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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/mnt_namespace.h> | |
21 | #include <linux/personality.h> | |
22 | #include <linux/mempolicy.h> | |
23 | #include <linux/sem.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/key.h> | |
26 | #include <linux/binfmts.h> | |
27 | #include <linux/mman.h> | |
28 | #include <linux/fs.h> | |
29 | #include <linux/nsproxy.h> | |
30 | #include <linux/capability.h> | |
31 | #include <linux/cpu.h> | |
32 | #include <linux/cpuset.h> | |
33 | #include <linux/security.h> | |
34 | #include <linux/swap.h> | |
35 | #include <linux/syscalls.h> | |
36 | #include <linux/jiffies.h> | |
37 | #include <linux/futex.h> | |
38 | #include <linux/task_io_accounting_ops.h> | |
39 | #include <linux/rcupdate.h> | |
40 | #include <linux/ptrace.h> | |
41 | #include <linux/mount.h> | |
42 | #include <linux/audit.h> | |
43 | #include <linux/profile.h> | |
44 | #include <linux/rmap.h> | |
45 | #include <linux/acct.h> | |
46 | #include <linux/tsacct_kern.h> | |
47 | #include <linux/cn_proc.h> | |
48 | #include <linux/freezer.h> | |
49 | #include <linux/delayacct.h> | |
50 | #include <linux/taskstats_kern.h> | |
51 | #include <linux/random.h> | |
52 | #include <linux/tty.h> | |
53 | ||
54 | #include <asm/pgtable.h> | |
55 | #include <asm/pgalloc.h> | |
56 | #include <asm/uaccess.h> | |
57 | #include <asm/mmu_context.h> | |
58 | #include <asm/cacheflush.h> | |
59 | #include <asm/tlbflush.h> | |
60 | ||
61 | /* | |
62 | * Protected counters by write_lock_irq(&tasklist_lock) | |
63 | */ | |
64 | unsigned long total_forks; /* Handle normal Linux uptimes. */ | |
65 | int nr_threads; /* The idle threads do not count.. */ | |
66 | ||
67 | int max_threads; /* tunable limit on nr_threads */ | |
68 | ||
69 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; | |
70 | ||
71 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ | |
72 | ||
73 | int nr_processes(void) | |
74 | { | |
75 | int cpu; | |
76 | int total = 0; | |
77 | ||
78 | for_each_online_cpu(cpu) | |
79 | total += per_cpu(process_counts, cpu); | |
80 | ||
81 | return total; | |
82 | } | |
83 | ||
84 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
85 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) | |
86 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) | |
87 | static struct kmem_cache *task_struct_cachep; | |
88 | #endif | |
89 | ||
90 | /* SLAB cache for signal_struct structures (tsk->signal) */ | |
91 | static struct kmem_cache *signal_cachep; | |
92 | ||
93 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ | |
94 | struct kmem_cache *sighand_cachep; | |
95 | ||
96 | /* SLAB cache for files_struct structures (tsk->files) */ | |
97 | struct kmem_cache *files_cachep; | |
98 | ||
99 | /* SLAB cache for fs_struct structures (tsk->fs) */ | |
100 | struct kmem_cache *fs_cachep; | |
101 | ||
102 | /* SLAB cache for vm_area_struct structures */ | |
103 | struct kmem_cache *vm_area_cachep; | |
104 | ||
105 | /* SLAB cache for mm_struct structures (tsk->mm) */ | |
106 | static struct kmem_cache *mm_cachep; | |
107 | ||
108 | void free_task(struct task_struct *tsk) | |
109 | { | |
110 | free_thread_info(tsk->stack); | |
111 | rt_mutex_debug_task_free(tsk); | |
112 | free_task_struct(tsk); | |
113 | } | |
114 | EXPORT_SYMBOL(free_task); | |
115 | ||
116 | void __put_task_struct(struct task_struct *tsk) | |
117 | { | |
118 | WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE))); | |
119 | WARN_ON(atomic_read(&tsk->usage)); | |
120 | WARN_ON(tsk == current); | |
121 | ||
122 | security_task_free(tsk); | |
123 | free_uid(tsk->user); | |
124 | put_group_info(tsk->group_info); | |
125 | delayacct_tsk_free(tsk); | |
126 | ||
127 | if (!profile_handoff_task(tsk)) | |
128 | free_task(tsk); | |
129 | } | |
130 | ||
131 | void __init fork_init(unsigned long mempages) | |
132 | { | |
133 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
134 | #ifndef ARCH_MIN_TASKALIGN | |
135 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES | |
136 | #endif | |
137 | /* create a slab on which task_structs can be allocated */ | |
138 | task_struct_cachep = | |
139 | kmem_cache_create("task_struct", sizeof(struct task_struct), | |
140 | ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL); | |
141 | #endif | |
142 | ||
143 | /* | |
144 | * The default maximum number of threads is set to a safe | |
145 | * value: the thread structures can take up at most half | |
146 | * of memory. | |
147 | */ | |
148 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); | |
149 | ||
150 | /* | |
151 | * we need to allow at least 20 threads to boot a system | |
152 | */ | |
153 | if(max_threads < 20) | |
154 | max_threads = 20; | |
155 | ||
156 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; | |
157 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; | |
158 | init_task.signal->rlim[RLIMIT_SIGPENDING] = | |
159 | init_task.signal->rlim[RLIMIT_NPROC]; | |
160 | } | |
161 | ||
162 | static struct task_struct *dup_task_struct(struct task_struct *orig) | |
163 | { | |
164 | struct task_struct *tsk; | |
165 | struct thread_info *ti; | |
166 | ||
167 | prepare_to_copy(orig); | |
168 | ||
169 | tsk = alloc_task_struct(); | |
170 | if (!tsk) | |
171 | return NULL; | |
172 | ||
173 | ti = alloc_thread_info(tsk); | |
174 | if (!ti) { | |
175 | free_task_struct(tsk); | |
176 | return NULL; | |
177 | } | |
178 | ||
179 | *tsk = *orig; | |
180 | tsk->stack = ti; | |
181 | setup_thread_stack(tsk, orig); | |
182 | ||
183 | #ifdef CONFIG_CC_STACKPROTECTOR | |
184 | tsk->stack_canary = get_random_int(); | |
185 | #endif | |
186 | ||
187 | /* One for us, one for whoever does the "release_task()" (usually parent) */ | |
188 | atomic_set(&tsk->usage,2); | |
189 | atomic_set(&tsk->fs_excl, 0); | |
190 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
191 | tsk->btrace_seq = 0; | |
192 | #endif | |
193 | tsk->splice_pipe = NULL; | |
194 | return tsk; | |
195 | } | |
196 | ||
197 | #ifdef CONFIG_MMU | |
198 | static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) | |
199 | { | |
200 | struct vm_area_struct *mpnt, *tmp, **pprev; | |
201 | struct rb_node **rb_link, *rb_parent; | |
202 | int retval; | |
203 | unsigned long charge; | |
204 | struct mempolicy *pol; | |
205 | ||
206 | down_write(&oldmm->mmap_sem); | |
207 | flush_cache_dup_mm(oldmm); | |
208 | /* | |
209 | * Not linked in yet - no deadlock potential: | |
210 | */ | |
211 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); | |
212 | ||
213 | mm->locked_vm = 0; | |
214 | mm->mmap = NULL; | |
215 | mm->mmap_cache = NULL; | |
216 | mm->free_area_cache = oldmm->mmap_base; | |
217 | mm->cached_hole_size = ~0UL; | |
218 | mm->map_count = 0; | |
219 | cpus_clear(mm->cpu_vm_mask); | |
220 | mm->mm_rb = RB_ROOT; | |
221 | rb_link = &mm->mm_rb.rb_node; | |
222 | rb_parent = NULL; | |
223 | pprev = &mm->mmap; | |
224 | ||
225 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { | |
