projects/linux·blob v5.17 · 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/mm_inline.h>
46#include <linux/vmacache.h>
47#include <linux/nsproxy.h>
48#include <linux/capability.h>
49#include <linux/cpu.h>
50#include <linux/cgroup.h>
51#include <linux/security.h>
52#include <linux/hugetlb.h>
53#include <linux/seccomp.h>
54#include <linux/swap.h>
55#include <linux/syscalls.h>
56#include <linux/jiffies.h>
57#include <linux/futex.h>
58#include <linux/compat.h>
59#include <linux/kthread.h>
60#include <linux/task_io_accounting_ops.h>
61#include <linux/rcupdate.h>
62#include <linux/ptrace.h>
63#include <linux/mount.h>
64#include <linux/audit.h>
65#include <linux/memcontrol.h>
66#include <linux/ftrace.h>
67#include <linux/proc_fs.h>
68#include <linux/profile.h>
69#include <linux/rmap.h>
70#include <linux/ksm.h>
71#include <linux/acct.h>
72#include <linux/userfaultfd_k.h>
73#include <linux/tsacct_kern.h>
74#include <linux/cn_proc.h>
75#include <linux/freezer.h>
76#include <linux/delayacct.h>
77#include <linux/taskstats_kern.h>
78#include <linux/random.h>
79#include <linux/tty.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#include <linux/bpf.h>
100
101#include <asm/pgalloc.h>
102#include <linux/uaccess.h>
103#include <asm/mmu_context.h>
104#include <asm/cacheflush.h>
105#include <asm/tlbflush.h>
106
107#include <trace/events/sched.h>
108
109#define CREATE_TRACE_POINTS
110#include <trace/events/task.h>
111
112/*
113 * Minimum number of threads to boot the kernel
114 */
115#define MIN_THREADS 20
116
117/*
118 * Maximum number of threads
119 */
120#define MAX_THREADS FUTEX_TID_MASK
121
122/*
123 * Protected counters by write_lock_irq(&tasklist_lock)
124 */
125unsigned long total_forks; /* Handle normal Linux uptimes. */
126int nr_threads; /* The idle threads do not count.. */
127
128static int max_threads; /* tunable limit on nr_threads */
129
130#define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
131
132static const char * const resident_page_types[] = {
133 NAMED_ARRAY_INDEX(MM_FILEPAGES),
134 NAMED_ARRAY_INDEX(MM_ANONPAGES),
135 NAMED_ARRAY_INDEX(MM_SWAPENTS),
136 NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
137};
138
139DEFINE_PER_CPU(unsigned long, process_counts) = 0;
140
141__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
142
143#ifdef CONFIG_PROVE_RCU
144int lockdep_tasklist_lock_is_held(void)
145{
146 return lockdep_is_held(&tasklist_lock);
147}
148EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
149#endif /* #ifdef CONFIG_PROVE_RCU */
150
151int nr_processes(void)
152{
153 int cpu;
154 int total = 0;
155
156 for_each_possible_cpu(cpu)
157 total += per_cpu(process_counts, cpu);
158
159 return total;
160}
161
162void __weak arch_release_task_struct(struct task_struct *tsk)
163{
164}
165
166#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
167static struct kmem_cache *task_struct_cachep;
168
169static inline struct task_struct *alloc_task_struct_node(int node)
170{
171 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
172}
173
174static inline void free_task_struct(struct task_struct *tsk)
175{
176 kmem_cache_free(task_struct_cachep, tsk);
177}
178#endif
179
180#ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
181
182/*
183 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
184 * kmemcache based allocator.
185 */
186# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
187
188#ifdef CONFIG_VMAP_STACK
189/*
190 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
191 * flush. Try to minimize the number of calls by caching stacks.
192 */
193#define NR_CACHED_STACKS 2
194static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
195
196static int free_vm_stack_cache(unsigned int cpu)
197{
198 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
199 int i;
200
201 for (i = 0; i < NR_CACHED_STACKS; i++) {
202 struct vm_struct *vm_stack = cached_vm_stacks[i];
203
204 if (!vm_stack)
205 continue;
206
207 vfree(vm_stack->addr);
208 cached_vm_stacks[i] = NULL;
209 }
210
211 return 0;
212}
213#endif
214
215static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
216{
217#ifdef CONFIG_VMAP_STACK
218 void *stack;
219 int i;
220
221 for (i = 0; i < NR_CACHED_STACKS; i++) {
222 struct vm_struct *s;
223
224 s = this_cpu_xchg(cached_stacks[i], NULL);
225
226 if (!s)
227 continue;
228
229 /* Mark stack accessible for KASAN. */
230 kasan_unpoison_range(s->addr, THREAD_SIZE);
231
232 /* Clear stale pointers from reused stack. */
233 memset(s->addr, 0, THREAD_SIZE);
234
235 tsk->stack_vm_area = s;
236 tsk->stack = s->addr;
237 return s->addr;
238 }
239
240 /*
241 * Allocated stacks are cached and later reused by new threads,
242 * so memcg accounting is performed manually on assigning/releasing
243 * stacks to tasks. Drop __GFP_ACCOUNT.
244 */
245 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
246 VMALLOC_START, VMALLOC_END,
247 THREADINFO_GFP & ~__GFP_ACCOUNT,
248 PAGE_KERNEL,
249 0, node, __builtin_return_address(0));
250
251 /*
252 * We can't call find_vm_area() in interrupt context, and
253 * free_thread_stack() can be called in interrupt context,
254 * so cache the vm_struct.
255 */
256 if (stack) {
257 tsk->stack_vm_area = find_vm_area(stack);
258 tsk->stack = stack;
259 }
260 return stack;
261#else
262 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
263 THREAD_SIZE_ORDER);
264
265 if (likely(page)) {
266 tsk->stack = kasan_reset_tag(page_address(page));
267 return tsk->stack;
268 }
269 return NULL;
270#endif
271}
272
273static inline void free_thread_stack(struct task_struct *tsk)
274{
275#ifdef CONFIG_VMAP_STACK
276 struct vm_struct *vm = task_stack_vm_area(tsk);
277
278 if (vm) {
279 int i;
280
281 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
282 memcg_kmem_uncharge_page(vm->pages[i], 0);
283
284 for (i = 0; i < NR_CACHED_STACKS; i++) {
285 if (this_cpu_cmpxchg(cached_stacks[i],
286 NULL, tsk->stack_vm_area) != NULL)
287 continue;
288
289 return;
290 }
291
292 vfree_atomic(tsk->stack);
293 return;
294 }
295#endif
296
297 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
298}
299# else
300static struct kmem_cache *thread_stack_cache;
301
302static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
303 int node)
304{
305 unsigned long *stack;
306 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
307 stack = kasan_reset_tag(stack);
308 tsk->stack = stack;
309 return stack;
310}
311
312static void free_thread_stack(struct task_struct *tsk)
313{
314 kmem_cache_free(thread_stack_cache, tsk->stack);
315}
316
317void thread_stack_cache_init(void)
318{
319 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
320 THREAD_SIZE, THREAD_SIZE, 0, 0,
321 THREAD_SIZE, NULL);
322 BUG_ON(thread_stack_cache == NULL);
323}
324# endif
325#endif
326
327/* SLAB cache for signal_struct structures (tsk->signal) */
328static struct kmem_cache *signal_cachep;
329
330/* SLAB cache for sighand_struct structures (tsk->sighand) */
331struct kmem_cache *sighand_cachep;
332
333/* SLAB cache for files_struct structures (tsk->files) */
334struct kmem_cache *files_cachep;
335
336/* SLAB cache for fs_struct structures (tsk->fs) */
337struct kmem_cache *fs_cachep;
338
339/* SLAB cache for vm_area_struct structures */
340static struct kmem_cache *vm_area_cachep;
341
342/* SLAB cache for mm_struct structures (tsk->mm) */
343static struct kmem_cache *mm_cachep;
344
345struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
346{
347 struct vm_area_struct *vma;
348
349 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
350 if (vma)
351 vma_init(vma, mm);
352 return vma;
353}
354
355struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
356{
357 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
358
359 if (new) {
360 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
361 ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
362 /*
363 * orig->shared.rb may be modified concurrently, but the clone
364 * will be reinitialized.
365 */
366 *new = data_race(*orig);
367 INIT_LIST_HEAD(&new->anon_vma_chain);
368 new->vm_next = new->vm_prev = NULL;
369 dup_anon_vma_name(orig, new);
370 }
371 return new;
372}
373
374void vm_area_free(struct vm_area_struct *vma)
375{
376 free_anon_vma_name(vma);
377 kmem_cache_free(vm_area_cachep, vma);
378}
379
380static void account_kernel_stack(struct task_struct *tsk, int account)
381{
382 void *stack = task_stack_page(tsk);
383 struct vm_struct *vm = task_stack_vm_area(tsk);
384
385 if (vm) {
386 int i;
387
388 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
389 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
390 account * (PAGE_SIZE / 1024));
391 } else {
392 /* All stack pages are in the same node. */
393 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
394 account * (THREAD_SIZE / 1024));
395 }
396}
397
398static int memcg_charge_kernel_stack(struct task_struct *tsk)
399{
400#ifdef CONFIG_VMAP_STACK
401 struct vm_struct *vm = task_stack_vm_area(tsk);
402 int ret;
403
404 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
405
406 if (vm) {
407 int i;
408
409 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
410
411 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
412 /*
413 * If memcg_kmem_charge_page() fails, page's
414 * memory cgroup pointer is NULL, and
415 * memcg_kmem_uncharge_page() in free_thread_stack()
416 * will ignore this page.
417 */
418 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
419 0);
420 if (ret)
421 return ret;
422 }
423 }
424#endif
425 return 0;
426}
427
428static void release_task_stack(struct task_struct *tsk)
429{
430 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
431 return; /* Better to leak the stack than to free prematurely */
432
433 account_kernel_stack(tsk, -1);
434 free_thread_stack(tsk);
435 tsk->stack = NULL;
436#ifdef CONFIG_VMAP_STACK
437 tsk->stack_vm_area = NULL;
438#endif
439}
440
441#ifdef CONFIG_THREAD_INFO_IN_TASK
442void put_task_stack(struct task_struct *tsk)
443{
444 if (refcount_dec_and_test(&tsk->stack_refcount))
445 release_task_stack(tsk);
446}
447#endif
448
449void free_task(struct task_struct *tsk)
450{
451 release_user_cpus_ptr(tsk);
452 scs_release(tsk);
453
454#ifndef CONFIG_THREAD_INFO_IN_TASK
455 /*
456 * The task is finally done with both the stack and thread_info,
457 * so free both.
458 */
459 release_task_stack(tsk);
460#else
461 /*
462 * If the task had a separate stack allocation, it should be gone
463 * by now.
464 */
465 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
466#endif
467 rt_mutex_debug_task_free(tsk);
468 ftrace_graph_exit_task(tsk);
469 arch_release_task_struct(tsk);
470 if (tsk->flags & PF_KTHREAD)
471 free_kthread_struct(tsk);
472 free_task_struct(tsk);
473}
474EXPORT_SYMBOL(free_task);
475
476static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
477{
478 struct file *exe_file;
479
480 exe_file = get_mm_exe_file(oldmm);
481 RCU_INIT_POINTER(mm->exe_file, exe_file);
482 /*
483 * We depend on the oldmm having properly denied write access to the
484 * exe_file already.
