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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/fork.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8/*
9 * 'fork.c' contains the help-routines for the 'fork' system call
10 * (see also entry.S and others).
11 * Fork is rather simple, once you get the hang of it, but the memory
12 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
13 */
14
15#include <linux/anon_inodes.h>
16#include <linux/slab.h>
17#include <linux/sched/autogroup.h>
18#include <linux/sched/mm.h>
19#include <linux/sched/coredump.h>
20#include <linux/sched/user.h>
21#include <linux/sched/numa_balancing.h>
22#include <linux/sched/stat.h>
23#include <linux/sched/task.h>
24#include <linux/sched/task_stack.h>
25#include <linux/sched/cputime.h>
26#include <linux/seq_file.h>
27#include <linux/rtmutex.h>
28#include <linux/init.h>
29#include <linux/unistd.h>
30#include <linux/module.h>
31#include <linux/vmalloc.h>
32#include <linux/completion.h>
33#include <linux/personality.h>
34#include <linux/mempolicy.h>
35#include <linux/sem.h>
36#include <linux/file.h>
37#include <linux/fdtable.h>
38#include <linux/iocontext.h>
39#include <linux/key.h>
40#include <linux/kmsan.h>
41#include <linux/binfmts.h>
42#include <linux/mman.h>
43#include <linux/mmu_notifier.h>
44#include <linux/fs.h>
45#include <linux/mm.h>
46#include <linux/mm_inline.h>
47#include <linux/nsproxy.h>
48#include <linux/capability.h>
49#include <linux/cpu.h>
50#include <linux/cgroup.h>
51#include <linux/security.h>
52#include <linux/hugetlb.h>
53#include <linux/seccomp.h>
54#include <linux/swap.h>
55#include <linux/syscalls.h>
56#include <linux/jiffies.h>
57#include <linux/futex.h>
58#include <linux/compat.h>
59#include <linux/kthread.h>
60#include <linux/task_io_accounting_ops.h>
61#include <linux/rcupdate.h>
62#include <linux/ptrace.h>
63#include <linux/mount.h>
64#include <linux/audit.h>
65#include <linux/memcontrol.h>
66#include <linux/ftrace.h>
67#include <linux/proc_fs.h>
68#include <linux/profile.h>
69#include <linux/rmap.h>
70#include <linux/ksm.h>
71#include <linux/acct.h>
72#include <linux/userfaultfd_k.h>
73#include <linux/tsacct_kern.h>
74#include <linux/cn_proc.h>
75#include <linux/freezer.h>
76#include <linux/delayacct.h>
77#include <linux/taskstats_kern.h>
78#include <linux/tty.h>
79#include <linux/fs_struct.h>
80#include <linux/magic.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#include <linux/kasan.h>
96#include <linux/scs.h>
97#include <linux/io_uring.h>
98#include <linux/bpf.h>
99#include <linux/stackprotector.h>
100
101#include <asm/pgalloc.h>
102#include <linux/uaccess.h>
103#include <asm/mmu_context.h>
104#include <asm/cacheflush.h>
105#include <asm/tlbflush.h>
106
107#include <trace/events/sched.h>
108
109#define CREATE_TRACE_POINTS
110#include <trace/events/task.h>
111
112/*
113 * Minimum number of threads to boot the kernel
114 */
115#define MIN_THREADS 20
116
117/*
118 * Maximum number of threads
119 */
120#define MAX_THREADS FUTEX_TID_MASK
121
122/*
123 * Protected counters by write_lock_irq(&tasklist_lock)
124 */
125unsigned long total_forks; /* Handle normal Linux uptimes. */
126int nr_threads; /* The idle threads do not count.. */
127
128static int max_threads; /* tunable limit on nr_threads */
129
130#define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
131
132static const char * const resident_page_types[] = {
133 NAMED_ARRAY_INDEX(MM_FILEPAGES),
134 NAMED_ARRAY_INDEX(MM_ANONPAGES),
135 NAMED_ARRAY_INDEX(MM_SWAPENTS),
136 NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
137};
138
139DEFINE_PER_CPU(unsigned long, process_counts) = 0;
140
141__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
142
143#ifdef CONFIG_PROVE_RCU
144int lockdep_tasklist_lock_is_held(void)
145{
146 return lockdep_is_held(&tasklist_lock);
147}
148EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
149#endif /* #ifdef CONFIG_PROVE_RCU */
150
151int nr_processes(void)
152{
153 int cpu;
154 int total = 0;
155
156 for_each_possible_cpu(cpu)
157 total += per_cpu(process_counts, cpu);
158
159 return total;
160}
161
162void __weak arch_release_task_struct(struct task_struct *tsk)
163{
164}
165
166#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
167static struct kmem_cache *task_struct_cachep;
168
169static inline struct task_struct *alloc_task_struct_node(int node)
170{
171 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
172}
173
174static inline void free_task_struct(struct task_struct *tsk)
175{
176 kmem_cache_free(task_struct_cachep, tsk);
177}
178#endif
179
180#ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
181
182/*
183 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
184 * kmemcache based allocator.
185 */
186# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
187
188# ifdef CONFIG_VMAP_STACK
189/*
190 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
191 * flush. Try to minimize the number of calls by caching stacks.
192 */
193#define NR_CACHED_STACKS 2
194static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
195
196struct vm_stack {
197 struct rcu_head rcu;
198 struct vm_struct *stack_vm_area;
199};
200
201static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
202{
203 unsigned int i;
204
205 for (i = 0; i < NR_CACHED_STACKS; i++) {
206 if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
207 continue;
208 return true;
209 }
210 return false;
211}
212
213static void thread_stack_free_rcu(struct rcu_head *rh)
214{
215 struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
216
217 if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
218 return;
219
220 vfree(vm_stack);
221}
222
223static void thread_stack_delayed_free(struct task_struct *tsk)
224{
225 struct vm_stack *vm_stack = tsk->stack;
226
227 vm_stack->stack_vm_area = tsk->stack_vm_area;
228 call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
229}
230
231static int free_vm_stack_cache(unsigned int cpu)
232{
233 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
234 int i;
235
236 for (i = 0; i < NR_CACHED_STACKS; i++) {
237 struct vm_struct *vm_stack = cached_vm_stacks[i];
238
239 if (!vm_stack)
240 continue;
241
242 vfree(vm_stack->addr);
243 cached_vm_stacks[i] = NULL;
244 }
245
246 return 0;
247}
248
249static int memcg_charge_kernel_stack(struct vm_struct *vm)
250{
251 int i;
252 int ret;
253
254 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
255 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
256
257 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
258 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
259 if (ret)
260 goto err;
261 }
262 return 0;
263err:
264 /*
265 * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
266 * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
267 * ignore this page.
268 */
269 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
270 memcg_kmem_uncharge_page(vm->pages[i], 0);
271 return ret;
272}
273
274static int alloc_thread_stack_node(struct task_struct *tsk, int node)
275{
276 struct vm_struct *vm;
277 void *stack;
278 int i;
279
280 for (i = 0; i < NR_CACHED_STACKS; i++) {
281 struct vm_struct *s;
282
283 s = this_cpu_xchg(cached_stacks[i], NULL);
284
285 if (!s)
286 continue;
287
288 /* Reset stack metadata. */
289 kasan_unpoison_range(s->addr, THREAD_SIZE);
290
291 stack = kasan_reset_tag(s->addr);
292
293 /* Clear stale pointers from reused stack. */
294 memset(stack, 0, THREAD_SIZE);
295
296 if (memcg_charge_kernel_stack(s)) {
297 vfree(s->addr);
298 return -ENOMEM;
299 }
300
301 tsk->stack_vm_area = s;
302 tsk->stack = stack;
303 return 0;
304 }
305
306 /*
307 * Allocated stacks are cached and later reused by new threads,
308 * so memcg accounting is performed manually on assigning/releasing
309 * stacks to tasks. Drop __GFP_ACCOUNT.
310 */
311 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
312 VMALLOC_START, VMALLOC_END,
313 THREADINFO_GFP & ~__GFP_ACCOUNT,
314 PAGE_KERNEL,
315 0, node, __builtin_return_address(0));
316 if (!stack)
317 return -ENOMEM;
318
319 vm = find_vm_area(stack);
320 if (memcg_charge_kernel_stack(vm)) {
321 vfree(stack);
322 return -ENOMEM;
323 }
324 /*
325 * We can't call find_vm_area() in interrupt context, and
326 * free_thread_stack() can be called in interrupt context,
327 * so cache the vm_struct.
328 */
329 tsk->stack_vm_area = vm;
330 stack = kasan_reset_tag(stack);
331 tsk->stack = stack;
332 return 0;
333}
334
335static void free_thread_stack(struct task_struct *tsk)
336{
337 if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
338 thread_stack_delayed_free(tsk);
339
340 tsk->stack = NULL;
341 tsk->stack_vm_area = NULL;
342}
343
344# else /* !CONFIG_VMAP_STACK */
345
346static void thread_stack_free_rcu(struct rcu_head *rh)
347{
348 __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
349}
350
351static void thread_stack_delayed_free(struct task_struct *tsk)
352{
353 struct rcu_head *rh = tsk->stack;
354
355 call_rcu(rh, thread_stack_free_rcu);
356}
357
358static int alloc_thread_stack_node(struct task_struct *tsk, int node)
359{
360 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
361 THREAD_SIZE_ORDER);
362
363 if (likely(page)) {
364 tsk->stack = kasan_reset_tag(page_address(page));
365 return 0;
366 }
367 return -ENOMEM;
368}
369
370static void free_thread_stack(struct task_struct *tsk)
371{
372 thread_stack_delayed_free(tsk);
373 tsk->stack = NULL;
374}
375
376# endif /* CONFIG_VMAP_STACK */
377# else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
378
379static struct kmem_cache *thread_stack_cache;
380
381static void thread_stack_free_rcu(struct rcu_head *rh)
382{
383 kmem_cache_free(thread_stack_cache, rh);
384}
385
386static void thread_stack_delayed_free(struct task_struct *tsk)
387{
388 struct rcu_head *rh = tsk->stack;
389
390 call_rcu(rh, thread_stack_free_rcu);
391}
392
393static int alloc_thread_stack_node(struct task_struct *tsk, int node)
394{
395 unsigned long *stack;
396 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
397 stack = kasan_reset_tag(stack);
398 tsk->stack = stack;
399 return stack ? 0 : -ENOMEM;
400}
401
402static void free_thread_stack(struct task_struct *tsk)
403{
404 thread_stack_delayed_free(tsk);
405 tsk->stack = NULL;
406}
407
408void thread_stack_cache_init(void)
409{
410 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
411 THREAD_SIZE, THREAD_SIZE, 0, 0,
412 THREAD_SIZE, NULL);
413 BUG_ON(thread_stack_cache == NULL);
414}
415
416# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
417#else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
418
419static int alloc_thread_stack_node(struct task_struct *tsk, int node)
420{
421 unsigned long *stack;
422
423 stack = arch_alloc_thread_stack_node(tsk, node);
424 tsk->stack = stack;
425 return stack ? 0 : -ENOMEM;
426}
427
428static void free_thread_stack(struct task_struct *tsk)
429{
430 arch_free_thread_stack(tsk);
431 tsk->stack = NULL;
432}
433
434#endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
435
436/* SLAB cache for signal_struct structures (tsk->signal) */
437static struct kmem_cache *signal_cachep;
438
439/* SLAB cache for sighand_struct structures (tsk->sighand) */
440struct kmem_cache *sighand_cachep;
441
442/* SLAB cache for files_struct structures (tsk->files) */
443struct kmem_cache *files_cachep;
444
445/* SLAB cache for fs_struct structures (tsk->fs) */
446struct kmem_cache *fs_cachep;
447
448/* SLAB cache for vm_area_struct structures */
449static struct kmem_cache *vm_area_cachep;
450
451/* SLAB cache for mm_struct structures (tsk->mm) */
452static struct kmem_cache *mm_cachep;
453
454struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
455{
456 struct vm_area_struct *vma;
457
458 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
459 if (vma)
460 vma_init(vma, mm);
461 return vma;
462}
463
464struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
465{
466 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
467
468 if (new) {
469 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
470 ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
471 /*
472 * orig->shared.rb may be modified concurrently, but the clone
473 * will be reinitialized.
474 */
475 *new = data_race(*orig);
476 INIT_LIST_HEAD(&new->anon_vma_chain);
477 dup_anon_vma_name(orig, new);
478 }
479 return new;
480}
481
482void vm_area_free(struct vm_area_struct *vma)
483{
484 free_anon_vma_name(vma);
485 kmem_cache_free(vm_area_cachep, vma);
486}
487
488static void account_kernel_stack(struct task_struct *tsk, int account)
489{
490 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
491 struct vm_struct *vm = task_stack_vm_area(tsk);
492 int i;
493
494 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
495 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
496 account * (PAGE_SIZE / 1024));
497 } else {
498 void *stack = task_stack_page(tsk);
499
500 /* All stack pages are in the same node. */
501 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
502 account * (THREAD_SIZE / 1024));
503 }
504}
505
506void exit_task_stack_account(struct task_struct *tsk)
507{
508 account_kernel_stack(tsk, -1);
509
510 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
511 struct vm_struct *vm;
512 int i;
513
514 vm = task_stack_vm_area(tsk);
515 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
516 memcg_kmem_uncharge_page(vm->pages[i], 0);
517 }
518}
519
520static void release_task_stack(struct task_struct *tsk)
521{
522 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
523 return; /* Better to leak the stack than to free prematurely */
524
525 free_thread_stack(tsk);
526}
527
528#ifdef CONFIG_THREAD_INFO_IN_TASK
529void put_task_stack(struct task_struct *tsk)
530{
531 if (refcount_dec_and_test(&tsk->stack_refcount))
532 release_task_stack(tsk);
533}
534#endif
535
536void free_task(struct task_struct *tsk)
537{
538#ifdef CONFIG_SECCOMP
539 WARN_ON_ONCE(tsk->seccomp.filter);
540#endif
541 release_user_cpus_ptr(tsk);
542 scs_release(tsk);
543
544#ifndef CONFIG_THREAD_INFO_IN_TASK
545 /*
546 * The task is finally done with both the stack and thread_info,
547 * so free both.
548 */
549 release_task_stack(tsk);
550#else
551 /*
552 * If the task had a separate stack allocation, it should be gone
553 * by now.
554 */
555 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
556#endif
557 rt_mutex_debug_task_free(tsk);
558 ftrace_graph_exit_task(tsk);
559 arch_release_task_struct(tsk);
560 if (tsk->flags & PF_KTHREAD)
561 free_kthread_struct(tsk);
562 free_task_struct(tsk);
563}
564EXPORT_SYMBOL(free_task);
565
566static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
567{
568 struct file *exe_file;
569
570 exe_file = get_mm_exe_file(oldmm);
571 RCU_INIT_POINTER(mm->exe_file, exe_file);
572 /*
573 * We depend on the oldmm having properly denied write access to the
574 * exe_file already.
575 */
576 if (exe_file && deny_write_access(exe_file))
577 pr_warn_once("deny_write_access() failed in %s\n", __func__);
578}
579
580#ifdef CONFIG_MMU
581static __latent_entropy int dup_mmap(struct mm_struct *mm,
582 struct mm_struct *oldmm)
583{
584 struct vm_area_struct *mpnt, *tmp;
585 int retval;
586 unsigned long charge = 0;
587 LIST_HEAD(uf);
588 MA_STATE(old_mas, &oldmm->mm_mt, 0, 0);
589 MA_STATE(mas, &mm->mm_mt, 0, 0);
590
591 uprobe_start_dup_mmap();
592 if (mmap_write_lock_killable(oldmm)) {
593 retval = -EINTR;
594 goto fail_uprobe_end;
595 }
596 flush_cache_dup_mm(oldmm);
597 uprobe_dup_mmap(oldmm, mm);
598 /*
599 * Not linked in yet - no deadlock potential:
600 */
601 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
602
603 /* No ordering required: file already has been exposed. */
604 dup_mm_exe_file(mm, oldmm);
605
606 mm->total_vm = oldmm->total_vm;
607 mm->data_vm = oldmm->data_vm;
608 mm->exec_vm = oldmm->exec_vm;
609 mm->stack_vm = oldmm->stack_vm;
610
611 retval = ksm_fork(mm, oldmm);
612 if (retval)
613 goto out;
614 khugepaged_fork(mm, oldmm);
615
616 retval = mas_expected_entries(&mas, oldmm->map_count);
617 if (retval)
618 goto out;
619
620 mas_for_each(&old_mas, mpnt, ULONG_MAX) {
621 struct file *file;
622
623 if (mpnt->vm_flags & VM_DONTCOPY) {
624 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
625 continue;
626 }
627 charge = 0;
628 /*
629 * Don't duplicate many vmas if we've been oom-killed (for
630 * example)
631 */
632 if (fatal_signal_pending(current)) {
633 retval = -EINTR;
634 goto loop_out;
635 }
636 if (mpnt->vm_flags & VM_ACCOUNT) {
637 unsigned long len = vma_pages(mpnt);
638
639 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
640 goto fail_nomem;
641 charge = len;
642 }
643 tmp = vm_area_dup(mpnt);
644 if (!tmp)
645 goto fail_nomem;
646 retval = vma_dup_policy(mpnt, tmp);
647 if (retval)
648 goto fail_nomem_policy;
649 tmp->vm_mm = mm;
650 retval = dup_userfaultfd(tmp, &uf);
651 if (retval)
652 goto fail_nomem_anon_vma_fork;
653 if (tmp->vm_flags & VM_WIPEONFORK) {
654 /*
655 * VM_WIPEONFORK gets a clean slate in the child.
656 * Don't prepare anon_vma until fault since we don't
657 * copy page for current vma.
658 */
659 tmp->anon_vma = NULL;
660 } else if (anon_vma_fork(tmp, mpnt))
661 goto fail_nomem_anon_vma_fork;
662 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
663 file = tmp->vm_file;
664 if (file) {
665 struct address_space *mapping = file->f_mapping;
666
667 get_file(file);
668 i_mmap_lock_write(mapping);
669 if (tmp->vm_flags & VM_SHARED)
670 mapping_allow_writable(mapping);
671 flush_dcache_mmap_lock(mapping);
672 /* insert tmp into the share list, just after mpnt */
673 vma_interval_tree_insert_after(tmp, mpnt,
674 &mapping->i_mmap);
675 flush_dcache_mmap_unlock(mapping);
676 i_mmap_unlock_write(mapping);
677 }
678
679 /*
680 * Copy/update hugetlb private vma information.
