Line data Source code
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/kmsan.h>
41 : #include <linux/binfmts.h>
42 : #include <linux/mman.h>
43 : #include <linux/mmu_notifier.h>
44 : #include <linux/fs.h>
45 : #include <linux/mm.h>
46 : #include <linux/mm_inline.h>
47 : #include <linux/nsproxy.h>
48 : #include <linux/capability.h>
49 : #include <linux/cpu.h>
50 : #include <linux/cgroup.h>
51 : #include <linux/security.h>
52 : #include <linux/hugetlb.h>
53 : #include <linux/seccomp.h>
54 : #include <linux/swap.h>
55 : #include <linux/syscalls.h>
56 : #include <linux/jiffies.h>
57 : #include <linux/futex.h>
58 : #include <linux/compat.h>
59 : #include <linux/kthread.h>
60 : #include <linux/task_io_accounting_ops.h>
61 : #include <linux/rcupdate.h>
62 : #include <linux/ptrace.h>
63 : #include <linux/mount.h>
64 : #include <linux/audit.h>
65 : #include <linux/memcontrol.h>
66 : #include <linux/ftrace.h>
67 : #include <linux/proc_fs.h>
68 : #include <linux/profile.h>
69 : #include <linux/rmap.h>
70 : #include <linux/ksm.h>
71 : #include <linux/acct.h>
72 : #include <linux/userfaultfd_k.h>
73 : #include <linux/tsacct_kern.h>
74 : #include <linux/cn_proc.h>
75 : #include <linux/freezer.h>
76 : #include <linux/delayacct.h>
77 : #include <linux/taskstats_kern.h>
78 : #include <linux/tty.h>
79 : #include <linux/fs_struct.h>
80 : #include <linux/magic.h>
81 : #include <linux/perf_event.h>
82 : #include <linux/posix-timers.h>
83 : #include <linux/user-return-notifier.h>
84 : #include <linux/oom.h>
85 : #include <linux/khugepaged.h>
86 : #include <linux/signalfd.h>
87 : #include <linux/uprobes.h>
88 : #include <linux/aio.h>
89 : #include <linux/compiler.h>
90 : #include <linux/sysctl.h>
91 : #include <linux/kcov.h>
92 : #include <linux/livepatch.h>
93 : #include <linux/thread_info.h>
94 : #include <linux/stackleak.h>
95 : #include <linux/kasan.h>
96 : #include <linux/scs.h>
97 : #include <linux/io_uring.h>
98 : #include <linux/bpf.h>
99 : #include <linux/stackprotector.h>
100 : #include <linux/user_events.h>
101 : #include <linux/iommu.h>
102 :
103 : #include <asm/pgalloc.h>
104 : #include <linux/uaccess.h>
105 : #include <asm/mmu_context.h>
106 : #include <asm/cacheflush.h>
107 : #include <asm/tlbflush.h>
108 :
109 : #include <trace/events/sched.h>
110 :
111 : #define CREATE_TRACE_POINTS
112 : #include <trace/events/task.h>
113 :
114 : /*
115 : * Minimum number of threads to boot the kernel
116 : */
117 : #define MIN_THREADS 20
118 :
119 : /*
120 : * Maximum number of threads
121 : */
122 : #define MAX_THREADS FUTEX_TID_MASK
123 :
124 : /*
125 : * Protected counters by write_lock_irq(&tasklist_lock)
126 : */
127 : unsigned long total_forks; /* Handle normal Linux uptimes. */
128 : int nr_threads; /* The idle threads do not count.. */
129 :
130 : static int max_threads; /* tunable limit on nr_threads */
131 :
132 : #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
133 :
134 : static const char * const resident_page_types[] = {
135 : NAMED_ARRAY_INDEX(MM_FILEPAGES),
136 : NAMED_ARRAY_INDEX(MM_ANONPAGES),
137 : NAMED_ARRAY_INDEX(MM_SWAPENTS),
138 : NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
139 : };
140 :
141 : DEFINE_PER_CPU(unsigned long, process_counts) = 0;
142 :
143 : __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
144 :
145 : #ifdef CONFIG_PROVE_RCU
146 : int lockdep_tasklist_lock_is_held(void)
147 : {
148 : return lockdep_is_held(&tasklist_lock);
149 : }
150 : EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
151 : #endif /* #ifdef CONFIG_PROVE_RCU */
152 :
153 0 : int nr_processes(void)
154 : {
155 : int cpu;
156 0 : int total = 0;
157 :
158 0 : for_each_possible_cpu(cpu)
159 0 : total += per_cpu(process_counts, cpu);
160 :
161 0 : return total;
162 : }
163 :
164 366 : void __weak arch_release_task_struct(struct task_struct *tsk)
165 : {
166 366 : }
167 :
168 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
169 : static struct kmem_cache *task_struct_cachep;
170 :
171 : static inline struct task_struct *alloc_task_struct_node(int node)
172 : {
173 382 : return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
174 : }
175 :
176 : static inline void free_task_struct(struct task_struct *tsk)
177 : {
178 366 : kmem_cache_free(task_struct_cachep, tsk);
179 : }
180 : #endif
181 :
182 : #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
183 :
184 : /*
185 : * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
186 : * kmemcache based allocator.
187 : */
188 : # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
189 :
190 : # ifdef CONFIG_VMAP_STACK
191 : /*
192 : * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
193 : * flush. Try to minimize the number of calls by caching stacks.
194 : */
195 : #define NR_CACHED_STACKS 2
196 : static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
197 :
198 : struct vm_stack {
199 : struct rcu_head rcu;
200 : struct vm_struct *stack_vm_area;
201 : };
202 :
203 366 : static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
204 : {
205 : unsigned int i;
206 :
207 366 : for (i = 0; i < NR_CACHED_STACKS; i++) {
208 1098 : if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
209 0 : continue;
210 : return true;
211 : }
212 : return false;
213 : }
214 :
215 0 : static void thread_stack_free_rcu(struct rcu_head *rh)
216 : {
217 0 : struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
218 :
219 0 : if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
220 : return;
221 :
222 0 : vfree(vm_stack);
223 : }
224 :
225 : static void thread_stack_delayed_free(struct task_struct *tsk)
226 : {
227 0 : struct vm_stack *vm_stack = tsk->stack;
228 :
229 0 : vm_stack->stack_vm_area = tsk->stack_vm_area;
230 0 : call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
231 : }
232 :
233 0 : static int free_vm_stack_cache(unsigned int cpu)
234 : {
235 0 : struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
236 : int i;
237 :
238 0 : for (i = 0; i < NR_CACHED_STACKS; i++) {
239 0 : struct vm_struct *vm_stack = cached_vm_stacks[i];
240 :
241 0 : if (!vm_stack)
242 0 : continue;
243 :
244 0 : vfree(vm_stack->addr);
245 0 : cached_vm_stacks[i] = NULL;
246 : }
247 :
248 0 : return 0;
249 : }
250 :
251 382 : static int memcg_charge_kernel_stack(struct vm_struct *vm)
252 : {
253 : int i;
254 : int ret;
255 :
256 : BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
257 382 : BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
258 :
259 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
260 : ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
261 : if (ret)
262 : goto err;
263 : }
264 : return 0;
265 : err:
266 : /*
267 : * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
268 : * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
269 : * ignore this page.
270 : */
271 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
272 : memcg_kmem_uncharge_page(vm->pages[i], 0);
273 : return ret;
274 : }
275 :
276 382 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
277 : {
278 : struct vm_struct *vm;
279 : void *stack;
280 : int i;
281 :
282 828 : for (i = 0; i < NR_CACHED_STACKS; i++) {
283 : struct vm_struct *s;
284 :
285 1194 : s = this_cpu_xchg(cached_stacks[i], NULL);
286 :
287 398 : if (!s)
288 32 : continue;
289 :
290 : /* Reset stack metadata. */
291 366 : kasan_unpoison_range(s->addr, THREAD_SIZE);
292 :
293 366 : stack = kasan_reset_tag(s->addr);
294 :
295 : /* Clear stale pointers from reused stack. */
296 366 : memset(stack, 0, THREAD_SIZE);
297 :
298 366 : if (memcg_charge_kernel_stack(s)) {
299 0 : vfree(s->addr);
300 : return -ENOMEM;
301 : }
302 :
303 366 : tsk->stack_vm_area = s;
304 366 : tsk->stack = stack;
305 : return 0;
306 : }
307 :
308 : /*
309 : * Allocated stacks are cached and later reused by new threads,
310 : * so memcg accounting is performed manually on assigning/releasing
311 : * stacks to tasks. Drop __GFP_ACCOUNT.
312 : */
313 32 : stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
314 16 : VMALLOC_START, VMALLOC_END,
315 : THREADINFO_GFP & ~__GFP_ACCOUNT,
316 16 : PAGE_KERNEL,
317 16 : 0, node, __builtin_return_address(0));
318 16 : if (!stack)
319 : return -ENOMEM;
320 :
321 16 : vm = find_vm_area(stack);
322 16 : if (memcg_charge_kernel_stack(vm)) {
323 0 : vfree(stack);
324 : return -ENOMEM;
325 : }
326 : /*
327 : * We can't call find_vm_area() in interrupt context, and
328 : * free_thread_stack() can be called in interrupt context,
329 : * so cache the vm_struct.
330 : */
331 16 : tsk->stack_vm_area = vm;
332 16 : stack = kasan_reset_tag(stack);
333 16 : tsk->stack = stack;
334 : return 0;
335 : }
336 :
337 366 : static void free_thread_stack(struct task_struct *tsk)
338 : {
339 366 : if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
340 0 : thread_stack_delayed_free(tsk);
341 :
342 366 : tsk->stack = NULL;
343 366 : tsk->stack_vm_area = NULL;
344 366 : }
345 :
346 : # else /* !CONFIG_VMAP_STACK */
347 :
348 : static void thread_stack_free_rcu(struct rcu_head *rh)
349 : {
350 : __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
351 : }
352 :
353 : static void thread_stack_delayed_free(struct task_struct *tsk)
354 : {
355 : struct rcu_head *rh = tsk->stack;
356 :
357 : call_rcu(rh, thread_stack_free_rcu);
358 : }
359 :
360 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
361 : {
362 : struct page *page = alloc_pages_node(node, THREADINFO_GFP,
363 : THREAD_SIZE_ORDER);
364 :
365 : if (likely(page)) {
366 : tsk->stack = kasan_reset_tag(page_address(page));
367 : return 0;
368 : }
369 : return -ENOMEM;
370 : }
371 :
372 : static void free_thread_stack(struct task_struct *tsk)
373 : {
374 : thread_stack_delayed_free(tsk);
375 : tsk->stack = NULL;
376 : }
377 :
378 : # endif /* CONFIG_VMAP_STACK */
379 : # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
380 :
381 : static struct kmem_cache *thread_stack_cache;
382 :
383 : static void thread_stack_free_rcu(struct rcu_head *rh)
384 : {
385 : kmem_cache_free(thread_stack_cache, rh);
386 : }
387 :
388 : static void thread_stack_delayed_free(struct task_struct *tsk)
389 : {
390 : struct rcu_head *rh = tsk->stack;
391 :
392 : call_rcu(rh, thread_stack_free_rcu);
393 : }
394 :
395 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
396 : {
397 : unsigned long *stack;
398 : stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
399 : stack = kasan_reset_tag(stack);
400 : tsk->stack = stack;
401 : return stack ? 0 : -ENOMEM;
402 : }
403 :
404 : static void free_thread_stack(struct task_struct *tsk)
405 : {
406 : thread_stack_delayed_free(tsk);
407 : tsk->stack = NULL;
408 : }
409 :
410 : void thread_stack_cache_init(void)
411 : {
412 : thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
413 : THREAD_SIZE, THREAD_SIZE, 0, 0,
414 : THREAD_SIZE, NULL);
415 : BUG_ON(thread_stack_cache == NULL);
416 : }
417 :
418 : # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
419 : #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
420 :
421 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
422 : {
423 : unsigned long *stack;
424 :
425 : stack = arch_alloc_thread_stack_node(tsk, node);
426 : tsk->stack = stack;
427 : return stack ? 0 : -ENOMEM;
428 : }
429 :
430 : static void free_thread_stack(struct task_struct *tsk)
431 : {
432 : arch_free_thread_stack(tsk);
433 : tsk->stack = NULL;
434 : }
435 :
436 : #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
437 :
438 : /* SLAB cache for signal_struct structures (tsk->signal) */
439 : static struct kmem_cache *signal_cachep;
440 :
441 : /* SLAB cache for sighand_struct structures (tsk->sighand) */
442 : struct kmem_cache *sighand_cachep;
443 :
444 : /* SLAB cache for files_struct structures (tsk->files) */
445 : struct kmem_cache *files_cachep;
446 :
447 : /* SLAB cache for fs_struct structures (tsk->fs) */
448 : struct kmem_cache *fs_cachep;
449 :
450 : /* SLAB cache for vm_area_struct structures */
451 : static struct kmem_cache *vm_area_cachep;
452 :
453 : /* SLAB cache for mm_struct structures (tsk->mm) */
454 : static struct kmem_cache *mm_cachep;
455 :
456 : #ifdef CONFIG_PER_VMA_LOCK
457 :
458 : /* SLAB cache for vm_area_struct.lock */
459 : static struct kmem_cache *vma_lock_cachep;
460 :
461 : static bool vma_lock_alloc(struct vm_area_struct *vma)
462 : {
463 : vma->vm_lock = kmem_cache_alloc(vma_lock_cachep, GFP_KERNEL);
464 : if (!vma->vm_lock)
465 : return false;
466 :
467 : init_rwsem(&vma->vm_lock->lock);
468 : vma->vm_lock_seq = -1;
469 :
470 : return true;
471 : }
472 :
473 : static inline void vma_lock_free(struct vm_area_struct *vma)
474 : {
475 : kmem_cache_free(vma_lock_cachep, vma->vm_lock);
476 : }
477 :
478 : #else /* CONFIG_PER_VMA_LOCK */
479 :
480 : static inline bool vma_lock_alloc(struct vm_area_struct *vma) { return true; }
481 : static inline void vma_lock_free(struct vm_area_struct *vma) {}
482 :
483 : #endif /* CONFIG_PER_VMA_LOCK */
484 :
485 0 : struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
486 : {
487 : struct vm_area_struct *vma;
488 :
489 0 : vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
490 0 : if (!vma)
491 : return NULL;
492 :
493 0 : vma_init(vma, mm);
494 0 : if (!vma_lock_alloc(vma)) {
495 : kmem_cache_free(vm_area_cachep, vma);
496 : return NULL;
497 : }
498 :
499 0 : return vma;
500 : }
501 :
502 0 : struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
503 : {
504 0 : struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
505 :
506 0 : if (!new)
507 : return NULL;
508 :
509 0 : ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
510 0 : ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
511 : /*
512 : * orig->shared.rb may be modified concurrently, but the clone
513 : * will be reinitialized.
