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/binfmts.h>
41 : #include <linux/mman.h>
42 : #include <linux/mmu_notifier.h>
43 : #include <linux/fs.h>
44 : #include <linux/mm.h>
45 : #include <linux/mm_inline.h>
46 : #include <linux/vmacache.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/random.h>
79 : #include <linux/tty.h>
80 : #include <linux/fs_struct.h>
81 : #include <linux/magic.h>
82 : #include <linux/perf_event.h>
83 : #include <linux/posix-timers.h>
84 : #include <linux/user-return-notifier.h>
85 : #include <linux/oom.h>
86 : #include <linux/khugepaged.h>
87 : #include <linux/signalfd.h>
88 : #include <linux/uprobes.h>
89 : #include <linux/aio.h>
90 : #include <linux/compiler.h>
91 : #include <linux/sysctl.h>
92 : #include <linux/kcov.h>
93 : #include <linux/livepatch.h>
94 : #include <linux/thread_info.h>
95 : #include <linux/stackleak.h>
96 : #include <linux/kasan.h>
97 : #include <linux/scs.h>
98 : #include <linux/io_uring.h>
99 : #include <linux/bpf.h>
100 : #include <linux/sched/mm.h>
101 :
102 : #include <asm/pgalloc.h>
103 : #include <linux/uaccess.h>
104 : #include <asm/mmu_context.h>
105 : #include <asm/cacheflush.h>
106 : #include <asm/tlbflush.h>
107 :
108 : #include <trace/events/sched.h>
109 :
110 : #define CREATE_TRACE_POINTS
111 : #include <trace/events/task.h>
112 :
113 : /*
114 : * Minimum number of threads to boot the kernel
115 : */
116 : #define MIN_THREADS 20
117 :
118 : /*
119 : * Maximum number of threads
120 : */
121 : #define MAX_THREADS FUTEX_TID_MASK
122 :
123 : /*
124 : * Protected counters by write_lock_irq(&tasklist_lock)
125 : */
126 : unsigned long total_forks; /* Handle normal Linux uptimes. */
127 : int nr_threads; /* The idle threads do not count.. */
128 :
129 : static int max_threads; /* tunable limit on nr_threads */
130 :
131 : #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
132 :
133 : static const char * const resident_page_types[] = {
134 : NAMED_ARRAY_INDEX(MM_FILEPAGES),
135 : NAMED_ARRAY_INDEX(MM_ANONPAGES),
136 : NAMED_ARRAY_INDEX(MM_SWAPENTS),
137 : NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
138 : };
139 :
140 : DEFINE_PER_CPU(unsigned long, process_counts) = 0;
141 :
142 : __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
143 :
144 : #ifdef CONFIG_PROVE_RCU
145 : int lockdep_tasklist_lock_is_held(void)
146 : {
147 : return lockdep_is_held(&tasklist_lock);
148 : }
149 : EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
150 : #endif /* #ifdef CONFIG_PROVE_RCU */
151 :
152 0 : int nr_processes(void)
153 : {
154 : int cpu;
155 0 : int total = 0;
156 :
157 0 : for_each_possible_cpu(cpu)
158 0 : total += per_cpu(process_counts, cpu);
159 :
160 0 : return total;
161 : }
162 :
163 92 : void __weak arch_release_task_struct(struct task_struct *tsk)
164 : {
165 92 : }
166 :
167 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
168 : static struct kmem_cache *task_struct_cachep;
169 :
170 : static inline struct task_struct *alloc_task_struct_node(int node)
171 : {
172 214 : return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
173 : }
174 :
175 : static inline void free_task_struct(struct task_struct *tsk)
176 : {
177 92 : kmem_cache_free(task_struct_cachep, tsk);
178 : }
179 : #endif
180 :
181 : #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
182 :
183 : /*
184 : * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
185 : * kmemcache based allocator.
186 : */
187 : # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
188 :
189 : # ifdef CONFIG_VMAP_STACK
190 : /*
191 : * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
192 : * flush. Try to minimize the number of calls by caching stacks.
193 : */
194 : #define NR_CACHED_STACKS 2
195 : static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
196 :
197 : struct vm_stack {
198 : struct rcu_head rcu;
199 : struct vm_struct *stack_vm_area;
200 : };
201 :
202 92 : static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
203 : {
204 : unsigned int i;
205 :
206 92 : for (i = 0; i < NR_CACHED_STACKS; i++) {
207 276 : if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
208 0 : continue;
209 : return true;
210 : }
211 : return false;
212 : }
213 :
214 0 : static void thread_stack_free_rcu(struct rcu_head *rh)
215 : {
216 0 : struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
217 :
218 0 : if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
219 : return;
220 :
221 0 : vfree(vm_stack);
222 : }
223 :
224 : static void thread_stack_delayed_free(struct task_struct *tsk)
225 : {
226 0 : struct vm_stack *vm_stack = tsk->stack;
227 :
228 0 : vm_stack->stack_vm_area = tsk->stack_vm_area;
229 0 : call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
230 : }
231 :
232 0 : static int free_vm_stack_cache(unsigned int cpu)
233 : {
234 0 : struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
235 : int i;
236 :
237 0 : for (i = 0; i < NR_CACHED_STACKS; i++) {
238 0 : struct vm_struct *vm_stack = cached_vm_stacks[i];
239 :
240 0 : if (!vm_stack)
241 0 : continue;
242 :
243 0 : vfree(vm_stack->addr);
244 0 : cached_vm_stacks[i] = NULL;
245 : }
246 :
247 0 : return 0;
248 : }
249 :
250 107 : static int memcg_charge_kernel_stack(struct vm_struct *vm)
251 : {
252 : int i;
253 : int ret;
254 :
255 : BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
256 107 : BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
257 :
258 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
259 : ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
260 : if (ret)
261 : goto err;
262 : }
263 : return 0;
264 : err:
265 : /*
266 : * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
267 : * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
268 : * ignore this page.
269 : */
270 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
271 : memcg_kmem_uncharge_page(vm->pages[i], 0);
272 : return ret;
273 : }
274 :
275 107 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
276 : {
277 : struct vm_struct *vm;
278 : void *stack;
279 : int i;
280 :
281 274 : for (i = 0; i < NR_CACHED_STACKS; i++) {
282 : struct vm_struct *s;
283 :
284 366 : s = this_cpu_xchg(cached_stacks[i], NULL);
285 :
286 122 : if (!s)
287 30 : continue;
288 :
289 : /* Reset stack metadata. */
290 92 : kasan_unpoison_range(s->addr, THREAD_SIZE);
291 :
292 92 : stack = kasan_reset_tag(s->addr);
293 :
294 : /* Clear stale pointers from reused stack. */
295 92 : memset(stack, 0, THREAD_SIZE);
296 :
297 92 : if (memcg_charge_kernel_stack(s)) {
298 0 : vfree(s->addr);
299 : return -ENOMEM;
300 : }
301 :
302 92 : tsk->stack_vm_area = s;
303 92 : tsk->stack = stack;
304 : return 0;
305 : }
306 :
307 : /*
308 : * Allocated stacks are cached and later reused by new threads,
309 : * so memcg accounting is performed manually on assigning/releasing
310 : * stacks to tasks. Drop __GFP_ACCOUNT.
311 : */
312 30 : stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
313 15 : VMALLOC_START, VMALLOC_END,
314 : THREADINFO_GFP & ~__GFP_ACCOUNT,
315 15 : PAGE_KERNEL,
316 15 : 0, node, __builtin_return_address(0));
317 15 : if (!stack)
318 : return -ENOMEM;
319 :
320 15 : vm = find_vm_area(stack);
321 15 : if (memcg_charge_kernel_stack(vm)) {
322 0 : vfree(stack);
323 : return -ENOMEM;
324 : }
325 : /*
326 : * We can't call find_vm_area() in interrupt context, and
327 : * free_thread_stack() can be called in interrupt context,
328 : * so cache the vm_struct.
329 : */
330 15 : tsk->stack_vm_area = vm;
331 15 : stack = kasan_reset_tag(stack);
332 15 : tsk->stack = stack;
333 : return 0;
334 : }
335 :
336 92 : static void free_thread_stack(struct task_struct *tsk)
337 : {
338 92 : if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
339 0 : thread_stack_delayed_free(tsk);
340 :
341 92 : tsk->stack = NULL;
342 92 : tsk->stack_vm_area = NULL;
343 92 : }
344 :
345 : # else /* !CONFIG_VMAP_STACK */
346 :
347 : static void thread_stack_free_rcu(struct rcu_head *rh)
348 : {
349 : __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
350 : }
351 :
352 : static void thread_stack_delayed_free(struct task_struct *tsk)
353 : {
354 : struct rcu_head *rh = tsk->stack;
355 :
356 : call_rcu(rh, thread_stack_free_rcu);
357 : }
358 :
359 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
360 : {
361 : struct page *page = alloc_pages_node(node, THREADINFO_GFP,
362 : THREAD_SIZE_ORDER);
363 :
364 : if (likely(page)) {
365 : tsk->stack = kasan_reset_tag(page_address(page));
366 : return 0;
367 : }
368 : return -ENOMEM;
369 : }
370 :
371 : static void free_thread_stack(struct task_struct *tsk)
372 : {
373 : thread_stack_delayed_free(tsk);
374 : tsk->stack = NULL;
375 : }
376 :
377 : # endif /* CONFIG_VMAP_STACK */
378 : # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
379 :
380 : static struct kmem_cache *thread_stack_cache;
381 :
382 : static void thread_stack_free_rcu(struct rcu_head *rh)
383 : {
384 : kmem_cache_free(thread_stack_cache, rh);
385 : }
386 :
387 : static void thread_stack_delayed_free(struct task_struct *tsk)
388 : {
389 : struct rcu_head *rh = tsk->stack;
390 :
391 : call_rcu(rh, thread_stack_free_rcu);
392 : }
393 :
394 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
395 : {
396 : unsigned long *stack;
397 : stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
398 : stack = kasan_reset_tag(stack);
399 : tsk->stack = stack;
400 : return stack ? 0 : -ENOMEM;
401 : }
402 :
403 : static void free_thread_stack(struct task_struct *tsk)
404 : {
405 : thread_stack_delayed_free(tsk);
406 : tsk->stack = NULL;
407 : }
408 :
409 : void thread_stack_cache_init(void)
410 : {
411 : thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
412 : THREAD_SIZE, THREAD_SIZE, 0, 0,
413 : THREAD_SIZE, NULL);
414 : BUG_ON(thread_stack_cache == NULL);
415 : }
416 :
417 : # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
418 : #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
419 :
420 : static int alloc_thread_stack_node(struct task_struct *tsk, int node)
421 : {
422 : unsigned long *stack;
423 :
424 : stack = arch_alloc_thread_stack_node(tsk, node);
425 : tsk->stack = stack;
426 : return stack ? 0 : -ENOMEM;
427 : }
428 :
429 : static void free_thread_stack(struct task_struct *tsk)
430 : {
431 : arch_free_thread_stack(tsk);
432 : tsk->stack = NULL;
433 : }
434 :
435 : #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
436 :
437 : /* SLAB cache for signal_struct structures (tsk->signal) */
438 : static struct kmem_cache *signal_cachep;
439 :
440 : /* SLAB cache for sighand_struct structures (tsk->sighand) */
441 : struct kmem_cache *sighand_cachep;
442 :
443 : /* SLAB cache for files_struct structures (tsk->files) */
444 : struct kmem_cache *files_cachep;
445 :
446 : /* SLAB cache for fs_struct structures (tsk->fs) */
447 : struct kmem_cache *fs_cachep;
448 :
449 : /* SLAB cache for vm_area_struct structures */
450 : static struct kmem_cache *vm_area_cachep;
451 :
452 : /* SLAB cache for mm_struct structures (tsk->mm) */
453 : static struct kmem_cache *mm_cachep;
454 :
455 0 : struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
456 : {
457 : struct vm_area_struct *vma;
458 :
459 0 : vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
460 0 : if (vma)
461 : vma_init(vma, mm);
462 0 : return vma;
463 : }
464 :
465 0 : struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
466 : {
467 0 : struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
468 :
469 0 : if (new) {
470 0 : ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
471 0 : ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
472 : /*
473 : * orig->shared.rb may be modified concurrently, but the clone
474 : * will be reinitialized.
475 : */
476 0 : *new = data_race(*orig);
477 0 : INIT_LIST_HEAD(&new->anon_vma_chain);
478 0 : new->vm_next = new->vm_prev = NULL;
479 0 : dup_anon_vma_name(orig, new);
480 : }
481 0 : return new;
482 : }
483 :
484 0 : void vm_area_free(struct vm_area_struct *vma)
485 : {
486 0 : free_anon_vma_name(vma);
487 0 : kmem_cache_free(vm_area_cachep, vma);
488 0 : }
489 :
490 : static void account_kernel_stack(struct task_struct *tsk, int account)
491 : {
492 : if (IS_ENABLED(CONFIG_VMAP_STACK)) {
493 : struct vm_struct *vm = task_stack_vm_area(tsk);
494 : int i;
495 :
496 800 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
497 1600 : mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
498 : account * (PAGE_SIZE / 1024));
499 : } else {
500 : void *stack = task_stack_page(tsk);
501 :
502 : /* All stack pages are in the same node. */
503 : mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
504 : account * (THREAD_SIZE / 1024));
505 : }
506 : }
507 :
508 93 : void exit_task_stack_account(struct task_struct *tsk)
509 : {
510 186 : account_kernel_stack(tsk, -1);
511 :
512 : if (IS_ENABLED(CONFIG_VMAP_STACK)) {
513 : struct vm_struct *vm;
514 : int i;
515 :
516 93 : vm = task_stack_vm_area(tsk);
517 93 : for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
518 : memcg_kmem_uncharge_page(vm->pages[i], 0);
519 : }
520 93 : }
521 :
522 92 : static void release_task_stack(struct task_struct *tsk)
523 : {
524 92 : if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
525 : return; /* Better to leak the stack than to free prematurely */
526 :
527 92 : free_thread_stack(tsk);
528 : }
529 :
530 : #ifdef CONFIG_THREAD_INFO_IN_TASK
531 : void put_task_stack(struct task_struct *tsk)
532 : {
533 : if (refcount_dec_and_test(&tsk->stack_refcount))
534 : release_task_stack(tsk);
535 : }
536 : #endif
537 :
538 92 : void free_task(struct task_struct *tsk)
539 : {
540 92 : release_user_cpus_ptr(tsk);
541 92 : scs_release(tsk);
542 :
543 : #ifndef CONFIG_THREAD_INFO_IN_TASK
544 : /*
545 : * The task is finally done with both the stack and thread_info,
546 : * so free both.
