1 /* 2 * linux/kernel/fork.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 /* 8 * 'fork.c' contains the help-routines for the 'fork' system call 9 * (see also entry.S and others). 10 * Fork is rather simple, once you get the hang of it, but the memory 11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' 12 */ 13 14 #include <linux/slab.h> 15 #include <linux/sched/autogroup.h> 16 #include <linux/sched/mm.h> 17 #include <linux/sched/coredump.h> 18 #include <linux/sched/user.h> 19 #include <linux/sched/numa_balancing.h> 20 #include <linux/sched/stat.h> 21 #include <linux/sched/task.h> 22 #include <linux/sched/task_stack.h> 23 #include <linux/sched/cputime.h> 24 #include <linux/rtmutex.h> 25 #include <linux/init.h> 26 #include <linux/unistd.h> 27 #include <linux/module.h> 28 #include <linux/vmalloc.h> 29 #include <linux/completion.h> 30 #include <linux/personality.h> 31 #include <linux/mempolicy.h> 32 #include <linux/sem.h> 33 #include <linux/file.h> 34 #include <linux/fdtable.h> 35 #include <linux/iocontext.h> 36 #include <linux/key.h> 37 #include <linux/binfmts.h> 38 #include <linux/mman.h> 39 #include <linux/mmu_notifier.h> 40 #include <linux/hmm.h> 41 #include <linux/fs.h> 42 #include <linux/mm.h> 43 #include <linux/vmacache.h> 44 #include <linux/nsproxy.h> 45 #include <linux/capability.h> 46 #include <linux/cpu.h> 47 #include <linux/cgroup.h> 48 #include <linux/security.h> 49 #include <linux/hugetlb.h> 50 #include <linux/seccomp.h> 51 #include <linux/swap.h> 52 #include <linux/syscalls.h> 53 #include <linux/jiffies.h> 54 #include <linux/futex.h> 55 #include <linux/compat.h> 56 #include <linux/kthread.h> 57 #include <linux/task_io_accounting_ops.h> 58 #include <linux/rcupdate.h> 59 #include <linux/ptrace.h> 60 #include <linux/mount.h> 61 #include <linux/audit.h> 62 #include <linux/memcontrol.h> 63 #include <linux/ftrace.h> 64 #include <linux/proc_fs.h> 65 #include <linux/profile.h> 66 #include <linux/rmap.h> 67 #include <linux/ksm.h> 68 #include <linux/acct.h> 69 #include <linux/userfaultfd_k.h> 70 #include <linux/tsacct_kern.h> 71 #include <linux/cn_proc.h> 72 #include <linux/freezer.h> 73 #include <linux/delayacct.h> 74 #include <linux/taskstats_kern.h> 75 #include <linux/random.h> 76 #include <linux/tty.h> 77 #include <linux/blkdev.h> 78 #include <linux/fs_struct.h> 79 #include <linux/magic.h> 80 #include <linux/perf_event.h> 81 #include <linux/posix-timers.h> 82 #include <linux/user-return-notifier.h> 83 #include <linux/oom.h> 84 #include <linux/khugepaged.h> 85 #include <linux/signalfd.h> 86 #include <linux/uprobes.h> 87 #include <linux/aio.h> 88 #include <linux/compiler.h> 89 #include <linux/sysctl.h> 90 #include <linux/kcov.h> 91 #include <linux/livepatch.h> 92 #include <linux/thread_info.h> 93 94 #include <asm/pgtable.h> 95 #include <asm/pgalloc.h> 96 #include <linux/uaccess.h> 97 #include <asm/mmu_context.h> 98 #include <asm/cacheflush.h> 99 #include <asm/tlbflush.h> 100 101 #include <trace/events/sched.h> 102 103 #define CREATE_TRACE_POINTS 104 #include <trace/events/task.h> 105 106 /* 107 * Minimum number of threads to boot the kernel 108 */ 109 #define MIN_THREADS 20 110 111 /* 112 * Maximum number of threads 113 */ 114 #define MAX_THREADS FUTEX_TID_MASK 115 116 /* 117 * Protected counters by write_lock_irq(&tasklist_lock) 118 */ 119 unsigned long total_forks; /* Handle normal Linux uptimes. */ 120 int nr_threads; /* The idle threads do not count.. */ 121 122 int max_threads; /* tunable limit on nr_threads */ 123 124 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 125 126 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 127 128 #ifdef CONFIG_PROVE_RCU 129 int lockdep_tasklist_lock_is_held(void) 130 { 131 return lockdep_is_held(&tasklist_lock); 132 } 133 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); 