kthread: rename probe_kthread_data() to kthread_probe_data()
[linux-2.6-block.git] / kernel / pid_namespace.c
CommitLineData
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
PE
14#include <linux/syscalls.h>
15#include <linux/err.h>
0b6b030f 16#include <linux/acct.h>
5a0e3ad6 17#include <linux/slab.h>
0bb80f24 18#include <linux/proc_ns.h>
cf3f8921 19#include <linux/reboot.h>
523a6a94 20#include <linux/export.h>
74bd59bb 21
74bd59bb
PE
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
0a01f2cc
EB
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
f2302505
AV
79/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
80#define MAX_PID_NS_LEVEL 32
81
f333c700
EB
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
49f4d8b9
EB
92static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
93 struct pid_namespace *parent_pid_ns)
74bd59bb
PE
94{
95 struct pid_namespace *ns;
ed469a63 96 unsigned int level = parent_pid_ns->level + 1;
f333c700 97 struct ucounts *ucounts;
f2302505
AV
98 int i;
99 int err;
100
df75e774 101 err = -ENOSPC;
f333c700
EB
102 if (level > MAX_PID_NS_LEVEL)
103 goto out;
104 ucounts = inc_pid_namespaces(user_ns);
105 if (!ucounts)
f2302505 106 goto out;
74bd59bb 107
f2302505 108 err = -ENOMEM;
84406c15 109 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
74bd59bb 110 if (ns == NULL)
f333c700 111 goto out_dec;
74bd59bb
PE
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
6344c433 121 err = ns_alloc_inum(&ns->ns);
98f842e6
EB
122 if (err)
123 goto out_free_map;
33c42940 124 ns->ns.ops = &pidns_operations;
98f842e6 125
74bd59bb 126 kref_init(&ns->kref);
74bd59bb 127 ns->level = level;
ed469a63 128 ns->parent = get_pid_ns(parent_pid_ns);
49f4d8b9 129 ns->user_ns = get_user_ns(user_ns);
f333c700 130 ns->ucounts = ucounts;
c876ad76 131 ns->nr_hashed = PIDNS_HASH_ADDING;
0a01f2cc 132 INIT_WORK(&ns->proc_work, proc_cleanup_work);
74bd59bb
PE
133
134 set_bit(0, ns->pidmap[0].page);
135 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
136
84406c15 137 for (i = 1; i < PIDMAP_ENTRIES; i++)
74bd59bb 138 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
74bd59bb
PE
139
140 return ns;
141
142out_free_map:
143 kfree(ns->pidmap[0].page);
144out_free:
145 kmem_cache_free(pid_ns_cachep, ns);
f333c700
EB
146out_dec:
147 dec_pid_namespaces(ucounts);
74bd59bb 148out:
4308eebb 149 return ERR_PTR(err);
74bd59bb
PE
150}
151
1adfcb03
AV
152static void delayed_free_pidns(struct rcu_head *p)
153{
154 kmem_cache_free(pid_ns_cachep,
155 container_of(p, struct pid_namespace, rcu));
156}
157
74bd59bb
PE
158static void destroy_pid_namespace(struct pid_namespace *ns)
159{
160 int i;
161
6344c433 162 ns_free_inum(&ns->ns);
74bd59bb
PE
163 for (i = 0; i < PIDMAP_ENTRIES; i++)
164 kfree(ns->pidmap[i].page);
f333c700 165 dec_pid_namespaces(ns->ucounts);
49f4d8b9 166 put_user_ns(ns->user_ns);
1adfcb03 167 call_rcu(&ns->rcu, delayed_free_pidns);
74bd59bb
PE
168}
169
49f4d8b9
EB
170struct pid_namespace *copy_pid_ns(unsigned long flags,
171 struct user_namespace *user_ns, struct pid_namespace *old_ns)
74bd59bb 172{
74bd59bb 173 if (!(flags & CLONE_NEWPID))
dca4a979 174 return get_pid_ns(old_ns);
225778d6
EB
175 if (task_active_pid_ns(current) != old_ns)
176 return ERR_PTR(-EINVAL);
49f4d8b9 177 return create_pid_namespace(user_ns, old_ns);
74bd59bb
PE
178}
179
bbc2e3ef 180static void free_pid_ns(struct kref *kref)
74bd59bb 181{
bbc2e3ef 182 struct pid_namespace *ns;
74bd59bb
PE
183
184 ns = container_of(kref, struct pid_namespace, kref);
74bd59bb 185 destroy_pid_namespace(ns);
bbc2e3ef 186}
74bd59bb 187
bbc2e3ef
CG
188void put_pid_ns(struct pid_namespace *ns)
189{
190 struct pid_namespace *parent;
191
192 while (ns != &init_pid_ns) {
193 parent = ns->parent;
194 if (!kref_put(&ns->kref, free_pid_ns))
195 break;
196 ns = parent;
197 }
74bd59bb 198}
bbc2e3ef 199EXPORT_SYMBOL_GPL(put_pid_ns);
74bd59bb
PE
200
201void zap_pid_ns_processes(struct pid_namespace *pid_ns)
202{
203 int nr;
204 int rc;
00c10bc1 205 struct task_struct *task, *me = current;
751c644b 206 int init_pids = thread_group_leader(me) ? 1 : 2;
00c10bc1 207
c876ad76
EB
208 /* Don't allow any more processes into the pid namespace */
209 disable_pid_allocation(pid_ns);
210
a53b8315
ON
211 /*
212 * Ignore SIGCHLD causing any terminated children to autoreap.
