projects/linux·blob v5.0-rc5 · refs

2666 lines · 63.4 KiB

1/*
2 * linux/kernel/fork.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
12 */
13
14#include <linux/slab.h>
15#include <linux/sched/autogroup.h>
16#include <linux/sched/mm.h>
17#include <linux/sched/coredump.h>
18#include <linux/sched/user.h>
19#include <linux/sched/numa_balancing.h>
20#include <linux/sched/stat.h>
21#include <linux/sched/task.h>
22#include <linux/sched/task_stack.h>
23#include <linux/sched/cputime.h>
24#include <linux/rtmutex.h>
25#include <linux/init.h>
26#include <linux/unistd.h>
27#include <linux/module.h>
28#include <linux/vmalloc.h>
29#include <linux/completion.h>
30#include <linux/personality.h>
31#include <linux/mempolicy.h>
32#include <linux/sem.h>
33#include <linux/file.h>
34#include <linux/fdtable.h>
35#include <linux/iocontext.h>
36#include <linux/key.h>
37#include <linux/binfmts.h>
38#include <linux/mman.h>
39#include <linux/mmu_notifier.h>
40#include <linux/hmm.h>
41#include <linux/fs.h>
42#include <linux/mm.h>
43#include <linux/vmacache.h>
44#include <linux/nsproxy.h>
45#include <linux/capability.h>
46#include <linux/cpu.h>
47#include <linux/cgroup.h>
48#include <linux/security.h>
49#include <linux/hugetlb.h>
50#include <linux/seccomp.h>
51#include <linux/swap.h>
52#include <linux/syscalls.h>
53#include <linux/jiffies.h>
54#include <linux/futex.h>
55#include <linux/compat.h>
56#include <linux/kthread.h>
57#include <linux/task_io_accounting_ops.h>
58#include <linux/rcupdate.h>
59#include <linux/ptrace.h>
60#include <linux/mount.h>
61#include <linux/audit.h>
62#include <linux/memcontrol.h>
63#include <linux/ftrace.h>
64#include <linux/proc_fs.h>
65#include <linux/profile.h>
66#include <linux/rmap.h>
67#include <linux/ksm.h>
68#include <linux/acct.h>
69#include <linux/userfaultfd_k.h>
70#include <linux/tsacct_kern.h>
71#include <linux/cn_proc.h>
72#include <linux/freezer.h>
73#include <linux/delayacct.h>
74#include <linux/taskstats_kern.h>
75#include <linux/random.h>
76#include <linux/tty.h>
77#include <linux/blkdev.h>
78#include <linux/fs_struct.h>
79#include <linux/magic.h>
80#include <linux/sched/mm.h>
81#include <linux/perf_event.h>
82#include <linux/posix-timers.h>
83#include <linux/user-return-notifier.h>
84#include <linux/oom.h>
85#include <linux/khugepaged.h>
86#include <linux/signalfd.h>
87#include <linux/uprobes.h>
88#include <linux/aio.h>
89#include <linux/compiler.h>
90#include <linux/sysctl.h>
91#include <linux/kcov.h>
92#include <linux/livepatch.h>
93#include <linux/thread_info.h>
94#include <linux/stackleak.h>
95
96#include <asm/pgtable.h>
97#include <asm/pgalloc.h>
98#include <linux/uaccess.h>
99#include <asm/mmu_context.h>
100#include <asm/cacheflush.h>
101#include <asm/tlbflush.h>
102
103#include <trace/events/sched.h>
104
105#define CREATE_TRACE_POINTS
106#include <trace/events/task.h>
107
108/*
109 * Minimum number of threads to boot the kernel
110 */
111#define MIN_THREADS 20
112
113/*
114 * Maximum number of threads
115 */
116#define MAX_THREADS FUTEX_TID_MASK
117
118/*
119 * Protected counters by write_lock_irq(&tasklist_lock)
120 */
121unsigned long total_forks; /* Handle normal Linux uptimes. */
122int nr_threads; /* The idle threads do not count.. */
123
124int max_threads; /* tunable limit on nr_threads */
125
126DEFINE_PER_CPU(unsigned long, process_counts) = 0;
127
128__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
129
130#ifdef CONFIG_PROVE_RCU
131int lockdep_tasklist_lock_is_held(void)
132{
133 return lockdep_is_held(&tasklist_lock);
134}
135EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
136#endif /* #ifdef CONFIG_PROVE_RCU */
137
138int nr_processes(void)
139{
140 int cpu;
141 int total = 0;
142
143 for_each_possible_cpu(cpu)
144 total += per_cpu(process_counts, cpu);
145
146 return total;
147}
148
149void __weak arch_release_task_struct(struct task_struct *tsk)
150{
151}
152
153#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
154static struct kmem_cache *task_struct_cachep;
155
156static inline struct task_struct *alloc_task_struct_node(int node)
157{
158 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
159}
160
161static inline void free_task_struct(struct task_struct *tsk)
162{
163 kmem_cache_free(task_struct_cachep, tsk);
164}
165#endif
166
167#ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
168
169/*
170 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
171 * kmemcache based allocator.
172 */
173# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
174
175#ifdef CONFIG_VMAP_STACK
176/*
177 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
178 * flush. Try to minimize the number of calls by caching stacks.
179 */
180#define NR_CACHED_STACKS 2
181static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
182
183static int free_vm_stack_cache(unsigned int cpu)
184{
185 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
186 int i;
187
188 for (i = 0; i < NR_CACHED_STACKS; i++) {
189 struct vm_struct *vm_stack = cached_vm_stacks[i];
190
191 if (!vm_stack)
192 continue;
193
194 vfree(vm_stack->addr);
195 cached_vm_stacks[i] = NULL;
196 }
197
198 return 0;
199}
200#endif
201
202static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
203{
204#ifdef CONFIG_VMAP_STACK
205 void *stack;
206 int i;
207
208 for (i = 0; i < NR_CACHED_STACKS; i++) {
209 struct vm_struct *s;
210
211 s = this_cpu_xchg(cached_stacks[i], NULL);
212
213 if (!s)
214 continue;
215
216 /* Clear stale pointers from reused stack. */
217 memset(s->addr, 0, THREAD_SIZE);
218
219 tsk->stack_vm_area = s;
220 tsk->stack = s->addr;
221 return s->addr;
222 }
223
224 /*
225 * Allocated stacks are cached and later reused by new threads,
226 * so memcg accounting is performed manually on assigning/releasing
227 * stacks to tasks. Drop __GFP_ACCOUNT.
228 */
229 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
230 VMALLOC_START, VMALLOC_END,
231 THREADINFO_GFP & ~__GFP_ACCOUNT,
232 PAGE_KERNEL,
233 0, node, __builtin_return_address(0));
234
235 /*
236 * We can't call find_vm_area() in interrupt context, and
237 * free_thread_stack() can be called in interrupt context,
238 * so cache the vm_struct.
239 */
240 if (stack) {
241 tsk->stack_vm_area = find_vm_area(stack);
242 tsk->stack = stack;
243 }
244 return stack;
245#else
246 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
247 THREAD_SIZE_ORDER);
248
249 return page ? page_address(page) : NULL;
250#endif
251}
252
253static inline void free_thread_stack(struct task_struct *tsk)
254{
255#ifdef CONFIG_VMAP_STACK
256 struct vm_struct *vm = task_stack_vm_area(tsk);
257
258 if (vm) {
259 int i;
260
261 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
262 mod_memcg_page_state(vm->pages[i],
263 MEMCG_KERNEL_STACK_KB,
264 -(int)(PAGE_SIZE / 1024));
265
266 memcg_kmem_uncharge(vm->pages[i], 0);
267 }
268
269 for (i = 0; i < NR_CACHED_STACKS; i++) {
270 if (this_cpu_cmpxchg(cached_stacks[i],
271 NULL, tsk->stack_vm_area) != NULL)
272 continue;
273
274 return;
275 }
276
277 vfree_atomic(tsk->stack);
278 return;
279 }
280#endif
281
282 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
283}
284# else
285static struct kmem_cache *thread_stack_cache;
286
287static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
288 int node)
289{
290 unsigned long *stack;
291 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
292 tsk->stack = stack;
293 return stack;
294}
295
296static void free_thread_stack(struct task_struct *tsk)
297{
298 kmem_cache_free(thread_stack_cache, tsk->stack);
299}
300
301void thread_stack_cache_init(void)
302{
303 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
304 THREAD_SIZE, THREAD_SIZE, 0, 0,
305 THREAD_SIZE, NULL);
306 BUG_ON(thread_stack_cache == NULL);
307}
308# endif
309#endif
310
311/* SLAB cache for signal_struct structures (tsk->signal) */
312static struct kmem_cache *signal_cachep;
313
314/* SLAB cache for sighand_struct structures (tsk->sighand) */
315struct kmem_cache *sighand_cachep;
316
317/* SLAB cache for files_struct structures (tsk->files) */
318struct kmem_cache *files_cachep;
319
320/* SLAB cache for fs_struct structures (tsk->fs) */
321struct kmem_cache *fs_cachep;
322
323/* SLAB cache for vm_area_struct structures */
324static struct kmem_cache *vm_area_cachep;
325
326/* SLAB cache for mm_struct structures (tsk->mm) */
327static struct kmem_cache *mm_cachep;
328
329struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
330{
331 struct vm_area_struct *vma;
332
333 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
334 if (vma)
335 vma_init(vma, mm);
336 return vma;
337}
338
339struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
340{
341 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
342
343 if (new) {
344 *new = *orig;
345 INIT_LIST_HEAD(&new->anon_vma_chain);
346 }
347 return new;
348}
349
350void vm_area_free(struct vm_area_struct *vma)
351{
352 kmem_cache_free(vm_area_cachep, vma);
353}
354
355static void account_kernel_stack(struct task_struct *tsk, int account)
356{
357 void *stack = task_stack_page(tsk);
358 struct vm_struct *vm = task_stack_vm_area(tsk);
359
360 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
361
362 if (vm) {
363 int i;
364
365 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
366
367 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
368 mod_zone_page_state(page_zone(vm->pages[i]),
369 NR_KERNEL_STACK_KB,
370 PAGE_SIZE / 1024 * account);
371 }
372 } else {
373 /*
374 * All stack pages are in the same zone and belong to the
375 * same memcg.
