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1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * linux/kernel/fork.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | */ | |
7 | ||
8 | /* | |
9 | * 'fork.c' contains the help-routines for the 'fork' system call | |
10 | * (see also entry.S and others). | |
11 | * Fork is rather simple, once you get the hang of it, but the memory | |
12 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' | |
13 | */ | |
14 | ||
15 | #include <linux/anon_inodes.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/sched/autogroup.h> | |
18 | #include <linux/sched/mm.h> | |
19 | #include <linux/sched/coredump.h> | |
20 | #include <linux/sched/user.h> | |
21 | #include <linux/sched/numa_balancing.h> | |
22 | #include <linux/sched/stat.h> | |
23 | #include <linux/sched/task.h> | |
24 | #include <linux/sched/task_stack.h> | |
25 | #include <linux/sched/cputime.h> | |
26 | #include <linux/seq_file.h> | |
27 | #include <linux/rtmutex.h> | |
28 | #include <linux/init.h> | |
29 | #include <linux/unistd.h> | |
30 | #include <linux/module.h> | |
31 | #include <linux/vmalloc.h> | |
32 | #include <linux/completion.h> | |
33 | #include <linux/personality.h> | |
34 | #include <linux/mempolicy.h> | |
35 | #include <linux/sem.h> | |
36 | #include <linux/file.h> | |
37 | #include <linux/fdtable.h> | |
38 | #include <linux/iocontext.h> | |
39 | #include <linux/key.h> | |
40 | #include <linux/binfmts.h> | |
41 | #include <linux/mman.h> | |
42 | #include <linux/mmu_notifier.h> | |
43 | #include <linux/fs.h> | |
44 | #include <linux/mm.h> | |
45 | #include <linux/vmacache.h> | |
46 | #include <linux/nsproxy.h> | |
47 | #include <linux/capability.h> | |
48 | #include <linux/cpu.h> | |
49 | #include <linux/cgroup.h> | |
50 | #include <linux/security.h> | |
51 | #include <linux/hugetlb.h> | |
52 | #include <linux/seccomp.h> | |
53 | #include <linux/swap.h> | |
54 | #include <linux/syscalls.h> | |
55 | #include <linux/jiffies.h> | |
56 | #include <linux/futex.h> | |
57 | #include <linux/compat.h> | |
58 | #include <linux/kthread.h> | |
59 | #include <linux/task_io_accounting_ops.h> | |
60 | #include <linux/rcupdate.h> | |
61 | #include <linux/ptrace.h> | |
62 | #include <linux/mount.h> | |
63 | #include <linux/audit.h> | |
64 | #include <linux/memcontrol.h> | |
65 | #include <linux/ftrace.h> | |
66 | #include <linux/proc_fs.h> | |
67 | #include <linux/profile.h> | |
68 | #include <linux/rmap.h> | |
69 | #include <linux/ksm.h> | |
70 | #include <linux/acct.h> | |
71 | #include <linux/userfaultfd_k.h> | |
72 | #include <linux/tsacct_kern.h> | |
73 | #include <linux/cn_proc.h> | |
74 | #include <linux/freezer.h> | |
75 | #include <linux/delayacct.h> | |
76 | #include <linux/taskstats_kern.h> | |
77 | #include <linux/random.h> | |
78 | #include <linux/tty.h> | |
79 | #include <linux/blkdev.h> | |
80 | #include <linux/fs_struct.h> | |
81 | #include <linux/magic.h> | |
82 | #include <linux/perf_event.h> | |
83 | #include <linux/posix-timers.h> | |
84 | #include <linux/user-return-notifier.h> | |
85 | #include <linux/oom.h> | |
86 | #include <linux/khugepaged.h> | |
87 | #include <linux/signalfd.h> | |
88 | #include <linux/uprobes.h> | |
89 | #include <linux/aio.h> | |
90 | #include <linux/compiler.h> | |
91 | #include <linux/sysctl.h> | |
92 | #include <linux/kcov.h> | |
93 | #include <linux/livepatch.h> | |
94 | #include <linux/thread_info.h> | |
95 | #include <linux/stackleak.h> | |
96 | #include <linux/kasan.h> | |
97 | #include <linux/scs.h> | |
98 | #include <linux/io_uring.h> | |
99 | #include <linux/bpf.h> | |
100 | ||
101 | #include <asm/pgalloc.h> | |
102 | #include <linux/uaccess.h> | |
103 | #include <asm/mmu_context.h> | |
104 | #include <asm/cacheflush.h> | |
105 | #include <asm/tlbflush.h> | |
106 | ||
107 | #include <trace/events/sched.h> | |
108 | ||
109 | #define CREATE_TRACE_POINTS | |
110 | #include <trace/events/task.h> | |
111 | ||
112 | /* | |
113 | * Minimum number of threads to boot the kernel | |
114 | */ | |
115 | #define MIN_THREADS 20 | |
116 | ||
117 | /* | |
118 | * Maximum number of threads | |
119 | */ | |
120 | #define MAX_THREADS FUTEX_TID_MASK | |
121 | ||
122 | /* | |
123 | * Protected counters by write_lock_irq(&tasklist_lock) | |
124 | */ | |
125 | unsigned long total_forks; /* Handle normal Linux uptimes. */ | |
126 | int nr_threads; /* The idle threads do not count.. */ | |
127 | ||
128 | static int max_threads; /* tunable limit on nr_threads */ | |
129 | ||
130 | #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x) | |
131 | ||
132 | static const char * const resident_page_types[] = { | |
133 | NAMED_ARRAY_INDEX(MM_FILEPAGES), | |
134 | NAMED_ARRAY_INDEX(MM_ANONPAGES), | |
135 | NAMED_ARRAY_INDEX(MM_SWAPENTS), | |
136 | NAMED_ARRAY_INDEX(MM_SHMEMPAGES), | |
137 | }; | |
138 | ||
139 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; | |
140 | ||
141 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ | |
142 | ||
143 | #ifdef CONFIG_PROVE_RCU | |
144 | int lockdep_tasklist_lock_is_held(void) | |
145 | { | |
146 | return lockdep_is_held(&tasklist_lock); | |
147 | } | |
148 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); | |
149 | #endif /* #ifdef CONFIG_PROVE_RCU */ | |
150 | ||
151 | int nr_processes(void) | |
152 | { | |
153 | int cpu; | |
154 | int total = 0; | |
155 | ||
156 | for_each_possible_cpu(cpu) | |
157 | total += per_cpu(process_counts, cpu); | |
158 | ||
159 | return total; | |
160 | } | |
161 | ||
162 | void __weak arch_release_task_struct(struct task_struct *tsk) | |
163 | { | |
164 | } | |
165 | ||
166 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR | |
167 | static struct kmem_cache *task_struct_cachep; | |
168 | ||
169 | static inline struct task_struct *alloc_task_struct_node(int node) | |
170 | { | |
171 | return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); | |
172 | } | |
173 | ||
174 | static inline void free_task_struct(struct task_struct *tsk) | |
175 | { | |
176 | kmem_cache_free(task_struct_cachep, tsk); | |
177 | } | |
178 | #endif | |
179 | ||
180 | #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR | |
181 | ||
182 | /* | |
183 | * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a | |
184 | * kmemcache based allocator. | |
185 | */ | |
186 | # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) | |
187 | ||
188 | #ifdef CONFIG_VMAP_STACK | |
189 | /* | |
190 | * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB | |
191 | * flush. Try to minimize the number of calls by caching stacks. | |
192 | */ | |
193 | #define NR_CACHED_STACKS 2 | |
194 | static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); | |
195 | ||
196 | static int free_vm_stack_cache(unsigned int cpu) | |
197 | { | |
198 | struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu); | |
199 | int i; | |
200 | ||
201 | for (i = 0; i < NR_CACHED_STACKS; i++) { | |
202 | struct vm_struct *vm_stack = cached_vm_stacks[i]; | |
203 | ||
204 | if (!vm_stack) | |
205 | continue; | |
206 | ||
207 | vfree(vm_stack->addr); | |
208 | cached_vm_stacks[i] = NULL; | |
209 | } | |
210 | ||
211 | return 0; | |
212 | } | |
213 | #endif | |
214 | ||
215 | static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) | |
216 | { | |
217 | #ifdef CONFIG_VMAP_STACK | |
218 | void *stack; | |
219 | int i; | |
220 | ||
221 | for (i = 0; i < NR_CACHED_STACKS; i++) { | |
222 | struct vm_struct *s; | |
223 | ||
224 | s = this_cpu_xchg(cached_stacks[i], NULL); | |
225 | ||
226 | if (!s) | |
227 | continue; | |
228 | ||
229 | /* Mark stack accessible for KASAN. */ | |
230 | kasan_unpoison_range(s->addr, THREAD_SIZE); | |
231 | ||
232 | /* Clear stale pointers from reused stack. */ | |
233 | memset(s->addr, 0, THREAD_SIZE); | |
234 | ||
235 | tsk->stack_vm_area = s; | |
236 | tsk->stack = s->addr; | |
237 | return s->addr; | |
238 | } | |
239 | ||
240 | /* | |
241 | * Allocated stacks are cached and later reused by new threads, | |
242 | * so memcg accounting is performed manually on assigning/releasing | |
243 | * stacks to tasks. Drop __GFP_ACCOUNT. | |
244 | */ | |
245 | stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, | |
246 | VMALLOC_START, VMALLOC_END, | |
247 | THREADINFO_GFP & ~__GFP_ACCOUNT, | |
248 | PAGE_KERNEL, | |
249 | 0, node, __builtin_return_address(0)); | |
250 | ||
251 | /* | |
252 | * We can't call find_vm_area() in interrupt context, and | |
253 | * free_thread_stack() can be called in interrupt context, | |
254 | * so cache the vm_struct. | |
255 | */ | |
256 | if (stack) { | |
257 | tsk->stack_vm_area = find_vm_area(stack); | |
258 | tsk->stack = stack; | |
259 | } | |
260 | return stack; | |
261 | #else | |
262 | struct page *page = alloc_pages_node(node, THREADINFO_GFP, | |
263 | THREAD_SIZE_ORDER); | |
264 | ||
265 | if (likely(page)) { | |
266 | tsk->stack = kasan_reset_tag(page_address(page)); | |
267 | return tsk->stack; | |
268 | } | |
269 | return NULL; | |
270 | #endif | |
271 | } | |
272 | ||
273 | static inline void free_thread_stack(struct task_struct *tsk) | |
274 | { | |
275 | #ifdef CONFIG_VMAP_STACK | |
276 | struct vm_struct *vm = task_stack_vm_area(tsk); | |
277 | ||
278 | if (vm) { | |
279 | int i; | |
280 | ||
281 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) | |
282 | memcg_kmem_uncharge_page(vm->pages[i], 0); | |
283 | ||
284 | for (i = 0; i < NR_CACHED_STACKS; i++) { | |
285 | if (this_cpu_cmpxchg(cached_stacks[i], | |
286 | NULL, tsk->stack_vm_area) != NULL) | |
287 | continue; | |
288 | ||
289 | return; | |
290 | } | |
291 | ||
292 | vfree_atomic(tsk->stack); | |
293 | return; | |
294 | } | |
295 | #endif | |
296 | ||
297 | __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER); | |
298 | } | |
299 | # else | |
300 | static struct kmem_cache *thread_stack_cache; | |
301 | ||
302 | static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, | |
303 | int node) | |
304 | { | |
305 | unsigned long *stack; | |
306 | stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); | |
307 | stack = kasan_reset_tag(stack); | |
308 | tsk->stack = stack; | |
309 | return stack; | |
310 | } | |
311 | ||
312 | static void free_thread_stack(struct task_struct *tsk) | |
313 | { | |
314 | kmem_cache_free(thread_stack_cache, tsk->stack); | |
315 | } | |
316 | ||
317 | void thread_stack_cache_init(void) | |
318 | { | |
319 | thread_stack_cache = kmem_cache_create_usercopy("thread_stack", | |
320 | THREAD_SIZE, THREAD_SIZE, 0, 0, | |
321 | THREAD_SIZE, NULL); | |
322 | BUG_ON(thread_stack_cache == NULL); | |
323 | } | |
324 | # endif | |
325 | #endif | |
326 | ||
327 | /* SLAB cache for signal_struct structures (tsk->signal) */ | |
328 | static struct kmem_cache *signal_cachep; | |
329 | ||
330 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ | |
331 | struct kmem_cache *sighand_cachep; | |
332 | ||
333 | /* SLAB cache for files_struct structures (tsk->files) */ | |
334 | struct kmem_cache *files_cachep; | |
335 | ||
336 | /* SLAB cache for fs_struct structures (tsk->fs) */ | |
337 | struct kmem_cache *fs_cachep; | |
338 | ||
339 | /* SLAB cache for vm_area_struct structures */ | |
340 | static struct kmem_cache *vm_area_cachep; | |
341 | ||
342 | /* SLAB cache for mm_struct structures (tsk->mm) */ | |
343 | static struct kmem_cache *mm_cachep; | |
344 | ||
345 | struct vm_area_struct *vm_area_alloc(struct mm_struct *mm) | |
346 | { | |
347 | struct vm_area_struct *vma; | |
348 | ||
349 | vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
350 | if (vma) | |
351 | vma_init(vma, mm); | |
352 | return vma; | |
353 | } | |
354 | ||
355 | struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) | |
356 | { | |
357 | struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
358 | ||
359 | if (new) { | |
360 | ASSERT_EXCLUSIVE_WRITER(orig->vm_flags); | |
361 | ASSERT_EXCLUSIVE_WRITER(orig->vm_file); | |
362 | /* | |
363 | * orig->shared.rb may be modified concurrently, but the clone | |
364 | * will be reinitialized. | |
365 | */ | |
366 | *new = data_race(*orig); | |
367 | INIT_LIST_HEAD(&new->anon_vma_chain); | |
368 | new->vm_next = new->vm_prev = NULL; | |
369 | } | |
370 | return new; | |
371 | } | |
372 | ||
373 | void vm_area_free(struct vm_area_struct *vma) | |
374 | { | |
375 | kmem_cache_free(vm_area_cachep, vma); | |
376 | } | |
377 | ||
378 | static void account_kernel_stack(struct task_struct *tsk, int account) | |
379 | { | |
380 | void *stack = task_stack_page(tsk); | |
381 | struct vm_struct *vm = task_stack_vm_area(tsk); | |
382 | ||
383 | if (vm) { | |
384 | int i; | |
385 | ||
386 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) | |
387 | mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB, | |
388 | account * (PAGE_SIZE / 1024)); | |
389 | } else { | |
390 | /* All stack pages are in the same node. */ | |
391 | mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB, | |
392 | account * (THREAD_SIZE / 1024)); | |
393 | } | |
394 | } | |
395 | ||
396 | static int memcg_charge_kernel_stack(struct task_struct *tsk) | |
397 | { | |
398 | #ifdef CONFIG_VMAP_STACK | |
399 | struct vm_struct *vm = task_stack_vm_area(tsk); | |
400 | int ret; | |
401 | ||
