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1 | /* |
2 | * linux/kernel/fork.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | */ |
6 | |
7 | /* |
8 | * 'fork.c' contains the help-routines for the 'fork' system call |
9 | * (see also entry.S and others). |
10 | * Fork is rather simple, once you get the hang of it, but the memory |
11 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' |
12 | */ |
13 | |
14 | #include <linux/slab.h> |
15 | #include <linux/init.h> |
16 | #include <linux/unistd.h> |
17 | #include <linux/module.h> |
18 | #include <linux/vmalloc.h> |
19 | #include <linux/completion.h> |
20 | #include <linux/personality.h> |
21 | #include <linux/mempolicy.h> |
22 | #include <linux/sem.h> |
23 | #include <linux/file.h> |
24 | #include <linux/fdtable.h> |
25 | #include <linux/iocontext.h> |
26 | #include <linux/key.h> |
27 | #include <linux/binfmts.h> |
28 | #include <linux/mman.h> |
29 | #include <linux/mmu_notifier.h> |
30 | #include <linux/fs.h> |
31 | #include <linux/mm.h> |
32 | #include <linux/vmacache.h> |
33 | #include <linux/nsproxy.h> |
34 | #include <linux/capability.h> |
35 | #include <linux/cpu.h> |
36 | #include <linux/cgroup.h> |
37 | #include <linux/security.h> |
38 | #include <linux/hugetlb.h> |
39 | #include <linux/seccomp.h> |
40 | #include <linux/swap.h> |
41 | #include <linux/syscalls.h> |
42 | #include <linux/jiffies.h> |
43 | #include <linux/futex.h> |
44 | #include <linux/compat.h> |
45 | #include <linux/kthread.h> |
46 | #include <linux/task_io_accounting_ops.h> |
47 | #include <linux/rcupdate.h> |
48 | #include <linux/ptrace.h> |
49 | #include <linux/mount.h> |
50 | #include <linux/audit.h> |
51 | #include <linux/memcontrol.h> |
52 | #include <linux/ftrace.h> |
53 | #include <linux/proc_fs.h> |
54 | #include <linux/profile.h> |
55 | #include <linux/rmap.h> |
56 | #include <linux/ksm.h> |
57 | #include <linux/acct.h> |
58 | #include <linux/tsacct_kern.h> |
59 | #include <linux/cn_proc.h> |
60 | #include <linux/freezer.h> |
61 | #include <linux/delayacct.h> |
62 | #include <linux/taskstats_kern.h> |
63 | #include <linux/random.h> |
64 | #include <linux/tty.h> |
65 | #include <linux/blkdev.h> |
66 | #include <linux/fs_struct.h> |
67 | #include <linux/magic.h> |
68 | #include <linux/perf_event.h> |
69 | #include <linux/posix-timers.h> |
70 | #include <linux/user-return-notifier.h> |
71 | #include <linux/oom.h> |
72 | #include <linux/khugepaged.h> |
73 | #include <linux/signalfd.h> |
74 | #include <linux/uprobes.h> |
75 | #include <linux/aio.h> |
76 | #include <linux/compiler.h> |
77 | |
78 | #include <asm/pgtable.h> |
79 | #include <asm/pgalloc.h> |
80 | #include <asm/uaccess.h> |
81 | #include <asm/mmu_context.h> |
82 | #include <asm/cacheflush.h> |
83 | #include <asm/tlbflush.h> |
84 | |
85 | #include <trace/events/sched.h> |
86 | |
87 | #define CREATE_TRACE_POINTS |
88 | #include <trace/events/task.h> |
89 | |
90 | /* |
91 | * Protected counters by write_lock_irq(&tasklist_lock) |
92 | */ |
93 | unsigned long total_forks; /* Handle normal Linux uptimes. */ |
94 | int nr_threads; /* The idle threads do not count.. */ |
95 | |
96 | int max_threads; /* tunable limit on nr_threads */ |
97 | |
98 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; |
99 | |
100 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ |
101 | |
102 | #ifdef CONFIG_PROVE_RCU |
103 | int lockdep_tasklist_lock_is_held(void) |
104 | { |
105 | return lockdep_is_held(&tasklist_lock); |
106 | } |
107 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); |
108 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
109 | |
110 | int nr_processes(void) |
111 | { |
112 | int cpu; |
113 | int total = 0; |
114 | |
115 | for_each_possible_cpu(cpu) |
116 | total += per_cpu(process_counts, cpu); |
117 | |
118 | return total; |
119 | } |
120 | |
121 | void __weak arch_release_task_struct(struct task_struct *tsk) |
122 | { |
123 | } |
124 | |
125 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
126 | static struct kmem_cache *task_struct_cachep; |
127 | |
128 | static inline struct task_struct *alloc_task_struct_node(int node) |
129 | { |
130 | return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); |
131 | } |
132 | |
133 | static inline void free_task_struct(struct task_struct *tsk) |
134 | { |
135 | kmem_cache_free(task_struct_cachep, tsk); |
136 | } |
137 | #endif |
138 | |
139 | void __weak arch_release_thread_info(struct thread_info *ti) |
140 | { |
141 | } |
142 | |
143 | #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR |
144 | |
145 | /* |
146 | * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a |
147 | * kmemcache based allocator. |
148 | */ |
149 | # if THREAD_SIZE >= PAGE_SIZE |
150 | static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, |
151 | int node) |
152 | { |
153 | struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP, |
154 | THREAD_SIZE_ORDER); |
155 | |
156 | return page ? page_address(page) : NULL; |
157 | } |
158 | |
159 | static inline void free_thread_info(struct thread_info *ti) |
160 | { |
161 | free_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER); |
162 | } |
163 | # else |
164 | static struct kmem_cache *thread_info_cache; |
165 | |
166 | static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, |
167 | int node) |
168 | { |
169 | return kmem_cache_alloc_node(thread_info_cache, THREADINFO_GFP, node); |
170 | } |
171 | |
172 | static void free_thread_info(struct thread_info *ti) |
173 | { |
174 | kmem_cache_free(thread_info_cache, ti); |
175 | } |
176 | |
177 | void thread_info_cache_init(void) |
178 | { |
179 | thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE, |
180 | THREAD_SIZE, 0, NULL); |
181 | BUG_ON(thread_info_cache == NULL); |
182 | } |
183 | # endif |
184 | #endif |
185 | |
186 | /* SLAB cache for signal_struct structures (tsk->signal) */ |
187 | static struct kmem_cache *signal_cachep; |
188 | |
189 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ |
190 | struct kmem_cache *sighand_cachep; |
191 | |
192 | /* SLAB cache for files_struct structures (tsk->files) */ |
193 | struct kmem_cache *files_cachep; |
194 | |
195 | /* SLAB cache for fs_struct structures (tsk->fs) */ |
196 | struct kmem_cache *fs_cachep; |
197 | |
198 | /* SLAB cache for vm_area_struct structures */ |
199 | struct kmem_cache *vm_area_cachep; |
200 | |
201 | /* SLAB cache for mm_struct structures (tsk->mm) */ |
202 | static struct kmem_cache *mm_cachep; |
203 | |
204 | static void account_kernel_stack(struct thread_info *ti, int account) |
205 | { |
206 | struct zone *zone = page_zone(virt_to_page(ti)); |
207 | |
208 | mod_zone_page_state(zone, NR_KERNEL_STACK, account); |
209 | } |
210 | |
211 | void free_task(struct task_struct *tsk) |
212 | { |
213 | account_kernel_stack(tsk->stack, -1); |
214 | arch_release_thread_info(tsk->stack); |
215 | free_thread_info(tsk->stack); |
216 | rt_mutex_debug_task_free(tsk); |
217 | ftrace_graph_exit_task(tsk); |
218 | put_seccomp_filter(tsk); |
219 | arch_release_task_struct(tsk); |
220 | free_task_struct(tsk); |
221 | } |
222 | EXPORT_SYMBOL(free_task); |
223 | |
224 | static inline void free_signal_struct(struct signal_struct *sig) |
225 | { |
226 | taskstats_tgid_free(sig); |
227 | sched_autogroup_exit(sig); |
228 | kmem_cache_free(signal_cachep, sig); |
229 | } |
230 | |
231 | static inline void put_signal_struct(struct signal_struct *sig) |
232 | { |
233 | if (atomic_dec_and_test(&sig->sigcnt)) |
234 | free_signal_struct(sig); |
235 | } |
236 | |
237 | void __put_task_struct(struct task_struct *tsk) |
238 | { |
239 | WARN_ON(!tsk->exit_state); |
