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