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