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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/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 = proc_alloc_inum(&ns->proc_inum);
109 if (err)
110 goto out_free_map;
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->nr_hashed = PIDNS_HASH_ADDING;
117 INIT_WORK(&ns->proc_work, proc_cleanup_work);
118
119 set_bit(0, ns->pidmap[0].page);
120 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
121
122 for (i = 1; i < PIDMAP_ENTRIES; i++)
123 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
124
125 return ns;
126
127out_free_map:
128 kfree(ns->pidmap[0].page);
129out_free:
130 kmem_cache_free(pid_ns_cachep, ns);
131out:
132 return ERR_PTR(err);
133}
134
135static void delayed_free_pidns(struct rcu_head *p)
136{
137 kmem_cache_free(pid_ns_cachep,
138 container_of(p, struct pid_namespace, rcu));
139}
140
141static void destroy_pid_namespace(struct pid_namespace *ns)
142{
143 int i;
144
145 proc_free_inum(ns->proc_inum);
146 for (i = 0; i < PIDMAP_ENTRIES; i++)
147 kfree(ns->pidmap[i].page);
148 put_user_ns(ns->user_ns);
149 call_rcu(&ns->rcu, delayed_free_pidns);
150}
151
152struct pid_namespace *copy_pid_ns(unsigned long flags,
153 struct user_namespace *user_ns, struct pid_namespace *old_ns)
154{
155 if (!(flags & CLONE_NEWPID))
156 return get_pid_ns(old_ns);
157 if (task_active_pid_ns(current) != old_ns)
158 return ERR_PTR(-EINVAL);
159 return create_pid_namespace(user_ns, old_ns);
160}
161
162static void free_pid_ns(struct kref *kref)
163{
164 struct pid_namespace *ns;
165
166 ns = container_of(kref, struct pid_namespace, kref);
167 destroy_pid_namespace(ns);
168}
169
170void put_pid_ns(struct pid_namespace *ns)
171{
172 struct pid_namespace *parent;
173
174 while (ns != &init_pid_ns) {
175 parent = ns->parent;
176 if (!kref_put(&ns->kref, free_pid_ns))
177 break;
178 ns = parent;
179 }
180}
181EXPORT_SYMBOL_GPL(put_pid_ns);
182
183void zap_pid_ns_processes(struct pid_namespace *pid_ns)
184{
185 int nr;
186 int rc;
187 struct task_struct *task, *me = current;
188 int init_pids = thread_group_leader(me) ? 1 : 2;
189
190 /* Don't allow any more processes into the pid namespace */
191 disable_pid_allocation(pid_ns);
192
193 /* Ignore SIGCHLD causing any terminated children to autoreap */
194 spin_lock_irq(&me->sighand->siglock);
195 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
196 spin_unlock_irq(&me->sighand->siglock);
197
198 /*
199 * The last thread in the cgroup-init thread group is terminating.
200 * Find remaining pid_ts in the namespace, signal and wait for them
201 * to exit.
202 *
203 * Note: This signals each threads in the namespace - even those that
204 * belong to the same thread group, To avoid this, we would have
205 * to walk the entire tasklist looking a processes in this
206 * namespace, but that could be unnecessarily expensive if the
207 * pid namespace has just a few processes. Or we need to
208 * maintain a tasklist for each pid namespace.
209 *
210 */
211 read_lock(&tasklist_lock);
212 nr = next_pidmap(pid_ns, 1);
213 while (nr > 0) {
214 rcu_read_lock();
215
216 task = pid_task(find_vpid(nr), PIDTYPE_PID);
217 if (task && !__fatal_signal_pending(task))
218 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
219
220 rcu_read_unlock();
221
222 nr = next_pidmap(pid_ns, nr);
223 }
224 read_unlock(&tasklist_lock);
225
226 /* Firstly reap the EXIT_ZOMBIE children we may have. */
227 do {
228 clear_thread_flag(TIF_SIGPENDING);
229 rc = sys_wait4(-1, NULL, __WALL, NULL);
230 } while (rc != -ECHILD);
231
232 /*
233 * sys_wait4() above can't reap the TASK_DEAD children.
