1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/kernel/fork.c 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 */ 7 8 /* 9 * 'fork.c' contains the help-routines for the 'fork' system call 10 * (see also entry.S and others). 11 * Fork is rather simple, once you get the hang of it, but the memory 12 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' 13 */ 14 15 #include <linux/anon_inodes.h> 16 #include <linux/slab.h> 17 #include <linux/sched/autogroup.h> 18 #include <linux/sched/mm.h> 19 #include <linux/sched/coredump.h> 20 #include <linux/sched/user.h> 21 #include <linux/sched/numa_balancing.h> 22 #include <linux/sched/stat.h> 23 #include <linux/sched/task.h> 24 #include <linux/sched/task_stack.h> 25 #include <linux/sched/cputime.h> 26 #include <linux/seq_file.h> 27 #include <linux/rtmutex.h> 28 #include <linux/init.h> 29 #include <linux/unistd.h> 30 #include <linux/module.h> 31 #include <linux/vmalloc.h> 32 #include <linux/completion.h> 33 #include <linux/personality.h> 34 #include <linux/mempolicy.h> 35 #include <linux/sem.h> 36 #include <linux/file.h> 37 #include <linux/fdtable.h> 38 #include <linux/iocontext.h> 39 #include <linux/key.h> 40 #include <linux/binfmts.h> 41 #include <linux/mman.h> 42 #include <linux/mmu_notifier.h> 43 #include <linux/fs.h> 44 #include <linux/mm.h> 45 #include <linux/vmacache.h> 46 #include <linux/nsproxy.h> 47 #include <linux/capability.h> 48 #include <linux/cpu.h> 49 #include <linux/cgroup.h> 50 #include <linux/security.h> 51 #include <linux/hugetlb.h> 52 #include <linux/seccomp.h> 53 #include <linux/swap.h> 54 #include <linux/syscalls.h> 55 #include <linux/jiffies.h> 56 #include <linux/futex.h> 57 #include <linux/compat.h> 58 #include <linux/kthread.h> 59 #include <linux/task_io_accounting_ops.h> 60 #include <linux/rcupdate.h> 61 #include <linux/ptrace.h> 62 #include <linux/mount.h> 63 #include <linux/audit.h> 64 #include <linux/memcontrol.h> 65 #include <linux/ftrace.h> 66 #include <linux/proc_fs.h> 67 #include <linux/profile.h> 68 #include <linux/rmap.h> 69 #include <linux/ksm.h> 70 #include <linux/acct.h> 71 #include <linux/userfaultfd_k.h> 72 #include <linux/tsacct_kern.h> 73 #include <linux/cn_proc.h> 74 #include <linux/freezer.h> 75 #include <linux/delayacct.h> 76 #include <linux/taskstats_kern.h> 77 #include <linux/random.h> 78 #include <linux/tty.h> 79 #include <linux/blkdev.h> 80 #include <linux/fs_struct.h> 81 #include <linux/magic.h> 82 #include <linux/perf_event.h> 83 #include <linux/posix-timers.h> 84 #include <linux/user-return-notifier.h> 85 #include <linux/oom.h> 86 #include <linux/khugepaged.h> 87 #include <linux/signalfd.h> 88 #include <linux/uprobes.h> 89 #include <linux/aio.h> 90 #include <linux/compiler.h> 91 #include <linux/sysctl.h> 92 #include <linux/kcov.h> 93 #include <linux/livepatch.h> 94 #include <linux/thread_info.h> 95 #include <linux/stackleak.h> 96 #include <linux/kasan.h> 97 #include <linux/scs.h> 98 #include <linux/io_uring.h> 99 #include <linux/bpf.h> 100 101 #include <asm/pgalloc.h> 102 #include <linux/uaccess.h> 103 #include <asm/mmu_context.h> 104 #include <asm/cacheflush.h> 105 #include <asm/tlbflush.h> 106 107 #include <trace/events/sched.h> 108 109 #define CREATE_TRACE_POINTS 110 #include <trace/events/task.h> 111 112 /* 113 * Minimum number of threads to boot the kernel 114 */ 115 #define MIN_THREADS 20 116 117 /* 118 * Maximum number of threads 119 */ 120 #define MAX_THREADS FUTEX_TID_MASK 121 122 /* 123 * Protected counters by write_lock_irq(&tasklist_lock) 124 */ 125 unsigned long total_forks; /* Handle normal Linux uptimes. */ 126 int nr_threads; /* The idle threads do not count.. */ 127 128 static int max_threads; /* tunable limit on nr_threads */ 129 130 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x) 131 132 static const char * const resident_page_types[] = { 133 NAMED_ARRAY_INDEX(MM_FILEPAGES), 134 NAMED_ARRAY_INDEX(MM_ANONPAGES), 135 NAMED_ARRAY_INDEX(MM_SWAPENTS), 136 NAMED_ARRAY_INDEX(MM_SHMEMPAGES), 137 }; 138 139 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 140 141 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 142 143 #ifdef CONFIG_PROVE_RCU 144 int lockdep_tasklist_lock_is_held(void) 145 { 146 return lockdep_is_held(&tasklist_lock); 147 } 148 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); 149 #endif /* #ifdef CONFIG_PROVE_RCU */ 150 151 int nr_processes(void) 152 { 153 int cpu; 154 int total = 0; 155 156 for_each_possible_cpu(cpu) 157 total += per_cpu(process_counts, cpu); 158 159 return total; 160 } 161 162 void __weak arch_release_task_struct(struct task_struct *tsk) 163 { 164 } 165 166 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 167 static struct kmem_cache *task_struct_cachep; 168 169 static inline struct task_struct *alloc_task_struct_node(int node) 170 { 171 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); 172 } 173 174 static inline void free_task_struct(struct task_struct *tsk) 175 { 176 kmem_cache_free(task_struct_cachep, tsk); 177 } 178 #endif 179 180 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR 181 182 /* 183 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a 184 * kmemcache based allocator. 185 */ 186 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) 187 188 #ifdef CONFIG_VMAP_STACK 189 /* 190 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB 191 * flush. Try to minimize the number of calls by caching stacks. 192 */ 193 #define NR_CACHED_STACKS 2 194 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); 195 196 static int free_vm_stack_cache(unsigned int cpu) 197 { 198 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu); 199 int i; 200 201 for (i = 0; i < NR_CACHED_STACKS; i++) { 202 struct vm_struct *vm_stack = cached_vm_stacks[i]; 203 204 if (!vm_stack) 205 continue; 206 207 vfree(vm_stack->addr); 208 cached_vm_stacks[i] = NULL; 209 } 210 211 return 0; 212 } 213 #endif 214 215 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) 216 { 217 #ifdef CONFIG_VMAP_STACK 218 void *stack; 219 int i; 220 221 for (i = 0; i < NR_CACHED_STACKS; i++) { 222 struct vm_struct *s; 223 224 s = this_cpu_xchg(cached_stacks[i], NULL); 225 226 if (!s) 227 continue; 228 229 /* Mark stack accessible for KASAN. */ 230 kasan_unpoison_range(s->addr, THREAD_SIZE); 231 232 /* Clear stale pointers from reused stack. */ 233 memset(s->addr, 0, THREAD_SIZE); 234 235 tsk->stack_vm_area = s; 236 tsk->stack = s->addr; 237 return s->addr; 238 } 239 240 /* 241 * Allocated stacks are cached and later reused by new threads, 242 * so memcg accounting is performed manually on assigning/releasing 243 * stacks to tasks. Drop __GFP_ACCOUNT. 244 */ 245 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, 246 VMALLOC_START, VMALLOC_END, 247 THREADINFO_GFP & ~__GFP_ACCOUNT, 248 PAGE_KERNEL, 249 0, node, __builtin_return_address(0)); 250 251 /* 252 * We can't call find_vm_area() in interrupt context, and 253 * free_thread_stack() can be called in interrupt context, 254 * so cache the vm_struct. 255 */ 256 if (stack) { 257 tsk->stack_vm_area = find_vm_area(stack); 258 tsk->stack = stack; 259 } 260 return stack; 261 #else 262 struct page *page = alloc_pages_node(node, THREADINFO_GFP, 263 THREAD_SIZE_ORDER); 264 265 if (likely(page)) { 266 tsk->stack = kasan_reset_tag(page_address(page)); 267 return tsk->stack; 268 } 269 return NULL; 270 #endif 271 } 272 273 static inline void free_thread_stack(struct task_struct *tsk) 274 { 275 #ifdef CONFIG_VMAP_STACK 276 struct vm_struct *vm = task_stack_vm_area(tsk); 277 278 if (vm) { 279 int i; 280 281 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) 282 memcg_kmem_uncharge_page(vm->pages[i], 0); 283 284 for (i = 0; i < NR_CACHED_STACKS; i++) { 285 if (this_cpu_cmpxchg(cached_stacks[i], 286 NULL, tsk->stack_vm_area) != NULL) 287 continue; 288 289 return; 290 } 291 292 vfree_atomic(tsk->stack); 293 return; 294 } 295 #endif 296 297 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER); 298 } 299 # else 300 static struct kmem_cache *thread_stack_cache; 301 302 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, 303 int node) 304 { 305 unsigned long *stack; 306 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); 307 stack = kasan_reset_tag(stack); 308 tsk->stack = stack; 309 return stack; 310 } 311 312 static void free_thread_stack(struct task_struct *tsk) 313 { 314 kmem_cache_free(thread_stack_cache, tsk->stack); 315 } 316 317 void thread_stack_cache_init(void) 318 { 319 thread_stack_cache = kmem_cache_create_usercopy("thread_stack", 320 THREAD_SIZE, THREAD_SIZE, 0, 0, 321 THREAD_SIZE, NULL); 322 BUG_ON(thread_stack_cache == NULL); 323 } 324 # endif 325 #endif 326 327 /* SLAB cache for signal_struct structures (tsk->signal) */ 328 static struct kmem_cache *signal_cachep; 329 330 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 331 struct kmem_cache *sighand_cachep; 332 333 /* SLAB cache for files_struct structures (tsk->files) */ 334 struct kmem_cache *files_cachep; 335 336 /* SLAB cache for fs_struct structures (tsk->fs) */ 337 struct kmem_cache *fs_cachep; 338 339 /* SLAB cache for vm_area_struct structures */ 340 static struct kmem_cache *vm_area_cachep; 341 342 /* SLAB cache for mm_struct structures (tsk->mm) */ 343 static struct kmem_cache *mm_cachep; 344 345 struct vm_area_struct *vm_area_alloc(struct mm_struct *mm) 346 { 347 struct vm_area_struct *vma; 348 349 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 350 if (vma) 351 vma_init(vma, mm); 352 return vma; 353 } 354 355 struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) 356 { 357 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 358 359 if (new) { 360 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags); 361 ASSERT_EXCLUSIVE_WRITER(orig->vm_file); 362 /* 363 * orig->shared.rb may be modified concurrently, but the clone 364 * will be reinitialized. 