681 */
682 if (is_vm_hugetlb_page(tmp))
683 hugetlb_dup_vma_private(tmp);
684
685 /* Link the vma into the MT */
686 mas.index = tmp->vm_start;
687 mas.last = tmp->vm_end - 1;
688 mas_store(&mas, tmp);
689 if (mas_is_err(&mas))
690 goto fail_nomem_mas_store;
691
692 mm->map_count++;
693 if (!(tmp->vm_flags & VM_WIPEONFORK))
694 retval = copy_page_range(tmp, mpnt);
695
696 if (tmp->vm_ops && tmp->vm_ops->open)
697 tmp->vm_ops->open(tmp);
698
699 if (retval)
700 goto loop_out;
701 }
702 /* a new mm has just been created */
703 retval = arch_dup_mmap(oldmm, mm);
704loop_out:
705 mas_destroy(&mas);
706out:
707 mmap_write_unlock(mm);
708 flush_tlb_mm(oldmm);
709 mmap_write_unlock(oldmm);
710 dup_userfaultfd_complete(&uf);
711fail_uprobe_end:
712 uprobe_end_dup_mmap();
713 return retval;
714
715fail_nomem_mas_store:
716 unlink_anon_vmas(tmp);
717fail_nomem_anon_vma_fork:
718 mpol_put(vma_policy(tmp));
719fail_nomem_policy:
720 vm_area_free(tmp);
721fail_nomem:
722 retval = -ENOMEM;
723 vm_unacct_memory(charge);
724 goto loop_out;
725}
726
727static inline int mm_alloc_pgd(struct mm_struct *mm)
728{
729 mm->pgd = pgd_alloc(mm);
730 if (unlikely(!mm->pgd))
731 return -ENOMEM;
732 return 0;
733}
734
735static inline void mm_free_pgd(struct mm_struct *mm)
736{
737 pgd_free(mm, mm->pgd);
738}
739#else
740static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
741{
742 mmap_write_lock(oldmm);
743 dup_mm_exe_file(mm, oldmm);
744 mmap_write_unlock(oldmm);
745 return 0;
746}
747#define mm_alloc_pgd(mm) (0)
748#define mm_free_pgd(mm)
749#endif /* CONFIG_MMU */
750
751static void check_mm(struct mm_struct *mm)
752{
753 int i;
754
755 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
756 "Please make sure 'struct resident_page_types[]' is updated as well");
757
758 for (i = 0; i < NR_MM_COUNTERS; i++) {
759 long x = percpu_counter_sum(&mm->rss_stat[i]);
760
761 if (likely(!x))
762 continue;
763
764 /* Making sure this is not due to race with CPU offlining. */
765 x = percpu_counter_sum_all(&mm->rss_stat[i]);
766 if (unlikely(x))
767 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
768 mm, resident_page_types[i], x);
769 }
770
771 if (mm_pgtables_bytes(mm))
772 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
773 mm_pgtables_bytes(mm));
774
775#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
776 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
777#endif
778}
779
780#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
781#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
782
783/*
784 * Called when the last reference to the mm
785 * is dropped: either by a lazy thread or by
786 * mmput. Free the page directory and the mm.
787 */
788void __mmdrop(struct mm_struct *mm)
789{
790 int i;
791
792 BUG_ON(mm == &init_mm);
793 WARN_ON_ONCE(mm == current->mm);
794 WARN_ON_ONCE(mm == current->active_mm);
795 mm_free_pgd(mm);
796 destroy_context(mm);
797 mmu_notifier_subscriptions_destroy(mm);
798 check_mm(mm);
799 put_user_ns(mm->user_ns);
800 mm_pasid_drop(mm);
801
802 for (i = 0; i < NR_MM_COUNTERS; i++)
803 percpu_counter_destroy(&mm->rss_stat[i]);
804 free_mm(mm);
805}
806EXPORT_SYMBOL_GPL(__mmdrop);
807
808static void mmdrop_async_fn(struct work_struct *work)
809{
810 struct mm_struct *mm;
811
812 mm = container_of(work, struct mm_struct, async_put_work);
813 __mmdrop(mm);
814}
815
816static void mmdrop_async(struct mm_struct *mm)
817{
818 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
819 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
820 schedule_work(&mm->async_put_work);
821 }
822}
823
824static inline void free_signal_struct(struct signal_struct *sig)
825{
826 taskstats_tgid_free(sig);
827 sched_autogroup_exit(sig);
828 /*
829 * __mmdrop is not safe to call from softirq context on x86 due to
830 * pgd_dtor so postpone it to the async context
831 */
832 if (sig->oom_mm)
833 mmdrop_async(sig->oom_mm);
834 kmem_cache_free(signal_cachep, sig);
835}
836
837static inline void put_signal_struct(struct signal_struct *sig)
838{
839 if (refcount_dec_and_test(&sig->sigcnt))
840 free_signal_struct(sig);
841}
842
843void __put_task_struct(struct task_struct *tsk)
844{
845 WARN_ON(!tsk->exit_state);
846 WARN_ON(refcount_read(&tsk->usage));
847 WARN_ON(tsk == current);
848
849 io_uring_free(tsk);
850 cgroup_free(tsk);
851 task_numa_free(tsk, true);
852 security_task_free(tsk);
853 bpf_task_storage_free(tsk);
854 exit_creds(tsk);
855 delayacct_tsk_free(tsk);
856 put_signal_struct(tsk->signal);
857 sched_core_free(tsk);
858 free_task(tsk);
859}
860EXPORT_SYMBOL_GPL(__put_task_struct);
861
862void __init __weak arch_task_cache_init(void) { }
863
864/*
865 * set_max_threads
866 */
867static void set_max_threads(unsigned int max_threads_suggested)
868{
869 u64 threads;
870 unsigned long nr_pages = totalram_pages();
871
872 /*
873 * The number of threads shall be limited such that the thread
874 * structures may only consume a small part of the available memory.
875 */
876 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
877 threads = MAX_THREADS;
878 else
879 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
880 (u64) THREAD_SIZE * 8UL);
881
882 if (threads > max_threads_suggested)
883 threads = max_threads_suggested;
884
885 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
886}
887
888#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
889/* Initialized by the architecture: */
890int arch_task_struct_size __read_mostly;
891#endif
892
893#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
894static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
895{
896 /* Fetch thread_struct whitelist for the architecture. */
897 arch_thread_struct_whitelist(offset, size);
898
899 /*
900 * Handle zero-sized whitelist or empty thread_struct, otherwise
901 * adjust offset to position of thread_struct in task_struct.
902 */
903 if (unlikely(*size == 0))
904 *offset = 0;
905 else
906 *offset += offsetof(struct task_struct, thread);
907}
908#endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
909
910void __init fork_init(void)
911{
912 int i;
913#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
914#ifndef ARCH_MIN_TASKALIGN
915#define ARCH_MIN_TASKALIGN 0
916#endif
917 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
918 unsigned long useroffset, usersize;
919
920 /* create a slab on which task_structs can be allocated */
921 task_struct_whitelist(&useroffset, &usersize);
922 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
923 arch_task_struct_size, align,
924 SLAB_PANIC|SLAB_ACCOUNT,
925 useroffset, usersize, NULL);
926#endif
927
928 /* do the arch specific task caches init */
929 arch_task_cache_init();
930
931 set_max_threads(MAX_THREADS);
932
933 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
934 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
935 init_task.signal->rlim[RLIMIT_SIGPENDING] =
936 init_task.signal->rlim[RLIMIT_NPROC];
937
938 for (i = 0; i < UCOUNT_COUNTS; i++)
939 init_user_ns.ucount_max[i] = max_threads/2;
940
941 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
942 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
943 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
944 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
945
946#ifdef CONFIG_VMAP_STACK
947 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
948 NULL, free_vm_stack_cache);
949#endif
950
951 scs_init();
952
953 lockdep_init_task(&init_task);
954 uprobes_init();
955}
956
957int __weak arch_dup_task_struct(struct task_struct *dst,
958 struct task_struct *src)
959{
960 *dst = *src;
961 return 0;
962}
963
964void set_task_stack_end_magic(struct task_struct *tsk)
965{
966 unsigned long *stackend;
967
968 stackend = end_of_stack(tsk);
969 *stackend = STACK_END_MAGIC; /* for overflow detection */
970}
971
972static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
973{
974 struct task_struct *tsk;
975 int err;
976
977 if (node == NUMA_NO_NODE)
978 node = tsk_fork_get_node(orig);
979 tsk = alloc_task_struct_node(node);
980 if (!tsk)
981 return NULL;
982
983 err = arch_dup_task_struct(tsk, orig);
984 if (err)
985 goto free_tsk;
986
987 err = alloc_thread_stack_node(tsk, node);
988 if (err)
989 goto free_tsk;
990
991#ifdef CONFIG_THREAD_INFO_IN_TASK
992 refcount_set(&tsk->stack_refcount, 1);
993#endif
994 account_kernel_stack(tsk, 1);
995
996 err = scs_prepare(tsk, node);
997 if (err)
998 goto free_stack;
999
1000#ifdef CONFIG_SECCOMP
1001 /*
1002 * We must handle setting up seccomp filters once we're under
1003 * the sighand lock in case orig has changed between now and
1004 * then. Until then, filter must be NULL to avoid messing up
1005 * the usage counts on the error path calling free_task.
1006 */
1007 tsk->seccomp.filter = NULL;
1008#endif
1009
1010 setup_thread_stack(tsk, orig);
1011 clear_user_return_notifier(tsk);
1012 clear_tsk_need_resched(tsk);
1013 set_task_stack_end_magic(tsk);
1014 clear_syscall_work_syscall_user_dispatch(tsk);
1015
1016#ifdef CONFIG_STACKPROTECTOR
1017 tsk->stack_canary = get_random_canary();
1018#endif
1019 if (orig->cpus_ptr == &orig->cpus_mask)
1020 tsk->cpus_ptr = &tsk->cpus_mask;
1021 dup_user_cpus_ptr(tsk, orig, node);
1022
1023 /*
1024 * One for the user space visible state that goes away when reaped.
1025 * One for the scheduler.
1026 */
1027 refcount_set(&tsk->rcu_users, 2);
1028 /* One for the rcu users */
1029 refcount_set(&tsk->usage, 1);
1030#ifdef CONFIG_BLK_DEV_IO_TRACE
1031 tsk->btrace_seq = 0;
1032#endif
1033 tsk->splice_pipe = NULL;
1034 tsk->task_frag.page = NULL;
1035 tsk->wake_q.next = NULL;
1036 tsk->worker_private = NULL;
1037
1038 kcov_task_init(tsk);
1039 kmsan_task_create(tsk);
1040 kmap_local_fork(tsk);
1041
1042#ifdef CONFIG_FAULT_INJECTION
1043 tsk->fail_nth = 0;
1044#endif
1045
1046#ifdef CONFIG_BLK_CGROUP
1047 tsk->throttle_queue = NULL;
1048 tsk->use_memdelay = 0;
1049#endif
1050
1051#ifdef CONFIG_IOMMU_SVA
1052 tsk->pasid_activated = 0;
1053#endif
1054
1055#ifdef CONFIG_MEMCG
1056 tsk->active_memcg = NULL;
1057#endif
1058
1059#ifdef CONFIG_CPU_SUP_INTEL
1060 tsk->reported_split_lock = 0;
1061#endif
1062
1063 return tsk;
1064
1065free_stack:
1066 exit_task_stack_account(tsk);
1067 free_thread_stack(tsk);
1068free_tsk:
1069 free_task_struct(tsk);
1070 return NULL;
1071}
1072
1073__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1074
1075static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1076
1077static int __init coredump_filter_setup(char *s)
1078{
1079 default_dump_filter =
1080 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1081 MMF_DUMP_FILTER_MASK;
1082 return 1;
1083}
1084
1085__setup("coredump_filter=", coredump_filter_setup);
1086
1087#include <linux/init_task.h>
1088
1089static void mm_init_aio(struct mm_struct *mm)
1090{
1091#ifdef CONFIG_AIO
1092 spin_lock_init(&mm->ioctx_lock);
1093 mm->ioctx_table = NULL;
1094#endif
1095}
1096
1097static __always_inline void mm_clear_owner(struct mm_struct *mm,
1098 struct task_struct *p)
1099{
1100#ifdef CONFIG_MEMCG
1101 if (mm->owner == p)
1102 WRITE_ONCE(mm->owner, NULL);
1103#endif
1104}
1105
1106static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1107{
1108#ifdef CONFIG_MEMCG
1109 mm->owner = p;
1110#endif
1111}
1112
1113static void mm_init_uprobes_state(struct mm_struct *mm)
1114{
1115#ifdef CONFIG_UPROBES
1116 mm->uprobes_state.xol_area = NULL;
1117#endif
1118}
1119
1120static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1121 struct user_namespace *user_ns)
1122{
1123 int i;
1124
1125 mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
1126 mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
1127 atomic_set(&mm->mm_users, 1);
1128 atomic_set(&mm->mm_count, 1);
1129 seqcount_init(&mm->write_protect_seq);
1130 mmap_init_lock(mm);
1131 INIT_LIST_HEAD(&mm->mmlist);
1132 mm_pgtables_bytes_init(mm);
1133 mm->map_count = 0;
1134 mm->locked_vm = 0;
1135 atomic64_set(&mm->pinned_vm, 0);
1136 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1137 spin_lock_init(&mm->page_table_lock);
1138 spin_lock_init(&mm->arg_lock);
1139 mm_init_cpumask(mm);
1140 mm_init_aio(mm);
1141 mm_init_owner(mm, p);
1142 mm_pasid_init(mm);
1143 RCU_INIT_POINTER(mm->exe_file, NULL);
1144 mmu_notifier_subscriptions_init(mm);
1145 init_tlb_flush_pending(mm);
1146#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1147 mm->pmd_huge_pte = NULL;
1148#endif
1149 mm_init_uprobes_state(mm);
1150 hugetlb_count_init(mm);
1151
1152 if (current->mm) {
1153 mm->flags = current->mm->flags & MMF_INIT_MASK;
1154 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1155 } else {
1156 mm->flags = default_dump_filter;
1157 mm->def_flags = 0;
1158 }
1159
1160 if (mm_alloc_pgd(mm))
1161 goto fail_nopgd;
1162
1163 if (init_new_context(p, mm))
1164 goto fail_nocontext;
1165
1166 for (i = 0; i < NR_MM_COUNTERS; i++)
1167 if (percpu_counter_init(&mm->rss_stat[i], 0, GFP_KERNEL_ACCOUNT))
1168 goto fail_pcpu;
1169
1170 mm->user_ns = get_user_ns(user_ns);
1171 lru_gen_init_mm(mm);
1172 return mm;
1173
1174fail_pcpu:
1175 while (i > 0)
1176 percpu_counter_destroy(&mm->rss_stat[--i]);
1177fail_nocontext:
1178 mm_free_pgd(mm);
1179fail_nopgd:
1180 free_mm(mm);
1181 return NULL;
1182}
1183
1184/*
1185 * Allocate and initialize an mm_struct.
1186 */
1187struct mm_struct *mm_alloc(void)
1188{
1189 struct mm_struct *mm;
1190
1191 mm = allocate_mm();
1192 if (!mm)
1193 return NULL;
1194
1195 memset(mm, 0, sizeof(*mm));
1196 return mm_init(mm, current, current_user_ns());
1197}
1198
1199static inline void __mmput(struct mm_struct *mm)
1200{
1201 VM_BUG_ON(atomic_read(&mm->mm_users));
1202
1203 uprobe_clear_state(mm);
1204 exit_aio(mm);
1205 ksm_exit(mm);
1206 khugepaged_exit(mm); /* must run before exit_mmap */
1207 exit_mmap(mm);
1208 mm_put_huge_zero_page(mm);
1209 set_mm_exe_file(mm, NULL);
1210 if (!list_empty(&mm->mmlist)) {
1211 spin_lock(&mmlist_lock);
1212 list_del(&mm->mmlist);
1213 spin_unlock(&mmlist_lock);
1214 }
1215 if (mm->binfmt)
1216 module_put(mm->binfmt->module);
1217 lru_gen_del_mm(mm);
1218 mmdrop(mm);
1219}
1220
1221/*
1222 * Decrement the use count and release all resources for an mm.
1223 */
1224void mmput(struct mm_struct *mm)
1225{
1226 might_sleep();
1227
1228 if (atomic_dec_and_test(&mm->mm_users))
1229 __mmput(mm);
1230}
1231EXPORT_SYMBOL_GPL(mmput);
1232
1233#ifdef CONFIG_MMU
1234static void mmput_async_fn(struct work_struct *work)
1235{
1236 struct mm_struct *mm = container_of(work, struct mm_struct,
1237 async_put_work);
1238
1239 __mmput(mm);
1240}
1241
1242void mmput_async(struct mm_struct *mm)
1243{
1244 if (atomic_dec_and_test(&mm->mm_users)) {
1245 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1246 schedule_work(&mm->async_put_work);
1247 }
1248}
1249EXPORT_SYMBOL_GPL(mmput_async);
1250#endif
1251
1252/**
1253 * set_mm_exe_file - change a reference to the mm's executable file
1254 *
1255 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1256 *
1257 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1258 * invocations: in mmput() nobody alive left, in execve task is single
1259 * threaded.
1260 *
1261 * Can only fail if new_exe_file != NULL.
1262 */
1263int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1264{
1265 struct file *old_exe_file;
1266
1267 /*
1268 * It is safe to dereference the exe_file without RCU as
1269 * this function is only called if nobody else can access
1270 * this mm -- see comment above for justification.
1271 */
1272 old_exe_file = rcu_dereference_raw(mm->exe_file);
1273
1274 if (new_exe_file) {
1275 /*
1276 * We expect the caller (i.e., sys_execve) to already denied
1277 * write access, so this is unlikely to fail.
1278 */
1279 if (unlikely(deny_write_access(new_exe_file)))
1280 return -EACCES;
1281 get_file(new_exe_file);
1282 }
1283 rcu_assign_pointer(mm->exe_file, new_exe_file);
1284 if (old_exe_file) {
1285 allow_write_access(old_exe_file);
1286 fput(old_exe_file);
1287 }
1288 return 0;
1289}
1290
1291/**
1292 * replace_mm_exe_file - replace a reference to the mm's executable file
1293 *
1294 * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1295 * dealing with concurrent invocation and without grabbing the mmap lock in
1296 * write mode.
1297 *
1298 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1299 */
1300int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1301{
1302 struct vm_area_struct *vma;
1303 struct file *old_exe_file;
1304 int ret = 0;
1305
1306 /* Forbid mm->exe_file change if old file still mapped. */
1307 old_exe_file = get_mm_exe_file(mm);
1308 if (old_exe_file) {
1309 VMA_ITERATOR(vmi, mm, 0);
1310 mmap_read_lock(mm);
1311 for_each_vma(vmi, vma) {
1312 if (!vma->vm_file)
1313 continue;
1314 if (path_equal(&vma->vm_file->f_path,
1315 &old_exe_file->f_path)) {
1316 ret = -EBUSY;
1317 break;
1318 }
1319 }
1320 mmap_read_unlock(mm);
1321 fput(old_exe_file);
1322 if (ret)
1323 return ret;
1324 }
1325
1326 /* set the new file, lockless */
1327 ret = deny_write_access(new_exe_file);
1328 if (ret)
1329 return -EACCES;
1330 get_file(new_exe_file);
1331
1332 old_exe_file = xchg(&mm->exe_file, new_exe_file);
1333 if (old_exe_file) {
1334 /*
1335 * Don't race with dup_mmap() getting the file and disallowing
1336 * write access while someone might open the file writable.
