[mirror_ubuntu-bionic-kernel.git] / kernel / pid_namespace.c

/*
 * Pid namespaces
 *
 * Authors:
 *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
 *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
 *     Many thanks to Oleg Nesterov for comments and help
 *
 */

#include <linux/pid.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <linux/syscalls.h>
#include <linux/cred.h>
#include <linux/err.h>
#include <linux/acct.h>
#include <linux/slab.h>
#include <linux/proc_ns.h>
#include <linux/reboot.h>
#include <linux/export.h>
#include <linux/sched/task.h>

struct pid_cache {
	int nr_ids;
	char name[16];
	struct kmem_cache *cachep;
	struct list_head list;
};

static LIST_HEAD(pid_caches_lh);
static DEFINE_MUTEX(pid_caches_mutex);
static struct kmem_cache *pid_ns_cachep;

/*
 * creates the kmem cache to allocate pids from.
 * @nr_ids: the number of numerical ids this pid will have to carry
 */

static struct kmem_cache *create_pid_cachep(int nr_ids)
{
	struct pid_cache *pcache;
	struct kmem_cache *cachep;

	mutex_lock(&pid_caches_mutex);
	list_for_each_entry(pcache, &pid_caches_lh, list)
		if (pcache->nr_ids == nr_ids)
			goto out;

	pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
	if (pcache == NULL)
		goto err_alloc;

	snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
	cachep = kmem_cache_create(pcache->name,
			sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
			0, SLAB_HWCACHE_ALIGN, NULL);
	if (cachep == NULL)
		goto err_cachep;

	pcache->nr_ids = nr_ids;
	pcache->cachep = cachep;
	list_add(&pcache->list, &pid_caches_lh);
out:
	mutex_unlock(&pid_caches_mutex);
	return pcache->cachep;

err_cachep:
	kfree(pcache);
err_alloc:
	mutex_unlock(&pid_caches_mutex);
	return NULL;
}

static void proc_cleanup_work(struct work_struct *work)
{
	struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
	pid_ns_release_proc(ns);
}

/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
#define MAX_PID_NS_LEVEL 32

static struct ucounts *inc_pid_namespaces(struct user_namespace *ns)
{
	return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
}

static void dec_pid_namespaces(struct ucounts *ucounts)
{
	dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
}

static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
	struct pid_namespace *parent_pid_ns)
{
	struct pid_namespace *ns;
	unsigned int level = parent_pid_ns->level + 1;
	struct ucounts *ucounts;
	int i;
	int err;

	err = -ENOSPC;
	if (level > MAX_PID_NS_LEVEL)
		goto out;
	ucounts = inc_pid_namespaces(user_ns);
	if (!ucounts)
		goto out;

	err = -ENOMEM;
	ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
	if (ns == NULL)
		goto out_dec;

	ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
	if (!ns->pidmap[0].page)
		goto out_free;

	ns->pid_cachep = create_pid_cachep(level + 1);
	if (ns->pid_cachep == NULL)
		goto out_free_map;

	err = ns_alloc_inum(&ns->ns);
	if (err)
		goto out_free_map;
	ns->ns.ops = &pidns_operations;

	kref_init(&ns->kref);
	ns->level = level;
	ns->parent = get_pid_ns(parent_pid_ns);
	ns->user_ns = get_user_ns(user_ns);
	ns->ucounts = ucounts;
	ns->nr_hashed = PIDNS_HASH_ADDING;
	INIT_WORK(&ns->proc_work, proc_cleanup_work);

	set_bit(0, ns->pidmap[0].page);
	atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);

	for (i = 1; i < PIDMAP_ENTRIES; i++)
		atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);

	return ns;

out_free_map:
	kfree(ns->pidmap[0].page);
out_free:
	kmem_cache_free(pid_ns_cachep, ns);
out_dec:
	dec_pid_namespaces(ucounts);
out:
	return ERR_PTR(err);
}

static void delayed_free_pidns(struct rcu_head *p)
{
	struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);

	dec_pid_namespaces(ns->ucounts);
	put_user_ns(ns->user_ns);

	kmem_cache_free(pid_ns_cachep, ns);
}

static void destroy_pid_namespace(struct pid_namespace *ns)
{
	int i;

	ns_free_inum(&ns->ns);
	for (i = 0; i < PIDMAP_ENTRIES; i++)
		kfree(ns->pidmap[i].page);
	call_rcu(&ns->rcu, delayed_free_pidns);
}

