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 :
101 : #include <asm/pgalloc.h>
102 : #include <linux/uaccess.h>
103 : #include <asm/mmu_context.h>
104 : #include <asm/cacheflush.h>
105 : #include <asm/tlbflush.h>
106 :
107 : #include <trace/events/sched.h>
108 :
109 : #define CREATE_TRACE_POINTS
110 : #include <trace/events/task.h>
111 :
112 : /*
113 : * Minimum number of threads to boot the kernel
114 : */
115 : #define MIN_THREADS 20
116 :
117 : /*
118 : * Maximum number of threads
119 : */
120 : #define MAX_THREADS FUTEX_TID_MASK
121 :
122 : /*
123 : * Protected counters by write_lock_irq(&tasklist_lock)
124 : */
125 : unsigned long total_forks; /* Handle normal Linux uptimes. */
126 : int nr_threads; /* The idle threads do not count.. */
127 :
128 : static int max_threads; /* tunable limit on nr_threads */
129 :
130 : #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
131 :
132 : static const char * const resident_page_types[] = {
133 : NAMED_ARRAY_INDEX(MM_FILEPAGES),
134 : NAMED_ARRAY_INDEX(MM_ANONPAGES),
135 : NAMED_ARRAY_INDEX(MM_SWAPENTS),
136 : NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
137 : };
138 :
139 : DEFINE_PER_CPU(unsigned long, process_counts) = 0;
140 :
141 : __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
142 :
143 : #ifdef CONFIG_PROVE_RCU
144 : int lockdep_tasklist_lock_is_held(void)
145 : {
146 : return lockdep_is_held(&tasklist_lock);
147 : }
148 : EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
149 : #endif /* #ifdef CONFIG_PROVE_RCU */
150 :
151 0 : int nr_processes(void)
152 : {
153 : int cpu;
154 0 : int total = 0;
155 :
156 0 : for_each_possible_cpu(cpu)
157 0 : total += per_cpu(process_counts, cpu);
158 :
159 0 : return total;
160 : }
161 :
162 324 : void __weak arch_release_task_struct(struct task_struct *tsk)
163 : {
164 324 : }
165 :
166 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
167 : static struct kmem_cache *task_struct_cachep;
168 :
169 : static inline struct task_struct *alloc_task_struct_node(int node)
170 : {
171 340 : return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
172 : }
173 :
174 : static inline void free_task_struct(struct task_struct *tsk)
175 : {
176 324 : kmem_cache_free(task_struct_cachep, tsk);
177 : }
178 : #endif
179 :
180 : #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
181 :
182 : /*
183 : * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
184 : * kmemcache based allocator.
185 : */
186 : # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
187 :
188 : # ifdef CONFIG_VMAP_STACK
189 : /*
190 : * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
191 : * flush. Try to minimize the number of calls by caching stacks.
192 : */
193 : #define NR_CACHED_STACKS 2
194 : static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
195 :
196 : struct vm_stack {
197 : struct rcu_head rcu;
198 : struct vm_struct *stack_vm_area;
199 : };
200 :
201 324 : static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
202 : {
203 : unsigned int i;
204 :
205 324 : for (i = 0; i < NR_CACHED_STACKS; i++) {
206 972 : if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
207 0 : continue;
208 : return true;
209 : }
210 : return false;
211 : }
212 :
213 0 : static void thread_stack_free_rcu(struct rcu_head *rh)
214 : {
215 0 : struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
216 :
217 0 : if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
218 : return;
219 :
220 0 : vfree(vm_stack);
221 : }
222 :
223 : static void thread_stack_delayed_free(struct task_struct *tsk)
224 : {
225 0 : struct vm_stack *vm_stack = tsk->stack;
226 :
227 0 : vm_stack->stack_vm_area = tsk->stack_vm_area;
228 0 : call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
229 : }
230 :
231 0 : static int free_vm_stack_cache(unsigned int cpu)
232 : {
233 0 : struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
234 : int i;
235 :
236 0 : for (i = 0; i < NR_CACHED_STACKS; i++) {
237 0 : struct vm_struct *vm_stack = cached_vm_stacks[i];
238 :
239 0 : if (!vm_stack)
240 0 : continue;
241 :
242 0 : vfree(vm_stack->addr);
243 0 : cached_vm_stacks[i] = NULL;
244 : }
245 :
246 0 : return 0;
247 : }
248 :
249 340 : static int memcg_charge_kernel_stack(struct vm_struct *vm)
250 : {
251 : int i;
252 : int ret;
253 :
254 : BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
255 340 : BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
256 :
257 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
258 : ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
259 : if (ret)
260 : goto err;
261 : }
262 : return 0;
263 : err:
264 : /*
265 : * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
266 : * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
267 : * ignore this page.
268 : */
269 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
270 : memcg_kmem_uncharge_page(vm->pages[i], 0);
271 : return ret;
272 : }
273 :
274 340 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
275 : {
276 : struct vm_struct *vm;
277 : void *stack;
278 : int i;
279 :
280 744 : for (i = 0; i < NR_CACHED_STACKS; i++) {
281 : struct vm_struct *s;
282 :
283 1068 : s = this_cpu_xchg(cached_stacks[i], NULL);
284 :
285 356 : if (!s)
286 32 : continue;
287 :
288 : /* Reset stack metadata. */
289 324 : kasan_unpoison_range(s->addr, THREAD_SIZE);
290 :
291 324 : stack = kasan_reset_tag(s->addr);
292 :
293 : /* Clear stale pointers from reused stack. */
294 324 : memset(stack, 0, THREAD_SIZE);
295 :
296 324 : if (memcg_charge_kernel_stack(s)) {
297 0 : vfree(s->addr);
298 : return -ENOMEM;
299 : }
300 :
301 324 : tsk->stack_vm_area = s;
302 324 : tsk->stack = stack;
303 : return 0;
304 : }
305 :
306 : /*
307 : * Allocated stacks are cached and later reused by new threads,
308 : * so memcg accounting is performed manually on assigning/releasing
309 : * stacks to tasks. Drop __GFP_ACCOUNT.
310 : */
311 32 : stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
312 16 : VMALLOC_START, VMALLOC_END,
313 : THREADINFO_GFP & ~__GFP_ACCOUNT,
314 16 : PAGE_KERNEL,
315 16 : 0, node, __builtin_return_address(0));
316 16 : if (!stack)
317 : return -ENOMEM;
318 :
319 16 : vm = find_vm_area(stack);
320 16 : if (memcg_charge_kernel_stack(vm)) {
321 0 : vfree(stack);
322 : return -ENOMEM;
323 : }
324 : /*
325 : * We can't call find_vm_area() in interrupt context, and
326 : * free_thread_stack() can be called in interrupt context,
327 : * so cache the vm_struct.
328 : */
329 16 : tsk->stack_vm_area = vm;
330 16 : stack = kasan_reset_tag(stack);
331 16 : tsk->stack = stack;
332 : return 0;
333 : }
334 :
335 324 : static void free_thread_stack(struct task_struct *tsk)
336 : {
337 324 : if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
338 0 : thread_stack_delayed_free(tsk);
339 :
340 324 : tsk->stack = NULL;
341 324 : tsk->stack_vm_area = NULL;
342 324 : }
343 :
344 : # else /* !CONFIG_VMAP_STACK */
345 :
346 : static void thread_stack_free_rcu(struct rcu_head *rh)
347 : {
348 : __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
349 : }
350 :
351 : static void thread_stack_delayed_free(struct task_struct *tsk)
352 : {
353 : struct rcu_head *rh = tsk->stack;
354 :
355 : call_rcu(rh, thread_stack_free_rcu);
356 : }
357 :
358 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
359 : {
360 : struct page *page = alloc_pages_node(node, THREADINFO_GFP,
361 : THREAD_SIZE_ORDER);
362 :
363 : if (likely(page)) {
364 : tsk->stack = kasan_reset_tag(page_address(page));
365 : return 0;
366 : }
367 : return -ENOMEM;
368 : }
369 :
370 : static void free_thread_stack(struct task_struct *tsk)
371 : {
372 : thread_stack_delayed_free(tsk);
373 : tsk->stack = NULL;
374 : }
375 :
376 : # endif /* CONFIG_VMAP_STACK */
377 : # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
378 :
379 : static struct kmem_cache *thread_stack_cache;
380 :
381 : static void thread_stack_free_rcu(struct rcu_head *rh)
382 : {
383 : kmem_cache_free(thread_stack_cache, rh);
384 : }
385 :
386 : static void thread_stack_delayed_free(struct task_struct *tsk)
387 : {
388 : struct rcu_head *rh = tsk->stack;
389 :
390 : call_rcu(rh, thread_stack_free_rcu);
391 : }
392 :
393 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
394 : {
395 : unsigned long *stack;
396 : stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
397 : stack = kasan_reset_tag(stack);
398 : tsk->stack = stack;
399 : return stack ? 0 : -ENOMEM;
400 : }
401 :
402 : static void free_thread_stack(struct task_struct *tsk)
403 : {
404 : thread_stack_delayed_free(tsk);
405 : tsk->stack = NULL;
406 : }
407 :
408 : void thread_stack_cache_init(void)
409 : {
410 : thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
411 : THREAD_SIZE, THREAD_SIZE, 0, 0,
412 : THREAD_SIZE, NULL);
413 : BUG_ON(thread_stack_cache == NULL);
414 : }
415 :
416 : # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
417 : #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
418 :
419 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
420 : {
421 : unsigned long *stack;
422 :
423 : stack = arch_alloc_thread_stack_node(tsk, node);
424 : tsk->stack = stack;
425 : return stack ? 0 : -ENOMEM;
426 : }
427 :
428 : static void free_thread_stack(struct task_struct *tsk)
429 : {
430 : arch_free_thread_stack(tsk);
431 : tsk->stack = NULL;
432 : }
433 :
434 : #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
435 :
436 : /* SLAB cache for signal_struct structures (tsk->signal) */
437 : static struct kmem_cache *signal_cachep;
438 :
439 : /* SLAB cache for sighand_struct structures (tsk->sighand) */
440 : struct kmem_cache *sighand_cachep;
441 :
442 : /* SLAB cache for files_struct structures (tsk->files) */
443 : struct kmem_cache *files_cachep;
444 :
445 : /* SLAB cache for fs_struct structures (tsk->fs) */
446 : struct kmem_cache *fs_cachep;
447 :
448 : /* SLAB cache for vm_area_struct structures */
449 : static struct kmem_cache *vm_area_cachep;
450 :
451 : /* SLAB cache for mm_struct structures (tsk->mm) */
452 : static struct kmem_cache *mm_cachep;
453 :
454 0 : struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
455 : {
456 : struct vm_area_struct *vma;
457 :
458 0 : vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
459 0 : if (vma)
460 : vma_init(vma, mm);
461 0 : return vma;
462 : }
463 :
464 0 : struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
465 : {
466 0 : struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
467 :
468 0 : if (new) {
469 0 : ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
470 0 : ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
471 : /*
472 : * orig->shared.rb may be modified concurrently, but the clone
473 : * will be reinitialized.
474 : */
475 0 : data_race(memcpy(new, orig, sizeof(*new)));
476 0 : INIT_LIST_HEAD(&new->anon_vma_chain);
477 : dup_anon_vma_name(orig, new);
478 : }
479 0 : return new;
480 : }
481 :
482 0 : void vm_area_free(struct vm_area_struct *vma)
483 : {
484 0 : free_anon_vma_name(vma);
485 0 : kmem_cache_free(vm_area_cachep, vma);
486 0 : }
487 :
488 : static void account_kernel_stack(struct task_struct *tsk, int account)
489 : {
490 : if (IS_ENABLED(CONFIG_VMAP_STACK)) {
491 : struct vm_struct *vm = task_stack_vm_area(tsk);
492 : int i;
493 :
494 2660 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
495 5320 : mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
496 : account * (PAGE_SIZE / 1024));
497 : } else {
498 : void *stack = task_stack_page(tsk);
499 :
500 : /* All stack pages are in the same node. */
501 : mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
502 : account * (THREAD_SIZE / 1024));
503 : }
504 : }
505 :
506 325 : void exit_task_stack_account(struct task_struct *tsk)
507 : {
508 650 : account_kernel_stack(tsk, -1);
509 :
510 : if (IS_ENABLED(CONFIG_VMAP_STACK)) {
511 : struct vm_struct *vm;
512 : int i;
513 :
514 325 : vm = task_stack_vm_area(tsk);
515 325 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
516 : memcg_kmem_uncharge_page(vm->pages[i], 0);
517 : }
518 325 : }
519 :
520 324 : static void release_task_stack(struct task_struct *tsk)
521 : {
522 324 : if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
523 : return; /* Better to leak the stack than to free prematurely */
524 :
525 324 : free_thread_stack(tsk);
526 : }
527 :
528 : #ifdef CONFIG_THREAD_INFO_IN_TASK
529 : void put_task_stack(struct task_struct *tsk)
530 : {
531 : if (refcount_dec_and_test(&tsk->stack_refcount))
532 : release_task_stack(tsk);
533 : }
534 : #endif
535 :
536 324 : void free_task(struct task_struct *tsk)
537 : {
538 : #ifdef CONFIG_SECCOMP
539 324 : WARN_ON_ONCE(tsk->seccomp.filter);
540 : #endif
541 324 : release_user_cpus_ptr(tsk);
542 324 : scs_release(tsk);
543 :
544 : #ifndef CONFIG_THREAD_INFO_IN_TASK
545 : /*
546 : * The task is finally done with both the stack and thread_info,
547 : * so free both.
548 : */
549 324 : release_task_stack(tsk);
550 : #else
551 : /*
552 : * If the task had a separate stack allocation, it should be gone
553 : * by now.
554 : */
555 : WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
556 : #endif
557 324 : rt_mutex_debug_task_free(tsk);
558 324 : ftrace_graph_exit_task(tsk);
559 324 : arch_release_task_struct(tsk);
560 324 : if (tsk->flags & PF_KTHREAD)
561 324 : free_kthread_struct(tsk);
562 324 : free_task_struct(tsk);
563 324 : }
564 : EXPORT_SYMBOL(free_task);
565 :
566 0 : static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
567 : {
568 : struct file *exe_file;
569 :
570 0 : exe_file = get_mm_exe_file(oldmm);
571 0 : RCU_INIT_POINTER(mm->exe_file, exe_file);
572 : /*
573 : * We depend on the oldmm having properly denied write access to the
574 : * exe_file already.
