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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 | void set_task_stack_end_magic(struct task_struct *tsk) | |
298 | { | |
299 | unsigned long *stackend; | |
300 | ||
301 | stackend = end_of_stack(tsk); | |
302 | *stackend = STACK_END_MAGIC; /* for overflow detection */ | |
303 | } | |
304 | ||
305 | static struct task_struct *dup_task_struct(struct task_struct *orig) | |
306 | { | |
307 | struct task_struct *tsk; | |
308 | struct thread_info *ti; | |
309 | int node = tsk_fork_get_node(orig); | |
310 | int err; | |
311 | ||
312 | tsk = alloc_task_struct_node(node); | |
313 | if (!tsk) | |
314 | return NULL; | |
315 | ||
316 | ti = alloc_thread_info_node(tsk, node); | |
317 | if (!ti) | |
318 | goto free_tsk; | |
319 | ||
320 | err = arch_dup_task_struct(tsk, orig); | |
321 | if (err) | |
322 | goto free_ti; | |
323 | ||
324 | tsk->stack = ti; | |
325 | #ifdef CONFIG_SECCOMP | |
326 | /* | |
327 | * We must handle setting up seccomp filters once we're under | |
328 | * the sighand lock in case orig has changed between now and | |
329 | * then. Until then, filter must be NULL to avoid messing up | |
330 | * the usage counts on the error path calling free_task. | |
331 | */ | |
332 | tsk->seccomp.filter = NULL; | |
333 | #endif | |
334 | ||
335 | setup_thread_stack(tsk, orig); | |
336 | clear_user_return_notifier(tsk); | |
337 | clear_tsk_need_resched(tsk); | |
338 | set_task_stack_end_magic(tsk); | |
339 | ||
340 | #ifdef CONFIG_CC_STACKPROTECTOR | |
341 | tsk->stack_canary = get_random_int(); | |
342 | #endif | |
343 | ||
344 | /* | |
345 | * One for us, one for whoever does the "release_task()" (usually | |
346 | * parent) | |
347 | */ | |
348 | atomic_set(&tsk->usage, 2); | |
349 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
350 | tsk->btrace_seq = 0; | |
351 | #endif | |
352 | tsk->splice_pipe = NULL; | |
353 | tsk->task_frag.page = NULL; | |
354 | ||
355 | account_kernel_stack(ti, 1); | |
356 | ||
357 | return tsk; | |
358 | ||
359 | free_ti: | |
360 | free_thread_info(ti); | |
361 | free_tsk: | |
362 | free_task_struct(tsk); | |
363 | return NULL; | |
364 | } | |
365 | ||
366 | #ifdef CONFIG_MMU | |
367 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) | |
368 | { | |
369 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; | |
370 | struct rb_node **rb_link, *rb_parent; | |
371 | int retval; | |
372 | unsigned long charge; | |
373 | ||
374 | uprobe_start_dup_mmap(); | |
375 | down_write(&oldmm->mmap_sem); | |
376 | flush_cache_dup_mm(oldmm); | |
377 | uprobe_dup_mmap(oldmm, mm); | |
378 | /* | |
379 | * Not linked in yet - no deadlock potential: | |
380 | */ | |
381 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); | |
382 | ||
383 | mm->total_vm = oldmm->total_vm; | |
384 | mm->shared_vm = oldmm->shared_vm; | |
385 | mm->exec_vm = oldmm->exec_vm; | |
386 | mm->stack_vm = oldmm->stack_vm; | |
387 | ||
388 | rb_link = &mm->mm_rb.rb_node; | |
389 | rb_parent = NULL; | |
390 | pprev = &mm->mmap; | |
391 | retval = ksm_fork(mm, oldmm); | |
392 | if (retval) | |
393 | goto out; | |
394 | retval = khugepaged_fork(mm, oldmm); | |
395 | if (retval) | |
396 | goto out; | |
397 | ||
398 | prev = NULL; | |
399 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { | |
400 | struct file *file; | |
401 | ||
402 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
403 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, | |
404 | -vma_pages(mpnt)); | |
405 | continue; | |
406 | } | |
407 | charge = 0; | |
408 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
409 | unsigned long len = vma_pages(mpnt); | |
410 | ||
411 | if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ | |
412 | goto fail_nomem; | |
413 | charge = len; | |
414 | } | |
415 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
416 | if (!tmp) | |
417 | goto fail_nomem; | |
418 | *tmp = *mpnt; | |
419 | INIT_LIST_HEAD(&tmp->anon_vma_chain); | |
420 | retval = vma_dup_policy(mpnt, tmp); | |
421 | if (retval) | |
422 | goto fail_nomem_policy; | |
423 | tmp->vm_mm = mm; | |
424 | if (anon_vma_fork(tmp, mpnt)) | |
425 | goto fail_nomem_anon_vma_fork; | |
426 | tmp->vm_flags &= ~VM_LOCKED; | |
427 | tmp->vm_next = tmp->vm_prev = NULL; | |
428 | file = tmp->vm_file; | |
429 | if (file) { | |
430 | struct inode *inode = file_inode(file); | |
431 | struct address_space *mapping = file->f_mapping; | |
432 | ||
433 | get_file(file); | |
434 | if (tmp->vm_flags & VM_DENYWRITE) | |
435 | atomic_dec(&inode->i_writecount); | |
436 | i_mmap_lock_write(mapping); | |
437 | if (tmp->vm_flags & VM_SHARED) | |
438 | atomic_inc(&mapping->i_mmap_writable); | |
439 | flush_dcache_mmap_lock(mapping); | |
440 | /* insert tmp into the share list, just after mpnt */ | |
441 | vma_interval_tree_insert_after(tmp, mpnt, | |
442 | &mapping->i_mmap); | |
443 | flush_dcache_mmap_unlock(mapping); | |
444 | i_mmap_unlock_write(mapping); | |
445 | } | |
446 | ||
447 | /* | |
448 | * Clear hugetlb-related page reserves for children. This only | |
449 | * affects MAP_PRIVATE mappings. Faults generated by the child | |
450 | * are not guaranteed to succeed, even if read-only | |
451 | */ | |
452 | if (is_vm_hugetlb_page(tmp)) | |
453 | reset_vma_resv_huge_pages(tmp); | |
454 | ||
455 | /* | |
456 | * Link in the new vma and copy the page table entries. | |
457 | */ | |
458 | *pprev = tmp; | |
459 | pprev = &tmp->vm_next; | |
460 | tmp->vm_prev = prev; | |
461 | prev = tmp; | |
462 | ||
463 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
464 | rb_link = &tmp->vm_rb.rb_right; | |
465 | rb_parent = &tmp->vm_rb; | |
466 | ||
467 | mm->map_count++; | |
468 | retval = copy_page_range(mm, oldmm, mpnt); | |
469 | ||
470 | if (tmp->vm_ops && tmp->vm_ops->open) | |
471 | tmp->vm_ops->open(tmp); | |
472 | ||
473 | if (retval) | |
474 | goto out; | |
475 | } | |
476 | /* a new mm has just been created */ | |
477 | arch_dup_mmap(oldmm, mm); | |
478 | retval = 0; | |
479 | out: | |
480 | up_write(&mm->mmap_sem); | |
481 | flush_tlb_mm(oldmm); | |
482 | up_write(&oldmm->mmap_sem); | |
483 | uprobe_end_dup_mmap(); | |
484 | return retval; | |
485 | fail_nomem_anon_vma_fork: | |
486 | mpol_put(vma_policy(tmp)); | |
487 | fail_nomem_policy: | |
488 | kmem_cache_free(vm_area_cachep, tmp); | |
489 | fail_nomem: | |
490 | retval = -ENOMEM; | |
491 | vm_unacct_memory(charge); | |
492 | goto out; | |
493 | } | |
494 | ||
495 | static inline int mm_alloc_pgd(struct mm_struct *mm) | |
496 | { | |
497 | mm->pgd = pgd_alloc(mm); | |
498 | if (unlikely(!mm->pgd)) | |
499 | return -ENOMEM; | |
500 | return 0; | |
501 | } | |
502 | ||
503 | static inline void mm_free_pgd(struct mm_struct *mm) | |
504 | { | |
505 | pgd_free(mm, mm->pgd); | |
506 | } | |
507 | #else | |
508 | #define dup_mmap(mm, oldmm) (0) | |
509 | #define mm_alloc_pgd(mm) (0) | |
510 | #define mm_free_pgd(mm) | |
511 | #endif /* CONFIG_MMU */ | |
512 | ||
513 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
514 | ||
515 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) | |
516 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