514 : */
515 0 : data_race(memcpy(new, orig, sizeof(*new)));
516 0 : if (!vma_lock_alloc(new)) {
517 : kmem_cache_free(vm_area_cachep, new);
518 : return NULL;
519 : }
520 0 : INIT_LIST_HEAD(&new->anon_vma_chain);
521 0 : vma_numab_state_init(new);
522 0 : dup_anon_vma_name(orig, new);
523 :
524 0 : return new;
525 : }
526 :
527 0 : void __vm_area_free(struct vm_area_struct *vma)
528 : {
529 0 : vma_numab_state_free(vma);
530 0 : free_anon_vma_name(vma);
531 0 : vma_lock_free(vma);
532 0 : kmem_cache_free(vm_area_cachep, vma);
533 0 : }
534 :
535 : #ifdef CONFIG_PER_VMA_LOCK
536 : static void vm_area_free_rcu_cb(struct rcu_head *head)
537 : {
538 : struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
539 : vm_rcu);
540 :
541 : /* The vma should not be locked while being destroyed. */
542 : VM_BUG_ON_VMA(rwsem_is_locked(&vma->vm_lock->lock), vma);
543 : __vm_area_free(vma);
544 : }
545 : #endif
546 :
547 0 : void vm_area_free(struct vm_area_struct *vma)
548 : {
549 : #ifdef CONFIG_PER_VMA_LOCK
550 : call_rcu(&vma->vm_rcu, vm_area_free_rcu_cb);
551 : #else
552 0 : __vm_area_free(vma);
553 : #endif
554 0 : }
555 :
556 : static void account_kernel_stack(struct task_struct *tsk, int account)
557 : {
558 : if (IS_ENABLED(CONFIG_VMAP_STACK)) {
559 : struct vm_struct *vm = task_stack_vm_area(tsk);
560 : int i;
561 :
562 2996 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
563 5992 : mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
564 : account * (PAGE_SIZE / 1024));
565 : } else {
566 : void *stack = task_stack_page(tsk);
567 :
568 : /* All stack pages are in the same node. */
569 : mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
570 : account * (THREAD_SIZE / 1024));
571 : }
572 : }
573 :
574 367 : void exit_task_stack_account(struct task_struct *tsk)
575 : {
576 734 : account_kernel_stack(tsk, -1);
577 :
578 : if (IS_ENABLED(CONFIG_VMAP_STACK)) {
579 : struct vm_struct *vm;
580 : int i;
581 :
582 367 : vm = task_stack_vm_area(tsk);
583 367 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
584 : memcg_kmem_uncharge_page(vm->pages[i], 0);
585 : }
586 367 : }
587 :
588 366 : static void release_task_stack(struct task_struct *tsk)
589 : {
590 366 : if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
591 : return; /* Better to leak the stack than to free prematurely */
592 :
593 366 : free_thread_stack(tsk);
594 : }
595 :
596 : #ifdef CONFIG_THREAD_INFO_IN_TASK
597 : void put_task_stack(struct task_struct *tsk)
598 : {
599 : if (refcount_dec_and_test(&tsk->stack_refcount))
600 : release_task_stack(tsk);
601 : }
602 : #endif
603 :
604 366 : void free_task(struct task_struct *tsk)
605 : {
606 : #ifdef CONFIG_SECCOMP
607 366 : WARN_ON_ONCE(tsk->seccomp.filter);
608 : #endif
609 366 : release_user_cpus_ptr(tsk);
610 366 : scs_release(tsk);
611 :
612 : #ifndef CONFIG_THREAD_INFO_IN_TASK
613 : /*
614 : * The task is finally done with both the stack and thread_info,
615 : * so free both.
616 : */
617 366 : release_task_stack(tsk);
618 : #else
619 : /*
620 : * If the task had a separate stack allocation, it should be gone
621 : * by now.
622 : */
623 : WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
624 : #endif
625 366 : rt_mutex_debug_task_free(tsk);
626 366 : ftrace_graph_exit_task(tsk);
627 366 : arch_release_task_struct(tsk);
628 366 : if (tsk->flags & PF_KTHREAD)
629 366 : free_kthread_struct(tsk);
630 366 : bpf_task_storage_free(tsk);
631 366 : free_task_struct(tsk);
632 366 : }
633 : EXPORT_SYMBOL(free_task);
634 :
635 0 : static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
636 : {
637 : struct file *exe_file;
638 :
639 0 : exe_file = get_mm_exe_file(oldmm);
640 0 : RCU_INIT_POINTER(mm->exe_file, exe_file);
641 : /*
642 : * We depend on the oldmm having properly denied write access to the
643 : * exe_file already.
644 : */
645 0 : if (exe_file && deny_write_access(exe_file))
646 0 : pr_warn_once("deny_write_access() failed in %s\n", __func__);
647 0 : }
648 :
649 : #ifdef CONFIG_MMU
650 0 : static __latent_entropy int dup_mmap(struct mm_struct *mm,
651 : struct mm_struct *oldmm)
652 : {
653 : struct vm_area_struct *mpnt, *tmp;
654 : int retval;
655 0 : unsigned long charge = 0;
656 0 : LIST_HEAD(uf);
657 0 : VMA_ITERATOR(old_vmi, oldmm, 0);
658 0 : VMA_ITERATOR(vmi, mm, 0);
659 :
660 0 : uprobe_start_dup_mmap();
661 0 : if (mmap_write_lock_killable(oldmm)) {
662 : retval = -EINTR;
663 : goto fail_uprobe_end;
664 : }
665 0 : flush_cache_dup_mm(oldmm);
666 0 : uprobe_dup_mmap(oldmm, mm);
667 : /*
668 : * Not linked in yet - no deadlock potential:
669 : */
670 0 : mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
671 :
672 : /* No ordering required: file already has been exposed. */
673 0 : dup_mm_exe_file(mm, oldmm);
674 :
675 0 : mm->total_vm = oldmm->total_vm;
676 0 : mm->data_vm = oldmm->data_vm;
677 0 : mm->exec_vm = oldmm->exec_vm;
678 0 : mm->stack_vm = oldmm->stack_vm;
679 :
680 0 : retval = ksm_fork(mm, oldmm);
681 : if (retval)
682 : goto out;
683 0 : khugepaged_fork(mm, oldmm);
684 :
685 0 : retval = vma_iter_bulk_alloc(&vmi, oldmm->map_count);
686 0 : if (retval)
687 : goto out;
688 :
689 0 : mt_clear_in_rcu(vmi.mas.tree);
690 0 : for_each_vma(old_vmi, mpnt) {
691 : struct file *file;
692 :
693 0 : if (mpnt->vm_flags & VM_DONTCOPY) {
694 0 : vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
695 0 : continue;
696 : }
697 0 : charge = 0;
698 : /*
699 : * Don't duplicate many vmas if we've been oom-killed (for
700 : * example)
701 : */
702 0 : if (fatal_signal_pending(current)) {
703 : retval = -EINTR;
704 : goto loop_out;
705 : }
706 0 : if (mpnt->vm_flags & VM_ACCOUNT) {
707 0 : unsigned long len = vma_pages(mpnt);
708 :
709 0 : if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
710 : goto fail_nomem;
711 : charge = len;
712 : }
713 0 : tmp = vm_area_dup(mpnt);
714 0 : if (!tmp)
715 : goto fail_nomem;
716 0 : retval = vma_dup_policy(mpnt, tmp);
717 : if (retval)
718 : goto fail_nomem_policy;
719 0 : tmp->vm_mm = mm;
720 0 : retval = dup_userfaultfd(tmp, &uf);
721 : if (retval)
722 : goto fail_nomem_anon_vma_fork;
723 0 : if (tmp->vm_flags & VM_WIPEONFORK) {
724 : /*
725 : * VM_WIPEONFORK gets a clean slate in the child.
726 : * Don't prepare anon_vma until fault since we don't
727 : * copy page for current vma.
728 : */
729 0 : tmp->anon_vma = NULL;
730 0 : } else if (anon_vma_fork(tmp, mpnt))
731 : goto fail_nomem_anon_vma_fork;
732 0 : vm_flags_clear(tmp, VM_LOCKED_MASK);
733 0 : file = tmp->vm_file;
734 0 : if (file) {
735 0 : struct address_space *mapping = file->f_mapping;
736 :
737 0 : get_file(file);
738 0 : i_mmap_lock_write(mapping);
739 0 : if (tmp->vm_flags & VM_SHARED)
740 : mapping_allow_writable(mapping);
741 0 : flush_dcache_mmap_lock(mapping);
742 : /* insert tmp into the share list, just after mpnt */
743 0 : vma_interval_tree_insert_after(tmp, mpnt,
744 : &mapping->i_mmap);
745 0 : flush_dcache_mmap_unlock(mapping);
746 : i_mmap_unlock_write(mapping);
747 : }
748 :
749 : /*
750 : * Copy/update hugetlb private vma information.
751 : */
752 0 : if (is_vm_hugetlb_page(tmp))
753 : hugetlb_dup_vma_private(tmp);
754 :
755 : /* Link the vma into the MT */
756 0 : if (vma_iter_bulk_store(&vmi, tmp))
757 : goto fail_nomem_vmi_store;
758 :
759 0 : mm->map_count++;
760 0 : if (!(tmp->vm_flags & VM_WIPEONFORK))
761 0 : retval = copy_page_range(tmp, mpnt);
762 :
763 0 : if (tmp->vm_ops && tmp->vm_ops->open)
764 0 : tmp->vm_ops->open(tmp);
765 :
766 0 : if (retval)
767 : goto loop_out;
768 : }
769 : /* a new mm has just been created */
770 : retval = arch_dup_mmap(oldmm, mm);
771 : loop_out:
772 0 : vma_iter_free(&vmi);
773 0 : if (!retval)
774 0 : mt_set_in_rcu(vmi.mas.tree);
775 : out:
776 0 : mmap_write_unlock(mm);
777 0 : flush_tlb_mm(oldmm);
778 : mmap_write_unlock(oldmm);
779 : dup_userfaultfd_complete(&uf);
780 : fail_uprobe_end:
781 : uprobe_end_dup_mmap();
782 0 : return retval;
783 :
784 : fail_nomem_vmi_store:
785 0 : unlink_anon_vmas(tmp);
786 : fail_nomem_anon_vma_fork:
787 0 : mpol_put(vma_policy(tmp));
788 : fail_nomem_policy:
789 : vm_area_free(tmp);
790 : fail_nomem:
791 0 : retval = -ENOMEM;
792 0 : vm_unacct_memory(charge);
793 : goto loop_out;
794 : }
795 :
796 : static inline int mm_alloc_pgd(struct mm_struct *mm)
797 : {
798 0 : mm->pgd = pgd_alloc(mm);
799 0 : if (unlikely(!mm->pgd))
800 : return -ENOMEM;
801 : return 0;
802 : }
803 :
804 : static inline void mm_free_pgd(struct mm_struct *mm)
805 : {
806 0 : pgd_free(mm, mm->pgd);
807 : }
808 : #else
809 : static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
810 : {
811 : mmap_write_lock(oldmm);
812 : dup_mm_exe_file(mm, oldmm);
813 : mmap_write_unlock(oldmm);
814 : return 0;
815 : }
816 : #define mm_alloc_pgd(mm) (0)
817 : #define mm_free_pgd(mm)
818 : #endif /* CONFIG_MMU */
819 :
820 0 : static void check_mm(struct mm_struct *mm)
821 : {
822 : int i;
823 :
824 : BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
825 : "Please make sure 'struct resident_page_types[]' is updated as well");
826 :
827 0 : for (i = 0; i < NR_MM_COUNTERS; i++) {
828 0 : long x = percpu_counter_sum(&mm->rss_stat[i]);
829 :
830 0 : if (unlikely(x))
831 0 : pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
832 : mm, resident_page_types[i], x);
833 : }
834 :
835 0 : if (mm_pgtables_bytes(mm))
836 0 : pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
837 : mm_pgtables_bytes(mm));
838 :
839 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
840 : VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
841 : #endif
842 0 : }
843 :
844 : #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
845 : #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
846 :
847 : static void do_check_lazy_tlb(void *arg)
848 : {
849 : struct mm_struct *mm = arg;
850 :
851 : WARN_ON_ONCE(current->active_mm == mm);
852 : }
853 :
854 : static void do_shoot_lazy_tlb(void *arg)
855 : {
856 : struct mm_struct *mm = arg;
857 :
858 : if (current->active_mm == mm) {
859 : WARN_ON_ONCE(current->mm);
860 : current->active_mm = &init_mm;
861 : switch_mm(mm, &init_mm, current);
862 : }
863 : }
864 :
865 : static void cleanup_lazy_tlbs(struct mm_struct *mm)
866 : {
867 : if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN)) {
868 : /*
869 : * In this case, lazy tlb mms are refounted and would not reach
870 : * __mmdrop until all CPUs have switched away and mmdrop()ed.
871 : */
872 : return;
873 : }
874 :
875 : /*
876 : * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it
877 : * requires lazy mm users to switch to another mm when the refcount
878 : * drops to zero, before the mm is freed. This requires IPIs here to
879 : * switch kernel threads to init_mm.
880 : *
881 : * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm
882 : * switch with the final userspace teardown TLB flush which leaves the
883 : * mm lazy on this CPU but no others, reducing the need for additional
884 : * IPIs here. There are cases where a final IPI is still required here,
885 : * such as the final mmdrop being performed on a different CPU than the
886 : * one exiting, or kernel threads using the mm when userspace exits.
887 : *
888 : * IPI overheads have not found to be expensive, but they could be
889 : * reduced in a number of possible ways, for example (roughly
890 : * increasing order of complexity):
891 : * - The last lazy reference created by exit_mm() could instead switch
892 : * to init_mm, however it's probable this will run on the same CPU
893 : * immediately afterwards, so this may not reduce IPIs much.
894 : * - A batch of mms requiring IPIs could be gathered and freed at once.
895 : * - CPUs store active_mm where it can be remotely checked without a
896 : * lock, to filter out false-positives in the cpumask.
897 : * - After mm_users or mm_count reaches zero, switching away from the
898 : * mm could clear mm_cpumask to reduce some IPIs, perhaps together
899 : * with some batching or delaying of the final IPIs.
900 : * - A delayed freeing and RCU-like quiescing sequence based on mm
901 : * switching to avoid IPIs completely.
902 : */
903 : on_each_cpu_mask(mm_cpumask(mm), do_shoot_lazy_tlb, (void *)mm, 1);
904 : if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES))
905 : on_each_cpu(do_check_lazy_tlb, (void *)mm, 1);
906 : }
907 :
908 : /*
909 : * Called when the last reference to the mm
910 : * is dropped: either by a lazy thread or by
911 : * mmput. Free the page directory and the mm.
912 : */
913 0 : void __mmdrop(struct mm_struct *mm)
914 : {
915 : int i;
916 :
917 0 : BUG_ON(mm == &init_mm);
918 0 : WARN_ON_ONCE(mm == current->mm);
919 :
920 : /* Ensure no CPUs are using this as their lazy tlb mm */
921 0 : cleanup_lazy_tlbs(mm);
922 :
923 0 : WARN_ON_ONCE(mm == current->active_mm);
924 0 : mm_free_pgd(mm);
925 0 : destroy_context(mm);
926 0 : mmu_notifier_subscriptions_destroy(mm);
927 0 : check_mm(mm);
928 0 : put_user_ns(mm->user_ns);
929 0 : mm_pasid_drop(mm);
930 0 : mm_destroy_cid(mm);
931 :
932 0 : for (i = 0; i < NR_MM_COUNTERS; i++)
933 : percpu_counter_destroy(&mm->rss_stat[i]);
934 0 : free_mm(mm);
935 0 : }
936 : EXPORT_SYMBOL_GPL(__mmdrop);
937 :
938 0 : static void mmdrop_async_fn(struct work_struct *work)
939 : {
940 : struct mm_struct *mm;
941 :
942 0 : mm = container_of(work, struct mm_struct, async_put_work);
943 0 : __mmdrop(mm);
944 0 : }
945 :
946 0 : static void mmdrop_async(struct mm_struct *mm)
947 : {
948 0 : if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
949 0 : INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
950 0 : schedule_work(&mm->async_put_work);
951 : }
952 0 : }
953 :
954 366 : static inline void free_signal_struct(struct signal_struct *sig)
955 : {
956 366 : taskstats_tgid_free(sig);
957 366 : sched_autogroup_exit(sig);
958 : /*
959 : * __mmdrop is not safe to call from softirq context on x86 due to
960 : * pgd_dtor so postpone it to the async context
961 : */
962 366 : if (sig->oom_mm)
963 0 : mmdrop_async(sig->oom_mm);
964 366 : kmem_cache_free(signal_cachep, sig);
965 366 : }
966 :
967 366 : static inline void put_signal_struct(struct signal_struct *sig)
968 : {
969 732 : if (refcount_dec_and_test(&sig->sigcnt))
970 366 : free_signal_struct(sig);
971 366 : }
972 :
973 366 : void __put_task_struct(struct task_struct *tsk)
974 : {
975 366 : WARN_ON(!tsk->exit_state);
976 732 : WARN_ON(refcount_read(&tsk->usage));
977 366 : WARN_ON(tsk == current);
978 :
979 366 : io_uring_free(tsk);
980 366 : cgroup_free(tsk);
981 366 : task_numa_free(tsk, true);
982 366 : security_task_free(tsk);
983 366 : exit_creds(tsk);
984 366 : delayacct_tsk_free(tsk);
985 366 : put_signal_struct(tsk->signal);
986 366 : sched_core_free(tsk);
987 366 : free_task(tsk);
988 366 : }
989 : EXPORT_SYMBOL_GPL(__put_task_struct);
990 :
991 1 : void __init __weak arch_task_cache_init(void) { }
992 :
993 : /*
994 : * set_max_threads
995 : */
996 : static void set_max_threads(unsigned int max_threads_suggested)
997 : {
998 : u64 threads;
999 1 : unsigned long nr_pages = totalram_pages();
1000 :
1001 : /*
1002 : * The number of threads shall be limited such that the thread
1003 : * structures may only consume a small part of the available memory.
