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