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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/cred.h>
16#include <linux/err.h>
17#include <linux/acct.h>
18#include <linux/slab.h>
19#include <linux/proc_ns.h>
20#include <linux/reboot.h>
21#include <linux/export.h>
22#include <linux/sched/task.h>
23#include <linux/sched/signal.h>
24#include <linux/idr.h>
25
26static DEFINE_MUTEX(pid_caches_mutex);
27static struct kmem_cache *pid_ns_cachep;
28/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
29#define MAX_PID_NS_LEVEL 32
30/* Write once array, filled from the beginning. */
31static struct kmem_cache *pid_cache[MAX_PID_NS_LEVEL];
32
33/*
34 * creates the kmem cache to allocate pids from.
35 * @level: pid namespace level
36 */
37
38static struct kmem_cache *create_pid_cachep(unsigned int level)
39{
40 /* Level 0 is init_pid_ns.pid_cachep */
41 struct kmem_cache **pkc = &pid_cache[level - 1];
42 struct kmem_cache *kc;
43 char name[4 + 10 + 1];
44 unsigned int len;
45
46 kc = READ_ONCE(*pkc);
47 if (kc)
48 return kc;
49
50 snprintf(name, sizeof(name), "pid_%u", level + 1);
51 len = sizeof(struct pid) + level * sizeof(struct upid);
52 mutex_lock(&pid_caches_mutex);
53 /* Name collision forces to do allocation under mutex. */
54 if (!*pkc)
55 *pkc = kmem_cache_create(name, len, 0, SLAB_HWCACHE_ALIGN, 0);
56 mutex_unlock(&pid_caches_mutex);
57 /* current can fail, but someone else can succeed. */
58 return READ_ONCE(*pkc);
59}
60
61static void proc_cleanup_work(struct work_struct *work)
62{
63 struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
64 pid_ns_release_proc(ns);
65}
66
67static struct ucounts *inc_pid_namespaces(struct user_namespace *ns)
68{
69 return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
70}
71
72static void dec_pid_namespaces(struct ucounts *ucounts)
73{
74 dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
75}
76
77static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
78 struct pid_namespace *parent_pid_ns)
79{
80 struct pid_namespace *ns;
81 unsigned int level = parent_pid_ns->level + 1;
82 struct ucounts *ucounts;
83 int err;
84
85 err = -EINVAL;
86 if (!in_userns(parent_pid_ns->user_ns, user_ns))
87 goto out;
88
89 err = -ENOSPC;
90 if (level > MAX_PID_NS_LEVEL)
91 goto out;
92 ucounts = inc_pid_namespaces(user_ns);
93 if (!ucounts)
94 goto out;
95
96 err = -ENOMEM;
97 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
98 if (ns == NULL)
99 goto out_dec;
100
101 idr_init(&ns->idr);
102
103 ns->pid_cachep = create_pid_cachep(level);
104 if (ns->pid_cachep == NULL)
105 goto out_free_idr;
106
107 err = ns_alloc_inum(&ns->ns);
108 if (err)
109 goto out_free_idr;
110 ns->ns.ops = &pidns_operations;
111
112 kref_init(&ns->kref);
113 ns->level = level;
114 ns->parent = get_pid_ns(parent_pid_ns);
115 ns->user_ns = get_user_ns(user_ns);
116 ns->ucounts = ucounts;
117 ns->pid_allocated = PIDNS_ADDING;
118 INIT_WORK(&ns->proc_work, proc_cleanup_work);
119
120 return ns;
121
122out_free_idr:
123 idr_destroy(&ns->idr);
124 kmem_cache_free(pid_ns_cachep, ns);
125out_dec:
126 dec_pid_namespaces(ucounts);
127out:
128 return ERR_PTR(err);
129}
130
131static void delayed_free_pidns(struct rcu_head *p)
132{
133 struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
134
135 dec_pid_namespaces(ns->ucounts);