517 | ||
518 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; | |
519 | ||
520 | static int __init coredump_filter_setup(char *s) | |
521 | { | |
522 | default_dump_filter = | |
523 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & | |
524 | MMF_DUMP_FILTER_MASK; | |
525 | return 1; | |
526 | } | |
527 | ||
528 | __setup("coredump_filter=", coredump_filter_setup); | |
529 | ||
530 | #include <linux/init_task.h> | |
531 | ||
532 | static void mm_init_aio(struct mm_struct *mm) | |
533 | { | |
534 | #ifdef CONFIG_AIO | |
535 | spin_lock_init(&mm->ioctx_lock); | |
536 | mm->ioctx_table = NULL; | |
537 | #endif | |
538 | } | |
539 | ||
540 | static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) | |
541 | { | |
542 | #ifdef CONFIG_MEMCG | |
543 | mm->owner = p; | |
544 | #endif | |
545 | } | |
546 | ||
547 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) | |
548 | { | |
549 | mm->mmap = NULL; | |
550 | mm->mm_rb = RB_ROOT; | |
551 | mm->vmacache_seqnum = 0; | |
552 | atomic_set(&mm->mm_users, 1); | |
553 | atomic_set(&mm->mm_count, 1); | |
554 | init_rwsem(&mm->mmap_sem); | |
555 | INIT_LIST_HEAD(&mm->mmlist); | |
556 | mm->core_state = NULL; | |
557 | atomic_long_set(&mm->nr_ptes, 0); | |
558 | mm_nr_pmds_init(mm); | |
559 | mm->map_count = 0; | |
560 | mm->locked_vm = 0; | |
561 | mm->pinned_vm = 0; | |
562 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); | |
563 | spin_lock_init(&mm->page_table_lock); | |
564 | mm_init_cpumask(mm); | |
565 | mm_init_aio(mm); | |
566 | mm_init_owner(mm, p); | |
567 | mmu_notifier_mm_init(mm); | |
568 | clear_tlb_flush_pending(mm); | |
569 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS | |
570 | mm->pmd_huge_pte = NULL; | |
571 | #endif | |
572 | ||
573 | if (current->mm) { | |
574 | mm->flags = current->mm->flags & MMF_INIT_MASK; | |
575 | mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; | |
576 | } else { | |
577 | mm->flags = default_dump_filter; | |
578 | mm->def_flags = 0; | |
579 | } | |
580 | ||
581 | if (mm_alloc_pgd(mm)) | |
582 | goto fail_nopgd; | |
583 | ||
584 | if (init_new_context(p, mm)) | |
585 | goto fail_nocontext; | |
586 | ||
587 | return mm; | |
588 | ||
589 | fail_nocontext: | |
590 | mm_free_pgd(mm); | |
591 | fail_nopgd: | |
592 | free_mm(mm); | |
593 | return NULL; | |
594 | } | |
595 | ||
596 | static void check_mm(struct mm_struct *mm) | |
597 | { | |
598 | int i; | |
599 | ||
600 | for (i = 0; i < NR_MM_COUNTERS; i++) { | |
601 | long x = atomic_long_read(&mm->rss_stat.count[i]); | |
602 | ||
603 | if (unlikely(x)) | |
604 | printk(KERN_ALERT "BUG: Bad rss-counter state " | |
605 | "mm:%p idx:%d val:%ld\n", mm, i, x); | |
606 | } | |
607 | ||
608 | if (atomic_long_read(&mm->nr_ptes)) | |
609 | pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n", | |
610 | atomic_long_read(&mm->nr_ptes)); | |
611 | if (mm_nr_pmds(mm)) | |
612 | pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n", | |
613 | mm_nr_pmds(mm)); | |
614 | ||
615 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS | |
616 | VM_BUG_ON_MM(mm->pmd_huge_pte, mm); | |
617 | #endif | |
618 | } | |
619 | ||
620 | /* | |
621 | * Allocate and initialize an mm_struct. | |
622 | */ | |
623 | struct mm_struct *mm_alloc(void) | |
624 | { | |
625 | struct mm_struct *mm; | |
626 | ||
627 | mm = allocate_mm(); | |
628 | if (!mm) | |
629 | return NULL; | |
630 | ||
631 | memset(mm, 0, sizeof(*mm)); | |
632 | return mm_init(mm, current); | |
633 | } | |
634 | ||
635 | /* | |
636 | * Called when the last reference to the mm | |
637 | * is dropped: either by a lazy thread or by | |
638 | * mmput. Free the page directory and the mm. | |
639 | */ | |
640 | void __mmdrop(struct mm_struct *mm) | |
641 | { | |
642 | BUG_ON(mm == &init_mm); | |
643 | mm_free_pgd(mm); | |
644 | destroy_context(mm); | |
645 | mmu_notifier_mm_destroy(mm); | |
646 | check_mm(mm); | |
647 | free_mm(mm); | |
648 | } | |
649 | EXPORT_SYMBOL_GPL(__mmdrop); | |
650 | ||
651 | /* | |
652 | * Decrement the use count and release all resources for an mm. | |
653 | */ | |
654 | void mmput(struct mm_struct *mm) | |
655 | { | |
656 | might_sleep(); | |
657 | ||
658 | if (atomic_dec_and_test(&mm->mm_users)) { | |
659 | uprobe_clear_state(mm); | |
660 | exit_aio(mm); | |
661 | ksm_exit(mm); | |
662 | khugepaged_exit(mm); /* must run before exit_mmap */ | |
663 | exit_mmap(mm); | |
664 | set_mm_exe_file(mm, NULL); | |
665 | if (!list_empty(&mm->mmlist)) { | |
666 | spin_lock(&mmlist_lock); | |
667 | list_del(&mm->mmlist); | |
668 | spin_unlock(&mmlist_lock); | |
669 | } | |
670 | if (mm->binfmt) | |
671 | module_put(mm->binfmt->module); | |
672 | mmdrop(mm); | |
673 | } | |
674 | } | |
675 | EXPORT_SYMBOL_GPL(mmput); | |
676 | ||
677 | void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) | |
678 | { | |
679 | if (new_exe_file) | |
680 | get_file(new_exe_file); | |
681 | if (mm->exe_file) | |
682 | fput(mm->exe_file); | |
683 | mm->exe_file = new_exe_file; | |
684 | } | |
685 | ||
686 | struct file *get_mm_exe_file(struct mm_struct *mm) | |
687 | { | |
688 | struct file *exe_file; | |
689 | ||
690 | /* We need mmap_sem to protect against races with removal of exe_file */ | |
691 | down_read(&mm->mmap_sem); | |
692 | exe_file = mm->exe_file; | |
693 | if (exe_file) | |
694 | get_file(exe_file); | |
695 | up_read(&mm->mmap_sem); | |
696 | return exe_file; | |
697 | } | |
698 | ||
699 | static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm) | |
700 | { | |
701 | /* It's safe to write the exe_file pointer without exe_file_lock because | |
702 | * this is called during fork when the task is not yet in /proc */ | |
703 | newmm->exe_file = get_mm_exe_file(oldmm); | |
704 | } | |
705 | ||
706 | /** | |
707 | * get_task_mm - acquire a reference to the task's mm | |
708 | * | |
709 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning | |
710 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
711 | * to do its AIO) is not set and if so returns a reference to it, after | |
712 | * bumping up the use count. User must release the mm via mmput() | |
713 | * after use. Typically used by /proc and ptrace. | |
714 | */ | |
715 | struct mm_struct *get_task_mm(struct task_struct *task) | |
716 | { | |
717 | struct mm_struct *mm; | |
718 | ||
719 | task_lock(task); | |
720 | mm = task->mm; | |
721 | if (mm) { | |
722 | if (task->flags & PF_KTHREAD) | |
723 | mm = NULL; | |
724 | else | |
725 | atomic_inc(&mm->mm_users); | |
726 | } | |
727 | task_unlock(task); | |
728 | return mm; | |
729 | } | |
730 | EXPORT_SYMBOL_GPL(get_task_mm); | |
731 | ||
732 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) | |
733 | { | |
734 | struct mm_struct *mm; | |
735 | int err; | |
736 | ||
737 | err = mutex_lock_killable(&task->signal->cred_guard_mutex); | |
738 | if (err) | |
739 | return ERR_PTR(err); | |
740 | ||
741 | mm = get_task_mm(task); | |
742 | if (mm && mm != current->mm && | |
743 | !ptrace_may_access(task, mode)) { | |
744 | mmput(mm); | |
745 | mm = ERR_PTR(-EACCES); | |
746 | } | |
747 | mutex_unlock(&task->signal->cred_guard_mutex); | |
748 | ||