1004 : */
1005 2 : if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
1006 : threads = MAX_THREADS;
1007 : else
1008 2 : threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
1009 : (u64) THREAD_SIZE * 8UL);
1010 :
1011 1 : if (threads > max_threads_suggested)
1012 0 : threads = max_threads_suggested;
1013 :
1014 1 : max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
1015 : }
1016 :
1017 : #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
1018 : /* Initialized by the architecture: */
1019 : int arch_task_struct_size __read_mostly;
1020 : #endif
1021 :
1022 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
1023 : static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
1024 : {
1025 : /* Fetch thread_struct whitelist for the architecture. */
1026 1 : arch_thread_struct_whitelist(offset, size);
1027 :
1028 : /*
1029 : * Handle zero-sized whitelist or empty thread_struct, otherwise
1030 : * adjust offset to position of thread_struct in task_struct.
1031 : */
1032 : if (unlikely(*size == 0))
1033 : *offset = 0;
1034 : else
1035 1 : *offset += offsetof(struct task_struct, thread);
1036 : }
1037 : #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
1038 :
1039 1 : void __init fork_init(void)
1040 : {
1041 : int i;
1042 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
1043 : #ifndef ARCH_MIN_TASKALIGN
1044 : #define ARCH_MIN_TASKALIGN 0
1045 : #endif
1046 1 : int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
1047 : unsigned long useroffset, usersize;
1048 :
1049 : /* create a slab on which task_structs can be allocated */
1050 1 : task_struct_whitelist(&useroffset, &usersize);
1051 1 : task_struct_cachep = kmem_cache_create_usercopy("task_struct",
1052 : arch_task_struct_size, align,
1053 : SLAB_PANIC|SLAB_ACCOUNT,
1054 : useroffset, usersize, NULL);
1055 : #endif
1056 :
1057 : /* do the arch specific task caches init */
1058 1 : arch_task_cache_init();
1059 :
1060 1 : set_max_threads(MAX_THREADS);
1061 :
1062 1 : init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
1063 1 : init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
1064 1 : init_task.signal->rlim[RLIMIT_SIGPENDING] =
1065 : init_task.signal->rlim[RLIMIT_NPROC];
1066 :
1067 11 : for (i = 0; i < UCOUNT_COUNTS; i++)
1068 10 : init_user_ns.ucount_max[i] = max_threads/2;
1069 :
1070 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
1071 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
1072 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
1073 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
1074 :
1075 : #ifdef CONFIG_VMAP_STACK
1076 1 : cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
1077 : NULL, free_vm_stack_cache);
1078 : #endif
1079 :
1080 : scs_init();
1081 :
1082 1 : lockdep_init_task(&init_task);
1083 : uprobes_init();
1084 1 : }
1085 :
1086 382 : int __weak arch_dup_task_struct(struct task_struct *dst,
1087 : struct task_struct *src)
1088 : {
1089 382 : *dst = *src;
1090 382 : return 0;
1091 : }
1092 :
1093 1 : void set_task_stack_end_magic(struct task_struct *tsk)
1094 : {
1095 : unsigned long *stackend;
1096 :
1097 383 : stackend = end_of_stack(tsk);
1098 383 : *stackend = STACK_END_MAGIC; /* for overflow detection */
1099 1 : }
1100 :
1101 382 : static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
1102 : {
1103 : struct task_struct *tsk;
1104 : int err;
1105 :
1106 382 : if (node == NUMA_NO_NODE)
1107 382 : node = tsk_fork_get_node(orig);
1108 382 : tsk = alloc_task_struct_node(node);
1109 382 : if (!tsk)
1110 : return NULL;
1111 :
1112 382 : err = arch_dup_task_struct(tsk, orig);
1113 382 : if (err)
1114 : goto free_tsk;
1115 :
1116 382 : err = alloc_thread_stack_node(tsk, node);
1117 382 : if (err)
1118 : goto free_tsk;
1119 :
1120 : #ifdef CONFIG_THREAD_INFO_IN_TASK
1121 : refcount_set(&tsk->stack_refcount, 1);
1122 : #endif
1123 382 : account_kernel_stack(tsk, 1);
1124 :
1125 382 : err = scs_prepare(tsk, node);
1126 : if (err)
1127 : goto free_stack;
1128 :
1129 : #ifdef CONFIG_SECCOMP
1130 : /*
1131 : * We must handle setting up seccomp filters once we're under
1132 : * the sighand lock in case orig has changed between now and
1133 : * then. Until then, filter must be NULL to avoid messing up
1134 : * the usage counts on the error path calling free_task.
1135 : */
1136 382 : tsk->seccomp.filter = NULL;
1137 : #endif
1138 :
1139 764 : setup_thread_stack(tsk, orig);
1140 382 : clear_user_return_notifier(tsk);
1141 382 : clear_tsk_need_resched(tsk);
1142 382 : set_task_stack_end_magic(tsk);
1143 : clear_syscall_work_syscall_user_dispatch(tsk);
1144 :
1145 : #ifdef CONFIG_STACKPROTECTOR
1146 : tsk->stack_canary = get_random_canary();
1147 : #endif
1148 382 : if (orig->cpus_ptr == &orig->cpus_mask)
1149 382 : tsk->cpus_ptr = &tsk->cpus_mask;
1150 382 : dup_user_cpus_ptr(tsk, orig, node);
1151 :
1152 : /*
1153 : * One for the user space visible state that goes away when reaped.
1154 : * One for the scheduler.
1155 : */
1156 764 : refcount_set(&tsk->rcu_users, 2);
1157 : /* One for the rcu users */
1158 764 : refcount_set(&tsk->usage, 1);
1159 : #ifdef CONFIG_BLK_DEV_IO_TRACE
1160 : tsk->btrace_seq = 0;
1161 : #endif
1162 382 : tsk->splice_pipe = NULL;
1163 382 : tsk->task_frag.page = NULL;
1164 382 : tsk->wake_q.next = NULL;
1165 382 : tsk->worker_private = NULL;
1166 :
1167 : kcov_task_init(tsk);
1168 : kmsan_task_create(tsk);
1169 : kmap_local_fork(tsk);
1170 :
1171 : #ifdef CONFIG_FAULT_INJECTION
1172 : tsk->fail_nth = 0;
1173 : #endif
1174 :
1175 : #ifdef CONFIG_BLK_CGROUP
1176 : tsk->throttle_disk = NULL;
1177 : tsk->use_memdelay = 0;
1178 : #endif
1179 :
1180 : #ifdef CONFIG_IOMMU_SVA
1181 : tsk->pasid_activated = 0;
1182 : #endif
1183 :
1184 : #ifdef CONFIG_MEMCG
1185 : tsk->active_memcg = NULL;
1186 : #endif
1187 :
1188 : #ifdef CONFIG_CPU_SUP_INTEL
1189 382 : tsk->reported_split_lock = 0;
1190 : #endif
1191 :
1192 : #ifdef CONFIG_SCHED_MM_CID
1193 : tsk->mm_cid = -1;
1194 : tsk->last_mm_cid = -1;
1195 : tsk->mm_cid_active = 0;
1196 : tsk->migrate_from_cpu = -1;
1197 : #endif
1198 382 : return tsk;
1199 :
1200 : free_stack:
1201 : exit_task_stack_account(tsk);
1202 : free_thread_stack(tsk);
1203 : free_tsk:
1204 0 : free_task_struct(tsk);
1205 0 : return NULL;
1206 : }
1207 :
1208 : __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1209 :
1210 : static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1211 :
1212 0 : static int __init coredump_filter_setup(char *s)
1213 : {
1214 0 : default_dump_filter =
1215 0 : (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1216 : MMF_DUMP_FILTER_MASK;
1217 0 : return 1;
1218 : }
1219 :
1220 : __setup("coredump_filter=", coredump_filter_setup);
1221 :
1222 : #include <linux/init_task.h>
1223 :
1224 : static void mm_init_aio(struct mm_struct *mm)
1225 : {
1226 : #ifdef CONFIG_AIO
1227 0 : spin_lock_init(&mm->ioctx_lock);
1228 0 : mm->ioctx_table = NULL;
1229 : #endif
1230 : }
1231 :
1232 : static __always_inline void mm_clear_owner(struct mm_struct *mm,
1233 : struct task_struct *p)
1234 : {
1235 : #ifdef CONFIG_MEMCG
1236 : if (mm->owner == p)
1237 : WRITE_ONCE(mm->owner, NULL);
1238 : #endif
1239 : }
1240 :
1241 : static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1242 : {
1243 : #ifdef CONFIG_MEMCG
1244 : mm->owner = p;
1245 : #endif
1246 : }
1247 :
1248 : static void mm_init_uprobes_state(struct mm_struct *mm)
1249 : {
1250 : #ifdef CONFIG_UPROBES
1251 : mm->uprobes_state.xol_area = NULL;
1252 : #endif
1253 : }
1254 :
1255 0 : static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1256 : struct user_namespace *user_ns)
1257 : {
1258 : int i;
1259 :
1260 0 : mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
1261 : mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
1262 0 : atomic_set(&mm->mm_users, 1);
1263 0 : atomic_set(&mm->mm_count, 1);
1264 0 : seqcount_init(&mm->write_protect_seq);
1265 0 : mmap_init_lock(mm);
1266 0 : INIT_LIST_HEAD(&mm->mmlist);
1267 : #ifdef CONFIG_PER_VMA_LOCK
1268 : mm->mm_lock_seq = 0;
1269 : #endif
1270 0 : mm_pgtables_bytes_init(mm);
1271 0 : mm->map_count = 0;
1272 0 : mm->locked_vm = 0;
1273 0 : atomic64_set(&mm->pinned_vm, 0);
1274 0 : memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1275 0 : spin_lock_init(&mm->page_table_lock);
1276 0 : spin_lock_init(&mm->arg_lock);
1277 0 : mm_init_cpumask(mm);
1278 0 : mm_init_aio(mm);
1279 0 : mm_init_owner(mm, p);
1280 0 : mm_pasid_init(mm);
1281 0 : RCU_INIT_POINTER(mm->exe_file, NULL);
1282 0 : mmu_notifier_subscriptions_init(mm);
1283 0 : init_tlb_flush_pending(mm);
1284 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1285 : mm->pmd_huge_pte = NULL;
1286 : #endif
1287 0 : mm_init_uprobes_state(mm);
1288 0 : hugetlb_count_init(mm);
1289 :
1290 0 : if (current->mm) {
1291 0 : mm->flags = current->mm->flags & MMF_INIT_MASK;
1292 0 : mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1293 : } else {
1294 0 : mm->flags = default_dump_filter;
1295 0 : mm->def_flags = 0;
1296 : }
1297 :
1298 0 : if (mm_alloc_pgd(mm))
1299 : goto fail_nopgd;
1300 :
1301 0 : if (init_new_context(p, mm))
1302 : goto fail_nocontext;
1303 :
1304 : if (mm_alloc_cid(mm))
1305 : goto fail_cid;
1306 :
1307 0 : for (i = 0; i < NR_MM_COUNTERS; i++)
1308 0 : if (percpu_counter_init(&mm->rss_stat[i], 0, GFP_KERNEL_ACCOUNT))
1309 : goto fail_pcpu;
1310 :
1311 0 : mm->user_ns = get_user_ns(user_ns);
1312 0 : lru_gen_init_mm(mm);
1313 : return mm;
1314 :
1315 : fail_pcpu:
1316 : while (i > 0)
1317 : percpu_counter_destroy(&mm->rss_stat[--i]);
1318 : mm_destroy_cid(mm);
1319 : fail_cid:
1320 : destroy_context(mm);
1321 : fail_nocontext:
1322 : mm_free_pgd(mm);
1323 : fail_nopgd:
1324 0 : free_mm(mm);
1325 : return NULL;
1326 : }
1327 :
1328 : /*
1329 : * Allocate and initialize an mm_struct.
1330 : */
1331 0 : struct mm_struct *mm_alloc(void)
1332 : {
1333 : struct mm_struct *mm;
1334 :
1335 0 : mm = allocate_mm();
1336 0 : if (!mm)
1337 : return NULL;
1338 :
1339 0 : memset(mm, 0, sizeof(*mm));
1340 0 : return mm_init(mm, current, current_user_ns());
1341 : }
1342 :
1343 0 : static inline void __mmput(struct mm_struct *mm)
1344 : {
1345 : VM_BUG_ON(atomic_read(&mm->mm_users));
1346 :
1347 0 : uprobe_clear_state(mm);
1348 0 : exit_aio(mm);
1349 0 : ksm_exit(mm);
1350 0 : khugepaged_exit(mm); /* must run before exit_mmap */
1351 0 : exit_mmap(mm);
1352 0 : mm_put_huge_zero_page(mm);
1353 0 : set_mm_exe_file(mm, NULL);
1354 0 : if (!list_empty(&mm->mmlist)) {
1355 0 : spin_lock(&mmlist_lock);
1356 0 : list_del(&mm->mmlist);
1357 : spin_unlock(&mmlist_lock);
1358 : }
1359 0 : if (mm->binfmt)
1360 : module_put(mm->binfmt->module);
1361 0 : lru_gen_del_mm(mm);
1362 0 : mmdrop(mm);
1363 0 : }
1364 :
1365 : /*
1366 : * Decrement the use count and release all resources for an mm.
1367 : */
1368 0 : void mmput(struct mm_struct *mm)
1369 : {
1370 : might_sleep();
1371 :
1372 0 : if (atomic_dec_and_test(&mm->mm_users))
1373 0 : __mmput(mm);
1374 0 : }
1375 : EXPORT_SYMBOL_GPL(mmput);
1376 :
1377 : #ifdef CONFIG_MMU
1378 0 : static void mmput_async_fn(struct work_struct *work)
1379 : {
1380 0 : struct mm_struct *mm = container_of(work, struct mm_struct,
1381 : async_put_work);
1382 :
1383 0 : __mmput(mm);
1384 0 : }
1385 :
1386 0 : void mmput_async(struct mm_struct *mm)
1387 : {
1388 0 : if (atomic_dec_and_test(&mm->mm_users)) {
1389 0 : INIT_WORK(&mm->async_put_work, mmput_async_fn);
1390 0 : schedule_work(&mm->async_put_work);
1391 : }
1392 0 : }
1393 : EXPORT_SYMBOL_GPL(mmput_async);
1394 : #endif
1395 :
1396 : /**
1397 : * set_mm_exe_file - change a reference to the mm's executable file
1398 : *
1399 : * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1400 : *
1401 : * Main users are mmput() and sys_execve(). Callers prevent concurrent
1402 : * invocations: in mmput() nobody alive left, in execve task is single
1403 : * threaded.