485 */
486 if (exe_file && deny_write_access(exe_file))
487 pr_warn_once("deny_write_access() failed in %s\n", __func__);
488}
489
490#ifdef CONFIG_MMU
491static __latent_entropy int dup_mmap(struct mm_struct *mm,
492 struct mm_struct *oldmm)
493{
494 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
495 struct rb_node **rb_link, *rb_parent;
496 int retval;
497 unsigned long charge;
498 LIST_HEAD(uf);
499
500 uprobe_start_dup_mmap();
501 if (mmap_write_lock_killable(oldmm)) {
502 retval = -EINTR;
503 goto fail_uprobe_end;
504 }
505 flush_cache_dup_mm(oldmm);
506 uprobe_dup_mmap(oldmm, mm);
507 /*
508 * Not linked in yet - no deadlock potential:
509 */
510 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
511
512 /* No ordering required: file already has been exposed. */
513 dup_mm_exe_file(mm, oldmm);
514
515 mm->total_vm = oldmm->total_vm;
516 mm->data_vm = oldmm->data_vm;
517 mm->exec_vm = oldmm->exec_vm;
518 mm->stack_vm = oldmm->stack_vm;
519
520 rb_link = &mm->mm_rb.rb_node;
521 rb_parent = NULL;
522 pprev = &mm->mmap;
523 retval = ksm_fork(mm, oldmm);
524 if (retval)
525 goto out;
526 retval = khugepaged_fork(mm, oldmm);
527 if (retval)
528 goto out;
529
530 prev = NULL;
531 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
532 struct file *file;
533
534 if (mpnt->vm_flags & VM_DONTCOPY) {
535 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
536 continue;
537 }
538 charge = 0;
539 /*
540 * Don't duplicate many vmas if we've been oom-killed (for
541 * example)
542 */
543 if (fatal_signal_pending(current)) {
544 retval = -EINTR;
545 goto out;
546 }
547 if (mpnt->vm_flags & VM_ACCOUNT) {
548 unsigned long len = vma_pages(mpnt);
549
550 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
551 goto fail_nomem;
552 charge = len;
553 }
554 tmp = vm_area_dup(mpnt);
555 if (!tmp)
556 goto fail_nomem;
557 retval = vma_dup_policy(mpnt, tmp);
558 if (retval)
559 goto fail_nomem_policy;
560 tmp->vm_mm = mm;
561 retval = dup_userfaultfd(tmp, &uf);
562 if (retval)
563 goto fail_nomem_anon_vma_fork;
564 if (tmp->vm_flags & VM_WIPEONFORK) {
565 /*
566 * VM_WIPEONFORK gets a clean slate in the child.
567 * Don't prepare anon_vma until fault since we don't
568 * copy page for current vma.
569 */
570 tmp->anon_vma = NULL;
571 } else if (anon_vma_fork(tmp, mpnt))
572 goto fail_nomem_anon_vma_fork;
573 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
574 file = tmp->vm_file;
575 if (file) {
576 struct address_space *mapping = file->f_mapping;
577
578 get_file(file);
579 i_mmap_lock_write(mapping);
580 if (tmp->vm_flags & VM_SHARED)
581 mapping_allow_writable(mapping);
582 flush_dcache_mmap_lock(mapping);
583 /* insert tmp into the share list, just after mpnt */
584 vma_interval_tree_insert_after(tmp, mpnt,
585 &mapping->i_mmap);
586 flush_dcache_mmap_unlock(mapping);
587 i_mmap_unlock_write(mapping);
588 }
589
590 /*
591 * Clear hugetlb-related page reserves for children. This only
592 * affects MAP_PRIVATE mappings. Faults generated by the child
593 * are not guaranteed to succeed, even if read-only
594 */
595 if (is_vm_hugetlb_page(tmp))
596 reset_vma_resv_huge_pages(tmp);
597
598 /*
599 * Link in the new vma and copy the page table entries.
600 */
601 *pprev = tmp;
602 pprev = &tmp->vm_next;
603 tmp->vm_prev = prev;
604 prev = tmp;
605
606 __vma_link_rb(mm, tmp, rb_link, rb_parent);
607 rb_link = &tmp->vm_rb.rb_right;
608 rb_parent = &tmp->vm_rb;
609
610 mm->map_count++;
611 if (!(tmp->vm_flags & VM_WIPEONFORK))
612 retval = copy_page_range(tmp, mpnt);
613
614 if (tmp->vm_ops && tmp->vm_ops->open)
615 tmp->vm_ops->open(tmp);
616
617 if (retval)
618 goto out;
619 }
620 /* a new mm has just been created */
621 retval = arch_dup_mmap(oldmm, mm);
622out:
623 mmap_write_unlock(mm);
624 flush_tlb_mm(oldmm);
625 mmap_write_unlock(oldmm);
626 dup_userfaultfd_complete(&uf);
627fail_uprobe_end:
628 uprobe_end_dup_mmap();
629 return retval;
630fail_nomem_anon_vma_fork:
631 mpol_put(vma_policy(tmp));
632fail_nomem_policy:
633 vm_area_free(tmp);
634fail_nomem:
635 retval = -ENOMEM;
636 vm_unacct_memory(charge);
637 goto out;
638}
639
640static inline int mm_alloc_pgd(struct mm_struct *mm)
641{
642 mm->pgd = pgd_alloc(mm);
643 if (unlikely(!mm->pgd))
644 return -ENOMEM;
645 return 0;
646}
647
648static inline void mm_free_pgd(struct mm_struct *mm)
649{
650 pgd_free(mm, mm->pgd);
651}
652#else
653static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
654{
655 mmap_write_lock(oldmm);
656 dup_mm_exe_file(mm, oldmm);
657 mmap_write_unlock(oldmm);
658 return 0;
659}
660#define mm_alloc_pgd(mm) (0)
661#define mm_free_pgd(mm)
662#endif /* CONFIG_MMU */
663
664static void check_mm(struct mm_struct *mm)
665{
666 int i;
667
668 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
669 "Please make sure 'struct resident_page_types[]' is updated as well");
670
671 for (i = 0; i < NR_MM_COUNTERS; i++) {
672 long x = atomic_long_read(&mm->rss_stat.count[i]);
673
674 if (unlikely(x))
675 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
676 mm, resident_page_types[i], x);
677 }
678
679 if (mm_pgtables_bytes(mm))
680 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
681 mm_pgtables_bytes(mm));
682
683#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
684 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
685#endif
686}
687
688#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
689#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
690
691/*
692 * Called when the last reference to the mm
693 * is dropped: either by a lazy thread or by
694 * mmput. Free the page directory and the mm.
695 */
696void __mmdrop(struct mm_struct *mm)
697{
698 BUG_ON(mm == &init_mm);
699 WARN_ON_ONCE(mm == current->mm);
700 WARN_ON_ONCE(mm == current->active_mm);
701 mm_free_pgd(mm);
702 destroy_context(mm);
703 mmu_notifier_subscriptions_destroy(mm);
704 check_mm(mm);
705 put_user_ns(mm->user_ns);
706 free_mm(mm);
707}
708EXPORT_SYMBOL_GPL(__mmdrop);
709
710static void mmdrop_async_fn(struct work_struct *work)
711{
712 struct mm_struct *mm;
713
714 mm = container_of(work, struct mm_struct, async_put_work);
715 __mmdrop(mm);
716}
717
718static void mmdrop_async(struct mm_struct *mm)
719{
720 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
721 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
722 schedule_work(&mm->async_put_work);
723 }
724}
725
726static inline void free_signal_struct(struct signal_struct *sig)
727{
728 taskstats_tgid_free(sig);
729 sched_autogroup_exit(sig);
730 /*
731 * __mmdrop is not safe to call from softirq context on x86 due to
732 * pgd_dtor so postpone it to the async context
733 */
734 if (sig->oom_mm)
735 mmdrop_async(sig->oom_mm);
736 kmem_cache_free(signal_cachep, sig);
737}
738
739static inline void put_signal_struct(struct signal_struct *sig)
740{
741 if (refcount_dec_and_test(&sig->sigcnt))
742 free_signal_struct(sig);
743}
744
745void __put_task_struct(struct task_struct *tsk)
746{
747 WARN_ON(!tsk->exit_state);
748 WARN_ON(refcount_read(&tsk->usage));
749 WARN_ON(tsk == current);
750
751 io_uring_free(tsk);
752 cgroup_free(tsk);
753 task_numa_free(tsk, true);
754 security_task_free(tsk);
755 bpf_task_storage_free(tsk);
756 exit_creds(tsk);
757 delayacct_tsk_free(tsk);
758 put_signal_struct(tsk->signal);
759 sched_core_free(tsk);
760 free_task(tsk);
761}
762EXPORT_SYMBOL_GPL(__put_task_struct);
763
764void __init __weak arch_task_cache_init(void) { }
765
766/*
767 * set_max_threads
768 */
769static void set_max_threads(unsigned int max_threads_suggested)
770{
771 u64 threads;
772 unsigned long nr_pages = totalram_pages();
773
774 /*
775 * The number of threads shall be limited such that the thread
776 * structures may only consume a small part of the available memory.
777 */
778 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
779 threads = MAX_THREADS;
780 else
781 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
782 (u64) THREAD_SIZE * 8UL);
783
784 if (threads > max_threads_suggested)
785 threads = max_threads_suggested;
786
787 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
788}
789
790#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
791/* Initialized by the architecture: */
792int arch_task_struct_size __read_mostly;
793#endif
794
795#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
796static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
797{
798 /* Fetch thread_struct whitelist for the architecture. */
799 arch_thread_struct_whitelist(offset, size);
800
801 /*
802 * Handle zero-sized whitelist or empty thread_struct, otherwise
803 * adjust offset to position of thread_struct in task_struct.
804 */
805 if (unlikely(*size == 0))
806 *offset = 0;
807 else
808 *offset += offsetof(struct task_struct, thread);
809}
810#endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
811
812void __init fork_init(void)
813{
814 int i;
815#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
816#ifndef ARCH_MIN_TASKALIGN
817#define ARCH_MIN_TASKALIGN 0
818#endif
819 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
820 unsigned long useroffset, usersize;
821
822 /* create a slab on which task_structs can be allocated */
823 task_struct_whitelist(&useroffset, &usersize);
824 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
825 arch_task_struct_size, align,
826 SLAB_PANIC|SLAB_ACCOUNT,
827 useroffset, usersize, NULL);
828#endif
829
830 /* do the arch specific task caches init */
831 arch_task_cache_init();
832
833 set_max_threads(MAX_THREADS);
834
835 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
836 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
837 init_task.signal->rlim[RLIMIT_SIGPENDING] =
838 init_task.signal->rlim[RLIMIT_NPROC];
839
840 for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++)
841 init_user_ns.ucount_max[i] = max_threads/2;
842
843 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
844 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
845 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
846 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
847
848#ifdef CONFIG_VMAP_STACK
849 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
850 NULL, free_vm_stack_cache);
851#endif
852
853 scs_init();
854
855 lockdep_init_task(&init_task);
856 uprobes_init();
857}
858
859int __weak arch_dup_task_struct(struct task_struct *dst,
860 struct task_struct *src)
861{
862 *dst = *src;
863 return 0;
864}
865
866void set_task_stack_end_magic(struct task_struct *tsk)
867{
868 unsigned long *stackend;
869
870 stackend = end_of_stack(tsk);
871 *stackend = STACK_END_MAGIC; /* for overflow detection */
872}
873
874static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
875{
876 struct task_struct *tsk;
877 unsigned long *stack;
878 struct vm_struct *stack_vm_area __maybe_unused;
879 int err;
880
881 if (node == NUMA_NO_NODE)
882 node = tsk_fork_get_node(orig);
883 tsk = alloc_task_struct_node(node);
884 if (!tsk)
885 return NULL;
886
887 stack = alloc_thread_stack_node(tsk, node);
888 if (!stack)
889 goto free_tsk;
890
891 if (memcg_charge_kernel_stack(tsk))
892 goto free_stack;
893
894 stack_vm_area = task_stack_vm_area(tsk);
895
896 err = arch_dup_task_struct(tsk, orig);
897
898 /*
899 * arch_dup_task_struct() clobbers the stack-related fields. Make
900 * sure they're properly initialized before using any stack-related
901 * functions again.