365 */ 366 *new = data_race(*orig); 367 INIT_LIST_HEAD(&new->anon_vma_chain); 368 new->vm_next = new->vm_prev = NULL; 369 } 370 return new; 371 } 372 373 void vm_area_free(struct vm_area_struct *vma) 374 { 375 kmem_cache_free(vm_area_cachep, vma); 376 } 377 378 static void account_kernel_stack(struct task_struct *tsk, int account) 379 { 380 void *stack = task_stack_page(tsk); 381 struct vm_struct *vm = task_stack_vm_area(tsk); 382 383 if (vm) { 384 int i; 385 386 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) 387 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB, 388 account * (PAGE_SIZE / 1024)); 389 } else { 390 /* All stack pages are in the same node. */ 391 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB, 392 account * (THREAD_SIZE / 1024)); 393 } 394 } 395 396 static int memcg_charge_kernel_stack(struct task_struct *tsk) 397 { 398 #ifdef CONFIG_VMAP_STACK 399 struct vm_struct *vm = task_stack_vm_area(tsk); 400 int ret; 401 402 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0); 403 404 if (vm) { 405 int i; 406 407 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE); 408 409 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) { 410 /* 411 * If memcg_kmem_charge_page() fails, page's 412 * memory cgroup pointer is NULL, and 413 * memcg_kmem_uncharge_page() in free_thread_stack() 414 * will ignore this page. 415 */ 416 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 417 0); 418 if (ret) 419 return ret; 420 } 421 } 422 #endif 423 return 0; 424 } 425 426 static void release_task_stack(struct task_struct *tsk) 427 { 428 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD)) 429 return; /* Better to leak the stack than to free prematurely */ 430 431 account_kernel_stack(tsk, -1); 432 free_thread_stack(tsk); 433 tsk->stack = NULL; 434 #ifdef CONFIG_VMAP_STACK 435 tsk->stack_vm_area = NULL; 436 #endif 437 } 438 439 #ifdef CONFIG_THREAD_INFO_IN_TASK 440 void put_task_stack(struct task_struct *tsk) 441 { 442 if (refcount_dec_and_test(&tsk->stack_refcount)) 443 release_task_stack(tsk); 444 } 445 #endif 446 447 void free_task(struct task_struct *tsk) 448 { 449 release_user_cpus_ptr(tsk); 450 scs_release(tsk); 451 452 #ifndef CONFIG_THREAD_INFO_IN_TASK 453 /* 454 * The task is finally done with both the stack and thread_info, 455 * so free both. 456 */ 457 release_task_stack(tsk); 458 #else 459 /* 460 * If the task had a separate stack allocation, it should be gone 461 * by now. 462 */ 463 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0); 464 #endif 465 rt_mutex_debug_task_free(tsk); 466 ftrace_graph_exit_task(tsk); 467 arch_release_task_struct(tsk); 468 if (tsk->flags & PF_KTHREAD) 469 free_kthread_struct(tsk); 470 free_task_struct(tsk); 471 } 472 EXPORT_SYMBOL(free_task); 473 474 #ifdef CONFIG_MMU 475 static __latent_entropy int dup_mmap(struct mm_struct *mm, 476 struct mm_struct *oldmm) 477 { 478 struct vm_area_struct *mpnt, *tmp, *prev, **pprev; 479 struct rb_node **rb_link, *rb_parent; 480 int retval; 481 unsigned long charge; 482 LIST_HEAD(uf); 483 484 uprobe_start_dup_mmap(); 485 if (mmap_write_lock_killable(oldmm)) { 486 retval = -EINTR; 487 goto fail_uprobe_end; 488 } 489 flush_cache_dup_mm(oldmm); 490 uprobe_dup_mmap(oldmm, mm); 491 /* 492 * Not linked in yet - no deadlock potential: 493 */ 494 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING); 495 496 /* No ordering required: file already has been exposed. */ 497 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 498 499 mm->total_vm = oldmm->total_vm; 500 mm->data_vm = oldmm->data_vm; 501 mm->exec_vm = oldmm->exec_vm; 502 mm->stack_vm = oldmm->stack_vm; 503 504 rb_link = &mm->mm_rb.rb_node; 505 rb_parent = NULL; 506 pprev = &mm->mmap; 507 retval = ksm_fork(mm, oldmm); 508 if (retval) 509 goto out; 510 retval = khugepaged_fork(mm, oldmm); 511 if (retval) 512 goto out; 513 514 prev = NULL; 515 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 516 struct file *file; 517 518 if (mpnt->vm_flags & VM_DONTCOPY) { 519 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); 520 continue; 521 } 522 charge = 0; 523 /* 524 * Don't duplicate many vmas if we've been oom-killed (for 525 * example) 526 */ 527 if (fatal_signal_pending(current)) { 528 retval = -EINTR; 529 goto out; 530 } 531 if (mpnt->vm_flags & VM_ACCOUNT) { 532 unsigned long len = vma_pages(mpnt); 533 534 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ 535 goto fail_nomem; 536 charge = len; 537 } 538 tmp = vm_area_dup(mpnt); 539 if (!tmp) 540 goto fail_nomem; 541 retval = vma_dup_policy(mpnt, tmp); 542 if (retval) 543 goto fail_nomem_policy; 544 tmp->vm_mm = mm; 545 retval = dup_userfaultfd(tmp, &uf); 546 if (retval) 547 goto fail_nomem_anon_vma_fork; 548 if (tmp->vm_flags & VM_WIPEONFORK) { 549 /* 550 * VM_WIPEONFORK gets a clean slate in the child. 551 * Don't prepare anon_vma until fault since we don't 552 * copy page for current vma. 553 */ 554 tmp->anon_vma = NULL; 555 } else if (anon_vma_fork(tmp, mpnt)) 556 goto fail_nomem_anon_vma_fork; 557 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); 558 file = tmp->vm_file; 559 if (file) { 560 struct inode *inode = file_inode(file); 561 struct address_space *mapping = file->f_mapping; 562 563 get_file(file); 564 if (tmp->vm_flags & VM_DENYWRITE) 565 put_write_access(inode); 566 i_mmap_lock_write(mapping); 567 if (tmp->vm_flags & VM_SHARED) 568 mapping_allow_writable(mapping); 569 flush_dcache_mmap_lock(mapping); 570 /* insert tmp into the share list, just after mpnt */ 571 vma_interval_tree_insert_after(tmp, mpnt, 572 &mapping->i_mmap); 573 flush_dcache_mmap_unlock(mapping); 574 i_mmap_unlock_write(mapping); 575 } 576 577 /* 578 * Clear hugetlb-related page reserves for children. This only 579 * affects MAP_PRIVATE mappings. Faults generated by the child 580 * are not guaranteed to succeed, even if read-only 581 */ 582 if (is_vm_hugetlb_page(tmp)) 583 reset_vma_resv_huge_pages(tmp); 584 585 /* 586 * Link in the new vma and copy the page table entries. 587 */ 588 *pprev = tmp; 589 pprev = &tmp->vm_next; 590 tmp->vm_prev = prev; 591 prev = tmp; 592 593 __vma_link_rb(mm, tmp, rb_link, rb_parent); 594 rb_link = &tmp->vm_rb.rb_right; 595 rb_parent = &tmp->vm_rb; 596 597 mm->map_count++; 598 if (!(tmp->vm_flags & VM_WIPEONFORK)) 599 retval = copy_page_range(tmp, mpnt); 600 601 if (tmp->vm_ops && tmp->vm_ops->open) 602 tmp->vm_ops->open(tmp); 603 604 if (retval) 605 goto out; 606 } 607 /* a new mm has just been created */ 608 retval = arch_dup_mmap(oldmm, mm); 609 out: 610 mmap_write_unlock(mm); 611 flush_tlb_mm(oldmm); 612 mmap_write_unlock(oldmm); 613 dup_userfaultfd_complete(&uf); 614 fail_uprobe_end: 615 uprobe_end_dup_mmap(); 616 return retval; 617 fail_nomem_anon_vma_fork: 618 mpol_put(vma_policy(tmp)); 619 fail_nomem_policy: 620 vm_area_free(tmp); 621 fail_nomem: 622 retval = -ENOMEM; 623 vm_unacct_memory(charge); 624 goto out; 625 } 626 627 static inline int mm_alloc_pgd(struct mm_struct *mm) 628 { 629 mm->pgd = pgd_alloc(mm); 630 if (unlikely(!mm->pgd)) 631 return -ENOMEM; 632 return 0; 633 } 634 635 static inline void mm_free_pgd(struct mm_struct *mm) 636 { 637 pgd_free(mm, mm->pgd); 638 } 639 #else 640 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 641 { 642 mmap_write_lock(oldmm); 643 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 644 mmap_write_unlock(oldmm); 645 return 0; 646 } 647 #define mm_alloc_pgd(mm) (0) 648 #define mm_free_pgd(mm) 649 #endif /* CONFIG_MMU */ 650 651 static void check_mm(struct mm_struct *mm) 652 { 653 int i; 654 655 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS, 656 "Please make sure 'struct resident_page_types[]' is updated as well"); 657 658 for (i = 0; i < NR_MM_COUNTERS; i++) { 659 long x = atomic_long_read(&mm->rss_stat.count[i]); 660 661 if (unlikely(x)) 662 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n", 663 mm, resident_page_types[i], x); 664 } 665 666 if (mm_pgtables_bytes(mm)) 667 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n", 668 mm_pgtables_bytes(mm)); 669 670 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 671 VM_BUG_ON_MM(mm->pmd_huge_pte, mm); 672 #endif 673 } 674 675 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 676 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 677 678 /* 679 * Called when the last reference to the mm 680 * is dropped: either by a lazy thread or by 681 * mmput. Free the page directory and the mm. 682 */ 683 void __mmdrop(struct mm_struct *mm) 684 { 685 BUG_ON(mm == &init_mm); 686 WARN_ON_ONCE(mm == current->mm); 687 WARN_ON_ONCE(mm == current->active_mm); 688 mm_free_pgd(mm); 689 destroy_context(mm); 690 mmu_notifier_subscriptions_destroy(mm); 691 check_mm(mm); 692 put_user_ns(mm->user_ns); 693 free_mm(mm); 694 } 695 EXPORT_SYMBOL_GPL(__mmdrop); 696 697 static void mmdrop_async_fn(struct work_struct *work) 698 { 699 struct mm_struct *mm; 700 701 mm = container_of(work, struct mm_struct, async_put_work); 702 __mmdrop(mm); 703 } 704 705 static void mmdrop_async(struct mm_struct *mm) 706 { 707 if (unlikely(atomic_dec_and_test(&mm->mm_count))) { 708 INIT_WORK(&mm->async_put_work, mmdrop_async_fn); 709 schedule_work(&mm->async_put_work); 710 } 711 } 712 713 static inline void free_signal_struct(struct signal_struct *sig) 714 { 715 taskstats_tgid_free(sig); 716 sched_autogroup_exit(sig); 717 /* 718 * __mmdrop is not safe to call from softirq context on x86 due to 719 * pgd_dtor so postpone it to the async context 720 */ 721 if (sig->oom_mm) 722 mmdrop_async(sig->oom_mm); 723 kmem_cache_free(signal_cachep, sig); 724 } 725 726 static inline void put_signal_struct(struct signal_struct *sig) 727 { 728 if (refcount_dec_and_test(&sig->sigcnt)) 729 free_signal_struct(sig); 730 } 731 732 void __put_task_struct(struct task_struct *tsk) 733 { 734 WARN_ON(!tsk->exit_state); 735 WARN_ON(refcount_read(&tsk->usage)); 736 WARN_ON(tsk == current); 737 738 io_uring_free(tsk); 739 cgroup_free(tsk); 740 task_numa_free(tsk, true); 741 security_task_free(tsk); 742 bpf_task_storage_free(tsk); 743 exit_creds(tsk); 744 delayacct_tsk_free(tsk); 745 put_signal_struct(tsk->signal); 746 sched_core_free(tsk); 747 748 if (!profile_handoff_task(tsk)) 749 free_task(tsk); 750 } 751 EXPORT_SYMBOL_GPL(__put_task_struct); 752 753 void __init __weak arch_task_cache_init(void) { } 754 755 /* 756 * set_max_threads 757 */ 758 static void set_max_threads(unsigned int max_threads_suggested) 759 { 760 u64 threads; 761 unsigned long nr_pages = totalram_pages(); 762 763 /* 764 * The number of threads shall be limited such that the thread 765 * structures may only consume a small part of the available memory. 766 */ 767 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64) 768 threads = MAX_THREADS; 769 else 770 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE, 771 (u64) THREAD_SIZE * 8UL); 772 773 if (threads > max_threads_suggested) 774 threads = max_threads_suggested; 775 776 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS); 777 } 778 779 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT 780 /* Initialized by the architecture: */ 781 int arch_task_struct_size __read_mostly; 782 #endif 783 784 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 785 static void task_struct_whitelist(unsigned long *offset, unsigned long *size) 786 { 787 /* Fetch thread_struct whitelist for the architecture. */ 788 arch_thread_struct_whitelist(offset, size); 789 790 /* 791 * Handle zero-sized whitelist or empty thread_struct, otherwise 792 * adjust offset to position of thread_struct in task_struct. 