213 * This speeds up the namespace shutdown, plus see the comment
214 * below.
215 */
00c10bc1
EB
216 spin_lock_irq(&me->sighand->siglock);
217 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
218 spin_unlock_irq(&me->sighand->siglock);
74bd59bb
PE
219
220 /*
221 * The last thread in the cgroup-init thread group is terminating.
222 * Find remaining pid_ts in the namespace, signal and wait for them
223 * to exit.
224 *
225 * Note: This signals each threads in the namespace - even those that
226 * belong to the same thread group, To avoid this, we would have
227 * to walk the entire tasklist looking a processes in this
228 * namespace, but that could be unnecessarily expensive if the
229 * pid namespace has just a few processes. Or we need to
230 * maintain a tasklist for each pid namespace.
231 *
232 */
233 read_lock(&tasklist_lock);
234 nr = next_pidmap(pid_ns, 1);
235 while (nr > 0) {
e4da026f
SB
236 rcu_read_lock();
237
e4da026f 238 task = pid_task(find_vpid(nr), PIDTYPE_PID);
a02d6fd6
ON
239 if (task && !__fatal_signal_pending(task))
240 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
e4da026f
SB
241
242 rcu_read_unlock();
243
74bd59bb
PE
244 nr = next_pidmap(pid_ns, nr);
245 }
246 read_unlock(&tasklist_lock);
247
a53b8315
ON
248 /*
249 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
250 * sys_wait4() will also block until our children traced from the
251 * parent namespace are detached and become EXIT_DEAD.
252 */
74bd59bb
PE
253 do {
254 clear_thread_flag(TIF_SIGPENDING);
255 rc = sys_wait4(-1, NULL, __WALL, NULL);
256 } while (rc != -ECHILD);
257
6347e900 258 /*
a53b8315
ON
259 * sys_wait4() above can't reap the EXIT_DEAD children but we do not
260 * really care, we could reparent them to the global init. We could
261 * exit and reap ->child_reaper even if it is not the last thread in
262 * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
263 * pid_ns can not go away until proc_kill_sb() drops the reference.
264 *
265 * But this ns can also have other tasks injected by setns()+fork().
266 * Again, ignoring the user visible semantics we do not really need
267 * to wait until they are all reaped, but they can be reparented to
268 * us and thus we need to ensure that pid->child_reaper stays valid
269 * until they all go away. See free_pid()->wake_up_process().
270 *
271 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
272 * if reparented.
6347e900
EB
273 */
274 for (;;) {
af4b8a83 275 set_current_state(TASK_UNINTERRUPTIBLE);
751c644b 276 if (pid_ns->nr_hashed == init_pids)
6347e900
EB
277 break;
278 schedule();
279 }
af4b8a83 280 __set_current_state(TASK_RUNNING);
6347e900 281
cf3f8921
DL
282 if (pid_ns->reboot)
283 current->signal->group_exit_code = pid_ns->reboot;
284
0b6b030f 285 acct_exit_ns(pid_ns);
74bd59bb
PE
286 return;
287}
288
98ed57ee 289#ifdef CONFIG_CHECKPOINT_RESTORE
b8f566b0
PE
290static int pid_ns_ctl_handler(struct ctl_table *table, int write,
291 void __user *buffer, size_t *lenp, loff_t *ppos)
292{
49f4d8b9 293 struct pid_namespace *pid_ns = task_active_pid_ns(current);
b8f566b0
PE
294 struct ctl_table tmp = *table;
295
49f4d8b9 296 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
b8f566b0
PE
297 return -EPERM;
298
299 /*
300 * Writing directly to ns' last_pid field is OK, since this field
301 * is volatile in a living namespace anyway and a code writing to
302 * it should synchronize its usage with external means.