902 */
903 tsk->stack = stack;
904#ifdef CONFIG_VMAP_STACK
905 tsk->stack_vm_area = stack_vm_area;
906#endif
907#ifdef CONFIG_THREAD_INFO_IN_TASK
908 refcount_set(&tsk->stack_refcount, 1);
909#endif
910
911 if (err)
912 goto free_stack;
913
914 err = scs_prepare(tsk, node);
915 if (err)
916 goto free_stack;
917
918#ifdef CONFIG_SECCOMP
919 /*
920 * We must handle setting up seccomp filters once we're under
921 * the sighand lock in case orig has changed between now and
922 * then. Until then, filter must be NULL to avoid messing up
923 * the usage counts on the error path calling free_task.
924 */
925 tsk->seccomp.filter = NULL;
926#endif
927
928 setup_thread_stack(tsk, orig);
929 clear_user_return_notifier(tsk);
930 clear_tsk_need_resched(tsk);
931 set_task_stack_end_magic(tsk);
932 clear_syscall_work_syscall_user_dispatch(tsk);
933
934#ifdef CONFIG_STACKPROTECTOR
935 tsk->stack_canary = get_random_canary();
936#endif
937 if (orig->cpus_ptr == &orig->cpus_mask)
938 tsk->cpus_ptr = &tsk->cpus_mask;
939 dup_user_cpus_ptr(tsk, orig, node);
940
941 /*
942 * One for the user space visible state that goes away when reaped.
943 * One for the scheduler.
944 */
945 refcount_set(&tsk->rcu_users, 2);
946 /* One for the rcu users */
947 refcount_set(&tsk->usage, 1);
948#ifdef CONFIG_BLK_DEV_IO_TRACE
949 tsk->btrace_seq = 0;
950#endif
951 tsk->splice_pipe = NULL;
952 tsk->task_frag.page = NULL;
953 tsk->wake_q.next = NULL;
954 tsk->worker_private = NULL;
955
956 account_kernel_stack(tsk, 1);
957
958 kcov_task_init(tsk);
959 kmap_local_fork(tsk);
960
961#ifdef CONFIG_FAULT_INJECTION
962 tsk->fail_nth = 0;
963#endif
964
965#ifdef CONFIG_BLK_CGROUP
966 tsk->throttle_queue = NULL;
967 tsk->use_memdelay = 0;
968#endif
969
970#ifdef CONFIG_MEMCG
971 tsk->active_memcg = NULL;
972#endif
973 return tsk;
974
975free_stack:
976 free_thread_stack(tsk);
977free_tsk:
978 free_task_struct(tsk);
979 return NULL;
980}
981
982__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
983
984static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
985
986static int __init coredump_filter_setup(char *s)
987{
988 default_dump_filter =
989 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
990 MMF_DUMP_FILTER_MASK;
991 return 1;
992}
993
994__setup("coredump_filter=", coredump_filter_setup);
995
996#include <linux/init_task.h>
997
998static void mm_init_aio(struct mm_struct *mm)
999{
1000#ifdef CONFIG_AIO
1001 spin_lock_init(&mm->ioctx_lock);
1002 mm->ioctx_table = NULL;
1003#endif
1004}
1005
1006static __always_inline void mm_clear_owner(struct mm_struct *mm,
1007 struct task_struct *p)
1008{
1009#ifdef CONFIG_MEMCG
1010 if (mm->owner == p)
1011 WRITE_ONCE(mm->owner, NULL);
1012#endif
1013}
1014
1015static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1016{
1017#ifdef CONFIG_MEMCG
1018 mm->owner = p;
1019#endif
1020}
1021
1022static void mm_init_pasid(struct mm_struct *mm)
1023{
1024#ifdef CONFIG_IOMMU_SUPPORT
1025 mm->pasid = INIT_PASID;
1026#endif
1027}
1028
1029static void mm_init_uprobes_state(struct mm_struct *mm)
1030{
1031#ifdef CONFIG_UPROBES
1032 mm->uprobes_state.xol_area = NULL;
1033#endif
1034}
1035
1036static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1037 struct user_namespace *user_ns)
1038{
1039 mm->mmap = NULL;
1040 mm->mm_rb = RB_ROOT;
1041 mm->vmacache_seqnum = 0;
1042 atomic_set(&mm->mm_users, 1);
1043 atomic_set(&mm->mm_count, 1);
1044 seqcount_init(&mm->write_protect_seq);
1045 mmap_init_lock(mm);
1046 INIT_LIST_HEAD(&mm->mmlist);
1047 mm_pgtables_bytes_init(mm);
1048 mm->map_count = 0;
1049 mm->locked_vm = 0;
1050 atomic64_set(&mm->pinned_vm, 0);
1051 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1052 spin_lock_init(&mm->page_table_lock);
1053 spin_lock_init(&mm->arg_lock);
1054 mm_init_cpumask(mm);
1055 mm_init_aio(mm);
1056 mm_init_owner(mm, p);
1057 mm_init_pasid(mm);
1058 RCU_INIT_POINTER(mm->exe_file, NULL);
1059 mmu_notifier_subscriptions_init(mm);
1060 init_tlb_flush_pending(mm);
1061#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1062 mm->pmd_huge_pte = NULL;
1063#endif
1064 mm_init_uprobes_state(mm);
1065 hugetlb_count_init(mm);
1066
1067 if (current->mm) {
1068 mm->flags = current->mm->flags & MMF_INIT_MASK;
1069 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1070 } else {
1071 mm->flags = default_dump_filter;
1072 mm->def_flags = 0;
1073 }
1074
1075 if (mm_alloc_pgd(mm))
1076 goto fail_nopgd;
1077
1078 if (init_new_context(p, mm))
1079 goto fail_nocontext;
1080
1081 mm->user_ns = get_user_ns(user_ns);
1082 return mm;
1083
1084fail_nocontext:
1085 mm_free_pgd(mm);
1086fail_nopgd:
1087 free_mm(mm);
1088 return NULL;
1089}
1090
1091/*
1092 * Allocate and initialize an mm_struct.
1093 */
1094struct mm_struct *mm_alloc(void)
1095{
1096 struct mm_struct *mm;
1097
1098 mm = allocate_mm();
1099 if (!mm)
1100 return NULL;
1101
1102 memset(mm, 0, sizeof(*mm));
1103 return mm_init(mm, current, current_user_ns());
1104}
1105
1106static inline void __mmput(struct mm_struct *mm)
1107{
1108 VM_BUG_ON(atomic_read(&mm->mm_users));
1109
1110 uprobe_clear_state(mm);
1111 exit_aio(mm);
1112 ksm_exit(mm);
1113 khugepaged_exit(mm); /* must run before exit_mmap */
1114 exit_mmap(mm);
1115 mm_put_huge_zero_page(mm);
1116 set_mm_exe_file(mm, NULL);
1117 if (!list_empty(&mm->mmlist)) {
1118 spin_lock(&mmlist_lock);
1119 list_del(&mm->mmlist);
1120 spin_unlock(&mmlist_lock);
1121 }
1122 if (mm->binfmt)
1123 module_put(mm->binfmt->module);
1124 mmdrop(mm);
1125}
1126
1127/*
1128 * Decrement the use count and release all resources for an mm.
1129 */
1130void mmput(struct mm_struct *mm)
1131{
1132 might_sleep();
1133
1134 if (atomic_dec_and_test(&mm->mm_users))
1135 __mmput(mm);
1136}
1137EXPORT_SYMBOL_GPL(mmput);
1138
1139#ifdef CONFIG_MMU
1140static void mmput_async_fn(struct work_struct *work)
1141{
1142 struct mm_struct *mm = container_of(work, struct mm_struct,
1143 async_put_work);
1144
1145 __mmput(mm);
1146}
1147
1148void mmput_async(struct mm_struct *mm)
1149{
1150 if (atomic_dec_and_test(&mm->mm_users)) {
1151 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1152 schedule_work(&mm->async_put_work);
1153 }
1154}
1155#endif
1156
1157/**
1158 * set_mm_exe_file - change a reference to the mm's executable file
1159 *
1160 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1161 *
1162 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1163 * invocations: in mmput() nobody alive left, in execve task is single
1164 * threaded.
1165 *
1166 * Can only fail if new_exe_file != NULL.
1167 */
1168int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1169{
1170 struct file *old_exe_file;
1171
1172 /*
1173 * It is safe to dereference the exe_file without RCU as
1174 * this function is only called if nobody else can access
1175 * this mm -- see comment above for justification.
1176 */
1177 old_exe_file = rcu_dereference_raw(mm->exe_file);
1178
1179 if (new_exe_file) {
1180 /*
1181 * We expect the caller (i.e., sys_execve) to already denied
1182 * write access, so this is unlikely to fail.
1183 */
1184 if (unlikely(deny_write_access(new_exe_file)))
1185 return -EACCES;
1186 get_file(new_exe_file);
1187 }
1188 rcu_assign_pointer(mm->exe_file, new_exe_file);
1189 if (old_exe_file) {
1190 allow_write_access(old_exe_file);
1191 fput(old_exe_file);
1192 }
1193 return 0;
1194}
1195
1196/**
1197 * replace_mm_exe_file - replace a reference to the mm's executable file
1198 *
1199 * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1200 * dealing with concurrent invocation and without grabbing the mmap lock in
1201 * write mode.
1202 *
1203 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1204 */
1205int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1206{
1207 struct vm_area_struct *vma;
1208 struct file *old_exe_file;
1209 int ret = 0;
1210
1211 /* Forbid mm->exe_file change if old file still mapped. */
1212 old_exe_file = get_mm_exe_file(mm);
1213 if (old_exe_file) {
1214 mmap_read_lock(mm);
1215 for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) {
1216 if (!vma->vm_file)
1217 continue;
1218 if (path_equal(&vma->vm_file->f_path,
1219 &old_exe_file->f_path))
1220 ret = -EBUSY;
1221 }
1222 mmap_read_unlock(mm);
1223 fput(old_exe_file);
1224 if (ret)
1225 return ret;
1226 }
1227
1228 /* set the new file, lockless */
1229 ret = deny_write_access(new_exe_file);
1230 if (ret)
1231 return -EACCES;
1232 get_file(new_exe_file);
1233
1234 old_exe_file = xchg(&mm->exe_file, new_exe_file);
1235 if (old_exe_file) {
1236 /*
1237 * Don't race with dup_mmap() getting the file and disallowing
1238 * write access while someone might open the file writable.
1239 */
1240 mmap_read_lock(mm);
1241 allow_write_access(old_exe_file);
1242 fput(old_exe_file);
1243 mmap_read_unlock(mm);
1244 }
1245 return 0;
1246}
1247
1248/**
1249 * get_mm_exe_file - acquire a reference to the mm's executable file
1250 *
1251 * Returns %NULL if mm has no associated executable file.
1252 * User must release file via fput().
1253 */
1254struct file *get_mm_exe_file(struct mm_struct *mm)
1255{
1256 struct file *exe_file;
1257
1258 rcu_read_lock();
1259 exe_file = rcu_dereference(mm->exe_file);
1260 if (exe_file && !get_file_rcu(exe_file))
1261 exe_file = NULL;
1262 rcu_read_unlock();
1263 return exe_file;
1264}
1265
1266/**
1267 * get_task_exe_file - acquire a reference to the task's executable file
1268 *
1269 * Returns %NULL if task's mm (if any) has no associated executable file or
1270 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1271 * User must release file via fput().
