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29#include <linux/mm.h>
30#include <linux/module.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
40#define pid_hashfn(nr, ns) \
41 hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
42static struct hlist_head *pid_hash;
43static unsigned int pidhash_shift = 4;
44struct pid init_struct_pid = INIT_STRUCT_PID;
45
46int pid_max = PID_MAX_DEFAULT;
47
48#define RESERVED_PIDS 300
49
50int pid_max_min = RESERVED_PIDS + 1;
51int pid_max_max = PID_MAX_LIMIT;
52
53#define BITS_PER_PAGE (PAGE_SIZE*8)
54#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
55
56static inline int mk_pid(struct pid_namespace *pid_ns,
57 struct pidmap *map, int off)
58{
59 return (map - pid_ns->pidmap)*BITS_PER_PAGE + off;
60}
61
62#define find_next_offset(map, off) \
63 find_next_zero_bit((map)->page, BITS_PER_PAGE, off)
64
65
66
67
68
69
70
71struct pid_namespace init_pid_ns = {
72 .kref = {
73 .refcount = ATOMIC_INIT(2),
74 },
75 .pidmap = {
76 [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
77 },
78 .last_pid = 0,
79 .level = 0,
80 .child_reaper = &init_task,
81};
82EXPORT_SYMBOL_GPL(init_pid_ns);
83
84int is_container_init(struct task_struct *tsk)
85{
86 int ret = 0;
87 struct pid *pid;
88
89 rcu_read_lock();
90 pid = task_pid(tsk);
91 if (pid != NULL && pid->numbers[pid->level].nr == 1)
92 ret = 1;
93 rcu_read_unlock();
94
95 return ret;
96}
97EXPORT_SYMBOL(is_container_init);
98
99
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103
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111
112
113static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
114
115static void free_pidmap(struct upid *upid)
116{
117 int nr = upid->nr;
118 struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE;
119 int offset = nr & BITS_PER_PAGE_MASK;
120
121 clear_bit(offset, map->page);
122 atomic_inc(&map->nr_free);
123}
124
125
126
127
128static int pid_before(int base, int a, int b)
129{
130
131
132
133
134
135
136 return (unsigned)(a - base) < (unsigned)(b - base);
137}
138
139
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149
150
151
152static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid)
153{
154 int prev;
155 int last_write = base;
156 do {
157 prev = last_write;
158 last_write = cmpxchg(&pid_ns->last_pid, prev, pid);
159 } while ((prev != last_write) && (pid_before(base, last_write, pid)));
160}
161
162static int alloc_pidmap(struct pid_namespace *pid_ns)
163{
164 int i, offset, max_scan, pid, last = pid_ns->last_pid;
165 struct pidmap *map;
166
167 pid = last + 1;
168 if (pid >= pid_max)
169 pid = RESERVED_PIDS;
170 offset = pid & BITS_PER_PAGE_MASK;
171 map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
172
173
174
175
176
177 max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset;
178 for (i = 0; i <= max_scan; ++i) {
179 if (unlikely(!map->page)) {
180 void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
181
182
183
184
185 spin_lock_irq(&pidmap_lock);
186 if (!map->page) {
187 map->page = page;
188 page = NULL;
189 }
190 spin_unlock_irq(&pidmap_lock);
191 kfree(page);
192 if (unlikely(!map->page))
193 break;
194 }
195 if (likely(atomic_read(&map->nr_free))) {
196 do {
197 if (!test_and_set_bit(offset, map->page)) {
198 atomic_dec(&map->nr_free);
199 set_last_pid(pid_ns, last, pid);
200 return pid;
201 }
202 offset = find_next_offset(map, offset);
203 pid = mk_pid(pid_ns, map, offset);
204 } while (offset < BITS_PER_PAGE && pid < pid_max);
205 }
206 if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
207 ++map;
208 offset = 0;
209 } else {
210 map = &pid_ns->pidmap[0];
211 offset = RESERVED_PIDS;
212 if (unlikely(last == offset))
213 break;
214 }
215 pid = mk_pid(pid_ns, map, offset);
216 }
217 return -1;
218}
219
220int next_pidmap(struct pid_namespace *pid_ns, int last)
221{
222 int offset;
