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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic pidhash and scalable, time-bounded PID allocator
4 *
5 * (C) 2002-2003 Nadia Yvette Chambers, IBM
6 * (C) 2004 Nadia Yvette Chambers, Oracle
7 * (C) 2002-2004 Ingo Molnar, Red Hat
8 *
9 * pid-structures are backing objects for tasks sharing a given ID to chain
10 * against. There is very little to them aside from hashing them and
11 * parking tasks using given ID's on a list.
12 *
13 * The hash is always changed with the tasklist_lock write-acquired,
14 * and the hash is only accessed with the tasklist_lock at least
15 * read-acquired, so there's no additional SMP locking needed here.
16 *
17 * We have a list of bitmap pages, which bitmaps represent the PID space.
18 * Allocating and freeing PIDs is completely lockless. The worst-case
19 * allocation scenario when all but one out of 1 million PIDs possible are
20 * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
21 * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
22 *
23 * Pid namespaces:
24 * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
25 * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
26 * Many thanks to Oleg Nesterov for comments and help
27 *
28 */
29
30#include <linux/mm.h>
31#include <linux/export.h>
32#include <linux/slab.h>
33#include <linux/init.h>
34#include <linux/rculist.h>
35#include <linux/memblock.h>
36#include <linux/pid_namespace.h>
37#include <linux/init_task.h>
38#include <linux/syscalls.h>
39#include <linux/proc_ns.h>
40#include <linux/refcount.h>
41#include <linux/anon_inodes.h>
42#include <linux/sched/signal.h>
43#include <linux/sched/task.h>
44#include <linux/idr.h>
45
46struct pid init_struct_pid = {
47 .count = REFCOUNT_INIT(1),
48 .tasks = {
49 { .first = NULL },
50 { .first = NULL },
51 { .first = NULL },
52 },
53 .level = 0,
54 .numbers = { {
55 .nr = 0,
56 .ns = &init_pid_ns,
57 }, }
58};
59
60int pid_max = PID_MAX_DEFAULT;
61
62#define RESERVED_PIDS 300
63
64int pid_max_min = RESERVED_PIDS + 1;
65int pid_max_max = PID_MAX_LIMIT;
66
67/*
68 * PID-map pages start out as NULL, they get allocated upon
69 * first use and are never deallocated. This way a low pid_max
70 * value does not cause lots of bitmaps to be allocated, but
71 * the scheme scales to up to 4 million PIDs, runtime.
72 */
73struct pid_namespace init_pid_ns = {
74 .kref = KREF_INIT(2),
75 .idr = IDR_INIT(init_pid_ns.idr),
76 .pid_allocated = PIDNS_ADDING,
77 .level = 0,
78 .child_reaper = &init_task,
79 .user_ns = &init_user_ns,
80 .ns.inum = PROC_PID_INIT_INO,
81#ifdef CONFIG_PID_NS
82 .ns.ops = &pidns_operations,
83#endif
84};
85EXPORT_SYMBOL_GPL(init_pid_ns);
86
87/*
88 * Note: disable interrupts while the pidmap_lock is held as an
89 * interrupt might come in and do read_lock(&tasklist_lock).
90 *
91 * If we don't disable interrupts there is a nasty deadlock between
92 * detach_pid()->free_pid() and another cpu that does
93 * spin_lock(&pidmap_lock) followed by an interrupt routine that does
94 * read_lock(&tasklist_lock);
95 *
96 * After we clean up the tasklist_lock and know there are no
97 * irq handlers that take it we can leave the interrupts enabled.
98 * For now it is easier to be safe than to prove it can't happen.
99 */
100
101static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
102
103void put_pid(struct pid *pid)
104{
105 struct pid_namespace *ns;
106
107 if (!pid)
108 return;
109
110 ns = pid->numbers[pid->level].ns;
111 if (refcount_dec_and_test(&pid->count)) {
112 kmem_cache_free(ns->pid_cachep, pid);
113 put_pid_ns(ns);
114 }
115}
116EXPORT_SYMBOL_GPL(put_pid);
117
118static void delayed_put_pid(struct rcu_head *rhp)
119{
120 struct pid *pid = container_of(rhp, struct pid, rcu);
121 put_pid(pid);
122}
123
124void free_pid(struct pid *pid)
125{
126 /* We can be called with write_lock_irq(&tasklist_lock) held */
127 int i;
128 unsigned long flags;
129
130 spin_lock_irqsave(&pidmap_lock, flags);
131 for (i = 0; i <= pid->level; i++) {
132 struct upid *upid = pid->numbers + i;
133 struct pid_namespace *ns = upid->ns;
134 switch (--ns->pid_allocated) {
135 case 2:
136 case 1:
137 /* When all that is left in the pid namespace
138 * is the reaper wake up the reaper. The reaper
139 * may be sleeping in zap_pid_ns_processes().
