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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#include <net/sock.h>
46
47struct pid init_struct_pid = {
48 .count = REFCOUNT_INIT(1),
49 .tasks = {
50 { .first = NULL },
51 { .first = NULL },
52 { .first = NULL },
53 },
54 .level = 0,
55 .numbers = { {
56 .nr = 0,
57 .ns = &init_pid_ns,
58 }, }
59};
60
61int pid_max = PID_MAX_DEFAULT;
62
63#define RESERVED_PIDS 300
64
65int pid_max_min = RESERVED_PIDS + 1;
66int pid_max_max = PID_MAX_LIMIT;
67
68
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70
71
72
73
74struct pid_namespace init_pid_ns = {
75 .kref = KREF_INIT(2),
76 .idr = IDR_INIT(init_pid_ns.idr),
77 .pid_allocated = PIDNS_ADDING,
78 .level = 0,
79 .child_reaper = &init_task,
80 .user_ns = &init_user_ns,
81 .ns.inum = PROC_PID_INIT_INO,
82#ifdef CONFIG_PID_NS
83 .ns.ops = &pidns_operations,
84#endif
85};
86EXPORT_SYMBOL_GPL(init_pid_ns);
87
88
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100
101
102static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
103
104void put_pid(struct pid *pid)
105{
106 struct pid_namespace *ns;
107
108 if (!pid)
109 return;
110
111 ns = pid->numbers[pid->level].ns;
112 if (refcount_dec_and_test(&pid->count)) {
113 kmem_cache_free(ns->pid_cachep, pid);
114 put_pid_ns(ns);
115 }
116}
117EXPORT_SYMBOL_GPL(put_pid);
118
119static void delayed_put_pid(struct rcu_head *rhp)
120{
121 struct pid *pid = container_of(rhp, struct pid, rcu);
122 put_pid(pid);
123}
124
125void free_pid(struct pid *pid)
126{
127
128 int i;
129 unsigned long flags;
130
131 spin_lock_irqsave(&pidmap_lock, flags);
132 for (i = 0; i <= pid->level; i++) {
133 struct upid *upid = pid->numbers + i;
134 struct pid_namespace *ns = upid->ns;
135 switch (--ns->pid_allocated) {
136 case 2:
137 case 1:
138
139
140
141
142 wake_up_process(ns->child_reaper);
143 break;
144 case PIDNS_ADDING:
145
146 WARN_ON(ns->child_reaper);
147 ns->pid_allocated = 0;
148 break;
149 }
150
151 idr_remove(&ns->idr, upid->nr);
152 }
153 spin_unlock_irqrestore(&pidmap_lock, flags);
154
155 call_rcu(&pid->rcu, delayed_put_pid);
156}
157
158struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
159 size_t set_tid_size)
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
169
170
171
172
173
174
175
176 if (set_tid_size > ns->level + 1)
177 return ERR_PTR(-EINVAL);
178
179 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
180 if (!pid)
181 return ERR_PTR(retval);
182
183 tmp = ns;
184 pid->level = ns->level;
185
186 for (i = ns->level; i >= 0; i--) {
187 int tid = 0;
188
189 if (set_tid_size) {
190 tid = set_tid[ns->level - i];
191
192 retval = -EINVAL;
193 if (tid < 1 || tid >= pid_max)
194 goto out_free;
195
196
197
198
199 if (tid != 1 && !tmp->child_reaper)
200 goto out_free;
201 retval = -EPERM;
202 if (!checkpoint_restore_ns_capable(tmp->user_ns))
203 goto out_free;
204 set_tid_size--;
205 }
206
207 idr_preload(GFP_KERNEL);
208 spin_lock_irq(&pidmap_lock);
209
210 if (tid) {
211 nr = idr_alloc(&tmp->idr, NULL, tid,
212 tid + 1, GFP_ATOMIC);
213
214
215
216
217 if (nr == -ENOSPC)
218 nr = -EEXIST;
219 } else {
220 int pid_min = 1;
221
222
223
224
225 if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
226 pid_min = RESERVED_PIDS;
227
228
229
230
231
232 nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
233 pid_max, GFP_ATOMIC);
234 }
235 spin_unlock_irq(&pidmap_lock);
236 idr_preload_end();
237
238 if (nr < 0) {
239 retval = (nr == -ENOSPC) ? -EAGAIN : nr;
240 goto out_free;
241 }
242
243 pid->numbers[i].nr = nr;
244 pid->numbers[i].ns = tmp;
245 tmp = tmp->parent;
246 }
247
248
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254
255
256 retval = -ENOMEM;
257
258 get_pid_ns(ns);
259 refcount_set(&pid->count, 1);
260 spin_lock_init(&pid->lock);
261 for (type = 0; type < PIDTYPE_MAX; ++type)
262 INIT_HLIST_HEAD(&pid->tasks[type]);
263
264 init_waitqueue_head(&pid->wait_pidfd);
265 INIT_HLIST_HEAD(&pid->inodes);
266
267 upid = pid->numbers + ns->level;
268 spin_lock_irq(&pidmap_lock);
269 if (!(ns->pid_allocated & PIDNS_ADDING))
270 goto out_unlock;
271 for ( ; upid >= pid->numbers; --upid) {
272