136 put_user_ns(ns->user_ns);
137
138 kmem_cache_free(pid_ns_cachep, ns);
139}
140
141static void destroy_pid_namespace(struct pid_namespace *ns)
142{
143 ns_free_inum(&ns->ns);
144
145 idr_destroy(&ns->idr);
146 call_rcu(&ns->rcu, delayed_free_pidns);
147}
148
149struct pid_namespace *copy_pid_ns(unsigned long flags,
150 struct user_namespace *user_ns, struct pid_namespace *old_ns)
151{
152 if (!(flags & CLONE_NEWPID))
153 return get_pid_ns(old_ns);
154 if (task_active_pid_ns(current) != old_ns)
155 return ERR_PTR(-EINVAL);
156 return create_pid_namespace(user_ns, old_ns);
157}
158
159static void free_pid_ns(struct kref *kref)
160{
161 struct pid_namespace *ns;
162
163 ns = container_of(kref, struct pid_namespace, kref);
164 destroy_pid_namespace(ns);
165}
166
167void put_pid_ns(struct pid_namespace *ns)
168{
169 struct pid_namespace *parent;
170
171 while (ns != &init_pid_ns) {
172 parent = ns->parent;
173 if (!kref_put(&ns->kref, free_pid_ns))
174 break;
175 ns = parent;
176 }
177}
178EXPORT_SYMBOL_GPL(put_pid_ns);
179
180void zap_pid_ns_processes(struct pid_namespace *pid_ns)
181{
182 int nr;
183 int rc;
184 struct task_struct *task, *me = current;
185 int init_pids = thread_group_leader(me) ? 1 : 2;
186 struct pid *pid;
187
188 /* Don't allow any more processes into the pid namespace */
189 disable_pid_allocation(pid_ns);
190
191 /*
192 * Ignore SIGCHLD causing any terminated children to autoreap.
193 * This speeds up the namespace shutdown, plus see the comment
194 * below.
195 */
196 spin_lock_irq(&me->sighand->siglock);
197 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
198 spin_unlock_irq(&me->sighand->siglock);
199
200 /*
201 * The last thread in the cgroup-init thread group is terminating.
202 * Find remaining pid_ts in the namespace, signal and wait for them
203 * to exit.
204 *
205 * Note: This signals each threads in the namespace - even those that
206 * belong to the same thread group, To avoid this, we would have
207 * to walk the entire tasklist looking a processes in this
208 * namespace, but that could be unnecessarily expensive if the
209 * pid namespace has just a few processes. Or we need to
210 * maintain a tasklist for each pid namespace.
211 *
212 */
213 rcu_read_lock();
214 read_lock(&tasklist_lock);
215 nr = 2;
216 idr_for_each_entry_continue(&pid_ns->idr, pid, nr) {
217 task = pid_task(pid, PIDTYPE_PID);
218 if (task && !__fatal_signal_pending(task))
219 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
220 }
221 read_unlock(&tasklist_lock);
222 rcu_read_unlock();
223
224 /*
225 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
226 * kernel_wait4() will also block until our children traced from the
227 * parent namespace are detached and become EXIT_DEAD.
228 */
229 do {
230 clear_thread_flag(TIF_SIGPENDING);
231 rc = kernel_wait4(-1, NULL, __WALL, NULL);
232 } while (rc != -ECHILD);
233
234 /*
235 * kernel_wait4() above can't reap the EXIT_DEAD children but we do not
236 * really care, we could reparent them to the global init. We could
237 * exit and reap ->child_reaper even if it is not the last thread in
238 * this pid_ns, free_pid(pid_allocated == 0) calls proc_cleanup_work(),
239 * pid_ns can not go away until proc_kill_sb() drops the reference.
240 *
241 * But this ns can also have other tasks injected by setns()+fork().