1337 */
1338 mmap_read_lock(mm);
1339 allow_write_access(old_exe_file);
1340 fput(old_exe_file);
1341 mmap_read_unlock(mm);
1342 }
1343 return 0;
1344}
1345
1346/**
1347 * get_mm_exe_file - acquire a reference to the mm's executable file
1348 *
1349 * Returns %NULL if mm has no associated executable file.
1350 * User must release file via fput().
1351 */
1352struct file *get_mm_exe_file(struct mm_struct *mm)
1353{
1354 struct file *exe_file;
1355
1356 rcu_read_lock();
1357 exe_file = rcu_dereference(mm->exe_file);
1358 if (exe_file && !get_file_rcu(exe_file))
1359 exe_file = NULL;
1360 rcu_read_unlock();
1361 return exe_file;
1362}
1363
1364/**
1365 * get_task_exe_file - acquire a reference to the task's executable file
1366 *
1367 * Returns %NULL if task's mm (if any) has no associated executable file or
1368 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1369 * User must release file via fput().
1370 */
1371struct file *get_task_exe_file(struct task_struct *task)
1372{
1373 struct file *exe_file = NULL;
1374 struct mm_struct *mm;
1375
1376 task_lock(task);
1377 mm = task->mm;
1378 if (mm) {
1379 if (!(task->flags & PF_KTHREAD))
1380 exe_file = get_mm_exe_file(mm);
1381 }
1382 task_unlock(task);
1383 return exe_file;
1384}
1385
1386/**
1387 * get_task_mm - acquire a reference to the task's mm
1388 *
1389 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1390 * this kernel workthread has transiently adopted a user mm with use_mm,
1391 * to do its AIO) is not set and if so returns a reference to it, after
1392 * bumping up the use count. User must release the mm via mmput()
1393 * after use. Typically used by /proc and ptrace.
1394 */
1395struct mm_struct *get_task_mm(struct task_struct *task)
1396{
1397 struct mm_struct *mm;
1398
1399 task_lock(task);
1400 mm = task->mm;
1401 if (mm) {
1402 if (task->flags & PF_KTHREAD)
1403 mm = NULL;
1404 else
1405 mmget(mm);
1406 }
1407 task_unlock(task);
1408 return mm;
1409}
1410EXPORT_SYMBOL_GPL(get_task_mm);
1411
1412struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1413{
1414 struct mm_struct *mm;
1415 int err;
1416
1417 err = down_read_killable(&task->signal->exec_update_lock);
1418 if (err)
1419 return ERR_PTR(err);
1420
1421 mm = get_task_mm(task);
1422 if (mm && mm != current->mm &&
1423 !ptrace_may_access(task, mode)) {
1424 mmput(mm);
1425 mm = ERR_PTR(-EACCES);
1426 }
1427 up_read(&task->signal->exec_update_lock);
1428
1429 return mm;
1430}
1431
1432static void complete_vfork_done(struct task_struct *tsk)
1433{
1434 struct completion *vfork;
1435
1436 task_lock(tsk);
1437 vfork = tsk->vfork_done;
1438 if (likely(vfork)) {
1439 tsk->vfork_done = NULL;
1440 complete(vfork);
1441 }
1442 task_unlock(tsk);
1443}
1444
1445static int wait_for_vfork_done(struct task_struct *child,
1446 struct completion *vfork)
1447{
1448 unsigned int state = TASK_UNINTERRUPTIBLE|TASK_KILLABLE|TASK_FREEZABLE;
1449 int killed;
1450
1451 cgroup_enter_frozen();
1452 killed = wait_for_completion_state(vfork, state);
1453 cgroup_leave_frozen(false);
1454
1455 if (killed) {
1456 task_lock(child);
1457 child->vfork_done = NULL;
1458 task_unlock(child);
1459 }
1460
1461 put_task_struct(child);
1462 return killed;
1463}
1464
1465/* Please note the differences between mmput and mm_release.
1466 * mmput is called whenever we stop holding onto a mm_struct,
1467 * error success whatever.
1468 *
1469 * mm_release is called after a mm_struct has been removed
1470 * from the current process.
1471 *
1472 * This difference is important for error handling, when we
1473 * only half set up a mm_struct for a new process and need to restore
1474 * the old one. Because we mmput the new mm_struct before
1475 * restoring the old one. . .
1476 * Eric Biederman 10 January 1998
1477 */
1478static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1479{
1480 uprobe_free_utask(tsk);
1481
1482 /* Get rid of any cached register state */
1483 deactivate_mm(tsk, mm);
1484
1485 /*
1486 * Signal userspace if we're not exiting with a core dump
1487 * because we want to leave the value intact for debugging
1488 * purposes.
1489 */
1490 if (tsk->clear_child_tid) {
1491 if (atomic_read(&mm->mm_users) > 1) {
1492 /*
1493 * We don't check the error code - if userspace has
1494 * not set up a proper pointer then tough luck.
1495 */
1496 put_user(0, tsk->clear_child_tid);
1497 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1498 1, NULL, NULL, 0, 0);
1499 }
1500 tsk->clear_child_tid = NULL;
1501 }
1502
1503 /*
1504 * All done, finally we can wake up parent and return this mm to him.
1505 * Also kthread_stop() uses this completion for synchronization.
1506 */
1507 if (tsk->vfork_done)
1508 complete_vfork_done(tsk);
1509}
1510
1511void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1512{
1513 futex_exit_release(tsk);
1514 mm_release(tsk, mm);
1515}
1516
1517void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1518{
1519 futex_exec_release(tsk);
1520 mm_release(tsk, mm);
1521}
1522
1523/**
1524 * dup_mm() - duplicates an existing mm structure
1525 * @tsk: the task_struct with which the new mm will be associated.
1526 * @oldmm: the mm to duplicate.
1527 *
1528 * Allocates a new mm structure and duplicates the provided @oldmm structure
1529 * content into it.
1530 *
1531 * Return: the duplicated mm or NULL on failure.
1532 */
1533static struct mm_struct *dup_mm(struct task_struct *tsk,
1534 struct mm_struct *oldmm)
1535{
1536 struct mm_struct *mm;
1537 int err;
1538
1539 mm = allocate_mm();
1540 if (!mm)
1541 goto fail_nomem;
1542
1543 memcpy(mm, oldmm, sizeof(*mm));
1544
1545 if (!mm_init(mm, tsk, mm->user_ns))
1546 goto fail_nomem;
1547
1548 err = dup_mmap(mm, oldmm);
1549 if (err)
1550 goto free_pt;
1551
1552 mm->hiwater_rss = get_mm_rss(mm);
1553 mm->hiwater_vm = mm->total_vm;
1554
1555 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1556 goto free_pt;
1557
1558 return mm;
1559
1560free_pt:
1561 /* don't put binfmt in mmput, we haven't got module yet */
1562 mm->binfmt = NULL;
1563 mm_init_owner(mm, NULL);
1564 mmput(mm);
1565
1566fail_nomem:
1567 return NULL;
1568}
1569
1570static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1571{
1572 struct mm_struct *mm, *oldmm;
1573
1574 tsk->min_flt = tsk->maj_flt = 0;
1575 tsk->nvcsw = tsk->nivcsw = 0;
1576#ifdef CONFIG_DETECT_HUNG_TASK
1577 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1578 tsk->last_switch_time = 0;
1579#endif
1580
1581 tsk->mm = NULL;
1582 tsk->active_mm = NULL;
1583
1584 /*
1585 * Are we cloning a kernel thread?
1586 *
1587 * We need to steal a active VM for that..
1588 */
1589 oldmm = current->mm;
1590 if (!oldmm)
1591 return 0;
1592
1593 if (clone_flags & CLONE_VM) {
1594 mmget(oldmm);
1595 mm = oldmm;
1596 } else {
1597 mm = dup_mm(tsk, current->mm);
1598 if (!mm)
1599 return -ENOMEM;
1600 }
1601
1602 tsk->mm = mm;
1603 tsk->active_mm = mm;
1604 return 0;
1605}
1606
1607static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1608{
1609 struct fs_struct *fs = current->fs;
1610 if (clone_flags & CLONE_FS) {
1611 /* tsk->fs is already what we want */
1612 spin_lock(&fs->lock);
1613 if (fs->in_exec) {
1614 spin_unlock(&fs->lock);
1615 return -EAGAIN;
1616 }
1617 fs->users++;
1618 spin_unlock(&fs->lock);
1619 return 0;
1620 }
1621 tsk->fs = copy_fs_struct(fs);
1622 if (!tsk->fs)
1623 return -ENOMEM;
1624 return 0;
1625}
1626
1627static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1628{
1629 struct files_struct *oldf, *newf;
1630 int error = 0;
1631
1632 /*
1633 * A background process may not have any files ...
1634 */
1635 oldf = current->files;
1636 if (!oldf)
1637 goto out;
1638
1639 if (clone_flags & CLONE_FILES) {
1640 atomic_inc(&oldf->count);
1641 goto out;
1642 }
1643
1644 newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1645 if (!newf)
1646 goto out;
1647
1648 tsk->files = newf;
1649 error = 0;
1650out:
1651 return error;
1652}
1653
1654static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1655{
1656 struct sighand_struct *sig;
1657
1658 if (clone_flags & CLONE_SIGHAND) {
1659 refcount_inc(¤t->sighand->count);
1660 return 0;
1661 }
1662 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1663 RCU_INIT_POINTER(tsk->sighand, sig);
1664 if (!sig)
1665 return -ENOMEM;
1666
1667 refcount_set(&sig->count, 1);
1668 spin_lock_irq(¤t->sighand->siglock);
1669 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1670 spin_unlock_irq(¤t->sighand->siglock);
1671
1672 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1673 if (clone_flags & CLONE_CLEAR_SIGHAND)
1674 flush_signal_handlers(tsk, 0);
1675
1676 return 0;
1677}
1678
1679void __cleanup_sighand(struct sighand_struct *sighand)
1680{
1681 if (refcount_dec_and_test(&sighand->count)) {
1682 signalfd_cleanup(sighand);
1683 /*
1684 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1685 * without an RCU grace period, see __lock_task_sighand().
1686 */
1687 kmem_cache_free(sighand_cachep, sighand);
1688 }
1689}
1690
1691/*
1692 * Initialize POSIX timer handling for a thread group.
1693 */
1694static void posix_cpu_timers_init_group(struct signal_struct *sig)
1695{
1696 struct posix_cputimers *pct = &sig->posix_cputimers;
1697 unsigned long cpu_limit;
1698
1699 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1700 posix_cputimers_group_init(pct, cpu_limit);
1701}
1702
1703static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1704{
1705 struct signal_struct *sig;
1706
1707 if (clone_flags & CLONE_THREAD)
1708 return 0;
1709
1710 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1711 tsk->signal = sig;
1712 if (!sig)
1713 return -ENOMEM;
1714
1715 sig->nr_threads = 1;
1716 sig->quick_threads = 1;
1717 atomic_set(&sig->live, 1);
1718 refcount_set(&sig->sigcnt, 1);
1719
1720 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1721 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1722 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1723
1724 init_waitqueue_head(&sig->wait_chldexit);
1725 sig->curr_target = tsk;
1726 init_sigpending(&sig->shared_pending);
1727 INIT_HLIST_HEAD(&sig->multiprocess);
1728 seqlock_init(&sig->stats_lock);
1729 prev_cputime_init(&sig->prev_cputime);
1730
1731#ifdef CONFIG_POSIX_TIMERS
1732 INIT_LIST_HEAD(&sig->posix_timers);
1733 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1734 sig->real_timer.function = it_real_fn;
1735#endif
1736
1737 task_lock(current->group_leader);
1738 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1739 task_unlock(current->group_leader);
1740
1741 posix_cpu_timers_init_group(sig);
1742
1743 tty_audit_fork(sig);
1744 sched_autogroup_fork(sig);
1745
1746 sig->oom_score_adj = current->signal->oom_score_adj;
1747 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1748
1749 mutex_init(&sig->cred_guard_mutex);
1750 init_rwsem(&sig->exec_update_lock);
1751
1752 return 0;
1753}
1754
1755static void copy_seccomp(struct task_struct *p)
1756{
1757#ifdef CONFIG_SECCOMP
1758 /*
1759 * Must be called with sighand->lock held, which is common to
1760 * all threads in the group. Holding cred_guard_mutex is not
1761 * needed because this new task is not yet running and cannot
1762 * be racing exec.
1763 */
1764 assert_spin_locked(¤t->sighand->siglock);
1765
1766 /* Ref-count the new filter user, and assign it. */
1767 get_seccomp_filter(current);
1768 p->seccomp = current->seccomp;
1769
1770 /*
1771 * Explicitly enable no_new_privs here in case it got set
1772 * between the task_struct being duplicated and holding the
1773 * sighand lock. The seccomp state and nnp must be in sync.
1774 */
1775 if (task_no_new_privs(current))
1776 task_set_no_new_privs(p);
1777
1778 /*
1779 * If the parent gained a seccomp mode after copying thread
1780 * flags and between before we held the sighand lock, we have
1781 * to manually enable the seccomp thread flag here.
1782 */
1783 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1784 set_task_syscall_work(p, SECCOMP);
1785#endif
1786}
1787
1788SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1789{
1790 current->clear_child_tid = tidptr;
1791
1792 return task_pid_vnr(current);
1793}
1794
1795static void rt_mutex_init_task(struct task_struct *p)
1796{
1797 raw_spin_lock_init(&p->pi_lock);
1798#ifdef CONFIG_RT_MUTEXES
1799 p->pi_waiters = RB_ROOT_CACHED;
1800 p->pi_top_task = NULL;
1801 p->pi_blocked_on = NULL;
1802#endif
1803}
1804
1805static inline void init_task_pid_links(struct task_struct *task)
1806{
1807 enum pid_type type;
1808
1809 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1810 INIT_HLIST_NODE(&task->pid_links[type]);
1811}
1812
1813static inline void
1814init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1815{
1816 if (type == PIDTYPE_PID)
1817 task->thread_pid = pid;
1818 else
1819 task->signal->pids[type] = pid;
1820}
1821
1822static inline void rcu_copy_process(struct task_struct *p)
1823{
1824#ifdef CONFIG_PREEMPT_RCU
1825 p->rcu_read_lock_nesting = 0;
1826 p->rcu_read_unlock_special.s = 0;
1827 p->rcu_blocked_node = NULL;
1828 INIT_LIST_HEAD(&p->rcu_node_entry);
1829#endif /* #ifdef CONFIG_PREEMPT_RCU */
1830#ifdef CONFIG_TASKS_RCU
1831 p->rcu_tasks_holdout = false;
1832 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1833 p->rcu_tasks_idle_cpu = -1;
1834#endif /* #ifdef CONFIG_TASKS_RCU */
1835#ifdef CONFIG_TASKS_TRACE_RCU
1836 p->trc_reader_nesting = 0;
1837 p->trc_reader_special.s = 0;
1838 INIT_LIST_HEAD(&p->trc_holdout_list);
1839 INIT_LIST_HEAD(&p->trc_blkd_node);
1840#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1841}
1842
1843struct pid *pidfd_pid(const struct file *file)
1844{
1845 if (file->f_op == &pidfd_fops)
1846 return file->private_data;
1847
1848 return ERR_PTR(-EBADF);
1849}
1850
1851static int pidfd_release(struct inode *inode, struct file *file)
1852{
1853 struct pid *pid = file->private_data;
1854
1855 file->private_data = NULL;
1856 put_pid(pid);
1857 return 0;
1858}
1859
1860#ifdef CONFIG_PROC_FS
1861/**
1862 * pidfd_show_fdinfo - print information about a pidfd
1863 * @m: proc fdinfo file
1864 * @f: file referencing a pidfd
1865 *
1866 * Pid:
1867 * This function will print the pid that a given pidfd refers to in the
1868 * pid namespace of the procfs instance.
1869 * If the pid namespace of the process is not a descendant of the pid
1870 * namespace of the procfs instance 0 will be shown as its pid. This is
1871 * similar to calling getppid() on a process whose parent is outside of
1872 * its pid namespace.
1873 *
1874 * NSpid:
1875 * If pid namespaces are supported then this function will also print
1876 * the pid of a given pidfd refers to for all descendant pid namespaces
1877 * starting from the current pid namespace of the instance, i.e. the
1878 * Pid field and the first entry in the NSpid field will be identical.
1879 * If the pid namespace of the process is not a descendant of the pid
1880 * namespace of the procfs instance 0 will be shown as its first NSpid
1881 * entry and no others will be shown.
1882 * Note that this differs from the Pid and NSpid fields in
1883 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1884 * the pid namespace of the procfs instance. The difference becomes
1885 * obvious when sending around a pidfd between pid namespaces from a
1886 * different branch of the tree, i.e. where no ancestral relation is
1887 * present between the pid namespaces:
1888 * - create two new pid namespaces ns1 and ns2 in the initial pid
1889 * namespace (also take care to create new mount namespaces in the
1890 * new pid namespace and mount procfs)
1891 * - create a process with a pidfd in ns1
1892 * - send pidfd from ns1 to ns2
1893 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1894 * have exactly one entry, which is 0
1895 */
1896static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
1897{
1898 struct pid *pid = f->private_data;
1899 struct pid_namespace *ns;
1900 pid_t nr = -1;
1901
1902 if (likely(pid_has_task(pid, PIDTYPE_PID))) {
1903 ns = proc_pid_ns(file_inode(m->file)->i_sb);
1904 nr = pid_nr_ns(pid, ns);
1905 }
1906
1907 seq_put_decimal_ll(m, "Pid:\t", nr);
1908
1909#ifdef CONFIG_PID_NS
1910 seq_put_decimal_ll(m, "\nNSpid:\t", nr);
1911 if (nr > 0) {
1912 int i;
1913
1914 /* If nr is non-zero it means that 'pid' is valid and that
1915 * ns, i.e. the pid namespace associated with the procfs
1916 * instance, is in the pid namespace hierarchy of pid.
1917 * Start at one below the already printed level.
1918 */
1919 for (i = ns->level + 1; i <= pid->level; i++)
1920 seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
1921 }
1922#endif
1923 seq_putc(m, '\n');
1924}
1925#endif
1926
1927/*
1928 * Poll support for process exit notification.
1929 */
1930static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
1931{
1932 struct pid *pid = file->private_data;
1933 __poll_t poll_flags = 0;
1934
1935 poll_wait(file, &pid->wait_pidfd, pts);
1936
1937 /*
1938 * Inform pollers only when the whole thread group exits.
1939 * If the thread group leader exits before all other threads in the
1940 * group, then poll(2) should block, similar to the wait(2) family.