547 : */
548 92 : release_task_stack(tsk);
549 : #else
550 : /*
551 : * If the task had a separate stack allocation, it should be gone
552 : * by now.
553 : */
554 : WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
555 : #endif
556 92 : rt_mutex_debug_task_free(tsk);
557 92 : ftrace_graph_exit_task(tsk);
558 92 : arch_release_task_struct(tsk);
559 92 : if (tsk->flags & PF_KTHREAD)
560 92 : free_kthread_struct(tsk);
561 92 : free_task_struct(tsk);
562 92 : }
563 : EXPORT_SYMBOL(free_task);
564 :
565 0 : static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
566 : {
567 : struct file *exe_file;
568 :
569 0 : exe_file = get_mm_exe_file(oldmm);
570 0 : RCU_INIT_POINTER(mm->exe_file, exe_file);
571 : /*
572 : * We depend on the oldmm having properly denied write access to the
573 : * exe_file already.
574 : */
575 0 : if (exe_file && deny_write_access(exe_file))
576 0 : pr_warn_once("deny_write_access() failed in %s\n", __func__);
577 0 : }
578 :
579 : #ifdef CONFIG_MMU
580 0 : static __latent_entropy int dup_mmap(struct mm_struct *mm,
581 : struct mm_struct *oldmm)
582 : {
583 : struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
584 : struct rb_node **rb_link, *rb_parent;
585 : int retval;
586 : unsigned long charge;
587 0 : LIST_HEAD(uf);
588 :
589 0 : uprobe_start_dup_mmap();
590 0 : if (mmap_write_lock_killable(oldmm)) {
591 : retval = -EINTR;
592 : goto fail_uprobe_end;
593 : }
594 0 : flush_cache_dup_mm(oldmm);
595 0 : uprobe_dup_mmap(oldmm, mm);
596 : /*
597 : * Not linked in yet - no deadlock potential:
598 : */
599 0 : mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
600 :
601 : /* No ordering required: file already has been exposed. */
602 0 : dup_mm_exe_file(mm, oldmm);
603 :
604 0 : mm->total_vm = oldmm->total_vm;
605 0 : mm->data_vm = oldmm->data_vm;
606 0 : mm->exec_vm = oldmm->exec_vm;
607 0 : mm->stack_vm = oldmm->stack_vm;
608 :
609 0 : rb_link = &mm->mm_rb.rb_node;
610 0 : rb_parent = NULL;
611 0 : pprev = &mm->mmap;
612 0 : retval = ksm_fork(mm, oldmm);
613 : if (retval)
614 : goto out;
615 0 : retval = khugepaged_fork(mm, oldmm);
616 : if (retval)
617 : goto out;
618 :
619 0 : prev = NULL;
620 0 : for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
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 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 : tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
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 : * Clear hugetlb-related page reserves for children. This only
681 : * affects MAP_PRIVATE mappings. Faults generated by the child
682 : * are not guaranteed to succeed, even if read-only
683 : */
684 0 : if (is_vm_hugetlb_page(tmp))
685 : reset_vma_resv_huge_pages(tmp);
686 :
687 : /*
688 : * Link in the new vma and copy the page table entries.
689 : */
690 0 : *pprev = tmp;
691 0 : pprev = &tmp->vm_next;
692 0 : tmp->vm_prev = prev;
693 0 : prev = tmp;
694 :
695 0 : __vma_link_rb(mm, tmp, rb_link, rb_parent);
696 0 : rb_link = &tmp->vm_rb.rb_right;
697 0 : rb_parent = &tmp->vm_rb;
698 :
699 0 : mm->map_count++;
700 0 : if (!(tmp->vm_flags & VM_WIPEONFORK))
701 0 : retval = copy_page_range(tmp, mpnt);
702 :
703 0 : if (tmp->vm_ops && tmp->vm_ops->open)
704 0 : tmp->vm_ops->open(tmp);
705 :
706 0 : if (retval)
707 : goto out;
708 : }
709 : /* a new mm has just been created */
710 : retval = arch_dup_mmap(oldmm, mm);
711 : out:
712 0 : mmap_write_unlock(mm);
713 0 : flush_tlb_mm(oldmm);
714 : mmap_write_unlock(oldmm);
715 : dup_userfaultfd_complete(&uf);
716 : fail_uprobe_end:
717 : uprobe_end_dup_mmap();
718 0 : return retval;
719 : fail_nomem_anon_vma_fork:
720 0 : mpol_put(vma_policy(tmp));
721 : fail_nomem_policy:
722 : vm_area_free(tmp);
723 : fail_nomem:
724 0 : retval = -ENOMEM;
725 0 : vm_unacct_memory(charge);
726 : goto out;
727 : }
728 :
729 : static inline int mm_alloc_pgd(struct mm_struct *mm)
730 : {
731 0 : mm->pgd = pgd_alloc(mm);
732 0 : if (unlikely(!mm->pgd))
733 : return -ENOMEM;
734 : return 0;
735 : }
736 :
737 : static inline void mm_free_pgd(struct mm_struct *mm)
738 : {
739 0 : pgd_free(mm, mm->pgd);
740 : }
741 : #else
742 : static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
743 : {
744 : mmap_write_lock(oldmm);
745 : dup_mm_exe_file(mm, oldmm);
746 : mmap_write_unlock(oldmm);
747 : return 0;
748 : }
749 : #define mm_alloc_pgd(mm) (0)
750 : #define mm_free_pgd(mm)
751 : #endif /* CONFIG_MMU */
752 :
753 0 : static void check_mm(struct mm_struct *mm)
754 : {
755 : int i;
756 :
757 : BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
758 : "Please make sure 'struct resident_page_types[]' is updated as well");
759 :
760 0 : for (i = 0; i < NR_MM_COUNTERS; i++) {
761 0 : long x = atomic_long_read(&mm->rss_stat.count[i]);
762 :
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 0 : BUG_ON(mm == &init_mm);
788 0 : WARN_ON_ONCE(mm == current->mm);
789 0 : WARN_ON_ONCE(mm == current->active_mm);
790 0 : mm_free_pgd(mm);
791 0 : destroy_context(mm);
792 0 : mmu_notifier_subscriptions_destroy(mm);
793 0 : check_mm(mm);
794 0 : put_user_ns(mm->user_ns);
795 0 : mm_pasid_drop(mm);
796 0 : free_mm(mm);
797 0 : }
798 : EXPORT_SYMBOL_GPL(__mmdrop);
799 :
800 0 : static void mmdrop_async_fn(struct work_struct *work)
801 : {
802 : struct mm_struct *mm;
803 :
804 0 : mm = container_of(work, struct mm_struct, async_put_work);
805 0 : __mmdrop(mm);
806 0 : }
807 :
808 0 : static void mmdrop_async(struct mm_struct *mm)
809 : {
810 0 : if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
811 0 : INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
812 0 : schedule_work(&mm->async_put_work);
813 : }
814 0 : }
815 :
816 92 : static inline void free_signal_struct(struct signal_struct *sig)
817 : {
818 92 : taskstats_tgid_free(sig);
819 92 : sched_autogroup_exit(sig);
820 : /*
821 : * __mmdrop is not safe to call from softirq context on x86 due to
822 : * pgd_dtor so postpone it to the async context
823 : */
824 92 : if (sig->oom_mm)
825 0 : mmdrop_async(sig->oom_mm);
826 92 : kmem_cache_free(signal_cachep, sig);
827 92 : }
828 :
829 92 : static inline void put_signal_struct(struct signal_struct *sig)
830 : {
831 184 : if (refcount_dec_and_test(&sig->sigcnt))
832 92 : free_signal_struct(sig);
833 92 : }
834 :
835 92 : void __put_task_struct(struct task_struct *tsk)
836 : {
837 92 : WARN_ON(!tsk->exit_state);
838 184 : WARN_ON(refcount_read(&tsk->usage));
839 92 : WARN_ON(tsk == current);
840 :
841 92 : io_uring_free(tsk);
842 92 : cgroup_free(tsk);
843 92 : task_numa_free(tsk, true);
844 92 : security_task_free(tsk);
845 92 : bpf_task_storage_free(tsk);
846 92 : exit_creds(tsk);
847 92 : delayacct_tsk_free(tsk);
848 92 : put_signal_struct(tsk->signal);
849 92 : sched_core_free(tsk);
850 92 : free_task(tsk);
851 92 : }
852 : EXPORT_SYMBOL_GPL(__put_task_struct);
853 :
854 1 : void __init __weak arch_task_cache_init(void) { }
855 :
856 : /*
857 : * set_max_threads
858 : */
859 : static void set_max_threads(unsigned int max_threads_suggested)
860 : {
861 : u64 threads;
862 1 : unsigned long nr_pages = totalram_pages();
863 :
864 : /*
865 : * The number of threads shall be limited such that the thread
866 : * structures may only consume a small part of the available memory.
867 : */
868 2 : if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
869 : threads = MAX_THREADS;
870 : else
871 2 : threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
872 : (u64) THREAD_SIZE * 8UL);
873 :
874 1 : if (threads > max_threads_suggested)
875 0 : threads = max_threads_suggested;
876 :
877 1 : max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
878 : }
879 :
880 : #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
881 : /* Initialized by the architecture: */
882 : int arch_task_struct_size __read_mostly;
883 : #endif
884 :
885 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
886 : static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
887 : {
888 : /* Fetch thread_struct whitelist for the architecture. */
889 1 : arch_thread_struct_whitelist(offset, size);
890 :
891 : /*
892 : * Handle zero-sized whitelist or empty thread_struct, otherwise
893 : * adjust offset to position of thread_struct in task_struct.
894 : */
895 : if (unlikely(*size == 0))
896 : *offset = 0;
897 : else
898 1 : *offset += offsetof(struct task_struct, thread);
899 : }
900 : #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
901 :
902 1 : void __init fork_init(void)
903 : {
904 : int i;
905 : #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
906 : #ifndef ARCH_MIN_TASKALIGN
907 : #define ARCH_MIN_TASKALIGN 0
908 : #endif
909 1 : int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
910 : unsigned long useroffset, usersize;
911 :
912 : /* create a slab on which task_structs can be allocated */
913 1 : task_struct_whitelist(&useroffset, &usersize);
914 1 : task_struct_cachep = kmem_cache_create_usercopy("task_struct",
915 : arch_task_struct_size, align,
916 : SLAB_PANIC|SLAB_ACCOUNT,
917 : useroffset, usersize, NULL);
918 : #endif
919 :
920 : /* do the arch specific task caches init */
921 1 : arch_task_cache_init();
922 :
923 1 : set_max_threads(MAX_THREADS);
924 :
925 1 : init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
926 1 : init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
927 1 : init_task.signal->rlim[RLIMIT_SIGPENDING] =
928 : init_task.signal->rlim[RLIMIT_NPROC];
929 :
930 11 : for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++)
931 10 : init_user_ns.ucount_max[i] = max_threads/2;
932 :
933 1 : set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
934 1 : set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
935 1 : set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
936 1 : set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
937 :
938 : #ifdef CONFIG_VMAP_STACK
939 1 : cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
940 : NULL, free_vm_stack_cache);
941 : #endif
942 :
943 : scs_init();
944 :
945 1 : lockdep_init_task(&init_task);
946 : uprobes_init();
947 1 : }
948 :
949 107 : int __weak arch_dup_task_struct(struct task_struct *dst,
950 : struct task_struct *src)
951 : {
952 107 : *dst = *src;
953 107 : return 0;
954 : }
955 :
956 1 : void set_task_stack_end_magic(struct task_struct *tsk)
957 : {
958 : unsigned long *stackend;
959 :
960 108 : stackend = end_of_stack(tsk);
961 108 : *stackend = STACK_END_MAGIC; /* for overflow detection */
962 1 : }
963 :
964 107 : static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
965 : {
966 : struct task_struct *tsk;
967 : int err;
968 :
969 107 : if (node == NUMA_NO_NODE)
970 107 : node = tsk_fork_get_node(orig);
971 214 : tsk = alloc_task_struct_node(node);
972 107 : if (!tsk)
973 : return NULL;
974 :
975 107 : err = arch_dup_task_struct(tsk, orig);
976 107 : if (err)
977 : goto free_tsk;
978 :
979 107 : err = alloc_thread_stack_node(tsk, node);
980 107 : if (err)
981 : goto free_tsk;
982 :
983 : #ifdef CONFIG_THREAD_INFO_IN_TASK
984 : refcount_set(&tsk->stack_refcount, 1);
985 : #endif
986 107 : account_kernel_stack(tsk, 1);
987 :
988 107 : err = scs_prepare(tsk, node);
989 : if (err)
990 : goto free_stack;
991 :
992 : #ifdef CONFIG_SECCOMP
993 : /*
994 : * We must handle setting up seccomp filters once we're under
995 : * the sighand lock in case orig has changed between now and
996 : * then. Until then, filter must be NULL to avoid messing up
997 : * the usage counts on the error path calling free_task.