402 | BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0); | |
403 | ||
404 | if (vm) { | |
405 | int i; | |
406 | ||
407 | BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE); | |
408 | ||
409 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) { | |
410 | /* | |
411 | * If memcg_kmem_charge_page() fails, page's | |
412 | * memory cgroup pointer is NULL, and | |
413 | * memcg_kmem_uncharge_page() in free_thread_stack() | |
414 | * will ignore this page. | |
415 | */ | |
416 | ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, | |
417 | 0); | |
418 | if (ret) | |
419 | return ret; | |
420 | } | |
421 | } | |
422 | #endif | |
423 | return 0; | |
424 | } | |
425 | ||
426 | static void release_task_stack(struct task_struct *tsk) | |
427 | { | |
428 | if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD)) | |
429 | return; /* Better to leak the stack than to free prematurely */ | |
430 | ||
431 | account_kernel_stack(tsk, -1); | |
432 | free_thread_stack(tsk); | |
433 | tsk->stack = NULL; | |
434 | #ifdef CONFIG_VMAP_STACK | |
435 | tsk->stack_vm_area = NULL; | |
436 | #endif | |
437 | } | |
438 | ||
439 | #ifdef CONFIG_THREAD_INFO_IN_TASK | |
440 | void put_task_stack(struct task_struct *tsk) | |
441 | { | |
442 | if (refcount_dec_and_test(&tsk->stack_refcount)) | |
443 | release_task_stack(tsk); | |
444 | } | |
445 | #endif | |
446 | ||
447 | void free_task(struct task_struct *tsk) | |
448 | { | |
449 | scs_release(tsk); | |
450 | ||
451 | #ifndef CONFIG_THREAD_INFO_IN_TASK | |
452 | /* | |
453 | * The task is finally done with both the stack and thread_info, | |
454 | * so free both. | |
455 | */ | |
456 | release_task_stack(tsk); | |
457 | #else | |
458 | /* | |
459 | * If the task had a separate stack allocation, it should be gone | |
460 | * by now. | |
461 | */ | |
462 | WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0); | |
463 | #endif | |
464 | rt_mutex_debug_task_free(tsk); | |
465 | ftrace_graph_exit_task(tsk); | |
466 | arch_release_task_struct(tsk); | |
467 | if (tsk->flags & PF_KTHREAD) | |
468 | free_kthread_struct(tsk); | |
469 | free_task_struct(tsk); | |
470 | } | |
471 | EXPORT_SYMBOL(free_task); | |
472 | ||
473 | #ifdef CONFIG_MMU | |
474 | static __latent_entropy int dup_mmap(struct mm_struct *mm, | |
475 | struct mm_struct *oldmm) | |
476 | { | |
477 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; | |
478 | struct rb_node **rb_link, *rb_parent; | |
479 | int retval; | |
480 | unsigned long charge; | |
481 | LIST_HEAD(uf); | |
482 | ||
483 | uprobe_start_dup_mmap(); | |
484 | if (mmap_write_lock_killable(oldmm)) { | |
485 | retval = -EINTR; | |
486 | goto fail_uprobe_end; | |
487 | } | |
488 | flush_cache_dup_mm(oldmm); | |
489 | uprobe_dup_mmap(oldmm, mm); | |
490 | /* | |
491 | * Not linked in yet - no deadlock potential: | |
492 | */ | |
493 | mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING); | |
494 | ||
495 | /* No ordering required: file already has been exposed. */ | |
496 | RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); | |
497 | ||
498 | mm->total_vm = oldmm->total_vm; | |
499 | mm->data_vm = oldmm->data_vm; | |
500 | mm->exec_vm = oldmm->exec_vm; | |
501 | mm->stack_vm = oldmm->stack_vm; | |
502 | ||
503 | rb_link = &mm->mm_rb.rb_node; | |
504 | rb_parent = NULL; | |
505 | pprev = &mm->mmap; | |
506 | retval = ksm_fork(mm, oldmm); | |
507 | if (retval) | |
508 | goto out; | |
509 | retval = khugepaged_fork(mm, oldmm); | |
510 | if (retval) | |
511 | goto out; | |
512 | ||
513 | prev = NULL; | |
514 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { | |
515 | struct file *file; | |
516 | ||
517 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
518 | vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); | |
519 | continue; | |
520 | } | |
521 | charge = 0; | |
522 | /* | |
523 | * Don't duplicate many vmas if we've been oom-killed (for | |
524 | * example) | |
525 | */ | |
526 | if (fatal_signal_pending(current)) { | |
527 | retval = -EINTR; | |
528 | goto out; | |
529 | } | |
530 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
531 | unsigned long len = vma_pages(mpnt); | |
532 | ||
533 | if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ | |
534 | goto fail_nomem; | |
535 | charge = len; | |
536 | } | |
537 | tmp = vm_area_dup(mpnt); | |
538 | if (!tmp) | |
539 | goto fail_nomem; | |
540 | retval = vma_dup_policy(mpnt, tmp); | |
541 | if (retval) | |
542 | goto fail_nomem_policy; | |
543 | tmp->vm_mm = mm; | |
544 | retval = dup_userfaultfd(tmp, &uf); | |
545 | if (retval) | |
546 | goto fail_nomem_anon_vma_fork; | |
547 | if (tmp->vm_flags & VM_WIPEONFORK) { | |
548 | /* | |
549 | * VM_WIPEONFORK gets a clean slate in the child. | |
550 | * Don't prepare anon_vma until fault since we don't | |
551 | * copy page for current vma. | |
552 | */ | |
553 | tmp->anon_vma = NULL; | |
554 | } else if (anon_vma_fork(tmp, mpnt)) | |
555 | goto fail_nomem_anon_vma_fork; | |
556 | tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); | |
557 | file = tmp->vm_file; | |
558 | if (file) { | |
559 | struct inode *inode = file_inode(file); | |
560 | struct address_space *mapping = file->f_mapping; | |
561 | ||
562 | get_file(file); | |
563 | if (tmp->vm_flags & VM_DENYWRITE) | |
564 | put_write_access(inode); | |
565 | i_mmap_lock_write(mapping); | |
566 | if (tmp->vm_flags & VM_SHARED) | |
567 | mapping_allow_writable(mapping); | |
568 | flush_dcache_mmap_lock(mapping); | |
569 | /* insert tmp into the share list, just after mpnt */ | |
570 | vma_interval_tree_insert_after(tmp, mpnt, | |
571 | &mapping->i_mmap); | |
572 | flush_dcache_mmap_unlock(mapping); | |
573 | i_mmap_unlock_write(mapping); | |
574 | } | |
575 | ||
576 | /* | |
577 | * Clear hugetlb-related page reserves for children. This only | |
578 | * affects MAP_PRIVATE mappings. Faults generated by the child | |
579 | * are not guaranteed to succeed, even if read-only | |
580 | */ | |
581 | if (is_vm_hugetlb_page(tmp)) | |
582 | reset_vma_resv_huge_pages(tmp); | |
583 | ||
584 | /* | |
585 | * Link in the new vma and copy the page table entries. | |
586 | */ | |
587 | *pprev = tmp; | |
588 | pprev = &tmp->vm_next; | |
589 | tmp->vm_prev = prev; | |
590 | prev = tmp; | |
591 | ||
592 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
593 | rb_link = &tmp->vm_rb.rb_right; | |
594 | rb_parent = &tmp->vm_rb; | |
595 | ||
596 | mm->map_count++; | |
597 | if (!(tmp->vm_flags & VM_WIPEONFORK)) | |
598 | retval = copy_page_range(tmp, mpnt); | |
599 | ||
600 | if (tmp->vm_ops && tmp->vm_ops->open) | |
601 | tmp->vm_ops->open(tmp); | |
602 | ||
603 | if (retval) | |
604 | goto out; | |
605 | } | |
606 | /* a new mm has just been created */ | |
607 | retval = arch_dup_mmap(oldmm, mm); | |
608 | out: | |
609 | mmap_write_unlock(mm); | |
610 | flush_tlb_mm(oldmm); | |
611 | mmap_write_unlock(oldmm); | |
612 | dup_userfaultfd_complete(&uf); | |
613 | fail_uprobe_end: | |
614 | uprobe_end_dup_mmap(); | |
615 | return retval; | |
616 | fail_nomem_anon_vma_fork: | |
617 | mpol_put(vma_policy(tmp)); | |
618 | fail_nomem_policy: | |
619 | vm_area_free(tmp); | |
620 | fail_nomem: | |
621 | retval = -ENOMEM; | |
622 | vm_unacct_memory(charge); | |
623 | goto out; | |
624 | } | |
625 | ||
626 | static inline int mm_alloc_pgd(struct mm_struct *mm) | |
627 | { | |
628 | mm->pgd = pgd_alloc(mm); | |
629 | if (unlikely(!mm->pgd)) | |
630 | return -ENOMEM; | |
631 | return 0; | |
632 | } | |
633 | ||
634 | static inline void mm_free_pgd(struct mm_struct *mm) | |
635 | { | |
636 | pgd_free(mm, mm->pgd); | |
637 | } | |
638 | #else | |
639 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) | |
640 | { | |
641 | mmap_write_lock(oldmm); | |
642 | RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); | |
643 | mmap_write_unlock(oldmm); | |
644 | return 0; | |
645 | } | |
646 | #define mm_alloc_pgd(mm) (0) | |
647 | #define mm_free_pgd(mm) | |
648 | #endif /* CONFIG_MMU */ | |
649 | ||
650 | static void check_mm(struct mm_struct *mm) | |
651 | { | |
652 | int i; | |
653 | ||
654 | BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS, | |
655 | "Please make sure 'struct resident_page_types[]' is updated as well"); | |
656 | ||
657 | for (i = 0; i < NR_MM_COUNTERS; i++) { | |
658 | long x = atomic_long_read(&mm->rss_stat.count[i]); | |
659 | ||
660 | if (unlikely(x)) | |
661 | pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n", | |
662 | mm, resident_page_types[i], x); | |
663 | } | |
664 | ||
665 | if (mm_pgtables_bytes(mm)) | |
666 | pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n", | |
667 | mm_pgtables_bytes(mm)); | |
668 | ||
669 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS | |
670 | VM_BUG_ON_MM(mm->pmd_huge_pte, mm); | |
671 | #endif | |
672 | } | |
673 | ||
674 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) | |
675 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
676 | ||
677 | /* | |
678 | * Called when the last reference to the mm | |
679 | * is dropped: either by a lazy thread or by | |
680 | * mmput. Free the page directory and the mm. | |
681 | */ | |
682 | void __mmdrop(struct mm_struct *mm) | |
683 | { | |
684 | BUG_ON(mm == &init_mm); | |
685 | WARN_ON_ONCE(mm == current->mm); | |
686 | WARN_ON_ONCE(mm == current->active_mm); | |
687 | mm_free_pgd(mm); | |
688 | destroy_context(mm); | |
689 | mmu_notifier_subscriptions_destroy(mm); | |
690 | check_mm(mm); | |
691 | put_user_ns(mm->user_ns); | |
692 | free_mm(mm); | |
693 | } | |
694 | EXPORT_SYMBOL_GPL(__mmdrop); | |
695 | ||
696 | static void mmdrop_async_fn(struct work_struct *work) | |
697 | { | |
698 | struct mm_struct *mm; | |
699 | ||
700 | mm = container_of(work, struct mm_struct, async_put_work); | |
701 | __mmdrop(mm); | |
702 | } | |
703 | ||
704 | static void mmdrop_async(struct mm_struct *mm) | |
705 | { | |
706 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) { | |
707 | INIT_WORK(&mm->async_put_work, mmdrop_async_fn); | |
708 | schedule_work(&mm->async_put_work); | |
709 | } | |
710 | } | |
711 | ||
712 | static inline void free_signal_struct(struct signal_struct *sig) | |
713 | { | |
714 | taskstats_tgid_free(sig); | |
715 | sched_autogroup_exit(sig); | |
716 | /* | |
717 | * __mmdrop is not safe to call from softirq context on x86 due to | |
718 | * pgd_dtor so postpone it to the async context | |
719 | */ | |
720 | if (sig->oom_mm) | |
721 | mmdrop_async(sig->oom_mm); | |
722 | kmem_cache_free(signal_cachep, sig); | |
723 | } | |
724 | ||
725 | static inline void put_signal_struct(struct signal_struct *sig) | |
726 | { | |
727 | if (refcount_dec_and_test(&sig->sigcnt)) | |
728 | free_signal_struct(sig); | |
729 | } | |
730 | ||
731 | void __put_task_struct(struct task_struct *tsk) | |
732 | { | |
733 | WARN_ON(!tsk->exit_state); | |
734 | WARN_ON(refcount_read(&tsk->usage)); | |
735 | WARN_ON(tsk == current); | |
736 | ||
737 | io_uring_free(tsk); | |
738 | cgroup_free(tsk); | |
739 | task_numa_free(tsk, true); | |
740 | security_task_free(tsk); | |
741 | bpf_task_storage_free(tsk); | |
742 | exit_creds(tsk); | |
743 | delayacct_tsk_free(tsk); | |
744 | put_signal_struct(tsk->signal); | |
745 | sched_core_free(tsk); | |
746 | ||
747 | if (!profile_handoff_task(tsk)) | |
748 | free_task(tsk); | |
749 | } | |
750 | EXPORT_SYMBOL_GPL(__put_task_struct); | |
751 | ||
752 | void __init __weak arch_task_cache_init(void) { } | |
753 | ||
754 | /* | |
755 | * set_max_threads | |
756 | */ | |
757 | static void set_max_threads(unsigned int max_threads_suggested) | |
758 | { | |
759 | u64 threads; | |
760 | unsigned long nr_pages = totalram_pages(); | |
761 | ||
762 | /* | |
763 | * The number of threads shall be limited such that the thread | |
764 | * structures may only consume a small part of the available memory. | |
765 | */ | |
766 | if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64) | |
767 | threads = MAX_THREADS; | |
768 | else | |
769 | threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE, | |
770 | (u64) THREAD_SIZE * 8UL); | |
771 | ||
772 | if (threads > max_threads_suggested) | |
773 | threads = max_threads_suggested; | |
774 | ||
775 | max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS); | |
776 | } | |
777 | ||
778 | #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT | |
779 | /* Initialized by the architecture: */ | |
780 | int arch_task_struct_size __read_mostly; | |
781 | #endif | |
782 | ||
783 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR | |
784 | static void task_struct_whitelist(unsigned long *offset, unsigned long *size) | |
785 | { | |
786 | /* Fetch thread_struct whitelist for the architecture. */ | |
787 | arch_thread_struct_whitelist(offset, size); | |
788 | ||
789 | /* | |
790 | * Handle zero-sized whitelist or empty thread_struct, otherwise | |
791 | * adjust offset to position of thread_struct in task_struct. | |
792 | */ | |
793 | if (unlikely(*size == 0)) | |
794 | *offset = 0; | |
795 | else | |
796 | *offset += offsetof(struct task_struct, thread); | |
797 | } | |
798 | #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */ | |
799 | ||
800 | void __init fork_init(void) | |
801 | { | |
802 | int i; | |