234 * Make sure they all go away, see free_pid().
235 */
236 for (;;) {
237 set_current_state(TASK_UNINTERRUPTIBLE);
238 if (pid_ns->nr_hashed == init_pids)
239 break;
240 schedule();
241 }
242 __set_current_state(TASK_RUNNING);
243
244 if (pid_ns->reboot)
245 current->signal->group_exit_code = pid_ns->reboot;
246
247 acct_exit_ns(pid_ns);
248 return;
249}
250
251#ifdef CONFIG_CHECKPOINT_RESTORE
252static int pid_ns_ctl_handler(struct ctl_table *table, int write,
253 void __user *buffer, size_t *lenp, loff_t *ppos)
254{
255 struct pid_namespace *pid_ns = task_active_pid_ns(current);
256 struct ctl_table tmp = *table;
257
258 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
259 return -EPERM;
260
261 /*
262 * Writing directly to ns' last_pid field is OK, since this field
263 * is volatile in a living namespace anyway and a code writing to
264 * it should synchronize its usage with external means.
265 */
266
267 tmp.data = &pid_ns->last_pid;
268 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
269}
270
271extern int pid_max;
272static int zero = 0;
273static struct ctl_table pid_ns_ctl_table[] = {
274 {
275 .procname = "ns_last_pid",
276 .maxlen = sizeof(int),
277 .mode = 0666, /* permissions are checked in the handler */
278 .proc_handler = pid_ns_ctl_handler,
279 .extra1 = &zero,
280 .extra2 = &pid_max,
281 },
282 { }
283};
284static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
285#endif /* CONFIG_CHECKPOINT_RESTORE */
286
287int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
288{
289 if (pid_ns == &init_pid_ns)
290 return 0;
291
292 switch (cmd) {
293 case LINUX_REBOOT_CMD_RESTART2:
294 case LINUX_REBOOT_CMD_RESTART:
295 pid_ns->reboot = SIGHUP;
296 break;
297
298 case LINUX_REBOOT_CMD_POWER_OFF:
299 case LINUX_REBOOT_CMD_HALT:
300 pid_ns->reboot = SIGINT;
301 break;
302 default:
303 return -EINVAL;
304 }
305
306 read_lock(&tasklist_lock);
307 force_sig(SIGKILL, pid_ns->child_reaper);
308 read_unlock(&tasklist_lock);
309
310 do_exit(0);
311
312 /* Not reached */
313 return 0;
314}
315
316static void *pidns_get(struct task_struct *task)
317{
318 struct pid_namespace *ns;
319
320 rcu_read_lock();
321 ns = task_active_pid_ns(task);
322 if (ns)
323 get_pid_ns(ns);
324 rcu_read_unlock();
325
326 return ns;
327}
328
329static void pidns_put(void *ns)
330{
331 put_pid_ns(ns);
332}
333
334static int pidns_install(struct nsproxy *nsproxy, void *ns)
335{
336 struct pid_namespace *active = task_active_pid_ns(current);
337 struct pid_namespace *ancestor, *new = ns;
338
339 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
340 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
341 return -EPERM;
342
343 /*
344 * Only allow entering the current active pid namespace
345 * or a child of the current active pid namespace.
346 *
347 * This is required for fork to return a usable pid value and
348 * this maintains the property that processes and their
349 * children can not escape their current pid namespace.