575 : */
576 0 : if (exe_file && deny_write_access(exe_file))
577 0 : pr_warn_once("deny_write_access() failed in %s\n", __func__);
578 0 : }
579 :
580 : #ifdef CONFIG_MMU
581 0 : static __latent_entropy int dup_mmap(struct mm_struct *mm,
582 : struct mm_struct *oldmm)
583 : {
584 : struct vm_area_struct *mpnt, *tmp;
585 : int retval;
586 0 : unsigned long charge = 0;
587 0 : LIST_HEAD(uf);
588 0 : VMA_ITERATOR(old_vmi, oldmm, 0);
589 0 : VMA_ITERATOR(vmi, mm, 0);
590 :
591 0 : uprobe_start_dup_mmap();
592 0 : if (mmap_write_lock_killable(oldmm)) {
593 : retval = -EINTR;
594 : goto fail_uprobe_end;
595 : }
596 0 : flush_cache_dup_mm(oldmm);
597 0 : uprobe_dup_mmap(oldmm, mm);
598 : /*
599 : * Not linked in yet - no deadlock potential:
600 : */
601 0 : mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
602 :
603 : /* No ordering required: file already has been exposed. */
604 0 : dup_mm_exe_file(mm, oldmm);
605 :
606 0 : mm->total_vm = oldmm->total_vm;
607 0 : mm->data_vm = oldmm->data_vm;
608 0 : mm->exec_vm = oldmm->exec_vm;
609 0 : mm->stack_vm = oldmm->stack_vm;
610 :
611 0 : retval = ksm_fork(mm, oldmm);
612 : if (retval)
613 : goto out;
614 0 : khugepaged_fork(mm, oldmm);
615 :
616 0 : retval = vma_iter_bulk_alloc(&vmi, oldmm->map_count);
617 0 : if (retval)
618 : goto out;
619 :
620 0 : for_each_vma(old_vmi, mpnt) {
621 : struct file *file;
622 :
623 0 : if (mpnt->vm_flags & VM_DONTCOPY) {
624 0 : vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
625 0 : continue;
626 : }
627 0 : charge = 0;
628 : /*
629 : * Don't duplicate many vmas if we've been oom-killed (for
630 : * example)
631 : */
632 0 : if (fatal_signal_pending(current)) {
633 : retval = -EINTR;
634 : goto loop_out;
635 : }
636 0 : if (mpnt->vm_flags & VM_ACCOUNT) {
637 0 : unsigned long len = vma_pages(mpnt);
638 :
639 0 : if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
640 : goto fail_nomem;
641 : charge = len;
642 : }
643 0 : tmp = vm_area_dup(mpnt);
644 0 : if (!tmp)
645 : goto fail_nomem;
646 0 : retval = vma_dup_policy(mpnt, tmp);
647 : if (retval)
648 : goto fail_nomem_policy;
649 0 : tmp->vm_mm = mm;
650 0 : retval = dup_userfaultfd(tmp, &uf);
651 : if (retval)
652 : goto fail_nomem_anon_vma_fork;
653 0 : if (tmp->vm_flags & VM_WIPEONFORK) {
654 : /*
655 : * VM_WIPEONFORK gets a clean slate in the child.
656 : * Don't prepare anon_vma until fault since we don't
657 : * copy page for current vma.
658 : */
659 0 : tmp->anon_vma = NULL;
660 0 : } else if (anon_vma_fork(tmp, mpnt))
661 : goto fail_nomem_anon_vma_fork;
662 0 : vm_flags_clear(tmp, VM_LOCKED_MASK);
663 0 : file = tmp->vm_file;
664 0 : if (file) {
665 0 : struct address_space *mapping = file->f_mapping;
666 :
667 0 : get_file(file);
668 0 : i_mmap_lock_write(mapping);
669 0 : if (tmp->vm_flags & VM_SHARED)
670 : mapping_allow_writable(mapping);
671 0 : flush_dcache_mmap_lock(mapping);
672 : /* insert tmp into the share list, just after mpnt */
673 0 : vma_interval_tree_insert_after(tmp, mpnt,
674 : &mapping->i_mmap);
675 0 : flush_dcache_mmap_unlock(mapping);
676 : i_mmap_unlock_write(mapping);
677 : }
678 :
679 : /*
680 : * Copy/update hugetlb private vma information.
681 : */
682 0 : if (is_vm_hugetlb_page(tmp))
683 : hugetlb_dup_vma_private(tmp);
684 :
685 : /* Link the vma into the MT */
686 0 : if (vma_iter_bulk_store(&vmi, tmp))
687 : goto fail_nomem_vmi_store;
688 :
689 0 : mm->map_count++;
690 0 : if (!(tmp->vm_flags & VM_WIPEONFORK))
691 0 : retval = copy_page_range(tmp, mpnt);
692 :
693 0 : if (tmp->vm_ops && tmp->vm_ops->open)
694 0 : tmp->vm_ops->open(tmp);
695 :
696 0 : if (retval)
697 : goto loop_out;
698 : }
699 : /* a new mm has just been created */
700 : retval = arch_dup_mmap(oldmm, mm);
701 : loop_out:
702 : vma_iter_free(&vmi);
703 : out:
704 0 : mmap_write_unlock(mm);
705 0 : flush_tlb_mm(oldmm);
706 : mmap_write_unlock(oldmm);
707 : dup_userfaultfd_complete(&uf);
708 : fail_uprobe_end:
709 : uprobe_end_dup_mmap();
710 0 : return retval;
711 :
712 : fail_nomem_vmi_store:
713 0 : unlink_anon_vmas(tmp);
714 : fail_nomem_anon_vma_fork:
715 0 : mpol_put(vma_policy(tmp));
716 : fail_nomem_policy:
717 : vm_area_free(tmp);
718 : fail_nomem:
719 0 : retval = -ENOMEM;
720 0 : vm_unacct_memory(charge);
721 : goto loop_out;
722 : }
723 :
724 : static inline int mm_alloc_pgd(struct mm_struct *mm)
725 : {
726 0 : mm->pgd = pgd_alloc(mm);
727 0 : if (unlikely(!mm->pgd))
728 : return -ENOMEM;
729 : return 0;
730 : }
731 :
732 : static inline void mm_free_pgd(struct mm_struct *mm)
733 : {
734 0 : pgd_free(mm, mm->pgd);
735 : }
736 : #else
737 : static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
738 : {
739 : mmap_write_lock(oldmm);
740 : dup_mm_exe_file(mm, oldmm);
741 : mmap_write_unlock(oldmm);
742 : return 0;
743 : }
744 : #define mm_alloc_pgd(mm) (0)
745 : #define mm_free_pgd(mm)
746 : #endif /* CONFIG_MMU */
747 :
748 0 : static void check_mm(struct mm_struct *mm)
749 : {
750 : int i;
751 :
752 : BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
753 : "Please make sure 'struct resident_page_types[]' is updated as well");
754 :
755 0 : for (i = 0; i < NR_MM_COUNTERS; i++) {
756 0 : long x = percpu_counter_sum(&mm->rss_stat[i]);
757 :
758 0 : if (likely(!x))
759 0 : continue;
760 :
761 : /* Making sure this is not due to race with CPU offlining. */
762 0 : x = percpu_counter_sum_all(&mm->rss_stat[i]);
763 0 : if (unlikely(x))
764 0 : pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
765 : mm, resident_page_types[i], x);
766 : }
767 :
768 0 : if (mm_pgtables_bytes(mm))
769 0 : pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
770 : mm_pgtables_bytes(mm));
771 :
772 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
773 : VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
774 : #endif
775 0 : }
776 :
777 : #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
778 : #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
779 :
780 : /*
781 : * Called when the last reference to the mm
782 : * is dropped: either by a lazy thread or by
783 : * mmput. Free the page directory and the mm.
784 : */
785 0 : void __mmdrop(struct mm_struct *mm)
786 : {
787 : int i;
788 :
789 0 : BUG_ON(mm == &init_mm);
790 0 : WARN_ON_ONCE(mm == current->mm);
791 0 : WARN_ON_ONCE(mm == current->active_mm);
792 0 : mm_free_pgd(mm);
793 0 : destroy_context(mm);
794 0 : mmu_notifier_subscriptions_destroy(mm);
795 0 : check_mm(mm);
796 0 : put_user_ns(mm->user_ns);
797 0 : mm_pasid_drop(mm);
798 :
799 0 : for (i = 0; i < NR_MM_COUNTERS; i++)
800 : percpu_counter_destroy(&mm->rss_stat[i]);
801 0 : free_mm(mm);
802 0 : }
803 : EXPORT_SYMBOL_GPL(__mmdrop);
804 :
805 0 : static void mmdrop_async_fn(struct work_struct *work)
806 : {
807 : struct mm_struct *mm;
808 :
809 0 : mm = container_of(work, struct mm_struct, async_put_work);
810 0 : __mmdrop(mm);
811 0 : }
812 :
813 0 : static void mmdrop_async(struct mm_struct *mm)
814 : {
815 0 : if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
816 0 : INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
817 0 : schedule_work(&mm->async_put_work);
818 : }
819 0 : }
820 :
821 324 : static inline void free_signal_struct(struct signal_struct *sig)
822 : {
823 324 : taskstats_tgid_free(sig);
824 324 : sched_autogroup_exit(sig);
825 : /*
826 : * __mmdrop is not safe to call from softirq context on x86 due to
827 : * pgd_dtor so postpone it to the async context
828 : */
829 324 : if (sig->oom_mm)
830 0 : mmdrop_async(sig->oom_mm);
831 324 : kmem_cache_free(signal_cachep, sig);
832 324 : }
833 :
834 324 : static inline void put_signal_struct(struct signal_struct *sig)
835 : {
836 648 : if (refcount_dec_and_test(&sig->sigcnt))
837 324 : free_signal_struct(sig);
838 324 : }
839 :
840 324 : void __put_task_struct(struct task_struct *tsk)
841 : {
842 324 : WARN_ON(!tsk->exit_state);
843 648 : WARN_ON(refcount_read(&tsk->usage));
844 324 : WARN_ON(tsk == current);
845 :
846 324 : io_uring_free(tsk);
847 324 : cgroup_free(tsk);
848 324 : task_numa_free(tsk, true);
849 324 : security_task_free(tsk);
850 324 : bpf_task_storage_free(tsk);
851 324 : exit_creds(tsk);
852 324 : delayacct_tsk_free(tsk);
853 324 : put_signal_struct(tsk->signal);
854 324 : sched_core_free(tsk);
855 324 : free_task(tsk);
856 324 : }
857 : EXPORT_SYMBOL_GPL(__put_task_struct);
858 :
859 1 : void __init __weak arch_task_cache_init(void) { }
860 :
861 : /*
862 : * set_max_threads
863 : */
864 : static void set_max_threads(unsigned int max_threads_suggested)
865 : {
866 : u64 threads;
867 1 : unsigned long nr_pages = totalram_pages();
868 :
869 : /*
870 : * The number of threads shall be limited such that the thread
871 : * structures may only consume a small part of the available memory.
872 : */
873 2 : if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
874 : threads = MAX_THREADS;
875 : else
876 2 : threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
877 : (u64) THREAD_SIZE * 8UL);
878 :
879 1 : if (threads > max_threads_suggested)
880 0 : threads = max_threads_suggested;
881 :
882 1 : max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
883 : }
884 :
885 : #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
886 : /* Initialized by the architecture: */
887 : int arch_task_struct_size __read_mostly;
888 : #endif
889 :
890 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
891 : static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
892 : {
893 : /* Fetch thread_struct whitelist for the architecture. */
894 1 : arch_thread_struct_whitelist(offset, size);
895 :
896 : /*
897 : * Handle zero-sized whitelist or empty thread_struct, otherwise
898 : * adjust offset to position of thread_struct in task_struct.
899 : */
900 : if (unlikely(*size == 0))
901 : *offset = 0;
902 : else
903 1 : *offset += offsetof(struct task_struct, thread);
904 : }
905 : #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
906 :
907 1 : void __init fork_init(void)
908 : {
909 : int i;
910 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
911 : #ifndef ARCH_MIN_TASKALIGN
912 : #define ARCH_MIN_TASKALIGN 0
913 : #endif
914 1 : int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
915 : unsigned long useroffset, usersize;
916 :
917 : /* create a slab on which task_structs can be allocated */
918 1 : task_struct_whitelist(&useroffset, &usersize);
919 1 : task_struct_cachep = kmem_cache_create_usercopy("task_struct",
920 : arch_task_struct_size, align,
921 : SLAB_PANIC|SLAB_ACCOUNT,
922 : useroffset, usersize, NULL);
923 : #endif
924 :
925 : /* do the arch specific task caches init */
926 1 : arch_task_cache_init();
927 :
928 1 : set_max_threads(MAX_THREADS);
929 :
930 1 : init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
931 1 : init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
932 1 : init_task.signal->rlim[RLIMIT_SIGPENDING] =
933 : init_task.signal->rlim[RLIMIT_NPROC];
934 :
935 11 : for (i = 0; i < UCOUNT_COUNTS; i++)
936 10 : init_user_ns.ucount_max[i] = max_threads/2;
937 :
938 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
939 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
940 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
941 1 : set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
942 :
943 : #ifdef CONFIG_VMAP_STACK
944 1 : cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
945 : NULL, free_vm_stack_cache);
946 : #endif
947 :
948 : scs_init();
949 :
950 1 : lockdep_init_task(&init_task);
951 : uprobes_init();
952 1 : }
953 :
954 340 : int __weak arch_dup_task_struct(struct task_struct *dst,
955 : struct task_struct *src)
956 : {
957 340 : *dst = *src;
958 340 : return 0;
959 : }
960 :
961 1 : void set_task_stack_end_magic(struct task_struct *tsk)
962 : {
963 : unsigned long *stackend;
964 :
965 341 : stackend = end_of_stack(tsk);
966 341 : *stackend = STACK_END_MAGIC; /* for overflow detection */
967 1 : }
968 :
969 340 : static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
970 : {
971 : struct task_struct *tsk;
972 : int err;
973 :
974 340 : if (node == NUMA_NO_NODE)
975 340 : node = tsk_fork_get_node(orig);
976 340 : tsk = alloc_task_struct_node(node);
977 340 : if (!tsk)
978 : return NULL;
979 :
980 340 : err = arch_dup_task_struct(tsk, orig);
981 340 : if (err)
982 : goto free_tsk;
983 :
984 340 : err = alloc_thread_stack_node(tsk, node);
985 340 : if (err)
986 : goto free_tsk;
987 :
988 : #ifdef CONFIG_THREAD_INFO_IN_TASK
989 : refcount_set(&tsk->stack_refcount, 1);
990 : #endif
991 340 : account_kernel_stack(tsk, 1);
992 :
993 340 : err = scs_prepare(tsk, node);
994 : if (err)
995 : goto free_stack;
996 :
997 : #ifdef CONFIG_SECCOMP
998 : /*
999 : * We must handle setting up seccomp filters once we're under
1000 : * the sighand lock in case orig has changed between now and
1001 : * then. Until then, filter must be NULL to avoid messing up
1002 : * the usage counts on the error path calling free_task.