803 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR | |
804 | #ifndef ARCH_MIN_TASKALIGN | |
805 | #define ARCH_MIN_TASKALIGN 0 | |
806 | #endif | |
807 | int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN); | |
808 | unsigned long useroffset, usersize; | |
809 | ||
810 | /* create a slab on which task_structs can be allocated */ | |
811 | task_struct_whitelist(&useroffset, &usersize); | |
812 | task_struct_cachep = kmem_cache_create_usercopy("task_struct", | |
813 | arch_task_struct_size, align, | |
814 | SLAB_PANIC|SLAB_ACCOUNT, | |
815 | useroffset, usersize, NULL); | |
816 | #endif | |
817 | ||
818 | /* do the arch specific task caches init */ | |
819 | arch_task_cache_init(); | |
820 | ||
821 | set_max_threads(MAX_THREADS); | |
822 | ||
823 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; | |
824 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; | |
825 | init_task.signal->rlim[RLIMIT_SIGPENDING] = | |
826 | init_task.signal->rlim[RLIMIT_NPROC]; | |
827 | ||
828 | for (i = 0; i < UCOUNT_COUNTS; i++) | |
829 | init_user_ns.ucount_max[i] = max_threads/2; | |
830 | ||
831 | #ifdef CONFIG_VMAP_STACK | |
832 | cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", | |
833 | NULL, free_vm_stack_cache); | |
834 | #endif | |
835 | ||
836 | scs_init(); | |
837 | ||
838 | lockdep_init_task(&init_task); | |
839 | uprobes_init(); | |
840 | } | |
841 | ||
842 | int __weak arch_dup_task_struct(struct task_struct *dst, | |
843 | struct task_struct *src) | |
844 | { | |
845 | *dst = *src; | |
846 | return 0; | |
847 | } | |
848 | ||
849 | void set_task_stack_end_magic(struct task_struct *tsk) | |
850 | { | |
851 | unsigned long *stackend; | |
852 | ||
853 | stackend = end_of_stack(tsk); | |
854 | *stackend = STACK_END_MAGIC; /* for overflow detection */ | |
855 | } | |
856 | ||
857 | static struct task_struct *dup_task_struct(struct task_struct *orig, int node) | |
858 | { | |
859 | struct task_struct *tsk; | |
860 | unsigned long *stack; | |
861 | struct vm_struct *stack_vm_area __maybe_unused; | |
862 | int err; | |
863 | ||
864 | if (node == NUMA_NO_NODE) | |
865 | node = tsk_fork_get_node(orig); | |
866 | tsk = alloc_task_struct_node(node); | |
867 | if (!tsk) | |
868 | return NULL; | |
869 | ||
870 | stack = alloc_thread_stack_node(tsk, node); | |
871 | if (!stack) | |
872 | goto free_tsk; | |
873 | ||
874 | if (memcg_charge_kernel_stack(tsk)) | |
875 | goto free_stack; | |
876 | ||
877 | stack_vm_area = task_stack_vm_area(tsk); | |
878 | ||
879 | err = arch_dup_task_struct(tsk, orig); | |
880 | ||
881 | /* | |
882 | * arch_dup_task_struct() clobbers the stack-related fields. Make | |
883 | * sure they're properly initialized before using any stack-related | |
884 | * functions again. | |
885 | */ | |
886 | tsk->stack = stack; | |
887 | #ifdef CONFIG_VMAP_STACK | |
888 | tsk->stack_vm_area = stack_vm_area; | |
889 | #endif | |
890 | #ifdef CONFIG_THREAD_INFO_IN_TASK | |
891 | refcount_set(&tsk->stack_refcount, 1); | |
892 | #endif | |
893 | ||
894 | if (err) | |
895 | goto free_stack; | |
896 | ||
897 | err = scs_prepare(tsk, node); | |
898 | if (err) | |
899 | goto free_stack; | |
900 | ||
901 | #ifdef CONFIG_SECCOMP | |
902 | /* | |
903 | * We must handle setting up seccomp filters once we're under | |
904 | * the sighand lock in case orig has changed between now and | |
905 | * then. Until then, filter must be NULL to avoid messing up | |
906 | * the usage counts on the error path calling free_task. | |
907 | */ | |
908 | tsk->seccomp.filter = NULL; | |
909 | #endif | |
910 | ||
911 | setup_thread_stack(tsk, orig); | |
912 | clear_user_return_notifier(tsk); | |
913 | clear_tsk_need_resched(tsk); | |
914 | set_task_stack_end_magic(tsk); | |
915 | clear_syscall_work_syscall_user_dispatch(tsk); | |
916 | ||
917 | #ifdef CONFIG_STACKPROTECTOR | |
918 | tsk->stack_canary = get_random_canary(); | |
919 | #endif | |
920 | if (orig->cpus_ptr == &orig->cpus_mask) | |
921 | tsk->cpus_ptr = &tsk->cpus_mask; | |
922 | ||
923 | /* | |
924 | * One for the user space visible state that goes away when reaped. | |
925 | * One for the scheduler. | |
926 | */ | |
927 | refcount_set(&tsk->rcu_users, 2); | |
928 | /* One for the rcu users */ | |
929 | refcount_set(&tsk->usage, 1); | |
930 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
931 | tsk->btrace_seq = 0; | |
932 | #endif | |
933 | tsk->splice_pipe = NULL; | |
934 | tsk->task_frag.page = NULL; | |
935 | tsk->wake_q.next = NULL; | |
936 | tsk->pf_io_worker = NULL; | |
937 | ||
938 | account_kernel_stack(tsk, 1); | |
939 | ||
940 | kcov_task_init(tsk); | |
941 | kmap_local_fork(tsk); | |
942 | ||
943 | #ifdef CONFIG_FAULT_INJECTION | |
944 | tsk->fail_nth = 0; | |
945 | #endif | |
946 | ||
947 | #ifdef CONFIG_BLK_CGROUP | |
948 | tsk->throttle_queue = NULL; | |
949 | tsk->use_memdelay = 0; | |
950 | #endif | |
951 | ||
952 | #ifdef CONFIG_MEMCG | |
953 | tsk->active_memcg = NULL; | |
954 | #endif | |
955 | return tsk; | |
956 | ||
957 | free_stack: | |
958 | free_thread_stack(tsk); | |
959 | free_tsk: | |
960 | free_task_struct(tsk); | |
961 | return NULL; | |
962 | } | |
963 | ||
964 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
965 | ||
966 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; | |
967 | ||
968 | static int __init coredump_filter_setup(char *s) | |
969 | { | |
970 | default_dump_filter = | |
971 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & | |
972 | MMF_DUMP_FILTER_MASK; | |
973 | return 1; | |
974 | } | |
975 | ||
976 | __setup("coredump_filter=", coredump_filter_setup); | |
977 | ||
978 | #include <linux/init_task.h> | |
979 | ||
980 | static void mm_init_aio(struct mm_struct *mm) | |
981 | { | |
982 | #ifdef CONFIG_AIO | |
983 | spin_lock_init(&mm->ioctx_lock); | |
984 | mm->ioctx_table = NULL; | |
985 | #endif | |
986 | } | |
987 | ||
988 | static __always_inline void mm_clear_owner(struct mm_struct *mm, | |
989 | struct task_struct *p) | |
990 | { | |
991 | #ifdef CONFIG_MEMCG | |
992 | if (mm->owner == p) | |
993 | WRITE_ONCE(mm->owner, NULL); | |
994 | #endif | |
995 | } | |
996 | ||
997 | static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) | |
998 | { | |
999 | #ifdef CONFIG_MEMCG | |
1000 | mm->owner = p; | |
1001 | #endif | |
1002 | } | |
1003 | ||
1004 | static void mm_init_pasid(struct mm_struct *mm) | |
1005 | { | |
1006 | #ifdef CONFIG_IOMMU_SUPPORT | |
1007 | mm->pasid = INIT_PASID; | |
1008 | #endif | |
1009 | } | |
1010 | ||
1011 | static void mm_init_uprobes_state(struct mm_struct *mm) | |
1012 | { | |
1013 | #ifdef CONFIG_UPROBES | |
1014 | mm->uprobes_state.xol_area = NULL; | |
1015 | #endif | |
1016 | } | |
1017 | ||
1018 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, | |
1019 | struct user_namespace *user_ns) | |
1020 | { | |
1021 | mm->mmap = NULL; | |
1022 | mm->mm_rb = RB_ROOT; | |
1023 | mm->vmacache_seqnum = 0; | |
1024 | atomic_set(&mm->mm_users, 1); | |
1025 | atomic_set(&mm->mm_count, 1); | |
1026 | seqcount_init(&mm->write_protect_seq); | |
1027 | mmap_init_lock(mm); | |
1028 | INIT_LIST_HEAD(&mm->mmlist); | |
1029 | mm->core_state = NULL; | |
1030 | mm_pgtables_bytes_init(mm); | |
1031 | mm->map_count = 0; | |
1032 | mm->locked_vm = 0; | |
1033 | atomic_set(&mm->has_pinned, 0); | |
1034 | atomic64_set(&mm->pinned_vm, 0); | |
1035 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); | |
1036 | spin_lock_init(&mm->page_table_lock); | |
1037 | spin_lock_init(&mm->arg_lock); | |
1038 | mm_init_cpumask(mm); | |
1039 | mm_init_aio(mm); | |
1040 | mm_init_owner(mm, p); | |
1041 | mm_init_pasid(mm); | |
1042 | RCU_INIT_POINTER(mm->exe_file, NULL); | |
1043 | mmu_notifier_subscriptions_init(mm); | |
1044 | init_tlb_flush_pending(mm); | |
1045 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS | |
1046 | mm->pmd_huge_pte = NULL; | |
1047 | #endif | |
1048 | mm_init_uprobes_state(mm); | |
1049 | ||
1050 | if (current->mm) { | |
1051 | mm->flags = current->mm->flags & MMF_INIT_MASK; | |
1052 | mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; | |
1053 | } else { | |
1054 | mm->flags = default_dump_filter; | |
1055 | mm->def_flags = 0; | |
1056 | } | |
1057 | ||
1058 | if (mm_alloc_pgd(mm)) | |
1059 | goto fail_nopgd; | |
1060 | ||
1061 | if (init_new_context(p, mm)) | |
1062 | goto fail_nocontext; | |
1063 | ||
1064 | mm->user_ns = get_user_ns(user_ns); | |
1065 | return mm; | |
1066 | ||
1067 | fail_nocontext: | |
1068 | mm_free_pgd(mm); | |
1069 | fail_nopgd: | |
1070 | free_mm(mm); | |
1071 | return NULL; | |
1072 | } | |
1073 | ||
1074 | /* | |
1075 | * Allocate and initialize an mm_struct. | |
1076 | */ | |
1077 | struct mm_struct *mm_alloc(void) | |
1078 | { | |
1079 | struct mm_struct *mm; | |
1080 | ||
1081 | mm = allocate_mm(); | |
1082 | if (!mm) | |
1083 | return NULL; | |
1084 | ||
1085 | memset(mm, 0, sizeof(*mm)); | |
1086 | return mm_init(mm, current, current_user_ns()); | |
1087 | } | |
1088 | ||
1089 | static inline void __mmput(struct mm_struct *mm) | |
1090 | { | |
1091 | VM_BUG_ON(atomic_read(&mm->mm_users)); | |
1092 | ||
1093 | uprobe_clear_state(mm); | |
1094 | exit_aio(mm); | |
1095 | ksm_exit(mm); | |
1096 | khugepaged_exit(mm); /* must run before exit_mmap */ | |
1097 | exit_mmap(mm); | |
1098 | mm_put_huge_zero_page(mm); | |
1099 | set_mm_exe_file(mm, NULL); | |
1100 | if (!list_empty(&mm->mmlist)) { | |
1101 | spin_lock(&mmlist_lock); | |
1102 | list_del(&mm->mmlist); | |
1103 | spin_unlock(&mmlist_lock); | |
1104 | } | |
1105 | if (mm->binfmt) | |
1106 | module_put(mm->binfmt->module); | |
1107 | mmdrop(mm); | |
1108 | } | |
1109 | ||
1110 | /* | |
1111 | * Decrement the use count and release all resources for an mm. | |
1112 | */ | |
1113 | void mmput(struct mm_struct *mm) | |
1114 | { | |
1115 | might_sleep(); | |
1116 | ||
1117 | if (atomic_dec_and_test(&mm->mm_users)) | |
1118 | __mmput(mm); | |
1119 | } | |
1120 | EXPORT_SYMBOL_GPL(mmput); | |
1121 | ||
1122 | #ifdef CONFIG_MMU | |
1123 | static void mmput_async_fn(struct work_struct *work) | |
1124 | { | |
1125 | struct mm_struct *mm = container_of(work, struct mm_struct, | |
1126 | async_put_work); | |
1127 | ||
1128 | __mmput(mm); | |
1129 | } | |
1130 | ||
1131 | void mmput_async(struct mm_struct *mm) | |
1132 | { | |
1133 | if (atomic_dec_and_test(&mm->mm_users)) { | |
1134 | INIT_WORK(&mm->async_put_work, mmput_async_fn); | |
1135 | schedule_work(&mm->async_put_work); | |
1136 | } | |
1137 | } | |
1138 | #endif | |
1139 | ||
1140 | /** | |
1141 | * set_mm_exe_file - change a reference to the mm's executable file | |
1142 | * | |
1143 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe). | |
1144 | * | |
1145 | * Main users are mmput() and sys_execve(). Callers prevent concurrent | |
1146 | * invocations: in mmput() nobody alive left, in execve task is single | |
1147 | * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the | |
1148 | * mm->exe_file, but does so without using set_mm_exe_file() in order | |
1149 | * to avoid the need for any locks. | |
1150 | */ | |
1151 | void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) | |
1152 | { | |
1153 | struct file *old_exe_file; | |
1154 | ||
1155 | /* | |
1156 | * It is safe to dereference the exe_file without RCU as | |
1157 | * this function is only called if nobody else can access | |
1158 | * this mm -- see comment above for justification. | |
1159 | */ | |
1160 | old_exe_file = rcu_dereference_raw(mm->exe_file); | |
1161 | ||
1162 | if (new_exe_file) | |
1163 | get_file(new_exe_file); | |
1164 | rcu_assign_pointer(mm->exe_file, new_exe_file); | |
1165 | if (old_exe_file) | |
1166 | fput(old_exe_file); | |
1167 | } | |
1168 | ||
1169 | /** | |
1170 | * get_mm_exe_file - acquire a reference to the mm's executable file | |
1171 | * | |
1172 | * Returns %NULL if mm has no associated executable file. | |
1173 | * User must release file via fput(). | |
1174 | */ | |
1175 | struct file *get_mm_exe_file(struct mm_struct *mm) | |
1176 | { | |
1177 | struct file *exe_file; | |
1178 | ||
1179 | rcu_read_lock(); | |
1180 | exe_file = rcu_dereference(mm->exe_file); | |
1181 | if (exe_file && !get_file_rcu(exe_file)) | |
1182 | exe_file = NULL; | |
1183 | rcu_read_unlock(); | |
1184 | return exe_file; | |
1185 | } | |
1186 | EXPORT_SYMBOL(get_mm_exe_file); | |
1187 | ||
1188 | /** | |
1189 | * get_task_exe_file - acquire a reference to the task's executable file | |
1190 | * | |
1191 | * Returns %NULL if task's mm (if any) has no associated executable file or | |
1192 | * this is a kernel thread with borrowed mm (see the comment above get_task_mm). | |
1193 | * User must release file via fput(). | |
1194 | */ | |
1195 | struct file *get_task_exe_file(struct task_struct *task) | |
1196 | { | |
1197 | struct file *exe_file = NULL; | |
1198 | struct mm_struct *mm; | |
1199 | ||
1200 | task_lock(task); | |
1201 | mm = task->mm; | |
1202 | if (mm) { | |
1203 | if (!(task->flags & PF_KTHREAD)) | |
1204 | exe_file = get_mm_exe_file(mm); | |
1205 | } | |
1206 | task_unlock(task); | |
1207 | return exe_file; | |
1208 | } | |
1209 | EXPORT_SYMBOL(get_task_exe_file); | |
1210 | ||
1211 | /** | |
1212 | * get_task_mm - acquire a reference to the task's mm | |
1213 | * | |
