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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/init.h> |
16 | #include <linux/unistd.h> |
17 | #include <linux/module.h> |
18 | #include <linux/vmalloc.h> |
19 | #include <linux/completion.h> |
20 | #include <linux/personality.h> |
21 | #include <linux/mempolicy.h> |
22 | #include <linux/sem.h> |
23 | #include <linux/file.h> |
24 | #include <linux/fdtable.h> |
25 | #include <linux/iocontext.h> |
26 | #include <linux/key.h> |
27 | #include <linux/binfmts.h> |
28 | #include <linux/mman.h> |
29 | #include <linux/mmu_notifier.h> |
30 | #include <linux/fs.h> |
31 | #include <linux/nsproxy.h> |
32 | #include <linux/capability.h> |
33 | #include <linux/cpu.h> |
34 | #include <linux/cgroup.h> |
35 | #include <linux/security.h> |
36 | #include <linux/hugetlb.h> |
37 | #include <linux/swap.h> |
38 | #include <linux/syscalls.h> |
39 | #include <linux/jiffies.h> |
40 | #include <linux/tracehook.h> |
41 | #include <linux/futex.h> |
42 | #include <linux/compat.h> |
43 | #include <linux/task_io_accounting_ops.h> |
44 | #include <linux/rcupdate.h> |
45 | #include <linux/ptrace.h> |
46 | #include <linux/mount.h> |
47 | #include <linux/audit.h> |
48 | #include <linux/memcontrol.h> |
49 | #include <linux/ftrace.h> |
50 | #include <linux/profile.h> |
51 | #include <linux/rmap.h> |
52 | #include <linux/ksm.h> |
53 | #include <linux/acct.h> |
54 | #include <linux/tsacct_kern.h> |
55 | #include <linux/cn_proc.h> |
56 | #include <linux/freezer.h> |
57 | #include <linux/delayacct.h> |
58 | #include <linux/taskstats_kern.h> |
59 | #include <linux/random.h> |
60 | #include <linux/tty.h> |
61 | #include <linux/proc_fs.h> |
62 | #include <linux/blkdev.h> |
63 | #include <linux/fs_struct.h> |
64 | #include <linux/magic.h> |
65 | #include <linux/perf_event.h> |
66 | #include <linux/posix-timers.h> |
67 | #include <linux/user-return-notifier.h> |
68 | #include <linux/oom.h> |
69 | |
70 | #include <asm/pgtable.h> |
71 | #include <asm/pgalloc.h> |
72 | #include <asm/uaccess.h> |
73 | #include <asm/mmu_context.h> |
74 | #include <asm/cacheflush.h> |
75 | #include <asm/tlbflush.h> |
76 | |
77 | #include <trace/events/sched.h> |
78 | |
79 | /* |
80 | * Protected counters by write_lock_irq(&tasklist_lock) |
81 | */ |
82 | unsigned long total_forks; /* Handle normal Linux uptimes. */ |
83 | int nr_threads; /* The idle threads do not count.. */ |
84 | |
85 | int max_threads; /* tunable limit on nr_threads */ |
86 | |
87 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; |
88 | |
89 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ |
90 | |
91 | #ifdef CONFIG_PROVE_RCU |
92 | int lockdep_tasklist_lock_is_held(void) |
93 | { |
94 | return lockdep_is_held(&tasklist_lock); |
95 | } |
96 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); |
97 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
98 | |
99 | int nr_processes(void) |
100 | { |
101 | int cpu; |
102 | int total = 0; |
103 | |
104 | for_each_possible_cpu(cpu) |
105 | total += per_cpu(process_counts, cpu); |
106 | |
107 | return total; |
108 | } |
109 | |
110 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR |
111 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) |
112 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) |
113 | static struct kmem_cache *task_struct_cachep; |
114 | #endif |
115 | |
116 | #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR |
117 | static inline struct thread_info *alloc_thread_info(struct task_struct *tsk) |
118 | { |
119 | #ifdef CONFIG_DEBUG_STACK_USAGE |
120 | gfp_t mask = GFP_KERNEL | __GFP_ZERO; |
121 | #else |
122 | gfp_t mask = GFP_KERNEL; |
123 | #endif |
124 | return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER); |
125 | } |
126 | |
127 | static inline void free_thread_info(struct thread_info *ti) |
128 | { |
129 | free_pages((unsigned long)ti, THREAD_SIZE_ORDER); |
130 | } |
131 | #endif |
132 | |
133 | /* SLAB cache for signal_struct structures (tsk->signal) */ |
134 | static struct kmem_cache *signal_cachep; |
135 | |
136 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ |
137 | struct kmem_cache *sighand_cachep; |
138 | |
139 | /* SLAB cache for files_struct structures (tsk->files) */ |
140 | struct kmem_cache *files_cachep; |
141 | |
142 | /* SLAB cache for fs_struct structures (tsk->fs) */ |
143 | struct kmem_cache *fs_cachep; |
144 | |
145 | /* SLAB cache for vm_area_struct structures */ |
146 | struct kmem_cache *vm_area_cachep; |
147 | |
148 | /* SLAB cache for mm_struct structures (tsk->mm) */ |
149 | static struct kmem_cache *mm_cachep; |
150 | |
151 | static void account_kernel_stack(struct thread_info *ti, int account) |
152 | { |
153 | struct zone *zone = page_zone(virt_to_page(ti)); |
154 | |
155 | mod_zone_page_state(zone, NR_KERNEL_STACK, account); |
156 | } |
157 | |
158 | void free_task(struct task_struct *tsk) |
159 | { |
160 | prop_local_destroy_single(&tsk->dirties); |
161 | account_kernel_stack(tsk->stack, -1); |
162 | free_thread_info(tsk->stack); |
163 | rt_mutex_debug_task_free(tsk); |
164 | ftrace_graph_exit_task(tsk); |
165 | free_task_struct(tsk); |
166 | } |
167 | EXPORT_SYMBOL(free_task); |
168 | |
169 | static inline void free_signal_struct(struct signal_struct *sig) |
170 | { |
171 | taskstats_tgid_free(sig); |
172 | kmem_cache_free(signal_cachep, sig); |
173 | } |
174 | |
175 | static inline void put_signal_struct(struct signal_struct *sig) |
176 | { |
177 | if (atomic_dec_and_test(&sig->sigcnt)) |
178 | free_signal_struct(sig); |
179 | } |
180 | |
181 | void __put_task_struct(struct task_struct *tsk) |
182 | { |
183 | WARN_ON(!tsk->exit_state); |
184 | WARN_ON(atomic_read(&tsk->usage)); |
185 | WARN_ON(tsk == current); |
186 | |
187 | exit_creds(tsk); |
188 | delayacct_tsk_free(tsk); |
189 | put_signal_struct(tsk->signal); |
190 | |
191 | if (!profile_handoff_task(tsk)) |
192 | free_task(tsk); |
193 | } |
194 | |
195 | /* |
196 | * macro override instead of weak attribute alias, to workaround |
197 | * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. |
198 | */ |
199 | #ifndef arch_task_cache_init |
200 | #define arch_task_cache_init() |
201 | #endif |
202 | |
203 | void __init fork_init(unsigned long mempages) |
204 | { |
205 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR |
206 | #ifndef ARCH_MIN_TASKALIGN |
207 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES |
208 | #endif |
209 | /* create a slab on which task_structs can be allocated */ |
210 | task_struct_cachep = |
211 | kmem_cache_create("task_struct", sizeof(struct task_struct), |
212 | ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); |
213 | #endif |
214 | |
215 | /* do the arch specific task caches init */ |
216 | arch_task_cache_init(); |
217 | |
218 | /* |
219 | * The default maximum number of threads is set to a safe |
220 | * value: the thread structures can take up at most half |