1404 : *
1405 : * Can only fail if new_exe_file != NULL.
1406 : */
1407 0 : int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1408 : {
1409 : struct file *old_exe_file;
1410 :
1411 : /*
1412 : * It is safe to dereference the exe_file without RCU as
1413 : * this function is only called if nobody else can access
1414 : * this mm -- see comment above for justification.
1415 : */
1416 0 : old_exe_file = rcu_dereference_raw(mm->exe_file);
1417 :
1418 0 : if (new_exe_file) {
1419 : /*
1420 : * We expect the caller (i.e., sys_execve) to already denied
1421 : * write access, so this is unlikely to fail.
1422 : */
1423 0 : if (unlikely(deny_write_access(new_exe_file)))
1424 : return -EACCES;
1425 : get_file(new_exe_file);
1426 : }
1427 0 : rcu_assign_pointer(mm->exe_file, new_exe_file);
1428 0 : if (old_exe_file) {
1429 0 : allow_write_access(old_exe_file);
1430 0 : fput(old_exe_file);
1431 : }
1432 : return 0;
1433 : }
1434 :
1435 : /**
1436 : * replace_mm_exe_file - replace a reference to the mm's executable file
1437 : *
1438 : * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1439 : * dealing with concurrent invocation and without grabbing the mmap lock in
1440 : * write mode.
1441 : *
1442 : * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1443 : */
1444 0 : int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1445 : {
1446 : struct vm_area_struct *vma;
1447 : struct file *old_exe_file;
1448 0 : int ret = 0;
1449 :
1450 : /* Forbid mm->exe_file change if old file still mapped. */
1451 0 : old_exe_file = get_mm_exe_file(mm);
1452 0 : if (old_exe_file) {
1453 0 : VMA_ITERATOR(vmi, mm, 0);
1454 : mmap_read_lock(mm);
1455 0 : for_each_vma(vmi, vma) {
1456 0 : if (!vma->vm_file)
1457 0 : continue;
1458 0 : if (path_equal(&vma->vm_file->f_path,
1459 0 : &old_exe_file->f_path)) {
1460 : ret = -EBUSY;
1461 : break;
1462 : }
1463 : }
1464 0 : mmap_read_unlock(mm);
1465 0 : fput(old_exe_file);
1466 0 : if (ret)
1467 0 : return ret;
1468 : }
1469 :
1470 : /* set the new file, lockless */
1471 0 : ret = deny_write_access(new_exe_file);
1472 0 : if (ret)
1473 : return -EACCES;
1474 0 : get_file(new_exe_file);
1475 :
1476 0 : old_exe_file = xchg(&mm->exe_file, new_exe_file);
1477 0 : if (old_exe_file) {
1478 : /*
1479 : * Don't race with dup_mmap() getting the file and disallowing
1480 : * write access while someone might open the file writable.
1481 : */
1482 0 : mmap_read_lock(mm);
1483 0 : allow_write_access(old_exe_file);
1484 0 : fput(old_exe_file);
1485 : mmap_read_unlock(mm);
1486 : }
1487 : return 0;
1488 : }
1489 :
1490 : /**
1491 : * get_mm_exe_file - acquire a reference to the mm's executable file
1492 : *
1493 : * Returns %NULL if mm has no associated executable file.
1494 : * User must release file via fput().
1495 : */
1496 0 : struct file *get_mm_exe_file(struct mm_struct *mm)
1497 : {
1498 : struct file *exe_file;
1499 :
1500 : rcu_read_lock();
1501 0 : exe_file = rcu_dereference(mm->exe_file);
1502 0 : if (exe_file && !get_file_rcu(exe_file))
1503 0 : exe_file = NULL;
1504 : rcu_read_unlock();
1505 0 : return exe_file;
1506 : }
1507 :
1508 : /**
1509 : * get_task_exe_file - acquire a reference to the task's executable file
1510 : *
1511 : * Returns %NULL if task's mm (if any) has no associated executable file or
1512 : * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1513 : * User must release file via fput().
1514 : */
1515 0 : struct file *get_task_exe_file(struct task_struct *task)
1516 : {
1517 0 : struct file *exe_file = NULL;
1518 : struct mm_struct *mm;
1519 :
1520 0 : task_lock(task);
1521 0 : mm = task->mm;
1522 0 : if (mm) {
1523 0 : if (!(task->flags & PF_KTHREAD))
1524 0 : exe_file = get_mm_exe_file(mm);
1525 : }
1526 0 : task_unlock(task);
1527 0 : return exe_file;
1528 : }
1529 :
1530 : /**
1531 : * get_task_mm - acquire a reference to the task's mm
1532 : *
1533 : * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1534 : * this kernel workthread has transiently adopted a user mm with use_mm,
1535 : * to do its AIO) is not set and if so returns a reference to it, after
1536 : * bumping up the use count. User must release the mm via mmput()
1537 : * after use. Typically used by /proc and ptrace.
1538 : */
1539 0 : struct mm_struct *get_task_mm(struct task_struct *task)
1540 : {
1541 : struct mm_struct *mm;
1542 :
1543 0 : task_lock(task);
1544 0 : mm = task->mm;
1545 0 : if (mm) {
1546 0 : if (task->flags & PF_KTHREAD)
1547 : mm = NULL;
1548 : else
1549 : mmget(mm);
1550 : }
1551 0 : task_unlock(task);
1552 0 : return mm;
1553 : }
1554 : EXPORT_SYMBOL_GPL(get_task_mm);
1555 :
1556 0 : struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1557 : {
1558 : struct mm_struct *mm;
1559 : int err;
1560 :
1561 0 : err = down_read_killable(&task->signal->exec_update_lock);
1562 0 : if (err)
1563 0 : return ERR_PTR(err);
1564 :
1565 0 : mm = get_task_mm(task);
1566 0 : if (mm && mm != current->mm &&
1567 0 : !ptrace_may_access(task, mode)) {
1568 : mmput(mm);
1569 : mm = ERR_PTR(-EACCES);
1570 : }
1571 0 : up_read(&task->signal->exec_update_lock);
1572 :
1573 0 : return mm;
1574 : }
1575 :
1576 : static void complete_vfork_done(struct task_struct *tsk)
1577 : {
1578 : struct completion *vfork;
1579 :
1580 367 : task_lock(tsk);
1581 367 : vfork = tsk->vfork_done;
1582 367 : if (likely(vfork)) {
1583 367 : tsk->vfork_done = NULL;
1584 367 : complete(vfork);
1585 : }
1586 367 : task_unlock(tsk);
1587 : }
1588 :
1589 0 : static int wait_for_vfork_done(struct task_struct *child,
1590 : struct completion *vfork)
1591 : {
1592 0 : unsigned int state = TASK_UNINTERRUPTIBLE|TASK_KILLABLE|TASK_FREEZABLE;
1593 : int killed;
1594 :
1595 : cgroup_enter_frozen();
1596 0 : killed = wait_for_completion_state(vfork, state);
1597 0 : cgroup_leave_frozen(false);
1598 :
1599 0 : if (killed) {
1600 0 : task_lock(child);
1601 0 : child->vfork_done = NULL;
1602 0 : task_unlock(child);
1603 : }
1604 :
1605 0 : put_task_struct(child);
1606 0 : return killed;
1607 : }
1608 :
1609 : /* Please note the differences between mmput and mm_release.
1610 : * mmput is called whenever we stop holding onto a mm_struct,
1611 : * error success whatever.
1612 : *
1613 : * mm_release is called after a mm_struct has been removed
1614 : * from the current process.
1615 : *
1616 : * This difference is important for error handling, when we
1617 : * only half set up a mm_struct for a new process and need to restore
1618 : * the old one. Because we mmput the new mm_struct before
1619 : * restoring the old one. . .
1620 : * Eric Biederman 10 January 1998
1621 : */
1622 367 : static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1623 : {
1624 367 : uprobe_free_utask(tsk);
1625 :
1626 : /* Get rid of any cached register state */
1627 367 : deactivate_mm(tsk, mm);
1628 :
1629 : /*
1630 : * Signal userspace if we're not exiting with a core dump
1631 : * because we want to leave the value intact for debugging
1632 : * purposes.
1633 : */
1634 367 : if (tsk->clear_child_tid) {
1635 0 : if (atomic_read(&mm->mm_users) > 1) {
1636 : /*
1637 : * We don't check the error code - if userspace has
1638 : * not set up a proper pointer then tough luck.
1639 : */
1640 0 : put_user(0, tsk->clear_child_tid);
1641 0 : do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1642 : 1, NULL, NULL, 0, 0);
1643 : }
1644 0 : tsk->clear_child_tid = NULL;
1645 : }
1646 :
1647 : /*
1648 : * All done, finally we can wake up parent and return this mm to him.
1649 : * Also kthread_stop() uses this completion for synchronization.
1650 : */
1651 367 : if (tsk->vfork_done)
1652 367 : complete_vfork_done(tsk);
1653 367 : }
1654 :
1655 367 : void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1656 : {
1657 367 : futex_exit_release(tsk);
1658 367 : mm_release(tsk, mm);
1659 367 : }
1660 :
1661 0 : void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1662 : {
1663 0 : futex_exec_release(tsk);
1664 0 : mm_release(tsk, mm);
1665 0 : }
1666 :
1667 : /**
1668 : * dup_mm() - duplicates an existing mm structure
1669 : * @tsk: the task_struct with which the new mm will be associated.
1670 : * @oldmm: the mm to duplicate.
1671 : *
1672 : * Allocates a new mm structure and duplicates the provided @oldmm structure
1673 : * content into it.
1674 : *
1675 : * Return: the duplicated mm or NULL on failure.
1676 : */
1677 0 : static struct mm_struct *dup_mm(struct task_struct *tsk,
1678 : struct mm_struct *oldmm)
1679 : {
1680 : struct mm_struct *mm;
1681 : int err;
1682 :
1683 0 : mm = allocate_mm();
1684 0 : if (!mm)
1685 : goto fail_nomem;
1686 :
1687 0 : memcpy(mm, oldmm, sizeof(*mm));
1688 :
1689 0 : if (!mm_init(mm, tsk, mm->user_ns))
1690 : goto fail_nomem;
1691 :
1692 0 : err = dup_mmap(mm, oldmm);
1693 0 : if (err)
1694 : goto free_pt;
1695 :
1696 0 : mm->hiwater_rss = get_mm_rss(mm);
1697 0 : mm->hiwater_vm = mm->total_vm;
1698 :
1699 0 : if (mm->binfmt && !try_module_get(mm->binfmt->module))
1700 : goto free_pt;
1701 :
1702 : return mm;
1703 :
1704 : free_pt:
1705 : /* don't put binfmt in mmput, we haven't got module yet */
1706 0 : mm->binfmt = NULL;
1707 0 : mm_init_owner(mm, NULL);
1708 : mmput(mm);
1709 :
1710 : fail_nomem:
1711 : return NULL;
1712 : }
1713 :
1714 382 : static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1715 : {
1716 : struct mm_struct *mm, *oldmm;
1717 :
1718 382 : tsk->min_flt = tsk->maj_flt = 0;
1719 382 : tsk->nvcsw = tsk->nivcsw = 0;
1720 : #ifdef CONFIG_DETECT_HUNG_TASK
1721 : tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1722 : tsk->last_switch_time = 0;
1723 : #endif
1724 :
1725 382 : tsk->mm = NULL;
1726 382 : tsk->active_mm = NULL;
1727 :
1728 : /*
1729 : * Are we cloning a kernel thread?
1730 : *
1731 : * We need to steal a active VM for that..
1732 : */
1733 382 : oldmm = current->mm;
1734 382 : if (!oldmm)
1735 : return 0;
1736 :
1737 0 : if (clone_flags & CLONE_VM) {
1738 0 : mmget(oldmm);
1739 0 : mm = oldmm;
1740 : } else {
1741 0 : mm = dup_mm(tsk, current->mm);
1742 0 : if (!mm)
1743 : return -ENOMEM;
1744 : }
1745 :
1746 0 : tsk->mm = mm;
1747 0 : tsk->active_mm = mm;
1748 0 : sched_mm_cid_fork(tsk);
1749 0 : return 0;
1750 : }
1751 :
1752 382 : static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1753 : {
1754 382 : struct fs_struct *fs = current->fs;
1755 382 : if (clone_flags & CLONE_FS) {
1756 : /* tsk->fs is already what we want */
1757 764 : spin_lock(&fs->lock);
1758 382 : if (fs->in_exec) {
1759 0 : spin_unlock(&fs->lock);
1760 : return -EAGAIN;
1761 : }
1762 382 : fs->users++;
1763 764 : spin_unlock(&fs->lock);
1764 : return 0;
1765 : }
1766 0 : tsk->fs = copy_fs_struct(fs);
1767 0 : if (!tsk->fs)
1768 : return -ENOMEM;
1769 : return 0;
1770 : }
1771 :
1772 382 : static int copy_files(unsigned long clone_flags, struct task_struct *tsk,
1773 : int no_files)
1774 : {
1775 : struct files_struct *oldf, *newf;
1776 382 : int error = 0;
1777 :
1778 : /*
1779 : * A background process may not have any files ...
1780 : */
1781 382 : oldf = current->files;
1782 382 : if (!oldf)
1783 : goto out;
1784 :
1785 382 : if (no_files) {
1786 0 : tsk->files = NULL;
1787 : goto out;
1788 : }
1789 :
1790 382 : if (clone_flags & CLONE_FILES) {
1791 381 : atomic_inc(&oldf->count);
1792 : goto out;
1793 : }
1794 :
1795 1 : newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1796 1 : if (!newf)
1797 : goto out;
1798 :
1799 1 : tsk->files = newf;
1800 1 : error = 0;
1801 : out:
1802 382 : return error;
1803 : }
1804 :
1805 382 : static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1806 : {
1807 : struct sighand_struct *sig;
1808 :
1809 382 : if (clone_flags & CLONE_SIGHAND) {
1810 0 : refcount_inc(¤t->sighand->count);
1811 0 : return 0;
1812 : }
1813 382 : sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1814 382 : RCU_INIT_POINTER(tsk->sighand, sig);
1815 382 : if (!sig)
1816 : return -ENOMEM;
1817 :
1818 764 : refcount_set(&sig->count, 1);
1819 764 : spin_lock_irq(¤t->sighand->siglock);
1820 382 : memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1821 764 : spin_unlock_irq(¤t->sighand->siglock);
1822 :
1823 : /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1824 382 : if (clone_flags & CLONE_CLEAR_SIGHAND)
1825 0 : flush_signal_handlers(tsk, 0);
1826 :
1827 : return 0;
1828 : }
1829 :
1830 367 : void __cleanup_sighand(struct sighand_struct *sighand)
1831 : {
1832 734 : if (refcount_dec_and_test(&sighand->count)) {
1833 367 : signalfd_cleanup(sighand);
1834 : /*
1835 : * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1836 : * without an RCU grace period, see __lock_task_sighand().
1837 : */
1838 367 : kmem_cache_free(sighand_cachep, sighand);
1839 : }
1840 367 : }
1841 :
1842 : /*
1843 : * Initialize POSIX timer handling for a thread group.