240 | WARN_ON(atomic_read(&tsk->usage)); |
241 | WARN_ON(tsk == current); |
242 | |
243 | task_numa_free(tsk); |
244 | security_task_free(tsk); |
245 | exit_creds(tsk); |
246 | delayacct_tsk_free(tsk); |
247 | put_signal_struct(tsk->signal); |
248 | |
249 | if (!profile_handoff_task(tsk)) |
250 | free_task(tsk); |
251 | } |
252 | EXPORT_SYMBOL_GPL(__put_task_struct); |
253 | |
254 | void __init __weak arch_task_cache_init(void) { } |
255 | |
256 | void __init fork_init(unsigned long mempages) |
257 | { |
258 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
259 | #ifndef ARCH_MIN_TASKALIGN |
260 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES |
261 | #endif |
262 | /* create a slab on which task_structs can be allocated */ |
263 | task_struct_cachep = |
264 | kmem_cache_create("task_struct", sizeof(struct task_struct), |
265 | ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); |
266 | #endif |
267 | |
268 | /* do the arch specific task caches init */ |
269 | arch_task_cache_init(); |
270 | |
271 | /* |
272 | * The default maximum number of threads is set to a safe |
273 | * value: the thread structures can take up at most half |
274 | * of memory. |
275 | */ |
276 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); |
277 | |
278 | /* |
279 | * we need to allow at least 20 threads to boot a system |
280 | */ |
281 | if (max_threads < 20) |
282 | max_threads = 20; |
283 | |
284 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; |
285 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |
286 | init_task.signal->rlim[RLIMIT_SIGPENDING] = |
287 | init_task.signal->rlim[RLIMIT_NPROC]; |
288 | } |
289 | |
290 | int __weak arch_dup_task_struct(struct task_struct *dst, |
291 | struct task_struct *src) |
292 | { |
293 | *dst = *src; |
294 | return 0; |
295 | } |
296 | |
297 | static struct task_struct *dup_task_struct(struct task_struct *orig) |
298 | { |
299 | struct task_struct *tsk; |
300 | struct thread_info *ti; |
301 | unsigned long *stackend; |
302 | int node = tsk_fork_get_node(orig); |
303 | int err; |
304 | |
305 | tsk = alloc_task_struct_node(node); |
306 | if (!tsk) |
307 | return NULL; |
308 | |
309 | ti = alloc_thread_info_node(tsk, node); |
310 | if (!ti) |
311 | goto free_tsk; |
312 | |
313 | err = arch_dup_task_struct(tsk, orig); |
314 | if (err) |
315 | goto free_ti; |
316 | |
317 | tsk->stack = ti; |
318 | |
319 | setup_thread_stack(tsk, orig); |
320 | clear_user_return_notifier(tsk); |
321 | clear_tsk_need_resched(tsk); |
322 | stackend = end_of_stack(tsk); |
323 | *stackend = STACK_END_MAGIC; /* for overflow detection */ |
324 | |
325 | #ifdef CONFIG_CC_STACKPROTECTOR |
326 | tsk->stack_canary = get_random_int(); |
327 | #endif |
328 | |
329 | /* |
330 | * One for us, one for whoever does the "release_task()" (usually |
331 | * parent) |
332 | */ |
333 | atomic_set(&tsk->usage, 2); |
334 | #ifdef CONFIG_BLK_DEV_IO_TRACE |
335 | tsk->btrace_seq = 0; |
336 | #endif |
337 | tsk->splice_pipe = NULL; |
338 | tsk->task_frag.page = NULL; |
339 | |
340 | account_kernel_stack(ti, 1); |
341 | |
342 | return tsk; |
343 | |
344 | free_ti: |
345 | free_thread_info(ti); |
346 | free_tsk: |
347 | free_task_struct(tsk); |
348 | return NULL; |
349 | } |
350 | |
351 | #ifdef CONFIG_MMU |
352 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) |
353 | { |
354 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; |
355 | struct rb_node **rb_link, *rb_parent; |
356 | int retval; |
357 | unsigned long charge; |
358 | |
359 | uprobe_start_dup_mmap(); |
360 | down_write(&oldmm->mmap_sem); |
361 | flush_cache_dup_mm(oldmm); |
362 | uprobe_dup_mmap(oldmm, mm); |
363 | /* |
364 | * Not linked in yet - no deadlock potential: |
365 | */ |
366 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); |
367 | |
368 | mm->locked_vm = 0; |
369 | mm->mmap = NULL; |
370 | mm->vmacache_seqnum = 0; |
371 | mm->map_count = 0; |
372 | cpumask_clear(mm_cpumask(mm)); |
373 | mm->mm_rb = RB_ROOT; |
374 | rb_link = &mm->mm_rb.rb_node; |
375 | rb_parent = NULL; |
376 | pprev = &mm->mmap; |
377 | retval = ksm_fork(mm, oldmm); |
378 | if (retval) |
379 | goto out; |
380 | retval = khugepaged_fork(mm, oldmm); |
381 | if (retval) |
382 | goto out; |
383 | |
384 | prev = NULL; |
385 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { |
386 | struct file *file; |
387 | |
388 | if (mpnt->vm_flags & VM_DONTCOPY) { |
389 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, |
390 | -vma_pages(mpnt)); |
391 | continue; |
392 | } |
393 | charge = 0; |
394 | if (mpnt->vm_flags & VM_ACCOUNT) { |
395 | unsigned long len = vma_pages(mpnt); |
396 | |
397 | if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ |
398 | goto fail_nomem; |
399 | charge = len; |
400 | } |
401 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
402 | if (!tmp) |
403 | goto fail_nomem; |
404 | *tmp = *mpnt; |
405 | INIT_LIST_HEAD(&tmp->anon_vma_chain); |
406 | retval = vma_dup_policy(mpnt, tmp); |
407 | if (retval) |
408 | goto fail_nomem_policy; |
409 | tmp->vm_mm = mm; |
410 | if (anon_vma_fork(tmp, mpnt)) |
411 | goto fail_nomem_anon_vma_fork; |
412 | tmp->vm_flags &= ~VM_LOCKED; |
413 | tmp->vm_next = tmp->vm_prev = NULL; |
414 | file = tmp->vm_file; |
415 | if (file) { |
416 | struct inode *inode = file_inode(file); |
417 | struct address_space *mapping = file->f_mapping; |
418 | |
419 | get_file(file); |
420 | if (tmp->vm_flags & VM_DENYWRITE) |
421 | atomic_dec(&inode->i_writecount); |
422 | mutex_lock(&mapping->i_mmap_mutex); |
423 | if (tmp->vm_flags & VM_SHARED) |
424 | mapping->i_mmap_writable++; |
425 | flush_dcache_mmap_lock(mapping); |
426 | /* insert tmp into the share list, just after mpnt */ |
427 | if (unlikely(tmp->vm_flags & VM_NONLINEAR)) |
428 | vma_nonlinear_insert(tmp, |
429 | &mapping->i_mmap_nonlinear); |
430 | else |
431 | vma_interval_tree_insert_after(tmp, mpnt, |
432 | &mapping->i_mmap); |
433 | flush_dcache_mmap_unlock(mapping); |
434 | mutex_unlock(&mapping->i_mmap_mutex); |
435 | } |
436 | |
437 | /* |
438 | * Clear hugetlb-related page reserves for children. This only |
439 | * affects MAP_PRIVATE mappings. Faults generated by the child |
440 | * are not guaranteed to succeed, even if read-only |
441 | */ |
442 | if (is_vm_hugetlb_page(tmp)) |
443 | reset_vma_resv_huge_pages(tmp); |
444 | |
445 | /* |
446 | * Link in the new vma and copy the page table entries. |
447 | */ |
448 | *pprev = tmp; |
449 | pprev = &tmp->vm_next; |
450 | tmp->vm_prev = prev; |
451 | prev = tmp; |
452 | |
453 | __vma_link_rb(mm, tmp, rb_link, rb_parent); |
454 | rb_link = &tmp->vm_rb.rb_right; |
455 | rb_parent = &tmp->vm_rb; |
456 | |
457 | mm->map_count++; |
458 | retval = copy_page_range(mm, oldmm, mpnt); |
459 | |
460 | if (tmp->vm_ops && tmp->vm_ops->open) |
461 | tmp->vm_ops->open(tmp); |
462 | |
463 | if (retval) |
464 | goto out; |
465 | } |
466 | /* a new mm has just been created */ |
467 | arch_dup_mmap(oldmm, mm); |
468 | retval = 0; |
469 | out: |
470 | up_write(&mm->mmap_sem); |
471 | flush_tlb_mm(oldmm); |
472 | up_write(&oldmm->mmap_sem); |
473 | uprobe_end_dup_mmap(); |
474 | return retval; |
475 | fail_nomem_anon_vma_fork: |
476 | mpol_put(vma_policy(tmp)); |
477 | fail_nomem_policy: |
478 | kmem_cache_free(vm_area_cachep, tmp); |
479 | fail_nomem: |
480 | retval = -ENOMEM; |
481 | vm_unacct_memory(charge); |
482 | goto out; |
483 | } |
484 | |
485 | static inline int mm_alloc_pgd(struct mm_struct *mm) |
486 | { |
487 | mm->pgd = pgd_alloc(mm); |
488 | if (unlikely(!mm->pgd)) |
489 | return -ENOMEM; |
490 | return 0; |
491 | } |
492 | |
493 | static inline void mm_free_pgd(struct mm_struct *mm) |