223 struct pidmap *map, *end;
224
225 offset = (last + 1) & BITS_PER_PAGE_MASK;
226 map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE];
227 end = &pid_ns->pidmap[PIDMAP_ENTRIES];
228 for (; map < end; map++, offset = 0) {
229 if (unlikely(!map->page))
230 continue;
231 offset = find_next_bit((map)->page, BITS_PER_PAGE, offset);
232 if (offset < BITS_PER_PAGE)
233 return mk_pid(pid_ns, map, offset);
234 }
235 return -1;
236}
237
238void put_pid(struct pid *pid)
239{
240 struct pid_namespace *ns;
241
242 if (!pid)
243 return;
244
245 ns = pid->numbers[pid->level].ns;
246 if ((atomic_read(&pid->count) == 1) ||
247 atomic_dec_and_test(&pid->count)) {
248 kmem_cache_free(ns->pid_cachep, pid);
249 put_pid_ns(ns);
250 }
251}
252EXPORT_SYMBOL_GPL(put_pid);
253
254static void delayed_put_pid(struct rcu_head *rhp)
255{
256 struct pid *pid = container_of(rhp, struct pid, rcu);
257 put_pid(pid);
258}
259
260void free_pid(struct pid *pid)
261{
262
263 int i;
264 unsigned long flags;
265
266 spin_lock_irqsave(&pidmap_lock, flags);
267 for (i = 0; i <= pid->level; i++)
268 hlist_del_rcu(&pid->numbers[i].pid_chain);
269 spin_unlock_irqrestore(&pidmap_lock, flags);
270
271 for (i = 0; i <= pid->level; i++)
272 free_pidmap(pid->numbers + i);
273
274 call_rcu(&pid->rcu, delayed_put_pid);
275}
276
277struct pid *alloc_pid(struct pid_namespace *ns)
278{
279 struct pid *pid;
280 enum pid_type type;
281 int i, nr;
282 struct pid_namespace *tmp;
283 struct upid *upid;
284
285 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
286 if (!pid)
287 goto out;
288
289 tmp = ns;
290 for (i = ns->level; i >= 0; i--) {
291 nr = alloc_pidmap(tmp);
292 if (nr < 0)
293 goto out_free;
294
295 pid->numbers[i].nr = nr;
296 pid->numbers[i].ns = tmp;
297 tmp = tmp->parent;
298 }
299
300 get_pid_ns(ns);
301 pid->level = ns->level;
302 atomic_set(&pid->count, 1);
303 for (type = 0; type < PIDTYPE_MAX; ++type)
304 INIT_HLIST_HEAD(&pid->tasks[type]);
305
306 upid = pid->numbers + ns->level;
307 spin_lock_irq(&pidmap_lock);
308 for ( ; upid >= pid->numbers; --upid)
309 hlist_add_head_rcu(&upid->pid_chain,
310 &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
311 spin_unlock_irq(&pidmap_lock);
312
313out:
314 return pid;
315
316out_free:
317 while (++i <= ns->level)
318 free_pidmap(pid->numbers + i);
319
320 kmem_cache_free(ns->pid_cachep, pid);
321 pid = NULL;
322 goto out;
323}
324
325struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
326{
327 struct hlist_node *elem;
328 struct upid *pnr;
329
330 hlist_for_each_entry_rcu(pnr, elem,
331 &pid_hash[pid_hashfn(nr, ns)], pid_chain)
332 if (pnr->nr == nr && pnr->ns == ns)
333 return container_of(pnr, struct pid,
334 numbers[ns->level]);
335
336 return NULL;
337}
338EXPORT_SYMBOL_GPL(find_pid_ns);
339
340struct pid *find_vpid(int nr)
341{
342 return find_pid_ns(nr, current->nsproxy->pid_ns);
343}
344EXPORT_SYMBOL_GPL(find_vpid);
345
346
347
348
349void attach_pid(struct task_struct *task, enum pid_type type,
350 struct pid *pid)
351{
352 struct pid_link *link;
353
354 link = &task->pids[type];
355 link->pid = pid;
356 hlist_add_head_rcu(&link->node, &pid->tasks[type]);
357}
358
359static void __change_pid(struct task_struct *task, enum pid_type type,
360 struct pid *new)
361{
362 struct pid_link *link;
363 struct pid *pid;
364 int tmp;
365
366 link = &task->pids[type];
367 pid = link->pid;
368
369 hlist_del_rcu(&link->node);
370 link->pid = new;
371
372 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
373 if (!hlist_empty(&pid->tasks[tmp]))
374 return;
375
376 free_pid(pid);
377}
378
379void detach_pid(struct task_struct *task, enum pid_type type)
380{
381 __change_pid(task, type, NULL);
382}
383
384void change_pid(struct task_struct *task, enum pid_type type,
385 struct pid *pid)
386{
387 __change_pid(task, type, pid);
388 attach_pid(task, type, pid);
389}
390
391