376 */
377 struct page *first_page = virt_to_page(stack);
378
379 mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
380 THREAD_SIZE / 1024 * account);
381
382 mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
383 account * (THREAD_SIZE / 1024));
384 }
385}
386
387static int memcg_charge_kernel_stack(struct task_struct *tsk)
388{
389#ifdef CONFIG_VMAP_STACK
390 struct vm_struct *vm = task_stack_vm_area(tsk);
391 int ret;
392
393 if (vm) {
394 int i;
395
396 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
397 /*
398 * If memcg_kmem_charge() fails, page->mem_cgroup
399 * pointer is NULL, and both memcg_kmem_uncharge()
400 * and mod_memcg_page_state() in free_thread_stack()
401 * will ignore this page. So it's safe.
402 */
403 ret = memcg_kmem_charge(vm->pages[i], GFP_KERNEL, 0);
404 if (ret)
405 return ret;
406
407 mod_memcg_page_state(vm->pages[i],
408 MEMCG_KERNEL_STACK_KB,
409 PAGE_SIZE / 1024);
410 }
411 }
412#endif
413 return 0;
414}
415
416static void release_task_stack(struct task_struct *tsk)
417{
418 if (WARN_ON(tsk->state != TASK_DEAD))
419 return; /* Better to leak the stack than to free prematurely */
420
421 account_kernel_stack(tsk, -1);
422 free_thread_stack(tsk);
423 tsk->stack = NULL;
424#ifdef CONFIG_VMAP_STACK
425 tsk->stack_vm_area = NULL;
426#endif
427}
428
429#ifdef CONFIG_THREAD_INFO_IN_TASK
430void put_task_stack(struct task_struct *tsk)
431{
432 if (atomic_dec_and_test(&tsk->stack_refcount))
433 release_task_stack(tsk);
434}
435#endif
436
437void free_task(struct task_struct *tsk)
438{
439#ifndef CONFIG_THREAD_INFO_IN_TASK
440 /*
441 * The task is finally done with both the stack and thread_info,
442 * so free both.
443 */
444 release_task_stack(tsk);
445#else
446 /*
447 * If the task had a separate stack allocation, it should be gone
448 * by now.
449 */
450 WARN_ON_ONCE(atomic_read(&tsk->stack_refcount) != 0);
451#endif
452 rt_mutex_debug_task_free(tsk);
453 ftrace_graph_exit_task(tsk);
454 put_seccomp_filter(tsk);
455 arch_release_task_struct(tsk);
456 if (tsk->flags & PF_KTHREAD)
457 free_kthread_struct(tsk);
458 free_task_struct(tsk);
459}
460EXPORT_SYMBOL(free_task);
461
462#ifdef CONFIG_MMU
463static __latent_entropy int dup_mmap(struct mm_struct *mm,
464 struct mm_struct *oldmm)
465{
466 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
467 struct rb_node **rb_link, *rb_parent;
468 int retval;
469 unsigned long charge;
470 LIST_HEAD(uf);
471
472 uprobe_start_dup_mmap();
473 if (down_write_killable(&oldmm->mmap_sem)) {
474 retval = -EINTR;
475 goto fail_uprobe_end;
476 }
477 flush_cache_dup_mm(oldmm);
478 uprobe_dup_mmap(oldmm, mm);
479 /*
480 * Not linked in yet - no deadlock potential:
481 */
482 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
483
484 /* No ordering required: file already has been exposed. */
485 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
486
487 mm->total_vm = oldmm->total_vm;
488 mm->data_vm = oldmm->data_vm;
489 mm->exec_vm = oldmm->exec_vm;
490 mm->stack_vm = oldmm->stack_vm;
491
492 rb_link = &mm->mm_rb.rb_node;
493 rb_parent = NULL;
494 pprev = &mm->mmap;
495 retval = ksm_fork(mm, oldmm);
496 if (retval)
497 goto out;
498 retval = khugepaged_fork(mm, oldmm);
499 if (retval)
500 goto out;
501
502 prev = NULL;
503 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
504 struct file *file;
505
506 if (mpnt->vm_flags & VM_DONTCOPY) {
507 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
508 continue;
509 }
510 charge = 0;
511 /*
512 * Don't duplicate many vmas if we've been oom-killed (for
513 * example)
514 */
515 if (fatal_signal_pending(current)) {
516 retval = -EINTR;
517 goto out;
518 }
519 if (mpnt->vm_flags & VM_ACCOUNT) {
520 unsigned long len = vma_pages(mpnt);
521
522 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
523 goto fail_nomem;
524 charge = len;
525 }
526 tmp = vm_area_dup(mpnt);
527 if (!tmp)
528 goto fail_nomem;
529 retval = vma_dup_policy(mpnt, tmp);
530 if (retval)
531 goto fail_nomem_policy;
532 tmp->vm_mm = mm;
533 retval = dup_userfaultfd(tmp, &uf);
534 if (retval)
535 goto fail_nomem_anon_vma_fork;
536 if (tmp->vm_flags & VM_WIPEONFORK) {
537 /* VM_WIPEONFORK gets a clean slate in the child. */
538 tmp->anon_vma = NULL;
539 if (anon_vma_prepare(tmp))
540 goto fail_nomem_anon_vma_fork;
541 } else if (anon_vma_fork(tmp, mpnt))
542 goto fail_nomem_anon_vma_fork;
543 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
544 tmp->vm_next = tmp->vm_prev = NULL;
545 file = tmp->vm_file;
546 if (file) {
547 struct inode *inode = file_inode(file);
548 struct address_space *mapping = file->f_mapping;
549
550 get_file(file);
551 if (tmp->vm_flags & VM_DENYWRITE)
552 atomic_dec(&inode->i_writecount);
553 i_mmap_lock_write(mapping);
554 if (tmp->vm_flags & VM_SHARED)
555 atomic_inc(&mapping->i_mmap_writable);
556 flush_dcache_mmap_lock(mapping);
557 /* insert tmp into the share list, just after mpnt */
558 vma_interval_tree_insert_after(tmp, mpnt,
559 &mapping->i_mmap);
560 flush_dcache_mmap_unlock(mapping);
561 i_mmap_unlock_write(mapping);
562 }
563
564 /*
565 * Clear hugetlb-related page reserves for children. This only
566 * affects MAP_PRIVATE mappings. Faults generated by the child
567 * are not guaranteed to succeed, even if read-only
568 */
569 if (is_vm_hugetlb_page(tmp))
570 reset_vma_resv_huge_pages(tmp);
571
572 /*
573 * Link in the new vma and copy the page table entries.
574 */
575 *pprev = tmp;
576 pprev = &tmp->vm_next;
577 tmp->vm_prev = prev;
578 prev = tmp;
579
580 __vma_link_rb(mm, tmp, rb_link, rb_parent);
581 rb_link = &tmp->vm_rb.rb_right;
582 rb_parent = &tmp->vm_rb;
583
584 mm->map_count++;
585 if (!(tmp->vm_flags & VM_WIPEONFORK))
586 retval = copy_page_range(mm, oldmm, mpnt);
587
588 if (tmp->vm_ops && tmp->vm_ops->open)
589 tmp->vm_ops->open(tmp);
590
591 if (retval)
592 goto out;
593 }
594 /* a new mm has just been created */
595 retval = arch_dup_mmap(oldmm, mm);
596out:
597 up_write(&mm->mmap_sem);
598 flush_tlb_mm(oldmm);
599 up_write(&oldmm->mmap_sem);
600 dup_userfaultfd_complete(&uf);
601fail_uprobe_end:
602 uprobe_end_dup_mmap();
603 return retval;
604fail_nomem_anon_vma_fork:
605 mpol_put(vma_policy(tmp));
606fail_nomem_policy:
607 vm_area_free(tmp);
608fail_nomem:
609 retval = -ENOMEM;
610 vm_unacct_memory(charge);
611 goto out;
612}
613
614static inline int mm_alloc_pgd(struct mm_struct *mm)
615{
616 mm->pgd = pgd_alloc(mm);
617 if (unlikely(!mm->pgd))
618 return -ENOMEM;
619 return 0;
620}
621
622static inline void mm_free_pgd(struct mm_struct *mm)
623{
624 pgd_free(mm, mm->pgd);
625}
626#else
627static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
628{
629 down_write(&oldmm->mmap_sem);
630 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
631 up_write(&oldmm->mmap_sem);
632 return 0;
633}
634#define mm_alloc_pgd(mm) (0)
635#define mm_free_pgd(mm)
636#endif /* CONFIG_MMU */
637
638static void check_mm(struct mm_struct *mm)
639{
640 int i;
641
642 for (i = 0; i < NR_MM_COUNTERS; i++) {
643 long x = atomic_long_read(&mm->rss_stat.count[i]);
644
645 if (unlikely(x))
646 printk(KERN_ALERT "BUG: Bad rss-counter state "
647 "mm:%p idx:%d val:%ld\n", mm, i, x);
648 }
649
650 if (mm_pgtables_bytes(mm))
651 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
652 mm_pgtables_bytes(mm));
653
654#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
655 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
656#endif
657}
658
659#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
660#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
661
662/*
663 * Called when the last reference to the mm
664 * is dropped: either by a lazy thread or by
665 * mmput. Free the page directory and the mm.