749 | return mm; | |
750 | } | |
751 | ||
752 | static void complete_vfork_done(struct task_struct *tsk) | |
753 | { | |
754 | struct completion *vfork; | |
755 | ||
756 | task_lock(tsk); | |
757 | vfork = tsk->vfork_done; | |
758 | if (likely(vfork)) { | |
759 | tsk->vfork_done = NULL; | |
760 | complete(vfork); | |
761 | } | |
762 | task_unlock(tsk); | |
763 | } | |
764 | ||
765 | static int wait_for_vfork_done(struct task_struct *child, | |
766 | struct completion *vfork) | |
767 | { | |
768 | int killed; | |
769 | ||
770 | freezer_do_not_count(); | |
771 | killed = wait_for_completion_killable(vfork); | |
772 | freezer_count(); | |
773 | ||
774 | if (killed) { | |
775 | task_lock(child); | |
776 | child->vfork_done = NULL; | |
777 | task_unlock(child); | |
778 | } | |
779 | ||
780 | put_task_struct(child); | |
781 | return killed; | |
782 | } | |
783 | ||
784 | /* Please note the differences between mmput and mm_release. | |
785 | * mmput is called whenever we stop holding onto a mm_struct, | |
786 | * error success whatever. | |
787 | * | |
788 | * mm_release is called after a mm_struct has been removed | |
789 | * from the current process. | |
790 | * | |
791 | * This difference is important for error handling, when we | |
792 | * only half set up a mm_struct for a new process and need to restore | |
793 | * the old one. Because we mmput the new mm_struct before | |
794 | * restoring the old one. . . | |
795 | * Eric Biederman 10 January 1998 | |
796 | */ | |
797 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
798 | { | |
799 | /* Get rid of any futexes when releasing the mm */ | |
800 | #ifdef CONFIG_FUTEX | |
801 | if (unlikely(tsk->robust_list)) { | |
802 | exit_robust_list(tsk); | |
803 | tsk->robust_list = NULL; | |
804 | } | |
805 | #ifdef CONFIG_COMPAT | |
806 | if (unlikely(tsk->compat_robust_list)) { | |
807 | compat_exit_robust_list(tsk); | |
808 | tsk->compat_robust_list = NULL; | |
809 | } | |
810 | #endif | |
811 | if (unlikely(!list_empty(&tsk->pi_state_list))) | |
812 | exit_pi_state_list(tsk); | |
813 | #endif | |
814 | ||
815 | uprobe_free_utask(tsk); | |
816 | ||
817 | /* Get rid of any cached register state */ | |
818 | deactivate_mm(tsk, mm); | |
819 | ||
820 | /* | |
821 | * If we're exiting normally, clear a user-space tid field if | |
822 | * requested. We leave this alone when dying by signal, to leave | |
823 | * the value intact in a core dump, and to save the unnecessary | |
824 | * trouble, say, a killed vfork parent shouldn't touch this mm. | |
825 | * Userland only wants this done for a sys_exit. | |
826 | */ | |
827 | if (tsk->clear_child_tid) { | |
828 | if (!(tsk->flags & PF_SIGNALED) && | |
829 | atomic_read(&mm->mm_users) > 1) { | |
830 | /* | |
831 | * We don't check the error code - if userspace has | |
832 | * not set up a proper pointer then tough luck. | |
833 | */ | |
834 | put_user(0, tsk->clear_child_tid); | |
835 | sys_futex(tsk->clear_child_tid, FUTEX_WAKE, | |
836 | 1, NULL, NULL, 0); | |
837 | } | |
838 | tsk->clear_child_tid = NULL; | |
839 | } | |
840 | ||
841 | /* | |
842 | * All done, finally we can wake up parent and return this mm to him. | |
843 | * Also kthread_stop() uses this completion for synchronization. | |
844 | */ | |
845 | if (tsk->vfork_done) | |
846 | complete_vfork_done(tsk); | |
847 | } | |
848 | ||
849 | /* | |
850 | * Allocate a new mm structure and copy contents from the | |
851 | * mm structure of the passed in task structure. | |
852 | */ | |
853 | static struct mm_struct *dup_mm(struct task_struct *tsk) | |
854 | { | |
855 | struct mm_struct *mm, *oldmm = current->mm; | |
856 | int err; | |
857 | ||
858 | mm = allocate_mm(); | |
859 | if (!mm) | |
860 | goto fail_nomem; | |
861 | ||
862 | memcpy(mm, oldmm, sizeof(*mm)); | |
863 | ||
864 | if (!mm_init(mm, tsk)) | |
865 | goto fail_nomem; | |
866 | ||
867 | dup_mm_exe_file(oldmm, mm); | |
868 | ||
869 | err = dup_mmap(mm, oldmm); | |
870 | if (err) | |
871 | goto free_pt; | |
872 | ||
873 | mm->hiwater_rss = get_mm_rss(mm); | |
874 | mm->hiwater_vm = mm->total_vm; | |
875 | ||
876 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) | |
877 | goto free_pt; | |
878 | ||
879 | return mm; | |
880 | ||
881 | free_pt: | |
882 | /* don't put binfmt in mmput, we haven't got module yet */ | |
883 | mm->binfmt = NULL; | |
884 | mmput(mm); | |
885 | ||
886 | fail_nomem: | |
887 | return NULL; | |
888 | } | |
889 | ||
890 | static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) | |
891 | { | |
892 | struct mm_struct *mm, *oldmm; | |
893 | int retval; | |
894 | ||
895 | tsk->min_flt = tsk->maj_flt = 0; | |
896 | tsk->nvcsw = tsk->nivcsw = 0; | |
897 | #ifdef CONFIG_DETECT_HUNG_TASK | |
898 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; | |
899 | #endif | |
900 | ||
901 | tsk->mm = NULL; | |
902 | tsk->active_mm = NULL; | |
903 | ||
904 | /* | |
905 | * Are we cloning a kernel thread? | |
906 | * | |
907 | * We need to steal a active VM for that.. | |
908 | */ | |
909 | oldmm = current->mm; | |
910 | if (!oldmm) | |
911 | return 0; | |
912 | ||
913 | /* initialize the new vmacache entries */ | |
914 | vmacache_flush(tsk); | |
915 | ||
916 | if (clone_flags & CLONE_VM) { | |
917 | atomic_inc(&oldmm->mm_users); | |
918 | mm = oldmm; | |
919 | goto good_mm; | |
920 | } | |
921 | ||
922 | retval = -ENOMEM; | |
923 | mm = dup_mm(tsk); | |
924 | if (!mm) | |
925 | goto fail_nomem; | |
926 | ||
927 | good_mm: | |
928 | tsk->mm = mm; | |
929 | tsk->active_mm = mm; | |
930 | return 0; | |
931 | ||
932 | fail_nomem: | |
933 | return retval; | |
934 | } | |
935 | ||
936 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) | |
937 | { | |
938 | struct fs_struct *fs = current->fs; | |
939 | if (clone_flags & CLONE_FS) { | |
940 | /* tsk->fs is already what we want */ | |
941 | spin_lock(&fs->lock); | |
942 | if (fs->in_exec) { | |
943 | spin_unlock(&fs->lock); | |
944 | return -EAGAIN; | |
945 | } | |
946 | fs->users++; | |
947 | spin_unlock(&fs->lock); | |
948 | return 0; | |
949 | } | |
950 | tsk->fs = copy_fs_struct(fs); | |
951 | if (!tsk->fs) | |
952 | return -ENOMEM; | |
953 | return 0; | |
954 | } | |
955 | ||
956 | static int copy_files(unsigned long clone_flags, struct task_struct *tsk) | |
957 | { | |
958 | struct files_struct *oldf, *newf; | |
959 | int error = 0; | |
960 | ||
961 | /* | |
962 | * A background process may not have any files ... | |
963 | */ | |
964 | oldf = current->files; | |
965 | if (!oldf) | |
966 | goto out; | |
967 | ||
968 | if (clone_flags & CLONE_FILES) { | |
969 | atomic_inc(&oldf->count); | |
970 | goto out; | |
971 | } | |
972 | ||
973 | newf = dup_fd(oldf, &error); | |
974 | if (!newf) | |
975 | goto out; | |
976 | ||
977 | tsk->files = newf; | |
978 | error = 0; | |
979 | out: | |
980 | return error; | |
981 | } | |
982 | ||
983 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) | |
984 | { | |
985 | #ifdef CONFIG_BLOCK | |
986 | struct io_context *ioc = current->io_context; | |
987 | struct io_context *new_ioc; | |
988 | ||
989 | if (!ioc) | |
990 | return 0; | |
991 | /* | |
992 | * Share io context with parent, if CLONE_IO is set | |