998 : */
999 107 : tsk->seccomp.filter = NULL;
1000 : #endif
1001 :
1002 214 : setup_thread_stack(tsk, orig);
1003 107 : clear_user_return_notifier(tsk);
1004 107 : clear_tsk_need_resched(tsk);
1005 107 : set_task_stack_end_magic(tsk);
1006 : clear_syscall_work_syscall_user_dispatch(tsk);
1007 :
1008 : #ifdef CONFIG_STACKPROTECTOR
1009 : tsk->stack_canary = get_random_canary();
1010 : #endif
1011 107 : if (orig->cpus_ptr == &orig->cpus_mask)
1012 107 : tsk->cpus_ptr = &tsk->cpus_mask;
1013 107 : dup_user_cpus_ptr(tsk, orig, node);
1014 :
1015 : /*
1016 : * One for the user space visible state that goes away when reaped.
1017 : * One for the scheduler.
1018 : */
1019 214 : refcount_set(&tsk->rcu_users, 2);
1020 : /* One for the rcu users */
1021 214 : refcount_set(&tsk->usage, 1);
1022 : #ifdef CONFIG_BLK_DEV_IO_TRACE
1023 : tsk->btrace_seq = 0;
1024 : #endif
1025 107 : tsk->splice_pipe = NULL;
1026 107 : tsk->task_frag.page = NULL;
1027 107 : tsk->wake_q.next = NULL;
1028 107 : tsk->worker_private = NULL;
1029 :
1030 : kcov_task_init(tsk);
1031 : kmap_local_fork(tsk);
1032 :
1033 : #ifdef CONFIG_FAULT_INJECTION
1034 : tsk->fail_nth = 0;
1035 : #endif
1036 :
1037 : #ifdef CONFIG_BLK_CGROUP
1038 : tsk->throttle_queue = NULL;
1039 : tsk->use_memdelay = 0;
1040 : #endif
1041 :
1042 : #ifdef CONFIG_IOMMU_SVA
1043 : tsk->pasid_activated = 0;
1044 : #endif
1045 :
1046 : #ifdef CONFIG_MEMCG
1047 : tsk->active_memcg = NULL;
1048 : #endif
1049 107 : return tsk;
1050 :
1051 : free_stack:
1052 : exit_task_stack_account(tsk);
1053 : free_thread_stack(tsk);
1054 : free_tsk:
1055 0 : free_task_struct(tsk);
1056 0 : return NULL;
1057 : }
1058 :
1059 : __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1060 :
1061 : static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1062 :
1063 0 : static int __init coredump_filter_setup(char *s)
1064 : {
1065 0 : default_dump_filter =
1066 0 : (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1067 : MMF_DUMP_FILTER_MASK;
1068 0 : return 1;
1069 : }
1070 :
1071 : __setup("coredump_filter=", coredump_filter_setup);
1072 :
1073 : #include <linux/init_task.h>
1074 :
1075 : static void mm_init_aio(struct mm_struct *mm)
1076 : {
1077 : #ifdef CONFIG_AIO
1078 0 : spin_lock_init(&mm->ioctx_lock);
1079 0 : mm->ioctx_table = NULL;
1080 : #endif
1081 : }
1082 :
1083 : static __always_inline void mm_clear_owner(struct mm_struct *mm,
1084 : struct task_struct *p)
1085 : {
1086 : #ifdef CONFIG_MEMCG
1087 : if (mm->owner == p)
1088 : WRITE_ONCE(mm->owner, NULL);
1089 : #endif
1090 : }
1091 :
1092 : static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1093 : {
1094 : #ifdef CONFIG_MEMCG
1095 : mm->owner = p;
1096 : #endif
1097 : }
1098 :
1099 : static void mm_init_uprobes_state(struct mm_struct *mm)
1100 : {
1101 : #ifdef CONFIG_UPROBES
1102 : mm->uprobes_state.xol_area = NULL;
1103 : #endif
1104 : }
1105 :
1106 0 : static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1107 : struct user_namespace *user_ns)
1108 : {
1109 0 : mm->mmap = NULL;
1110 0 : mm->mm_rb = RB_ROOT;
1111 0 : mm->vmacache_seqnum = 0;
1112 0 : atomic_set(&mm->mm_users, 1);
1113 0 : atomic_set(&mm->mm_count, 1);
1114 0 : seqcount_init(&mm->write_protect_seq);
1115 0 : mmap_init_lock(mm);
1116 0 : INIT_LIST_HEAD(&mm->mmlist);
1117 0 : mm_pgtables_bytes_init(mm);
1118 0 : mm->map_count = 0;
1119 0 : mm->locked_vm = 0;
1120 0 : atomic64_set(&mm->pinned_vm, 0);
1121 0 : memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1122 0 : spin_lock_init(&mm->page_table_lock);
1123 0 : spin_lock_init(&mm->arg_lock);
1124 0 : mm_init_cpumask(mm);
1125 0 : mm_init_aio(mm);
1126 0 : mm_init_owner(mm, p);
1127 0 : mm_pasid_init(mm);
1128 0 : RCU_INIT_POINTER(mm->exe_file, NULL);
1129 0 : mmu_notifier_subscriptions_init(mm);
1130 0 : init_tlb_flush_pending(mm);
1131 : #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1132 : mm->pmd_huge_pte = NULL;
1133 : #endif
1134 0 : mm_init_uprobes_state(mm);
1135 0 : hugetlb_count_init(mm);
1136 :
1137 0 : if (current->mm) {
1138 0 : mm->flags = current->mm->flags & MMF_INIT_MASK;
1139 0 : mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1140 : } else {
1141 0 : mm->flags = default_dump_filter;
1142 0 : mm->def_flags = 0;
1143 : }
1144 :
1145 0 : if (mm_alloc_pgd(mm))
1146 : goto fail_nopgd;
1147 :
1148 0 : if (init_new_context(p, mm))
1149 : goto fail_nocontext;
1150 :
1151 0 : mm->user_ns = get_user_ns(user_ns);
1152 : return mm;
1153 :
1154 : fail_nocontext:
1155 : mm_free_pgd(mm);
1156 : fail_nopgd:
1157 0 : free_mm(mm);
1158 : return NULL;
1159 : }
1160 :
1161 : /*
1162 : * Allocate and initialize an mm_struct.
1163 : */
1164 0 : struct mm_struct *mm_alloc(void)
1165 : {
1166 : struct mm_struct *mm;
1167 :
1168 0 : mm = allocate_mm();
1169 0 : if (!mm)
1170 : return NULL;
1171 :
1172 0 : memset(mm, 0, sizeof(*mm));
1173 0 : return mm_init(mm, current, current_user_ns());
1174 : }
1175 :
1176 0 : static inline void __mmput(struct mm_struct *mm)
1177 : {
1178 : VM_BUG_ON(atomic_read(&mm->mm_users));
1179 :
1180 0 : uprobe_clear_state(mm);
1181 0 : exit_aio(mm);
1182 0 : ksm_exit(mm);
1183 0 : khugepaged_exit(mm); /* must run before exit_mmap */
1184 0 : exit_mmap(mm);
1185 0 : mm_put_huge_zero_page(mm);
1186 0 : set_mm_exe_file(mm, NULL);
1187 0 : if (!list_empty(&mm->mmlist)) {
1188 0 : spin_lock(&mmlist_lock);
1189 0 : list_del(&mm->mmlist);
1190 : spin_unlock(&mmlist_lock);
1191 : }
1192 0 : if (mm->binfmt)
1193 : module_put(mm->binfmt->module);
1194 0 : mmdrop(mm);
1195 0 : }
1196 :
1197 : /*
1198 : * Decrement the use count and release all resources for an mm.
1199 : */
1200 0 : void mmput(struct mm_struct *mm)
1201 : {
1202 : might_sleep();
1203 :
1204 0 : if (atomic_dec_and_test(&mm->mm_users))
1205 0 : __mmput(mm);
1206 0 : }
1207 : EXPORT_SYMBOL_GPL(mmput);
1208 :
1209 : #ifdef CONFIG_MMU
1210 0 : static void mmput_async_fn(struct work_struct *work)
1211 : {
1212 0 : struct mm_struct *mm = container_of(work, struct mm_struct,
1213 : async_put_work);
1214 :
1215 0 : __mmput(mm);
1216 0 : }
1217 :
1218 0 : void mmput_async(struct mm_struct *mm)
1219 : {
1220 0 : if (atomic_dec_and_test(&mm->mm_users)) {
1221 0 : INIT_WORK(&mm->async_put_work, mmput_async_fn);
1222 0 : schedule_work(&mm->async_put_work);
1223 : }
1224 0 : }
1225 : #endif
1226 :
1227 : /**
1228 : * set_mm_exe_file - change a reference to the mm's executable file
1229 : *
1230 : * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1231 : *
1232 : * Main users are mmput() and sys_execve(). Callers prevent concurrent
1233 : * invocations: in mmput() nobody alive left, in execve task is single
1234 : * threaded.
1235 : *
1236 : * Can only fail if new_exe_file != NULL.
1237 : */
1238 0 : int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1239 : {
1240 : struct file *old_exe_file;
1241 :
1242 : /*
1243 : * It is safe to dereference the exe_file without RCU as
1244 : * this function is only called if nobody else can access
1245 : * this mm -- see comment above for justification.
1246 : */
1247 0 : old_exe_file = rcu_dereference_raw(mm->exe_file);
1248 :
1249 0 : if (new_exe_file) {
1250 : /*
1251 : * We expect the caller (i.e., sys_execve) to already denied
1252 : * write access, so this is unlikely to fail.
1253 : */
1254 0 : if (unlikely(deny_write_access(new_exe_file)))
1255 : return -EACCES;
1256 : get_file(new_exe_file);
1257 : }
1258 0 : rcu_assign_pointer(mm->exe_file, new_exe_file);
1259 0 : if (old_exe_file) {
1260 0 : allow_write_access(old_exe_file);
1261 0 : fput(old_exe_file);
1262 : }
1263 : return 0;
1264 : }
1265 :
1266 : /**
1267 : * replace_mm_exe_file - replace a reference to the mm's executable file
1268 : *
1269 : * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1270 : * dealing with concurrent invocation and without grabbing the mmap lock in
1271 : * write mode.
1272 : *
1273 : * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1274 : */
1275 0 : int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1276 : {
1277 : struct vm_area_struct *vma;
1278 : struct file *old_exe_file;
1279 0 : int ret = 0;
1280 :
1281 : /* Forbid mm->exe_file change if old file still mapped. */
1282 0 : old_exe_file = get_mm_exe_file(mm);
1283 0 : if (old_exe_file) {
1284 0 : mmap_read_lock(mm);
1285 0 : for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) {
1286 0 : if (!vma->vm_file)
1287 0 : continue;
1288 0 : if (path_equal(&vma->vm_file->f_path,
1289 0 : &old_exe_file->f_path))
1290 0 : ret = -EBUSY;
1291 : }
1292 0 : mmap_read_unlock(mm);
1293 0 : fput(old_exe_file);
1294 0 : if (ret)
1295 : return ret;
1296 : }
1297 :
1298 : /* set the new file, lockless */
1299 0 : ret = deny_write_access(new_exe_file);
1300 0 : if (ret)
1301 : return -EACCES;
1302 0 : get_file(new_exe_file);
1303 :
1304 0 : old_exe_file = xchg(&mm->exe_file, new_exe_file);
1305 0 : if (old_exe_file) {
1306 : /*
1307 : * Don't race with dup_mmap() getting the file and disallowing
1308 : * write access while someone might open the file writable.
1309 : */
1310 0 : mmap_read_lock(mm);
1311 0 : allow_write_access(old_exe_file);
1312 0 : fput(old_exe_file);
1313 : mmap_read_unlock(mm);
1314 : }
1315 : return 0;
1316 : }
1317 :
1318 : /**
1319 : * get_mm_exe_file - acquire a reference to the mm's executable file
1320 : *
1321 : * Returns %NULL if mm has no associated executable file.
1322 : * User must release file via fput().
1323 : */
1324 0 : struct file *get_mm_exe_file(struct mm_struct *mm)
1325 : {
1326 : struct file *exe_file;
1327 :
1328 : rcu_read_lock();
1329 0 : exe_file = rcu_dereference(mm->exe_file);
1330 0 : if (exe_file && !get_file_rcu(exe_file))
1331 0 : exe_file = NULL;
1332 : rcu_read_unlock();
1333 0 : return exe_file;
1334 : }
1335 :
1336 : /**
1337 : * get_task_exe_file - acquire a reference to the task's executable file
1338 : *
1339 : * Returns %NULL if task's mm (if any) has no associated executable file or
1340 : * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1341 : * User must release file via fput().
1342 : */
1343 0 : struct file *get_task_exe_file(struct task_struct *task)
1344 : {
1345 0 : struct file *exe_file = NULL;
1346 : struct mm_struct *mm;
1347 :
1348 0 : task_lock(task);
1349 0 : mm = task->mm;
1350 0 : if (mm) {
1351 0 : if (!(task->flags & PF_KTHREAD))
1352 0 : exe_file = get_mm_exe_file(mm);
1353 : }
1354 0 : task_unlock(task);
1355 0 : return exe_file;
1356 : }
1357 :
1358 : /**
1359 : * get_task_mm - acquire a reference to the task's mm
1360 : *
1361 : * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1362 : * this kernel workthread has transiently adopted a user mm with use_mm,
1363 : * to do its AIO) is not set and if so returns a reference to it, after
1364 : * bumping up the use count. User must release the mm via mmput()
1365 : * after use. Typically used by /proc and ptrace.