666 */
667void __mmdrop(struct mm_struct *mm)
668{
669 BUG_ON(mm == &init_mm);
670 WARN_ON_ONCE(mm == current->mm);
671 WARN_ON_ONCE(mm == current->active_mm);
672 mm_free_pgd(mm);
673 destroy_context(mm);
674 hmm_mm_destroy(mm);
675 mmu_notifier_mm_destroy(mm);
676 check_mm(mm);
677 put_user_ns(mm->user_ns);
678 free_mm(mm);
679}
680EXPORT_SYMBOL_GPL(__mmdrop);
681
682static void mmdrop_async_fn(struct work_struct *work)
683{
684 struct mm_struct *mm;
685
686 mm = container_of(work, struct mm_struct, async_put_work);
687 __mmdrop(mm);
688}
689
690static void mmdrop_async(struct mm_struct *mm)
691{
692 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
693 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
694 schedule_work(&mm->async_put_work);
695 }
696}
697
698static inline void free_signal_struct(struct signal_struct *sig)
699{
700 taskstats_tgid_free(sig);
701 sched_autogroup_exit(sig);
702 /*
703 * __mmdrop is not safe to call from softirq context on x86 due to
704 * pgd_dtor so postpone it to the async context
705 */
706 if (sig->oom_mm)
707 mmdrop_async(sig->oom_mm);
708 kmem_cache_free(signal_cachep, sig);
709}
710
711static inline void put_signal_struct(struct signal_struct *sig)
712{
713 if (atomic_dec_and_test(&sig->sigcnt))
714 free_signal_struct(sig);
715}
716
717void __put_task_struct(struct task_struct *tsk)
718{
719 WARN_ON(!tsk->exit_state);
720 WARN_ON(atomic_read(&tsk->usage));
721 WARN_ON(tsk == current);
722
723 cgroup_free(tsk);
724 task_numa_free(tsk);
725 security_task_free(tsk);
726 exit_creds(tsk);
727 delayacct_tsk_free(tsk);
728 put_signal_struct(tsk->signal);
729
730 if (!profile_handoff_task(tsk))
731 free_task(tsk);
732}
733EXPORT_SYMBOL_GPL(__put_task_struct);
734
735void __init __weak arch_task_cache_init(void) { }
736
737/*
738 * set_max_threads
739 */
740static void set_max_threads(unsigned int max_threads_suggested)
741{
742 u64 threads;
743 unsigned long nr_pages = totalram_pages();
744
745 /*
746 * The number of threads shall be limited such that the thread
747 * structures may only consume a small part of the available memory.
748 */
749 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
750 threads = MAX_THREADS;
751 else
752 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
753 (u64) THREAD_SIZE * 8UL);
754
755 if (threads > max_threads_suggested)
756 threads = max_threads_suggested;
757
758 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
759}
760
761#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
762/* Initialized by the architecture: */
763int arch_task_struct_size __read_mostly;
764#endif
765
766static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
767{
768 /* Fetch thread_struct whitelist for the architecture. */
769 arch_thread_struct_whitelist(offset, size);
770
771 /*
772 * Handle zero-sized whitelist or empty thread_struct, otherwise
773 * adjust offset to position of thread_struct in task_struct.
774 */
775 if (unlikely(*size == 0))
776 *offset = 0;
777 else
778 *offset += offsetof(struct task_struct, thread);
779}
780
781void __init fork_init(void)
782{
783 int i;
784#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
785#ifndef ARCH_MIN_TASKALIGN
786#define ARCH_MIN_TASKALIGN 0
787#endif
788 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
789 unsigned long useroffset, usersize;
790
791 /* create a slab on which task_structs can be allocated */
792 task_struct_whitelist(&useroffset, &usersize);
793 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
794 arch_task_struct_size, align,
795 SLAB_PANIC|SLAB_ACCOUNT,
796 useroffset, usersize, NULL);
797#endif
798
799 /* do the arch specific task caches init */
800 arch_task_cache_init();
801
802 set_max_threads(MAX_THREADS);
803
804 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
805 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
806 init_task.signal->rlim[RLIMIT_SIGPENDING] =
807 init_task.signal->rlim[RLIMIT_NPROC];
808
809 for (i = 0; i < UCOUNT_COUNTS; i++) {
810 init_user_ns.ucount_max[i] = max_threads/2;
811 }
812
813#ifdef CONFIG_VMAP_STACK
814 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
815 NULL, free_vm_stack_cache);
816#endif
817
818 lockdep_init_task(&init_task);
819}
820
821int __weak arch_dup_task_struct(struct task_struct *dst,
822 struct task_struct *src)
823{
824 *dst = *src;
825 return 0;
826}
827
828void set_task_stack_end_magic(struct task_struct *tsk)
829{
830 unsigned long *stackend;
831
832 stackend = end_of_stack(tsk);
833 *stackend = STACK_END_MAGIC; /* for overflow detection */
834}
835
836static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
837{
838 struct task_struct *tsk;
839 unsigned long *stack;
840 struct vm_struct *stack_vm_area __maybe_unused;
841 int err;
842
843 if (node == NUMA_NO_NODE)
844 node = tsk_fork_get_node(orig);
845 tsk = alloc_task_struct_node(node);
846 if (!tsk)
847 return NULL;
848
849 stack = alloc_thread_stack_node(tsk, node);
850 if (!stack)
851 goto free_tsk;
852
853 if (memcg_charge_kernel_stack(tsk))
854 goto free_stack;
855
856 stack_vm_area = task_stack_vm_area(tsk);
857
858 err = arch_dup_task_struct(tsk, orig);
859
860 /*
861 * arch_dup_task_struct() clobbers the stack-related fields. Make
862 * sure they're properly initialized before using any stack-related
863 * functions again.
864 */
865 tsk->stack = stack;
866#ifdef CONFIG_VMAP_STACK
867 tsk->stack_vm_area = stack_vm_area;
868#endif
869#ifdef CONFIG_THREAD_INFO_IN_TASK
870 atomic_set(&tsk->stack_refcount, 1);
871#endif
872
873 if (err)
874 goto free_stack;
875
876#ifdef CONFIG_SECCOMP
877 /*
878 * We must handle setting up seccomp filters once we're under
879 * the sighand lock in case orig has changed between now and
880 * then. Until then, filter must be NULL to avoid messing up
881 * the usage counts on the error path calling free_task.
882 */
883 tsk->seccomp.filter = NULL;
884#endif
885
886 setup_thread_stack(tsk, orig);
887 clear_user_return_notifier(tsk);
888 clear_tsk_need_resched(tsk);
889 set_task_stack_end_magic(tsk);
890
891#ifdef CONFIG_STACKPROTECTOR
892 tsk->stack_canary = get_random_canary();
893#endif
894
895 /*
896 * One for us, one for whoever does the "release_task()" (usually
897 * parent)
898 */
899 atomic_set(&tsk->usage, 2);
900#ifdef CONFIG_BLK_DEV_IO_TRACE
901 tsk->btrace_seq = 0;
902#endif
903 tsk->splice_pipe = NULL;
904 tsk->task_frag.page = NULL;
905 tsk->wake_q.next = NULL;
906
907 account_kernel_stack(tsk, 1);
908
909 kcov_task_init(tsk);
910
911#ifdef CONFIG_FAULT_INJECTION
912 tsk->fail_nth = 0;
913#endif
914
915#ifdef CONFIG_BLK_CGROUP
916 tsk->throttle_queue = NULL;
917 tsk->use_memdelay = 0;
918#endif
919
920#ifdef CONFIG_MEMCG
921 tsk->active_memcg = NULL;
922#endif
923 return tsk;
924
925free_stack:
926 free_thread_stack(tsk);
927free_tsk:
928 free_task_struct(tsk);
929 return NULL;
930}
931
932__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
933
934static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
935
936static int __init coredump_filter_setup(char *s)
937{
938 default_dump_filter =
939 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
940 MMF_DUMP_FILTER_MASK;
941 return 1;
942}
943
944__setup("coredump_filter=", coredump_filter_setup);
945
946#include <linux/init_task.h>
947
948static void mm_init_aio(struct mm_struct *mm)
949{
950#ifdef CONFIG_AIO
951 spin_lock_init(&mm->ioctx_lock);
952 mm->ioctx_table = NULL;
953#endif
954}
955
956static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
957{
958#ifdef CONFIG_MEMCG
959 mm->owner = p;
960#endif
961}
962
963static void mm_init_uprobes_state(struct mm_struct *mm)
964{
965#ifdef CONFIG_UPROBES
966 mm->uprobes_state.xol_area = NULL;
967#endif
968}
969
970static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
971 struct user_namespace *user_ns)
972{
973 mm->mmap = NULL;
974 mm->mm_rb = RB_ROOT;
975 mm->vmacache_seqnum = 0;
976 atomic_set(&mm->mm_users, 1);
977 atomic_set(&mm->mm_count, 1);
978 init_rwsem(&mm->mmap_sem);
979 INIT_LIST_HEAD(&mm->mmlist);
980 mm->core_state = NULL;
981 mm_pgtables_bytes_init(mm);
982 mm->map_count = 0;
983 mm->locked_vm = 0;
984 mm->pinned_vm = 0;
985 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
986 spin_lock_init(&mm->page_table_lock);
987 spin_lock_init(&mm->arg_lock);
988 mm_init_cpumask(mm);
989 mm_init_aio(mm);
990 mm_init_owner(mm, p);
991 RCU_INIT_POINTER(mm->exe_file, NULL);
992 mmu_notifier_mm_init(mm);
993 hmm_mm_init(mm);
994 init_tlb_flush_pending(mm);
995#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
996 mm->pmd_huge_pte = NULL;
997#endif
998 mm_init_uprobes_state(mm);
999
1000 if (current->mm) {
1001 mm->flags = current->mm->flags & MMF_INIT_MASK;
1002 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1003 } else {
1004 mm->flags = default_dump_filter;
1005 mm->def_flags = 0;
1006 }
1007
1008 if (mm_alloc_pgd(mm))
1009 goto fail_nopgd;
1010
1011 if (init_new_context(p, mm))
1012 goto fail_nocontext;
1013
1014 mm->user_ns = get_user_ns(user_ns);
1015 return mm;
1016
1017fail_nocontext:
1018 mm_free_pgd(mm);
1019fail_nopgd:
1020 free_mm(mm);
1021 return NULL;
1022}
1023
1024/*
1025 * Allocate and initialize an mm_struct.
1026 */
1027struct mm_struct *mm_alloc(void)
1028{
1029 struct mm_struct *mm;
1030
1031 mm = allocate_mm();
1032 if (!mm)
1033 return NULL;
1034
1035 memset(mm, 0, sizeof(*mm));
1036 return mm_init(mm, current, current_user_ns());
1037}
1038
1039static inline void __mmput(struct mm_struct *mm)
1040{
1041 VM_BUG_ON(atomic_read(&mm->mm_users));
1042
1043 uprobe_clear_state(mm);
1044 exit_aio(mm);
1045 ksm_exit(mm);
1046 khugepaged_exit(mm); /* must run before exit_mmap */
1047 exit_mmap(mm);
1048 mm_put_huge_zero_page(mm);
1049 set_mm_exe_file(mm, NULL);
1050 if (!list_empty(&mm->mmlist)) {
1051 spin_lock(&mmlist_lock);
1052 list_del(&mm->mmlist);
1053 spin_unlock(&mmlist_lock);
1054 }
1055 if (mm->binfmt)
1056 module_put(mm->binfmt->module);
1057 mmdrop(mm);
1058}
1059
1060/*
1061 * Decrement the use count and release all resources for an mm.
