1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
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()'
15 #include <linux/anon_inodes.h>
16 #include <linux/slab.h>
17 #include <linux/sched/autogroup.h>
18 #include <linux/sched/mm.h>
19 #include <linux/sched/coredump.h>
20 #include <linux/sched/user.h>
21 #include <linux/sched/numa_balancing.h>
22 #include <linux/sched/stat.h>
23 #include <linux/sched/task.h>
24 #include <linux/sched/task_stack.h>
25 #include <linux/sched/cputime.h>
26 #include <linux/seq_file.h>
27 #include <linux/rtmutex.h>
28 #include <linux/init.h>
29 #include <linux/unistd.h>
30 #include <linux/module.h>
31 #include <linux/vmalloc.h>
32 #include <linux/completion.h>
33 #include <linux/personality.h>
34 #include <linux/mempolicy.h>
35 #include <linux/sem.h>
36 #include <linux/file.h>
37 #include <linux/fdtable.h>
38 #include <linux/iocontext.h>
39 #include <linux/key.h>
40 #include <linux/kmsan.h>
41 #include <linux/binfmts.h>
42 #include <linux/mman.h>
43 #include <linux/mmu_notifier.h>
46 #include <linux/mm_inline.h>
47 #include <linux/nsproxy.h>
48 #include <linux/capability.h>
49 #include <linux/cpu.h>
50 #include <linux/cgroup.h>
51 #include <linux/security.h>
52 #include <linux/hugetlb.h>
53 #include <linux/seccomp.h>
54 #include <linux/swap.h>
55 #include <linux/syscalls.h>
56 #include <linux/jiffies.h>
57 #include <linux/futex.h>
58 #include <linux/compat.h>
59 #include <linux/kthread.h>
60 #include <linux/task_io_accounting_ops.h>
61 #include <linux/rcupdate.h>
62 #include <linux/ptrace.h>
63 #include <linux/mount.h>
64 #include <linux/audit.h>
65 #include <linux/memcontrol.h>
66 #include <linux/ftrace.h>
67 #include <linux/proc_fs.h>
68 #include <linux/profile.h>
69 #include <linux/rmap.h>
70 #include <linux/ksm.h>
71 #include <linux/acct.h>
72 #include <linux/userfaultfd_k.h>
73 #include <linux/tsacct_kern.h>
74 #include <linux/cn_proc.h>
75 #include <linux/freezer.h>
76 #include <linux/delayacct.h>
77 #include <linux/taskstats_kern.h>
78 #include <linux/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>
101 #include <asm/pgalloc.h>
102 #include <linux/uaccess.h>
103 #include <asm/mmu_context.h>
104 #include <asm/cacheflush.h>
105 #include <asm/tlbflush.h>
107 #include <trace/events/sched.h>
109 #define CREATE_TRACE_POINTS
110 #include <trace/events/task.h>
113 * Minimum number of threads to boot the kernel
115 #define MIN_THREADS 20
118 * Maximum number of threads
120 #define MAX_THREADS FUTEX_TID_MASK
123 * Protected counters by write_lock_irq(&tasklist_lock)
125 unsigned long total_forks
; /* Handle normal Linux uptimes. */
126 int nr_threads
; /* The idle threads do not count.. */
128 static int max_threads
; /* tunable limit on nr_threads */
130 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
132 static const char * const resident_page_types
[] = {
133 NAMED_ARRAY_INDEX(MM_FILEPAGES
),
134 NAMED_ARRAY_INDEX(MM_ANONPAGES
),
135 NAMED_ARRAY_INDEX(MM_SWAPENTS
),
136 NAMED_ARRAY_INDEX(MM_SHMEMPAGES
),
139 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
141 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
143 #ifdef CONFIG_PROVE_RCU
144 int lockdep_tasklist_lock_is_held(void)
146 return lockdep_is_held(&tasklist_lock
);
148 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
149 #endif /* #ifdef CONFIG_PROVE_RCU */
151 int nr_processes(void)
156 for_each_possible_cpu(cpu
)
157 total
+= per_cpu(process_counts
, cpu
);
162 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
166 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
167 static struct kmem_cache
*task_struct_cachep
;
169 static inline struct task_struct
*alloc_task_struct_node(int node
)
171 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
174 static inline void free_task_struct(struct task_struct
*tsk
)
176 kmem_cache_free(task_struct_cachep
, tsk
);
180 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
183 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
184 * kmemcache based allocator.
186 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
188 # ifdef CONFIG_VMAP_STACK
190 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
191 * flush. Try to minimize the number of calls by caching stacks.
193 #define NR_CACHED_STACKS 2
194 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
198 struct vm_struct
*stack_vm_area
;
201 static bool try_release_thread_stack_to_cache(struct vm_struct
*vm
)
205 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
206 if (this_cpu_cmpxchg(cached_stacks
[i
], NULL
, vm
) != NULL
)
213 static void thread_stack_free_rcu(struct rcu_head
*rh
)
215 struct vm_stack
*vm_stack
= container_of(rh
, struct vm_stack
, rcu
);
217 if (try_release_thread_stack_to_cache(vm_stack
->stack_vm_area
))
223 static void thread_stack_delayed_free(struct task_struct
*tsk
)
225 struct vm_stack
*vm_stack
= tsk
->stack
;
227 vm_stack
->stack_vm_area
= tsk
->stack_vm_area
;
228 call_rcu(&vm_stack
->rcu
, thread_stack_free_rcu
);
231 static int free_vm_stack_cache(unsigned int cpu
)
233 struct vm_struct
**cached_vm_stacks
= per_cpu_ptr(cached_stacks
, cpu
);
236 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
237 struct vm_struct
*vm_stack
= cached_vm_stacks
[i
];
242 vfree(vm_stack
->addr
);
243 cached_vm_stacks
[i
] = NULL
;
249 static int memcg_charge_kernel_stack(struct vm_struct
*vm
)
254 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
255 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
257 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
258 ret
= memcg_kmem_charge_page(vm
->pages
[i
], GFP_KERNEL
, 0);
265 * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
266 * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
269 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
270 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
274 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
276 struct vm_struct
*vm
;
280 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
283 s
= this_cpu_xchg(cached_stacks
[i
], NULL
);
288 /* Reset stack metadata. */
289 kasan_unpoison_range(s
->addr
, THREAD_SIZE
);
291 stack
= kasan_reset_tag(s
->addr
);
293 /* Clear stale pointers from reused stack. */
294 memset(stack
, 0, THREAD_SIZE
);
296 if (memcg_charge_kernel_stack(s
)) {
301 tsk
->stack_vm_area
= s
;
307 * Allocated stacks are cached and later reused by new threads,
308 * so memcg accounting is performed manually on assigning/releasing
309 * stacks to tasks. Drop __GFP_ACCOUNT.
311 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_ALIGN
,
312 VMALLOC_START
, VMALLOC_END
,
313 THREADINFO_GFP
& ~__GFP_ACCOUNT
,
315 0, node
, __builtin_return_address(0));
319 vm
= find_vm_area(stack
);
320 if (memcg_charge_kernel_stack(vm
)) {
325 * We can't call find_vm_area() in interrupt context, and
326 * free_thread_stack() can be called in interrupt context,
327 * so cache the vm_struct.
329 tsk
->stack_vm_area
= vm
;
330 stack
= kasan_reset_tag(stack
);
335 static void free_thread_stack(struct task_struct
*tsk
)
337 if (!try_release_thread_stack_to_cache(tsk
->stack_vm_area
))
338 thread_stack_delayed_free(tsk
);
341 tsk
->stack_vm_area
= NULL
;
344 # else /* !CONFIG_VMAP_STACK */
346 static void thread_stack_free_rcu(struct rcu_head
*rh
)
348 __free_pages(virt_to_page(rh
), THREAD_SIZE_ORDER
);
351 static void thread_stack_delayed_free(struct task_struct
*tsk
)
353 struct rcu_head
*rh
= tsk
->stack
;
355 call_rcu(rh
, thread_stack_free_rcu
);
358 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
360 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
364 tsk
->stack
= kasan_reset_tag(page_address(page
));
370 static void free_thread_stack(struct task_struct
*tsk
)
372 thread_stack_delayed_free(tsk
);
376 # endif /* CONFIG_VMAP_STACK */
377 # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
379 static struct kmem_cache
*thread_stack_cache
;
381 static void thread_stack_free_rcu(struct rcu_head
*rh
)
383 kmem_cache_free(thread_stack_cache
, rh
);
386 static void thread_stack_delayed_free(struct task_struct
*tsk
)
388 struct rcu_head
*rh
= tsk
->stack
;
390 call_rcu(rh
, thread_stack_free_rcu
);
393 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
395 unsigned long *stack
;
396 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
397 stack
= kasan_reset_tag(stack
);
399 return stack
? 0 : -ENOMEM
;
402 static void free_thread_stack(struct task_struct
*tsk
)
404 thread_stack_delayed_free(tsk
);
408 void thread_stack_cache_init(void)
410 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
411 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
413 BUG_ON(thread_stack_cache
== NULL
);
416 # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
417 #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
419 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
421 unsigned long *stack
;
423 stack
= arch_alloc_thread_stack_node(tsk
, node
);
425 return stack
? 0 : -ENOMEM
;
428 static void free_thread_stack(struct task_struct
*tsk
)
430 arch_free_thread_stack(tsk
);
434 #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
436 /* SLAB cache for signal_struct structures (tsk->signal) */
437 static struct kmem_cache
*signal_cachep
;
439 /* SLAB cache for sighand_struct structures (tsk->sighand) */
440 struct kmem_cache
*sighand_cachep
;
442 /* SLAB cache for files_struct structures (tsk->files) */
443 struct kmem_cache
*files_cachep
;
445 /* SLAB cache for fs_struct structures (tsk->fs) */
446 struct kmem_cache
*fs_cachep
;
448 /* SLAB cache for vm_area_struct structures */
449 static struct kmem_cache
*vm_area_cachep
;
451 /* SLAB cache for mm_struct structures (tsk->mm) */
452 static struct kmem_cache
*mm_cachep
;
454 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
456 struct vm_area_struct
*vma
;
458 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
464 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
466 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
469 ASSERT_EXCLUSIVE_WRITER(orig
->vm_flags
);
470 ASSERT_EXCLUSIVE_WRITER(orig
->vm_file
);
472 * orig->shared.rb may be modified concurrently, but the clone
473 * will be reinitialized.