1272 */
1273struct file *get_task_exe_file(struct task_struct *task)
1274{
1275 struct file *exe_file = NULL;
1276 struct mm_struct *mm;
1277
1278 task_lock(task);
1279 mm = task->mm;
1280 if (mm) {
1281 if (!(task->flags & PF_KTHREAD))
1282 exe_file = get_mm_exe_file(mm);
1283 }
1284 task_unlock(task);
1285 return exe_file;
1286}
1287
1288/**
1289 * get_task_mm - acquire a reference to the task's mm
1290 *
1291 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1292 * this kernel workthread has transiently adopted a user mm with use_mm,
1293 * to do its AIO) is not set and if so returns a reference to it, after
1294 * bumping up the use count. User must release the mm via mmput()
1295 * after use. Typically used by /proc and ptrace.
1296 */
1297struct mm_struct *get_task_mm(struct task_struct *task)
1298{
1299 struct mm_struct *mm;
1300
1301 task_lock(task);
1302 mm = task->mm;
1303 if (mm) {
1304 if (task->flags & PF_KTHREAD)
1305 mm = NULL;
1306 else
1307 mmget(mm);
1308 }
1309 task_unlock(task);
1310 return mm;
1311}
1312EXPORT_SYMBOL_GPL(get_task_mm);
1313
1314struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1315{
1316 struct mm_struct *mm;
1317 int err;
1318
1319 err = down_read_killable(&task->signal->exec_update_lock);
1320 if (err)
1321 return ERR_PTR(err);
1322
1323 mm = get_task_mm(task);
1324 if (mm && mm != current->mm &&
1325 !ptrace_may_access(task, mode)) {
1326 mmput(mm);
1327 mm = ERR_PTR(-EACCES);
1328 }
1329 up_read(&task->signal->exec_update_lock);
1330
1331 return mm;
1332}
1333
1334static void complete_vfork_done(struct task_struct *tsk)
1335{
1336 struct completion *vfork;
1337
1338 task_lock(tsk);
1339 vfork = tsk->vfork_done;
1340 if (likely(vfork)) {
1341 tsk->vfork_done = NULL;
1342 complete(vfork);
1343 }
1344 task_unlock(tsk);
1345}
1346
1347static int wait_for_vfork_done(struct task_struct *child,
1348 struct completion *vfork)
1349{
1350 int killed;
1351
1352 freezer_do_not_count();
1353 cgroup_enter_frozen();
1354 killed = wait_for_completion_killable(vfork);
1355 cgroup_leave_frozen(false);
1356 freezer_count();
1357
1358 if (killed) {
1359 task_lock(child);
1360 child->vfork_done = NULL;
1361 task_unlock(child);
1362 }
1363
1364 put_task_struct(child);
1365 return killed;
1366}
1367
1368/* Please note the differences between mmput and mm_release.
1369 * mmput is called whenever we stop holding onto a mm_struct,
1370 * error success whatever.
1371 *
1372 * mm_release is called after a mm_struct has been removed
1373 * from the current process.
1374 *
1375 * This difference is important for error handling, when we
1376 * only half set up a mm_struct for a new process and need to restore
1377 * the old one. Because we mmput the new mm_struct before
1378 * restoring the old one. . .
1379 * Eric Biederman 10 January 1998
1380 */
1381static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1382{
1383 uprobe_free_utask(tsk);
1384
1385 /* Get rid of any cached register state */
1386 deactivate_mm(tsk, mm);
1387
1388 /*
1389 * Signal userspace if we're not exiting with a core dump
1390 * because we want to leave the value intact for debugging
1391 * purposes.
1392 */
1393 if (tsk->clear_child_tid) {
1394 if (atomic_read(&mm->mm_users) > 1) {
1395 /*
1396 * We don't check the error code - if userspace has
1397 * not set up a proper pointer then tough luck.
1398 */
1399 put_user(0, tsk->clear_child_tid);
1400 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1401 1, NULL, NULL, 0, 0);
1402 }
1403 tsk->clear_child_tid = NULL;
1404 }
1405
1406 /*
1407 * All done, finally we can wake up parent and return this mm to him.
1408 * Also kthread_stop() uses this completion for synchronization.
1409 */
1410 if (tsk->vfork_done)
1411 complete_vfork_done(tsk);
1412}
1413
1414void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1415{
1416 futex_exit_release(tsk);
1417 mm_release(tsk, mm);
1418}
1419
1420void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1421{
1422 futex_exec_release(tsk);
1423 mm_release(tsk, mm);
1424}
1425
1426/**
1427 * dup_mm() - duplicates an existing mm structure
1428 * @tsk: the task_struct with which the new mm will be associated.
1429 * @oldmm: the mm to duplicate.
1430 *
1431 * Allocates a new mm structure and duplicates the provided @oldmm structure
1432 * content into it.
1433 *
1434 * Return: the duplicated mm or NULL on failure.
1435 */
1436static struct mm_struct *dup_mm(struct task_struct *tsk,
1437 struct mm_struct *oldmm)
1438{
1439 struct mm_struct *mm;
1440 int err;
1441
1442 mm = allocate_mm();
1443 if (!mm)
1444 goto fail_nomem;
1445
1446 memcpy(mm, oldmm, sizeof(*mm));
1447
1448 if (!mm_init(mm, tsk, mm->user_ns))
1449 goto fail_nomem;
1450
1451 err = dup_mmap(mm, oldmm);
1452 if (err)
1453 goto free_pt;
1454
1455 mm->hiwater_rss = get_mm_rss(mm);
1456 mm->hiwater_vm = mm->total_vm;
1457
1458 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1459 goto free_pt;
1460
1461 return mm;
1462
1463free_pt:
1464 /* don't put binfmt in mmput, we haven't got module yet */
1465 mm->binfmt = NULL;
1466 mm_init_owner(mm, NULL);
1467 mmput(mm);
1468
1469fail_nomem:
1470 return NULL;
1471}
1472
1473static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1474{
1475 struct mm_struct *mm, *oldmm;
1476
1477 tsk->min_flt = tsk->maj_flt = 0;
1478 tsk->nvcsw = tsk->nivcsw = 0;
1479#ifdef CONFIG_DETECT_HUNG_TASK
1480 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1481 tsk->last_switch_time = 0;
1482#endif
1483
1484 tsk->mm = NULL;
1485 tsk->active_mm = NULL;
1486
1487 /*
1488 * Are we cloning a kernel thread?
1489 *
1490 * We need to steal a active VM for that..
1491 */
1492 oldmm = current->mm;
1493 if (!oldmm)
1494 return 0;
1495
1496 /* initialize the new vmacache entries */
1497 vmacache_flush(tsk);
1498
1499 if (clone_flags & CLONE_VM) {
1500 mmget(oldmm);
1501 mm = oldmm;
1502 } else {
1503 mm = dup_mm(tsk, current->mm);
1504 if (!mm)
1505 return -ENOMEM;
1506 }
1507
1508 tsk->mm = mm;
1509 tsk->active_mm = mm;
1510 return 0;
1511}
1512
1513static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1514{
1515 struct fs_struct *fs = current->fs;
1516 if (clone_flags & CLONE_FS) {
1517 /* tsk->fs is already what we want */
1518 spin_lock(&fs->lock);
1519 if (fs->in_exec) {
1520 spin_unlock(&fs->lock);
1521 return -EAGAIN;
1522 }
1523 fs->users++;
1524 spin_unlock(&fs->lock);
1525 return 0;
1526 }
1527 tsk->fs = copy_fs_struct(fs);
1528 if (!tsk->fs)
1529 return -ENOMEM;
1530 return 0;
1531}
1532
1533static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1534{
1535 struct files_struct *oldf, *newf;
1536 int error = 0;
1537
1538 /*
1539 * A background process may not have any files ...
1540 */
1541 oldf = current->files;
1542 if (!oldf)
1543 goto out;
1544
1545 if (clone_flags & CLONE_FILES) {
1546 atomic_inc(&oldf->count);
1547 goto out;
1548 }
1549
1550 newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1551 if (!newf)
1552 goto out;
1553
1554 tsk->files = newf;
1555 error = 0;
1556out:
1557 return error;
1558}
1559
1560static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1561{
1562 struct sighand_struct *sig;
1563
1564 if (clone_flags & CLONE_SIGHAND) {
1565 refcount_inc(&current->sighand->count);
1566 return 0;
1567 }
1568 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1569 RCU_INIT_POINTER(tsk->sighand, sig);
1570 if (!sig)
1571 return -ENOMEM;
1572
1573 refcount_set(&sig->count, 1);
1574 spin_lock_irq(&current->sighand->siglock);
1575 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1576 spin_unlock_irq(&current->sighand->siglock);
1577
1578 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1579 if (clone_flags & CLONE_CLEAR_SIGHAND)
1580 flush_signal_handlers(tsk, 0);
1581
1582 return 0;
1583}
1584
1585void __cleanup_sighand(struct sighand_struct *sighand)
1586{
1587 if (refcount_dec_and_test(&sighand->count)) {
1588 signalfd_cleanup(sighand);
1589 /*
1590 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1591 * without an RCU grace period, see __lock_task_sighand().
1592 */
1593 kmem_cache_free(sighand_cachep, sighand);
1594 }
1595}
1596
1597/*
1598 * Initialize POSIX timer handling for a thread group.
1599 */
1600static void posix_cpu_timers_init_group(struct signal_struct *sig)
1601{
1602 struct posix_cputimers *pct = &sig->posix_cputimers;
1603 unsigned long cpu_limit;
1604
1605 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1606 posix_cputimers_group_init(pct, cpu_limit);
1607}
1608
1609static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1610{
1611 struct signal_struct *sig;
1612
1613 if (clone_flags & CLONE_THREAD)
1614 return 0;
1615
1616 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1617 tsk->signal = sig;
1618 if (!sig)
1619 return -ENOMEM;
1620
1621 sig->nr_threads = 1;
1622 atomic_set(&sig->live, 1);
1623 refcount_set(&sig->sigcnt, 1);
1624
1625 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1626 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1627 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1628
1629 init_waitqueue_head(&sig->wait_chldexit);
1630 sig->curr_target = tsk;
1631 init_sigpending(&sig->shared_pending);
1632 INIT_HLIST_HEAD(&sig->multiprocess);
1633 seqlock_init(&sig->stats_lock);
1634 prev_cputime_init(&sig->prev_cputime);
1635
1636#ifdef CONFIG_POSIX_TIMERS
1637 INIT_LIST_HEAD(&sig->posix_timers);
1638 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1639 sig->real_timer.function = it_real_fn;
1640#endif
1641
1642 task_lock(current->group_leader);
1643 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1644 task_unlock(current->group_leader);
1645
1646 posix_cpu_timers_init_group(sig);
1647
1648 tty_audit_fork(sig);
1649 sched_autogroup_fork(sig);
1650
1651 sig->oom_score_adj = current->signal->oom_score_adj;
1652 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1653
1654 mutex_init(&sig->cred_guard_mutex);
1655 init_rwsem(&sig->exec_update_lock);
1656
1657 return 0;
1658}
1659
1660static void copy_seccomp(struct task_struct *p)
1661{
1662#ifdef CONFIG_SECCOMP
1663 /*
1664 * Must be called with sighand->lock held, which is common to
1665 * all threads in the group. Holding cred_guard_mutex is not
1666 * needed because this new task is not yet running and cannot
1667 * be racing exec.
1668 */
1669 assert_spin_locked(&current->sighand->siglock);
1670
1671 /* Ref-count the new filter user, and assign it. */
1672 get_seccomp_filter(current);
1673 p->seccomp = current->seccomp;
1674
1675 /*
1676 * Explicitly enable no_new_privs here in case it got set
1677 * between the task_struct being duplicated and holding the
1678 * sighand lock. The seccomp state and nnp must be in sync.
1679 */
1680 if (task_no_new_privs(current))
1681 task_set_no_new_privs(p);
1682
1683 /*
1684 * If the parent gained a seccomp mode after copying thread
1685 * flags and between before we held the sighand lock, we have
1686 * to manually enable the seccomp thread flag here.
