]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * linux/kernel/fork.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * 'fork.c' contains the help-routines for the 'fork' system call | |
9 | * (see also entry.S and others). | |
10 | * Fork is rather simple, once you get the hang of it, but the memory | |
11 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' | |
12 | */ | |
13 | ||
14 | #include <linux/slab.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/unistd.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/vmalloc.h> | |
19 | #include <linux/completion.h> | |
20 | #include <linux/personality.h> | |
21 | #include <linux/mempolicy.h> | |
22 | #include <linux/sem.h> | |
23 | #include <linux/file.h> | |
24 | #include <linux/fdtable.h> | |
25 | #include <linux/iocontext.h> | |
26 | #include <linux/key.h> | |
27 | #include <linux/binfmts.h> | |
28 | #include <linux/mman.h> | |
29 | #include <linux/mmu_notifier.h> | |
30 | #include <linux/fs.h> | |
31 | #include <linux/nsproxy.h> | |
32 | #include <linux/capability.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/cgroup.h> | |
35 | #include <linux/security.h> | |
36 | #include <linux/hugetlb.h> | |
37 | #include <linux/swap.h> | |
38 | #include <linux/syscalls.h> | |
39 | #include <linux/jiffies.h> | |
40 | #include <linux/tracehook.h> | |
41 | #include <linux/futex.h> | |
42 | #include <linux/compat.h> | |
43 | #include <linux/task_io_accounting_ops.h> | |
44 | #include <linux/rcupdate.h> | |
45 | #include <linux/ptrace.h> | |
46 | #include <linux/mount.h> | |
47 | #include <linux/audit.h> | |
48 | #include <linux/memcontrol.h> | |
49 | #include <linux/ftrace.h> | |
50 | #include <linux/profile.h> | |
51 | #include <linux/rmap.h> | |
52 | #include <linux/ksm.h> | |
53 | #include <linux/acct.h> | |
54 | #include <linux/tsacct_kern.h> | |
55 | #include <linux/cn_proc.h> | |
56 | #include <linux/freezer.h> | |
57 | #include <linux/delayacct.h> | |
58 | #include <linux/taskstats_kern.h> | |
59 | #include <linux/random.h> | |
60 | #include <linux/tty.h> | |
61 | #include <linux/proc_fs.h> | |
62 | #include <linux/blkdev.h> | |
63 | #include <linux/fs_struct.h> | |
64 | #include <linux/magic.h> | |
65 | #include <linux/perf_event.h> | |
66 | #include <linux/posix-timers.h> | |
67 | #include <linux/user-return-notifier.h> | |
68 | ||
69 | #include <asm/pgtable.h> | |
70 | #include <asm/pgalloc.h> | |
71 | #include <asm/uaccess.h> | |
72 | #include <asm/mmu_context.h> | |
73 | #include <asm/cacheflush.h> | |
74 | #include <asm/tlbflush.h> | |
75 | ||
76 | #include <trace/events/sched.h> | |
77 | ||
78 | /* | |
79 | * Protected counters by write_lock_irq(&tasklist_lock) | |
80 | */ | |
81 | unsigned long total_forks; /* Handle normal Linux uptimes. */ | |
82 | int nr_threads; /* The idle threads do not count.. */ | |
83 | ||
84 | int max_threads; /* tunable limit on nr_threads */ | |
85 | ||
86 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; | |
87 | ||
88 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ | |
89 | ||
90 | #ifdef CONFIG_PROVE_RCU | |
91 | int lockdep_tasklist_lock_is_held(void) | |
92 | { | |
93 | return lockdep_is_held(&tasklist_lock); | |
94 | } | |
95 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); | |
96 | #endif /* #ifdef CONFIG_PROVE_RCU */ | |
97 | ||
98 | int nr_processes(void) | |
99 | { | |
100 | int cpu; | |
101 | int total = 0; | |
102 | ||
103 | for_each_possible_cpu(cpu) | |
104 | total += per_cpu(process_counts, cpu); | |
105 | ||
106 | return total; | |
107 | } | |
108 | ||
109 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
110 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) | |
111 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) | |
112 | static struct kmem_cache *task_struct_cachep; | |
113 | #endif | |
114 | ||
115 | #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR | |
116 | static inline struct thread_info *alloc_thread_info(struct task_struct *tsk) | |
117 | { | |
118 | #ifdef CONFIG_DEBUG_STACK_USAGE | |
119 | gfp_t mask = GFP_KERNEL | __GFP_ZERO; | |
120 | #else | |
121 | gfp_t mask = GFP_KERNEL; | |
122 | #endif | |
123 | return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER); | |
124 | } | |
125 | ||
126 | static inline void free_thread_info(struct thread_info *ti) | |
127 | { | |
128 | free_pages((unsigned long)ti, THREAD_SIZE_ORDER); | |
129 | } | |
130 | #endif | |
131 | ||
132 | /* SLAB cache for signal_struct structures (tsk->signal) */ | |
133 | static struct kmem_cache *signal_cachep; | |
134 | ||
135 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ | |
136 | struct kmem_cache *sighand_cachep; | |
137 | ||
138 | /* SLAB cache for files_struct structures (tsk->files) */ | |
139 | struct kmem_cache *files_cachep; | |
140 | ||
141 | /* SLAB cache for fs_struct structures (tsk->fs) */ | |
142 | struct kmem_cache *fs_cachep; | |
143 | ||
144 | /* SLAB cache for vm_area_struct structures */ | |
145 | struct kmem_cache *vm_area_cachep; | |
146 | ||
147 | /* SLAB cache for mm_struct structures (tsk->mm) */ | |
148 | static struct kmem_cache *mm_cachep; | |
149 | ||
150 | static void account_kernel_stack(struct thread_info *ti, int account) | |
151 | { | |
152 | struct zone *zone = page_zone(virt_to_page(ti)); | |
153 | ||
154 | mod_zone_page_state(zone, NR_KERNEL_STACK, account); | |
155 | } | |
156 | ||
157 | void free_task(struct task_struct *tsk) | |
158 | { | |
159 | prop_local_destroy_single(&tsk->dirties); | |
160 | account_kernel_stack(tsk->stack, -1); | |
161 | free_thread_info(tsk->stack); | |
162 | rt_mutex_debug_task_free(tsk); | |
163 | ftrace_graph_exit_task(tsk); | |
164 | free_task_struct(tsk); | |
165 | } | |
166 | EXPORT_SYMBOL(free_task); | |
167 | ||
168 | static inline void free_signal_struct(struct signal_struct *sig) | |
169 | { | |
170 | taskstats_tgid_free(sig); | |
171 | kmem_cache_free(signal_cachep, sig); | |
172 | } | |
173 | ||
174 | static inline void put_signal_struct(struct signal_struct *sig) | |
175 | { | |
176 | if (atomic_dec_and_test(&sig->sigcnt)) | |
177 | free_signal_struct(sig); | |
178 | } | |
179 | ||
180 | void __put_task_struct(struct task_struct *tsk) | |
181 | { | |
182 | WARN_ON(!tsk->exit_state); | |
183 | WARN_ON(atomic_read(&tsk->usage)); | |
184 | WARN_ON(tsk == current); | |
185 | ||
186 | exit_creds(tsk); | |
187 | delayacct_tsk_free(tsk); | |
188 | put_signal_struct(tsk->signal); | |
189 | ||
190 | if (!profile_handoff_task(tsk)) | |
191 | free_task(tsk); | |
192 | } | |
193 | ||
194 | /* | |
195 | * macro override instead of weak attribute alias, to workaround | |
196 | * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. | |
197 | */ | |
198 | #ifndef arch_task_cache_init | |
199 | #define arch_task_cache_init() | |
200 | #endif | |
201 | ||
202 | void __init fork_init(unsigned long mempages) | |
203 | { | |
204 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
205 | #ifndef ARCH_MIN_TASKALIGN | |
206 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES | |
207 | #endif | |
208 | /* create a slab on which task_structs can be allocated */ | |
209 | task_struct_cachep = | |
210 | kmem_cache_create("task_struct", sizeof(struct task_struct), | |