793 */ 794 if (unlikely(*size == 0)) 795 *offset = 0; 796 else 797 *offset += offsetof(struct task_struct, thread); 798 } 799 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */ 800 801 void __init fork_init(void) 802 { 803 int i; 804 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 805 #ifndef ARCH_MIN_TASKALIGN 806 #define ARCH_MIN_TASKALIGN 0 807 #endif 808 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN); 809 unsigned long useroffset, usersize; 810 811 /* create a slab on which task_structs can be allocated */ 812 task_struct_whitelist(&useroffset, &usersize); 813 task_struct_cachep = kmem_cache_create_usercopy("task_struct", 814 arch_task_struct_size, align, 815 SLAB_PANIC|SLAB_ACCOUNT, 816 useroffset, usersize, NULL); 817 #endif 818 819 /* do the arch specific task caches init */ 820 arch_task_cache_init(); 821 822 set_max_threads(MAX_THREADS); 823 824 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 825 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 826 init_task.signal->rlim[RLIMIT_SIGPENDING] = 827 init_task.signal->rlim[RLIMIT_NPROC]; 828 829 for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) 830 init_user_ns.ucount_max[i] = max_threads/2; 831 832 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY); 833 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY); 834 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY); 835 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY); 836 837 #ifdef CONFIG_VMAP_STACK 838 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", 839 NULL, free_vm_stack_cache); 840 #endif 841 842 scs_init(); 843 844 lockdep_init_task(&init_task); 845 uprobes_init(); 846 } 847 848 int __weak arch_dup_task_struct(struct task_struct *dst, 849 struct task_struct *src) 850 { 851 *dst = *src; 852 return 0; 853 } 854 855 void set_task_stack_end_magic(struct task_struct *tsk) 856 { 857 unsigned long *stackend; 858 859 stackend = end_of_stack(tsk); 860 *stackend = STACK_END_MAGIC; /* for overflow detection */ 861 } 862 863 static struct task_struct *dup_task_struct(struct task_struct *orig, int node) 864 { 865 struct task_struct *tsk; 866 unsigned long *stack; 867 struct vm_struct *stack_vm_area __maybe_unused; 868 int err; 869 870 if (node == NUMA_NO_NODE) 871 node = tsk_fork_get_node(orig); 872 tsk = alloc_task_struct_node(node); 873 if (!tsk) 874 return NULL; 875 876 stack = alloc_thread_stack_node(tsk, node); 877 if (!stack) 878 goto free_tsk; 879 880 if (memcg_charge_kernel_stack(tsk)) 881 goto free_stack; 882 883 stack_vm_area = task_stack_vm_area(tsk); 884 885 err = arch_dup_task_struct(tsk, orig); 886 887 /* 888 * arch_dup_task_struct() clobbers the stack-related fields. Make 889 * sure they're properly initialized before using any stack-related 890 * functions again. 891 */ 892 tsk->stack = stack; 893 #ifdef CONFIG_VMAP_STACK 894 tsk->stack_vm_area = stack_vm_area; 895 #endif 896 #ifdef CONFIG_THREAD_INFO_IN_TASK 897 refcount_set(&tsk->stack_refcount, 1); 898 #endif 899 900 if (err) 901 goto free_stack; 902 903 err = scs_prepare(tsk, node); 904 if (err) 905 goto free_stack; 906 907 #ifdef CONFIG_SECCOMP 908 /* 909 * We must handle setting up seccomp filters once we're under 910 * the sighand lock in case orig has changed between now and 911 * then. Until then, filter must be NULL to avoid messing up 912 * the usage counts on the error path calling free_task. 913 */ 914 tsk->seccomp.filter = NULL; 915 #endif 916 917 setup_thread_stack(tsk, orig); 918 clear_user_return_notifier(tsk); 919 clear_tsk_need_resched(tsk); 920 set_task_stack_end_magic(tsk); 921 clear_syscall_work_syscall_user_dispatch(tsk); 922 923 #ifdef CONFIG_STACKPROTECTOR 924 tsk->stack_canary = get_random_canary(); 925 #endif 926 if (orig->cpus_ptr == &orig->cpus_mask) 927 tsk->cpus_ptr = &tsk->cpus_mask; 928 dup_user_cpus_ptr(tsk, orig, node); 929 930 /* 931 * One for the user space visible state that goes away when reaped. 932 * One for the scheduler. 933 */ 934 refcount_set(&tsk->rcu_users, 2); 935 /* One for the rcu users */ 936 refcount_set(&tsk->usage, 1); 937 #ifdef CONFIG_BLK_DEV_IO_TRACE 938 tsk->btrace_seq = 0; 939 #endif 940 tsk->splice_pipe = NULL; 941 tsk->task_frag.page = NULL; 942 tsk->wake_q.next = NULL; 943 tsk->pf_io_worker = NULL; 944 945 account_kernel_stack(tsk, 1); 946 947 kcov_task_init(tsk); 948 kmap_local_fork(tsk); 949 950 #ifdef CONFIG_FAULT_INJECTION 951 tsk->fail_nth = 0; 952 #endif 953 954 #ifdef CONFIG_BLK_CGROUP 955 tsk->throttle_queue = NULL; 956 tsk->use_memdelay = 0; 957 #endif 958 959 #ifdef CONFIG_MEMCG 960 tsk->active_memcg = NULL; 961 #endif 962 return tsk; 963 964 free_stack: 965 free_thread_stack(tsk); 966 free_tsk: 967 free_task_struct(tsk); 968 return NULL; 969 } 970 971 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 972 973 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; 974 975 static int __init coredump_filter_setup(char *s) 976 { 977 default_dump_filter = 978 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & 979 MMF_DUMP_FILTER_MASK; 980 return 1; 981 } 982 983 __setup("coredump_filter=", coredump_filter_setup); 984 985 #include <linux/init_task.h> 986 987 static void mm_init_aio(struct mm_struct *mm) 988 { 989 #ifdef CONFIG_AIO 990 spin_lock_init(&mm->ioctx_lock); 991 mm->ioctx_table = NULL; 992 #endif 993 } 994 995 static __always_inline void mm_clear_owner(struct mm_struct *mm, 996 struct task_struct *p) 997 { 998 #ifdef CONFIG_MEMCG 999 if (mm->owner == p) 1000 WRITE_ONCE(mm->owner, NULL); 1001 #endif 1002 } 1003 1004 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) 1005 { 1006 #ifdef CONFIG_MEMCG 1007 mm->owner = p; 1008 #endif 1009 } 1010 1011 static void mm_init_pasid(struct mm_struct *mm) 1012 { 1013 #ifdef CONFIG_IOMMU_SUPPORT 1014 mm->pasid = INIT_PASID; 1015 #endif 1016 } 1017 1018 static void mm_init_uprobes_state(struct mm_struct *mm) 1019 { 1020 #ifdef CONFIG_UPROBES 1021 mm->uprobes_state.xol_area = NULL; 1022 #endif 1023 } 1024 1025 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, 1026 struct user_namespace *user_ns) 1027 { 1028 mm->mmap = NULL; 1029 mm->mm_rb = RB_ROOT; 1030 mm->vmacache_seqnum = 0; 1031 atomic_set(&mm->mm_users, 1); 1032 atomic_set(&mm->mm_count, 1); 1033 seqcount_init(&mm->write_protect_seq); 1034 mmap_init_lock(mm); 1035 INIT_LIST_HEAD(&mm->mmlist); 1036 mm->core_state = NULL; 1037 mm_pgtables_bytes_init(mm); 1038 mm->map_count = 0; 1039 mm->locked_vm = 0; 1040 atomic64_set(&mm->pinned_vm, 0); 1041 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); 1042 spin_lock_init(&mm->page_table_lock); 1043 spin_lock_init(&mm->arg_lock); 1044 mm_init_cpumask(mm); 1045 mm_init_aio(mm); 1046 mm_init_owner(mm, p); 1047 mm_init_pasid(mm); 1048 RCU_INIT_POINTER(mm->exe_file, NULL); 1049 mmu_notifier_subscriptions_init(mm); 1050 init_tlb_flush_pending(mm); 1051 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 1052 mm->pmd_huge_pte = NULL; 1053 #endif 1054 mm_init_uprobes_state(mm); 1055 1056 if (current->mm) { 1057 mm->flags = current->mm->flags & MMF_INIT_MASK; 1058 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; 1059 } else { 1060 mm->flags = default_dump_filter; 1061 mm->def_flags = 0; 1062 } 1063 1064 if (mm_alloc_pgd(mm)) 1065 goto fail_nopgd; 1066 1067 if (init_new_context(p, mm)) 1068 goto fail_nocontext; 1069 1070 mm->user_ns = get_user_ns(user_ns); 1071 return mm; 1072 1073 fail_nocontext: 1074 mm_free_pgd(mm); 1075 fail_nopgd: 1076 free_mm(mm); 1077 return NULL; 1078 } 1079 1080 /* 1081 * Allocate and initialize an mm_struct. 1082 */ 1083 struct mm_struct *mm_alloc(void) 1084 { 1085 struct mm_struct *mm; 1086 1087 mm = allocate_mm(); 1088 if (!mm) 1089 return NULL; 1090 1091 memset(mm, 0, sizeof(*mm)); 1092 return mm_init(mm, current, current_user_ns()); 1093 } 1094 1095 static inline void __mmput(struct mm_struct *mm) 1096 { 1097 VM_BUG_ON(atomic_read(&mm->mm_users)); 1098 1099 uprobe_clear_state(mm); 1100 exit_aio(mm); 1101 ksm_exit(mm); 1102 khugepaged_exit(mm); /* must run before exit_mmap */ 1103 exit_mmap(mm); 1104 mm_put_huge_zero_page(mm); 1105 set_mm_exe_file(mm, NULL); 1106 if (!list_empty(&mm->mmlist)) { 1107 spin_lock(&mmlist_lock); 1108 list_del(&mm->mmlist); 1109 spin_unlock(&mmlist_lock); 1110 } 1111 if (mm->binfmt) 1112 module_put(mm->binfmt->module); 1113 mmdrop(mm); 1114 } 1115 1116 /* 1117 * Decrement the use count and release all resources for an mm. 1118 */ 1119 void mmput(struct mm_struct *mm) 1120 { 1121 might_sleep(); 1122 1123 if (atomic_dec_and_test(&mm->mm_users)) 1124 __mmput(mm); 1125 } 1126 EXPORT_SYMBOL_GPL(mmput); 1127 1128 #ifdef CONFIG_MMU 1129 static void mmput_async_fn(struct work_struct *work) 1130 { 1131 struct mm_struct *mm = container_of(work, struct mm_struct, 1132 async_put_work); 1133 1134 __mmput(mm); 1135 } 1136 1137 void mmput_async(struct mm_struct *mm) 1138 { 1139 if (atomic_dec_and_test(&mm->mm_users)) { 1140 INIT_WORK(&mm->async_put_work, mmput_async_fn); 1141 schedule_work(&mm->async_put_work); 1142 } 1143 } 1144 #endif 1145 1146 /** 1147 * set_mm_exe_file - change a reference to the mm's executable file 1148 * 1149 * This changes mm's executable file (shown as symlink /proc/[pid]/exe). 1150 * 1151 * Main users are mmput() and sys_execve(). Callers prevent concurrent 1152 * invocations: in mmput() nobody alive left, in execve task is single 1153 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the 1154 * mm->exe_file, but does so without using set_mm_exe_file() in order 1155 * to avoid the need for any locks. 1156 */ 1157 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) 1158 { 1159 struct file *old_exe_file; 1160 1161 /* 1162 * It is safe to dereference the exe_file without RCU as 1163 * this function is only called if nobody else can access 1164 * this mm -- see comment above for justification. 1165 */ 1166 old_exe_file = rcu_dereference_raw(mm->exe_file); 1167 1168 if (new_exe_file) 1169 get_file(new_exe_file); 1170 rcu_assign_pointer(mm->exe_file, new_exe_file); 1171 if (old_exe_file) 1172 fput(old_exe_file); 1173 } 1174 1175 /** 1176 * get_mm_exe_file - acquire a reference to the mm's executable file 1177 * 1178 * Returns %NULL if mm has no associated executable file. 1179 * User must release file via fput(). 1180 */ 1181 struct file *get_mm_exe_file(struct mm_struct *mm) 1182 { 1183 struct file *exe_file; 1184 1185 rcu_read_lock(); 1186 exe_file = rcu_dereference(mm->exe_file); 1187 if (exe_file && !get_file_rcu(exe_file)) 1188 exe_file = NULL; 1189 rcu_read_unlock(); 1190 return exe_file; 1191 } 1192 EXPORT_SYMBOL(get_mm_exe_file); 1193 1194 /** 1195 * get_task_exe_file - acquire a reference to the task's executable file 1196 * 1197 * Returns %NULL if task's mm (if any) has no associated executable file or 1198 * this is a kernel thread with borrowed mm (see the comment above get_task_mm). 1199 * User must release file via fput(). 1200 */ 1201 struct file *get_task_exe_file(struct task_struct *task) 1202 { 1203 struct file *exe_file = NULL; 1204 struct mm_struct *mm; 1205 1206 task_lock(task); 1207 mm = task->mm; 1208 if (mm) { 1209 if (!(task->flags & PF_KTHREAD)) 1210 exe_file = get_mm_exe_file(mm); 1211 } 1212 task_unlock(task); 1213 return exe_file; 1214 } 1215 EXPORT_SYMBOL(get_task_exe_file); 1216 1217 /** 1218 * get_task_mm - acquire a reference to the task's mm 1219 * 1220 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning 1221 * this kernel workthread has transiently adopted a user mm with use_mm, 1222 * to do its AIO) is not set and if so returns a reference to it, after 1223 * bumping up the use count. User must release the mm via mmput() 1224 * after use. Typically used by /proc and ptrace. 