134 #endif /* #ifdef CONFIG_PROVE_RCU */ 135 136 int nr_processes(void) 137 { 138 int cpu; 139 int total = 0; 140 141 for_each_possible_cpu(cpu) 142 total += per_cpu(process_counts, cpu); 143 144 return total; 145 } 146 147 void __weak arch_release_task_struct(struct task_struct *tsk) 148 { 149 } 150 151 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 152 static struct kmem_cache *task_struct_cachep; 153 154 static inline struct task_struct *alloc_task_struct_node(int node) 155 { 156 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); 157 } 158 159 static inline void free_task_struct(struct task_struct *tsk) 160 { 161 kmem_cache_free(task_struct_cachep, tsk); 162 } 163 #endif 164 165 void __weak arch_release_thread_stack(unsigned long *stack) 166 { 167 } 168 169 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR 170 171 /* 172 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a 173 * kmemcache based allocator. 174 */ 175 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) 176 177 #ifdef CONFIG_VMAP_STACK 178 /* 179 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB 180 * flush. Try to minimize the number of calls by caching stacks. 181 */ 182 #define NR_CACHED_STACKS 2 183 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); 184 185 static int free_vm_stack_cache(unsigned int cpu) 186 { 187 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu); 188 int i; 189 190 for (i = 0; i < NR_CACHED_STACKS; i++) { 191 struct vm_struct *vm_stack = cached_vm_stacks[i]; 192 193 if (!vm_stack) 194 continue; 195 196 vfree(vm_stack->addr); 197 cached_vm_stacks[i] = NULL; 198 } 199 200 return 0; 201 } 202 #endif 203 204 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) 205 { 206 #ifdef CONFIG_VMAP_STACK 207 void *stack; 208 int i; 209 210 for (i = 0; i < NR_CACHED_STACKS; i++) { 211 struct vm_struct *s; 212 213 s = this_cpu_xchg(cached_stacks[i], NULL); 214 215 if (!s) 216 continue; 217 218 #ifdef CONFIG_DEBUG_KMEMLEAK 219 /* Clear stale pointers from reused stack. */ 220 memset(s->addr, 0, THREAD_SIZE); 221 #endif 222 tsk->stack_vm_area = s; 223 return s->addr; 224 } 225 226 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, 227 VMALLOC_START, VMALLOC_END, 228 THREADINFO_GFP, 229 PAGE_KERNEL, 230 0, node, __builtin_return_address(0)); 231 232 /* 233 * We can't call find_vm_area() in interrupt context, and 234 * free_thread_stack() can be called in interrupt context, 235 * so cache the vm_struct. 236 */ 237 if (stack) 238 tsk->stack_vm_area = find_vm_area(stack); 239 return stack; 240 #else 241 struct page *page = alloc_pages_node(node, THREADINFO_GFP, 242 THREAD_SIZE_ORDER); 243 244 return page ? page_address(page) : NULL; 245 #endif 246 } 247 248 static inline void free_thread_stack(struct task_struct *tsk) 249 { 250 #ifdef CONFIG_VMAP_STACK 251 if (task_stack_vm_area(tsk)) { 252 int i; 253 254 for (i = 0; i < NR_CACHED_STACKS; i++) { 255 if (this_cpu_cmpxchg(cached_stacks[i], 256 NULL, tsk->stack_vm_area) != NULL) 257 continue; 258 259 return; 260 } 261 262 vfree_atomic(tsk->stack); 263 return; 264 } 265 #endif 266 267 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER); 268 } 269 # else 270 static struct kmem_cache *thread_stack_cache; 271 272 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, 273 int node) 274 { 275 return kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node); 276 } 277 278 static void free_thread_stack(struct task_struct *tsk) 279 { 280 kmem_cache_free(thread_stack_cache, tsk->stack); 281 } 282 283 void thread_stack_cache_init(void) 284 { 285 thread_stack_cache = kmem_cache_create("thread_stack", THREAD_SIZE, 286 THREAD_SIZE, 0, NULL); 287 BUG_ON(thread_stack_cache == NULL); 288 } 289 # endif 290 #endif 291 292 /* SLAB cache for signal_struct structures (tsk->signal) */ 293 static