1844 : */
1845 : static void posix_cpu_timers_init_group(struct signal_struct *sig)
1846 : {
1847 382 : struct posix_cputimers *pct = &sig->posix_cputimers;
1848 : unsigned long cpu_limit;
1849 :
1850 382 : cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1851 382 : posix_cputimers_group_init(pct, cpu_limit);
1852 : }
1853 :
1854 382 : static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1855 : {
1856 : struct signal_struct *sig;
1857 :
1858 382 : if (clone_flags & CLONE_THREAD)
1859 : return 0;
1860 :
1861 764 : sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1862 382 : tsk->signal = sig;
1863 382 : if (!sig)
1864 : return -ENOMEM;
1865 :
1866 382 : sig->nr_threads = 1;
1867 382 : sig->quick_threads = 1;
1868 764 : atomic_set(&sig->live, 1);
1869 764 : refcount_set(&sig->sigcnt, 1);
1870 :
1871 : /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1872 382 : sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1873 382 : tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1874 :
1875 382 : init_waitqueue_head(&sig->wait_chldexit);
1876 382 : sig->curr_target = tsk;
1877 764 : init_sigpending(&sig->shared_pending);
1878 382 : INIT_HLIST_HEAD(&sig->multiprocess);
1879 764 : seqlock_init(&sig->stats_lock);
1880 764 : prev_cputime_init(&sig->prev_cputime);
1881 :
1882 : #ifdef CONFIG_POSIX_TIMERS
1883 764 : INIT_LIST_HEAD(&sig->posix_timers);
1884 382 : hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1885 382 : sig->real_timer.function = it_real_fn;
1886 : #endif
1887 :
1888 382 : task_lock(current->group_leader);
1889 382 : memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1890 764 : task_unlock(current->group_leader);
1891 :
1892 382 : posix_cpu_timers_init_group(sig);
1893 :
1894 : tty_audit_fork(sig);
1895 : sched_autogroup_fork(sig);
1896 :
1897 382 : sig->oom_score_adj = current->signal->oom_score_adj;
1898 382 : sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1899 :
1900 382 : mutex_init(&sig->cred_guard_mutex);
1901 382 : init_rwsem(&sig->exec_update_lock);
1902 :
1903 382 : return 0;
1904 : }
1905 :
1906 382 : static void copy_seccomp(struct task_struct *p)
1907 : {
1908 : #ifdef CONFIG_SECCOMP
1909 : /*
1910 : * Must be called with sighand->lock held, which is common to
1911 : * all threads in the group. Holding cred_guard_mutex is not
1912 : * needed because this new task is not yet running and cannot
1913 : * be racing exec.
1914 : */
1915 382 : assert_spin_locked(¤t->sighand->siglock);
1916 :
1917 : /* Ref-count the new filter user, and assign it. */
1918 382 : get_seccomp_filter(current);
1919 382 : p->seccomp = current->seccomp;
1920 :
1921 : /*
1922 : * Explicitly enable no_new_privs here in case it got set
1923 : * between the task_struct being duplicated and holding the
1924 : * sighand lock. The seccomp state and nnp must be in sync.
1925 : */
1926 764 : if (task_no_new_privs(current))
1927 : task_set_no_new_privs(p);
1928 :
1929 : /*
1930 : * If the parent gained a seccomp mode after copying thread
1931 : * flags and between before we held the sighand lock, we have
1932 : * to manually enable the seccomp thread flag here.
1933 : */
1934 382 : if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1935 0 : set_task_syscall_work(p, SECCOMP);
1936 : #endif
1937 382 : }
1938 :
1939 0 : SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1940 : {
1941 0 : current->clear_child_tid = tidptr;
1942 :
1943 0 : return task_pid_vnr(current);
1944 : }
1945 :
1946 : static void rt_mutex_init_task(struct task_struct *p)
1947 : {
1948 : raw_spin_lock_init(&p->pi_lock);
1949 : #ifdef CONFIG_RT_MUTEXES
1950 382 : p->pi_waiters = RB_ROOT_CACHED;
1951 382 : p->pi_top_task = NULL;
1952 382 : p->pi_blocked_on = NULL;
1953 : #endif
1954 : }
1955 :
1956 : static inline void init_task_pid_links(struct task_struct *task)
1957 : {
1958 : enum pid_type type;
1959 :
1960 1910 : for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1961 3056 : INIT_HLIST_NODE(&task->pid_links[type]);
1962 : }
1963 :
1964 : static inline void
1965 : init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1966 : {
1967 0 : if (type == PIDTYPE_PID)
1968 382 : task->thread_pid = pid;
1969 : else
1970 1146 : task->signal->pids[type] = pid;
1971 : }
1972 :
1973 : static inline void rcu_copy_process(struct task_struct *p)
1974 : {
1975 : #ifdef CONFIG_PREEMPT_RCU
1976 : p->rcu_read_lock_nesting = 0;
1977 : p->rcu_read_unlock_special.s = 0;
1978 : p->rcu_blocked_node = NULL;
1979 : INIT_LIST_HEAD(&p->rcu_node_entry);
1980 : #endif /* #ifdef CONFIG_PREEMPT_RCU */
1981 : #ifdef CONFIG_TASKS_RCU
1982 : p->rcu_tasks_holdout = false;
1983 : INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1984 : p->rcu_tasks_idle_cpu = -1;
1985 : #endif /* #ifdef CONFIG_TASKS_RCU */
1986 : #ifdef CONFIG_TASKS_TRACE_RCU
1987 : p->trc_reader_nesting = 0;
1988 : p->trc_reader_special.s = 0;
1989 : INIT_LIST_HEAD(&p->trc_holdout_list);
1990 : INIT_LIST_HEAD(&p->trc_blkd_node);
1991 : #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1992 : }
1993 :
1994 0 : struct pid *pidfd_pid(const struct file *file)
1995 : {
1996 0 : if (file->f_op == &pidfd_fops)
1997 0 : return file->private_data;
1998 :
1999 : return ERR_PTR(-EBADF);
2000 : }
2001 :
2002 0 : static int pidfd_release(struct inode *inode, struct file *file)
2003 : {
2004 0 : struct pid *pid = file->private_data;
2005 :
2006 0 : file->private_data = NULL;
2007 0 : put_pid(pid);
2008 0 : return 0;
2009 : }
2010 :
2011 : #ifdef CONFIG_PROC_FS
2012 : /**
2013 : * pidfd_show_fdinfo - print information about a pidfd
2014 : * @m: proc fdinfo file
2015 : * @f: file referencing a pidfd
2016 : *
2017 : * Pid:
2018 : * This function will print the pid that a given pidfd refers to in the
2019 : * pid namespace of the procfs instance.
2020 : * If the pid namespace of the process is not a descendant of the pid
2021 : * namespace of the procfs instance 0 will be shown as its pid. This is
2022 : * similar to calling getppid() on a process whose parent is outside of
2023 : * its pid namespace.
2024 : *
2025 : * NSpid:
2026 : * If pid namespaces are supported then this function will also print
2027 : * the pid of a given pidfd refers to for all descendant pid namespaces
2028 : * starting from the current pid namespace of the instance, i.e. the
2029 : * Pid field and the first entry in the NSpid field will be identical.
2030 : * If the pid namespace of the process is not a descendant of the pid
2031 : * namespace of the procfs instance 0 will be shown as its first NSpid
2032 : * entry and no others will be shown.
2033 : * Note that this differs from the Pid and NSpid fields in
2034 : * /proc/<pid>/status where Pid and NSpid are always shown relative to
2035 : * the pid namespace of the procfs instance. The difference becomes
2036 : * obvious when sending around a pidfd between pid namespaces from a
2037 : * different branch of the tree, i.e. where no ancestral relation is
2038 : * present between the pid namespaces:
2039 : * - create two new pid namespaces ns1 and ns2 in the initial pid
2040 : * namespace (also take care to create new mount namespaces in the
2041 : * new pid namespace and mount procfs)
2042 : * - create a process with a pidfd in ns1
2043 : * - send pidfd from ns1 to ns2
2044 : * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
2045 : * have exactly one entry, which is 0
2046 : */
2047 0 : static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
2048 : {
2049 0 : struct pid *pid = f->private_data;
2050 : struct pid_namespace *ns;
2051 0 : pid_t nr = -1;
2052 :
2053 0 : if (likely(pid_has_task(pid, PIDTYPE_PID))) {
2054 0 : ns = proc_pid_ns(file_inode(m->file)->i_sb);
2055 0 : nr = pid_nr_ns(pid, ns);
2056 : }
2057 :
2058 0 : seq_put_decimal_ll(m, "Pid:\t", nr);
2059 :
2060 : #ifdef CONFIG_PID_NS
2061 0 : seq_put_decimal_ll(m, "\nNSpid:\t", nr);
2062 0 : if (nr > 0) {
2063 : int i;
2064 :
2065 : /* If nr is non-zero it means that 'pid' is valid and that
2066 : * ns, i.e. the pid namespace associated with the procfs
2067 : * instance, is in the pid namespace hierarchy of pid.
2068 : * Start at one below the already printed level.
2069 : */
2070 0 : for (i = ns->level + 1; i <= pid->level; i++)
2071 0 : seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
2072 : }
2073 : #endif
2074 0 : seq_putc(m, '\n');
2075 0 : }
2076 : #endif
2077 :
2078 : /*
2079 : * Poll support for process exit notification.
2080 : */
2081 0 : static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
2082 : {
2083 0 : struct pid *pid = file->private_data;
2084 0 : __poll_t poll_flags = 0;
2085 :
2086 0 : poll_wait(file, &pid->wait_pidfd, pts);
2087 :
2088 : /*
2089 : * Inform pollers only when the whole thread group exits.
2090 : * If the thread group leader exits before all other threads in the
2091 : * group, then poll(2) should block, similar to the wait(2) family.
2092 : */
2093 0 : if (thread_group_exited(pid))
2094 0 : poll_flags = EPOLLIN | EPOLLRDNORM;
2095 :
2096 0 : return poll_flags;
2097 : }
2098 :
2099 : const struct file_operations pidfd_fops = {
2100 : .release = pidfd_release,
2101 : .poll = pidfd_poll,
2102 : #ifdef CONFIG_PROC_FS
2103 : .show_fdinfo = pidfd_show_fdinfo,
2104 : #endif
2105 : };
2106 :
2107 : /**
2108 : * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2109 : * @pid: the struct pid for which to create a pidfd
2110 : * @flags: flags of the new @pidfd
2111 : * @pidfd: the pidfd to return
2112 : *
2113 : * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2114 : * caller's file descriptor table. The pidfd is reserved but not installed yet.
2115 :
2116 : * The helper doesn't perform checks on @pid which makes it useful for pidfds
2117 : * created via CLONE_PIDFD where @pid has no task attached when the pidfd and
2118 : * pidfd file are prepared.
2119 : *
2120 : * If this function returns successfully the caller is responsible to either
2121 : * call fd_install() passing the returned pidfd and pidfd file as arguments in
2122 : * order to install the pidfd into its file descriptor table or they must use
2123 : * put_unused_fd() and fput() on the returned pidfd and pidfd file
2124 : * respectively.
2125 : *
2126 : * This function is useful when a pidfd must already be reserved but there
2127 : * might still be points of failure afterwards and the caller wants to ensure
2128 : * that no pidfd is leaked into its file descriptor table.
2129 : *
2130 : * Return: On success, a reserved pidfd is returned from the function and a new
2131 : * pidfd file is returned in the last argument to the function. On
2132 : * error, a negative error code is returned from the function and the
2133 : * last argument remains unchanged.
2134 : */
2135 0 : static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
2136 : {
2137 : int pidfd;
2138 : struct file *pidfd_file;
2139 :
2140 0 : if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC))
2141 : return -EINVAL;
2142 :
2143 0 : pidfd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2144 0 : if (pidfd < 0)
2145 : return pidfd;
2146 :
2147 0 : pidfd_file = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2148 0 : flags | O_RDWR | O_CLOEXEC);
2149 0 : if (IS_ERR(pidfd_file)) {
2150 0 : put_unused_fd(pidfd);
2151 0 : return PTR_ERR(pidfd_file);
2152 : }
2153 0 : get_pid(pid); /* held by pidfd_file now */
2154 0 : *ret = pidfd_file;
2155 0 : return pidfd;
2156 : }
2157 :
2158 : /**
2159 : * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2160 : * @pid: the struct pid for which to create a pidfd
2161 : * @flags: flags of the new @pidfd
2162 : * @pidfd: the pidfd to return
2163 : *
2164 : * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2165 : * caller's file descriptor table. The pidfd is reserved but not installed yet.
2166 : *
2167 : * The helper verifies that @pid is used as a thread group leader.
2168 : *
2169 : * If this function returns successfully the caller is responsible to either
2170 : * call fd_install() passing the returned pidfd and pidfd file as arguments in
2171 : * order to install the pidfd into its file descriptor table or they must use
2172 : * put_unused_fd() and fput() on the returned pidfd and pidfd file
2173 : * respectively.
2174 : *
2175 : * This function is useful when a pidfd must already be reserved but there
2176 : * might still be points of failure afterwards and the caller wants to ensure
2177 : * that no pidfd is leaked into its file descriptor table.
2178 : *
2179 : * Return: On success, a reserved pidfd is returned from the function and a new
2180 : * pidfd file is returned in the last argument to the function. On
2181 : * error, a negative error code is returned from the function and the
2182 : * last argument remains unchanged.
2183 : */
2184 0 : int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
2185 : {
2186 0 : if (!pid || !pid_has_task(pid, PIDTYPE_TGID))
2187 : return -EINVAL;
2188 :
2189 0 : return __pidfd_prepare(pid, flags, ret);
2190 : }
2191 :
2192 : static void __delayed_free_task(struct rcu_head *rhp)
2193 : {
2194 : struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
2195 :
2196 : free_task(tsk);
2197 : }
2198 :
2199 : static __always_inline void delayed_free_task(struct task_struct *tsk)
2200 : {
2201 : if (IS_ENABLED(CONFIG_MEMCG))
2202 : call_rcu(&tsk->rcu, __delayed_free_task);
2203 : else
2204 0 : free_task(tsk);
2205 : }
2206 :
2207 382 : static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
2208 : {
2209 : /* Skip if kernel thread */
2210 382 : if (!tsk->mm)
2211 : return;
2212 :
2213 : /* Skip if spawning a thread or using vfork */
2214 0 : if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
2215 : return;
2216 :
2217 : /* We need to synchronize with __set_oom_adj */
2218 0 : mutex_lock(&oom_adj_mutex);
2219 0 : set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
2220 : /* Update the values in case they were changed after copy_signal */
2221 0 : tsk->signal->oom_score_adj = current->signal->oom_score_adj;
2222 0 : tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
2223 0 : mutex_unlock(&oom_adj_mutex);
2224 : }
2225 :
2226 : #ifdef CONFIG_RV
2227 : static void rv_task_fork(struct task_struct *p)
2228 : {
2229 : int i;
2230 :
2231 : for (i = 0; i < RV_PER_TASK_MONITORS; i++)
2232 : p->rv[i].da_mon.monitoring = false;
2233 : }
2234 : #else
2235 : #define rv_task_fork(p) do {} while (0)
2236 : #endif
2237 :
2238 : /*
2239 : * This creates a new process as a copy of the old one,
2240 : * but does not actually start it yet.
2241 : *
2242 : * It copies the registers, and all the appropriate
2243 : * parts of the process environment (as per the clone
2244 : * flags). The actual kick-off is left to the caller.