1225 */ 1226 struct mm_struct *get_task_mm(struct task_struct *task) 1227 { 1228 struct mm_struct *mm; 1229 1230 task_lock(task); 1231 mm = task->mm; 1232 if (mm) { 1233 if (task->flags & PF_KTHREAD) 1234 mm = NULL; 1235 else 1236 mmget(mm); 1237 } 1238 task_unlock(task); 1239 return mm; 1240 } 1241 EXPORT_SYMBOL_GPL(get_task_mm); 1242 1243 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) 1244 { 1245 struct mm_struct *mm; 1246 int err; 1247 1248 err = down_read_killable(&task->signal->exec_update_lock); 1249 if (err) 1250 return ERR_PTR(err); 1251 1252 mm = get_task_mm(task); 1253 if (mm && mm != current->mm && 1254 !ptrace_may_access(task, mode)) { 1255 mmput(mm); 1256 mm = ERR_PTR(-EACCES); 1257 } 1258 up_read(&task->signal->exec_update_lock); 1259 1260 return mm; 1261 } 1262 1263 static void complete_vfork_done(struct task_struct *tsk) 1264 { 1265 struct completion *vfork; 1266 1267 task_lock(tsk); 1268 vfork = tsk->vfork_done; 1269 if (likely(vfork)) { 1270 tsk->vfork_done = NULL; 1271 complete(vfork); 1272 } 1273 task_unlock(tsk); 1274 } 1275 1276 static int wait_for_vfork_done(struct task_struct *child, 1277 struct completion *vfork) 1278 { 1279 int killed; 1280 1281 freezer_do_not_count(); 1282 cgroup_enter_frozen(); 1283 killed = wait_for_completion_killable(vfork); 1284 cgroup_leave_frozen(false); 1285 freezer_count(); 1286 1287 if (killed) { 1288 task_lock(child); 1289 child->vfork_done = NULL; 1290 task_unlock(child); 1291 } 1292 1293 put_task_struct(child); 1294 return killed; 1295 } 1296 1297 /* Please note the differences between mmput and mm_release. 1298 * mmput is called whenever we stop holding onto a mm_struct, 1299 * error success whatever. 1300 * 1301 * mm_release is called after a mm_struct has been removed 1302 * from the current process. 1303 * 1304 * This difference is important for error handling, when we 1305 * only half set up a mm_struct for a new process and need to restore 1306 * the old one. Because we mmput the new mm_struct before 1307 * restoring the old one. . . 1308 * Eric Biederman 10 January 1998 1309 */ 1310 static void mm_release(struct task_struct *tsk, struct mm_struct *mm) 1311 { 1312 uprobe_free_utask(tsk); 1313 1314 /* Get rid of any cached register state */ 1315 deactivate_mm(tsk, mm); 1316 1317 /* 1318 * Signal userspace if we're not exiting with a core dump 1319 * because we want to leave the value intact for debugging 1320 * purposes. 1321 */ 1322 if (tsk->clear_child_tid) { 1323 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) && 1324 atomic_read(&mm->mm_users) > 1) { 1325 /* 1326 * We don't check the error code - if userspace has 1327 * not set up a proper pointer then tough luck. 1328 */ 1329 put_user(0, tsk->clear_child_tid); 1330 do_futex(tsk->clear_child_tid, FUTEX_WAKE, 1331 1, NULL, NULL, 0, 0); 1332 } 1333 tsk->clear_child_tid = NULL; 1334 } 1335 1336 /* 1337 * All done, finally we can wake up parent and return this mm to him. 1338 * Also kthread_stop() uses this completion for synchronization. 1339 */ 1340 if (tsk->vfork_done) 1341 complete_vfork_done(tsk); 1342 } 1343 1344 void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm) 1345 { 1346 futex_exit_release(tsk); 1347 mm_release(tsk, mm); 1348 } 1349 1350 void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm) 1351 { 1352 futex_exec_release(tsk); 1353 mm_release(tsk, mm); 1354 } 1355 1356 /** 1357 * dup_mm() - duplicates an existing mm structure 1358 * @tsk: the task_struct with which the new mm will be associated. 1359 * @oldmm: the mm to duplicate. 1360 * 1361 * Allocates a new mm structure and duplicates the provided @oldmm structure 1362 * content into it. 1363 * 1364 * Return: the duplicated mm or NULL on failure. 1365 */ 1366 static struct mm_struct *dup_mm(struct task_struct *tsk, 1367 struct mm_struct *oldmm) 1368 { 1369 struct mm_struct *mm; 1370 int err; 1371 1372 mm = allocate_mm(); 1373 if (!mm) 1374 goto fail_nomem; 1375 1376 memcpy(mm, oldmm, sizeof(*mm)); 1377 1378 if (!mm_init(mm, tsk, mm->user_ns)) 1379 goto fail_nomem; 1380 1381 err = dup_mmap(mm, oldmm); 1382 if (err) 1383 goto free_pt; 1384 1385 mm->hiwater_rss = get_mm_rss(mm); 1386 mm->hiwater_vm = mm->total_vm; 1387 1388 if (mm->binfmt && !try_module_get(mm->binfmt->module)) 1389 goto free_pt; 1390 1391 return mm; 1392 1393 free_pt: 1394 /* don't put binfmt in mmput, we haven't got module yet */ 1395 mm->binfmt = NULL; 1396 mm_init_owner(mm, NULL); 1397 mmput(mm); 1398 1399 fail_nomem: 1400 return NULL; 1401 } 1402 1403 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) 1404 { 1405 struct mm_struct *mm, *oldmm; 1406 1407 tsk->min_flt = tsk->maj_flt = 0; 1408 tsk->nvcsw = tsk->nivcsw = 0; 1409 #ifdef CONFIG_DETECT_HUNG_TASK 1410 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; 1411 tsk->last_switch_time = 0; 1412 #endif 1413 1414 tsk->mm = NULL; 1415 tsk->active_mm = NULL; 1416 1417 /* 1418 * Are we cloning a kernel thread? 1419 * 1420 * We need to steal a active VM for that.. 1421 */ 1422 oldmm = current->mm; 1423 if (!oldmm) 1424 return 0; 1425 1426 /* initialize the new vmacache entries */ 1427 vmacache_flush(tsk); 1428 1429 if (clone_flags & CLONE_VM) { 1430 mmget(oldmm); 1431 mm = oldmm; 1432 } else { 1433 mm = dup_mm(tsk, current->mm); 1434 if (!mm) 1435 return -ENOMEM; 1436 } 1437 1438 tsk->mm = mm; 1439 tsk->active_mm = mm; 1440 return 0; 1441 } 1442 1443 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 1444 { 1445 struct fs_struct *fs = current->fs; 1446 if (clone_flags & CLONE_FS) { 1447 /* tsk->fs is already what we want */ 1448 spin_lock(&fs->lock); 1449 if (fs->in_exec) { 1450 spin_unlock(&fs->lock); 1451 return -EAGAIN; 1452 } 1453 fs->users++; 1454 spin_unlock(&fs->lock); 1455 return 0; 1456 } 1457 tsk->fs = copy_fs_struct(fs); 1458 if (!tsk->fs) 1459 return -ENOMEM; 1460 return 0; 1461 } 1462 1463 static int copy_files(unsigned long clone_flags, struct task_struct *tsk) 1464 { 1465 struct files_struct *oldf, *newf; 1466 int error = 0; 1467 1468 /* 1469 * A background process may not have any files ... 1470 */ 1471 oldf = current->files; 1472 if (!oldf) 1473 goto out; 1474 1475 if (clone_flags & CLONE_FILES) { 1476 atomic_inc(&oldf->count); 1477 goto out; 1478 } 1479 1480 newf = dup_fd(oldf, NR_OPEN_MAX, &error); 1481 if (!newf) 1482 goto out; 1483 1484 tsk->files = newf; 1485 error = 0; 1486 out: 1487 return error; 1488 } 1489 1490 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 1491 { 1492 #ifdef CONFIG_BLOCK 1493 struct io_context *ioc = current->io_context; 1494 struct io_context *new_ioc; 1495 1496 if (!ioc) 1497 return 0; 1498 /* 1499 * Share io context with parent, if CLONE_IO is set 1500 */ 1501 if (clone_flags & CLONE_IO) { 1502 ioc_task_link(ioc); 1503 tsk->io_context = ioc; 1504 } else if (ioprio_valid(ioc->ioprio)) { 1505 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); 1506 if (unlikely(!new_ioc)) 1507 return -ENOMEM; 1508 1509 new_ioc->ioprio = ioc->ioprio; 1510 put_io_context(new_ioc); 1511 } 1512 #endif 1513 return 0; 1514 } 1515 1516 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 1517 { 1518 struct sighand_struct *sig; 1519 1520 if (clone_flags & CLONE_SIGHAND) { 1521 refcount_inc(¤t->sighand->count); 1522 return 0; 1523 } 1524 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 1525 RCU_INIT_POINTER(tsk->sighand, sig); 1526 if (!sig) 1527 return -ENOMEM; 1528 1529 refcount_set(&sig->count, 1); 1530 spin_lock_irq(¤t->sighand->siglock); 1531 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 1532 spin_unlock_irq(¤t->sighand->siglock); 1533 1534 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */ 1535 if (clone_flags & CLONE_CLEAR_SIGHAND) 1536 flush_signal_handlers(tsk, 0); 1537 1538 return 0; 1539 } 1540 1541 void __cleanup_sighand(struct sighand_struct *sighand) 1542 { 1543 if (refcount_dec_and_test(&sighand->count)) { 1544 signalfd_cleanup(sighand); 1545 /* 1546 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it 1547 * without an RCU grace period, see __lock_task_sighand(). 1548 */ 1549 kmem_cache_free(sighand_cachep, sighand); 1550 } 1551 } 1552 1553 /* 1554 * Initialize POSIX timer handling for a thread group. 1555 */ 1556 static void posix_cpu_timers_init_group(struct signal_struct *sig) 1557 { 1558 struct posix_cputimers *pct = &sig->posix_cputimers; 1559 unsigned long cpu_limit; 1560 1561 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); 1562 posix_cputimers_group_init(pct, cpu_limit); 1563 } 1564 1565 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 1566 { 1567 struct signal_struct *sig; 1568 1569 if (clone_flags & CLONE_THREAD) 1570 return 0; 1571 1572 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); 1573 tsk->signal = sig; 1574 if (!sig) 1575 return -ENOMEM; 1576 1577 sig->nr_threads = 1; 1578 atomic_set(&sig->live, 1); 1579 refcount_set(&sig->sigcnt, 1); 1580 1581 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ 1582 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); 1583 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); 1584 1585 init_waitqueue_head(&sig->wait_chldexit); 1586 sig->curr_target = tsk; 1587 init_sigpending(&sig->shared_pending); 1588 INIT_HLIST_HEAD(&sig->multiprocess); 1589 seqlock_init(&sig->stats_lock); 1590 prev_cputime_init(&sig->prev_cputime); 1591 1592 #ifdef CONFIG_POSIX_TIMERS 1593 INIT_LIST_HEAD(&sig->posix_timers); 1594 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 1595 sig->real_timer.function = it_real_fn; 1596 #endif 1597 1598 task_lock(current->group_leader); 1599 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 1600 task_unlock(current->group_leader); 1601 1602 posix_cpu_timers_init_group(sig); 1603 1604 tty_audit_fork(sig); 1605 sched_autogroup_fork(sig); 1606 1607 sig->oom_score_adj = current->signal->oom_score_adj; 1608 sig->oom_score_adj_min = current->signal->oom_score_adj_min; 1609 1610 mutex_init(&sig->cred_guard_mutex); 1611 init_rwsem(&sig->exec_update_lock); 1612 1613 return 0; 1614 } 1615 1616 static void copy_seccomp(struct task_struct *p) 1617 { 1618 #ifdef CONFIG_SECCOMP 1619 /* 1620 * Must be called with sighand->lock held, which is common to 1621 * all threads in the group. Holding cred_guard_mutex is not 1622 * needed because this new task is not yet running and cannot 1623 * be racing exec. 1624 */ 1625 assert_spin_locked(¤t->sighand->siglock); 1626 1627 /* Ref-count the new filter user, and assign it. */ 1628 get_seccomp_filter(current); 1629 p->seccomp = current->seccomp; 1630 1631 /* 1632 * Explicitly enable no_new_privs here in case it got set 1633 * between the task_struct being duplicated and holding the 1634 * sighand lock. The seccomp state and nnp must be in sync. 1635 */ 1636 if (task_no_new_privs(current)) 1637 task_set_no_new_privs(p); 1638 1639 /* 1640 * If the parent gained