1003 : */
1004 340 : tsk->seccomp.filter = NULL;
1005 : #endif
1006 :
1007 680 : setup_thread_stack(tsk, orig);
1008 340 : clear_user_return_notifier(tsk);
1009 340 : clear_tsk_need_resched(tsk);
1010 340 : set_task_stack_end_magic(tsk);
1011 : clear_syscall_work_syscall_user_dispatch(tsk);
1012 :
1013 : #ifdef CONFIG_STACKPROTECTOR
1014 : tsk->stack_canary = get_random_canary();
1015 : #endif
1016 340 : if (orig->cpus_ptr == &orig->cpus_mask)
1017 340 : tsk->cpus_ptr = &tsk->cpus_mask;
1018 340 : dup_user_cpus_ptr(tsk, orig, node);
1019 :
1020 : /*
1021 : * One for the user space visible state that goes away when reaped.
1022 : * One for the scheduler.
1023 : */
1024 680 : refcount_set(&tsk->rcu_users, 2);
1025 : /* One for the rcu users */
1026 680 : refcount_set(&tsk->usage, 1);
1027 : #ifdef CONFIG_BLK_DEV_IO_TRACE
1028 : tsk->btrace_seq = 0;
1029 : #endif
1030 340 : tsk->splice_pipe = NULL;
1031 340 : tsk->task_frag.page = NULL;
1032 340 : tsk->wake_q.next = NULL;
1033 340 : tsk->worker_private = NULL;
1034 :
1035 : kcov_task_init(tsk);
1036 : kmsan_task_create(tsk);
1037 : kmap_local_fork(tsk);
1038 :
1039 : #ifdef CONFIG_FAULT_INJECTION
1040 : tsk->fail_nth = 0;
1041 : #endif
1042 :
1043 : #ifdef CONFIG_BLK_CGROUP
1044 : tsk->throttle_disk = NULL;
1045 : tsk->use_memdelay = 0;
1046 : #endif
1047 :
1048 : #ifdef CONFIG_IOMMU_SVA
1049 : tsk->pasid_activated = 0;
1050 : #endif
1051 :
1052 : #ifdef CONFIG_MEMCG
1053 : tsk->active_memcg = NULL;
1054 : #endif
1055 :
1056 : #ifdef CONFIG_CPU_SUP_INTEL
1057 340 : tsk->reported_split_lock = 0;
1058 : #endif
1059 :
1060 : #ifdef CONFIG_SCHED_MM_CID
1061 : tsk->mm_cid = -1;
1062 : tsk->mm_cid_active = 0;
1063 : #endif
1064 340 : return tsk;
1065 :
1066 : free_stack:
1067 : exit_task_stack_account(tsk);
1068 : free_thread_stack(tsk);
1069 : free_tsk:
1070 0 : free_task_struct(tsk);
1071 0 : return NULL;
1072 : }
1073 :
1074 : __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1075 :
1076 : static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1077 :
1078 0 : static int __init coredump_filter_setup(char *s)
1079 : {
1080 0 : default_dump_filter =
1081 0 : (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1082 : MMF_DUMP_FILTER_MASK;
1083 0 : return 1;
1084 : }
1085 :
1086 : __setup("coredump_filter=", coredump_filter_setup);
1087 :
1088 : #include <linux/init_task.h>
1089 :
1090 : static void mm_init_aio(struct mm_struct *mm)
1091 : {
1092 : #ifdef CONFIG_AIO
1093 0 : spin_lock_init(&mm->ioctx_lock);
1094 0 : mm->ioctx_table = NULL;
1095 : #endif
1096 : }
1097 :
1098 : static __always_inline void mm_clear_owner(struct mm_struct *mm,
1099 : struct task_struct *p)
1100 : {
1101 : #ifdef CONFIG_MEMCG
1102 : if (mm->owner == p)
1103 : WRITE_ONCE(mm->owner, NULL);
1104 : #endif
1105 : }
1106 :
1107 : static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1108 : {
1109 : #ifdef CONFIG_MEMCG
1110 : mm->owner = p;
1111 : #endif
1112 : }
1113 :
1114 : static void mm_init_uprobes_state(struct mm_struct *mm)
1115 : {
1116 : #ifdef CONFIG_UPROBES
1117 : mm->uprobes_state.xol_area = NULL;
1118 : #endif
1119 : }
1120 :
1121 0 : static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1122 : struct user_namespace *user_ns)
1123 : {
1124 : int i;
1125 :
1126 0 : mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
1127 : mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
1128 0 : atomic_set(&mm->mm_users, 1);
1129 0 : atomic_set(&mm->mm_count, 1);
1130 0 : seqcount_init(&mm->write_protect_seq);
1131 0 : mmap_init_lock(mm);
1132 0 : INIT_LIST_HEAD(&mm->mmlist);
1133 0 : mm_pgtables_bytes_init(mm);
1134 0 : mm->map_count = 0;
1135 0 : mm->locked_vm = 0;
1136 0 : atomic64_set(&mm->pinned_vm, 0);
1137 0 : memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1138 0 : spin_lock_init(&mm->page_table_lock);
1139 0 : spin_lock_init(&mm->arg_lock);
1140 0 : mm_init_cpumask(mm);
1141 0 : mm_init_aio(mm);
1142 0 : mm_init_owner(mm, p);
1143 0 : mm_pasid_init(mm);
1144 0 : RCU_INIT_POINTER(mm->exe_file, NULL);
1145 0 : mmu_notifier_subscriptions_init(mm);
1146 0 : init_tlb_flush_pending(mm);
1147 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1148 : mm->pmd_huge_pte = NULL;
1149 : #endif
1150 0 : mm_init_uprobes_state(mm);
1151 0 : hugetlb_count_init(mm);
1152 :
1153 0 : if (current->mm) {
1154 0 : mm->flags = current->mm->flags & MMF_INIT_MASK;
1155 0 : mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1156 : } else {
1157 0 : mm->flags = default_dump_filter;
1158 0 : mm->def_flags = 0;
1159 : }
1160 :
1161 0 : if (mm_alloc_pgd(mm))
1162 : goto fail_nopgd;
1163 :
1164 0 : if (init_new_context(p, mm))
1165 : goto fail_nocontext;
1166 :
1167 0 : for (i = 0; i < NR_MM_COUNTERS; i++)
1168 0 : if (percpu_counter_init(&mm->rss_stat[i], 0, GFP_KERNEL_ACCOUNT))
1169 : goto fail_pcpu;
1170 :
1171 0 : mm->user_ns = get_user_ns(user_ns);
1172 0 : lru_gen_init_mm(mm);
1173 0 : mm_init_cid(mm);
1174 : return mm;
1175 :
1176 : fail_pcpu:
1177 : while (i > 0)
1178 : percpu_counter_destroy(&mm->rss_stat[--i]);
1179 : fail_nocontext:
1180 : mm_free_pgd(mm);
1181 : fail_nopgd:
1182 0 : free_mm(mm);
1183 : return NULL;
1184 : }
1185 :
1186 : /*
1187 : * Allocate and initialize an mm_struct.
1188 : */
1189 0 : struct mm_struct *mm_alloc(void)
1190 : {
1191 : struct mm_struct *mm;
1192 :
1193 0 : mm = allocate_mm();
1194 0 : if (!mm)
1195 : return NULL;
1196 :
1197 0 : memset(mm, 0, sizeof(*mm));
1198 0 : return mm_init(mm, current, current_user_ns());
1199 : }
1200 :
1201 0 : static inline void __mmput(struct mm_struct *mm)
1202 : {
1203 : VM_BUG_ON(atomic_read(&mm->mm_users));
1204 :
1205 0 : uprobe_clear_state(mm);
1206 0 : exit_aio(mm);
1207 0 : ksm_exit(mm);
1208 0 : khugepaged_exit(mm); /* must run before exit_mmap */
1209 0 : exit_mmap(mm);
1210 0 : mm_put_huge_zero_page(mm);
1211 0 : set_mm_exe_file(mm, NULL);
1212 0 : if (!list_empty(&mm->mmlist)) {
1213 0 : spin_lock(&mmlist_lock);
1214 0 : list_del(&mm->mmlist);
1215 : spin_unlock(&mmlist_lock);
1216 : }
1217 0 : if (mm->binfmt)
1218 : module_put(mm->binfmt->module);
1219 0 : lru_gen_del_mm(mm);
1220 0 : mmdrop(mm);
1221 0 : }
1222 :
1223 : /*
1224 : * Decrement the use count and release all resources for an mm.
1225 : */
1226 0 : void mmput(struct mm_struct *mm)
1227 : {
1228 : might_sleep();
1229 :
1230 0 : if (atomic_dec_and_test(&mm->mm_users))
1231 0 : __mmput(mm);
1232 0 : }
1233 : EXPORT_SYMBOL_GPL(mmput);
1234 :
1235 : #ifdef CONFIG_MMU
1236 0 : static void mmput_async_fn(struct work_struct *work)
1237 : {
1238 0 : struct mm_struct *mm = container_of(work, struct mm_struct,
1239 : async_put_work);
1240 :
1241 0 : __mmput(mm);
1242 0 : }
1243 :
1244 0 : void mmput_async(struct mm_struct *mm)
1245 : {
1246 0 : if (atomic_dec_and_test(&mm->mm_users)) {
1247 0 : INIT_WORK(&mm->async_put_work, mmput_async_fn);
1248 0 : schedule_work(&mm->async_put_work);
1249 : }
1250 0 : }
1251 : EXPORT_SYMBOL_GPL(mmput_async);
1252 : #endif
1253 :
1254 : /**
1255 : * set_mm_exe_file - change a reference to the mm's executable file
1256 : *
1257 : * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1258 : *
1259 : * Main users are mmput() and sys_execve(). Callers prevent concurrent
1260 : * invocations: in mmput() nobody alive left, in execve task is single
1261 : * threaded.
1262 : *
1263 : * Can only fail if new_exe_file != NULL.
1264 : */
1265 0 : int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1266 : {
1267 : struct file *old_exe_file;
1268 :
1269 : /*
1270 : * It is safe to dereference the exe_file without RCU as
1271 : * this function is only called if nobody else can access
1272 : * this mm -- see comment above for justification.
1273 : */
1274 0 : old_exe_file = rcu_dereference_raw(mm->exe_file);
1275 :
1276 0 : if (new_exe_file) {
1277 : /*
1278 : * We expect the caller (i.e., sys_execve) to already denied
1279 : * write access, so this is unlikely to fail.
1280 : */
1281 0 : if (unlikely(deny_write_access(new_exe_file)))
1282 : return -EACCES;
1283 : get_file(new_exe_file);
1284 : }
1285 0 : rcu_assign_pointer(mm->exe_file, new_exe_file);
1286 0 : if (old_exe_file) {
1287 0 : allow_write_access(old_exe_file);
1288 0 : fput(old_exe_file);
1289 : }
1290 : return 0;
1291 : }
1292 :
1293 : /**
1294 : * replace_mm_exe_file - replace a reference to the mm's executable file
1295 : *
1296 : * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1297 : * dealing with concurrent invocation and without grabbing the mmap lock in
1298 : * write mode.
1299 : *
1300 : * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1301 : */
1302 0 : int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1303 : {
1304 : struct vm_area_struct *vma;
1305 : struct file *old_exe_file;
1306 0 : int ret = 0;
1307 :
1308 : /* Forbid mm->exe_file change if old file still mapped. */
1309 0 : old_exe_file = get_mm_exe_file(mm);
1310 0 : if (old_exe_file) {
1311 0 : VMA_ITERATOR(vmi, mm, 0);
1312 : mmap_read_lock(mm);
1313 0 : for_each_vma(vmi, vma) {
1314 0 : if (!vma->vm_file)
1315 0 : continue;
1316 0 : if (path_equal(&vma->vm_file->f_path,
1317 0 : &old_exe_file->f_path)) {
1318 : ret = -EBUSY;
1319 : break;
1320 : }
1321 : }
1322 0 : mmap_read_unlock(mm);
1323 0 : fput(old_exe_file);
1324 0 : if (ret)
1325 0 : return ret;
1326 : }
1327 :
1328 : /* set the new file, lockless */
1329 0 : ret = deny_write_access(new_exe_file);
1330 0 : if (ret)
1331 : return -EACCES;
1332 0 : get_file(new_exe_file);
1333 :
1334 0 : old_exe_file = xchg(&mm->exe_file, new_exe_file);
1335 0 : if (old_exe_file) {
1336 : /*
1337 : * Don't race with dup_mmap() getting the file and disallowing
1338 : * write access while someone might open the file writable.
1339 : */
1340 0 : mmap_read_lock(mm);
1341 0 : allow_write_access(old_exe_file);
1342 0 : fput(old_exe_file);
1343 : mmap_read_unlock(mm);
1344 : }
1345 : return 0;
1346 : }
1347 :
1348 : /**
1349 : * get_mm_exe_file - acquire a reference to the mm's executable file
1350 : *
1351 : * Returns %NULL if mm has no associated executable file.
1352 : * User must release file via fput().
