projects/linux·blob v5.12 · refs

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