1062 */
1063void mmput(struct mm_struct *mm)
1064{
1065 might_sleep();
1066
1067 if (atomic_dec_and_test(&mm->mm_users))
1068 __mmput(mm);
1069}
1070EXPORT_SYMBOL_GPL(mmput);
1071
1072#ifdef CONFIG_MMU
1073static void mmput_async_fn(struct work_struct *work)
1074{
1075 struct mm_struct *mm = container_of(work, struct mm_struct,
1076 async_put_work);
1077
1078 __mmput(mm);
1079}
1080
1081void mmput_async(struct mm_struct *mm)
1082{
1083 if (atomic_dec_and_test(&mm->mm_users)) {
1084 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1085 schedule_work(&mm->async_put_work);
1086 }
1087}
1088#endif
1089
1090/**
1091 * set_mm_exe_file - change a reference to the mm's executable file
1092 *
1093 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1094 *
1095 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1096 * invocations: in mmput() nobody alive left, in execve task is single
1097 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1098 * mm->exe_file, but does so without using set_mm_exe_file() in order
1099 * to do avoid the need for any locks.
1100 */
1101void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1102{
1103 struct file *old_exe_file;
1104
1105 /*
1106 * It is safe to dereference the exe_file without RCU as
1107 * this function is only called if nobody else can access
1108 * this mm -- see comment above for justification.
1109 */
1110 old_exe_file = rcu_dereference_raw(mm->exe_file);
1111
1112 if (new_exe_file)
1113 get_file(new_exe_file);
1114 rcu_assign_pointer(mm->exe_file, new_exe_file);
1115 if (old_exe_file)
1116 fput(old_exe_file);
1117}
1118
1119/**
1120 * get_mm_exe_file - acquire a reference to the mm's executable file
1121 *
1122 * Returns %NULL if mm has no associated executable file.
1123 * User must release file via fput().
1124 */
1125struct file *get_mm_exe_file(struct mm_struct *mm)
1126{
1127 struct file *exe_file;
1128
1129 rcu_read_lock();
1130 exe_file = rcu_dereference(mm->exe_file);
1131 if (exe_file && !get_file_rcu(exe_file))
1132 exe_file = NULL;
1133 rcu_read_unlock();
1134 return exe_file;
1135}
1136EXPORT_SYMBOL(get_mm_exe_file);
1137
1138/**
1139 * get_task_exe_file - acquire a reference to the task's executable file
1140 *
1141 * Returns %NULL if task's mm (if any) has no associated executable file or
1142 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1143 * User must release file via fput().
1144 */
1145struct file *get_task_exe_file(struct task_struct *task)
1146{
1147 struct file *exe_file = NULL;
1148 struct mm_struct *mm;
1149
1150 task_lock(task);
1151 mm = task->mm;
1152 if (mm) {
1153 if (!(task->flags & PF_KTHREAD))
1154 exe_file = get_mm_exe_file(mm);
1155 }
1156 task_unlock(task);
1157 return exe_file;
1158}
1159EXPORT_SYMBOL(get_task_exe_file);
1160
1161/**
1162 * get_task_mm - acquire a reference to the task's mm
1163 *
1164 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1165 * this kernel workthread has transiently adopted a user mm with use_mm,
1166 * to do its AIO) is not set and if so returns a reference to it, after
1167 * bumping up the use count. User must release the mm via mmput()
1168 * after use. Typically used by /proc and ptrace.
1169 */
1170struct mm_struct *get_task_mm(struct task_struct *task)
1171{
1172 struct mm_struct *mm;
1173
1174 task_lock(task);
1175 mm = task->mm;
1176 if (mm) {
1177 if (task->flags & PF_KTHREAD)
1178 mm = NULL;
1179 else
1180 mmget(mm);
1181 }
1182 task_unlock(task);
1183 return mm;
1184}
1185EXPORT_SYMBOL_GPL(get_task_mm);
1186
1187struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1188{
1189 struct mm_struct *mm;
1190 int err;
1191
1192 err = mutex_lock_killable(&task->signal->cred_guard_mutex);
1193 if (err)
1194 return ERR_PTR(err);
1195
1196 mm = get_task_mm(task);
1197 if (mm && mm != current->mm &&
1198 !ptrace_may_access(task, mode)) {
1199 mmput(mm);
1200 mm = ERR_PTR(-EACCES);
1201 }
1202 mutex_unlock(&task->signal->cred_guard_mutex);
1203
1204 return mm;
1205}
1206
1207static void complete_vfork_done(struct task_struct *tsk)
1208{
1209 struct completion *vfork;
1210
1211 task_lock(tsk);
1212 vfork = tsk->vfork_done;
1213 if (likely(vfork)) {
1214 tsk->vfork_done = NULL;
1215 complete(vfork);
1216 }
1217 task_unlock(tsk);
1218}
1219
1220static int wait_for_vfork_done(struct task_struct *child,
1221 struct completion *vfork)
1222{
1223 int killed;
1224
1225 freezer_do_not_count();
1226 killed = wait_for_completion_killable(vfork);
1227 freezer_count();
1228
1229 if (killed) {
1230 task_lock(child);
1231 child->vfork_done = NULL;
1232 task_unlock(child);
1233 }
1234
1235 put_task_struct(child);
1236 return killed;
1237}
1238
1239/* Please note the differences between mmput and mm_release.
1240 * mmput is called whenever we stop holding onto a mm_struct,
1241 * error success whatever.
1242 *
1243 * mm_release is called after a mm_struct has been removed
1244 * from the current process.
1245 *
1246 * This difference is important for error handling, when we
1247 * only half set up a mm_struct for a new process and need to restore
1248 * the old one. Because we mmput the new mm_struct before
1249 * restoring the old one. . .
1250 * Eric Biederman 10 January 1998
1251 */
1252void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1253{
1254 /* Get rid of any futexes when releasing the mm */
1255#ifdef CONFIG_FUTEX
1256 if (unlikely(tsk->robust_list)) {
1257 exit_robust_list(tsk);
1258 tsk->robust_list = NULL;
1259 }
1260#ifdef CONFIG_COMPAT
1261 if (unlikely(tsk->compat_robust_list)) {
1262 compat_exit_robust_list(tsk);
1263 tsk->compat_robust_list = NULL;
1264 }
1265#endif
1266 if (unlikely(!list_empty(&tsk->pi_state_list)))
1267 exit_pi_state_list(tsk);
1268#endif
1269
1270 uprobe_free_utask(tsk);
1271
1272 /* Get rid of any cached register state */
1273 deactivate_mm(tsk, mm);
1274
1275 /*
1276 * Signal userspace if we're not exiting with a core dump
1277 * because we want to leave the value intact for debugging
1278 * purposes.
1279 */
1280 if (tsk->clear_child_tid) {
1281 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) &&
1282 atomic_read(&mm->mm_users) > 1) {
1283 /*
1284 * We don't check the error code - if userspace has
1285 * not set up a proper pointer then tough luck.
1286 */
1287 put_user(0, tsk->clear_child_tid);
1288 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1289 1, NULL, NULL, 0, 0);
1290 }
1291 tsk->clear_child_tid = NULL;
1292 }
1293
1294 /*
1295 * All done, finally we can wake up parent and return this mm to him.
1296 * Also kthread_stop() uses this completion for synchronization.
1297 */
1298 if (tsk->vfork_done)
1299 complete_vfork_done(tsk);
1300}
1301
1302/*
1303 * Allocate a new mm structure and copy contents from the
1304 * mm structure of the passed in task structure.
1305 */
1306static struct mm_struct *dup_mm(struct task_struct *tsk)
1307{
1308 struct mm_struct *mm, *oldmm = current->mm;
1309 int err;
1310
1311 mm = allocate_mm();
1312 if (!mm)
1313 goto fail_nomem;
1314
1315 memcpy(mm, oldmm, sizeof(*mm));
1316
1317 if (!mm_init(mm, tsk, mm->user_ns))
1318 goto fail_nomem;
1319
1320 err = dup_mmap(mm, oldmm);
1321 if (err)
1322 goto free_pt;
1323
1324 mm->hiwater_rss = get_mm_rss(mm);
1325 mm->hiwater_vm = mm->total_vm;
1326
1327 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1328 goto free_pt;
1329
1330 return mm;
1331
1332free_pt:
1333 /* don't put binfmt in mmput, we haven't got module yet */
1334 mm->binfmt = NULL;
1335 mmput(mm);
1336
1337fail_nomem:
1338 return NULL;
1339}
1340
1341static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1342{
1343 struct mm_struct *mm, *oldmm;
1344 int retval;
1345
1346 tsk->min_flt = tsk->maj_flt = 0;
1347 tsk->nvcsw = tsk->nivcsw = 0;
1348#ifdef CONFIG_DETECT_HUNG_TASK
1349 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1350 tsk->last_switch_time = 0;
1351#endif
1352
1353 tsk->mm = NULL;
1354 tsk->active_mm = NULL;
1355
1356 /*
1357 * Are we cloning a kernel thread?
1358 *
1359 * We need to steal a active VM for that..
1360 */
1361 oldmm = current->mm;
1362 if (!oldmm)
1363 return 0;
1364
1365 /* initialize the new vmacache entries */
1366 vmacache_flush(tsk);
1367
1368 if (clone_flags & CLONE_VM) {
1369 mmget(oldmm);
1370 mm = oldmm;
1371 goto good_mm;
1372 }
1373
1374 retval = -ENOMEM;
1375 mm = dup_mm(tsk);
1376 if (!mm)
1377 goto fail_nomem;
1378
1379good_mm:
1380 tsk->mm = mm;
1381 tsk->active_mm = mm;
1382 return 0;
1383
1384fail_nomem:
1385 return retval;
1386}
1387
1388static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1389{
1390 struct fs_struct *fs = current->fs;
1391 if (clone_flags & CLONE_FS) {
1392 /* tsk->fs is already what we want */
1393 spin_lock(&fs->lock);
1394 if (fs->in_exec) {
1395 spin_unlock(&fs->lock);
1396 return -EAGAIN;
1397 }
1398 fs->users++;
1399 spin_unlock(&fs->lock);
1400 return 0;
1401 }
1402 tsk->fs = copy_fs_struct(fs);
1403 if (!tsk->fs)
1404 return -ENOMEM;
1405 return 0;
1406}
1407
1408static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1409{
1410 struct files_struct *oldf, *newf;
1411 int error = 0;
1412
1413 /*
1414 * A background process may not have any files ...