350 */
351 if (new->level < active->level)
352 return -EINVAL;
353
354 ancestor = new;
355 while (ancestor->level > active->level)
356 ancestor = ancestor->parent;
357 if (ancestor != active)
358 return -EINVAL;
359
360 put_pid_ns(nsproxy->pid_ns_for_children);
361 nsproxy->pid_ns_for_children = get_pid_ns(new);
362 return 0;
363}
364
365static unsigned int pidns_inum(void *ns)
366{
367 struct pid_namespace *pid_ns = ns;
368 return pid_ns->proc_inum;
369}
370
371const struct proc_ns_operations pidns_operations = {
372 .name = "pid",
373 .type = CLONE_NEWPID,
374 .get = pidns_get,
375 .put = pidns_put,
376 .install = pidns_install,
377 .inum = pidns_inum,
378};
379
380static __init int pid_namespaces_init(void)
381{
382 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
383
384#ifdef CONFIG_CHECKPOINT_RESTORE
385 register_sysctl_paths(kern_path, pid_ns_ctl_table);
386#endif
387 return 0;
388}
389
390__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/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 ucounts *inc_pid_namespaces(struct user_namespace *ns)
83{
84 return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
85}
86
87static void dec_pid_namespaces(struct ucounts *ucounts)
88{
89 dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
90}
91
92static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
93 struct pid_namespace *parent_pid_ns)
94{
95 struct pid_namespace *ns;
96 unsigned int level = parent_pid_ns->level + 1;
97 struct ucounts *ucounts;
98 int i;
99 int err;
100
101 err = -ENOSPC;
102 if (level > MAX_PID_NS_LEVEL)
103 goto out;
104 ucounts = inc_pid_namespaces(user_ns);
105 if (!ucounts)
106 goto out;
107
108 err = -ENOMEM;
109 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
110 if (ns == NULL)
111 goto out_dec;
112
113 ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
114 if (!ns->pidmap[0].page)
115 goto out_free;
116
117 ns->pid_cachep = create_pid_cachep(level + 1);
118 if (ns->pid_cachep == NULL)
119 goto out_free_map;
120
121 err = ns_alloc_inum(&ns->ns);
122 if (err)
123 goto out_free_map;
124 ns->ns.ops = &pidns_operations;
125
126 kref_init(&ns->kref);
127 ns->level = level;
128 ns->parent = get_pid_ns(parent_pid_ns);
129 ns->user_ns = get_user_ns(user_ns);
130 ns->ucounts = ucounts;
131 ns->nr_hashed = PIDNS_HASH_ADDING;
132 INIT_WORK(&ns->proc_work, proc_cleanup_work);
133
134 set_bit(0, ns->pidmap[0].page);
135 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
136
137 for (i = 1; i < PIDMAP_ENTRIES; i++)
138 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
139
140 return ns;
141
142out_free_map:
143 kfree(ns->pidmap[0].page);
144out_free:
145 kmem_cache_free(pid_ns_cachep, ns);
146out_dec:
147 dec_pid_namespaces(ucounts);
148out:
149 return ERR_PTR(err);
150}
151
152static void delayed_free_pidns(struct rcu_head *p)
153{
154 struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
155
156 dec_pid_namespaces(ns->ucounts);
157 put_user_ns(ns->user_ns);
158
159 kmem_cache_free(pid_ns_cachep, ns);
160}
161
162static void destroy_pid_namespace(struct pid_namespace *ns)
163{
164 int i;
165
166 ns_free_inum(&ns->ns);
167 for (i = 0; i < PIDMAP_ENTRIES; i++)
168 kfree(ns->pidmap[i].page);
169 call_rcu(&ns->rcu, delayed_free_pidns);
170}
171
172struct pid_namespace *copy_pid_ns(unsigned long flags,
173 struct user_namespace *user_ns, struct pid_namespace *old_ns)
174{
175 if (!(flags & CLONE_NEWPID))
176 return get_pid_ns(old_ns);
177 if (task_active_pid_ns(current) != old_ns)
178 return ERR_PTR(-EINVAL);
179 return create_pid_namespace(user_ns, old_ns);
180}
181
182static void free_pid_ns(struct kref *kref)
183{
184 struct pid_namespace *ns;
185
186 ns = container_of(kref, struct pid_namespace, kref);
187 destroy_pid_namespace(ns);
188}
189
190void put_pid_ns(struct pid_namespace *ns)
191{
192 struct pid_namespace *parent;
193
194 while (ns != &init_pid_ns) {
195 parent = ns->parent;
196 if (!kref_put(&ns->kref, free_pid_ns))
197 break;
198 ns = parent;
199 }
200}
201EXPORT_SYMBOL_GPL(put_pid_ns);
202
203void zap_pid_ns_processes(struct pid_namespace *pid_ns)
204{
205 int nr;
206 int rc;
207 struct task_struct *task, *me = current;
208 int init_pids = thread_group_leader(me) ? 1 : 2;
209
210 /* Don't allow any more processes into the pid namespace */
211 disable_pid_allocation(pid_ns);
212
213 /*
214 * Ignore SIGCHLD causing any terminated children to autoreap.