211 | ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); | |
212 | #endif | |
213 | ||
214 | /* do the arch specific task caches init */ | |
215 | arch_task_cache_init(); | |
216 | ||
217 | /* | |
218 | * The default maximum number of threads is set to a safe | |
219 | * value: the thread structures can take up at most half | |
220 | * of memory. | |
221 | */ | |
222 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); | |
223 | ||
224 | /* | |
225 | * we need to allow at least 20 threads to boot a system | |
226 | */ | |
227 | if(max_threads < 20) | |
228 | max_threads = 20; | |
229 | ||
230 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; | |
231 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; | |
232 | init_task.signal->rlim[RLIMIT_SIGPENDING] = | |
233 | init_task.signal->rlim[RLIMIT_NPROC]; | |
234 | } | |
235 | ||
236 | int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, | |
237 | struct task_struct *src) | |
238 | { | |
239 | *dst = *src; | |
240 | return 0; | |
241 | } | |
242 | ||
243 | static struct task_struct *dup_task_struct(struct task_struct *orig) | |
244 | { | |
245 | struct task_struct *tsk; | |
246 | struct thread_info *ti; | |
247 | unsigned long *stackend; | |
248 | ||
249 | int err; | |
250 | ||
251 | prepare_to_copy(orig); | |
252 | ||
253 | tsk = alloc_task_struct(); | |
254 | if (!tsk) | |
255 | return NULL; | |
256 | ||
257 | ti = alloc_thread_info(tsk); | |
258 | if (!ti) { | |
259 | free_task_struct(tsk); | |
260 | return NULL; | |
261 | } | |
262 | ||
263 | err = arch_dup_task_struct(tsk, orig); | |
264 | if (err) | |
265 | goto out; | |
266 | ||
267 | tsk->stack = ti; | |
268 | ||
269 | err = prop_local_init_single(&tsk->dirties); | |
270 | if (err) | |
271 | goto out; | |
272 | ||
273 | setup_thread_stack(tsk, orig); | |
274 | clear_user_return_notifier(tsk); | |
275 | stackend = end_of_stack(tsk); | |
276 | *stackend = STACK_END_MAGIC; /* for overflow detection */ | |
277 | ||
278 | #ifdef CONFIG_CC_STACKPROTECTOR | |
279 | tsk->stack_canary = get_random_int(); | |
280 | #endif | |
281 | ||
282 | /* One for us, one for whoever does the "release_task()" (usually parent) */ | |
283 | atomic_set(&tsk->usage,2); | |
284 | atomic_set(&tsk->fs_excl, 0); | |
285 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
286 | tsk->btrace_seq = 0; | |
287 | #endif | |
288 | tsk->splice_pipe = NULL; | |
289 | ||
290 | account_kernel_stack(ti, 1); | |
291 | ||
292 | return tsk; | |
293 | ||
294 | out: | |
295 | free_thread_info(ti); | |
296 | free_task_struct(tsk); | |
297 | return NULL; | |
298 | } | |
299 | ||
300 | #ifdef CONFIG_MMU | |
301 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) | |
302 | { | |
303 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; | |
304 | struct rb_node **rb_link, *rb_parent; | |
305 | int retval; | |
306 | unsigned long charge; | |
307 | struct mempolicy *pol; | |
308 | ||
309 | down_write(&oldmm->mmap_sem); | |
310 | flush_cache_dup_mm(oldmm); | |
311 | /* | |
312 | * Not linked in yet - no deadlock potential: | |
313 | */ | |
314 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); | |
315 | ||
316 | mm->locked_vm = 0; | |
317 | mm->mmap = NULL; | |
318 | mm->mmap_cache = NULL; | |
319 | mm->free_area_cache = oldmm->mmap_base; | |
320 | mm->cached_hole_size = ~0UL; | |
321 | mm->map_count = 0; | |
322 | cpumask_clear(mm_cpumask(mm)); | |
323 | mm->mm_rb = RB_ROOT; | |
324 | rb_link = &mm->mm_rb.rb_node; | |
325 | rb_parent = NULL; | |
326 | pprev = &mm->mmap; | |
327 | retval = ksm_fork(mm, oldmm); | |
328 | if (retval) | |
329 | goto out; | |
330 | ||
331 | prev = NULL; | |
332 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { | |
333 | struct file *file; | |
334 | ||
335 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
336 | long pages = vma_pages(mpnt); | |
337 | mm->total_vm -= pages; | |
338 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, | |
339 | -pages); | |
340 | continue; | |
341 | } | |
342 | charge = 0; | |
343 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
344 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; | |
345 | if (security_vm_enough_memory(len)) | |
346 | goto fail_nomem; | |
347 | charge = len; | |
348 | } | |
349 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
350 | if (!tmp) | |
351 | goto fail_nomem; | |
352 | *tmp = *mpnt; | |
353 | INIT_LIST_HEAD(&tmp->anon_vma_chain); | |
354 | pol = mpol_dup(vma_policy(mpnt)); | |
355 | retval = PTR_ERR(pol); | |
356 | if (IS_ERR(pol)) | |
357 | goto fail_nomem_policy; | |
358 | vma_set_policy(tmp, pol); | |
359 | if (anon_vma_fork(tmp, mpnt)) | |
360 | goto fail_nomem_anon_vma_fork; | |
361 | tmp->vm_flags &= ~VM_LOCKED; | |
362 | tmp->vm_mm = mm; | |
363 | tmp->vm_next = tmp->vm_prev = NULL; | |
364 | file = tmp->vm_file; | |
365 | if (file) { | |
366 | struct inode *inode = file->f_path.dentry->d_inode; | |
367 | struct address_space *mapping = file->f_mapping; | |
368 | ||
369 | get_file(file); | |
370 | if (tmp->vm_flags & VM_DENYWRITE) | |
371 | atomic_dec(&inode->i_writecount); | |
372 | spin_lock(&mapping->i_mmap_lock); | |
373 | if (tmp->vm_flags & VM_SHARED) | |
374 | mapping->i_mmap_writable++; | |
375 | tmp->vm_truncate_count = mpnt->vm_truncate_count; | |
376 | flush_dcache_mmap_lock(mapping); | |
377 | /* insert tmp into the share list, just after mpnt */ | |
378 | vma_prio_tree_add(tmp, mpnt); | |
379 | flush_dcache_mmap_unlock(mapping); | |
380 | spin_unlock(&mapping->i_mmap_lock); | |
381 | } | |
382 | ||
383 | /* | |
384 | * Clear hugetlb-related page reserves for children. This only | |
385 | * affects MAP_PRIVATE mappings. Faults generated by the child | |
386 | * are not guaranteed to succeed, even if read-only | |
387 | */ | |
388 | if (is_vm_hugetlb_page(tmp)) | |
389 | reset_vma_resv_huge_pages(tmp); | |
390 | ||
391 | /* | |
392 | * Link in the new vma and copy the page table entries. | |
393 | */ | |
394 | *pprev = tmp; | |
395 | pprev = &tmp->vm_next; | |
396 | tmp->vm_prev = prev; | |
397 | prev = tmp; | |
398 | ||
399 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
400 | rb_link = &tmp->vm_rb.rb_right; | |
401 | rb_parent = &tmp->vm_rb; | |
402 | ||
403 | mm->map_count++; | |
404 | retval = copy_page_range(mm, oldmm, mpnt); | |
405 | ||
406 | if (tmp->vm_ops && tmp->vm_ops->open) | |
407 | tmp->vm_ops->open(tmp); | |
408 | ||
409 | if (retval) | |
410 | goto out; | |
411 | } | |
412 | /* a new mm has just been created */ | |
413 | arch_dup_mmap(oldmm, mm); | |
414 | retval = 0; | |
415 | out: | |
416 | up_write(&mm->mmap_sem); | |
417 | flush_tlb_mm(oldmm); | |
418 | up_write(&oldmm->mmap_sem); | |
419 | return retval; | |
420 | fail_nomem_anon_vma_fork: | |
421 | mpol_put(pol); | |
422 | fail_nomem_policy: | |
423 | kmem_cache_free(vm_area_cachep, tmp); | |
424 | fail_nomem: | |
425 | retval = -ENOMEM; | |
426 | vm_unacct_memory(charge); | |
427 | goto out; | |
428 | } | |
429 | ||
430 | static inline int mm_alloc_pgd(struct mm_struct * mm) | |
431 | { | |
432 | mm->pgd = pgd_alloc(mm); | |
433 | if (unlikely(!mm->pgd)) | |
434 | return -ENOMEM; | |
435 | return 0; | |
436 | } | |
437 | ||
438 | static inline void mm_free_pgd(struct mm_struct * mm) | |
439 | { | |
440 | pgd_free(mm, mm->pgd); | |
441 | } | |