a seccomp mode after copying thread 1641 * flags and between before we held the sighand lock, we have 1642 * to manually enable the seccomp thread flag here. 1643 */ 1644 if (p->seccomp.mode != SECCOMP_MODE_DISABLED) 1645 set_task_syscall_work(p, SECCOMP); 1646 #endif 1647 } 1648 1649 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) 1650 { 1651 current->clear_child_tid = tidptr; 1652 1653 return task_pid_vnr(current); 1654 } 1655 1656 static void rt_mutex_init_task(struct task_struct *p) 1657 { 1658 raw_spin_lock_init(&p->pi_lock); 1659 #ifdef CONFIG_RT_MUTEXES 1660 p->pi_waiters = RB_ROOT_CACHED; 1661 p->pi_top_task = NULL; 1662 p->pi_blocked_on = NULL; 1663 #endif 1664 } 1665 1666 static inline void init_task_pid_links(struct task_struct *task) 1667 { 1668 enum pid_type type; 1669 1670 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) 1671 INIT_HLIST_NODE(&task->pid_links[type]); 1672 } 1673 1674 static inline void 1675 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) 1676 { 1677 if (type == PIDTYPE_PID) 1678 task->thread_pid = pid; 1679 else 1680 task->signal->pids[type] = pid; 1681 } 1682 1683 static inline void rcu_copy_process(struct task_struct *p) 1684 { 1685 #ifdef CONFIG_PREEMPT_RCU 1686 p->rcu_read_lock_nesting = 0; 1687 p->rcu_read_unlock_special.s = 0; 1688 p->rcu_blocked_node = NULL; 1689 INIT_LIST_HEAD(&p->rcu_node_entry); 1690 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 1691 #ifdef CONFIG_TASKS_RCU 1692 p->rcu_tasks_holdout = false; 1693 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list); 1694 p->rcu_tasks_idle_cpu = -1; 1695 #endif /* #ifdef CONFIG_TASKS_RCU */ 1696 #ifdef CONFIG_TASKS_TRACE_RCU 1697 p->trc_reader_nesting = 0; 1698 p->trc_reader_special.s = 0; 1699 INIT_LIST_HEAD(&p->trc_holdout_list); 1700 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ 1701 } 1702 1703 struct pid *pidfd_pid(const struct file *file) 1704 { 1705 if (file->f_op == &pidfd_fops) 1706 return file->private_data; 1707 1708 return ERR_PTR(-EBADF); 1709 } 1710 1711 static int pidfd_release(struct inode *inode, struct file *file) 1712 { 1713 struct pid *pid = file->private_data; 1714 1715 file->private_data = NULL; 1716 put_pid(pid); 1717 return 0; 1718 } 1719 1720 #ifdef CONFIG_PROC_FS 1721 /** 1722 * pidfd_show_fdinfo - print information about a pidfd 1723 * @m: proc fdinfo file 1724 * @f: file referencing a pidfd 1725 * 1726 * Pid: 1727 * This function will print the pid that a given pidfd refers to in the 1728 * pid namespace of the procfs instance. 1729 * If the pid namespace of the process is not a descendant of the pid 1730 * namespace of the procfs instance 0 will be shown as its pid. This is 1731 * similar to calling getppid() on a process whose parent is outside of 1732 * its pid namespace. 1733 * 1734 * NSpid: 1735 * If pid namespaces are supported then this function will also print 1736 * the pid of a given pidfd refers to for all descendant pid namespaces 1737 * starting from the current pid namespace of the instance, i.e. the 1738 * Pid field and the first entry in the NSpid field will be identical. 1739 * If the pid namespace of the process is not a descendant of the pid 1740 * namespace of the procfs instance 0 will be shown as its first NSpid 1741 * entry and no others will be shown. 1742 * Note that this differs from the Pid and NSpid fields in 1743 * /proc/<pid>/status where Pid and NSpid are always shown relative to 1744 * the pid namespace of the procfs instance. The difference becomes 1745 * obvious when sending around a pidfd between pid namespaces from a 1746 * different branch of the tree, i.e. where no ancestral relation is 1747 * present between the pid namespaces: 1748 * - create two new pid namespaces ns1 and ns2 in the initial pid 1749 * namespace (also take care to create new mount namespaces in the 1750 * new pid namespace and mount procfs) 1751 * - create a process with a pidfd in ns1 1752 * - send pidfd from ns1 to ns2 1753 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid 1754 * have exactly one entry, which is 0 1755 */ 1756 static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) 1757 { 1758 struct pid *pid = f->private_data; 1759 struct pid_namespace *ns; 1760 pid_t nr = -1; 1761 1762 if (likely(pid_has_task(pid, PIDTYPE_PID))) { 1763 ns = proc_pid_ns(file_inode(m->file)->i_sb); 1764 nr = pid_nr_ns(pid, ns); 1765 } 1766 1767 seq_put_decimal_ll(m, "Pid:\t", nr); 1768 1769 #ifdef CONFIG_PID_NS 1770 seq_put_decimal_ll(m, "\nNSpid:\t", nr); 1771 if (nr > 0) { 1772 int i; 1773 1774 /* If nr is non-zero it means that 'pid' is valid and that 1775 * ns, i.e. the pid namespace associated with the procfs 1776 * instance, is in the pid namespace hierarchy of pid. 1777 * Start at one below the already printed level. 1778 */ 1779 for (i = ns->level + 1; i <= pid->level; i++) 1780 seq_put_decimal_ll(m, "\t", pid->numbers[i].nr); 1781 } 1782 #endif 1783 seq_putc(m, '\n'); 1784 } 1785 #endif 1786 1787 /* 1788 * Poll support for process exit notification. 1789 */ 1790 static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts) 1791 { 1792 struct pid *pid = file->private_data; 1793 __poll_t poll_flags = 0; 1794 1795 poll_wait(file, &pid->wait_pidfd, pts); 1796 1797 /* 1798 * Inform pollers only when the whole thread group exits. 1799 * If the thread group leader exits before all other threads in the 1800 * group, then poll(2) should block, similar to the wait(2) family. 1801 */ 1802 if (thread_group_exited(pid)) 1803 poll_flags = EPOLLIN | EPOLLRDNORM; 1804 1805 return poll_flags; 1806 } 1807 1808 const struct file_operations pidfd_fops = { 1809 .release = pidfd_release, 1810 .poll = pidfd_poll, 1811 #ifdef CONFIG_PROC_FS 1812 .show_fdinfo = pidfd_show_fdinfo, 1813 #endif 1814 }; 1815 1816 static void __delayed_free_task(struct rcu_head *rhp) 1817 { 1818 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 1819 1820 free_task(tsk); 1821 } 1822 1823 static __always_inline void delayed_free_task(struct task_struct *tsk) 1824 { 1825 if (IS_ENABLED(CONFIG_MEMCG)) 1826 call_rcu(&tsk->rcu, __delayed_free_task); 1827 else 1828 free_task(tsk); 1829 } 1830 1831 static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk) 1832 { 1833 /* Skip if kernel thread */ 1834 if (!tsk->mm) 1835 return; 1836 1837 /* Skip if spawning a thread or using vfork */ 1838 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM) 1839 return; 1840 1841 /* We need to synchronize with __set_oom_adj */ 1842 mutex_lock(&oom_adj_mutex); 1843 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags); 1844 /* Update the values in case they were changed after copy_signal */ 1845 tsk->signal->oom_score_adj = current->signal->oom_score_adj; 1846 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min; 1847 mutex_unlock(&oom_adj_mutex); 1848 } 1849 1850 /* 1851 * This creates a new process as a copy of the old one, 1852 * but does not actually start it yet. 1853 * 1854 * It copies the registers, and all the appropriate 1855 * parts of the process environment (as per the clone 1856 * flags). The actual kick-off is left to the caller. 1857 */ 1858 static __latent_entropy struct task_struct *copy_process( 1859 struct pid *pid, 1860 int trace, 1861 int node, 1862 struct kernel_clone_args *args) 1863 { 1864 int pidfd = -1, retval; 1865 struct task_struct *p; 1866 struct multiprocess_signals delayed; 1867 struct file *pidfile = NULL; 1868 u64 clone_flags = args->flags; 1869 struct nsproxy *nsp = current->nsproxy; 1870 1871 /* 1872 * Don't allow sharing the root directory with processes in a different 1873 * namespace 1874 */ 1875 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1876 return ERR_PTR(-EINVAL); 1877 1878 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) 1879 return ERR_PTR(-EINVAL); 1880 1881 /* 1882 * Thread groups must share signals as well, and detached threads 1883 * can only be started up within the thread group. 1884 */ 1885 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1886 return ERR_PTR(-EINVAL); 1887 1888 /* 1889 * Shared signal handlers imply shared VM. By way of the above, 1890 * thread groups also imply shared VM. Blocking this case allows 1891 * for various simplifications in other code. 1892 */ 1893 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1894 return ERR_PTR(-EINVAL); 1895 1896 /* 1897 * Siblings of global init remain as zombies on exit since they are 1898 * not reaped by their parent (swapper). To solve this and to avoid 1899 * multi-rooted process trees, prevent global and container-inits 1900 * from creating siblings. 1901 */ 1902 if ((clone_flags & CLONE_PARENT) && 1903 current->signal->flags & SIGNAL_UNKILLABLE) 1904 return ERR_PTR(-EINVAL); 1905 1906 /* 1907 * If the new process will be in a different pid or user namespace 1908 * do not allow it to share a thread group with the forking task. 1909 */ 1910 if (clone_flags & CLONE_THREAD) { 1911 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || 1912 (task_active_pid_ns(current) != nsp->pid_ns_for_children)) 1913 return ERR_PTR(-EINVAL); 1914 } 1915 1916 /* 1917 * If the new process will be in a different time namespace 1918 * do not allow it to share VM or a thread group with the forking task. 1919 */ 1920 if (clone_flags & (CLONE_THREAD | CLONE_VM)) { 1921 if (nsp->time_ns != nsp->time_ns_for_children) 1922 return ERR_PTR(-EINVAL); 1923 } 1924 1925 if (clone_flags & CLONE_PIDFD) { 1926 /* 1927 * - CLONE_DETACHED is blocked so that we can potentially 1928 * reuse it later for CLONE_PIDFD. 1929 * - CLONE_THREAD is blocked until someone really needs it. 1930 */ 1931 if (clone_flags & (CLONE_DETACHED | CLONE_THREAD)) 1932 return ERR_PTR(-EINVAL); 1933 } 1934 1935 /* 1936 * Force any signals received before this point to be delivered 1937 * before the fork happens. Collect up signals sent to multiple 1938 * processes that happen during the fork and delay them so that 1939 * they appear to happen after the fork. 1940 */ 1941 sigemptyset(&delayed.signal); 1942 INIT_HLIST_NODE(&delayed.node); 1943 1944 spin_lock_irq(¤t->sighand->siglock); 1945 if (!(clone_flags & CLONE_THREAD)) 1946 hlist_add_head(&delayed.node, ¤t->signal->multiprocess); 1947 recalc_sigpending(); 1948 spin_unlock_irq(¤t->sighand->siglock); 1949 retval = -ERESTARTNOINTR; 1950 if (task_sigpending(current)) 1951 goto fork_out; 1952 1953 retval = -ENOMEM; 1954 p = dup_task_struct(current, node); 1955 if (!p) 1956 goto fork_out; 1957 if (args->io_thread) { 1958 /* 1959 * Mark us an IO worker, and block any signal that isn't 1960 * fatal or STOP 1961 */ 1962 p->flags |= PF_IO_WORKER; 1963 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)); 1964 } 1965 1966 /* 1967 * This _must_ happen before we call free_task(), i.e. before we jump 1968 * to any of the bad_fork_* labels. This is to avoid freeing 1969 * p->set_child_tid which is (ab)used as a kthread's data pointer for 1970 * kernel threads (PF_KTHREAD). 