242 * Again, ignoring the user visible semantics we do not really need
243 * to wait until they are all reaped, but they can be reparented to
244 * us and thus we need to ensure that pid->child_reaper stays valid
245 * until they all go away. See free_pid()->wake_up_process().
246 *
247 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
248 * if reparented.
249 */
250 for (;;) {
251 set_current_state(TASK_INTERRUPTIBLE);
252 if (pid_ns->pid_allocated == init_pids)
253 break;
254 schedule();
255 }
256 __set_current_state(TASK_RUNNING);
257
258 if (pid_ns->reboot)
259 current->signal->group_exit_code = pid_ns->reboot;
260
261 acct_exit_ns(pid_ns);
262 return;
263}
264
265#ifdef CONFIG_CHECKPOINT_RESTORE
266static int pid_ns_ctl_handler(struct ctl_table *table, int write,
267 void __user *buffer, size_t *lenp, loff_t *ppos)
268{
269 struct pid_namespace *pid_ns = task_active_pid_ns(current);
270 struct ctl_table tmp = *table;
271 int ret, next;
272
273 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
274 return -EPERM;
275
276 /*
277 * Writing directly to ns' last_pid field is OK, since this field
278 * is volatile in a living namespace anyway and a code writing to
279 * it should synchronize its usage with external means.
280 */
281
282 next = idr_get_cursor(&pid_ns->idr) - 1;
283
284 tmp.data = &next;
285 ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
286 if (!ret && write)
287 idr_set_cursor(&pid_ns->idr, next + 1);
288
289 return ret;
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 struct ns_common *pidns_for_children_get(struct task_struct *task)
356{
357 struct pid_namespace *ns = NULL;
358
359 task_lock(task);
360 if (task->nsproxy) {
361 ns = task->nsproxy->pid_ns_for_children;
362 get_pid_ns(ns);
363 }
364 task_unlock(task);
365
366 if (ns) {
367 read_lock(&tasklist_lock);
368 if (!ns->child_reaper) {
369 put_pid_ns(ns);
370 ns = NULL;
371 }
372 read_unlock(&tasklist_lock);
373 }
374
375 return ns ? &ns->ns : NULL;
376}
377
378static void pidns_put(struct ns_common *ns)
379{
380 put_pid_ns(to_pid_ns(ns));
381}
382
383static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
384{
385 struct pid_namespace *active = task_active_pid_ns(current);
386 struct pid_namespace *ancestor, *new = to_pid_ns(ns);
387
388 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
389 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
390 return -EPERM;
391
392 /*
393 * Only allow entering the current active pid namespace
394 * or a child of the current active pid namespace.
395 *
396 * This is required for fork to return a usable pid value and
397 * this maintains the property that processes and their
398 * children can not escape their current pid namespace.
399 */
400 if (new->level < active->level)
401 return -EINVAL;
402
403 ancestor = new;
404 while (ancestor->level > active->level)
405 ancestor = ancestor->parent;
406 if (ancestor != active)
407 return -EINVAL;
408
409 put_pid_ns(nsproxy->pid_ns_for_children);
410 nsproxy->pid_ns_for_children = get_pid_ns(new);
411 return 0;
412}
413
414static struct ns_common *pidns_get_parent(struct ns_common *ns)
415{
416 struct pid_namespace *active = task_active_pid_ns(current);
417 struct pid_namespace *pid_ns, *p;
418
419 /* See if the parent is in the current namespace */
420 pid_ns = p = to_pid_ns(ns)->parent;
421 for (;;) {
422 if (!p)
423 return ERR_PTR(-EPERM);
424 if (p == active)
425 break;
426 p = p->parent;
427 }
428
429 return &get_pid_ns(pid_ns)->ns;
430}
431