273 idr_replace(&upid->ns->idr, pid, upid->nr);
274 upid->ns->pid_allocated++;
275 }
276 spin_unlock_irq(&pidmap_lock);
277
278 return pid;
279
280out_unlock:
281 spin_unlock_irq(&pidmap_lock);
282 put_pid_ns(ns);
283
284out_free:
285 spin_lock_irq(&pidmap_lock);
286 while (++i <= ns->level) {
287 upid = pid->numbers + i;
288 idr_remove(&upid->ns->idr, upid->nr);
289 }
290
291
292 if (ns->pid_allocated == PIDNS_ADDING)
293 idr_set_cursor(&ns->idr, 0);
294
295 spin_unlock_irq(&pidmap_lock);
296
297 kmem_cache_free(ns->pid_cachep, pid);
298 return ERR_PTR(retval);
299}
300
301void disable_pid_allocation(struct pid_namespace *ns)
302{
303 spin_lock_irq(&pidmap_lock);
304 ns->pid_allocated &= ~PIDNS_ADDING;
305 spin_unlock_irq(&pidmap_lock);
306}
307
308struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
309{
310 return idr_find(&ns->idr, nr);
311}
312EXPORT_SYMBOL_GPL(find_pid_ns);
313
314struct pid *find_vpid(int nr)
315{
316 return find_pid_ns(nr, task_active_pid_ns(current));
317}
318EXPORT_SYMBOL_GPL(find_vpid);
319
320static struct pid **task_pid_ptr(struct task_struct *task, enum pid_type type)
321{
322 return (type == PIDTYPE_PID) ?
323 &task->thread_pid :
324 &task->signal->pids[type];
325}
326
327
328
329
330void attach_pid(struct task_struct *task, enum pid_type type)
331{
332 struct pid *pid = *task_pid_ptr(task, type);
333 hlist_add_head_rcu(&task->pid_links[type], &pid->tasks[type]);
334}
335
336static void __change_pid(struct task_struct *task, enum pid_type type,
337 struct pid *new)
338{
339 struct pid **pid_ptr = task_pid_ptr(task, type);
340 struct pid *pid;
341 int tmp;
342
343 pid = *pid_ptr;
344
345 hlist_del_rcu(&task->pid_links[type]);
346 *pid_ptr = new;
347
348 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
349 if (pid_has_task(pid, tmp))
350 return;
351
352 free_pid(pid);
353}
354
355void detach_pid(struct task_struct *task, enum pid_type type)
356{
357 __change_pid(task, type, NULL);
358}
359
360void change_pid(struct task_struct *task, enum pid_type type,
361 struct pid *pid)
362{
363 __change_pid(task, type, pid);
364 attach_pid(task, type);
365}
366
367void exchange_tids(struct task_struct *left, struct task_struct *right)
368{
369 struct pid *pid1 = left->thread_pid;
370 struct pid *pid2 = right->thread_pid;
371 struct hlist_head *head1 = &pid1->tasks[PIDTYPE_PID];
372 struct hlist_head *head2 = &pid2->tasks[PIDTYPE_PID];
373
374
375 hlists_swap_heads_rcu(head1, head2);
376
377
378 rcu_assign_pointer(left->thread_pid, pid2);
379 rcu_assign_pointer(right->thread_pid, pid1);
380
381
382 WRITE_ONCE(left->pid, pid_nr(pid2));
383 WRITE_ONCE(right->pid, pid_nr(pid1));
384}
385
386
387void transfer_pid(struct task_struct *old, struct task_struct *new,
388 enum pid_type type)
389{
390 if (type == PIDTYPE_PID)
391 new->thread_pid = old->thread_pid;
392 hlist_replace_rcu(&old->pid_links[type], &new->pid_links[type]);
393}
394
395struct task_struct *pid_task(struct pid *pid, enum pid_type type)
396{
397 struct task_struct *result = NULL;
398 if (pid) {
399 struct hlist_node *first;
400 first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
401 lockdep_tasklist_lock_is_held());
402 if (first)
403 result = hlist_entry(first, struct task_struct, pid_links[(type)]);
404 }
405 return result;
406}
407EXPORT_SYMBOL(pid_task);
408
409
410
411
412struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
413{
414 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
415 "find_task_by_pid_ns() needs rcu_read_lock() protection");
416 return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
417}
418
419struct task_struct *find_task_by_vpid(pid_t vnr)
420{
421 return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
422}
423
424struct task_struct *find_get_task_by_vpid(pid_t nr)
425{
426 struct task_struct *task;
427
428 rcu_read_lock();
429 task = find_task_by_vpid(nr);
430 if (task)
431 get_task_struct(task);
432 rcu_read_unlock();
433
434 return task;
435}
436
437struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
438{
439 struct pid *pid;
440 rcu_read_lock();
441 pid = get_pid(rcu_dereference(*task_pid_ptr(task, type)));
442 rcu_read_unlock();
443 return pid;
