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