1941 */
1942 if (thread_group_exited(pid))
1943 poll_flags = EPOLLIN | EPOLLRDNORM;
1944
1945 return poll_flags;
1946}
1947
1948const struct file_operations pidfd_fops = {
1949 .release = pidfd_release,
1950 .poll = pidfd_poll,
1951#ifdef CONFIG_PROC_FS
1952 .show_fdinfo = pidfd_show_fdinfo,
1953#endif
1954};
1955
1956static void __delayed_free_task(struct rcu_head *rhp)
1957{
1958 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1959
1960 free_task(tsk);
1961}
1962
1963static __always_inline void delayed_free_task(struct task_struct *tsk)
1964{
1965 if (IS_ENABLED(CONFIG_MEMCG))
1966 call_rcu(&tsk->rcu, __delayed_free_task);
1967 else
1968 free_task(tsk);
1969}
1970
1971static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1972{
1973 /* Skip if kernel thread */
1974 if (!tsk->mm)
1975 return;
1976
1977 /* Skip if spawning a thread or using vfork */
1978 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1979 return;
1980
1981 /* We need to synchronize with __set_oom_adj */
1982 mutex_lock(&oom_adj_mutex);
1983 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1984 /* Update the values in case they were changed after copy_signal */
1985 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1986 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1987 mutex_unlock(&oom_adj_mutex);
1988}
1989
1990#ifdef CONFIG_RV
1991static void rv_task_fork(struct task_struct *p)
1992{
1993 int i;
1994
1995 for (i = 0; i < RV_PER_TASK_MONITORS; i++)
1996 p->rv[i].da_mon.monitoring = false;
1997}
1998#else
1999#define rv_task_fork(p) do {} while (0)
2000#endif
2001
2002/*
2003 * This creates a new process as a copy of the old one,
2004 * but does not actually start it yet.
2005 *
2006 * It copies the registers, and all the appropriate
2007 * parts of the process environment (as per the clone
2008 * flags). The actual kick-off is left to the caller.
2009 */
2010static __latent_entropy struct task_struct *copy_process(
2011 struct pid *pid,
2012 int trace,
2013 int node,
2014 struct kernel_clone_args *args)
2015{
2016 int pidfd = -1, retval;
2017 struct task_struct *p;
2018 struct multiprocess_signals delayed;
2019 struct file *pidfile = NULL;
2020 const u64 clone_flags = args->flags;
2021 struct nsproxy *nsp = current->nsproxy;
2022
2023 /*
2024 * Don't allow sharing the root directory with processes in a different
2025 * namespace
2026 */
2027 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
2028 return ERR_PTR(-EINVAL);
2029
2030 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
2031 return ERR_PTR(-EINVAL);
2032
2033 /*
2034 * Thread groups must share signals as well, and detached threads
2035 * can only be started up within the thread group.
2036 */
2037 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2038 return ERR_PTR(-EINVAL);
2039
2040 /*
2041 * Shared signal handlers imply shared VM. By way of the above,
2042 * thread groups also imply shared VM. Blocking this case allows
2043 * for various simplifications in other code.
2044 */
2045 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2046 return ERR_PTR(-EINVAL);
2047
2048 /*
2049 * Siblings of global init remain as zombies on exit since they are
2050 * not reaped by their parent (swapper). To solve this and to avoid
2051 * multi-rooted process trees, prevent global and container-inits
2052 * from creating siblings.
2053 */
2054 if ((clone_flags & CLONE_PARENT) &&
2055 current->signal->flags & SIGNAL_UNKILLABLE)
2056 return ERR_PTR(-EINVAL);
2057
2058 /*
2059 * If the new process will be in a different pid or user namespace
2060 * do not allow it to share a thread group with the forking task.
2061 */
2062 if (clone_flags & CLONE_THREAD) {
2063 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2064 (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2065 return ERR_PTR(-EINVAL);
2066 }
2067
2068 if (clone_flags & CLONE_PIDFD) {
2069 /*
2070 * - CLONE_DETACHED is blocked so that we can potentially
2071 * reuse it later for CLONE_PIDFD.
2072 * - CLONE_THREAD is blocked until someone really needs it.
2073 */
2074 if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
2075 return ERR_PTR(-EINVAL);
2076 }
2077
2078 /*
2079 * Force any signals received before this point to be delivered
2080 * before the fork happens. Collect up signals sent to multiple
2081 * processes that happen during the fork and delay them so that
2082 * they appear to happen after the fork.
2083 */
2084 sigemptyset(&delayed.signal);
2085 INIT_HLIST_NODE(&delayed.node);
2086
2087 spin_lock_irq(¤t->sighand->siglock);
2088 if (!(clone_flags & CLONE_THREAD))
2089 hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2090 recalc_sigpending();
2091 spin_unlock_irq(¤t->sighand->siglock);
2092 retval = -ERESTARTNOINTR;
2093 if (task_sigpending(current))
2094 goto fork_out;
2095
2096 retval = -ENOMEM;
2097 p = dup_task_struct(current, node);
2098 if (!p)
2099 goto fork_out;
2100 p->flags &= ~PF_KTHREAD;
2101 if (args->kthread)
2102 p->flags |= PF_KTHREAD;
2103 if (args->io_thread) {
2104 /*
2105 * Mark us an IO worker, and block any signal that isn't
2106 * fatal or STOP
2107 */
2108 p->flags |= PF_IO_WORKER;
2109 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2110 }
2111
2112 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2113 /*
2114 * Clear TID on mm_release()?
2115 */
2116 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2117
2118 ftrace_graph_init_task(p);
2119
2120 rt_mutex_init_task(p);
2121
2122 lockdep_assert_irqs_enabled();
2123#ifdef CONFIG_PROVE_LOCKING
2124 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2125#endif
2126 retval = copy_creds(p, clone_flags);
2127 if (retval < 0)
2128 goto bad_fork_free;
2129
2130 retval = -EAGAIN;
2131 if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2132 if (p->real_cred->user != INIT_USER &&
2133 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2134 goto bad_fork_cleanup_count;
2135 }
2136 current->flags &= ~PF_NPROC_EXCEEDED;
2137
2138 /*
2139 * If multiple threads are within copy_process(), then this check
2140 * triggers too late. This doesn't hurt, the check is only there
2141 * to stop root fork bombs.
2142 */
2143 retval = -EAGAIN;
2144 if (data_race(nr_threads >= max_threads))
2145 goto bad_fork_cleanup_count;
2146
2147 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2148 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2149 p->flags |= PF_FORKNOEXEC;
2150 INIT_LIST_HEAD(&p->children);
2151 INIT_LIST_HEAD(&p->sibling);
2152 rcu_copy_process(p);
2153 p->vfork_done = NULL;
2154 spin_lock_init(&p->alloc_lock);
2155
2156 init_sigpending(&p->pending);
2157
2158 p->utime = p->stime = p->gtime = 0;
2159#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2160 p->utimescaled = p->stimescaled = 0;
2161#endif
2162 prev_cputime_init(&p->prev_cputime);
2163
2164#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2165 seqcount_init(&p->vtime.seqcount);
2166 p->vtime.starttime = 0;
2167 p->vtime.state = VTIME_INACTIVE;
2168#endif
2169
2170#ifdef CONFIG_IO_URING
2171 p->io_uring = NULL;
2172#endif
2173
2174#if defined(SPLIT_RSS_COUNTING)
2175 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2176#endif
2177
2178 p->default_timer_slack_ns = current->timer_slack_ns;
2179
2180#ifdef CONFIG_PSI
2181 p->psi_flags = 0;
2182#endif
2183
2184 task_io_accounting_init(&p->ioac);
2185 acct_clear_integrals(p);
2186
2187 posix_cputimers_init(&p->posix_cputimers);
2188
2189 p->io_context = NULL;
2190 audit_set_context(p, NULL);
2191 cgroup_fork(p);
2192 if (args->kthread) {
2193 if (!set_kthread_struct(p))
2194 goto bad_fork_cleanup_delayacct;
2195 }
2196#ifdef CONFIG_NUMA
2197 p->mempolicy = mpol_dup(p->mempolicy);
2198 if (IS_ERR(p->mempolicy)) {
2199 retval = PTR_ERR(p->mempolicy);
2200 p->mempolicy = NULL;
2201 goto bad_fork_cleanup_delayacct;
2202 }
2203#endif
2204#ifdef CONFIG_CPUSETS
2205 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2206 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2207 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2208#endif
2209#ifdef CONFIG_TRACE_IRQFLAGS
2210 memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2211 p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2212 p->irqtrace.softirq_enable_ip = _THIS_IP_;
2213 p->softirqs_enabled = 1;
2214 p->softirq_context = 0;
2215#endif
2216
2217 p->pagefault_disabled = 0;
2218
2219#ifdef CONFIG_LOCKDEP
2220 lockdep_init_task(p);
2221#endif
2222
2223#ifdef CONFIG_DEBUG_MUTEXES
2224 p->blocked_on = NULL; /* not blocked yet */
2225#endif
2226#ifdef CONFIG_BCACHE
2227 p->sequential_io = 0;
2228 p->sequential_io_avg = 0;
2229#endif
2230#ifdef CONFIG_BPF_SYSCALL
2231 RCU_INIT_POINTER(p->bpf_storage, NULL);
2232 p->bpf_ctx = NULL;
2233#endif
2234
2235 /* Perform scheduler related setup. Assign this task to a CPU. */
2236 retval = sched_fork(clone_flags, p);
2237 if (retval)
2238 goto bad_fork_cleanup_policy;
2239
2240 retval = perf_event_init_task(p, clone_flags);
2241 if (retval)
2242 goto bad_fork_cleanup_policy;
2243 retval = audit_alloc(p);
2244 if (retval)
2245 goto bad_fork_cleanup_perf;
2246 /* copy all the process information */
2247 shm_init_task(p);
2248 retval = security_task_alloc(p, clone_flags);
2249 if (retval)
2250 goto bad_fork_cleanup_audit;
2251 retval = copy_semundo(clone_flags, p);
2252 if (retval)
2253 goto bad_fork_cleanup_security;
2254 retval = copy_files(clone_flags, p);
2255 if (retval)
2256 goto bad_fork_cleanup_semundo;
2257 retval = copy_fs(clone_flags, p);
2258 if (retval)
2259 goto bad_fork_cleanup_files;
2260 retval = copy_sighand(clone_flags, p);
2261 if (retval)
2262 goto bad_fork_cleanup_fs;
2263 retval = copy_signal(clone_flags, p);
2264 if (retval)
2265 goto bad_fork_cleanup_sighand;
2266 retval = copy_mm(clone_flags, p);
2267 if (retval)
2268 goto bad_fork_cleanup_signal;
2269 retval = copy_namespaces(clone_flags, p);
2270 if (retval)
2271 goto bad_fork_cleanup_mm;
2272 retval = copy_io(clone_flags, p);
2273 if (retval)
2274 goto bad_fork_cleanup_namespaces;
2275 retval = copy_thread(p, args);
2276 if (retval)
2277 goto bad_fork_cleanup_io;
2278
2279 stackleak_task_init(p);
2280
2281 if (pid != &init_struct_pid) {
2282 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2283 args->set_tid_size);
2284 if (IS_ERR(pid)) {
2285 retval = PTR_ERR(pid);
2286 goto bad_fork_cleanup_thread;
2287 }
2288 }
2289
2290 /*
2291 * This has to happen after we've potentially unshared the file
2292 * descriptor table (so that the pidfd doesn't leak into the child
2293 * if the fd table isn't shared).
2294 */
2295 if (clone_flags & CLONE_PIDFD) {
2296 retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2297 if (retval < 0)
2298 goto bad_fork_free_pid;
2299
2300 pidfd = retval;
2301
2302 pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2303 O_RDWR | O_CLOEXEC);
2304 if (IS_ERR(pidfile)) {
2305 put_unused_fd(pidfd);
2306 retval = PTR_ERR(pidfile);
2307 goto bad_fork_free_pid;
2308 }
2309 get_pid(pid); /* held by pidfile now */
2310
2311 retval = put_user(pidfd, args->pidfd);
2312 if (retval)
2313 goto bad_fork_put_pidfd;
2314 }
2315
2316#ifdef CONFIG_BLOCK
2317 p->plug = NULL;
2318#endif
2319 futex_init_task(p);
2320
2321 /*
2322 * sigaltstack should be cleared when sharing the same VM
2323 */
2324 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2325 sas_ss_reset(p);
2326
2327 /*
2328 * Syscall tracing and stepping should be turned off in the
2329 * child regardless of CLONE_PTRACE.
2330 */
2331 user_disable_single_step(p);
2332 clear_task_syscall_work(p, SYSCALL_TRACE);
2333#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2334 clear_task_syscall_work(p, SYSCALL_EMU);
2335#endif
2336 clear_tsk_latency_tracing(p);
2337
2338 /* ok, now we should be set up.. */
2339 p->pid = pid_nr(pid);
2340 if (clone_flags & CLONE_THREAD) {
2341 p->group_leader = current->group_leader;
2342 p->tgid = current->tgid;
2343 } else {
2344 p->group_leader = p;
2345 p->tgid = p->pid;
2346 }
2347
2348 p->nr_dirtied = 0;
2349 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2350 p->dirty_paused_when = 0;
2351
2352 p->pdeath_signal = 0;
2353 INIT_LIST_HEAD(&p->thread_group);
2354 p->task_works = NULL;
2355 clear_posix_cputimers_work(p);
2356
2357#ifdef CONFIG_KRETPROBES
2358 p->kretprobe_instances.first = NULL;
2359#endif
2360#ifdef CONFIG_RETHOOK
2361 p->rethooks.first = NULL;
2362#endif
2363
2364 /*
2365 * Ensure that the cgroup subsystem policies allow the new process to be
2366 * forked. It should be noted that the new process's css_set can be changed
2367 * between here and cgroup_post_fork() if an organisation operation is in
2368 * progress.
2369 */
2370 retval = cgroup_can_fork(p, args);
2371 if (retval)
2372 goto bad_fork_put_pidfd;
2373
2374 /*
2375 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2376 * the new task on the correct runqueue. All this *before* the task
2377 * becomes visible.
2378 *
2379 * This isn't part of ->can_fork() because while the re-cloning is
2380 * cgroup specific, it unconditionally needs to place the task on a
2381 * runqueue.
2382 */
2383 sched_cgroup_fork(p, args);
2384
2385 /*
2386 * From this point on we must avoid any synchronous user-space
2387 * communication until we take the tasklist-lock. In particular, we do
2388 * not want user-space to be able to predict the process start-time by
2389 * stalling fork(2) after we recorded the start_time but before it is
2390 * visible to the system.
2391 */
2392
2393 p->start_time = ktime_get_ns();
2394 p->start_boottime = ktime_get_boottime_ns();
2395
2396 /*
2397 * Make it visible to the rest of the system, but dont wake it up yet.
2398 * Need tasklist lock for parent etc handling!
2399 */
2400 write_lock_irq(&tasklist_lock);
2401
2402 /* CLONE_PARENT re-uses the old parent */
2403 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2404 p->real_parent = current->real_parent;
2405 p->parent_exec_id = current->parent_exec_id;
2406 if (clone_flags & CLONE_THREAD)
2407 p->exit_signal = -1;
2408 else
2409 p->exit_signal = current->group_leader->exit_signal;
2410 } else {
2411 p->real_parent = current;
2412 p->parent_exec_id = current->self_exec_id;
2413 p->exit_signal = args->exit_signal;
2414 }
2415
2416 klp_copy_process(p);
2417
2418 sched_core_fork(p);
2419
2420 spin_lock(¤t->sighand->siglock);
2421
2422 rv_task_fork(p);
2423
2424 rseq_fork(p, clone_flags);
2425
2426 /* Don't start children in a dying pid namespace */
2427 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2428 retval = -ENOMEM;
2429 goto bad_fork_cancel_cgroup;
2430 }
2431
2432 /* Let kill terminate clone/fork in the middle */
2433 if (fatal_signal_pending(current)) {
2434 retval = -EINTR;
2435 goto bad_fork_cancel_cgroup;
2436 }
2437
2438 /* No more failure paths after this point. */
2439
2440 /*
2441 * Copy seccomp details explicitly here, in case they were changed
2442 * before holding sighand lock.
2443 */
2444 copy_seccomp(p);
2445
2446 init_task_pid_links(p);
2447 if (likely(p->pid)) {
2448 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2449
2450 init_task_pid(p, PIDTYPE_PID, pid);
2451 if (thread_group_leader(p)) {
2452 init_task_pid(p, PIDTYPE_TGID, pid);
2453 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2454 init_task_pid(p, PIDTYPE_SID, task_session(current));
2455
2456 if (is_child_reaper(pid)) {
2457 ns_of_pid(pid)->child_reaper = p;
2458 p->signal->flags |= SIGNAL_UNKILLABLE;
2459 }
2460 p->signal->shared_pending.signal = delayed.signal;
2461 p->signal->tty = tty_kref_get(current->signal->tty);
2462 /*
2463 * Inherit has_child_subreaper flag under the same
2464 * tasklist_lock with adding child to the process tree
2465 * for propagate_has_child_subreaper optimization.
2466 */
2467 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2468 p->real_parent->signal->is_child_subreaper;
2469 list_add_tail(&p->sibling, &p->real_parent->children);
2470 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2471 attach_pid(p, PIDTYPE_TGID);
2472 attach_pid(p, PIDTYPE_PGID);
2473 attach_pid(p, PIDTYPE_SID);
2474 __this_cpu_inc(process_counts);
2475 } else {
2476 current->signal->nr_threads++;
2477 current->signal->quick_threads++;
2478 atomic_inc(¤t->signal->live);
2479 refcount_inc(¤t->signal->sigcnt);
2480 task_join_group_stop(p);
2481 list_add_tail_rcu(&p->thread_group,
2482 &p->group_leader->thread_group);
2483 list_add_tail_rcu(&p->thread_node,
2484 &p->signal->thread_head);
2485 }
2486 attach_pid(p, PIDTYPE_PID);
2487 nr_threads++;
2488 }
2489 total_forks++;
2490 hlist_del_init(&delayed.node);
2491 spin_unlock(¤t->sighand->siglock);
2492 syscall_tracepoint_update(p);
2493 write_unlock_irq(&tasklist_lock);
2494
2495 if (pidfile)
2496 fd_install(pidfd, pidfile);
2497
2498 proc_fork_connector(p);
2499 sched_post_fork(p);
2500 cgroup_post_fork(p, args);
2501 perf_event_fork(p);
2502
2503 trace_task_newtask(p, clone_flags);
2504 uprobe_copy_process(p, clone_flags);
2505
2506 copy_oom_score_adj(clone_flags, p);
2507
2508 return p;
2509
2510bad_fork_cancel_cgroup:
2511 sched_core_free(p);
2512 spin_unlock(¤t->sighand->siglock);
2513 write_unlock_irq(&tasklist_lock);
2514 cgroup_cancel_fork(p, args);
2515bad_fork_put_pidfd:
2516 if (clone_flags & CLONE_PIDFD) {
2517 fput(pidfile);
2518 put_unused_fd(pidfd);
2519 }
2520bad_fork_free_pid:
2521 if (pid != &init_struct_pid)
2522 free_pid(pid);
2523bad_fork_cleanup_thread:
2524 exit_thread(p);
2525bad_fork_cleanup_io:
2526 if (p->io_context)
2527 exit_io_context(p);
2528bad_fork_cleanup_namespaces:
2529 exit_task_namespaces(p);
2530bad_fork_cleanup_mm:
2531 if (p->mm) {
2532 mm_clear_owner(p->mm, p);
2533 mmput(p->mm);
2534 }
2535bad_fork_cleanup_signal:
2536 if (!(clone_flags & CLONE_THREAD))
2537 free_signal_struct(p->signal);
2538bad_fork_cleanup_sighand:
2539 __cleanup_sighand(p->sighand);
2540bad_fork_cleanup_fs:
2541 exit_fs(p); /* blocking */
2542bad_fork_cleanup_files:
2543 exit_files(p); /* blocking */
2544bad_fork_cleanup_semundo:
2545 exit_sem(p);
2546bad_fork_cleanup_security:
2547 security_task_free(p);
2548bad_fork_cleanup_audit:
2549 audit_free(p);
2550bad_fork_cleanup_perf:
2551 perf_event_free_task(p);
2552bad_fork_cleanup_policy:
2553 lockdep_free_task(p);
2554#ifdef CONFIG_NUMA
2555 mpol_put(p->mempolicy);
2556#endif
2557bad_fork_cleanup_delayacct:
2558 delayacct_tsk_free(p);
2559bad_fork_cleanup_count:
2560 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2561 exit_creds(p);
2562bad_fork_free:
2563 WRITE_ONCE(p->__state, TASK_DEAD);
2564 exit_task_stack_account(p);
2565 put_task_stack(p);
2566 delayed_free_task(p);
2567fork_out:
2568 spin_lock_irq(¤t->sighand->siglock);
2569 hlist_del_init(&delayed.node);
2570 spin_unlock_irq(¤t->sighand->siglock);
2571 return ERR_PTR(retval);
2572}
2573
2574static inline void init_idle_pids(struct task_struct *idle)
2575{
2576 enum pid_type type;
2577
2578 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2579 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2580 init_task_pid(idle, type, &init_struct_pid);
2581 }
2582}
2583
2584static int idle_dummy(void *dummy)
2585{
2586 /* This function is never called */
2587 return 0;
2588}
2589
2590struct task_struct * __init fork_idle(int cpu)
2591{
2592 struct task_struct *task;
2593 struct kernel_clone_args args = {
2594 .flags = CLONE_VM,
2595 .fn = &idle_dummy,
2596 .fn_arg = NULL,
2597 .kthread = 1,
2598 .idle = 1,
2599 };
2600
2601 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2602 if (!IS_ERR(task)) {
2603 init_idle_pids(task);
2604 init_idle(task, cpu);
2605 }
2606
2607 return task;
2608}
2609
2610/*
2611 * This is like kernel_clone(), but shaved down and tailored to just
2612 * creating io_uring workers. It returns a created task, or an error pointer.
