projects/linux·blob v6.3-rc5 · refs

3319 lines · 80.0 KiB

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