993 | */ | |
994 | if (clone_flags & CLONE_IO) { | |
995 | ioc_task_link(ioc); | |
996 | tsk->io_context = ioc; | |
997 | } else if (ioprio_valid(ioc->ioprio)) { | |
998 | new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); | |
999 | if (unlikely(!new_ioc)) | |
1000 | return -ENOMEM; | |
1001 | ||
1002 | new_ioc->ioprio = ioc->ioprio; | |
1003 | put_io_context(new_ioc); | |
1004 | } | |
1005 | #endif | |
1006 | return 0; | |
1007 | } | |
1008 | ||
1009 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) | |
1010 | { | |
1011 | struct sighand_struct *sig; | |
1012 | ||
1013 | if (clone_flags & CLONE_SIGHAND) { | |
1014 | atomic_inc(¤t->sighand->count); | |
1015 | return 0; | |
1016 | } | |
1017 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
1018 | rcu_assign_pointer(tsk->sighand, sig); | |
1019 | if (!sig) | |
1020 | return -ENOMEM; | |
1021 | atomic_set(&sig->count, 1); | |
1022 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
1023 | return 0; | |
1024 | } | |
1025 | ||
1026 | void __cleanup_sighand(struct sighand_struct *sighand) | |
1027 | { | |
1028 | if (atomic_dec_and_test(&sighand->count)) { | |
1029 | signalfd_cleanup(sighand); | |
1030 | /* | |
1031 | * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it | |
1032 | * without an RCU grace period, see __lock_task_sighand(). | |
1033 | */ | |
1034 | kmem_cache_free(sighand_cachep, sighand); | |
1035 | } | |
1036 | } | |
1037 | ||
1038 | /* | |
1039 | * Initialize POSIX timer handling for a thread group. | |
1040 | */ | |
1041 | static void posix_cpu_timers_init_group(struct signal_struct *sig) | |
1042 | { | |
1043 | unsigned long cpu_limit; | |
1044 | ||
1045 | /* Thread group counters. */ | |
1046 | thread_group_cputime_init(sig); | |
1047 | ||
1048 | cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); | |
1049 | if (cpu_limit != RLIM_INFINITY) { | |
1050 | sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); | |
1051 | sig->cputimer.running = 1; | |
1052 | } | |
1053 | ||
1054 | /* The timer lists. */ | |
1055 | INIT_LIST_HEAD(&sig->cpu_timers[0]); | |
1056 | INIT_LIST_HEAD(&sig->cpu_timers[1]); | |
1057 | INIT_LIST_HEAD(&sig->cpu_timers[2]); | |
1058 | } | |
1059 | ||
1060 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) | |
1061 | { | |
1062 | struct signal_struct *sig; | |
1063 | ||
1064 | if (clone_flags & CLONE_THREAD) | |
1065 | return 0; | |
1066 | ||
1067 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); | |
1068 | tsk->signal = sig; | |
1069 | if (!sig) | |
1070 | return -ENOMEM; | |
1071 | ||
1072 | sig->nr_threads = 1; | |
1073 | atomic_set(&sig->live, 1); | |
1074 | atomic_set(&sig->sigcnt, 1); | |
1075 | ||
1076 | /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ | |
1077 | sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); | |
1078 | tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); | |
1079 | ||
1080 | init_waitqueue_head(&sig->wait_chldexit); | |
1081 | sig->curr_target = tsk; | |
1082 | init_sigpending(&sig->shared_pending); | |
1083 | INIT_LIST_HEAD(&sig->posix_timers); | |
1084 | seqlock_init(&sig->stats_lock); | |
1085 | ||
1086 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
1087 | sig->real_timer.function = it_real_fn; | |
1088 | ||
1089 | task_lock(current->group_leader); | |
1090 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
1091 | task_unlock(current->group_leader); | |
1092 | ||
1093 | posix_cpu_timers_init_group(sig); | |
1094 | ||
1095 | tty_audit_fork(sig); | |
1096 | sched_autogroup_fork(sig); | |
1097 | ||
1098 | #ifdef CONFIG_CGROUPS | |
1099 | init_rwsem(&sig->group_rwsem); | |
1100 | #endif | |
1101 | ||
1102 | sig->oom_score_adj = current->signal->oom_score_adj; | |
1103 | sig->oom_score_adj_min = current->signal->oom_score_adj_min; | |
1104 | ||
1105 | sig->has_child_subreaper = current->signal->has_child_subreaper || | |
1106 | current->signal->is_child_subreaper; | |
1107 | ||
1108 | mutex_init(&sig->cred_guard_mutex); | |
1109 | ||
1110 | return 0; | |
1111 | } | |
1112 | ||
1113 | static void copy_seccomp(struct task_struct *p) | |
1114 | { | |
1115 | #ifdef CONFIG_SECCOMP | |
1116 | /* | |
1117 | * Must be called with sighand->lock held, which is common to | |
1118 | * all threads in the group. Holding cred_guard_mutex is not | |
1119 | * needed because this new task is not yet running and cannot | |
1120 | * be racing exec. | |
1121 | */ | |
1122 | assert_spin_locked(¤t->sighand->siglock); | |
1123 | ||
1124 | /* Ref-count the new filter user, and assign it. */ | |
1125 | get_seccomp_filter(current); | |
1126 | p->seccomp = current->seccomp; | |
1127 | ||
1128 | /* | |
1129 | * Explicitly enable no_new_privs here in case it got set | |
1130 | * between the task_struct being duplicated and holding the | |
1131 | * sighand lock. The seccomp state and nnp must be in sync. | |
1132 | */ | |
1133 | if (task_no_new_privs(current)) | |
1134 | task_set_no_new_privs(p); | |
1135 | ||
1136 | /* | |
1137 | * If the parent gained a seccomp mode after copying thread | |
1138 | * flags and between before we held the sighand lock, we have | |
1139 | * to manually enable the seccomp thread flag here. | |
1140 | */ | |
1141 | if (p->seccomp.mode != SECCOMP_MODE_DISABLED) | |
1142 | set_tsk_thread_flag(p, TIF_SECCOMP); | |
1143 | #endif | |
1144 | } | |
1145 | ||
1146 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) | |
1147 | { | |
1148 | current->clear_child_tid = tidptr; | |
1149 | ||
1150 | return task_pid_vnr(current); | |
1151 | } | |
1152 | ||
1153 | static void rt_mutex_init_task(struct task_struct *p) | |
1154 | { | |
1155 | raw_spin_lock_init(&p->pi_lock); | |
1156 | #ifdef CONFIG_RT_MUTEXES | |
1157 | p->pi_waiters = RB_ROOT; | |
1158 | p->pi_waiters_leftmost = NULL; | |
1159 | p->pi_blocked_on = NULL; | |
1160 | #endif | |
1161 | } | |
1162 | ||
1163 | /* | |
1164 | * Initialize POSIX timer handling for a single task. | |
1165 | */ | |
1166 | static void posix_cpu_timers_init(struct task_struct *tsk) | |
1167 | { | |
1168 | tsk->cputime_expires.prof_exp = 0; | |
1169 | tsk->cputime_expires.virt_exp = 0; | |
1170 | tsk->cputime_expires.sched_exp = 0; | |
1171 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); | |
1172 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); | |
1173 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); | |
1174 | } | |
1175 | ||
1176 | static inline void | |
1177 | init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) | |
1178 | { | |
1179 | task->pids[type].pid = pid; | |
1180 | } | |
1181 | ||
1182 | /* | |
1183 | * This creates a new process as a copy of the old one, | |
1184 | * but does not actually start it yet. | |
1185 | * | |
1186 | * It copies the registers, and all the appropriate | |
1187 | * parts of the process environment (as per the clone | |
1188 | * flags). The actual kick-off is left to the caller. | |
1189 | */ | |
1190 | static struct task_struct *copy_process(unsigned long clone_flags, | |
1191 | unsigned long stack_start, | |
1192 | unsigned long stack_size, | |
1193 | int __user *child_tidptr, | |
1194 | struct pid *pid, | |