2613 * The returned task is inactive, and the caller must fire it up through
2614 * wake_up_new_task(p). All signals are blocked in the created task.
2615 */
2616struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2617{
2618 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2619 CLONE_IO;
2620 struct kernel_clone_args args = {
2621 .flags = ((lower_32_bits(flags) | CLONE_VM |
2622 CLONE_UNTRACED) & ~CSIGNAL),
2623 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2624 .fn = fn,
2625 .fn_arg = arg,
2626 .io_thread = 1,
2627 };
2628
2629 return copy_process(NULL, 0, node, &args);
2630}
2631
2632/*
2633 * Ok, this is the main fork-routine.
2634 *
2635 * It copies the process, and if successful kick-starts
2636 * it and waits for it to finish using the VM if required.
2637 *
2638 * args->exit_signal is expected to be checked for sanity by the caller.
2639 */
2640pid_t kernel_clone(struct kernel_clone_args *args)
2641{
2642 u64 clone_flags = args->flags;
2643 struct completion vfork;
2644 struct pid *pid;
2645 struct task_struct *p;
2646 int trace = 0;
2647 pid_t nr;
2648
2649 /*
2650 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2651 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2652 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2653 * field in struct clone_args and it still doesn't make sense to have
2654 * them both point at the same memory location. Performing this check
2655 * here has the advantage that we don't need to have a separate helper
2656 * to check for legacy clone().
2657 */
2658 if ((args->flags & CLONE_PIDFD) &&
2659 (args->flags & CLONE_PARENT_SETTID) &&
2660 (args->pidfd == args->parent_tid))
2661 return -EINVAL;
2662
2663 /*
2664 * Determine whether and which event to report to ptracer. When
2665 * called from kernel_thread or CLONE_UNTRACED is explicitly
2666 * requested, no event is reported; otherwise, report if the event
2667 * for the type of forking is enabled.
2668 */
2669 if (!(clone_flags & CLONE_UNTRACED)) {
2670 if (clone_flags & CLONE_VFORK)
2671 trace = PTRACE_EVENT_VFORK;
2672 else if (args->exit_signal != SIGCHLD)
2673 trace = PTRACE_EVENT_CLONE;
2674 else
2675 trace = PTRACE_EVENT_FORK;
2676
2677 if (likely(!ptrace_event_enabled(current, trace)))
2678 trace = 0;
2679 }
2680
2681 p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2682 add_latent_entropy();
2683
2684 if (IS_ERR(p))
2685 return PTR_ERR(p);
2686
2687 /*
2688 * Do this prior waking up the new thread - the thread pointer
2689 * might get invalid after that point, if the thread exits quickly.
2690 */
2691 trace_sched_process_fork(current, p);
2692
2693 pid = get_task_pid(p, PIDTYPE_PID);
2694 nr = pid_vnr(pid);
2695
2696 if (clone_flags & CLONE_PARENT_SETTID)
2697 put_user(nr, args->parent_tid);
2698
2699 if (clone_flags & CLONE_VFORK) {
2700 p->vfork_done = &vfork;
2701 init_completion(&vfork);
2702 get_task_struct(p);
2703 }
2704
2705 if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) {
2706 /* lock the task to synchronize with memcg migration */
2707 task_lock(p);
2708 lru_gen_add_mm(p->mm);
2709 task_unlock(p);
2710 }
2711
2712 wake_up_new_task(p);
2713
2714 /* forking complete and child started to run, tell ptracer */
2715 if (unlikely(trace))
2716 ptrace_event_pid(trace, pid);
2717
2718 if (clone_flags & CLONE_VFORK) {
2719 if (!wait_for_vfork_done(p, &vfork))
2720 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2721 }
2722
2723 put_pid(pid);
2724 return nr;
2725}
2726
2727/*
2728 * Create a kernel thread.
2729 */
2730pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2731{
2732 struct kernel_clone_args args = {
2733 .flags = ((lower_32_bits(flags) | CLONE_VM |
2734 CLONE_UNTRACED) & ~CSIGNAL),
2735 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2736 .fn = fn,
2737 .fn_arg = arg,
2738 .kthread = 1,
2739 };
2740
2741 return kernel_clone(&args);
2742}
2743
2744/*
2745 * Create a user mode thread.
2746 */
2747pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
2748{
2749 struct kernel_clone_args args = {
2750 .flags = ((lower_32_bits(flags) | CLONE_VM |
2751 CLONE_UNTRACED) & ~CSIGNAL),
2752 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2753 .fn = fn,
2754 .fn_arg = arg,
2755 };
2756
2757 return kernel_clone(&args);
2758}
2759
2760#ifdef __ARCH_WANT_SYS_FORK
2761SYSCALL_DEFINE0(fork)
2762{
2763#ifdef CONFIG_MMU
2764 struct kernel_clone_args args = {
2765 .exit_signal = SIGCHLD,
2766 };
2767
2768 return kernel_clone(&args);
2769#else
2770 /* can not support in nommu mode */
2771 return -EINVAL;
2772#endif
2773}
2774#endif
2775
2776#ifdef __ARCH_WANT_SYS_VFORK
2777SYSCALL_DEFINE0(vfork)
2778{
2779 struct kernel_clone_args args = {
2780 .flags = CLONE_VFORK | CLONE_VM,
2781 .exit_signal = SIGCHLD,
2782 };
2783
2784 return kernel_clone(&args);
2785}
2786#endif
2787
2788#ifdef __ARCH_WANT_SYS_CLONE
2789#ifdef CONFIG_CLONE_BACKWARDS
2790SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2791 int __user *, parent_tidptr,
2792 unsigned long, tls,
2793 int __user *, child_tidptr)
2794#elif defined(CONFIG_CLONE_BACKWARDS2)
2795SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2796 int __user *, parent_tidptr,
2797 int __user *, child_tidptr,
2798 unsigned long, tls)
2799#elif defined(CONFIG_CLONE_BACKWARDS3)
2800SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2801 int, stack_size,
2802 int __user *, parent_tidptr,
2803 int __user *, child_tidptr,
2804 unsigned long, tls)
2805#else
2806SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2807 int __user *, parent_tidptr,
2808 int __user *, child_tidptr,
2809 unsigned long, tls)
2810#endif
2811{
2812 struct kernel_clone_args args = {
2813 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2814 .pidfd = parent_tidptr,
2815 .child_tid = child_tidptr,
2816 .parent_tid = parent_tidptr,
2817 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2818 .stack = newsp,
2819 .tls = tls,
2820 };
2821
2822 return kernel_clone(&args);
2823}
2824#endif
2825
2826#ifdef __ARCH_WANT_SYS_CLONE3
2827
2828noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2829 struct clone_args __user *uargs,
2830 size_t usize)
2831{
2832 int err;
2833 struct clone_args args;
2834 pid_t *kset_tid = kargs->set_tid;
2835
2836 BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2837 CLONE_ARGS_SIZE_VER0);
2838 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2839 CLONE_ARGS_SIZE_VER1);
2840 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2841 CLONE_ARGS_SIZE_VER2);
2842 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2843
2844 if (unlikely(usize > PAGE_SIZE))
2845 return -E2BIG;
2846 if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2847 return -EINVAL;
2848
2849 err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2850 if (err)
2851 return err;
2852
2853 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2854 return -EINVAL;
2855
2856 if (unlikely(!args.set_tid && args.set_tid_size > 0))
2857 return -EINVAL;
2858
2859 if (unlikely(args.set_tid && args.set_tid_size == 0))
2860 return -EINVAL;
2861
2862 /*
2863 * Verify that higher 32bits of exit_signal are unset and that
2864 * it is a valid signal
2865 */
2866 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2867 !valid_signal(args.exit_signal)))
2868 return -EINVAL;
2869
2870 if ((args.flags & CLONE_INTO_CGROUP) &&
2871 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2872 return -EINVAL;
2873
2874 *kargs = (struct kernel_clone_args){
2875 .flags = args.flags,
2876 .pidfd = u64_to_user_ptr(args.pidfd),
2877 .child_tid = u64_to_user_ptr(args.child_tid),
2878 .parent_tid = u64_to_user_ptr(args.parent_tid),
2879 .exit_signal = args.exit_signal,
2880 .stack = args.stack,
2881 .stack_size = args.stack_size,
2882 .tls = args.tls,
2883 .set_tid_size = args.set_tid_size,
2884 .cgroup = args.cgroup,
2885 };
2886
2887 if (args.set_tid &&
2888 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
2889 (kargs->set_tid_size * sizeof(pid_t))))
2890 return -EFAULT;
2891
2892 kargs->set_tid = kset_tid;
2893
2894 return 0;
2895}
2896
2897/**
2898 * clone3_stack_valid - check and prepare stack
2899 * @kargs: kernel clone args
2900 *
2901 * Verify that the stack arguments userspace gave us are sane.
2902 * In addition, set the stack direction for userspace since it's easy for us to
2903 * determine.
2904 */
2905static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
2906{
2907 if (kargs->stack == 0) {
2908 if (kargs->stack_size > 0)
2909 return false;
2910 } else {
2911 if (kargs->stack_size == 0)
2912 return false;
2913
2914 if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
2915 return false;
2916
2917#if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2918 kargs->stack += kargs->stack_size;
2919#endif
2920 }
2921
2922 return true;
2923}
2924
2925static bool clone3_args_valid(struct kernel_clone_args *kargs)
2926{
2927 /* Verify that no unknown flags are passed along. */
2928 if (kargs->flags &
2929 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
2930 return false;
2931
2932 /*
2933 * - make the CLONE_DETACHED bit reusable for clone3
2934 * - make the CSIGNAL bits reusable for clone3
2935 */
2936 if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
2937 return false;
2938
2939 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
2940 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
2941 return false;
2942
2943 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
2944 kargs->exit_signal)
2945 return false;
2946
2947 if (!clone3_stack_valid(kargs))
2948 return false;
2949
2950 return true;
2951}
2952
2953/**
2954 * clone3 - create a new process with specific properties
2955 * @uargs: argument structure
2956 * @size: size of @uargs
2957 *
2958 * clone3() is the extensible successor to clone()/clone2().
2959 * It takes a struct as argument that is versioned by its size.
2960 *
2961 * Return: On success, a positive PID for the child process.
2962 * On error, a negative errno number.
2963 */
2964SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
2965{
2966 int err;
2967
2968 struct kernel_clone_args kargs;
2969 pid_t set_tid[MAX_PID_NS_LEVEL];
2970
2971 kargs.set_tid = set_tid;
2972
2973 err = copy_clone_args_from_user(&kargs, uargs, size);
2974 if (err)
2975 return err;
2976
2977 if (!clone3_args_valid(&kargs))
2978 return -EINVAL;
2979
2980 return kernel_clone(&kargs);
2981}
2982#endif
2983
2984void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2985{
2986 struct task_struct *leader, *parent, *child;
2987 int res;
2988
2989 read_lock(&tasklist_lock);
2990 leader = top = top->group_leader;
2991down:
2992 for_each_thread(leader, parent) {
2993 list_for_each_entry(child, &parent->children, sibling) {
2994 res = visitor(child, data);
2995 if (res) {
2996 if (res < 0)
2997 goto out;
2998 leader = child;
2999 goto down;
3000 }
3001up:
3002 ;
3003 }
3004 }
3005
3006 if (leader != top) {
3007 child = leader;
3008 parent = child->real_parent;
3009 leader = parent->group_leader;
3010 goto up;
3011 }
3012out:
3013 read_unlock(&tasklist_lock);
3014}
3015
3016#ifndef ARCH_MIN_MMSTRUCT_ALIGN
3017#define ARCH_MIN_MMSTRUCT_ALIGN 0
3018#endif
3019
3020static void sighand_ctor(void *data)
3021{
3022 struct sighand_struct *sighand = data;
3023
3024 spin_lock_init(&sighand->siglock);
3025 init_waitqueue_head(&sighand->signalfd_wqh);
3026}
3027
3028void __init mm_cache_init(void)
3029{
3030 unsigned int mm_size;
3031
3032 /*
3033 * The mm_cpumask is located at the end of mm_struct, and is
3034 * dynamically sized based on the maximum CPU number this system
3035 * can have, taking hotplug into account (nr_cpu_ids).
3036 */
3037 mm_size = sizeof(struct mm_struct) + cpumask_size();
3038
3039 mm_cachep = kmem_cache_create_usercopy("mm_struct",
3040 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
3041 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3042 offsetof(struct mm_struct, saved_auxv),
3043 sizeof_field(struct mm_struct, saved_auxv),
3044 NULL);
3045}
3046
3047void __init proc_caches_init(void)
3048{
3049 sighand_cachep = kmem_cache_create("sighand_cache",
3050 sizeof(struct sighand_struct), 0,
3051 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
3052 SLAB_ACCOUNT, sighand_ctor);
3053 signal_cachep = kmem_cache_create("signal_cache",
3054 sizeof(struct signal_struct), 0,
3055 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3056 NULL);
3057 files_cachep = kmem_cache_create("files_cache",
3058 sizeof(struct files_struct), 0,
3059 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3060 NULL);
3061 fs_cachep = kmem_cache_create("fs_cache",
3062 sizeof(struct fs_struct), 0,
3063 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3064 NULL);
3065
3066 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
3067 mmap_init();
3068 nsproxy_cache_init();
3069}
3070
3071/*
3072 * Check constraints on flags passed to the unshare system call.
3073 */
3074static int check_unshare_flags(unsigned long unshare_flags)
3075{
3076 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3077 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3078 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3079 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3080 CLONE_NEWTIME))
3081 return -EINVAL;
3082 /*
3083 * Not implemented, but pretend it works if there is nothing
3084 * to unshare. Note that unsharing the address space or the
3085 * signal handlers also need to unshare the signal queues (aka
3086 * CLONE_THREAD).
3087 */
3088 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3089 if (!thread_group_empty(current))
3090 return -EINVAL;
3091 }
3092 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3093 if (refcount_read(¤t->sighand->count) > 1)
3094 return -EINVAL;
3095 }
3096 if (unshare_flags & CLONE_VM) {
3097 if (!current_is_single_threaded())
3098 return -EINVAL;
3099 }
3100
3101 return 0;
3102}
3103
3104/*
3105 * Unshare the filesystem structure if it is being shared
3106 */
3107static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3108{
3109 struct fs_struct *fs = current->fs;
3110
3111 if (!(unshare_flags & CLONE_FS) || !fs)
3112 return 0;
3113
3114 /* don't need lock here; in the worst case we'll do useless copy */
3115 if (fs->users == 1)
3116 return 0;
3117
3118 *new_fsp = copy_fs_struct(fs);
3119 if (!*new_fsp)
3120 return -ENOMEM;
3121
3122 return 0;
3123}
3124
3125/*
3126 * Unshare file descriptor table if it is being shared
3127 */
3128int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3129 struct files_struct **new_fdp)
3130{
3131 struct files_struct *fd = current->files;
3132 int error = 0;
3133
3134 if ((unshare_flags & CLONE_FILES) &&
3135 (fd && atomic_read(&fd->count) > 1)) {
3136 *new_fdp = dup_fd(fd, max_fds, &error);
3137 if (!*new_fdp)
3138 return error;
3139 }
3140
3141 return 0;
3142}
3143
3144/*
3145 * unshare allows a process to 'unshare' part of the process
3146 * context which was originally shared using clone. copy_*
3147 * functions used by kernel_clone() cannot be used here directly
3148 * because they modify an inactive task_struct that is being
3149 * constructed. Here we are modifying the current, active,
3150 * task_struct.
3151 */
3152int ksys_unshare(unsigned long unshare_flags)
3153{
3154 struct fs_struct *fs, *new_fs = NULL;
3155 struct files_struct *new_fd = NULL;
3156 struct cred *new_cred = NULL;
3157 struct nsproxy *new_nsproxy = NULL;
3158 int do_sysvsem = 0;
3159 int err;
3160
3161 /*
3162 * If unsharing a user namespace must also unshare the thread group
3163 * and unshare the filesystem root and working directories.
3164 */
3165 if (unshare_flags & CLONE_NEWUSER)
3166 unshare_flags |= CLONE_THREAD | CLONE_FS;
3167 /*
3168 * If unsharing vm, must also unshare signal handlers.
3169 */
3170 if (unshare_flags & CLONE_VM)
3171 unshare_flags |= CLONE_SIGHAND;
3172 /*
3173 * If unsharing a signal handlers, must also unshare the signal queues.
3174 */
3175 if (unshare_flags & CLONE_SIGHAND)
3176 unshare_flags |= CLONE_THREAD;
3177 /*
3178 * If unsharing namespace, must also unshare filesystem information.
3179 */
3180 if (unshare_flags & CLONE_NEWNS)
3181 unshare_flags |= CLONE_FS;
3182
3183 err = check_unshare_flags(unshare_flags);
3184 if (err)
3185 goto bad_unshare_out;
3186 /*
3187 * CLONE_NEWIPC must also detach from the undolist: after switching
3188 * to a new ipc namespace, the semaphore arrays from the old
3189 * namespace are unreachable.
