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