1353 : */
1354 0 : struct file *get_mm_exe_file(struct mm_struct *mm)
1355 : {
1356 : struct file *exe_file;
1357 :
1358 : rcu_read_lock();
1359 0 : exe_file = rcu_dereference(mm->exe_file);
1360 0 : if (exe_file && !get_file_rcu(exe_file))
1361 0 : exe_file = NULL;
1362 : rcu_read_unlock();
1363 0 : return exe_file;
1364 : }
1365 :
1366 : /**
1367 : * get_task_exe_file - acquire a reference to the task's executable file
1368 : *
1369 : * Returns %NULL if task's mm (if any) has no associated executable file or
1370 : * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1371 : * User must release file via fput().
1372 : */
1373 0 : struct file *get_task_exe_file(struct task_struct *task)
1374 : {
1375 0 : struct file *exe_file = NULL;
1376 : struct mm_struct *mm;
1377 :
1378 0 : task_lock(task);
1379 0 : mm = task->mm;
1380 0 : if (mm) {
1381 0 : if (!(task->flags & PF_KTHREAD))
1382 0 : exe_file = get_mm_exe_file(mm);
1383 : }
1384 0 : task_unlock(task);
1385 0 : return exe_file;
1386 : }
1387 :
1388 : /**
1389 : * get_task_mm - acquire a reference to the task's mm
1390 : *
1391 : * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1392 : * this kernel workthread has transiently adopted a user mm with use_mm,
1393 : * to do its AIO) is not set and if so returns a reference to it, after
1394 : * bumping up the use count. User must release the mm via mmput()
1395 : * after use. Typically used by /proc and ptrace.
1396 : */
1397 0 : struct mm_struct *get_task_mm(struct task_struct *task)
1398 : {
1399 : struct mm_struct *mm;
1400 :
1401 0 : task_lock(task);
1402 0 : mm = task->mm;
1403 0 : if (mm) {
1404 0 : if (task->flags & PF_KTHREAD)
1405 : mm = NULL;
1406 : else
1407 : mmget(mm);
1408 : }
1409 0 : task_unlock(task);
1410 0 : return mm;
1411 : }
1412 : EXPORT_SYMBOL_GPL(get_task_mm);
1413 :
1414 0 : struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1415 : {
1416 : struct mm_struct *mm;
1417 : int err;
1418 :
1419 0 : err = down_read_killable(&task->signal->exec_update_lock);
1420 0 : if (err)
1421 0 : return ERR_PTR(err);
1422 :
1423 0 : mm = get_task_mm(task);
1424 0 : if (mm && mm != current->mm &&
1425 0 : !ptrace_may_access(task, mode)) {
1426 : mmput(mm);
1427 : mm = ERR_PTR(-EACCES);
1428 : }
1429 0 : up_read(&task->signal->exec_update_lock);
1430 :
1431 0 : return mm;
1432 : }
1433 :
1434 : static void complete_vfork_done(struct task_struct *tsk)
1435 : {
1436 : struct completion *vfork;
1437 :
1438 325 : task_lock(tsk);
1439 325 : vfork = tsk->vfork_done;
1440 325 : if (likely(vfork)) {
1441 325 : tsk->vfork_done = NULL;
1442 325 : complete(vfork);
1443 : }
1444 325 : task_unlock(tsk);
1445 : }
1446 :
1447 0 : static int wait_for_vfork_done(struct task_struct *child,
1448 : struct completion *vfork)
1449 : {
1450 0 : unsigned int state = TASK_UNINTERRUPTIBLE|TASK_KILLABLE|TASK_FREEZABLE;
1451 : int killed;
1452 :
1453 : cgroup_enter_frozen();
1454 0 : killed = wait_for_completion_state(vfork, state);
1455 0 : cgroup_leave_frozen(false);
1456 :
1457 0 : if (killed) {
1458 0 : task_lock(child);
1459 0 : child->vfork_done = NULL;
1460 0 : task_unlock(child);
1461 : }
1462 :
1463 0 : put_task_struct(child);
1464 0 : return killed;
1465 : }
1466 :
1467 : /* Please note the differences between mmput and mm_release.
1468 : * mmput is called whenever we stop holding onto a mm_struct,
1469 : * error success whatever.
1470 : *
1471 : * mm_release is called after a mm_struct has been removed
1472 : * from the current process.
1473 : *
1474 : * This difference is important for error handling, when we
1475 : * only half set up a mm_struct for a new process and need to restore
1476 : * the old one. Because we mmput the new mm_struct before
1477 : * restoring the old one. . .
1478 : * Eric Biederman 10 January 1998
1479 : */
1480 325 : static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1481 : {
1482 325 : uprobe_free_utask(tsk);
1483 :
1484 : /* Get rid of any cached register state */
1485 325 : deactivate_mm(tsk, mm);
1486 :
1487 : /*
1488 : * Signal userspace if we're not exiting with a core dump
1489 : * because we want to leave the value intact for debugging
1490 : * purposes.
1491 : */
1492 325 : if (tsk->clear_child_tid) {
1493 0 : if (atomic_read(&mm->mm_users) > 1) {
1494 : /*
1495 : * We don't check the error code - if userspace has
1496 : * not set up a proper pointer then tough luck.
1497 : */
1498 0 : put_user(0, tsk->clear_child_tid);
1499 0 : do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1500 : 1, NULL, NULL, 0, 0);
1501 : }
1502 0 : tsk->clear_child_tid = NULL;
1503 : }
1504 :
1505 : /*
1506 : * All done, finally we can wake up parent and return this mm to him.
1507 : * Also kthread_stop() uses this completion for synchronization.
1508 : */
1509 325 : if (tsk->vfork_done)
1510 325 : complete_vfork_done(tsk);
1511 325 : }
1512 :
1513 325 : void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1514 : {
1515 325 : futex_exit_release(tsk);
1516 325 : mm_release(tsk, mm);
1517 325 : }
1518 :
1519 0 : void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1520 : {
1521 0 : futex_exec_release(tsk);
1522 0 : mm_release(tsk, mm);
1523 0 : }
1524 :
1525 : /**
1526 : * dup_mm() - duplicates an existing mm structure
1527 : * @tsk: the task_struct with which the new mm will be associated.
1528 : * @oldmm: the mm to duplicate.
1529 : *
1530 : * Allocates a new mm structure and duplicates the provided @oldmm structure
1531 : * content into it.
1532 : *
1533 : * Return: the duplicated mm or NULL on failure.
1534 : */
1535 0 : static struct mm_struct *dup_mm(struct task_struct *tsk,
1536 : struct mm_struct *oldmm)
1537 : {
1538 : struct mm_struct *mm;
1539 : int err;
1540 :
1541 0 : mm = allocate_mm();
1542 0 : if (!mm)
1543 : goto fail_nomem;
1544 :
1545 0 : memcpy(mm, oldmm, sizeof(*mm));
1546 :
1547 0 : if (!mm_init(mm, tsk, mm->user_ns))
1548 : goto fail_nomem;
1549 :
1550 0 : err = dup_mmap(mm, oldmm);
1551 0 : if (err)
1552 : goto free_pt;
1553 :
1554 0 : mm->hiwater_rss = get_mm_rss(mm);
1555 0 : mm->hiwater_vm = mm->total_vm;
1556 :
1557 0 : if (mm->binfmt && !try_module_get(mm->binfmt->module))
1558 : goto free_pt;
1559 :
1560 : return mm;
1561 :
1562 : free_pt:
1563 : /* don't put binfmt in mmput, we haven't got module yet */
1564 0 : mm->binfmt = NULL;
1565 0 : mm_init_owner(mm, NULL);
1566 : mmput(mm);
1567 :
1568 : fail_nomem:
1569 : return NULL;
1570 : }
1571 :
1572 340 : static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1573 : {
1574 : struct mm_struct *mm, *oldmm;
1575 :
1576 340 : tsk->min_flt = tsk->maj_flt = 0;
1577 340 : tsk->nvcsw = tsk->nivcsw = 0;
1578 : #ifdef CONFIG_DETECT_HUNG_TASK
1579 : tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1580 : tsk->last_switch_time = 0;
1581 : #endif
1582 :
1583 340 : tsk->mm = NULL;
1584 340 : tsk->active_mm = NULL;
1585 :
1586 : /*
1587 : * Are we cloning a kernel thread?
1588 : *
1589 : * We need to steal a active VM for that..
1590 : */
1591 340 : oldmm = current->mm;
1592 340 : if (!oldmm)
1593 : return 0;
1594 :
1595 0 : if (clone_flags & CLONE_VM) {
1596 0 : mmget(oldmm);
1597 0 : mm = oldmm;
1598 : } else {
1599 0 : mm = dup_mm(tsk, current->mm);
1600 0 : if (!mm)
1601 : return -ENOMEM;
1602 : }
1603 :
1604 0 : tsk->mm = mm;
1605 0 : tsk->active_mm = mm;
1606 0 : sched_mm_cid_fork(tsk);
1607 0 : return 0;
1608 : }
1609 :
1610 340 : static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1611 : {
1612 340 : struct fs_struct *fs = current->fs;
1613 340 : if (clone_flags & CLONE_FS) {
1614 : /* tsk->fs is already what we want */
1615 680 : spin_lock(&fs->lock);
1616 340 : if (fs->in_exec) {
1617 0 : spin_unlock(&fs->lock);
1618 : return -EAGAIN;
1619 : }
1620 340 : fs->users++;
1621 680 : spin_unlock(&fs->lock);
1622 : return 0;
1623 : }
1624 0 : tsk->fs = copy_fs_struct(fs);
1625 0 : if (!tsk->fs)
1626 : return -ENOMEM;
1627 : return 0;
1628 : }
1629 :
1630 340 : static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1631 : {
1632 : struct files_struct *oldf, *newf;
1633 340 : int error = 0;
1634 :
1635 : /*
1636 : * A background process may not have any files ...
1637 : */
1638 340 : oldf = current->files;
1639 340 : if (!oldf)
1640 : goto out;
1641 :
1642 340 : if (clone_flags & CLONE_FILES) {
1643 339 : atomic_inc(&oldf->count);
1644 : goto out;
1645 : }
1646 :
1647 1 : newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1648 1 : if (!newf)
1649 : goto out;
1650 :
1651 1 : tsk->files = newf;
1652 1 : error = 0;
1653 : out:
1654 340 : return error;
1655 : }
1656 :
1657 340 : static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1658 : {
1659 : struct sighand_struct *sig;
1660 :
1661 340 : if (clone_flags & CLONE_SIGHAND) {
1662 0 : refcount_inc(¤t->sighand->count);
1663 0 : return 0;
1664 : }
1665 340 : sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1666 340 : RCU_INIT_POINTER(tsk->sighand, sig);
1667 340 : if (!sig)
1668 : return -ENOMEM;
1669 :
1670 680 : refcount_set(&sig->count, 1);
1671 680 : spin_lock_irq(¤t->sighand->siglock);
1672 340 : memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1673 680 : spin_unlock_irq(¤t->sighand->siglock);
1674 :
1675 : /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1676 340 : if (clone_flags & CLONE_CLEAR_SIGHAND)
1677 0 : flush_signal_handlers(tsk, 0);
1678 :
1679 : return 0;
1680 : }
1681 :
1682 325 : void __cleanup_sighand(struct sighand_struct *sighand)
1683 : {
1684 650 : if (refcount_dec_and_test(&sighand->count)) {
1685 325 : signalfd_cleanup(sighand);
1686 : /*
1687 : * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1688 : * without an RCU grace period, see __lock_task_sighand().
1689 : */
1690 325 : kmem_cache_free(sighand_cachep, sighand);
1691 : }
1692 325 : }
1693 :
1694 : /*
1695 : * Initialize POSIX timer handling for a thread group.
1696 : */
1697 : static void posix_cpu_timers_init_group(struct signal_struct *sig)
1698 : {
1699 340 : struct posix_cputimers *pct = &sig->posix_cputimers;
1700 : unsigned long cpu_limit;
1701 :
1702 340 : cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1703 340 : posix_cputimers_group_init(pct, cpu_limit);
1704 : }
1705 :
1706 340 : static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1707 : {
1708 : struct signal_struct *sig;
1709 :
1710 340 : if (clone_flags & CLONE_THREAD)
1711 : return 0;
1712 :
1713 680 : sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1714 340 : tsk->signal = sig;
1715 340 : if (!sig)
1716 : return -ENOMEM;
1717 :
1718 340 : sig->nr_threads = 1;
1719 340 : sig->quick_threads = 1;
1720 680 : atomic_set(&sig->live, 1);
1721 680 : refcount_set(&sig->sigcnt, 1);
1722 :
1723 : /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1724 340 : sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1725 340 : tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1726 :
1727 340 : init_waitqueue_head(&sig->wait_chldexit);
1728 340 : sig->curr_target = tsk;
1729 680 : init_sigpending(&sig->shared_pending);
1730 340 : INIT_HLIST_HEAD(&sig->multiprocess);
1731 680 : seqlock_init(&sig->stats_lock);
1732 680 : prev_cputime_init(&sig->prev_cputime);
1733 :
1734 : #ifdef CONFIG_POSIX_TIMERS
1735 680 : INIT_LIST_HEAD(&sig->posix_timers);
1736 340 : hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1737 340 : sig->real_timer.function = it_real_fn;
1738 : #endif
1739 :
1740 340 : task_lock(current->group_leader);
1741 340 : memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1742 680 : task_unlock(current->group_leader);
1743 :
1744 340 : posix_cpu_timers_init_group(sig);
1745 :
1746 : tty_audit_fork(sig);
1747 : sched_autogroup_fork(sig);
1748 :
1749 340 : sig->oom_score_adj = current->signal->oom_score_adj;
1750 340 : sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1751 :
1752 340 : mutex_init(&sig->cred_guard_mutex);
1753 340 : init_rwsem(&sig->exec_update_lock);
1754 :
1755 340 : return 0;
1756 : }
1757 :
1758 340 : static void copy_seccomp(struct task_struct *p)
1759 : {
1760 : #ifdef CONFIG_SECCOMP
1761 : /*
1762 : * Must be called with sighand->lock held, which is common to
1763 : * all threads in the group. Holding cred_guard_mutex is not
1764 : * needed because this new task is not yet running and cannot
1765 : * be racing exec.