1195 | int trace) | |
1196 | { | |
1197 | int retval; | |
1198 | struct task_struct *p; | |
1199 | ||
1200 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
1201 | return ERR_PTR(-EINVAL); | |
1202 | ||
1203 | if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) | |
1204 | return ERR_PTR(-EINVAL); | |
1205 | ||
1206 | /* | |
1207 | * Thread groups must share signals as well, and detached threads | |
1208 | * can only be started up within the thread group. | |
1209 | */ | |
1210 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
1211 | return ERR_PTR(-EINVAL); | |
1212 | ||
1213 | /* | |
1214 | * Shared signal handlers imply shared VM. By way of the above, | |
1215 | * thread groups also imply shared VM. Blocking this case allows | |
1216 | * for various simplifications in other code. | |
1217 | */ | |
1218 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
1219 | return ERR_PTR(-EINVAL); | |
1220 | ||
1221 | /* | |
1222 | * Siblings of global init remain as zombies on exit since they are | |
1223 | * not reaped by their parent (swapper). To solve this and to avoid | |
1224 | * multi-rooted process trees, prevent global and container-inits | |
1225 | * from creating siblings. | |
1226 | */ | |
1227 | if ((clone_flags & CLONE_PARENT) && | |
1228 | current->signal->flags & SIGNAL_UNKILLABLE) | |
1229 | return ERR_PTR(-EINVAL); | |
1230 | ||
1231 | /* | |
1232 | * If the new process will be in a different pid or user namespace | |
1233 | * do not allow it to share a thread group or signal handlers or | |
1234 | * parent with the forking task. | |
1235 | */ | |
1236 | if (clone_flags & CLONE_SIGHAND) { | |
1237 | if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || | |
1238 | (task_active_pid_ns(current) != | |
1239 | current->nsproxy->pid_ns_for_children)) | |
1240 | return ERR_PTR(-EINVAL); | |
1241 | } | |
1242 | ||
1243 | retval = security_task_create(clone_flags); | |
1244 | if (retval) | |
1245 | goto fork_out; | |
1246 | ||
1247 | retval = -ENOMEM; | |
1248 | p = dup_task_struct(current); | |
1249 | if (!p) | |
1250 | goto fork_out; | |
1251 | ||
1252 | ftrace_graph_init_task(p); | |
1253 | ||
1254 | rt_mutex_init_task(p); | |
1255 | ||
1256 | #ifdef CONFIG_PROVE_LOCKING | |
1257 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); | |
1258 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); | |
1259 | #endif | |
1260 | retval = -EAGAIN; | |
1261 | if (atomic_read(&p->real_cred->user->processes) >= | |
1262 | task_rlimit(p, RLIMIT_NPROC)) { | |
1263 | if (p->real_cred->user != INIT_USER && | |
1264 | !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) | |
1265 | goto bad_fork_free; | |
1266 | } | |
1267 | current->flags &= ~PF_NPROC_EXCEEDED; | |
1268 | ||
1269 | retval = copy_creds(p, clone_flags); | |
1270 | if (retval < 0) | |
1271 | goto bad_fork_free; | |
1272 | ||
1273 | /* | |
1274 | * If multiple threads are within copy_process(), then this check | |
1275 | * triggers too late. This doesn't hurt, the check is only there | |
1276 | * to stop root fork bombs. | |
1277 | */ | |
1278 | retval = -EAGAIN; | |
1279 | if (nr_threads >= max_threads) | |
1280 | goto bad_fork_cleanup_count; | |
1281 | ||
1282 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) | |
1283 | goto bad_fork_cleanup_count; | |
1284 | ||
1285 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ | |
1286 | p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); | |
1287 | p->flags |= PF_FORKNOEXEC; | |
1288 | INIT_LIST_HEAD(&p->children); | |
1289 | INIT_LIST_HEAD(&p->sibling); | |
1290 | rcu_copy_process(p); | |
1291 | p->vfork_done = NULL; | |
1292 | spin_lock_init(&p->alloc_lock); | |
1293 | ||
1294 | init_sigpending(&p->pending); | |
1295 | ||
1296 | p->utime = p->stime = p->gtime = 0; | |
1297 | p->utimescaled = p->stimescaled = 0; | |
1298 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE | |
1299 | p->prev_cputime.utime = p->prev_cputime.stime = 0; | |
1300 | #endif | |
1301 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN | |
1302 | seqlock_init(&p->vtime_seqlock); | |
1303 | p->vtime_snap = 0; | |
1304 | p->vtime_snap_whence = VTIME_SLEEPING; | |
1305 | #endif | |
1306 | ||
1307 | #if defined(SPLIT_RSS_COUNTING) | |
1308 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); | |
1309 | #endif | |
1310 | ||
1311 | p->default_timer_slack_ns = current->timer_slack_ns; | |
1312 | ||
1313 | task_io_accounting_init(&p->ioac); | |
1314 | acct_clear_integrals(p); | |
1315 | ||
1316 | posix_cpu_timers_init(p); | |
1317 | ||
1318 | p->start_time = ktime_get_ns(); | |
1319 | p->real_start_time = ktime_get_boot_ns(); | |
1320 | p->io_context = NULL; | |
1321 | p->audit_context = NULL; | |
1322 | if (clone_flags & CLONE_THREAD) | |
1323 | threadgroup_change_begin(current); | |
1324 | cgroup_fork(p); | |
1325 | #ifdef CONFIG_NUMA | |
1326 | p->mempolicy = mpol_dup(p->mempolicy); | |
1327 | if (IS_ERR(p->mempolicy)) { | |
1328 | retval = PTR_ERR(p->mempolicy); | |
1329 | p->mempolicy = NULL; | |
1330 | goto bad_fork_cleanup_threadgroup_lock; | |
1331 | } | |
1332 | #endif | |
1333 | #ifdef CONFIG_CPUSETS | |
1334 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE; | |
1335 | p->cpuset_slab_spread_rotor = NUMA_NO_NODE; | |
1336 | seqcount_init(&p->mems_allowed_seq); | |
1337 | #endif | |
1338 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1339 | p->irq_events = 0; | |
1340 | p->hardirqs_enabled = 0; | |
1341 | p->hardirq_enable_ip = 0; | |
1342 | p->hardirq_enable_event = 0; | |
1343 | p->hardirq_disable_ip = _THIS_IP_; | |
1344 | p->hardirq_disable_event = 0; | |
1345 | p->softirqs_enabled = 1; | |
1346 | p->softirq_enable_ip = _THIS_IP_; | |
1347 | p->softirq_enable_event = 0; | |
1348 | p->softirq_disable_ip = 0; | |
1349 | p->softirq_disable_event = 0; | |
1350 | p->hardirq_context = 0; | |
1351 | p->softirq_context = 0; | |
1352 | #endif | |
1353 | #ifdef CONFIG_LOCKDEP | |
1354 | p->lockdep_depth = 0; /* no locks held yet */ | |
1355 | p->curr_chain_key = 0; | |
1356 | p->lockdep_recursion = 0; | |
1357 | #endif | |
1358 | ||
1359 | #ifdef CONFIG_DEBUG_MUTEXES | |
1360 | p->blocked_on = NULL; /* not blocked yet */ | |
1361 | #endif | |
1362 | #ifdef CONFIG_BCACHE | |
1363 | p->sequential_io = 0; | |
1364 | p->sequential_io_avg = 0; | |
1365 | #endif | |
1366 | ||
1367 | /* Perform scheduler related setup. Assign this task to a CPU. */ | |
1368 | retval = sched_fork(clone_flags, p); | |
1369 | if (retval) | |
1370 | goto bad_fork_cleanup_policy; | |
1371 | ||
1372 | retval = perf_event_init_task(p); | |
1373 | if (retval) | |
1374 | goto bad_fork_cleanup_policy; | |
1375 | retval = audit_alloc(p); | |
1376 | if (retval) | |
1377 | goto bad_fork_cleanup_perf; | |
1378 | /* copy all the process information */ | |
1379 | shm_init_task(p); | |
1380 | retval = copy_semundo(clone_flags, p); | |
1381 | if (retval) | |
1382 | goto bad_fork_cleanup_audit; | |
1383 | retval = copy_files(clone_flags, p); | |
1384 | if (retval) | |
1385 | goto bad_fork_cleanup_semundo; | |
1386 | retval = copy_fs(clone_flags, p); | |
1387 | if (retval) | |
1388 | goto bad_fork_cleanup_files; | |