221 | * of memory. |
222 | */ |
223 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); |
224 | |
225 | /* |
226 | * we need to allow at least 20 threads to boot a system |
227 | */ |
228 | if(max_threads < 20) |
229 | max_threads = 20; |
230 | |
231 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; |
232 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |
233 | init_task.signal->rlim[RLIMIT_SIGPENDING] = |
234 | init_task.signal->rlim[RLIMIT_NPROC]; |
235 | } |
236 | |
237 | int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, |
238 | struct task_struct *src) |
239 | { |
240 | *dst = *src; |
241 | return 0; |
242 | } |
243 | |
244 | static struct task_struct *dup_task_struct(struct task_struct *orig) |
245 | { |
246 | struct task_struct *tsk; |
247 | struct thread_info *ti; |
248 | unsigned long *stackend; |
249 | |
250 | int err; |
251 | |
252 | prepare_to_copy(orig); |
253 | |
254 | tsk = alloc_task_struct(); |
255 | if (!tsk) |
256 | return NULL; |
257 | |
258 | ti = alloc_thread_info(tsk); |
259 | if (!ti) { |
260 | free_task_struct(tsk); |
261 | return NULL; |
262 | } |
263 | |
264 | err = arch_dup_task_struct(tsk, orig); |
265 | if (err) |
266 | goto out; |
267 | |
268 | tsk->stack = ti; |
269 | |
270 | err = prop_local_init_single(&tsk->dirties); |
271 | if (err) |
272 | goto out; |
273 | |
274 | setup_thread_stack(tsk, orig); |
275 | clear_user_return_notifier(tsk); |
276 | clear_tsk_need_resched(tsk); |
277 | stackend = end_of_stack(tsk); |
278 | *stackend = STACK_END_MAGIC; /* for overflow detection */ |
279 | |
280 | #ifdef CONFIG_CC_STACKPROTECTOR |
281 | tsk->stack_canary = get_random_int(); |
282 | #endif |
283 | |
284 | /* One for us, one for whoever does the "release_task()" (usually parent) */ |
285 | atomic_set(&tsk->usage,2); |
286 | atomic_set(&tsk->fs_excl, 0); |
287 | #ifdef CONFIG_BLK_DEV_IO_TRACE |
288 | tsk->btrace_seq = 0; |
289 | #endif |
290 | tsk->splice_pipe = NULL; |
291 | |
292 | account_kernel_stack(ti, 1); |
293 | |
294 | return tsk; |
295 | |
296 | out: |
297 | free_thread_info(ti); |
298 | free_task_struct(tsk); |
299 | return NULL; |
300 | } |
301 | |
302 | #ifdef CONFIG_MMU |
303 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) |
304 | { |
305 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; |
306 | struct rb_node **rb_link, *rb_parent; |
307 | int retval; |
308 | unsigned long charge; |
309 | struct mempolicy *pol; |
310 | |
311 | down_write(&oldmm->mmap_sem); |
312 | flush_cache_dup_mm(oldmm); |
313 | /* |
314 | * Not linked in yet - no deadlock potential: |
315 | */ |
316 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); |
317 | |
318 | mm->locked_vm = 0; |
319 | mm->mmap = NULL; |
320 | mm->mmap_cache = NULL; |
321 | mm->free_area_cache = oldmm->mmap_base; |
322 | mm->cached_hole_size = ~0UL; |
323 | mm->map_count = 0; |
324 | cpumask_clear(mm_cpumask(mm)); |
325 | mm->mm_rb = RB_ROOT; |
326 | rb_link = &mm->mm_rb.rb_node; |
327 | rb_parent = NULL; |
328 | pprev = &mm->mmap; |
329 | retval = ksm_fork(mm, oldmm); |
330 | if (retval) |
331 | goto out; |
332 | |
333 | prev = NULL; |
334 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { |
335 | struct file *file; |
336 | |
337 | if (mpnt->vm_flags & VM_DONTCOPY) { |
338 | long pages = vma_pages(mpnt); |
339 | mm->total_vm -= pages; |
340 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, |
341 | -pages); |
342 | continue; |
343 | } |
344 | charge = 0; |
345 | if (mpnt->vm_flags & VM_ACCOUNT) { |
346 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; |
347 | if (security_vm_enough_memory(len)) |
348 | goto fail_nomem; |
349 | charge = len; |
350 | } |
351 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
352 | if (!tmp) |
353 | goto fail_nomem; |
354 | *tmp = *mpnt; |
355 | INIT_LIST_HEAD(&tmp->anon_vma_chain); |
356 | pol = mpol_dup(vma_policy(mpnt)); |
357 | retval = PTR_ERR(pol); |
358 | if (IS_ERR(pol)) |
359 | goto fail_nomem_policy; |
360 | vma_set_policy(tmp, pol); |
361 | tmp->vm_mm = mm; |
362 | if (anon_vma_fork(tmp, mpnt)) |
363 | goto fail_nomem_anon_vma_fork; |
364 | tmp->vm_flags &= ~VM_LOCKED; |
365 | tmp->vm_next = tmp->vm_prev = NULL; |
366 | file = tmp->vm_file; |
367 | if (file) { |
368 | struct inode *inode = file->f_path.dentry->d_inode; |
369 | struct address_space *mapping = file->f_mapping; |
370 | |
371 | get_file(file); |
372 | if (tmp->vm_flags & VM_DENYWRITE) |
373 | atomic_dec(&inode->i_writecount); |
374 | spin_lock(&mapping->i_mmap_lock); |
375 | if (tmp->vm_flags & VM_SHARED) |
376 | mapping->i_mmap_writable++; |
377 | tmp->vm_truncate_count = mpnt->vm_truncate_count; |
378 | flush_dcache_mmap_lock(mapping); |
379 | /* insert tmp into the share list, just after mpnt */ |
380 | vma_prio_tree_add(tmp, mpnt); |
381 | flush_dcache_mmap_unlock(mapping); |
382 | spin_unlock(&mapping->i_mmap_lock); |
383 | } |
384 | |
385 | /* |
386 | * Clear hugetlb-related page reserves for children. This only |
387 | * affects MAP_PRIVATE mappings. Faults generated by the child |
388 | * are not guaranteed to succeed, even if read-only |
389 | */ |
390 | if (is_vm_hugetlb_page(tmp)) |
391 | reset_vma_resv_huge_pages(tmp); |
392 | |
393 | /* |
394 | * Link in the new vma and copy the page table entries. |
395 | */ |
396 | *pprev = tmp; |
397 | pprev = &tmp->vm_next; |
398 | tmp->vm_prev = prev; |
399 | prev = tmp; |
400 | |
401 | __vma_link_rb(mm, tmp, rb_link, rb_parent); |
402 | rb_link = &tmp->vm_rb.rb_right; |
403 | rb_parent = &tmp->vm_rb; |
404 | |
405 | mm->map_count++; |
406 | retval = copy_page_range(mm, oldmm, mpnt); |
407 | |
408 | if (tmp->vm_ops && tmp->vm_ops->open) |
409 | tmp->vm_ops->open(tmp); |
410 | |
411 | if (retval) |
412 | goto out; |
413 | } |
414 | /* a new mm has just been created */ |
415 | arch_dup_mmap(oldmm, mm); |
416 | retval = 0; |
417 | out: |
418 | up_write(&mm->mmap_sem); |
419 | flush_tlb_mm(oldmm); |
420 | up_write(&oldmm->mmap_sem); |
421 | return retval; |
422 | fail_nomem_anon_vma_fork: |
423 | mpol_put(pol); |
424 | fail_nomem_policy: |
425 | kmem_cache_free(vm_area_cachep, tmp); |
426 | fail_nomem: |
427 | retval = -ENOMEM; |
428 | vm_unacct_memory(charge); |
429 | goto out; |
430 | } |
431 | |
432 | static inline int mm_alloc_pgd(struct mm_struct * mm) |
433 | { |
434 | mm->pgd = pgd_alloc(mm); |
435 | if (unlikely(!mm->pgd)) |
436 | return -ENOMEM; |
437 | return 0; |
438 | } |
439 | |
440 | static inline void mm_free_pgd(struct mm_struct * mm) |
441 | { |
442 | pgd_free(mm, mm->pgd); |
443 | } |
444 | #else |
445 | #define dup_mmap(mm, oldmm) (0) |
446 | #define mm_alloc_pgd(mm) (0) |
447 | #define mm_free_pgd(mm) |
448 | #endif /* CONFIG_MMU */ |
449 | |
450 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); |
451 | |
452 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) |
453 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) |
454 | |