140 */
141 wake_up_process(ns->child_reaper);
142 break;
143 case PIDNS_ADDING:
144 /* Handle a fork failure of the first process */
145 WARN_ON(ns->child_reaper);
146 ns->pid_allocated = 0;
147 /* fall through */
148 case 0:
149 schedule_work(&ns->proc_work);
150 break;
151 }
152
153 idr_remove(&ns->idr, upid->nr);
154 }
155 spin_unlock_irqrestore(&pidmap_lock, flags);
156
157 call_rcu(&pid->rcu, delayed_put_pid);
158}
159
160struct pid *alloc_pid(struct pid_namespace *ns)
161{
162 struct pid *pid;
163 enum pid_type type;
164 int i, nr;
165 struct pid_namespace *tmp;
166 struct upid *upid;
167 int retval = -ENOMEM;
168
169 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
170 if (!pid)
171 return ERR_PTR(retval);
172
173 tmp = ns;
174 pid->level = ns->level;
175
176 for (i = ns->level; i >= 0; i--) {
177 int pid_min = 1;
178
179 idr_preload(GFP_KERNEL);
180 spin_lock_irq(&pidmap_lock);
181
182 /*
183 * init really needs pid 1, but after reaching the maximum
184 * wrap back to RESERVED_PIDS
185 */
186 if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
187 pid_min = RESERVED_PIDS;
188
189 /*
190 * Store a null pointer so find_pid_ns does not find
191 * a partially initialized PID (see below).
192 */
193 nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
194 pid_max, GFP_ATOMIC);
195 spin_unlock_irq(&pidmap_lock);
196 idr_preload_end();
197
198 if (nr < 0) {
199 retval = (nr == -ENOSPC) ? -EAGAIN : nr;
200 goto out_free;
201 }
202
203 pid->numbers[i].nr = nr;
204 pid->numbers[i].ns = tmp;
205 tmp = tmp->parent;
206 }
207
208 if (unlikely(is_child_reaper(pid))) {
209 if (pid_ns_prepare_proc(ns))
210 goto out_free;
211 }
212
213 get_pid_ns(ns);
214 refcount_set(&pid->count, 1);
215 for (type = 0; type < PIDTYPE_MAX; ++type)
216 INIT_HLIST_HEAD(&pid->tasks[type]);
217
218 init_waitqueue_head(&pid->wait_pidfd);
219
220 upid = pid->numbers + ns->level;
221 spin_lock_irq(&pidmap_lock);
222 if (!(ns->pid_allocated & PIDNS_ADDING))
223 goto out_unlock;
224 for ( ; upid >= pid->numbers; --upid) {
225 /* Make the PID visible to find_pid_ns. */
226 idr_replace(&upid->ns->idr, pid, upid->nr);
227 upid->ns->pid_allocated++;
228 }
229 spin_unlock_irq(&pidmap_lock);
230
231 return pid;
232
233out_unlock:
234 spin_unlock_irq(&pidmap_lock);
235 put_pid_ns(ns);
236
237out_free:
238 spin_lock_irq(&pidmap_lock);
239 while (++i <= ns->level) {
240 upid = pid->numbers + i;
241 idr_remove(&upid->ns->idr, upid->nr);
242 }
243
244 /* On failure to allocate the first pid, reset the state */
245 if (ns->pid_allocated == PIDNS_ADDING)
246 idr_set_cursor(&ns->idr, 0);
247
248 spin_unlock_irq(&pidmap_lock);
249
250 kmem_cache_free(ns->pid_cachep, pid);
251 return ERR_PTR(retval);
252}
253
254void disable_pid_allocation(struct pid_namespace *ns)
255{
256 spin_lock_irq(&pidmap_lock);
257 ns->pid_allocated &= ~PIDNS_ADDING;
258 spin_unlock_irq(&pidmap_lock);
259}
260
261struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
262{
263 return idr_find(&ns->idr, nr);
264}
265EXPORT_SYMBOL_GPL(find_pid_ns);
266
267struct pid *find_vpid(int nr)
268{
269 return find_pid_ns(nr, task_active_pid_ns(current));
270}
271EXPORT_SYMBOL_GPL(find_vpid);
272
273static struct pid **task_pid_ptr(struct task_struct *task, enum pid_type type)
274{
275 return (type == PIDTYPE_PID) ?