475 *new = data_race(*orig
);
476 INIT_LIST_HEAD(&new->anon_vma_chain
);
477 dup_anon_vma_name(orig
, new);
482 void vm_area_free(struct vm_area_struct
*vma
)
484 free_anon_vma_name(vma
);
485 kmem_cache_free(vm_area_cachep
, vma
);
488 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
490 if (IS_ENABLED(CONFIG_VMAP_STACK
)) {
491 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
494 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
495 mod_lruvec_page_state(vm
->pages
[i
], NR_KERNEL_STACK_KB
,
496 account
* (PAGE_SIZE
/ 1024));
498 void *stack
= task_stack_page(tsk
);
500 /* All stack pages are in the same node. */
501 mod_lruvec_kmem_state(stack
, NR_KERNEL_STACK_KB
,
502 account
* (THREAD_SIZE
/ 1024));
506 void exit_task_stack_account(struct task_struct
*tsk
)
508 account_kernel_stack(tsk
, -1);
510 if (IS_ENABLED(CONFIG_VMAP_STACK
)) {
511 struct vm_struct
*vm
;
514 vm
= task_stack_vm_area(tsk
);
515 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
516 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
520 static void release_task_stack(struct task_struct
*tsk
)
522 if (WARN_ON(READ_ONCE(tsk
->__state
) != TASK_DEAD
))
523 return; /* Better to leak the stack than to free prematurely */
525 free_thread_stack(tsk
);
528 #ifdef CONFIG_THREAD_INFO_IN_TASK
529 void put_task_stack(struct task_struct
*tsk
)
531 if (refcount_dec_and_test(&tsk
->stack_refcount
))
532 release_task_stack(tsk
);
536 void free_task(struct task_struct
*tsk
)
538 release_user_cpus_ptr(tsk
);
541 #ifndef CONFIG_THREAD_INFO_IN_TASK
543 * The task is finally done with both the stack and thread_info,
546 release_task_stack(tsk
);
549 * If the task had a separate stack allocation, it should be gone
552 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
554 rt_mutex_debug_task_free(tsk
);
555 ftrace_graph_exit_task(tsk
);
556 arch_release_task_struct(tsk
);
557 if (tsk
->flags
& PF_KTHREAD
)
558 free_kthread_struct(tsk
);
559 free_task_struct(tsk
);
561 EXPORT_SYMBOL(free_task
);
563 static void dup_mm_exe_file(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
565 struct file
*exe_file
;
567 exe_file
= get_mm_exe_file(oldmm
);
568 RCU_INIT_POINTER(mm
->exe_file
, exe_file
);
570 * We depend on the oldmm having properly denied write access to the
573 if (exe_file
&& deny_write_access(exe_file
))
574 pr_warn_once("deny_write_access() failed in %s\n", __func__
);
578 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
579 struct mm_struct
*oldmm
)
581 struct vm_area_struct
*mpnt
, *tmp
;
583 unsigned long charge
= 0;
585 MA_STATE(old_mas
, &oldmm
->mm_mt
, 0, 0);
586 MA_STATE(mas
, &mm
->mm_mt
, 0, 0);
588 uprobe_start_dup_mmap();
589 if (mmap_write_lock_killable(oldmm
)) {
591 goto fail_uprobe_end
;
593 flush_cache_dup_mm(oldmm
);
594 uprobe_dup_mmap(oldmm
, mm
);
596 * Not linked in yet - no deadlock potential:
598 mmap_write_lock_nested(mm
, SINGLE_DEPTH_NESTING
);
600 /* No ordering required: file already has been exposed. */
601 dup_mm_exe_file(mm
, oldmm
);
603 mm
->total_vm
= oldmm
->total_vm
;
604 mm
->data_vm
= oldmm
->data_vm
;
605 mm
->exec_vm
= oldmm
->exec_vm
;
606 mm
->stack_vm
= oldmm
->stack_vm
;
608 retval
= ksm_fork(mm
, oldmm
);
611 khugepaged_fork(mm
, oldmm
);
613 retval
= mas_expected_entries(&mas
, oldmm
->map_count
);
617 mas_for_each(&old_mas
, mpnt
, ULONG_MAX
) {
620 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
621 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
626 * Don't duplicate many vmas if we've been oom-killed (for
629 if (fatal_signal_pending(current
)) {
633 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
634 unsigned long len
= vma_pages(mpnt
);
636 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
640 tmp
= vm_area_dup(mpnt
);
643 retval
= vma_dup_policy(mpnt
, tmp
);
645 goto fail_nomem_policy
;
647 retval
= dup_userfaultfd(tmp
, &uf
);
649 goto fail_nomem_anon_vma_fork
;
650 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
652 * VM_WIPEONFORK gets a clean slate in the child.
653 * Don't prepare anon_vma until fault since we don't
654 * copy page for current vma.
656 tmp
->anon_vma
= NULL
;
657 } else if (anon_vma_fork(tmp
, mpnt
))
658 goto fail_nomem_anon_vma_fork
;
659 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
662 struct address_space
*mapping
= file
->f_mapping
;
665 i_mmap_lock_write(mapping
);
666 if (tmp
->vm_flags
& VM_SHARED
)
667 mapping_allow_writable(mapping
);
668 flush_dcache_mmap_lock(mapping
);
669 /* insert tmp into the share list, just after mpnt */
670 vma_interval_tree_insert_after(tmp
, mpnt
,
672 flush_dcache_mmap_unlock(mapping
);
673 i_mmap_unlock_write(mapping
);
677 * Copy/update hugetlb private vma information.
679 if (is_vm_hugetlb_page(tmp
))
680 hugetlb_dup_vma_private(tmp
);
682 /* Link the vma into the MT */
683 mas
.index
= tmp
->vm_start
;
684 mas
.last
= tmp
->vm_end
- 1;
685 mas_store(&mas
, tmp
);
686 if (mas_is_err(&mas
))
687 goto fail_nomem_mas_store
;
690 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
691 retval
= copy_page_range(tmp
, mpnt
);
693 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
694 tmp
->vm_ops
->open(tmp
);
699 /* a new mm has just been created */
700 retval
= arch_dup_mmap(oldmm
, mm
);
704 mmap_write_unlock(mm
);
706 mmap_write_unlock(oldmm
);
707 dup_userfaultfd_complete(&uf
);
709 uprobe_end_dup_mmap();
712 fail_nomem_mas_store
:
713 unlink_anon_vmas(tmp
);
714 fail_nomem_anon_vma_fork
:
715 mpol_put(vma_policy(tmp
));
720 vm_unacct_memory(charge
);
724 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
726 mm
->pgd
= pgd_alloc(mm
);
727 if (unlikely(!mm
->pgd
))
732 static inline void mm_free_pgd(struct mm_struct
*mm
)
734 pgd_free(mm
, mm
->pgd
);
737 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
739 mmap_write_lock(oldmm
);
740 dup_mm_exe_file(mm
, oldmm
);
741 mmap_write_unlock(oldmm
);
744 #define mm_alloc_pgd(mm) (0)
745 #define mm_free_pgd(mm)
746 #endif /* CONFIG_MMU */
748 static void check_mm(struct mm_struct
*mm
)
752 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types
) != NR_MM_COUNTERS
,
753 "Please make sure 'struct resident_page_types[]' is updated as well");
755 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
756 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
759 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
760 mm
, resident_page_types
[i
], x
);
763 if (mm_pgtables_bytes(mm
))
764 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
765 mm_pgtables_bytes(mm
));
767 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
768 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
772 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
773 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
776 * Called when the last reference to the mm
777 * is dropped: either by a lazy thread or by
778 * mmput. Free the page directory and the mm.
780 void __mmdrop(struct mm_struct
*mm
)
782 BUG_ON(mm
== &init_mm
);
783 WARN_ON_ONCE(mm
== current
->mm
);
784 WARN_ON_ONCE(mm
== current
->active_mm
);
787 mmu_notifier_subscriptions_destroy(mm
);
789 put_user_ns(mm
->user_ns
);
793 EXPORT_SYMBOL_GPL(__mmdrop
);
795 static void mmdrop_async_fn(struct work_struct
*work
)
797 struct mm_struct
*mm
;
799 mm
= container_of(work
, struct mm_struct
, async_put_work
);
803 static void mmdrop_async(struct mm_struct
*mm
)
805 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
806 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
807 schedule_work(&mm
->async_put_work
);
811 static inline void free_signal_struct(struct signal_struct
*sig
)
813 taskstats_tgid_free(sig
);
814 sched_autogroup_exit(sig
);
816 * __mmdrop is not safe to call from softirq context on x86 due to
817 * pgd_dtor so postpone it to the async context
820 mmdrop_async(sig
->oom_mm
);
821 kmem_cache_free(signal_cachep
, sig
);
824 static inline void put_signal_struct(struct signal_struct
*sig
)
826 if (refcount_dec_and_test(&sig
->sigcnt
))
827 free_signal_struct(sig
);
830 void __put_task_struct(struct task_struct
*tsk
)
832 WARN_ON(!tsk
->exit_state
);
833 WARN_ON(refcount_read(&tsk
->usage
));
834 WARN_ON(tsk
== current
);
838 task_numa_free(tsk
, true);
839 security_task_free(tsk
);
840 bpf_task_storage_free(tsk
);
842 delayacct_tsk_free(tsk
);
843 put_signal_struct(tsk
->signal
);
844 sched_core_free(tsk
);
847 EXPORT_SYMBOL_GPL(__put_task_struct
);
849 void __init __weak
arch_task_cache_init(void) { }
854 static void set_max_threads(unsigned int max_threads_suggested
)
857 unsigned long nr_pages
= totalram_pages();
860 * The number of threads shall be limited such that the thread
861 * structures may only consume a small part of the available memory.
863 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
864 threads
= MAX_THREADS
;
866 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
867 (u64
) THREAD_SIZE
* 8UL);
869 if (threads
> max_threads_suggested
)
870 threads
= max_threads_suggested
;
872 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
875 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
876 /* Initialized by the architecture: */
877 int arch_task_struct_size __read_mostly
;
880 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
881 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
883 /* Fetch thread_struct whitelist for the architecture. */
884 arch_thread_struct_whitelist(offset
, size
);
887 * Handle zero-sized whitelist or empty thread_struct, otherwise
888 * adjust offset to position of thread_struct in task_struct.