432static struct user_namespace *pidns_owner(struct ns_common *ns)
433{
434 return to_pid_ns(ns)->user_ns;
435}
436
437const struct proc_ns_operations pidns_operations = {
438 .name = "pid",
439 .type = CLONE_NEWPID,
440 .get = pidns_get,
441 .put = pidns_put,
442 .install = pidns_install,
443 .owner = pidns_owner,
444 .get_parent = pidns_get_parent,
445};
446
447const struct proc_ns_operations pidns_for_children_operations = {
448 .name = "pid_for_children",
449 .real_ns_name = "pid",
450 .type = CLONE_NEWPID,
451 .get = pidns_for_children_get,
452 .put = pidns_put,
453 .install = pidns_install,
454 .owner = pidns_owner,
455 .get_parent = pidns_get_parent,
456};
457
458static __init int pid_namespaces_init(void)
459{
460 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
461
462#ifdef CONFIG_CHECKPOINT_RESTORE
463 register_sysctl_paths(kern_path, pid_ns_ctl_table);
464#endif
465 return 0;
466}
467
468__initcall(pid_namespaces_init);
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/syscalls.h>
14#include <linux/err.h>
15#include <linux/acct.h>
16#include <linux/slab.h>
17#include <linux/proc_fs.h>
18#include <linux/reboot.h>
19
20#define BITS_PER_PAGE (PAGE_SIZE*8)
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 struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
74{
75 struct pid_namespace *ns;
76 unsigned int level = parent_pid_ns->level + 1;
77 int i, err = -ENOMEM;
78
79 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
80 if (ns == NULL)
81 goto out;
82
83 ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
84 if (!ns->pidmap[0].page)
85 goto out_free;
86
87 ns->pid_cachep = create_pid_cachep(level + 1);
88 if (ns->pid_cachep == NULL)
89 goto out_free_map;
90
91 kref_init(&ns->kref);
92 ns->level = level;
93 ns->parent = get_pid_ns(parent_pid_ns);
94
95 set_bit(0, ns->pidmap[0].page);
96 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
97
98 for (i = 1; i < PIDMAP_ENTRIES; i++)
99 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
100
101 err = pid_ns_prepare_proc(ns);
102 if (err)
103 goto out_put_parent_pid_ns;
104
105 return ns;
106
107out_put_parent_pid_ns:
108 put_pid_ns(parent_pid_ns);
109out_free_map:
110 kfree(ns->pidmap[0].page);
111out_free:
112 kmem_cache_free(pid_ns_cachep, ns);
113out:
114 return ERR_PTR(err);
115}
116
117static void destroy_pid_namespace(struct pid_namespace *ns)
118{
119 int i;
120
121 for (i = 0; i < PIDMAP_ENTRIES; i++)
122 kfree(ns->pidmap[i].page);
123 kmem_cache_free(pid_ns_cachep, ns);
124}
125
126struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
127{
128 if (!(flags & CLONE_NEWPID))
129 return get_pid_ns(old_ns);
130 if (flags & (CLONE_THREAD|CLONE_PARENT))
131 return ERR_PTR(-EINVAL);
132 return create_pid_namespace(old_ns);
133}
134
135void free_pid_ns(struct kref *kref)
136{
137 struct pid_namespace *ns, *parent;
138
139 ns = container_of(kref, struct pid_namespace, kref);
140
141 parent = ns->parent;
142 destroy_pid_namespace(ns);
143
144 if (parent != NULL)
145 put_pid_ns(parent);
146}
147
148void zap_pid_ns_processes(struct pid_namespace *pid_ns)
149{
150 int nr;
151 int rc;
152 struct task_struct *task, *me = current;
153
154 /* Ignore SIGCHLD causing any terminated children to autoreap */
155 spin_lock_irq(&me->sighand->siglock);
156 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
157 spin_unlock_irq(&me->sighand->siglock);
158
159 /*
160 * The last thread in the cgroup-init thread group is terminating.
161 * Find remaining pid_ts in the namespace, signal and wait for them
162 * to exit.