276 &task->thread_pid :
277 &task->signal->pids[type];
278}
279
280/*
281 * attach_pid() must be called with the tasklist_lock write-held.
282 */
283void attach_pid(struct task_struct *task, enum pid_type type)
284{
285 struct pid *pid = *task_pid_ptr(task, type);
286 hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]);
287}
288
289static void __change_pid(struct task_struct *task, enum pid_type type,
290 struct pid *new)
291{
292 struct pid **pid_ptr = task_pid_ptr(task, type);
293 struct pid *pid;
294 int tmp;
295
296 pid = *pid_ptr;
297
298 hlist_del_rcu(&task->pid_links[type]);
299 *pid_ptr = new;
300
301 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
302 if (!hlist_empty(&pid->tasks[tmp]))
303 return;
304
305 free_pid(pid);
306}
307
308void detach_pid(struct task_struct *task, enum pid_type type)
309{
310 __change_pid(task, type, NULL);
311}
312
313void change_pid(struct task_struct *task, enum pid_type type,
314 struct pid *pid)
315{
316 __change_pid(task, type, pid);
317 attach_pid(task, type);
318}
319
320/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
321void transfer_pid(struct task_struct *old, struct task_struct *new,
322 enum pid_type type)
323{
324 if (type == PIDTYPE_PID)
325 new->thread_pid = old->thread_pid;
326 hlist_replace_rcu(&old->pid_links[type], &new->pid_links[type]);
327}
328
329struct task_struct *pid_task(struct pid *pid, enum pid_type type)
330{
331 struct task_struct *result = NULL;
332 if (pid) {
333 struct hlist_node *first;
334 first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
335 lockdep_tasklist_lock_is_held());
336 if (first)
337 result = hlist_entry(first, struct task_struct, pid_links[(type)]);
338 }
339 return result;
340}
341EXPORT_SYMBOL(pid_task);
342
343/*
344 * Must be called under rcu_read_lock().
345 */
346struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
347{
348 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
349 "find_task_by_pid_ns() needs rcu_read_lock() protection");
350 return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
351}
352
353struct task_struct *find_task_by_vpid(pid_t vnr)
354{
355 return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
356}
357
358struct task_struct *find_get_task_by_vpid(pid_t nr)
359{
360 struct task_struct *task;
361
362 rcu_read_lock();
363 task = find_task_by_vpid(nr);
364 if (task)
365 get_task_struct(task);
366 rcu_read_unlock();
367
368 return task;
369}
370
371struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
372{
373 struct pid *pid;
374 rcu_read_lock();
375 pid = get_pid(rcu_dereference(*task_pid_ptr(task, type)));
376 rcu_read_unlock();
377 return pid;
378}
379EXPORT_SYMBOL_GPL(get_task_pid);
380
381struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
382{
383 struct task_struct *result;
384 rcu_read_lock();
385 result = pid_task(pid, type);
386 if (result)
387 get_task_struct(result);
388 rcu_read_unlock();
389 return result;
390}
391EXPORT_SYMBOL_GPL(get_pid_task);
392
393struct pid *find_get_pid(pid_t nr)
394{
395 struct pid *pid;
396
397 rcu_read_lock();
398 pid = get_pid(find_vpid(nr));
399 rcu_read_unlock();
400
401 return pid;
402}
403EXPORT_SYMBOL_GPL(find_get_pid);
404
405pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
406{
407 struct upid *upid;
408 pid_t nr = 0;
409
410 if (pid && ns->level <= pid->level) {
411 upid = &pid->numbers[ns->level];
412 if (upid->ns == ns)
413 nr = upid->nr;
414 }
415 return nr;
416}
417EXPORT_SYMBOL_GPL(pid_nr_ns);
418
419pid_t pid_vnr(struct pid *pid)
420{
421 return pid_nr_ns(pid, task_active_pid_ns(current));
422}
423EXPORT_SYMBOL_GPL(pid_vnr);
424
425pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
426 struct pid_namespace *ns)
427{
428 pid_t nr = 0;
429
430 rcu_read_lock();
431 if (!ns)
432 ns = task_active_pid_ns(current);
433 if (likely(pid_alive(task)))
434 nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
435 rcu_read_unlock();
436
437 return nr;
438}
439EXPORT_SYMBOL(__task_pid_nr_ns);
440
441struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
442{
443 return ns_of_pid(task_pid(tsk));
444}
445EXPORT_SYMBOL_GPL(task_active_pid_ns);
446
447/*
448 * Used by proc to find the first pid that is greater than or equal to nr.