890 if (unlikely(*size
== 0))
893 *offset
+= offsetof(struct task_struct
, thread
);
895 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
897 void __init
fork_init(void)
900 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
901 #ifndef ARCH_MIN_TASKALIGN
902 #define ARCH_MIN_TASKALIGN 0
904 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
905 unsigned long useroffset
, usersize
;
907 /* create a slab on which task_structs can be allocated */
908 task_struct_whitelist(&useroffset
, &usersize
);
909 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
910 arch_task_struct_size
, align
,
911 SLAB_PANIC
|SLAB_ACCOUNT
,
912 useroffset
, usersize
, NULL
);
915 /* do the arch specific task caches init */
916 arch_task_cache_init();
918 set_max_threads(MAX_THREADS
);
920 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
921 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
922 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
923 init_task
.signal
->rlim
[RLIMIT_NPROC
];
925 for (i
= 0; i
< UCOUNT_COUNTS
; i
++)
926 init_user_ns
.ucount_max
[i
] = max_threads
/2;
928 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_NPROC
, RLIM_INFINITY
);
929 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_MSGQUEUE
, RLIM_INFINITY
);
930 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_SIGPENDING
, RLIM_INFINITY
);
931 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_MEMLOCK
, RLIM_INFINITY
);
933 #ifdef CONFIG_VMAP_STACK
934 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
935 NULL
, free_vm_stack_cache
);
940 lockdep_init_task(&init_task
);
944 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
945 struct task_struct
*src
)
951 void set_task_stack_end_magic(struct task_struct
*tsk
)
953 unsigned long *stackend
;
955 stackend
= end_of_stack(tsk
);
956 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
959 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
961 struct task_struct
*tsk
;
964 if (node
== NUMA_NO_NODE
)
965 node
= tsk_fork_get_node(orig
);
966 tsk
= alloc_task_struct_node(node
);
970 err
= arch_dup_task_struct(tsk
, orig
);
974 err
= alloc_thread_stack_node(tsk
, node
);
978 #ifdef CONFIG_THREAD_INFO_IN_TASK
979 refcount_set(&tsk
->stack_refcount
, 1);
981 account_kernel_stack(tsk
, 1);
983 err
= scs_prepare(tsk
, node
);
987 #ifdef CONFIG_SECCOMP
989 * We must handle setting up seccomp filters once we're under
990 * the sighand lock in case orig has changed between now and
991 * then. Until then, filter must be NULL to avoid messing up
992 * the usage counts on the error path calling free_task.
994 tsk
->seccomp
.filter
= NULL
;
997 setup_thread_stack(tsk
, orig
);
998 clear_user_return_notifier(tsk
);
999 clear_tsk_need_resched(tsk
);
1000 set_task_stack_end_magic(tsk
);
1001 clear_syscall_work_syscall_user_dispatch(tsk
);
1003 #ifdef CONFIG_STACKPROTECTOR
1004 tsk
->stack_canary
= get_random_canary();
1006 if (orig
->cpus_ptr
== &orig
->cpus_mask
)
1007 tsk
->cpus_ptr
= &tsk
->cpus_mask
;
1008 dup_user_cpus_ptr(tsk
, orig
, node
);
1011 * One for the user space visible state that goes away when reaped.
1012 * One for the scheduler.
1014 refcount_set(&tsk
->rcu_users
, 2);
1015 /* One for the rcu users */
1016 refcount_set(&tsk
->usage
, 1);
1017 #ifdef CONFIG_BLK_DEV_IO_TRACE
1018 tsk
->btrace_seq
= 0;
1020 tsk
->splice_pipe
= NULL
;
1021 tsk
->task_frag
.page
= NULL
;
1022 tsk
->wake_q
.next
= NULL
;
1023 tsk
->worker_private
= NULL
;
1025 kcov_task_init(tsk
);
1026 kmsan_task_create(tsk
);
1027 kmap_local_fork(tsk
);
1029 #ifdef CONFIG_FAULT_INJECTION
1033 #ifdef CONFIG_BLK_CGROUP
1034 tsk
->throttle_queue
= NULL
;
1035 tsk
->use_memdelay
= 0;
1038 #ifdef CONFIG_IOMMU_SVA
1039 tsk
->pasid_activated
= 0;
1043 tsk
->active_memcg
= NULL
;
1046 #ifdef CONFIG_CPU_SUP_INTEL
1047 tsk
->reported_split_lock
= 0;
1053 exit_task_stack_account(tsk
);
1054 free_thread_stack(tsk
);
1056 free_task_struct(tsk
);
1060 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
1062 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
1064 static int __init
coredump_filter_setup(char *s
)
1066 default_dump_filter
=
1067 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
1068 MMF_DUMP_FILTER_MASK
;
1072 __setup("coredump_filter=", coredump_filter_setup
);
1074 #include <linux/init_task.h>
1076 static void mm_init_aio(struct mm_struct
*mm
)
1079 spin_lock_init(&mm
->ioctx_lock
);
1080 mm
->ioctx_table
= NULL
;
1084 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
1085 struct task_struct
*p
)
1089 WRITE_ONCE(mm
->owner
, NULL
);
1093 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1100 static void mm_init_uprobes_state(struct mm_struct
*mm
)
1102 #ifdef CONFIG_UPROBES
1103 mm
->uprobes_state
.xol_area
= NULL
;
1107 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
1108 struct user_namespace
*user_ns
)
1110 mt_init_flags(&mm
->mm_mt
, MM_MT_FLAGS
);
1111 mt_set_external_lock(&mm
->mm_mt
, &mm
->mmap_lock
);
1112 atomic_set(&mm
->mm_users
, 1);
1113 atomic_set(&mm
->mm_count
, 1);
1114 seqcount_init(&mm
->write_protect_seq
);
1116 INIT_LIST_HEAD(&mm
->mmlist
);
1117 mm_pgtables_bytes_init(mm
);
1120 atomic64_set(&mm
->pinned_vm
, 0);
1121 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
1122 spin_lock_init(&mm
->page_table_lock
);
1123 spin_lock_init(&mm
->arg_lock
);
1124 mm_init_cpumask(mm
);
1126 mm_init_owner(mm
, p
);
1128 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1129 mmu_notifier_subscriptions_init(mm
);
1130 init_tlb_flush_pending(mm
);
1131 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1132 mm
->pmd_huge_pte
= NULL
;
1134 mm_init_uprobes_state(mm
);
1135 hugetlb_count_init(mm
);
1138 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1139 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1141 mm
->flags
= default_dump_filter
;
1145 if (mm_alloc_pgd(mm
))
1148 if (init_new_context(p
, mm
))
1149 goto fail_nocontext
;
1151 mm
->user_ns
= get_user_ns(user_ns
);
1152 lru_gen_init_mm(mm
);
1163 * Allocate and initialize an mm_struct.
1165 struct mm_struct
*mm_alloc(void)
1167 struct mm_struct
*mm
;
1173 memset(mm
, 0, sizeof(*mm
));
1174 return mm_init(mm
, current
, current_user_ns());
1177 static inline void __mmput(struct mm_struct
*mm
)
1179 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1181 uprobe_clear_state(mm
);
1184 khugepaged_exit(mm
); /* must run before exit_mmap */
1186 mm_put_huge_zero_page(mm
);
1187 set_mm_exe_file(mm
, NULL
);
1188 if (!list_empty(&mm
->mmlist
)) {
1189 spin_lock(&mmlist_lock
);
1190 list_del(&mm
->mmlist
);
1191 spin_unlock(&mmlist_lock
);
1194 module_put(mm
->binfmt
->module
);
1200 * Decrement the use count and release all resources for an mm.
1202 void mmput(struct mm_struct
*mm
)
1206 if (atomic_dec_and_test(&mm
->mm_users
))
1209 EXPORT_SYMBOL_GPL(mmput
);
1212 static void mmput_async_fn(struct work_struct
*work
)
1214 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1220 void mmput_async(struct mm_struct
*mm
)
1222 if (atomic_dec_and_test(&mm
->mm_users
)) {
1223 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1224 schedule_work(&mm
->async_put_work
);
1227 EXPORT_SYMBOL_GPL(mmput_async
);
1231 * set_mm_exe_file - change a reference to the mm's executable file
1233 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1235 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1236 * invocations: in mmput() nobody alive left, in execve task is single
1239 * Can only fail if new_exe_file != NULL.
1241 int set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1243 struct file
*old_exe_file
;
1246 * It is safe to dereference the exe_file without RCU as
1247 * this function is only called if nobody else can access
1248 * this mm -- see comment above for justification.
1250 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1254 * We expect the caller (i.e., sys_execve) to already denied
1255 * write access, so this is unlikely to fail.
1257 if (unlikely(deny_write_access(new_exe_file
)))
1259 get_file(new_exe_file
);
1261 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1263 allow_write_access(old_exe_file
);
1270 * replace_mm_exe_file - replace a reference to the mm's executable file
1272 * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1273 * dealing with concurrent invocation and without grabbing the mmap lock in
1276 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1278 int replace_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1280 struct vm_area_struct
*vma
;
1281 struct file
*old_exe_file
;
1284 /* Forbid mm->exe_file change if old file still mapped. */
1285 old_exe_file
= get_mm_exe_file(mm
);
1287 VMA_ITERATOR(vmi
, mm
, 0);
1289 for_each_vma(vmi
, vma
) {
1292 if (path_equal(&vma
->vm_file
->f_path
,
1293 &old_exe_file
->f_path
)) {
1298 mmap_read_unlock(mm
);
1304 /* set the new file, lockless */
1305 ret
= deny_write_access(new_exe_file
);
1308 get_file(new_exe_file
);
1310 old_exe_file
= xchg(&mm
->exe_file
, new_exe_file
);
1313 * Don't race with dup_mmap() getting the file and disallowing
1314 * write access while someone might open the file writable.
1317 allow_write_access(old_exe_file
);
1319 mmap_read_unlock(mm
);
1325 * get_mm_exe_file - acquire a reference to the mm's executable file
1327 * Returns %NULL if mm has no associated executable file.
1328 * User must release file via fput().
1330 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1332 struct file
*exe_file
;
1335 exe_file
= rcu_dereference(mm
->exe_file
);
1336 if (exe_file
&& !get_file_rcu(exe_file
))
1343 * get_task_exe_file - acquire a reference to the task's executable file
1345 * Returns %NULL if task's mm (if any) has no associated executable file or
1346 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1347 * User must release file via fput().