1366 : */
1367 0 : struct mm_struct *get_task_mm(struct task_struct *task)
1368 : {
1369 : struct mm_struct *mm;
1370 :
1371 0 : task_lock(task);
1372 0 : mm = task->mm;
1373 0 : if (mm) {
1374 0 : if (task->flags & PF_KTHREAD)
1375 : mm = NULL;
1376 : else
1377 : mmget(mm);
1378 : }
1379 0 : task_unlock(task);
1380 0 : return mm;
1381 : }
1382 : EXPORT_SYMBOL_GPL(get_task_mm);
1383 :
1384 0 : struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1385 : {
1386 : struct mm_struct *mm;
1387 : int err;
1388 :
1389 0 : err = down_read_killable(&task->signal->exec_update_lock);
1390 0 : if (err)
1391 0 : return ERR_PTR(err);
1392 :
1393 0 : mm = get_task_mm(task);
1394 0 : if (mm && mm != current->mm &&
1395 0 : !ptrace_may_access(task, mode)) {
1396 : mmput(mm);
1397 : mm = ERR_PTR(-EACCES);
1398 : }
1399 0 : up_read(&task->signal->exec_update_lock);
1400 :
1401 0 : return mm;
1402 : }
1403 :
1404 : static void complete_vfork_done(struct task_struct *tsk)
1405 : {
1406 : struct completion *vfork;
1407 :
1408 93 : task_lock(tsk);
1409 93 : vfork = tsk->vfork_done;
1410 93 : if (likely(vfork)) {
1411 93 : tsk->vfork_done = NULL;
1412 93 : complete(vfork);
1413 : }
1414 93 : task_unlock(tsk);
1415 : }
1416 :
1417 0 : static int wait_for_vfork_done(struct task_struct *child,
1418 : struct completion *vfork)
1419 : {
1420 : int killed;
1421 :
1422 0 : freezer_do_not_count();
1423 : cgroup_enter_frozen();
1424 0 : killed = wait_for_completion_killable(vfork);
1425 0 : cgroup_leave_frozen(false);
1426 0 : freezer_count();
1427 :
1428 0 : if (killed) {
1429 0 : task_lock(child);
1430 0 : child->vfork_done = NULL;
1431 0 : task_unlock(child);
1432 : }
1433 :
1434 0 : put_task_struct(child);
1435 0 : return killed;
1436 : }
1437 :
1438 : /* Please note the differences between mmput and mm_release.
1439 : * mmput is called whenever we stop holding onto a mm_struct,
1440 : * error success whatever.
1441 : *
1442 : * mm_release is called after a mm_struct has been removed
1443 : * from the current process.
1444 : *
1445 : * This difference is important for error handling, when we
1446 : * only half set up a mm_struct for a new process and need to restore
1447 : * the old one. Because we mmput the new mm_struct before
1448 : * restoring the old one. . .
1449 : * Eric Biederman 10 January 1998
1450 : */
1451 93 : static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1452 : {
1453 93 : uprobe_free_utask(tsk);
1454 :
1455 : /* Get rid of any cached register state */
1456 93 : deactivate_mm(tsk, mm);
1457 :
1458 : /*
1459 : * Signal userspace if we're not exiting with a core dump
1460 : * because we want to leave the value intact for debugging
1461 : * purposes.
1462 : */
1463 93 : if (tsk->clear_child_tid) {
1464 0 : if (atomic_read(&mm->mm_users) > 1) {
1465 : /*
1466 : * We don't check the error code - if userspace has
1467 : * not set up a proper pointer then tough luck.
1468 : */
1469 0 : put_user(0, tsk->clear_child_tid);
1470 0 : do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1471 : 1, NULL, NULL, 0, 0);
1472 : }
1473 0 : tsk->clear_child_tid = NULL;
1474 : }
1475 :
1476 : /*
1477 : * All done, finally we can wake up parent and return this mm to him.
1478 : * Also kthread_stop() uses this completion for synchronization.
1479 : */
1480 93 : if (tsk->vfork_done)
1481 93 : complete_vfork_done(tsk);
1482 93 : }
1483 :
1484 93 : void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1485 : {
1486 93 : futex_exit_release(tsk);
1487 93 : mm_release(tsk, mm);
1488 93 : }
1489 :
1490 0 : void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1491 : {
1492 0 : futex_exec_release(tsk);
1493 0 : mm_release(tsk, mm);
1494 0 : }
1495 :
1496 : /**
1497 : * dup_mm() - duplicates an existing mm structure
1498 : * @tsk: the task_struct with which the new mm will be associated.
1499 : * @oldmm: the mm to duplicate.
1500 : *
1501 : * Allocates a new mm structure and duplicates the provided @oldmm structure
1502 : * content into it.
1503 : *
1504 : * Return: the duplicated mm or NULL on failure.
1505 : */
1506 0 : static struct mm_struct *dup_mm(struct task_struct *tsk,
1507 : struct mm_struct *oldmm)
1508 : {
1509 : struct mm_struct *mm;
1510 : int err;
1511 :
1512 0 : mm = allocate_mm();
1513 0 : if (!mm)
1514 : goto fail_nomem;
1515 :
1516 0 : memcpy(mm, oldmm, sizeof(*mm));
1517 :
1518 0 : if (!mm_init(mm, tsk, mm->user_ns))
1519 : goto fail_nomem;
1520 :
1521 0 : err = dup_mmap(mm, oldmm);
1522 0 : if (err)
1523 : goto free_pt;
1524 :
1525 0 : mm->hiwater_rss = get_mm_rss(mm);
1526 0 : mm->hiwater_vm = mm->total_vm;
1527 :
1528 0 : if (mm->binfmt && !try_module_get(mm->binfmt->module))
1529 : goto free_pt;
1530 :
1531 : return mm;
1532 :
1533 : free_pt:
1534 : /* don't put binfmt in mmput, we haven't got module yet */
1535 0 : mm->binfmt = NULL;
1536 0 : mm_init_owner(mm, NULL);
1537 : mmput(mm);
1538 :
1539 : fail_nomem:
1540 : return NULL;
1541 : }
1542 :
1543 107 : static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1544 : {
1545 : struct mm_struct *mm, *oldmm;
1546 :
1547 107 : tsk->min_flt = tsk->maj_flt = 0;
1548 107 : tsk->nvcsw = tsk->nivcsw = 0;
1549 : #ifdef CONFIG_DETECT_HUNG_TASK
1550 : tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1551 : tsk->last_switch_time = 0;
1552 : #endif
1553 :
1554 107 : tsk->mm = NULL;
1555 107 : tsk->active_mm = NULL;
1556 :
1557 : /*
1558 : * Are we cloning a kernel thread?
1559 : *
1560 : * We need to steal a active VM for that..
1561 : */
1562 107 : oldmm = current->mm;
1563 107 : if (!oldmm)
1564 : return 0;
1565 :
1566 : /* initialize the new vmacache entries */
1567 0 : vmacache_flush(tsk);
1568 :
1569 0 : if (clone_flags & CLONE_VM) {
1570 0 : mmget(oldmm);
1571 0 : mm = oldmm;
1572 : } else {
1573 0 : mm = dup_mm(tsk, current->mm);
1574 0 : if (!mm)
1575 : return -ENOMEM;
1576 : }
1577 :
1578 0 : tsk->mm = mm;
1579 0 : tsk->active_mm = mm;
1580 0 : return 0;
1581 : }
1582 :
1583 107 : static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1584 : {
1585 107 : struct fs_struct *fs = current->fs;
1586 107 : if (clone_flags & CLONE_FS) {
1587 : /* tsk->fs is already what we want */
1588 214 : spin_lock(&fs->lock);
1589 107 : if (fs->in_exec) {
1590 0 : spin_unlock(&fs->lock);
1591 : return -EAGAIN;
1592 : }
1593 107 : fs->users++;
1594 214 : spin_unlock(&fs->lock);
1595 : return 0;
1596 : }
1597 0 : tsk->fs = copy_fs_struct(fs);
1598 0 : if (!tsk->fs)
1599 : return -ENOMEM;
1600 : return 0;
1601 : }
1602 :
1603 107 : static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1604 : {
1605 : struct files_struct *oldf, *newf;
1606 107 : int error = 0;
1607 :
1608 : /*
1609 : * A background process may not have any files ...
1610 : */
1611 107 : oldf = current->files;
1612 107 : if (!oldf)
1613 : goto out;
1614 :
1615 107 : if (clone_flags & CLONE_FILES) {
1616 106 : atomic_inc(&oldf->count);
1617 : goto out;
1618 : }
1619 :
1620 1 : newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1621 1 : if (!newf)
1622 : goto out;
1623 :
1624 1 : tsk->files = newf;
1625 1 : error = 0;
1626 : out:
1627 107 : return error;
1628 : }
1629 :
1630 107 : static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1631 : {
1632 : struct sighand_struct *sig;
1633 :
1634 107 : if (clone_flags & CLONE_SIGHAND) {
1635 0 : refcount_inc(¤t->sighand->count);
1636 0 : return 0;
1637 : }
1638 107 : sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1639 107 : RCU_INIT_POINTER(tsk->sighand, sig);
1640 107 : if (!sig)
1641 : return -ENOMEM;
1642 :
1643 214 : refcount_set(&sig->count, 1);
1644 214 : spin_lock_irq(¤t->sighand->siglock);
1645 107 : memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1646 214 : spin_unlock_irq(¤t->sighand->siglock);
1647 :
1648 : /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1649 107 : if (clone_flags & CLONE_CLEAR_SIGHAND)
1650 0 : flush_signal_handlers(tsk, 0);
1651 :
1652 : return 0;
1653 : }
1654 :
1655 93 : void __cleanup_sighand(struct sighand_struct *sighand)
1656 : {
1657 186 : if (refcount_dec_and_test(&sighand->count)) {
1658 93 : signalfd_cleanup(sighand);
1659 : /*
1660 : * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1661 : * without an RCU grace period, see __lock_task_sighand().
1662 : */
1663 93 : kmem_cache_free(sighand_cachep, sighand);
1664 : }
1665 93 : }
1666 :
1667 : /*
1668 : * Initialize POSIX timer handling for a thread group.
1669 : */
1670 : static void posix_cpu_timers_init_group(struct signal_struct *sig)
1671 : {
1672 107 : struct posix_cputimers *pct = &sig->posix_cputimers;
1673 : unsigned long cpu_limit;
1674 :
1675 107 : cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1676 107 : posix_cputimers_group_init(pct, cpu_limit);
1677 : }
1678 :
1679 107 : static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1680 : {
1681 : struct signal_struct *sig;
1682 :
1683 107 : if (clone_flags & CLONE_THREAD)
1684 : return 0;
1685 :
1686 214 : sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1687 107 : tsk->signal = sig;
1688 107 : if (!sig)
1689 : return -ENOMEM;
1690 :
1691 107 : sig->nr_threads = 1;
1692 214 : atomic_set(&sig->live, 1);
1693 214 : refcount_set(&sig->sigcnt, 1);
1694 :
1695 : /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1696 107 : sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1697 107 : tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1698 :
1699 107 : init_waitqueue_head(&sig->wait_chldexit);
1700 107 : sig->curr_target = tsk;
1701 214 : init_sigpending(&sig->shared_pending);
1702 107 : INIT_HLIST_HEAD(&sig->multiprocess);
1703 214 : seqlock_init(&sig->stats_lock);
1704 214 : prev_cputime_init(&sig->prev_cputime);
1705 :
1706 : #ifdef CONFIG_POSIX_TIMERS
1707 214 : INIT_LIST_HEAD(&sig->posix_timers);
1708 107 : hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1709 107 : sig->real_timer.function = it_real_fn;
1710 : #endif
1711 :
1712 107 : task_lock(current->group_leader);
1713 107 : memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1714 214 : task_unlock(current->group_leader);
1715 :
1716 107 : posix_cpu_timers_init_group(sig);
1717 :
1718 : tty_audit_fork(sig);
1719 : sched_autogroup_fork(sig);
1720 :
1721 107 : sig->oom_score_adj = current->signal->oom_score_adj;
1722 107 : sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1723 :
1724 107 : mutex_init(&sig->cred_guard_mutex);
1725 107 : init_rwsem(&sig->exec_update_lock);
1726 :
1727 107 : return 0;
1728 : }
1729 :
1730 107 : static void copy_seccomp(struct task_struct *p)
1731 : {
1732 : #ifdef CONFIG_SECCOMP
1733 : /*
1734 : * Must be called with sighand->lock held, which is common to
1735 : * all threads in the group. Holding cred_guard_mutex is not
1736 : * needed because this new task is not yet running and cannot
1737 : * be racing exec.
1738 : */
1739 107 : assert_spin_locked(¤t->sighand->siglock);
1740 :
1741 : /* Ref-count the new filter user, and assign it. */
1742 107 : get_seccomp_filter(current);
1743 107 : p->seccomp = current->seccomp;
1744 :
1745 : /*
1746 : * Explicitly enable no_new_privs here in case it got set
1747 : * between the task_struct being duplicated and holding the
1748 : * sighand lock. The seccomp state and nnp must be in sync.
1749 : */
1750 214 : if (task_no_new_privs(current))
1751 : task_set_no_new_privs(p);
1752 :
1753 : /*
1754 : * If the parent gained a seccomp mode after copying thread
1755 : * flags and between before we held the sighand lock, we have
1756 : * to manually enable the seccomp thread flag here.
