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