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