1757 : */
1758 107 : if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1759 0 : set_task_syscall_work(p, SECCOMP);
1760 : #endif
1761 107 : }
1762 :
1763 0 : SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1764 : {
1765 0 : current->clear_child_tid = tidptr;
1766 :
1767 0 : return task_pid_vnr(current);
1768 : }
1769 :
1770 : static void rt_mutex_init_task(struct task_struct *p)
1771 : {
1772 : raw_spin_lock_init(&p->pi_lock);
1773 : #ifdef CONFIG_RT_MUTEXES
1774 107 : p->pi_waiters = RB_ROOT_CACHED;
1775 107 : p->pi_top_task = NULL;
1776 107 : p->pi_blocked_on = NULL;
1777 : #endif
1778 : }
1779 :
1780 : static inline void init_task_pid_links(struct task_struct *task)
1781 : {
1782 : enum pid_type type;
1783 :
1784 428 : for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1785 856 : INIT_HLIST_NODE(&task->pid_links[type]);
1786 : }
1787 :
1788 : static inline void
1789 : init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1790 : {
1791 0 : if (type == PIDTYPE_PID)
1792 107 : task->thread_pid = pid;
1793 : else
1794 321 : task->signal->pids[type] = pid;
1795 : }
1796 :
1797 : static inline void rcu_copy_process(struct task_struct *p)
1798 : {
1799 : #ifdef CONFIG_PREEMPT_RCU
1800 : p->rcu_read_lock_nesting = 0;
1801 : p->rcu_read_unlock_special.s = 0;
1802 : p->rcu_blocked_node = NULL;
1803 : INIT_LIST_HEAD(&p->rcu_node_entry);
1804 : #endif /* #ifdef CONFIG_PREEMPT_RCU */
1805 : #ifdef CONFIG_TASKS_RCU
1806 : p->rcu_tasks_holdout = false;
1807 : INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1808 : p->rcu_tasks_idle_cpu = -1;
1809 : #endif /* #ifdef CONFIG_TASKS_RCU */
1810 : #ifdef CONFIG_TASKS_TRACE_RCU
1811 : p->trc_reader_nesting = 0;
1812 : p->trc_reader_special.s = 0;
1813 : INIT_LIST_HEAD(&p->trc_holdout_list);
1814 : #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1815 : }
1816 :
1817 0 : struct pid *pidfd_pid(const struct file *file)
1818 : {
1819 0 : if (file->f_op == &pidfd_fops)
1820 0 : return file->private_data;
1821 :
1822 : return ERR_PTR(-EBADF);
1823 : }
1824 :
1825 0 : static int pidfd_release(struct inode *inode, struct file *file)
1826 : {
1827 0 : struct pid *pid = file->private_data;
1828 :
1829 0 : file->private_data = NULL;
1830 0 : put_pid(pid);
1831 0 : return 0;
1832 : }
1833 :
1834 : #ifdef CONFIG_PROC_FS
1835 : /**
1836 : * pidfd_show_fdinfo - print information about a pidfd
1837 : * @m: proc fdinfo file
1838 : * @f: file referencing a pidfd
1839 : *
1840 : * Pid:
1841 : * This function will print the pid that a given pidfd refers to in the
1842 : * pid namespace of the procfs instance.
1843 : * If the pid namespace of the process is not a descendant of the pid
1844 : * namespace of the procfs instance 0 will be shown as its pid. This is
1845 : * similar to calling getppid() on a process whose parent is outside of
1846 : * its pid namespace.
1847 : *
1848 : * NSpid:
1849 : * If pid namespaces are supported then this function will also print
1850 : * the pid of a given pidfd refers to for all descendant pid namespaces
1851 : * starting from the current pid namespace of the instance, i.e. the
1852 : * Pid field and the first entry in the NSpid field will be identical.
1853 : * If the pid namespace of the process is not a descendant of the pid
1854 : * namespace of the procfs instance 0 will be shown as its first NSpid
1855 : * entry and no others will be shown.
1856 : * Note that this differs from the Pid and NSpid fields in
1857 : * /proc/<pid>/status where Pid and NSpid are always shown relative to
1858 : * the pid namespace of the procfs instance. The difference becomes
1859 : * obvious when sending around a pidfd between pid namespaces from a
1860 : * different branch of the tree, i.e. where no ancestral relation is
1861 : * present between the pid namespaces:
1862 : * - create two new pid namespaces ns1 and ns2 in the initial pid
1863 : * namespace (also take care to create new mount namespaces in the
1864 : * new pid namespace and mount procfs)
1865 : * - create a process with a pidfd in ns1
1866 : * - send pidfd from ns1 to ns2
1867 : * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1868 : * have exactly one entry, which is 0
1869 : */
1870 0 : static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
1871 : {
1872 0 : struct pid *pid = f->private_data;
1873 : struct pid_namespace *ns;
1874 0 : pid_t nr = -1;
1875 :
1876 0 : if (likely(pid_has_task(pid, PIDTYPE_PID))) {
1877 0 : ns = proc_pid_ns(file_inode(m->file)->i_sb);
1878 0 : nr = pid_nr_ns(pid, ns);
1879 : }
1880 :
1881 0 : seq_put_decimal_ll(m, "Pid:\t", nr);
1882 :
1883 : #ifdef CONFIG_PID_NS
1884 0 : seq_put_decimal_ll(m, "\nNSpid:\t", nr);
1885 0 : if (nr > 0) {
1886 : int i;
1887 :
1888 : /* If nr is non-zero it means that 'pid' is valid and that
1889 : * ns, i.e. the pid namespace associated with the procfs
1890 : * instance, is in the pid namespace hierarchy of pid.
1891 : * Start at one below the already printed level.
1892 : */
1893 0 : for (i = ns->level + 1; i <= pid->level; i++)
1894 0 : seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
1895 : }
1896 : #endif
1897 0 : seq_putc(m, '\n');
1898 0 : }
1899 : #endif
1900 :
1901 : /*
1902 : * Poll support for process exit notification.
1903 : */
1904 0 : static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
1905 : {
1906 0 : struct pid *pid = file->private_data;
1907 0 : __poll_t poll_flags = 0;
1908 :
1909 0 : poll_wait(file, &pid->wait_pidfd, pts);
1910 :
1911 : /*
1912 : * Inform pollers only when the whole thread group exits.
1913 : * If the thread group leader exits before all other threads in the
1914 : * group, then poll(2) should block, similar to the wait(2) family.
1915 : */
1916 0 : if (thread_group_exited(pid))
1917 0 : poll_flags = EPOLLIN | EPOLLRDNORM;
1918 :
1919 0 : return poll_flags;
1920 : }
1921 :
1922 : const struct file_operations pidfd_fops = {
1923 : .release = pidfd_release,
1924 : .poll = pidfd_poll,
1925 : #ifdef CONFIG_PROC_FS
1926 : .show_fdinfo = pidfd_show_fdinfo,
1927 : #endif
1928 : };
1929 :
1930 : static void __delayed_free_task(struct rcu_head *rhp)
1931 : {
1932 : struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1933 :
1934 : free_task(tsk);
1935 : }
1936 :
1937 : static __always_inline void delayed_free_task(struct task_struct *tsk)
1938 : {
1939 : if (IS_ENABLED(CONFIG_MEMCG))
1940 : call_rcu(&tsk->rcu, __delayed_free_task);
1941 : else
1942 0 : free_task(tsk);
1943 : }
1944 :
1945 107 : static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1946 : {
1947 : /* Skip if kernel thread */
1948 107 : if (!tsk->mm)
1949 : return;
1950 :
1951 : /* Skip if spawning a thread or using vfork */
1952 0 : if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1953 : return;
1954 :
1955 : /* We need to synchronize with __set_oom_adj */
1956 0 : mutex_lock(&oom_adj_mutex);
1957 0 : set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1958 : /* Update the values in case they were changed after copy_signal */
1959 0 : tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1960 0 : tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1961 0 : mutex_unlock(&oom_adj_mutex);
1962 : }
1963 :
1964 : /*
1965 : * This creates a new process as a copy of the old one,
1966 : * but does not actually start it yet.
1967 : *
1968 : * It copies the registers, and all the appropriate
1969 : * parts of the process environment (as per the clone
1970 : * flags). The actual kick-off is left to the caller.
1971 : */
1972 107 : static __latent_entropy struct task_struct *copy_process(
1973 : struct pid *pid,
1974 : int trace,
1975 : int node,
1976 : struct kernel_clone_args *args)
1977 : {
1978 107 : int pidfd = -1, retval;
1979 : struct task_struct *p;
1980 : struct multiprocess_signals delayed;
1981 107 : struct file *pidfile = NULL;
1982 107 : u64 clone_flags = args->flags;
1983 107 : struct nsproxy *nsp = current->nsproxy;
1984 :
1985 : /*
1986 : * Don't allow sharing the root directory with processes in a different
1987 : * namespace
1988 : */
1989 107 : if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1990 : return ERR_PTR(-EINVAL);
1991 :
1992 107 : if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1993 : return ERR_PTR(-EINVAL);
1994 :
1995 : /*
1996 : * Thread groups must share signals as well, and detached threads
1997 : * can only be started up within the thread group.
1998 : */
1999 107 : if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2000 : return ERR_PTR(-EINVAL);
2001 :
2002 : /*
2003 : * Shared signal handlers imply shared VM. By way of the above,
2004 : * thread groups also imply shared VM. Blocking this case allows
2005 : * for various simplifications in other code.
2006 : */
2007 107 : if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2008 : return ERR_PTR(-EINVAL);
2009 :
2010 : /*
2011 : * Siblings of global init remain as zombies on exit since they are
2012 : * not reaped by their parent (swapper). To solve this and to avoid
2013 : * multi-rooted process trees, prevent global and container-inits
2014 : * from creating siblings.
2015 : */
2016 107 : if ((clone_flags & CLONE_PARENT) &&
2017 0 : current->signal->flags & SIGNAL_UNKILLABLE)
2018 : return ERR_PTR(-EINVAL);
2019 :
2020 : /*
2021 : * If the new process will be in a different pid or user namespace
2022 : * do not allow it to share a thread group with the forking task.
2023 : */
2024 107 : if (clone_flags & CLONE_THREAD) {
2025 0 : if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2026 0 : (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2027 : return ERR_PTR(-EINVAL);
2028 : }
2029 :
2030 : /*
2031 : * If the new process will be in a different time namespace
2032 : * do not allow it to share VM or a thread group with the forking task.
2033 : */
2034 107 : if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
2035 107 : if (nsp->time_ns != nsp->time_ns_for_children)
2036 : return ERR_PTR(-EINVAL);
2037 : }
2038 :
2039 107 : if (clone_flags & CLONE_PIDFD) {
2040 : /*
2041 : * - CLONE_DETACHED is blocked so that we can potentially
2042 : * reuse it later for CLONE_PIDFD.
2043 : * - CLONE_THREAD is blocked until someone really needs it.
2044 : */
2045 0 : if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
2046 : return ERR_PTR(-EINVAL);
2047 : }
2048 :
2049 : /*
2050 : * Force any signals received before this point to be delivered
2051 : * before the fork happens. Collect up signals sent to multiple
2052 : * processes that happen during the fork and delay them so that
2053 : * they appear to happen after the fork.
2054 : */
2055 107 : sigemptyset(&delayed.signal);
2056 107 : INIT_HLIST_NODE(&delayed.node);
2057 :
2058 214 : spin_lock_irq(¤t->sighand->siglock);
2059 107 : if (!(clone_flags & CLONE_THREAD))
2060 107 : hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2061 107 : recalc_sigpending();
2062 214 : spin_unlock_irq(¤t->sighand->siglock);
2063 107 : retval = -ERESTARTNOINTR;
2064 214 : if (task_sigpending(current))
2065 : goto fork_out;
2066 :
2067 107 : retval = -ENOMEM;
2068 107 : p = dup_task_struct(current, node);
2069 107 : if (!p)
2070 : goto fork_out;
2071 107 : if (args->io_thread) {
2072 : /*
2073 : * Mark us an IO worker, and block any signal that isn't
2074 : * fatal or STOP
2075 : */
2076 0 : p->flags |= PF_IO_WORKER;
2077 0 : siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2078 : }
2079 :
2080 107 : p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2081 : /*
2082 : * Clear TID on mm_release()?
2083 : */
2084 107 : p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2085 :
2086 107 : ftrace_graph_init_task(p);
2087 :
2088 107 : rt_mutex_init_task(p);
2089 :
2090 : lockdep_assert_irqs_enabled();
2091 : #ifdef CONFIG_PROVE_LOCKING
2092 : DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2093 : #endif
2094 107 : retval = copy_creds(p, clone_flags);
2095 107 : if (retval < 0)
2096 : goto bad_fork_free;
2097 :
2098 107 : retval = -EAGAIN;
2099 321 : if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2100 0 : if (p->real_cred->user != INIT_USER &&
2101 0 : !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2102 : goto bad_fork_cleanup_count;
2103 : }
2104 107 : current->flags &= ~PF_NPROC_EXCEEDED;
2105 :
2106 : /*
2107 : * If multiple threads are within copy_process(), then this check
2108 : * triggers too late. This doesn't hurt, the check is only there
2109 : * to stop root fork bombs.