449 *
450 * If there is a pid at nr this function is exactly the same as find_pid_ns.
451 */
452struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
453{
454 return idr_get_next(&ns->idr, &nr);
455}
456
457/**
458 * pidfd_create() - Create a new pid file descriptor.
459 *
460 * @pid: struct pid that the pidfd will reference
461 *
462 * This creates a new pid file descriptor with the O_CLOEXEC flag set.
463 *
464 * Note, that this function can only be called after the fd table has
465 * been unshared to avoid leaking the pidfd to the new process.
466 *
467 * Return: On success, a cloexec pidfd is returned.
468 * On error, a negative errno number will be returned.
469 */
470static int pidfd_create(struct pid *pid)
471{
472 int fd;
473
474 fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
475 O_RDWR | O_CLOEXEC);
476 if (fd < 0)
477 put_pid(pid);
478
479 return fd;
480}
481
482/**
483 * pidfd_open() - Open new pid file descriptor.
484 *
485 * @pid: pid for which to retrieve a pidfd
486 * @flags: flags to pass
487 *
488 * This creates a new pid file descriptor with the O_CLOEXEC flag set for
489 * the process identified by @pid. Currently, the process identified by
490 * @pid must be a thread-group leader. This restriction currently exists
491 * for all aspects of pidfds including pidfd creation (CLONE_PIDFD cannot
492 * be used with CLONE_THREAD) and pidfd polling (only supports thread group
493 * leaders).
494 *
495 * Return: On success, a cloexec pidfd is returned.
496 * On error, a negative errno number will be returned.
497 */
498SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
499{
500 int fd, ret;
501 struct pid *p;
502
503 if (flags)
504 return -EINVAL;
505
506 if (pid <= 0)
507 return -EINVAL;
508
509 p = find_get_pid(pid);
510 if (!p)
511 return -ESRCH;
512
513 ret = 0;
514 rcu_read_lock();
515 if (!pid_task(p, PIDTYPE_TGID))
516 ret = -EINVAL;
517 rcu_read_unlock();
518
519 fd = ret ?: pidfd_create(p);
520 put_pid(p);
521 return fd;
522}
523
524void __init pid_idr_init(void)
525{
526 /* Verify no one has done anything silly: */
527 BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
528
529 /* bump default and minimum pid_max based on number of cpus */
530 pid_max = min(pid_max_max, max_t(int, pid_max,
531 PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
532 pid_max_min = max_t(int, pid_max_min,
533 PIDS_PER_CPU_MIN * num_possible_cpus());
534 pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
535
536 idr_init(&init_pid_ns.idr);
537
538 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
539 SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
540}
1/*
2 * Generic pidhash and scalable, time-bounded PID allocator
3 *
4 * (C) 2002-2003 Nadia Yvette Chambers, IBM
5 * (C) 2004 Nadia Yvette Chambers, Oracle
6 * (C) 2002-2004 Ingo Molnar, Red Hat
7 *
8 * pid-structures are backing objects for tasks sharing a given ID to chain
9 * against. There is very little to them aside from hashing them and
10 * parking tasks using given ID's on a list.
11 *
12 * The hash is always changed with the tasklist_lock write-acquired,
13 * and the hash is only accessed with the tasklist_lock at least
14 * read-acquired, so there's no additional SMP locking needed here.
15 *
16 * We have a list of bitmap pages, which bitmaps represent the PID space.