1214 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning | |
1215 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
1216 | * to do its AIO) is not set and if so returns a reference to it, after | |
1217 | * bumping up the use count. User must release the mm via mmput() | |
1218 | * after use. Typically used by /proc and ptrace. | |
1219 | */ | |
1220 | struct mm_struct *get_task_mm(struct task_struct *task) | |
1221 | { | |
1222 | struct mm_struct *mm; | |
1223 | ||
1224 | task_lock(task); | |
1225 | mm = task->mm; | |
1226 | if (mm) { | |
1227 | if (task->flags & PF_KTHREAD) | |
1228 | mm = NULL; | |
1229 | else | |
1230 | mmget(mm); | |
1231 | } | |
1232 | task_unlock(task); | |
1233 | return mm; | |
1234 | } | |
1235 | EXPORT_SYMBOL_GPL(get_task_mm); | |
1236 | ||
1237 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) | |
1238 | { | |
1239 | struct mm_struct *mm; | |
1240 | int err; | |
1241 | ||
1242 | err = down_read_killable(&task->signal->exec_update_lock); | |
1243 | if (err) | |
1244 | return ERR_PTR(err); | |
1245 | ||
1246 | mm = get_task_mm(task); | |
1247 | if (mm && mm != current->mm && | |
1248 | !ptrace_may_access(task, mode)) { | |
1249 | mmput(mm); | |
1250 | mm = ERR_PTR(-EACCES); | |
1251 | } | |
1252 | up_read(&task->signal->exec_update_lock); | |
1253 | ||
1254 | return mm; | |
1255 | } | |
1256 | ||
1257 | static void complete_vfork_done(struct task_struct *tsk) | |
1258 | { | |
1259 | struct completion *vfork; | |
1260 | ||
1261 | task_lock(tsk); | |
1262 | vfork = tsk->vfork_done; | |
1263 | if (likely(vfork)) { | |
1264 | tsk->vfork_done = NULL; | |
1265 | complete(vfork); | |
1266 | } | |
1267 | task_unlock(tsk); | |
1268 | } | |
1269 | ||
1270 | static int wait_for_vfork_done(struct task_struct *child, | |
1271 | struct completion *vfork) | |
1272 | { | |
1273 | int killed; | |
1274 | ||
1275 | freezer_do_not_count(); | |
1276 | cgroup_enter_frozen(); | |
1277 | killed = wait_for_completion_killable(vfork); | |
1278 | cgroup_leave_frozen(false); | |
1279 | freezer_count(); | |
1280 | ||
1281 | if (killed) { | |
1282 | task_lock(child); | |
1283 | child->vfork_done = NULL; | |
1284 | task_unlock(child); | |
1285 | } | |
1286 | ||
1287 | put_task_struct(child); | |
1288 | return killed; | |
1289 | } | |
1290 | ||
1291 | /* Please note the differences between mmput and mm_release. | |
1292 | * mmput is called whenever we stop holding onto a mm_struct, | |
1293 | * error success whatever. | |
1294 | * | |
1295 | * mm_release is called after a mm_struct has been removed | |
1296 | * from the current process. | |
1297 | * | |
1298 | * This difference is important for error handling, when we | |
1299 | * only half set up a mm_struct for a new process and need to restore | |
1300 | * the old one. Because we mmput the new mm_struct before | |
1301 | * restoring the old one. . . | |
1302 | * Eric Biederman 10 January 1998 | |
1303 | */ | |
1304 | static void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
1305 | { | |
1306 | uprobe_free_utask(tsk); | |
1307 | ||
1308 | /* Get rid of any cached register state */ | |
1309 | deactivate_mm(tsk, mm); | |
1310 | ||
1311 | /* | |
1312 | * Signal userspace if we're not exiting with a core dump | |
1313 | * because we want to leave the value intact for debugging | |
1314 | * purposes. | |
1315 | */ | |
1316 | if (tsk->clear_child_tid) { | |
1317 | if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) && | |
1318 | atomic_read(&mm->mm_users) > 1) { | |
1319 | /* | |
1320 | * We don't check the error code - if userspace has | |
1321 | * not set up a proper pointer then tough luck. | |
1322 | */ | |
1323 | put_user(0, tsk->clear_child_tid); | |
1324 | do_futex(tsk->clear_child_tid, FUTEX_WAKE, | |
1325 | 1, NULL, NULL, 0, 0); | |
1326 | } | |
1327 | tsk->clear_child_tid = NULL; | |
1328 | } | |
1329 | ||
1330 | /* | |
1331 | * All done, finally we can wake up parent and return this mm to him. | |
1332 | * Also kthread_stop() uses this completion for synchronization. | |
1333 | */ | |
1334 | if (tsk->vfork_done) | |
1335 | complete_vfork_done(tsk); | |
1336 | } | |
1337 | ||
1338 | void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
1339 | { | |
1340 | futex_exit_release(tsk); | |
1341 | mm_release(tsk, mm); | |
1342 | } | |
1343 | ||
1344 | void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
1345 | { | |
1346 | futex_exec_release(tsk); | |
1347 | mm_release(tsk, mm); | |
1348 | } | |
1349 | ||
1350 | /** | |
1351 | * dup_mm() - duplicates an existing mm structure | |
1352 | * @tsk: the task_struct with which the new mm will be associated. | |
1353 | * @oldmm: the mm to duplicate. | |
1354 | * | |
1355 | * Allocates a new mm structure and duplicates the provided @oldmm structure | |
1356 | * content into it. | |
1357 | * | |
1358 | * Return: the duplicated mm or NULL on failure. | |
1359 | */ | |
1360 | static struct mm_struct *dup_mm(struct task_struct *tsk, | |
1361 | struct mm_struct *oldmm) | |
1362 | { | |
1363 | struct mm_struct *mm; | |
1364 | int err; | |
1365 | ||
1366 | mm = allocate_mm(); | |
1367 | if (!mm) | |
1368 | goto fail_nomem; | |
1369 | ||
1370 | memcpy(mm, oldmm, sizeof(*mm)); | |
1371 | ||
1372 | if (!mm_init(mm, tsk, mm->user_ns)) | |
1373 | goto fail_nomem; | |
1374 | ||
1375 | err = dup_mmap(mm, oldmm); | |
1376 | if (err) | |
1377 | goto free_pt; | |
1378 | ||
1379 | mm->hiwater_rss = get_mm_rss(mm); | |
1380 | mm->hiwater_vm = mm->total_vm; | |
1381 | ||
1382 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) | |
1383 | goto free_pt; | |
1384 | ||
1385 | return mm; | |
1386 | ||
1387 | free_pt: | |
1388 | /* don't put binfmt in mmput, we haven't got module yet */ | |
1389 | mm->binfmt = NULL; | |
1390 | mm_init_owner(mm, NULL); | |
1391 | mmput(mm); | |
1392 | ||
1393 | fail_nomem: | |
1394 | return NULL; | |
1395 | } | |
1396 | ||
1397 | static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) | |
1398 | { | |
1399 | struct mm_struct *mm, *oldmm; | |
1400 | ||
1401 | tsk->min_flt = tsk->maj_flt = 0; | |
1402 | tsk->nvcsw = tsk->nivcsw = 0; | |
1403 | #ifdef CONFIG_DETECT_HUNG_TASK | |
1404 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; | |
1405 | tsk->last_switch_time = 0; | |
1406 | #endif | |
1407 | ||
1408 | tsk->mm = NULL; | |
1409 | tsk->active_mm = NULL; | |
1410 | ||
1411 | /* | |
1412 | * Are we cloning a kernel thread? | |
1413 | * | |
1414 | * We need to steal a active VM for that.. | |
1415 | */ | |
1416 | oldmm = current->mm; | |
1417 | if (!oldmm) | |
1418 | return 0; | |
1419 | ||
1420 | /* initialize the new vmacache entries */ | |
1421 | vmacache_flush(tsk); | |
1422 | ||
1423 | if (clone_flags & CLONE_VM) { | |
1424 | mmget(oldmm); | |
1425 | mm = oldmm; | |
1426 | } else { | |
1427 | mm = dup_mm(tsk, current->mm); | |
1428 | if (!mm) | |
1429 | return -ENOMEM; | |
1430 | } | |
1431 | ||
1432 | tsk->mm = mm; | |
1433 | tsk->active_mm = mm; | |
1434 | return 0; | |
1435 | } | |
1436 | ||
1437 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) | |
1438 | { | |
1439 | struct fs_struct *fs = current->fs; | |
1440 | if (clone_flags & CLONE_FS) { | |
1441 | /* tsk->fs is already what we want */ | |
1442 | spin_lock(&fs->lock); | |
1443 | if (fs->in_exec) { | |
1444 | spin_unlock(&fs->lock); | |
1445 | return -EAGAIN; | |
1446 | } | |
1447 | fs->users++; | |
1448 | spin_unlock(&fs->lock); | |
1449 | return 0; | |
1450 | } | |
1451 | tsk->fs = copy_fs_struct(fs); | |
1452 | if (!tsk->fs) | |
1453 | return -ENOMEM; | |
1454 | return 0; | |
1455 | } | |
1456 | ||
1457 | static int copy_files(unsigned long clone_flags, struct task_struct *tsk) | |
1458 | { | |
1459 | struct files_struct *oldf, *newf; | |
1460 | int error = 0; | |
1461 | ||
1462 | /* | |
1463 | * A background process may not have any files ... | |
1464 | */ | |
1465 | oldf = current->files; | |
1466 | if (!oldf) | |
1467 | goto out; | |
1468 | ||
1469 | if (clone_flags & CLONE_FILES) { | |
1470 | atomic_inc(&oldf->count); | |
1471 | goto out; | |
1472 | } | |
1473 | ||
1474 | newf = dup_fd(oldf, NR_OPEN_MAX, &error); | |
1475 | if (!newf) | |
1476 | goto out; | |
1477 | ||
1478 | tsk->files = newf; | |
1479 | error = 0; | |
1480 | out: | |
1481 | return error; | |
1482 | } | |
1483 | ||
1484 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) | |
1485 | { | |
1486 | #ifdef CONFIG_BLOCK | |
1487 | struct io_context *ioc = current->io_context; | |
1488 | struct io_context *new_ioc; | |
1489 | ||
1490 | if (!ioc) | |
1491 | return 0; | |
1492 | /* | |
1493 | * Share io context with parent, if CLONE_IO is set | |
1494 | */ | |
1495 | if (clone_flags & CLONE_IO) { | |
1496 | ioc_task_link(ioc); | |
1497 | tsk->io_context = ioc; | |
1498 | } else if (ioprio_valid(ioc->ioprio)) { | |
1499 | new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); | |
1500 | if (unlikely(!new_ioc)) | |
1501 | return -ENOMEM; | |
1502 | ||
1503 | new_ioc->ioprio = ioc->ioprio; | |
1504 | put_io_context(new_ioc); | |
1505 | } | |
1506 | #endif | |
1507 | return 0; | |
1508 | } | |
1509 | ||
1510 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) | |
1511 | { | |
1512 | struct sighand_struct *sig; | |
1513 | ||
1514 | if (clone_flags & CLONE_SIGHAND) { | |
1515 | refcount_inc(¤t->sighand->count); | |
1516 | return 0; | |
1517 | } | |
1518 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
1519 | RCU_INIT_POINTER(tsk->sighand, sig); | |
1520 | if (!sig) | |
1521 | return -ENOMEM; | |
1522 | ||
1523 | refcount_set(&sig->count, 1); | |
1524 | spin_lock_irq(¤t->sighand->siglock); | |
1525 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
1526 | spin_unlock_irq(¤t->sighand->siglock); | |
1527 | ||
1528 | /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */ | |
1529 | if (clone_flags & CLONE_CLEAR_SIGHAND) | |
1530 | flush_signal_handlers(tsk, 0); | |
1531 | ||
1532 | return 0; | |
1533 | } | |
1534 | ||
1535 | void __cleanup_sighand(struct sighand_struct *sighand) | |
1536 | { | |
1537 | if (refcount_dec_and_test(&sighand->count)) { | |
1538 | signalfd_cleanup(sighand); | |
1539 | /* | |
1540 | * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it | |
1541 | * without an RCU grace period, see __lock_task_sighand(). | |
1542 | */ | |
1543 | kmem_cache_free(sighand_cachep, sighand); | |
1544 | } | |
1545 | } | |
1546 | ||
1547 | /* | |
1548 | * Initialize POSIX timer handling for a thread group. | |
1549 | */ | |
1550 | static void posix_cpu_timers_init_group(struct signal_struct *sig) | |
1551 | { | |
1552 | struct posix_cputimers *pct = &sig->posix_cputimers; | |
1553 | unsigned long cpu_limit; | |
1554 | ||
1555 | cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); | |
1556 | posix_cputimers_group_init(pct, cpu_limit); | |
1557 | } | |
1558 | ||
1559 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) | |
1560 | { | |
1561 | struct signal_struct *sig; | |
1562 | ||
1563 | if (clone_flags & CLONE_THREAD) | |
1564 | return 0; | |
1565 | ||
1566 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); | |
1567 | tsk->signal = sig; | |
1568 | if (!sig) | |
1569 | return -ENOMEM; | |
1570 | ||
1571 | sig->nr_threads = 1; | |
1572 | atomic_set(&sig->live, 1); | |
1573 | refcount_set(&sig->sigcnt, 1); | |
1574 | ||
1575 | /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ | |
1576 | sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); | |
1577 | tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); | |
1578 | ||
1579 | init_waitqueue_head(&sig->wait_chldexit); | |
1580 | sig->curr_target = tsk; | |
1581 | init_sigpending(&sig->shared_pending); | |
1582 | INIT_HLIST_HEAD(&sig->multiprocess); | |
1583 | seqlock_init(&sig->stats_lock); | |
1584 | prev_cputime_init(&sig->prev_cputime); | |
1585 | ||
1586 | #ifdef CONFIG_POSIX_TIMERS | |
1587 | INIT_LIST_HEAD(&sig->posix_timers); | |
1588 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
1589 | sig->real_timer.function = it_real_fn; | |
1590 | #endif | |
1591 | ||
1592 | task_lock(current->group_leader); | |
1593 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
1594 | task_unlock(current->group_leader); | |
1595 | ||
1596 | posix_cpu_timers_init_group(sig); | |
1597 | ||
1598 | tty_audit_fork(sig); | |
1599 | sched_autogroup_fork(sig); | |
1600 | ||
1601 | sig->oom_score_adj = current->signal->oom_score_adj; | |
1602 | sig->oom_score_adj_min = current->signal->oom_score_adj_min; | |
1603 | ||
1604 | mutex_init(&sig->cred_guard_mutex); | |
1605 | init_rwsem(&sig->exec_update_lock); | |
1606 | ||
1607 | return 0; | |
1608 | } | |
1609 | ||
1610 | static void copy_seccomp(struct task_struct *p) | |
1611 | { | |
1612 | #ifdef CONFIG_SECCOMP | |
1613 | /* | |
1614 | * Must be called with sighand->lock held, which is common to | |
1615 | * all threads in the group. Holding cred_guard_mutex is not | |
1616 | * needed because this new task is not yet running and cannot | |
1617 | * be racing exec. | |
1618 | */ | |
1619 | assert_spin_locked(¤t->sighand->siglock); | |
1620 | ||
1621 | /* Ref-count the new filter user, and assign it. */ | |
1622 | get_seccomp_filter(current); | |
1623 | p->seccomp = current->seccomp; | |
1624 | ||
1625 | /* | |
