projects/linux·blob v5.11 · refs

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