3190 */
3191 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3192 do_sysvsem = 1;
3193 err = unshare_fs(unshare_flags, &new_fs);
3194 if (err)
3195 goto bad_unshare_out;
3196 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3197 if (err)
3198 goto bad_unshare_cleanup_fs;
3199 err = unshare_userns(unshare_flags, &new_cred);
3200 if (err)
3201 goto bad_unshare_cleanup_fd;
3202 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3203 new_cred, new_fs);
3204 if (err)
3205 goto bad_unshare_cleanup_cred;
3206
3207 if (new_cred) {
3208 err = set_cred_ucounts(new_cred);
3209 if (err)
3210 goto bad_unshare_cleanup_cred;
3211 }
3212
3213 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3214 if (do_sysvsem) {
3215 /*
3216 * CLONE_SYSVSEM is equivalent to sys_exit().
3217 */
3218 exit_sem(current);
3219 }
3220 if (unshare_flags & CLONE_NEWIPC) {
3221 /* Orphan segments in old ns (see sem above). */
3222 exit_shm(current);
3223 shm_init_task(current);
3224 }
3225
3226 if (new_nsproxy)
3227 switch_task_namespaces(current, new_nsproxy);
3228
3229 task_lock(current);
3230
3231 if (new_fs) {
3232 fs = current->fs;
3233 spin_lock(&fs->lock);
3234 current->fs = new_fs;
3235 if (--fs->users)
3236 new_fs = NULL;
3237 else
3238 new_fs = fs;
3239 spin_unlock(&fs->lock);
3240 }
3241
3242 if (new_fd)
3243 swap(current->files, new_fd);
3244
3245 task_unlock(current);
3246
3247 if (new_cred) {
3248 /* Install the new user namespace */
3249 commit_creds(new_cred);
3250 new_cred = NULL;
3251 }
3252 }
3253
3254 perf_event_namespaces(current);
3255
3256bad_unshare_cleanup_cred:
3257 if (new_cred)
3258 put_cred(new_cred);
3259bad_unshare_cleanup_fd:
3260 if (new_fd)
3261 put_files_struct(new_fd);
3262
3263bad_unshare_cleanup_fs:
3264 if (new_fs)
3265 free_fs_struct(new_fs);
3266
3267bad_unshare_out:
3268 return err;
3269}
3270
3271SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3272{
3273 return ksys_unshare(unshare_flags);
3274}
3275
3276/*
3277 * Helper to unshare the files of the current task.
3278 * We don't want to expose copy_files internals to
3279 * the exec layer of the kernel.
3280 */
3281
3282int unshare_files(void)
3283{
3284 struct task_struct *task = current;
3285 struct files_struct *old, *copy = NULL;
3286 int error;
3287
3288 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3289 if (error || !copy)
3290 return error;
3291
3292 old = task->files;
3293 task_lock(task);
3294 task->files = copy;
3295 task_unlock(task);
3296 put_files_struct(old);
3297 return 0;
3298}
3299
3300int sysctl_max_threads(struct ctl_table *table, int write,
3301 void *buffer, size_t *lenp, loff_t *ppos)
3302{
3303 struct ctl_table t;
3304 int ret;
3305 int threads = max_threads;
3306 int min = 1;
3307 int max = MAX_THREADS;
3308
3309 t = *table;
3310 t.data = &threads;
3311 t.extra1 = &min;
3312 t.extra2 = &max;
3313
3314 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3315 if (ret || !write)
3316 return ret;
3317
3318 max_threads = threads;
3319
3320 return 0;
3321}
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/init.h>
16#include <linux/unistd.h>
17#include <linux/module.h>
18#include <linux/vmalloc.h>
19#include <linux/completion.h>
20#include <linux/personality.h>
21#include <linux/mempolicy.h>
22#include <linux/sem.h>
23#include <linux/file.h>
24#include <linux/fdtable.h>
25#include <linux/iocontext.h>
26#include <linux/key.h>
27#include <linux/binfmts.h>
28#include <linux/mman.h>
29#include <linux/mmu_notifier.h>
30#include <linux/fs.h>
31#include <linux/nsproxy.h>
32#include <linux/capability.h>
33#include <linux/cpu.h>
34#include <linux/cgroup.h>
35#include <linux/security.h>
36#include <linux/hugetlb.h>
37#include <linux/swap.h>
38#include <linux/syscalls.h>
39#include <linux/jiffies.h>
40#include <linux/futex.h>
41#include <linux/compat.h>
42#include <linux/kthread.h>
43#include <linux/task_io_accounting_ops.h>
44#include <linux/rcupdate.h>
45#include <linux/ptrace.h>
46#include <linux/mount.h>
47#include <linux/audit.h>
48#include <linux/memcontrol.h>
49#include <linux/ftrace.h>
50#include <linux/profile.h>
51#include <linux/rmap.h>
52#include <linux/ksm.h>
53#include <linux/acct.h>
54#include <linux/tsacct_kern.h>
55#include <linux/cn_proc.h>
56#include <linux/freezer.h>
57#include <linux/delayacct.h>
58#include <linux/taskstats_kern.h>
59#include <linux/random.h>
60#include <linux/tty.h>
61#include <linux/blkdev.h>
62#include <linux/fs_struct.h>
63#include <linux/magic.h>
64#include <linux/perf_event.h>
65#include <linux/posix-timers.h>
66#include <linux/user-return-notifier.h>
67#include <linux/oom.h>
68#include <linux/khugepaged.h>
69
70#include <asm/pgtable.h>
71#include <asm/pgalloc.h>
72#include <asm/uaccess.h>
73#include <asm/mmu_context.h>
74#include <asm/cacheflush.h>
75#include <asm/tlbflush.h>
76
77#include <trace/events/sched.h>
78
79/*
80 * Protected counters by write_lock_irq(&tasklist_lock)
81 */
82unsigned long total_forks; /* Handle normal Linux uptimes. */
83int nr_threads; /* The idle threads do not count.. */
84
85int max_threads; /* tunable limit on nr_threads */
86
87DEFINE_PER_CPU(unsigned long, process_counts) = 0;
88
89__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
90
91#ifdef CONFIG_PROVE_RCU
92int lockdep_tasklist_lock_is_held(void)
93{
94 return lockdep_is_held(&tasklist_lock);
95}
96EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
97#endif /* #ifdef CONFIG_PROVE_RCU */
98
99int nr_processes(void)
100{
101 int cpu;
102 int total = 0;
103
104 for_each_possible_cpu(cpu)
105 total += per_cpu(process_counts, cpu);
106
107 return total;
108}
109
110#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
111# define alloc_task_struct_node(node) \
112 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
113# define free_task_struct(tsk) \
114 kmem_cache_free(task_struct_cachep, (tsk))
115static struct kmem_cache *task_struct_cachep;
116#endif
117
118#ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
119static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
120 int node)
121{
122#ifdef CONFIG_DEBUG_STACK_USAGE
123 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
124#else
125 gfp_t mask = GFP_KERNEL;
126#endif
127 struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER);
128
129 return page ? page_address(page) : NULL;
130}
131
132static inline void free_thread_info(struct thread_info *ti)
133{
134 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
135}
136#endif
137
138/* SLAB cache for signal_struct structures (tsk->signal) */
139static struct kmem_cache *signal_cachep;
140
141/* SLAB cache for sighand_struct structures (tsk->sighand) */
142struct kmem_cache *sighand_cachep;
143
144/* SLAB cache for files_struct structures (tsk->files) */
145struct kmem_cache *files_cachep;
146
147/* SLAB cache for fs_struct structures (tsk->fs) */
148struct kmem_cache *fs_cachep;
149
150/* SLAB cache for vm_area_struct structures */
151struct kmem_cache *vm_area_cachep;
152
153/* SLAB cache for mm_struct structures (tsk->mm) */
154static struct kmem_cache *mm_cachep;
155
156static void account_kernel_stack(struct thread_info *ti, int account)
157{
158 struct zone *zone = page_zone(virt_to_page(ti));
159
160 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
161}
162
163void free_task(struct task_struct *tsk)
164{
165 prop_local_destroy_single(&tsk->dirties);
166 account_kernel_stack(tsk->stack, -1);
167 free_thread_info(tsk->stack);
168 rt_mutex_debug_task_free(tsk);
169 ftrace_graph_exit_task(tsk);
170 free_task_struct(tsk);
171}
172EXPORT_SYMBOL(free_task);
173
174static inline void free_signal_struct(struct signal_struct *sig)
175{
176 taskstats_tgid_free(sig);
177 sched_autogroup_exit(sig);
178 kmem_cache_free(signal_cachep, sig);
179}
180
181static inline void put_signal_struct(struct signal_struct *sig)
182{
183 if (atomic_dec_and_test(&sig->sigcnt))
184 free_signal_struct(sig);
185}
186
187void __put_task_struct(struct task_struct *tsk)
188{
189 WARN_ON(!tsk->exit_state);
190 WARN_ON(atomic_read(&tsk->usage));
191 WARN_ON(tsk == current);
192
193 exit_creds(tsk);
194 delayacct_tsk_free(tsk);
195 put_signal_struct(tsk->signal);
196
197 if (!profile_handoff_task(tsk))
198 free_task(tsk);
199}
200EXPORT_SYMBOL_GPL(__put_task_struct);
201
202/*
203 * macro override instead of weak attribute alias, to workaround
204 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
205 */
206#ifndef arch_task_cache_init
207#define arch_task_cache_init()
208#endif
209
210void __init fork_init(unsigned long mempages)
211{
212#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
213#ifndef ARCH_MIN_TASKALIGN
214#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
215#endif
216 /* create a slab on which task_structs can be allocated */
217 task_struct_cachep =
218 kmem_cache_create("task_struct", sizeof(struct task_struct),
219 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
220#endif
221
222 /* do the arch specific task caches init */
223 arch_task_cache_init();
224
225 /*
226 * The default maximum number of threads is set to a safe
227 * value: the thread structures can take up at most half
228 * of memory.
229 */
230 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
231
232 /*
233 * we need to allow at least 20 threads to boot a system
234 */
235 if (max_threads < 20)
236 max_threads = 20;
237
238 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
239 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
240 init_task.signal->rlim[RLIMIT_SIGPENDING] =
241 init_task.signal->rlim[RLIMIT_NPROC];
242}
243
244int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
245 struct task_struct *src)
246{
247 *dst = *src;
248 return 0;
249}
250
251static struct task_struct *dup_task_struct(struct task_struct *orig)
252{
253 struct task_struct *tsk;
254 struct thread_info *ti;
255 unsigned long *stackend;
256 int node = tsk_fork_get_node(orig);
257 int err;
258
259 prepare_to_copy(orig);
260
261 tsk = alloc_task_struct_node(node);
262 if (!tsk)
263 return NULL;
264
265 ti = alloc_thread_info_node(tsk, node);
266 if (!ti) {
267 free_task_struct(tsk);
268 return NULL;
269 }
270
271 err = arch_dup_task_struct(tsk, orig);
272 if (err)
273 goto out;
274
275 tsk->stack = ti;
276
277 err = prop_local_init_single(&tsk->dirties);
278 if (err)
279 goto out;
280
281 setup_thread_stack(tsk, orig);
282 clear_user_return_notifier(tsk);
283 clear_tsk_need_resched(tsk);
284 stackend = end_of_stack(tsk);
285 *stackend = STACK_END_MAGIC; /* for overflow detection */
286
287#ifdef CONFIG_CC_STACKPROTECTOR
288 tsk->stack_canary = get_random_int();
289#endif
290
291 /*
292 * One for us, one for whoever does the "release_task()" (usually
293 * parent)
294 */
295 atomic_set(&tsk->usage, 2);
296#ifdef CONFIG_BLK_DEV_IO_TRACE
297 tsk->btrace_seq = 0;
298#endif
299 tsk->splice_pipe = NULL;
300
301 account_kernel_stack(ti, 1);
302
303 return tsk;
304
305out:
306 free_thread_info(ti);
307 free_task_struct(tsk);
308 return NULL;
309}
310
311#ifdef CONFIG_MMU
312static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
313{
314 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
315 struct rb_node **rb_link, *rb_parent;
316 int retval;
317 unsigned long charge;
318 struct mempolicy *pol;
319
320 down_write(&oldmm->mmap_sem);
321 flush_cache_dup_mm(oldmm);
322 /*
323 * Not linked in yet - no deadlock potential:
324 */
325 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
326
327 mm->locked_vm = 0;
328 mm->mmap = NULL;
329 mm->mmap_cache = NULL;
330 mm->free_area_cache = oldmm->mmap_base;
331 mm->cached_hole_size = ~0UL;
332 mm->map_count = 0;
333 cpumask_clear(mm_cpumask(mm));
334 mm->mm_rb = RB_ROOT;
335 rb_link = &mm->mm_rb.rb_node;
336 rb_parent = NULL;
337 pprev = &mm->mmap;
338 retval = ksm_fork(mm, oldmm);
339 if (retval)
340 goto out;
341 retval = khugepaged_fork(mm, oldmm);
342 if (retval)
343 goto out;
344
345 prev = NULL;
346 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
347 struct file *file;
348
349 if (mpnt->vm_flags & VM_DONTCOPY) {
350 long pages = vma_pages(mpnt);
351 mm->total_vm -= pages;
352 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
353 -pages);
354 continue;
355 }
356 charge = 0;
357 if (mpnt->vm_flags & VM_ACCOUNT) {
358 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
359 if (security_vm_enough_memory(len))
360 goto fail_nomem;
361 charge = len;
362 }
363 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
364 if (!tmp)
365 goto fail_nomem;
366 *tmp = *mpnt;
367 INIT_LIST_HEAD(&tmp->anon_vma_chain);
368 pol = mpol_dup(vma_policy(mpnt));
369 retval = PTR_ERR(pol);
370 if (IS_ERR(pol))
371 goto fail_nomem_policy;
372 vma_set_policy(tmp, pol);
373 tmp->vm_mm = mm;
374 if (anon_vma_fork(tmp, mpnt))
375 goto fail_nomem_anon_vma_fork;
376 tmp->vm_flags &= ~VM_LOCKED;
377 tmp->vm_next = tmp->vm_prev = NULL;
378 file = tmp->vm_file;
379 if (file) {
380 struct inode *inode = file->f_path.dentry->d_inode;
381 struct address_space *mapping = file->f_mapping;
382
383 get_file(file);
384 if (tmp->vm_flags & VM_DENYWRITE)
385 atomic_dec(&inode->i_writecount);
386 mutex_lock(&mapping->i_mmap_mutex);
387 if (tmp->vm_flags & VM_SHARED)
388 mapping->i_mmap_writable++;
389 flush_dcache_mmap_lock(mapping);
390 /* insert tmp into the share list, just after mpnt */
391 vma_prio_tree_add(tmp, mpnt);
392 flush_dcache_mmap_unlock(mapping);
393 mutex_unlock(&mapping->i_mmap_mutex);
394 }
395
396 /*
397 * Clear hugetlb-related page reserves for children. This only
398 * affects MAP_PRIVATE mappings. Faults generated by the child
399 * are not guaranteed to succeed, even if read-only
400 */
401 if (is_vm_hugetlb_page(tmp))
402 reset_vma_resv_huge_pages(tmp);
403
404 /*
405 * Link in the new vma and copy the page table entries.
406 */
407 *pprev = tmp;
408 pprev = &tmp->vm_next;
409 tmp->vm_prev = prev;
410 prev = tmp;
411
412 __vma_link_rb(mm, tmp, rb_link, rb_parent);
413 rb_link = &tmp->vm_rb.rb_right;
414 rb_parent = &tmp->vm_rb;
415
416 mm->map_count++;
417 retval = copy_page_range(mm, oldmm, mpnt);
418
419 if (tmp->vm_ops && tmp->vm_ops->open)
420 tmp->vm_ops->open(tmp);
421
422 if (retval)
423 goto out;
424 }
425 /* a new mm has just been created */
426 arch_dup_mmap(oldmm, mm);
427 retval = 0;
428out:
429 up_write(&mm->mmap_sem);
430 flush_tlb_mm(oldmm);
431 up_write(&oldmm->mmap_sem);
432 return retval;
433fail_nomem_anon_vma_fork:
434 mpol_put(pol);
435fail_nomem_policy:
436 kmem_cache_free(vm_area_cachep, tmp);
437fail_nomem:
438 retval = -ENOMEM;
439 vm_unacct_memory(charge);
440 goto out;
441}
442
443static inline int mm_alloc_pgd(struct mm_struct *mm)
444{
445 mm->pgd = pgd_alloc(mm);
446 if (unlikely(!mm->pgd))
447 return -ENOMEM;
448 return 0;
449}
450
451static inline void mm_free_pgd(struct mm_struct *mm)
452{
453 pgd_free(mm, mm->pgd);
454}
455#else
456#define dup_mmap(mm, oldmm) (0)
457#define mm_alloc_pgd(mm) (0)
458#define mm_free_pgd(mm)
459#endif /* CONFIG_MMU */
460
461__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
462
463#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
464#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
465
466static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
467
468static int __init coredump_filter_setup(char *s)
469{
470 default_dump_filter =
471 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
472 MMF_DUMP_FILTER_MASK;
473 return 1;
474}
475
476__setup("coredump_filter=", coredump_filter_setup);
477
478#include <linux/init_task.h>
479
480static void mm_init_aio(struct mm_struct *mm)
481{
482#ifdef CONFIG_AIO
483 spin_lock_init(&mm->ioctx_lock);
484 INIT_HLIST_HEAD(&mm->ioctx_list);
485#endif
486}
487
488static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
489{
490 atomic_set(&mm->mm_users, 1);
491 atomic_set(&mm->mm_count, 1);
492 init_rwsem(&mm->mmap_sem);
493 INIT_LIST_HEAD(&mm->mmlist);
494 mm->flags = (current->mm) ?
495 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
496 mm->core_state = NULL;
497 mm->nr_ptes = 0;
498 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
499 spin_lock_init(&mm->page_table_lock);
500 mm->free_area_cache = TASK_UNMAPPED_BASE;
501 mm->cached_hole_size = ~0UL;
502 mm_init_aio(mm);
503 mm_init_owner(mm, p);
504 atomic_set(&mm->oom_disable_count, 0);
505
506 if (likely(!mm_alloc_pgd(mm))) {
507 mm->def_flags = 0;
508 mmu_notifier_mm_init(mm);
509 return mm;
510 }
511
512 free_mm(mm);
513 return NULL;
514}
515
516/*
517 * Allocate and initialize an mm_struct.
518 */
519struct mm_struct *mm_alloc(void)
520{
521 struct mm_struct *mm;
522
523 mm = allocate_mm();
524 if (!mm)
525 return NULL;
526
527 memset(mm, 0, sizeof(*mm));
528 mm_init_cpumask(mm);
529 return mm_init(mm, current);
530}
531
532/*
533 * Called when the last reference to the mm
534 * is dropped: either by a lazy thread or by
535 * mmput. Free the page directory and the mm.