215 * This speeds up the namespace shutdown, plus see the comment
216 * below.
217 */
218 spin_lock_irq(&me->sighand->siglock);
219 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
220 spin_unlock_irq(&me->sighand->siglock);
221
222 /*
223 * The last thread in the cgroup-init thread group is terminating.
224 * Find remaining pid_ts in the namespace, signal and wait for them
225 * to exit.
226 *
227 * Note: This signals each threads in the namespace - even those that
228 * belong to the same thread group, To avoid this, we would have
229 * to walk the entire tasklist looking a processes in this
230 * namespace, but that could be unnecessarily expensive if the
231 * pid namespace has just a few processes. Or we need to
232 * maintain a tasklist for each pid namespace.
233 *
234 */
235 read_lock(&tasklist_lock);
236 nr = next_pidmap(pid_ns, 1);
237 while (nr > 0) {
238 rcu_read_lock();
239
240 task = pid_task(find_vpid(nr), PIDTYPE_PID);
241 if (task && !__fatal_signal_pending(task))
242 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
243
244 rcu_read_unlock();
245
246 nr = next_pidmap(pid_ns, nr);
247 }
248 read_unlock(&tasklist_lock);
249
250 /*
251 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
252 * sys_wait4() will also block until our children traced from the
253 * parent namespace are detached and become EXIT_DEAD.
254 */
255 do {
256 clear_thread_flag(TIF_SIGPENDING);
257 rc = sys_wait4(-1, NULL, __WALL, NULL);
258 } while (rc != -ECHILD);
259
260 /*
261 * sys_wait4() above can't reap the EXIT_DEAD children but we do not
262 * really care, we could reparent them to the global init. We could
263 * exit and reap ->child_reaper even if it is not the last thread in
264 * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
265 * pid_ns can not go away until proc_kill_sb() drops the reference.
266 *
267 * But this ns can also have other tasks injected by setns()+fork().
268 * Again, ignoring the user visible semantics we do not really need
269 * to wait until they are all reaped, but they can be reparented to
270 * us and thus we need to ensure that pid->child_reaper stays valid
271 * until they all go away. See free_pid()->wake_up_process().
272 *
273 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
274 * if reparented.
275 */
276 for (;;) {
277 set_current_state(TASK_UNINTERRUPTIBLE);
278 if (pid_ns->nr_hashed == init_pids)
279 break;
280 schedule();
281 }
282 __set_current_state(TASK_RUNNING);
283
284 if (pid_ns->reboot)
285 current->signal->group_exit_code = pid_ns->reboot;
286
287 acct_exit_ns(pid_ns);
288 return;
289}
290
291#ifdef CONFIG_CHECKPOINT_RESTORE
292static int pid_ns_ctl_handler(struct ctl_table *table, int write,
293 void __user *buffer, size_t *lenp, loff_t *ppos)
294{
295 struct pid_namespace *pid_ns = task_active_pid_ns(current);
296 struct ctl_table tmp = *table;
297
298 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
299 return -EPERM;
300
301 /*
302 * Writing directly to ns' last_pid field is OK, since this field
303 * is volatile in a living namespace anyway and a code writing to
304 * it should synchronize its usage with external means.