1626 | * Explicitly enable no_new_privs here in case it got set | |
1627 | * between the task_struct being duplicated and holding the | |
1628 | * sighand lock. The seccomp state and nnp must be in sync. | |
1629 | */ | |
1630 | if (task_no_new_privs(current)) | |
1631 | task_set_no_new_privs(p); | |
1632 | ||
1633 | /* | |
1634 | * If the parent gained a seccomp mode after copying thread | |
1635 | * flags and between before we held the sighand lock, we have | |
1636 | * to manually enable the seccomp thread flag here. | |
1637 | */ | |
1638 | if (p->seccomp.mode != SECCOMP_MODE_DISABLED) | |
1639 | set_task_syscall_work(p, SECCOMP); | |
1640 | #endif | |
1641 | } | |
1642 | ||
1643 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) | |
1644 | { | |
1645 | current->clear_child_tid = tidptr; | |
1646 | ||
1647 | return task_pid_vnr(current); | |
1648 | } | |
1649 | ||
1650 | static void rt_mutex_init_task(struct task_struct *p) | |
1651 | { | |
1652 | raw_spin_lock_init(&p->pi_lock); | |
1653 | #ifdef CONFIG_RT_MUTEXES | |
1654 | p->pi_waiters = RB_ROOT_CACHED; | |
1655 | p->pi_top_task = NULL; | |
1656 | p->pi_blocked_on = NULL; | |
1657 | #endif | |
1658 | } | |
1659 | ||
1660 | static inline void init_task_pid_links(struct task_struct *task) | |
1661 | { | |
1662 | enum pid_type type; | |
1663 | ||
1664 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) | |
1665 | INIT_HLIST_NODE(&task->pid_links[type]); | |
1666 | } | |
1667 | ||
1668 | static inline void | |
1669 | init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) | |
1670 | { | |
1671 | if (type == PIDTYPE_PID) | |
1672 | task->thread_pid = pid; | |
1673 | else | |
1674 | task->signal->pids[type] = pid; | |
1675 | } | |
1676 | ||
1677 | static inline void rcu_copy_process(struct task_struct *p) | |
1678 | { | |
1679 | #ifdef CONFIG_PREEMPT_RCU | |
1680 | p->rcu_read_lock_nesting = 0; | |
1681 | p->rcu_read_unlock_special.s = 0; | |
1682 | p->rcu_blocked_node = NULL; | |
1683 | INIT_LIST_HEAD(&p->rcu_node_entry); | |
1684 | #endif /* #ifdef CONFIG_PREEMPT_RCU */ | |
1685 | #ifdef CONFIG_TASKS_RCU | |
1686 | p->rcu_tasks_holdout = false; | |
1687 | INIT_LIST_HEAD(&p->rcu_tasks_holdout_list); | |
1688 | p->rcu_tasks_idle_cpu = -1; | |
1689 | #endif /* #ifdef CONFIG_TASKS_RCU */ | |
1690 | #ifdef CONFIG_TASKS_TRACE_RCU | |
1691 | p->trc_reader_nesting = 0; | |
1692 | p->trc_reader_special.s = 0; | |
1693 | INIT_LIST_HEAD(&p->trc_holdout_list); | |
1694 | #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ | |
1695 | } | |
1696 | ||
1697 | struct pid *pidfd_pid(const struct file *file) | |
1698 | { | |
1699 | if (file->f_op == &pidfd_fops) | |
1700 | return file->private_data; | |
1701 | ||
1702 | return ERR_PTR(-EBADF); | |
1703 | } | |
1704 | ||
1705 | static int pidfd_release(struct inode *inode, struct file *file) | |
1706 | { | |
1707 | struct pid *pid = file->private_data; | |
1708 | ||
1709 | file->private_data = NULL; | |
1710 | put_pid(pid); | |
1711 | return 0; | |
1712 | } | |
1713 | ||
1714 | #ifdef CONFIG_PROC_FS | |
1715 | /** | |
1716 | * pidfd_show_fdinfo - print information about a pidfd | |
1717 | * @m: proc fdinfo file | |
1718 | * @f: file referencing a pidfd | |
1719 | * | |
1720 | * Pid: | |
1721 | * This function will print the pid that a given pidfd refers to in the | |
1722 | * pid namespace of the procfs instance. | |
1723 | * If the pid namespace of the process is not a descendant of the pid | |
1724 | * namespace of the procfs instance 0 will be shown as its pid. This is | |
1725 | * similar to calling getppid() on a process whose parent is outside of | |
1726 | * its pid namespace. | |
1727 | * | |
1728 | * NSpid: | |
1729 | * If pid namespaces are supported then this function will also print | |
1730 | * the pid of a given pidfd refers to for all descendant pid namespaces | |
1731 | * starting from the current pid namespace of the instance, i.e. the | |
1732 | * Pid field and the first entry in the NSpid field will be identical. | |
1733 | * If the pid namespace of the process is not a descendant of the pid | |
1734 | * namespace of the procfs instance 0 will be shown as its first NSpid | |
1735 | * entry and no others will be shown. | |
1736 | * Note that this differs from the Pid and NSpid fields in | |
1737 | * /proc/<pid>/status where Pid and NSpid are always shown relative to | |
1738 | * the pid namespace of the procfs instance. The difference becomes | |
1739 | * obvious when sending around a pidfd between pid namespaces from a | |
1740 | * different branch of the tree, i.e. where no ancestral relation is | |
1741 | * present between the pid namespaces: | |
1742 | * - create two new pid namespaces ns1 and ns2 in the initial pid | |
1743 | * namespace (also take care to create new mount namespaces in the | |
1744 | * new pid namespace and mount procfs) | |
1745 | * - create a process with a pidfd in ns1 | |
1746 | * - send pidfd from ns1 to ns2 | |
1747 | * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid | |
1748 | * have exactly one entry, which is 0 | |
1749 | */ | |
1750 | static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) | |
1751 | { | |
1752 | struct pid *pid = f->private_data; | |
1753 | struct pid_namespace *ns; | |
1754 | pid_t nr = -1; | |
1755 | ||
1756 | if (likely(pid_has_task(pid, PIDTYPE_PID))) { | |
1757 | ns = proc_pid_ns(file_inode(m->file)->i_sb); | |
1758 | nr = pid_nr_ns(pid, ns); | |
1759 | } | |
1760 | ||
1761 | seq_put_decimal_ll(m, "Pid:\t", nr); | |
1762 | ||
1763 | #ifdef CONFIG_PID_NS | |
1764 | seq_put_decimal_ll(m, "\nNSpid:\t", nr); | |
1765 | if (nr > 0) { | |
1766 | int i; | |
1767 | ||
1768 | /* If nr is non-zero it means that 'pid' is valid and that | |
1769 | * ns, i.e. the pid namespace associated with the procfs | |
1770 | * instance, is in the pid namespace hierarchy of pid. | |
1771 | * Start at one below the already printed level. | |
1772 | */ | |
1773 | for (i = ns->level + 1; i <= pid->level; i++) | |
1774 | seq_put_decimal_ll(m, "\t", pid->numbers[i].nr); | |
1775 | } | |
1776 | #endif | |
1777 | seq_putc(m, '\n'); | |
1778 | } | |
1779 | #endif | |
1780 | ||
1781 | /* | |
1782 | * Poll support for process exit notification. | |
1783 | */ | |
1784 | static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts) | |
1785 | { | |
1786 | struct pid *pid = file->private_data; | |
1787 | __poll_t poll_flags = 0; | |
1788 | ||
1789 | poll_wait(file, &pid->wait_pidfd, pts); | |
1790 | ||
1791 | /* | |
1792 | * Inform pollers only when the whole thread group exits. | |
1793 | * If the thread group leader exits before all other threads in the | |
1794 | * group, then poll(2) should block, similar to the wait(2) family. | |
1795 | */ | |
1796 | if (thread_group_exited(pid)) | |
1797 | poll_flags = EPOLLIN | EPOLLRDNORM; | |
1798 | ||
1799 | return poll_flags; | |
1800 | } | |
1801 | ||
1802 | const struct file_operations pidfd_fops = { | |
1803 | .release = pidfd_release, | |
1804 | .poll = pidfd_poll, | |
1805 | #ifdef CONFIG_PROC_FS | |
1806 | .show_fdinfo = pidfd_show_fdinfo, | |
1807 | #endif | |
1808 | }; | |
1809 | ||
1810 | static void __delayed_free_task(struct rcu_head *rhp) | |
1811 | { | |
1812 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); | |
1813 | ||
1814 | free_task(tsk); | |
1815 | } | |
1816 | ||
1817 | static __always_inline void delayed_free_task(struct task_struct *tsk) | |
1818 | { | |
1819 | if (IS_ENABLED(CONFIG_MEMCG)) | |
1820 | call_rcu(&tsk->rcu, __delayed_free_task); | |
1821 | else | |
1822 | free_task(tsk); | |
1823 | } | |
1824 | ||
1825 | static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk) | |
1826 | { | |
1827 | /* Skip if kernel thread */ | |
1828 | if (!tsk->mm) | |
1829 | return; | |
1830 | ||
1831 | /* Skip if spawning a thread or using vfork */ | |
1832 | if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM) | |
1833 | return; | |
1834 | ||
1835 | /* We need to synchronize with __set_oom_adj */ | |
1836 | mutex_lock(&oom_adj_mutex); | |
1837 | set_bit(MMF_MULTIPROCESS, &tsk->mm->flags); | |
1838 | /* Update the values in case they were changed after copy_signal */ | |
1839 | tsk->signal->oom_score_adj = current->signal->oom_score_adj; | |
1840 | tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min; | |
1841 | mutex_unlock(&oom_adj_mutex); | |
1842 | } | |
1843 | ||
1844 | /* | |
1845 | * This creates a new process as a copy of the old one, | |
1846 | * but does not actually start it yet. | |
1847 | * | |
1848 | * It copies the registers, and all the appropriate | |
1849 | * parts of the process environment (as per the clone | |
1850 | * flags). The actual kick-off is left to the caller. | |
1851 | */ | |
1852 | static __latent_entropy struct task_struct *copy_process( | |
1853 | struct pid *pid, | |
1854 | int trace, | |
1855 | int node, | |
1856 | struct kernel_clone_args *args) | |
1857 | { | |
1858 | int pidfd = -1, retval; | |
1859 | struct task_struct *p; | |
1860 | struct multiprocess_signals delayed; | |
1861 | struct file *pidfile = NULL; | |
1862 | u64 clone_flags = args->flags; | |
1863 | struct nsproxy *nsp = current->nsproxy; | |
1864 | ||
1865 | /* | |
1866 | * Don't allow sharing the root directory with processes in a different | |
1867 | * namespace | |
1868 | */ | |
1869 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
1870 | return ERR_PTR(-EINVAL); | |
1871 | ||
1872 | if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) | |
1873 | return ERR_PTR(-EINVAL); | |
1874 | ||
1875 | /* | |
1876 | * Thread groups must share signals as well, and detached threads | |
1877 | * can only be started up within the thread group. | |
1878 | */ | |
1879 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
1880 | return ERR_PTR(-EINVAL); | |
1881 | ||
1882 | /* | |
1883 | * Shared signal handlers imply shared VM. By way of the above, | |
1884 | * thread groups also imply shared VM. Blocking this case allows | |
1885 | * for various simplifications in other code. | |
1886 | */ | |
1887 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
1888 | return ERR_PTR(-EINVAL); | |
1889 | ||
1890 | /* | |
1891 | * Siblings of global init remain as zombies on exit since they are | |
1892 | * not reaped by their parent (swapper). To solve this and to avoid | |
1893 | * multi-rooted process trees, prevent global and container-inits | |
1894 | * from creating siblings. | |
1895 | */ | |
1896 | if ((clone_flags & CLONE_PARENT) && | |
1897 | current->signal->flags & SIGNAL_UNKILLABLE) | |
1898 | return ERR_PTR(-EINVAL); | |
1899 | ||
1900 | /* | |
1901 | * If the new process will be in a different pid or user namespace | |
1902 | * do not allow it to share a thread group with the forking task. | |
1903 | */ | |
1904 | if (clone_flags & CLONE_THREAD) { | |
1905 | if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || | |
1906 | (task_active_pid_ns(current) != nsp->pid_ns_for_children)) | |
1907 | return ERR_PTR(-EINVAL); | |
1908 | } | |
1909 | ||
1910 | /* | |
1911 | * If the new process will be in a different time namespace | |
1912 | * do not allow it to share VM or a thread group with the forking task. | |
1913 | */ | |
1914 | if (clone_flags & (CLONE_THREAD | CLONE_VM)) { | |
1915 | if (nsp->time_ns != nsp->time_ns_for_children) | |
1916 | return ERR_PTR(-EINVAL); | |
1917 | } | |
1918 | ||
1919 | if (clone_flags & CLONE_PIDFD) { | |
1920 | /* | |
1921 | * - CLONE_DETACHED is blocked so that we can potentially | |
1922 | * reuse it later for CLONE_PIDFD. | |
1923 | * - CLONE_THREAD is blocked until someone really needs it. | |
1924 | */ | |
1925 | if (clone_flags & (CLONE_DETACHED | CLONE_THREAD)) | |
1926 | return ERR_PTR(-EINVAL); | |
1927 | } | |
1928 | ||
1929 | /* | |
1930 | * Force any signals received before this point to be delivered | |
1931 | * before the fork happens. Collect up signals sent to multiple | |
1932 | * processes that happen during the fork and delay them so that | |
1933 | * they appear to happen after the fork. | |
1934 | */ | |
1935 | sigemptyset(&delayed.signal); | |
1936 | INIT_HLIST_NODE(&delayed.node); | |
1937 | ||
1938 | spin_lock_irq(¤t->sighand->siglock); | |
1939 | if (!(clone_flags & CLONE_THREAD)) | |
1940 | hlist_add_head(&delayed.node, ¤t->signal->multiprocess); | |
1941 | recalc_sigpending(); | |
1942 | spin_unlock_irq(¤t->sighand->siglock); | |
1943 | retval = -ERESTARTNOINTR; | |
1944 | if (task_sigpending(current)) | |
1945 | goto fork_out; | |
1946 | ||
1947 | retval = -ENOMEM; | |
1948 | p = dup_task_struct(current, node); | |
1949 | if (!p) | |
1950 | goto fork_out; | |
1951 | if (args->io_thread) { | |
1952 | /* | |
1953 | * Mark us an IO worker, and block any signal that isn't | |
1954 | * fatal or STOP | |
1955 | */ | |
1956 | p->flags |= PF_IO_WORKER; | |
1957 | siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
1958 | } | |
1959 | ||
1960 | /* | |
1961 | * This _must_ happen before we call free_task(), i.e. before we jump | |
1962 | * to any of the bad_fork_* labels. This is to avoid freeing | |
1963 | * p->set_child_tid which is (ab)used as a kthread's data pointer for | |
1964 | * kernel threads (PF_KTHREAD). | |
1965 | */ | |
1966 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL; | |