536 */
537void __mmdrop(struct mm_struct *mm)
538{
539 BUG_ON(mm == &init_mm);
540 mm_free_pgd(mm);
541 destroy_context(mm);
542 mmu_notifier_mm_destroy(mm);
543#ifdef CONFIG_TRANSPARENT_HUGEPAGE
544 VM_BUG_ON(mm->pmd_huge_pte);
545#endif
546 free_mm(mm);
547}
548EXPORT_SYMBOL_GPL(__mmdrop);
549
550/*
551 * Decrement the use count and release all resources for an mm.
552 */
553void mmput(struct mm_struct *mm)
554{
555 might_sleep();
556
557 if (atomic_dec_and_test(&mm->mm_users)) {
558 exit_aio(mm);
559 ksm_exit(mm);
560 khugepaged_exit(mm); /* must run before exit_mmap */
561 exit_mmap(mm);
562 set_mm_exe_file(mm, NULL);
563 if (!list_empty(&mm->mmlist)) {
564 spin_lock(&mmlist_lock);
565 list_del(&mm->mmlist);
566 spin_unlock(&mmlist_lock);
567 }
568 put_swap_token(mm);
569 if (mm->binfmt)
570 module_put(mm->binfmt->module);
571 mmdrop(mm);
572 }
573}
574EXPORT_SYMBOL_GPL(mmput);
575
576/*
577 * We added or removed a vma mapping the executable. The vmas are only mapped
578 * during exec and are not mapped with the mmap system call.
579 * Callers must hold down_write() on the mm's mmap_sem for these
580 */
581void added_exe_file_vma(struct mm_struct *mm)
582{
583 mm->num_exe_file_vmas++;
584}
585
586void removed_exe_file_vma(struct mm_struct *mm)
587{
588 mm->num_exe_file_vmas--;
589 if ((mm->num_exe_file_vmas == 0) && mm->exe_file) {
590 fput(mm->exe_file);
591 mm->exe_file = NULL;
592 }
593
594}
595
596void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
597{
598 if (new_exe_file)
599 get_file(new_exe_file);
600 if (mm->exe_file)
601 fput(mm->exe_file);
602 mm->exe_file = new_exe_file;
603 mm->num_exe_file_vmas = 0;
604}
605
606struct file *get_mm_exe_file(struct mm_struct *mm)
607{
608 struct file *exe_file;
609
610 /* We need mmap_sem to protect against races with removal of
611 * VM_EXECUTABLE vmas */
612 down_read(&mm->mmap_sem);
613 exe_file = mm->exe_file;
614 if (exe_file)
615 get_file(exe_file);
616 up_read(&mm->mmap_sem);
617 return exe_file;
618}
619
620static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
621{
622 /* It's safe to write the exe_file pointer without exe_file_lock because
623 * this is called during fork when the task is not yet in /proc */
624 newmm->exe_file = get_mm_exe_file(oldmm);
625}
626
627/**
628 * get_task_mm - acquire a reference to the task's mm
629 *
630 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
631 * this kernel workthread has transiently adopted a user mm with use_mm,
632 * to do its AIO) is not set and if so returns a reference to it, after
633 * bumping up the use count. User must release the mm via mmput()
634 * after use. Typically used by /proc and ptrace.
635 */
636struct mm_struct *get_task_mm(struct task_struct *task)
637{
638 struct mm_struct *mm;
639
640 task_lock(task);
641 mm = task->mm;
642 if (mm) {
643 if (task->flags & PF_KTHREAD)
644 mm = NULL;
645 else
646 atomic_inc(&mm->mm_users);
647 }
648 task_unlock(task);
649 return mm;
650}
651EXPORT_SYMBOL_GPL(get_task_mm);
652
653/* Please note the differences between mmput and mm_release.
654 * mmput is called whenever we stop holding onto a mm_struct,
655 * error success whatever.
656 *
657 * mm_release is called after a mm_struct has been removed
658 * from the current process.
659 *
660 * This difference is important for error handling, when we
661 * only half set up a mm_struct for a new process and need to restore
662 * the old one. Because we mmput the new mm_struct before
663 * restoring the old one. . .
664 * Eric Biederman 10 January 1998
665 */
666void mm_release(struct task_struct *tsk, struct mm_struct *mm)
667{
668 struct completion *vfork_done = tsk->vfork_done;
669
670 /* Get rid of any futexes when releasing the mm */
671#ifdef CONFIG_FUTEX
672 if (unlikely(tsk->robust_list)) {
673 exit_robust_list(tsk);
674 tsk->robust_list = NULL;
675 }
676#ifdef CONFIG_COMPAT
677 if (unlikely(tsk->compat_robust_list)) {
678 compat_exit_robust_list(tsk);
679 tsk->compat_robust_list = NULL;
680 }
681#endif
682 if (unlikely(!list_empty(&tsk->pi_state_list)))
683 exit_pi_state_list(tsk);
684#endif
685
686 /* Get rid of any cached register state */
687 deactivate_mm(tsk, mm);
688
689 /* notify parent sleeping on vfork() */
690 if (vfork_done) {
691 tsk->vfork_done = NULL;
692 complete(vfork_done);
693 }
694
695 /*
696 * If we're exiting normally, clear a user-space tid field if
697 * requested. We leave this alone when dying by signal, to leave
698 * the value intact in a core dump, and to save the unnecessary
699 * trouble otherwise. Userland only wants this done for a sys_exit.
700 */
701 if (tsk->clear_child_tid) {
702 if (!(tsk->flags & PF_SIGNALED) &&
703 atomic_read(&mm->mm_users) > 1) {
704 /*
705 * We don't check the error code - if userspace has
706 * not set up a proper pointer then tough luck.
707 */
708 put_user(0, tsk->clear_child_tid);
709 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
710 1, NULL, NULL, 0);
711 }
712 tsk->clear_child_tid = NULL;
713 }
714}
715
716/*
717 * Allocate a new mm structure and copy contents from the
718 * mm structure of the passed in task structure.
719 */
720struct mm_struct *dup_mm(struct task_struct *tsk)
721{
722 struct mm_struct *mm, *oldmm = current->mm;
723 int err;
724
725 if (!oldmm)
726 return NULL;
727
728 mm = allocate_mm();
729 if (!mm)
730 goto fail_nomem;
731
732 memcpy(mm, oldmm, sizeof(*mm));
733 mm_init_cpumask(mm);
734
735 /* Initializing for Swap token stuff */
736 mm->token_priority = 0;
737 mm->last_interval = 0;
738
739#ifdef CONFIG_TRANSPARENT_HUGEPAGE
740 mm->pmd_huge_pte = NULL;
741#endif
742
743 if (!mm_init(mm, tsk))
744 goto fail_nomem;
745
746 if (init_new_context(tsk, mm))
747 goto fail_nocontext;
748
749 dup_mm_exe_file(oldmm, mm);
750
751 err = dup_mmap(mm, oldmm);
752 if (err)
753 goto free_pt;
754
755 mm->hiwater_rss = get_mm_rss(mm);
756 mm->hiwater_vm = mm->total_vm;
757
758 if (mm->binfmt && !try_module_get(mm->binfmt->module))
759 goto free_pt;
760
761 return mm;
762
763free_pt:
764 /* don't put binfmt in mmput, we haven't got module yet */
765 mm->binfmt = NULL;
766 mmput(mm);
767
768fail_nomem:
769 return NULL;
770
771fail_nocontext:
772 /*
773 * If init_new_context() failed, we cannot use mmput() to free the mm
774 * because it calls destroy_context()
775 */
776 mm_free_pgd(mm);
777 free_mm(mm);
778 return NULL;
779}
780
781static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
782{
783 struct mm_struct *mm, *oldmm;
784 int retval;
785
786 tsk->min_flt = tsk->maj_flt = 0;
787 tsk->nvcsw = tsk->nivcsw = 0;
788#ifdef CONFIG_DETECT_HUNG_TASK
789 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
790#endif
791
792 tsk->mm = NULL;
793 tsk->active_mm = NULL;
794
795 /*
796 * Are we cloning a kernel thread?
797 *
798 * We need to steal a active VM for that..
799 */
800 oldmm = current->mm;
801 if (!oldmm)
802 return 0;
803
804 if (clone_flags & CLONE_VM) {
805 atomic_inc(&oldmm->mm_users);
806 mm = oldmm;
807 goto good_mm;
808 }
809
810 retval = -ENOMEM;
811 mm = dup_mm(tsk);
812 if (!mm)
813 goto fail_nomem;
814
815good_mm:
816 /* Initializing for Swap token stuff */
817 mm->token_priority = 0;
818 mm->last_interval = 0;
819 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
820 atomic_inc(&mm->oom_disable_count);
821
822 tsk->mm = mm;
823 tsk->active_mm = mm;
824 return 0;
825
826fail_nomem:
827 return retval;
828}
829
830static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
831{
832 struct fs_struct *fs = current->fs;
833 if (clone_flags & CLONE_FS) {
834 /* tsk->fs is already what we want */
835 spin_lock(&fs->lock);
836 if (fs->in_exec) {
837 spin_unlock(&fs->lock);
838 return -EAGAIN;
839 }
840 fs->users++;
841 spin_unlock(&fs->lock);
842 return 0;
843 }
844 tsk->fs = copy_fs_struct(fs);
845 if (!tsk->fs)
846 return -ENOMEM;
847 return 0;
848}
849
850static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
851{
852 struct files_struct *oldf, *newf;
853 int error = 0;
854
855 /*
856 * A background process may not have any files ...
857 */
858 oldf = current->files;
859 if (!oldf)
860 goto out;
861
862 if (clone_flags & CLONE_FILES) {
863 atomic_inc(&oldf->count);
864 goto out;
865 }
866
867 newf = dup_fd(oldf, &error);
868 if (!newf)
869 goto out;
870
871 tsk->files = newf;
872 error = 0;
873out:
874 return error;
875}
876
877static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
878{
879#ifdef CONFIG_BLOCK
880 struct io_context *ioc = current->io_context;
881
882 if (!ioc)
883 return 0;
884 /*
885 * Share io context with parent, if CLONE_IO is set
886 */
887 if (clone_flags & CLONE_IO) {
888 tsk->io_context = ioc_task_link(ioc);
889 if (unlikely(!tsk->io_context))
890 return -ENOMEM;
891 } else if (ioprio_valid(ioc->ioprio)) {
892 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
893 if (unlikely(!tsk->io_context))
894 return -ENOMEM;
895
896 tsk->io_context->ioprio = ioc->ioprio;
897 }
898#endif
899 return 0;
900}
901
902static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
903{
904 struct sighand_struct *sig;
905
906 if (clone_flags & CLONE_SIGHAND) {
907 atomic_inc(¤t->sighand->count);
908 return 0;
909 }
910 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
911 rcu_assign_pointer(tsk->sighand, sig);
912 if (!sig)
913 return -ENOMEM;
914 atomic_set(&sig->count, 1);
915 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
916 return 0;
917}
918
919void __cleanup_sighand(struct sighand_struct *sighand)
920{
921 if (atomic_dec_and_test(&sighand->count))
922 kmem_cache_free(sighand_cachep, sighand);
923}
924
925
926/*
927 * Initialize POSIX timer handling for a thread group.
928 */
929static void posix_cpu_timers_init_group(struct signal_struct *sig)
930{
931 unsigned long cpu_limit;
932
933 /* Thread group counters. */
934 thread_group_cputime_init(sig);
935
936 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
937 if (cpu_limit != RLIM_INFINITY) {
938 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
939 sig->cputimer.running = 1;
940 }
941
942 /* The timer lists. */
943 INIT_LIST_HEAD(&sig->cpu_timers[0]);
944 INIT_LIST_HEAD(&sig->cpu_timers[1]);
945 INIT_LIST_HEAD(&sig->cpu_timers[2]);
946}
947
948static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
949{
950 struct signal_struct *sig;
951
952 if (clone_flags & CLONE_THREAD)
953 return 0;
954
955 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
956 tsk->signal = sig;
957 if (!sig)
958 return -ENOMEM;
959
960 sig->nr_threads = 1;
961 atomic_set(&sig->live, 1);
962 atomic_set(&sig->sigcnt, 1);
963 init_waitqueue_head(&sig->wait_chldexit);
964 if (clone_flags & CLONE_NEWPID)
965 sig->flags |= SIGNAL_UNKILLABLE;
966 sig->curr_target = tsk;
967 init_sigpending(&sig->shared_pending);
968 INIT_LIST_HEAD(&sig->posix_timers);
969
970 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
971 sig->real_timer.function = it_real_fn;
972
973 task_lock(current->group_leader);
974 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
975 task_unlock(current->group_leader);
976
977 posix_cpu_timers_init_group(sig);
978
979 tty_audit_fork(sig);
980 sched_autogroup_fork(sig);
981
982#ifdef CONFIG_CGROUPS
983 init_rwsem(&sig->threadgroup_fork_lock);
984#endif
985
986 sig->oom_adj = current->signal->oom_adj;
987 sig->oom_score_adj = current->signal->oom_score_adj;
988 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
989
990 mutex_init(&sig->cred_guard_mutex);
991
992 return 0;
993}
994
995static void copy_flags(unsigned long clone_flags, struct task_struct *p)
996{
997 unsigned long new_flags = p->flags;
998
999 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
1000 new_flags |= PF_FORKNOEXEC;
1001 new_flags |= PF_STARTING;
1002 p->flags = new_flags;
1003 clear_freeze_flag(p);
1004}
1005
1006SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1007{
1008 current->clear_child_tid = tidptr;
1009
1010 return task_pid_vnr(current);
1011}
1012
1013static void rt_mutex_init_task(struct task_struct *p)
1014{
1015 raw_spin_lock_init(&p->pi_lock);
1016#ifdef CONFIG_RT_MUTEXES
1017 plist_head_init(&p->pi_waiters);
1018 p->pi_blocked_on = NULL;
1019#endif
1020}
1021
1022#ifdef CONFIG_MM_OWNER
1023void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1024{
1025 mm->owner = p;
1026}
1027#endif /* CONFIG_MM_OWNER */
1028
1029/*
1030 * Initialize POSIX timer handling for a single task.
1031 */
1032static void posix_cpu_timers_init(struct task_struct *tsk)
1033{
1034 tsk->cputime_expires.prof_exp = cputime_zero;
1035 tsk->cputime_expires.virt_exp = cputime_zero;
1036 tsk->cputime_expires.sched_exp = 0;
1037 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1038 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1039 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1040}
1041
1042/*
1043 * This creates a new process as a copy of the old one,
1044 * but does not actually start it yet.
1045 *
1046 * It copies the registers, and all the appropriate
1047 * parts of the process environment (as per the clone
1048 * flags). The actual kick-off is left to the caller.
1049 */
1050static struct task_struct *copy_process(unsigned long clone_flags,
1051 unsigned long stack_start,
1052 struct pt_regs *regs,
1053 unsigned long stack_size,
1054 int __user *child_tidptr,
1055 struct pid *pid,
1056 int trace)
1057{
1058 int retval;
1059 struct task_struct *p;
1060 int cgroup_callbacks_done = 0;
1061
1062 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1063 return ERR_PTR(-EINVAL);
1064
1065 /*
1066 * Thread groups must share signals as well, and detached threads
1067 * can only be started up within the thread group.
1068 */
1069 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1070 return ERR_PTR(-EINVAL);
1071
1072 /*
1073 * Shared signal handlers imply shared VM. By way of the above,
1074 * thread groups also imply shared VM. Blocking this case allows
1075 * for various simplifications in other code.
1076 */
1077 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1078 return ERR_PTR(-EINVAL);
1079
1080 /*
1081 * Siblings of global init remain as zombies on exit since they are
1082 * not reaped by their parent (swapper). To solve this and to avoid
1083 * multi-rooted process trees, prevent global and container-inits
1084 * from creating siblings.
1085 */
1086 if ((clone_flags & CLONE_PARENT) &&
1087 current->signal->flags & SIGNAL_UNKILLABLE)
1088 return ERR_PTR(-EINVAL);
1089
1090 retval = security_task_create(clone_flags);
1091 if (retval)
1092 goto fork_out;
1093
1094 retval = -ENOMEM;
1095 p = dup_task_struct(current);
1096 if (!p)
1097 goto fork_out;
1098
1099 ftrace_graph_init_task(p);
1100
1101 rt_mutex_init_task(p);
1102
1103#ifdef CONFIG_PROVE_LOCKING
1104 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1105 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1106#endif
1107 retval = -EAGAIN;
1108 if (atomic_read(&p->real_cred->user->processes) >=
1109 task_rlimit(p, RLIMIT_NPROC)) {
1110 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1111 p->real_cred->user != INIT_USER)
1112 goto bad_fork_free;
1113 }
1114 current->flags &= ~PF_NPROC_EXCEEDED;
1115
1116 retval = copy_creds(p, clone_flags);
1117 if (retval < 0)
1118 goto bad_fork_free;
1119
1120 /*
1121 * If multiple threads are within copy_process(), then this check
1122 * triggers too late. This doesn't hurt, the check is only there
1123 * to stop root fork bombs.