442 | #else | |
443 | #define dup_mmap(mm, oldmm) (0) | |
444 | #define mm_alloc_pgd(mm) (0) | |
445 | #define mm_free_pgd(mm) | |
446 | #endif /* CONFIG_MMU */ | |
447 | ||
448 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
449 | ||
450 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) | |
451 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
452 | ||
453 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; | |
454 | ||
455 | static int __init coredump_filter_setup(char *s) | |
456 | { | |
457 | default_dump_filter = | |
458 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & | |
459 | MMF_DUMP_FILTER_MASK; | |
460 | return 1; | |
461 | } | |
462 | ||
463 | __setup("coredump_filter=", coredump_filter_setup); | |
464 | ||
465 | #include <linux/init_task.h> | |
466 | ||
467 | static void mm_init_aio(struct mm_struct *mm) | |
468 | { | |
469 | #ifdef CONFIG_AIO | |
470 | spin_lock_init(&mm->ioctx_lock); | |
471 | INIT_HLIST_HEAD(&mm->ioctx_list); | |
472 | #endif | |
473 | } | |
474 | ||
475 | static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) | |
476 | { | |
477 | atomic_set(&mm->mm_users, 1); | |
478 | atomic_set(&mm->mm_count, 1); | |
479 | init_rwsem(&mm->mmap_sem); | |
480 | INIT_LIST_HEAD(&mm->mmlist); | |
481 | mm->flags = (current->mm) ? | |
482 | (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; | |
483 | mm->core_state = NULL; | |
484 | mm->nr_ptes = 0; | |
485 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); | |
486 | spin_lock_init(&mm->page_table_lock); | |
487 | mm->free_area_cache = TASK_UNMAPPED_BASE; | |
488 | mm->cached_hole_size = ~0UL; | |
489 | mm_init_aio(mm); | |
490 | mm_init_owner(mm, p); | |
491 | ||
492 | if (likely(!mm_alloc_pgd(mm))) { | |
493 | mm->def_flags = 0; | |
494 | mmu_notifier_mm_init(mm); | |
495 | return mm; | |
496 | } | |
497 | ||
498 | free_mm(mm); | |
499 | return NULL; | |
500 | } | |
501 | ||
502 | /* | |
503 | * Allocate and initialize an mm_struct. | |
504 | */ | |
505 | struct mm_struct * mm_alloc(void) | |
506 | { | |
507 | struct mm_struct * mm; | |
508 | ||
509 | mm = allocate_mm(); | |
510 | if (mm) { | |
511 | memset(mm, 0, sizeof(*mm)); | |
512 | mm = mm_init(mm, current); | |
513 | } | |
514 | return mm; | |
515 | } | |
516 | ||
517 | /* | |
518 | * Called when the last reference to the mm | |
519 | * is dropped: either by a lazy thread or by | |
520 | * mmput. Free the page directory and the mm. | |
521 | */ | |
522 | void __mmdrop(struct mm_struct *mm) | |
523 | { | |
524 | BUG_ON(mm == &init_mm); | |
525 | mm_free_pgd(mm); | |
526 | destroy_context(mm); | |
527 | mmu_notifier_mm_destroy(mm); | |
528 | free_mm(mm); | |
529 | } | |
530 | EXPORT_SYMBOL_GPL(__mmdrop); | |
531 | ||
532 | /* | |
533 | * Decrement the use count and release all resources for an mm. | |
534 | */ | |
535 | void mmput(struct mm_struct *mm) | |
536 | { | |
537 | might_sleep(); | |
538 | ||
539 | if (atomic_dec_and_test(&mm->mm_users)) { | |
540 | exit_aio(mm); | |
541 | ksm_exit(mm); | |
542 | exit_mmap(mm); | |
543 | set_mm_exe_file(mm, NULL); | |
544 | if (!list_empty(&mm->mmlist)) { | |
545 | spin_lock(&mmlist_lock); | |
546 | list_del(&mm->mmlist); | |
547 | spin_unlock(&mmlist_lock); | |
548 | } | |
549 | put_swap_token(mm); | |
550 | if (mm->binfmt) | |
551 | module_put(mm->binfmt->module); | |
552 | mmdrop(mm); | |
553 | } | |
554 | } | |
555 | EXPORT_SYMBOL_GPL(mmput); | |
556 | ||
557 | /** | |
558 | * get_task_mm - acquire a reference to the task's mm | |
559 | * | |
560 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning | |
561 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
562 | * to do its AIO) is not set and if so returns a reference to it, after | |
563 | * bumping up the use count. User must release the mm via mmput() | |
564 | * after use. Typically used by /proc and ptrace. | |
565 | */ | |
566 | struct mm_struct *get_task_mm(struct task_struct *task) | |
567 | { | |
568 | struct mm_struct *mm; | |
569 | ||
570 | task_lock(task); | |
571 | mm = task->mm; | |
572 | if (mm) { | |
573 | if (task->flags & PF_KTHREAD) | |
574 | mm = NULL; | |
575 | else | |
576 | atomic_inc(&mm->mm_users); | |
577 | } | |
578 | task_unlock(task); | |
579 | return mm; | |
580 | } | |
581 | EXPORT_SYMBOL_GPL(get_task_mm); | |
582 | ||
583 | /* Please note the differences between mmput and mm_release. | |
584 | * mmput is called whenever we stop holding onto a mm_struct, | |
585 | * error success whatever. | |
586 | * | |
587 | * mm_release is called after a mm_struct has been removed | |
588 | * from the current process. | |
589 | * | |
590 | * This difference is important for error handling, when we | |
591 | * only half set up a mm_struct for a new process and need to restore | |
592 | * the old one. Because we mmput the new mm_struct before | |
593 | * restoring the old one. . . | |
594 | * Eric Biederman 10 January 1998 | |
595 | */ | |
596 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
597 | { | |
598 | struct completion *vfork_done = tsk->vfork_done; | |
599 | ||
600 | /* Get rid of any futexes when releasing the mm */ | |
601 | #ifdef CONFIG_FUTEX | |
602 | if (unlikely(tsk->robust_list)) { | |
603 | exit_robust_list(tsk); | |
604 | tsk->robust_list = NULL; | |
605 | } | |
606 | #ifdef CONFIG_COMPAT | |
607 | if (unlikely(tsk->compat_robust_list)) { | |
608 | compat_exit_robust_list(tsk); | |
609 | tsk->compat_robust_list = NULL; | |
610 | } | |
611 | #endif | |
612 | if (unlikely(!list_empty(&tsk->pi_state_list))) | |
613 | exit_pi_state_list(tsk); | |
614 | #endif | |
615 | ||
616 | /* Get rid of any cached register state */ | |
617 | deactivate_mm(tsk, mm); | |
618 | ||
619 | /* notify parent sleeping on vfork() */ | |
620 | if (vfork_done) { | |
621 | tsk->vfork_done = NULL; | |
622 | complete(vfork_done); | |
623 | } | |
624 | ||
625 | /* | |
626 | * If we're exiting normally, clear a user-space tid field if | |
627 | * requested. We leave this alone when dying by signal, to leave | |
628 | * the value intact in a core dump, and to save the unnecessary | |
629 | * trouble otherwise. Userland only wants this done for a sys_exit. | |
630 | */ | |
631 | if (tsk->clear_child_tid) { | |
632 | if (!(tsk->flags & PF_SIGNALED) && | |
633 | atomic_read(&mm->mm_users) > 1) { | |
634 | /* | |
635 | * We don't check the error code - if userspace has | |
636 | * not set up a proper pointer then tough luck. | |
637 | */ | |
638 | put_user(0, tsk->clear_child_tid); | |
639 | sys_futex(tsk->clear_child_tid, FUTEX_WAKE, | |
640 | 1, NULL, NULL, 0); | |
641 | } | |
642 | tsk->clear_child_tid = NULL; | |
643 | } | |
644 | } | |
645 | ||
646 | /* | |
647 | * Allocate a new mm structure and copy contents from the | |
648 | * mm structure of the passed in task structure. | |
649 | */ | |
650 | struct mm_struct *dup_mm(struct task_struct *tsk) | |
651 | { | |
652 | struct mm_struct *mm, *oldmm = current->mm; | |
653 | int err; | |
654 | ||
655 | if (!oldmm) | |
656 | return NULL; | |
657 | ||
658 | mm = allocate_mm(); | |
659 | if (!mm) | |
660 | goto fail_nomem; | |
661 | ||
662 | memcpy(mm, oldmm, sizeof(*mm)); | |
663 | ||
664 | /* Initializing for Swap token stuff */ | |
665 | mm->token_priority = 0; | |
666 | mm->last_interval = 0; | |