2245 : */
2246 382 : __latent_entropy struct task_struct *copy_process(
2247 : struct pid *pid,
2248 : int trace,
2249 : int node,
2250 : struct kernel_clone_args *args)
2251 : {
2252 382 : int pidfd = -1, retval;
2253 : struct task_struct *p;
2254 : struct multiprocess_signals delayed;
2255 382 : struct file *pidfile = NULL;
2256 382 : const u64 clone_flags = args->flags;
2257 382 : struct nsproxy *nsp = current->nsproxy;
2258 :
2259 : /*
2260 : * Don't allow sharing the root directory with processes in a different
2261 : * namespace
2262 : */
2263 382 : if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
2264 : return ERR_PTR(-EINVAL);
2265 :
2266 382 : if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
2267 : return ERR_PTR(-EINVAL);
2268 :
2269 : /*
2270 : * Thread groups must share signals as well, and detached threads
2271 : * can only be started up within the thread group.
2272 : */
2273 382 : if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2274 : return ERR_PTR(-EINVAL);
2275 :
2276 : /*
2277 : * Shared signal handlers imply shared VM. By way of the above,
2278 : * thread groups also imply shared VM. Blocking this case allows
2279 : * for various simplifications in other code.
2280 : */
2281 382 : if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2282 : return ERR_PTR(-EINVAL);
2283 :
2284 : /*
2285 : * Siblings of global init remain as zombies on exit since they are
2286 : * not reaped by their parent (swapper). To solve this and to avoid
2287 : * multi-rooted process trees, prevent global and container-inits
2288 : * from creating siblings.
2289 : */
2290 382 : if ((clone_flags & CLONE_PARENT) &&
2291 0 : current->signal->flags & SIGNAL_UNKILLABLE)
2292 : return ERR_PTR(-EINVAL);
2293 :
2294 : /*
2295 : * If the new process will be in a different pid or user namespace
2296 : * do not allow it to share a thread group with the forking task.
2297 : */
2298 382 : if (clone_flags & CLONE_THREAD) {
2299 0 : if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2300 0 : (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2301 : return ERR_PTR(-EINVAL);
2302 : }
2303 :
2304 382 : if (clone_flags & CLONE_PIDFD) {
2305 : /*
2306 : * - CLONE_DETACHED is blocked so that we can potentially
2307 : * reuse it later for CLONE_PIDFD.
2308 : * - CLONE_THREAD is blocked until someone really needs it.
2309 : */
2310 0 : if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
2311 : return ERR_PTR(-EINVAL);
2312 : }
2313 :
2314 : /*
2315 : * Force any signals received before this point to be delivered
2316 : * before the fork happens. Collect up signals sent to multiple
2317 : * processes that happen during the fork and delay them so that
2318 : * they appear to happen after the fork.
2319 : */
2320 382 : sigemptyset(&delayed.signal);
2321 382 : INIT_HLIST_NODE(&delayed.node);
2322 :
2323 764 : spin_lock_irq(¤t->sighand->siglock);
2324 382 : if (!(clone_flags & CLONE_THREAD))
2325 382 : hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2326 382 : recalc_sigpending();
2327 764 : spin_unlock_irq(¤t->sighand->siglock);
2328 382 : retval = -ERESTARTNOINTR;
2329 764 : if (task_sigpending(current))
2330 : goto fork_out;
2331 :
2332 382 : retval = -ENOMEM;
2333 382 : p = dup_task_struct(current, node);
2334 382 : if (!p)
2335 : goto fork_out;
2336 382 : p->flags &= ~PF_KTHREAD;
2337 382 : if (args->kthread)
2338 381 : p->flags |= PF_KTHREAD;
2339 382 : if (args->user_worker) {
2340 : /*
2341 : * Mark us a user worker, and block any signal that isn't
2342 : * fatal or STOP
2343 : */
2344 0 : p->flags |= PF_USER_WORKER;
2345 0 : siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2346 : }
2347 382 : if (args->io_thread)
2348 0 : p->flags |= PF_IO_WORKER;
2349 :
2350 382 : if (args->name)
2351 380 : strscpy_pad(p->comm, args->name, sizeof(p->comm));
2352 :
2353 382 : p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2354 : /*
2355 : * Clear TID on mm_release()?
2356 : */
2357 382 : p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2358 :
2359 382 : ftrace_graph_init_task(p);
2360 :
2361 382 : rt_mutex_init_task(p);
2362 :
2363 : lockdep_assert_irqs_enabled();
2364 : #ifdef CONFIG_PROVE_LOCKING
2365 : DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2366 : #endif
2367 382 : retval = copy_creds(p, clone_flags);
2368 382 : if (retval < 0)
2369 : goto bad_fork_free;
2370 :
2371 382 : retval = -EAGAIN;
2372 1146 : if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2373 0 : if (p->real_cred->user != INIT_USER &&
2374 0 : !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2375 : goto bad_fork_cleanup_count;
2376 : }
2377 382 : current->flags &= ~PF_NPROC_EXCEEDED;
2378 :
2379 : /*
2380 : * If multiple threads are within copy_process(), then this check
2381 : * triggers too late. This doesn't hurt, the check is only there
2382 : * to stop root fork bombs.
2383 : */
2384 382 : retval = -EAGAIN;
2385 382 : if (data_race(nr_threads >= max_threads))
2386 : goto bad_fork_cleanup_count;
2387 :
2388 382 : delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2389 382 : p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2390 382 : p->flags |= PF_FORKNOEXEC;
2391 764 : INIT_LIST_HEAD(&p->children);
2392 764 : INIT_LIST_HEAD(&p->sibling);
2393 382 : rcu_copy_process(p);
2394 382 : p->vfork_done = NULL;
2395 382 : spin_lock_init(&p->alloc_lock);
2396 :
2397 764 : init_sigpending(&p->pending);
2398 :
2399 382 : p->utime = p->stime = p->gtime = 0;
2400 : #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2401 : p->utimescaled = p->stimescaled = 0;
2402 : #endif
2403 764 : prev_cputime_init(&p->prev_cputime);
2404 :
2405 : #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2406 : seqcount_init(&p->vtime.seqcount);
2407 : p->vtime.starttime = 0;
2408 : p->vtime.state = VTIME_INACTIVE;
2409 : #endif
2410 :
2411 : #ifdef CONFIG_IO_URING
2412 382 : p->io_uring = NULL;
2413 : #endif
2414 :
2415 : #if defined(SPLIT_RSS_COUNTING)
2416 : memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2417 : #endif
2418 :
2419 382 : p->default_timer_slack_ns = current->timer_slack_ns;
2420 :
2421 : #ifdef CONFIG_PSI
2422 : p->psi_flags = 0;
2423 : #endif
2424 :
2425 382 : task_io_accounting_init(&p->ioac);
2426 382 : acct_clear_integrals(p);
2427 :
2428 764 : posix_cputimers_init(&p->posix_cputimers);
2429 :
2430 382 : p->io_context = NULL;
2431 382 : audit_set_context(p, NULL);
2432 382 : cgroup_fork(p);
2433 382 : if (args->kthread) {
2434 381 : if (!set_kthread_struct(p))
2435 : goto bad_fork_cleanup_delayacct;
2436 : }
2437 : #ifdef CONFIG_NUMA
2438 : p->mempolicy = mpol_dup(p->mempolicy);
2439 : if (IS_ERR(p->mempolicy)) {
2440 : retval = PTR_ERR(p->mempolicy);
2441 : p->mempolicy = NULL;
2442 : goto bad_fork_cleanup_delayacct;
2443 : }
2444 : #endif
2445 : #ifdef CONFIG_CPUSETS
2446 : p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2447 : p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2448 : seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2449 : #endif
2450 : #ifdef CONFIG_TRACE_IRQFLAGS
2451 : memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2452 : p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2453 : p->irqtrace.softirq_enable_ip = _THIS_IP_;
2454 : p->softirqs_enabled = 1;
2455 : p->softirq_context = 0;
2456 : #endif
2457 :
2458 382 : p->pagefault_disabled = 0;
2459 :
2460 : #ifdef CONFIG_LOCKDEP
2461 : lockdep_init_task(p);
2462 : #endif
2463 :
2464 : #ifdef CONFIG_DEBUG_MUTEXES
2465 : p->blocked_on = NULL; /* not blocked yet */
2466 : #endif
2467 : #ifdef CONFIG_BCACHE
2468 : p->sequential_io = 0;
2469 : p->sequential_io_avg = 0;
2470 : #endif
2471 : #ifdef CONFIG_BPF_SYSCALL
2472 : RCU_INIT_POINTER(p->bpf_storage, NULL);
2473 : p->bpf_ctx = NULL;
2474 : #endif
2475 :
2476 : /* Perform scheduler related setup. Assign this task to a CPU. */
2477 382 : retval = sched_fork(clone_flags, p);
2478 382 : if (retval)
2479 : goto bad_fork_cleanup_policy;
2480 :
2481 382 : retval = perf_event_init_task(p, clone_flags);
2482 : if (retval)
2483 : goto bad_fork_cleanup_policy;
2484 382 : retval = audit_alloc(p);
2485 : if (retval)
2486 : goto bad_fork_cleanup_perf;
2487 : /* copy all the process information */
2488 382 : shm_init_task(p);
2489 382 : retval = security_task_alloc(p, clone_flags);
2490 : if (retval)
2491 : goto bad_fork_cleanup_audit;
2492 382 : retval = copy_semundo(clone_flags, p);
2493 : if (retval)
2494 : goto bad_fork_cleanup_security;
2495 382 : retval = copy_files(clone_flags, p, args->no_files);
2496 382 : if (retval)
2497 : goto bad_fork_cleanup_semundo;
2498 382 : retval = copy_fs(clone_flags, p);
2499 382 : if (retval)
2500 : goto bad_fork_cleanup_files;
2501 382 : retval = copy_sighand(clone_flags, p);
2502 382 : if (retval)
2503 : goto bad_fork_cleanup_fs;
2504 382 : retval = copy_signal(clone_flags, p);
2505 382 : if (retval)
2506 : goto bad_fork_cleanup_sighand;
2507 382 : retval = copy_mm(clone_flags, p);
2508 382 : if (retval)
2509 : goto bad_fork_cleanup_signal;
2510 382 : retval = copy_namespaces(clone_flags, p);
2511 382 : if (retval)
2512 : goto bad_fork_cleanup_mm;
2513 382 : retval = copy_io(clone_flags, p);
2514 382 : if (retval)
2515 : goto bad_fork_cleanup_namespaces;
2516 382 : retval = copy_thread(p, args);
2517 382 : if (retval)
2518 : goto bad_fork_cleanup_io;
2519 :
2520 382 : stackleak_task_init(p);
2521 :
2522 382 : if (pid != &init_struct_pid) {
2523 382 : pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2524 : args->set_tid_size);
2525 382 : if (IS_ERR(pid)) {
2526 0 : retval = PTR_ERR(pid);
2527 0 : goto bad_fork_cleanup_thread;
2528 : }
2529 : }
2530 :
2531 : /*
2532 : * This has to happen after we've potentially unshared the file
2533 : * descriptor table (so that the pidfd doesn't leak into the child
2534 : * if the fd table isn't shared).
2535 : */
2536 382 : if (clone_flags & CLONE_PIDFD) {
2537 : /* Note that no task has been attached to @pid yet. */
2538 0 : retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile);
2539 0 : if (retval < 0)
2540 : goto bad_fork_free_pid;
2541 0 : pidfd = retval;
2542 :
2543 0 : retval = put_user(pidfd, args->pidfd);
2544 0 : if (retval)
2545 : goto bad_fork_put_pidfd;
2546 : }
2547 :
2548 : #ifdef CONFIG_BLOCK
2549 382 : p->plug = NULL;
2550 : #endif
2551 382 : futex_init_task(p);
2552 :
2553 : /*
2554 : * sigaltstack should be cleared when sharing the same VM
2555 : */
2556 382 : if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2557 : sas_ss_reset(p);
2558 :
2559 : /*
2560 : * Syscall tracing and stepping should be turned off in the
2561 : * child regardless of CLONE_PTRACE.
2562 : */
2563 382 : user_disable_single_step(p);
2564 764 : clear_task_syscall_work(p, SYSCALL_TRACE);
2565 : #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2566 : clear_task_syscall_work(p, SYSCALL_EMU);
2567 : #endif
2568 382 : clear_tsk_latency_tracing(p);
2569 :
2570 : /* ok, now we should be set up.. */
2571 382 : p->pid = pid_nr(pid);
2572 382 : if (clone_flags & CLONE_THREAD) {
2573 0 : p->group_leader = current->group_leader;
2574 0 : p->tgid = current->tgid;
2575 : } else {
2576 382 : p->group_leader = p;
2577 382 : p->tgid = p->pid;
2578 : }
2579 :
2580 382 : p->nr_dirtied = 0;
2581 382 : p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2582 382 : p->dirty_paused_when = 0;
2583 :
2584 382 : p->pdeath_signal = 0;
2585 764 : INIT_LIST_HEAD(&p->thread_group);
2586 382 : p->task_works = NULL;
2587 382 : clear_posix_cputimers_work(p);
2588 :
2589 : #ifdef CONFIG_KRETPROBES
2590 : p->kretprobe_instances.first = NULL;
2591 : #endif
2592 : #ifdef CONFIG_RETHOOK
2593 : p->rethooks.first = NULL;
2594 : #endif
2595 :
2596 : /*
2597 : * Ensure that the cgroup subsystem policies allow the new process to be
2598 : * forked. It should be noted that the new process's css_set can be changed
2599 : * between here and cgroup_post_fork() if an organisation operation is in
2600 : * progress.
2601 : */
2602 382 : retval = cgroup_can_fork(p, args);
2603 : if (retval)
2604 : goto bad_fork_put_pidfd;
2605 :
2606 : /*
2607 : * Now that the cgroups are pinned, re-clone the parent cgroup and put
2608 : * the new task on the correct runqueue. All this *before* the task
2609 : * becomes visible.
2610 : *
2611 : * This isn't part of ->can_fork() because while the re-cloning is
2612 : * cgroup specific, it unconditionally needs to place the task on a
2613 : * runqueue.
2614 : */
2615 382 : sched_cgroup_fork(p, args);
2616 :
2617 : /*
2618 : * From this point on we must avoid any synchronous user-space
2619 : * communication until we take the tasklist-lock. In particular, we do
2620 : * not want user-space to be able to predict the process start-time by
2621 : * stalling fork(2) after we recorded the start_time but before it is
2622 : * visible to the system.
2623 : */
2624 :
2625 382 : p->start_time = ktime_get_ns();
2626 382 : p->start_boottime = ktime_get_boottime_ns();
2627 :
2628 : /*
2629 : * Make it visible to the rest of the system, but dont wake it up yet.
2630 : * Need tasklist lock for parent etc handling!
2631 : */
2632 382 : write_lock_irq(&tasklist_lock);
2633 :
2634 : /* CLONE_PARENT re-uses the old parent */
2635 382 : if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2636 0 : p->real_parent = current->real_parent;
2637 0 : p->parent_exec_id = current->parent_exec_id;
2638 0 : if (clone_flags & CLONE_THREAD)
2639 0 : p->exit_signal = -1;
2640 : else
2641 0 : p->exit_signal = current->group_leader->exit_signal;
2642 : } else {
2643 382 : p->real_parent = current;
2644 382 : p->parent_exec_id = current->self_exec_id;
2645 382 : p->exit_signal = args->exit_signal;
2646 : }
2647 :
2648 382 : klp_copy_process(p);
2649 :
2650 382 : sched_core_fork(p);
2651 :
2652 764 : spin_lock(¤t->sighand->siglock);
2653 :
2654 : rv_task_fork(p);
2655 :
2656 382 : rseq_fork(p, clone_flags);
2657 :
2658 : /* Don't start children in a dying pid namespace */
2659 382 : if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2660 : retval = -ENOMEM;
2661 : goto bad_fork_cancel_cgroup;
2662 : }
2663 :
2664 : /* Let kill terminate clone/fork in the middle */
2665 382 : if (fatal_signal_pending(current)) {
2666 : retval = -EINTR;
2667 : goto bad_fork_cancel_cgroup;
2668 : }
2669 :
2670 : /* No more failure paths after this point. */
2671 :
2672 : /*
2673 : * Copy seccomp details explicitly here, in case they were changed
2674 : * before holding sighand lock.