163 *
164 * Note: This signals each threads in the namespace - even those that
165 * belong to the same thread group, To avoid this, we would have
166 * to walk the entire tasklist looking a processes in this
167 * namespace, but that could be unnecessarily expensive if the
168 * pid namespace has just a few processes. Or we need to
169 * maintain a tasklist for each pid namespace.
170 *
171 */
172 read_lock(&tasklist_lock);
173 nr = next_pidmap(pid_ns, 1);
174 while (nr > 0) {
175 rcu_read_lock();
176
177 task = pid_task(find_vpid(nr), PIDTYPE_PID);
178 if (task && !__fatal_signal_pending(task))
179 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
180
181 rcu_read_unlock();
182
183 nr = next_pidmap(pid_ns, nr);
184 }
185 read_unlock(&tasklist_lock);
186
187 /* Firstly reap the EXIT_ZOMBIE children we may have. */
188 do {
189 clear_thread_flag(TIF_SIGPENDING);
190 rc = sys_wait4(-1, NULL, __WALL, NULL);
191 } while (rc != -ECHILD);
192
193 /*
194 * sys_wait4() above can't reap the TASK_DEAD children.
195 * Make sure they all go away, see __unhash_process().
196 */
197 for (;;) {
198 bool need_wait = false;
199
200 read_lock(&tasklist_lock);
201 if (!list_empty(¤t->children)) {
202 __set_current_state(TASK_UNINTERRUPTIBLE);
203 need_wait = true;
204 }
205 read_unlock(&tasklist_lock);
206
207 if (!need_wait)
208 break;
209 schedule();
210 }
211
212 if (pid_ns->reboot)
213 current->signal->group_exit_code = pid_ns->reboot;
214
215 acct_exit_ns(pid_ns);
216 return;
217}
218
219#ifdef CONFIG_CHECKPOINT_RESTORE
220static int pid_ns_ctl_handler(struct ctl_table *table, int write,
221 void __user *buffer, size_t *lenp, loff_t *ppos)
222{
223 struct ctl_table tmp = *table;
224
225 if (write && !capable(CAP_SYS_ADMIN))
226 return -EPERM;
227
228 /*
229 * Writing directly to ns' last_pid field is OK, since this field
230 * is volatile in a living namespace anyway and a code writing to
231 * it should synchronize its usage with external means.
232 */
233
234 tmp.data = ¤t->nsproxy->pid_ns->last_pid;
235 return proc_dointvec(&tmp, write, buffer, lenp, ppos);
236}
237
238static struct ctl_table pid_ns_ctl_table[] = {
239 {
240 .procname = "ns_last_pid",
241 .maxlen = sizeof(int),
242 .mode = 0666, /* permissions are checked in the handler */
243 .proc_handler = pid_ns_ctl_handler,
244 },
245 { }
246};
247static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
248#endif /* CONFIG_CHECKPOINT_RESTORE */
249
250int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
251{
252 if (pid_ns == &init_pid_ns)
253 return 0;
254
255 switch (cmd) {
256 case LINUX_REBOOT_CMD_RESTART2:
257 case LINUX_REBOOT_CMD_RESTART:
258 pid_ns->reboot = SIGHUP;
259 break;
260
261 case LINUX_REBOOT_CMD_POWER_OFF:
262 case LINUX_REBOOT_CMD_HALT:
263 pid_ns->reboot = SIGINT;
264 break;
265 default:
266 return -EINVAL;
267 }
268
269 read_lock(&tasklist_lock);
270 force_sig(SIGKILL, pid_ns->child_reaper);
271 read_unlock(&tasklist_lock);
272
273 do_exit(0);
274
275 /* Not reached */
276 return 0;
277}
278
279static __init int pid_namespaces_init(void)
280{
281 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
282
283#ifdef CONFIG_CHECKPOINT_RESTORE
284 register_sysctl_paths(kern_path, pid_ns_ctl_table);
285#endif
286 return 0;
287}
288
289__initcall(pid_namespaces_init);