struct pid_namespace *copy_pid_ns(unsigned long flags,
	struct user_namespace *user_ns, struct pid_namespace *old_ns)
{
	if (!(flags & CLONE_NEWPID))
		return get_pid_ns(old_ns);
	if (task_active_pid_ns(current) != old_ns)
		return ERR_PTR(-EINVAL);
	return create_pid_namespace(user_ns, old_ns);
}

static void free_pid_ns(struct kref *kref)
{
	struct pid_namespace *ns;

	ns = container_of(kref, struct pid_namespace, kref);
	destroy_pid_namespace(ns);
}

void put_pid_ns(struct pid_namespace *ns)
{
	struct pid_namespace *parent;

	while (ns != &init_pid_ns) {
		parent = ns->parent;
		if (!kref_put(&ns->kref, free_pid_ns))
			break;
		ns = parent;
	}
}
EXPORT_SYMBOL_GPL(put_pid_ns);

void zap_pid_ns_processes(struct pid_namespace *pid_ns)
{
	int nr;
	int rc;
	struct task_struct *task, *me = current;
	int init_pids = thread_group_leader(me) ? 1 : 2;

	/* Don't allow any more processes into the pid namespace */
	disable_pid_allocation(pid_ns);

	/*
	 * Ignore SIGCHLD causing any terminated children to autoreap.
	 * This speeds up the namespace shutdown, plus see the comment
	 * below.
	 */
	spin_lock_irq(&me->sighand->siglock);
	me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
	spin_unlock_irq(&me->sighand->siglock);

	/*
	 * The last thread in the cgroup-init thread group is terminating.
	 * Find remaining pid_ts in the namespace, signal and wait for them
	 * to exit.
	 *
	 * Note:  This signals each threads in the namespace - even those that
	 * 	  belong to the same thread group, To avoid this, we would have
	 * 	  to walk the entire tasklist looking a processes in this
	 * 	  namespace, but that could be unnecessarily expensive if the
	 * 	  pid namespace has just a few processes. Or we need to
	 * 	  maintain a tasklist for each pid namespace.
	 *
	 */
	read_lock(&tasklist_lock);
	nr = next_pidmap(pid_ns, 1);
	while (nr > 0) {
		rcu_read_lock();

		task = pid_task(find_vpid(nr), PIDTYPE_PID);
		if (task && !__fatal_signal_pending(task))
			send_sig_info(SIGKILL, SEND_SIG_FORCED, task);

		rcu_read_unlock();

		nr = next_pidmap(pid_ns, nr);
	}
	read_unlock(&tasklist_lock);

	/*
	 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
	 * sys_wait4() will also block until our children traced from the
	 * parent namespace are detached and become EXIT_DEAD.
	 */
	do {
		clear_thread_flag(TIF_SIGPENDING);
		rc = sys_wait4(-1, NULL, __WALL, NULL);
	} while (rc != -ECHILD);

	/*
	 * sys_wait4() above can't reap the EXIT_DEAD children but we do not
	 * really care, we could reparent them to the global init. We could
	 * exit and reap ->child_reaper even if it is not the last thread in
	 * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
	 * pid_ns can not go away until proc_kill_sb() drops the reference.
	 *
	 * But this ns can also have other tasks injected by setns()+fork().
	 * Again, ignoring the user visible semantics we do not really need
	 * to wait until they are all reaped, but they can be reparented to
	 * us and thus we need to ensure that pid->child_reaper stays valid
	 * until they all go away. See free_pid()->wake_up_process().
	 *
	 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
	 * if reparented.
	 */
	for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (pid_ns->nr_hashed == init_pids)
			break;
		schedule();
	}
	__set_current_state(TASK_RUNNING);

	if (pid_ns->reboot)
		current->signal->group_exit_code = pid_ns->reboot;

	acct_exit_ns(pid_ns);
	return;
}

#ifdef CONFIG_CHECKPOINT_RESTORE
static int pid_ns_ctl_handler(struct ctl_table *table, int write,
		void __user *buffer, size_t *lenp, loff_t *ppos)
{
	struct pid_namespace *pid_ns = task_active_pid_ns(current);
	struct ctl_table tmp = *table;

	if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
		return -EPERM;