1389 | retval = copy_sighand(clone_flags, p); | |
1390 | if (retval) | |
1391 | goto bad_fork_cleanup_fs; | |
1392 | retval = copy_signal(clone_flags, p); | |
1393 | if (retval) | |
1394 | goto bad_fork_cleanup_sighand; | |
1395 | retval = copy_mm(clone_flags, p); | |
1396 | if (retval) | |
1397 | goto bad_fork_cleanup_signal; | |
1398 | retval = copy_namespaces(clone_flags, p); | |
1399 | if (retval) | |
1400 | goto bad_fork_cleanup_mm; | |
1401 | retval = copy_io(clone_flags, p); | |
1402 | if (retval) | |
1403 | goto bad_fork_cleanup_namespaces; | |
1404 | retval = copy_thread(clone_flags, stack_start, stack_size, p); | |
1405 | if (retval) | |
1406 | goto bad_fork_cleanup_io; | |
1407 | ||
1408 | if (pid != &init_struct_pid) { | |
1409 | retval = -ENOMEM; | |
1410 | pid = alloc_pid(p->nsproxy->pid_ns_for_children); | |
1411 | if (!pid) | |
1412 | goto bad_fork_cleanup_io; | |
1413 | } | |
1414 | ||
1415 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; | |
1416 | /* | |
1417 | * Clear TID on mm_release()? | |
1418 | */ | |
1419 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; | |
1420 | #ifdef CONFIG_BLOCK | |
1421 | p->plug = NULL; | |
1422 | #endif | |
1423 | #ifdef CONFIG_FUTEX | |
1424 | p->robust_list = NULL; | |
1425 | #ifdef CONFIG_COMPAT | |
1426 | p->compat_robust_list = NULL; | |
1427 | #endif | |
1428 | INIT_LIST_HEAD(&p->pi_state_list); | |
1429 | p->pi_state_cache = NULL; | |
1430 | #endif | |
1431 | /* | |
1432 | * sigaltstack should be cleared when sharing the same VM | |
1433 | */ | |
1434 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) | |
1435 | p->sas_ss_sp = p->sas_ss_size = 0; | |
1436 | ||
1437 | /* | |
1438 | * Syscall tracing and stepping should be turned off in the | |
1439 | * child regardless of CLONE_PTRACE. | |
1440 | */ | |
1441 | user_disable_single_step(p); | |
1442 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); | |
1443 | #ifdef TIF_SYSCALL_EMU | |
1444 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); | |
1445 | #endif | |
1446 | clear_all_latency_tracing(p); | |
1447 | ||
1448 | /* ok, now we should be set up.. */ | |
1449 | p->pid = pid_nr(pid); | |
1450 | if (clone_flags & CLONE_THREAD) { | |
1451 | p->exit_signal = -1; | |
1452 | p->group_leader = current->group_leader; | |
1453 | p->tgid = current->tgid; | |
1454 | } else { | |
1455 | if (clone_flags & CLONE_PARENT) | |
1456 | p->exit_signal = current->group_leader->exit_signal; | |
1457 | else | |
1458 | p->exit_signal = (clone_flags & CSIGNAL); | |
1459 | p->group_leader = p; | |
1460 | p->tgid = p->pid; | |
1461 | } | |
1462 | ||
1463 | p->nr_dirtied = 0; | |
1464 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); | |
1465 | p->dirty_paused_when = 0; | |
1466 | ||
1467 | p->pdeath_signal = 0; | |
1468 | INIT_LIST_HEAD(&p->thread_group); | |
1469 | p->task_works = NULL; | |
1470 | ||
1471 | /* | |
1472 | * Make it visible to the rest of the system, but dont wake it up yet. | |
1473 | * Need tasklist lock for parent etc handling! | |
1474 | */ | |
1475 | write_lock_irq(&tasklist_lock); | |
1476 | ||
1477 | /* CLONE_PARENT re-uses the old parent */ | |
1478 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { | |
1479 | p->real_parent = current->real_parent; | |
1480 | p->parent_exec_id = current->parent_exec_id; | |
1481 | } else { | |
1482 | p->real_parent = current; | |
1483 | p->parent_exec_id = current->self_exec_id; | |
1484 | } | |
1485 | ||
1486 | spin_lock(¤t->sighand->siglock); | |
1487 | ||
1488 | /* | |
1489 | * Copy seccomp details explicitly here, in case they were changed | |
1490 | * before holding sighand lock. | |
1491 | */ | |
1492 | copy_seccomp(p); | |
1493 | ||
1494 | /* | |
1495 | * Process group and session signals need to be delivered to just the | |
1496 | * parent before the fork or both the parent and the child after the | |
1497 | * fork. Restart if a signal comes in before we add the new process to | |
1498 | * it's process group. | |
1499 | * A fatal signal pending means that current will exit, so the new | |
1500 | * thread can't slip out of an OOM kill (or normal SIGKILL). | |
1501 | */ | |
1502 | recalc_sigpending(); | |
1503 | if (signal_pending(current)) { | |
1504 | spin_unlock(¤t->sighand->siglock); | |
1505 | write_unlock_irq(&tasklist_lock); | |
1506 | retval = -ERESTARTNOINTR; | |
1507 | goto bad_fork_free_pid; | |
1508 | } | |
1509 | ||
1510 | if (likely(p->pid)) { | |
1511 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); | |
1512 | ||
1513 | init_task_pid(p, PIDTYPE_PID, pid); | |
1514 | if (thread_group_leader(p)) { | |
1515 | init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); | |
1516 | init_task_pid(p, PIDTYPE_SID, task_session(current)); | |
1517 | ||
1518 | if (is_child_reaper(pid)) { | |
1519 | ns_of_pid(pid)->child_reaper = p; | |
1520 | p->signal->flags |= SIGNAL_UNKILLABLE; | |
1521 | } | |
1522 | ||
1523 | p->signal->leader_pid = pid; | |
1524 | p->signal->tty = tty_kref_get(current->signal->tty); | |
1525 | list_add_tail(&p->sibling, &p->real_parent->children); | |
1526 | list_add_tail_rcu(&p->tasks, &init_task.tasks); | |
1527 | attach_pid(p, PIDTYPE_PGID); | |
1528 | attach_pid(p, PIDTYPE_SID); | |
1529 | __this_cpu_inc(process_counts); | |
1530 | } else { | |
1531 | current->signal->nr_threads++; | |
1532 | atomic_inc(¤t->signal->live); | |
1533 | atomic_inc(¤t->signal->sigcnt); | |
1534 | list_add_tail_rcu(&p->thread_group, | |
1535 | &p->group_leader->thread_group); | |
1536 | list_add_tail_rcu(&p->thread_node, | |
1537 | &p->signal->thread_head); | |
1538 | } | |
1539 | attach_pid(p, PIDTYPE_PID); | |
1540 | nr_threads++; | |
1541 | } | |
1542 | ||
1543 | total_forks++; | |
1544 | spin_unlock(¤t->sighand->siglock); | |
1545 | syscall_tracepoint_update(p); | |
1546 | write_unlock_irq(&tasklist_lock); | |
1547 | ||
1548 | proc_fork_connector(p); | |
1549 | cgroup_post_fork(p); | |
1550 | if (clone_flags & CLONE_THREAD) | |
1551 | threadgroup_change_end(current); | |
1552 | perf_event_fork(p); | |
1553 | ||
1554 | trace_task_newtask(p, clone_flags); | |
1555 | uprobe_copy_process(p, clone_flags); | |
1556 | ||
1557 | return p; | |
1558 | ||
1559 | bad_fork_free_pid: | |
1560 | if (pid != &init_struct_pid) | |
1561 | free_pid(pid); | |
1562 | bad_fork_cleanup_io: | |
1563 | if (p->io_context) | |
1564 | exit_io_context(p); | |
1565 | bad_fork_cleanup_namespaces: | |
1566 | exit_task_namespaces(p); | |
1567 | bad_fork_cleanup_mm: | |
1568 | if (p->mm) | |
1569 | mmput(p->mm); | |
1570 | bad_fork_cleanup_signal: | |
1571 | if (!(clone_flags & CLONE_THREAD)) | |
1572 | free_signal_struct(p->signal); | |
1573 | bad_fork_cleanup_sighand: | |
1574 | __cleanup_sighand(p->sighand); | |
1575 | bad_fork_cleanup_fs: | |
1576 | exit_fs(p); /* blocking */ | |
1577 | bad_fork_cleanup_files: | |
1578 | exit_files(p); /* blocking */ | |
1579 | bad_fork_cleanup_semundo: | |
1580 | exit_sem(p); | |
1581 | bad_fork_cleanup_audit: | |
1582 | audit_free(p); | |
1583 | bad_fork_cleanup_perf: | |
1584 | perf_event_free_task(p); | |
1585 | bad_fork_cleanup_policy: | |
1586 | #ifdef CONFIG_NUMA | |