2110 : */
2111 107 : retval = -EAGAIN;
2112 107 : if (data_race(nr_threads >= max_threads))
2113 : goto bad_fork_cleanup_count;
2114 :
2115 107 : delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2116 107 : p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2117 107 : p->flags |= PF_FORKNOEXEC;
2118 214 : INIT_LIST_HEAD(&p->children);
2119 214 : INIT_LIST_HEAD(&p->sibling);
2120 107 : rcu_copy_process(p);
2121 107 : p->vfork_done = NULL;
2122 107 : spin_lock_init(&p->alloc_lock);
2123 :
2124 214 : init_sigpending(&p->pending);
2125 :
2126 107 : p->utime = p->stime = p->gtime = 0;
2127 : #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2128 : p->utimescaled = p->stimescaled = 0;
2129 : #endif
2130 214 : prev_cputime_init(&p->prev_cputime);
2131 :
2132 : #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2133 : seqcount_init(&p->vtime.seqcount);
2134 : p->vtime.starttime = 0;
2135 : p->vtime.state = VTIME_INACTIVE;
2136 : #endif
2137 :
2138 : #ifdef CONFIG_IO_URING
2139 107 : p->io_uring = NULL;
2140 : #endif
2141 :
2142 : #if defined(SPLIT_RSS_COUNTING)
2143 : memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2144 : #endif
2145 :
2146 107 : p->default_timer_slack_ns = current->timer_slack_ns;
2147 :
2148 : #ifdef CONFIG_PSI
2149 : p->psi_flags = 0;
2150 : #endif
2151 :
2152 107 : task_io_accounting_init(&p->ioac);
2153 107 : acct_clear_integrals(p);
2154 :
2155 214 : posix_cputimers_init(&p->posix_cputimers);
2156 :
2157 107 : p->io_context = NULL;
2158 107 : audit_set_context(p, NULL);
2159 107 : cgroup_fork(p);
2160 107 : if (p->flags & PF_KTHREAD) {
2161 107 : if (!set_kthread_struct(p))
2162 : goto bad_fork_cleanup_delayacct;
2163 : }
2164 : #ifdef CONFIG_NUMA
2165 : p->mempolicy = mpol_dup(p->mempolicy);
2166 : if (IS_ERR(p->mempolicy)) {
2167 : retval = PTR_ERR(p->mempolicy);
2168 : p->mempolicy = NULL;
2169 : goto bad_fork_cleanup_delayacct;
2170 : }
2171 : #endif
2172 : #ifdef CONFIG_CPUSETS
2173 : p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2174 : p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2175 : seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2176 : #endif
2177 : #ifdef CONFIG_TRACE_IRQFLAGS
2178 : memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2179 : p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2180 : p->irqtrace.softirq_enable_ip = _THIS_IP_;
2181 : p->softirqs_enabled = 1;
2182 : p->softirq_context = 0;
2183 : #endif
2184 :
2185 107 : p->pagefault_disabled = 0;
2186 :
2187 : #ifdef CONFIG_LOCKDEP
2188 : lockdep_init_task(p);
2189 : #endif
2190 :
2191 : #ifdef CONFIG_DEBUG_MUTEXES
2192 : p->blocked_on = NULL; /* not blocked yet */
2193 : #endif
2194 : #ifdef CONFIG_BCACHE
2195 : p->sequential_io = 0;
2196 : p->sequential_io_avg = 0;
2197 : #endif
2198 : #ifdef CONFIG_BPF_SYSCALL
2199 : RCU_INIT_POINTER(p->bpf_storage, NULL);
2200 : p->bpf_ctx = NULL;
2201 : #endif
2202 :
2203 : /* Perform scheduler related setup. Assign this task to a CPU. */
2204 107 : retval = sched_fork(clone_flags, p);
2205 107 : if (retval)
2206 : goto bad_fork_cleanup_policy;
2207 :
2208 107 : retval = perf_event_init_task(p, clone_flags);
2209 : if (retval)
2210 : goto bad_fork_cleanup_policy;
2211 107 : retval = audit_alloc(p);
2212 : if (retval)
2213 : goto bad_fork_cleanup_perf;
2214 : /* copy all the process information */
2215 107 : shm_init_task(p);
2216 107 : retval = security_task_alloc(p, clone_flags);
2217 : if (retval)
2218 : goto bad_fork_cleanup_audit;
2219 107 : retval = copy_semundo(clone_flags, p);
2220 : if (retval)
2221 : goto bad_fork_cleanup_security;
2222 107 : retval = copy_files(clone_flags, p);
2223 107 : if (retval)
2224 : goto bad_fork_cleanup_semundo;
2225 107 : retval = copy_fs(clone_flags, p);
2226 107 : if (retval)
2227 : goto bad_fork_cleanup_files;
2228 107 : retval = copy_sighand(clone_flags, p);
2229 107 : if (retval)
2230 : goto bad_fork_cleanup_fs;
2231 107 : retval = copy_signal(clone_flags, p);
2232 107 : if (retval)
2233 : goto bad_fork_cleanup_sighand;
2234 107 : retval = copy_mm(clone_flags, p);
2235 107 : if (retval)
2236 : goto bad_fork_cleanup_signal;
2237 107 : retval = copy_namespaces(clone_flags, p);
2238 107 : if (retval)
2239 : goto bad_fork_cleanup_mm;
2240 107 : retval = copy_io(clone_flags, p);
2241 107 : if (retval)
2242 : goto bad_fork_cleanup_namespaces;
2243 107 : retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls);
2244 107 : if (retval)
2245 : goto bad_fork_cleanup_io;
2246 :
2247 107 : stackleak_task_init(p);
2248 :
2249 107 : if (pid != &init_struct_pid) {
2250 107 : pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2251 : args->set_tid_size);
2252 107 : if (IS_ERR(pid)) {
2253 0 : retval = PTR_ERR(pid);
2254 0 : goto bad_fork_cleanup_thread;
2255 : }
2256 : }
2257 :
2258 : /*
2259 : * This has to happen after we've potentially unshared the file
2260 : * descriptor table (so that the pidfd doesn't leak into the child
2261 : * if the fd table isn't shared).
2262 : */
2263 107 : if (clone_flags & CLONE_PIDFD) {
2264 0 : retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2265 0 : if (retval < 0)
2266 : goto bad_fork_free_pid;
2267 :
2268 0 : pidfd = retval;
2269 :
2270 0 : pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2271 : O_RDWR | O_CLOEXEC);
2272 0 : if (IS_ERR(pidfile)) {
2273 0 : put_unused_fd(pidfd);
2274 0 : retval = PTR_ERR(pidfile);
2275 0 : goto bad_fork_free_pid;
2276 : }
2277 0 : get_pid(pid); /* held by pidfile now */
2278 :
2279 0 : retval = put_user(pidfd, args->pidfd);
2280 0 : if (retval)
2281 : goto bad_fork_put_pidfd;
2282 : }
2283 :
2284 : #ifdef CONFIG_BLOCK
2285 107 : p->plug = NULL;
2286 : #endif
2287 107 : futex_init_task(p);
2288 :
2289 : /*
2290 : * sigaltstack should be cleared when sharing the same VM
2291 : */
2292 107 : if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2293 : sas_ss_reset(p);
2294 :
2295 : /*
2296 : * Syscall tracing and stepping should be turned off in the
2297 : * child regardless of CLONE_PTRACE.
2298 : */
2299 107 : user_disable_single_step(p);
2300 214 : clear_task_syscall_work(p, SYSCALL_TRACE);
2301 : #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2302 : clear_task_syscall_work(p, SYSCALL_EMU);
2303 : #endif
2304 107 : clear_tsk_latency_tracing(p);
2305 :
2306 : /* ok, now we should be set up.. */
2307 107 : p->pid = pid_nr(pid);
2308 107 : if (clone_flags & CLONE_THREAD) {
2309 0 : p->group_leader = current->group_leader;
2310 0 : p->tgid = current->tgid;
2311 : } else {
2312 107 : p->group_leader = p;
2313 107 : p->tgid = p->pid;
2314 : }
2315 :
2316 107 : p->nr_dirtied = 0;
2317 107 : p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2318 107 : p->dirty_paused_when = 0;
2319 :
2320 107 : p->pdeath_signal = 0;
2321 214 : INIT_LIST_HEAD(&p->thread_group);
2322 107 : p->task_works = NULL;
2323 107 : clear_posix_cputimers_work(p);
2324 :
2325 : #ifdef CONFIG_KRETPROBES
2326 : p->kretprobe_instances.first = NULL;
2327 : #endif
2328 : #ifdef CONFIG_RETHOOK
2329 : p->rethooks.first = NULL;
2330 : #endif
2331 :
2332 : /*
2333 : * Ensure that the cgroup subsystem policies allow the new process to be
2334 : * forked. It should be noted that the new process's css_set can be changed
2335 : * between here and cgroup_post_fork() if an organisation operation is in
2336 : * progress.
2337 : */
2338 107 : retval = cgroup_can_fork(p, args);
2339 : if (retval)
2340 : goto bad_fork_put_pidfd;
2341 :
2342 : /*
2343 : * Now that the cgroups are pinned, re-clone the parent cgroup and put
2344 : * the new task on the correct runqueue. All this *before* the task
2345 : * becomes visible.
2346 : *
2347 : * This isn't part of ->can_fork() because while the re-cloning is
2348 : * cgroup specific, it unconditionally needs to place the task on a
2349 : * runqueue.
2350 : */
2351 107 : sched_cgroup_fork(p, args);
2352 :
2353 : /*
2354 : * From this point on we must avoid any synchronous user-space
2355 : * communication until we take the tasklist-lock. In particular, we do
2356 : * not want user-space to be able to predict the process start-time by
2357 : * stalling fork(2) after we recorded the start_time but before it is
2358 : * visible to the system.
2359 : */
2360 :
2361 107 : p->start_time = ktime_get_ns();
2362 107 : p->start_boottime = ktime_get_boottime_ns();
2363 :
2364 : /*
2365 : * Make it visible to the rest of the system, but dont wake it up yet.
2366 : * Need tasklist lock for parent etc handling!
2367 : */
2368 107 : write_lock_irq(&tasklist_lock);
2369 :
2370 : /* CLONE_PARENT re-uses the old parent */
2371 107 : if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2372 0 : p->real_parent = current->real_parent;
2373 0 : p->parent_exec_id = current->parent_exec_id;
2374 0 : if (clone_flags & CLONE_THREAD)
2375 0 : p->exit_signal = -1;
2376 : else
2377 0 : p->exit_signal = current->group_leader->exit_signal;
2378 : } else {
2379 107 : p->real_parent = current;
2380 107 : p->parent_exec_id = current->self_exec_id;
2381 107 : p->exit_signal = args->exit_signal;
2382 : }
2383 :
2384 107 : klp_copy_process(p);
2385 :
2386 107 : sched_core_fork(p);
2387 :
2388 214 : spin_lock(¤t->sighand->siglock);
2389 :
2390 : /*
2391 : * Copy seccomp details explicitly here, in case they were changed
2392 : * before holding sighand lock.
2393 : */
2394 107 : copy_seccomp(p);
2395 :
2396 107 : rseq_fork(p, clone_flags);
2397 :
2398 : /* Don't start children in a dying pid namespace */
2399 107 : if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2400 : retval = -ENOMEM;
2401 : goto bad_fork_cancel_cgroup;
2402 : }
2403 :
2404 : /* Let kill terminate clone/fork in the middle */
2405 214 : if (fatal_signal_pending(current)) {
2406 : retval = -EINTR;
2407 : goto bad_fork_cancel_cgroup;
2408 : }
2409 :
2410 107 : init_task_pid_links(p);
2411 107 : if (likely(p->pid)) {
2412 107 : ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2413 :
2414 214 : init_task_pid(p, PIDTYPE_PID, pid);
2415 107 : if (thread_group_leader(p)) {
2416 214 : init_task_pid(p, PIDTYPE_TGID, pid);
2417 321 : init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2418 321 : init_task_pid(p, PIDTYPE_SID, task_session(current));
2419 :
2420 107 : if (is_child_reaper(pid)) {
2421 1 : ns_of_pid(pid)->child_reaper = p;
2422 1 : p->signal->flags |= SIGNAL_UNKILLABLE;
2423 : }
2424 107 : p->signal->shared_pending.signal = delayed.signal;
2425 321 : p->signal->tty = tty_kref_get(current->signal->tty);
2426 : /*
2427 : * Inherit has_child_subreaper flag under the same
2428 : * tasklist_lock with adding child to the process tree
2429 : * for propagate_has_child_subreaper optimization.