667 | ||
668 | if (!mm_init(mm, tsk)) | |
669 | goto fail_nomem; | |
670 | ||
671 | if (init_new_context(tsk, mm)) | |
672 | goto fail_nocontext; | |
673 | ||
674 | dup_mm_exe_file(oldmm, mm); | |
675 | ||
676 | err = dup_mmap(mm, oldmm); | |
677 | if (err) | |
678 | goto free_pt; | |
679 | ||
680 | mm->hiwater_rss = get_mm_rss(mm); | |
681 | mm->hiwater_vm = mm->total_vm; | |
682 | ||
683 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) | |
684 | goto free_pt; | |
685 | ||
686 | return mm; | |
687 | ||
688 | free_pt: | |
689 | /* don't put binfmt in mmput, we haven't got module yet */ | |
690 | mm->binfmt = NULL; | |
691 | mmput(mm); | |
692 | ||
693 | fail_nomem: | |
694 | return NULL; | |
695 | ||
696 | fail_nocontext: | |
697 | /* | |
698 | * If init_new_context() failed, we cannot use mmput() to free the mm | |
699 | * because it calls destroy_context() | |
700 | */ | |
701 | mm_free_pgd(mm); | |
702 | free_mm(mm); | |
703 | return NULL; | |
704 | } | |
705 | ||
706 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) | |
707 | { | |
708 | struct mm_struct * mm, *oldmm; | |
709 | int retval; | |
710 | ||
711 | tsk->min_flt = tsk->maj_flt = 0; | |
712 | tsk->nvcsw = tsk->nivcsw = 0; | |
713 | #ifdef CONFIG_DETECT_HUNG_TASK | |
714 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; | |
715 | #endif | |
716 | ||
717 | tsk->mm = NULL; | |
718 | tsk->active_mm = NULL; | |
719 | ||
720 | /* | |
721 | * Are we cloning a kernel thread? | |
722 | * | |
723 | * We need to steal a active VM for that.. | |
724 | */ | |
725 | oldmm = current->mm; | |
726 | if (!oldmm) | |
727 | return 0; | |
728 | ||
729 | if (clone_flags & CLONE_VM) { | |
730 | atomic_inc(&oldmm->mm_users); | |
731 | mm = oldmm; | |
732 | goto good_mm; | |
733 | } | |
734 | ||
735 | retval = -ENOMEM; | |
736 | mm = dup_mm(tsk); | |
737 | if (!mm) | |
738 | goto fail_nomem; | |
739 | ||
740 | good_mm: | |
741 | /* Initializing for Swap token stuff */ | |
742 | mm->token_priority = 0; | |
743 | mm->last_interval = 0; | |
744 | ||
745 | tsk->mm = mm; | |
746 | tsk->active_mm = mm; | |
747 | return 0; | |
748 | ||
749 | fail_nomem: | |
750 | return retval; | |
751 | } | |
752 | ||
753 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) | |
754 | { | |
755 | struct fs_struct *fs = current->fs; | |
756 | if (clone_flags & CLONE_FS) { | |
757 | /* tsk->fs is already what we want */ | |
758 | spin_lock(&fs->lock); | |
759 | if (fs->in_exec) { | |
760 | spin_unlock(&fs->lock); | |
761 | return -EAGAIN; | |
762 | } | |
763 | fs->users++; | |
764 | spin_unlock(&fs->lock); | |
765 | return 0; | |
766 | } | |
767 | tsk->fs = copy_fs_struct(fs); | |
768 | if (!tsk->fs) | |
769 | return -ENOMEM; | |
770 | return 0; | |
771 | } | |
772 | ||
773 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) | |
774 | { | |
775 | struct files_struct *oldf, *newf; | |
776 | int error = 0; | |
777 | ||
778 | /* | |
779 | * A background process may not have any files ... | |
780 | */ | |
781 | oldf = current->files; | |
782 | if (!oldf) | |
783 | goto out; | |
784 | ||
785 | if (clone_flags & CLONE_FILES) { | |
786 | atomic_inc(&oldf->count); | |
787 | goto out; | |
788 | } | |
789 | ||
790 | newf = dup_fd(oldf, &error); | |
791 | if (!newf) | |
792 | goto out; | |
793 | ||
794 | tsk->files = newf; | |
795 | error = 0; | |
796 | out: | |
797 | return error; | |
798 | } | |
799 | ||
800 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) | |
801 | { | |
802 | #ifdef CONFIG_BLOCK | |
803 | struct io_context *ioc = current->io_context; | |
804 | ||
805 | if (!ioc) | |
806 | return 0; | |
807 | /* | |
808 | * Share io context with parent, if CLONE_IO is set | |
809 | */ | |
810 | if (clone_flags & CLONE_IO) { | |
811 | tsk->io_context = ioc_task_link(ioc); | |
812 | if (unlikely(!tsk->io_context)) | |
813 | return -ENOMEM; | |
814 | } else if (ioprio_valid(ioc->ioprio)) { | |
815 | tsk->io_context = alloc_io_context(GFP_KERNEL, -1); | |
816 | if (unlikely(!tsk->io_context)) | |
817 | return -ENOMEM; | |
818 | ||
819 | tsk->io_context->ioprio = ioc->ioprio; | |
820 | } | |
821 | #endif | |
822 | return 0; | |
823 | } | |
824 | ||
825 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) | |
826 | { | |
827 | struct sighand_struct *sig; | |
828 | ||
829 | if (clone_flags & CLONE_SIGHAND) { | |
830 | atomic_inc(¤t->sighand->count); | |
831 | return 0; | |
832 | } | |
833 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
834 | rcu_assign_pointer(tsk->sighand, sig); | |
835 | if (!sig) | |
836 | return -ENOMEM; | |
837 | atomic_set(&sig->count, 1); | |
838 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
839 | return 0; | |
840 | } | |
841 | ||
842 | void __cleanup_sighand(struct sighand_struct *sighand) | |
843 | { | |
844 | if (atomic_dec_and_test(&sighand->count)) | |
845 | kmem_cache_free(sighand_cachep, sighand); | |
846 | } | |
847 | ||
848 | ||
849 | /* | |
850 | * Initialize POSIX timer handling for a thread group. | |
851 | */ | |
852 | static void posix_cpu_timers_init_group(struct signal_struct *sig) | |
853 | { | |
854 | unsigned long cpu_limit; | |
855 | ||
856 | /* Thread group counters. */ | |
857 | thread_group_cputime_init(sig); | |
858 | ||
859 | cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); | |
860 | if (cpu_limit != RLIM_INFINITY) { | |
861 | sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); | |
862 | sig->cputimer.running = 1; | |
863 | } | |
864 | ||
865 | /* The timer lists. */ | |
866 | INIT_LIST_HEAD(&sig->cpu_timers[0]); | |
867 | INIT_LIST_HEAD(&sig->cpu_timers[1]); | |
868 | INIT_LIST_HEAD(&sig->cpu_timers[2]); | |
869 | } | |
870 | ||
871 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) | |
872 | { | |
873 | struct signal_struct *sig; | |
874 | ||
875 | if (clone_flags & CLONE_THREAD) | |
876 | return 0; | |
877 | ||
878 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); | |
879 | tsk->signal = sig; | |
880 | if (!sig) | |
881 | return -ENOMEM; | |
882 | ||
883 | sig->nr_threads = 1; | |
884 | atomic_set(&sig->live, 1); | |
885 | atomic_set(&sig->sigcnt, 1); | |
886 | init_waitqueue_head(&sig->wait_chldexit); | |
887 | if (clone_flags & CLONE_NEWPID) | |
888 | sig->flags |= SIGNAL_UNKILLABLE; | |
889 | sig->curr_target = tsk; | |
890 | init_sigpending(&sig->shared_pending); | |
891 | INIT_LIST_HEAD(&sig->posix_timers); | |
892 | ||
893 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
894 | sig->real_timer.function = it_real_fn; | |
895 | ||
896 | task_lock(current->group_leader); | |
897 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
898 | task_unlock(current->group_leader); | |
899 | ||
900 | posix_cpu_timers_init_group(sig); | |
901 | ||
902 | tty_audit_fork(sig); | |
903 | ||
904 | sig->oom_adj = current->signal->oom_adj; | |
905 | sig->oom_score_adj = current->signal->oom_score_adj; | |
906 | ||
907 | return 0; | |
908 | } | |
909 | ||
910 | static void copy_flags(unsigned long clone_flags, struct task_struct *p) | |
911 | { | |
912 | unsigned long new_flags = p->flags; | |
913 | ||
914 | new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); | |
915 | new_flags |= PF_FORKNOEXEC; | |
916 | new_flags |= PF_STARTING; | |
917 | p->flags = new_flags; | |