226 | struct file *file; | |
227 | ||
228 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
229 | long pages = vma_pages(mpnt); | |
230 | mm->total_vm -= pages; | |
231 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, | |
232 | -pages); | |
233 | continue; | |
234 | } | |
235 | charge = 0; | |
236 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
237 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; | |
238 | if (security_vm_enough_memory(len)) | |
239 | goto fail_nomem; | |
240 | charge = len; | |
241 | } | |
242 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
243 | if (!tmp) | |
244 | goto fail_nomem; | |
245 | *tmp = *mpnt; | |
246 | pol = mpol_copy(vma_policy(mpnt)); | |
247 | retval = PTR_ERR(pol); | |
248 | if (IS_ERR(pol)) | |
249 | goto fail_nomem_policy; | |
250 | vma_set_policy(tmp, pol); | |
251 | tmp->vm_flags &= ~VM_LOCKED; | |
252 | tmp->vm_mm = mm; | |
253 | tmp->vm_next = NULL; | |
254 | anon_vma_link(tmp); | |
255 | file = tmp->vm_file; | |
256 | if (file) { | |
257 | struct inode *inode = file->f_path.dentry->d_inode; | |
258 | get_file(file); | |
259 | if (tmp->vm_flags & VM_DENYWRITE) | |
260 | atomic_dec(&inode->i_writecount); | |
261 | ||
262 | /* insert tmp into the share list, just after mpnt */ | |
263 | spin_lock(&file->f_mapping->i_mmap_lock); | |
264 | tmp->vm_truncate_count = mpnt->vm_truncate_count; | |
265 | flush_dcache_mmap_lock(file->f_mapping); | |
266 | vma_prio_tree_add(tmp, mpnt); | |
267 | flush_dcache_mmap_unlock(file->f_mapping); | |
268 | spin_unlock(&file->f_mapping->i_mmap_lock); | |
269 | } | |
270 | ||
271 | /* | |
272 | * Link in the new vma and copy the page table entries. | |
273 | */ | |
274 | *pprev = tmp; | |
275 | pprev = &tmp->vm_next; | |
276 | ||
277 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
278 | rb_link = &tmp->vm_rb.rb_right; | |
279 | rb_parent = &tmp->vm_rb; | |
280 | ||
281 | mm->map_count++; | |
282 | retval = copy_page_range(mm, oldmm, mpnt); | |
283 | ||
284 | if (tmp->vm_ops && tmp->vm_ops->open) | |
285 | tmp->vm_ops->open(tmp); | |
286 | ||
287 | if (retval) | |
288 | goto out; | |
289 | } | |
290 | /* a new mm has just been created */ | |
291 | arch_dup_mmap(oldmm, mm); | |
292 | retval = 0; | |
293 | out: | |
294 | up_write(&mm->mmap_sem); | |
295 | flush_tlb_mm(oldmm); | |
296 | up_write(&oldmm->mmap_sem); | |
297 | return retval; | |
298 | fail_nomem_policy: | |
299 | kmem_cache_free(vm_area_cachep, tmp); | |
300 | fail_nomem: | |
301 | retval = -ENOMEM; | |
302 | vm_unacct_memory(charge); | |
303 | goto out; | |
304 | } | |
305 | ||
306 | static inline int mm_alloc_pgd(struct mm_struct * mm) | |
307 | { | |
308 | mm->pgd = pgd_alloc(mm); | |
309 | if (unlikely(!mm->pgd)) | |
310 | return -ENOMEM; | |
311 | return 0; | |
312 | } | |
313 | ||
314 | static inline void mm_free_pgd(struct mm_struct * mm) | |
315 | { | |
316 | pgd_free(mm->pgd); | |
317 | } | |
318 | #else | |
319 | #define dup_mmap(mm, oldmm) (0) | |
320 | #define mm_alloc_pgd(mm) (0) | |
321 | #define mm_free_pgd(mm) | |
322 | #endif /* CONFIG_MMU */ | |
323 | ||
324 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
325 | ||
326 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) | |
327 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
328 | ||
329 | #include <linux/init_task.h> | |
330 | ||
331 | static struct mm_struct * mm_init(struct mm_struct * mm) | |
332 | { | |
333 | atomic_set(&mm->mm_users, 1); | |
334 | atomic_set(&mm->mm_count, 1); | |
335 | init_rwsem(&mm->mmap_sem); | |
336 | INIT_LIST_HEAD(&mm->mmlist); | |
337 | mm->flags = (current->mm) ? current->mm->flags | |
338 | : MMF_DUMP_FILTER_DEFAULT; | |
339 | mm->core_waiters = 0; | |
340 | mm->nr_ptes = 0; | |
341 | set_mm_counter(mm, file_rss, 0); | |
342 | set_mm_counter(mm, anon_rss, 0); | |
343 | spin_lock_init(&mm->page_table_lock); | |
344 | rwlock_init(&mm->ioctx_list_lock); | |
345 | mm->ioctx_list = NULL; | |
346 | mm->free_area_cache = TASK_UNMAPPED_BASE; | |
347 | mm->cached_hole_size = ~0UL; | |
348 | ||
349 | if (likely(!mm_alloc_pgd(mm))) { | |
350 | mm->def_flags = 0; | |
351 | return mm; | |
352 | } | |
353 | free_mm(mm); | |
354 | return NULL; | |
355 | } | |
356 | ||
357 | /* | |
358 | * Allocate and initialize an mm_struct. | |
359 | */ | |
360 | struct mm_struct * mm_alloc(void) | |
361 | { | |
362 | struct mm_struct * mm; | |
363 | ||
364 | mm = allocate_mm(); | |
365 | if (mm) { | |
366 | memset(mm, 0, sizeof(*mm)); | |
367 | mm = mm_init(mm); | |
368 | } | |
369 | return mm; | |
370 | } | |
371 | ||
372 | /* | |
373 | * Called when the last reference to the mm | |
374 | * is dropped: either by a lazy thread or by | |
375 | * mmput. Free the page directory and the mm. | |
376 | */ | |
377 | void fastcall __mmdrop(struct mm_struct *mm) | |
378 | { | |
379 | BUG_ON(mm == &init_mm); | |
380 | mm_free_pgd(mm); | |
381 | destroy_context(mm); | |
382 | free_mm(mm); | |
383 | } | |
384 | ||
385 | /* | |
386 | * Decrement the use count and release all resources for an mm. | |
387 | */ | |
388 | void mmput(struct mm_struct *mm) | |
389 | { | |
390 | might_sleep(); | |
391 | ||
392 | if (atomic_dec_and_test(&mm->mm_users)) { | |
393 | exit_aio(mm); | |
394 | exit_mmap(mm); | |
395 | if (!list_empty(&mm->mmlist)) { | |
396 | spin_lock(&mmlist_lock); | |
397 | list_del(&mm->mmlist); | |
398 | spin_unlock(&mmlist_lock); | |
399 | } | |
400 | put_swap_token(mm); | |
401 | mmdrop(mm); | |
402 | } | |
403 | } | |
404 | EXPORT_SYMBOL_GPL(mmput); | |
405 | ||
406 | /** | |
407 | * get_task_mm - acquire a reference to the task's mm | |
408 | * | |
409 | * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning | |
410 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
411 | * to do its AIO) is not set and if so returns a reference to it, after | |
412 | * bumping up the use count. User must release the mm via mmput() | |
413 | * after use. Typically used by /proc and ptrace. | |
414 | */ | |
415 | struct mm_struct *get_task_mm(struct task_struct *task) | |
416 | { | |
417 | struct mm_struct *mm; | |
418 | ||
419 | task_lock(task); | |
420 | mm = task->mm; | |
421 | if (mm) { | |
422 | if (task->flags & PF_BORROWED_MM) | |
423 | mm = NULL; | |
424 | else | |
425 | atomic_inc(&mm->mm_users); | |
426 | } | |
427 | task_unlock(task); | |
428 | return mm; | |
429 | } | |
430 | EXPORT_SYMBOL_GPL(get_task_mm); | |
431 | ||
432 | /* Please note the differences between mmput and mm_release. | |
433 | * mmput is called whenever we stop holding onto a mm_struct, | |
434 | * error success whatever. | |
435 | * | |
436 | * mm_release is called after a mm_struct has been removed | |
437 | * from the current process. | |
438 | * | |
439 | * This difference is important for error handling, when we | |
440 | * only half set up a mm_struct for a new process and need to restore | |
441 | * the old one. Because we mmput the new mm_struct before | |
442 | * restoring the old one. . . | |
443 | * Eric Biederman 10 January 1998 | |