17 * Allocating and freeing PIDs is completely lockless. The worst-case
18 * allocation scenario when all but one out of 1 million PIDs possible are
19 * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
20 * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
21 *
22 * Pid namespaces:
23 * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
24 * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
25 * Many thanks to Oleg Nesterov for comments and help
26 *
27 */
28
29#include <linux/mm.h>
30#include <linux/export.h>
31#include <linux/slab.h>
32#include <linux/init.h>
33#include <linux/rculist.h>
34#include <linux/bootmem.h>
35#include <linux/hash.h>
36#include <linux/pid_namespace.h>
37#include <linux/init_task.h>
38#include <linux/syscalls.h>
39#include <linux/proc_ns.h>
40#include <linux/proc_fs.h>
41#include <linux/sched/task.h>
42#include <linux/idr.h>
43
44struct pid init_struct_pid = {
45 .count = ATOMIC_INIT(1),
46 .tasks = {
47 { .first = NULL },
48 { .first = NULL },
49 { .first = NULL },
50 },
51 .level = 0,
52 .numbers = { {
53 .nr = 0,
54 .ns = &init_pid_ns,
55 }, }
56};
57
58int pid_max = PID_MAX_DEFAULT;
59
60#define RESERVED_PIDS 300
61
62int pid_max_min = RESERVED_PIDS + 1;
63int pid_max_max = PID_MAX_LIMIT;
64
65/*
66 * PID-map pages start out as NULL, they get allocated upon
67 * first use and are never deallocated. This way a low pid_max
68 * value does not cause lots of bitmaps to be allocated, but
69 * the scheme scales to up to 4 million PIDs, runtime.
70 */
71struct pid_namespace init_pid_ns = {
72 .kref = KREF_INIT(2),
73 .idr = IDR_INIT(init_pid_ns.idr),
74 .pid_allocated = PIDNS_ADDING,
75 .level = 0,
76 .child_reaper = &init_task,
77 .user_ns = &init_user_ns,
78 .ns.inum = PROC_PID_INIT_INO,
79#ifdef CONFIG_PID_NS
80 .ns.ops = &pidns_operations,
81#endif
82};
83EXPORT_SYMBOL_GPL(init_pid_ns);
84
85/*
86 * Note: disable interrupts while the pidmap_lock is held as an
87 * interrupt might come in and do read_lock(&tasklist_lock).
88 *
89 * If we don't disable interrupts there is a nasty deadlock between
90 * detach_pid()->free_pid() and another cpu that does
91 * spin_lock(&pidmap_lock) followed by an interrupt routine that does
92 * read_lock(&tasklist_lock);
93 *
94 * After we clean up the tasklist_lock and know there are no
95 * irq handlers that take it we can leave the interrupts enabled.
96 * For now it is easier to be safe than to prove it can't happen.
97 */
98
99static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
100
101void put_pid(struct pid *pid)
102{
103 struct pid_namespace *ns;
104
105 if (!pid)
106 return;
107
108 ns = pid->numbers[pid->level].ns;
109 if ((atomic_read(&pid->count) == 1) ||
110 atomic_dec_and_test(&pid->count)) {
111 kmem_cache_free(ns->pid_cachep, pid);
112 put_pid_ns(ns);
113 }
114}
115EXPORT_SYMBOL_GPL(put_pid);
116
117static void delayed_put_pid(struct rcu_head *rhp)
118{
119 struct pid *pid = container_of(rhp, struct pid, rcu);
120 put_pid(pid);
121}
122
123void free_pid(struct pid *pid)
124{
125 /* We can be called with write_lock_irq(&tasklist_lock) held */
126 int i;
127 unsigned long flags;
128
129 spin_lock_irqsave(&pidmap_lock, flags);
130 for (i = 0; i <= pid->level; i++) {
131 struct upid *upid = pid->numbers + i;
132 struct pid_namespace *ns = upid->ns;
133 switch (--ns->pid_allocated) {
134 case 2:
135 case 1:
136 /* When all that is left in the pid namespace
137 * is the reaper wake up the reaper. The reaper
138 * may be sleeping in zap_pid_ns_processes().