1766 : */
1767 340 : assert_spin_locked(¤t->sighand->siglock);
1768 :
1769 : /* Ref-count the new filter user, and assign it. */
1770 340 : get_seccomp_filter(current);
1771 340 : p->seccomp = current->seccomp;
1772 :
1773 : /*
1774 : * Explicitly enable no_new_privs here in case it got set
1775 : * between the task_struct being duplicated and holding the
1776 : * sighand lock. The seccomp state and nnp must be in sync.
1777 : */
1778 680 : if (task_no_new_privs(current))
1779 : task_set_no_new_privs(p);
1780 :
1781 : /*
1782 : * If the parent gained a seccomp mode after copying thread
1783 : * flags and between before we held the sighand lock, we have
1784 : * to manually enable the seccomp thread flag here.
1785 : */
1786 340 : if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1787 0 : set_task_syscall_work(p, SECCOMP);
1788 : #endif
1789 340 : }
1790 :
1791 0 : SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1792 : {
1793 0 : current->clear_child_tid = tidptr;
1794 :
1795 0 : return task_pid_vnr(current);
1796 : }
1797 :
1798 : static void rt_mutex_init_task(struct task_struct *p)
1799 : {
1800 : raw_spin_lock_init(&p->pi_lock);
1801 : #ifdef CONFIG_RT_MUTEXES
1802 340 : p->pi_waiters = RB_ROOT_CACHED;
1803 340 : p->pi_top_task = NULL;
1804 340 : p->pi_blocked_on = NULL;
1805 : #endif
1806 : }
1807 :
1808 : static inline void init_task_pid_links(struct task_struct *task)
1809 : {
1810 : enum pid_type type;
1811 :
1812 1700 : for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1813 2720 : INIT_HLIST_NODE(&task->pid_links[type]);
1814 : }
1815 :
1816 : static inline void
1817 : init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1818 : {
1819 0 : if (type == PIDTYPE_PID)
1820 340 : task->thread_pid = pid;
1821 : else
1822 1020 : task->signal->pids[type] = pid;
1823 : }
1824 :
1825 : static inline void rcu_copy_process(struct task_struct *p)
1826 : {
1827 : #ifdef CONFIG_PREEMPT_RCU
1828 : p->rcu_read_lock_nesting = 0;
1829 : p->rcu_read_unlock_special.s = 0;
1830 : p->rcu_blocked_node = NULL;
1831 : INIT_LIST_HEAD(&p->rcu_node_entry);
1832 : #endif /* #ifdef CONFIG_PREEMPT_RCU */
1833 : #ifdef CONFIG_TASKS_RCU
1834 : p->rcu_tasks_holdout = false;
1835 : INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1836 : p->rcu_tasks_idle_cpu = -1;
1837 : #endif /* #ifdef CONFIG_TASKS_RCU */
1838 : #ifdef CONFIG_TASKS_TRACE_RCU
1839 : p->trc_reader_nesting = 0;
1840 : p->trc_reader_special.s = 0;
1841 : INIT_LIST_HEAD(&p->trc_holdout_list);
1842 : INIT_LIST_HEAD(&p->trc_blkd_node);
1843 : #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1844 : }
1845 :
1846 0 : struct pid *pidfd_pid(const struct file *file)
1847 : {
1848 0 : if (file->f_op == &pidfd_fops)
1849 0 : return file->private_data;
1850 :
1851 : return ERR_PTR(-EBADF);
1852 : }
1853 :
1854 0 : static int pidfd_release(struct inode *inode, struct file *file)
1855 : {
1856 0 : struct pid *pid = file->private_data;
1857 :
1858 0 : file->private_data = NULL;
1859 0 : put_pid(pid);
1860 0 : return 0;
1861 : }
1862 :
1863 : #ifdef CONFIG_PROC_FS
1864 : /**
1865 : * pidfd_show_fdinfo - print information about a pidfd
1866 : * @m: proc fdinfo file
1867 : * @f: file referencing a pidfd
1868 : *
1869 : * Pid:
1870 : * This function will print the pid that a given pidfd refers to in the
1871 : * pid namespace of the procfs instance.
1872 : * If the pid namespace of the process is not a descendant of the pid
1873 : * namespace of the procfs instance 0 will be shown as its pid. This is
1874 : * similar to calling getppid() on a process whose parent is outside of
1875 : * its pid namespace.
1876 : *
1877 : * NSpid:
1878 : * If pid namespaces are supported then this function will also print
1879 : * the pid of a given pidfd refers to for all descendant pid namespaces
1880 : * starting from the current pid namespace of the instance, i.e. the
1881 : * Pid field and the first entry in the NSpid field will be identical.
1882 : * If the pid namespace of the process is not a descendant of the pid
1883 : * namespace of the procfs instance 0 will be shown as its first NSpid
1884 : * entry and no others will be shown.
1885 : * Note that this differs from the Pid and NSpid fields in
1886 : * /proc/<pid>/status where Pid and NSpid are always shown relative to
1887 : * the pid namespace of the procfs instance. The difference becomes
1888 : * obvious when sending around a pidfd between pid namespaces from a
1889 : * different branch of the tree, i.e. where no ancestral relation is
1890 : * present between the pid namespaces:
1891 : * - create two new pid namespaces ns1 and ns2 in the initial pid
1892 : * namespace (also take care to create new mount namespaces in the
1893 : * new pid namespace and mount procfs)
1894 : * - create a process with a pidfd in ns1
1895 : * - send pidfd from ns1 to ns2
1896 : * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1897 : * have exactly one entry, which is 0
1898 : */
1899 0 : static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
1900 : {
1901 0 : struct pid *pid = f->private_data;
1902 : struct pid_namespace *ns;
1903 0 : pid_t nr = -1;
1904 :
1905 0 : if (likely(pid_has_task(pid, PIDTYPE_PID))) {
1906 0 : ns = proc_pid_ns(file_inode(m->file)->i_sb);
1907 0 : nr = pid_nr_ns(pid, ns);
1908 : }
1909 :
1910 0 : seq_put_decimal_ll(m, "Pid:\t", nr);
1911 :
1912 : #ifdef CONFIG_PID_NS
1913 0 : seq_put_decimal_ll(m, "\nNSpid:\t", nr);
1914 0 : if (nr > 0) {
1915 : int i;
1916 :
1917 : /* If nr is non-zero it means that 'pid' is valid and that
1918 : * ns, i.e. the pid namespace associated with the procfs
1919 : * instance, is in the pid namespace hierarchy of pid.
1920 : * Start at one below the already printed level.
1921 : */
1922 0 : for (i = ns->level + 1; i <= pid->level; i++)
1923 0 : seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
1924 : }
1925 : #endif
1926 0 : seq_putc(m, '\n');
1927 0 : }
1928 : #endif
1929 :
1930 : /*
1931 : * Poll support for process exit notification.
1932 : */
1933 0 : static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
1934 : {
1935 0 : struct pid *pid = file->private_data;
1936 0 : __poll_t poll_flags = 0;
1937 :
1938 0 : poll_wait(file, &pid->wait_pidfd, pts);
1939 :
1940 : /*
1941 : * Inform pollers only when the whole thread group exits.
1942 : * If the thread group leader exits before all other threads in the
1943 : * group, then poll(2) should block, similar to the wait(2) family.
1944 : */
1945 0 : if (thread_group_exited(pid))
1946 0 : poll_flags = EPOLLIN | EPOLLRDNORM;
1947 :
1948 0 : return poll_flags;
1949 : }
1950 :
1951 : const struct file_operations pidfd_fops = {
1952 : .release = pidfd_release,
1953 : .poll = pidfd_poll,
1954 : #ifdef CONFIG_PROC_FS
1955 : .show_fdinfo = pidfd_show_fdinfo,
1956 : #endif
1957 : };
1958 :
1959 : static void __delayed_free_task(struct rcu_head *rhp)
1960 : {
1961 : struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1962 :
1963 : free_task(tsk);
1964 : }
1965 :
1966 : static __always_inline void delayed_free_task(struct task_struct *tsk)
1967 : {
1968 : if (IS_ENABLED(CONFIG_MEMCG))
1969 : call_rcu(&tsk->rcu, __delayed_free_task);
1970 : else
1971 0 : free_task(tsk);
1972 : }
1973 :
1974 340 : static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1975 : {
1976 : /* Skip if kernel thread */
1977 340 : if (!tsk->mm)
1978 : return;
1979 :
1980 : /* Skip if spawning a thread or using vfork */
1981 0 : if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1982 : return;
1983 :
1984 : /* We need to synchronize with __set_oom_adj */
1985 0 : mutex_lock(&oom_adj_mutex);
1986 0 : set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1987 : /* Update the values in case they were changed after copy_signal */
1988 0 : tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1989 0 : tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1990 0 : mutex_unlock(&oom_adj_mutex);
1991 : }
1992 :
1993 : #ifdef CONFIG_RV
1994 : static void rv_task_fork(struct task_struct *p)
1995 : {
1996 : int i;
1997 :
1998 : for (i = 0; i < RV_PER_TASK_MONITORS; i++)
1999 : p->rv[i].da_mon.monitoring = false;
2000 : }
2001 : #else
2002 : #define rv_task_fork(p) do {} while (0)
2003 : #endif
2004 :
2005 : /*
2006 : * This creates a new process as a copy of the old one,
2007 : * but does not actually start it yet.
2008 : *
2009 : * It copies the registers, and all the appropriate
2010 : * parts of the process environment (as per the clone
2011 : * flags). The actual kick-off is left to the caller.
2012 : */
2013 340 : static __latent_entropy struct task_struct *copy_process(
2014 : struct pid *pid,
2015 : int trace,
2016 : int node,
2017 : struct kernel_clone_args *args)
2018 : {
2019 340 : int pidfd = -1, retval;
2020 : struct task_struct *p;
2021 : struct multiprocess_signals delayed;
2022 340 : struct file *pidfile = NULL;
2023 340 : const u64 clone_flags = args->flags;
2024 340 : struct nsproxy *nsp = current->nsproxy;
2025 :
2026 : /*
2027 : * Don't allow sharing the root directory with processes in a different
2028 : * namespace
2029 : */
2030 340 : if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
2031 : return ERR_PTR(-EINVAL);
2032 :
2033 340 : if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
2034 : return ERR_PTR(-EINVAL);
2035 :
2036 : /*
2037 : * Thread groups must share signals as well, and detached threads
2038 : * can only be started up within the thread group.
2039 : */
2040 340 : if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2041 : return ERR_PTR(-EINVAL);
2042 :
2043 : /*
2044 : * Shared signal handlers imply shared VM. By way of the above,
2045 : * thread groups also imply shared VM. Blocking this case allows
2046 : * for various simplifications in other code.
2047 : */
2048 340 : if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2049 : return ERR_PTR(-EINVAL);
2050 :
2051 : /*
2052 : * Siblings of global init remain as zombies on exit since they are
2053 : * not reaped by their parent (swapper). To solve this and to avoid
2054 : * multi-rooted process trees, prevent global and container-inits
2055 : * from creating siblings.
2056 : */
2057 340 : if ((clone_flags & CLONE_PARENT) &&
2058 0 : current->signal->flags & SIGNAL_UNKILLABLE)
2059 : return ERR_PTR(-EINVAL);
2060 :
2061 : /*
2062 : * If the new process will be in a different pid or user namespace
2063 : * do not allow it to share a thread group with the forking task.
2064 : */
2065 340 : if (clone_flags & CLONE_THREAD) {
2066 0 : if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2067 0 : (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2068 : return ERR_PTR(-EINVAL);
2069 : }
2070 :
2071 340 : if (clone_flags & CLONE_PIDFD) {
2072 : /*
2073 : * - CLONE_DETACHED is blocked so that we can potentially
2074 : * reuse it later for CLONE_PIDFD.
2075 : * - CLONE_THREAD is blocked until someone really needs it.
2076 : */
2077 0 : if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
2078 : return ERR_PTR(-EINVAL);
2079 : }
2080 :
2081 : /*
2082 : * Force any signals received before this point to be delivered
2083 : * before the fork happens. Collect up signals sent to multiple
2084 : * processes that happen during the fork and delay them so that
2085 : * they appear to happen after the fork.
2086 : */
2087 340 : sigemptyset(&delayed.signal);
2088 340 : INIT_HLIST_NODE(&delayed.node);
2089 :
2090 680 : spin_lock_irq(¤t->sighand->siglock);
2091 340 : if (!(clone_flags & CLONE_THREAD))
2092 340 : hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2093 340 : recalc_sigpending();
2094 680 : spin_unlock_irq(¤t->sighand->siglock);
2095 340 : retval = -ERESTARTNOINTR;
2096 680 : if (task_sigpending(current))
2097 : goto fork_out;
2098 :
2099 340 : retval = -ENOMEM;
2100 340 : p = dup_task_struct(current, node);
2101 340 : if (!p)
2102 : goto fork_out;
2103 340 : p->flags &= ~PF_KTHREAD;
2104 340 : if (args->kthread)
2105 339 : p->flags |= PF_KTHREAD;
2106 340 : if (args->io_thread) {
2107 : /*
2108 : * Mark us an IO worker, and block any signal that isn't
2109 : * fatal or STOP
2110 : */
2111 0 : p->flags |= PF_IO_WORKER;
2112 0 : siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2113 : }
2114 :
2115 340 : p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2116 : /*
2117 : * Clear TID on mm_release()?
2118 : */
2119 340 : p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2120 :
2121 340 : ftrace_graph_init_task(p);
2122 :
2123 340 : rt_mutex_init_task(p);
2124 :
2125 : lockdep_assert_irqs_enabled();
2126 : #ifdef CONFIG_PROVE_LOCKING
2127 : DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2128 : #endif
2129 340 : retval = copy_creds(p, clone_flags);
2130 340 : if (retval < 0)
2131 : goto bad_fork_free;
2132 :
2133 340 : retval = -EAGAIN;
2134 1020 : if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2135 0 : if (p->real_cred->user != INIT_USER &&
2136 0 : !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2137 : goto bad_fork_cleanup_count;
2138 : }
2139 340 : current->flags &= ~PF_NPROC_EXCEEDED;
2140 :
2141 : /*
2142 : * If multiple threads are within copy_process(), then this check
2143 : * triggers too late. This doesn't hurt, the check is only there
2144 : * to stop root fork bombs.