444 | */ | |
445 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
446 | { | |
447 | struct completion *vfork_done = tsk->vfork_done; | |
448 | ||
449 | /* Get rid of any cached register state */ | |
450 | deactivate_mm(tsk, mm); | |
451 | ||
452 | /* notify parent sleeping on vfork() */ | |
453 | if (vfork_done) { | |
454 | tsk->vfork_done = NULL; | |
455 | complete(vfork_done); | |
456 | } | |
457 | ||
458 | /* | |
459 | * If we're exiting normally, clear a user-space tid field if | |
460 | * requested. We leave this alone when dying by signal, to leave | |
461 | * the value intact in a core dump, and to save the unnecessary | |
462 | * trouble otherwise. Userland only wants this done for a sys_exit. | |
463 | */ | |
464 | if (tsk->clear_child_tid | |
465 | && !(tsk->flags & PF_SIGNALED) | |
466 | && atomic_read(&mm->mm_users) > 1) { | |
467 | u32 __user * tidptr = tsk->clear_child_tid; | |
468 | tsk->clear_child_tid = NULL; | |
469 | ||
470 | /* | |
471 | * We don't check the error code - if userspace has | |
472 | * not set up a proper pointer then tough luck. | |
473 | */ | |
474 | put_user(0, tidptr); | |
475 | sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); | |
476 | } | |
477 | } | |
478 | ||
479 | /* | |
480 | * Allocate a new mm structure and copy contents from the | |
481 | * mm structure of the passed in task structure. | |
482 | */ | |
483 | static struct mm_struct *dup_mm(struct task_struct *tsk) | |
484 | { | |
485 | struct mm_struct *mm, *oldmm = current->mm; | |
486 | int err; | |
487 | ||
488 | if (!oldmm) | |
489 | return NULL; | |
490 | ||
491 | mm = allocate_mm(); | |
492 | if (!mm) | |
493 | goto fail_nomem; | |
494 | ||
495 | memcpy(mm, oldmm, sizeof(*mm)); | |
496 | ||
497 | /* Initializing for Swap token stuff */ | |
498 | mm->token_priority = 0; | |
499 | mm->last_interval = 0; | |
500 | ||
501 | if (!mm_init(mm)) | |
502 | goto fail_nomem; | |
503 | ||
504 | if (init_new_context(tsk, mm)) | |
505 | goto fail_nocontext; | |
506 | ||
507 | err = dup_mmap(mm, oldmm); | |
508 | if (err) | |
509 | goto free_pt; | |
510 | ||
511 | mm->hiwater_rss = get_mm_rss(mm); | |
512 | mm->hiwater_vm = mm->total_vm; | |
513 | ||
514 | return mm; | |
515 | ||
516 | free_pt: | |
517 | mmput(mm); | |
518 | ||
519 | fail_nomem: | |
520 | return NULL; | |
521 | ||
522 | fail_nocontext: | |
523 | /* | |
524 | * If init_new_context() failed, we cannot use mmput() to free the mm | |
525 | * because it calls destroy_context() | |
526 | */ | |
527 | mm_free_pgd(mm); | |
528 | free_mm(mm); | |
529 | return NULL; | |
530 | } | |
531 | ||
532 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) | |
533 | { | |
534 | struct mm_struct * mm, *oldmm; | |
535 | int retval; | |
536 | ||
537 | tsk->min_flt = tsk->maj_flt = 0; | |
538 | tsk->nvcsw = tsk->nivcsw = 0; | |
539 | ||
540 | tsk->mm = NULL; | |
541 | tsk->active_mm = NULL; | |
542 | ||
543 | /* | |
544 | * Are we cloning a kernel thread? | |
545 | * | |
546 | * We need to steal a active VM for that.. | |
547 | */ | |
548 | oldmm = current->mm; | |
549 | if (!oldmm) | |
550 | return 0; | |
551 | ||
552 | if (clone_flags & CLONE_VM) { | |
553 | atomic_inc(&oldmm->mm_users); | |
554 | mm = oldmm; | |
555 | goto good_mm; | |
556 | } | |
557 | ||
558 | retval = -ENOMEM; | |
559 | mm = dup_mm(tsk); | |
560 | if (!mm) | |
561 | goto fail_nomem; | |
562 | ||
563 | good_mm: | |
564 | /* Initializing for Swap token stuff */ | |
565 | mm->token_priority = 0; | |
566 | mm->last_interval = 0; | |
567 | ||
568 | tsk->mm = mm; | |
569 | tsk->active_mm = mm; | |
570 | return 0; | |
571 | ||
572 | fail_nomem: | |
573 | return retval; | |
574 | } | |
575 | ||
576 | static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old) | |
577 | { | |
578 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
579 | /* We don't need to lock fs - think why ;-) */ | |
580 | if (fs) { | |
581 | atomic_set(&fs->count, 1); | |
582 | rwlock_init(&fs->lock); | |
583 | fs->umask = old->umask; | |
584 | read_lock(&old->lock); | |
585 | fs->rootmnt = mntget(old->rootmnt); | |
586 | fs->root = dget(old->root); | |
587 | fs->pwdmnt = mntget(old->pwdmnt); | |
588 | fs->pwd = dget(old->pwd); | |
589 | if (old->altroot) { | |
590 | fs->altrootmnt = mntget(old->altrootmnt); | |
591 | fs->altroot = dget(old->altroot); | |
592 | } else { | |
593 | fs->altrootmnt = NULL; | |
594 | fs->altroot = NULL; | |
595 | } | |
596 | read_unlock(&old->lock); | |
597 | } | |
598 | return fs; | |
599 | } | |
600 | ||
601 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
602 | { | |
603 | return __copy_fs_struct(old); | |
604 | } | |
605 | ||
606 | EXPORT_SYMBOL_GPL(copy_fs_struct); | |
607 | ||
608 | static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk) | |
609 | { | |
610 | if (clone_flags & CLONE_FS) { | |
611 | atomic_inc(¤t->fs->count); | |
612 | return 0; | |
613 | } | |
614 | tsk->fs = __copy_fs_struct(current->fs); | |
615 | if (!tsk->fs) | |
616 | return -ENOMEM; | |
617 | return 0; | |
618 | } | |
619 | ||
620 | static int count_open_files(struct fdtable *fdt) | |
621 | { | |
622 | int size = fdt->max_fds; | |
623 | int i; | |
624 | ||
625 | /* Find the last open fd */ | |
626 | for (i = size/(8*sizeof(long)); i > 0; ) { | |
627 | if (fdt->open_fds->fds_bits[--i]) | |
628 | break; | |
629 | } | |
630 | i = (i+1) * 8 * sizeof(long); | |
631 | return i; | |
632 | } | |
633 | ||
634 | static struct files_struct *alloc_files(void) | |
635 | { | |
636 | struct files_struct *newf; | |
637 | struct fdtable *fdt; | |
638 | ||
639 | newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); | |
640 | if (!newf) | |
641 | goto out; | |
642 | ||
643 | atomic_set(&newf->count, 1); | |
644 | ||
645 | spin_lock_init(&newf->file_lock); | |
646 | newf->next_fd = 0; | |
647 | fdt = &newf->fdtab; | |
648 | fdt->max_fds = NR_OPEN_DEFAULT; | |
649 | fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init; | |
650 | fdt->open_fds = (fd_set *)&newf->open_fds_init; | |
651 | fdt->fd = &newf->fd_array[0]; | |
652 | INIT_RCU_HEAD(&fdt->rcu); | |
653 | fdt->next = NULL; | |
654 | rcu_assign_pointer(newf->fdt, fdt); | |
655 | out: | |
656 | return newf; | |
657 | } | |
658 | ||
659 | /* | |
660 | * Allocate a new files structure and copy contents from the | |
661 | * passed in files structure. | |
662 | * errorp will be valid only when the returned files_struct is NULL. | |
663 | */ | |
664 | static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) | |
665 | { | |
666 | struct files_struct *newf; | |
667 | struct file **old_fds, **new_fds; | |
668 | int open_files, size, i; | |
669 | struct fdtable *old_fdt, *new_fdt; | |
670 | ||
671 | *errorp = -ENOMEM; | |
672 | newf = alloc_files(); | |
673 | if (!newf) | |
674 | goto out; | |
675 | ||
676 | spin_lock(&oldf->file_lock); | |
677 | old_fdt = files_fdtable(oldf); | |
678 | new_fdt = files_fdtable(newf); | |
679 | open_files = count_open_files(old_fdt); | |
680 | ||
681 | /* | |