494 | { |
495 | pgd_free(mm, mm->pgd); |
496 | } |
497 | #else |
498 | #define dup_mmap(mm, oldmm) (0) |
499 | #define mm_alloc_pgd(mm) (0) |
500 | #define mm_free_pgd(mm) |
501 | #endif /* CONFIG_MMU */ |
502 | |
503 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); |
504 | |
505 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) |
506 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) |
507 | |
508 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; |
509 | |
510 | static int __init coredump_filter_setup(char *s) |
511 | { |
512 | default_dump_filter = |
513 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & |
514 | MMF_DUMP_FILTER_MASK; |
515 | return 1; |
516 | } |
517 | |
518 | __setup("coredump_filter=", coredump_filter_setup); |
519 | |
520 | #include <linux/init_task.h> |
521 | |
522 | static void mm_init_aio(struct mm_struct *mm) |
523 | { |
524 | #ifdef CONFIG_AIO |
525 | spin_lock_init(&mm->ioctx_lock); |
526 | mm->ioctx_table = NULL; |
527 | #endif |
528 | } |
529 | |
530 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) |
531 | { |
532 | atomic_set(&mm->mm_users, 1); |
533 | atomic_set(&mm->mm_count, 1); |
534 | init_rwsem(&mm->mmap_sem); |
535 | INIT_LIST_HEAD(&mm->mmlist); |
536 | mm->core_state = NULL; |
537 | atomic_long_set(&mm->nr_ptes, 0); |
538 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); |
539 | spin_lock_init(&mm->page_table_lock); |
540 | mm_init_aio(mm); |
541 | mm_init_owner(mm, p); |
542 | clear_tlb_flush_pending(mm); |
543 | |
544 | if (current->mm) { |
545 | mm->flags = current->mm->flags & MMF_INIT_MASK; |
546 | mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; |
547 | } else { |
548 | mm->flags = default_dump_filter; |
549 | mm->def_flags = 0; |
550 | } |
551 | |
552 | if (likely(!mm_alloc_pgd(mm))) { |
553 | mmu_notifier_mm_init(mm); |
554 | return mm; |
555 | } |
556 | |
557 | free_mm(mm); |
558 | return NULL; |
559 | } |
560 | |
561 | static void check_mm(struct mm_struct *mm) |
562 | { |
563 | int i; |
564 | |
565 | for (i = 0; i < NR_MM_COUNTERS; i++) { |
566 | long x = atomic_long_read(&mm->rss_stat.count[i]); |
567 | |
568 | if (unlikely(x)) |
569 | printk(KERN_ALERT "BUG: Bad rss-counter state " |
570 | "mm:%p idx:%d val:%ld\n", mm, i, x); |
571 | } |
572 | |
573 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS |
574 | VM_BUG_ON(mm->pmd_huge_pte); |
575 | #endif |
576 | } |
577 | |
578 | /* |
579 | * Allocate and initialize an mm_struct. |
580 | */ |
581 | struct mm_struct *mm_alloc(void) |
582 | { |
583 | struct mm_struct *mm; |
584 | |
585 | mm = allocate_mm(); |
586 | if (!mm) |
587 | return NULL; |
588 | |
589 | memset(mm, 0, sizeof(*mm)); |
590 | mm_init_cpumask(mm); |
591 | return mm_init(mm, current); |
592 | } |
593 | |
594 | /* |
595 | * Called when the last reference to the mm |
596 | * is dropped: either by a lazy thread or by |
597 | * mmput. Free the page directory and the mm. |
598 | */ |
599 | void __mmdrop(struct mm_struct *mm) |
600 | { |
601 | BUG_ON(mm == &init_mm); |
602 | mm_free_pgd(mm); |
603 | destroy_context(mm); |
604 | mmu_notifier_mm_destroy(mm); |
605 | check_mm(mm); |
606 | free_mm(mm); |
607 | } |
608 | EXPORT_SYMBOL_GPL(__mmdrop); |
609 | |
610 | /* |
611 | * Decrement the use count and release all resources for an mm. |
612 | */ |
613 | void mmput(struct mm_struct *mm) |
614 | { |
615 | might_sleep(); |
616 | |
617 | if (atomic_dec_and_test(&mm->mm_users)) { |
618 | uprobe_clear_state(mm); |
619 | exit_aio(mm); |
620 | ksm_exit(mm); |
621 | khugepaged_exit(mm); /* must run before exit_mmap */ |
622 | exit_mmap(mm); |
623 | set_mm_exe_file(mm, NULL); |
624 | if (!list_empty(&mm->mmlist)) { |
625 | spin_lock(&mmlist_lock); |
626 | list_del(&mm->mmlist); |
627 | spin_unlock(&mmlist_lock); |
628 | } |
629 | if (mm->binfmt) |
630 | module_put(mm->binfmt->module); |
631 | mmdrop(mm); |
632 | } |
633 | } |
634 | EXPORT_SYMBOL_GPL(mmput); |
635 | |
636 | void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) |
637 | { |
638 | if (new_exe_file) |
639 | get_file(new_exe_file); |
640 | if (mm->exe_file) |
641 | fput(mm->exe_file); |
642 | mm->exe_file = new_exe_file; |
643 | } |
644 | |
645 | struct file *get_mm_exe_file(struct mm_struct *mm) |
646 | { |
647 | struct file *exe_file; |
648 | |
649 | /* We need mmap_sem to protect against races with removal of exe_file */ |
650 | down_read(&mm->mmap_sem); |
651 | exe_file = mm->exe_file; |
652 | if (exe_file) |
653 | get_file(exe_file); |
654 | up_read(&mm->mmap_sem); |
655 | return exe_file; |
656 | } |
657 | |
658 | static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm) |
659 | { |
660 | /* It's safe to write the exe_file pointer without exe_file_lock because |
661 | * this is called during fork when the task is not yet in /proc */ |
662 | newmm->exe_file = get_mm_exe_file(oldmm); |
663 | } |
664 | |
665 | /** |
666 | * get_task_mm - acquire a reference to the task's mm |
667 | * |
668 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning |
669 | * this kernel workthread has transiently adopted a user mm with use_mm, |
670 | * to do its AIO) is not set and if so returns a reference to it, after |
671 | * bumping up the use count. User must release the mm via mmput() |
672 | * after use. Typically used by /proc and ptrace. |
673 | */ |
674 | struct mm_struct *get_task_mm(struct task_struct *task) |
675 | { |
676 | struct mm_struct *mm; |
677 | |
678 | task_lock(task); |
679 | mm = task->mm; |
680 | if (mm) { |
681 | if (task->flags & PF_KTHREAD) |
682 | mm = NULL; |
683 | else |
684 | atomic_inc(&mm->mm_users); |
685 | } |
686 | task_unlock(task); |
687 | return mm; |
688 | } |
689 | EXPORT_SYMBOL_GPL(get_task_mm); |
690 | |
691 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) |
692 | { |
693 | struct mm_struct *mm; |
694 | int err; |
695 | |
696 | err = mutex_lock_killable(&task->signal->cred_guard_mutex); |
697 | if (err) |
698 | return ERR_PTR(err); |
699 | |
700 | mm = get_task_mm(task); |
701 | if (mm && mm != current->mm && |
702 | !ptrace_may_access(task, mode)) { |
703 | mmput(mm); |
704 | mm = ERR_PTR(-EACCES); |
705 | } |
706 | mutex_unlock(&task->signal->cred_guard_mutex); |
707 | |
708 | return mm; |
709 | } |
710 | |
711 | static void complete_vfork_done(struct task_struct *tsk) |
712 | { |
713 | struct completion *vfork; |
714 | |
715 | task_lock(tsk); |
716 | vfork = tsk->vfork_done; |
717 | if (likely(vfork)) { |
718 | tsk->vfork_done = NULL; |
719 | complete(vfork); |
720 | } |
721 | task_unlock(tsk); |
722 | } |
723 | |
724 | static int wait_for_vfork_done(struct task_struct *child, |
725 | struct completion *vfork) |
726 | { |
727 | int killed; |
728 | |
729 | freezer_do_not_count(); |
730 | killed = wait_for_completion_killable(vfork); |
731 | freezer_count(); |
732 | |
733 | if (killed) { |
734 | task_lock(child); |
735 | child->vfork_done = NULL; |
736 | task_unlock(child); |
737 | } |
738 | |
739 | put_task_struct(child); |
740 | return killed; |
741 | } |
742 | |
743 | /* Please note the differences between mmput and mm_release. |
744 | * mmput is called whenever we stop holding onto a mm_struct, |
745 | * error success whatever. |
746 | * |
747 | * mm_release is called after a mm_struct has been removed |
748 | * from the current process. |
749 | * |
750 | * This difference is important for error handling, when we |
751 | * only half set up a mm_struct for a new process and need to restore |
752 | * the old one. Because we mmput the new mm_struct before |
753 | * restoring the old one. . . |
754 | * Eric Biederman 10 January 1998 |
755 | */ |
756 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) |