1349 struct file
*get_task_exe_file(struct task_struct
*task
)
1351 struct file
*exe_file
= NULL
;
1352 struct mm_struct
*mm
;
1357 if (!(task
->flags
& PF_KTHREAD
))
1358 exe_file
= get_mm_exe_file(mm
);
1365 * get_task_mm - acquire a reference to the task's mm
1367 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1368 * this kernel workthread has transiently adopted a user mm with use_mm,
1369 * to do its AIO) is not set and if so returns a reference to it, after
1370 * bumping up the use count. User must release the mm via mmput()
1371 * after use. Typically used by /proc and ptrace.
1373 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1375 struct mm_struct
*mm
;
1380 if (task
->flags
& PF_KTHREAD
)
1388 EXPORT_SYMBOL_GPL(get_task_mm
);
1390 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1392 struct mm_struct
*mm
;
1395 err
= down_read_killable(&task
->signal
->exec_update_lock
);
1397 return ERR_PTR(err
);
1399 mm
= get_task_mm(task
);
1400 if (mm
&& mm
!= current
->mm
&&
1401 !ptrace_may_access(task
, mode
)) {
1403 mm
= ERR_PTR(-EACCES
);
1405 up_read(&task
->signal
->exec_update_lock
);
1410 static void complete_vfork_done(struct task_struct
*tsk
)
1412 struct completion
*vfork
;
1415 vfork
= tsk
->vfork_done
;
1416 if (likely(vfork
)) {
1417 tsk
->vfork_done
= NULL
;
1423 static int wait_for_vfork_done(struct task_struct
*child
,
1424 struct completion
*vfork
)
1426 unsigned int state
= TASK_UNINTERRUPTIBLE
|TASK_KILLABLE
|TASK_FREEZABLE
;
1429 cgroup_enter_frozen();
1430 killed
= wait_for_completion_state(vfork
, state
);
1431 cgroup_leave_frozen(false);
1435 child
->vfork_done
= NULL
;
1439 put_task_struct(child
);
1443 /* Please note the differences between mmput and mm_release.
1444 * mmput is called whenever we stop holding onto a mm_struct,
1445 * error success whatever.
1447 * mm_release is called after a mm_struct has been removed
1448 * from the current process.
1450 * This difference is important for error handling, when we
1451 * only half set up a mm_struct for a new process and need to restore
1452 * the old one. Because we mmput the new mm_struct before
1453 * restoring the old one. . .
1454 * Eric Biederman 10 January 1998
1456 static void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1458 uprobe_free_utask(tsk
);
1460 /* Get rid of any cached register state */
1461 deactivate_mm(tsk
, mm
);
1464 * Signal userspace if we're not exiting with a core dump
1465 * because we want to leave the value intact for debugging
1468 if (tsk
->clear_child_tid
) {
1469 if (atomic_read(&mm
->mm_users
) > 1) {
1471 * We don't check the error code - if userspace has
1472 * not set up a proper pointer then tough luck.
1474 put_user(0, tsk
->clear_child_tid
);
1475 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1476 1, NULL
, NULL
, 0, 0);
1478 tsk
->clear_child_tid
= NULL
;
1482 * All done, finally we can wake up parent and return this mm to him.
1483 * Also kthread_stop() uses this completion for synchronization.
1485 if (tsk
->vfork_done
)
1486 complete_vfork_done(tsk
);
1489 void exit_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1491 futex_exit_release(tsk
);
1492 mm_release(tsk
, mm
);
1495 void exec_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1497 futex_exec_release(tsk
);
1498 mm_release(tsk
, mm
);
1502 * dup_mm() - duplicates an existing mm structure
1503 * @tsk: the task_struct with which the new mm will be associated.
1504 * @oldmm: the mm to duplicate.
1506 * Allocates a new mm structure and duplicates the provided @oldmm structure
1509 * Return: the duplicated mm or NULL on failure.
1511 static struct mm_struct
*dup_mm(struct task_struct
*tsk
,
1512 struct mm_struct
*oldmm
)
1514 struct mm_struct
*mm
;
1521 memcpy(mm
, oldmm
, sizeof(*mm
));
1523 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1526 err
= dup_mmap(mm
, oldmm
);
1530 mm
->hiwater_rss
= get_mm_rss(mm
);
1531 mm
->hiwater_vm
= mm
->total_vm
;
1533 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1539 /* don't put binfmt in mmput, we haven't got module yet */
1541 mm_init_owner(mm
, NULL
);
1548 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1550 struct mm_struct
*mm
, *oldmm
;
1552 tsk
->min_flt
= tsk
->maj_flt
= 0;
1553 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1554 #ifdef CONFIG_DETECT_HUNG_TASK
1555 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1556 tsk
->last_switch_time
= 0;
1560 tsk
->active_mm
= NULL
;
1563 * Are we cloning a kernel thread?
1565 * We need to steal a active VM for that..
1567 oldmm
= current
->mm
;
1571 if (clone_flags
& CLONE_VM
) {
1575 mm
= dup_mm(tsk
, current
->mm
);
1581 tsk
->active_mm
= mm
;
1585 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1587 struct fs_struct
*fs
= current
->fs
;
1588 if (clone_flags
& CLONE_FS
) {
1589 /* tsk->fs is already what we want */
1590 spin_lock(&fs
->lock
);
1592 spin_unlock(&fs
->lock
);
1596 spin_unlock(&fs
->lock
);
1599 tsk
->fs
= copy_fs_struct(fs
);
1605 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1607 struct files_struct
*oldf
, *newf
;
1611 * A background process may not have any files ...
1613 oldf
= current
->files
;
1617 if (clone_flags
& CLONE_FILES
) {
1618 atomic_inc(&oldf
->count
);
1622 newf
= dup_fd(oldf
, NR_OPEN_MAX
, &error
);
1632 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1634 struct sighand_struct
*sig
;
1636 if (clone_flags
& CLONE_SIGHAND
) {
1637 refcount_inc(¤t
->sighand
->count
);
1640 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1641 RCU_INIT_POINTER(tsk
->sighand
, sig
);
1645 refcount_set(&sig
->count
, 1);
1646 spin_lock_irq(¤t
->sighand
->siglock
);
1647 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1648 spin_unlock_irq(¤t
->sighand
->siglock
);
1650 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1651 if (clone_flags
& CLONE_CLEAR_SIGHAND
)
1652 flush_signal_handlers(tsk
, 0);
1657 void __cleanup_sighand(struct sighand_struct
*sighand
)
1659 if (refcount_dec_and_test(&sighand
->count
)) {
1660 signalfd_cleanup(sighand
);
1662 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1663 * without an RCU grace period, see __lock_task_sighand().
1665 kmem_cache_free(sighand_cachep
, sighand
);
1670 * Initialize POSIX timer handling for a thread group.
1672 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1674 struct posix_cputimers
*pct
= &sig
->posix_cputimers
;
1675 unsigned long cpu_limit
;
1677 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1678 posix_cputimers_group_init(pct
, cpu_limit
);
1681 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1683 struct signal_struct
*sig
;
1685 if (clone_flags
& CLONE_THREAD
)
1688 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1693 sig
->nr_threads
= 1;
1694 sig
->quick_threads
= 1;
1695 atomic_set(&sig
->live
, 1);
1696 refcount_set(&sig
->sigcnt
, 1);
1698 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1699 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1700 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1702 init_waitqueue_head(&sig
->wait_chldexit
);
1703 sig
->curr_target
= tsk
;
1704 init_sigpending(&sig
->shared_pending
);
1705 INIT_HLIST_HEAD(&sig
->multiprocess
);
1706 seqlock_init(&sig
->stats_lock
);
1707 prev_cputime_init(&sig
->prev_cputime
);
1709 #ifdef CONFIG_POSIX_TIMERS
1710 INIT_LIST_HEAD(&sig
->posix_timers
);
1711 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1712 sig
->real_timer
.function
= it_real_fn
;
1715 task_lock(current
->group_leader
);
1716 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1717 task_unlock(current
->group_leader
);
1719 posix_cpu_timers_init_group(sig
);
1721 tty_audit_fork(sig
);
1722 sched_autogroup_fork(sig
);
1724 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1725 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1727 mutex_init(&sig
->cred_guard_mutex
);
1728 init_rwsem(&sig
->exec_update_lock
);
1733 static void copy_seccomp(struct task_struct
*p
)
1735 #ifdef CONFIG_SECCOMP
1737 * Must be called with sighand->lock held, which is common to
1738 * all threads in the group. Holding cred_guard_mutex is not
1739 * needed because this new task is not yet running and cannot
1742 assert_spin_locked(¤t
->sighand
->siglock
);
1744 /* Ref-count the new filter user, and assign it. */
1745 get_seccomp_filter(current
);
1746 p
->seccomp
= current
->seccomp
;
1749 * Explicitly enable no_new_privs here in case it got set
1750 * between the task_struct being duplicated and holding the
1751 * sighand lock. The seccomp state and nnp must be in sync.
1753 if (task_no_new_privs(current
))
1754 task_set_no_new_privs(p
);
1757 * If the parent gained a seccomp mode after copying thread
1758 * flags and between before we held the sighand lock, we have
1759 * to manually enable the seccomp thread flag here.
1761 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1762 set_task_syscall_work(p
, SECCOMP
);
1766 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1768 current
->clear_child_tid
= tidptr
;
1770 return task_pid_vnr(current
);
1773 static void rt_mutex_init_task(struct task_struct
*p
)
1775 raw_spin_lock_init(&p
->pi_lock
);
1776 #ifdef CONFIG_RT_MUTEXES
1777 p
->pi_waiters
= RB_ROOT_CACHED
;
1778 p
->pi_top_task
= NULL
;
1779 p
->pi_blocked_on
= NULL
;
1783 static inline void init_task_pid_links(struct task_struct
*task
)
1787 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
)
1788 INIT_HLIST_NODE(&task
->pid_links
[type
]);
1792 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1794 if (type
== PIDTYPE_PID
)
1795 task
->thread_pid
= pid
;
1797 task
->signal
->pids
[type
] = pid
;
1800 static inline void rcu_copy_process(struct task_struct
*p
)
1802 #ifdef CONFIG_PREEMPT_RCU
1803 p
->rcu_read_lock_nesting
= 0;
1804 p
->rcu_read_unlock_special
.s
= 0;
1805 p
->rcu_blocked_node
= NULL
;
1806 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1807 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1808 #ifdef CONFIG_TASKS_RCU
1809 p
->rcu_tasks_holdout
= false;
1810 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1811 p
->rcu_tasks_idle_cpu
= -1;
1812 #endif /* #ifdef CONFIG_TASKS_RCU */
1813 #ifdef CONFIG_TASKS_TRACE_RCU
1814 p
->trc_reader_nesting
= 0;
1815 p
->trc_reader_special
.s
= 0;
1816 INIT_LIST_HEAD(&p
->trc_holdout_list
);
1817 INIT_LIST_HEAD(&p
->trc_blkd_node
);
1818 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1821 struct pid
*pidfd_pid(const struct file
*file
)
1823 if (file
->f_op
== &pidfd_fops
)
1824 return file
->private_data
;
1826 return ERR_PTR(-EBADF
);
1829 static int pidfd_release(struct inode
*inode
, struct file
*file
)
1831 struct pid
*pid
= file
->private_data
;
1833 file
->private_data
= NULL
;
1838 #ifdef CONFIG_PROC_FS
1840 * pidfd_show_fdinfo - print information about a pidfd
1841 * @m: proc fdinfo file
1842 * @f: file referencing a pidfd
1845 * This function will print the pid that a given pidfd refers to in the
1846 * pid namespace of the procfs instance.