139 */
140 wake_up_process(ns->child_reaper);
141 break;
142 case PIDNS_ADDING:
143 /* Handle a fork failure of the first process */
144 WARN_ON(ns->child_reaper);
145 ns->pid_allocated = 0;
146 /* fall through */
147 case 0:
148 schedule_work(&ns->proc_work);
149 break;
150 }
151
152 idr_remove(&ns->idr, upid->nr);
153 }
154 spin_unlock_irqrestore(&pidmap_lock, flags);
155
156 call_rcu(&pid->rcu, delayed_put_pid);
157}
158
159struct pid *alloc_pid(struct pid_namespace *ns)
160{
161 struct pid *pid;
162 enum pid_type type;
163 int i, nr;
164 struct pid_namespace *tmp;
165 struct upid *upid;
166 int retval = -ENOMEM;
167
168 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
169 if (!pid)
170 return ERR_PTR(retval);
171
172 tmp = ns;
173 pid->level = ns->level;
174
175 for (i = ns->level; i >= 0; i--) {
176 int pid_min = 1;
177
178 idr_preload(GFP_KERNEL);
179 spin_lock_irq(&pidmap_lock);
180
181 /*
182 * init really needs pid 1, but after reaching the maximum
183 * wrap back to RESERVED_PIDS
184 */
185 if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
186 pid_min = RESERVED_PIDS;
187
188 /*
189 * Store a null pointer so find_pid_ns does not find
190 * a partially initialized PID (see below).
191 */
192 nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
193 pid_max, GFP_ATOMIC);
194 spin_unlock_irq(&pidmap_lock);
195 idr_preload_end();
196
197 if (nr < 0) {
198 retval = nr;
199 goto out_free;
200 }
201
202 pid->numbers[i].nr = nr;
203 pid->numbers[i].ns = tmp;
204 tmp = tmp->parent;
205 }
206
207 if (unlikely(is_child_reaper(pid))) {
208 if (pid_ns_prepare_proc(ns))
209 goto out_free;
210 }
211
212 get_pid_ns(ns);
213 atomic_set(&pid->count, 1);
214 for (type = 0; type < PIDTYPE_MAX; ++type)
215 INIT_HLIST_HEAD(&pid->tasks[type]);
216
217 upid = pid->numbers + ns->level;
218 spin_lock_irq(&pidmap_lock);
219 if (!(ns->pid_allocated & PIDNS_ADDING))
220 goto out_unlock;
221 for ( ; upid >= pid->numbers; --upid) {
222 /* Make the PID visible to find_pid_ns. */
223 idr_replace(&upid->ns->idr, pid, upid->nr);
224 upid->ns->pid_allocated++;
225 }
226 spin_unlock_irq(&pidmap_lock);
227
228 return pid;
229
230out_unlock:
231 spin_unlock_irq(&pidmap_lock);
232 put_pid_ns(ns);
233
234out_free:
235 spin_lock_irq(&pidmap_lock);
236 while (++i <= ns->level)
237 idr_remove(&ns->idr, (pid->numbers + i)->nr);
238
239 /* On failure to allocate the first pid, reset the state */
240 if (ns->pid_allocated == PIDNS_ADDING)
241 idr_set_cursor(&ns->idr, 0);
242
243 spin_unlock_irq(&pidmap_lock);
244
245 kmem_cache_free(ns->pid_cachep, pid);
246 return ERR_PTR(retval);
247}
248
249void disable_pid_allocation(struct pid_namespace *ns)
250{
251 spin_lock_irq(&pidmap_lock);
252 ns->pid_allocated &= ~PIDNS_ADDING;
253 spin_unlock_irq(&pidmap_lock);
254}
255
256struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
257{
258 return idr_find(&ns->idr, nr);
259}
260EXPORT_SYMBOL_GPL(find_pid_ns);
261
262struct pid *find_vpid(int nr)
263{
264 return find_pid_ns(nr, task_active_pid_ns(current));
265}
266EXPORT_SYMBOL_GPL(find_vpid);
267
268/*
269 * attach_pid() must be called with the tasklist_lock write-held.
270 */
271void attach_pid(struct task_struct *task, enum pid_type type)
272{
273 struct pid_link *link = &task->pids[type];
274 hlist_add_head_rcu(&link->node, &link->pid->tasks[type]);
275}
276
277static void __change_pid(struct task_struct *task, enum pid_type type,
278 struct pid *new)
279{
280 struct pid_link *link;
281 struct pid *pid;
282 int tmp;
283
284 link = &task->pids[type];
285 pid = link->pid;
286
287 hlist_del_rcu(&link->node);
288 link->pid = new;
289
290 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
291 if (!hlist_empty(&pid->tasks[tmp]))
292 return;
293
294 free_pid(pid);
295}
296
297void detach_pid(struct task_struct *task, enum pid_type type)
298{
299 __change_pid(task, type, NULL);
300}
301
302void change_pid(struct task_struct *task, enum pid_type type,
303 struct pid *pid)
304{
305 __change_pid(task, type, pid);
306 attach_pid(task, type);
307}
308
309/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
310void transfer_pid(struct task_struct *old, struct task_struct *new,
311 enum pid_type type)
312{
313 new->pids[type].pid = old->pids[type].pid;
314 hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
315}
316
317struct task_struct *pid_task(struct pid *pid, enum pid_type type)
318{
319 struct task_struct *result = NULL;
320 if (pid) {
321 struct hlist_node *first;
322 first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
323 lockdep_tasklist_lock_is_held());
324 if (first)
325 result = hlist_entry(first, struct task_struct, pids[(type)].node);
326 }
327 return result;
328}
329EXPORT_SYMBOL(pid_task);
330
331/*
332 * Must be called under rcu_read_lock().