682 | * Check whether we need to allocate a larger fd array and fd set. | |
683 | * Note: we're not a clone task, so the open count won't change. | |
684 | */ | |
685 | if (open_files > new_fdt->max_fds) { | |
686 | new_fdt->max_fds = 0; | |
687 | spin_unlock(&oldf->file_lock); | |
688 | spin_lock(&newf->file_lock); | |
689 | *errorp = expand_files(newf, open_files-1); | |
690 | spin_unlock(&newf->file_lock); | |
691 | if (*errorp < 0) | |
692 | goto out_release; | |
693 | new_fdt = files_fdtable(newf); | |
694 | /* | |
695 | * Reacquire the oldf lock and a pointer to its fd table | |
696 | * who knows it may have a new bigger fd table. We need | |
697 | * the latest pointer. | |
698 | */ | |
699 | spin_lock(&oldf->file_lock); | |
700 | old_fdt = files_fdtable(oldf); | |
701 | } | |
702 | ||
703 | old_fds = old_fdt->fd; | |
704 | new_fds = new_fdt->fd; | |
705 | ||
706 | memcpy(new_fdt->open_fds->fds_bits, | |
707 | old_fdt->open_fds->fds_bits, open_files/8); | |
708 | memcpy(new_fdt->close_on_exec->fds_bits, | |
709 | old_fdt->close_on_exec->fds_bits, open_files/8); | |
710 | ||
711 | for (i = open_files; i != 0; i--) { | |
712 | struct file *f = *old_fds++; | |
713 | if (f) { | |
714 | get_file(f); | |
715 | } else { | |
716 | /* | |
717 | * The fd may be claimed in the fd bitmap but not yet | |
718 | * instantiated in the files array if a sibling thread | |
719 | * is partway through open(). So make sure that this | |
720 | * fd is available to the new process. | |
721 | */ | |
722 | FD_CLR(open_files - i, new_fdt->open_fds); | |
723 | } | |
724 | rcu_assign_pointer(*new_fds++, f); | |
725 | } | |
726 | spin_unlock(&oldf->file_lock); | |
727 | ||
728 | /* compute the remainder to be cleared */ | |
729 | size = (new_fdt->max_fds - open_files) * sizeof(struct file *); | |
730 | ||
731 | /* This is long word aligned thus could use a optimized version */ | |
732 | memset(new_fds, 0, size); | |
733 | ||
734 | if (new_fdt->max_fds > open_files) { | |
735 | int left = (new_fdt->max_fds-open_files)/8; | |
736 | int start = open_files / (8 * sizeof(unsigned long)); | |
737 | ||
738 | memset(&new_fdt->open_fds->fds_bits[start], 0, left); | |
739 | memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); | |
740 | } | |
741 | ||
742 | return newf; | |
743 | ||
744 | out_release: | |
745 | kmem_cache_free(files_cachep, newf); | |
746 | out: | |
747 | return NULL; | |
748 | } | |
749 | ||
750 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) | |
751 | { | |
752 | struct files_struct *oldf, *newf; | |
753 | int error = 0; | |
754 | ||
755 | /* | |
756 | * A background process may not have any files ... | |
757 | */ | |
758 | oldf = current->files; | |
759 | if (!oldf) | |
760 | goto out; | |
761 | ||
762 | if (clone_flags & CLONE_FILES) { | |
763 | atomic_inc(&oldf->count); | |
764 | goto out; | |
765 | } | |
766 | ||
767 | /* | |
768 | * Note: we may be using current for both targets (See exec.c) | |
769 | * This works because we cache current->files (old) as oldf. Don't | |
770 | * break this. | |
771 | */ | |
772 | tsk->files = NULL; | |
773 | newf = dup_fd(oldf, &error); | |
774 | if (!newf) | |
775 | goto out; | |
776 | ||
777 | tsk->files = newf; | |
778 | error = 0; | |
779 | out: | |
780 | return error; | |
781 | } | |
782 | ||
783 | /* | |
784 | * Helper to unshare the files of the current task. | |
785 | * We don't want to expose copy_files internals to | |
786 | * the exec layer of the kernel. | |
787 | */ | |
788 | ||
789 | int unshare_files(void) | |
790 | { | |
791 | struct files_struct *files = current->files; | |
792 | int rc; | |
793 | ||
794 | BUG_ON(!files); | |
795 | ||
796 | /* This can race but the race causes us to copy when we don't | |
797 | need to and drop the copy */ | |
798 | if(atomic_read(&files->count) == 1) | |
799 | { | |
800 | atomic_inc(&files->count); | |
801 | return 0; | |
802 | } | |
803 | rc = copy_files(0, current); | |
804 | if(rc) | |
805 | current->files = files; | |
806 | return rc; | |
807 | } | |
808 | ||
809 | EXPORT_SYMBOL(unshare_files); | |
810 | ||
811 | static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk) | |
812 | { | |
813 | struct sighand_struct *sig; | |
814 | ||
815 | if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { | |
816 | atomic_inc(¤t->sighand->count); | |
817 | return 0; | |
818 | } | |
819 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
820 | rcu_assign_pointer(tsk->sighand, sig); | |
821 | if (!sig) | |
822 | return -ENOMEM; | |
823 | atomic_set(&sig->count, 1); | |
824 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
825 | return 0; | |
826 | } | |
827 | ||
828 | void __cleanup_sighand(struct sighand_struct *sighand) | |
829 | { | |
830 | if (atomic_dec_and_test(&sighand->count)) | |
831 | kmem_cache_free(sighand_cachep, sighand); | |
832 | } | |
833 | ||
834 | static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk) | |
835 | { | |
836 | struct signal_struct *sig; | |
837 | int ret; | |
838 | ||
839 | if (clone_flags & CLONE_THREAD) { | |
840 | atomic_inc(¤t->signal->count); | |
841 | atomic_inc(¤t->signal->live); | |
842 | return 0; | |
843 | } | |
844 | sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); | |
845 | tsk->signal = sig; | |
846 | if (!sig) | |
847 | return -ENOMEM; | |
848 | ||
849 | ret = copy_thread_group_keys(tsk); | |
850 | if (ret < 0) { | |
851 | kmem_cache_free(signal_cachep, sig); | |
852 | return ret; | |
853 | } | |
854 | ||
855 | atomic_set(&sig->count, 1); | |
856 | atomic_set(&sig->live, 1); | |
857 | init_waitqueue_head(&sig->wait_chldexit); | |
858 | sig->flags = 0; | |
859 | sig->group_exit_code = 0; | |
860 | sig->group_exit_task = NULL; | |
861 | sig->group_stop_count = 0; | |
862 | sig->curr_target = NULL; | |
863 | init_sigpending(&sig->shared_pending); | |
864 | INIT_LIST_HEAD(&sig->posix_timers); | |
865 | ||
866 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
867 | sig->it_real_incr.tv64 = 0; | |
868 | sig->real_timer.function = it_real_fn; | |
869 | sig->tsk = tsk; | |
870 | ||
871 | sig->it_virt_expires = cputime_zero; | |
872 | sig->it_virt_incr = cputime_zero; | |
873 | sig->it_prof_expires = cputime_zero; | |
874 | sig->it_prof_incr = cputime_zero; | |
875 | ||
876 | sig->leader = 0; /* session leadership doesn't inherit */ | |
877 | sig->tty_old_pgrp = NULL; | |
878 | ||
879 | sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; | |
880 | sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; | |
881 | sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; | |
882 | sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0; | |
883 | sig->sum_sched_runtime = 0; | |
884 | INIT_LIST_HEAD(&sig->cpu_timers[0]); | |
885 | INIT_LIST_HEAD(&sig->cpu_timers[1]); | |
886 | INIT_LIST_HEAD(&sig->cpu_timers[2]); | |
887 | taskstats_tgid_init(sig); | |
888 | ||
889 | task_lock(current->group_leader); | |
890 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
891 | task_unlock(current->group_leader); | |
892 | ||