1847 * If the pid namespace of the process is not a descendant of the pid
1848 * namespace of the procfs instance 0 will be shown as its pid. This is
1849 * similar to calling getppid() on a process whose parent is outside of
1850 * its pid namespace.
1853 * If pid namespaces are supported then this function will also print
1854 * the pid of a given pidfd refers to for all descendant pid namespaces
1855 * starting from the current pid namespace of the instance, i.e. the
1856 * Pid field and the first entry in the NSpid field will be identical.
1857 * If the pid namespace of the process is not a descendant of the pid
1858 * namespace of the procfs instance 0 will be shown as its first NSpid
1859 * entry and no others will be shown.
1860 * Note that this differs from the Pid and NSpid fields in
1861 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1862 * the pid namespace of the procfs instance. The difference becomes
1863 * obvious when sending around a pidfd between pid namespaces from a
1864 * different branch of the tree, i.e. where no ancestral relation is
1865 * present between the pid namespaces:
1866 * - create two new pid namespaces ns1 and ns2 in the initial pid
1867 * namespace (also take care to create new mount namespaces in the
1868 * new pid namespace and mount procfs)
1869 * - create a process with a pidfd in ns1
1870 * - send pidfd from ns1 to ns2
1871 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1872 * have exactly one entry, which is 0
1874 static void pidfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
1876 struct pid
*pid
= f
->private_data
;
1877 struct pid_namespace
*ns
;
1880 if (likely(pid_has_task(pid
, PIDTYPE_PID
))) {
1881 ns
= proc_pid_ns(file_inode(m
->file
)->i_sb
);
1882 nr
= pid_nr_ns(pid
, ns
);
1885 seq_put_decimal_ll(m
, "Pid:\t", nr
);
1887 #ifdef CONFIG_PID_NS
1888 seq_put_decimal_ll(m
, "\nNSpid:\t", nr
);
1892 /* If nr is non-zero it means that 'pid' is valid and that
1893 * ns, i.e. the pid namespace associated with the procfs
1894 * instance, is in the pid namespace hierarchy of pid.
1895 * Start at one below the already printed level.
1897 for (i
= ns
->level
+ 1; i
<= pid
->level
; i
++)
1898 seq_put_decimal_ll(m
, "\t", pid
->numbers
[i
].nr
);
1906 * Poll support for process exit notification.
1908 static __poll_t
pidfd_poll(struct file
*file
, struct poll_table_struct
*pts
)
1910 struct pid
*pid
= file
->private_data
;
1911 __poll_t poll_flags
= 0;
1913 poll_wait(file
, &pid
->wait_pidfd
, pts
);
1916 * Inform pollers only when the whole thread group exits.
1917 * If the thread group leader exits before all other threads in the
1918 * group, then poll(2) should block, similar to the wait(2) family.
1920 if (thread_group_exited(pid
))
1921 poll_flags
= EPOLLIN
| EPOLLRDNORM
;
1926 const struct file_operations pidfd_fops
= {
1927 .release
= pidfd_release
,
1929 #ifdef CONFIG_PROC_FS
1930 .show_fdinfo
= pidfd_show_fdinfo
,
1934 static void __delayed_free_task(struct rcu_head
*rhp
)
1936 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
1941 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
1943 if (IS_ENABLED(CONFIG_MEMCG
))
1944 call_rcu(&tsk
->rcu
, __delayed_free_task
);
1949 static void copy_oom_score_adj(u64 clone_flags
, struct task_struct
*tsk
)
1951 /* Skip if kernel thread */
1955 /* Skip if spawning a thread or using vfork */
1956 if ((clone_flags
& (CLONE_VM
| CLONE_THREAD
| CLONE_VFORK
)) != CLONE_VM
)
1959 /* We need to synchronize with __set_oom_adj */
1960 mutex_lock(&oom_adj_mutex
);
1961 set_bit(MMF_MULTIPROCESS
, &tsk
->mm
->flags
);
1962 /* Update the values in case they were changed after copy_signal */
1963 tsk
->signal
->oom_score_adj
= current
->signal
->oom_score_adj
;
1964 tsk
->signal
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1965 mutex_unlock(&oom_adj_mutex
);
1969 static void rv_task_fork(struct task_struct
*p
)
1973 for (i
= 0; i
< RV_PER_TASK_MONITORS
; i
++)
1974 p
->rv
[i
].da_mon
.monitoring
= false;
1977 #define rv_task_fork(p) do {} while (0)
1981 * This creates a new process as a copy of the old one,
1982 * but does not actually start it yet.
1984 * It copies the registers, and all the appropriate
1985 * parts of the process environment (as per the clone
1986 * flags). The actual kick-off is left to the caller.
1988 static __latent_entropy
struct task_struct
*copy_process(
1992 struct kernel_clone_args
*args
)
1994 int pidfd
= -1, retval
;
1995 struct task_struct
*p
;
1996 struct multiprocess_signals delayed
;
1997 struct file
*pidfile
= NULL
;
1998 const u64 clone_flags
= args
->flags
;
1999 struct nsproxy
*nsp
= current
->nsproxy
;
2002 * Don't allow sharing the root directory with processes in a different
2005 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
2006 return ERR_PTR(-EINVAL
);
2008 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
2009 return ERR_PTR(-EINVAL
);
2012 * Thread groups must share signals as well, and detached threads
2013 * can only be started up within the thread group.
2015 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
2016 return ERR_PTR(-EINVAL
);
2019 * Shared signal handlers imply shared VM. By way of the above,
2020 * thread groups also imply shared VM. Blocking this case allows
2021 * for various simplifications in other code.
2023 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
2024 return ERR_PTR(-EINVAL
);
2027 * Siblings of global init remain as zombies on exit since they are
2028 * not reaped by their parent (swapper). To solve this and to avoid
2029 * multi-rooted process trees, prevent global and container-inits
2030 * from creating siblings.
2032 if ((clone_flags
& CLONE_PARENT
) &&
2033 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
2034 return ERR_PTR(-EINVAL
);
2037 * If the new process will be in a different pid or user namespace
2038 * do not allow it to share a thread group with the forking task.
2040 if (clone_flags
& CLONE_THREAD
) {
2041 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
2042 (task_active_pid_ns(current
) != nsp
->pid_ns_for_children
))
2043 return ERR_PTR(-EINVAL
);
2047 * If the new process will be in a different time namespace
2048 * do not allow it to share VM or a thread group with the forking task.
2050 if (clone_flags
& (CLONE_THREAD
| CLONE_VM
)) {
2051 if (nsp
->time_ns
!= nsp
->time_ns_for_children
)
2052 return ERR_PTR(-EINVAL
);
2055 if (clone_flags
& CLONE_PIDFD
) {
2057 * - CLONE_DETACHED is blocked so that we can potentially
2058 * reuse it later for CLONE_PIDFD.
2059 * - CLONE_THREAD is blocked until someone really needs it.
2061 if (clone_flags
& (CLONE_DETACHED
| CLONE_THREAD
))
2062 return ERR_PTR(-EINVAL
);
2066 * Force any signals received before this point to be delivered
2067 * before the fork happens. Collect up signals sent to multiple
2068 * processes that happen during the fork and delay them so that
2069 * they appear to happen after the fork.
2071 sigemptyset(&delayed
.signal
);
2072 INIT_HLIST_NODE(&delayed
.node
);
2074 spin_lock_irq(¤t
->sighand
->siglock
);
2075 if (!(clone_flags
& CLONE_THREAD
))
2076 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
2077 recalc_sigpending();
2078 spin_unlock_irq(¤t
->sighand
->siglock
);
2079 retval
= -ERESTARTNOINTR
;
2080 if (task_sigpending(current
))
2084 p
= dup_task_struct(current
, node
);
2087 p
->flags
&= ~PF_KTHREAD
;
2089 p
->flags
|= PF_KTHREAD
;
2090 if (args
->io_thread
) {
2092 * Mark us an IO worker, and block any signal that isn't
2095 p
->flags
|= PF_IO_WORKER
;
2096 siginitsetinv(&p
->blocked
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2099 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? args
->child_tid
: NULL
;
2101 * Clear TID on mm_release()?
2103 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? args
->child_tid
: NULL
;
2105 ftrace_graph_init_task(p
);
2107 rt_mutex_init_task(p
);
2109 lockdep_assert_irqs_enabled();
2110 #ifdef CONFIG_PROVE_LOCKING
2111 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
2113 retval
= copy_creds(p
, clone_flags
);
2118 if (is_rlimit_overlimit(task_ucounts(p
), UCOUNT_RLIMIT_NPROC
, rlimit(RLIMIT_NPROC
))) {
2119 if (p
->real_cred
->user
!= INIT_USER
&&
2120 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
2121 goto bad_fork_cleanup_count
;
2123 current
->flags
&= ~PF_NPROC_EXCEEDED
;
2126 * If multiple threads are within copy_process(), then this check
2127 * triggers too late. This doesn't hurt, the check is only there
2128 * to stop root fork bombs.