918 | clear_freeze_flag(p); | |
919 | } | |
920 | ||
921 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) | |
922 | { | |
923 | current->clear_child_tid = tidptr; | |
924 | ||
925 | return task_pid_vnr(current); | |
926 | } | |
927 | ||
928 | static void rt_mutex_init_task(struct task_struct *p) | |
929 | { | |
930 | raw_spin_lock_init(&p->pi_lock); | |
931 | #ifdef CONFIG_RT_MUTEXES | |
932 | plist_head_init_raw(&p->pi_waiters, &p->pi_lock); | |
933 | p->pi_blocked_on = NULL; | |
934 | #endif | |
935 | } | |
936 | ||
937 | #ifdef CONFIG_MM_OWNER | |
938 | void mm_init_owner(struct mm_struct *mm, struct task_struct *p) | |
939 | { | |
940 | mm->owner = p; | |
941 | } | |
942 | #endif /* CONFIG_MM_OWNER */ | |
943 | ||
944 | /* | |
945 | * Initialize POSIX timer handling for a single task. | |
946 | */ | |
947 | static void posix_cpu_timers_init(struct task_struct *tsk) | |
948 | { | |
949 | tsk->cputime_expires.prof_exp = cputime_zero; | |
950 | tsk->cputime_expires.virt_exp = cputime_zero; | |
951 | tsk->cputime_expires.sched_exp = 0; | |
952 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); | |
953 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); | |
954 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); | |
955 | } | |
956 | ||
957 | /* | |
958 | * This creates a new process as a copy of the old one, | |
959 | * but does not actually start it yet. | |
960 | * | |
961 | * It copies the registers, and all the appropriate | |
962 | * parts of the process environment (as per the clone | |
963 | * flags). The actual kick-off is left to the caller. | |
964 | */ | |
965 | static struct task_struct *copy_process(unsigned long clone_flags, | |
966 | unsigned long stack_start, | |
967 | struct pt_regs *regs, | |
968 | unsigned long stack_size, | |
969 | int __user *child_tidptr, | |
970 | struct pid *pid, | |
971 | int trace) | |
972 | { | |
973 | int retval; | |
974 | struct task_struct *p; | |
975 | int cgroup_callbacks_done = 0; | |
976 | ||
977 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
978 | return ERR_PTR(-EINVAL); | |
979 | ||
980 | /* | |
981 | * Thread groups must share signals as well, and detached threads | |
982 | * can only be started up within the thread group. | |
983 | */ | |
984 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
985 | return ERR_PTR(-EINVAL); | |
986 | ||
987 | /* | |
988 | * Shared signal handlers imply shared VM. By way of the above, | |
989 | * thread groups also imply shared VM. Blocking this case allows | |
990 | * for various simplifications in other code. | |
991 | */ | |
992 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
993 | return ERR_PTR(-EINVAL); | |
994 | ||
995 | /* | |
996 | * Siblings of global init remain as zombies on exit since they are | |
997 | * not reaped by their parent (swapper). To solve this and to avoid | |
998 | * multi-rooted process trees, prevent global and container-inits | |
999 | * from creating siblings. | |
1000 | */ | |
1001 | if ((clone_flags & CLONE_PARENT) && | |
1002 | current->signal->flags & SIGNAL_UNKILLABLE) | |
1003 | return ERR_PTR(-EINVAL); | |
1004 | ||
1005 | retval = security_task_create(clone_flags); | |
1006 | if (retval) | |
1007 | goto fork_out; | |
1008 | ||
1009 | retval = -ENOMEM; | |
1010 | p = dup_task_struct(current); | |
1011 | if (!p) | |
1012 | goto fork_out; | |
1013 | ||
1014 | ftrace_graph_init_task(p); | |
1015 | ||
1016 | rt_mutex_init_task(p); | |
1017 | ||
1018 | #ifdef CONFIG_PROVE_LOCKING | |
1019 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); | |
1020 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); | |
1021 | #endif | |
1022 | retval = -EAGAIN; | |
1023 | if (atomic_read(&p->real_cred->user->processes) >= | |
1024 | task_rlimit(p, RLIMIT_NPROC)) { | |
1025 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && | |
1026 | p->real_cred->user != INIT_USER) | |
1027 | goto bad_fork_free; | |
1028 | } | |
1029 | ||
1030 | retval = copy_creds(p, clone_flags); | |
1031 | if (retval < 0) | |
1032 | goto bad_fork_free; | |
1033 | ||
1034 | /* | |
1035 | * If multiple threads are within copy_process(), then this check | |
1036 | * triggers too late. This doesn't hurt, the check is only there | |
1037 | * to stop root fork bombs. | |
1038 | */ | |
1039 | retval = -EAGAIN; | |
1040 | if (nr_threads >= max_threads) | |
1041 | goto bad_fork_cleanup_count; | |
1042 | ||
1043 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) | |
1044 | goto bad_fork_cleanup_count; | |
1045 | ||
1046 | p->did_exec = 0; | |
1047 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ | |
1048 | copy_flags(clone_flags, p); | |
1049 | INIT_LIST_HEAD(&p->children); | |
1050 | INIT_LIST_HEAD(&p->sibling); | |
1051 | rcu_copy_process(p); | |
1052 | p->vfork_done = NULL; | |
1053 | spin_lock_init(&p->alloc_lock); | |
1054 | ||
1055 | init_sigpending(&p->pending); | |
1056 | ||
1057 | p->utime = cputime_zero; | |
1058 | p->stime = cputime_zero; | |
1059 | p->gtime = cputime_zero; | |
1060 | p->utimescaled = cputime_zero; | |
1061 | p->stimescaled = cputime_zero; | |
1062 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING | |
1063 | p->prev_utime = cputime_zero; | |
1064 | p->prev_stime = cputime_zero; | |
1065 | #endif | |
1066 | #if defined(SPLIT_RSS_COUNTING) | |
1067 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); | |
1068 | #endif | |
1069 | ||
1070 | p->default_timer_slack_ns = current->timer_slack_ns; | |
1071 | ||
1072 | task_io_accounting_init(&p->ioac); | |
1073 | acct_clear_integrals(p); | |
1074 | ||
1075 | posix_cpu_timers_init(p); | |
1076 | ||
1077 | p->lock_depth = -1; /* -1 = no lock */ | |
1078 | do_posix_clock_monotonic_gettime(&p->start_time); | |
1079 | p->real_start_time = p->start_time; | |
1080 | monotonic_to_bootbased(&p->real_start_time); | |
1081 | p->io_context = NULL; | |
1082 | p->audit_context = NULL; | |
1083 | cgroup_fork(p); | |
1084 | #ifdef CONFIG_NUMA | |
1085 | p->mempolicy = mpol_dup(p->mempolicy); | |
1086 | if (IS_ERR(p->mempolicy)) { | |
1087 | retval = PTR_ERR(p->mempolicy); | |
1088 | p->mempolicy = NULL; | |
1089 | goto bad_fork_cleanup_cgroup; | |
1090 | } | |
1091 | mpol_fix_fork_child_flag(p); | |
1092 | #endif | |
1093 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1094 | p->irq_events = 0; | |
1095 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW | |
1096 | p->hardirqs_enabled = 1; | |
1097 | #else | |
1098 | p->hardirqs_enabled = 0; | |
1099 | #endif | |
1100 | p->hardirq_enable_ip = 0; | |
1101 | p->hardirq_enable_event = 0; | |
1102 | p->hardirq_disable_ip = _THIS_IP_; | |
1103 | p->hardirq_disable_event = 0; | |
1104 | p->softirqs_enabled = 1; | |
1105 | p->softirq_enable_ip = _THIS_IP_; | |
1106 | p->softirq_enable_event = 0; | |
1107 | p->softirq_disable_ip = 0; | |
1108 | p->softirq_disable_event = 0; | |
1109 | p->hardirq_context = 0; | |
1110 | p->softirq_context = 0; | |
1111 | #endif | |
1112 | #ifdef CONFIG_LOCKDEP | |
1113 | p->lockdep_depth = 0; /* no locks held yet */ | |
1114 | p->curr_chain_key = 0; | |
1115 | p->lockdep_recursion = 0; | |
1116 | #endif | |
1117 | ||
1118 | #ifdef CONFIG_DEBUG_MUTEXES | |
1119 | p->blocked_on = NULL; /* not blocked yet */ | |
1120 | #endif | |