2145 : */
2146 340 : retval = -EAGAIN;
2147 340 : if (data_race(nr_threads >= max_threads))
2148 : goto bad_fork_cleanup_count;
2149 :
2150 340 : delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2151 340 : p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2152 340 : p->flags |= PF_FORKNOEXEC;
2153 680 : INIT_LIST_HEAD(&p->children);
2154 680 : INIT_LIST_HEAD(&p->sibling);
2155 340 : rcu_copy_process(p);
2156 340 : p->vfork_done = NULL;
2157 340 : spin_lock_init(&p->alloc_lock);
2158 :
2159 680 : init_sigpending(&p->pending);
2160 :
2161 340 : p->utime = p->stime = p->gtime = 0;
2162 : #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2163 : p->utimescaled = p->stimescaled = 0;
2164 : #endif
2165 680 : prev_cputime_init(&p->prev_cputime);
2166 :
2167 : #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2168 : seqcount_init(&p->vtime.seqcount);
2169 : p->vtime.starttime = 0;
2170 : p->vtime.state = VTIME_INACTIVE;
2171 : #endif
2172 :
2173 : #ifdef CONFIG_IO_URING
2174 340 : p->io_uring = NULL;
2175 : #endif
2176 :
2177 : #if defined(SPLIT_RSS_COUNTING)
2178 : memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2179 : #endif
2180 :
2181 340 : p->default_timer_slack_ns = current->timer_slack_ns;
2182 :
2183 : #ifdef CONFIG_PSI
2184 : p->psi_flags = 0;
2185 : #endif
2186 :
2187 340 : task_io_accounting_init(&p->ioac);
2188 340 : acct_clear_integrals(p);
2189 :
2190 680 : posix_cputimers_init(&p->posix_cputimers);
2191 :
2192 340 : p->io_context = NULL;
2193 340 : audit_set_context(p, NULL);
2194 340 : cgroup_fork(p);
2195 340 : if (args->kthread) {
2196 339 : if (!set_kthread_struct(p))
2197 : goto bad_fork_cleanup_delayacct;
2198 : }
2199 : #ifdef CONFIG_NUMA
2200 : p->mempolicy = mpol_dup(p->mempolicy);
2201 : if (IS_ERR(p->mempolicy)) {
2202 : retval = PTR_ERR(p->mempolicy);
2203 : p->mempolicy = NULL;
2204 : goto bad_fork_cleanup_delayacct;
2205 : }
2206 : #endif
2207 : #ifdef CONFIG_CPUSETS
2208 : p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2209 : p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2210 : seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2211 : #endif
2212 : #ifdef CONFIG_TRACE_IRQFLAGS
2213 : memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2214 : p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2215 : p->irqtrace.softirq_enable_ip = _THIS_IP_;
2216 : p->softirqs_enabled = 1;
2217 : p->softirq_context = 0;
2218 : #endif
2219 :
2220 340 : p->pagefault_disabled = 0;
2221 :
2222 : #ifdef CONFIG_LOCKDEP
2223 : lockdep_init_task(p);
2224 : #endif
2225 :
2226 : #ifdef CONFIG_DEBUG_MUTEXES
2227 : p->blocked_on = NULL; /* not blocked yet */
2228 : #endif
2229 : #ifdef CONFIG_BCACHE
2230 : p->sequential_io = 0;
2231 : p->sequential_io_avg = 0;
2232 : #endif
2233 : #ifdef CONFIG_BPF_SYSCALL
2234 : RCU_INIT_POINTER(p->bpf_storage, NULL);
2235 : p->bpf_ctx = NULL;
2236 : #endif
2237 :
2238 : /* Perform scheduler related setup. Assign this task to a CPU. */
2239 340 : retval = sched_fork(clone_flags, p);
2240 340 : if (retval)
2241 : goto bad_fork_cleanup_policy;
2242 :
2243 340 : retval = perf_event_init_task(p, clone_flags);
2244 : if (retval)
2245 : goto bad_fork_cleanup_policy;
2246 340 : retval = audit_alloc(p);
2247 : if (retval)
2248 : goto bad_fork_cleanup_perf;
2249 : /* copy all the process information */
2250 340 : shm_init_task(p);
2251 340 : retval = security_task_alloc(p, clone_flags);
2252 : if (retval)
2253 : goto bad_fork_cleanup_audit;
2254 340 : retval = copy_semundo(clone_flags, p);
2255 : if (retval)
2256 : goto bad_fork_cleanup_security;
2257 340 : retval = copy_files(clone_flags, p);
2258 340 : if (retval)
2259 : goto bad_fork_cleanup_semundo;
2260 340 : retval = copy_fs(clone_flags, p);
2261 340 : if (retval)
2262 : goto bad_fork_cleanup_files;
2263 340 : retval = copy_sighand(clone_flags, p);
2264 340 : if (retval)
2265 : goto bad_fork_cleanup_fs;
2266 340 : retval = copy_signal(clone_flags, p);
2267 340 : if (retval)
2268 : goto bad_fork_cleanup_sighand;
2269 340 : retval = copy_mm(clone_flags, p);
2270 340 : if (retval)
2271 : goto bad_fork_cleanup_signal;
2272 340 : retval = copy_namespaces(clone_flags, p);
2273 340 : if (retval)
2274 : goto bad_fork_cleanup_mm;
2275 340 : retval = copy_io(clone_flags, p);
2276 340 : if (retval)
2277 : goto bad_fork_cleanup_namespaces;
2278 340 : retval = copy_thread(p, args);
2279 340 : if (retval)
2280 : goto bad_fork_cleanup_io;
2281 :
2282 340 : stackleak_task_init(p);
2283 :
2284 340 : if (pid != &init_struct_pid) {
2285 340 : pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2286 : args->set_tid_size);
2287 340 : if (IS_ERR(pid)) {
2288 0 : retval = PTR_ERR(pid);
2289 0 : goto bad_fork_cleanup_thread;
2290 : }
2291 : }
2292 :
2293 : /*
2294 : * This has to happen after we've potentially unshared the file
2295 : * descriptor table (so that the pidfd doesn't leak into the child
2296 : * if the fd table isn't shared).
2297 : */
2298 340 : if (clone_flags & CLONE_PIDFD) {
2299 0 : retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2300 0 : if (retval < 0)
2301 : goto bad_fork_free_pid;
2302 :
2303 0 : pidfd = retval;
2304 :
2305 0 : pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2306 : O_RDWR | O_CLOEXEC);
2307 0 : if (IS_ERR(pidfile)) {
2308 0 : put_unused_fd(pidfd);
2309 0 : retval = PTR_ERR(pidfile);
2310 0 : goto bad_fork_free_pid;
2311 : }
2312 0 : get_pid(pid); /* held by pidfile now */
2313 :
2314 0 : retval = put_user(pidfd, args->pidfd);
2315 0 : if (retval)
2316 : goto bad_fork_put_pidfd;
2317 : }
2318 :
2319 : #ifdef CONFIG_BLOCK
2320 340 : p->plug = NULL;
2321 : #endif
2322 340 : futex_init_task(p);
2323 :
2324 : /*
2325 : * sigaltstack should be cleared when sharing the same VM
2326 : */
2327 340 : if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2328 : sas_ss_reset(p);
2329 :
2330 : /*
2331 : * Syscall tracing and stepping should be turned off in the
2332 : * child regardless of CLONE_PTRACE.
2333 : */
2334 340 : user_disable_single_step(p);
2335 680 : clear_task_syscall_work(p, SYSCALL_TRACE);
2336 : #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2337 : clear_task_syscall_work(p, SYSCALL_EMU);
2338 : #endif
2339 340 : clear_tsk_latency_tracing(p);
2340 :
2341 : /* ok, now we should be set up.. */
2342 340 : p->pid = pid_nr(pid);
2343 340 : if (clone_flags & CLONE_THREAD) {
2344 0 : p->group_leader = current->group_leader;
2345 0 : p->tgid = current->tgid;
2346 : } else {
2347 340 : p->group_leader = p;
2348 340 : p->tgid = p->pid;
2349 : }
2350 :
2351 340 : p->nr_dirtied = 0;
2352 340 : p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2353 340 : p->dirty_paused_when = 0;
2354 :
2355 340 : p->pdeath_signal = 0;
2356 680 : INIT_LIST_HEAD(&p->thread_group);
2357 340 : p->task_works = NULL;
2358 340 : clear_posix_cputimers_work(p);
2359 :
2360 : #ifdef CONFIG_KRETPROBES
2361 : p->kretprobe_instances.first = NULL;
2362 : #endif
2363 : #ifdef CONFIG_RETHOOK
2364 : p->rethooks.first = NULL;
2365 : #endif
2366 :
2367 : /*
2368 : * Ensure that the cgroup subsystem policies allow the new process to be
2369 : * forked. It should be noted that the new process's css_set can be changed
2370 : * between here and cgroup_post_fork() if an organisation operation is in
2371 : * progress.
2372 : */
2373 340 : retval = cgroup_can_fork(p, args);
2374 : if (retval)
2375 : goto bad_fork_put_pidfd;
2376 :
2377 : /*
2378 : * Now that the cgroups are pinned, re-clone the parent cgroup and put
2379 : * the new task on the correct runqueue. All this *before* the task
2380 : * becomes visible.
2381 : *
2382 : * This isn't part of ->can_fork() because while the re-cloning is
2383 : * cgroup specific, it unconditionally needs to place the task on a
2384 : * runqueue.
2385 : */
2386 340 : sched_cgroup_fork(p, args);
2387 :
2388 : /*
2389 : * From this point on we must avoid any synchronous user-space
2390 : * communication until we take the tasklist-lock. In particular, we do
2391 : * not want user-space to be able to predict the process start-time by
2392 : * stalling fork(2) after we recorded the start_time but before it is
2393 : * visible to the system.
2394 : */
2395 :
2396 340 : p->start_time = ktime_get_ns();
2397 340 : p->start_boottime = ktime_get_boottime_ns();
2398 :
2399 : /*
2400 : * Make it visible to the rest of the system, but dont wake it up yet.
2401 : * Need tasklist lock for parent etc handling!
2402 : */
2403 340 : write_lock_irq(&tasklist_lock);
2404 :
2405 : /* CLONE_PARENT re-uses the old parent */
2406 340 : if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2407 0 : p->real_parent = current->real_parent;
2408 0 : p->parent_exec_id = current->parent_exec_id;
2409 0 : if (clone_flags & CLONE_THREAD)
2410 0 : p->exit_signal = -1;
2411 : else
2412 0 : p->exit_signal = current->group_leader->exit_signal;
2413 : } else {
2414 340 : p->real_parent = current;
2415 340 : p->parent_exec_id = current->self_exec_id;
2416 340 : p->exit_signal = args->exit_signal;
2417 : }
2418 :
2419 340 : klp_copy_process(p);
2420 :
2421 340 : sched_core_fork(p);
2422 :
2423 680 : spin_lock(¤t->sighand->siglock);
2424 :
2425 : rv_task_fork(p);
2426 :
2427 340 : rseq_fork(p, clone_flags);
2428 :
2429 : /* Don't start children in a dying pid namespace */
2430 340 : if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2431 : retval = -ENOMEM;
2432 : goto bad_fork_cancel_cgroup;
2433 : }
2434 :
2435 : /* Let kill terminate clone/fork in the middle */
2436 340 : if (fatal_signal_pending(current)) {
2437 : retval = -EINTR;
2438 : goto bad_fork_cancel_cgroup;
2439 : }
2440 :
2441 : /* No more failure paths after this point. */
2442 :
2443 : /*
2444 : * Copy seccomp details explicitly here, in case they were changed
2445 : * before holding sighand lock.
2446 : */
2447 340 : copy_seccomp(p);
2448 :
2449 340 : init_task_pid_links(p);
2450 340 : if (likely(p->pid)) {
2451 340 : ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2452 :
2453 680 : init_task_pid(p, PIDTYPE_PID, pid);
2454 340 : if (thread_group_leader(p)) {
2455 680 : init_task_pid(p, PIDTYPE_TGID, pid);
2456 1020 : init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2457 1020 : init_task_pid(p, PIDTYPE_SID, task_session(current));
2458 :
2459 340 : if (is_child_reaper(pid)) {
2460 1 : ns_of_pid(pid)->child_reaper = p;
2461 1 : p->signal->flags |= SIGNAL_UNKILLABLE;
2462 : }
2463 340 : p->signal->shared_pending.signal = delayed.signal;
2464 1020 : p->signal->tty = tty_kref_get(current->signal->tty);
2465 : /*
2466 : * Inherit has_child_subreaper flag under the same
2467 : * tasklist_lock with adding child to the process tree
2468 : * for propagate_has_child_subreaper optimization.