455 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; |
456 | |
457 | static int __init coredump_filter_setup(char *s) |
458 | { |
459 | default_dump_filter = |
460 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & |
461 | MMF_DUMP_FILTER_MASK; |
462 | return 1; |
463 | } |
464 | |
465 | __setup("coredump_filter=", coredump_filter_setup); |
466 | |
467 | #include <linux/init_task.h> |
468 | |
469 | static void mm_init_aio(struct mm_struct *mm) |
470 | { |
471 | #ifdef CONFIG_AIO |
472 | spin_lock_init(&mm->ioctx_lock); |
473 | INIT_HLIST_HEAD(&mm->ioctx_list); |
474 | #endif |
475 | } |
476 | |
477 | static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) |
478 | { |
479 | atomic_set(&mm->mm_users, 1); |
480 | atomic_set(&mm->mm_count, 1); |
481 | init_rwsem(&mm->mmap_sem); |
482 | INIT_LIST_HEAD(&mm->mmlist); |
483 | mm->flags = (current->mm) ? |
484 | (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; |
485 | mm->core_state = NULL; |
486 | mm->nr_ptes = 0; |
487 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); |
488 | spin_lock_init(&mm->page_table_lock); |
489 | mm->free_area_cache = TASK_UNMAPPED_BASE; |
490 | mm->cached_hole_size = ~0UL; |
491 | mm_init_aio(mm); |
492 | mm_init_owner(mm, p); |
493 | atomic_set(&mm->oom_disable_count, 0); |
494 | |
495 | if (likely(!mm_alloc_pgd(mm))) { |
496 | mm->def_flags = 0; |
497 | mmu_notifier_mm_init(mm); |
498 | return mm; |
499 | } |
500 | |
501 | free_mm(mm); |
502 | return NULL; |
503 | } |
504 | |
505 | /* |
506 | * Allocate and initialize an mm_struct. |
507 | */ |
508 | struct mm_struct * mm_alloc(void) |
509 | { |
510 | struct mm_struct * mm; |
511 | |
512 | mm = allocate_mm(); |
513 | if (mm) { |
514 | memset(mm, 0, sizeof(*mm)); |
515 | mm = mm_init(mm, current); |
516 | } |
517 | return mm; |
518 | } |
519 | |
520 | /* |
521 | * Called when the last reference to the mm |
522 | * is dropped: either by a lazy thread or by |
523 | * mmput. Free the page directory and the mm. |
524 | */ |
525 | void __mmdrop(struct mm_struct *mm) |
526 | { |
527 | BUG_ON(mm == &init_mm); |
528 | mm_free_pgd(mm); |
529 | destroy_context(mm); |
530 | mmu_notifier_mm_destroy(mm); |
531 | free_mm(mm); |
532 | } |
533 | EXPORT_SYMBOL_GPL(__mmdrop); |
534 | |
535 | /* |
536 | * Decrement the use count and release all resources for an mm. |
537 | */ |
538 | void mmput(struct mm_struct *mm) |
539 | { |
540 | might_sleep(); |
541 | |
542 | if (atomic_dec_and_test(&mm->mm_users)) { |
543 | exit_aio(mm); |
544 | ksm_exit(mm); |
545 | exit_mmap(mm); |
546 | set_mm_exe_file(mm, NULL); |
547 | if (!list_empty(&mm->mmlist)) { |
548 | spin_lock(&mmlist_lock); |
549 | list_del(&mm->mmlist); |
550 | spin_unlock(&mmlist_lock); |
551 | } |
552 | put_swap_token(mm); |
553 | if (mm->binfmt) |
554 | module_put(mm->binfmt->module); |
555 | mmdrop(mm); |
556 | } |
557 | } |
558 | EXPORT_SYMBOL_GPL(mmput); |
559 | |
560 | /** |
561 | * get_task_mm - acquire a reference to the task's mm |
562 | * |
563 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning |
564 | * this kernel workthread has transiently adopted a user mm with use_mm, |
565 | * to do its AIO) is not set and if so returns a reference to it, after |
566 | * bumping up the use count. User must release the mm via mmput() |
567 | * after use. Typically used by /proc and ptrace. |
568 | */ |
569 | struct mm_struct *get_task_mm(struct task_struct *task) |
570 | { |
571 | struct mm_struct *mm; |
572 | |
573 | task_lock(task); |
574 | mm = task->mm; |
575 | if (mm) { |
576 | if (task->flags & PF_KTHREAD) |
577 | mm = NULL; |
578 | else |
579 | atomic_inc(&mm->mm_users); |
580 | } |
581 | task_unlock(task); |
582 | return mm; |
583 | } |
584 | EXPORT_SYMBOL_GPL(get_task_mm); |
585 | |
586 | /* Please note the differences between mmput and mm_release. |
587 | * mmput is called whenever we stop holding onto a mm_struct, |
588 | * error success whatever. |
589 | * |
590 | * mm_release is called after a mm_struct has been removed |
591 | * from the current process. |
592 | * |
593 | * This difference is important for error handling, when we |
594 | * only half set up a mm_struct for a new process and need to restore |
595 | * the old one. Because we mmput the new mm_struct before |
596 | * restoring the old one. . . |
597 | * Eric Biederman 10 January 1998 |
598 | */ |
599 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) |
600 | { |
601 | struct completion *vfork_done = tsk->vfork_done; |
602 | |
603 | /* Get rid of any futexes when releasing the mm */ |
604 | #ifdef CONFIG_FUTEX |
605 | if (unlikely(tsk->robust_list)) { |
606 | exit_robust_list(tsk); |
607 | tsk->robust_list = NULL; |
608 | } |
609 | #ifdef CONFIG_COMPAT |
610 | if (unlikely(tsk->compat_robust_list)) { |
611 | compat_exit_robust_list(tsk); |
612 | tsk->compat_robust_list = NULL; |
613 | } |
614 | #endif |
615 | if (unlikely(!list_empty(&tsk->pi_state_list))) |
616 | exit_pi_state_list(tsk); |
617 | #endif |
618 | |
619 | /* Get rid of any cached register state */ |
620 | deactivate_mm(tsk, mm); |
621 | |
622 | /* notify parent sleeping on vfork() */ |
623 | if (vfork_done) { |
624 | tsk->vfork_done = NULL; |
625 | complete(vfork_done); |
626 | } |
627 | |
628 | /* |
629 | * If we're exiting normally, clear a user-space tid field if |
630 | * requested. We leave this alone when dying by signal, to leave |
631 | * the value intact in a core dump, and to save the unnecessary |
632 | * trouble otherwise. Userland only wants this done for a sys_exit. |
633 | */ |
634 | if (tsk->clear_child_tid) { |
635 | if (!(tsk->flags & PF_SIGNALED) && |
636 | atomic_read(&mm->mm_users) > 1) { |
637 | /* |
638 | * We don't check the error code - if userspace has |
639 | * not set up a proper pointer then tough luck. |
640 | */ |
641 | put_user(0, tsk->clear_child_tid); |
642 | sys_futex(tsk->clear_child_tid, FUTEX_WAKE, |
643 | 1, NULL, NULL, 0); |
644 | } |
645 | tsk->clear_child_tid = NULL; |
646 | } |
647 | } |
648 | |
649 | /* |
650 | * Allocate a new mm structure and copy contents from the |
651 | * mm structure of the passed in task structure. |
652 | */ |
653 | struct mm_struct *dup_mm(struct task_struct *tsk) |
654 | { |
655 | struct mm_struct *mm, *oldmm = current->mm; |
656 | int err; |
657 | |
658 | if (!oldmm) |
659 | return NULL; |
660 | |
661 | mm = allocate_mm(); |
662 | if (!mm) |
663 | goto fail_nomem; |
664 | |
665 | memcpy(mm, oldmm, sizeof(*mm)); |
666 | |
667 | /* Initializing for Swap token stuff */ |
668 | mm->token_priority = 0; |
669 | mm->last_interval = 0; |
670 | |
671 | if (!mm_init(mm, tsk)) |
672 | goto fail_nomem; |
673 | |
674 | if (init_new_context(tsk, mm)) |
675 | goto fail_nocontext; |
676 | |
677 | dup_mm_exe_file(oldmm, mm); |
678 | |
679 | err = dup_mmap(mm, oldmm); |
680 | if (err) |
681 | goto free_pt; |
682 | |
683 | mm->hiwater_rss = get_mm_rss(mm); |