	/*
	 * Writing directly to ns' last_pid field is OK, since this field
	 * is volatile in a living namespace anyway and a code writing to
	 * it should synchronize its usage with external means.
	 */

	tmp.data = &pid_ns->last_pid;
	return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
}

extern int pid_max;
static int zero = 0;
static struct ctl_table pid_ns_ctl_table[] = {
	{
		.procname = "ns_last_pid",
		.maxlen = sizeof(int),
		.mode = 0666, /* permissions are checked in the handler */
		.proc_handler = pid_ns_ctl_handler,
		.extra1 = &zero,
		.extra2 = &pid_max,
	},
	{ }
};
static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
#endif	/* CONFIG_CHECKPOINT_RESTORE */

int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
{
	if (pid_ns == &init_pid_ns)
		return 0;

	switch (cmd) {
	case LINUX_REBOOT_CMD_RESTART2:
	case LINUX_REBOOT_CMD_RESTART:
		pid_ns->reboot = SIGHUP;
		break;

	case LINUX_REBOOT_CMD_POWER_OFF:
	case LINUX_REBOOT_CMD_HALT:
		pid_ns->reboot = SIGINT;
		break;
	default:
		return -EINVAL;
	}

	read_lock(&tasklist_lock);
	force_sig(SIGKILL, pid_ns->child_reaper);
	read_unlock(&tasklist_lock);

	do_exit(0);

	/* Not reached */
	return 0;
}

static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
{
	return container_of(ns, struct pid_namespace, ns);
}

static struct ns_common *pidns_get(struct task_struct *task)
{
	struct pid_namespace *ns;

	rcu_read_lock();
	ns = task_active_pid_ns(task);
	if (ns)
		get_pid_ns(ns);
	rcu_read_unlock();

	return ns ? &ns->ns : NULL;
}

static void pidns_put(struct ns_common *ns)
{
	put_pid_ns(to_pid_ns(ns));
}

static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
{
	struct pid_namespace *active = task_active_pid_ns(current);
	struct pid_namespace *ancestor, *new = to_pid_ns(ns);

	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
		return -EPERM;

	/*
	 * Only allow entering the current active pid namespace
	 * or a child of the current active pid namespace.
	 *
	 * This is required for fork to return a usable pid value and
	 * this maintains the property that processes and their
	 * children can not escape their current pid namespace.
	 */
	if (new->level < active->level)
		return -EINVAL;

	ancestor = new;
	while (ancestor->level > active->level)
		ancestor = ancestor->parent;
	if (ancestor != active)
		return -EINVAL;

	put_pid_ns(nsproxy->pid_ns_for_children);
	nsproxy->pid_ns_for_children = get_pid_ns(new);
	return 0;
}

static struct ns_common *pidns_get_parent(struct ns_common *ns)
{
	struct pid_namespace *active = task_active_pid_ns(current);
	struct pid_namespace *pid_ns, *p;

	/* See if the parent is in the current namespace */
	pid_ns = p = to_pid_ns(ns)->parent;
	for (;;) {
		if (!p)
			return ERR_PTR(-EPERM);
		if (p == active)
			break;
		p = p->parent;
	}

	return &get_pid_ns(pid_ns)->ns;
}

static struct user_namespace *pidns_owner(struct ns_common *ns)
{
	return to_pid_ns(ns)->user_ns;
}

const struct proc_ns_operations pidns_operations = {
	.name		= "pid",
	.type		= CLONE_NEWPID,
	.get		= pidns_get,
	.put		= pidns_put,
	.install	= pidns_install,
	.owner		= pidns_owner,
	.get_parent	= pidns_get_parent,
};

static __init int pid_namespaces_init(void)
{
	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);

#ifdef CONFIG_CHECKPOINT_RESTORE
	register_sysctl_paths(kern_path, pid_ns_ctl_table);
#endif
	return 0;
}