444}
445EXPORT_SYMBOL_GPL(get_task_pid);
446
447struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
448{
449 struct task_struct *result;
450 rcu_read_lock();
451 result = pid_task(pid, type);
452 if (result)
453 get_task_struct(result);
454 rcu_read_unlock();
455 return result;
456}
457EXPORT_SYMBOL_GPL(get_pid_task);
458
459struct pid *find_get_pid(pid_t nr)
460{
461 struct pid *pid;
462
463 rcu_read_lock();
464 pid = get_pid(find_vpid(nr));
465 rcu_read_unlock();
466
467 return pid;
468}
469EXPORT_SYMBOL_GPL(find_get_pid);
470
471pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
472{
473 struct upid *upid;
474 pid_t nr = 0;
475
476 if (pid && ns->level <= pid->level) {
477 upid = &pid->numbers[ns->level];
478 if (upid->ns == ns)
479 nr = upid->nr;
480 }
481 return nr;
482}
483EXPORT_SYMBOL_GPL(pid_nr_ns);
484
485pid_t pid_vnr(struct pid *pid)
486{
487 return pid_nr_ns(pid, task_active_pid_ns(current));
488}
489EXPORT_SYMBOL_GPL(pid_vnr);
490
491pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
492 struct pid_namespace *ns)
493{
494 pid_t nr = 0;
495
496 rcu_read_lock();
497 if (!ns)
498 ns = task_active_pid_ns(current);
499 nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
500 rcu_read_unlock();
501
502 return nr;
503}
504EXPORT_SYMBOL(__task_pid_nr_ns);
505
506struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
507{
508 return ns_of_pid(task_pid(tsk));
509}
510EXPORT_SYMBOL_GPL(task_active_pid_ns);
511
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517struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
518{
519 return idr_get_next(&ns->idr, &nr);
520}
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535static int pidfd_create(struct pid *pid)
536{
537 int fd;
538
539 fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
540 O_RDWR | O_CLOEXEC);
541 if (fd < 0)
542 put_pid(pid);
543
544 return fd;
545}
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563SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
564{
565 int fd;
566 struct pid *p;
567
568 if (flags)
569 return -EINVAL;
570
571 if (pid <= 0)
572 return -EINVAL;
573
574 p = find_get_pid(pid);
575 if (!p)
576 return -ESRCH;
577
578 if (pid_has_task(p, PIDTYPE_TGID))
579 fd = pidfd_create(p);
580 else
581 fd = -EINVAL;
582
583 put_pid(p);
584 return fd;
585}
586
587void __init pid_idr_init(void)
588{
589
590 BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
591
592
593 pid_max = min(pid_max_max, max_t(int, pid_max,
594 PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
595 pid_max_min = max_t(int, pid_max_min,
596 PIDS_PER_CPU_MIN * num_possible_cpus());
597 pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
598
599 idr_init(&init_pid_ns.idr);
600
601 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
602 SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
603}
604
605static struct file *__pidfd_fget(struct task_struct *task, int fd)
606{
607 struct file *file;
608 int ret;
609
610 ret = mutex_lock_killable(&task->signal->exec_update_mutex);
611 if (ret)
612 return ERR_PTR(ret);
613
614 if (ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS))
615 file = fget_task(task, fd);
616 else
617 file = ERR_PTR(-EPERM);
618
619 mutex_unlock(&task->signal->exec_update_mutex);
620
621 return file ?: ERR_PTR(-EBADF);
622}
623
624static int pidfd_getfd(struct pid *pid, int fd)
625{
626 struct task_struct *task;
627 struct file *file;
628 int ret;
629
630 task = get_pid_task(pid, PIDTYPE_PID);
631 if (!task)
632 return -ESRCH;
633
634 file = __pidfd_fget(task, fd);
635 put_task_struct(task);
636 if (IS_ERR(file))
637 return PTR_ERR(file);
638
639 ret = receive_fd(file, O_CLOEXEC);
640 fput(file);
641
642 return ret;
643}
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661SYSCALL_DEFINE3(pidfd_getfd, int, pidfd, int, fd,
662 unsigned int, flags)
663{
664 struct pid *pid;
665 struct fd f;
666 int ret;
667
668
669 if (flags)
670 return -EINVAL;
671
672 f = fdget(pidfd);
673 if (!f.file)
674 return -EBADF;
675
676 pid = pidfd_pid(f.file);
677 if (IS_ERR(pid))
678 ret = PTR_ERR(pid);
679 else
680 ret = pidfd_getfd(pid, fd);
681
682 fdput(f);
683 return ret;
684}
685