684 | mm->hiwater_vm = mm->total_vm; |
685 | |
686 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) |
687 | goto free_pt; |
688 | |
689 | return mm; |
690 | |
691 | free_pt: |
692 | /* don't put binfmt in mmput, we haven't got module yet */ |
693 | mm->binfmt = NULL; |
694 | mmput(mm); |
695 | |
696 | fail_nomem: |
697 | return NULL; |
698 | |
699 | fail_nocontext: |
700 | /* |
701 | * If init_new_context() failed, we cannot use mmput() to free the mm |
702 | * because it calls destroy_context() |
703 | */ |
704 | mm_free_pgd(mm); |
705 | free_mm(mm); |
706 | return NULL; |
707 | } |
708 | |
709 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) |
710 | { |
711 | struct mm_struct * mm, *oldmm; |
712 | int retval; |
713 | |
714 | tsk->min_flt = tsk->maj_flt = 0; |
715 | tsk->nvcsw = tsk->nivcsw = 0; |
716 | #ifdef CONFIG_DETECT_HUNG_TASK |
717 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; |
718 | #endif |
719 | |
720 | tsk->mm = NULL; |
721 | tsk->active_mm = NULL; |
722 | |
723 | /* |
724 | * Are we cloning a kernel thread? |
725 | * |
726 | * We need to steal a active VM for that.. |
727 | */ |
728 | oldmm = current->mm; |
729 | if (!oldmm) |
730 | return 0; |
731 | |
732 | if (clone_flags & CLONE_VM) { |
733 | atomic_inc(&oldmm->mm_users); |
734 | mm = oldmm; |
735 | goto good_mm; |
736 | } |
737 | |
738 | retval = -ENOMEM; |
739 | mm = dup_mm(tsk); |
740 | if (!mm) |
741 | goto fail_nomem; |
742 | |
743 | good_mm: |
744 | /* Initializing for Swap token stuff */ |
745 | mm->token_priority = 0; |
746 | mm->last_interval = 0; |
747 | if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) |
748 | atomic_inc(&mm->oom_disable_count); |
749 | |
750 | tsk->mm = mm; |
751 | tsk->active_mm = mm; |
752 | return 0; |
753 | |
754 | fail_nomem: |
755 | return retval; |
756 | } |
757 | |
758 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) |
759 | { |
760 | struct fs_struct *fs = current->fs; |
761 | if (clone_flags & CLONE_FS) { |
762 | /* tsk->fs is already what we want */ |
763 | spin_lock(&fs->lock); |
764 | if (fs->in_exec) { |
765 | spin_unlock(&fs->lock); |
766 | return -EAGAIN; |
767 | } |
768 | fs->users++; |
769 | spin_unlock(&fs->lock); |
770 | return 0; |
771 | } |
772 | tsk->fs = copy_fs_struct(fs); |
773 | if (!tsk->fs) |
774 | return -ENOMEM; |
775 | return 0; |
776 | } |
777 | |
778 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) |
779 | { |
780 | struct files_struct *oldf, *newf; |
781 | int error = 0; |
782 | |
783 | /* |
784 | * A background process may not have any files ... |
785 | */ |
786 | oldf = current->files; |
787 | if (!oldf) |
788 | goto out; |
789 | |
790 | if (clone_flags & CLONE_FILES) { |
791 | atomic_inc(&oldf->count); |
792 | goto out; |
793 | } |
794 | |
795 | newf = dup_fd(oldf, &error); |
796 | if (!newf) |
797 | goto out; |
798 | |
799 | tsk->files = newf; |
800 | error = 0; |
801 | out: |
802 | return error; |
803 | } |
804 | |
805 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) |
806 | { |
807 | #ifdef CONFIG_BLOCK |
808 | struct io_context *ioc = current->io_context; |
809 | |
810 | if (!ioc) |
811 | return 0; |
812 | /* |
813 | * Share io context with parent, if CLONE_IO is set |
814 | */ |
815 | if (clone_flags & CLONE_IO) { |
816 | tsk->io_context = ioc_task_link(ioc); |
817 | if (unlikely(!tsk->io_context)) |
818 | return -ENOMEM; |
819 | } else if (ioprio_valid(ioc->ioprio)) { |
820 | tsk->io_context = alloc_io_context(GFP_KERNEL, -1); |
821 | if (unlikely(!tsk->io_context)) |
822 | return -ENOMEM; |
823 | |
824 | tsk->io_context->ioprio = ioc->ioprio; |
825 | } |
826 | #endif |
827 | return 0; |
828 | } |
829 | |
830 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) |
831 | { |
832 | struct sighand_struct *sig; |
833 | |
834 | if (clone_flags & CLONE_SIGHAND) { |
835 | atomic_inc(¤t->sighand->count); |
836 | return 0; |
837 | } |
838 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
839 | rcu_assign_pointer(tsk->sighand, sig); |
840 | if (!sig) |
841 | return -ENOMEM; |
842 | atomic_set(&sig->count, 1); |
843 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); |
844 | return 0; |
845 | } |
846 | |
847 | void __cleanup_sighand(struct sighand_struct *sighand) |
848 | { |
849 | if (atomic_dec_and_test(&sighand->count)) |
850 | kmem_cache_free(sighand_cachep, sighand); |
851 | } |
852 | |
853 | |
854 | /* |
855 | * Initialize POSIX timer handling for a thread group. |
856 | */ |
857 | static void posix_cpu_timers_init_group(struct signal_struct *sig) |
858 | { |
859 | unsigned long cpu_limit; |
860 | |
861 | /* Thread group counters. */ |
862 | thread_group_cputime_init(sig); |
863 | |
864 | cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
865 | if (cpu_limit != RLIM_INFINITY) { |
866 | sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); |
867 | sig->cputimer.running = 1; |
868 | } |
869 | |
870 | /* The timer lists. */ |
871 | INIT_LIST_HEAD(&sig->cpu_timers[0]); |
872 | INIT_LIST_HEAD(&sig->cpu_timers[1]); |
873 | INIT_LIST_HEAD(&sig->cpu_timers[2]); |
874 | } |
875 | |
876 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) |
877 | { |
878 | struct signal_struct *sig; |
879 | |
880 | if (clone_flags & CLONE_THREAD) |
881 | return 0; |
882 | |
883 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); |
884 | tsk->signal = sig; |
885 | if (!sig) |
886 | return -ENOMEM; |
887 | |
888 | sig->nr_threads = 1; |
889 | atomic_set(&sig->live, 1); |
890 | atomic_set(&sig->sigcnt, 1); |
891 | init_waitqueue_head(&sig->wait_chldexit); |
892 | if (clone_flags & CLONE_NEWPID) |
893 | sig->flags |= SIGNAL_UNKILLABLE; |
894 | sig->curr_target = tsk; |
895 | init_sigpending(&sig->shared_pending); |
896 | INIT_LIST_HEAD(&sig->posix_timers); |
897 | |
898 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
899 | sig->real_timer.function = it_real_fn; |
900 | |
901 | task_lock(current->group_leader); |
902 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); |
903 | task_unlock(current->group_leader); |
904 | |
905 | posix_cpu_timers_init_group(sig); |
906 | |
907 | tty_audit_fork(sig); |
908 | |
909 | sig->oom_adj = current->signal->oom_adj; |
910 | sig->oom_score_adj = current->signal->oom_score_adj; |
911 | |
912 | mutex_init(&sig->cred_guard_mutex); |
913 | |
914 | return 0; |
915 | } |
916 | |
917 | static void copy_flags(unsigned long clone_flags, struct task_struct *p) |
918 | { |
919 | unsigned long new_flags = p->flags; |
920 | |
921 | new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); |
922 | new_flags |= PF_FORKNOEXEC; |
923 | new_flags |= PF_STARTING; |
924 | p->flags = new_flags; |
925 | clear_freeze_flag(p); |
926 | } |
927 | |
928 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) |
929 | { |
930 | current->clear_child_tid = tidptr; |
931 | |
932 | return task_pid_vnr(current); |
933 | } |
934 | |
935 | static void rt_mutex_init_task(struct task_struct *p) |