__initcall(pid_namespaces_init);
Commit	Line	Data
74bd59bb PE	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>
49f4d8b9	13	#include <linux/user_namespace.h>
74bd59bb	14	#include <linux/syscalls.h>
5b825c3a	15	#include <linux/cred.h>
74bd59bb	16	#include <linux/err.h>
0b6b030f	17	#include <linux/acct.h>
5a0e3ad6	18	#include <linux/slab.h>
0bb80f24	19	#include <linux/proc_ns.h>
cf3f8921	20	#include <linux/reboot.h>
523a6a94	21	#include <linux/export.h>
29930025	22	#include <linux/sched/task.h>
74bd59bb	23
74bd59bb PE	24	struct pid_cache {
	25	int nr_ids;
	26	char name[16];
	27	struct kmem_cache *cachep;
	28	struct list_head list;
	29	};
	30
	31	static LIST_HEAD(pid_caches_lh);
	32	static DEFINE_MUTEX(pid_caches_mutex);
	33	static struct kmem_cache *pid_ns_cachep;
	34
	35	/*
	36	* creates the kmem cache to allocate pids from.
	37	* @nr_ids: the number of numerical ids this pid will have to carry
	38	*/
	39
	40	static struct kmem_cache *create_pid_cachep(int nr_ids)
	41	{
	42	struct pid_cache *pcache;
	43	struct kmem_cache *cachep;
	44
	45	mutex_lock(&pid_caches_mutex);
	46	list_for_each_entry(pcache, &pid_caches_lh, list)
	47	if (pcache->nr_ids == nr_ids)
	48	goto out;
	49
	50	pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
	51	if (pcache == NULL)
	52	goto err_alloc;
	53
	54	snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
	55	cachep = kmem_cache_create(pcache->name,
	56	sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
	57	0, SLAB_HWCACHE_ALIGN, NULL);
	58	if (cachep == NULL)
	59	goto err_cachep;
	60
	61	pcache->nr_ids = nr_ids;
	62	pcache->cachep = cachep;
	63	list_add(&pcache->list, &pid_caches_lh);
	64	out:
	65	mutex_unlock(&pid_caches_mutex);
	66	return pcache->cachep;
	67
	68	err_cachep:
	69	kfree(pcache);
	70	err_alloc:
	71	mutex_unlock(&pid_caches_mutex);
	72	return NULL;
	73	}
	74
0a01f2cc EB	75	static void proc_cleanup_work(struct work_struct *work)
	76	{
	77	struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
	78	pid_ns_release_proc(ns);
	79	}
	80
f2302505 AV	81	/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
	82	#define MAX_PID_NS_LEVEL 32
	83
f333c700 EB	84	static struct ucounts inc_pid_namespaces(struct user_namespace ns)
	85	{
	86	return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
	87	}
	88
	89	static void dec_pid_namespaces(struct ucounts *ucounts)
	90	{
	91	dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
	92	}
	93
49f4d8b9 EB	94	static struct pid_namespace create_pid_namespace(struct user_namespace user_ns,
49f4d8b9 EB	95	struct pid_namespace *parent_pid_ns)
74bd59bb PE	96	{
74bd59bb PE	97	struct pid_namespace *ns;
ed469a63	98	unsigned int level = parent_pid_ns->level + 1;
f333c700	99	struct ucounts *ucounts;
f2302505 AV	100	int i;
	101	int err;
	102
df75e774	103	err = -ENOSPC;
f333c700 EB	104	if (level > MAX_PID_NS_LEVEL)
	105	goto out;
	106	ucounts = inc_pid_namespaces(user_ns);
	107	if (!ucounts)
f2302505	108	goto out;
74bd59bb	109
f2302505	110	err = -ENOMEM;
84406c15	111	ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
74bd59bb	112	if (ns == NULL)
f333c700	113	goto out_dec;
74bd59bb PE	114
	115	ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
	116	if (!ns->pidmap[0].page)
	117	goto out_free;
	118
	119	ns->pid_cachep = create_pid_cachep(level + 1);
	120	if (ns->pid_cachep == NULL)
	121	goto out_free_map;
	122
6344c433	123	err = ns_alloc_inum(&ns->ns);
98f842e6 EB	124	if (err)
98f842e6 EB	125	goto out_free_map;
33c42940	126	ns->ns.ops = &pidns_operations;
98f842e6	127
74bd59bb	128	kref_init(&ns->kref);
74bd59bb	129	ns->level = level;