392void transfer_pid(struct task_struct *old, struct task_struct *new,
393 enum pid_type type)
394{
395 new->pids[type].pid = old->pids[type].pid;
396 hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
397}
398
399struct task_struct *pid_task(struct pid *pid, enum pid_type type)
400{
401 struct task_struct *result = NULL;
402 if (pid) {
403 struct hlist_node *first;
404 first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
405 rcu_read_lock_held() ||
406 lockdep_tasklist_lock_is_held());
407 if (first)
408 result = hlist_entry(first, struct task_struct, pids[(type)].node);
409 }
410 return result;
411}
412EXPORT_SYMBOL(pid_task);
413
414
415
416
417struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
418{
419 rcu_lockdep_assert(rcu_read_lock_held());
420 return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
421}
422
423struct task_struct *find_task_by_vpid(pid_t vnr)
424{
425 return find_task_by_pid_ns(vnr, current->nsproxy->pid_ns);
426}
427
428struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
429{
430 struct pid *pid;
431 rcu_read_lock();
432 if (type != PIDTYPE_PID)
433 task = task->group_leader;
434 pid = get_pid(task->pids[type].pid);
435 rcu_read_unlock();
436 return pid;
437}
438
439struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
440{
441 struct task_struct *result;
442 rcu_read_lock();
443 result = pid_task(pid, type);
444 if (result)
445 get_task_struct(result);
446 rcu_read_unlock();
447 return result;
448}
449
450struct pid *find_get_pid(pid_t nr)
451{
452 struct pid *pid;
453
454 rcu_read_lock();
455 pid = get_pid(find_vpid(nr));
456 rcu_read_unlock();
457
458 return pid;
459}
460EXPORT_SYMBOL_GPL(find_get_pid);
461
462pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
463{
464 struct upid *upid;
465 pid_t nr = 0;
466
467 if (pid && ns->level <= pid->level) {
468 upid = &pid->numbers[ns->level];
469 if (upid->ns == ns)
470 nr = upid->nr;
471 }
472 return nr;
473}
474
475pid_t pid_vnr(struct pid *pid)
476{
477 return pid_nr_ns(pid, current->nsproxy->pid_ns);
478}
479EXPORT_SYMBOL_GPL(pid_vnr);
480
481pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
482 struct pid_namespace *ns)
483{
484 pid_t nr = 0;
485
486 rcu_read_lock();
487 if (!ns)
488 ns = current->nsproxy->pid_ns;
489 if (likely(pid_alive(task))) {
490 if (type != PIDTYPE_PID)
491 task = task->group_leader;
492 nr = pid_nr_ns(task->pids[type].pid, ns);
493 }
494 rcu_read_unlock();
495
496 return nr;
497}
498EXPORT_SYMBOL(__task_pid_nr_ns);
499
500pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
501{
502 return pid_nr_ns(task_tgid(tsk), ns);
503}
504EXPORT_SYMBOL(task_tgid_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
512
513
514
515
516
517struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
518{
519 struct pid *pid;
520
521 do {
522 pid = find_pid_ns(nr, ns);
523 if (pid)
524 break;
525 nr = next_pidmap(ns, nr);
526 } while (nr > 0);
527
528 return pid;
529}
530
531
532
533
534
535
536void __init pidhash_init(void)
537{
538 int i, pidhash_size;
539
540 pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
541 HASH_EARLY | HASH_SMALL,
542 &pidhash_shift, NULL, 4096);
543 pidhash_size = 1 << pidhash_shift;
544
545 for (i = 0; i < pidhash_size; i++)
546 INIT_HLIST_HEAD(&pid_hash[i]);
547}
548
549void __init pidmap_init(void)
550{
551
552 pid_max = min(pid_max_max, max_t(int, pid_max,
553 PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
554 pid_max_min = max_t(int, pid_max_min,
555 PIDS_PER_CPU_MIN * num_possible_cpus());
556 pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
557
558 init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
559
560 set_bit(0, init_pid_ns.pidmap[0].page);
561 atomic_dec(&init_pid_ns.pidmap[0].nr_free);
562
563 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
564 SLAB_HWCACHE_ALIGN | SLAB_PANIC);
565}
566