struct kmem_cache *signal_cachep; 294 295 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 296 struct kmem_cache *sighand_cachep; 297 298 /* SLAB cache for files_struct structures (tsk->files) */ 299 struct kmem_cache *files_cachep; 300 301 /* SLAB cache for fs_struct structures (tsk->fs) */ 302 struct kmem_cache *fs_cachep; 303 304 /* SLAB cache for vm_area_struct structures */ 305 struct kmem_cache *vm_area_cachep; 306 307 /* SLAB cache for mm_struct structures (tsk->mm) */ 308 static struct kmem_cache *mm_cachep; 309 310 static void account_kernel_stack(struct task_struct *tsk, int account) 311 { 312 void *stack = task_stack_page(tsk); 313 struct vm_struct *vm = task_stack_vm_area(tsk); 314 315 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0); 316 317 if (vm) { 318 int i; 319 320 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE); 321 322 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) { 323 mod_zone_page_state(page_zone(vm->pages[i]), 324 NR_KERNEL_STACK_KB, 325 PAGE_SIZE / 1024 * account); 326 } 327 328 /* All stack pages belong to the same memcg. */ 329 mod_memcg_page_state(vm->pages[0], MEMCG_KERNEL_STACK_KB, 330 account * (THREAD_SIZE / 1024)); 331 } else { 332 /* 333 * All stack pages are in the same zone and belong to the 334 * same memcg. 335 */ 336 struct page *first_page = virt_to_page(stack); 337 338 mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB, 339 THREAD_SIZE / 1024 * account); 340 341 mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB, 342 account * (THREAD_SIZE / 1024)); 343 } 344 } 345 346 static void release_task_stack(struct task_struct *tsk) 347 { 348 if (WARN_ON(tsk->state != TASK_DEAD)) 349 return; /* Better to leak the stack than to free prematurely */ 350 351 account_kernel_stack(tsk, -1); 352 arch_release_thread_stack(tsk->stack); 353 free_thread_stack(tsk); 354 tsk->stack = NULL; 355 #ifdef CONFIG_VMAP_STACK 356 tsk->stack_vm_area = NULL; 357 #endif 358 } 359 360 #ifdef CONFIG_THREAD_INFO_IN_TASK 361 void put_task_stack(struct task_struct *tsk) 362 { 363 if (atomic_dec_and_test(&tsk->stack_refcount)) 364 release_task_stack(tsk); 365 } 366 #endif 367 368 void free_task(struct task_struct *tsk) 369 { 370 #ifndef CONFIG_THREAD_INFO_IN_TASK 371 /* 372 * The task is finally done with both the stack and thread_info, 373 * so free both. 374 */ 375 release_task_stack(tsk); 376 #else 377 /* 378 * If the task had a separate stack allocation, it should be gone 379 * by now. 380 */ 381 WARN_ON_ONCE(atomic_read(&tsk->stack_refcount) != 0); 382 #endif 383 rt_mutex_debug_task_free(tsk); 384 ftrace_graph_exit_task(tsk); 385 put_seccomp_filter(tsk); 386 arch_release_task_struct(tsk); 387 if (tsk->flags & PF_KTHREAD) 388 free_kthread_struct(tsk); 389 free_task_struct(tsk); 390 } 391 EXPORT_SYMBOL(free_task); 392 393 static inline void free_signal_struct(struct signal_struct *sig) 394 { 395 taskstats_tgid_free(sig); 396 sched_autogroup_exit(sig); 397 /* 398 * __mmdrop is not safe to call from softirq context on x86 due to 399 * pgd_dtor so postpone it to the async context 400 */ 401 if (sig->oom_mm) 402 mmdrop_async(sig->oom_mm); 403 kmem_cache_free(signal_cachep, sig); 404 } 405 406 static inline void put_signal_struct(struct signal_struct *sig) 407 { 408 if (atomic_dec_and_test(&sig->sigcnt)) 409 free_signal_struct(sig); 410 } 411 412 void __put_task_struct(struct task_struct *tsk) 413 { 414 WARN_ON(!tsk->exit_state); 415 WARN_ON(atomic_read(&tsk->usage)); 416 WARN_ON(tsk == current); 417 418 cgroup_free(tsk); 419 task_numa_free(tsk); 420 security_task_free(tsk); 421 exit_creds(tsk); 422 delayacct_tsk_free(tsk); 423 put_signal_struct(tsk->signal); 424 425 if (!profile_handoff_task(tsk)) 426 free_task(tsk); 427 } 428 EXPORT_SYMBOL_GPL(__put_task_struct); 429 430 void __init __weak arch_task_cache_init(void) { } 431 432 /* 433 * set_max_threads 434 */ 435 static void set_max_threads(unsigned int max_threads_suggested) 436 { 437 u64 threads; 438 439 /* 440 * The number of threads shall be limited such that the thread 441 * structures may only consume a small part of the available memory. 