ed469a63	130	ns->parent = get_pid_ns(parent_pid_ns);
49f4d8b9	131	ns->user_ns = get_user_ns(user_ns);
f333c700	132	ns->ucounts = ucounts;
c876ad76	133	ns->nr_hashed = PIDNS_HASH_ADDING;
0a01f2cc	134	INIT_WORK(&ns->proc_work, proc_cleanup_work);
74bd59bb PE	135
	136	set_bit(0, ns->pidmap[0].page);
	137	atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
	138
84406c15	139	for (i = 1; i < PIDMAP_ENTRIES; i++)
74bd59bb	140	atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
74bd59bb PE	141
	142	return ns;
	143
	144	out_free_map:
	145	kfree(ns->pidmap[0].page);
	146	out_free:
	147	kmem_cache_free(pid_ns_cachep, ns);
f333c700 EB	148	out_dec:
f333c700 EB	149	dec_pid_namespaces(ucounts);
74bd59bb	150	out:
4308eebb	151	return ERR_PTR(err);
74bd59bb PE	152	}
74bd59bb PE	153
1adfcb03 AV	154	static void delayed_free_pidns(struct rcu_head *p)
1adfcb03 AV	155	{
add7c65c AV	156	struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
	157
	158	dec_pid_namespaces(ns->ucounts);
	159	put_user_ns(ns->user_ns);
	160
	161	kmem_cache_free(pid_ns_cachep, ns);
1adfcb03 AV	162	}
1adfcb03 AV	163
74bd59bb PE	164	static void destroy_pid_namespace(struct pid_namespace *ns)
	165	{
	166	int i;
	167
6344c433	168	ns_free_inum(&ns->ns);
74bd59bb PE	169	for (i = 0; i < PIDMAP_ENTRIES; i++)
74bd59bb PE	170	kfree(ns->pidmap[i].page);
1adfcb03	171	call_rcu(&ns->rcu, delayed_free_pidns);
74bd59bb PE	172	}
74bd59bb PE	173
49f4d8b9 EB	174	struct pid_namespace *copy_pid_ns(unsigned long flags,
49f4d8b9 EB	175	struct user_namespace user_ns, struct pid_namespace old_ns)
74bd59bb	176	{
74bd59bb	177	if (!(flags & CLONE_NEWPID))
dca4a979	178	return get_pid_ns(old_ns);
225778d6 EB	179	if (task_active_pid_ns(current) != old_ns)
225778d6 EB	180	return ERR_PTR(-EINVAL);
49f4d8b9	181	return create_pid_namespace(user_ns, old_ns);
74bd59bb PE	182	}
74bd59bb PE	183
bbc2e3ef	184	static void free_pid_ns(struct kref *kref)
74bd59bb	185	{
bbc2e3ef	186	struct pid_namespace *ns;
74bd59bb PE	187
74bd59bb PE	188	ns = container_of(kref, struct pid_namespace, kref);
74bd59bb	189	destroy_pid_namespace(ns);
bbc2e3ef	190	}
74bd59bb	191
bbc2e3ef CG	192	void put_pid_ns(struct pid_namespace *ns)
	193	{
	194	struct pid_namespace *parent;
	195
	196	while (ns != &init_pid_ns) {
	197	parent = ns->parent;
	198	if (!kref_put(&ns->kref, free_pid_ns))
	199	break;
	200	ns = parent;
	201	}
74bd59bb	202	}
bbc2e3ef	203	EXPORT_SYMBOL_GPL(put_pid_ns);
74bd59bb PE	204
	205	void zap_pid_ns_processes(struct pid_namespace *pid_ns)
	206	{
	207	int nr;
	208	int rc;
00c10bc1	209	struct task_struct task, me = current;
751c644b	210	int init_pids = thread_group_leader(me) ? 1 : 2;
00c10bc1	211
c876ad76 EB	212	/* Don't allow any more processes into the pid namespace */
	213	disable_pid_allocation(pid_ns);
	214
a53b8315 ON	215	/*
	216	* Ignore SIGCHLD causing any terminated children to autoreap.
	217	* This speeds up the namespace shutdown, plus see the comment
	218	* below.
	219	*/
00c10bc1 EB	220	spin_lock_irq(&me->sighand->siglock);
	221	me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
	222	spin_unlock_irq(&me->sighand->siglock);
74bd59bb PE	223
	224	/*
	225	* The last thread in the cgroup-init thread group is terminating.
	226	* Find remaining pid_ts in the namespace, signal and wait for them
	227	* to exit.
	228	*
	229	* Note: This signals each threads in the namespace - even those that
	230	* belong to the same thread group, To avoid this, we would have
	231	* to walk the entire tasklist looking a processes in this
	232	* namespace, but that could be unnecessarily expensive if the
	233	* pid namespace has just a few processes. Or we need to