1967 | /* | |
1968 | * Clear TID on mm_release()? | |
1969 | */ | |
1970 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL; | |
1971 | ||
1972 | ftrace_graph_init_task(p); | |
1973 | ||
1974 | rt_mutex_init_task(p); | |
1975 | ||
1976 | lockdep_assert_irqs_enabled(); | |
1977 | #ifdef CONFIG_PROVE_LOCKING | |
1978 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); | |
1979 | #endif | |
1980 | retval = -EAGAIN; | |
1981 | if (atomic_read(&p->real_cred->user->processes) >= | |
1982 | task_rlimit(p, RLIMIT_NPROC)) { | |
1983 | if (p->real_cred->user != INIT_USER && | |
1984 | !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) | |
1985 | goto bad_fork_free; | |
1986 | } | |
1987 | current->flags &= ~PF_NPROC_EXCEEDED; | |
1988 | ||
1989 | retval = copy_creds(p, clone_flags); | |
1990 | if (retval < 0) | |
1991 | goto bad_fork_free; | |
1992 | ||
1993 | /* | |
1994 | * If multiple threads are within copy_process(), then this check | |
1995 | * triggers too late. This doesn't hurt, the check is only there | |
1996 | * to stop root fork bombs. | |
1997 | */ | |
1998 | retval = -EAGAIN; | |
1999 | if (data_race(nr_threads >= max_threads)) | |
2000 | goto bad_fork_cleanup_count; | |
2001 | ||
2002 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ | |
2003 | p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY); | |
2004 | p->flags |= PF_FORKNOEXEC; | |
2005 | INIT_LIST_HEAD(&p->children); | |
2006 | INIT_LIST_HEAD(&p->sibling); | |
2007 | rcu_copy_process(p); | |
2008 | p->vfork_done = NULL; | |
2009 | spin_lock_init(&p->alloc_lock); | |
2010 | ||
2011 | init_sigpending(&p->pending); | |
2012 | p->sigqueue_cache = NULL; | |
2013 | ||
2014 | p->utime = p->stime = p->gtime = 0; | |
2015 | #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME | |
2016 | p->utimescaled = p->stimescaled = 0; | |
2017 | #endif | |
2018 | prev_cputime_init(&p->prev_cputime); | |
2019 | ||
2020 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN | |
2021 | seqcount_init(&p->vtime.seqcount); | |
2022 | p->vtime.starttime = 0; | |
2023 | p->vtime.state = VTIME_INACTIVE; | |
2024 | #endif | |
2025 | ||
2026 | #ifdef CONFIG_IO_URING | |
2027 | p->io_uring = NULL; | |
2028 | #endif | |
2029 | ||
2030 | #if defined(SPLIT_RSS_COUNTING) | |
2031 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); | |
2032 | #endif | |
2033 | ||
2034 | p->default_timer_slack_ns = current->timer_slack_ns; | |
2035 | ||
2036 | #ifdef CONFIG_PSI | |
2037 | p->psi_flags = 0; | |
2038 | #endif | |
2039 | ||
2040 | task_io_accounting_init(&p->ioac); | |
2041 | acct_clear_integrals(p); | |
2042 | ||
2043 | posix_cputimers_init(&p->posix_cputimers); | |
2044 | ||
2045 | p->io_context = NULL; | |
2046 | audit_set_context(p, NULL); | |
2047 | cgroup_fork(p); | |
2048 | #ifdef CONFIG_NUMA | |
2049 | p->mempolicy = mpol_dup(p->mempolicy); | |
2050 | if (IS_ERR(p->mempolicy)) { | |
2051 | retval = PTR_ERR(p->mempolicy); | |
2052 | p->mempolicy = NULL; | |
2053 | goto bad_fork_cleanup_threadgroup_lock; | |
2054 | } | |
2055 | #endif | |
2056 | #ifdef CONFIG_CPUSETS | |
2057 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE; | |
2058 | p->cpuset_slab_spread_rotor = NUMA_NO_NODE; | |
2059 | seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock); | |
2060 | #endif | |
2061 | #ifdef CONFIG_TRACE_IRQFLAGS | |
2062 | memset(&p->irqtrace, 0, sizeof(p->irqtrace)); | |
2063 | p->irqtrace.hardirq_disable_ip = _THIS_IP_; | |
2064 | p->irqtrace.softirq_enable_ip = _THIS_IP_; | |
2065 | p->softirqs_enabled = 1; | |
2066 | p->softirq_context = 0; | |
2067 | #endif | |
2068 | ||
2069 | p->pagefault_disabled = 0; | |
2070 | ||
2071 | #ifdef CONFIG_LOCKDEP | |
2072 | lockdep_init_task(p); | |
2073 | #endif | |
2074 | ||
2075 | #ifdef CONFIG_DEBUG_MUTEXES | |
2076 | p->blocked_on = NULL; /* not blocked yet */ | |
2077 | #endif | |
2078 | #ifdef CONFIG_BCACHE | |
2079 | p->sequential_io = 0; | |
2080 | p->sequential_io_avg = 0; | |
2081 | #endif | |
2082 | #ifdef CONFIG_BPF_SYSCALL | |
2083 | RCU_INIT_POINTER(p->bpf_storage, NULL); | |
2084 | #endif | |
2085 | ||
2086 | /* Perform scheduler related setup. Assign this task to a CPU. */ | |
2087 | retval = sched_fork(clone_flags, p); | |
2088 | if (retval) | |
2089 | goto bad_fork_cleanup_policy; | |
2090 | ||
2091 | retval = perf_event_init_task(p, clone_flags); | |
2092 | if (retval) | |
2093 | goto bad_fork_cleanup_policy; | |
2094 | retval = audit_alloc(p); | |
2095 | if (retval) | |
2096 | goto bad_fork_cleanup_perf; | |
2097 | /* copy all the process information */ | |
2098 | shm_init_task(p); | |
2099 | retval = security_task_alloc(p, clone_flags); | |
2100 | if (retval) | |
2101 | goto bad_fork_cleanup_audit; | |
2102 | retval = copy_semundo(clone_flags, p); | |
2103 | if (retval) | |
2104 | goto bad_fork_cleanup_security; | |
2105 | retval = copy_files(clone_flags, p); | |
2106 | if (retval) | |
2107 | goto bad_fork_cleanup_semundo; | |
2108 | retval = copy_fs(clone_flags, p); | |
2109 | if (retval) | |
2110 | goto bad_fork_cleanup_files; | |
2111 | retval = copy_sighand(clone_flags, p); | |
2112 | if (retval) | |
2113 | goto bad_fork_cleanup_fs; | |
2114 | retval = copy_signal(clone_flags, p); | |
2115 | if (retval) | |
2116 | goto bad_fork_cleanup_sighand; | |
2117 | retval = copy_mm(clone_flags, p); | |
2118 | if (retval) | |
2119 | goto bad_fork_cleanup_signal; | |
2120 | retval = copy_namespaces(clone_flags, p); | |
2121 | if (retval) | |
2122 | goto bad_fork_cleanup_mm; | |
2123 | retval = copy_io(clone_flags, p); | |
2124 | if (retval) | |
2125 | goto bad_fork_cleanup_namespaces; | |
2126 | retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls); | |
2127 | if (retval) | |
2128 | goto bad_fork_cleanup_io; | |
2129 | ||
2130 | stackleak_task_init(p); | |
2131 | ||
2132 | if (pid != &init_struct_pid) { | |
2133 | pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid, | |
2134 | args->set_tid_size); | |
2135 | if (IS_ERR(pid)) { | |
2136 | retval = PTR_ERR(pid); | |
2137 | goto bad_fork_cleanup_thread; | |
2138 | } | |
2139 | } | |
2140 | ||
2141 | /* | |
2142 | * This has to happen after we've potentially unshared the file | |
2143 | * descriptor table (so that the pidfd doesn't leak into the child | |
2144 | * if the fd table isn't shared). | |
2145 | */ | |
2146 | if (clone_flags & CLONE_PIDFD) { | |
2147 | retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC); | |
2148 | if (retval < 0) | |
2149 | goto bad_fork_free_pid; | |
2150 | ||
2151 | pidfd = retval; | |
2152 | ||
2153 | pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, | |
2154 | O_RDWR | O_CLOEXEC); | |
2155 | if (IS_ERR(pidfile)) { | |
2156 | put_unused_fd(pidfd); | |
2157 | retval = PTR_ERR(pidfile); | |
2158 | goto bad_fork_free_pid; | |
2159 | } | |
2160 | get_pid(pid); /* held by pidfile now */ | |
2161 | ||
2162 | retval = put_user(pidfd, args->pidfd); | |
2163 | if (retval) | |
2164 | goto bad_fork_put_pidfd; | |
2165 | } | |
2166 | ||
2167 | #ifdef CONFIG_BLOCK | |
2168 | p->plug = NULL; | |
2169 | #endif | |
2170 | futex_init_task(p); | |
2171 | ||
2172 | /* | |
2173 | * sigaltstack should be cleared when sharing the same VM | |
2174 | */ | |
2175 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) | |
2176 | sas_ss_reset(p); | |
2177 | ||
2178 | /* | |
2179 | * Syscall tracing and stepping should be turned off in the | |
2180 | * child regardless of CLONE_PTRACE. | |
2181 | */ | |
2182 | user_disable_single_step(p); | |
2183 | clear_task_syscall_work(p, SYSCALL_TRACE); | |
2184 | #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU) | |
2185 | clear_task_syscall_work(p, SYSCALL_EMU); | |
2186 | #endif | |
2187 | clear_tsk_latency_tracing(p); | |
2188 | ||
2189 | /* ok, now we should be set up.. */ | |
2190 | p->pid = pid_nr(pid); | |
2191 | if (clone_flags & CLONE_THREAD) { | |
2192 | p->group_leader = current->group_leader; | |
2193 | p->tgid = current->tgid; | |
2194 | } else { | |
2195 | p->group_leader = p; | |
2196 | p->tgid = p->pid; | |
2197 | } | |
2198 | ||
2199 | p->nr_dirtied = 0; | |
2200 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); | |
2201 | p->dirty_paused_when = 0; | |
2202 | ||
2203 | p->pdeath_signal = 0; | |
2204 | INIT_LIST_HEAD(&p->thread_group); | |
2205 | p->task_works = NULL; | |
2206 | ||
2207 | #ifdef CONFIG_KRETPROBES | |
2208 | p->kretprobe_instances.first = NULL; | |
2209 | #endif | |
2210 | ||
2211 | /* | |
2212 | * Ensure that the cgroup subsystem policies allow the new process to be | |
2213 | * forked. It should be noted that the new process's css_set can be changed | |
2214 | * between here and cgroup_post_fork() if an organisation operation is in | |
2215 | * progress. | |
2216 | */ | |
2217 | retval = cgroup_can_fork(p, args); | |
2218 | if (retval) | |
2219 | goto bad_fork_put_pidfd; | |
2220 | ||
2221 | /* | |
2222 | * From this point on we must avoid any synchronous user-space | |
2223 | * communication until we take the tasklist-lock. In particular, we do | |
2224 | * not want user-space to be able to predict the process start-time by | |
2225 | * stalling fork(2) after we recorded the start_time but before it is | |
2226 | * visible to the system. | |
2227 | */ | |
2228 | ||
2229 | p->start_time = ktime_get_ns(); | |
2230 | p->start_boottime = ktime_get_boottime_ns(); | |
2231 | ||
2232 | /* | |
2233 | * Make it visible to the rest of the system, but dont wake it up yet. | |
2234 | * Need tasklist lock for parent etc handling! | |
2235 | */ | |
2236 | write_lock_irq(&tasklist_lock); | |
2237 | ||
2238 | /* CLONE_PARENT re-uses the old parent */ | |
2239 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { | |
2240 | p->real_parent = current->real_parent; | |
2241 | p->parent_exec_id = current->parent_exec_id; | |
2242 | if (clone_flags & CLONE_THREAD) | |
2243 | p->exit_signal = -1; | |
2244 | else | |
2245 | p->exit_signal = current->group_leader->exit_signal; | |
2246 | } else { | |
2247 | p->real_parent = current; | |
2248 | p->parent_exec_id = current->self_exec_id; | |
2249 | p->exit_signal = args->exit_signal; | |
2250 | } | |
2251 | ||
2252 | klp_copy_process(p); | |
2253 | ||
2254 | sched_core_fork(p); | |
2255 | ||
2256 | spin_lock(¤t->sighand->siglock); | |
2257 | ||
2258 | /* | |
2259 | * Copy seccomp details explicitly here, in case they were changed | |
2260 | * before holding sighand lock. | |
2261 | */ | |
2262 | copy_seccomp(p); | |
2263 | ||
2264 | rseq_fork(p, clone_flags); | |
2265 | ||
2266 | /* Don't start children in a dying pid namespace */ | |
2267 | if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) { | |
2268 | retval = -ENOMEM; | |
2269 | goto bad_fork_cancel_cgroup; | |
2270 | } | |
2271 | ||
2272 | /* Let kill terminate clone/fork in the middle */ | |
2273 | if (fatal_signal_pending(current)) { | |
2274 | retval = -EINTR; | |
2275 | goto bad_fork_cancel_cgroup; | |
2276 | } | |
2277 | ||
2278 | /* past the last point of failure */ | |
2279 | if (pidfile) | |
2280 | fd_install(pidfd, pidfile); | |
2281 | ||
2282 | init_task_pid_links(p); | |
2283 | if (likely(p->pid)) { | |
2284 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); | |
2285 | ||
2286 | init_task_pid(p, PIDTYPE_PID, pid); | |
2287 | if (thread_group_leader(p)) { | |
2288 | init_task_pid(p, PIDTYPE_TGID, pid); | |
2289 | init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); | |
2290 | init_task_pid(p, PIDTYPE_SID, task_session(current)); | |
2291 | ||
2292 | if (is_child_reaper(pid)) { | |
2293 | ns_of_pid(pid)->child_reaper = p; | |
2294 | p->signal->flags |= SIGNAL_UNKILLABLE; | |
2295 | } | |
2296 | p->signal->shared_pending.signal = delayed.signal; | |
2297 | p->signal->tty = tty_kref_get(current->signal->tty); | |
2298 | /* | |
2299 | * Inherit has_child_subreaper flag under the same | |
2300 | * tasklist_lock with adding child to the process tree | |
2301 | * for propagate_has_child_subreaper optimization. | |
2302 | */ | |
2303 | p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper || | |
2304 | p->real_parent->signal->is_child_subreaper; | |
2305 | list_add_tail(&p->sibling, &p->real_parent->children); | |
2306 | list_add_tail_rcu(&p->tasks, &init_task.tasks); | |
2307 | attach_pid(p, PIDTYPE_TGID); | |
2308 | attach_pid(p, PIDTYPE_PGID); | |
2309 | attach_pid(p, PIDTYPE_SID); | |
2310 | __this_cpu_inc(process_counts); | |
2311 | } else { | |
2312 | current->signal->nr_threads++; | |
2313 | atomic_inc(¤t->signal->live); | |
2314 | refcount_inc(¤t->signal->sigcnt); | |
2315 | task_join_group_stop(p); | |
2316 | list_add_tail_rcu(&p->thread_group, | |
2317 | &p->group_leader->thread_group); | |
2318 | list_add_tail_rcu(&p->thread_node, | |
2319 | &p->signal->thread_head); | |
2320 | } | |
2321 | attach_pid(p, PIDTYPE_PID); | |
2322 | nr_threads++; | |
2323 | } | |
2324 | total_forks++; | |
2325 | hlist_del_init(&delayed.node); | |
2326 | spin_unlock(¤t->sighand->siglock); | |
2327 | syscall_tracepoint_update(p); | |
2328 | write_unlock_irq(&tasklist_lock); | |
2329 | ||
2330 | proc_fork_connector(p); | |
2331 | sched_post_fork(p); | |
2332 | cgroup_post_fork(p, args); | |
2333 | perf_event_fork(p); | |
2334 | ||