2131 if (data_race(nr_threads
>= max_threads
))
2132 goto bad_fork_cleanup_count
;
2134 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
2135 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
| PF_NO_SETAFFINITY
);
2136 p
->flags
|= PF_FORKNOEXEC
;
2137 INIT_LIST_HEAD(&p
->children
);
2138 INIT_LIST_HEAD(&p
->sibling
);
2139 rcu_copy_process(p
);
2140 p
->vfork_done
= NULL
;
2141 spin_lock_init(&p
->alloc_lock
);
2143 init_sigpending(&p
->pending
);
2145 p
->utime
= p
->stime
= p
->gtime
= 0;
2146 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2147 p
->utimescaled
= p
->stimescaled
= 0;
2149 prev_cputime_init(&p
->prev_cputime
);
2151 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2152 seqcount_init(&p
->vtime
.seqcount
);
2153 p
->vtime
.starttime
= 0;
2154 p
->vtime
.state
= VTIME_INACTIVE
;
2157 #ifdef CONFIG_IO_URING
2161 #if defined(SPLIT_RSS_COUNTING)
2162 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
2165 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
2171 task_io_accounting_init(&p
->ioac
);
2172 acct_clear_integrals(p
);
2174 posix_cputimers_init(&p
->posix_cputimers
);
2176 p
->io_context
= NULL
;
2177 audit_set_context(p
, NULL
);
2179 if (args
->kthread
) {
2180 if (!set_kthread_struct(p
))
2181 goto bad_fork_cleanup_delayacct
;
2184 p
->mempolicy
= mpol_dup(p
->mempolicy
);
2185 if (IS_ERR(p
->mempolicy
)) {
2186 retval
= PTR_ERR(p
->mempolicy
);
2187 p
->mempolicy
= NULL
;
2188 goto bad_fork_cleanup_delayacct
;
2191 #ifdef CONFIG_CPUSETS
2192 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
2193 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
2194 seqcount_spinlock_init(&p
->mems_allowed_seq
, &p
->alloc_lock
);
2196 #ifdef CONFIG_TRACE_IRQFLAGS
2197 memset(&p
->irqtrace
, 0, sizeof(p
->irqtrace
));
2198 p
->irqtrace
.hardirq_disable_ip
= _THIS_IP_
;
2199 p
->irqtrace
.softirq_enable_ip
= _THIS_IP_
;
2200 p
->softirqs_enabled
= 1;
2201 p
->softirq_context
= 0;
2204 p
->pagefault_disabled
= 0;
2206 #ifdef CONFIG_LOCKDEP
2207 lockdep_init_task(p
);
2210 #ifdef CONFIG_DEBUG_MUTEXES
2211 p
->blocked_on
= NULL
; /* not blocked yet */
2213 #ifdef CONFIG_BCACHE
2214 p
->sequential_io
= 0;
2215 p
->sequential_io_avg
= 0;
2217 #ifdef CONFIG_BPF_SYSCALL
2218 RCU_INIT_POINTER(p
->bpf_storage
, NULL
);
2222 /* Perform scheduler related setup. Assign this task to a CPU. */
2223 retval
= sched_fork(clone_flags
, p
);
2225 goto bad_fork_cleanup_policy
;
2227 retval
= perf_event_init_task(p
, clone_flags
);
2229 goto bad_fork_cleanup_policy
;
2230 retval
= audit_alloc(p
);
2232 goto bad_fork_cleanup_perf
;
2233 /* copy all the process information */
2235 retval
= security_task_alloc(p
, clone_flags
);
2237 goto bad_fork_cleanup_audit
;
2238 retval
= copy_semundo(clone_flags
, p
);
2240 goto bad_fork_cleanup_security
;
2241 retval
= copy_files(clone_flags
, p
);
2243 goto bad_fork_cleanup_semundo
;
2244 retval
= copy_fs(clone_flags
, p
);
2246 goto bad_fork_cleanup_files
;
2247 retval
= copy_sighand(clone_flags
, p
);
2249 goto bad_fork_cleanup_fs
;
2250 retval
= copy_signal(clone_flags
, p
);
2252 goto bad_fork_cleanup_sighand
;
2253 retval
= copy_mm(clone_flags
, p
);
2255 goto bad_fork_cleanup_signal
;
2256 retval
= copy_namespaces(clone_flags
, p
);
2258 goto bad_fork_cleanup_mm
;
2259 retval
= copy_io(clone_flags
, p
);
2261 goto bad_fork_cleanup_namespaces
;
2262 retval
= copy_thread(p
, args
);
2264 goto bad_fork_cleanup_io
;
2266 stackleak_task_init(p
);
2268 if (pid
!= &init_struct_pid
) {
2269 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
, args
->set_tid
,
2270 args
->set_tid_size
);
2272 retval
= PTR_ERR(pid
);
2273 goto bad_fork_cleanup_thread
;
2278 * This has to happen after we've potentially unshared the file
2279 * descriptor table (so that the pidfd doesn't leak into the child
2280 * if the fd table isn't shared).
2282 if (clone_flags
& CLONE_PIDFD
) {
2283 retval
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2285 goto bad_fork_free_pid
;
2289 pidfile
= anon_inode_getfile("[pidfd]", &pidfd_fops
, pid
,
2290 O_RDWR
| O_CLOEXEC
);
2291 if (IS_ERR(pidfile
)) {
2292 put_unused_fd(pidfd
);
2293 retval
= PTR_ERR(pidfile
);
2294 goto bad_fork_free_pid
;
2296 get_pid(pid
); /* held by pidfile now */
2298 retval
= put_user(pidfd
, args
->pidfd
);
2300 goto bad_fork_put_pidfd
;
2309 * sigaltstack should be cleared when sharing the same VM
2311 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
2315 * Syscall tracing and stepping should be turned off in the
2316 * child regardless of CLONE_PTRACE.
2318 user_disable_single_step(p
);
2319 clear_task_syscall_work(p
, SYSCALL_TRACE
);
2320 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2321 clear_task_syscall_work(p
, SYSCALL_EMU
);
2323 clear_tsk_latency_tracing(p
);
2325 /* ok, now we should be set up.. */
2326 p
->pid
= pid_nr(pid
);
2327 if (clone_flags
& CLONE_THREAD
) {
2328 p
->group_leader
= current
->group_leader
;
2329 p
->tgid
= current
->tgid
;
2331 p
->group_leader
= p
;
2336 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2337 p
->dirty_paused_when
= 0;
2339 p
->pdeath_signal
= 0;
2340 INIT_LIST_HEAD(&p
->thread_group
);
2341 p
->task_works
= NULL
;
2342 clear_posix_cputimers_work(p
);
2344 #ifdef CONFIG_KRETPROBES
2345 p
->kretprobe_instances
.first
= NULL
;
2347 #ifdef CONFIG_RETHOOK
2348 p
->rethooks
.first
= NULL
;
2352 * Ensure that the cgroup subsystem policies allow the new process to be
2353 * forked. It should be noted that the new process's css_set can be changed
2354 * between here and cgroup_post_fork() if an organisation operation is in
2357 retval
= cgroup_can_fork(p
, args
);
2359 goto bad_fork_put_pidfd
;
2362 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2363 * the new task on the correct runqueue. All this *before* the task
2366 * This isn't part of ->can_fork() because while the re-cloning is
2367 * cgroup specific, it unconditionally needs to place the task on a
2370 sched_cgroup_fork(p
, args
);
2373 * From this point on we must avoid any synchronous user-space
2374 * communication until we take the tasklist-lock. In particular, we do
2375 * not want user-space to be able to predict the process start-time by
2376 * stalling fork(2) after we recorded the start_time but before it is
2377 * visible to the system.
2380 p
->start_time
= ktime_get_ns();
2381 p
->start_boottime
= ktime_get_boottime_ns();
2384 * Make it visible to the rest of the system, but dont wake it up yet.
2385 * Need tasklist lock for parent etc handling!
2387 write_lock_irq(&tasklist_lock
);
2389 /* CLONE_PARENT re-uses the old parent */
2390 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2391 p
->real_parent
= current
->real_parent
;
2392 p
->parent_exec_id
= current
->parent_exec_id
;
2393 if (clone_flags
& CLONE_THREAD
)
2394 p
->exit_signal
= -1;
2396 p
->exit_signal
= current
->group_leader
->exit_signal
;
2398 p
->real_parent
= current
;
2399 p
->parent_exec_id
= current
->self_exec_id
;
2400 p
->exit_signal
= args
->exit_signal
;
2403 klp_copy_process(p
);
2407 spin_lock(¤t
->sighand
->siglock
);
2410 * Copy seccomp details explicitly here, in case they were changed
2411 * before holding sighand lock.
2417 rseq_fork(p
, clone_flags
);
2419 /* Don't start children in a dying pid namespace */
2420 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2422 goto bad_fork_cancel_cgroup
;
2425 /* Let kill terminate clone/fork in the middle */
2426 if (fatal_signal_pending(current
)) {
2428 goto bad_fork_cancel_cgroup
;
2431 init_task_pid_links(p
);
2432 if (likely(p
->pid
)) {
2433 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2435 init_task_pid(p
, PIDTYPE_PID
, pid
);
2436 if (thread_group_leader(p
)) {
2437 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2438 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2439 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2441 if (is_child_reaper(pid
)) {
2442 ns_of_pid(pid
)->child_reaper
= p
;
2443 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2445 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2446 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2448 * Inherit has_child_subreaper flag under the same
2449 * tasklist_lock with adding child to the process tree
2450 * for propagate_has_child_subreaper optimization.