	234	* maintain a tasklist for each pid namespace.
	235	*
	236	*/
	237	read_lock(&tasklist_lock);
	238	nr = next_pidmap(pid_ns, 1);
	239	while (nr > 0) {
e4da026f SB	240	rcu_read_lock();
e4da026f SB	241
e4da026f	242	task = pid_task(find_vpid(nr), PIDTYPE_PID);
a02d6fd6 ON	243	if (task && !__fatal_signal_pending(task))
a02d6fd6 ON	244	send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
e4da026f SB	245
	246	rcu_read_unlock();
	247
74bd59bb PE	248	nr = next_pidmap(pid_ns, nr);
	249	}
	250	read_unlock(&tasklist_lock);
	251
a53b8315 ON	252	/*
	253	* Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
	254	* sys_wait4() will also block until our children traced from the
	255	* parent namespace are detached and become EXIT_DEAD.
	256	*/
74bd59bb PE	257	do {
	258	clear_thread_flag(TIF_SIGPENDING);
	259	rc = sys_wait4(-1, NULL, __WALL, NULL);
	260	} while (rc != -ECHILD);
	261
6347e900	262	/*
a53b8315 ON	263	* sys_wait4() above can't reap the EXIT_DEAD children but we do not
	264	* really care, we could reparent them to the global init. We could
	265	* exit and reap ->child_reaper even if it is not the last thread in
	266	* this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
	267	* pid_ns can not go away until proc_kill_sb() drops the reference.
	268	*
	269	* But this ns can also have other tasks injected by setns()+fork().
	270	* Again, ignoring the user visible semantics we do not really need
	271	* to wait until they are all reaped, but they can be reparented to
	272	* us and thus we need to ensure that pid->child_reaper stays valid
	273	* until they all go away. See free_pid()->wake_up_process().
	274	*
	275	* We rely on ignored SIGCHLD, an injected zombie must be autoreaped
	276	* if reparented.
6347e900 EB	277	*/
6347e900 EB	278	for (;;) {
af4b8a83	279	set_current_state(TASK_UNINTERRUPTIBLE);
751c644b	280	if (pid_ns->nr_hashed == init_pids)
6347e900 EB	281	break;
	282	schedule();
	283	}
af4b8a83	284	__set_current_state(TASK_RUNNING);
6347e900	285
cf3f8921 DL	286	if (pid_ns->reboot)
	287	current->signal->group_exit_code = pid_ns->reboot;
	288
0b6b030f	289	acct_exit_ns(pid_ns);
74bd59bb PE	290	return;
	291	}
	292
98ed57ee	293	#ifdef CONFIG_CHECKPOINT_RESTORE
b8f566b0 PE	294	static int pid_ns_ctl_handler(struct ctl_table *table, int write,
	295	void __user buffer, size_t lenp, loff_t *ppos)
	296	{
49f4d8b9	297	struct pid_namespace *pid_ns = task_active_pid_ns(current);
b8f566b0 PE	298	struct ctl_table tmp = *table;
b8f566b0 PE	299
49f4d8b9	300	if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
b8f566b0 PE	301	return -EPERM;
	302
	303	/*
	304	* Writing directly to ns' last_pid field is OK, since this field
	305	* is volatile in a living namespace anyway and a code writing to
	306	* it should synchronize its usage with external means.
	307	*/
	308
49f4d8b9	309	tmp.data = &pid_ns->last_pid;
579035dc	310	return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
b8f566b0 PE	311	}
b8f566b0 PE	312
579035dc AV	313	extern int pid_max;
579035dc AV	314	static int zero = 0;
b8f566b0 PE	315	static struct ctl_table pid_ns_ctl_table[] = {
	316	{
	317	.procname = "ns_last_pid",
	318	.maxlen = sizeof(int),
	319	.mode = 0666, /* permissions are checked in the handler */
	320	.proc_handler = pid_ns_ctl_handler,
579035dc AV	321	.extra1 = &zero,
579035dc AV	322	.extra2 = &pid_max,
b8f566b0 PE	323	},
	324	{ }
	325	};
b8f566b0	326	static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
98ed57ee	327	#endif /* CONFIG_CHECKPOINT_RESTORE */
b8f566b0	328
cf3f8921 DL	329	int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