1687 */
1688 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1689 set_task_syscall_work(p, SECCOMP);
1690#endif
1691}
1692
1693SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1694{
1695 current->clear_child_tid = tidptr;
1696
1697 return task_pid_vnr(current);
1698}
1699
1700static void rt_mutex_init_task(struct task_struct *p)
1701{
1702 raw_spin_lock_init(&p->pi_lock);
1703#ifdef CONFIG_RT_MUTEXES
1704 p->pi_waiters = RB_ROOT_CACHED;
1705 p->pi_top_task = NULL;
1706 p->pi_blocked_on = NULL;
1707#endif
1708}
1709
1710static inline void init_task_pid_links(struct task_struct *task)
1711{
1712 enum pid_type type;
1713
1714 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1715 INIT_HLIST_NODE(&task->pid_links[type]);
1716}
1717
1718static inline void
1719init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1720{
1721 if (type == PIDTYPE_PID)
1722 task->thread_pid = pid;
1723 else
1724 task->signal->pids[type] = pid;
1725}
1726
1727static inline void rcu_copy_process(struct task_struct *p)
1728{
1729#ifdef CONFIG_PREEMPT_RCU
1730 p->rcu_read_lock_nesting = 0;
1731 p->rcu_read_unlock_special.s = 0;
1732 p->rcu_blocked_node = NULL;
1733 INIT_LIST_HEAD(&p->rcu_node_entry);
1734#endif /* #ifdef CONFIG_PREEMPT_RCU */
1735#ifdef CONFIG_TASKS_RCU
1736 p->rcu_tasks_holdout = false;
1737 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1738 p->rcu_tasks_idle_cpu = -1;
1739#endif /* #ifdef CONFIG_TASKS_RCU */
1740#ifdef CONFIG_TASKS_TRACE_RCU
1741 p->trc_reader_nesting = 0;
1742 p->trc_reader_special.s = 0;
1743 INIT_LIST_HEAD(&p->trc_holdout_list);
1744#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1745}
1746
1747struct pid *pidfd_pid(const struct file *file)
1748{
1749 if (file->f_op == &pidfd_fops)
1750 return file->private_data;
1751
1752 return ERR_PTR(-EBADF);
1753}
1754
1755static int pidfd_release(struct inode *inode, struct file *file)
1756{
1757 struct pid *pid = file->private_data;
1758
1759 file->private_data = NULL;
1760 put_pid(pid);
1761 return 0;
1762}
1763
1764#ifdef CONFIG_PROC_FS
1765/**
1766 * pidfd_show_fdinfo - print information about a pidfd
1767 * @m: proc fdinfo file
1768 * @f: file referencing a pidfd
1769 *
1770 * Pid:
1771 * This function will print the pid that a given pidfd refers to in the
1772 * pid namespace of the procfs instance.
1773 * If the pid namespace of the process is not a descendant of the pid
1774 * namespace of the procfs instance 0 will be shown as its pid. This is
1775 * similar to calling getppid() on a process whose parent is outside of
1776 * its pid namespace.
1777 *
1778 * NSpid:
1779 * If pid namespaces are supported then this function will also print
1780 * the pid of a given pidfd refers to for all descendant pid namespaces
1781 * starting from the current pid namespace of the instance, i.e. the
1782 * Pid field and the first entry in the NSpid field will be identical.
1783 * If the pid namespace of the process is not a descendant of the pid
1784 * namespace of the procfs instance 0 will be shown as its first NSpid
1785 * entry and no others will be shown.
1786 * Note that this differs from the Pid and NSpid fields in
1787 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1788 * the pid namespace of the procfs instance. The difference becomes
1789 * obvious when sending around a pidfd between pid namespaces from a
1790 * different branch of the tree, i.e. where no ancestral relation is
1791 * present between the pid namespaces:
1792 * - create two new pid namespaces ns1 and ns2 in the initial pid
1793 * namespace (also take care to create new mount namespaces in the
1794 * new pid namespace and mount procfs)
1795 * - create a process with a pidfd in ns1
1796 * - send pidfd from ns1 to ns2
1797 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1798 * have exactly one entry, which is 0
1799 */
1800static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
1801{
1802 struct pid *pid = f->private_data;
1803 struct pid_namespace *ns;
1804 pid_t nr = -1;
1805
1806 if (likely(pid_has_task(pid, PIDTYPE_PID))) {
1807 ns = proc_pid_ns(file_inode(m->file)->i_sb);
1808 nr = pid_nr_ns(pid, ns);
1809 }
1810
1811 seq_put_decimal_ll(m, "Pid:\t", nr);
1812
1813#ifdef CONFIG_PID_NS
1814 seq_put_decimal_ll(m, "\nNSpid:\t", nr);
1815 if (nr > 0) {
1816 int i;
1817
1818 /* If nr is non-zero it means that 'pid' is valid and that
1819 * ns, i.e. the pid namespace associated with the procfs
1820 * instance, is in the pid namespace hierarchy of pid.
1821 * Start at one below the already printed level.
1822 */
1823 for (i = ns->level + 1; i <= pid->level; i++)
1824 seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
1825 }
1826#endif
1827 seq_putc(m, '\n');
1828}
1829#endif
1830
1831/*
1832 * Poll support for process exit notification.
1833 */
1834static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
1835{
1836 struct pid *pid = file->private_data;
1837 __poll_t poll_flags = 0;
1838
1839 poll_wait(file, &pid->wait_pidfd, pts);
1840
1841 /*
1842 * Inform pollers only when the whole thread group exits.
1843 * If the thread group leader exits before all other threads in the
1844 * group, then poll(2) should block, similar to the wait(2) family.
1845 */
1846 if (thread_group_exited(pid))
1847 poll_flags = EPOLLIN | EPOLLRDNORM;
1848
1849 return poll_flags;
1850}
1851
1852const struct file_operations pidfd_fops = {
1853 .release = pidfd_release,
1854 .poll = pidfd_poll,
1855#ifdef CONFIG_PROC_FS
1856 .show_fdinfo = pidfd_show_fdinfo,
1857#endif
1858};
1859
1860static void __delayed_free_task(struct rcu_head *rhp)
1861{
1862 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1863
1864 free_task(tsk);
1865}
1866
1867static __always_inline void delayed_free_task(struct task_struct *tsk)
1868{
1869 if (IS_ENABLED(CONFIG_MEMCG))
1870 call_rcu(&tsk->rcu, __delayed_free_task);
1871 else
1872 free_task(tsk);
1873}
1874
1875static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1876{
1877 /* Skip if kernel thread */
1878 if (!tsk->mm)
1879 return;
1880
1881 /* Skip if spawning a thread or using vfork */
1882 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1883 return;
1884
1885 /* We need to synchronize with __set_oom_adj */
1886 mutex_lock(&oom_adj_mutex);
1887 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1888 /* Update the values in case they were changed after copy_signal */
1889 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1890 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1891 mutex_unlock(&oom_adj_mutex);
1892}
1893
1894/*
1895 * This creates a new process as a copy of the old one,
1896 * but does not actually start it yet.
1897 *
1898 * It copies the registers, and all the appropriate
1899 * parts of the process environment (as per the clone
1900 * flags). The actual kick-off is left to the caller.
1901 */
1902static __latent_entropy struct task_struct *copy_process(
1903 struct pid *pid,
1904 int trace,
1905 int node,
1906 struct kernel_clone_args *args)
1907{
1908 int pidfd = -1, retval;
1909 struct task_struct *p;
1910 struct multiprocess_signals delayed;
1911 struct file *pidfile = NULL;
1912 u64 clone_flags = args->flags;
1913 struct nsproxy *nsp = current->nsproxy;
1914
1915 /*
1916 * Don't allow sharing the root directory with processes in a different
1917 * namespace
1918 */
1919 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1920 return ERR_PTR(-EINVAL);
1921
1922 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1923 return ERR_PTR(-EINVAL);
1924
1925 /*
1926 * Thread groups must share signals as well, and detached threads
1927 * can only be started up within the thread group.
1928 */
1929 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1930 return ERR_PTR(-EINVAL);
1931
1932 /*
1933 * Shared signal handlers imply shared VM. By way of the above,
1934 * thread groups also imply shared VM. Blocking this case allows
1935 * for various simplifications in other code.
1936 */
1937 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1938 return ERR_PTR(-EINVAL);
1939
1940 /*
1941 * Siblings of global init remain as zombies on exit since they are
1942 * not reaped by their parent (swapper). To solve this and to avoid
1943 * multi-rooted process trees, prevent global and container-inits
1944 * from creating siblings.
1945 */
1946 if ((clone_flags & CLONE_PARENT) &&
1947 current->signal->flags & SIGNAL_UNKILLABLE)
1948 return ERR_PTR(-EINVAL);
1949
1950 /*
1951 * If the new process will be in a different pid or user namespace
1952 * do not allow it to share a thread group with the forking task.
1953 */
1954 if (clone_flags & CLONE_THREAD) {
1955 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
1956 (task_active_pid_ns(current) != nsp->pid_ns_for_children))
1957 return ERR_PTR(-EINVAL);
1958 }
1959
1960 /*
1961 * If the new process will be in a different time namespace
1962 * do not allow it to share VM or a thread group with the forking task.
1963 */
1964 if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
1965 if (nsp->time_ns != nsp->time_ns_for_children)
1966 return ERR_PTR(-EINVAL);
1967 }
1968
1969 if (clone_flags & CLONE_PIDFD) {
1970 /*
1971 * - CLONE_DETACHED is blocked so that we can potentially
1972 * reuse it later for CLONE_PIDFD.
1973 * - CLONE_THREAD is blocked until someone really needs it.
1974 */
1975 if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
1976 return ERR_PTR(-EINVAL);
1977 }
1978
1979 /*
1980 * Force any signals received before this point to be delivered
1981 * before the fork happens. Collect up signals sent to multiple
1982 * processes that happen during the fork and delay them so that
1983 * they appear to happen after the fork.
1984 */
1985 sigemptyset(&delayed.signal);
1986 INIT_HLIST_NODE(&delayed.node);
1987
1988 spin_lock_irq(&current->sighand->siglock);
1989 if (!(clone_flags & CLONE_THREAD))
1990 hlist_add_head(&delayed.node, &current->signal->multiprocess);
1991 recalc_sigpending();
1992 spin_unlock_irq(&current->sighand->siglock);
1993 retval = -ERESTARTNOINTR;
1994 if (task_sigpending(current))
1995 goto fork_out;
1996
1997 retval = -ENOMEM;
1998 p = dup_task_struct(current, node);
1999 if (!p)
2000 goto fork_out;
2001 if (args->io_thread) {
2002 /*
2003 * Mark us an IO worker, and block any signal that isn't
2004 * fatal or STOP
2005 */
2006 p->flags |= PF_IO_WORKER;
2007 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2008 }
2009
2010 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2011 /*
2012 * Clear TID on mm_release()?
2013 */
2014 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2015
2016 ftrace_graph_init_task(p);
2017
2018 rt_mutex_init_task(p);
2019
2020 lockdep_assert_irqs_enabled();
2021#ifdef CONFIG_PROVE_LOCKING
2022 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2023#endif
2024 retval = copy_creds(p, clone_flags);
2025 if (retval < 0)
2026 goto bad_fork_free;
2027
2028 retval = -EAGAIN;
2029 if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2030 if (p->real_cred->user != INIT_USER &&
2031 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2032 goto bad_fork_cleanup_count;
2033 }
2034 current->flags &= ~PF_NPROC_EXCEEDED;
2035
2036 /*
2037 * If multiple threads are within copy_process(), then this check
2038 * triggers too late. This doesn't hurt, the check is only there
2039 * to stop root fork bombs.
