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