1121 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR | |
1122 | p->memcg_batch.do_batch = 0; | |
1123 | p->memcg_batch.memcg = NULL; | |
1124 | #endif | |
1125 | ||
1126 | /* Perform scheduler related setup. Assign this task to a CPU. */ | |
1127 | sched_fork(p, clone_flags); | |
1128 | ||
1129 | retval = perf_event_init_task(p); | |
1130 | if (retval) | |
1131 | goto bad_fork_cleanup_policy; | |
1132 | ||
1133 | if ((retval = audit_alloc(p))) | |
1134 | goto bad_fork_cleanup_policy; | |
1135 | /* copy all the process information */ | |
1136 | if ((retval = copy_semundo(clone_flags, p))) | |
1137 | goto bad_fork_cleanup_audit; | |
1138 | if ((retval = copy_files(clone_flags, p))) | |
1139 | goto bad_fork_cleanup_semundo; | |
1140 | if ((retval = copy_fs(clone_flags, p))) | |
1141 | goto bad_fork_cleanup_files; | |
1142 | if ((retval = copy_sighand(clone_flags, p))) | |
1143 | goto bad_fork_cleanup_fs; | |
1144 | if ((retval = copy_signal(clone_flags, p))) | |
1145 | goto bad_fork_cleanup_sighand; | |
1146 | if ((retval = copy_mm(clone_flags, p))) | |
1147 | goto bad_fork_cleanup_signal; | |
1148 | if ((retval = copy_namespaces(clone_flags, p))) | |
1149 | goto bad_fork_cleanup_mm; | |
1150 | if ((retval = copy_io(clone_flags, p))) | |
1151 | goto bad_fork_cleanup_namespaces; | |
1152 | retval = copy_thread(clone_flags, stack_start, stack_size, p, regs); | |
1153 | if (retval) | |
1154 | goto bad_fork_cleanup_io; | |
1155 | ||
1156 | if (pid != &init_struct_pid) { | |
1157 | retval = -ENOMEM; | |
1158 | pid = alloc_pid(p->nsproxy->pid_ns); | |
1159 | if (!pid) | |
1160 | goto bad_fork_cleanup_io; | |
1161 | ||
1162 | if (clone_flags & CLONE_NEWPID) { | |
1163 | retval = pid_ns_prepare_proc(p->nsproxy->pid_ns); | |
1164 | if (retval < 0) | |
1165 | goto bad_fork_free_pid; | |
1166 | } | |
1167 | } | |
1168 | ||
1169 | p->pid = pid_nr(pid); | |
1170 | p->tgid = p->pid; | |
1171 | if (clone_flags & CLONE_THREAD) | |
1172 | p->tgid = current->tgid; | |
1173 | ||
1174 | if (current->nsproxy != p->nsproxy) { | |
1175 | retval = ns_cgroup_clone(p, pid); | |
1176 | if (retval) | |
1177 | goto bad_fork_free_pid; | |
1178 | } | |
1179 | ||
1180 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; | |
1181 | /* | |
1182 | * Clear TID on mm_release()? | |
1183 | */ | |
1184 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; | |
1185 | #ifdef CONFIG_FUTEX | |
1186 | p->robust_list = NULL; | |
1187 | #ifdef CONFIG_COMPAT | |
1188 | p->compat_robust_list = NULL; | |
1189 | #endif | |
1190 | INIT_LIST_HEAD(&p->pi_state_list); | |
1191 | p->pi_state_cache = NULL; | |
1192 | #endif | |
1193 | /* | |
1194 | * sigaltstack should be cleared when sharing the same VM | |
1195 | */ | |
1196 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) | |
1197 | p->sas_ss_sp = p->sas_ss_size = 0; | |
1198 | ||
1199 | /* | |
1200 | * Syscall tracing and stepping should be turned off in the | |
1201 | * child regardless of CLONE_PTRACE. | |
1202 | */ | |
1203 | user_disable_single_step(p); | |
1204 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); | |
1205 | #ifdef TIF_SYSCALL_EMU | |
1206 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); | |
1207 | #endif | |
1208 | clear_all_latency_tracing(p); | |
1209 | ||
1210 | /* ok, now we should be set up.. */ | |
1211 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); | |
1212 | p->pdeath_signal = 0; | |
1213 | p->exit_state = 0; | |
1214 | ||
1215 | /* | |
1216 | * Ok, make it visible to the rest of the system. | |
1217 | * We dont wake it up yet. | |
1218 | */ | |
1219 | p->group_leader = p; | |
1220 | INIT_LIST_HEAD(&p->thread_group); | |
1221 | ||
1222 | /* Now that the task is set up, run cgroup callbacks if | |
1223 | * necessary. We need to run them before the task is visible | |
1224 | * on the tasklist. */ | |
1225 | cgroup_fork_callbacks(p); | |
1226 | cgroup_callbacks_done = 1; | |
1227 | ||
1228 | /* Need tasklist lock for parent etc handling! */ | |
1229 | write_lock_irq(&tasklist_lock); | |
1230 | ||
1231 | /* CLONE_PARENT re-uses the old parent */ | |
1232 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { | |
1233 | p->real_parent = current->real_parent; | |
1234 | p->parent_exec_id = current->parent_exec_id; | |
1235 | } else { | |
1236 | p->real_parent = current; | |
1237 | p->parent_exec_id = current->self_exec_id; | |
1238 | } | |
1239 | ||
1240 | spin_lock(¤t->sighand->siglock); | |
1241 | ||
1242 | /* | |
1243 | * Process group and session signals need to be delivered to just the | |
1244 | * parent before the fork or both the parent and the child after the | |
1245 | * fork. Restart if a signal comes in before we add the new process to | |
1246 | * it's process group. | |
1247 | * A fatal signal pending means that current will exit, so the new | |
1248 | * thread can't slip out of an OOM kill (or normal SIGKILL). | |
1249 | */ | |
1250 | recalc_sigpending(); | |
1251 | if (signal_pending(current)) { | |
1252 | spin_unlock(¤t->sighand->siglock); | |
1253 | write_unlock_irq(&tasklist_lock); | |
1254 | retval = -ERESTARTNOINTR; | |
1255 | goto bad_fork_free_pid; | |
1256 | } | |
1257 | ||
1258 | if (clone_flags & CLONE_THREAD) { | |
1259 | current->signal->nr_threads++; | |
1260 | atomic_inc(¤t->signal->live); | |
1261 | atomic_inc(¤t->signal->sigcnt); | |
1262 | p->group_leader = current->group_leader; | |
1263 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); | |
1264 | } | |
1265 | ||
1266 | if (likely(p->pid)) { | |
1267 | tracehook_finish_clone(p, clone_flags, trace); | |
1268 | ||
1269 | if (thread_group_leader(p)) { | |
1270 | if (clone_flags & CLONE_NEWPID) | |
1271 | p->nsproxy->pid_ns->child_reaper = p; | |
1272 | ||
1273 | p->signal->leader_pid = pid; | |
1274 | p->signal->tty = tty_kref_get(current->signal->tty); | |
1275 | attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); | |
1276 | attach_pid(p, PIDTYPE_SID, task_session(current)); | |
1277 | list_add_tail(&p->sibling, &p->real_parent->children); | |
1278 | list_add_tail_rcu(&p->tasks, &init_task.tasks); | |
1279 | __get_cpu_var(process_counts)++; | |
1280 | } | |
1281 | attach_pid(p, PIDTYPE_PID, pid); | |
1282 | nr_threads++; | |
1283 | } | |
1284 | ||
1285 | total_forks++; | |
1286 | spin_unlock(¤t->sighand->siglock); | |
1287 | write_unlock_irq(&tasklist_lock); | |
1288 | proc_fork_connector(p); | |
1289 | cgroup_post_fork(p); | |
1290 | perf_event_fork(p); | |
1291 | return p; | |
1292 | ||
1293 | bad_fork_free_pid: | |
1294 | if (pid != &init_struct_pid) | |
1295 | free_pid(pid); | |
1296 | bad_fork_cleanup_io: | |
1297 | if (p->io_context) | |
1298 | exit_io_context(p); | |
1299 | bad_fork_cleanup_namespaces: | |
1300 | exit_task_namespaces(p); | |
1301 | bad_fork_cleanup_mm: | |
1302 | if (p->mm) | |
1303 | mmput(p->mm); | |
1304 | bad_fork_cleanup_signal: | |
1305 | if (!(clone_flags & CLONE_THREAD)) | |
1306 | free_signal_struct(p->signal); | |
1307 | bad_fork_cleanup_sighand: | |
1308 | __cleanup_sighand(p->sighand); | |
1309 | bad_fork_cleanup_fs: | |
1310 | exit_fs(p); /* blocking */ | |
1311 | bad_fork_cleanup_files: | |
1312 | exit_files(p); /* blocking */ | |
1313 | bad_fork_cleanup_semundo: | |
1314 | exit_sem(p); | |
1315 | bad_fork_cleanup_audit: | |
1316 | audit_free(p); | |