757 | { |
758 | /* Get rid of any futexes when releasing the mm */ |
759 | #ifdef CONFIG_FUTEX |
760 | if (unlikely(tsk->robust_list)) { |
761 | exit_robust_list(tsk); |
762 | tsk->robust_list = NULL; |
763 | } |
764 | #ifdef CONFIG_COMPAT |
765 | if (unlikely(tsk->compat_robust_list)) { |
766 | compat_exit_robust_list(tsk); |
767 | tsk->compat_robust_list = NULL; |
768 | } |
769 | #endif |
770 | if (unlikely(!list_empty(&tsk->pi_state_list))) |
771 | exit_pi_state_list(tsk); |
772 | #endif |
773 | |
774 | uprobe_free_utask(tsk); |
775 | |
776 | /* Get rid of any cached register state */ |
777 | deactivate_mm(tsk, mm); |
778 | |
779 | /* |
780 | * If we're exiting normally, clear a user-space tid field if |
781 | * requested. We leave this alone when dying by signal, to leave |
782 | * the value intact in a core dump, and to save the unnecessary |
783 | * trouble, say, a killed vfork parent shouldn't touch this mm. |
784 | * Userland only wants this done for a sys_exit. |
785 | */ |
786 | if (tsk->clear_child_tid) { |
787 | if (!(tsk->flags & PF_SIGNALED) && |
788 | atomic_read(&mm->mm_users) > 1) { |
789 | /* |
790 | * We don't check the error code - if userspace has |
791 | * not set up a proper pointer then tough luck. |
792 | */ |
793 | put_user(0, tsk->clear_child_tid); |
794 | sys_futex(tsk->clear_child_tid, FUTEX_WAKE, |
795 | 1, NULL, NULL, 0); |
796 | } |
797 | tsk->clear_child_tid = NULL; |
798 | } |
799 | |
800 | /* |
801 | * All done, finally we can wake up parent and return this mm to him. |
802 | * Also kthread_stop() uses this completion for synchronization. |
803 | */ |
804 | if (tsk->vfork_done) |
805 | complete_vfork_done(tsk); |
806 | } |
807 | |
808 | /* |
809 | * Allocate a new mm structure and copy contents from the |
810 | * mm structure of the passed in task structure. |
811 | */ |
812 | static struct mm_struct *dup_mm(struct task_struct *tsk) |
813 | { |
814 | struct mm_struct *mm, *oldmm = current->mm; |
815 | int err; |
816 | |
817 | mm = allocate_mm(); |
818 | if (!mm) |
819 | goto fail_nomem; |
820 | |
821 | memcpy(mm, oldmm, sizeof(*mm)); |
822 | mm_init_cpumask(mm); |
823 | |
824 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS |
825 | mm->pmd_huge_pte = NULL; |
826 | #endif |
827 | if (!mm_init(mm, tsk)) |
828 | goto fail_nomem; |
829 | |
830 | if (init_new_context(tsk, mm)) |
831 | goto fail_nocontext; |
832 | |
833 | dup_mm_exe_file(oldmm, mm); |
834 | |
835 | err = dup_mmap(mm, oldmm); |
836 | if (err) |
837 | goto free_pt; |
838 | |
839 | mm->hiwater_rss = get_mm_rss(mm); |
840 | mm->hiwater_vm = mm->total_vm; |
841 | |
842 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) |
843 | goto free_pt; |
844 | |
845 | return mm; |
846 | |
847 | free_pt: |
848 | /* don't put binfmt in mmput, we haven't got module yet */ |
849 | mm->binfmt = NULL; |
850 | mmput(mm); |
851 | |
852 | fail_nomem: |
853 | return NULL; |
854 | |
855 | fail_nocontext: |
856 | /* |
857 | * If init_new_context() failed, we cannot use mmput() to free the mm |
858 | * because it calls destroy_context() |
859 | */ |
860 | mm_free_pgd(mm); |
861 | free_mm(mm); |
862 | return NULL; |
863 | } |
864 | |
865 | static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) |
866 | { |
867 | struct mm_struct *mm, *oldmm; |
868 | int retval; |
869 | |
870 | tsk->min_flt = tsk->maj_flt = 0; |
871 | tsk->nvcsw = tsk->nivcsw = 0; |
872 | #ifdef CONFIG_DETECT_HUNG_TASK |
873 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; |
874 | #endif |
875 | |
876 | tsk->mm = NULL; |
877 | tsk->active_mm = NULL; |
878 | |
879 | /* |
880 | * Are we cloning a kernel thread? |
881 | * |
882 | * We need to steal a active VM for that.. |
883 | */ |
884 | oldmm = current->mm; |
885 | if (!oldmm) |
886 | return 0; |
887 | |
888 | /* initialize the new vmacache entries */ |
889 | vmacache_flush(tsk); |
890 | |
891 | if (clone_flags & CLONE_VM) { |
892 | atomic_inc(&oldmm->mm_users); |
893 | mm = oldmm; |
894 | goto good_mm; |
895 | } |
896 | |
897 | retval = -ENOMEM; |
898 | mm = dup_mm(tsk); |
899 | if (!mm) |
900 | goto fail_nomem; |
901 | |
902 | good_mm: |
903 | tsk->mm = mm; |
904 | tsk->active_mm = mm; |
905 | return 0; |
906 | |
907 | fail_nomem: |
908 | return retval; |
909 | } |
910 | |
911 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) |
912 | { |
913 | struct fs_struct *fs = current->fs; |
914 | if (clone_flags & CLONE_FS) { |
915 | /* tsk->fs is already what we want */ |
916 | spin_lock(&fs->lock); |
917 | if (fs->in_exec) { |
918 | spin_unlock(&fs->lock); |
919 | return -EAGAIN; |
920 | } |
921 | fs->users++; |
922 | spin_unlock(&fs->lock); |
923 | return 0; |
924 | } |
925 | tsk->fs = copy_fs_struct(fs); |
926 | if (!tsk->fs) |
927 | return -ENOMEM; |
928 | return 0; |
929 | } |
930 | |
931 | static int copy_files(unsigned long clone_flags, struct task_struct *tsk) |
932 | { |
933 | struct files_struct *oldf, *newf; |
934 | int error = 0; |
935 | |
936 | /* |
937 | * A background process may not have any files ... |
938 | */ |
939 | oldf = current->files; |
940 | if (!oldf) |
941 | goto out; |
942 | |
943 | if (clone_flags & CLONE_FILES) { |
944 | atomic_inc(&oldf->count); |
945 | goto out; |
946 | } |
947 | |
948 | newf = dup_fd(oldf, &error); |
949 | if (!newf) |
950 | goto out; |
951 | |
952 | tsk->files = newf; |
953 | error = 0; |
954 | out: |
955 | return error; |
956 | } |
957 | |
958 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) |
959 | { |
960 | #ifdef CONFIG_BLOCK |
961 | struct io_context *ioc = current->io_context; |
962 | struct io_context *new_ioc; |
963 | |
964 | if (!ioc) |
965 | return 0; |
966 | /* |
967 | * Share io context with parent, if CLONE_IO is set |
968 | */ |
969 | if (clone_flags & CLONE_IO) { |
970 | ioc_task_link(ioc); |
971 | tsk->io_context = ioc; |
972 | } else if (ioprio_valid(ioc->ioprio)) { |
973 | new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); |
974 | if (unlikely(!new_ioc)) |
975 | return -ENOMEM; |
976 | |
977 | new_ioc->ioprio = ioc->ioprio; |
978 | put_io_context(new_ioc); |
979 | } |
980 | #endif |
981 | return 0; |
982 | } |
983 | |
984 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) |
985 | { |
986 | struct sighand_struct *sig; |
987 | |
988 | if (clone_flags & CLONE_SIGHAND) { |
989 | atomic_inc(¤t->sighand->count); |
990 | return 0; |
991 | } |
992 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
993 | rcu_assign_pointer(tsk->sighand, sig); |
994 | if (!sig) |
995 | return -ENOMEM; |
996 | atomic_set(&sig->count, 1); |
997 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); |
998 | return 0; |
999 | } |
1000 | |
1001 | void __cleanup_sighand(struct sighand_struct *sighand) |
1002 | { |
1003 | if (atomic_dec_and_test(&sighand->count)) { |
1004 | signalfd_cleanup(sighand); |
1005 | kmem_cache_free(sighand_cachep, sighand); |
1006 | } |
1007 | } |
1008 | |
1009 | |
1010 | /* |
1011 | * Initialize POSIX timer handling for a thread group. |
1012 | */ |
1013 | static void posix_cpu_timers_init_group(struct signal_struct *sig) |
1014 | { |
1015 | unsigned long cpu_limit; |
1016 | |
1017 | /* Thread group counters. */ |
1018 | thread_group_cputime_init(sig); |
1019 | |
1020 | cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
1021 | if (cpu_limit != RLIM_INFINITY) { |
1022 | sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); |
1023 | sig->cputimer.running = 1; |
1024 | } |
1025 | |
1026 | /* The timer lists. */ |
1027 | INIT_LIST_HEAD(&sig->cpu_timers[0]); |
1028 | INIT_LIST_HEAD(&sig->cpu_timers[1]); |
1029 | INIT_LIST_HEAD(&sig->cpu_timers[2]); |
1030 | } |
1031 | |