1587 | mpol_put(p->mempolicy); | |
1588 | bad_fork_cleanup_threadgroup_lock: | |
1589 | #endif | |
1590 | if (clone_flags & CLONE_THREAD) | |
1591 | threadgroup_change_end(current); | |
1592 | delayacct_tsk_free(p); | |
1593 | module_put(task_thread_info(p)->exec_domain->module); | |
1594 | bad_fork_cleanup_count: | |
1595 | atomic_dec(&p->cred->user->processes); | |
1596 | exit_creds(p); | |
1597 | bad_fork_free: | |
1598 | free_task(p); | |
1599 | fork_out: | |
1600 | return ERR_PTR(retval); | |
1601 | } | |
1602 | ||
1603 | static inline void init_idle_pids(struct pid_link *links) | |
1604 | { | |
1605 | enum pid_type type; | |
1606 | ||
1607 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { | |
1608 | INIT_HLIST_NODE(&links[type].node); /* not really needed */ | |
1609 | links[type].pid = &init_struct_pid; | |
1610 | } | |
1611 | } | |
1612 | ||
1613 | struct task_struct *fork_idle(int cpu) | |
1614 | { | |
1615 | struct task_struct *task; | |
1616 | task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0); | |
1617 | if (!IS_ERR(task)) { | |
1618 | init_idle_pids(task->pids); | |
1619 | init_idle(task, cpu); | |
1620 | } | |
1621 | ||
1622 | return task; | |
1623 | } | |
1624 | ||
1625 | /* | |
1626 | * Ok, this is the main fork-routine. | |
1627 | * | |
1628 | * It copies the process, and if successful kick-starts | |
1629 | * it and waits for it to finish using the VM if required. | |
1630 | */ | |
1631 | long do_fork(unsigned long clone_flags, | |
1632 | unsigned long stack_start, | |
1633 | unsigned long stack_size, | |
1634 | int __user *parent_tidptr, | |
1635 | int __user *child_tidptr) | |
1636 | { | |
1637 | struct task_struct *p; | |
1638 | int trace = 0; | |
1639 | long nr; | |
1640 | ||
1641 | /* | |
1642 | * Determine whether and which event to report to ptracer. When | |
1643 | * called from kernel_thread or CLONE_UNTRACED is explicitly | |
1644 | * requested, no event is reported; otherwise, report if the event | |
1645 | * for the type of forking is enabled. | |
1646 | */ | |
1647 | if (!(clone_flags & CLONE_UNTRACED)) { | |
1648 | if (clone_flags & CLONE_VFORK) | |
1649 | trace = PTRACE_EVENT_VFORK; | |
1650 | else if ((clone_flags & CSIGNAL) != SIGCHLD) | |
1651 | trace = PTRACE_EVENT_CLONE; | |
1652 | else | |
1653 | trace = PTRACE_EVENT_FORK; | |
1654 | ||
1655 | if (likely(!ptrace_event_enabled(current, trace))) | |
1656 | trace = 0; | |
1657 | } | |
1658 | ||
1659 | p = copy_process(clone_flags, stack_start, stack_size, | |
1660 | child_tidptr, NULL, trace); | |
1661 | /* | |
1662 | * Do this prior waking up the new thread - the thread pointer | |
1663 | * might get invalid after that point, if the thread exits quickly. | |
1664 | */ | |
1665 | if (!IS_ERR(p)) { | |
1666 | struct completion vfork; | |
1667 | struct pid *pid; | |
1668 | ||
1669 | trace_sched_process_fork(current, p); | |
1670 | ||
1671 | pid = get_task_pid(p, PIDTYPE_PID); | |
1672 | nr = pid_vnr(pid); | |
1673 | ||
1674 | if (clone_flags & CLONE_PARENT_SETTID) | |
1675 | put_user(nr, parent_tidptr); | |
1676 | ||
1677 | if (clone_flags & CLONE_VFORK) { | |
1678 | p->vfork_done = &vfork; | |
1679 | init_completion(&vfork); | |
1680 | get_task_struct(p); | |
1681 | } | |
1682 | ||
1683 | wake_up_new_task(p); | |
1684 | ||
1685 | /* forking complete and child started to run, tell ptracer */ | |
1686 | if (unlikely(trace)) | |
1687 | ptrace_event_pid(trace, pid); | |
1688 | ||
1689 | if (clone_flags & CLONE_VFORK) { | |
1690 | if (!wait_for_vfork_done(p, &vfork)) | |
1691 | ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); | |
1692 | } | |
1693 | ||
1694 | put_pid(pid); | |
1695 | } else { | |
1696 | nr = PTR_ERR(p); | |
1697 | } | |
1698 | return nr; | |
1699 | } | |
1700 | ||
1701 | /* | |
1702 | * Create a kernel thread. | |
1703 | */ | |
1704 | pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) | |
1705 | { | |
1706 | return do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, | |
1707 | (unsigned long)arg, NULL, NULL); | |
1708 | } | |
1709 | ||
1710 | #ifdef __ARCH_WANT_SYS_FORK | |
1711 | SYSCALL_DEFINE0(fork) | |
1712 | { | |
1713 | #ifdef CONFIG_MMU | |
1714 | return do_fork(SIGCHLD, 0, 0, NULL, NULL); | |
1715 | #else | |
1716 | /* can not support in nommu mode */ | |
1717 | return -EINVAL; | |
1718 | #endif | |
1719 | } | |
1720 | #endif | |
1721 | ||
1722 | #ifdef __ARCH_WANT_SYS_VFORK | |
1723 | SYSCALL_DEFINE0(vfork) | |
1724 | { | |
1725 | return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, | |
1726 | 0, NULL, NULL); | |
1727 | } | |
1728 | #endif | |
1729 | ||
1730 | #ifdef __ARCH_WANT_SYS_CLONE | |
1731 | #ifdef CONFIG_CLONE_BACKWARDS | |
1732 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, | |
1733 | int __user *, parent_tidptr, | |
1734 | int, tls_val, | |
1735 | int __user *, child_tidptr) | |
1736 | #elif defined(CONFIG_CLONE_BACKWARDS2) | |
1737 | SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, | |
1738 | int __user *, parent_tidptr, | |
1739 | int __user *, child_tidptr, | |
1740 | int, tls_val) | |
1741 | #elif defined(CONFIG_CLONE_BACKWARDS3) | |
1742 | SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, | |
1743 | int, stack_size, | |
1744 | int __user *, parent_tidptr, | |
1745 | int __user *, child_tidptr, | |
1746 | int, tls_val) | |
1747 | #else | |
1748 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, | |
1749 | int __user *, parent_tidptr, | |
1750 | int __user *, child_tidptr, | |
1751 | int, tls_val) | |
1752 | #endif | |
1753 | { | |
1754 | return do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr); | |
1755 | } | |
1756 | #endif | |
1757 | ||
1758 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN | |
1759 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 | |
1760 | #endif | |
1761 | ||
1762 | static void sighand_ctor(void *data) | |
1763 | { | |
1764 | struct sighand_struct *sighand = data; | |
1765 | ||
1766 | spin_lock_init(&sighand->siglock); | |
1767 | init_waitqueue_head(&sighand->signalfd_wqh); | |
1768 | } | |
1769 | ||
1770 | void __init proc_caches_init(void) | |
1771 | { | |
1772 | sighand_cachep = kmem_cache_create("sighand_cache", | |
1773 | sizeof(struct sighand_struct), 0, | |
1774 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| | |
1775 | SLAB_NOTRACK, sighand_ctor); | |
1776 | signal_cachep = kmem_cache_create("signal_cache", | |
1777 | sizeof(struct signal_struct), 0, | |
1778 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1779 | files_cachep = kmem_cache_create("files_cache", | |
1780 | sizeof(struct files_struct), 0, | |
1781 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1782 | fs_cachep = kmem_cache_create("fs_cache", | |
1783 | sizeof(struct fs_struct), 0, | |
1784 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1785 | /* | |
1786 | * FIXME! The "sizeof(struct mm_struct)" currently includes the | |
1787 | * whole struct cpumask for the OFFSTACK case. We could change | |
1788 | * this to *only* allocate as much of it as required by the | |
1789 | * maximum number of CPU's we can ever have. The cpumask_allocation | |