2040 */
2041 retval = -EAGAIN;
2042 if (data_race(nr_threads >= max_threads))
2043 goto bad_fork_cleanup_count;
2044
2045 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2046 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2047 p->flags |= PF_FORKNOEXEC;
2048 INIT_LIST_HEAD(&p->children);
2049 INIT_LIST_HEAD(&p->sibling);
2050 rcu_copy_process(p);
2051 p->vfork_done = NULL;
2052 spin_lock_init(&p->alloc_lock);
2053
2054 init_sigpending(&p->pending);
2055
2056 p->utime = p->stime = p->gtime = 0;
2057#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2058 p->utimescaled = p->stimescaled = 0;
2059#endif
2060 prev_cputime_init(&p->prev_cputime);
2061
2062#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2063 seqcount_init(&p->vtime.seqcount);
2064 p->vtime.starttime = 0;
2065 p->vtime.state = VTIME_INACTIVE;
2066#endif
2067
2068#ifdef CONFIG_IO_URING
2069 p->io_uring = NULL;
2070#endif
2071
2072#if defined(SPLIT_RSS_COUNTING)
2073 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2074#endif
2075
2076 p->default_timer_slack_ns = current->timer_slack_ns;
2077
2078#ifdef CONFIG_PSI
2079 p->psi_flags = 0;
2080#endif
2081
2082 task_io_accounting_init(&p->ioac);
2083 acct_clear_integrals(p);
2084
2085 posix_cputimers_init(&p->posix_cputimers);
2086
2087 p->io_context = NULL;
2088 audit_set_context(p, NULL);
2089 cgroup_fork(p);
2090 if (p->flags & PF_KTHREAD) {
2091 if (!set_kthread_struct(p))
2092 goto bad_fork_cleanup_delayacct;
2093 }
2094#ifdef CONFIG_NUMA
2095 p->mempolicy = mpol_dup(p->mempolicy);
2096 if (IS_ERR(p->mempolicy)) {
2097 retval = PTR_ERR(p->mempolicy);
2098 p->mempolicy = NULL;
2099 goto bad_fork_cleanup_delayacct;
2100 }
2101#endif
2102#ifdef CONFIG_CPUSETS
2103 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2104 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2105 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2106#endif
2107#ifdef CONFIG_TRACE_IRQFLAGS
2108 memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2109 p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2110 p->irqtrace.softirq_enable_ip = _THIS_IP_;
2111 p->softirqs_enabled = 1;
2112 p->softirq_context = 0;
2113#endif
2114
2115 p->pagefault_disabled = 0;
2116
2117#ifdef CONFIG_LOCKDEP
2118 lockdep_init_task(p);
2119#endif
2120
2121#ifdef CONFIG_DEBUG_MUTEXES
2122 p->blocked_on = NULL; /* not blocked yet */
2123#endif
2124#ifdef CONFIG_BCACHE
2125 p->sequential_io = 0;
2126 p->sequential_io_avg = 0;
2127#endif
2128#ifdef CONFIG_BPF_SYSCALL
2129 RCU_INIT_POINTER(p->bpf_storage, NULL);
2130 p->bpf_ctx = NULL;
2131#endif
2132
2133 /* Perform scheduler related setup. Assign this task to a CPU. */
2134 retval = sched_fork(clone_flags, p);
2135 if (retval)
2136 goto bad_fork_cleanup_policy;
2137
2138 retval = perf_event_init_task(p, clone_flags);
2139 if (retval)
2140 goto bad_fork_cleanup_policy;
2141 retval = audit_alloc(p);
2142 if (retval)
2143 goto bad_fork_cleanup_perf;
2144 /* copy all the process information */
2145 shm_init_task(p);
2146 retval = security_task_alloc(p, clone_flags);
2147 if (retval)
2148 goto bad_fork_cleanup_audit;
2149 retval = copy_semundo(clone_flags, p);
2150 if (retval)
2151 goto bad_fork_cleanup_security;
2152 retval = copy_files(clone_flags, p);
2153 if (retval)
2154 goto bad_fork_cleanup_semundo;
2155 retval = copy_fs(clone_flags, p);
2156 if (retval)
2157 goto bad_fork_cleanup_files;
2158 retval = copy_sighand(clone_flags, p);
2159 if (retval)
2160 goto bad_fork_cleanup_fs;
2161 retval = copy_signal(clone_flags, p);
2162 if (retval)
2163 goto bad_fork_cleanup_sighand;
2164 retval = copy_mm(clone_flags, p);
2165 if (retval)
2166 goto bad_fork_cleanup_signal;
2167 retval = copy_namespaces(clone_flags, p);
2168 if (retval)
2169 goto bad_fork_cleanup_mm;
2170 retval = copy_io(clone_flags, p);
2171 if (retval)
2172 goto bad_fork_cleanup_namespaces;
2173 retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls);
2174 if (retval)
2175 goto bad_fork_cleanup_io;
2176
2177 stackleak_task_init(p);
2178
2179 if (pid != &init_struct_pid) {
2180 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2181 args->set_tid_size);
2182 if (IS_ERR(pid)) {
2183 retval = PTR_ERR(pid);
2184 goto bad_fork_cleanup_thread;
2185 }
2186 }
2187
2188 /*
2189 * This has to happen after we've potentially unshared the file
2190 * descriptor table (so that the pidfd doesn't leak into the child
2191 * if the fd table isn't shared).
2192 */
2193 if (clone_flags & CLONE_PIDFD) {
2194 retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2195 if (retval < 0)
2196 goto bad_fork_free_pid;
2197
2198 pidfd = retval;
2199
2200 pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2201 O_RDWR | O_CLOEXEC);
2202 if (IS_ERR(pidfile)) {
2203 put_unused_fd(pidfd);
2204 retval = PTR_ERR(pidfile);
2205 goto bad_fork_free_pid;
2206 }
2207 get_pid(pid); /* held by pidfile now */
2208
2209 retval = put_user(pidfd, args->pidfd);
2210 if (retval)
2211 goto bad_fork_put_pidfd;
2212 }
2213
2214#ifdef CONFIG_BLOCK
2215 p->plug = NULL;
2216#endif
2217 futex_init_task(p);
2218
2219 /*
2220 * sigaltstack should be cleared when sharing the same VM
2221 */
2222 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2223 sas_ss_reset(p);
2224
2225 /*
2226 * Syscall tracing and stepping should be turned off in the
2227 * child regardless of CLONE_PTRACE.
2228 */
2229 user_disable_single_step(p);
2230 clear_task_syscall_work(p, SYSCALL_TRACE);
2231#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2232 clear_task_syscall_work(p, SYSCALL_EMU);
2233#endif
2234 clear_tsk_latency_tracing(p);
2235
2236 /* ok, now we should be set up.. */
2237 p->pid = pid_nr(pid);
2238 if (clone_flags & CLONE_THREAD) {
2239 p->group_leader = current->group_leader;
2240 p->tgid = current->tgid;
2241 } else {
2242 p->group_leader = p;
2243 p->tgid = p->pid;
2244 }
2245
2246 p->nr_dirtied = 0;
2247 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2248 p->dirty_paused_when = 0;
2249
2250 p->pdeath_signal = 0;
2251 INIT_LIST_HEAD(&p->thread_group);
2252 p->task_works = NULL;
2253 clear_posix_cputimers_work(p);
2254
2255#ifdef CONFIG_KRETPROBES
2256 p->kretprobe_instances.first = NULL;
2257#endif
2258
2259 /*
2260 * Ensure that the cgroup subsystem policies allow the new process to be
2261 * forked. It should be noted that the new process's css_set can be changed
2262 * between here and cgroup_post_fork() if an organisation operation is in
2263 * progress.
2264 */
2265 retval = cgroup_can_fork(p, args);
2266 if (retval)
2267 goto bad_fork_put_pidfd;
2268
2269 /*
2270 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2271 * the new task on the correct runqueue. All this *before* the task
2272 * becomes visible.
2273 *
2274 * This isn't part of ->can_fork() because while the re-cloning is
2275 * cgroup specific, it unconditionally needs to place the task on a
2276 * runqueue.
2277 */
2278 sched_cgroup_fork(p, args);
2279
2280 /*
2281 * From this point on we must avoid any synchronous user-space
2282 * communication until we take the tasklist-lock. In particular, we do
2283 * not want user-space to be able to predict the process start-time by
2284 * stalling fork(2) after we recorded the start_time but before it is
2285 * visible to the system.
2286 */
2287
2288 p->start_time = ktime_get_ns();
2289 p->start_boottime = ktime_get_boottime_ns();
2290
2291 /*
2292 * Make it visible to the rest of the system, but dont wake it up yet.
2293 * Need tasklist lock for parent etc handling!
2294 */
2295 write_lock_irq(&tasklist_lock);
2296
2297 /* CLONE_PARENT re-uses the old parent */
2298 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2299 p->real_parent = current->real_parent;
2300 p->parent_exec_id = current->parent_exec_id;
2301 if (clone_flags & CLONE_THREAD)
2302 p->exit_signal = -1;
2303 else
2304 p->exit_signal = current->group_leader->exit_signal;
2305 } else {
2306 p->real_parent = current;
2307 p->parent_exec_id = current->self_exec_id;
2308 p->exit_signal = args->exit_signal;
2309 }
2310
2311 klp_copy_process(p);
2312
2313 sched_core_fork(p);
2314
2315 spin_lock(&current->sighand->siglock);
2316
2317 /*
2318 * Copy seccomp details explicitly here, in case they were changed
2319 * before holding sighand lock.
2320 */
2321 copy_seccomp(p);
2322
2323 rseq_fork(p, clone_flags);
2324
2325 /* Don't start children in a dying pid namespace */
2326 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2327 retval = -ENOMEM;
2328 goto bad_fork_cancel_cgroup;
2329 }
2330
2331 /* Let kill terminate clone/fork in the middle */
2332 if (fatal_signal_pending(current)) {
2333 retval = -EINTR;
2334 goto bad_fork_cancel_cgroup;
2335 }
2336
2337 init_task_pid_links(p);
2338 if (likely(p->pid)) {
2339 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2340
2341 init_task_pid(p, PIDTYPE_PID, pid);
2342 if (thread_group_leader(p)) {
2343 init_task_pid(p, PIDTYPE_TGID, pid);
2344 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2345 init_task_pid(p, PIDTYPE_SID, task_session(current));
2346
2347 if (is_child_reaper(pid)) {
2348 ns_of_pid(pid)->child_reaper = p;
2349 p->signal->flags |= SIGNAL_UNKILLABLE;
2350 }
2351 p->signal->shared_pending.signal = delayed.signal;
2352 p->signal->tty = tty_kref_get(current->signal->tty);
2353 /*
2354 * Inherit has_child_subreaper flag under the same
2355 * tasklist_lock with adding child to the process tree
2356 * for propagate_has_child_subreaper optimization.