1032 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) |
1033 | { |
1034 | struct signal_struct *sig; |
1035 | |
1036 | if (clone_flags & CLONE_THREAD) |
1037 | return 0; |
1038 | |
1039 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); |
1040 | tsk->signal = sig; |
1041 | if (!sig) |
1042 | return -ENOMEM; |
1043 | |
1044 | sig->nr_threads = 1; |
1045 | atomic_set(&sig->live, 1); |
1046 | atomic_set(&sig->sigcnt, 1); |
1047 | |
1048 | /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ |
1049 | sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); |
1050 | tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); |
1051 | |
1052 | init_waitqueue_head(&sig->wait_chldexit); |
1053 | sig->curr_target = tsk; |
1054 | init_sigpending(&sig->shared_pending); |
1055 | INIT_LIST_HEAD(&sig->posix_timers); |
1056 | |
1057 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
1058 | sig->real_timer.function = it_real_fn; |
1059 | |
1060 | task_lock(current->group_leader); |
1061 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); |
1062 | task_unlock(current->group_leader); |
1063 | |
1064 | posix_cpu_timers_init_group(sig); |
1065 | |
1066 | tty_audit_fork(sig); |
1067 | sched_autogroup_fork(sig); |
1068 | |
1069 | #ifdef CONFIG_CGROUPS |
1070 | init_rwsem(&sig->group_rwsem); |
1071 | #endif |
1072 | |
1073 | sig->oom_score_adj = current->signal->oom_score_adj; |
1074 | sig->oom_score_adj_min = current->signal->oom_score_adj_min; |
1075 | |
1076 | sig->has_child_subreaper = current->signal->has_child_subreaper || |
1077 | current->signal->is_child_subreaper; |
1078 | |
1079 | mutex_init(&sig->cred_guard_mutex); |
1080 | |
1081 | return 0; |
1082 | } |
1083 | |
1084 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) |
1085 | { |
1086 | current->clear_child_tid = tidptr; |
1087 | |
1088 | return task_pid_vnr(current); |
1089 | } |
1090 | |
1091 | static void rt_mutex_init_task(struct task_struct *p) |
1092 | { |
1093 | raw_spin_lock_init(&p->pi_lock); |
1094 | #ifdef CONFIG_RT_MUTEXES |
1095 | p->pi_waiters = RB_ROOT; |
1096 | p->pi_waiters_leftmost = NULL; |
1097 | p->pi_blocked_on = NULL; |
1098 | p->pi_top_task = NULL; |
1099 | #endif |
1100 | } |
1101 | |
1102 | #ifdef CONFIG_MEMCG |
1103 | void mm_init_owner(struct mm_struct *mm, struct task_struct *p) |
1104 | { |
1105 | mm->owner = p; |
1106 | } |
1107 | #endif /* CONFIG_MEMCG */ |
1108 | |
1109 | /* |
1110 | * Initialize POSIX timer handling for a single task. |
1111 | */ |
1112 | static void posix_cpu_timers_init(struct task_struct *tsk) |
1113 | { |
1114 | tsk->cputime_expires.prof_exp = 0; |
1115 | tsk->cputime_expires.virt_exp = 0; |
1116 | tsk->cputime_expires.sched_exp = 0; |
1117 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); |
1118 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); |
1119 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); |
1120 | } |
1121 | |
1122 | static inline void |
1123 | init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) |
1124 | { |
1125 | task->pids[type].pid = pid; |
1126 | } |
1127 | |
1128 | /* |
1129 | * This creates a new process as a copy of the old one, |
1130 | * but does not actually start it yet. |
1131 | * |
1132 | * It copies the registers, and all the appropriate |
1133 | * parts of the process environment (as per the clone |
1134 | * flags). The actual kick-off is left to the caller. |
1135 | */ |
1136 | static struct task_struct *copy_process(unsigned long clone_flags, |
1137 | unsigned long stack_start, |
1138 | unsigned long stack_size, |
1139 | int __user *child_tidptr, |
1140 | struct pid *pid, |
1141 | int trace) |
1142 | { |
1143 | int retval; |
1144 | struct task_struct *p; |
1145 | |
1146 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) |
1147 | return ERR_PTR(-EINVAL); |
1148 | |
1149 | if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) |
1150 | return ERR_PTR(-EINVAL); |
1151 | |
1152 | /* |
1153 | * Thread groups must share signals as well, and detached threads |
1154 | * can only be started up within the thread group. |
1155 | */ |
1156 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) |
1157 | return ERR_PTR(-EINVAL); |
1158 | |
1159 | /* |
1160 | * Shared signal handlers imply shared VM. By way of the above, |
1161 | * thread groups also imply shared VM. Blocking this case allows |
1162 | * for various simplifications in other code. |
1163 | */ |
1164 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) |
1165 | return ERR_PTR(-EINVAL); |
1166 | |
1167 | /* |
1168 | * Siblings of global init remain as zombies on exit since they are |
1169 | * not reaped by their parent (swapper). To solve this and to avoid |
1170 | * multi-rooted process trees, prevent global and container-inits |
1171 | * from creating siblings. |
1172 | */ |
1173 | if ((clone_flags & CLONE_PARENT) && |
1174 | current->signal->flags & SIGNAL_UNKILLABLE) |
1175 | return ERR_PTR(-EINVAL); |
1176 | |
1177 | /* |
1178 | * If the new process will be in a different pid or user namespace |
1179 | * do not allow it to share a thread group or signal handlers or |
1180 | * parent with the forking task. |
1181 | */ |
1182 | if (clone_flags & CLONE_SIGHAND) { |
1183 | if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || |
1184 | (task_active_pid_ns(current) != |
1185 | current->nsproxy->pid_ns_for_children)) |
1186 | return ERR_PTR(-EINVAL); |
1187 | } |
1188 | |
1189 | retval = security_task_create(clone_flags); |
1190 | if (retval) |
1191 | goto fork_out; |
1192 | |
1193 | retval = -ENOMEM; |
1194 | p = dup_task_struct(current); |
1195 | if (!p) |
1196 | goto fork_out; |
1197 | |
1198 | ftrace_graph_init_task(p); |
1199 | get_seccomp_filter(p); |
1200 | |
1201 | rt_mutex_init_task(p); |
1202 | |
1203 | #ifdef CONFIG_PROVE_LOCKING |
1204 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); |
1205 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); |
1206 | #endif |
1207 | retval = -EAGAIN; |
1208 | if (atomic_read(&p->real_cred->user->processes) >= |
1209 | task_rlimit(p, RLIMIT_NPROC)) { |
1210 | if (p->real_cred->user != INIT_USER && |
1211 | !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) |
1212 | goto bad_fork_free; |
1213 | } |
1214 | current->flags &= ~PF_NPROC_EXCEEDED; |
1215 | |
1216 | retval = copy_creds(p, clone_flags); |
1217 | if (retval < 0) |
1218 | goto bad_fork_free; |
1219 | |
1220 | /* |
1221 | * If multiple threads are within copy_process(), then this check |
1222 | * triggers too late. This doesn't hurt, the check is only there |
1223 | * to stop root fork bombs. |
1224 | */ |
1225 | retval = -EAGAIN; |
1226 | if (nr_threads >= max_threads) |
1227 | goto bad_fork_cleanup_count; |
1228 | |
1229 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) |
1230 | goto bad_fork_cleanup_count; |
1231 | |
1232 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ |
1233 | p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); |
1234 | p->flags |= PF_FORKNOEXEC; |
1235 | INIT_LIST_HEAD(&p->children); |
1236 | INIT_LIST_HEAD(&p->sibling); |
1237 | rcu_copy_process(p); |
1238 | p->vfork_done = NULL; |
1239 | spin_lock_init(&p->alloc_lock); |
1240 | |
1241 | init_sigpending(&p->pending); |
1242 | |
1243 | p->utime = p->stime = p->gtime = 0; |
1244 | p->utimescaled = p->stimescaled = 0; |
1245 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
1246 | p->prev_cputime.utime = p->prev_cputime.stime = 0; |
1247 | #endif |
1248 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN |
1249 | seqlock_init(&p->vtime_seqlock); |
1250 | p->vtime_snap = 0; |
1251 | p->vtime_snap_whence = VTIME_SLEEPING; |
1252 | #endif |