1415 */
1416 oldf = current->files;
1417 if (!oldf)
1418 goto out;
1419
1420 if (clone_flags & CLONE_FILES) {
1421 atomic_inc(&oldf->count);
1422 goto out;
1423 }
1424
1425 newf = dup_fd(oldf, &error);
1426 if (!newf)
1427 goto out;
1428
1429 tsk->files = newf;
1430 error = 0;
1431out:
1432 return error;
1433}
1434
1435static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
1436{
1437#ifdef CONFIG_BLOCK
1438 struct io_context *ioc = current->io_context;
1439 struct io_context *new_ioc;
1440
1441 if (!ioc)
1442 return 0;
1443 /*
1444 * Share io context with parent, if CLONE_IO is set
1445 */
1446 if (clone_flags & CLONE_IO) {
1447 ioc_task_link(ioc);
1448 tsk->io_context = ioc;
1449 } else if (ioprio_valid(ioc->ioprio)) {
1450 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
1451 if (unlikely(!new_ioc))
1452 return -ENOMEM;
1453
1454 new_ioc->ioprio = ioc->ioprio;
1455 put_io_context(new_ioc);
1456 }
1457#endif
1458 return 0;
1459}
1460
1461static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1462{
1463 struct sighand_struct *sig;
1464
1465 if (clone_flags & CLONE_SIGHAND) {
1466 atomic_inc(&current->sighand->count);
1467 return 0;
1468 }
1469 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1470 rcu_assign_pointer(tsk->sighand, sig);
1471 if (!sig)
1472 return -ENOMEM;
1473
1474 atomic_set(&sig->count, 1);
1475 spin_lock_irq(&current->sighand->siglock);
1476 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1477 spin_unlock_irq(&current->sighand->siglock);
1478 return 0;
1479}
1480
1481void __cleanup_sighand(struct sighand_struct *sighand)
1482{
1483 if (atomic_dec_and_test(&sighand->count)) {
1484 signalfd_cleanup(sighand);
1485 /*
1486 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1487 * without an RCU grace period, see __lock_task_sighand().
1488 */
1489 kmem_cache_free(sighand_cachep, sighand);
1490 }
1491}
1492
1493#ifdef CONFIG_POSIX_TIMERS
1494/*
1495 * Initialize POSIX timer handling for a thread group.
1496 */
1497static void posix_cpu_timers_init_group(struct signal_struct *sig)
1498{
1499 unsigned long cpu_limit;
1500
1501 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1502 if (cpu_limit != RLIM_INFINITY) {
1503 sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
1504 sig->cputimer.running = true;
1505 }
1506
1507 /* The timer lists. */
1508 INIT_LIST_HEAD(&sig->cpu_timers[0]);
1509 INIT_LIST_HEAD(&sig->cpu_timers[1]);
1510 INIT_LIST_HEAD(&sig->cpu_timers[2]);
1511}
1512#else
1513static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
1514#endif
1515
1516static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1517{
1518 struct signal_struct *sig;
1519
1520 if (clone_flags & CLONE_THREAD)
1521 return 0;
1522
1523 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1524 tsk->signal = sig;
1525 if (!sig)
1526 return -ENOMEM;
1527
1528 sig->nr_threads = 1;
1529 atomic_set(&sig->live, 1);
1530 atomic_set(&sig->sigcnt, 1);
1531
1532 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1533 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1534 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1535
1536 init_waitqueue_head(&sig->wait_chldexit);
1537 sig->curr_target = tsk;
1538 init_sigpending(&sig->shared_pending);
1539 INIT_HLIST_HEAD(&sig->multiprocess);
1540 seqlock_init(&sig->stats_lock);
1541 prev_cputime_init(&sig->prev_cputime);
1542
1543#ifdef CONFIG_POSIX_TIMERS
1544 INIT_LIST_HEAD(&sig->posix_timers);
1545 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1546 sig->real_timer.function = it_real_fn;
1547#endif
1548
1549 task_lock(current->group_leader);
1550 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1551 task_unlock(current->group_leader);
1552
1553 posix_cpu_timers_init_group(sig);
1554
1555 tty_audit_fork(sig);
1556 sched_autogroup_fork(sig);
1557
1558 sig->oom_score_adj = current->signal->oom_score_adj;
1559 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1560
1561 mutex_init(&sig->cred_guard_mutex);
1562
1563 return 0;
1564}
1565
1566static void copy_seccomp(struct task_struct *p)
1567{
1568#ifdef CONFIG_SECCOMP
1569 /*
1570 * Must be called with sighand->lock held, which is common to
1571 * all threads in the group. Holding cred_guard_mutex is not
1572 * needed because this new task is not yet running and cannot
1573 * be racing exec.
1574 */
1575 assert_spin_locked(&current->sighand->siglock);
1576
1577 /* Ref-count the new filter user, and assign it. */
1578 get_seccomp_filter(current);
1579 p->seccomp = current->seccomp;
1580
1581 /*
1582 * Explicitly enable no_new_privs here in case it got set
1583 * between the task_struct being duplicated and holding the
1584 * sighand lock. The seccomp state and nnp must be in sync.
1585 */
1586 if (task_no_new_privs(current))
1587 task_set_no_new_privs(p);
1588
1589 /*
1590 * If the parent gained a seccomp mode after copying thread
1591 * flags and between before we held the sighand lock, we have
1592 * to manually enable the seccomp thread flag here.
1593 */
1594 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1595 set_tsk_thread_flag(p, TIF_SECCOMP);
1596#endif
1597}
1598
1599SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1600{
1601 current->clear_child_tid = tidptr;
1602
1603 return task_pid_vnr(current);
1604}
1605
1606static void rt_mutex_init_task(struct task_struct *p)
1607{
1608 raw_spin_lock_init(&p->pi_lock);
1609#ifdef CONFIG_RT_MUTEXES
1610 p->pi_waiters = RB_ROOT_CACHED;
1611 p->pi_top_task = NULL;
1612 p->pi_blocked_on = NULL;
1613#endif
1614}
1615
1616#ifdef CONFIG_POSIX_TIMERS
1617/*
1618 * Initialize POSIX timer handling for a single task.
1619 */
1620static void posix_cpu_timers_init(struct task_struct *tsk)
1621{
1622 tsk->cputime_expires.prof_exp = 0;
1623 tsk->cputime_expires.virt_exp = 0;
1624 tsk->cputime_expires.sched_exp = 0;
1625 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1626 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1627 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1628}
1629#else
1630static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
1631#endif
1632
1633static inline void init_task_pid_links(struct task_struct *task)
1634{
1635 enum pid_type type;
1636
1637 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1638 INIT_HLIST_NODE(&task->pid_links[type]);
1639 }
1640}
1641
1642static inline void
1643init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1644{
1645 if (type == PIDTYPE_PID)
1646 task->thread_pid = pid;
1647 else
1648 task->signal->pids[type] = pid;
1649}
1650
1651static inline void rcu_copy_process(struct task_struct *p)
1652{
1653#ifdef CONFIG_PREEMPT_RCU
1654 p->rcu_read_lock_nesting = 0;
1655 p->rcu_read_unlock_special.s = 0;
1656 p->rcu_blocked_node = NULL;
1657 INIT_LIST_HEAD(&p->rcu_node_entry);
1658#endif /* #ifdef CONFIG_PREEMPT_RCU */
1659#ifdef CONFIG_TASKS_RCU
1660 p->rcu_tasks_holdout = false;
1661 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1662 p->rcu_tasks_idle_cpu = -1;
1663#endif /* #ifdef CONFIG_TASKS_RCU */
1664}
1665
1666/*
1667 * This creates a new process as a copy of the old one,
1668 * but does not actually start it yet.
1669 *
1670 * It copies the registers, and all the appropriate
1671 * parts of the process environment (as per the clone
1672 * flags). The actual kick-off is left to the caller.
1673 */
1674static __latent_entropy struct task_struct *copy_process(
1675 unsigned long clone_flags,
1676 unsigned long stack_start,
1677 unsigned long stack_size,
1678 int __user *child_tidptr,
1679 struct pid *pid,
1680 int trace,
1681 unsigned long tls,
1682 int node)
1683{
1684 int retval;
1685 struct task_struct *p;
1686 struct multiprocess_signals delayed;
1687
1688 /*
1689 * Don't allow sharing the root directory with processes in a different
1690 * namespace
1691 */
1692 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1693 return ERR_PTR(-EINVAL);
1694
1695 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1696 return ERR_PTR(-EINVAL);
1697
1698 /*
1699 * Thread groups must share signals as well, and detached threads
1700 * can only be started up within the thread group.
1701 */
1702 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1703 return ERR_PTR(-EINVAL);
1704
1705 /*
1706 * Shared signal handlers imply shared VM. By way of the above,
1707 * thread groups also imply shared VM. Blocking this case allows
1708 * for various simplifications in other code.
1709 */
1710 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1711 return ERR_PTR(-EINVAL);
1712
1713 /*
1714 * Siblings of global init remain as zombies on exit since they are
1715 * not reaped by their parent (swapper). To solve this and to avoid
1716 * multi-rooted process trees, prevent global and container-inits
1717 * from creating siblings.
1718 */
1719 if ((clone_flags & CLONE_PARENT) &&
1720 current->signal->flags & SIGNAL_UNKILLABLE)
1721 return ERR_PTR(-EINVAL);
1722
1723 /*
1724 * If the new process will be in a different pid or user namespace
1725 * do not allow it to share a thread group with the forking task.