2357 */
2358 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2359 p->real_parent->signal->is_child_subreaper;
2360 list_add_tail(&p->sibling, &p->real_parent->children);
2361 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2362 attach_pid(p, PIDTYPE_TGID);
2363 attach_pid(p, PIDTYPE_PGID);
2364 attach_pid(p, PIDTYPE_SID);
2365 __this_cpu_inc(process_counts);
2366 } else {
2367 current->signal->nr_threads++;
2368 atomic_inc(&current->signal->live);
2369 refcount_inc(&current->signal->sigcnt);
2370 task_join_group_stop(p);
2371 list_add_tail_rcu(&p->thread_group,
2372 &p->group_leader->thread_group);
2373 list_add_tail_rcu(&p->thread_node,
2374 &p->signal->thread_head);
2375 }
2376 attach_pid(p, PIDTYPE_PID);
2377 nr_threads++;
2378 }
2379 total_forks++;
2380 hlist_del_init(&delayed.node);
2381 spin_unlock(&current->sighand->siglock);
2382 syscall_tracepoint_update(p);
2383 write_unlock_irq(&tasklist_lock);
2384
2385 if (pidfile)
2386 fd_install(pidfd, pidfile);
2387
2388 proc_fork_connector(p);
2389 sched_post_fork(p);
2390 cgroup_post_fork(p, args);
2391 perf_event_fork(p);
2392
2393 trace_task_newtask(p, clone_flags);
2394 uprobe_copy_process(p, clone_flags);
2395
2396 copy_oom_score_adj(clone_flags, p);
2397
2398 return p;
2399
2400bad_fork_cancel_cgroup:
2401 sched_core_free(p);
2402 spin_unlock(&current->sighand->siglock);
2403 write_unlock_irq(&tasklist_lock);
2404 cgroup_cancel_fork(p, args);
2405bad_fork_put_pidfd:
2406 if (clone_flags & CLONE_PIDFD) {
2407 fput(pidfile);
2408 put_unused_fd(pidfd);
2409 }
2410bad_fork_free_pid:
2411 if (pid != &init_struct_pid)
2412 free_pid(pid);
2413bad_fork_cleanup_thread:
2414 exit_thread(p);
2415bad_fork_cleanup_io:
2416 if (p->io_context)
2417 exit_io_context(p);
2418bad_fork_cleanup_namespaces:
2419 exit_task_namespaces(p);
2420bad_fork_cleanup_mm:
2421 if (p->mm) {
2422 mm_clear_owner(p->mm, p);
2423 mmput(p->mm);
2424 }
2425bad_fork_cleanup_signal:
2426 if (!(clone_flags & CLONE_THREAD))
2427 free_signal_struct(p->signal);
2428bad_fork_cleanup_sighand:
2429 __cleanup_sighand(p->sighand);
2430bad_fork_cleanup_fs:
2431 exit_fs(p); /* blocking */
2432bad_fork_cleanup_files:
2433 exit_files(p); /* blocking */
2434bad_fork_cleanup_semundo:
2435 exit_sem(p);
2436bad_fork_cleanup_security:
2437 security_task_free(p);
2438bad_fork_cleanup_audit:
2439 audit_free(p);
2440bad_fork_cleanup_perf:
2441 perf_event_free_task(p);
2442bad_fork_cleanup_policy:
2443 lockdep_free_task(p);
2444#ifdef CONFIG_NUMA
2445 mpol_put(p->mempolicy);
2446#endif
2447bad_fork_cleanup_delayacct:
2448 delayacct_tsk_free(p);
2449bad_fork_cleanup_count:
2450 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2451 exit_creds(p);
2452bad_fork_free:
2453 WRITE_ONCE(p->__state, TASK_DEAD);
2454 put_task_stack(p);
2455 delayed_free_task(p);
2456fork_out:
2457 spin_lock_irq(&current->sighand->siglock);
2458 hlist_del_init(&delayed.node);
2459 spin_unlock_irq(&current->sighand->siglock);
2460 return ERR_PTR(retval);
2461}
2462
2463static inline void init_idle_pids(struct task_struct *idle)
2464{
2465 enum pid_type type;
2466
2467 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2468 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2469 init_task_pid(idle, type, &init_struct_pid);
2470 }
2471}
2472
2473struct task_struct * __init fork_idle(int cpu)
2474{
2475 struct task_struct *task;
2476 struct kernel_clone_args args = {
2477 .flags = CLONE_VM,
2478 };
2479
2480 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2481 if (!IS_ERR(task)) {
2482 init_idle_pids(task);
2483 init_idle(task, cpu);
2484 }
2485
2486 return task;
2487}
2488
2489struct mm_struct *copy_init_mm(void)
2490{
2491 return dup_mm(NULL, &init_mm);
2492}
2493
2494/*
2495 * This is like kernel_clone(), but shaved down and tailored to just
2496 * creating io_uring workers. It returns a created task, or an error pointer.
2497 * The returned task is inactive, and the caller must fire it up through
2498 * wake_up_new_task(p). All signals are blocked in the created task.
2499 */
2500struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2501{
2502 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2503 CLONE_IO;
2504 struct kernel_clone_args args = {
2505 .flags = ((lower_32_bits(flags) | CLONE_VM |
2506 CLONE_UNTRACED) & ~CSIGNAL),
2507 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2508 .stack = (unsigned long)fn,
2509 .stack_size = (unsigned long)arg,
2510 .io_thread = 1,
2511 };
2512
2513 return copy_process(NULL, 0, node, &args);
2514}
2515
2516/*
2517 * Ok, this is the main fork-routine.
2518 *
2519 * It copies the process, and if successful kick-starts
2520 * it and waits for it to finish using the VM if required.
2521 *
2522 * args->exit_signal is expected to be checked for sanity by the caller.
2523 */
2524pid_t kernel_clone(struct kernel_clone_args *args)
2525{
2526 u64 clone_flags = args->flags;
2527 struct completion vfork;
2528 struct pid *pid;
2529 struct task_struct *p;
2530 int trace = 0;
2531 pid_t nr;
2532
2533 /*
2534 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2535 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2536 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2537 * field in struct clone_args and it still doesn't make sense to have
2538 * them both point at the same memory location. Performing this check
2539 * here has the advantage that we don't need to have a separate helper
2540 * to check for legacy clone().
2541 */
2542 if ((args->flags & CLONE_PIDFD) &&
2543 (args->flags & CLONE_PARENT_SETTID) &&
2544 (args->pidfd == args->parent_tid))
2545 return -EINVAL;
2546
2547 /*
2548 * Determine whether and which event to report to ptracer. When
2549 * called from kernel_thread or CLONE_UNTRACED is explicitly
2550 * requested, no event is reported; otherwise, report if the event
2551 * for the type of forking is enabled.
2552 */
2553 if (!(clone_flags & CLONE_UNTRACED)) {
2554 if (clone_flags & CLONE_VFORK)
2555 trace = PTRACE_EVENT_VFORK;
2556 else if (args->exit_signal != SIGCHLD)
2557 trace = PTRACE_EVENT_CLONE;
2558 else
2559 trace = PTRACE_EVENT_FORK;
2560
2561 if (likely(!ptrace_event_enabled(current, trace)))
2562 trace = 0;
2563 }
2564
2565 p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2566 add_latent_entropy();
2567
2568 if (IS_ERR(p))
2569 return PTR_ERR(p);
2570
2571 /*
2572 * Do this prior waking up the new thread - the thread pointer
2573 * might get invalid after that point, if the thread exits quickly.
2574 */
2575 trace_sched_process_fork(current, p);
2576
2577 pid = get_task_pid(p, PIDTYPE_PID);
2578 nr = pid_vnr(pid);
2579
2580 if (clone_flags & CLONE_PARENT_SETTID)
2581 put_user(nr, args->parent_tid);
2582
2583 if (clone_flags & CLONE_VFORK) {
2584 p->vfork_done = &vfork;
2585 init_completion(&vfork);
2586 get_task_struct(p);
2587 }
2588
2589 wake_up_new_task(p);
2590
2591 /* forking complete and child started to run, tell ptracer */
2592 if (unlikely(trace))
2593 ptrace_event_pid(trace, pid);
2594
2595 if (clone_flags & CLONE_VFORK) {
2596 if (!wait_for_vfork_done(p, &vfork))
2597 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2598 }
2599
2600 put_pid(pid);
2601 return nr;
2602}
2603
2604/*
2605 * Create a kernel thread.
2606 */
2607pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2608{
2609 struct kernel_clone_args args = {
2610 .flags = ((lower_32_bits(flags) | CLONE_VM |
2611 CLONE_UNTRACED) & ~CSIGNAL),
2612 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2613 .stack = (unsigned long)fn,
2614 .stack_size = (unsigned long)arg,
2615 };
2616
2617 return kernel_clone(&args);
2618}
2619
2620#ifdef __ARCH_WANT_SYS_FORK
2621SYSCALL_DEFINE0(fork)
2622{
2623#ifdef CONFIG_MMU
2624 struct kernel_clone_args args = {
2625 .exit_signal = SIGCHLD,
2626 };
2627
2628 return kernel_clone(&args);
2629#else
2630 /* can not support in nommu mode */
2631 return -EINVAL;
2632#endif
2633}
2634#endif
2635
2636#ifdef __ARCH_WANT_SYS_VFORK
2637SYSCALL_DEFINE0(vfork)
2638{
2639 struct kernel_clone_args args = {
2640 .flags = CLONE_VFORK | CLONE_VM,
2641 .exit_signal = SIGCHLD,
2642 };
2643
2644 return kernel_clone(&args);
2645}
2646#endif
2647
2648#ifdef __ARCH_WANT_SYS_CLONE
2649#ifdef CONFIG_CLONE_BACKWARDS
2650SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2651 int __user *, parent_tidptr,
2652 unsigned long, tls,
2653 int __user *, child_tidptr)
2654#elif defined(CONFIG_CLONE_BACKWARDS2)
2655SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2656 int __user *, parent_tidptr,
2657 int __user *, child_tidptr,
2658 unsigned long, tls)
2659#elif defined(CONFIG_CLONE_BACKWARDS3)
2660SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2661 int, stack_size,
2662 int __user *, parent_tidptr,
2663 int __user *, child_tidptr,
2664 unsigned long, tls)
2665#else
2666SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2667 int __user *, parent_tidptr,
2668 int __user *, child_tidptr,
2669 unsigned long, tls)
2670#endif
2671{
2672 struct kernel_clone_args args = {
2673 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2674 .pidfd = parent_tidptr,
2675 .child_tid = child_tidptr,
2676 .parent_tid = parent_tidptr,
2677 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2678 .stack = newsp,
2679 .tls = tls,
2680 };
2681
2682 return kernel_clone(&args);
2683}
2684#endif
2685
2686#ifdef __ARCH_WANT_SYS_CLONE3
2687
2688noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2689 struct clone_args __user *uargs,
2690 size_t usize)
2691{
2692 int err;
2693 struct clone_args args;
2694 pid_t *kset_tid = kargs->set_tid;
2695
2696 BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2697 CLONE_ARGS_SIZE_VER0);
2698 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2699 CLONE_ARGS_SIZE_VER1);
2700 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2701 CLONE_ARGS_SIZE_VER2);
2702 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2703
2704 if (unlikely(usize > PAGE_SIZE))
2705 return -E2BIG;
2706 if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2707 return -EINVAL;
2708
2709 err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2710 if (err)
2711 return err;
2712
2713 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2714 return -EINVAL;
2715
2716 if (unlikely(!args.set_tid && args.set_tid_size > 0))
2717 return -EINVAL;
2718
2719 if (unlikely(args.set_tid && args.set_tid_size == 0))
2720 return -EINVAL;
2721
2722 /*
2723 * Verify that higher 32bits of exit_signal are unset and that
2724 * it is a valid signal
2725 */
2726 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2727 !valid_signal(args.exit_signal)))
2728 return -EINVAL;
2729
2730 if ((args.flags & CLONE_INTO_CGROUP) &&
2731 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2732 return -EINVAL;
2733
2734 *kargs = (struct kernel_clone_args){
2735 .flags = args.flags,
2736 .pidfd = u64_to_user_ptr(args.pidfd),
2737 .child_tid = u64_to_user_ptr(args.child_tid),
2738 .parent_tid = u64_to_user_ptr(args.parent_tid),
2739 .exit_signal = args.exit_signal,
2740 .stack = args.stack,
2741 .stack_size = args.stack_size,
2742 .tls = args.tls,
2743 .set_tid_size = args.set_tid_size,
2744 .cgroup = args.cgroup,
2745 };
2746
2747 if (args.set_tid &&
2748 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
2749 (kargs->set_tid_size * sizeof(pid_t))))
2750 return -EFAULT;
2751
2752 kargs->set_tid = kset_tid;
2753
2754 return 0;
2755}
2756
2757/**
2758 * clone3_stack_valid - check and prepare stack
2759 * @kargs: kernel clone args
2760 *
2761 * Verify that the stack arguments userspace gave us are sane.
