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