2452 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2453 p
->real_parent
->signal
->is_child_subreaper
;
2454 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2455 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2456 attach_pid(p
, PIDTYPE_TGID
);
2457 attach_pid(p
, PIDTYPE_PGID
);
2458 attach_pid(p
, PIDTYPE_SID
);
2459 __this_cpu_inc(process_counts
);
2461 current
->signal
->nr_threads
++;
2462 current
->signal
->quick_threads
++;
2463 atomic_inc(¤t
->signal
->live
);
2464 refcount_inc(¤t
->signal
->sigcnt
);
2465 task_join_group_stop(p
);
2466 list_add_tail_rcu(&p
->thread_group
,
2467 &p
->group_leader
->thread_group
);
2468 list_add_tail_rcu(&p
->thread_node
,
2469 &p
->signal
->thread_head
);
2471 attach_pid(p
, PIDTYPE_PID
);
2475 hlist_del_init(&delayed
.node
);
2476 spin_unlock(¤t
->sighand
->siglock
);
2477 syscall_tracepoint_update(p
);
2478 write_unlock_irq(&tasklist_lock
);
2481 fd_install(pidfd
, pidfile
);
2483 proc_fork_connector(p
);
2485 cgroup_post_fork(p
, args
);
2488 trace_task_newtask(p
, clone_flags
);
2489 uprobe_copy_process(p
, clone_flags
);
2491 copy_oom_score_adj(clone_flags
, p
);
2495 bad_fork_cancel_cgroup
:
2497 spin_unlock(¤t
->sighand
->siglock
);
2498 write_unlock_irq(&tasklist_lock
);
2499 cgroup_cancel_fork(p
, args
);
2501 if (clone_flags
& CLONE_PIDFD
) {
2503 put_unused_fd(pidfd
);
2506 if (pid
!= &init_struct_pid
)
2508 bad_fork_cleanup_thread
:
2510 bad_fork_cleanup_io
:
2513 bad_fork_cleanup_namespaces
:
2514 exit_task_namespaces(p
);
2515 bad_fork_cleanup_mm
:
2517 mm_clear_owner(p
->mm
, p
);
2520 bad_fork_cleanup_signal
:
2521 if (!(clone_flags
& CLONE_THREAD
))
2522 free_signal_struct(p
->signal
);
2523 bad_fork_cleanup_sighand
:
2524 __cleanup_sighand(p
->sighand
);
2525 bad_fork_cleanup_fs
:
2526 exit_fs(p
); /* blocking */
2527 bad_fork_cleanup_files
:
2528 exit_files(p
); /* blocking */
2529 bad_fork_cleanup_semundo
:
2531 bad_fork_cleanup_security
:
2532 security_task_free(p
);
2533 bad_fork_cleanup_audit
:
2535 bad_fork_cleanup_perf
:
2536 perf_event_free_task(p
);
2537 bad_fork_cleanup_policy
:
2538 lockdep_free_task(p
);
2540 mpol_put(p
->mempolicy
);
2542 bad_fork_cleanup_delayacct
:
2543 delayacct_tsk_free(p
);
2544 bad_fork_cleanup_count
:
2545 dec_rlimit_ucounts(task_ucounts(p
), UCOUNT_RLIMIT_NPROC
, 1);
2548 WRITE_ONCE(p
->__state
, TASK_DEAD
);
2549 exit_task_stack_account(p
);
2551 delayed_free_task(p
);
2553 spin_lock_irq(¤t
->sighand
->siglock
);
2554 hlist_del_init(&delayed
.node
);
2555 spin_unlock_irq(¤t
->sighand
->siglock
);
2556 return ERR_PTR(retval
);
2559 static inline void init_idle_pids(struct task_struct
*idle
)
2563 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2564 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2565 init_task_pid(idle
, type
, &init_struct_pid
);
2569 static int idle_dummy(void *dummy
)
2571 /* This function is never called */
2575 struct task_struct
* __init
fork_idle(int cpu
)
2577 struct task_struct
*task
;
2578 struct kernel_clone_args args
= {
2586 task
= copy_process(&init_struct_pid
, 0, cpu_to_node(cpu
), &args
);
2587 if (!IS_ERR(task
)) {
2588 init_idle_pids(task
);
2589 init_idle(task
, cpu
);
2595 struct mm_struct
*copy_init_mm(void)
2597 return dup_mm(NULL
, &init_mm
);
2601 * This is like kernel_clone(), but shaved down and tailored to just
2602 * creating io_uring workers. It returns a created task, or an error pointer.
2603 * The returned task is inactive, and the caller must fire it up through
2604 * wake_up_new_task(p). All signals are blocked in the created task.
2606 struct task_struct
*create_io_thread(int (*fn
)(void *), void *arg
, int node
)
2608 unsigned long flags
= CLONE_FS
|CLONE_FILES
|CLONE_SIGHAND
|CLONE_THREAD
|
2610 struct kernel_clone_args args
= {
2611 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2612 CLONE_UNTRACED
) & ~CSIGNAL
),
2613 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2619 return copy_process(NULL
, 0, node
, &args
);
2623 * Ok, this is the main fork-routine.
2625 * It copies the process, and if successful kick-starts
2626 * it and waits for it to finish using the VM if required.
2628 * args->exit_signal is expected to be checked for sanity by the caller.
2630 pid_t
kernel_clone(struct kernel_clone_args
*args
)
2632 u64 clone_flags
= args
->flags
;
2633 struct completion vfork
;
2635 struct task_struct
*p
;
2640 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2641 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2642 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2643 * field in struct clone_args and it still doesn't make sense to have
2644 * them both point at the same memory location. Performing this check
2645 * here has the advantage that we don't need to have a separate helper
2646 * to check for legacy clone().
2648 if ((args
->flags
& CLONE_PIDFD
) &&
2649 (args
->flags
& CLONE_PARENT_SETTID
) &&
2650 (args
->pidfd
== args
->parent_tid
))
2654 * Determine whether and which event to report to ptracer. When
2655 * called from kernel_thread or CLONE_UNTRACED is explicitly
2656 * requested, no event is reported; otherwise, report if the event
2657 * for the type of forking is enabled.
2659 if (!(clone_flags
& CLONE_UNTRACED
)) {
2660 if (clone_flags
& CLONE_VFORK
)
2661 trace
= PTRACE_EVENT_VFORK
;
2662 else if (args
->exit_signal
!= SIGCHLD
)
2663 trace
= PTRACE_EVENT_CLONE
;
2665 trace
= PTRACE_EVENT_FORK
;
2667 if (likely(!ptrace_event_enabled(current
, trace
)))
2671 p
= copy_process(NULL
, trace
, NUMA_NO_NODE
, args
);
2672 add_latent_entropy();
2678 * Do this prior waking up the new thread - the thread pointer
2679 * might get invalid after that point, if the thread exits quickly.
2681 trace_sched_process_fork(current
, p
);
2683 pid
= get_task_pid(p
, PIDTYPE_PID
);
2686 if (clone_flags
& CLONE_PARENT_SETTID
)
2687 put_user(nr
, args
->parent_tid
);
2689 if (clone_flags
& CLONE_VFORK
) {
2690 p
->vfork_done
= &vfork
;
2691 init_completion(&vfork
);
2695 if (IS_ENABLED(CONFIG_LRU_GEN
) && !(clone_flags
& CLONE_VM
)) {
2696 /* lock the task to synchronize with memcg migration */
2698 lru_gen_add_mm(p
->mm
);
2702 wake_up_new_task(p
);
2704 /* forking complete and child started to run, tell ptracer */
2705 if (unlikely(trace
))
2706 ptrace_event_pid(trace
, pid
);
2708 if (clone_flags
& CLONE_VFORK
) {
2709 if (!wait_for_vfork_done(p
, &vfork
))
2710 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2718 * Create a kernel thread.
2720 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2722 struct kernel_clone_args args
= {
2723 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2724 CLONE_UNTRACED
) & ~CSIGNAL
),
2725 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2731 return kernel_clone(&args
);
2735 * Create a user mode thread.
2737 pid_t
user_mode_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2739 struct kernel_clone_args args
= {
2740 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2741 CLONE_UNTRACED
) & ~CSIGNAL
),
2742 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2747 return kernel_clone(&args
);
2750 #ifdef __ARCH_WANT_SYS_FORK
2751 SYSCALL_DEFINE0(fork
)
2754 struct kernel_clone_args args
= {
2755 .exit_signal
= SIGCHLD
,
2758 return kernel_clone(&args
);
2760 /* can not support in nommu mode */
2766 #ifdef __ARCH_WANT_SYS_VFORK
2767 SYSCALL_DEFINE0(vfork
)
2769 struct kernel_clone_args args
= {
2770 .flags
= CLONE_VFORK
| CLONE_VM
,
2771 .exit_signal
= SIGCHLD
,
2774 return kernel_clone(&args
);
2778 #ifdef __ARCH_WANT_SYS_CLONE
2779 #ifdef CONFIG_CLONE_BACKWARDS
2780 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2781 int __user
*, parent_tidptr
,
2783 int __user
*, child_tidptr
)
2784 #elif defined(CONFIG_CLONE_BACKWARDS2)
2785 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2786 int __user
*, parent_tidptr
,
2787 int __user
*, child_tidptr
,
2789 #elif defined(CONFIG_CLONE_BACKWARDS3)
2790 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2792 int __user
*, parent_tidptr
,
2793 int __user
*, child_tidptr
,
2796 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2797 int __user
*, parent_tidptr
,
2798 int __user
*, child_tidptr
,
2802 struct kernel_clone_args args
= {
2803 .flags
= (lower_32_bits(clone_flags
) & ~CSIGNAL
),
2804 .pidfd
= parent_tidptr
,
2805 .child_tid
= child_tidptr
,
2806 .parent_tid
= parent_tidptr
,
2807 .exit_signal
= (lower_32_bits(clone_flags
) & CSIGNAL
),
2812 return kernel_clone(&args
);
2816 #ifdef __ARCH_WANT_SYS_CLONE3
2818 noinline
static int copy_clone_args_from_user(struct kernel_clone_args
*kargs
,
2819 struct clone_args __user
*uargs
,
2823 struct clone_args args
;
2824 pid_t
*kset_tid
= kargs
->set_tid
;
2826 BUILD_BUG_ON(offsetofend(struct clone_args
, tls
) !=
2827 CLONE_ARGS_SIZE_VER0
);
2828 BUILD_BUG_ON(offsetofend(struct clone_args
, set_tid_size
) !=
2829 CLONE_ARGS_SIZE_VER1
);
2830 BUILD_BUG_ON(offsetofend(struct clone_args
, cgroup
) !=
2831 CLONE_ARGS_SIZE_VER2
);
2832 BUILD_BUG_ON(sizeof(struct clone_args
) != CLONE_ARGS_SIZE_VER2
);
2834 if (unlikely(usize
> PAGE_SIZE
))
2836 if (unlikely(usize
< CLONE_ARGS_SIZE_VER0
))
2839 err
= copy_struct_from_user(&args
, sizeof(args
), uargs
, usize
);
2843 if (unlikely(args
.set_tid_size
> MAX_PID_NS_LEVEL
))
2846 if (unlikely(!args
.set_tid
&& args
.set_tid_size
> 0))
2849 if (unlikely(args
.set_tid
&& args
.set_tid_size
== 0))
2853 * Verify that higher 32bits of exit_signal are unset and that
2854 * it is a valid signal
2856 if (unlikely((args
.exit_signal
& ~((u64
)CSIGNAL
)) ||
2857 !valid_signal(args
.exit_signal
)))
2860 if ((args
.flags
& CLONE_INTO_CGROUP
) &&
2861 (args
.cgroup
> INT_MAX
|| usize
< CLONE_ARGS_SIZE_VER2
))
2864 *kargs
= (struct kernel_clone_args
){
2865 .flags
= args
.flags
,
2866 .pidfd
= u64_to_user_ptr(args
.pidfd
),
2867 .child_tid
= u64_to_user_ptr(args
.child_tid
),
2868 .parent_tid
= u64_to_user_ptr(args
.parent_tid
),
2869 .exit_signal
= args
.exit_signal
,
2870 .stack
= args
.stack
,
2871 .stack_size
= args
.stack_size
,
2873 .set_tid_size
= args
.set_tid_size
,
2874 .cgroup
= args
.cgroup
,
2878 copy_from_user(kset_tid
, u64_to_user_ptr(args
.set_tid
),
2879 (kargs
->set_tid_size
* sizeof(pid_t
))))
2882 kargs
->set_tid
= kset_tid
;
2888 * clone3_stack_valid - check and prepare stack
2889 * @kargs: kernel clone args
2891 * Verify that the stack arguments userspace gave us are sane.