1317 | bad_fork_cleanup_policy: | |
1318 | perf_event_free_task(p); | |
1319 | #ifdef CONFIG_NUMA | |
1320 | mpol_put(p->mempolicy); | |
1321 | bad_fork_cleanup_cgroup: | |
1322 | #endif | |
1323 | cgroup_exit(p, cgroup_callbacks_done); | |
1324 | delayacct_tsk_free(p); | |
1325 | module_put(task_thread_info(p)->exec_domain->module); | |
1326 | bad_fork_cleanup_count: | |
1327 | atomic_dec(&p->cred->user->processes); | |
1328 | exit_creds(p); | |
1329 | bad_fork_free: | |
1330 | free_task(p); | |
1331 | fork_out: | |
1332 | return ERR_PTR(retval); | |
1333 | } | |
1334 | ||
1335 | noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) | |
1336 | { | |
1337 | memset(regs, 0, sizeof(struct pt_regs)); | |
1338 | return regs; | |
1339 | } | |
1340 | ||
1341 | static inline void init_idle_pids(struct pid_link *links) | |
1342 | { | |
1343 | enum pid_type type; | |
1344 | ||
1345 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { | |
1346 | INIT_HLIST_NODE(&links[type].node); /* not really needed */ | |
1347 | links[type].pid = &init_struct_pid; | |
1348 | } | |
1349 | } | |
1350 | ||
1351 | struct task_struct * __cpuinit fork_idle(int cpu) | |
1352 | { | |
1353 | struct task_struct *task; | |
1354 | struct pt_regs regs; | |
1355 | ||
1356 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, | |
1357 | &init_struct_pid, 0); | |
1358 | if (!IS_ERR(task)) { | |
1359 | init_idle_pids(task->pids); | |
1360 | init_idle(task, cpu); | |
1361 | } | |
1362 | ||
1363 | return task; | |
1364 | } | |
1365 | ||
1366 | /* | |
1367 | * Ok, this is the main fork-routine. | |
1368 | * | |
1369 | * It copies the process, and if successful kick-starts | |
1370 | * it and waits for it to finish using the VM if required. | |
1371 | */ | |
1372 | long do_fork(unsigned long clone_flags, | |
1373 | unsigned long stack_start, | |
1374 | struct pt_regs *regs, | |
1375 | unsigned long stack_size, | |
1376 | int __user *parent_tidptr, | |
1377 | int __user *child_tidptr) | |
1378 | { | |
1379 | struct task_struct *p; | |
1380 | int trace = 0; | |
1381 | long nr; | |
1382 | ||
1383 | /* | |
1384 | * Do some preliminary argument and permissions checking before we | |
1385 | * actually start allocating stuff | |
1386 | */ | |
1387 | if (clone_flags & CLONE_NEWUSER) { | |
1388 | if (clone_flags & CLONE_THREAD) | |
1389 | return -EINVAL; | |
1390 | /* hopefully this check will go away when userns support is | |
1391 | * complete | |
1392 | */ | |
1393 | if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || | |
1394 | !capable(CAP_SETGID)) | |
1395 | return -EPERM; | |
1396 | } | |
1397 | ||
1398 | /* | |
1399 | * We hope to recycle these flags after 2.6.26 | |
1400 | */ | |
1401 | if (unlikely(clone_flags & CLONE_STOPPED)) { | |
1402 | static int __read_mostly count = 100; | |
1403 | ||
1404 | if (count > 0 && printk_ratelimit()) { | |
1405 | char comm[TASK_COMM_LEN]; | |
1406 | ||
1407 | count--; | |
1408 | printk(KERN_INFO "fork(): process `%s' used deprecated " | |
1409 | "clone flags 0x%lx\n", | |
1410 | get_task_comm(comm, current), | |
1411 | clone_flags & CLONE_STOPPED); | |
1412 | } | |
1413 | } | |
1414 | ||
1415 | /* | |
1416 | * When called from kernel_thread, don't do user tracing stuff. | |
1417 | */ | |
1418 | if (likely(user_mode(regs))) | |
1419 | trace = tracehook_prepare_clone(clone_flags); | |
1420 | ||
1421 | p = copy_process(clone_flags, stack_start, regs, stack_size, | |
1422 | child_tidptr, NULL, trace); | |
1423 | /* | |
1424 | * Do this prior waking up the new thread - the thread pointer | |
1425 | * might get invalid after that point, if the thread exits quickly. | |
1426 | */ | |
1427 | if (!IS_ERR(p)) { | |
1428 | struct completion vfork; | |
1429 | ||
1430 | trace_sched_process_fork(current, p); | |
1431 | ||
1432 | nr = task_pid_vnr(p); | |
1433 | ||
1434 | if (clone_flags & CLONE_PARENT_SETTID) | |
1435 | put_user(nr, parent_tidptr); | |
1436 | ||
1437 | if (clone_flags & CLONE_VFORK) { | |
1438 | p->vfork_done = &vfork; | |
1439 | init_completion(&vfork); | |
1440 | } | |
1441 | ||
1442 | audit_finish_fork(p); | |
1443 | tracehook_report_clone(regs, clone_flags, nr, p); | |
1444 | ||
1445 | /* | |
1446 | * We set PF_STARTING at creation in case tracing wants to | |
1447 | * use this to distinguish a fully live task from one that | |
1448 | * hasn't gotten to tracehook_report_clone() yet. Now we | |
1449 | * clear it and set the child going. | |
1450 | */ | |
1451 | p->flags &= ~PF_STARTING; | |
1452 | ||
1453 | if (unlikely(clone_flags & CLONE_STOPPED)) { | |
1454 | /* | |
1455 | * We'll start up with an immediate SIGSTOP. | |
1456 | */ | |
1457 | sigaddset(&p->pending.signal, SIGSTOP); | |
1458 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1459 | __set_task_state(p, TASK_STOPPED); | |
1460 | } else { | |
1461 | wake_up_new_task(p, clone_flags); | |
1462 | } | |
1463 | ||
1464 | tracehook_report_clone_complete(trace, regs, | |
1465 | clone_flags, nr, p); | |
1466 | ||
1467 | if (clone_flags & CLONE_VFORK) { | |
1468 | freezer_do_not_count(); | |
1469 | wait_for_completion(&vfork); | |
1470 | freezer_count(); | |
1471 | tracehook_report_vfork_done(p, nr); | |
1472 | } | |
1473 | } else { | |
1474 | nr = PTR_ERR(p); | |
1475 | } | |
1476 | return nr; | |
1477 | } | |
1478 | ||
1479 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN | |
1480 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 | |
1481 | #endif | |
1482 | ||
1483 | static void sighand_ctor(void *data) | |
1484 | { | |
1485 | struct sighand_struct *sighand = data; | |
1486 | ||
1487 | spin_lock_init(&sighand->siglock); | |
1488 | init_waitqueue_head(&sighand->signalfd_wqh); | |
1489 | } | |
1490 | ||
1491 | void __init proc_caches_init(void) | |
1492 | { | |
1493 | sighand_cachep = kmem_cache_create("sighand_cache", | |
1494 | sizeof(struct sighand_struct), 0, | |
1495 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| | |
1496 | SLAB_NOTRACK, sighand_ctor); | |
1497 | signal_cachep = kmem_cache_create("signal_cache", | |
1498 | sizeof(struct signal_struct), 0, | |
1499 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1500 | files_cachep = kmem_cache_create("files_cache", | |
1501 | sizeof(struct files_struct), 0, | |
1502 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1503 | fs_cachep = kmem_cache_create("fs_cache", | |
1504 | sizeof(struct fs_struct), 0, | |
1505 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1506 | mm_cachep = kmem_cache_create("mm_struct", | |
1507 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, | |
1508 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1509 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); | |
1510 | mmap_init(); | |
1511 | } | |
1512 | ||
1513 | /* | |
1514 | * Check constraints on flags passed to the unshare system call and | |
1515 | * force unsharing of additional process context as appropriate. | |
1516 | */ | |
1517 | static void check_unshare_flags(unsigned long *flags_ptr) | |
1518 | { | |
1519 | /* | |
1520 | * If unsharing a thread from a thread group, must also | |
1521 | * unshare vm. | |
1522 | */ | |
1523 | if (*flags_ptr & CLONE_THREAD) | |
1524 | *flags_ptr |= CLONE_VM; | |
1525 | ||
1526 | /* | |