1253 | |
1254 | #if defined(SPLIT_RSS_COUNTING) |
1255 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); |
1256 | #endif |
1257 | |
1258 | p->default_timer_slack_ns = current->timer_slack_ns; |
1259 | |
1260 | task_io_accounting_init(&p->ioac); |
1261 | acct_clear_integrals(p); |
1262 | |
1263 | posix_cpu_timers_init(p); |
1264 | |
1265 | do_posix_clock_monotonic_gettime(&p->start_time); |
1266 | p->real_start_time = p->start_time; |
1267 | monotonic_to_bootbased(&p->real_start_time); |
1268 | p->io_context = NULL; |
1269 | p->audit_context = NULL; |
1270 | if (clone_flags & CLONE_THREAD) |
1271 | threadgroup_change_begin(current); |
1272 | cgroup_fork(p); |
1273 | #ifdef CONFIG_NUMA |
1274 | p->mempolicy = mpol_dup(p->mempolicy); |
1275 | if (IS_ERR(p->mempolicy)) { |
1276 | retval = PTR_ERR(p->mempolicy); |
1277 | p->mempolicy = NULL; |
1278 | goto bad_fork_cleanup_threadgroup_lock; |
1279 | } |
1280 | #endif |
1281 | #ifdef CONFIG_CPUSETS |
1282 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE; |
1283 | p->cpuset_slab_spread_rotor = NUMA_NO_NODE; |
1284 | seqcount_init(&p->mems_allowed_seq); |
1285 | #endif |
1286 | #ifdef CONFIG_TRACE_IRQFLAGS |
1287 | p->irq_events = 0; |
1288 | p->hardirqs_enabled = 0; |
1289 | p->hardirq_enable_ip = 0; |
1290 | p->hardirq_enable_event = 0; |
1291 | p->hardirq_disable_ip = _THIS_IP_; |
1292 | p->hardirq_disable_event = 0; |
1293 | p->softirqs_enabled = 1; |
1294 | p->softirq_enable_ip = _THIS_IP_; |
1295 | p->softirq_enable_event = 0; |
1296 | p->softirq_disable_ip = 0; |
1297 | p->softirq_disable_event = 0; |
1298 | p->hardirq_context = 0; |
1299 | p->softirq_context = 0; |
1300 | #endif |
1301 | #ifdef CONFIG_LOCKDEP |
1302 | p->lockdep_depth = 0; /* no locks held yet */ |
1303 | p->curr_chain_key = 0; |
1304 | p->lockdep_recursion = 0; |
1305 | #endif |
1306 | |
1307 | #ifdef CONFIG_DEBUG_MUTEXES |
1308 | p->blocked_on = NULL; /* not blocked yet */ |
1309 | #endif |
1310 | #ifdef CONFIG_MEMCG |
1311 | p->memcg_batch.do_batch = 0; |
1312 | p->memcg_batch.memcg = NULL; |
1313 | #endif |
1314 | #ifdef CONFIG_BCACHE |
1315 | p->sequential_io = 0; |
1316 | p->sequential_io_avg = 0; |
1317 | #endif |
1318 | |
1319 | /* Perform scheduler related setup. Assign this task to a CPU. */ |
1320 | retval = sched_fork(clone_flags, p); |
1321 | if (retval) |
1322 | goto bad_fork_cleanup_policy; |
1323 | |
1324 | retval = perf_event_init_task(p); |
1325 | if (retval) |
1326 | goto bad_fork_cleanup_policy; |
1327 | retval = audit_alloc(p); |
1328 | if (retval) |
1329 | goto bad_fork_cleanup_policy; |
1330 | /* copy all the process information */ |
1331 | retval = copy_semundo(clone_flags, p); |
1332 | if (retval) |
1333 | goto bad_fork_cleanup_audit; |
1334 | retval = copy_files(clone_flags, p); |
1335 | if (retval) |
1336 | goto bad_fork_cleanup_semundo; |
1337 | retval = copy_fs(clone_flags, p); |
1338 | if (retval) |
1339 | goto bad_fork_cleanup_files; |
1340 | retval = copy_sighand(clone_flags, p); |
1341 | if (retval) |
1342 | goto bad_fork_cleanup_fs; |
1343 | retval = copy_signal(clone_flags, p); |
1344 | if (retval) |
1345 | goto bad_fork_cleanup_sighand; |
1346 | retval = copy_mm(clone_flags, p); |
1347 | if (retval) |
1348 | goto bad_fork_cleanup_signal; |
1349 | retval = copy_namespaces(clone_flags, p); |
1350 | if (retval) |
1351 | goto bad_fork_cleanup_mm; |
1352 | retval = copy_io(clone_flags, p); |
1353 | if (retval) |
1354 | goto bad_fork_cleanup_namespaces; |
1355 | retval = copy_thread(clone_flags, stack_start, stack_size, p); |
1356 | if (retval) |
1357 | goto bad_fork_cleanup_io; |
1358 | |
1359 | if (pid != &init_struct_pid) { |
1360 | retval = -ENOMEM; |
1361 | pid = alloc_pid(p->nsproxy->pid_ns_for_children); |
1362 | if (!pid) |
1363 | goto bad_fork_cleanup_io; |
1364 | } |
1365 | |
1366 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; |
1367 | /* |
1368 | * Clear TID on mm_release()? |
1369 | */ |
1370 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; |
1371 | #ifdef CONFIG_BLOCK |
1372 | p->plug = NULL; |
1373 | #endif |
1374 | #ifdef CONFIG_FUTEX |
1375 | p->robust_list = NULL; |
1376 | #ifdef CONFIG_COMPAT |
1377 | p->compat_robust_list = NULL; |
1378 | #endif |
1379 | INIT_LIST_HEAD(&p->pi_state_list); |
1380 | p->pi_state_cache = NULL; |
1381 | #endif |
1382 | /* |
1383 | * sigaltstack should be cleared when sharing the same VM |
1384 | */ |
1385 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) |
1386 | p->sas_ss_sp = p->sas_ss_size = 0; |
1387 | |
1388 | /* |
1389 | * Syscall tracing and stepping should be turned off in the |
1390 | * child regardless of CLONE_PTRACE. |
1391 | */ |
1392 | user_disable_single_step(p); |
1393 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); |
1394 | #ifdef TIF_SYSCALL_EMU |
1395 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); |
1396 | #endif |
1397 | clear_all_latency_tracing(p); |
1398 | |
1399 | /* ok, now we should be set up.. */ |
1400 | p->pid = pid_nr(pid); |
1401 | if (clone_flags & CLONE_THREAD) { |
1402 | p->exit_signal = -1; |
1403 | p->group_leader = current->group_leader; |
1404 | p->tgid = current->tgid; |
1405 | } else { |
1406 | if (clone_flags & CLONE_PARENT) |
1407 | p->exit_signal = current->group_leader->exit_signal; |
1408 | else |
1409 | p->exit_signal = (clone_flags & CSIGNAL); |
1410 | p->group_leader = p; |
1411 | p->tgid = p->pid; |
1412 | } |
1413 | |
1414 | p->nr_dirtied = 0; |
1415 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); |
1416 | p->dirty_paused_when = 0; |
1417 | |
1418 | p->pdeath_signal = 0; |
1419 | INIT_LIST_HEAD(&p->thread_group); |
1420 | p->task_works = NULL; |
1421 | |
1422 | /* |
1423 | * Make it visible to the rest of the system, but dont wake it up yet. |
1424 | * Need tasklist lock for parent etc handling! |
1425 | */ |
1426 | write_lock_irq(&tasklist_lock); |
1427 | |
1428 | /* CLONE_PARENT re-uses the old parent */ |
1429 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { |
1430 | p->real_parent = current->real_parent; |
1431 | p->parent_exec_id = current->parent_exec_id; |
1432 | } else { |
1433 | p->real_parent = current; |
1434 | p->parent_exec_id = current->self_exec_id; |
1435 | } |
1436 | |
1437 | spin_lock(¤t->sighand->siglock); |
1438 | |
1439 | /* |
1440 | * Process group and session signals need to be delivered to just the |
1441 | * parent before the fork or both the parent and the child after the |
1442 | * fork. Restart if a signal comes in before we add the new process to |
1443 | * it's process group. |
1444 | * A fatal signal pending means that current will exit, so the new |
1445 | * thread can't slip out of an OOM kill (or normal SIGKILL). |
1446 | */ |
1447 | recalc_sigpending(); |
1448 | if (signal_pending(current)) { |
1449 | spin_unlock(¤t->sighand->siglock); |
1450 | write_unlock_irq(&tasklist_lock); |
1451 | retval = -ERESTARTNOINTR; |
1452 | goto bad_fork_free_pid; |
1453 | } |
1454 | |
1455 | if (likely(p->pid)) { |
1456 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); |
1457 | |
1458 | init_task_pid(p, PIDTYPE_PID, pid); |
1459 | if (thread_group_leader(p)) { |
1460 | init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); |
1461 | init_task_pid(p, PIDTYPE_SID, task_session(current)); |
1462 | |
1463 | if (is_child_reaper(pid)) { |
1464 | ns_of_pid(pid)->child_reaper = p; |
1465 | p->signal->flags |= SIGNAL_UNKILLABLE; |
1466 | } |
1467 | |
1468 | p->signal->leader_pid = pid; |
1469 | p->signal->tty = tty_kref_get(current->signal->tty); |
1470 | list_add_tail(&p->sibling, &p->real_parent->children); |
1471 | list_add_tail_rcu(&p->tasks, &init_task.tasks); |