2335 | trace_task_newtask(p, clone_flags); | |
2336 | uprobe_copy_process(p, clone_flags); | |
2337 | ||
2338 | copy_oom_score_adj(clone_flags, p); | |
2339 | ||
2340 | return p; | |
2341 | ||
2342 | bad_fork_cancel_cgroup: | |
2343 | sched_core_free(p); | |
2344 | spin_unlock(¤t->sighand->siglock); | |
2345 | write_unlock_irq(&tasklist_lock); | |
2346 | cgroup_cancel_fork(p, args); | |
2347 | bad_fork_put_pidfd: | |
2348 | if (clone_flags & CLONE_PIDFD) { | |
2349 | fput(pidfile); | |
2350 | put_unused_fd(pidfd); | |
2351 | } | |
2352 | bad_fork_free_pid: | |
2353 | if (pid != &init_struct_pid) | |
2354 | free_pid(pid); | |
2355 | bad_fork_cleanup_thread: | |
2356 | exit_thread(p); | |
2357 | bad_fork_cleanup_io: | |
2358 | if (p->io_context) | |
2359 | exit_io_context(p); | |
2360 | bad_fork_cleanup_namespaces: | |
2361 | exit_task_namespaces(p); | |
2362 | bad_fork_cleanup_mm: | |
2363 | if (p->mm) { | |
2364 | mm_clear_owner(p->mm, p); | |
2365 | mmput(p->mm); | |
2366 | } | |
2367 | bad_fork_cleanup_signal: | |
2368 | if (!(clone_flags & CLONE_THREAD)) | |
2369 | free_signal_struct(p->signal); | |
2370 | bad_fork_cleanup_sighand: | |
2371 | __cleanup_sighand(p->sighand); | |
2372 | bad_fork_cleanup_fs: | |
2373 | exit_fs(p); /* blocking */ | |
2374 | bad_fork_cleanup_files: | |
2375 | exit_files(p); /* blocking */ | |
2376 | bad_fork_cleanup_semundo: | |
2377 | exit_sem(p); | |
2378 | bad_fork_cleanup_security: | |
2379 | security_task_free(p); | |
2380 | bad_fork_cleanup_audit: | |
2381 | audit_free(p); | |
2382 | bad_fork_cleanup_perf: | |
2383 | perf_event_free_task(p); | |
2384 | bad_fork_cleanup_policy: | |
2385 | lockdep_free_task(p); | |
2386 | #ifdef CONFIG_NUMA | |
2387 | mpol_put(p->mempolicy); | |
2388 | bad_fork_cleanup_threadgroup_lock: | |
2389 | #endif | |
2390 | delayacct_tsk_free(p); | |
2391 | bad_fork_cleanup_count: | |
2392 | atomic_dec(&p->cred->user->processes); | |
2393 | exit_creds(p); | |
2394 | bad_fork_free: | |
2395 | WRITE_ONCE(p->__state, TASK_DEAD); | |
2396 | put_task_stack(p); | |
2397 | delayed_free_task(p); | |
2398 | fork_out: | |
2399 | spin_lock_irq(¤t->sighand->siglock); | |
2400 | hlist_del_init(&delayed.node); | |
2401 | spin_unlock_irq(¤t->sighand->siglock); | |
2402 | return ERR_PTR(retval); | |
2403 | } | |
2404 | ||
2405 | static inline void init_idle_pids(struct task_struct *idle) | |
2406 | { | |
2407 | enum pid_type type; | |
2408 | ||
2409 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { | |
2410 | INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */ | |
2411 | init_task_pid(idle, type, &init_struct_pid); | |
2412 | } | |
2413 | } | |
2414 | ||
2415 | struct task_struct * __init fork_idle(int cpu) | |
2416 | { | |
2417 | struct task_struct *task; | |
2418 | struct kernel_clone_args args = { | |
2419 | .flags = CLONE_VM, | |
2420 | }; | |
2421 | ||
2422 | task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args); | |
2423 | if (!IS_ERR(task)) { | |
2424 | init_idle_pids(task); | |
2425 | init_idle(task, cpu); | |
2426 | } | |
2427 | ||
2428 | return task; | |
2429 | } | |
2430 | ||
2431 | struct mm_struct *copy_init_mm(void) | |
2432 | { | |
2433 | return dup_mm(NULL, &init_mm); | |
2434 | } | |
2435 | ||
2436 | /* | |
2437 | * This is like kernel_clone(), but shaved down and tailored to just | |
2438 | * creating io_uring workers. It returns a created task, or an error pointer. | |
2439 | * The returned task is inactive, and the caller must fire it up through | |
2440 | * wake_up_new_task(p). All signals are blocked in the created task. | |
2441 | */ | |
2442 | struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) | |
2443 | { | |
2444 | unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD| | |
2445 | CLONE_IO; | |
2446 | struct kernel_clone_args args = { | |
2447 | .flags = ((lower_32_bits(flags) | CLONE_VM | | |
2448 | CLONE_UNTRACED) & ~CSIGNAL), | |
2449 | .exit_signal = (lower_32_bits(flags) & CSIGNAL), | |
2450 | .stack = (unsigned long)fn, | |
2451 | .stack_size = (unsigned long)arg, | |
2452 | .io_thread = 1, | |
2453 | }; | |
2454 | ||
2455 | return copy_process(NULL, 0, node, &args); | |
2456 | } | |
2457 | ||
2458 | /* | |
2459 | * Ok, this is the main fork-routine. | |
2460 | * | |
2461 | * It copies the process, and if successful kick-starts | |
2462 | * it and waits for it to finish using the VM if required. | |
2463 | * | |
2464 | * args->exit_signal is expected to be checked for sanity by the caller. | |
2465 | */ | |
2466 | pid_t kernel_clone(struct kernel_clone_args *args) | |
2467 | { | |
2468 | u64 clone_flags = args->flags; | |
2469 | struct completion vfork; | |
2470 | struct pid *pid; | |
2471 | struct task_struct *p; | |
2472 | int trace = 0; | |
2473 | pid_t nr; | |
2474 | ||
2475 | /* | |
2476 | * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument | |
2477 | * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are | |
2478 | * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate | |
2479 | * field in struct clone_args and it still doesn't make sense to have | |
2480 | * them both point at the same memory location. Performing this check | |
2481 | * here has the advantage that we don't need to have a separate helper | |
2482 | * to check for legacy clone(). | |
2483 | */ | |
2484 | if ((args->flags & CLONE_PIDFD) && | |
2485 | (args->flags & CLONE_PARENT_SETTID) && | |
2486 | (args->pidfd == args->parent_tid)) | |
2487 | return -EINVAL; | |
2488 | ||
2489 | /* | |
2490 | * Determine whether and which event to report to ptracer. When | |
2491 | * called from kernel_thread or CLONE_UNTRACED is explicitly | |
2492 | * requested, no event is reported; otherwise, report if the event | |
2493 | * for the type of forking is enabled. | |
2494 | */ | |
2495 | if (!(clone_flags & CLONE_UNTRACED)) { | |
2496 | if (clone_flags & CLONE_VFORK) | |
2497 | trace = PTRACE_EVENT_VFORK; | |
2498 | else if (args->exit_signal != SIGCHLD) | |
2499 | trace = PTRACE_EVENT_CLONE; | |
2500 | else | |
2501 | trace = PTRACE_EVENT_FORK; | |
2502 | ||
2503 | if (likely(!ptrace_event_enabled(current, trace))) | |
2504 | trace = 0; | |
2505 | } | |
2506 | ||
2507 | p = copy_process(NULL, trace, NUMA_NO_NODE, args); | |
2508 | add_latent_entropy(); | |
2509 | ||
2510 | if (IS_ERR(p)) | |
2511 | return PTR_ERR(p); | |
2512 | ||
2513 | /* | |
2514 | * Do this prior waking up the new thread - the thread pointer | |
2515 | * might get invalid after that point, if the thread exits quickly. | |
2516 | */ | |
2517 | trace_sched_process_fork(current, p); | |
2518 | ||
2519 | pid = get_task_pid(p, PIDTYPE_PID); | |
2520 | nr = pid_vnr(pid); | |
2521 | ||
2522 | if (clone_flags & CLONE_PARENT_SETTID) | |
2523 | put_user(nr, args->parent_tid); | |
2524 | ||
2525 | if (clone_flags & CLONE_VFORK) { | |
2526 | p->vfork_done = &vfork; | |
2527 | init_completion(&vfork); | |
2528 | get_task_struct(p); | |
2529 | } | |
2530 | ||
2531 | wake_up_new_task(p); | |
2532 | ||
2533 | /* forking complete and child started to run, tell ptracer */ | |
2534 | if (unlikely(trace)) | |
2535 | ptrace_event_pid(trace, pid); | |
2536 | ||
2537 | if (clone_flags & CLONE_VFORK) { | |
2538 | if (!wait_for_vfork_done(p, &vfork)) | |
2539 | ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); | |
2540 | } | |
2541 | ||
2542 | put_pid(pid); | |
2543 | return nr; | |
2544 | } | |
2545 | ||
2546 | /* | |
2547 | * Create a kernel thread. | |
2548 | */ | |
2549 | pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) | |
2550 | { | |
2551 | struct kernel_clone_args args = { | |
2552 | .flags = ((lower_32_bits(flags) | CLONE_VM | | |
2553 | CLONE_UNTRACED) & ~CSIGNAL), | |
2554 | .exit_signal = (lower_32_bits(flags) & CSIGNAL), | |
2555 | .stack = (unsigned long)fn, | |
2556 | .stack_size = (unsigned long)arg, | |
2557 | }; | |
2558 | ||
2559 | return kernel_clone(&args); | |
2560 | } | |
2561 | ||
2562 | #ifdef __ARCH_WANT_SYS_FORK | |
2563 | SYSCALL_DEFINE0(fork) | |
2564 | { | |
2565 | #ifdef CONFIG_MMU | |
2566 | struct kernel_clone_args args = { | |
2567 | .exit_signal = SIGCHLD, | |
2568 | }; | |
2569 | ||
2570 | return kernel_clone(&args); | |
2571 | #else | |
2572 | /* can not support in nommu mode */ | |
2573 | return -EINVAL; | |
2574 | #endif | |
2575 | } | |
2576 | #endif | |
2577 | ||
2578 | #ifdef __ARCH_WANT_SYS_VFORK | |
2579 | SYSCALL_DEFINE0(vfork) | |
2580 | { | |
2581 | struct kernel_clone_args args = { | |
2582 | .flags = CLONE_VFORK | CLONE_VM, | |
2583 | .exit_signal = SIGCHLD, | |
2584 | }; | |
2585 | ||
2586 | return kernel_clone(&args); | |
2587 | } | |
2588 | #endif | |
2589 | ||
2590 | #ifdef __ARCH_WANT_SYS_CLONE | |
2591 | #ifdef CONFIG_CLONE_BACKWARDS | |
2592 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, | |
2593 | int __user *, parent_tidptr, | |
2594 | unsigned long, tls, | |
2595 | int __user *, child_tidptr) | |
2596 | #elif defined(CONFIG_CLONE_BACKWARDS2) | |
2597 | SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, | |
2598 | int __user *, parent_tidptr, | |
2599 | int __user *, child_tidptr, | |
2600 | unsigned long, tls) | |
2601 | #elif defined(CONFIG_CLONE_BACKWARDS3) | |
2602 | SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, | |
2603 | int, stack_size, | |
2604 | int __user *, parent_tidptr, | |
2605 | int __user *, child_tidptr, | |
2606 | unsigned long, tls) | |
2607 | #else | |
2608 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, | |
2609 | int __user *, parent_tidptr, | |
2610 | int __user *, child_tidptr, | |
2611 | unsigned long, tls) | |
2612 | #endif | |
2613 | { | |
2614 | struct kernel_clone_args args = { | |
2615 | .flags = (lower_32_bits(clone_flags) & ~CSIGNAL), | |
2616 | .pidfd = parent_tidptr, | |
2617 | .child_tid = child_tidptr, | |
2618 | .parent_tid = parent_tidptr, | |
2619 | .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL), | |
2620 | .stack = newsp, | |
2621 | .tls = tls, | |
2622 | }; | |
2623 | ||
2624 | return kernel_clone(&args); | |
2625 | } | |
2626 | #endif | |
2627 | ||
2628 | #ifdef __ARCH_WANT_SYS_CLONE3 | |
2629 | ||
2630 | noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, | |
2631 | struct clone_args __user *uargs, | |
2632 | size_t usize) | |
2633 | { | |
2634 | int err; | |
2635 | struct clone_args args; | |
2636 | pid_t *kset_tid = kargs->set_tid; | |
2637 | ||
2638 | BUILD_BUG_ON(offsetofend(struct clone_args, tls) != | |
2639 | CLONE_ARGS_SIZE_VER0); | |
2640 | BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) != | |
2641 | CLONE_ARGS_SIZE_VER1); | |
2642 | BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) != | |
2643 | CLONE_ARGS_SIZE_VER2); | |
2644 | BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2); | |
2645 | ||
2646 | if (unlikely(usize > PAGE_SIZE)) | |
2647 | return -E2BIG; | |
2648 | if (unlikely(usize < CLONE_ARGS_SIZE_VER0)) | |
2649 | return -EINVAL; | |
2650 | ||
2651 | err = copy_struct_from_user(&args, sizeof(args), uargs, usize); | |
2652 | if (err) | |
2653 | return err; | |
2654 | ||
2655 | if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL)) | |
2656 | return -EINVAL; | |
2657 | ||
2658 | if (unlikely(!args.set_tid && args.set_tid_size > 0)) | |
2659 | return -EINVAL; | |
2660 | ||
2661 | if (unlikely(args.set_tid && args.set_tid_size == 0)) | |
2662 | return -EINVAL; | |
2663 | ||
2664 | /* | |
2665 | * Verify that higher 32bits of exit_signal are unset and that | |
2666 | * it is a valid signal | |
2667 | */ | |
2668 | if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) || | |
2669 | !valid_signal(args.exit_signal))) | |
2670 | return -EINVAL; | |
2671 | ||
2672 | if ((args.flags & CLONE_INTO_CGROUP) && | |
2673 | (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2)) | |
2674 | return -EINVAL; | |
2675 | ||
2676 | *kargs = (struct kernel_clone_args){ | |
2677 | .flags = args.flags, | |
2678 | .pidfd = u64_to_user_ptr(args.pidfd), | |
2679 | .child_tid = u64_to_user_ptr(args.child_tid), | |
2680 | .parent_tid = u64_to_user_ptr(args.parent_tid), | |
2681 | .exit_signal = args.exit_signal, | |
2682 | .stack = args.stack, | |
2683 | .stack_size = args.stack_size, | |
2684 | .tls = args.tls, | |
2685 | .set_tid_size = args.set_tid_size, | |
2686 | .cgroup = args.cgroup, | |
2687 | }; | |
2688 | ||
2689 | if (args.set_tid && | |
2690 | copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid), | |
2691 | (kargs->set_tid_size * sizeof(pid_t)))) | |
2692 | return -EFAULT; | |
2693 | ||
2694 | kargs->set_tid = kset_tid; | |
2695 | ||
2696 | return 0; | |
2697 | } | |
2698 | ||
2699 | /** | |
2700 | * clone3_stack_valid - check and prepare stack | |
2701 | * @kargs: kernel clone args | |
2702 | * | |
2703 | * Verify that the stack arguments userspace gave us are sane. | |
2704 | * In addition, set the stack direction for userspace since it's easy for us to | |
2705 | * determine. | |
2706 | */ | |
2707 | static inline bool clone3_stack_valid(struct kernel_clone_args *kargs) | |
2708 | { | |
2709 | if (kargs->stack == 0) { | |
2710 | if (kargs->stack_size > 0) | |
2711 | return false; | |
2712 | } else { | |
2713 | if (kargs->stack_size == 0) | |
2714 | return false; | |
2715 | ||