936 | { |
937 | raw_spin_lock_init(&p->pi_lock); |
938 | #ifdef CONFIG_RT_MUTEXES |
939 | plist_head_init_raw(&p->pi_waiters, &p->pi_lock); |
940 | p->pi_blocked_on = NULL; |
941 | #endif |
942 | } |
943 | |
944 | #ifdef CONFIG_MM_OWNER |
945 | void mm_init_owner(struct mm_struct *mm, struct task_struct *p) |
946 | { |
947 | mm->owner = p; |
948 | } |
949 | #endif /* CONFIG_MM_OWNER */ |
950 | |
951 | /* |
952 | * Initialize POSIX timer handling for a single task. |
953 | */ |
954 | static void posix_cpu_timers_init(struct task_struct *tsk) |
955 | { |
956 | tsk->cputime_expires.prof_exp = cputime_zero; |
957 | tsk->cputime_expires.virt_exp = cputime_zero; |
958 | tsk->cputime_expires.sched_exp = 0; |
959 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); |
960 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); |
961 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); |
962 | } |
963 | |
964 | /* |
965 | * This creates a new process as a copy of the old one, |
966 | * but does not actually start it yet. |
967 | * |
968 | * It copies the registers, and all the appropriate |
969 | * parts of the process environment (as per the clone |
970 | * flags). The actual kick-off is left to the caller. |
971 | */ |
972 | static struct task_struct *copy_process(unsigned long clone_flags, |
973 | unsigned long stack_start, |
974 | struct pt_regs *regs, |
975 | unsigned long stack_size, |
976 | int __user *child_tidptr, |
977 | struct pid *pid, |
978 | int trace) |
979 | { |
980 | int retval; |
981 | struct task_struct *p; |
982 | int cgroup_callbacks_done = 0; |
983 | |
984 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) |
985 | return ERR_PTR(-EINVAL); |
986 | |
987 | /* |
988 | * Thread groups must share signals as well, and detached threads |
989 | * can only be started up within the thread group. |
990 | */ |
991 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) |
992 | return ERR_PTR(-EINVAL); |
993 | |
994 | /* |
995 | * Shared signal handlers imply shared VM. By way of the above, |
996 | * thread groups also imply shared VM. Blocking this case allows |
997 | * for various simplifications in other code. |
998 | */ |
999 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) |
1000 | return ERR_PTR(-EINVAL); |
1001 | |
1002 | /* |
1003 | * Siblings of global init remain as zombies on exit since they are |
1004 | * not reaped by their parent (swapper). To solve this and to avoid |
1005 | * multi-rooted process trees, prevent global and container-inits |
1006 | * from creating siblings. |
1007 | */ |
1008 | if ((clone_flags & CLONE_PARENT) && |
1009 | current->signal->flags & SIGNAL_UNKILLABLE) |
1010 | return ERR_PTR(-EINVAL); |
1011 | |
1012 | retval = security_task_create(clone_flags); |
1013 | if (retval) |
1014 | goto fork_out; |
1015 | |
1016 | retval = -ENOMEM; |
1017 | p = dup_task_struct(current); |
1018 | if (!p) |
1019 | goto fork_out; |
1020 | |
1021 | ftrace_graph_init_task(p); |
1022 | |
1023 | rt_mutex_init_task(p); |
1024 | |
1025 | #ifdef CONFIG_PROVE_LOCKING |
1026 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); |
1027 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); |
1028 | #endif |
1029 | retval = -EAGAIN; |
1030 | if (atomic_read(&p->real_cred->user->processes) >= |
1031 | task_rlimit(p, RLIMIT_NPROC)) { |
1032 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && |
1033 | p->real_cred->user != INIT_USER) |
1034 | goto bad_fork_free; |
1035 | } |
1036 | |
1037 | retval = copy_creds(p, clone_flags); |
1038 | if (retval < 0) |
1039 | goto bad_fork_free; |
1040 | |
1041 | /* |
1042 | * If multiple threads are within copy_process(), then this check |
1043 | * triggers too late. This doesn't hurt, the check is only there |
1044 | * to stop root fork bombs. |
1045 | */ |
1046 | retval = -EAGAIN; |
1047 | if (nr_threads >= max_threads) |
1048 | goto bad_fork_cleanup_count; |
1049 | |
1050 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) |
1051 | goto bad_fork_cleanup_count; |
1052 | |
1053 | p->did_exec = 0; |
1054 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ |
1055 | copy_flags(clone_flags, p); |
1056 | INIT_LIST_HEAD(&p->children); |
1057 | INIT_LIST_HEAD(&p->sibling); |
1058 | rcu_copy_process(p); |
1059 | p->vfork_done = NULL; |
1060 | spin_lock_init(&p->alloc_lock); |
1061 | |
1062 | init_sigpending(&p->pending); |
1063 | |
1064 | p->utime = cputime_zero; |
1065 | p->stime = cputime_zero; |
1066 | p->gtime = cputime_zero; |
1067 | p->utimescaled = cputime_zero; |
1068 | p->stimescaled = cputime_zero; |
1069 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING |
1070 | p->prev_utime = cputime_zero; |
1071 | p->prev_stime = cputime_zero; |
1072 | #endif |
1073 | #if defined(SPLIT_RSS_COUNTING) |
1074 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); |
1075 | #endif |
1076 | |
1077 | p->default_timer_slack_ns = current->timer_slack_ns; |
1078 | |
1079 | task_io_accounting_init(&p->ioac); |
1080 | acct_clear_integrals(p); |
1081 | |
1082 | posix_cpu_timers_init(p); |
1083 | |
1084 | p->lock_depth = -1; /* -1 = no lock */ |
1085 | do_posix_clock_monotonic_gettime(&p->start_time); |
1086 | p->real_start_time = p->start_time; |
1087 | monotonic_to_bootbased(&p->real_start_time); |
1088 | p->io_context = NULL; |
1089 | p->audit_context = NULL; |
1090 | cgroup_fork(p); |
1091 | #ifdef CONFIG_NUMA |
1092 | p->mempolicy = mpol_dup(p->mempolicy); |
1093 | if (IS_ERR(p->mempolicy)) { |
1094 | retval = PTR_ERR(p->mempolicy); |
1095 | p->mempolicy = NULL; |
1096 | goto bad_fork_cleanup_cgroup; |
1097 | } |
1098 | mpol_fix_fork_child_flag(p); |
1099 | #endif |
1100 | #ifdef CONFIG_TRACE_IRQFLAGS |
1101 | p->irq_events = 0; |
1102 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW |
1103 | p->hardirqs_enabled = 1; |
1104 | #else |
1105 | p->hardirqs_enabled = 0; |
1106 | #endif |
1107 | p->hardirq_enable_ip = 0; |
1108 | p->hardirq_enable_event = 0; |
1109 | p->hardirq_disable_ip = _THIS_IP_; |
1110 | p->hardirq_disable_event = 0; |
1111 | p->softirqs_enabled = 1; |
1112 | p->softirq_enable_ip = _THIS_IP_; |
1113 | p->softirq_enable_event = 0; |
1114 | p->softirq_disable_ip = 0; |
1115 | p->softirq_disable_event = 0; |
1116 | p->hardirq_context = 0; |
1117 | p->softirq_context = 0; |
1118 | #endif |
1119 | #ifdef CONFIG_LOCKDEP |
1120 | p->lockdep_depth = 0; /* no locks held yet */ |
1121 | p->curr_chain_key = 0; |
1122 | p->lockdep_recursion = 0; |
1123 | #endif |
1124 | |
1125 | #ifdef CONFIG_DEBUG_MUTEXES |
1126 | p->blocked_on = NULL; /* not blocked yet */ |
1127 | #endif |
1128 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
1129 | p->memcg_batch.do_batch = 0; |
1130 | p->memcg_batch.memcg = NULL; |
1131 | #endif |
1132 | |
1133 | /* Perform scheduler related setup. Assign this task to a CPU. */ |
1134 | sched_fork(p, clone_flags); |
1135 | |
1136 | retval = perf_event_init_task(p); |
