 77	unsigned int level = parent_pid_ns->level + 1;
 78	struct ucounts *ucounts;
 79	int err;
 80
 81	err = -EINVAL;
 82	if (!in_userns(parent_pid_ns->user_ns, user_ns))
 83		goto out;
 84
 85	err = -ENOSPC;
 86	if (level > MAX_PID_NS_LEVEL)
 87		goto out;
 88	ucounts = inc_pid_namespaces(user_ns);
 89	if (!ucounts)
 90		goto out;
 
 91
 92	err = -ENOMEM;
 93	ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
 94	if (ns == NULL)
 95		goto out_dec;
 96
 97	idr_init(&ns->idr);
 
 
 98
 99	ns->pid_cachep = create_pid_cachep(level);
100	if (ns->pid_cachep == NULL)
101		goto out_free_idr;
102
103	err = ns_alloc_inum(&ns->ns);
104	if (err)
105		goto out_free_idr;
106	ns->ns.ops = &pidns_operations;
107
108	refcount_set(&ns->ns.count, 1);
109	ns->level = level;
110	ns->parent = get_pid_ns(parent_pid_ns);
111	ns->user_ns = get_user_ns(user_ns);
112	ns->ucounts = ucounts;
113	ns->pid_allocated = PIDNS_ADDING;
114#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
115	ns->memfd_noexec_scope = pidns_memfd_noexec_scope(parent_pid_ns);
116#endif
 
 
 
 
117	return ns;
118
119out_free_idr:
120	idr_destroy(&ns->idr);
 
121	kmem_cache_free(pid_ns_cachep, ns);
122out_dec:
123	dec_pid_namespaces(ucounts);
124out:
125	return ERR_PTR(err);
126}
127
128static void delayed_free_pidns(struct rcu_head *p)
129{
130	struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
131
132	dec_pid_namespaces(ns->ucounts);
133	put_user_ns(ns->user_ns);
134
135	kmem_cache_free(pid_ns_cachep, ns);
136}
137
138static void destroy_pid_namespace(struct pid_namespace *ns)
139{
 
 
140	ns_free_inum(&ns->ns);
141
142	idr_destroy(&ns->idr);
 
143	call_rcu(&ns->rcu, delayed_free_pidns);
144}
145
146struct pid_namespace *copy_pid_ns(unsigned long flags,
147	struct user_namespace *user_ns, struct pid_namespace *old_ns)
148{
149	if (!(flags & CLONE_NEWPID))
150		return get_pid_ns(old_ns);
151	if (task_active_pid_ns(current) != old_ns)
152		return ERR_PTR(-EINVAL);
153	return create_pid_namespace(user_ns, old_ns);
154}
155
 
 
 
 
 
 
 
 
156void put_pid_ns(struct pid_namespace *ns)
157{
158	struct pid_namespace *parent;
159
160	while (ns != &init_pid_ns) {
161		parent = ns->parent;
162		if (!refcount_dec_and_test(&ns->ns.count))
163			break;
164		destroy_pid_namespace(ns);
165		ns = parent;
166	}
167}
168EXPORT_SYMBOL_GPL(put_pid_ns);
169
170void zap_pid_ns_processes(struct pid_namespace *pid_ns)
171{
172	int nr;
173	int rc;
174	struct task_struct *task, *me = current;
175	int init_pids = thread_group_leader(me) ? 1 : 2;
176	struct pid *pid;
177
178	/* Don't allow any more processes into the pid namespace */
179	disable_pid_allocation(pid_ns);
180
181	/*
182	 * Ignore SIGCHLD causing any terminated children to autoreap.
183	 * This speeds up the namespace shutdown, plus see the comment
184	 * below.
185	 */
186	spin_lock_irq(&me->sighand->siglock);
187	me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
188	spin_unlock_irq(&me->sighand->siglock);
189
190	/*
191	 * The last thread in the cgroup-init thread group is terminating.
192	 * Find remaining pid_ts in the namespace, signal and wait for them
193	 * to exit.
194	 *
195	 * Note:  This signals each threads in the namespace - even those that
196	 * 	  belong to the same thread group, To avoid this, we would have
197	 * 	  to walk the entire tasklist looking a processes in this
198	 * 	  namespace, but that could be unnecessarily expensive if the
199	 * 	  pid namespace has just a few processes. Or we need to
200	 * 	  maintain a tasklist for each pid namespace.
201	 *
202	 */
203	rcu_read_lock();
204	read_lock(&tasklist_lock);
205	nr = 2;
206	idr_for_each_entry_continue(&pid_ns->idr, pid, nr) {
207		task = pid_task(pid, PIDTYPE_PID);
 