303 */
304
49f4d8b9 305 tmp.data = &pid_ns->last_pid;
579035dc 306 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
b8f566b0
PE
307}
308
579035dc
AV
309extern int pid_max;
310static int zero = 0;
b8f566b0
PE
311static struct ctl_table pid_ns_ctl_table[] = {
312 {
313 .procname = "ns_last_pid",
314 .maxlen = sizeof(int),
315 .mode = 0666, /* permissions are checked in the handler */
316 .proc_handler = pid_ns_ctl_handler,
579035dc
AV
317 .extra1 = &zero,
318 .extra2 = &pid_max,
b8f566b0
PE
319 },
320 { }
321};
b8f566b0 322static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
98ed57ee 323#endif /* CONFIG_CHECKPOINT_RESTORE */
b8f566b0 324
cf3f8921
DL
325int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
326{
327 if (pid_ns == &init_pid_ns)
328 return 0;
329
330 switch (cmd) {
331 case LINUX_REBOOT_CMD_RESTART2:
332 case LINUX_REBOOT_CMD_RESTART:
333 pid_ns->reboot = SIGHUP;
334 break;
335
336 case LINUX_REBOOT_CMD_POWER_OFF:
337 case LINUX_REBOOT_CMD_HALT:
338 pid_ns->reboot = SIGINT;
339 break;
340 default:
341 return -EINVAL;
342 }
343
344 read_lock(&tasklist_lock);
345 force_sig(SIGKILL, pid_ns->child_reaper);
346 read_unlock(&tasklist_lock);
347
348 do_exit(0);
349
350 /* Not reached */
351 return 0;
352}
353
3c041184
AV
354static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
355{
356 return container_of(ns, struct pid_namespace, ns);
357}
358
64964528 359static struct ns_common *pidns_get(struct task_struct *task)
57e8391d
EB
360{
361 struct pid_namespace *ns;
362
363 rcu_read_lock();
d2308225
ON
364 ns = task_active_pid_ns(task);
365 if (ns)
366 get_pid_ns(ns);
57e8391d
EB
367 rcu_read_unlock();
368
3c041184 369 return ns ? &ns->ns : NULL;
57e8391d
EB
370}
371
64964528 372static void pidns_put(struct ns_common *ns)
57e8391d 373{
3c041184 374 put_pid_ns(to_pid_ns(ns));
57e8391d
EB
375}
376
64964528 377static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
57e8391d
EB
378{
379 struct pid_namespace *active = task_active_pid_ns(current);
3c041184 380 struct pid_namespace *ancestor, *new = to_pid_ns(ns);
57e8391d 381
5e4a0847 382 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
c7b96acf 383 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
57e8391d
EB
384 return -EPERM;
385
386 /*
387 * Only allow entering the current active pid namespace
388 * or a child of the current active pid namespace.
389 *
390 * This is required for fork to return a usable pid value and
391 * this maintains the property that processes and their
392 * children can not escape their current pid namespace.
393 */
394 if (new->level < active->level)
395 return -EINVAL;
396
397 ancestor = new;
398 while (ancestor->level > active->level)
399 ancestor = ancestor->parent;
400 if (ancestor != active)
401 return -EINVAL;
402
c2b1df2e
AL
403 put_pid_ns(nsproxy->pid_ns_for_children);
404 nsproxy->pid_ns_for_children = get_pid_ns(new);
57e8391d
EB
405 return 0;
406}
407
a7306ed8
AV
408static struct ns_common *pidns_get_parent(struct ns_common *ns)
409{
410 struct pid_namespace *active = task_active_pid_ns(current);
411 struct pid_namespace *pid_ns, *p;
412
413 /* See if the parent is in the current namespace */
414 pid_ns = p = to_pid_ns(ns)->parent;
415 for (;;) {
416 if (!p)
417 return ERR_PTR(-EPERM);
418 if (p == active)
419 break;
420 p = p->parent;
421 }
422
423 return &get_pid_ns(pid_ns)->ns;
424}
425
bcac25a5
AV
426static struct user_namespace *pidns_owner(struct ns_common *ns)
427{
428 return to_pid_ns(ns)->user_ns;
429}
430
57e8391d
EB
431const struct proc_ns_operations pidns_operations = {
432 .name = "pid",
433 .type = CLONE_NEWPID,
434 .get = pidns_get,
435 .put = pidns_put,
436 .install = pidns_install,
bcac25a5 437 .owner = pidns_owner,
a7306ed8 438 .get_parent = pidns_get_parent,
57e8391d
EB
439};
440
74bd59bb
PE
441static __init int pid_namespaces_init(void)
442{
443 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
98ed57ee
CG
444
445#ifdef CONFIG_CHECKPOINT_RESTORE
b8f566b0 446 register_sysctl_paths(kern_path, pid_ns_ctl_table);
98ed57ee 447#endif
74bd59bb
PE
448 return 0;
449}
450
451__initcall(pid_namespaces_init);