1137 | if (retval) |
1138 | goto bad_fork_cleanup_policy; |
1139 | |
1140 | if ((retval = audit_alloc(p))) |
1141 | goto bad_fork_cleanup_policy; |
1142 | /* copy all the process information */ |
1143 | if ((retval = copy_semundo(clone_flags, p))) |
1144 | goto bad_fork_cleanup_audit; |
1145 | if ((retval = copy_files(clone_flags, p))) |
1146 | goto bad_fork_cleanup_semundo; |
1147 | if ((retval = copy_fs(clone_flags, p))) |
1148 | goto bad_fork_cleanup_files; |
1149 | if ((retval = copy_sighand(clone_flags, p))) |
1150 | goto bad_fork_cleanup_fs; |
1151 | if ((retval = copy_signal(clone_flags, p))) |
1152 | goto bad_fork_cleanup_sighand; |
1153 | if ((retval = copy_mm(clone_flags, p))) |
1154 | goto bad_fork_cleanup_signal; |
1155 | if ((retval = copy_namespaces(clone_flags, p))) |
1156 | goto bad_fork_cleanup_mm; |
1157 | if ((retval = copy_io(clone_flags, p))) |
1158 | goto bad_fork_cleanup_namespaces; |
1159 | retval = copy_thread(clone_flags, stack_start, stack_size, p, regs); |
1160 | if (retval) |
1161 | goto bad_fork_cleanup_io; |
1162 | |
1163 | if (pid != &init_struct_pid) { |
1164 | retval = -ENOMEM; |
1165 | pid = alloc_pid(p->nsproxy->pid_ns); |
1166 | if (!pid) |
1167 | goto bad_fork_cleanup_io; |
1168 | |
1169 | if (clone_flags & CLONE_NEWPID) { |
1170 | retval = pid_ns_prepare_proc(p->nsproxy->pid_ns); |
1171 | if (retval < 0) |
1172 | goto bad_fork_free_pid; |
1173 | } |
1174 | } |
1175 | |
1176 | p->pid = pid_nr(pid); |
1177 | p->tgid = p->pid; |
1178 | if (clone_flags & CLONE_THREAD) |
1179 | p->tgid = current->tgid; |
1180 | |
1181 | if (current->nsproxy != p->nsproxy) { |
1182 | retval = ns_cgroup_clone(p, pid); |
1183 | if (retval) |
1184 | goto bad_fork_free_pid; |
1185 | } |
1186 | |
1187 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; |
1188 | /* |
1189 | * Clear TID on mm_release()? |
1190 | */ |
1191 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; |
1192 | #ifdef CONFIG_FUTEX |
1193 | p->robust_list = NULL; |
1194 | #ifdef CONFIG_COMPAT |
1195 | p->compat_robust_list = NULL; |
1196 | #endif |
1197 | INIT_LIST_HEAD(&p->pi_state_list); |
1198 | p->pi_state_cache = NULL; |
1199 | #endif |
1200 | /* |
1201 | * sigaltstack should be cleared when sharing the same VM |
1202 | */ |
1203 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) |
1204 | p->sas_ss_sp = p->sas_ss_size = 0; |
1205 | |
1206 | /* |
1207 | * Syscall tracing and stepping should be turned off in the |
1208 | * child regardless of CLONE_PTRACE. |
1209 | */ |
1210 | user_disable_single_step(p); |
1211 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); |
1212 | #ifdef TIF_SYSCALL_EMU |
1213 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); |
1214 | #endif |
1215 | clear_all_latency_tracing(p); |
1216 | |
1217 | /* ok, now we should be set up.. */ |
1218 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); |
1219 | p->pdeath_signal = 0; |
1220 | p->exit_state = 0; |
1221 | |
1222 | /* |
1223 | * Ok, make it visible to the rest of the system. |
1224 | * We dont wake it up yet. |
1225 | */ |
1226 | p->group_leader = p; |
1227 | INIT_LIST_HEAD(&p->thread_group); |
1228 | |
1229 | /* Now that the task is set up, run cgroup callbacks if |
1230 | * necessary. We need to run them before the task is visible |
1231 | * on the tasklist. */ |
1232 | cgroup_fork_callbacks(p); |
1233 | cgroup_callbacks_done = 1; |
1234 | |
1235 | /* Need tasklist lock for parent etc handling! */ |
1236 | write_lock_irq(&tasklist_lock); |
1237 | |
1238 | /* CLONE_PARENT re-uses the old parent */ |
1239 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { |
1240 | p->real_parent = current->real_parent; |
1241 | p->parent_exec_id = current->parent_exec_id; |
1242 | } else { |
1243 | p->real_parent = current; |
1244 | p->parent_exec_id = current->self_exec_id; |
1245 | } |
1246 | |
1247 | spin_lock(¤t->sighand->siglock); |
1248 | |
1249 | /* |
1250 | * Process group and session signals need to be delivered to just the |
1251 | * parent before the fork or both the parent and the child after the |
1252 | * fork. Restart if a signal comes in before we add the new process to |
1253 | * it's process group. |
1254 | * A fatal signal pending means that current will exit, so the new |
1255 | * thread can't slip out of an OOM kill (or normal SIGKILL). |
1256 | */ |
1257 | recalc_sigpending(); |
1258 | if (signal_pending(current)) { |
1259 | spin_unlock(¤t->sighand->siglock); |
1260 | write_unlock_irq(&tasklist_lock); |
1261 | retval = -ERESTARTNOINTR; |
1262 | goto bad_fork_free_pid; |
1263 | } |
1264 | |
1265 | if (clone_flags & CLONE_THREAD) { |
1266 | current->signal->nr_threads++; |
1267 | atomic_inc(¤t->signal->live); |
1268 | atomic_inc(¤t->signal->sigcnt); |
1269 | p->group_leader = current->group_leader; |
1270 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); |
1271 | } |
1272 | |
1273 | if (likely(p->pid)) { |
1274 | tracehook_finish_clone(p, clone_flags, trace); |
1275 | |
1276 | if (thread_group_leader(p)) { |
1277 | if (clone_flags & CLONE_NEWPID) |
1278 | p->nsproxy->pid_ns->child_reaper = p; |
1279 | |
1280 | p->signal->leader_pid = pid; |
1281 | p->signal->tty = tty_kref_get(current->signal->tty); |
1282 | attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); |
1283 | attach_pid(p, PIDTYPE_SID, task_session(current)); |
1284 | list_add_tail(&p->sibling, &p->real_parent->children); |
1285 | list_add_tail_rcu(&p->tasks, &init_task.tasks); |
1286 | __get_cpu_var(process_counts)++; |
1287 | } |
1288 | attach_pid(p, PIDTYPE_PID, pid); |
1289 | nr_threads++; |
1290 | } |
1291 | |
1292 | total_forks++; |
1293 | spin_unlock(¤t->sighand->siglock); |
1294 | write_unlock_irq(&tasklist_lock); |
1295 | proc_fork_connector(p); |
1296 | cgroup_post_fork(p); |
1297 | perf_event_fork(p); |
1298 | return p; |
1299 | |
1300 | bad_fork_free_pid: |
1301 | if (pid != &init_struct_pid) |
1302 | free_pid(pid); |
1303 | bad_fork_cleanup_io: |
1304 | if (p->io_context) |
1305 | exit_io_context(p); |
1306 | bad_fork_cleanup_namespaces: |
1307 | exit_task_namespaces(p); |
1308 | bad_fork_cleanup_mm: |
1309 | if (p->mm) { |
1310 | task_lock(p); |
1311 | if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) |
1312 | atomic_dec(&p->mm->oom_disable_count); |
1313 | task_unlock(p); |
1314 | mmput(p->mm); |
1315 | } |
1316 | bad_fork_cleanup_signal: |
1317 | if (!(clone_flags & CLONE_THREAD)) |
1318 | free_signal_struct(p->signal); |
1319 | bad_fork_cleanup_sighand: |
1320 | __cleanup_sighand(p->sighand); |
1321 | bad_fork_cleanup_fs: |
1322 | exit_fs(p); /* blocking */ |
1323 | bad_fork_cleanup_files: |
1324 | exit_files(p); /* blocking */ |
1325 | bad_fork_cleanup_semundo: |
1326 | exit_sem(p); |
1327 | bad_fork_cleanup_audit: |
1328 | audit_free(p); |
1329 | bad_fork_cleanup_policy: |
1330 | perf_event_free_task(p); |
1331 | #ifdef CONFIG_NUMA |
1332 | mpol_put(p->mempolicy); |