2469 : */
2470 340 : p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2471 : p->real_parent->signal->is_child_subreaper;
2472 680 : list_add_tail(&p->sibling, &p->real_parent->children);
2473 680 : list_add_tail_rcu(&p->tasks, &init_task.tasks);
2474 340 : attach_pid(p, PIDTYPE_TGID);
2475 340 : attach_pid(p, PIDTYPE_PGID);
2476 340 : attach_pid(p, PIDTYPE_SID);
2477 340 : __this_cpu_inc(process_counts);
2478 : } else {
2479 0 : current->signal->nr_threads++;
2480 0 : current->signal->quick_threads++;
2481 0 : atomic_inc(¤t->signal->live);
2482 0 : refcount_inc(¤t->signal->sigcnt);
2483 0 : task_join_group_stop(p);
2484 0 : list_add_tail_rcu(&p->thread_group,
2485 0 : &p->group_leader->thread_group);
2486 0 : list_add_tail_rcu(&p->thread_node,
2487 0 : &p->signal->thread_head);
2488 : }
2489 340 : attach_pid(p, PIDTYPE_PID);
2490 340 : nr_threads++;
2491 : }
2492 340 : total_forks++;
2493 340 : hlist_del_init(&delayed.node);
2494 680 : spin_unlock(¤t->sighand->siglock);
2495 340 : syscall_tracepoint_update(p);
2496 340 : write_unlock_irq(&tasklist_lock);
2497 :
2498 340 : if (pidfile)
2499 0 : fd_install(pidfd, pidfile);
2500 :
2501 340 : proc_fork_connector(p);
2502 340 : sched_post_fork(p);
2503 340 : cgroup_post_fork(p, args);
2504 340 : perf_event_fork(p);
2505 :
2506 340 : trace_task_newtask(p, clone_flags);
2507 340 : uprobe_copy_process(p, clone_flags);
2508 :
2509 340 : copy_oom_score_adj(clone_flags, p);
2510 :
2511 340 : return p;
2512 :
2513 : bad_fork_cancel_cgroup:
2514 0 : sched_core_free(p);
2515 0 : spin_unlock(¤t->sighand->siglock);
2516 0 : write_unlock_irq(&tasklist_lock);
2517 0 : cgroup_cancel_fork(p, args);
2518 : bad_fork_put_pidfd:
2519 0 : if (clone_flags & CLONE_PIDFD) {
2520 0 : fput(pidfile);
2521 0 : put_unused_fd(pidfd);
2522 : }
2523 : bad_fork_free_pid:
2524 0 : if (pid != &init_struct_pid)
2525 0 : free_pid(pid);
2526 : bad_fork_cleanup_thread:
2527 : exit_thread(p);
2528 : bad_fork_cleanup_io:
2529 0 : if (p->io_context)
2530 0 : exit_io_context(p);
2531 : bad_fork_cleanup_namespaces:
2532 0 : exit_task_namespaces(p);
2533 : bad_fork_cleanup_mm:
2534 0 : if (p->mm) {
2535 0 : mm_clear_owner(p->mm, p);
2536 0 : mmput(p->mm);
2537 : }
2538 : bad_fork_cleanup_signal:
2539 0 : if (!(clone_flags & CLONE_THREAD))
2540 0 : free_signal_struct(p->signal);
2541 : bad_fork_cleanup_sighand:
2542 0 : __cleanup_sighand(p->sighand);
2543 : bad_fork_cleanup_fs:
2544 0 : exit_fs(p); /* blocking */
2545 : bad_fork_cleanup_files:
2546 0 : exit_files(p); /* blocking */
2547 : bad_fork_cleanup_semundo:
2548 : exit_sem(p);
2549 : bad_fork_cleanup_security:
2550 : security_task_free(p);
2551 : bad_fork_cleanup_audit:
2552 : audit_free(p);
2553 : bad_fork_cleanup_perf:
2554 : perf_event_free_task(p);
2555 : bad_fork_cleanup_policy:
2556 : lockdep_free_task(p);
2557 : #ifdef CONFIG_NUMA
2558 : mpol_put(p->mempolicy);
2559 : #endif
2560 : bad_fork_cleanup_delayacct:
2561 : delayacct_tsk_free(p);
2562 : bad_fork_cleanup_count:
2563 0 : dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2564 0 : exit_creds(p);
2565 : bad_fork_free:
2566 0 : WRITE_ONCE(p->__state, TASK_DEAD);
2567 0 : exit_task_stack_account(p);
2568 0 : put_task_stack(p);
2569 : delayed_free_task(p);
2570 : fork_out:
2571 0 : spin_lock_irq(¤t->sighand->siglock);
2572 0 : hlist_del_init(&delayed.node);
2573 0 : spin_unlock_irq(¤t->sighand->siglock);
2574 0 : return ERR_PTR(retval);
2575 : }
2576 :
2577 : static inline void init_idle_pids(struct task_struct *idle)
2578 : {
2579 : enum pid_type type;
2580 :
2581 0 : for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2582 0 : INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2583 0 : init_task_pid(idle, type, &init_struct_pid);
2584 : }
2585 : }
2586 :
2587 0 : static int idle_dummy(void *dummy)
2588 : {
2589 : /* This function is never called */
2590 0 : return 0;
2591 : }
2592 :
2593 0 : struct task_struct * __init fork_idle(int cpu)
2594 : {
2595 : struct task_struct *task;
2596 0 : struct kernel_clone_args args = {
2597 : .flags = CLONE_VM,
2598 : .fn = &idle_dummy,
2599 : .fn_arg = NULL,
2600 : .kthread = 1,
2601 : .idle = 1,
2602 : };
2603 :
2604 0 : task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2605 0 : if (!IS_ERR(task)) {
2606 0 : init_idle_pids(task);
2607 0 : init_idle(task, cpu);
2608 : }
2609 :
2610 0 : return task;
2611 : }
2612 :
2613 : /*
2614 : * This is like kernel_clone(), but shaved down and tailored to just
2615 : * creating io_uring workers. It returns a created task, or an error pointer.
2616 : * The returned task is inactive, and the caller must fire it up through
2617 : * wake_up_new_task(p). All signals are blocked in the created task.
2618 : */
2619 0 : struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2620 : {
2621 0 : unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2622 : CLONE_IO;
2623 0 : struct kernel_clone_args args = {
2624 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2625 : CLONE_UNTRACED) & ~CSIGNAL),
2626 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2627 : .fn = fn,
2628 : .fn_arg = arg,
2629 : .io_thread = 1,
2630 : };
2631 :
2632 0 : return copy_process(NULL, 0, node, &args);
2633 : }
2634 :
2635 : /*
2636 : * Ok, this is the main fork-routine.
2637 : *
2638 : * It copies the process, and if successful kick-starts
2639 : * it and waits for it to finish using the VM if required.
2640 : *
2641 : * args->exit_signal is expected to be checked for sanity by the caller.
2642 : */
2643 340 : pid_t kernel_clone(struct kernel_clone_args *args)
2644 : {
2645 340 : u64 clone_flags = args->flags;
2646 : struct completion vfork;
2647 : struct pid *pid;
2648 : struct task_struct *p;
2649 340 : int trace = 0;
2650 : pid_t nr;
2651 :
2652 : /*
2653 : * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2654 : * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2655 : * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2656 : * field in struct clone_args and it still doesn't make sense to have
2657 : * them both point at the same memory location. Performing this check
2658 : * here has the advantage that we don't need to have a separate helper
2659 : * to check for legacy clone().
2660 : */
2661 340 : if ((args->flags & CLONE_PIDFD) &&
2662 0 : (args->flags & CLONE_PARENT_SETTID) &&
2663 0 : (args->pidfd == args->parent_tid))
2664 : return -EINVAL;
2665 :
2666 : /*
2667 : * Determine whether and which event to report to ptracer. When
2668 : * called from kernel_thread or CLONE_UNTRACED is explicitly
2669 : * requested, no event is reported; otherwise, report if the event
2670 : * for the type of forking is enabled.
2671 : */
2672 340 : if (!(clone_flags & CLONE_UNTRACED)) {
2673 0 : if (clone_flags & CLONE_VFORK)
2674 : trace = PTRACE_EVENT_VFORK;
2675 0 : else if (args->exit_signal != SIGCHLD)
2676 : trace = PTRACE_EVENT_CLONE;
2677 : else
2678 0 : trace = PTRACE_EVENT_FORK;
2679 :
2680 0 : if (likely(!ptrace_event_enabled(current, trace)))
2681 0 : trace = 0;
2682 : }
2683 :
2684 340 : p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2685 340 : add_latent_entropy();
2686 :
2687 340 : if (IS_ERR(p))
2688 0 : return PTR_ERR(p);
2689 :
2690 : /*
2691 : * Do this prior waking up the new thread - the thread pointer
2692 : * might get invalid after that point, if the thread exits quickly.
2693 : */
2694 340 : trace_sched_process_fork(current, p);
2695 :
2696 340 : pid = get_task_pid(p, PIDTYPE_PID);
2697 340 : nr = pid_vnr(pid);
2698 :
2699 340 : if (clone_flags & CLONE_PARENT_SETTID)
2700 0 : put_user(nr, args->parent_tid);
2701 :
2702 340 : if (clone_flags & CLONE_VFORK) {
2703 0 : p->vfork_done = &vfork;
2704 0 : init_completion(&vfork);
2705 : get_task_struct(p);
2706 : }
2707 :
2708 : if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) {
2709 : /* lock the task to synchronize with memcg migration */
2710 : task_lock(p);
2711 : lru_gen_add_mm(p->mm);
2712 : task_unlock(p);
2713 : }
2714 :
2715 340 : wake_up_new_task(p);
2716 :
2717 : /* forking complete and child started to run, tell ptracer */
2718 340 : if (unlikely(trace))
2719 0 : ptrace_event_pid(trace, pid);
2720 :
2721 340 : if (clone_flags & CLONE_VFORK) {
2722 0 : if (!wait_for_vfork_done(p, &vfork))
2723 0 : ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2724 : }
2725 :
2726 340 : put_pid(pid);
2727 340 : return nr;
2728 : }
2729 :
2730 : /*
2731 : * Create a kernel thread.
2732 : */
2733 339 : pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2734 : {
2735 1017 : struct kernel_clone_args args = {
2736 339 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2737 339 : CLONE_UNTRACED) & ~CSIGNAL),
2738 339 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2739 : .fn = fn,
2740 : .fn_arg = arg,
2741 : .kthread = 1,
2742 : };
2743 :
2744 339 : return kernel_clone(&args);
2745 : }
2746 :
2747 : /*
2748 : * Create a user mode thread.
2749 : */
2750 1 : pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
2751 : {
2752 3 : struct kernel_clone_args args = {
2753 1 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2754 1 : CLONE_UNTRACED) & ~CSIGNAL),
2755 1 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2756 : .fn = fn,
2757 : .fn_arg = arg,
2758 : };
2759 :
2760 1 : return kernel_clone(&args);
2761 : }
2762 :
2763 : #ifdef __ARCH_WANT_SYS_FORK
2764 0 : SYSCALL_DEFINE0(fork)
2765 : {
2766 : #ifdef CONFIG_MMU
2767 0 : struct kernel_clone_args args = {
2768 : .exit_signal = SIGCHLD,
2769 : };
2770 :
2771 0 : return kernel_clone(&args);
2772 : #else
2773 : /* can not support in nommu mode */
2774 : return -EINVAL;
2775 : #endif
2776 : }
2777 : #endif
2778 :
2779 : #ifdef __ARCH_WANT_SYS_VFORK
2780 0 : SYSCALL_DEFINE0(vfork)
2781 : {
2782 0 : struct kernel_clone_args args = {
2783 : .flags = CLONE_VFORK | CLONE_VM,
2784 : .exit_signal = SIGCHLD,
2785 : };
2786 :
2787 0 : return kernel_clone(&args);
2788 : }
2789 : #endif
2790 :
2791 : #ifdef __ARCH_WANT_SYS_CLONE
2792 : #ifdef CONFIG_CLONE_BACKWARDS
2793 : SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2794 : int __user *, parent_tidptr,
2795 : unsigned long, tls,
2796 : int __user *, child_tidptr)
2797 : #elif defined(CONFIG_CLONE_BACKWARDS2)
2798 : SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2799 : int __user *, parent_tidptr,
2800 : int __user *, child_tidptr,
2801 : unsigned long, tls)
2802 : #elif defined(CONFIG_CLONE_BACKWARDS3)
2803 : SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2804 : int, stack_size,
2805 : int __user *, parent_tidptr,
2806 : int __user *, child_tidptr,
2807 : unsigned long, tls)
2808 : #else
2809 0 : SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2810 : int __user *, parent_tidptr,
2811 : int __user *, child_tidptr,
2812 : unsigned long, tls)
2813 : #endif
2814 : {
2815 0 : struct kernel_clone_args args = {
2816 0 : .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2817 : .pidfd = parent_tidptr,
2818 : .child_tid = child_tidptr,
2819 : .parent_tid = parent_tidptr,
2820 0 : .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2821 : .stack = newsp,
2822 : .tls = tls,
2823 : };
2824 :
2825 0 : return kernel_clone(&args);
2826 : }
2827 : #endif
2828 :
2829 : #ifdef __ARCH_WANT_SYS_CLONE3
2830 :
2831 0 : noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2832 : struct clone_args __user *uargs,
2833 : size_t usize)
2834 : {
2835 : int err;
2836 : struct clone_args args;
2837 0 : pid_t *kset_tid = kargs->set_tid;
2838 :
2839 : BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2840 : CLONE_ARGS_SIZE_VER0);
2841 : BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2842 : CLONE_ARGS_SIZE_VER1);
2843 : BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2844 : CLONE_ARGS_SIZE_VER2);
2845 : BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2846 :
2847 0 : if (unlikely(usize > PAGE_SIZE))
2848 : return -E2BIG;
2849 0 : if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2850 : return -EINVAL;
2851 :
2852 0 : err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2853 0 : if (err)
2854 : return err;
2855 :
2856 0 : if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2857 : return -EINVAL;
2858 :
2859 0 : if (unlikely(!args.set_tid && args.set_tid_size > 0))
2860 : return -EINVAL;
2861 :
2862 0 : if (unlikely(args.set_tid && args.set_tid_size == 0))
2863 : return -EINVAL;
2864 :
2865 : /*
2866 : * Verify that higher 32bits of exit_signal are unset and that
2867 : * it is a valid signal
2868 : */
2869 0 : if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2870 : !valid_signal(args.exit_signal)))
2871 : return -EINVAL;
2872 :
2873 0 : if ((args.flags & CLONE_INTO_CGROUP) &&
2874 0 : (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2875 : return -EINVAL;
2876 :
2877 0 : *kargs = (struct kernel_clone_args){
2878 : .flags = args.flags,
2879 0 : .pidfd = u64_to_user_ptr(args.pidfd),
2880 0 : .child_tid = u64_to_user_ptr(args.child_tid),
2881 0 : .parent_tid = u64_to_user_ptr(args.parent_tid),
2882 : .exit_signal = args.exit_signal,
2883 0 : .stack = args.stack,
2884 0 : .stack_size = args.stack_size,
2885 0 : .tls = args.tls,
2886 : .set_tid_size = args.set_tid_size,
2887 0 : .cgroup = args.cgroup,
2888 : };
2889 :
2890 0 : if (args.set_tid &&
2891 0 : copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
2892 : (kargs->set_tid_size * sizeof(pid_t))))
2893 : return -EFAULT;
2894 :
2895 0 : kargs->set_tid = kset_tid;
2896 :
2897 0 : return 0;
2898 : }
2899 :
2900 : /**
2901 : * clone3_stack_valid - check and prepare stack
2902 : * @kargs: kernel clone args
2903 : *
2904 : * Verify that the stack arguments userspace gave us are sane.