2892 * In addition, set the stack direction for userspace since it's easy for us to
2895 static inline bool clone3_stack_valid(struct kernel_clone_args
*kargs
)
2897 if (kargs
->stack
== 0) {
2898 if (kargs
->stack_size
> 0)
2901 if (kargs
->stack_size
== 0)
2904 if (!access_ok((void __user
*)kargs
->stack
, kargs
->stack_size
))
2907 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2908 kargs
->stack
+= kargs
->stack_size
;
2915 static bool clone3_args_valid(struct kernel_clone_args
*kargs
)
2917 /* Verify that no unknown flags are passed along. */
2919 ~(CLONE_LEGACY_FLAGS
| CLONE_CLEAR_SIGHAND
| CLONE_INTO_CGROUP
))
2923 * - make the CLONE_DETACHED bit reusable for clone3
2924 * - make the CSIGNAL bits reusable for clone3
2926 if (kargs
->flags
& (CLONE_DETACHED
| CSIGNAL
))
2929 if ((kargs
->flags
& (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
)) ==
2930 (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
))
2933 if ((kargs
->flags
& (CLONE_THREAD
| CLONE_PARENT
)) &&
2937 if (!clone3_stack_valid(kargs
))
2944 * clone3 - create a new process with specific properties
2945 * @uargs: argument structure
2946 * @size: size of @uargs
2948 * clone3() is the extensible successor to clone()/clone2().
2949 * It takes a struct as argument that is versioned by its size.
2951 * Return: On success, a positive PID for the child process.
2952 * On error, a negative errno number.
2954 SYSCALL_DEFINE2(clone3
, struct clone_args __user
*, uargs
, size_t, size
)
2958 struct kernel_clone_args kargs
;
2959 pid_t set_tid
[MAX_PID_NS_LEVEL
];
2961 kargs
.set_tid
= set_tid
;
2963 err
= copy_clone_args_from_user(&kargs
, uargs
, size
);
2967 if (!clone3_args_valid(&kargs
))
2970 return kernel_clone(&kargs
);
2974 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2976 struct task_struct
*leader
, *parent
, *child
;
2979 read_lock(&tasklist_lock
);
2980 leader
= top
= top
->group_leader
;
2982 for_each_thread(leader
, parent
) {
2983 list_for_each_entry(child
, &parent
->children
, sibling
) {
2984 res
= visitor(child
, data
);
2996 if (leader
!= top
) {
2998 parent
= child
->real_parent
;
2999 leader
= parent
->group_leader
;
3003 read_unlock(&tasklist_lock
);
3006 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
3007 #define ARCH_MIN_MMSTRUCT_ALIGN 0
3010 static void sighand_ctor(void *data
)
3012 struct sighand_struct
*sighand
= data
;
3014 spin_lock_init(&sighand
->siglock
);
3015 init_waitqueue_head(&sighand
->signalfd_wqh
);
3018 void __init
proc_caches_init(void)
3020 unsigned int mm_size
;
3022 sighand_cachep
= kmem_cache_create("sighand_cache",
3023 sizeof(struct sighand_struct
), 0,
3024 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
3025 SLAB_ACCOUNT
, sighand_ctor
);
3026 signal_cachep
= kmem_cache_create("signal_cache",
3027 sizeof(struct signal_struct
), 0,
3028 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3030 files_cachep
= kmem_cache_create("files_cache",
3031 sizeof(struct files_struct
), 0,
3032 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3034 fs_cachep
= kmem_cache_create("fs_cache",
3035 sizeof(struct fs_struct
), 0,
3036 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3040 * The mm_cpumask is located at the end of mm_struct, and is
3041 * dynamically sized based on the maximum CPU number this system
3042 * can have, taking hotplug into account (nr_cpu_ids).
3044 mm_size
= sizeof(struct mm_struct
) + cpumask_size();
3046 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
3047 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
3048 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3049 offsetof(struct mm_struct
, saved_auxv
),
3050 sizeof_field(struct mm_struct
, saved_auxv
),
3052 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
3054 nsproxy_cache_init();
3058 * Check constraints on flags passed to the unshare system call.
3060 static int check_unshare_flags(unsigned long unshare_flags
)
3062 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
3063 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
3064 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
3065 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
|
3069 * Not implemented, but pretend it works if there is nothing
3070 * to unshare. Note that unsharing the address space or the
3071 * signal handlers also need to unshare the signal queues (aka
3074 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
3075 if (!thread_group_empty(current
))
3078 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
3079 if (refcount_read(¤t
->sighand
->count
) > 1)
3082 if (unshare_flags
& CLONE_VM
) {
3083 if (!current_is_single_threaded())
3091 * Unshare the filesystem structure if it is being shared
3093 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
3095 struct fs_struct
*fs
= current
->fs
;
3097 if (!(unshare_flags
& CLONE_FS
) || !fs
)
3100 /* don't need lock here; in the worst case we'll do useless copy */
3104 *new_fsp
= copy_fs_struct(fs
);
3112 * Unshare file descriptor table if it is being shared
3114 int unshare_fd(unsigned long unshare_flags
, unsigned int max_fds
,
3115 struct files_struct
**new_fdp
)
3117 struct files_struct
*fd
= current
->files
;
3120 if ((unshare_flags
& CLONE_FILES
) &&
3121 (fd
&& atomic_read(&fd
->count
) > 1)) {
3122 *new_fdp
= dup_fd(fd
, max_fds
, &error
);
3131 * unshare allows a process to 'unshare' part of the process
3132 * context which was originally shared using clone. copy_*
3133 * functions used by kernel_clone() cannot be used here directly
3134 * because they modify an inactive task_struct that is being
3135 * constructed. Here we are modifying the current, active,
3138 int ksys_unshare(unsigned long unshare_flags
)
3140 struct fs_struct
*fs
, *new_fs
= NULL
;
3141 struct files_struct
*new_fd
= NULL
;
3142 struct cred
*new_cred
= NULL
;
3143 struct nsproxy
*new_nsproxy
= NULL
;
3148 * If unsharing a user namespace must also unshare the thread group
3149 * and unshare the filesystem root and working directories.
3151 if (unshare_flags
& CLONE_NEWUSER
)
3152 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
3154 * If unsharing vm, must also unshare signal handlers.
3156 if (unshare_flags
& CLONE_VM
)
3157 unshare_flags
|= CLONE_SIGHAND
;
3159 * If unsharing a signal handlers, must also unshare the signal queues.
3161 if (unshare_flags
& CLONE_SIGHAND
)
3162 unshare_flags
|= CLONE_THREAD
;
3164 * If unsharing namespace, must also unshare filesystem information.
3166 if (unshare_flags
& CLONE_NEWNS
)
3167 unshare_flags
|= CLONE_FS
;
3169 err
= check_unshare_flags(unshare_flags
);
3171 goto bad_unshare_out
;
3173 * CLONE_NEWIPC must also detach from the undolist: after switching
3174 * to a new ipc namespace, the semaphore arrays from the old
3175 * namespace are unreachable.
3177 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
3179 err
= unshare_fs(unshare_flags
, &new_fs
);
3181 goto bad_unshare_out
;
3182 err
= unshare_fd(unshare_flags
, NR_OPEN_MAX
, &new_fd
);
3184 goto bad_unshare_cleanup_fs
;
3185 err
= unshare_userns(unshare_flags
, &new_cred
);
3187 goto bad_unshare_cleanup_fd
;
3188 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
3191 goto bad_unshare_cleanup_cred
;
3194 err
= set_cred_ucounts(new_cred
);
3196 goto bad_unshare_cleanup_cred
;
3199 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
3202 * CLONE_SYSVSEM is equivalent to sys_exit().
3206 if (unshare_flags
& CLONE_NEWIPC
) {
3207 /* Orphan segments in old ns (see sem above). */
3209 shm_init_task(current
);
3213 switch_task_namespaces(current
, new_nsproxy
);
3219 spin_lock(&fs
->lock
);
3220 current
->fs
= new_fs
;
3225 spin_unlock(&fs
->lock
);
3229 swap(current
->files
, new_fd
);
3231 task_unlock(current
);
3234 /* Install the new user namespace */
3235 commit_creds(new_cred
);
3240 perf_event_namespaces(current
);
3242 bad_unshare_cleanup_cred
:
3245 bad_unshare_cleanup_fd
:
3247 put_files_struct(new_fd
);
3249 bad_unshare_cleanup_fs
:
3251 free_fs_struct(new_fs
);
3257 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
3259 return ksys_unshare(unshare_flags
);
3263 * Helper to unshare the files of the current task.
3264 * We don't want to expose copy_files internals to
3265 * the exec layer of the kernel.
3268 int unshare_files(void)
3270 struct task_struct
*task
= current
;
3271 struct files_struct
*old
, *copy
= NULL
;
3274 error
= unshare_fd(CLONE_FILES
, NR_OPEN_MAX
, ©
);
3282 put_files_struct(old
);
3286 int sysctl_max_threads(struct ctl_table
*table
, int write
,
3287 void *buffer
, size_t *lenp
, loff_t
*ppos
)
3291 int threads
= max_threads
;
3293 int max
= MAX_THREADS
;
3300 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
3304 max_threads
= threads
;