893 | if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { | |
894 | /* | |
895 | * New sole thread in the process gets an expiry time | |
896 | * of the whole CPU time limit. | |
897 | */ | |
898 | tsk->it_prof_expires = | |
899 | secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); | |
900 | } | |
901 | acct_init_pacct(&sig->pacct); | |
902 | ||
903 | tty_audit_fork(sig); | |
904 | ||
905 | return 0; | |
906 | } | |
907 | ||
908 | void __cleanup_signal(struct signal_struct *sig) | |
909 | { | |
910 | exit_thread_group_keys(sig); | |
911 | kmem_cache_free(signal_cachep, sig); | |
912 | } | |
913 | ||
914 | static inline void cleanup_signal(struct task_struct *tsk) | |
915 | { | |
916 | struct signal_struct *sig = tsk->signal; | |
917 | ||
918 | atomic_dec(&sig->live); | |
919 | ||
920 | if (atomic_dec_and_test(&sig->count)) | |
921 | __cleanup_signal(sig); | |
922 | } | |
923 | ||
924 | static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) | |
925 | { | |
926 | unsigned long new_flags = p->flags; | |
927 | ||
928 | new_flags &= ~PF_SUPERPRIV; | |
929 | new_flags |= PF_FORKNOEXEC; | |
930 | if (!(clone_flags & CLONE_PTRACE)) | |
931 | p->ptrace = 0; | |
932 | p->flags = new_flags; | |
933 | } | |
934 | ||
935 | asmlinkage long sys_set_tid_address(int __user *tidptr) | |
936 | { | |
937 | current->clear_child_tid = tidptr; | |
938 | ||
939 | return current->pid; | |
940 | } | |
941 | ||
942 | static inline void rt_mutex_init_task(struct task_struct *p) | |
943 | { | |
944 | spin_lock_init(&p->pi_lock); | |
945 | #ifdef CONFIG_RT_MUTEXES | |
946 | plist_head_init(&p->pi_waiters, &p->pi_lock); | |
947 | p->pi_blocked_on = NULL; | |
948 | #endif | |
949 | } | |
950 | ||
951 | /* | |
952 | * This creates a new process as a copy of the old one, | |
953 | * but does not actually start it yet. | |
954 | * | |
955 | * It copies the registers, and all the appropriate | |
956 | * parts of the process environment (as per the clone | |
957 | * flags). The actual kick-off is left to the caller. | |
958 | */ | |
959 | static struct task_struct *copy_process(unsigned long clone_flags, | |
960 | unsigned long stack_start, | |
961 | struct pt_regs *regs, | |
962 | unsigned long stack_size, | |
963 | int __user *parent_tidptr, | |
964 | int __user *child_tidptr, | |
965 | struct pid *pid) | |
966 | { | |
967 | int retval; | |
968 | struct task_struct *p = NULL; | |
969 | ||
970 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
971 | return ERR_PTR(-EINVAL); | |
972 | ||
973 | /* | |
974 | * Thread groups must share signals as well, and detached threads | |
975 | * can only be started up within the thread group. | |
976 | */ | |
977 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
978 | return ERR_PTR(-EINVAL); | |
979 | ||
980 | /* | |
981 | * Shared signal handlers imply shared VM. By way of the above, | |
982 | * thread groups also imply shared VM. Blocking this case allows | |
983 | * for various simplifications in other code. | |
984 | */ | |
985 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
986 | return ERR_PTR(-EINVAL); | |
987 | ||
988 | retval = security_task_create(clone_flags); | |
989 | if (retval) | |
990 | goto fork_out; | |
991 | ||
992 | retval = -ENOMEM; | |
993 | p = dup_task_struct(current); | |
994 | if (!p) | |
995 | goto fork_out; | |
996 | ||
997 | rt_mutex_init_task(p); | |
998 | ||
999 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1000 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); | |
1001 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); | |
1002 | #endif | |
1003 | retval = -EAGAIN; | |
1004 | if (atomic_read(&p->user->processes) >= | |
1005 | p->signal->rlim[RLIMIT_NPROC].rlim_cur) { | |
1006 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && | |
1007 | p->user != current->nsproxy->user_ns->root_user) | |
1008 | goto bad_fork_free; | |
1009 | } | |
1010 | ||
1011 | atomic_inc(&p->user->__count); | |
1012 | atomic_inc(&p->user->processes); | |
1013 | get_group_info(p->group_info); | |
1014 | ||
1015 | /* | |
1016 | * If multiple threads are within copy_process(), then this check | |
1017 | * triggers too late. This doesn't hurt, the check is only there | |
1018 | * to stop root fork bombs. | |
1019 | */ | |
1020 | if (nr_threads >= max_threads) | |
1021 | goto bad_fork_cleanup_count; | |
1022 | ||
1023 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) | |
1024 | goto bad_fork_cleanup_count; | |
1025 | ||
1026 | if (p->binfmt && !try_module_get(p->binfmt->module)) | |
1027 | goto bad_fork_cleanup_put_domain; | |
1028 | ||
1029 | p->did_exec = 0; | |
1030 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ | |
1031 | copy_flags(clone_flags, p); | |
1032 | p->pid = pid_nr(pid); | |
1033 | retval = -EFAULT; | |
1034 | if (clone_flags & CLONE_PARENT_SETTID) | |
1035 | if (put_user(p->pid, parent_tidptr)) | |
1036 | goto bad_fork_cleanup_delays_binfmt; | |
1037 | ||
1038 | INIT_LIST_HEAD(&p->children); | |
1039 | INIT_LIST_HEAD(&p->sibling); | |
1040 | p->vfork_done = NULL; | |
1041 | spin_lock_init(&p->alloc_lock); | |
1042 | ||
1043 | clear_tsk_thread_flag(p, TIF_SIGPENDING); | |
1044 | init_sigpending(&p->pending); | |
1045 | ||
1046 | p->utime = cputime_zero; | |
1047 | p->stime = cputime_zero; | |
1048 | ||
1049 | #ifdef CONFIG_TASK_XACCT | |
1050 | p->rchar = 0; /* I/O counter: bytes read */ | |
1051 | p->wchar = 0; /* I/O counter: bytes written */ | |
1052 | p->syscr = 0; /* I/O counter: read syscalls */ | |
1053 | p->syscw = 0; /* I/O counter: write syscalls */ | |
1054 | #endif | |
1055 | task_io_accounting_init(p); | |
1056 | acct_clear_integrals(p); | |
1057 | ||
1058 | p->it_virt_expires = cputime_zero; | |
1059 | p->it_prof_expires = cputime_zero; | |
1060 | p->it_sched_expires = 0; | |
1061 | INIT_LIST_HEAD(&p->cpu_timers[0]); | |
1062 | INIT_LIST_HEAD(&p->cpu_timers[1]); | |
1063 | INIT_LIST_HEAD(&p->cpu_timers[2]); | |
1064 | ||
1065 | p->lock_depth = -1; /* -1 = no lock */ | |
1066 | do_posix_clock_monotonic_gettime(&p->start_time); | |
1067 | p->real_start_time = p->start_time; | |
1068 | monotonic_to_bootbased(&p->real_start_time); | |
1069 | p->security = NULL; | |
1070 | p->io_context = NULL; | |
1071 | p->io_wait = NULL; | |
1072 | p->audit_context = NULL; | |
1073 | cpuset_fork(p); | |
1074 | #ifdef CONFIG_NUMA | |
1075 | p->mempolicy = mpol_copy(p->mempolicy); | |
1076 | if (IS_ERR(p->mempolicy)) { | |
1077 | retval = PTR_ERR(p->mempolicy); | |
1078 | p->mempolicy = NULL; | |
1079 | goto bad_fork_cleanup_cpuset; | |
1080 | } | |
1081 | mpol_fix_fork_child_flag(p); | |
1082 | #endif | |
1083 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1084 | p->irq_events = 0; | |
1085 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW | |
1086 | p->hardirqs_enabled = 1; | |
1087 | #else | |
1088 | p->hardirqs_enabled = 0; | |
1089 | #endif | |
1090 | p->hardirq_enable_ip = 0; | |
1091 | p->hardirq_enable_event = 0; | |
1092 | p->hardirq_disable_ip = _THIS_IP_; | |