305 */
306
307 tmp.data = &pid_ns->last_pid;
308 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
309}
310
311extern int pid_max;
312static int zero = 0;
313static struct ctl_table pid_ns_ctl_table[] = {
314 {
315 .procname = "ns_last_pid",
316 .maxlen = sizeof(int),
317 .mode = 0666, /* permissions are checked in the handler */
318 .proc_handler = pid_ns_ctl_handler,
319 .extra1 = &zero,
320 .extra2 = &pid_max,
321 },
322 { }
323};
324static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
325#endif /* CONFIG_CHECKPOINT_RESTORE */
326
327int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
328{
329 if (pid_ns == &init_pid_ns)
330 return 0;
331
332 switch (cmd) {
333 case LINUX_REBOOT_CMD_RESTART2:
334 case LINUX_REBOOT_CMD_RESTART:
335 pid_ns->reboot = SIGHUP;
336 break;
337
338 case LINUX_REBOOT_CMD_POWER_OFF:
339 case LINUX_REBOOT_CMD_HALT:
340 pid_ns->reboot = SIGINT;
341 break;
342 default:
343 return -EINVAL;
344 }
345
346 read_lock(&tasklist_lock);
347 force_sig(SIGKILL, pid_ns->child_reaper);
348 read_unlock(&tasklist_lock);
349
350 do_exit(0);
351
352 /* Not reached */
353 return 0;
354}
355
356static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
357{
358 return container_of(ns, struct pid_namespace, ns);
359}
360
361static struct ns_common *pidns_get(struct task_struct *task)
362{
363 struct pid_namespace *ns;
364
365 rcu_read_lock();
366 ns = task_active_pid_ns(task);
367 if (ns)
368 get_pid_ns(ns);
369 rcu_read_unlock();
370
371 return ns ? &ns->ns : NULL;
372}
373
374static void pidns_put(struct ns_common *ns)
375{
376 put_pid_ns(to_pid_ns(ns));
377}
378
379static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
380{
381 struct pid_namespace *active = task_active_pid_ns(current);
382 struct pid_namespace *ancestor, *new = to_pid_ns(ns);
383
384 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
385 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
386 return -EPERM;
387
388 /*
389 * Only allow entering the current active pid namespace
390 * or a child of the current active pid namespace.
391 *
392 * This is required for fork to return a usable pid value and
393 * this maintains the property that processes and their
394 * children can not escape their current pid namespace.
395 */
396 if (new->level < active->level)
397 return -EINVAL;
398
399 ancestor = new;
400 while (ancestor->level > active->level)
401 ancestor = ancestor->parent;
402 if (ancestor != active)
403 return -EINVAL;
404
405 put_pid_ns(nsproxy->pid_ns_for_children);
406 nsproxy->pid_ns_for_children = get_pid_ns(new);
407 return 0;
408}
409
410static struct ns_common *pidns_get_parent(struct ns_common *ns)
411{
412 struct pid_namespace *active = task_active_pid_ns(current);
413 struct pid_namespace *pid_ns, *p;
414
415 /* See if the parent is in the current namespace */
416 pid_ns = p = to_pid_ns(ns)->parent;
417 for (;;) {
418 if (!p)
419 return ERR_PTR(-EPERM);
420 if (p == active)
421 break;
422 p = p->parent;
423 }
424
425 return &get_pid_ns(pid_ns)->ns;
426}
427
428static struct user_namespace *pidns_owner(struct ns_common *ns)
429{
430 return to_pid_ns(ns)->user_ns;
431}
432
433const struct proc_ns_operations pidns_operations = {
434 .name = "pid",
435 .type = CLONE_NEWPID,
436 .get = pidns_get,
437 .put = pidns_put,
438 .install = pidns_install,
439 .owner = pidns_owner,
440 .get_parent = pidns_get_parent,
441};
442
443static __init int pid_namespaces_init(void)
444{
445 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
446
447#ifdef CONFIG_CHECKPOINT_RESTORE
448 register_sysctl_paths(kern_path, pid_ns_ctl_table);
449#endif
450 return 0;
451}
452
453__initcall(pid_namespaces_init);