1971 */ 1972 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL; 1973 /* 1974 * Clear TID on mm_release()? 1975 */ 1976 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL; 1977 1978 ftrace_graph_init_task(p); 1979 1980 rt_mutex_init_task(p); 1981 1982 lockdep_assert_irqs_enabled(); 1983 #ifdef CONFIG_PROVE_LOCKING 1984 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1985 #endif 1986 retval = -EAGAIN; 1987 if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) { 1988 if (p->real_cred->user != INIT_USER && 1989 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) 1990 goto bad_fork_free; 1991 } 1992 current->flags &= ~PF_NPROC_EXCEEDED; 1993 1994 retval = copy_creds(p, clone_flags); 1995 if (retval < 0) 1996 goto bad_fork_free; 1997 1998 /* 1999 * If multiple threads are within copy_process(), then this check 2000 * triggers too late. This doesn't hurt, the check is only there 2001 * to stop root fork bombs. 2002 */ 2003 retval = -EAGAIN; 2004 if (data_race(nr_threads >= max_threads)) 2005 goto bad_fork_cleanup_count; 2006 2007 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 2008 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY); 2009 p->flags |= PF_FORKNOEXEC; 2010 INIT_LIST_HEAD(&p->children); 2011 INIT_LIST_HEAD(&p->sibling); 2012 rcu_copy_process(p); 2013 p->vfork_done = NULL; 2014 spin_lock_init(&p->alloc_lock); 2015 2016 init_sigpending(&p->pending); 2017 2018 p->utime = p->stime = p->gtime = 0; 2019 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME 2020 p->utimescaled = p->stimescaled = 0; 2021 #endif 2022 prev_cputime_init(&p->prev_cputime); 2023 2024 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN 2025 seqcount_init(&p->vtime.seqcount); 2026 p->vtime.starttime = 0; 2027 p->vtime.state = VTIME_INACTIVE; 2028 #endif 2029 2030 #ifdef CONFIG_IO_URING 2031 p->io_uring = NULL; 2032 #endif 2033 2034 #if defined(SPLIT_RSS_COUNTING) 2035 memset(&p->rss_stat, 0, sizeof(p->rss_stat)); 2036 #endif 2037 2038 p->default_timer_slack_ns = current->timer_slack_ns; 2039 2040 #ifdef CONFIG_PSI 2041 p->psi_flags = 0; 2042 #endif 2043 2044 task_io_accounting_init(&p->ioac); 2045 acct_clear_integrals(p); 2046 2047 posix_cputimers_init(&p->posix_cputimers); 2048 2049 p->io_context = NULL; 2050 audit_set_context(p, NULL); 2051 cgroup_fork(p); 2052 #ifdef CONFIG_NUMA 2053 p->mempolicy = mpol_dup(p->mempolicy); 2054 if (IS_ERR(p->mempolicy)) { 2055 retval = PTR_ERR(p->mempolicy); 2056 p->mempolicy = NULL; 2057 goto bad_fork_cleanup_threadgroup_lock; 2058 } 2059 #endif 2060 #ifdef CONFIG_CPUSETS 2061 p->cpuset_mem_spread_rotor = NUMA_NO_NODE; 2062 p->cpuset_slab_spread_rotor = NUMA_NO_NODE; 2063 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock); 2064 #endif 2065 #ifdef CONFIG_TRACE_IRQFLAGS 2066 memset(&p->irqtrace, 0, sizeof(p->irqtrace)); 2067 p->irqtrace.hardirq_disable_ip = _THIS_IP_; 2068 p->irqtrace.softirq_enable_ip = _THIS_IP_; 2069 p->softirqs_enabled = 1; 2070 p->softirq_context = 0; 2071 #endif 2072 2073 p->pagefault_disabled = 0; 2074 2075 #ifdef CONFIG_LOCKDEP 2076 lockdep_init_task(p); 2077 #endif 2078 2079 #ifdef CONFIG_DEBUG_MUTEXES 2080 p->blocked_on = NULL; /* not blocked yet */ 2081 #endif 2082 #ifdef CONFIG_BCACHE 2083 p->sequential_io = 0; 2084 p->sequential_io_avg = 0; 2085 #endif 2086 #ifdef CONFIG_BPF_SYSCALL 2087 RCU_INIT_POINTER(p->bpf_storage, NULL); 2088 p->bpf_ctx = NULL; 2089 #endif 2090 2091 /* Perform scheduler related setup. Assign this task to a CPU. */ 2092 retval = sched_fork(clone_flags, p); 2093 if (retval) 2094 goto bad_fork_cleanup_policy; 2095 2096 retval = perf_event_init_task(p, clone_flags); 2097 if (retval) 2098 goto bad_fork_cleanup_policy; 2099 retval = audit_alloc(p); 2100 if (retval) 2101 goto bad_fork_cleanup_perf; 2102 /* copy all the process information */ 2103 shm_init_task(p); 2104 retval = security_task_alloc(p, clone_flags); 2105 if (retval) 2106 goto bad_fork_cleanup_audit; 2107 retval = copy_semundo(clone_flags, p); 2108 if (retval) 2109 goto bad_fork_cleanup_security; 2110 retval = copy_files(clone_flags, p); 2111 if (retval) 2112 goto bad_fork_cleanup_semundo; 2113 retval = copy_fs(clone_flags, p); 2114 if (retval) 2115 goto bad_fork_cleanup_files; 2116 retval = copy_sighand(clone_flags, p); 2117 if (retval) 2118 goto bad_fork_cleanup_fs; 2119 retval = copy_signal(clone_flags, p); 2120 if (retval) 2121 goto bad_fork_cleanup_sighand; 2122 retval = copy_mm(clone_flags, p); 2123 if (retval) 2124 goto bad_fork_cleanup_signal; 2125 retval = copy_namespaces(clone_flags, p); 2126 if (retval) 2127 goto bad_fork_cleanup_mm; 2128 retval = copy_io(clone_flags, p); 2129 if (retval) 2130 goto bad_fork_cleanup_namespaces; 2131 retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls); 2132 if (retval) 2133 goto bad_fork_cleanup_io; 2134 2135 stackleak_task_init(p); 2136 2137 if (pid != &init_struct_pid) { 2138 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid, 2139 args->set_tid_size); 2140 if (IS_ERR(pid)) { 2141 retval = PTR_ERR(pid); 2142 goto bad_fork_cleanup_thread; 2143 } 2144 } 2145 2146 /* 2147 * This has to happen after we've potentially unshared the file 2148 * descriptor table (so that the pidfd doesn't leak into the child 2149 * if the fd table isn't shared). 2150 */ 2151 if (clone_flags & CLONE_PIDFD) { 2152 retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC); 2153 if (retval < 0) 2154 goto bad_fork_free_pid; 2155 2156 pidfd = retval; 2157 2158 pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, 2159 O_RDWR | O_CLOEXEC); 2160 if (IS_ERR(pidfile)) { 2161 put_unused_fd(pidfd); 2162 retval = PTR_ERR(pidfile); 2163 goto bad_fork_free_pid; 2164 } 2165 get_pid(pid); /* held by pidfile now */ 2166 2167 retval = put_user(pidfd, args->pidfd); 2168 if (retval) 2169 goto bad_fork_put_pidfd; 2170 } 2171 2172 #ifdef CONFIG_BLOCK 2173 p->plug = NULL; 2174 #endif 2175 futex_init_task(p); 2176 2177 /* 2178 * sigaltstack should be cleared when sharing the same VM 2179 */ 2180 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 2181 sas_ss_reset(p); 2182 2183 /* 2184 * Syscall tracing and stepping should be turned off in the 2185 * child regardless of CLONE_PTRACE. 2186 */ 2187 user_disable_single_step(p); 2188 clear_task_syscall_work(p, SYSCALL_TRACE); 2189 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU) 2190 clear_task_syscall_work(p, SYSCALL_EMU); 2191 #endif 2192 clear_tsk_latency_tracing(p); 2193 2194 /* ok, now we should be set up.. */ 2195 p->pid = pid_nr(pid); 2196 if (clone_flags & CLONE_THREAD) { 2197 p->group_leader = current->group_leader; 2198 p->tgid = current->tgid; 2199 } else { 2200 p->group_leader = p; 2201 p->tgid = p->pid; 2202 } 2203 2204 p->nr_dirtied = 0; 2205 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); 2206 p->dirty_paused_when = 0; 2207 2208 p->pdeath_signal = 0; 2209 INIT_LIST_HEAD(&p->thread_group); 2210 p->task_works = NULL; 2211 2212 #ifdef CONFIG_KRETPROBES 2213 p->kretprobe_instances.first = NULL; 2214 #endif 2215 2216 /* 2217 * Ensure that the cgroup subsystem policies allow the new process to be 2218 * forked. It should be noted that the new process's css_set can be changed 2219 * between here and cgroup_post_fork() if an organisation operation is in 2220 * progress. 2221 */ 2222 retval = cgroup_can_fork(p, args); 2223 if (retval) 2224 goto bad_fork_put_pidfd; 2225 2226 /* 2227 * From this point on we must avoid any synchronous user-space 2228 * communication until we take the tasklist-lock. In particular, we do 2229 * not want user-space to be able to predict the process start-time by 2230 * stalling fork(2) after we recorded the start_time but before it is 2231 * visible to the system. 2232 */ 2233 2234 p->start_time = ktime_get_ns(); 2235 p->start_boottime = ktime_get_boottime_ns(); 2236 2237 /* 2238 * Make it visible to the rest of the system, but dont wake it up yet. 2239 * Need tasklist lock for parent etc handling! 2240 */ 2241 write_lock_irq(&tasklist_lock); 2242 2243 /* CLONE_PARENT re-uses the old parent */ 2244 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { 2245 p->real_parent = current->real_parent; 2246 p->parent_exec_id = current->parent_exec_id; 2247 if (clone_flags & CLONE_THREAD) 2248 p->exit_signal = -1; 2249 else 2250 p->exit_signal = current->group_leader->exit_signal; 2251 } else { 2252 p->real_parent = current; 2253 p->parent_exec_id = current->self_exec_id; 2254 p->exit_signal = args->exit_signal; 2255 } 2256 2257 klp_copy_process(p); 2258 2259 sched_core_fork(p); 2260 2261 spin_lock(¤t->sighand->siglock); 2262 2263 /* 2264 * Copy seccomp details explicitly here, in case they were changed 2265 * before holding sighand lock. 2266 */ 2267 copy_seccomp(p); 2268 2269 rseq_fork(p, clone_flags); 2270 2271 /* Don't start children in a dying pid namespace */ 2272 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) { 2273 retval = -ENOMEM; 2274 goto bad_fork_cancel_cgroup; 2275 } 2276 2277 /* Let kill terminate clone/fork in the middle */ 2278 if (fatal_signal_pending(current)) { 2279 retval = -EINTR; 2280 goto bad_fork_cancel_cgroup; 2281 } 2282 2283 /* past the last point of failure */ 2284 if (pidfile) 2285 fd_install(pidfd, pidfile); 2286 2287 init_task_pid_links(p); 2288 if (likely(p->pid)) { 2289 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); 2290 2291 init_task_pid(p, PIDTYPE_PID, pid); 2292 if (thread_group_leader(p)) { 2293 init_task_pid(p, PIDTYPE_TGID, pid); 2294 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); 2295 init_task_pid(p, PIDTYPE_SID, task_session(current)); 2296 2297 if (is_child_reaper(pid)) { 2298 ns_of_pid(pid)->child_reaper = p; 2299 p->signal->flags |= SIGNAL_UNKILLABLE; 2300 } 2301 p->signal->shared_pending.signal = delayed.signal; 2302 p->signal->tty = tty_kref_get(current->signal->tty); 2303 /* 2304 * Inherit has_child_subreaper flag under the same 2305 * tasklist_lock with adding child to the process tree 2306 * for propagate_has_child_subreaper optimization. 2307 */ 2308 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper || 2309 p->real_parent->signal->is_child_subreaper; 2310 list_add_tail(&p->sibling, &p->real_parent->children); 2311 list_add_tail_rcu(&p->tasks, &init_task.tasks); 2312 attach_pid(p, PIDTYPE_TGID); 2313 attach_pid(p, PIDTYPE_PGID); 2314 attach_pid(p, PIDTYPE_SID); 2315 __this_cpu_inc(process_counts); 2316 } else { 2317 current->signal->nr_threads++; 2318 atomic_inc(¤t->signal->live); 2319 refcount_inc(¤t->signal->sigcnt); 2320 task_join_group_stop(p); 2321 list_add_tail_rcu(&p->thread_group, 2322 &p->group_leader->thread_group); 2323 list_add_tail_rcu(&p->thread_node, 2324 &p->signal->thread_head); 2325 } 2326 attach_pid(p, PIDTYPE_PID); 2327 nr_threads++; 2328 } 2329 total_forks++; 2330 hlist_del_init(&delayed.node); 2331 spin_unlock(¤t->sighand->siglock); 2332 syscall_tracepoint_update(p); 2333 write_unlock_irq(&tasklist_lock); 2334 2335 proc_fork_connector(p); 2336 sched_post_fork(p); 2337 cgroup_post_fork(p, args); 2338 perf_event_fork(p); 2339 2340 trace_task_newtask(p, clone_flags); 2341 uprobe_copy_process(p, clone_flags); 2342 2343 copy_oom_score_adj(clone_flags, p); 2344 2345 return p; 2346 2347 bad_fork_cancel_cgroup: 2348 sched_core_free(p); 2349 spin_unlock(¤t->sighand->siglock); 2350 write_unlock_irq(&tasklist_lock); 2351 cgroup_cancel_fork(p, args); 2352 bad_fork_put_pidfd: 2353 if (clone_flags & CLONE_PIDFD) { 2354 fput(pidfile); 2355 put_unused_fd(pidfd); 2356 } 2357 bad_fork_free_pid: 2358 if (pid != &init_struct_pid) 2359 free_pid(pid); 2360 bad_fork_cleanup_thread: 2361 exit_thread(p); 2362 bad_fork_cleanup_io: 2363 if (p->io_context) 2364 exit_io_context(p); 2365 bad_fork_cleanup_namespaces: 2366 exit_task_namespaces(p); 2367 bad_fork_cleanup_mm: 2368 if (p->mm) { 2369 mm_clear_owner(p->mm, p); 2370 mmput(p->mm); 2371 } 2372 bad_fork_cleanup_signal: 2373 if (!