1472 | attach_pid(p, PIDTYPE_PGID); |
1473 | attach_pid(p, PIDTYPE_SID); |
1474 | __this_cpu_inc(process_counts); |
1475 | } else { |
1476 | current->signal->nr_threads++; |
1477 | atomic_inc(¤t->signal->live); |
1478 | atomic_inc(¤t->signal->sigcnt); |
1479 | list_add_tail_rcu(&p->thread_group, |
1480 | &p->group_leader->thread_group); |
1481 | list_add_tail_rcu(&p->thread_node, |
1482 | &p->signal->thread_head); |
1483 | } |
1484 | attach_pid(p, PIDTYPE_PID); |
1485 | nr_threads++; |
1486 | } |
1487 | |
1488 | total_forks++; |
1489 | spin_unlock(¤t->sighand->siglock); |
1490 | syscall_tracepoint_update(p); |
1491 | write_unlock_irq(&tasklist_lock); |
1492 | |
1493 | proc_fork_connector(p); |
1494 | cgroup_post_fork(p); |
1495 | if (clone_flags & CLONE_THREAD) |
1496 | threadgroup_change_end(current); |
1497 | perf_event_fork(p); |
1498 | |
1499 | trace_task_newtask(p, clone_flags); |
1500 | uprobe_copy_process(p, clone_flags); |
1501 | |
1502 | return p; |
1503 | |
1504 | bad_fork_free_pid: |
1505 | if (pid != &init_struct_pid) |
1506 | free_pid(pid); |
1507 | bad_fork_cleanup_io: |
1508 | if (p->io_context) |
1509 | exit_io_context(p); |
1510 | bad_fork_cleanup_namespaces: |
1511 | exit_task_namespaces(p); |
1512 | bad_fork_cleanup_mm: |
1513 | if (p->mm) |
1514 | mmput(p->mm); |
1515 | bad_fork_cleanup_signal: |
1516 | if (!(clone_flags & CLONE_THREAD)) |
1517 | free_signal_struct(p->signal); |
1518 | bad_fork_cleanup_sighand: |
1519 | __cleanup_sighand(p->sighand); |
1520 | bad_fork_cleanup_fs: |
1521 | exit_fs(p); /* blocking */ |
1522 | bad_fork_cleanup_files: |
1523 | exit_files(p); /* blocking */ |
1524 | bad_fork_cleanup_semundo: |
1525 | exit_sem(p); |
1526 | bad_fork_cleanup_audit: |
1527 | audit_free(p); |
1528 | bad_fork_cleanup_policy: |
1529 | perf_event_free_task(p); |
1530 | #ifdef CONFIG_NUMA |
1531 | mpol_put(p->mempolicy); |
1532 | bad_fork_cleanup_threadgroup_lock: |
1533 | #endif |
1534 | if (clone_flags & CLONE_THREAD) |
1535 | threadgroup_change_end(current); |
1536 | delayacct_tsk_free(p); |
1537 | module_put(task_thread_info(p)->exec_domain->module); |
1538 | bad_fork_cleanup_count: |
1539 | atomic_dec(&p->cred->user->processes); |
1540 | exit_creds(p); |
1541 | bad_fork_free: |
1542 | free_task(p); |
1543 | fork_out: |
1544 | return ERR_PTR(retval); |
1545 | } |
1546 | |
1547 | static inline void init_idle_pids(struct pid_link *links) |
1548 | { |
1549 | enum pid_type type; |
1550 | |
1551 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { |
1552 | INIT_HLIST_NODE(&links[type].node); /* not really needed */ |
1553 | links[type].pid = &init_struct_pid; |
1554 | } |
1555 | } |
1556 | |
1557 | struct task_struct *fork_idle(int cpu) |
1558 | { |
1559 | struct task_struct *task; |
1560 | task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0); |
1561 | if (!IS_ERR(task)) { |
1562 | init_idle_pids(task->pids); |
1563 | init_idle(task, cpu); |
1564 | } |
1565 | |
1566 | return task; |
1567 | } |
1568 | |
1569 | /* |
1570 | * Ok, this is the main fork-routine. |
1571 | * |
1572 | * It copies the process, and if successful kick-starts |
1573 | * it and waits for it to finish using the VM if required. |
1574 | */ |
1575 | long do_fork(unsigned long clone_flags, |
1576 | unsigned long stack_start, |
1577 | unsigned long stack_size, |
1578 | int __user *parent_tidptr, |
1579 | int __user *child_tidptr) |
1580 | { |
1581 | struct task_struct *p; |
1582 | int trace = 0; |
1583 | long nr; |
1584 | |
1585 | /* |
1586 | * Determine whether and which event to report to ptracer. When |
1587 | * called from kernel_thread or CLONE_UNTRACED is explicitly |
1588 | * requested, no event is reported; otherwise, report if the event |
1589 | * for the type of forking is enabled. |
1590 | */ |
1591 | if (!(clone_flags & CLONE_UNTRACED)) { |
1592 | if (clone_flags & CLONE_VFORK) |
1593 | trace = PTRACE_EVENT_VFORK; |
1594 | else if ((clone_flags & CSIGNAL) != SIGCHLD) |
1595 | trace = PTRACE_EVENT_CLONE; |
1596 | else |
1597 | trace = PTRACE_EVENT_FORK; |
1598 | |
1599 | if (likely(!ptrace_event_enabled(current, trace))) |
1600 | trace = 0; |
1601 | } |
1602 | |
1603 | p = copy_process(clone_flags, stack_start, stack_size, |
1604 | child_tidptr, NULL, trace); |
1605 | /* |
1606 | * Do this prior waking up the new thread - the thread pointer |
1607 | * might get invalid after that point, if the thread exits quickly. |
1608 | */ |
1609 | if (!IS_ERR(p)) { |
1610 | struct completion vfork; |
1611 | struct pid *pid; |
1612 | |
1613 | trace_sched_process_fork(current, p); |
1614 | |
1615 | pid = get_task_pid(p, PIDTYPE_PID); |
1616 | nr = pid_vnr(pid); |
1617 | |
1618 | if (clone_flags & CLONE_PARENT_SETTID) |
1619 | put_user(nr, parent_tidptr); |
1620 | |
1621 | if (clone_flags & CLONE_VFORK) { |
1622 | p->vfork_done = &vfork; |
1623 | init_completion(&vfork); |
1624 | get_task_struct(p); |
1625 | } |
1626 | |
1627 | wake_up_new_task(p); |
1628 | |
1629 | /* forking complete and child started to run, tell ptracer */ |
1630 | if (unlikely(trace)) |
1631 | ptrace_event_pid(trace, pid); |
1632 | |
1633 | if (clone_flags & CLONE_VFORK) { |
1634 | if (!wait_for_vfork_done(p, &vfork)) |
1635 | ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); |
1636 | } |
1637 | |
1638 | put_pid(pid); |
1639 | } else { |
1640 | nr = PTR_ERR(p); |
1641 | } |
1642 | return nr; |
1643 | } |
1644 | |
1645 | /* |
1646 | * Create a kernel thread. |
1647 | */ |
1648 | pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) |
1649 | { |
1650 | return do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, |
1651 | (unsigned long)arg, NULL, NULL); |
1652 | } |
1653 | |
1654 | #ifdef __ARCH_WANT_SYS_FORK |
1655 | SYSCALL_DEFINE0(fork) |
1656 | { |
1657 | #ifdef CONFIG_MMU |
1658 | return do_fork(SIGCHLD, 0, 0, NULL, NULL); |
1659 | #else |
1660 | /* can not support in nommu mode */ |
1661 | return -EINVAL; |
1662 | #endif |
1663 | } |
1664 | #endif |
1665 | |
1666 | #ifdef __ARCH_WANT_SYS_VFORK |
1667 | SYSCALL_DEFINE0(vfork) |
1668 | { |
1669 | return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, |
1670 | 0, NULL, NULL); |
1671 | } |
1672 | #endif |
1673 | |
1674 | #ifdef __ARCH_WANT_SYS_CLONE |
1675 | #ifdef CONFIG_CLONE_BACKWARDS |
1676 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, |
1677 | int __user *, parent_tidptr, |
1678 | int, tls_val, |
1679 | int __user *, child_tidptr) |
1680 | #elif defined(CONFIG_CLONE_BACKWARDS2) |
1681 | SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, |
1682 | int __user *, parent_tidptr, |
1683 | int __user *, child_tidptr, |
1684 | int, tls_val) |
1685 | #elif defined(CONFIG_CLONE_BACKWARDS3) |
1686 | SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, |
1687 | int, stack_size, |
1688 | int __user *, parent_tidptr, |
1689 | int __user *, child_tidptr, |
1690 | int, tls_val) |
1691 | #else |
1692 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, |
1693 | int __user *, parent_tidptr, |
1694 | int __user *, child_tidptr, |
1695 | int, tls_val) |
1696 | #endif |
1697 | { |
1698 | return do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr); |
1699 | } |
1700 | #endif |
1701 | |
1702 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN |
1703 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 |
1704 | #endif |
1705 | |
1706 | static void sighand_ctor(void *data) |
1707 | { |
1708 | struct sighand_struct *sighand = data; |
1709 | |
1710 | spin_lock_init(&sighand->siglock); |
1711 | init_waitqueue_head(&sighand->signalfd_wqh); |
1712 | } |
1713 | |
1714 | void __init proc_caches_init(void) |
1715 | { |