2430 : */
2431 107 : p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2432 : p->real_parent->signal->is_child_subreaper;
2433 214 : list_add_tail(&p->sibling, &p->real_parent->children);
2434 214 : list_add_tail_rcu(&p->tasks, &init_task.tasks);
2435 107 : attach_pid(p, PIDTYPE_TGID);
2436 107 : attach_pid(p, PIDTYPE_PGID);
2437 107 : attach_pid(p, PIDTYPE_SID);
2438 107 : __this_cpu_inc(process_counts);
2439 : } else {
2440 0 : current->signal->nr_threads++;
2441 0 : atomic_inc(¤t->signal->live);
2442 0 : refcount_inc(¤t->signal->sigcnt);
2443 0 : task_join_group_stop(p);
2444 0 : list_add_tail_rcu(&p->thread_group,
2445 0 : &p->group_leader->thread_group);
2446 0 : list_add_tail_rcu(&p->thread_node,
2447 0 : &p->signal->thread_head);
2448 : }
2449 107 : attach_pid(p, PIDTYPE_PID);
2450 107 : nr_threads++;
2451 : }
2452 107 : total_forks++;
2453 107 : hlist_del_init(&delayed.node);
2454 214 : spin_unlock(¤t->sighand->siglock);
2455 107 : syscall_tracepoint_update(p);
2456 107 : write_unlock_irq(&tasklist_lock);
2457 :
2458 107 : if (pidfile)
2459 0 : fd_install(pidfd, pidfile);
2460 :
2461 107 : proc_fork_connector(p);
2462 107 : sched_post_fork(p);
2463 107 : cgroup_post_fork(p, args);
2464 107 : perf_event_fork(p);
2465 :
2466 107 : trace_task_newtask(p, clone_flags);
2467 107 : uprobe_copy_process(p, clone_flags);
2468 :
2469 107 : copy_oom_score_adj(clone_flags, p);
2470 :
2471 107 : return p;
2472 :
2473 : bad_fork_cancel_cgroup:
2474 0 : sched_core_free(p);
2475 0 : spin_unlock(¤t->sighand->siglock);
2476 0 : write_unlock_irq(&tasklist_lock);
2477 0 : cgroup_cancel_fork(p, args);
2478 : bad_fork_put_pidfd:
2479 0 : if (clone_flags & CLONE_PIDFD) {
2480 0 : fput(pidfile);
2481 0 : put_unused_fd(pidfd);
2482 : }
2483 : bad_fork_free_pid:
2484 0 : if (pid != &init_struct_pid)
2485 0 : free_pid(pid);
2486 : bad_fork_cleanup_thread:
2487 : exit_thread(p);
2488 : bad_fork_cleanup_io:
2489 0 : if (p->io_context)
2490 0 : exit_io_context(p);
2491 : bad_fork_cleanup_namespaces:
2492 0 : exit_task_namespaces(p);
2493 : bad_fork_cleanup_mm:
2494 0 : if (p->mm) {
2495 0 : mm_clear_owner(p->mm, p);
2496 0 : mmput(p->mm);
2497 : }
2498 : bad_fork_cleanup_signal:
2499 0 : if (!(clone_flags & CLONE_THREAD))
2500 0 : free_signal_struct(p->signal);
2501 : bad_fork_cleanup_sighand:
2502 0 : __cleanup_sighand(p->sighand);
2503 : bad_fork_cleanup_fs:
2504 0 : exit_fs(p); /* blocking */
2505 : bad_fork_cleanup_files:
2506 0 : exit_files(p); /* blocking */
2507 : bad_fork_cleanup_semundo:
2508 : exit_sem(p);
2509 : bad_fork_cleanup_security:
2510 : security_task_free(p);
2511 : bad_fork_cleanup_audit:
2512 : audit_free(p);
2513 : bad_fork_cleanup_perf:
2514 : perf_event_free_task(p);
2515 : bad_fork_cleanup_policy:
2516 : lockdep_free_task(p);
2517 : #ifdef CONFIG_NUMA
2518 : mpol_put(p->mempolicy);
2519 : #endif
2520 : bad_fork_cleanup_delayacct:
2521 : delayacct_tsk_free(p);
2522 : bad_fork_cleanup_count:
2523 0 : dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2524 0 : exit_creds(p);
2525 : bad_fork_free:
2526 0 : WRITE_ONCE(p->__state, TASK_DEAD);
2527 0 : exit_task_stack_account(p);
2528 0 : put_task_stack(p);
2529 : delayed_free_task(p);
2530 : fork_out:
2531 0 : spin_lock_irq(¤t->sighand->siglock);
2532 0 : hlist_del_init(&delayed.node);
2533 0 : spin_unlock_irq(¤t->sighand->siglock);
2534 0 : return ERR_PTR(retval);
2535 : }
2536 :
2537 : static inline void init_idle_pids(struct task_struct *idle)
2538 : {
2539 : enum pid_type type;
2540 :
2541 0 : for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2542 0 : INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2543 0 : init_task_pid(idle, type, &init_struct_pid);
2544 : }
2545 : }
2546 :
2547 0 : struct task_struct * __init fork_idle(int cpu)
2548 : {
2549 : struct task_struct *task;
2550 0 : struct kernel_clone_args args = {
2551 : .flags = CLONE_VM,
2552 : };
2553 :
2554 0 : task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2555 0 : if (!IS_ERR(task)) {
2556 0 : init_idle_pids(task);
2557 0 : init_idle(task, cpu);
2558 : }
2559 :
2560 0 : return task;
2561 : }
2562 :
2563 0 : struct mm_struct *copy_init_mm(void)
2564 : {
2565 0 : return dup_mm(NULL, &init_mm);
2566 : }
2567 :
2568 : /*
2569 : * This is like kernel_clone(), but shaved down and tailored to just
2570 : * creating io_uring workers. It returns a created task, or an error pointer.
2571 : * The returned task is inactive, and the caller must fire it up through
2572 : * wake_up_new_task(p). All signals are blocked in the created task.
2573 : */
2574 0 : struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2575 : {
2576 0 : unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2577 : CLONE_IO;
2578 0 : struct kernel_clone_args args = {
2579 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2580 : CLONE_UNTRACED) & ~CSIGNAL),
2581 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2582 0 : .stack = (unsigned long)fn,
2583 0 : .stack_size = (unsigned long)arg,
2584 : .io_thread = 1,
2585 : };
2586 :
2587 0 : return copy_process(NULL, 0, node, &args);
2588 : }
2589 :
2590 : /*
2591 : * Ok, this is the main fork-routine.
2592 : *
2593 : * It copies the process, and if successful kick-starts
2594 : * it and waits for it to finish using the VM if required.
2595 : *
2596 : * args->exit_signal is expected to be checked for sanity by the caller.
2597 : */
2598 107 : pid_t kernel_clone(struct kernel_clone_args *args)
2599 : {
2600 107 : u64 clone_flags = args->flags;
2601 : struct completion vfork;
2602 : struct pid *pid;
2603 : struct task_struct *p;
2604 107 : int trace = 0;
2605 : pid_t nr;
2606 :
2607 : /*
2608 : * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2609 : * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2610 : * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2611 : * field in struct clone_args and it still doesn't make sense to have
2612 : * them both point at the same memory location. Performing this check
2613 : * here has the advantage that we don't need to have a separate helper
2614 : * to check for legacy clone().
2615 : */
2616 107 : if ((args->flags & CLONE_PIDFD) &&
2617 0 : (args->flags & CLONE_PARENT_SETTID) &&
2618 0 : (args->pidfd == args->parent_tid))
2619 : return -EINVAL;
2620 :
2621 : /*
2622 : * Determine whether and which event to report to ptracer. When
2623 : * called from kernel_thread or CLONE_UNTRACED is explicitly
2624 : * requested, no event is reported; otherwise, report if the event
2625 : * for the type of forking is enabled.
2626 : */
2627 107 : if (!(clone_flags & CLONE_UNTRACED)) {
2628 0 : if (clone_flags & CLONE_VFORK)
2629 : trace = PTRACE_EVENT_VFORK;
2630 0 : else if (args->exit_signal != SIGCHLD)
2631 : trace = PTRACE_EVENT_CLONE;
2632 : else
2633 0 : trace = PTRACE_EVENT_FORK;
2634 :
2635 0 : if (likely(!ptrace_event_enabled(current, trace)))
2636 0 : trace = 0;
2637 : }
2638 :
2639 107 : p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2640 107 : add_latent_entropy();
2641 :
2642 107 : if (IS_ERR(p))
2643 0 : return PTR_ERR(p);
2644 :
2645 : /*
2646 : * Do this prior waking up the new thread - the thread pointer
2647 : * might get invalid after that point, if the thread exits quickly.
2648 : */
2649 107 : trace_sched_process_fork(current, p);
2650 :
2651 107 : pid = get_task_pid(p, PIDTYPE_PID);
2652 107 : nr = pid_vnr(pid);
2653 :
2654 107 : if (clone_flags & CLONE_PARENT_SETTID)
2655 0 : put_user(nr, args->parent_tid);
2656 :
2657 107 : if (clone_flags & CLONE_VFORK) {
2658 0 : p->vfork_done = &vfork;
2659 0 : init_completion(&vfork);
2660 : get_task_struct(p);
2661 : }
2662 :
2663 107 : wake_up_new_task(p);
2664 :
2665 : /* forking complete and child started to run, tell ptracer */
2666 107 : if (unlikely(trace))
2667 0 : ptrace_event_pid(trace, pid);
2668 :
2669 107 : if (clone_flags & CLONE_VFORK) {
2670 0 : if (!wait_for_vfork_done(p, &vfork))
2671 0 : ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2672 : }
2673 :
2674 107 : put_pid(pid);
2675 107 : return nr;
2676 : }
2677 :
2678 : /*
2679 : * Create a kernel thread.
2680 : */
2681 107 : pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2682 : {
2683 535 : struct kernel_clone_args args = {
2684 107 : .flags = ((lower_32_bits(flags) | CLONE_VM |
2685 107 : CLONE_UNTRACED) & ~CSIGNAL),
2686 107 : .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2687 107 : .stack = (unsigned long)fn,
2688 107 : .stack_size = (unsigned long)arg,
2689 : };
2690 :
2691 107 : return kernel_clone(&args);
2692 : }
2693 :
2694 : #ifdef __ARCH_WANT_SYS_FORK
2695 0 : SYSCALL_DEFINE0(fork)
2696 : {
2697 : #ifdef CONFIG_MMU
2698 0 : struct kernel_clone_args args = {
2699 : .exit_signal = SIGCHLD,
2700 : };
2701 :
2702 0 : return kernel_clone(&args);
2703 : #else
2704 : /* can not support in nommu mode */
2705 : return -EINVAL;
2706 : #endif
2707 : }
2708 : #endif
2709 :
2710 : #ifdef __ARCH_WANT_SYS_VFORK
2711 0 : SYSCALL_DEFINE0(vfork)
2712 : {
2713 0 : struct kernel_clone_args args = {
2714 : .flags = CLONE_VFORK | CLONE_VM,
2715 : .exit_signal = SIGCHLD,
2716 : };
2717 :
2718 0 : return kernel_clone(&args);
2719 : }
2720 : #endif
2721 :
2722 : #ifdef __ARCH_WANT_SYS_CLONE
2723 : #ifdef CONFIG_CLONE_BACKWARDS
2724 : SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2725 : int __user *, parent_tidptr,
2726 : unsigned long, tls,
2727 : int __user *, child_tidptr)
2728 : #elif defined(CONFIG_CLONE_BACKWARDS2)
2729 : SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2730 : int __user *, parent_tidptr,
2731 : int __user *, child_tidptr,
2732 : unsigned long, tls)
2733 : #elif defined(CONFIG_CLONE_BACKWARDS3)
2734 : SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2735 : int, stack_size,
2736 : int __user *, parent_tidptr,
2737 : int __user *, child_tidptr,
2738 : unsigned long, tls)
2739 : #else
2740 0 : SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2741 : int __user *, parent_tidptr,
2742 : int __user *, child_tidptr,
2743 : unsigned long, tls)
2744 : #endif
2745 : {
2746 0 : struct kernel_clone_args args = {
2747 0 : .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2748 : .pidfd = parent_tidptr,
2749 : .child_tid = child_tidptr,
2750 : .parent_tid = parent_tidptr,
2751 0 : .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2752 : .stack = newsp,
2753 : .tls = tls,
2754 : };
2755 :
2756 0 : return kernel_clone(&args);
2757 : }
2758 : #endif
2759 :
2760 : #ifdef __ARCH_WANT_SYS_CLONE3
2761 :
2762 0 : noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2763 : struct clone_args __user *uargs,
2764 : size_t usize)
2765 : {
2766 : int err;
2767 : struct clone_args args;
2768 0 : pid_t *kset_tid = kargs->set_tid;
2769 :
2770 : BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2771 : CLONE_ARGS_SIZE_VER0);
2772 : BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2773 : CLONE_ARGS_SIZE_VER1);
2774 : BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2775 : CLONE_ARGS_SIZE_VER2);
2776 : BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2777 :
2778 0 : if (unlikely(usize > PAGE_SIZE))
2779 : return -E2BIG;
2780 0 : if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2781 : return -EINVAL;
2782 :
2783 0 : err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2784 0 : if (err)
2785 : return err;
2786 :
2787 0 : if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2788 : return -EINVAL;
2789 :
2790 0 : if (unlikely(!args.set_tid && args.set_tid_size > 0))
2791 : return -EINVAL;
2792 :
2793 0 : if (unlikely(args.set_tid && args.set_tid_size == 0))
2794 : return -EINVAL;
2795 :
2796 : /*
2797 : * Verify that higher 32bits of exit_signal are unset and that
2798 : * it is a valid signal
2799 : */
2800 0 : if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2801 : !valid_signal(args.exit_signal)))
2802 : return -EINVAL;
2803 :
2804 0 : if ((args.flags & CLONE_INTO_CGROUP) &&
2805 0 : (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2806 : return -EINVAL;
2807 :
2808 0 : *kargs = (struct kernel_clone_args){
2809 : .flags = args.flags,
2810 0 : .pidfd = u64_to_user_ptr(args.pidfd),
2811 0 : .child_tid = u64_to_user_ptr(args.child_tid),
2812 0 : .parent_tid = u64_to_user_ptr(args.parent_tid),
2813 : .exit_signal = args.exit_signal,
2814 0 : .stack = args.stack,
2815 0 : .stack_size = args.stack_size,
2816 0 : .tls = args.tls,
2817 : .set_tid_size = args.set_tid_size,
2818 0 : .cgroup = args.cgroup,
2819 : };
2820 :
2821 0 : if (args.set_tid &&
2822 0 : copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
2823 : (kargs->set_tid_size * sizeof(pid_t))))
2824 : return -EFAULT;
2825 :
2826 0 : kargs->set_tid = kset_tid;
2827 :
2828 0 : return 0;
2829 : }
2830 :
2831 : /**
2832 : * clone3_stack_valid - check and prepare stack
2833 : * @kargs: kernel clone args
2834 : *
2835 : * Verify that the stack arguments userspace gave us are sane.
2836 : * In addition, set the stack direction for userspace since it's easy for us to
2837 : * determine.