(clone_flags & CLONE_THREAD)) 2374 free_signal_struct(p->signal); 2375 bad_fork_cleanup_sighand: 2376 __cleanup_sighand(p->sighand); 2377 bad_fork_cleanup_fs: 2378 exit_fs(p); /* blocking */ 2379 bad_fork_cleanup_files: 2380 exit_files(p); /* blocking */ 2381 bad_fork_cleanup_semundo: 2382 exit_sem(p); 2383 bad_fork_cleanup_security: 2384 security_task_free(p); 2385 bad_fork_cleanup_audit: 2386 audit_free(p); 2387 bad_fork_cleanup_perf: 2388 perf_event_free_task(p); 2389 bad_fork_cleanup_policy: 2390 lockdep_free_task(p); 2391 #ifdef CONFIG_NUMA 2392 mpol_put(p->mempolicy); 2393 bad_fork_cleanup_threadgroup_lock: 2394 #endif 2395 delayacct_tsk_free(p); 2396 bad_fork_cleanup_count: 2397 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); 2398 exit_creds(p); 2399 bad_fork_free: 2400 WRITE_ONCE(p->__state, TASK_DEAD); 2401 put_task_stack(p); 2402 delayed_free_task(p); 2403 fork_out: 2404 spin_lock_irq(¤t->sighand->siglock); 2405 hlist_del_init(&delayed.node); 2406 spin_unlock_irq(¤t->sighand->siglock); 2407 return ERR_PTR(retval); 2408 } 2409 2410 static inline void init_idle_pids(struct task_struct *idle) 2411 { 2412 enum pid_type type; 2413 2414 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { 2415 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */ 2416 init_task_pid(idle, type, &init_struct_pid); 2417 } 2418 } 2419 2420 struct task_struct * __init fork_idle(int cpu) 2421 { 2422 struct task_struct *task; 2423 struct kernel_clone_args args = { 2424 .flags = CLONE_VM, 2425 }; 2426 2427 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args); 2428 if (!IS_ERR(task)) { 2429 init_idle_pids(task); 2430 init_idle(task, cpu); 2431 } 2432 2433 return task; 2434 } 2435 2436 struct mm_struct *copy_init_mm(void) 2437 { 2438 return dup_mm(NULL, &init_mm); 2439 } 2440 2441 /* 2442 * This is like kernel_clone(), but shaved down and tailored to just 2443 * creating io_uring workers. It returns a created task, or an error pointer. 2444 * The returned task is inactive, and the caller must fire it up through 2445 * wake_up_new_task(p). All signals are blocked in the created task. 2446 */ 2447 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node) 2448 { 2449 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD| 2450 CLONE_IO; 2451 struct kernel_clone_args args = { 2452 .flags = ((lower_32_bits(flags) | CLONE_VM | 2453 CLONE_UNTRACED) & ~CSIGNAL), 2454 .exit_signal = (lower_32_bits(flags) & CSIGNAL), 2455 .stack = (unsigned long)fn, 2456 .stack_size = (unsigned long)arg, 2457 .io_thread = 1, 2458 }; 2459 2460 return copy_process(NULL, 0, node, &args); 2461 } 2462 2463 /* 2464 * Ok, this is the main fork-routine. 2465 * 2466 * It copies the process, and if successful kick-starts 2467 * it and waits for it to finish using the VM if required. 2468 * 2469 * args->exit_signal is expected to be checked for sanity by the caller. 2470 */ 2471 pid_t kernel_clone(struct kernel_clone_args *args) 2472 { 2473 u64 clone_flags = args->flags; 2474 struct completion vfork; 2475 struct pid *pid; 2476 struct task_struct *p; 2477 int trace = 0; 2478 pid_t nr; 2479 2480 /* 2481 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument 2482 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are 2483 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate 2484 * field in struct clone_args and it still doesn't make sense to have 2485 * them both point at the same memory location. Performing this check 2486 * here has the advantage that we don't need to have a separate helper 2487 * to check for legacy clone(). 2488 */ 2489 if ((args->flags & CLONE_PIDFD) && 2490 (args->flags & CLONE_PARENT_SETTID) && 2491 (args->pidfd == args->parent_tid)) 2492 return -EINVAL; 2493 2494 /* 2495 * Determine whether and which event to report to ptracer. When 2496 * called from kernel_thread or CLONE_UNTRACED is explicitly 2497 * requested, no event is reported; otherwise, report if the event 2498 * for the type of forking is enabled. 2499 */ 2500 if (!(clone_flags & CLONE_UNTRACED)) { 2501 if (clone_flags & CLONE_VFORK) 2502 trace = PTRACE_EVENT_VFORK; 2503 else if (args->exit_signal != SIGCHLD) 2504 trace = PTRACE_EVENT_CLONE; 2505 else 2506 trace = PTRACE_EVENT_FORK; 2507 2508 if (likely(!ptrace_event_enabled(current, trace))) 2509 trace = 0; 2510 } 2511 2512 p = copy_process(NULL, trace, NUMA_NO_NODE, args); 2513 add_latent_entropy(); 2514 2515 if (IS_ERR(p)) 2516 return PTR_ERR(p); 2517 2518 /* 2519 * Do this prior waking up the new thread - the thread pointer 2520 * might get invalid after that point, if the thread exits quickly. 2521 */ 2522 trace_sched_process_fork(current, p); 2523 2524 pid = get_task_pid(p, PIDTYPE_PID); 2525 nr = pid_vnr(pid); 2526 2527 if (clone_flags & CLONE_PARENT_SETTID) 2528 put_user(nr, args->parent_tid); 2529 2530 if (clone_flags & CLONE_VFORK) { 2531 p->vfork_done = &vfork; 2532 init_completion(&vfork); 2533 get_task_struct(p); 2534 } 2535 2536 wake_up_new_task(p); 2537 2538 /* forking complete and child started to run, tell ptracer */ 2539 if (unlikely(trace)) 2540 ptrace_event_pid(trace, pid); 2541 2542 if (clone_flags & CLONE_VFORK) { 2543 if (!wait_for_vfork_done(p, &vfork)) 2544 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); 2545 } 2546 2547 put_pid(pid); 2548 return nr; 2549 } 2550 2551 /* 2552 * Create a kernel thread. 2553 */ 2554 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 2555 { 2556 struct kernel_clone_args args = { 2557 .flags = ((lower_32_bits(flags) | CLONE_VM | 2558 CLONE_UNTRACED) & ~CSIGNAL), 2559 .exit_signal = (lower_32_bits(flags) & CSIGNAL), 2560 .stack = (unsigned long)fn, 2561 .stack_size = (unsigned long)arg, 2562 }; 2563 2564 return kernel_clone(&args); 2565 } 2566 2567 #ifdef __ARCH_WANT_SYS_FORK 2568 SYSCALL_DEFINE0(fork) 2569 { 2570 #ifdef CONFIG_MMU 2571 struct kernel_clone_args args = { 2572 .exit_signal = SIGCHLD, 2573 }; 2574 2575 return kernel_clone(&args); 2576 #else 2577 /* can not support in nommu mode */ 2578 return -EINVAL; 2579 #endif 2580 } 2581 #endif 2582 2583 #ifdef __ARCH_WANT_SYS_VFORK 2584 SYSCALL_DEFINE0(vfork) 2585 { 2586 struct kernel_clone_args args = { 2587 .flags = CLONE_VFORK | CLONE_VM, 2588 .exit_signal = SIGCHLD, 2589 }; 2590 2591 return kernel_clone(&args); 2592 } 2593 #endif 2594 2595 #ifdef __ARCH_WANT_SYS_CLONE 2596 #ifdef CONFIG_CLONE_BACKWARDS 2597 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 2598 int __user *, parent_tidptr, 2599 unsigned long, tls, 2600 int __user *, child_tidptr) 2601 #elif defined(CONFIG_CLONE_BACKWARDS2) 2602 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, 2603 int __user *, parent_tidptr, 2604 int __user *, child_tidptr, 2605 unsigned long, tls) 2606 #elif defined(CONFIG_CLONE_BACKWARDS3) 2607 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, 2608 int, stack_size, 2609 int __user *, parent_tidptr, 2610 int __user *, child_tidptr, 2611 unsigned long, tls) 2612 #else 2613 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 2614 int __user *, parent_tidptr, 2615 int __user *, child_tidptr, 2616 unsigned long, tls) 2617 #endif 2618 { 2619 struct kernel_clone_args args = { 2620 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL), 2621 .pidfd = parent_tidptr, 2622 .child_tid = child_tidptr, 2623 .parent_tid = parent_tidptr, 2624 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL), 2625 .stack = newsp, 2626 .tls = tls, 2627 }; 2628 2629 return kernel_clone(&args); 2630 } 2631 #endif 2632 2633 #ifdef __ARCH_WANT_SYS_CLONE3 2634 2635 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, 2636 struct clone_args __user *uargs, 2637 size_t usize) 2638 { 2639 int err; 2640 struct clone_args args; 2641 pid_t *kset_tid = kargs->set_tid; 2642 2643 BUILD_BUG_ON(offsetofend(struct clone_args, tls) != 2644 CLONE_ARGS_SIZE_VER0); 2645 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) != 2646 CLONE_ARGS_SIZE_VER1); 2647 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) != 2648 CLONE_ARGS_SIZE_VER2); 2649 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2); 2650 2651 if (unlikely(usize > PAGE_SIZE)) 2652 return -E2BIG; 2653 if (unlikely(usize < CLONE_ARGS_SIZE_VER0)) 2654 return -EINVAL; 2655 2656 err = copy_struct_from_user(&args, sizeof(args), uargs, usize); 2657 if (err) 2658 return err; 2659 2660 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL)) 2661 return -EINVAL; 2662 2663 if (unlikely(!args.set_tid && args.set_tid_size > 0)) 2664 return -EINVAL; 2665 2666 if (unlikely(args.set_tid && args.set_tid_size == 0)) 2667 return -EINVAL; 2668 2669 /* 2670 * Verify that higher 32bits of exit_signal are unset and that 2671 * it is a valid signal 2672 */ 2673 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) || 2674 !valid_signal(args.exit_signal))) 2675 return -EINVAL; 2676 2677 if ((args.flags & CLONE_INTO_CGROUP) && 2678 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2)) 2679 return -EINVAL; 2680 2681 *kargs = (struct kernel_clone_args){ 2682 .flags = args.flags, 2683 .pidfd = u64_to_user_ptr(args.pidfd), 2684 .child_tid = u64_to_user_ptr(args.child_tid), 2685 .parent_tid = u64_to_user_ptr(args.parent_tid), 2686 .exit_signal = args.exit_signal, 2687 .stack = args.stack, 2688 .stack_size = args.stack_size, 2689 .tls = args.tls, 2690 .set_tid_size = args.set_tid_size, 2691 .cgroup = args.cgroup, 2692 }; 2693 2694 if (args.set_tid && 2695 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid), 2696 (kargs->set_tid_size * sizeof(pid_t)))) 2697 return -EFAULT; 2698 2699 kargs->set_tid = kset_tid; 2700 2701 return 0; 2702 } 2703 2704 /** 2705 * clone3_stack_valid - check and prepare stack 2706 * @kargs: kernel clone args 2707 * 2708 * Verify that the stack arguments userspace gave us are sane. 2709 * In addition, set the stack direction for userspace since it's easy for us to 2710 * determine. 