1093 | p->hardirq_disable_event = 0; | |
1094 | p->softirqs_enabled = 1; | |
1095 | p->softirq_enable_ip = _THIS_IP_; | |
1096 | p->softirq_enable_event = 0; | |
1097 | p->softirq_disable_ip = 0; | |
1098 | p->softirq_disable_event = 0; | |
1099 | p->hardirq_context = 0; | |
1100 | p->softirq_context = 0; | |
1101 | #endif | |
1102 | #ifdef CONFIG_LOCKDEP | |
1103 | p->lockdep_depth = 0; /* no locks held yet */ | |
1104 | p->curr_chain_key = 0; | |
1105 | p->lockdep_recursion = 0; | |
1106 | #endif | |
1107 | ||
1108 | #ifdef CONFIG_DEBUG_MUTEXES | |
1109 | p->blocked_on = NULL; /* not blocked yet */ | |
1110 | #endif | |
1111 | ||
1112 | p->tgid = p->pid; | |
1113 | if (clone_flags & CLONE_THREAD) | |
1114 | p->tgid = current->tgid; | |
1115 | ||
1116 | if ((retval = security_task_alloc(p))) | |
1117 | goto bad_fork_cleanup_policy; | |
1118 | if ((retval = audit_alloc(p))) | |
1119 | goto bad_fork_cleanup_security; | |
1120 | /* copy all the process information */ | |
1121 | if ((retval = copy_semundo(clone_flags, p))) | |
1122 | goto bad_fork_cleanup_audit; | |
1123 | if ((retval = copy_files(clone_flags, p))) | |
1124 | goto bad_fork_cleanup_semundo; | |
1125 | if ((retval = copy_fs(clone_flags, p))) | |
1126 | goto bad_fork_cleanup_files; | |
1127 | if ((retval = copy_sighand(clone_flags, p))) | |
1128 | goto bad_fork_cleanup_fs; | |
1129 | if ((retval = copy_signal(clone_flags, p))) | |
1130 | goto bad_fork_cleanup_sighand; | |
1131 | if ((retval = copy_mm(clone_flags, p))) | |
1132 | goto bad_fork_cleanup_signal; | |
1133 | if ((retval = copy_keys(clone_flags, p))) | |
1134 | goto bad_fork_cleanup_mm; | |
1135 | if ((retval = copy_namespaces(clone_flags, p))) | |
1136 | goto bad_fork_cleanup_keys; | |
1137 | retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); | |
1138 | if (retval) | |
1139 | goto bad_fork_cleanup_namespaces; | |
1140 | ||
1141 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; | |
1142 | /* | |
1143 | * Clear TID on mm_release()? | |
1144 | */ | |
1145 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; | |
1146 | p->robust_list = NULL; | |
1147 | #ifdef CONFIG_COMPAT | |
1148 | p->compat_robust_list = NULL; | |
1149 | #endif | |
1150 | INIT_LIST_HEAD(&p->pi_state_list); | |
1151 | p->pi_state_cache = NULL; | |
1152 | ||
1153 | /* | |
1154 | * sigaltstack should be cleared when sharing the same VM | |
1155 | */ | |
1156 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) | |
1157 | p->sas_ss_sp = p->sas_ss_size = 0; | |
1158 | ||
1159 | /* | |
1160 | * Syscall tracing should be turned off in the child regardless | |
1161 | * of CLONE_PTRACE. | |
1162 | */ | |
1163 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); | |
1164 | #ifdef TIF_SYSCALL_EMU | |
1165 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); | |
1166 | #endif | |
1167 | ||
1168 | /* Our parent execution domain becomes current domain | |
1169 | These must match for thread signalling to apply */ | |
1170 | p->parent_exec_id = p->self_exec_id; | |
1171 | ||
1172 | /* ok, now we should be set up.. */ | |
1173 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); | |
1174 | p->pdeath_signal = 0; | |
1175 | p->exit_state = 0; | |
1176 | ||
1177 | /* | |
1178 | * Ok, make it visible to the rest of the system. | |
1179 | * We dont wake it up yet. | |
1180 | */ | |
1181 | p->group_leader = p; | |
1182 | INIT_LIST_HEAD(&p->thread_group); | |
1183 | INIT_LIST_HEAD(&p->ptrace_children); | |
1184 | INIT_LIST_HEAD(&p->ptrace_list); | |
1185 | ||
1186 | /* Perform scheduler related setup. Assign this task to a CPU. */ | |
1187 | sched_fork(p, clone_flags); | |
1188 | ||
1189 | /* Need tasklist lock for parent etc handling! */ | |
1190 | write_lock_irq(&tasklist_lock); | |
1191 | ||
1192 | /* for sys_ioprio_set(IOPRIO_WHO_PGRP) */ | |
1193 | p->ioprio = current->ioprio; | |
1194 | ||
1195 | /* | |
1196 | * The task hasn't been attached yet, so its cpus_allowed mask will | |
1197 | * not be changed, nor will its assigned CPU. | |
1198 | * | |
1199 | * The cpus_allowed mask of the parent may have changed after it was | |
1200 | * copied first time - so re-copy it here, then check the child's CPU | |
1201 | * to ensure it is on a valid CPU (and if not, just force it back to | |
1202 | * parent's CPU). This avoids alot of nasty races. | |
1203 | */ | |
1204 | p->cpus_allowed = current->cpus_allowed; | |
1205 | if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) || | |
1206 | !cpu_online(task_cpu(p)))) | |
1207 | set_task_cpu(p, smp_processor_id()); | |
1208 | ||
1209 | /* CLONE_PARENT re-uses the old parent */ | |
1210 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) | |
1211 | p->real_parent = current->real_parent; | |
1212 | else | |
1213 | p->real_parent = current; | |
1214 | p->parent = p->real_parent; | |
1215 | ||
1216 | spin_lock(¤t->sighand->siglock); | |
1217 | ||
1218 | /* | |
1219 | * Process group and session signals need to be delivered to just the | |
1220 | * parent before the fork or both the parent and the child after the | |
1221 | * fork. Restart if a signal comes in before we add the new process to | |
1222 | * it's process group. | |
1223 | * A fatal signal pending means that current will exit, so the new | |
1224 | * thread can't slip out of an OOM kill (or normal SIGKILL). | |
1225 | */ | |
1226 | recalc_sigpending(); | |
1227 | if (signal_pending(current)) { | |
1228 | spin_unlock(¤t->sighand->siglock); | |
1229 | write_unlock_irq(&tasklist_lock); | |
1230 | retval = -ERESTARTNOINTR; | |
1231 | goto bad_fork_cleanup_namespaces; | |
1232 | } | |
1233 | ||
1234 | if (clone_flags & CLONE_THREAD) { | |
1235 | p->group_leader = current->group_leader; | |
1236 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); | |
1237 | ||
1238 | if (!cputime_eq(current->signal->it_virt_expires, | |
1239 | cputime_zero) || | |
1240 | !cputime_eq(current->signal->it_prof_expires, | |
1241 | cputime_zero) || | |
1242 | current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || | |
1243 | !list_empty(¤t->signal->cpu_timers[0]) || | |
1244 | !list_empty(¤t->signal->cpu_timers[1]) || | |
1245 | !list_empty(¤t->signal->cpu_timers[2])) { | |
1246 | /* | |
1247 | * Have child wake up on its first tick to check | |
1248 | * for process CPU timers. | |
1249 | */ | |
1250 | p->it_prof_expires = jiffies_to_cputime(1); | |
1251 | } | |
1252 | } | |
1253 | ||
1254 | if (likely(p->pid)) { | |
1255 | add_parent(p); | |
1256 | if (unlikely(p->ptrace & PT_PTRACED)) | |
1257 | __ptrace_link(p, current->parent); | |
1258 | ||
1259 | if (thread_group_leader(p)) { | |
1260 | p->signal->tty = current->signal->tty; | |
1261 | p->signal->pgrp = process_group(current); | |
1262 | set_signal_session(p->signal, process_session(current)); | |
1263 | attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); | |
1264 | attach_pid(p, PIDTYPE_SID, task_session(current)); | |
1265 | ||
1266 | list_add_tail_rcu(&p->tasks, &init_task.tasks); | |
1267 | __get_cpu_var(process_counts)++; | |