2762 * In addition, set the stack direction for userspace since it's easy for us to
2763 * determine.
2764 */
2765static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
2766{
2767 if (kargs->stack == 0) {
2768 if (kargs->stack_size > 0)
2769 return false;
2770 } else {
2771 if (kargs->stack_size == 0)
2772 return false;
2773
2774 if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
2775 return false;
2776
2777#if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2778 kargs->stack += kargs->stack_size;
2779#endif
2780 }
2781
2782 return true;
2783}
2784
2785static bool clone3_args_valid(struct kernel_clone_args *kargs)
2786{
2787 /* Verify that no unknown flags are passed along. */
2788 if (kargs->flags &
2789 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
2790 return false;
2791
2792 /*
2793 * - make the CLONE_DETACHED bit reusable for clone3
2794 * - make the CSIGNAL bits reusable for clone3
2795 */
2796 if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
2797 return false;
2798
2799 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
2800 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
2801 return false;
2802
2803 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
2804 kargs->exit_signal)
2805 return false;
2806
2807 if (!clone3_stack_valid(kargs))
2808 return false;
2809
2810 return true;
2811}
2812
2813/**
2814 * clone3 - create a new process with specific properties
2815 * @uargs: argument structure
2816 * @size: size of @uargs
2817 *
2818 * clone3() is the extensible successor to clone()/clone2().
2819 * It takes a struct as argument that is versioned by its size.
2820 *
2821 * Return: On success, a positive PID for the child process.
2822 * On error, a negative errno number.
2823 */
2824SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
2825{
2826 int err;
2827
2828 struct kernel_clone_args kargs;
2829 pid_t set_tid[MAX_PID_NS_LEVEL];
2830
2831 kargs.set_tid = set_tid;
2832
2833 err = copy_clone_args_from_user(&kargs, uargs, size);
2834 if (err)
2835 return err;
2836
2837 if (!clone3_args_valid(&kargs))
2838 return -EINVAL;
2839
2840 return kernel_clone(&kargs);
2841}
2842#endif
2843
2844void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2845{
2846 struct task_struct *leader, *parent, *child;
2847 int res;
2848
2849 read_lock(&tasklist_lock);
2850 leader = top = top->group_leader;
2851down:
2852 for_each_thread(leader, parent) {
2853 list_for_each_entry(child, &parent->children, sibling) {
2854 res = visitor(child, data);
2855 if (res) {
2856 if (res < 0)
2857 goto out;
2858 leader = child;
2859 goto down;
2860 }
2861up:
2862 ;
2863 }
2864 }
2865
2866 if (leader != top) {
2867 child = leader;
2868 parent = child->real_parent;
2869 leader = parent->group_leader;
2870 goto up;
2871 }
2872out:
2873 read_unlock(&tasklist_lock);
2874}
2875
2876#ifndef ARCH_MIN_MMSTRUCT_ALIGN
2877#define ARCH_MIN_MMSTRUCT_ALIGN 0
2878#endif
2879
2880static void sighand_ctor(void *data)
2881{
2882 struct sighand_struct *sighand = data;
2883
2884 spin_lock_init(&sighand->siglock);
2885 init_waitqueue_head(&sighand->signalfd_wqh);
2886}
2887
2888void __init proc_caches_init(void)
2889{
2890 unsigned int mm_size;
2891
2892 sighand_cachep = kmem_cache_create("sighand_cache",
2893 sizeof(struct sighand_struct), 0,
2894 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2895 SLAB_ACCOUNT, sighand_ctor);
2896 signal_cachep = kmem_cache_create("signal_cache",
2897 sizeof(struct signal_struct), 0,
2898 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2899 NULL);
2900 files_cachep = kmem_cache_create("files_cache",
2901 sizeof(struct files_struct), 0,
2902 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2903 NULL);
2904 fs_cachep = kmem_cache_create("fs_cache",
2905 sizeof(struct fs_struct), 0,
2906 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2907 NULL);
2908
2909 /*
2910 * The mm_cpumask is located at the end of mm_struct, and is
2911 * dynamically sized based on the maximum CPU number this system
2912 * can have, taking hotplug into account (nr_cpu_ids).
2913 */
2914 mm_size = sizeof(struct mm_struct) + cpumask_size();
2915
2916 mm_cachep = kmem_cache_create_usercopy("mm_struct",
2917 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
2918 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2919 offsetof(struct mm_struct, saved_auxv),
2920 sizeof_field(struct mm_struct, saved_auxv),
2921 NULL);
2922 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
2923 mmap_init();
2924 nsproxy_cache_init();
2925}
2926
2927/*
2928 * Check constraints on flags passed to the unshare system call.
2929 */
2930static int check_unshare_flags(unsigned long unshare_flags)
2931{
2932 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
2933 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
2934 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
2935 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
2936 CLONE_NEWTIME))
2937 return -EINVAL;
2938 /*
2939 * Not implemented, but pretend it works if there is nothing
2940 * to unshare. Note that unsharing the address space or the
2941 * signal handlers also need to unshare the signal queues (aka
2942 * CLONE_THREAD).
2943 */
2944 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
2945 if (!thread_group_empty(current))
2946 return -EINVAL;
2947 }
2948 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
2949 if (refcount_read(&current->sighand->count) > 1)
2950 return -EINVAL;
2951 }
2952 if (unshare_flags & CLONE_VM) {
2953 if (!current_is_single_threaded())
2954 return -EINVAL;
2955 }
2956
2957 return 0;
2958}
2959
2960/*
2961 * Unshare the filesystem structure if it is being shared
2962 */
2963static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
2964{
2965 struct fs_struct *fs = current->fs;
2966
2967 if (!(unshare_flags & CLONE_FS) || !fs)
2968 return 0;
2969
2970 /* don't need lock here; in the worst case we'll do useless copy */
2971 if (fs->users == 1)
2972 return 0;
2973
2974 *new_fsp = copy_fs_struct(fs);
2975 if (!*new_fsp)
2976 return -ENOMEM;
2977
2978 return 0;
2979}
2980
2981/*
2982 * Unshare file descriptor table if it is being shared
2983 */
2984int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
2985 struct files_struct **new_fdp)
2986{
2987 struct files_struct *fd = current->files;
2988 int error = 0;
2989
2990 if ((unshare_flags & CLONE_FILES) &&
2991 (fd && atomic_read(&fd->count) > 1)) {
2992 *new_fdp = dup_fd(fd, max_fds, &error);
2993 if (!*new_fdp)
2994 return error;
2995 }
2996
2997 return 0;
2998}
2999
3000/*
3001 * unshare allows a process to 'unshare' part of the process
3002 * context which was originally shared using clone. copy_*
3003 * functions used by kernel_clone() cannot be used here directly
3004 * because they modify an inactive task_struct that is being
3005 * constructed. Here we are modifying the current, active,
3006 * task_struct.
3007 */
3008int ksys_unshare(unsigned long unshare_flags)
3009{
3010 struct fs_struct *fs, *new_fs = NULL;
3011 struct files_struct *new_fd = NULL;
3012 struct cred *new_cred = NULL;
3013 struct nsproxy *new_nsproxy = NULL;
3014 int do_sysvsem = 0;
3015 int err;
3016
3017 /*
3018 * If unsharing a user namespace must also unshare the thread group
3019 * and unshare the filesystem root and working directories.
3020 */
3021 if (unshare_flags & CLONE_NEWUSER)
3022 unshare_flags |= CLONE_THREAD | CLONE_FS;
3023 /*
3024 * If unsharing vm, must also unshare signal handlers.
3025 */
3026 if (unshare_flags & CLONE_VM)
3027 unshare_flags |= CLONE_SIGHAND;
3028 /*
3029 * If unsharing a signal handlers, must also unshare the signal queues.
3030 */
3031 if (unshare_flags & CLONE_SIGHAND)
3032 unshare_flags |= CLONE_THREAD;
3033 /*
3034 * If unsharing namespace, must also unshare filesystem information.
3035 */
3036 if (unshare_flags & CLONE_NEWNS)
3037 unshare_flags |= CLONE_FS;
3038
3039 err = check_unshare_flags(unshare_flags);
3040 if (err)
3041 goto bad_unshare_out;
3042 /*
3043 * CLONE_NEWIPC must also detach from the undolist: after switching
3044 * to a new ipc namespace, the semaphore arrays from the old
3045 * namespace are unreachable.
3046 */
3047 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3048 do_sysvsem = 1;
3049 err = unshare_fs(unshare_flags, &new_fs);
3050 if (err)
3051 goto bad_unshare_out;
3052 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3053 if (err)
3054 goto bad_unshare_cleanup_fs;
3055 err = unshare_userns(unshare_flags, &new_cred);
3056 if (err)
3057 goto bad_unshare_cleanup_fd;
3058 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3059 new_cred, new_fs);
3060 if (err)
3061 goto bad_unshare_cleanup_cred;
3062
3063 if (new_cred) {
3064 err = set_cred_ucounts(new_cred);
3065 if (err)
3066 goto bad_unshare_cleanup_cred;
3067 }
3068
3069 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3070 if (do_sysvsem) {
3071 /*
3072 * CLONE_SYSVSEM is equivalent to sys_exit().
3073 */
3074 exit_sem(current);
3075 }
3076 if (unshare_flags & CLONE_NEWIPC) {
3077 /* Orphan segments in old ns (see sem above). */
3078 exit_shm(current);
3079 shm_init_task(current);
3080 }
3081
3082 if (new_nsproxy)
3083 switch_task_namespaces(current, new_nsproxy);
3084
3085 task_lock(current);
3086
3087 if (new_fs) {
3088 fs = current->fs;
3089 spin_lock(&fs->lock);
3090 current->fs = new_fs;
3091 if (--fs->users)
3092 new_fs = NULL;
3093 else
3094 new_fs = fs;
3095 spin_unlock(&fs->lock);
3096 }
3097
3098 if (new_fd)
3099 swap(current->files, new_fd);
3100
3101 task_unlock(current);
3102
3103 if (new_cred) {
3104 /* Install the new user namespace */
3105 commit_creds(new_cred);
3106 new_cred = NULL;
3107 }
3108 }
3109
3110 perf_event_namespaces(current);
3111
3112bad_unshare_cleanup_cred:
3113 if (new_cred)
3114 put_cred(new_cred);
3115bad_unshare_cleanup_fd:
3116 if (new_fd)
3117 put_files_struct(new_fd);
3118
3119bad_unshare_cleanup_fs:
3120 if (new_fs)
3121 free_fs_struct(new_fs);
3122
3123bad_unshare_out:
3124 return err;
3125}
3126
3127SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3128{
3129 return ksys_unshare(unshare_flags);
3130}
3131
3132/*
3133 * Helper to unshare the files of the current task.
3134 * We don't want to expose copy_files internals to
3135 * the exec layer of the kernel.
3136 */
3137
3138int unshare_files(void)
3139{
3140 struct task_struct *task = current;
3141 struct files_struct *old, *copy = NULL;
3142 int error;
3143
3144 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, &copy);
3145 if (error || !copy)
3146 return error;
3147
3148 old = task->files;
3149 task_lock(task);
3150 task->files = copy;
3151 task_unlock(task);
3152 put_files_struct(old);
3153 return 0;
3154}
3155
3156int sysctl_max_threads(struct ctl_table *table, int write,
3157 void *buffer, size_t *lenp, loff_t *ppos)
3158{
3159 struct ctl_table t;
3160 int ret;
3161 int threads = max_threads;
3162 int min = 1;
3163 int max = MAX_THREADS;
3164
3165 t = *table;
3166 t.data = &threads;
3167 t.extra1 = &min;
3168 t.extra2 = &max;
3169
3170 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3171 if (ret || !write)
3172 return ret;
3173
3174 max_threads = threads;
3175
3176 return 0;
3177}