2905 : * In addition, set the stack direction for userspace since it's easy for us to
2906 : * determine.
2907 : */
2908 0 : static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
2909 : {
2910 0 : if (kargs->stack == 0) {
2911 0 : if (kargs->stack_size > 0)
2912 : return false;
2913 : } else {
2914 0 : if (kargs->stack_size == 0)
2915 : return false;
2916 :
2917 0 : if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
2918 : return false;
2919 :
2920 : #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2921 0 : kargs->stack += kargs->stack_size;
2922 : #endif
2923 : }
2924 :
2925 : return true;
2926 : }
2927 :
2928 0 : static bool clone3_args_valid(struct kernel_clone_args *kargs)
2929 : {
2930 : /* Verify that no unknown flags are passed along. */
2931 0 : if (kargs->flags &
2932 : ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
2933 : return false;
2934 :
2935 : /*
2936 : * - make the CLONE_DETACHED bit reusable for clone3
2937 : * - make the CSIGNAL bits reusable for clone3
2938 : */
2939 0 : if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
2940 : return false;
2941 :
2942 0 : if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
2943 : (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
2944 : return false;
2945 :
2946 0 : if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
2947 0 : kargs->exit_signal)
2948 : return false;
2949 :
2950 0 : if (!clone3_stack_valid(kargs))
2951 : return false;
2952 :
2953 0 : return true;
2954 : }
2955 :
2956 : /**
2957 : * clone3 - create a new process with specific properties
2958 : * @uargs: argument structure
2959 : * @size: size of @uargs
2960 : *
2961 : * clone3() is the extensible successor to clone()/clone2().
2962 : * It takes a struct as argument that is versioned by its size.
2963 : *
2964 : * Return: On success, a positive PID for the child process.
2965 : * On error, a negative errno number.
2966 : */
2967 0 : SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
2968 : {
2969 : int err;
2970 :
2971 : struct kernel_clone_args kargs;
2972 : pid_t set_tid[MAX_PID_NS_LEVEL];
2973 :
2974 0 : kargs.set_tid = set_tid;
2975 :
2976 0 : err = copy_clone_args_from_user(&kargs, uargs, size);
2977 0 : if (err)
2978 0 : return err;
2979 :
2980 0 : if (!clone3_args_valid(&kargs))
2981 : return -EINVAL;
2982 :
2983 0 : return kernel_clone(&kargs);
2984 : }
2985 : #endif
2986 :
2987 0 : void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2988 : {
2989 : struct task_struct *leader, *parent, *child;
2990 : int res;
2991 :
2992 0 : read_lock(&tasklist_lock);
2993 0 : leader = top = top->group_leader;
2994 : down:
2995 0 : for_each_thread(leader, parent) {
2996 0 : list_for_each_entry(child, &parent->children, sibling) {
2997 0 : res = visitor(child, data);
2998 0 : if (res) {
2999 0 : if (res < 0)
3000 : goto out;
3001 : leader = child;
3002 : goto down;
3003 : }
3004 : up:
3005 : ;
3006 : }
3007 : }
3008 :
3009 0 : if (leader != top) {
3010 0 : child = leader;
3011 0 : parent = child->real_parent;
3012 0 : leader = parent->group_leader;
3013 0 : goto up;
3014 : }
3015 : out:
3016 0 : read_unlock(&tasklist_lock);
3017 0 : }
3018 :
3019 : #ifndef ARCH_MIN_MMSTRUCT_ALIGN
3020 : #define ARCH_MIN_MMSTRUCT_ALIGN 0
3021 : #endif
3022 :
3023 30 : static void sighand_ctor(void *data)
3024 : {
3025 30 : struct sighand_struct *sighand = data;
3026 :
3027 30 : spin_lock_init(&sighand->siglock);
3028 30 : init_waitqueue_head(&sighand->signalfd_wqh);
3029 30 : }
3030 :
3031 1 : void __init mm_cache_init(void)
3032 : {
3033 : unsigned int mm_size;
3034 :
3035 : /*
3036 : * The mm_cpumask is located at the end of mm_struct, and is
3037 : * dynamically sized based on the maximum CPU number this system
3038 : * can have, taking hotplug into account (nr_cpu_ids).
3039 : */
3040 1 : mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size();
3041 :
3042 1 : mm_cachep = kmem_cache_create_usercopy("mm_struct",
3043 : mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
3044 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3045 : offsetof(struct mm_struct, saved_auxv),
3046 : sizeof_field(struct mm_struct, saved_auxv),
3047 : NULL);
3048 1 : }
3049 :
3050 1 : void __init proc_caches_init(void)
3051 : {
3052 1 : sighand_cachep = kmem_cache_create("sighand_cache",
3053 : sizeof(struct sighand_struct), 0,
3054 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
3055 : SLAB_ACCOUNT, sighand_ctor);
3056 1 : signal_cachep = kmem_cache_create("signal_cache",
3057 : sizeof(struct signal_struct), 0,
3058 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3059 : NULL);
3060 1 : files_cachep = kmem_cache_create("files_cache",
3061 : sizeof(struct files_struct), 0,
3062 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3063 : NULL);
3064 1 : fs_cachep = kmem_cache_create("fs_cache",
3065 : sizeof(struct fs_struct), 0,
3066 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3067 : NULL);
3068 :
3069 1 : vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
3070 1 : mmap_init();
3071 1 : nsproxy_cache_init();
3072 1 : }
3073 :
3074 : /*
3075 : * Check constraints on flags passed to the unshare system call.
3076 : */
3077 0 : static int check_unshare_flags(unsigned long unshare_flags)
3078 : {
3079 0 : if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3080 : CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3081 : CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3082 : CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3083 : CLONE_NEWTIME))
3084 : return -EINVAL;
3085 : /*
3086 : * Not implemented, but pretend it works if there is nothing
3087 : * to unshare. Note that unsharing the address space or the
3088 : * signal handlers also need to unshare the signal queues (aka
3089 : * CLONE_THREAD).
3090 : */
3091 0 : if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3092 0 : if (!thread_group_empty(current))
3093 : return -EINVAL;
3094 : }
3095 0 : if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3096 0 : if (refcount_read(¤t->sighand->count) > 1)
3097 : return -EINVAL;
3098 : }
3099 0 : if (unshare_flags & CLONE_VM) {
3100 0 : if (!current_is_single_threaded())
3101 : return -EINVAL;
3102 : }
3103 :
3104 : return 0;
3105 : }
3106 :
3107 : /*
3108 : * Unshare the filesystem structure if it is being shared
3109 : */
3110 0 : static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3111 : {
3112 0 : struct fs_struct *fs = current->fs;
3113 :
3114 0 : if (!(unshare_flags & CLONE_FS) || !fs)
3115 : return 0;
3116 :
3117 : /* don't need lock here; in the worst case we'll do useless copy */
3118 0 : if (fs->users == 1)
3119 : return 0;
3120 :
3121 0 : *new_fsp = copy_fs_struct(fs);
3122 0 : if (!*new_fsp)
3123 : return -ENOMEM;
3124 :
3125 0 : return 0;
3126 : }
3127 :
3128 : /*
3129 : * Unshare file descriptor table if it is being shared
3130 : */
3131 0 : int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3132 : struct files_struct **new_fdp)
3133 : {
3134 0 : struct files_struct *fd = current->files;
3135 0 : int error = 0;
3136 :
3137 0 : if ((unshare_flags & CLONE_FILES) &&
3138 0 : (fd && atomic_read(&fd->count) > 1)) {
3139 0 : *new_fdp = dup_fd(fd, max_fds, &error);
3140 0 : if (!*new_fdp)
3141 0 : return error;
3142 : }
3143 :
3144 : return 0;
3145 : }
3146 :
3147 : /*
3148 : * unshare allows a process to 'unshare' part of the process
3149 : * context which was originally shared using clone. copy_*
3150 : * functions used by kernel_clone() cannot be used here directly
3151 : * because they modify an inactive task_struct that is being
3152 : * constructed. Here we are modifying the current, active,
3153 : * task_struct.
3154 : */
3155 0 : int ksys_unshare(unsigned long unshare_flags)
3156 : {
3157 0 : struct fs_struct *fs, *new_fs = NULL;
3158 0 : struct files_struct *new_fd = NULL;
3159 0 : struct cred *new_cred = NULL;
3160 0 : struct nsproxy *new_nsproxy = NULL;
3161 0 : int do_sysvsem = 0;
3162 : int err;
3163 :
3164 : /*
3165 : * If unsharing a user namespace must also unshare the thread group
3166 : * and unshare the filesystem root and working directories.
3167 : */
3168 0 : if (unshare_flags & CLONE_NEWUSER)
3169 0 : unshare_flags |= CLONE_THREAD | CLONE_FS;
3170 : /*
3171 : * If unsharing vm, must also unshare signal handlers.
3172 : */
3173 0 : if (unshare_flags & CLONE_VM)
3174 0 : unshare_flags |= CLONE_SIGHAND;
3175 : /*
3176 : * If unsharing a signal handlers, must also unshare the signal queues.
3177 : */
3178 0 : if (unshare_flags & CLONE_SIGHAND)
3179 0 : unshare_flags |= CLONE_THREAD;
3180 : /*
3181 : * If unsharing namespace, must also unshare filesystem information.
3182 : */
3183 0 : if (unshare_flags & CLONE_NEWNS)
3184 0 : unshare_flags |= CLONE_FS;
3185 :
3186 0 : err = check_unshare_flags(unshare_flags);
3187 0 : if (err)
3188 : goto bad_unshare_out;
3189 : /*
3190 : * CLONE_NEWIPC must also detach from the undolist: after switching
3191 : * to a new ipc namespace, the semaphore arrays from the old
3192 : * namespace are unreachable.
3193 : */
3194 0 : if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3195 0 : do_sysvsem = 1;
3196 0 : err = unshare_fs(unshare_flags, &new_fs);
3197 0 : if (err)
3198 : goto bad_unshare_out;
3199 0 : err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3200 0 : if (err)
3201 : goto bad_unshare_cleanup_fs;
3202 0 : err = unshare_userns(unshare_flags, &new_cred);
3203 0 : if (err)
3204 : goto bad_unshare_cleanup_fd;
3205 0 : err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3206 : new_cred, new_fs);
3207 0 : if (err)
3208 : goto bad_unshare_cleanup_cred;
3209 :
3210 : if (new_cred) {
3211 : err = set_cred_ucounts(new_cred);
3212 : if (err)
3213 : goto bad_unshare_cleanup_cred;
3214 : }
3215 :
3216 0 : if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3217 0 : if (do_sysvsem) {
3218 : /*
3219 : * CLONE_SYSVSEM is equivalent to sys_exit().
3220 : */
3221 0 : exit_sem(current);
3222 : }
3223 0 : if (unshare_flags & CLONE_NEWIPC) {
3224 : /* Orphan segments in old ns (see sem above). */
3225 0 : exit_shm(current);
3226 0 : shm_init_task(current);
3227 : }
3228 :
3229 0 : if (new_nsproxy)
3230 0 : switch_task_namespaces(current, new_nsproxy);
3231 :
3232 0 : task_lock(current);
3233 :
3234 0 : if (new_fs) {
3235 0 : fs = current->fs;
3236 0 : spin_lock(&fs->lock);
3237 0 : current->fs = new_fs;
3238 0 : if (--fs->users)
3239 0 : new_fs = NULL;
3240 : else
3241 0 : new_fs = fs;
3242 0 : spin_unlock(&fs->lock);
3243 : }
3244 :
3245 0 : if (new_fd)
3246 0 : swap(current->files, new_fd);
3247 :
3248 0 : task_unlock(current);
3249 :
3250 : if (new_cred) {
3251 : /* Install the new user namespace */
3252 : commit_creds(new_cred);
3253 : new_cred = NULL;
3254 : }
3255 : }
3256 :
3257 0 : perf_event_namespaces(current);
3258 :
3259 : bad_unshare_cleanup_cred:
3260 : if (new_cred)
3261 : put_cred(new_cred);
3262 : bad_unshare_cleanup_fd:
3263 0 : if (new_fd)
3264 0 : put_files_struct(new_fd);
3265 :
3266 : bad_unshare_cleanup_fs:
3267 0 : if (new_fs)
3268 0 : free_fs_struct(new_fs);
3269 :
3270 : bad_unshare_out:
3271 0 : return err;
3272 : }
3273 :
3274 0 : SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3275 : {
3276 0 : return ksys_unshare(unshare_flags);
3277 : }
3278 :
3279 : /*
3280 : * Helper to unshare the files of the current task.
3281 : * We don't want to expose copy_files internals to
3282 : * the exec layer of the kernel.
3283 : */
3284 :
3285 0 : int unshare_files(void)
3286 : {
3287 0 : struct task_struct *task = current;
3288 0 : struct files_struct *old, *copy = NULL;
3289 : int error;
3290 :
3291 0 : error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3292 0 : if (error || !copy)
3293 : return error;
3294 :
3295 0 : old = task->files;
3296 0 : task_lock(task);
3297 0 : task->files = copy;
3298 0 : task_unlock(task);
3299 0 : put_files_struct(old);
3300 0 : return 0;
3301 : }
3302 :
3303 0 : int sysctl_max_threads(struct ctl_table *table, int write,
3304 : void *buffer, size_t *lenp, loff_t *ppos)
3305 : {
3306 : struct ctl_table t;
3307 : int ret;
3308 0 : int threads = max_threads;
3309 0 : int min = 1;
3310 0 : int max = MAX_THREADS;
3311 :
3312 0 : t = *table;
3313 0 : t.data = &threads;
3314 0 : t.extra1 = &min;
3315 0 : t.extra2 = &max;
3316 :
3317 0 : ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3318 0 : if (ret || !write)
3319 : return ret;
3320 :
3321 0 : max_threads = threads;
3322 :
3323 0 : return 0;
3324 : }
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