1726 */
1727 if (clone_flags & CLONE_THREAD) {
1728 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
1729 (task_active_pid_ns(current) !=
1730 current->nsproxy->pid_ns_for_children))
1731 return ERR_PTR(-EINVAL);
1732 }
1733
1734 /*
1735 * Force any signals received before this point to be delivered
1736 * before the fork happens. Collect up signals sent to multiple
1737 * processes that happen during the fork and delay them so that
1738 * they appear to happen after the fork.
1739 */
1740 sigemptyset(&delayed.signal);
1741 INIT_HLIST_NODE(&delayed.node);
1742
1743 spin_lock_irq(&current->sighand->siglock);
1744 if (!(clone_flags & CLONE_THREAD))
1745 hlist_add_head(&delayed.node, &current->signal->multiprocess);
1746 recalc_sigpending();
1747 spin_unlock_irq(&current->sighand->siglock);
1748 retval = -ERESTARTNOINTR;
1749 if (signal_pending(current))
1750 goto fork_out;
1751
1752 retval = -ENOMEM;
1753 p = dup_task_struct(current, node);
1754 if (!p)
1755 goto fork_out;
1756
1757 /*
1758 * This _must_ happen before we call free_task(), i.e. before we jump
1759 * to any of the bad_fork_* labels. This is to avoid freeing
1760 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1761 * kernel threads (PF_KTHREAD).
1762 */
1763 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1764 /*
1765 * Clear TID on mm_release()?
1766 */
1767 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1768
1769 ftrace_graph_init_task(p);
1770
1771 rt_mutex_init_task(p);
1772
1773#ifdef CONFIG_PROVE_LOCKING
1774 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1775 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1776#endif
1777 retval = -EAGAIN;
1778 if (atomic_read(&p->real_cred->user->processes) >=
1779 task_rlimit(p, RLIMIT_NPROC)) {
1780 if (p->real_cred->user != INIT_USER &&
1781 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
1782 goto bad_fork_free;
1783 }
1784 current->flags &= ~PF_NPROC_EXCEEDED;
1785
1786 retval = copy_creds(p, clone_flags);
1787 if (retval < 0)
1788 goto bad_fork_free;
1789
1790 /*
1791 * If multiple threads are within copy_process(), then this check
1792 * triggers too late. This doesn't hurt, the check is only there
1793 * to stop root fork bombs.
1794 */
1795 retval = -EAGAIN;
1796 if (nr_threads >= max_threads)
1797 goto bad_fork_cleanup_count;
1798
1799 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1800 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE);
1801 p->flags |= PF_FORKNOEXEC;
1802 INIT_LIST_HEAD(&p->children);
1803 INIT_LIST_HEAD(&p->sibling);
1804 rcu_copy_process(p);
1805 p->vfork_done = NULL;
1806 spin_lock_init(&p->alloc_lock);
1807
1808 init_sigpending(&p->pending);
1809
1810 p->utime = p->stime = p->gtime = 0;
1811#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1812 p->utimescaled = p->stimescaled = 0;
1813#endif
1814 prev_cputime_init(&p->prev_cputime);
1815
1816#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1817 seqcount_init(&p->vtime.seqcount);
1818 p->vtime.starttime = 0;
1819 p->vtime.state = VTIME_INACTIVE;
1820#endif
1821
1822#if defined(SPLIT_RSS_COUNTING)
1823 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1824#endif
1825
1826 p->default_timer_slack_ns = current->timer_slack_ns;
1827
1828#ifdef CONFIG_PSI
1829 p->psi_flags = 0;
1830#endif
1831
1832 task_io_accounting_init(&p->ioac);
1833 acct_clear_integrals(p);
1834
1835 posix_cpu_timers_init(p);
1836
1837 p->io_context = NULL;
1838 audit_set_context(p, NULL);
1839 cgroup_fork(p);
1840#ifdef CONFIG_NUMA
1841 p->mempolicy = mpol_dup(p->mempolicy);
1842 if (IS_ERR(p->mempolicy)) {
1843 retval = PTR_ERR(p->mempolicy);
1844 p->mempolicy = NULL;
1845 goto bad_fork_cleanup_threadgroup_lock;
1846 }
1847#endif
1848#ifdef CONFIG_CPUSETS
1849 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1850 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1851 seqcount_init(&p->mems_allowed_seq);
1852#endif
1853#ifdef CONFIG_TRACE_IRQFLAGS
1854 p->irq_events = 0;
1855 p->hardirqs_enabled = 0;
1856 p->hardirq_enable_ip = 0;
1857 p->hardirq_enable_event = 0;
1858 p->hardirq_disable_ip = _THIS_IP_;
1859 p->hardirq_disable_event = 0;
1860 p->softirqs_enabled = 1;
1861 p->softirq_enable_ip = _THIS_IP_;
1862 p->softirq_enable_event = 0;
1863 p->softirq_disable_ip = 0;
1864 p->softirq_disable_event = 0;
1865 p->hardirq_context = 0;
1866 p->softirq_context = 0;
1867#endif
1868
1869 p->pagefault_disabled = 0;
1870
1871#ifdef CONFIG_LOCKDEP
1872 p->lockdep_depth = 0; /* no locks held yet */
1873 p->curr_chain_key = 0;
1874 p->lockdep_recursion = 0;
1875 lockdep_init_task(p);
1876#endif
1877
1878#ifdef CONFIG_DEBUG_MUTEXES
1879 p->blocked_on = NULL; /* not blocked yet */
1880#endif
1881#ifdef CONFIG_BCACHE
1882 p->sequential_io = 0;
1883 p->sequential_io_avg = 0;
1884#endif
1885
1886 /* Perform scheduler related setup. Assign this task to a CPU. */
1887 retval = sched_fork(clone_flags, p);
1888 if (retval)
1889 goto bad_fork_cleanup_policy;
1890
1891 retval = perf_event_init_task(p);
1892 if (retval)
1893 goto bad_fork_cleanup_policy;
1894 retval = audit_alloc(p);
1895 if (retval)
1896 goto bad_fork_cleanup_perf;
1897 /* copy all the process information */
1898 shm_init_task(p);
1899 retval = security_task_alloc(p, clone_flags);
1900 if (retval)
1901 goto bad_fork_cleanup_audit;
1902 retval = copy_semundo(clone_flags, p);
1903 if (retval)
1904 goto bad_fork_cleanup_security;
1905 retval = copy_files(clone_flags, p);
1906 if (retval)
1907 goto bad_fork_cleanup_semundo;
1908 retval = copy_fs(clone_flags, p);
1909 if (retval)
1910 goto bad_fork_cleanup_files;
1911 retval = copy_sighand(clone_flags, p);
1912 if (retval)
1913 goto bad_fork_cleanup_fs;
1914 retval = copy_signal(clone_flags, p);
1915 if (retval)
1916 goto bad_fork_cleanup_sighand;
1917 retval = copy_mm(clone_flags, p);
1918 if (retval)
1919 goto bad_fork_cleanup_signal;
1920 retval = copy_namespaces(clone_flags, p);
1921 if (retval)
1922 goto bad_fork_cleanup_mm;
1923 retval = copy_io(clone_flags, p);
1924 if (retval)
1925 goto bad_fork_cleanup_namespaces;
1926 retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls);
1927 if (retval)
1928 goto bad_fork_cleanup_io;
1929
1930 stackleak_task_init(p);
1931
1932 if (pid != &init_struct_pid) {
1933 pid = alloc_pid(p->nsproxy->pid_ns_for_children);
1934 if (IS_ERR(pid)) {
1935 retval = PTR_ERR(pid);
1936 goto bad_fork_cleanup_thread;
1937 }
1938 }
1939
1940#ifdef CONFIG_BLOCK
1941 p->plug = NULL;
1942#endif
1943#ifdef CONFIG_FUTEX
1944 p->robust_list = NULL;
1945#ifdef CONFIG_COMPAT
1946 p->compat_robust_list = NULL;
1947#endif
1948 INIT_LIST_HEAD(&p->pi_state_list);
1949 p->pi_state_cache = NULL;
1950#endif
1951 /*
1952 * sigaltstack should be cleared when sharing the same VM
1953 */
1954 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1955 sas_ss_reset(p);
1956
1957 /*
1958 * Syscall tracing and stepping should be turned off in the
1959 * child regardless of CLONE_PTRACE.
1960 */
1961 user_disable_single_step(p);
1962 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1963#ifdef TIF_SYSCALL_EMU
1964 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1965#endif
1966 clear_all_latency_tracing(p);
1967
1968 /* ok, now we should be set up.. */
1969 p->pid = pid_nr(pid);
1970 if (clone_flags & CLONE_THREAD) {
1971 p->exit_signal = -1;
1972 p->group_leader = current->group_leader;
1973 p->tgid = current->tgid;
1974 } else {
1975 if (clone_flags & CLONE_PARENT)
1976 p->exit_signal = current->group_leader->exit_signal;
1977 else
1978 p->exit_signal = (clone_flags & CSIGNAL);
1979 p->group_leader = p;
1980 p->tgid = p->pid;
1981 }
1982
1983 p->nr_dirtied = 0;
1984 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1985 p->dirty_paused_when = 0;
1986
1987 p->pdeath_signal = 0;
1988 INIT_LIST_HEAD(&p->thread_group);
1989 p->task_works = NULL;
1990
1991 cgroup_threadgroup_change_begin(current);
1992 /*
1993 * Ensure that the cgroup subsystem policies allow the new process to be
1994 * forked. It should be noted the the new process's css_set can be changed
1995 * between here and cgroup_post_fork() if an organisation operation is in
1996 * progress.
1997 */
1998 retval = cgroup_can_fork(p);
1999 if (retval)
2000 goto bad_fork_free_pid;
2001
2002 /*
2003 * From this point on we must avoid any synchronous user-space
2004 * communication until we take the tasklist-lock. In particular, we do
2005 * not want user-space to be able to predict the process start-time by
2006 * stalling fork(2) after we recorded the start_time but before it is
2007 * visible to the system.
2008 */
2009
2010 p->start_time = ktime_get_ns();
2011 p->real_start_time = ktime_get_boot_ns();
2012
2013 /*
2014 * Make it visible to the rest of the system, but dont wake it up yet.
2015 * Need tasklist lock for parent etc handling!