442 */ 443 if (fls64(totalram_pages) + fls64(PAGE_SIZE) > 64) 444 threads = MAX_THREADS; 445 else 446 threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE, 447 (u64) THREAD_SIZE * 8UL); 448 449 if (threads > max_threads_suggested) 450 threads = max_threads_suggested; 451 452 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS); 453 } 454 455 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT 456 /* Initialized by the architecture: */ 457 int arch_task_struct_size __read_mostly; 458 #endif 459 460 void __init fork_init(void) 461 { 462 int i; 463 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 464 #ifndef ARCH_MIN_TASKALIGN 465 #define ARCH_MIN_TASKALIGN 0 466 #endif 467 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN); 468 469 /* create a slab on which task_structs can be allocated */ 470 task_struct_cachep = kmem_cache_create("task_struct", 471 arch_task_struct_size, align, 472 SLAB_PANIC|SLAB_ACCOUNT, NULL); 473 #endif 474 475 /* do the arch specific task caches init */ 476 arch_task_cache_init(); 477 478 set_max_threads(MAX_THREADS); 479 480 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 481 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 482 init_task.signal->rlim[RLIMIT_SIGPENDING] = 483 init_task.signal->rlim[RLIMIT_NPROC]; 484 485 for (i = 0; i < UCOUNT_COUNTS; i++) { 486 init_user_ns.ucount_max[i] = max_threads/2; 487 } 488 489 #ifdef CONFIG_VMAP_STACK 490 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", 491 NULL, free_vm_stack_cache); 492 #endif 493 494 lockdep_init_task(&init_task); 495 } 496 497 int __weak arch_dup_task_struct(struct task_struct *dst, 498 struct task_struct *src) 499 { 500 *dst = *src; 501 return 0; 502 } 503 504 void set_task_stack_end_magic(struct task_struct *tsk) 505 { 506 unsigned long *stackend; 507 508 stackend = end_of_stack(tsk); 509 *stackend = STACK_END_MAGIC; /* for overflow detection */ 510 } 511 512 static struct task_struct *dup_task_struct(struct task_struct *orig, int node) 513 { 514 struct task_struct *tsk; 515 unsigned long *stack; 516 struct vm_struct *stack_vm_area; 517 int err; 518 519 if (node == NUMA_NO_NODE) 520 node = tsk_fork_get_node(orig); 521 tsk = alloc_task_struct_node(node); 522 if (!tsk) 523 return NULL; 524 525 stack = alloc_thread_stack_node(tsk, node); 526 if (!stack) 527 goto free_tsk; 528 529 stack_vm_area = task_stack_vm_area(tsk); 530 531 err = arch_dup_task_struct(tsk, orig); 532 533 /* 534 * arch_dup_task_struct() clobbers the stack-related fields. Make 535 * sure they're properly initialized before using any stack-related 536 * functions again. 537 */ 538 tsk->stack = stack; 539 #ifdef CONFIG_VMAP_STACK 540 tsk->stack_vm_area = stack_vm_area; 541 #endif 542 #ifdef CONFIG_THREAD_INFO_IN_TASK 543 atomic_set(&tsk->stack_refcount, 1); 544 #endif 545 546 if (err) 547 goto free_stack; 548 549 #ifdef CONFIG_SECCOMP 550 /* 551 * We must handle setting up seccomp filters once we're under 552 * the sighand lock in case orig has changed between now and 553 * then. Until then, filter must be NULL to avoid messing up 554 * the usage counts on the error path calling free_task. 555 */ 556 tsk->seccomp.filter = NULL; 557 #endif 558 559 setup_thread_stack(tsk, orig); 560 clear_user_return_notifier(tsk); 561 clear_tsk_need_resched(tsk); 562 set_task_stack_end_magic(tsk); 563 564 #ifdef CONFIG_CC_STACKPROTECTOR 565 tsk->stack_canary = get_random_canary(); 566 #endif 567 568 /* 569 * One for us, one for whoever does the "release_task()" (usually 