333 */
334struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
335{
336 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
337 "find_task_by_pid_ns() needs rcu_read_lock() protection");
338 return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
339}
340
341struct task_struct *find_task_by_vpid(pid_t vnr)
342{
343 return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
344}
345
346struct task_struct *find_get_task_by_vpid(pid_t nr)
347{
348 struct task_struct *task;
349
350 rcu_read_lock();
351 task = find_task_by_vpid(nr);
352 if (task)
353 get_task_struct(task);
354 rcu_read_unlock();
355
356 return task;
357}
358
359struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
360{
361 struct pid *pid;
362 rcu_read_lock();
363 if (type != PIDTYPE_PID)
364 task = task->group_leader;
365 pid = get_pid(rcu_dereference(task->pids[type].pid));
366 rcu_read_unlock();
367 return pid;
368}
369EXPORT_SYMBOL_GPL(get_task_pid);
370
371struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
372{
373 struct task_struct *result;
374 rcu_read_lock();
375 result = pid_task(pid, type);
376 if (result)
377 get_task_struct(result);
378 rcu_read_unlock();
379 return result;
380}
381EXPORT_SYMBOL_GPL(get_pid_task);
382
383struct pid *find_get_pid(pid_t nr)
384{
385 struct pid *pid;
386
387 rcu_read_lock();
388 pid = get_pid(find_vpid(nr));
389 rcu_read_unlock();
390
391 return pid;
392}
393EXPORT_SYMBOL_GPL(find_get_pid);
394
395pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
396{
397 struct upid *upid;
398 pid_t nr = 0;
399
400 if (pid && ns->level <= pid->level) {
401 upid = &pid->numbers[ns->level];
402 if (upid->ns == ns)
403 nr = upid->nr;
404 }
405 return nr;
406}
407EXPORT_SYMBOL_GPL(pid_nr_ns);
408
409pid_t pid_vnr(struct pid *pid)
410{
411 return pid_nr_ns(pid, task_active_pid_ns(current));
412}
413EXPORT_SYMBOL_GPL(pid_vnr);
414
415pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
416 struct pid_namespace *ns)
417{
418 pid_t nr = 0;
419
420 rcu_read_lock();
421 if (!ns)
422 ns = task_active_pid_ns(current);
423 if (likely(pid_alive(task))) {
424 if (type != PIDTYPE_PID) {
425 if (type == __PIDTYPE_TGID)
426 type = PIDTYPE_PID;
427
428 task = task->group_leader;
429 }
430 nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
431 }
432 rcu_read_unlock();
433
434 return nr;
435}
436EXPORT_SYMBOL(__task_pid_nr_ns);
437
438struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
439{
440 return ns_of_pid(task_pid(tsk));
441}
442EXPORT_SYMBOL_GPL(task_active_pid_ns);
443
444/*
445 * Used by proc to find the first pid that is greater than or equal to nr.
446 *
447 * If there is a pid at nr this function is exactly the same as find_pid_ns.
448 */
449struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
450{
451 return idr_get_next(&ns->idr, &nr);
452}
453
454void __init pid_idr_init(void)
455{
456 /* Verify no one has done anything silly: */
457 BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
458
459 /* bump default and minimum pid_max based on number of cpus */
460 pid_max = min(pid_max_max, max_t(int, pid_max,
461 PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
462 pid_max_min = max_t(int, pid_max_min,
463 PIDS_PER_CPU_MIN * num_possible_cpus());
464 pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
465
466 idr_init(&init_pid_ns.idr);
467
468 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
469 SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
470}