1527 | * If unsharing vm, must also unshare signal handlers. | |
1528 | */ | |
1529 | if (*flags_ptr & CLONE_VM) | |
1530 | *flags_ptr |= CLONE_SIGHAND; | |
1531 | ||
1532 | /* | |
1533 | * If unsharing namespace, must also unshare filesystem information. | |
1534 | */ | |
1535 | if (*flags_ptr & CLONE_NEWNS) | |
1536 | *flags_ptr |= CLONE_FS; | |
1537 | } | |
1538 | ||
1539 | /* | |
1540 | * Unsharing of tasks created with CLONE_THREAD is not supported yet | |
1541 | */ | |
1542 | static int unshare_thread(unsigned long unshare_flags) | |
1543 | { | |
1544 | if (unshare_flags & CLONE_THREAD) | |
1545 | return -EINVAL; | |
1546 | ||
1547 | return 0; | |
1548 | } | |
1549 | ||
1550 | /* | |
1551 | * Unshare the filesystem structure if it is being shared | |
1552 | */ | |
1553 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) | |
1554 | { | |
1555 | struct fs_struct *fs = current->fs; | |
1556 | ||
1557 | if (!(unshare_flags & CLONE_FS) || !fs) | |
1558 | return 0; | |
1559 | ||
1560 | /* don't need lock here; in the worst case we'll do useless copy */ | |
1561 | if (fs->users == 1) | |
1562 | return 0; | |
1563 | ||
1564 | *new_fsp = copy_fs_struct(fs); | |
1565 | if (!*new_fsp) | |
1566 | return -ENOMEM; | |
1567 | ||
1568 | return 0; | |
1569 | } | |
1570 | ||
1571 | /* | |
1572 | * Unsharing of sighand is not supported yet | |
1573 | */ | |
1574 | static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) | |
1575 | { | |
1576 | struct sighand_struct *sigh = current->sighand; | |
1577 | ||
1578 | if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) | |
1579 | return -EINVAL; | |
1580 | else | |
1581 | return 0; | |
1582 | } | |
1583 | ||
1584 | /* | |
1585 | * Unshare vm if it is being shared | |
1586 | */ | |
1587 | static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) | |
1588 | { | |
1589 | struct mm_struct *mm = current->mm; | |
1590 | ||
1591 | if ((unshare_flags & CLONE_VM) && | |
1592 | (mm && atomic_read(&mm->mm_users) > 1)) { | |
1593 | return -EINVAL; | |
1594 | } | |
1595 | ||
1596 | return 0; | |
1597 | } | |
1598 | ||
1599 | /* | |
1600 | * Unshare file descriptor table if it is being shared | |
1601 | */ | |
1602 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) | |
1603 | { | |
1604 | struct files_struct *fd = current->files; | |
1605 | int error = 0; | |
1606 | ||
1607 | if ((unshare_flags & CLONE_FILES) && | |
1608 | (fd && atomic_read(&fd->count) > 1)) { | |
1609 | *new_fdp = dup_fd(fd, &error); | |
1610 | if (!*new_fdp) | |
1611 | return error; | |
1612 | } | |
1613 | ||
1614 | return 0; | |
1615 | } | |
1616 | ||
1617 | /* | |
1618 | * unshare allows a process to 'unshare' part of the process | |
1619 | * context which was originally shared using clone. copy_* | |
1620 | * functions used by do_fork() cannot be used here directly | |
1621 | * because they modify an inactive task_struct that is being | |
1622 | * constructed. Here we are modifying the current, active, | |
1623 | * task_struct. | |
1624 | */ | |
1625 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) | |
1626 | { | |
1627 | int err = 0; | |
1628 | struct fs_struct *fs, *new_fs = NULL; | |
1629 | struct sighand_struct *new_sigh = NULL; | |
1630 | struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; | |
1631 | struct files_struct *fd, *new_fd = NULL; | |
1632 | struct nsproxy *new_nsproxy = NULL; | |
1633 | int do_sysvsem = 0; | |
1634 | ||
1635 | check_unshare_flags(&unshare_flags); | |
1636 | ||
1637 | /* Return -EINVAL for all unsupported flags */ | |
1638 | err = -EINVAL; | |
1639 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| | |
1640 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| | |
1641 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET)) | |
1642 | goto bad_unshare_out; | |
1643 | ||
1644 | /* | |
1645 | * CLONE_NEWIPC must also detach from the undolist: after switching | |
1646 | * to a new ipc namespace, the semaphore arrays from the old | |
1647 | * namespace are unreachable. | |
1648 | */ | |
1649 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) | |
1650 | do_sysvsem = 1; | |
1651 | if ((err = unshare_thread(unshare_flags))) | |
1652 | goto bad_unshare_out; | |
1653 | if ((err = unshare_fs(unshare_flags, &new_fs))) | |
1654 | goto bad_unshare_cleanup_thread; | |
1655 | if ((err = unshare_sighand(unshare_flags, &new_sigh))) | |
1656 | goto bad_unshare_cleanup_fs; | |
1657 | if ((err = unshare_vm(unshare_flags, &new_mm))) | |
1658 | goto bad_unshare_cleanup_sigh; | |
1659 | if ((err = unshare_fd(unshare_flags, &new_fd))) | |
1660 | goto bad_unshare_cleanup_vm; | |
1661 | if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, | |
1662 | new_fs))) | |
1663 | goto bad_unshare_cleanup_fd; | |
1664 | ||
1665 | if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) { | |
1666 | if (do_sysvsem) { | |
1667 | /* | |
1668 | * CLONE_SYSVSEM is equivalent to sys_exit(). | |
1669 | */ | |
1670 | exit_sem(current); | |
1671 | } | |
1672 | ||
1673 | if (new_nsproxy) { | |
1674 | switch_task_namespaces(current, new_nsproxy); | |
1675 | new_nsproxy = NULL; | |
1676 | } | |
1677 | ||
1678 | task_lock(current); | |
1679 | ||
1680 | if (new_fs) { | |
1681 | fs = current->fs; | |
1682 | spin_lock(&fs->lock); | |
1683 | current->fs = new_fs; | |
1684 | if (--fs->users) | |
1685 | new_fs = NULL; | |
1686 | else | |
1687 | new_fs = fs; | |
1688 | spin_unlock(&fs->lock); | |
1689 | } | |
1690 | ||
1691 | if (new_mm) { | |
1692 | mm = current->mm; | |
1693 | active_mm = current->active_mm; | |
1694 | current->mm = new_mm; | |
1695 | current->active_mm = new_mm; | |
1696 | activate_mm(active_mm, new_mm); | |
1697 | new_mm = mm; | |
1698 | } | |
1699 | ||
1700 | if (new_fd) { | |
1701 | fd = current->files; | |
1702 | current->files = new_fd; | |
1703 | new_fd = fd; | |
1704 | } | |
1705 | ||
1706 | task_unlock(current); | |
1707 | } | |
1708 | ||
1709 | if (new_nsproxy) | |
1710 | put_nsproxy(new_nsproxy); | |
1711 | ||
1712 | bad_unshare_cleanup_fd: | |
1713 | if (new_fd) | |
1714 | put_files_struct(new_fd); | |
1715 | ||
1716 | bad_unshare_cleanup_vm: | |
1717 | if (new_mm) | |
1718 | mmput(new_mm); | |
1719 | ||
1720 | bad_unshare_cleanup_sigh: | |
1721 | if (new_sigh) | |
1722 | if (atomic_dec_and_test(&new_sigh->count)) | |
1723 | kmem_cache_free(sighand_cachep, new_sigh); | |
1724 | ||
1725 | bad_unshare_cleanup_fs: | |
1726 | if (new_fs) | |
1727 | free_fs_struct(new_fs); | |
1728 | ||
1729 | bad_unshare_cleanup_thread: | |
1730 | bad_unshare_out: | |
1731 | return err; | |
1732 | } | |
1733 | ||
1734 | /* | |
1735 | * Helper to unshare the files of the current task. | |
1736 | * We don't want to expose copy_files internals to | |
1737 | * the exec layer of the kernel. | |
1738 | */ | |
1739 | ||
1740 | int unshare_files(struct files_struct **displaced) | |
1741 | { | |
1742 | struct task_struct *task = current; | |
1743 | struct files_struct *copy = NULL; | |
1744 | int error; | |
1745 | ||
1746 | error = unshare_fd(CLONE_FILES, ©); | |
1747 | if (error || !copy) { | |
1748 | *displaced = NULL; | |
1749 | return error; | |
1750 | } | |
1751 | *displaced = task->files; | |
1752 | task_lock(task); | |
1753 | task->files = copy; | |
1754 | task_unlock(task); | |
1755 | return 0; | |
1756 | } |