2716 | if (!access_ok((void __user *)kargs->stack, kargs->stack_size)) | |
2717 | return false; | |
2718 | ||
2719 | #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64) | |
2720 | kargs->stack += kargs->stack_size; | |
2721 | #endif | |
2722 | } | |
2723 | ||
2724 | return true; | |
2725 | } | |
2726 | ||
2727 | static bool clone3_args_valid(struct kernel_clone_args *kargs) | |
2728 | { | |
2729 | /* Verify that no unknown flags are passed along. */ | |
2730 | if (kargs->flags & | |
2731 | ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP)) | |
2732 | return false; | |
2733 | ||
2734 | /* | |
2735 | * - make the CLONE_DETACHED bit reusable for clone3 | |
2736 | * - make the CSIGNAL bits reusable for clone3 | |
2737 | */ | |
2738 | if (kargs->flags & (CLONE_DETACHED | CSIGNAL)) | |
2739 | return false; | |
2740 | ||
2741 | if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) == | |
2742 | (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) | |
2743 | return false; | |
2744 | ||
2745 | if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) && | |
2746 | kargs->exit_signal) | |
2747 | return false; | |
2748 | ||
2749 | if (!clone3_stack_valid(kargs)) | |
2750 | return false; | |
2751 | ||
2752 | return true; | |
2753 | } | |
2754 | ||
2755 | /** | |
2756 | * clone3 - create a new process with specific properties | |
2757 | * @uargs: argument structure | |
2758 | * @size: size of @uargs | |
2759 | * | |
2760 | * clone3() is the extensible successor to clone()/clone2(). | |
2761 | * It takes a struct as argument that is versioned by its size. | |
2762 | * | |
2763 | * Return: On success, a positive PID for the child process. | |
2764 | * On error, a negative errno number. | |
2765 | */ | |
2766 | SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size) | |
2767 | { | |
2768 | int err; | |
2769 | ||
2770 | struct kernel_clone_args kargs; | |
2771 | pid_t set_tid[MAX_PID_NS_LEVEL]; | |
2772 | ||
2773 | kargs.set_tid = set_tid; | |
2774 | ||
2775 | err = copy_clone_args_from_user(&kargs, uargs, size); | |
2776 | if (err) | |
2777 | return err; | |
2778 | ||
2779 | if (!clone3_args_valid(&kargs)) | |
2780 | return -EINVAL; | |
2781 | ||
2782 | return kernel_clone(&kargs); | |
2783 | } | |
2784 | #endif | |
2785 | ||
2786 | void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data) | |
2787 | { | |
2788 | struct task_struct *leader, *parent, *child; | |
2789 | int res; | |
2790 | ||
2791 | read_lock(&tasklist_lock); | |
2792 | leader = top = top->group_leader; | |
2793 | down: | |
2794 | for_each_thread(leader, parent) { | |
2795 | list_for_each_entry(child, &parent->children, sibling) { | |
2796 | res = visitor(child, data); | |
2797 | if (res) { | |
2798 | if (res < 0) | |
2799 | goto out; | |
2800 | leader = child; | |
2801 | goto down; | |
2802 | } | |
2803 | up: | |
2804 | ; | |
2805 | } | |
2806 | } | |
2807 | ||
2808 | if (leader != top) { | |
2809 | child = leader; | |
2810 | parent = child->real_parent; | |
2811 | leader = parent->group_leader; | |
2812 | goto up; | |
2813 | } | |
2814 | out: | |
2815 | read_unlock(&tasklist_lock); | |
2816 | } | |
2817 | ||
2818 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN | |
2819 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 | |
2820 | #endif | |
2821 | ||
2822 | static void sighand_ctor(void *data) | |
2823 | { | |
2824 | struct sighand_struct *sighand = data; | |
2825 | ||
2826 | spin_lock_init(&sighand->siglock); | |
2827 | init_waitqueue_head(&sighand->signalfd_wqh); | |
2828 | } | |
2829 | ||
2830 | void __init proc_caches_init(void) | |
2831 | { | |
2832 | unsigned int mm_size; | |
2833 | ||
2834 | sighand_cachep = kmem_cache_create("sighand_cache", | |
2835 | sizeof(struct sighand_struct), 0, | |
2836 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU| | |
2837 | SLAB_ACCOUNT, sighand_ctor); | |
2838 | signal_cachep = kmem_cache_create("signal_cache", | |
2839 | sizeof(struct signal_struct), 0, | |
2840 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, | |
2841 | NULL); | |
2842 | files_cachep = kmem_cache_create("files_cache", | |
2843 | sizeof(struct files_struct), 0, | |
2844 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, | |
2845 | NULL); | |
2846 | fs_cachep = kmem_cache_create("fs_cache", | |
2847 | sizeof(struct fs_struct), 0, | |
2848 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, | |
2849 | NULL); | |
2850 | ||
2851 | /* | |
2852 | * The mm_cpumask is located at the end of mm_struct, and is | |
2853 | * dynamically sized based on the maximum CPU number this system | |
2854 | * can have, taking hotplug into account (nr_cpu_ids). | |
2855 | */ | |
2856 | mm_size = sizeof(struct mm_struct) + cpumask_size(); | |
2857 | ||
2858 | mm_cachep = kmem_cache_create_usercopy("mm_struct", | |
2859 | mm_size, ARCH_MIN_MMSTRUCT_ALIGN, | |
2860 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, | |
2861 | offsetof(struct mm_struct, saved_auxv), | |
2862 | sizeof_field(struct mm_struct, saved_auxv), | |
2863 | NULL); | |
2864 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); | |
2865 | mmap_init(); | |
2866 | nsproxy_cache_init(); | |
2867 | } | |
2868 | ||
2869 | /* | |
2870 | * Check constraints on flags passed to the unshare system call. | |
2871 | */ | |
2872 | static int check_unshare_flags(unsigned long unshare_flags) | |
2873 | { | |
2874 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| | |
2875 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| | |
2876 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| | |
2877 | CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP| | |
2878 | CLONE_NEWTIME)) | |
2879 | return -EINVAL; | |
2880 | /* | |
2881 | * Not implemented, but pretend it works if there is nothing | |
2882 | * to unshare. Note that unsharing the address space or the | |
2883 | * signal handlers also need to unshare the signal queues (aka | |
2884 | * CLONE_THREAD). | |
2885 | */ | |
2886 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { | |
2887 | if (!thread_group_empty(current)) | |
2888 | return -EINVAL; | |
2889 | } | |
2890 | if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) { | |
2891 | if (refcount_read(¤t->sighand->count) > 1) | |
2892 | return -EINVAL; | |
2893 | } | |
2894 | if (unshare_flags & CLONE_VM) { | |
2895 | if (!current_is_single_threaded()) | |
2896 | return -EINVAL; | |
2897 | } | |
2898 | ||
2899 | return 0; | |
2900 | } | |
2901 | ||
2902 | /* | |
2903 | * Unshare the filesystem structure if it is being shared | |
2904 | */ | |
2905 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) | |
2906 | { | |
2907 | struct fs_struct *fs = current->fs; | |
2908 | ||
2909 | if (!(unshare_flags & CLONE_FS) || !fs) | |
2910 | return 0; | |
2911 | ||
2912 | /* don't need lock here; in the worst case we'll do useless copy */ | |
2913 | if (fs->users == 1) | |
2914 | return 0; | |
2915 | ||
2916 | *new_fsp = copy_fs_struct(fs); | |
2917 | if (!*new_fsp) | |
2918 | return -ENOMEM; | |
2919 | ||
2920 | return 0; | |
2921 | } | |
2922 | ||
2923 | /* | |
2924 | * Unshare file descriptor table if it is being shared | |
2925 | */ | |
2926 | int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, | |
2927 | struct files_struct **new_fdp) | |
2928 | { | |
2929 | struct files_struct *fd = current->files; | |
2930 | int error = 0; | |
2931 | ||
2932 | if ((unshare_flags & CLONE_FILES) && | |
2933 | (fd && atomic_read(&fd->count) > 1)) { | |
2934 | *new_fdp = dup_fd(fd, max_fds, &error); | |
2935 | if (!*new_fdp) | |
2936 | return error; | |
2937 | } | |
2938 | ||
2939 | return 0; | |
2940 | } | |
2941 | ||
2942 | /* | |
2943 | * unshare allows a process to 'unshare' part of the process | |
2944 | * context which was originally shared using clone. copy_* | |
2945 | * functions used by kernel_clone() cannot be used here directly | |
2946 | * because they modify an inactive task_struct that is being | |
2947 | * constructed. Here we are modifying the current, active, | |
2948 | * task_struct. | |
2949 | */ | |
2950 | int ksys_unshare(unsigned long unshare_flags) | |
2951 | { | |
2952 | struct fs_struct *fs, *new_fs = NULL; | |
2953 | struct files_struct *fd, *new_fd = NULL; | |
2954 | struct cred *new_cred = NULL; | |
2955 | struct nsproxy *new_nsproxy = NULL; | |
2956 | int do_sysvsem = 0; | |
2957 | int err; | |
2958 | ||
2959 | /* | |
2960 | * If unsharing a user namespace must also unshare the thread group | |
2961 | * and unshare the filesystem root and working directories. | |
2962 | */ | |
2963 | if (unshare_flags & CLONE_NEWUSER) | |
2964 | unshare_flags |= CLONE_THREAD | CLONE_FS; | |
2965 | /* | |
2966 | * If unsharing vm, must also unshare signal handlers. | |
2967 | */ | |
2968 | if (unshare_flags & CLONE_VM) | |
2969 | unshare_flags |= CLONE_SIGHAND; | |
2970 | /* | |
2971 | * If unsharing a signal handlers, must also unshare the signal queues. | |
2972 | */ | |
2973 | if (unshare_flags & CLONE_SIGHAND) | |
2974 | unshare_flags |= CLONE_THREAD; | |
2975 | /* | |
2976 | * If unsharing namespace, must also unshare filesystem information. | |
2977 | */ | |
2978 | if (unshare_flags & CLONE_NEWNS) | |
2979 | unshare_flags |= CLONE_FS; | |
2980 | ||
2981 | err = check_unshare_flags(unshare_flags); | |
2982 | if (err) | |
2983 | goto bad_unshare_out; | |
2984 | /* | |
2985 | * CLONE_NEWIPC must also detach from the undolist: after switching | |
2986 | * to a new ipc namespace, the semaphore arrays from the old | |
2987 | * namespace are unreachable. | |
2988 | */ | |
2989 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) | |
2990 | do_sysvsem = 1; | |
2991 | err = unshare_fs(unshare_flags, &new_fs); | |
2992 | if (err) | |
2993 | goto bad_unshare_out; | |
2994 | err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd); | |
2995 | if (err) | |
2996 | goto bad_unshare_cleanup_fs; | |
2997 | err = unshare_userns(unshare_flags, &new_cred); | |
2998 | if (err) | |
2999 | goto bad_unshare_cleanup_fd; | |
3000 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, | |
3001 | new_cred, new_fs); | |
3002 | if (err) | |
3003 | goto bad_unshare_cleanup_cred; | |
3004 | ||
3005 | if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { | |
3006 | if (do_sysvsem) { | |
3007 | /* | |
3008 | * CLONE_SYSVSEM is equivalent to sys_exit(). | |
3009 | */ | |
3010 | exit_sem(current); | |
3011 | } | |
3012 | if (unshare_flags & CLONE_NEWIPC) { | |
3013 | /* Orphan segments in old ns (see sem above). */ | |
3014 | exit_shm(current); | |
3015 | shm_init_task(current); | |
3016 | } | |
3017 | ||
3018 | if (new_nsproxy) | |
3019 | switch_task_namespaces(current, new_nsproxy); | |
3020 | ||
3021 | task_lock(current); | |
3022 | ||
3023 | if (new_fs) { | |
3024 | fs = current->fs; | |
3025 | spin_lock(&fs->lock); | |
3026 | current->fs = new_fs; | |
3027 | if (--fs->users) | |
3028 | new_fs = NULL; | |
3029 | else | |
3030 | new_fs = fs; | |
3031 | spin_unlock(&fs->lock); | |
3032 | } | |
3033 | ||
3034 | if (new_fd) { | |
3035 | fd = current->files; | |
3036 | current->files = new_fd; | |
3037 | new_fd = fd; | |
3038 | } | |
3039 | ||
3040 | task_unlock(current); | |
3041 | ||
3042 | if (new_cred) { | |
3043 | /* Install the new user namespace */ | |
3044 | commit_creds(new_cred); | |
3045 | new_cred = NULL; | |
3046 | } | |
3047 | } | |
3048 | ||
3049 | perf_event_namespaces(current); | |
3050 | ||
3051 | bad_unshare_cleanup_cred: | |
3052 | if (new_cred) | |
3053 | put_cred(new_cred); | |
3054 | bad_unshare_cleanup_fd: | |
3055 | if (new_fd) | |
3056 | put_files_struct(new_fd); | |
3057 | ||
3058 | bad_unshare_cleanup_fs: | |
3059 | if (new_fs) | |
3060 | free_fs_struct(new_fs); | |
3061 | ||
3062 | bad_unshare_out: | |
3063 | return err; | |
3064 | } | |
3065 | ||
3066 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) | |
3067 | { | |
3068 | return ksys_unshare(unshare_flags); | |
3069 | } | |
3070 | ||
3071 | /* | |
3072 | * Helper to unshare the files of the current task. | |
3073 | * We don't want to expose copy_files internals to | |
3074 | * the exec layer of the kernel. | |
3075 | */ | |
3076 | ||
3077 | int unshare_files(void) | |
3078 | { | |
3079 | struct task_struct *task = current; | |
3080 | struct files_struct *old, *copy = NULL; | |
3081 | int error; | |
3082 | ||
3083 | error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©); | |
3084 | if (error || !copy) | |
3085 | return error; | |
3086 | ||
3087 | old = task->files; | |
3088 | task_lock(task); | |
3089 | task->files = copy; | |
3090 | task_unlock(task); | |
3091 | put_files_struct(old); | |
3092 | return 0; | |
3093 | } | |
3094 | ||
3095 | int sysctl_max_threads(struct ctl_table *table, int write, | |
3096 | void *buffer, size_t *lenp, loff_t *ppos) | |
3097 | { | |
3098 | struct ctl_table t; | |
3099 | int ret; | |
3100 | int threads = max_threads; | |
3101 | int min = 1; | |
3102 | int max = MAX_THREADS; | |
3103 | ||
3104 | t = *table; | |
3105 | t.data = &threads; | |
3106 | t.extra1 = &min; | |
3107 | t.extra2 = &max; | |
3108 | ||
3109 | ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
3110 | if (ret || !write) | |
3111 | return ret; | |
3112 | ||
3113 | max_threads = threads; | |
3114 | ||
3115 | return 0; | |
3116 | } |