1333 | bad_fork_cleanup_cgroup: |
1334 | #endif |
1335 | cgroup_exit(p, cgroup_callbacks_done); |
1336 | delayacct_tsk_free(p); |
1337 | module_put(task_thread_info(p)->exec_domain->module); |
1338 | bad_fork_cleanup_count: |
1339 | atomic_dec(&p->cred->user->processes); |
1340 | exit_creds(p); |
1341 | bad_fork_free: |
1342 | free_task(p); |
1343 | fork_out: |
1344 | return ERR_PTR(retval); |
1345 | } |
1346 | |
1347 | noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) |
1348 | { |
1349 | memset(regs, 0, sizeof(struct pt_regs)); |
1350 | return regs; |
1351 | } |
1352 | |
1353 | static inline void init_idle_pids(struct pid_link *links) |
1354 | { |
1355 | enum pid_type type; |
1356 | |
1357 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { |
1358 | INIT_HLIST_NODE(&links[type].node); /* not really needed */ |
1359 | links[type].pid = &init_struct_pid; |
1360 | } |
1361 | } |
1362 | |
1363 | struct task_struct * __cpuinit fork_idle(int cpu) |
1364 | { |
1365 | struct task_struct *task; |
1366 | struct pt_regs regs; |
1367 | |
1368 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, |
1369 | &init_struct_pid, 0); |
1370 | if (!IS_ERR(task)) { |
1371 | init_idle_pids(task->pids); |
1372 | init_idle(task, cpu); |
1373 | } |
1374 | |
1375 | return task; |
1376 | } |
1377 | |
1378 | /* |
1379 | * Ok, this is the main fork-routine. |
1380 | * |
1381 | * It copies the process, and if successful kick-starts |
1382 | * it and waits for it to finish using the VM if required. |
1383 | */ |
1384 | long do_fork(unsigned long clone_flags, |
1385 | unsigned long stack_start, |
1386 | struct pt_regs *regs, |
1387 | unsigned long stack_size, |
1388 | int __user *parent_tidptr, |
1389 | int __user *child_tidptr) |
1390 | { |
1391 | struct task_struct *p; |
1392 | int trace = 0; |
1393 | long nr; |
1394 | |
1395 | /* |
1396 | * Do some preliminary argument and permissions checking before we |
1397 | * actually start allocating stuff |
1398 | */ |
1399 | if (clone_flags & CLONE_NEWUSER) { |
1400 | if (clone_flags & CLONE_THREAD) |
1401 | return -EINVAL; |
1402 | /* hopefully this check will go away when userns support is |
1403 | * complete |
1404 | */ |
1405 | if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || |
1406 | !capable(CAP_SETGID)) |
1407 | return -EPERM; |
1408 | } |
1409 | |
1410 | /* |
1411 | * We hope to recycle these flags after 2.6.26 |
1412 | */ |
1413 | if (unlikely(clone_flags & CLONE_STOPPED)) { |
1414 | static int __read_mostly count = 100; |
1415 | |
1416 | if (count > 0 && printk_ratelimit()) { |
1417 | char comm[TASK_COMM_LEN]; |
1418 | |
1419 | count--; |
1420 | printk(KERN_INFO "fork(): process `%s' used deprecated " |
1421 | "clone flags 0x%lx\n", |
1422 | get_task_comm(comm, current), |
1423 | clone_flags & CLONE_STOPPED); |
1424 | } |
1425 | } |
1426 | |
1427 | /* |
1428 | * When called from kernel_thread, don't do user tracing stuff. |
1429 | */ |
1430 | if (likely(user_mode(regs))) |
1431 | trace = tracehook_prepare_clone(clone_flags); |
1432 | |
1433 | p = copy_process(clone_flags, stack_start, regs, stack_size, |
1434 | child_tidptr, NULL, trace); |
1435 | /* |
1436 | * Do this prior waking up the new thread - the thread pointer |
1437 | * might get invalid after that point, if the thread exits quickly. |
1438 | */ |
1439 | if (!IS_ERR(p)) { |
1440 | struct completion vfork; |
1441 | |
1442 | trace_sched_process_fork(current, p); |
1443 | |
1444 | nr = task_pid_vnr(p); |
1445 | |
1446 | if (clone_flags & CLONE_PARENT_SETTID) |
1447 | put_user(nr, parent_tidptr); |
1448 | |
1449 | if (clone_flags & CLONE_VFORK) { |
1450 | p->vfork_done = &vfork; |
1451 | init_completion(&vfork); |
1452 | } |
1453 | |
1454 | audit_finish_fork(p); |
1455 | tracehook_report_clone(regs, clone_flags, nr, p); |
1456 | |
1457 | /* |
1458 | * We set PF_STARTING at creation in case tracing wants to |
1459 | * use this to distinguish a fully live task from one that |
1460 | * hasn't gotten to tracehook_report_clone() yet. Now we |
1461 | * clear it and set the child going. |
1462 | */ |
1463 | p->flags &= ~PF_STARTING; |
1464 | |
1465 | if (unlikely(clone_flags & CLONE_STOPPED)) { |
1466 | /* |
1467 | * We'll start up with an immediate SIGSTOP. |
1468 | */ |
1469 | sigaddset(&p->pending.signal, SIGSTOP); |
1470 | set_tsk_thread_flag(p, TIF_SIGPENDING); |
1471 | __set_task_state(p, TASK_STOPPED); |
1472 | } else { |
1473 | wake_up_new_task(p, clone_flags); |
1474 | } |
1475 | |
1476 | tracehook_report_clone_complete(trace, regs, |
1477 | clone_flags, nr, p); |
1478 | |
1479 | if (clone_flags & CLONE_VFORK) { |
1480 | freezer_do_not_count(); |
1481 | wait_for_completion(&vfork); |
1482 | freezer_count(); |
1483 | tracehook_report_vfork_done(p, nr); |
1484 | } |
1485 | } else { |
1486 | nr = PTR_ERR(p); |
1487 | } |
1488 | return nr; |
1489 | } |
1490 | |
1491 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN |
1492 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 |
1493 | #endif |
1494 | |
1495 | static void sighand_ctor(void *data) |
1496 | { |
1497 | struct sighand_struct *sighand = data; |
1498 | |
1499 | spin_lock_init(&sighand->siglock); |
1500 | init_waitqueue_head(&sighand->signalfd_wqh); |
1501 | } |
1502 | |
1503 | void __init proc_caches_init(void) |
1504 | { |
1505 | sighand_cachep = kmem_cache_create("sighand_cache", |
1506 | sizeof(struct sighand_struct), 0, |
1507 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| |
1508 | SLAB_NOTRACK, sighand_ctor); |
1509 | signal_cachep = kmem_cache_create("signal_cache", |
1510 | sizeof(struct signal_struct), 0, |
1511 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1512 | files_cachep = kmem_cache_create("files_cache", |
1513 | sizeof(struct files_struct), 0, |
1514 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1515 | fs_cachep = kmem_cache_create("fs_cache", |
1516 | sizeof(struct fs_struct), 0, |
1517 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1518 | mm_cachep = kmem_cache_create("mm_struct", |
1519 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, |
1520 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1521 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); |
1522 | mmap_init(); |
1523 | } |
1524 | |
1525 | /* |
1526 | * Check constraints on flags passed to the unshare system call and |
1527 | * force unsharing of additional process context as appropriate. |
1528 | */ |
1529 | static void check_unshare_flags(unsigned long *flags_ptr) |
1530 | { |
1531 | /* |
1532 | * If unsharing a thread from a thread group, must also |
1533 | * unshare vm. |
1534 | */ |
1535 | if (*flags_ptr & CLONE_THREAD) |
1536 | *flags_ptr |= CLONE_VM; |
1537 | |
1538 | /* |
1539 | * If unsharing vm, must also unshare signal handlers. |
1540 | */ |
1541 | if (*flags_ptr & CLONE_VM) |
1542 | *flags_ptr |= CLONE_SIGHAND; |
1543 | |
1544 | /* |