 
208		if (task && !__fatal_signal_pending(task))
209			group_send_sig_info(SIGKILL, SEND_SIG_PRIV, task, PIDTYPE_MAX);
 
 
 
 
210	}
211	read_unlock(&tasklist_lock);
212	rcu_read_unlock();
213
214	/*
215	 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
216	 * kernel_wait4() will also block until our children traced from the
217	 * parent namespace are detached and become EXIT_DEAD.
218	 */
219	do {
220		clear_thread_flag(TIF_SIGPENDING);
221		clear_thread_flag(TIF_NOTIFY_SIGNAL);
222		rc = kernel_wait4(-1, NULL, __WALL, NULL);
223	} while (rc != -ECHILD);
224
225	/*
226	 * kernel_wait4() misses EXIT_DEAD children, and EXIT_ZOMBIE
227	 * process whose parents processes are outside of the pid
228	 * namespace.  Such processes are created with setns()+fork().
 
 
229	 *
230	 * If those EXIT_ZOMBIE processes are not reaped by their
231	 * parents before their parents exit, they will be reparented
232	 * to pid_ns->child_reaper.  Thus pidns->child_reaper needs to
233	 * stay valid until they all go away.
 
234	 *
235	 * The code relies on the pid_ns->child_reaper ignoring
236	 * SIGCHILD to cause those EXIT_ZOMBIE processes to be
237	 * autoreaped if reparented.
238	 *
239	 * Semantically it is also desirable to wait for EXIT_ZOMBIE
240	 * processes before allowing the child_reaper to be reaped, as
241	 * that gives the invariant that when the init process of a
242	 * pid namespace is reaped all of the processes in the pid
243	 * namespace are gone.
244	 *
245	 * Once all of the other tasks are gone from the pid_namespace
246	 * free_pid() will awaken this task.
247	 */
248	for (;;) {
249		set_current_state(TASK_INTERRUPTIBLE);
250		if (pid_ns->pid_allocated == init_pids)
251			break;
252		schedule();
253	}
254	__set_current_state(TASK_RUNNING);
255
256	if (pid_ns->reboot)
257		current->signal->group_exit_code = pid_ns->reboot;
258
259	acct_exit_ns(pid_ns);
260	return;
261}
262
263#ifdef CONFIG_CHECKPOINT_RESTORE
264static int pid_ns_ctl_handler(const struct ctl_table *table, int write,
265		void *buffer, size_t *lenp, loff_t *ppos)
266{
267	struct pid_namespace *pid_ns = task_active_pid_ns(current);
268	struct ctl_table tmp = *table;
269	int ret, next;
270
271	if (write && !checkpoint_restore_ns_capable(pid_ns->user_ns))
272		return -EPERM;
273
274	next = idr_get_cursor(&pid_ns->idr) - 1;
275
276	tmp.data = &next;
277	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
278	if (!ret && write)
279		idr_set_cursor(&pid_ns->idr, next + 1);
280
281	return ret;
 
282}
283
284extern int pid_max;
 
285static struct ctl_table pid_ns_ctl_table[] = {
286	{
287		.procname = "ns_last_pid",
288		.maxlen = sizeof(int),
289		.mode = 0666, /* permissions are checked in the handler */
290		.proc_handler = pid_ns_ctl_handler,
291		.extra1 = SYSCTL_ZERO,
292		.extra2 = &pid_max,
293	},
 
294};
 