2675 : */
2676 382 : copy_seccomp(p);
2677 :
2678 382 : init_task_pid_links(p);
2679 382 : if (likely(p->pid)) {
2680 382 : ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2681 :
2682 764 : init_task_pid(p, PIDTYPE_PID, pid);
2683 382 : if (thread_group_leader(p)) {
2684 764 : init_task_pid(p, PIDTYPE_TGID, pid);
2685 1146 : init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2686 1146 : init_task_pid(p, PIDTYPE_SID, task_session(current));
2687 :
2688 382 : if (is_child_reaper(pid)) {
2689 1 : ns_of_pid(pid)->child_reaper = p;
2690 1 : p->signal->flags |= SIGNAL_UNKILLABLE;
2691 : }
2692 382 : p->signal->shared_pending.signal = delayed.signal;
2693 1146 : p->signal->tty = tty_kref_get(current->signal->tty);
2694 : /*
2695 : * Inherit has_child_subreaper flag under the same
2696 : * tasklist_lock with adding child to the process tree
2697 : * for propagate_has_child_subreaper optimization.
2698 : */
2699 382 : p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2700 : p->real_parent->signal->is_child_subreaper;
2701 764 : list_add_tail(&p->sibling, &p->real_parent->children);
2702 764 : list_add_tail_rcu(&p->tasks, &init_task.tasks);
2703 382 : attach_pid(p, PIDTYPE_TGID);
2704 382 : attach_pid(p, PIDTYPE_PGID);
2705 382 : attach_pid(p, PIDTYPE_SID);
2706 382 : __this_cpu_inc(process_counts);
2707 : } else {
2708 0 : current->signal->nr_threads++;
2709 0 : current->signal->quick_threads++;
2710 0 : atomic_inc(¤t->signal->live);
2711 0 : refcount_inc(¤t->signal->sigcnt);
2712 0 : task_join_group_stop(p);
2713 0 : list_add_tail_rcu(&p->thread_group,
2714 0 : &p->group_leader->thread_group);
2715 0 : list_add_tail_rcu(&p->thread_node,
2716 0 : &p->signal->thread_head);
2717 : }
2718 382 : attach_pid(p, PIDTYPE_PID);
2719 382 : nr_threads++;
2720 : }
2721 382 : total_forks++;
2722 382 : hlist_del_init(&delayed.node);
2723 764 : spin_unlock(¤t->sighand->siglock);
2724 382 : syscall_tracepoint_update(p);
2725 382 : write_unlock_irq(&tasklist_lock);
2726 :
2727 382 : if (pidfile)
2728 0 : fd_install(pidfd, pidfile);
2729 :
2730 382 : proc_fork_connector(p);
2731 382 : sched_post_fork(p);
2732 382 : cgroup_post_fork(p, args);
2733 382 : perf_event_fork(p);
2734 :
2735 382 : trace_task_newtask(p, clone_flags);
2736 382 : uprobe_copy_process(p, clone_flags);
2737 382 : user_events_fork(p, clone_flags);
2738 :
2739 382 : copy_oom_score_adj(clone_flags, p);
2740 :
2741 382 : return p;
2742 :
2743 : bad_fork_cancel_cgroup:
2744 0 : sched_core_free(p);
2745 0 : spin_unlock(¤t->sighand->siglock);
2746 0 : write_unlock_irq(&tasklist_lock);
2747 0 : cgroup_cancel_fork(p, args);
2748 : bad_fork_put_pidfd:
2749 0 : if (clone_flags & CLONE_PIDFD) {
2750 0 : fput(pidfile);
2751 0 : put_unused_fd(pidfd);
2752 : }
2753 : bad_fork_free_pid:
2754 0 : if (pid != &init_struct_pid)
2755 0 : free_pid(pid);
2756 : bad_fork_cleanup_thread:
2757 : exit_thread(p);
2758 : bad_fork_cleanup_io:
2759 0 : if (p->io_context)
2760 0 : exit_io_context(p);
2761 : bad_fork_cleanup_namespaces:
2762 0 : exit_task_namespaces(p);
2763 : bad_fork_cleanup_mm:
2764 0 : if (p->mm) {
2765 0 : mm_clear_owner(p->mm, p);
2766 0 : mmput(p->mm);
2767 : }
2768 : bad_fork_cleanup_signal:
2769 0 : if (!(clone_flags & CLONE_THREAD))
2770 0 : free_signal_struct(p->signal);
2771 : bad_fork_cleanup_sighand:
2772 0 : __cleanup_sighand(p->sighand);
2773 : bad_fork_cleanup_fs:
2774 0 : exit_fs(p); /* blocking */
2775 : bad_fork_cleanup_files:
2776 0 : exit_files(p); /* blocking */
2777 : bad_fork_cleanup_semundo:
2778 : exit_sem(p);
2779 : bad_fork_cleanup_security:
2780 : security_task_free(p);
2781 : bad_fork_cleanup_audit:
2782 : audit_free(p);
2783 : bad_fork_cleanup_perf:
2784 : perf_event_free_task(p);
2785 : bad_fork_cleanup_policy:
2786 : lockdep_free_task(p);
2787 : #ifdef CONFIG_NUMA
2788 : mpol_put(p->mempolicy);
2789 : #endif
2790 : bad_fork_cleanup_delayacct:
2791 : delayacct_tsk_free(p);
2792 : bad_fork_cleanup_count:
2793 0 : dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2794 0 : exit_creds(p);
2795 : bad_fork_free:
2796 0 : WRITE_ONCE(p->__state, TASK_DEAD);
2797 0 : exit_task_stack_account(p);
2798 0 : put_task_stack(p);
2799 : delayed_free_task(p);
2800 : fork_out:
2801 0 : spin_lock_irq(¤t->sighand->siglock);
2802 0 : hlist_del_init(&delayed.node);
2803 0 : spin_unlock_irq(¤t->sighand->siglock);
2804 0 : return ERR_PTR(retval);
2805 : }
2806 :
2807 : static inline void init_idle_pids(struct task_struct *idle)
2808 : {
2809 : enum pid_type type;
2810 :
2811 0 : for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2812 0 : INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2813 0 : init_task_pid(idle, type, &init_struct_pid);
2814 : }
2815 : }
2816 :
2817 0 : static int idle_dummy(void *dummy)
2818 : {
2819 : /* This function is never called */
2820 0 : return 0;
2821 : }
2822 :
2823 0 : struct task_struct * __init fork_idle(int cpu)
2824 : {
2825 : struct task_struct *task;
2826 0 : struct kernel_clone_args args = {
2827 : .flags = CLONE_VM,
2828 : .fn = &idle_dummy,
2829 : .fn_arg = NULL,
2830 : .kthread = 1,
2831 : .idle = 1,
2832 : };
2833 :
2834 0 : task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2835 0 : if (!IS_ERR(task)) {
2836 0 : init_idle_pids(task);
2837 0 : init_idle(task, cpu);
2838 : }
2839 :
2840 0 : return task;
2841 : }
2842 :
2843 : /*
2844 : * This is like kernel_clone(), but shaved down and tailored to just
2845 : * creating io_uring workers. It returns a created task, or an error pointer.
2846 : * The returned task is inactive, and the caller must fire it up through
2847 : * wake_up_new_task(p). All signals are blocked in the created task.
2848 : */
2849 0 : struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2850 : {
2851 0 : unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2852 : CLONE_IO;
2853 0 : struct kernel_clone_args args = {
2854 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2855 : CLONE_UNTRACED) & ~CSIGNAL),
2856 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2857 : .fn = fn,
2858 : .fn_arg = arg,
2859 : .io_thread = 1,
2860 : .user_worker = 1,
2861 : };
2862 :
2863 0 : return copy_process(NULL, 0, node, &args);
2864 : }
2865 :
2866 : /*
2867 : * Ok, this is the main fork-routine.
2868 : *
2869 : * It copies the process, and if successful kick-starts
2870 : * it and waits for it to finish using the VM if required.
2871 : *
2872 : * args->exit_signal is expected to be checked for sanity by the caller.
2873 : */
2874 382 : pid_t kernel_clone(struct kernel_clone_args *args)
2875 : {
2876 382 : u64 clone_flags = args->flags;
2877 : struct completion vfork;
2878 : struct pid *pid;
2879 : struct task_struct *p;
2880 382 : int trace = 0;
2881 : pid_t nr;
2882 :
2883 : /*
2884 : * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2885 : * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2886 : * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2887 : * field in struct clone_args and it still doesn't make sense to have
2888 : * them both point at the same memory location. Performing this check
2889 : * here has the advantage that we don't need to have a separate helper
2890 : * to check for legacy clone().
2891 : */
2892 382 : if ((args->flags & CLONE_PIDFD) &&
2893 0 : (args->flags & CLONE_PARENT_SETTID) &&
2894 0 : (args->pidfd == args->parent_tid))
2895 : return -EINVAL;
2896 :
2897 : /*
2898 : * Determine whether and which event to report to ptracer. When
2899 : * called from kernel_thread or CLONE_UNTRACED is explicitly
2900 : * requested, no event is reported; otherwise, report if the event
2901 : * for the type of forking is enabled.
2902 : */
2903 382 : if (!(clone_flags & CLONE_UNTRACED)) {
2904 0 : if (clone_flags & CLONE_VFORK)
2905 : trace = PTRACE_EVENT_VFORK;
2906 0 : else if (args->exit_signal != SIGCHLD)
2907 : trace = PTRACE_EVENT_CLONE;
2908 : else
2909 0 : trace = PTRACE_EVENT_FORK;
2910 :
2911 0 : if (likely(!ptrace_event_enabled(current, trace)))
2912 0 : trace = 0;
2913 : }
2914 :
2915 382 : p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2916 382 : add_latent_entropy();
2917 :
2918 382 : if (IS_ERR(p))
2919 0 : return PTR_ERR(p);
2920 :
2921 : /*
2922 : * Do this prior waking up the new thread - the thread pointer
2923 : * might get invalid after that point, if the thread exits quickly.
2924 : */
2925 382 : trace_sched_process_fork(current, p);
2926 :
2927 382 : pid = get_task_pid(p, PIDTYPE_PID);
2928 382 : nr = pid_vnr(pid);
2929 :
2930 382 : if (clone_flags & CLONE_PARENT_SETTID)
2931 0 : put_user(nr, args->parent_tid);
2932 :
2933 382 : if (clone_flags & CLONE_VFORK) {
2934 0 : p->vfork_done = &vfork;
2935 0 : init_completion(&vfork);
2936 : get_task_struct(p);
2937 : }
2938 :
2939 : if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) {
2940 : /* lock the task to synchronize with memcg migration */
2941 : task_lock(p);
2942 : lru_gen_add_mm(p->mm);
2943 : task_unlock(p);
2944 : }
2945 :
2946 382 : wake_up_new_task(p);
2947 :
2948 : /* forking complete and child started to run, tell ptracer */
2949 382 : if (unlikely(trace))
2950 0 : ptrace_event_pid(trace, pid);
2951 :
2952 382 : if (clone_flags & CLONE_VFORK) {
2953 0 : if (!wait_for_vfork_done(p, &vfork))
2954 0 : ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2955 : }
2956 :
2957 382 : put_pid(pid);
2958 382 : return nr;
2959 : }
2960 :
2961 : /*
2962 : * Create a kernel thread.
2963 : */
2964 381 : pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
2965 : unsigned long flags)
2966 : {
2967 1143 : struct kernel_clone_args args = {
2968 381 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2969 381 : CLONE_UNTRACED) & ~CSIGNAL),
2970 381 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2971 : .fn = fn,
2972 : .fn_arg = arg,
2973 : .name = name,
2974 : .kthread = 1,
2975 : };
2976 :
2977 381 : return kernel_clone(&args);
2978 : }
2979 :
2980 : /*
2981 : * Create a user mode thread.
2982 : */
2983 1 : pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
2984 : {
2985 3 : struct kernel_clone_args args = {
2986 1 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2987 1 : CLONE_UNTRACED) & ~CSIGNAL),
2988 1 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2989 : .fn = fn,
2990 : .fn_arg = arg,
2991 : };
2992 :
2993 1 : return kernel_clone(&args);
2994 : }
2995 :
2996 : #ifdef __ARCH_WANT_SYS_FORK
2997 0 : SYSCALL_DEFINE0(fork)
2998 : {
2999 : #ifdef CONFIG_MMU
3000 0 : struct kernel_clone_args args = {
3001 : .exit_signal = SIGCHLD,
3002 : };
3003 :
3004 0 : return kernel_clone(&args);
3005 : #else
3006 : /* can not support in nommu mode */
3007 : return -EINVAL;
3008 : #endif
3009 : }
3010 : #endif
3011 :
3012 : #ifdef __ARCH_WANT_SYS_VFORK
3013 0 : SYSCALL_DEFINE0(vfork)
3014 : {
3015 0 : struct kernel_clone_args args = {
3016 : .flags = CLONE_VFORK | CLONE_VM,
3017 : .exit_signal = SIGCHLD,
3018 : };
3019 :
3020 0 : return kernel_clone(&args);
3021 : }
3022 : #endif
3023 :
3024 : #ifdef __ARCH_WANT_SYS_CLONE
3025 : #ifdef CONFIG_CLONE_BACKWARDS
3026 : SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
3027 : int __user *, parent_tidptr,
3028 : unsigned long, tls,
3029 : int __user *, child_tidptr)
3030 : #elif defined(CONFIG_CLONE_BACKWARDS2)
3031 : SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
3032 : int __user *, parent_tidptr,
3033 : int __user *, child_tidptr,
3034 : unsigned long, tls)
3035 : #elif defined(CONFIG_CLONE_BACKWARDS3)
3036 : SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
3037 : int, stack_size,
3038 : int __user *, parent_tidptr,
3039 : int __user *, child_tidptr,
3040 : unsigned long, tls)
3041 : #else
3042 0 : SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
3043 : int __user *, parent_tidptr,
3044 : int __user *, child_tidptr,
3045 : unsigned long, tls)
3046 : #endif
3047 : {
3048 0 : struct kernel_clone_args args = {
3049 0 : .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
3050 : .pidfd = parent_tidptr,
3051 : .child_tid = child_tidptr,
3052 : .parent_tid = parent_tidptr,
3053 0 : .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
3054 : .stack = newsp,
3055 : .tls = tls,
3056 : };
3057 :
3058 0 : return kernel_clone(&args);
3059 : }
3060 : #endif
3061 :
3062 : #ifdef __ARCH_WANT_SYS_CLONE3
3063 :
3064 0 : noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
3065 : struct clone_args __user *uargs,
3066 : size_t usize)
3067 : {
3068 : int err;
3069 : struct clone_args args;
3070 0 : pid_t *kset_tid = kargs->set_tid;
3071 :
3072 : BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
3073 : CLONE_ARGS_SIZE_VER0);
3074 : BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
3075 : CLONE_ARGS_SIZE_VER1);
3076 : BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
3077 : CLONE_ARGS_SIZE_VER2);
3078 : BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
3079 :
3080 0 : if (unlikely(usize > PAGE_SIZE))
3081 : return -E2BIG;
3082 0 : if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
3083 : return -EINVAL;
3084 :
3085 0 : err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
3086 0 : if (err)
3087 : return err;
3088 :
3089 0 : if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
3090 : return -EINVAL;
3091 :
3092 0 : if (unlikely(!args.set_tid && args.set_tid_size > 0))
3093 : return -EINVAL;
3094 :
3095 0 : if (unlikely(args.set_tid && args.set_tid_size == 0))
3096 : return -EINVAL;
3097 :
3098 : /*
3099 : * Verify that higher 32bits of exit_signal are unset and that
3100 : * it is a valid signal
3101 : */
3102 0 : if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
3103 : !valid_signal(args.exit_signal)))
3104 : return -EINVAL;
3105 :
3106 0 : if ((args.flags & CLONE_INTO_CGROUP) &&
3107 0 : (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
3108 : return -EINVAL;
3109 :
3110 0 : *kargs = (struct kernel_clone_args){
3111 : .flags = args.flags,
3112 0 : .pidfd = u64_to_user_ptr(args.pidfd),
3113 0 : .child_tid = u64_to_user_ptr(args.child_tid),
3114 0 : .parent_tid = u64_to_user_ptr(args.parent_tid),
3115 : .exit_signal = args.exit_signal,
3116 0 : .stack = args.stack,
3117 0 : .stack_size = args.stack_size,
3118 0 : .tls = args.tls,
3119 : .set_tid_size = args.set_tid_size,
3120 0 : .cgroup = args.cgroup,
3121 : };
3122 :
3123 0 : if (args.set_tid &&
3124 0 : copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
3125 : (kargs->set_tid_size * sizeof(pid_t))))
3126 : return -EFAULT;
3127 :
3128 0 : kargs->set_tid = kset_tid;
3129 :
3130 0 : return 0;
3131 : }
3132 :
3133 : /**
3134 : * clone3_stack_valid - check and prepare stack
3135 : * @kargs: kernel clone args
3136 : *
3137 : * Verify that the stack arguments userspace gave us are sane.