2711 */ 2712 static inline bool clone3_stack_valid(struct kernel_clone_args *kargs) 2713 { 2714 if (kargs->stack == 0) { 2715 if (kargs->stack_size > 0) 2716 return false; 2717 } else { 2718 if (kargs->stack_size == 0) 2719 return false; 2720 2721 if (!access_ok((void __user *)kargs->stack, kargs->stack_size)) 2722 return false; 2723 2724 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64) 2725 kargs->stack += kargs->stack_size; 2726 #endif 2727 } 2728 2729 return true; 2730 } 2731 2732 static bool clone3_args_valid(struct kernel_clone_args *kargs) 2733 { 2734 /* Verify that no unknown flags are passed along. */ 2735 if (kargs->flags & 2736 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP)) 2737 return false; 2738 2739 /* 2740 * - make the CLONE_DETACHED bit reusable for clone3 2741 * - make the CSIGNAL bits reusable for clone3 2742 */ 2743 if (kargs->flags & (CLONE_DETACHED | CSIGNAL)) 2744 return false; 2745 2746 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) == 2747 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) 2748 return false; 2749 2750 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) && 2751 kargs->exit_signal) 2752 return false; 2753 2754 if (!clone3_stack_valid(kargs)) 2755 return false; 2756 2757 return true; 2758 } 2759 2760 /** 2761 * clone3 - create a new process with specific properties 2762 * @uargs: argument structure 2763 * @size: size of @uargs 2764 * 2765 * clone3() is the extensible successor to clone()/clone2(). 2766 * It takes a struct as argument that is versioned by its size. 2767 * 2768 * Return: On success, a positive PID for the child process. 2769 * On error, a negative errno number. 2770 */ 2771 SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size) 2772 { 2773 int err; 2774 2775 struct kernel_clone_args kargs; 2776 pid_t set_tid[MAX_PID_NS_LEVEL]; 2777 2778 kargs.set_tid = set_tid; 2779 2780 err = copy_clone_args_from_user(&kargs, uargs, size); 2781 if (err) 2782 return err; 2783 2784 if (!clone3_args_valid(&kargs)) 2785 return -EINVAL; 2786 2787 return kernel_clone(&kargs); 2788 } 2789 #endif 2790 2791 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data) 2792 { 2793 struct task_struct *leader, *parent, *child; 2794 int res; 2795 2796 read_lock(&tasklist_lock); 2797 leader = top = top->group_leader; 2798 down: 2799 for_each_thread(leader, parent) { 2800 list_for_each_entry(child, &parent->children, sibling) { 2801 res = visitor(child, data); 2802 if (res) { 2803 if (res < 0) 2804 goto out; 2805 leader = child; 2806 goto down; 2807 } 2808 up: 2809 ; 2810 } 2811 } 2812 2813 if (leader != top) { 2814 child = leader; 2815 parent = child->real_parent; 2816 leader = parent->group_leader; 2817 goto up; 2818 } 2819 out: 2820 read_unlock(&tasklist_lock); 2821 } 2822 2823 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 2824 #define ARCH_MIN_MMSTRUCT_ALIGN 0 2825 #endif 2826 2827 static void sighand_ctor(void *data) 2828 { 2829 struct sighand_struct *sighand = data; 2830 2831 spin_lock_init(&sighand->siglock); 2832 init_waitqueue_head(&sighand->signalfd_wqh); 2833 } 2834 2835 void __init proc_caches_init(void) 2836 { 2837 unsigned int mm_size; 2838 2839 sighand_cachep = kmem_cache_create("sighand_cache", 2840 sizeof(struct sighand_struct), 0, 2841 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU| 2842 SLAB_ACCOUNT, sighand_ctor); 2843 signal_cachep = kmem_cache_create("signal_cache", 2844 sizeof(struct signal_struct), 0, 2845 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2846 NULL); 2847 files_cachep = kmem_cache_create("files_cache", 2848 sizeof(struct files_struct), 0, 2849 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2850 NULL); 2851 fs_cachep = kmem_cache_create("fs_cache", 2852 sizeof(struct fs_struct), 0, 2853 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2854 NULL); 2855 2856 /* 2857 * The mm_cpumask is located at the end of mm_struct, and is 2858 * dynamically sized based on the maximum CPU number this system 2859 * can have, taking hotplug into account (nr_cpu_ids). 2860 */ 2861 mm_size = sizeof(struct mm_struct) + cpumask_size(); 2862 2863 mm_cachep = kmem_cache_create_usercopy("mm_struct", 2864 mm_size, ARCH_MIN_MMSTRUCT_ALIGN, 2865 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2866 offsetof(struct mm_struct, saved_auxv), 2867 sizeof_field(struct mm_struct, saved_auxv), 2868 NULL); 2869 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); 2870 mmap_init(); 2871 nsproxy_cache_init(); 2872 } 2873 2874 /* 2875 * Check constraints on flags passed to the unshare system call. 2876 */ 2877 static int check_unshare_flags(unsigned long unshare_flags) 2878 { 2879 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 2880 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 2881 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| 2882 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP| 2883 CLONE_NEWTIME)) 2884 return -EINVAL; 2885 /* 2886 * Not implemented, but pretend it works if there is nothing 2887 * to unshare. Note that unsharing the address space or the 2888 * signal handlers also need to unshare the signal queues (aka 2889 * CLONE_THREAD). 2890 */ 2891 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { 2892 if (!thread_group_empty(current)) 2893 return -EINVAL; 2894 } 2895 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) { 2896 if (refcount_read(¤t->sighand->count) > 1) 2897 return -EINVAL; 2898 } 2899 if (unshare_flags & CLONE_VM) { 2900 if (!current_is_single_threaded()) 2901 return -EINVAL; 2902 } 2903 2904 return 0; 2905 } 2906 2907 /* 2908 * Unshare the filesystem structure if it is being shared 2909 */ 2910 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 2911 { 2912 struct fs_struct *fs = current->fs; 2913 2914 if (!(unshare_flags & CLONE_FS) || !fs) 2915 return 0; 2916 2917 /* don't need lock here; in the worst case we'll do useless copy */ 2918 if (fs->users == 1) 2919 return 0; 2920 2921 *new_fsp = copy_fs_struct(fs); 2922 if (!*new_fsp) 2923 return -ENOMEM; 2924 2925 return 0; 2926 } 2927 2928 /* 2929 * Unshare file descriptor table if it is being shared 2930 */ 2931 int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, 2932 struct files_struct **new_fdp) 2933 { 2934 struct files_struct *fd = current->files; 2935 int error = 0; 2936 2937 if ((unshare_flags & CLONE_FILES) && 2938 (fd && atomic_read(&fd->count) > 1)) { 2939 *new_fdp = dup_fd(fd, max_fds, &error); 2940 if (!*new_fdp) 2941 return error; 2942 } 2943 2944 return 0; 2945 } 2946 2947 /* 2948 * unshare allows a process to 'unshare' part of the process 2949 * context which was originally shared using clone. copy_* 2950 * functions used by kernel_clone() cannot be used here directly 2951 * because they modify an inactive task_struct that is being 2952 * constructed. Here we are modifying the current, active, 2953 * task_struct. 2954 */ 2955 int ksys_unshare(unsigned long unshare_flags) 2956 { 2957 struct fs_struct *fs, *new_fs = NULL; 2958 struct files_struct *fd, *new_fd = NULL; 2959 struct cred *new_cred = NULL; 2960 struct nsproxy *new_nsproxy = NULL; 2961 int do_sysvsem = 0; 2962 int err; 2963 2964 /* 2965 * If unsharing a user namespace must also unshare the thread group 2966 * and unshare the filesystem root and working directories. 2967 */ 2968 if (unshare_flags & CLONE_NEWUSER) 2969 unshare_flags |= CLONE_THREAD | CLONE_FS; 2970 /* 2971 * If unsharing vm, must also unshare signal handlers. 2972 */ 2973 if (unshare_flags & CLONE_VM) 2974 unshare_flags |= CLONE_SIGHAND; 2975 /* 2976 * If unsharing a signal handlers, must also unshare the signal queues. 2977 */ 2978 if (unshare_flags & CLONE_SIGHAND) 2979 unshare_flags |= CLONE_THREAD; 2980 /* 2981 * If unsharing namespace, must also unshare filesystem information. 2982 */ 2983 if (unshare_flags & CLONE_NEWNS) 2984 unshare_flags |= CLONE_FS; 2985 2986 err = check_unshare_flags(unshare_flags); 2987 if (err) 2988 goto bad_unshare_out; 2989 /* 2990 * CLONE_NEWIPC must also detach from the undolist: after switching 2991 * to a new ipc namespace, the semaphore arrays from the old 2992 * namespace are unreachable. 2993 */ 2994 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) 2995 do_sysvsem = 1; 2996 err = unshare_fs(unshare_flags, &new_fs); 2997 if (err) 2998 goto bad_unshare_out; 2999 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd); 3000 if (err) 3001 goto bad_unshare_cleanup_fs; 3002 err = unshare_userns(unshare_flags, &new_cred); 3003 if (err) 3004 goto bad_unshare_cleanup_fd; 3005 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 3006 new_cred, new_fs); 3007 if (err) 3008 goto bad_unshare_cleanup_cred; 3009 3010 if (new_cred) { 3011 err = set_cred_ucounts(new_cred); 3012 if (err) 3013 goto bad_unshare_cleanup_cred; 3014 } 3015 3016 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { 3017 if (do_sysvsem) { 3018 /* 3019 * CLONE_SYSVSEM is equivalent to sys_exit(). 3020 */ 3021 exit_sem(current); 3022 } 3023 if (unshare_flags & CLONE_NEWIPC) { 3024 /* Orphan segments in old ns (see sem above). */ 3025 exit_shm(current); 3026 shm_init_task(current); 3027 } 3028 3029 if (new_nsproxy) 3030 switch_task_namespaces(current, new_nsproxy); 3031 3032 task_lock(current); 3033 3034 if (new_fs) { 3035 fs = current->fs; 3036 spin_lock(&fs->lock); 3037 current->fs = new_fs; 3038 if (--fs->users) 3039 new_fs = NULL; 3040 else 3041 new_fs = fs; 3042 spin_unlock(&fs->lock); 3043 } 3044 3045 if (new_fd) { 3046 fd = current->files; 3047 current->files = new_fd; 3048 new_fd = fd; 3049 } 3050 3051 task_unlock(current); 3052 3053 if (new_cred) { 3054 /* Install the new user namespace */ 3055 commit_creds(new_cred); 3056 new_cred = NULL; 3057 } 3058 } 3059 3060 perf_event_namespaces(current); 3061 3062 bad_unshare_cleanup_cred: 3063 if (new_cred) 3064 put_cred(new_cred); 3065 bad_unshare_cleanup_fd: 3066 if (new_fd) 3067 put_files_struct(new_fd); 3068 3069 bad_unshare_cleanup_fs: 3070 if (new_fs) 3071 free_fs_struct(new_fs); 3072 3073 bad_unshare_out: 3074 return err; 3075 } 3076 3077 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) 3078 { 3079 return ksys_unshare(unshare_flags); 3080 } 3081 3082 /* 3083 * Helper to unshare the files of the current task. 3084 * We don't want to expose copy_files internals to 3085 * the exec layer of the kernel. 3086 */ 3087 3088 int unshare_files(void) 3089 { 3090 struct task_struct *task = current; 3091 struct files_struct *old, *copy = NULL; 3092 int error; 3093 3094 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©); 3095 if (error || !copy) 3096 return error; 3097 3098 old = task->files; 3099 task_lock(task); 3100 task->files = copy; 3101 task_unlock(task); 3102 put_files_struct(old); 3103 return 0; 3104 } 3105 3106 int sysctl_max_threads(struct ctl_table *table, int write, 3107 void *buffer, size_t *lenp, loff_t *ppos) 3108 { 3109 struct ctl_table t; 3110 int ret; 3111 int threads = max_threads; 3112 int min = 1; 3113 int max = MAX_THREADS; 3114 3115 t = *table; 3116 t.data = &threads; 3117 t.extra1 = &min; 3118 t.extra2 = &max; 3119 3120 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 3121 if (ret || !write) 3122 return ret; 3123 3124 max_threads = threads; 3125 3126 return 0; 3127 } 3128