295#endif	/* CONFIG_CHECKPOINT_RESTORE */
296
297int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
298{
299	if (pid_ns == &init_pid_ns)
300		return 0;
301
302	switch (cmd) {
303	case LINUX_REBOOT_CMD_RESTART2:
304	case LINUX_REBOOT_CMD_RESTART:
305		pid_ns->reboot = SIGHUP;
306		break;
307
308	case LINUX_REBOOT_CMD_POWER_OFF:
309	case LINUX_REBOOT_CMD_HALT:
310		pid_ns->reboot = SIGINT;
311		break;
312	default:
313		return -EINVAL;
314	}
315
316	read_lock(&tasklist_lock);
317	send_sig(SIGKILL, pid_ns->child_reaper, 1);
318	read_unlock(&tasklist_lock);
319
320	do_exit(0);
321
322	/* Not reached */
323	return 0;
324}
325
326static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
327{
328	return container_of(ns, struct pid_namespace, ns);
329}
330
331static struct ns_common *pidns_get(struct task_struct *task)
332{
333	struct pid_namespace *ns;
334
335	rcu_read_lock();
336	ns = task_active_pid_ns(task);
337	if (ns)
338		get_pid_ns(ns);
339	rcu_read_unlock();
340
341	return ns ? &ns->ns : NULL;
342}
343
344static struct ns_common *pidns_for_children_get(struct task_struct *task)
345{
346	struct pid_namespace *ns = NULL;
347
348	task_lock(task);
349	if (task->nsproxy) {
350		ns = task->nsproxy->pid_ns_for_children;
351		get_pid_ns(ns);
352	}
353	task_unlock(task);
354
355	if (ns) {
356		read_lock(&tasklist_lock);
357		if (!ns->child_reaper) {
358			put_pid_ns(ns);
359			ns = NULL;
360		}
361		read_unlock(&tasklist_lock);
362	}
363
364	return ns ? &ns->ns : NULL;
365}
366
367static void pidns_put(struct ns_common *ns)
368{
369	put_pid_ns(to_pid_ns(ns));
370}
371
372static int pidns_install(struct nsset *nsset, struct ns_common *ns)
373{
374	struct nsproxy *nsproxy = nsset->nsproxy;
375	struct pid_namespace *active = task_active_pid_ns(current);
376	struct pid_namespace *ancestor, *new = to_pid_ns(ns);
377
378	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
379	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
380		return -EPERM;
381
382	/*
383	 * Only allow entering the current active pid namespace
384	 * or a child of the current active pid namespace.
385	 *
386	 * This is required for fork to return a usable pid value and
387	 * this maintains the property that processes and their
388	 * children can not escape their current pid namespace.
389	 */
390	if (new->level < active->level)
391		return -EINVAL;
392
393	ancestor = new;
394	while (ancestor->level > active->level)
395		ancestor = ancestor->parent;
396	if (ancestor != active)
397		return -EINVAL;
398
399	put_pid_ns(nsproxy->pid_ns_for_children);
400	nsproxy->pid_ns_for_children = get_pid_ns(new);
401	return 0;
402}
403
404static struct ns_common *pidns_get_parent(struct ns_common *ns)
405{
406	struct pid_namespace *active = task_active_pid_ns(current);
407	struct pid_namespace *pid_ns, *p;
408
409	/* See if the parent is in the current namespace */
410	pid_ns = p = to_pid_ns(ns)->parent;
411	for (;;) {
412		if (!p)
413			return ERR_PTR(-EPERM);
414		if (p == active)
415			break;
416		p = p->parent;
417	}
418
419	return &get_pid_ns(pid_ns)->ns;
420}
421
422static struct user_namespace *pidns_owner(struct ns_common *ns)
423{
424	return to_pid_ns(ns)->user_ns;
425}
426
427const struct proc_ns_operations pidns_operations = {
428	.name		= "pid",
429	.type		= CLONE_NEWPID,
430	.get		= pidns_get,
431	.put		= pidns_put,
432	.install	= pidns_install,
433	.owner		= pidns_owner,
434	.get_parent	= pidns_get_parent,
435};
436
437const struct proc_ns_operations pidns_for_children_operations = {
438	.name		= "pid_for_children",
439	.real_ns_name	= "pid",
440	.type		= CLONE_NEWPID,
441	.get		= pidns_for_children_get,
442	.put		= pidns_put,
443	.install	= pidns_install,
444	.owner		= pidns_owner,
445	.get_parent	= pidns_get_parent,
446};
447
448static __init int pid_namespaces_init(void)
449{
450	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC | SLAB_ACCOUNT);
451
452#ifdef CONFIG_CHECKPOINT_RESTORE
453	register_sysctl_init("kernel", pid_ns_ctl_table);
454#endif
455
456	register_pid_ns_sysctl_table_vm();
457	return 0;
458}
459
460__initcall(pid_namespaces_init);