1790 | * is at the end of the structure, exactly for that reason. | |
1791 | */ | |
1792 | mm_cachep = kmem_cache_create("mm_struct", | |
1793 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, | |
1794 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); | |
1795 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); | |
1796 | mmap_init(); | |
1797 | nsproxy_cache_init(); | |
1798 | } | |
1799 | ||
1800 | /* | |
1801 | * Check constraints on flags passed to the unshare system call. | |
1802 | */ | |
1803 | static int check_unshare_flags(unsigned long unshare_flags) | |
1804 | { | |
1805 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| | |
1806 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| | |
1807 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| | |
1808 | CLONE_NEWUSER|CLONE_NEWPID)) | |
1809 | return -EINVAL; | |
1810 | /* | |
1811 | * Not implemented, but pretend it works if there is nothing to | |
1812 | * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND | |
1813 | * needs to unshare vm. | |
1814 | */ | |
1815 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { | |
1816 | /* FIXME: get_task_mm() increments ->mm_users */ | |
1817 | if (atomic_read(¤t->mm->mm_users) > 1) | |
1818 | return -EINVAL; | |
1819 | } | |
1820 | ||
1821 | return 0; | |
1822 | } | |
1823 | ||
1824 | /* | |
1825 | * Unshare the filesystem structure if it is being shared | |
1826 | */ | |
1827 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) | |
1828 | { | |
1829 | struct fs_struct *fs = current->fs; | |
1830 | ||
1831 | if (!(unshare_flags & CLONE_FS) || !fs) | |
1832 | return 0; | |
1833 | ||
1834 | /* don't need lock here; in the worst case we'll do useless copy */ | |
1835 | if (fs->users == 1) | |
1836 | return 0; | |
1837 | ||
1838 | *new_fsp = copy_fs_struct(fs); | |
1839 | if (!*new_fsp) | |
1840 | return -ENOMEM; | |
1841 | ||
1842 | return 0; | |
1843 | } | |
1844 | ||
1845 | /* | |
1846 | * Unshare file descriptor table if it is being shared | |
1847 | */ | |
1848 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) | |
1849 | { | |
1850 | struct files_struct *fd = current->files; | |
1851 | int error = 0; | |
1852 | ||
1853 | if ((unshare_flags & CLONE_FILES) && | |
1854 | (fd && atomic_read(&fd->count) > 1)) { | |
1855 | *new_fdp = dup_fd(fd, &error); | |
1856 | if (!*new_fdp) | |
1857 | return error; | |
1858 | } | |
1859 | ||
1860 | return 0; | |
1861 | } | |
1862 | ||
1863 | /* | |
1864 | * unshare allows a process to 'unshare' part of the process | |
1865 | * context which was originally shared using clone. copy_* | |
1866 | * functions used by do_fork() cannot be used here directly | |
1867 | * because they modify an inactive task_struct that is being | |
1868 | * constructed. Here we are modifying the current, active, | |
1869 | * task_struct. | |
1870 | */ | |
1871 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) | |
1872 | { | |
1873 | struct fs_struct *fs, *new_fs = NULL; | |
1874 | struct files_struct *fd, *new_fd = NULL; | |
1875 | struct cred *new_cred = NULL; | |
1876 | struct nsproxy *new_nsproxy = NULL; | |
1877 | int do_sysvsem = 0; | |
1878 | int err; | |
1879 | ||
1880 | /* | |
1881 | * If unsharing a user namespace must also unshare the thread. | |
1882 | */ | |
1883 | if (unshare_flags & CLONE_NEWUSER) | |
1884 | unshare_flags |= CLONE_THREAD | CLONE_FS; | |
1885 | /* | |
1886 | * If unsharing a thread from a thread group, must also unshare vm. | |
1887 | */ | |
1888 | if (unshare_flags & CLONE_THREAD) | |
1889 | unshare_flags |= CLONE_VM; | |
1890 | /* | |
1891 | * If unsharing vm, must also unshare signal handlers. | |
1892 | */ | |
1893 | if (unshare_flags & CLONE_VM) | |
1894 | unshare_flags |= CLONE_SIGHAND; | |
1895 | /* | |
1896 | * If unsharing namespace, must also unshare filesystem information. | |
1897 | */ | |
1898 | if (unshare_flags & CLONE_NEWNS) | |
1899 | unshare_flags |= CLONE_FS; | |
1900 | ||
1901 | err = check_unshare_flags(unshare_flags); | |
1902 | if (err) | |
1903 | goto bad_unshare_out; | |
1904 | /* | |
1905 | * CLONE_NEWIPC must also detach from the undolist: after switching | |
1906 | * to a new ipc namespace, the semaphore arrays from the old | |
1907 | * namespace are unreachable. | |
1908 | */ | |
1909 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) | |
1910 | do_sysvsem = 1; | |
1911 | err = unshare_fs(unshare_flags, &new_fs); | |
1912 | if (err) | |
1913 | goto bad_unshare_out; | |
1914 | err = unshare_fd(unshare_flags, &new_fd); | |
1915 | if (err) | |
1916 | goto bad_unshare_cleanup_fs; | |
1917 | err = unshare_userns(unshare_flags, &new_cred); | |
1918 | if (err) | |
1919 | goto bad_unshare_cleanup_fd; | |
1920 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, | |
1921 | new_cred, new_fs); | |
1922 | if (err) | |
1923 | goto bad_unshare_cleanup_cred; | |
1924 | ||
1925 | if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { | |
1926 | if (do_sysvsem) { | |
1927 | /* | |
1928 | * CLONE_SYSVSEM is equivalent to sys_exit(). | |
1929 | */ | |
1930 | exit_sem(current); | |
1931 | } | |
1932 | if (unshare_flags & CLONE_NEWIPC) { | |
1933 | /* Orphan segments in old ns (see sem above). */ | |
1934 | exit_shm(current); | |
1935 | shm_init_task(current); | |
1936 | } | |
1937 | ||
1938 | if (new_nsproxy) | |
1939 | switch_task_namespaces(current, new_nsproxy); | |
1940 | ||
1941 | task_lock(current); | |
1942 | ||
1943 | if (new_fs) { | |
1944 | fs = current->fs; | |
1945 | spin_lock(&fs->lock); | |
1946 | current->fs = new_fs; | |
1947 | if (--fs->users) | |
1948 | new_fs = NULL; | |
1949 | else | |
1950 | new_fs = fs; | |
1951 | spin_unlock(&fs->lock); | |
1952 | } | |
1953 | ||
1954 | if (new_fd) { | |
1955 | fd = current->files; | |
1956 | current->files = new_fd; | |
1957 | new_fd = fd; | |
1958 | } | |
1959 | ||
1960 | task_unlock(current); | |
1961 | ||
1962 | if (new_cred) { | |
1963 | /* Install the new user namespace */ | |
1964 | commit_creds(new_cred); | |
1965 | new_cred = NULL; | |
1966 | } | |
1967 | } | |
1968 | ||
1969 | bad_unshare_cleanup_cred: | |
1970 | if (new_cred) | |
1971 | put_cred(new_cred); | |
1972 | bad_unshare_cleanup_fd: | |
1973 | if (new_fd) | |
1974 | put_files_struct(new_fd); | |
1975 | ||
1976 | bad_unshare_cleanup_fs: | |
1977 | if (new_fs) | |
1978 | free_fs_struct(new_fs); | |
1979 | ||
1980 | bad_unshare_out: | |
1981 | return err; | |
1982 | } | |
1983 | ||
1984 | /* | |
1985 | * Helper to unshare the files of the current task. | |
1986 | * We don't want to expose copy_files internals to | |
1987 | * the exec layer of the kernel. | |
1988 | */ | |
1989 | ||
1990 | int unshare_files(struct files_struct **displaced) | |
1991 | { | |
1992 | struct task_struct *task = current; | |
1993 | struct files_struct *copy = NULL; | |
1994 | int error; | |
1995 | ||
1996 | error = unshare_fd(CLONE_FILES, ©); | |
1997 | if (error || !copy) { | |
1998 | *displaced = NULL; | |
1999 | return error; | |
2000 | } | |
2001 | *displaced = task->files; | |
2002 | task_lock(task); | |
2003 | task->files = copy; | |
2004 | task_unlock(task); | |
2005 | return 0; | |
2006 | } |