1268 | } | |
1269 | attach_pid(p, PIDTYPE_PID, pid); | |
1270 | nr_threads++; | |
1271 | } | |
1272 | ||
1273 | total_forks++; | |
1274 | spin_unlock(¤t->sighand->siglock); | |
1275 | write_unlock_irq(&tasklist_lock); | |
1276 | proc_fork_connector(p); | |
1277 | return p; | |
1278 | ||
1279 | bad_fork_cleanup_namespaces: | |
1280 | exit_task_namespaces(p); | |
1281 | bad_fork_cleanup_keys: | |
1282 | exit_keys(p); | |
1283 | bad_fork_cleanup_mm: | |
1284 | if (p->mm) | |
1285 | mmput(p->mm); | |
1286 | bad_fork_cleanup_signal: | |
1287 | cleanup_signal(p); | |
1288 | bad_fork_cleanup_sighand: | |
1289 | __cleanup_sighand(p->sighand); | |
1290 | bad_fork_cleanup_fs: | |
1291 | exit_fs(p); /* blocking */ | |
1292 | bad_fork_cleanup_files: | |
1293 | exit_files(p); /* blocking */ | |
1294 | bad_fork_cleanup_semundo: | |
1295 | exit_sem(p); | |
1296 | bad_fork_cleanup_audit: | |
1297 | audit_free(p); | |
1298 | bad_fork_cleanup_security: | |
1299 | security_task_free(p); | |
1300 | bad_fork_cleanup_policy: | |
1301 | #ifdef CONFIG_NUMA | |
1302 | mpol_free(p->mempolicy); | |
1303 | bad_fork_cleanup_cpuset: | |
1304 | #endif | |
1305 | cpuset_exit(p); | |
1306 | bad_fork_cleanup_delays_binfmt: | |
1307 | delayacct_tsk_free(p); | |
1308 | if (p->binfmt) | |
1309 | module_put(p->binfmt->module); | |
1310 | bad_fork_cleanup_put_domain: | |
1311 | module_put(task_thread_info(p)->exec_domain->module); | |
1312 | bad_fork_cleanup_count: | |
1313 | put_group_info(p->group_info); | |
1314 | atomic_dec(&p->user->processes); | |
1315 | free_uid(p->user); | |
1316 | bad_fork_free: | |
1317 | free_task(p); | |
1318 | fork_out: | |
1319 | return ERR_PTR(retval); | |
1320 | } | |
1321 | ||
1322 | noinline struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs) | |
1323 | { | |
1324 | memset(regs, 0, sizeof(struct pt_regs)); | |
1325 | return regs; | |
1326 | } | |
1327 | ||
1328 | struct task_struct * __cpuinit fork_idle(int cpu) | |
1329 | { | |
1330 | struct task_struct *task; | |
1331 | struct pt_regs regs; | |
1332 | ||
1333 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, | |
1334 | &init_struct_pid); | |
1335 | if (!IS_ERR(task)) | |
1336 | init_idle(task, cpu); | |
1337 | ||
1338 | return task; | |
1339 | } | |
1340 | ||
1341 | static inline int fork_traceflag (unsigned clone_flags) | |
1342 | { | |
1343 | if (clone_flags & CLONE_UNTRACED) | |
1344 | return 0; | |
1345 | else if (clone_flags & CLONE_VFORK) { | |
1346 | if (current->ptrace & PT_TRACE_VFORK) | |
1347 | return PTRACE_EVENT_VFORK; | |
1348 | } else if ((clone_flags & CSIGNAL) != SIGCHLD) { | |
1349 | if (current->ptrace & PT_TRACE_CLONE) | |
1350 | return PTRACE_EVENT_CLONE; | |
1351 | } else if (current->ptrace & PT_TRACE_FORK) | |
1352 | return PTRACE_EVENT_FORK; | |
1353 | ||
1354 | return 0; | |
1355 | } | |
1356 | ||
1357 | /* | |
1358 | * Ok, this is the main fork-routine. | |
1359 | * | |
1360 | * It copies the process, and if successful kick-starts | |
1361 | * it and waits for it to finish using the VM if required. | |
1362 | */ | |
1363 | long do_fork(unsigned long clone_flags, | |
1364 | unsigned long stack_start, | |
1365 | struct pt_regs *regs, | |
1366 | unsigned long stack_size, | |
1367 | int __user *parent_tidptr, | |
1368 | int __user *child_tidptr) | |
1369 | { | |
1370 | struct task_struct *p; | |
1371 | int trace = 0; | |
1372 | struct pid *pid = alloc_pid(); | |
1373 | long nr; | |
1374 | ||
1375 | if (!pid) | |
1376 | return -EAGAIN; | |
1377 | nr = pid->nr; | |
1378 | if (unlikely(current->ptrace)) { | |
1379 | trace = fork_traceflag (clone_flags); | |
1380 | if (trace) | |
1381 | clone_flags |= CLONE_PTRACE; | |
1382 | } | |
1383 | ||
1384 | p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid); | |
1385 | /* | |
1386 | * Do this prior waking up the new thread - the thread pointer | |
1387 | * might get invalid after that point, if the thread exits quickly. | |
1388 | */ | |
1389 | if (!IS_ERR(p)) { | |
1390 | struct completion vfork; | |
1391 | ||
1392 | if (clone_flags & CLONE_VFORK) { | |
1393 | p->vfork_done = &vfork; | |
1394 | init_completion(&vfork); | |
1395 | } | |
1396 | ||
1397 | if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { | |
1398 | /* | |
1399 | * We'll start up with an immediate SIGSTOP. | |
1400 | */ | |
1401 | sigaddset(&p->pending.signal, SIGSTOP); | |
1402 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1403 | } | |
1404 | ||
1405 | if (!(clone_flags & CLONE_STOPPED)) | |
1406 | wake_up_new_task(p, clone_flags); | |
1407 | else | |
1408 | p->state = TASK_STOPPED; | |
1409 | ||
1410 | if (unlikely (trace)) { | |
1411 | current->ptrace_message = nr; | |
1412 | ptrace_notify ((trace << 8) | SIGTRAP); | |
1413 | } | |
1414 | ||
1415 | if (clone_flags & CLONE_VFORK) { | |
1416 | freezer_do_not_count(); | |
1417 | wait_for_completion(&vfork); | |
1418 | freezer_count(); | |
1419 | if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) { | |
1420 | current->ptrace_message = nr; | |
1421 | ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); | |
1422 | } | |
1423 | } | |
1424 | } else { | |
1425 | free_pid(pid); | |
1426 | nr = PTR_ERR(p); | |
1427 | } | |
1428 | return nr; | |
1429 | } | |
1430 | ||
1431 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN | |
1432 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 | |
1433 | #endif | |
1434 | ||
1435 | static void sighand_ctor(void *data, struct kmem_cache *cachep, | |
1436 | unsigned long flags) | |
1437 | { | |
1438 | struct sighand_struct *sighand = data; | |
1439 | ||
1440 | spin_lock_init(&sighand->siglock); | |
1441 | init_waitqueue_head(&sighand->signalfd_wqh); | |
1442 | } | |
1443 | ||
1444 | void __init proc_caches_init(void) | |
1445 | { | |
1446 | sighand_cachep = kmem_cache_create("sighand_cache", | |
1447 | sizeof(struct sighand_struct), 0, | |
1448 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, | |
1449 | sighand_ctor); | |
1450 | signal_cachep = kmem_cache_create("signal_cache", | |
1451 | sizeof(struct signal_struct), 0, | |
1452 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1453 | files_cachep = kmem_cache_create("files_cache", | |
1454 | sizeof(struct files_struct), 0, | |
1455 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1456 | fs_cachep = kmem_cache_create("fs_cache", | |
1457 | sizeof(struct fs_struct), 0, | |
1458 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1459 | vm_area_cachep = kmem_cache_create("vm_area_struct", | |
1460 | sizeof(struct vm_area_struct), 0, | |
1461 | SLAB_PANIC, NULL); | |
1462 | mm_cachep = kmem_cache_create("mm_struct", | |
1463 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, | |
1464 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1465 | } | |
1466 | ||
1467 | /* | |
1468 | * Check constraints on flags passed to the unshare system call and | |
1469 | * force unsharing of additional process context as appropriate. | |
1470 | */ | |
1471 | static inline void check_unshare_flags(unsigned long *flags_ptr) | |