2016 */
2017 write_lock_irq(&tasklist_lock);
2018
2019 /* CLONE_PARENT re-uses the old parent */
2020 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2021 p->real_parent = current->real_parent;
2022 p->parent_exec_id = current->parent_exec_id;
2023 } else {
2024 p->real_parent = current;
2025 p->parent_exec_id = current->self_exec_id;
2026 }
2027
2028 klp_copy_process(p);
2029
2030 spin_lock(&current->sighand->siglock);
2031
2032 /*
2033 * Copy seccomp details explicitly here, in case they were changed
2034 * before holding sighand lock.
2035 */
2036 copy_seccomp(p);
2037
2038 rseq_fork(p, clone_flags);
2039
2040 /* Don't start children in a dying pid namespace */
2041 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2042 retval = -ENOMEM;
2043 goto bad_fork_cancel_cgroup;
2044 }
2045
2046 /* Let kill terminate clone/fork in the middle */
2047 if (fatal_signal_pending(current)) {
2048 retval = -EINTR;
2049 goto bad_fork_cancel_cgroup;
2050 }
2051
2052
2053 init_task_pid_links(p);
2054 if (likely(p->pid)) {
2055 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2056
2057 init_task_pid(p, PIDTYPE_PID, pid);
2058 if (thread_group_leader(p)) {
2059 init_task_pid(p, PIDTYPE_TGID, pid);
2060 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2061 init_task_pid(p, PIDTYPE_SID, task_session(current));
2062
2063 if (is_child_reaper(pid)) {
2064 ns_of_pid(pid)->child_reaper = p;
2065 p->signal->flags |= SIGNAL_UNKILLABLE;
2066 }
2067 p->signal->shared_pending.signal = delayed.signal;
2068 p->signal->tty = tty_kref_get(current->signal->tty);
2069 /*
2070 * Inherit has_child_subreaper flag under the same
2071 * tasklist_lock with adding child to the process tree
2072 * for propagate_has_child_subreaper optimization.
2073 */
2074 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2075 p->real_parent->signal->is_child_subreaper;
2076 list_add_tail(&p->sibling, &p->real_parent->children);
2077 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2078 attach_pid(p, PIDTYPE_TGID);
2079 attach_pid(p, PIDTYPE_PGID);
2080 attach_pid(p, PIDTYPE_SID);
2081 __this_cpu_inc(process_counts);
2082 } else {
2083 current->signal->nr_threads++;
2084 atomic_inc(&current->signal->live);
2085 atomic_inc(&current->signal->sigcnt);
2086 task_join_group_stop(p);
2087 list_add_tail_rcu(&p->thread_group,
2088 &p->group_leader->thread_group);
2089 list_add_tail_rcu(&p->thread_node,
2090 &p->signal->thread_head);
2091 }
2092 attach_pid(p, PIDTYPE_PID);
2093 nr_threads++;
2094 }
2095 total_forks++;
2096 hlist_del_init(&delayed.node);
2097 spin_unlock(&current->sighand->siglock);
2098 syscall_tracepoint_update(p);
2099 write_unlock_irq(&tasklist_lock);
2100
2101 proc_fork_connector(p);
2102 cgroup_post_fork(p);
2103 cgroup_threadgroup_change_end(current);
2104 perf_event_fork(p);
2105
2106 trace_task_newtask(p, clone_flags);
2107 uprobe_copy_process(p, clone_flags);
2108
2109 return p;
2110
2111bad_fork_cancel_cgroup:
2112 spin_unlock(&current->sighand->siglock);
2113 write_unlock_irq(&tasklist_lock);
2114 cgroup_cancel_fork(p);
2115bad_fork_free_pid:
2116 cgroup_threadgroup_change_end(current);
2117 if (pid != &init_struct_pid)
2118 free_pid(pid);
2119bad_fork_cleanup_thread:
2120 exit_thread(p);
2121bad_fork_cleanup_io:
2122 if (p->io_context)
2123 exit_io_context(p);
2124bad_fork_cleanup_namespaces:
2125 exit_task_namespaces(p);
2126bad_fork_cleanup_mm:
2127 if (p->mm)
2128 mmput(p->mm);
2129bad_fork_cleanup_signal:
2130 if (!(clone_flags & CLONE_THREAD))
2131 free_signal_struct(p->signal);
2132bad_fork_cleanup_sighand:
2133 __cleanup_sighand(p->sighand);
2134bad_fork_cleanup_fs:
2135 exit_fs(p); /* blocking */
2136bad_fork_cleanup_files:
2137 exit_files(p); /* blocking */
2138bad_fork_cleanup_semundo:
2139 exit_sem(p);
2140bad_fork_cleanup_security:
2141 security_task_free(p);
2142bad_fork_cleanup_audit:
2143 audit_free(p);
2144bad_fork_cleanup_perf:
2145 perf_event_free_task(p);
2146bad_fork_cleanup_policy:
2147 lockdep_free_task(p);
2148#ifdef CONFIG_NUMA
2149 mpol_put(p->mempolicy);
2150bad_fork_cleanup_threadgroup_lock:
2151#endif
2152 delayacct_tsk_free(p);
2153bad_fork_cleanup_count:
2154 atomic_dec(&p->cred->user->processes);
2155 exit_creds(p);
2156bad_fork_free:
2157 p->state = TASK_DEAD;
2158 put_task_stack(p);
2159 free_task(p);
2160fork_out:
2161 spin_lock_irq(&current->sighand->siglock);
2162 hlist_del_init(&delayed.node);
2163 spin_unlock_irq(&current->sighand->siglock);
2164 return ERR_PTR(retval);
2165}
2166
2167static inline void init_idle_pids(struct task_struct *idle)
2168{
2169 enum pid_type type;
2170
2171 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2172 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2173 init_task_pid(idle, type, &init_struct_pid);
2174 }
2175}
2176
2177struct task_struct *fork_idle(int cpu)
2178{
2179 struct task_struct *task;
2180 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0,
2181 cpu_to_node(cpu));
2182 if (!IS_ERR(task)) {
2183 init_idle_pids(task);
2184 init_idle(task, cpu);
2185 }
2186
2187 return task;
2188}
2189
2190/*
2191 * Ok, this is the main fork-routine.
2192 *
2193 * It copies the process, and if successful kick-starts
2194 * it and waits for it to finish using the VM if required.
2195 */
2196long _do_fork(unsigned long clone_flags,
2197 unsigned long stack_start,
2198 unsigned long stack_size,
2199 int __user *parent_tidptr,
2200 int __user *child_tidptr,
2201 unsigned long tls)
2202{
2203 struct completion vfork;
2204 struct pid *pid;
2205 struct task_struct *p;
2206 int trace = 0;
2207 long nr;
2208
2209 /*
2210 * Determine whether and which event to report to ptracer. When
2211 * called from kernel_thread or CLONE_UNTRACED is explicitly
2212 * requested, no event is reported; otherwise, report if the event
2213 * for the type of forking is enabled.
2214 */
2215 if (!(clone_flags & CLONE_UNTRACED)) {
2216 if (clone_flags & CLONE_VFORK)
2217 trace = PTRACE_EVENT_VFORK;
2218 else if ((clone_flags & CSIGNAL) != SIGCHLD)
2219 trace = PTRACE_EVENT_CLONE;
2220 else
2221 trace = PTRACE_EVENT_FORK;
2222
2223 if (likely(!ptrace_event_enabled(current, trace)))
2224 trace = 0;
2225 }
2226
2227 p = copy_process(clone_flags, stack_start, stack_size,
2228 child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
2229 add_latent_entropy();
2230
2231 if (IS_ERR(p))
2232 return PTR_ERR(p);
2233
2234 /*
2235 * Do this prior waking up the new thread - the thread pointer
2236 * might get invalid after that point, if the thread exits quickly.
2237 */
2238 trace_sched_process_fork(current, p);
2239
2240 pid = get_task_pid(p, PIDTYPE_PID);
2241 nr = pid_vnr(pid);
2242
2243 if (clone_flags & CLONE_PARENT_SETTID)
2244 put_user(nr, parent_tidptr);
2245
2246 if (clone_flags & CLONE_VFORK) {
2247 p->vfork_done = &vfork;
2248 init_completion(&vfork);
2249 get_task_struct(p);
2250 }
2251
2252 wake_up_new_task(p);
2253
2254 /* forking complete and child started to run, tell ptracer */
2255 if (unlikely(trace))
2256 ptrace_event_pid(trace, pid);
2257
2258 if (clone_flags & CLONE_VFORK) {
2259 if (!wait_for_vfork_done(p, &vfork))
2260 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2261 }
2262
2263 put_pid(pid);
2264 return nr;
2265}
2266
2267#ifndef CONFIG_HAVE_COPY_THREAD_TLS
2268/* For compatibility with architectures that call do_fork directly rather than
2269 * using the syscall entry points below. */
2270long do_fork(unsigned long clone_flags,
2271 unsigned long stack_start,
2272 unsigned long stack_size,
2273 int __user *parent_tidptr,
2274 int __user *child_tidptr)
2275{
2276 return _do_fork(clone_flags, stack_start, stack_size,
2277 parent_tidptr, child_tidptr, 0);
2278}
2279#endif
2280
2281/*
2282 * Create a kernel thread.