1716 | sighand_cachep = kmem_cache_create("sighand_cache", |
1717 | sizeof(struct sighand_struct), 0, |
1718 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| |
1719 | SLAB_NOTRACK, sighand_ctor); |
1720 | signal_cachep = kmem_cache_create("signal_cache", |
1721 | sizeof(struct signal_struct), 0, |
1722 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1723 | files_cachep = kmem_cache_create("files_cache", |
1724 | sizeof(struct files_struct), 0, |
1725 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1726 | fs_cachep = kmem_cache_create("fs_cache", |
1727 | sizeof(struct fs_struct), 0, |
1728 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1729 | /* |
1730 | * FIXME! The "sizeof(struct mm_struct)" currently includes the |
1731 | * whole struct cpumask for the OFFSTACK case. We could change |
1732 | * this to *only* allocate as much of it as required by the |
1733 | * maximum number of CPU's we can ever have. The cpumask_allocation |
1734 | * is at the end of the structure, exactly for that reason. |
1735 | */ |
1736 | mm_cachep = kmem_cache_create("mm_struct", |
1737 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, |
1738 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1739 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); |
1740 | mmap_init(); |
1741 | nsproxy_cache_init(); |
1742 | } |
1743 | |
1744 | /* |
1745 | * Check constraints on flags passed to the unshare system call. |
1746 | */ |
1747 | static int check_unshare_flags(unsigned long unshare_flags) |
1748 | { |
1749 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| |
1750 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| |
1751 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| |
1752 | CLONE_NEWUSER|CLONE_NEWPID)) |
1753 | return -EINVAL; |
1754 | /* |
1755 | * Not implemented, but pretend it works if there is nothing to |
1756 | * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND |
1757 | * needs to unshare vm. |
1758 | */ |
1759 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { |
1760 | /* FIXME: get_task_mm() increments ->mm_users */ |
1761 | if (atomic_read(¤t->mm->mm_users) > 1) |
1762 | return -EINVAL; |
1763 | } |
1764 | |
1765 | return 0; |
1766 | } |
1767 | |
1768 | /* |
1769 | * Unshare the filesystem structure if it is being shared |
1770 | */ |
1771 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) |
1772 | { |
1773 | struct fs_struct *fs = current->fs; |
1774 | |
1775 | if (!(unshare_flags & CLONE_FS) || !fs) |
1776 | return 0; |
1777 | |
1778 | /* don't need lock here; in the worst case we'll do useless copy */ |
1779 | if (fs->users == 1) |
1780 | return 0; |
1781 | |
1782 | *new_fsp = copy_fs_struct(fs); |
1783 | if (!*new_fsp) |
1784 | return -ENOMEM; |
1785 | |
1786 | return 0; |
1787 | } |
1788 | |
1789 | /* |
1790 | * Unshare file descriptor table if it is being shared |
1791 | */ |
1792 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) |
1793 | { |
1794 | struct files_struct *fd = current->files; |
1795 | int error = 0; |
1796 | |
1797 | if ((unshare_flags & CLONE_FILES) && |
1798 | (fd && atomic_read(&fd->count) > 1)) { |
1799 | *new_fdp = dup_fd(fd, &error); |
1800 | if (!*new_fdp) |
1801 | return error; |
1802 | } |
1803 | |
1804 | return 0; |
1805 | } |
1806 | |
1807 | /* |
1808 | * unshare allows a process to 'unshare' part of the process |
1809 | * context which was originally shared using clone. copy_* |
1810 | * functions used by do_fork() cannot be used here directly |
1811 | * because they modify an inactive task_struct that is being |
1812 | * constructed. Here we are modifying the current, active, |
1813 | * task_struct. |
1814 | */ |
1815 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) |
1816 | { |
1817 | struct fs_struct *fs, *new_fs = NULL; |
1818 | struct files_struct *fd, *new_fd = NULL; |
1819 | struct cred *new_cred = NULL; |
1820 | struct nsproxy *new_nsproxy = NULL; |
1821 | int do_sysvsem = 0; |
1822 | int err; |
1823 | |
1824 | /* |
1825 | * If unsharing a user namespace must also unshare the thread. |
1826 | */ |
1827 | if (unshare_flags & CLONE_NEWUSER) |
1828 | unshare_flags |= CLONE_THREAD | CLONE_FS; |
1829 | /* |
1830 | * If unsharing a thread from a thread group, must also unshare vm. |
1831 | */ |
1832 | if (unshare_flags & CLONE_THREAD) |
1833 | unshare_flags |= CLONE_VM; |
1834 | /* |
1835 | * If unsharing vm, must also unshare signal handlers. |
1836 | */ |
1837 | if (unshare_flags & CLONE_VM) |
1838 | unshare_flags |= CLONE_SIGHAND; |
1839 | /* |
1840 | * If unsharing namespace, must also unshare filesystem information. |
1841 | */ |
1842 | if (unshare_flags & CLONE_NEWNS) |
1843 | unshare_flags |= CLONE_FS; |
1844 | |
1845 | err = check_unshare_flags(unshare_flags); |
1846 | if (err) |
1847 | goto bad_unshare_out; |
1848 | /* |
1849 | * CLONE_NEWIPC must also detach from the undolist: after switching |
1850 | * to a new ipc namespace, the semaphore arrays from the old |
1851 | * namespace are unreachable. |
1852 | */ |
1853 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) |
1854 | do_sysvsem = 1; |
1855 | err = unshare_fs(unshare_flags, &new_fs); |
1856 | if (err) |
1857 | goto bad_unshare_out; |
1858 | err = unshare_fd(unshare_flags, &new_fd); |
1859 | if (err) |
1860 | goto bad_unshare_cleanup_fs; |
1861 | err = unshare_userns(unshare_flags, &new_cred); |
1862 | if (err) |
1863 | goto bad_unshare_cleanup_fd; |
1864 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, |
1865 | new_cred, new_fs); |
1866 | if (err) |
1867 | goto bad_unshare_cleanup_cred; |
1868 | |
1869 | if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { |
1870 | if (do_sysvsem) { |
1871 | /* |
1872 | * CLONE_SYSVSEM is equivalent to sys_exit(). |
1873 | */ |
1874 | exit_sem(current); |
1875 | } |
1876 | |
1877 | if (new_nsproxy) |
1878 | switch_task_namespaces(current, new_nsproxy); |
1879 | |
1880 | task_lock(current); |
1881 | |
1882 | if (new_fs) { |
1883 | fs = current->fs; |
1884 | spin_lock(&fs->lock); |
1885 | current->fs = new_fs; |
1886 | if (--fs->users) |
1887 | new_fs = NULL; |
1888 | else |
1889 | new_fs = fs; |
1890 | spin_unlock(&fs->lock); |
1891 | } |
1892 | |
1893 | if (new_fd) { |
1894 | fd = current->files; |
1895 | current->files = new_fd; |
1896 | new_fd = fd; |
1897 | } |
1898 | |
1899 | task_unlock(current); |
1900 | |
1901 | if (new_cred) { |
1902 | /* Install the new user namespace */ |
1903 | commit_creds(new_cred); |
1904 | new_cred = NULL; |
1905 | } |
1906 | } |
1907 | |
1908 | bad_unshare_cleanup_cred: |
1909 | if (new_cred) |
1910 | put_cred(new_cred); |
1911 | bad_unshare_cleanup_fd: |
1912 | if (new_fd) |
1913 | put_files_struct(new_fd); |
1914 | |
1915 | bad_unshare_cleanup_fs: |
1916 | if (new_fs) |
1917 | free_fs_struct(new_fs); |
1918 | |
1919 | bad_unshare_out: |
1920 | return err; |
1921 | } |
1922 | |
1923 | /* |
1924 | * Helper to unshare the files of the current task. |
1925 | * We don't want to expose copy_files internals to |
1926 | * the exec layer of the kernel. |
1927 | */ |
1928 | |
1929 | int unshare_files(struct files_struct **displaced) |
1930 | { |
1931 | struct task_struct *task = current; |
1932 | struct files_struct *copy = NULL; |
1933 | int error; |
1934 | |
1935 | error = unshare_fd(CLONE_FILES, ©); |
1936 | if (error || !copy) { |
1937 | *displaced = NULL; |
1938 | return error; |
1939 | } |
1940 | *displaced = task->files; |
1941 | task_lock(task); |
1942 | task->files = copy; |
1943 | task_unlock(task); |
1944 | return 0; |
1945 | } |
1946 |
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javiroman/ks7010
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9