1472 | { | |
1473 | /* | |
1474 | * If unsharing a thread from a thread group, must also | |
1475 | * unshare vm. | |
1476 | */ | |
1477 | if (*flags_ptr & CLONE_THREAD) | |
1478 | *flags_ptr |= CLONE_VM; | |
1479 | ||
1480 | /* | |
1481 | * If unsharing vm, must also unshare signal handlers. | |
1482 | */ | |
1483 | if (*flags_ptr & CLONE_VM) | |
1484 | *flags_ptr |= CLONE_SIGHAND; | |
1485 | ||
1486 | /* | |
1487 | * If unsharing signal handlers and the task was created | |
1488 | * using CLONE_THREAD, then must unshare the thread | |
1489 | */ | |
1490 | if ((*flags_ptr & CLONE_SIGHAND) && | |
1491 | (atomic_read(¤t->signal->count) > 1)) | |
1492 | *flags_ptr |= CLONE_THREAD; | |
1493 | ||
1494 | /* | |
1495 | * If unsharing namespace, must also unshare filesystem information. | |
1496 | */ | |
1497 | if (*flags_ptr & CLONE_NEWNS) | |
1498 | *flags_ptr |= CLONE_FS; | |
1499 | } | |
1500 | ||
1501 | /* | |
1502 | * Unsharing of tasks created with CLONE_THREAD is not supported yet | |
1503 | */ | |
1504 | static int unshare_thread(unsigned long unshare_flags) | |
1505 | { | |
1506 | if (unshare_flags & CLONE_THREAD) | |
1507 | return -EINVAL; | |
1508 | ||
1509 | return 0; | |
1510 | } | |
1511 | ||
1512 | /* | |
1513 | * Unshare the filesystem structure if it is being shared | |
1514 | */ | |
1515 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) | |
1516 | { | |
1517 | struct fs_struct *fs = current->fs; | |
1518 | ||
1519 | if ((unshare_flags & CLONE_FS) && | |
1520 | (fs && atomic_read(&fs->count) > 1)) { | |
1521 | *new_fsp = __copy_fs_struct(current->fs); | |
1522 | if (!*new_fsp) | |
1523 | return -ENOMEM; | |
1524 | } | |
1525 | ||
1526 | return 0; | |
1527 | } | |
1528 | ||
1529 | /* | |
1530 | * Unsharing of sighand is not supported yet | |
1531 | */ | |
1532 | static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) | |
1533 | { | |
1534 | struct sighand_struct *sigh = current->sighand; | |
1535 | ||
1536 | if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) | |
1537 | return -EINVAL; | |
1538 | else | |
1539 | return 0; | |
1540 | } | |
1541 | ||
1542 | /* | |
1543 | * Unshare vm if it is being shared | |
1544 | */ | |
1545 | static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) | |
1546 | { | |
1547 | struct mm_struct *mm = current->mm; | |
1548 | ||
1549 | if ((unshare_flags & CLONE_VM) && | |
1550 | (mm && atomic_read(&mm->mm_users) > 1)) { | |
1551 | return -EINVAL; | |
1552 | } | |
1553 | ||
1554 | return 0; | |
1555 | } | |
1556 | ||
1557 | /* | |
1558 | * Unshare file descriptor table if it is being shared | |
1559 | */ | |
1560 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) | |
1561 | { | |
1562 | struct files_struct *fd = current->files; | |
1563 | int error = 0; | |
1564 | ||
1565 | if ((unshare_flags & CLONE_FILES) && | |
1566 | (fd && atomic_read(&fd->count) > 1)) { | |
1567 | *new_fdp = dup_fd(fd, &error); | |
1568 | if (!*new_fdp) | |
1569 | return error; | |
1570 | } | |
1571 | ||
1572 | return 0; | |
1573 | } | |
1574 | ||
1575 | /* | |
1576 | * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not | |
1577 | * supported yet | |
1578 | */ | |
1579 | static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp) | |
1580 | { | |
1581 | if (unshare_flags & CLONE_SYSVSEM) | |
1582 | return -EINVAL; | |
1583 | ||
1584 | return 0; | |
1585 | } | |
1586 | ||
1587 | /* | |
1588 | * unshare allows a process to 'unshare' part of the process | |
1589 | * context which was originally shared using clone. copy_* | |
1590 | * functions used by do_fork() cannot be used here directly | |
1591 | * because they modify an inactive task_struct that is being | |
1592 | * constructed. Here we are modifying the current, active, | |
1593 | * task_struct. | |
1594 | */ | |
1595 | asmlinkage long sys_unshare(unsigned long unshare_flags) | |
1596 | { | |
1597 | int err = 0; | |
1598 | struct fs_struct *fs, *new_fs = NULL; | |
1599 | struct sighand_struct *new_sigh = NULL; | |
1600 | struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; | |
1601 | struct files_struct *fd, *new_fd = NULL; | |
1602 | struct sem_undo_list *new_ulist = NULL; | |
1603 | struct nsproxy *new_nsproxy = NULL, *old_nsproxy = NULL; | |
1604 | ||
1605 | check_unshare_flags(&unshare_flags); | |
1606 | ||
1607 | /* Return -EINVAL for all unsupported flags */ | |
1608 | err = -EINVAL; | |
1609 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| | |
1610 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| | |
1611 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER)) | |
1612 | goto bad_unshare_out; | |
1613 | ||
1614 | if ((err = unshare_thread(unshare_flags))) | |
1615 | goto bad_unshare_out; | |
1616 | if ((err = unshare_fs(unshare_flags, &new_fs))) | |
1617 | goto bad_unshare_cleanup_thread; | |
1618 | if ((err = unshare_sighand(unshare_flags, &new_sigh))) | |
1619 | goto bad_unshare_cleanup_fs; | |
1620 | if ((err = unshare_vm(unshare_flags, &new_mm))) | |
1621 | goto bad_unshare_cleanup_sigh; | |
1622 | if ((err = unshare_fd(unshare_flags, &new_fd))) | |
1623 | goto bad_unshare_cleanup_vm; | |
1624 | if ((err = unshare_semundo(unshare_flags, &new_ulist))) | |
1625 | goto bad_unshare_cleanup_fd; | |
1626 | if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, | |
1627 | new_fs))) | |
1628 | goto bad_unshare_cleanup_semundo; | |
1629 | ||
1630 | if (new_fs || new_mm || new_fd || new_ulist || new_nsproxy) { | |
1631 | ||
1632 | task_lock(current); | |
1633 | ||
1634 | if (new_nsproxy) { | |
1635 | old_nsproxy = current->nsproxy; | |
1636 | current->nsproxy = new_nsproxy; | |
1637 | new_nsproxy = old_nsproxy; | |
1638 | } | |
1639 | ||
1640 | if (new_fs) { | |
1641 | fs = current->fs; | |
1642 | current->fs = new_fs; | |
1643 | new_fs = fs; | |
1644 | } | |
1645 | ||
1646 | if (new_mm) { | |
1647 | mm = current->mm; | |
1648 | active_mm = current->active_mm; | |
1649 | current->mm = new_mm; | |
1650 | current->active_mm = new_mm; | |
1651 | activate_mm(active_mm, new_mm); | |
1652 | new_mm = mm; | |
1653 | } | |
1654 | ||
1655 | if (new_fd) { | |
1656 | fd = current->files; | |
1657 | current->files = new_fd; | |
1658 | new_fd = fd; | |
1659 | } | |
1660 | ||
1661 | task_unlock(current); | |
1662 | } | |
1663 | ||
1664 | if (new_nsproxy) | |
1665 | put_nsproxy(new_nsproxy); | |
1666 | ||
1667 | bad_unshare_cleanup_semundo: | |
1668 | bad_unshare_cleanup_fd: | |
1669 | if (new_fd) | |
1670 | put_files_struct(new_fd); | |
1671 | ||
1672 | bad_unshare_cleanup_vm: | |
1673 | if (new_mm) | |
1674 | mmput(new_mm); | |
1675 | ||
1676 | bad_unshare_cleanup_sigh: | |
1677 | if (new_sigh) | |
1678 | if (atomic_dec_and_test(&new_sigh->count)) | |
1679 | kmem_cache_free(sighand_cachep, new_sigh); | |
1680 | ||
1681 | bad_unshare_cleanup_fs: | |
1682 | if (new_fs) | |
1683 | put_fs_struct(new_fs); | |
1684 | ||
1685 | bad_unshare_cleanup_thread: | |
1686 | bad_unshare_out: | |
1687 | return err; | |
1688 | } |