1545 | * If unsharing namespace, must also unshare filesystem information. |
1546 | */ |
1547 | if (*flags_ptr & CLONE_NEWNS) |
1548 | *flags_ptr |= CLONE_FS; |
1549 | } |
1550 | |
1551 | /* |
1552 | * Unsharing of tasks created with CLONE_THREAD is not supported yet |
1553 | */ |
1554 | static int unshare_thread(unsigned long unshare_flags) |
1555 | { |
1556 | if (unshare_flags & CLONE_THREAD) |
1557 | return -EINVAL; |
1558 | |
1559 | return 0; |
1560 | } |
1561 | |
1562 | /* |
1563 | * Unshare the filesystem structure if it is being shared |
1564 | */ |
1565 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) |
1566 | { |
1567 | struct fs_struct *fs = current->fs; |
1568 | |
1569 | if (!(unshare_flags & CLONE_FS) || !fs) |
1570 | return 0; |
1571 | |
1572 | /* don't need lock here; in the worst case we'll do useless copy */ |
1573 | if (fs->users == 1) |
1574 | return 0; |
1575 | |
1576 | *new_fsp = copy_fs_struct(fs); |
1577 | if (!*new_fsp) |
1578 | return -ENOMEM; |
1579 | |
1580 | return 0; |
1581 | } |
1582 | |
1583 | /* |
1584 | * Unsharing of sighand is not supported yet |
1585 | */ |
1586 | static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) |
1587 | { |
1588 | struct sighand_struct *sigh = current->sighand; |
1589 | |
1590 | if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) |
1591 | return -EINVAL; |
1592 | else |
1593 | return 0; |
1594 | } |
1595 | |
1596 | /* |
1597 | * Unshare vm if it is being shared |
1598 | */ |
1599 | static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) |
1600 | { |
1601 | struct mm_struct *mm = current->mm; |
1602 | |
1603 | if ((unshare_flags & CLONE_VM) && |
1604 | (mm && atomic_read(&mm->mm_users) > 1)) { |
1605 | return -EINVAL; |
1606 | } |
1607 | |
1608 | return 0; |
1609 | } |
1610 | |
1611 | /* |
1612 | * Unshare file descriptor table if it is being shared |
1613 | */ |
1614 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) |
1615 | { |
1616 | struct files_struct *fd = current->files; |
1617 | int error = 0; |
1618 | |
1619 | if ((unshare_flags & CLONE_FILES) && |
1620 | (fd && atomic_read(&fd->count) > 1)) { |
1621 | *new_fdp = dup_fd(fd, &error); |
1622 | if (!*new_fdp) |
1623 | return error; |
1624 | } |
1625 | |
1626 | return 0; |
1627 | } |
1628 | |
1629 | /* |
1630 | * unshare allows a process to 'unshare' part of the process |
1631 | * context which was originally shared using clone. copy_* |
1632 | * functions used by do_fork() cannot be used here directly |
1633 | * because they modify an inactive task_struct that is being |
1634 | * constructed. Here we are modifying the current, active, |
1635 | * task_struct. |
1636 | */ |
1637 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) |
1638 | { |
1639 | int err = 0; |
1640 | struct fs_struct *fs, *new_fs = NULL; |
1641 | struct sighand_struct *new_sigh = NULL; |
1642 | struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; |
1643 | struct files_struct *fd, *new_fd = NULL; |
1644 | struct nsproxy *new_nsproxy = NULL; |
1645 | int do_sysvsem = 0; |
1646 | |
1647 | check_unshare_flags(&unshare_flags); |
1648 | |
1649 | /* Return -EINVAL for all unsupported flags */ |
1650 | err = -EINVAL; |
1651 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| |
1652 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| |
1653 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET)) |
1654 | goto bad_unshare_out; |
1655 | |
1656 | /* |
1657 | * CLONE_NEWIPC must also detach from the undolist: after switching |
1658 | * to a new ipc namespace, the semaphore arrays from the old |
1659 | * namespace are unreachable. |
1660 | */ |
1661 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) |
1662 | do_sysvsem = 1; |
1663 | if ((err = unshare_thread(unshare_flags))) |
1664 | goto bad_unshare_out; |
1665 | if ((err = unshare_fs(unshare_flags, &new_fs))) |
1666 | goto bad_unshare_cleanup_thread; |
1667 | if ((err = unshare_sighand(unshare_flags, &new_sigh))) |
1668 | goto bad_unshare_cleanup_fs; |
1669 | if ((err = unshare_vm(unshare_flags, &new_mm))) |
1670 | goto bad_unshare_cleanup_sigh; |
1671 | if ((err = unshare_fd(unshare_flags, &new_fd))) |
1672 | goto bad_unshare_cleanup_vm; |
1673 | if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, |
1674 | new_fs))) |
1675 | goto bad_unshare_cleanup_fd; |
1676 | |
1677 | if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) { |
1678 | if (do_sysvsem) { |
1679 | /* |
1680 | * CLONE_SYSVSEM is equivalent to sys_exit(). |
1681 | */ |
1682 | exit_sem(current); |
1683 | } |
1684 | |
1685 | if (new_nsproxy) { |
1686 | switch_task_namespaces(current, new_nsproxy); |
1687 | new_nsproxy = NULL; |
1688 | } |
1689 | |
1690 | task_lock(current); |
1691 | |
1692 | if (new_fs) { |
1693 | fs = current->fs; |
1694 | spin_lock(&fs->lock); |
1695 | current->fs = new_fs; |
1696 | if (--fs->users) |
1697 | new_fs = NULL; |
1698 | else |
1699 | new_fs = fs; |
1700 | spin_unlock(&fs->lock); |
1701 | } |
1702 | |
1703 | if (new_mm) { |
1704 | mm = current->mm; |
1705 | active_mm = current->active_mm; |
1706 | current->mm = new_mm; |
1707 | current->active_mm = new_mm; |
1708 | if (current->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { |
1709 | atomic_dec(&mm->oom_disable_count); |
1710 | atomic_inc(&new_mm->oom_disable_count); |
1711 | } |
1712 | activate_mm(active_mm, new_mm); |
1713 | new_mm = mm; |
1714 | } |
1715 | |
1716 | if (new_fd) { |
1717 | fd = current->files; |
1718 | current->files = new_fd; |
1719 | new_fd = fd; |
1720 | } |
1721 | |
1722 | task_unlock(current); |
1723 | } |
1724 | |
1725 | if (new_nsproxy) |
1726 | put_nsproxy(new_nsproxy); |
1727 | |
1728 | bad_unshare_cleanup_fd: |
1729 | if (new_fd) |
1730 | put_files_struct(new_fd); |
1731 | |
1732 | bad_unshare_cleanup_vm: |
1733 | if (new_mm) |
1734 | mmput(new_mm); |
1735 | |
1736 | bad_unshare_cleanup_sigh: |
1737 | if (new_sigh) |
1738 | if (atomic_dec_and_test(&new_sigh->count)) |
1739 | kmem_cache_free(sighand_cachep, new_sigh); |
1740 | |
1741 | bad_unshare_cleanup_fs: |
1742 | if (new_fs) |
1743 | free_fs_struct(new_fs); |
1744 | |
1745 | bad_unshare_cleanup_thread: |
1746 | bad_unshare_out: |
1747 | return err; |
1748 | } |
1749 | |
1750 | /* |
1751 | * Helper to unshare the files of the current task. |
1752 | * We don't want to expose copy_files internals to |
1753 | * the exec layer of the kernel. |
1754 | */ |
1755 | |
1756 | int unshare_files(struct files_struct **displaced) |
1757 | { |
1758 | struct task_struct *task = current; |
1759 | struct files_struct *copy = NULL; |
1760 | int error; |
1761 | |
1762 | error = unshare_fd(CLONE_FILES, ©); |
1763 | if (error || !copy) { |
1764 | *displaced = NULL; |
1765 | return error; |
1766 | } |
1767 | *displaced = task->files; |
1768 | task_lock(task); |
1769 | task->files = copy; |
1770 | task_unlock(task); |
1771 | return 0; |
1772 | } |
1773 |
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