	330	{
	331	if (pid_ns == &init_pid_ns)
	332	return 0;
	333
	334	switch (cmd) {
	335	case LINUX_REBOOT_CMD_RESTART2:
	336	case LINUX_REBOOT_CMD_RESTART:
	337	pid_ns->reboot = SIGHUP;
	338	break;
	339
	340	case LINUX_REBOOT_CMD_POWER_OFF:
	341	case LINUX_REBOOT_CMD_HALT:
	342	pid_ns->reboot = SIGINT;
	343	break;
	344	default:
	345	return -EINVAL;
	346	}
	347
	348	read_lock(&tasklist_lock);
	349	force_sig(SIGKILL, pid_ns->child_reaper);
	350	read_unlock(&tasklist_lock);
	351
	352	do_exit(0);
	353
	354	/* Not reached */
	355	return 0;
	356	}
	357
3c041184 AV	358	static inline struct pid_namespace to_pid_ns(struct ns_common ns)
	359	{
	360	return container_of(ns, struct pid_namespace, ns);
	361	}
	362
64964528	363	static struct ns_common pidns_get(struct task_struct task)
57e8391d EB	364	{
	365	struct pid_namespace *ns;
	366
	367	rcu_read_lock();
d2308225 ON	368	ns = task_active_pid_ns(task);
	369	if (ns)
	370	get_pid_ns(ns);
57e8391d EB	371	rcu_read_unlock();
57e8391d EB	372
3c041184	373	return ns ? &ns->ns : NULL;
57e8391d EB	374	}
57e8391d EB	375
64964528	376	static void pidns_put(struct ns_common *ns)
57e8391d	377	{
3c041184	378	put_pid_ns(to_pid_ns(ns));
57e8391d EB	379	}
57e8391d EB	380
64964528	381	static int pidns_install(struct nsproxy nsproxy, struct ns_common ns)
57e8391d EB	382	{
57e8391d EB	383	struct pid_namespace *active = task_active_pid_ns(current);
3c041184	384	struct pid_namespace ancestor, new = to_pid_ns(ns);
57e8391d	385
5e4a0847	386	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) \|\|
c7b96acf	387	!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
57e8391d EB	388	return -EPERM;
	389
	390	/*
	391	* Only allow entering the current active pid namespace
	392	* or a child of the current active pid namespace.
	393	*
	394	* This is required for fork to return a usable pid value and
	395	* this maintains the property that processes and their
	396	* children can not escape their current pid namespace.
	397	*/
	398	if (new->level < active->level)
	399	return -EINVAL;
	400
	401	ancestor = new;
	402	while (ancestor->level > active->level)
	403	ancestor = ancestor->parent;
	404	if (ancestor != active)
	405	return -EINVAL;
	406
c2b1df2e AL	407	put_pid_ns(nsproxy->pid_ns_for_children);
c2b1df2e AL	408	nsproxy->pid_ns_for_children = get_pid_ns(new);
57e8391d EB	409	return 0;
	410	}
	411
a7306ed8 AV	412	static struct ns_common pidns_get_parent(struct ns_common ns)
	413	{
	414	struct pid_namespace *active = task_active_pid_ns(current);
	415	struct pid_namespace pid_ns, p;
	416
	417	/* See if the parent is in the current namespace */
	418	pid_ns = p = to_pid_ns(ns)->parent;
	419	for (;;) {
	420	if (!p)
	421	return ERR_PTR(-EPERM);
	422	if (p == active)
	423	break;
	424	p = p->parent;
	425	}
	426
	427	return &get_pid_ns(pid_ns)->ns;
	428	}
	429
bcac25a5 AV	430	static struct user_namespace pidns_owner(struct ns_common ns)
	431	{
	432	return to_pid_ns(ns)->user_ns;
	433	}
	434
57e8391d EB	435	const struct proc_ns_operations pidns_operations = {
	436	.name = "pid",
	437	.type = CLONE_NEWPID,
	438	.get = pidns_get,
	439	.put = pidns_put,
	440	.install = pidns_install,
bcac25a5	441	.owner = pidns_owner,
a7306ed8	442	.get_parent = pidns_get_parent,
57e8391d EB	443	};
57e8391d EB	444
74bd59bb PE	445	static __init int pid_namespaces_init(void)
	446	{
	447	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
98ed57ee CG	448
98ed57ee CG	449	#ifdef CONFIG_CHECKPOINT_RESTORE
b8f566b0	450	register_sysctl_paths(kern_path, pid_ns_ctl_table);
98ed57ee	451	#endif
74bd59bb PE	452	return 0;
	453	}
	454
	455	__initcall(pid_namespaces_init);