1124 */
1125 retval = -EAGAIN;
1126 if (nr_threads >= max_threads)
1127 goto bad_fork_cleanup_count;
1128
1129 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1130 goto bad_fork_cleanup_count;
1131
1132 p->did_exec = 0;
1133 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1134 copy_flags(clone_flags, p);
1135 INIT_LIST_HEAD(&p->children);
1136 INIT_LIST_HEAD(&p->sibling);
1137 rcu_copy_process(p);
1138 p->vfork_done = NULL;
1139 spin_lock_init(&p->alloc_lock);
1140
1141 init_sigpending(&p->pending);
1142
1143 p->utime = cputime_zero;
1144 p->stime = cputime_zero;
1145 p->gtime = cputime_zero;
1146 p->utimescaled = cputime_zero;
1147 p->stimescaled = cputime_zero;
1148#ifndef CONFIG_VIRT_CPU_ACCOUNTING
1149 p->prev_utime = cputime_zero;
1150 p->prev_stime = cputime_zero;
1151#endif
1152#if defined(SPLIT_RSS_COUNTING)
1153 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1154#endif
1155
1156 p->default_timer_slack_ns = current->timer_slack_ns;
1157
1158 task_io_accounting_init(&p->ioac);
1159 acct_clear_integrals(p);
1160
1161 posix_cpu_timers_init(p);
1162
1163 do_posix_clock_monotonic_gettime(&p->start_time);
1164 p->real_start_time = p->start_time;
1165 monotonic_to_bootbased(&p->real_start_time);
1166 p->io_context = NULL;
1167 p->audit_context = NULL;
1168 if (clone_flags & CLONE_THREAD)
1169 threadgroup_fork_read_lock(current);
1170 cgroup_fork(p);
1171#ifdef CONFIG_NUMA
1172 p->mempolicy = mpol_dup(p->mempolicy);
1173 if (IS_ERR(p->mempolicy)) {
1174 retval = PTR_ERR(p->mempolicy);
1175 p->mempolicy = NULL;
1176 goto bad_fork_cleanup_cgroup;
1177 }
1178 mpol_fix_fork_child_flag(p);
1179#endif
1180#ifdef CONFIG_CPUSETS
1181 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1182 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1183#endif
1184#ifdef CONFIG_TRACE_IRQFLAGS
1185 p->irq_events = 0;
1186#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1187 p->hardirqs_enabled = 1;
1188#else
1189 p->hardirqs_enabled = 0;
1190#endif
1191 p->hardirq_enable_ip = 0;
1192 p->hardirq_enable_event = 0;
1193 p->hardirq_disable_ip = _THIS_IP_;
1194 p->hardirq_disable_event = 0;
1195 p->softirqs_enabled = 1;
1196 p->softirq_enable_ip = _THIS_IP_;
1197 p->softirq_enable_event = 0;
1198 p->softirq_disable_ip = 0;
1199 p->softirq_disable_event = 0;
1200 p->hardirq_context = 0;
1201 p->softirq_context = 0;
1202#endif
1203#ifdef CONFIG_LOCKDEP
1204 p->lockdep_depth = 0; /* no locks held yet */
1205 p->curr_chain_key = 0;
1206 p->lockdep_recursion = 0;
1207#endif
1208
1209#ifdef CONFIG_DEBUG_MUTEXES
1210 p->blocked_on = NULL; /* not blocked yet */
1211#endif
1212#ifdef CONFIG_CGROUP_MEM_RES_CTLR
1213 p->memcg_batch.do_batch = 0;
1214 p->memcg_batch.memcg = NULL;
1215#endif
1216
1217 /* Perform scheduler related setup. Assign this task to a CPU. */
1218 sched_fork(p);
1219
1220 retval = perf_event_init_task(p);
1221 if (retval)
1222 goto bad_fork_cleanup_policy;
1223 retval = audit_alloc(p);
1224 if (retval)
1225 goto bad_fork_cleanup_policy;
1226 /* copy all the process information */
1227 retval = copy_semundo(clone_flags, p);
1228 if (retval)
1229 goto bad_fork_cleanup_audit;
1230 retval = copy_files(clone_flags, p);
1231 if (retval)
1232 goto bad_fork_cleanup_semundo;
1233 retval = copy_fs(clone_flags, p);
1234 if (retval)
1235 goto bad_fork_cleanup_files;
1236 retval = copy_sighand(clone_flags, p);
1237 if (retval)
1238 goto bad_fork_cleanup_fs;
1239 retval = copy_signal(clone_flags, p);
1240 if (retval)
1241 goto bad_fork_cleanup_sighand;
1242 retval = copy_mm(clone_flags, p);
1243 if (retval)
1244 goto bad_fork_cleanup_signal;
1245 retval = copy_namespaces(clone_flags, p);
1246 if (retval)
1247 goto bad_fork_cleanup_mm;
1248 retval = copy_io(clone_flags, p);
1249 if (retval)
1250 goto bad_fork_cleanup_namespaces;
1251 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1252 if (retval)
1253 goto bad_fork_cleanup_io;
1254
1255 if (pid != &init_struct_pid) {
1256 retval = -ENOMEM;
1257 pid = alloc_pid(p->nsproxy->pid_ns);
1258 if (!pid)
1259 goto bad_fork_cleanup_io;
1260 }
1261
1262 p->pid = pid_nr(pid);
1263 p->tgid = p->pid;
1264 if (clone_flags & CLONE_THREAD)
1265 p->tgid = current->tgid;
1266
1267 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1268 /*
1269 * Clear TID on mm_release()?
1270 */
1271 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1272#ifdef CONFIG_BLOCK
1273 p->plug = NULL;
1274#endif
1275#ifdef CONFIG_FUTEX
1276 p->robust_list = NULL;
1277#ifdef CONFIG_COMPAT
1278 p->compat_robust_list = NULL;
1279#endif
1280 INIT_LIST_HEAD(&p->pi_state_list);
1281 p->pi_state_cache = NULL;
1282#endif
1283 /*
1284 * sigaltstack should be cleared when sharing the same VM
1285 */
1286 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1287 p->sas_ss_sp = p->sas_ss_size = 0;
1288
1289 /*
1290 * Syscall tracing and stepping should be turned off in the
1291 * child regardless of CLONE_PTRACE.
1292 */
1293 user_disable_single_step(p);
1294 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1295#ifdef TIF_SYSCALL_EMU
1296 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1297#endif
1298 clear_all_latency_tracing(p);
1299
1300 /* ok, now we should be set up.. */
1301 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1302 p->pdeath_signal = 0;
1303 p->exit_state = 0;
1304
1305 /*
1306 * Ok, make it visible to the rest of the system.
1307 * We dont wake it up yet.
1308 */
1309 p->group_leader = p;
1310 INIT_LIST_HEAD(&p->thread_group);
1311
1312 /* Now that the task is set up, run cgroup callbacks if
1313 * necessary. We need to run them before the task is visible
1314 * on the tasklist. */
1315 cgroup_fork_callbacks(p);
1316 cgroup_callbacks_done = 1;
1317
1318 /* Need tasklist lock for parent etc handling! */
1319 write_lock_irq(&tasklist_lock);
1320
1321 /* CLONE_PARENT re-uses the old parent */
1322 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1323 p->real_parent = current->real_parent;
1324 p->parent_exec_id = current->parent_exec_id;
1325 } else {
1326 p->real_parent = current;
1327 p->parent_exec_id = current->self_exec_id;
1328 }
1329
1330 spin_lock(¤t->sighand->siglock);
1331
1332 /*
1333 * Process group and session signals need to be delivered to just the
1334 * parent before the fork or both the parent and the child after the
1335 * fork. Restart if a signal comes in before we add the new process to
1336 * it's process group.
1337 * A fatal signal pending means that current will exit, so the new
1338 * thread can't slip out of an OOM kill (or normal SIGKILL).
1339 */
1340 recalc_sigpending();
1341 if (signal_pending(current)) {
1342 spin_unlock(¤t->sighand->siglock);
1343 write_unlock_irq(&tasklist_lock);
1344 retval = -ERESTARTNOINTR;
1345 goto bad_fork_free_pid;
1346 }
1347
1348 if (clone_flags & CLONE_THREAD) {
1349 current->signal->nr_threads++;
1350 atomic_inc(¤t->signal->live);
1351 atomic_inc(¤t->signal->sigcnt);
1352 p->group_leader = current->group_leader;
1353 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1354 }
1355
1356 if (likely(p->pid)) {
1357 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
1358
1359 if (thread_group_leader(p)) {
1360 if (is_child_reaper(pid))
1361 p->nsproxy->pid_ns->child_reaper = p;
1362
1363 p->signal->leader_pid = pid;
1364 p->signal->tty = tty_kref_get(current->signal->tty);
1365 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1366 attach_pid(p, PIDTYPE_SID, task_session(current));
1367 list_add_tail(&p->sibling, &p->real_parent->children);
1368 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1369 __this_cpu_inc(process_counts);
1370 }
1371 attach_pid(p, PIDTYPE_PID, pid);
1372 nr_threads++;
1373 }
1374
1375 total_forks++;
1376 spin_unlock(¤t->sighand->siglock);
1377 write_unlock_irq(&tasklist_lock);
1378 proc_fork_connector(p);
1379 cgroup_post_fork(p);
1380 if (clone_flags & CLONE_THREAD)
1381 threadgroup_fork_read_unlock(current);
1382 perf_event_fork(p);
1383 return p;
1384
1385bad_fork_free_pid:
1386 if (pid != &init_struct_pid)
1387 free_pid(pid);
1388bad_fork_cleanup_io:
1389 if (p->io_context)
1390 exit_io_context(p);
1391bad_fork_cleanup_namespaces:
1392 exit_task_namespaces(p);
1393bad_fork_cleanup_mm:
1394 if (p->mm) {
1395 task_lock(p);
1396 if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
1397 atomic_dec(&p->mm->oom_disable_count);
1398 task_unlock(p);
1399 mmput(p->mm);
1400 }
1401bad_fork_cleanup_signal:
1402 if (!(clone_flags & CLONE_THREAD))
1403 free_signal_struct(p->signal);
1404bad_fork_cleanup_sighand:
1405 __cleanup_sighand(p->sighand);
1406bad_fork_cleanup_fs:
1407 exit_fs(p); /* blocking */
1408bad_fork_cleanup_files:
1409 exit_files(p); /* blocking */
1410bad_fork_cleanup_semundo:
1411 exit_sem(p);
1412bad_fork_cleanup_audit:
1413 audit_free(p);
1414bad_fork_cleanup_policy:
1415 perf_event_free_task(p);
1416#ifdef CONFIG_NUMA
1417 mpol_put(p->mempolicy);
1418bad_fork_cleanup_cgroup:
1419#endif
1420 if (clone_flags & CLONE_THREAD)
1421 threadgroup_fork_read_unlock(current);
1422 cgroup_exit(p, cgroup_callbacks_done);
1423 delayacct_tsk_free(p);
1424 module_put(task_thread_info(p)->exec_domain->module);
1425bad_fork_cleanup_count:
1426 atomic_dec(&p->cred->user->processes);
1427 exit_creds(p);
1428bad_fork_free:
1429 free_task(p);
1430fork_out:
1431 return ERR_PTR(retval);
1432}
1433
1434noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1435{
1436 memset(regs, 0, sizeof(struct pt_regs));
1437 return regs;
1438}
1439
1440static inline void init_idle_pids(struct pid_link *links)
1441{
1442 enum pid_type type;
1443
1444 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1445 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1446 links[type].pid = &init_struct_pid;
1447 }
1448}
1449
1450struct task_struct * __cpuinit fork_idle(int cpu)
1451{
1452 struct task_struct *task;
1453 struct pt_regs regs;
1454
1455 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1456 &init_struct_pid, 0);
1457 if (!IS_ERR(task)) {
1458 init_idle_pids(task->pids);
1459 init_idle(task, cpu);
1460 }
1461
1462 return task;
1463}
1464
1465/*
1466 * Ok, this is the main fork-routine.
1467 *
1468 * It copies the process, and if successful kick-starts
1469 * it and waits for it to finish using the VM if required.
1470 */
1471long do_fork(unsigned long clone_flags,
1472 unsigned long stack_start,
1473 struct pt_regs *regs,
1474 unsigned long stack_size,
1475 int __user *parent_tidptr,
1476 int __user *child_tidptr)
1477{
1478 struct task_struct *p;
1479 int trace = 0;
1480 long nr;
1481
1482 /*
1483 * Do some preliminary argument and permissions checking before we
1484 * actually start allocating stuff
1485 */
1486 if (clone_flags & CLONE_NEWUSER) {
1487 if (clone_flags & CLONE_THREAD)
1488 return -EINVAL;
1489 /* hopefully this check will go away when userns support is
1490 * complete
1491 */
1492 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1493 !capable(CAP_SETGID))
1494 return -EPERM;
1495 }
1496
1497 /*
1498 * Determine whether and which event to report to ptracer. When
1499 * called from kernel_thread or CLONE_UNTRACED is explicitly
1500 * requested, no event is reported; otherwise, report if the event
1501 * for the type of forking is enabled.
1502 */
1503 if (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) {
1504 if (clone_flags & CLONE_VFORK)
1505 trace = PTRACE_EVENT_VFORK;
1506 else if ((clone_flags & CSIGNAL) != SIGCHLD)
1507 trace = PTRACE_EVENT_CLONE;
1508 else
1509 trace = PTRACE_EVENT_FORK;
1510
1511 if (likely(!ptrace_event_enabled(current, trace)))
1512 trace = 0;
1513 }
1514
1515 p = copy_process(clone_flags, stack_start, regs, stack_size,
1516 child_tidptr, NULL, trace);
1517 /*
1518 * Do this prior waking up the new thread - the thread pointer
1519 * might get invalid after that point, if the thread exits quickly.
1520 */
1521 if (!IS_ERR(p)) {
1522 struct completion vfork;
1523
1524 trace_sched_process_fork(current, p);
1525
1526 nr = task_pid_vnr(p);
1527
1528 if (clone_flags & CLONE_PARENT_SETTID)
1529 put_user(nr, parent_tidptr);
1530
1531 if (clone_flags & CLONE_VFORK) {
1532 p->vfork_done = &vfork;
1533 init_completion(&vfork);
1534 }
1535
1536 audit_finish_fork(p);
1537
1538 /*
1539 * We set PF_STARTING at creation in case tracing wants to
1540 * use this to distinguish a fully live task from one that
1541 * hasn't finished SIGSTOP raising yet. Now we clear it
1542 * and set the child going.
1543 */
1544 p->flags &= ~PF_STARTING;
1545
1546 wake_up_new_task(p);
1547
1548 /* forking complete and child started to run, tell ptracer */
1549 if (unlikely(trace))
1550 ptrace_event(trace, nr);
1551
1552 if (clone_flags & CLONE_VFORK) {
1553 freezer_do_not_count();
1554 wait_for_completion(&vfork);
1555 freezer_count();
1556 ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
1557 }
1558 } else {
1559 nr = PTR_ERR(p);
1560 }
1561 return nr;
1562}
1563
1564#ifndef ARCH_MIN_MMSTRUCT_ALIGN
1565#define ARCH_MIN_MMSTRUCT_ALIGN 0
1566#endif
1567
1568static void sighand_ctor(void *data)
1569{
1570 struct sighand_struct *sighand = data;
1571
1572 spin_lock_init(&sighand->siglock);
1573 init_waitqueue_head(&sighand->signalfd_wqh);
1574}
1575
1576void __init proc_caches_init(void)
1577{
1578 sighand_cachep = kmem_cache_create("sighand_cache",
1579 sizeof(struct sighand_struct), 0,
1580 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1581 SLAB_NOTRACK, sighand_ctor);
1582 signal_cachep = kmem_cache_create("signal_cache",
1583 sizeof(struct signal_struct), 0,
1584 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1585 files_cachep = kmem_cache_create("files_cache",
1586 sizeof(struct files_struct), 0,
1587 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1588 fs_cachep = kmem_cache_create("fs_cache",
1589 sizeof(struct fs_struct), 0,
1590 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1591 /*
1592 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1593 * whole struct cpumask for the OFFSTACK case. We could change
1594 * this to *only* allocate as much of it as required by the
1595 * maximum number of CPU's we can ever have. The cpumask_allocation
1596 * is at the end of the structure, exactly for that reason.
1597 */
1598 mm_cachep = kmem_cache_create("mm_struct",
1599 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1600 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1601 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1602 mmap_init();
1603 nsproxy_cache_init();
1604}
1605
1606/*
1607 * Check constraints on flags passed to the unshare system call.
1608 */
1609static int check_unshare_flags(unsigned long unshare_flags)
1610{
1611 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1612 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1613 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1614 return -EINVAL;
1615 /*
1616 * Not implemented, but pretend it works if there is nothing to
1617 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1618 * needs to unshare vm.
1619 */
1620 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1621 /* FIXME: get_task_mm() increments ->mm_users */
1622 if (atomic_read(¤t->mm->mm_users) > 1)
1623 return -EINVAL;
1624 }
1625
1626 return 0;
1627}
1628
1629/*
1630 * Unshare the filesystem structure if it is being shared
1631 */
1632static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1633{
1634 struct fs_struct *fs = current->fs;
1635
1636 if (!(unshare_flags & CLONE_FS) || !fs)
1637 return 0;
1638
1639 /* don't need lock here; in the worst case we'll do useless copy */
1640 if (fs->users == 1)
1641 return 0;
1642
1643 *new_fsp = copy_fs_struct(fs);
1644 if (!*new_fsp)
1645 return -ENOMEM;
1646
1647 return 0;
1648}
1649
1650/*
1651 * Unshare file descriptor table if it is being shared
1652 */
1653static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1654{
1655 struct files_struct *fd = current->files;
1656 int error = 0;
1657
1658 if ((unshare_flags & CLONE_FILES) &&
1659 (fd && atomic_read(&fd->count) > 1)) {
1660 *new_fdp = dup_fd(fd, &error);
1661 if (!*new_fdp)
1662 return error;
1663 }
1664
1665 return 0;
1666}
1667
1668/*
1669 * unshare allows a process to 'unshare' part of the process
1670 * context which was originally shared using clone. copy_*
1671 * functions used by do_fork() cannot be used here directly
1672 * because they modify an inactive task_struct that is being
1673 * constructed. Here we are modifying the current, active,
1674 * task_struct.
1675 */
1676SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1677{
1678 struct fs_struct *fs, *new_fs = NULL;
1679 struct files_struct *fd, *new_fd = NULL;
1680 struct nsproxy *new_nsproxy = NULL;
1681 int do_sysvsem = 0;
1682 int err;
1683
1684 err = check_unshare_flags(unshare_flags);
1685 if (err)
1686 goto bad_unshare_out;
1687
1688 /*
1689 * If unsharing namespace, must also unshare filesystem information.
1690 */
1691 if (unshare_flags & CLONE_NEWNS)
1692 unshare_flags |= CLONE_FS;
1693 /*
1694 * CLONE_NEWIPC must also detach from the undolist: after switching
1695 * to a new ipc namespace, the semaphore arrays from the old
1696 * namespace are unreachable.
1697 */
1698 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1699 do_sysvsem = 1;
1700 err = unshare_fs(unshare_flags, &new_fs);
1701 if (err)
1702 goto bad_unshare_out;
1703 err = unshare_fd(unshare_flags, &new_fd);
1704 if (err)
1705 goto bad_unshare_cleanup_fs;
1706 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs);
1707 if (err)
1708 goto bad_unshare_cleanup_fd;
1709
1710 if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
1711 if (do_sysvsem) {
1712 /*
1713 * CLONE_SYSVSEM is equivalent to sys_exit().
1714 */
1715 exit_sem(current);
1716 }
1717
1718 if (new_nsproxy) {
1719 switch_task_namespaces(current, new_nsproxy);
1720 new_nsproxy = NULL;
1721 }
1722
1723 task_lock(current);
1724
1725 if (new_fs) {
1726 fs = current->fs;
1727 spin_lock(&fs->lock);
1728 current->fs = new_fs;
1729 if (--fs->users)
1730 new_fs = NULL;
1731 else
1732 new_fs = fs;
1733 spin_unlock(&fs->lock);
1734 }
1735
1736 if (new_fd) {
1737 fd = current->files;
1738 current->files = new_fd;
1739 new_fd = fd;
1740 }
1741
1742 task_unlock(current);
1743 }
1744
1745 if (new_nsproxy)
1746 put_nsproxy(new_nsproxy);
1747
1748bad_unshare_cleanup_fd:
1749 if (new_fd)
1750 put_files_struct(new_fd);
1751
1752bad_unshare_cleanup_fs:
1753 if (new_fs)
1754 free_fs_struct(new_fs);
1755
1756bad_unshare_out:
1757 return err;
1758}
1759
1760/*
1761 * Helper to unshare the files of the current task.
1762 * We don't want to expose copy_files internals to
1763 * the exec layer of the kernel.
1764 */
1765
1766int unshare_files(struct files_struct **displaced)
1767{
1768 struct task_struct *task = current;
1769 struct files_struct *copy = NULL;
1770 int error;
1771
1772 error = unshare_fd(CLONE_FILES, ©);
1773 if (error || !copy) {
1774 *displaced = NULL;
1775 return error;
1776 }
1777 *displaced = task->files;
1778 task_lock(task);
1779 task->files = copy;
1780 task_unlock(task);
1781 return 0;
1782}