2838 : */
2839 0 : static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
2840 : {
2841 0 : if (kargs->stack == 0) {
2842 0 : if (kargs->stack_size > 0)
2843 : return false;
2844 : } else {
2845 0 : if (kargs->stack_size == 0)
2846 : return false;
2847 :
2848 0 : if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
2849 : return false;
2850 :
2851 : #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2852 0 : kargs->stack += kargs->stack_size;
2853 : #endif
2854 : }
2855 :
2856 : return true;
2857 : }
2858 :
2859 0 : static bool clone3_args_valid(struct kernel_clone_args *kargs)
2860 : {
2861 : /* Verify that no unknown flags are passed along. */
2862 0 : if (kargs->flags &
2863 : ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
2864 : return false;
2865 :
2866 : /*
2867 : * - make the CLONE_DETACHED bit reusable for clone3
2868 : * - make the CSIGNAL bits reusable for clone3
2869 : */
2870 0 : if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
2871 : return false;
2872 :
2873 0 : if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
2874 : (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
2875 : return false;
2876 :
2877 0 : if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
2878 0 : kargs->exit_signal)
2879 : return false;
2880 :
2881 0 : if (!clone3_stack_valid(kargs))
2882 : return false;
2883 :
2884 0 : return true;
2885 : }
2886 :
2887 : /**
2888 : * clone3 - create a new process with specific properties
2889 : * @uargs: argument structure
2890 : * @size: size of @uargs
2891 : *
2892 : * clone3() is the extensible successor to clone()/clone2().
2893 : * It takes a struct as argument that is versioned by its size.
2894 : *
2895 : * Return: On success, a positive PID for the child process.
2896 : * On error, a negative errno number.
2897 : */
2898 0 : SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
2899 : {
2900 : int err;
2901 :
2902 : struct kernel_clone_args kargs;
2903 : pid_t set_tid[MAX_PID_NS_LEVEL];
2904 :
2905 0 : kargs.set_tid = set_tid;
2906 :
2907 0 : err = copy_clone_args_from_user(&kargs, uargs, size);
2908 0 : if (err)
2909 0 : return err;
2910 :
2911 0 : if (!clone3_args_valid(&kargs))
2912 : return -EINVAL;
2913 :
2914 0 : return kernel_clone(&kargs);
2915 : }
2916 : #endif
2917 :
2918 0 : void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2919 : {
2920 : struct task_struct *leader, *parent, *child;
2921 : int res;
2922 :
2923 0 : read_lock(&tasklist_lock);
2924 0 : leader = top = top->group_leader;
2925 : down:
2926 0 : for_each_thread(leader, parent) {
2927 0 : list_for_each_entry(child, &parent->children, sibling) {
2928 0 : res = visitor(child, data);
2929 0 : if (res) {
2930 0 : if (res < 0)
2931 : goto out;
2932 : leader = child;
2933 : goto down;
2934 : }
2935 : up:
2936 : ;
2937 : }
2938 : }
2939 :
2940 0 : if (leader != top) {
2941 0 : child = leader;
2942 0 : parent = child->real_parent;
2943 0 : leader = parent->group_leader;
2944 0 : goto up;
2945 : }
2946 : out:
2947 0 : read_unlock(&tasklist_lock);
2948 0 : }
2949 :
2950 : #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2951 : #define ARCH_MIN_MMSTRUCT_ALIGN 0
2952 : #endif
2953 :
2954 15 : static void sighand_ctor(void *data)
2955 : {
2956 15 : struct sighand_struct *sighand = data;
2957 :
2958 15 : spin_lock_init(&sighand->siglock);
2959 15 : init_waitqueue_head(&sighand->signalfd_wqh);
2960 15 : }
2961 :
2962 1 : void __init proc_caches_init(void)
2963 : {
2964 : unsigned int mm_size;
2965 :
2966 1 : sighand_cachep = kmem_cache_create("sighand_cache",
2967 : sizeof(struct sighand_struct), 0,
2968 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2969 : SLAB_ACCOUNT, sighand_ctor);
2970 1 : signal_cachep = kmem_cache_create("signal_cache",
2971 : sizeof(struct signal_struct), 0,
2972 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2973 : NULL);
2974 1 : files_cachep = kmem_cache_create("files_cache",
2975 : sizeof(struct files_struct), 0,
2976 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2977 : NULL);
2978 1 : fs_cachep = kmem_cache_create("fs_cache",
2979 : sizeof(struct fs_struct), 0,
2980 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2981 : NULL);
2982 :
2983 : /*
2984 : * The mm_cpumask is located at the end of mm_struct, and is
2985 : * dynamically sized based on the maximum CPU number this system
2986 : * can have, taking hotplug into account (nr_cpu_ids).
2987 : */
2988 1 : mm_size = sizeof(struct mm_struct) + cpumask_size();
2989 :
2990 1 : mm_cachep = kmem_cache_create_usercopy("mm_struct",
2991 : mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
2992 : SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2993 : offsetof(struct mm_struct, saved_auxv),
2994 : sizeof_field(struct mm_struct, saved_auxv),
2995 : NULL);
2996 1 : vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
2997 1 : mmap_init();
2998 1 : nsproxy_cache_init();
2999 1 : }
3000 :
3001 : /*
3002 : * Check constraints on flags passed to the unshare system call.
3003 : */
3004 0 : static int check_unshare_flags(unsigned long unshare_flags)
3005 : {
3006 0 : if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3007 : CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3008 : CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3009 : CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3010 : CLONE_NEWTIME))
3011 : return -EINVAL;
3012 : /*
3013 : * Not implemented, but pretend it works if there is nothing
3014 : * to unshare. Note that unsharing the address space or the
3015 : * signal handlers also need to unshare the signal queues (aka
3016 : * CLONE_THREAD).
3017 : */
3018 0 : if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3019 0 : if (!thread_group_empty(current))
3020 : return -EINVAL;
3021 : }
3022 0 : if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3023 0 : if (refcount_read(¤t->sighand->count) > 1)
3024 : return -EINVAL;
3025 : }
3026 0 : if (unshare_flags & CLONE_VM) {
3027 0 : if (!current_is_single_threaded())
3028 : return -EINVAL;
3029 : }
3030 :
3031 : return 0;
3032 : }
3033 :
3034 : /*
3035 : * Unshare the filesystem structure if it is being shared
3036 : */
3037 0 : static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3038 : {
3039 0 : struct fs_struct *fs = current->fs;
3040 :
3041 0 : if (!(unshare_flags & CLONE_FS) || !fs)
3042 : return 0;
3043 :
3044 : /* don't need lock here; in the worst case we'll do useless copy */
3045 0 : if (fs->users == 1)
3046 : return 0;
3047 :
3048 0 : *new_fsp = copy_fs_struct(fs);
3049 0 : if (!*new_fsp)
3050 : return -ENOMEM;
3051 :
3052 0 : return 0;
3053 : }
3054 :
3055 : /*
3056 : * Unshare file descriptor table if it is being shared
3057 : */
3058 0 : int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3059 : struct files_struct **new_fdp)
3060 : {
3061 0 : struct files_struct *fd = current->files;
3062 0 : int error = 0;
3063 :
3064 0 : if ((unshare_flags & CLONE_FILES) &&
3065 0 : (fd && atomic_read(&fd->count) > 1)) {
3066 0 : *new_fdp = dup_fd(fd, max_fds, &error);
3067 0 : if (!*new_fdp)
3068 0 : return error;
3069 : }
3070 :
3071 : return 0;
3072 : }
3073 :
3074 : /*
3075 : * unshare allows a process to 'unshare' part of the process
3076 : * context which was originally shared using clone. copy_*
3077 : * functions used by kernel_clone() cannot be used here directly
3078 : * because they modify an inactive task_struct that is being
3079 : * constructed. Here we are modifying the current, active,
3080 : * task_struct.
3081 : */
3082 0 : int ksys_unshare(unsigned long unshare_flags)
3083 : {
3084 0 : struct fs_struct *fs, *new_fs = NULL;
3085 0 : struct files_struct *new_fd = NULL;
3086 0 : struct cred *new_cred = NULL;
3087 0 : struct nsproxy *new_nsproxy = NULL;
3088 0 : int do_sysvsem = 0;
3089 : int err;
3090 :
3091 : /*
3092 : * If unsharing a user namespace must also unshare the thread group
3093 : * and unshare the filesystem root and working directories.
3094 : */
3095 0 : if (unshare_flags & CLONE_NEWUSER)
3096 0 : unshare_flags |= CLONE_THREAD | CLONE_FS;
3097 : /*
3098 : * If unsharing vm, must also unshare signal handlers.
3099 : */
3100 0 : if (unshare_flags & CLONE_VM)
3101 0 : unshare_flags |= CLONE_SIGHAND;
3102 : /*
3103 : * If unsharing a signal handlers, must also unshare the signal queues.
3104 : */
3105 0 : if (unshare_flags & CLONE_SIGHAND)
3106 0 : unshare_flags |= CLONE_THREAD;
3107 : /*
3108 : * If unsharing namespace, must also unshare filesystem information.
3109 : */
3110 0 : if (unshare_flags & CLONE_NEWNS)
3111 0 : unshare_flags |= CLONE_FS;
3112 :
3113 0 : err = check_unshare_flags(unshare_flags);
3114 0 : if (err)
3115 : goto bad_unshare_out;
3116 : /*
3117 : * CLONE_NEWIPC must also detach from the undolist: after switching
3118 : * to a new ipc namespace, the semaphore arrays from the old
3119 : * namespace are unreachable.
3120 : */
3121 0 : if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3122 0 : do_sysvsem = 1;
3123 0 : err = unshare_fs(unshare_flags, &new_fs);
3124 0 : if (err)
3125 : goto bad_unshare_out;
3126 0 : err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3127 0 : if (err)
3128 : goto bad_unshare_cleanup_fs;
3129 0 : err = unshare_userns(unshare_flags, &new_cred);
3130 0 : if (err)
3131 : goto bad_unshare_cleanup_fd;
3132 0 : err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3133 : new_cred, new_fs);
3134 0 : if (err)
3135 : goto bad_unshare_cleanup_cred;
3136 :
3137 : if (new_cred) {
3138 : err = set_cred_ucounts(new_cred);
3139 : if (err)
3140 : goto bad_unshare_cleanup_cred;
3141 : }
3142 :
3143 0 : if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3144 0 : if (do_sysvsem) {
3145 : /*
3146 : * CLONE_SYSVSEM is equivalent to sys_exit().
3147 : */
3148 0 : exit_sem(current);
3149 : }
3150 0 : if (unshare_flags & CLONE_NEWIPC) {
3151 : /* Orphan segments in old ns (see sem above). */
3152 0 : exit_shm(current);
3153 0 : shm_init_task(current);
3154 : }
3155 :
3156 0 : if (new_nsproxy)
3157 0 : switch_task_namespaces(current, new_nsproxy);
3158 :
3159 0 : task_lock(current);
3160 :
3161 0 : if (new_fs) {
3162 0 : fs = current->fs;
3163 0 : spin_lock(&fs->lock);
3164 0 : current->fs = new_fs;
3165 0 : if (--fs->users)
3166 0 : new_fs = NULL;
3167 : else
3168 0 : new_fs = fs;
3169 0 : spin_unlock(&fs->lock);
3170 : }
3171 :
3172 0 : if (new_fd)
3173 0 : swap(current->files, new_fd);
3174 :
3175 0 : task_unlock(current);
3176 :
3177 : if (new_cred) {
3178 : /* Install the new user namespace */
3179 : commit_creds(new_cred);
3180 : new_cred = NULL;
3181 : }
3182 : }
3183 :
3184 0 : perf_event_namespaces(current);
3185 :
3186 : bad_unshare_cleanup_cred:
3187 : if (new_cred)
3188 : put_cred(new_cred);
3189 : bad_unshare_cleanup_fd:
3190 0 : if (new_fd)
3191 0 : put_files_struct(new_fd);
3192 :
3193 : bad_unshare_cleanup_fs:
3194 0 : if (new_fs)
3195 0 : free_fs_struct(new_fs);
3196 :
3197 : bad_unshare_out:
3198 0 : return err;
3199 : }
3200 :
3201 0 : SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3202 : {
3203 0 : return ksys_unshare(unshare_flags);
3204 : }
3205 :
3206 : /*
3207 : * Helper to unshare the files of the current task.
3208 : * We don't want to expose copy_files internals to
3209 : * the exec layer of the kernel.
3210 : */
3211 :
3212 0 : int unshare_files(void)
3213 : {
3214 0 : struct task_struct *task = current;
3215 0 : struct files_struct *old, *copy = NULL;
3216 : int error;
3217 :
3218 0 : error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3219 0 : if (error || !copy)
3220 : return error;
3221 :
3222 0 : old = task->files;
3223 0 : task_lock(task);
3224 0 : task->files = copy;
3225 0 : task_unlock(task);
3226 0 : put_files_struct(old);
3227 0 : return 0;
3228 : }
3229 :
3230 0 : int sysctl_max_threads(struct ctl_table *table, int write,
3231 : void *buffer, size_t *lenp, loff_t *ppos)
3232 : {
3233 : struct ctl_table t;
3234 : int ret;
3235 0 : int threads = max_threads;
3236 0 : int min = 1;
3237 0 : int max = MAX_THREADS;
3238 :
3239 0 : t = *table;
3240 0 : t.data = &threads;
3241 0 : t.extra1 = &min;
3242 0 : t.extra2 = &max;
3243 :
3244 0 : ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3245 0 : if (ret || !write)
3246 : return ret;
3247 :
3248 0 : max_threads = threads;
3249 :
3250 0 : return 0;
3251 : }
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