2283 */
2284pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2285{
2286 return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
2287 (unsigned long)arg, NULL, NULL, 0);
2288}
2289
2290#ifdef __ARCH_WANT_SYS_FORK
2291SYSCALL_DEFINE0(fork)
2292{
2293#ifdef CONFIG_MMU
2294 return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0);
2295#else
2296 /* can not support in nommu mode */
2297 return -EINVAL;
2298#endif
2299}
2300#endif
2301
2302#ifdef __ARCH_WANT_SYS_VFORK
2303SYSCALL_DEFINE0(vfork)
2304{
2305 return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
2306 0, NULL, NULL, 0);
2307}
2308#endif
2309
2310#ifdef __ARCH_WANT_SYS_CLONE
2311#ifdef CONFIG_CLONE_BACKWARDS
2312SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2313 int __user *, parent_tidptr,
2314 unsigned long, tls,
2315 int __user *, child_tidptr)
2316#elif defined(CONFIG_CLONE_BACKWARDS2)
2317SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2318 int __user *, parent_tidptr,
2319 int __user *, child_tidptr,
2320 unsigned long, tls)
2321#elif defined(CONFIG_CLONE_BACKWARDS3)
2322SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2323 int, stack_size,
2324 int __user *, parent_tidptr,
2325 int __user *, child_tidptr,
2326 unsigned long, tls)
2327#else
2328SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2329 int __user *, parent_tidptr,
2330 int __user *, child_tidptr,
2331 unsigned long, tls)
2332#endif
2333{
2334 return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
2335}
2336#endif
2337
2338void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2339{
2340 struct task_struct *leader, *parent, *child;
2341 int res;
2342
2343 read_lock(&tasklist_lock);
2344 leader = top = top->group_leader;
2345down:
2346 for_each_thread(leader, parent) {
2347 list_for_each_entry(child, &parent->children, sibling) {
2348 res = visitor(child, data);
2349 if (res) {
2350 if (res < 0)
2351 goto out;
2352 leader = child;
2353 goto down;
2354 }
2355up:
2356 ;
2357 }
2358 }
2359
2360 if (leader != top) {
2361 child = leader;
2362 parent = child->real_parent;
2363 leader = parent->group_leader;
2364 goto up;
2365 }
2366out:
2367 read_unlock(&tasklist_lock);
2368}
2369
2370#ifndef ARCH_MIN_MMSTRUCT_ALIGN
2371#define ARCH_MIN_MMSTRUCT_ALIGN 0
2372#endif
2373
2374static void sighand_ctor(void *data)
2375{
2376 struct sighand_struct *sighand = data;
2377
2378 spin_lock_init(&sighand->siglock);
2379 init_waitqueue_head(&sighand->signalfd_wqh);
2380}
2381
2382void __init proc_caches_init(void)
2383{
2384 unsigned int mm_size;
2385
2386 sighand_cachep = kmem_cache_create("sighand_cache",
2387 sizeof(struct sighand_struct), 0,
2388 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2389 SLAB_ACCOUNT, sighand_ctor);
2390 signal_cachep = kmem_cache_create("signal_cache",
2391 sizeof(struct signal_struct), 0,
2392 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2393 NULL);
2394 files_cachep = kmem_cache_create("files_cache",
2395 sizeof(struct files_struct), 0,
2396 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2397 NULL);
2398 fs_cachep = kmem_cache_create("fs_cache",
2399 sizeof(struct fs_struct), 0,
2400 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2401 NULL);
2402
2403 /*
2404 * The mm_cpumask is located at the end of mm_struct, and is
2405 * dynamically sized based on the maximum CPU number this system
2406 * can have, taking hotplug into account (nr_cpu_ids).
2407 */
2408 mm_size = sizeof(struct mm_struct) + cpumask_size();
2409
2410 mm_cachep = kmem_cache_create_usercopy("mm_struct",
2411 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
2412 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2413 offsetof(struct mm_struct, saved_auxv),
2414 sizeof_field(struct mm_struct, saved_auxv),
2415 NULL);
2416 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
2417 mmap_init();
2418 nsproxy_cache_init();
2419}
2420
2421/*
2422 * Check constraints on flags passed to the unshare system call.
2423 */
2424static int check_unshare_flags(unsigned long unshare_flags)
2425{
2426 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
2427 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
2428 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
2429 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP))
2430 return -EINVAL;
2431 /*
2432 * Not implemented, but pretend it works if there is nothing
2433 * to unshare. Note that unsharing the address space or the
2434 * signal handlers also need to unshare the signal queues (aka
2435 * CLONE_THREAD).
2436 */
2437 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
2438 if (!thread_group_empty(current))
2439 return -EINVAL;
2440 }
2441 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
2442 if (atomic_read(&current->sighand->count) > 1)
2443 return -EINVAL;
2444 }
2445 if (unshare_flags & CLONE_VM) {
2446 if (!current_is_single_threaded())
2447 return -EINVAL;
2448 }
2449
2450 return 0;
2451}
2452
2453/*
2454 * Unshare the filesystem structure if it is being shared
2455 */
2456static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
2457{
2458 struct fs_struct *fs = current->fs;
2459
2460 if (!(unshare_flags & CLONE_FS) || !fs)
2461 return 0;
2462
2463 /* don't need lock here; in the worst case we'll do useless copy */
2464 if (fs->users == 1)
2465 return 0;
2466
2467 *new_fsp = copy_fs_struct(fs);
2468 if (!*new_fsp)
2469 return -ENOMEM;
2470
2471 return 0;
2472}
2473
2474/*
2475 * Unshare file descriptor table if it is being shared
2476 */
2477static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
2478{
2479 struct files_struct *fd = current->files;
2480 int error = 0;
2481
2482 if ((unshare_flags & CLONE_FILES) &&
2483 (fd && atomic_read(&fd->count) > 1)) {
2484 *new_fdp = dup_fd(fd, &error);
2485 if (!*new_fdp)
2486 return error;
2487 }
2488
2489 return 0;
2490}
2491
2492/*
2493 * unshare allows a process to 'unshare' part of the process
2494 * context which was originally shared using clone. copy_*
2495 * functions used by do_fork() cannot be used here directly
2496 * because they modify an inactive task_struct that is being
2497 * constructed. Here we are modifying the current, active,
2498 * task_struct.
2499 */
2500int ksys_unshare(unsigned long unshare_flags)
2501{
2502 struct fs_struct *fs, *new_fs = NULL;
2503 struct files_struct *fd, *new_fd = NULL;
2504 struct cred *new_cred = NULL;
2505 struct nsproxy *new_nsproxy = NULL;
2506 int do_sysvsem = 0;
2507 int err;
2508
2509 /*
2510 * If unsharing a user namespace must also unshare the thread group
2511 * and unshare the filesystem root and working directories.
2512 */
2513 if (unshare_flags & CLONE_NEWUSER)
2514 unshare_flags |= CLONE_THREAD | CLONE_FS;
2515 /*
2516 * If unsharing vm, must also unshare signal handlers.
2517 */
2518 if (unshare_flags & CLONE_VM)
2519 unshare_flags |= CLONE_SIGHAND;
2520 /*
2521 * If unsharing a signal handlers, must also unshare the signal queues.
2522 */
2523 if (unshare_flags & CLONE_SIGHAND)
2524 unshare_flags |= CLONE_THREAD;
2525 /*
2526 * If unsharing namespace, must also unshare filesystem information.
2527 */
2528 if (unshare_flags & CLONE_NEWNS)
2529 unshare_flags |= CLONE_FS;
2530
2531 err = check_unshare_flags(unshare_flags);
2532 if (err)
2533 goto bad_unshare_out;
2534 /*
2535 * CLONE_NEWIPC must also detach from the undolist: after switching
2536 * to a new ipc namespace, the semaphore arrays from the old
2537 * namespace are unreachable.
2538 */
2539 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
2540 do_sysvsem = 1;
2541 err = unshare_fs(unshare_flags, &new_fs);
2542 if (err)
2543 goto bad_unshare_out;
2544 err = unshare_fd(unshare_flags, &new_fd);
2545 if (err)
2546 goto bad_unshare_cleanup_fs;
2547 err = unshare_userns(unshare_flags, &new_cred);
2548 if (err)
2549 goto bad_unshare_cleanup_fd;
2550 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
2551 new_cred, new_fs);
2552 if (err)
2553 goto bad_unshare_cleanup_cred;
2554
2555 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
2556 if (do_sysvsem) {
2557 /*
2558 * CLONE_SYSVSEM is equivalent to sys_exit().
2559 */
2560 exit_sem(current);
2561 }
2562 if (unshare_flags & CLONE_NEWIPC) {
2563 /* Orphan segments in old ns (see sem above). */
2564 exit_shm(current);
2565 shm_init_task(current);
2566 }
2567
2568 if (new_nsproxy)
2569 switch_task_namespaces(current, new_nsproxy);
2570
2571 task_lock(current);
2572
2573 if (new_fs) {
2574 fs = current->fs;
2575 spin_lock(&fs->lock);
2576 current->fs = new_fs;
2577 if (--fs->users)
2578 new_fs = NULL;
2579 else
2580 new_fs = fs;
2581 spin_unlock(&fs->lock);
2582 }
2583
2584 if (new_fd) {
2585 fd = current->files;
2586 current->files = new_fd;
2587 new_fd = fd;
2588 }
2589
2590 task_unlock(current);
2591
2592 if (new_cred) {
2593 /* Install the new user namespace */
2594 commit_creds(new_cred);
2595 new_cred = NULL;
2596 }
2597 }
2598
2599 perf_event_namespaces(current);
2600
2601bad_unshare_cleanup_cred:
2602 if (new_cred)
2603 put_cred(new_cred);
2604bad_unshare_cleanup_fd:
2605 if (new_fd)
2606 put_files_struct(new_fd);
2607
2608bad_unshare_cleanup_fs:
2609 if (new_fs)
2610 free_fs_struct(new_fs);
2611
2612bad_unshare_out:
2613 return err;
2614}
2615
2616SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
2617{
2618 return ksys_unshare(unshare_flags);
2619}
2620
2621/*
2622 * Helper to unshare the files of the current task.
2623 * We don't want to expose copy_files internals to
2624 * the exec layer of the kernel.
2625 */
2626
2627int unshare_files(struct files_struct **displaced)
2628{
2629 struct task_struct *task = current;
2630 struct files_struct *copy = NULL;
2631 int error;
2632
2633 error = unshare_fd(CLONE_FILES, &copy);
2634 if (error || !copy) {
2635 *displaced = NULL;
2636 return error;
2637 }
2638 *displaced = task->files;
2639 task_lock(task);
2640 task->files = copy;
2641 task_unlock(task);
2642 return 0;
2643}
2644
2645int sysctl_max_threads(struct ctl_table *table, int write,
2646 void __user *buffer, size_t *lenp, loff_t *ppos)
2647{
2648 struct ctl_table t;
2649 int ret;
2650 int threads = max_threads;
2651 int min = MIN_THREADS;
2652 int max = MAX_THREADS;
2653
2654 t = *table;
2655 t.data = &threads;
2656 t.extra1 = &min;
2657 t.extra2 = &max;
2658
2659 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2660 if (ret || !write)
2661 return ret;
2662
2663 set_max_threads(threads);
2664
2665 return 0;
2666}