3138 : * In addition, set the stack direction for userspace since it's easy for us to
3139 : * determine.
3140 : */
3141 0 : static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
3142 : {
3143 0 : if (kargs->stack == 0) {
3144 0 : if (kargs->stack_size > 0)
3145 : return false;
3146 : } else {
3147 0 : if (kargs->stack_size == 0)
3148 : return false;
3149 :
3150 0 : if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
3151 : return false;
3152 :
3153 : #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
3154 0 : kargs->stack += kargs->stack_size;
3155 : #endif
3156 : }
3157 :
3158 : return true;
3159 : }
3160 :
3161 0 : static bool clone3_args_valid(struct kernel_clone_args *kargs)
3162 : {
3163 : /* Verify that no unknown flags are passed along. */
3164 0 : if (kargs->flags &
3165 : ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
3166 : return false;
3167 :
3168 : /*
3169 : * - make the CLONE_DETACHED bit reusable for clone3
3170 : * - make the CSIGNAL bits reusable for clone3
3171 : */
3172 0 : if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
3173 : return false;
3174 :
3175 0 : if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
3176 : (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
3177 : return false;
3178 :
3179 0 : if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
3180 0 : kargs->exit_signal)
3181 : return false;
3182 :
3183 0 : if (!clone3_stack_valid(kargs))
3184 : return false;
3185 :
3186 0 : return true;
3187 : }
3188 :
3189 : /**
3190 : * clone3 - create a new process with specific properties
3191 : * @uargs: argument structure
3192 : * @size: size of @uargs
3193 : *
3194 : * clone3() is the extensible successor to clone()/clone2().
3195 : * It takes a struct as argument that is versioned by its size.
3196 : *
3197 : * Return: On success, a positive PID for the child process.
3198 : * On error, a negative errno number.
3199 : */
3200 0 : SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
3201 : {
3202 : int err;
3203 :
3204 : struct kernel_clone_args kargs;
3205 : pid_t set_tid[MAX_PID_NS_LEVEL];
3206 :
3207 0 : kargs.set_tid = set_tid;
3208 :
3209 0 : err = copy_clone_args_from_user(&kargs, uargs, size);
3210 0 : if (err)
3211 0 : return err;
3212 :
3213 0 : if (!clone3_args_valid(&kargs))
3214 : return -EINVAL;
3215 :
3216 0 : return kernel_clone(&kargs);
3217 : }
3218 : #endif
3219 :
3220 0 : void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
3221 : {
3222 : struct task_struct *leader, *parent, *child;
3223 : int res;
3224 :
3225 0 : read_lock(&tasklist_lock);
3226 0 : leader = top = top->group_leader;
3227 : down:
3228 0 : for_each_thread(leader, parent) {
3229 0 : list_for_each_entry(child, &parent->children, sibling) {
3230 0 : res = visitor(child, data);
3231 0 : if (res) {
3232 0 : if (res < 0)
3233 : goto out;
3234 : leader = child;
3235 : goto down;
3236 : }
3237 : up:
3238 : ;
3239 : }
3240 : }
3241 :
3242 0 : if (leader != top) {
3243 0 : child = leader;
3244 0 : parent = child->real_parent;
3245 0 : leader = parent->group_leader;
3246 0 : goto up;
3247 : }
3248 : out:
3249 0 : read_unlock(&tasklist_lock);
3250 0 : }
3251 :
3252 : #ifndef ARCH_MIN_MMSTRUCT_ALIGN
3253 : #define ARCH_MIN_MMSTRUCT_ALIGN 0
3254 : #endif
3255 :
3256 30 : static void sighand_ctor(void *data)
3257 : {
3258 30 : struct sighand_struct *sighand = data;
3259 :
3260 30 : spin_lock_init(&sighand->siglock);
3261 30 : init_waitqueue_head(&sighand->signalfd_wqh);
3262 30 : }
3263 :
3264 1 : void __init mm_cache_init(void)
3265 : {
3266 : unsigned int mm_size;
3267 :
3268 : /*
3269 : * The mm_cpumask is located at the end of mm_struct, and is
3270 : * dynamically sized based on the maximum CPU number this system
3271 : * can have, taking hotplug into account (nr_cpu_ids).
3272 : */
3273 1 : mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size();
3274 :
3275 1 : mm_cachep = kmem_cache_create_usercopy("mm_struct",
3276 : mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
3277 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3278 : offsetof(struct mm_struct, saved_auxv),
3279 : sizeof_field(struct mm_struct, saved_auxv),
3280 : NULL);
3281 1 : }
3282 :
3283 1 : void __init proc_caches_init(void)
3284 : {
3285 1 : sighand_cachep = kmem_cache_create("sighand_cache",
3286 : sizeof(struct sighand_struct), 0,
3287 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
3288 : SLAB_ACCOUNT, sighand_ctor);
3289 1 : signal_cachep = kmem_cache_create("signal_cache",
3290 : sizeof(struct signal_struct), 0,
3291 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3292 : NULL);
3293 1 : files_cachep = kmem_cache_create("files_cache",
3294 : sizeof(struct files_struct), 0,
3295 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3296 : NULL);
3297 1 : fs_cachep = kmem_cache_create("fs_cache",
3298 : sizeof(struct fs_struct), 0,
3299 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3300 : NULL);
3301 :
3302 1 : vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
3303 : #ifdef CONFIG_PER_VMA_LOCK
3304 : vma_lock_cachep = KMEM_CACHE(vma_lock, SLAB_PANIC|SLAB_ACCOUNT);
3305 : #endif
3306 1 : mmap_init();
3307 1 : nsproxy_cache_init();
3308 1 : }
3309 :
3310 : /*
3311 : * Check constraints on flags passed to the unshare system call.
3312 : */
3313 0 : static int check_unshare_flags(unsigned long unshare_flags)
3314 : {
3315 0 : if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3316 : CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3317 : CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3318 : CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3319 : CLONE_NEWTIME))
3320 : return -EINVAL;
3321 : /*
3322 : * Not implemented, but pretend it works if there is nothing
3323 : * to unshare. Note that unsharing the address space or the
3324 : * signal handlers also need to unshare the signal queues (aka
3325 : * CLONE_THREAD).
3326 : */
3327 0 : if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3328 0 : if (!thread_group_empty(current))
3329 : return -EINVAL;
3330 : }
3331 0 : if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3332 0 : if (refcount_read(¤t->sighand->count) > 1)
3333 : return -EINVAL;
3334 : }
3335 0 : if (unshare_flags & CLONE_VM) {
3336 0 : if (!current_is_single_threaded())
3337 : return -EINVAL;
3338 : }
3339 :
3340 : return 0;
3341 : }
3342 :
3343 : /*
3344 : * Unshare the filesystem structure if it is being shared
3345 : */
3346 0 : static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3347 : {
3348 0 : struct fs_struct *fs = current->fs;
3349 :
3350 0 : if (!(unshare_flags & CLONE_FS) || !fs)
3351 : return 0;
3352 :
3353 : /* don't need lock here; in the worst case we'll do useless copy */
3354 0 : if (fs->users == 1)
3355 : return 0;
3356 :
3357 0 : *new_fsp = copy_fs_struct(fs);
3358 0 : if (!*new_fsp)
3359 : return -ENOMEM;
3360 :
3361 0 : return 0;
3362 : }
3363 :
3364 : /*
3365 : * Unshare file descriptor table if it is being shared
3366 : */
3367 0 : int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3368 : struct files_struct **new_fdp)
3369 : {
3370 0 : struct files_struct *fd = current->files;
3371 0 : int error = 0;
3372 :
3373 0 : if ((unshare_flags & CLONE_FILES) &&
3374 0 : (fd && atomic_read(&fd->count) > 1)) {
3375 0 : *new_fdp = dup_fd(fd, max_fds, &error);
3376 0 : if (!*new_fdp)
3377 0 : return error;
3378 : }
3379 :
3380 : return 0;
3381 : }
3382 :
3383 : /*
3384 : * unshare allows a process to 'unshare' part of the process
3385 : * context which was originally shared using clone. copy_*
3386 : * functions used by kernel_clone() cannot be used here directly
3387 : * because they modify an inactive task_struct that is being
3388 : * constructed. Here we are modifying the current, active,
3389 : * task_struct.
3390 : */
3391 0 : int ksys_unshare(unsigned long unshare_flags)
3392 : {
3393 0 : struct fs_struct *fs, *new_fs = NULL;
3394 0 : struct files_struct *new_fd = NULL;
3395 0 : struct cred *new_cred = NULL;
3396 0 : struct nsproxy *new_nsproxy = NULL;
3397 0 : int do_sysvsem = 0;
3398 : int err;
3399 :
3400 : /*
3401 : * If unsharing a user namespace must also unshare the thread group
3402 : * and unshare the filesystem root and working directories.
3403 : */
3404 0 : if (unshare_flags & CLONE_NEWUSER)
3405 0 : unshare_flags |= CLONE_THREAD | CLONE_FS;
3406 : /*
3407 : * If unsharing vm, must also unshare signal handlers.
3408 : */
3409 0 : if (unshare_flags & CLONE_VM)
3410 0 : unshare_flags |= CLONE_SIGHAND;
3411 : /*
3412 : * If unsharing a signal handlers, must also unshare the signal queues.
3413 : */
3414 0 : if (unshare_flags & CLONE_SIGHAND)
3415 0 : unshare_flags |= CLONE_THREAD;
3416 : /*
3417 : * If unsharing namespace, must also unshare filesystem information.
3418 : */
3419 0 : if (unshare_flags & CLONE_NEWNS)
3420 0 : unshare_flags |= CLONE_FS;
3421 :
3422 0 : err = check_unshare_flags(unshare_flags);
3423 0 : if (err)
3424 : goto bad_unshare_out;
3425 : /*
3426 : * CLONE_NEWIPC must also detach from the undolist: after switching
3427 : * to a new ipc namespace, the semaphore arrays from the old
3428 : * namespace are unreachable.
3429 : */
3430 0 : if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3431 0 : do_sysvsem = 1;
3432 0 : err = unshare_fs(unshare_flags, &new_fs);
3433 0 : if (err)
3434 : goto bad_unshare_out;
3435 0 : err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3436 0 : if (err)
3437 : goto bad_unshare_cleanup_fs;
3438 0 : err = unshare_userns(unshare_flags, &new_cred);
3439 0 : if (err)
3440 : goto bad_unshare_cleanup_fd;
3441 0 : err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3442 : new_cred, new_fs);
3443 0 : if (err)
3444 : goto bad_unshare_cleanup_cred;
3445 :
3446 : if (new_cred) {
3447 : err = set_cred_ucounts(new_cred);
3448 : if (err)
3449 : goto bad_unshare_cleanup_cred;
3450 : }
3451 :
3452 0 : if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3453 0 : if (do_sysvsem) {
3454 : /*
3455 : * CLONE_SYSVSEM is equivalent to sys_exit().
3456 : */
3457 0 : exit_sem(current);
3458 : }
3459 0 : if (unshare_flags & CLONE_NEWIPC) {
3460 : /* Orphan segments in old ns (see sem above). */
3461 0 : exit_shm(current);
3462 0 : shm_init_task(current);
3463 : }
3464 :
3465 0 : if (new_nsproxy)
3466 0 : switch_task_namespaces(current, new_nsproxy);
3467 :
3468 0 : task_lock(current);
3469 :
3470 0 : if (new_fs) {
3471 0 : fs = current->fs;
3472 0 : spin_lock(&fs->lock);
3473 0 : current->fs = new_fs;
3474 0 : if (--fs->users)
3475 0 : new_fs = NULL;
3476 : else
3477 0 : new_fs = fs;
3478 0 : spin_unlock(&fs->lock);
3479 : }
3480 :
3481 0 : if (new_fd)
3482 0 : swap(current->files, new_fd);
3483 :
3484 0 : task_unlock(current);
3485 :
3486 : if (new_cred) {
3487 : /* Install the new user namespace */
3488 : commit_creds(new_cred);
3489 : new_cred = NULL;
3490 : }
3491 : }
3492 :
3493 0 : perf_event_namespaces(current);
3494 :
3495 : bad_unshare_cleanup_cred:
3496 : if (new_cred)
3497 : put_cred(new_cred);
3498 : bad_unshare_cleanup_fd:
3499 0 : if (new_fd)
3500 0 : put_files_struct(new_fd);
3501 :
3502 : bad_unshare_cleanup_fs:
3503 0 : if (new_fs)
3504 0 : free_fs_struct(new_fs);
3505 :
3506 : bad_unshare_out:
3507 0 : return err;
3508 : }
3509 :
3510 0 : SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3511 : {
3512 0 : return ksys_unshare(unshare_flags);
3513 : }
3514 :
3515 : /*
3516 : * Helper to unshare the files of the current task.
3517 : * We don't want to expose copy_files internals to
3518 : * the exec layer of the kernel.
3519 : */
3520 :
3521 0 : int unshare_files(void)
3522 : {
3523 0 : struct task_struct *task = current;
3524 0 : struct files_struct *old, *copy = NULL;
3525 : int error;
3526 :
3527 0 : error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3528 0 : if (error || !copy)
3529 : return error;
3530 :
3531 0 : old = task->files;
3532 0 : task_lock(task);
3533 0 : task->files = copy;
3534 0 : task_unlock(task);
3535 0 : put_files_struct(old);
3536 0 : return 0;
3537 : }
3538 :
3539 0 : int sysctl_max_threads(struct ctl_table *table, int write,
3540 : void *buffer, size_t *lenp, loff_t *ppos)
3541 : {
3542 : struct ctl_table t;
3543 : int ret;
3544 0 : int threads = max_threads;
3545 0 : int min = 1;
3546 0 : int max = MAX_THREADS;
3547 :
3548 0 : t = *table;
3549 0 : t.data = &threads;
3550 0 : t.extra1 = &min;
3551 0 : t.extra2 = &max;
3552 :
3553 0 : ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3554 0 : if (ret || !write)
3555 : return ret;
3556 :
3557 0 : max_threads = threads;
3558 :
3559 0 : return 0;
3560 : }
|