570 * parent) 571 */ 572 atomic_set(&tsk->usage, 2); 573 #ifdef CONFIG_BLK_DEV_IO_TRACE 574 tsk->btrace_seq = 0; 575 #endif 576 tsk->splice_pipe = NULL; 577 tsk->task_frag.page = NULL; 578 tsk->wake_q.next = NULL; 579 580 account_kernel_stack(tsk, 1); 581 582 kcov_task_init(tsk); 583 584 #ifdef CONFIG_FAULT_INJECTION 585 tsk->fail_nth = 0; 586 #endif 587 588 return tsk; 589 590 free_stack: 591 free_thread_stack(tsk); 592 free_tsk: 593 free_task_struct(tsk); 594 return NULL; 595 } 596 597 #ifdef CONFIG_MMU 598 static __latent_entropy int dup_mmap(struct mm_struct *mm, 599 struct mm_struct *oldmm) 600 { 601 struct vm_area_struct *mpnt, *tmp, *prev, **pprev; 602 struct rb_node **rb_link, *rb_parent; 603 int retval; 604 unsigned long charge; 605 LIST_HEAD(uf); 606 607 uprobe_start_dup_mmap(); 608 if (down_write_killable(&oldmm->mmap_sem)) { 609 retval = -EINTR; 610 goto fail_uprobe_end; 611 } 612 flush_cache_dup_mm(oldmm); 613 uprobe_dup_mmap(oldmm, mm); 614 /* 615 * Not linked in yet - no deadlock potential: 616 */ 617 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); 618 619 /* No ordering required: file already has been exposed. */ 620 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 621 622 mm->total_vm = oldmm->total_vm; 623 mm->data_vm = oldmm->data_vm; 624 mm->exec_vm = oldmm->exec_vm; 625 mm->stack_vm = oldmm->stack_vm; 626 627 rb_link = &mm->mm_rb.rb_node; 628 rb_parent = NULL; 629 pprev = &mm->mmap; 630 retval = ksm_fork(mm, oldmm); 631 if (retval) 632 goto out; 633 retval = khugepaged_fork(mm, oldmm); 634 if (retval) 635 goto out; 636 637 prev = NULL; 638 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 639 struct file *file; 640 641 if (mpnt->vm_flags & VM_DONTCOPY) { 642 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); 643 continue; 644 } 645 charge = 0; 646 if (mpnt->vm_flags & VM_ACCOUNT) { 647 unsigned long len = vma_pages(mpnt); 648 649 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ 650 goto fail_nomem; 651 charge = len; 652 } 653 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 654 if (!tmp) 655 goto fail_nomem; 656 *tmp = *mpnt; 657 INIT_LIST_HEAD(&tmp->anon_vma_chain); 658 retval = vma_dup_policy(mpnt, tmp); 659 if (retval) 660 goto fail_nomem_policy; 661 tmp->vm_mm = mm; 662 retval = dup_userfaultfd(tmp, &uf); 663 if (retval) 664 goto fail_nomem_anon_vma_fork; 665 if (tmp->vm_flags & VM_WIPEONFORK) { 666 /* VM_WIPEONFORK gets a clean slate in the child. */ 667 tmp->anon_vma = NULL; 668 if (anon_vma_prepare(tmp)) 669 goto fail_nomem_anon_vma_fork; 670 } else if (anon_vma_fork(tmp, mpnt)) 671 goto fail_nomem_anon_vma_fork; 672 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); 673 tmp->vm_next = tmp->vm_prev = NULL; 674 file = tmp->vm_file; 675 if (file) { 676 struct inode *inode = file_inode(file); 677 struct address_space *mapping = file->f_mapping; 678 679 get_file(file); 680 if (tmp->vm_flags & VM_DENYWRITE) 681 atomic_dec(&inode->i_writecount); 682 i_mmap_lock_write(mapping); 683 if (tmp->vm_flags & VM_SHARED) 684 atomic_inc(&mapping->i_mmap_writable); 685 flush_dcache_mmap_lock(mapping); 686 /* insert tmp into the share list, just after mpnt */ 687 vma_interval_tree_insert_after(tmp, mpnt, 688 &mapping->i_mmap); 689 flush_dcache_mmap_unlock(mapping); 690 i_mmap_unlock_write(mapping); 691 } 692 693 /* 694 * Clear hugetlb-related page reserves for children. This only 695 * affects MAP_PRIVATE mappings. Faults generated by the child 696 * are not guaranteed to succeed, even if read-only 697 */ 698 if (is_vm_hugetlb_page(tmp)) 699 reset_vma_resv_huge_pages(tmp); 700 701 /* 702 * Link in the new vma and copy the page table entries. 703 */ 704 *pprev = tmp; 705 pprev = &tmp->vm_next; 706 tmp->vm_prev = prev; 707 prev = tmp; 708 709 __vma_link_rb(mm, tmp, rb_link, rb_parent); 710 rb_link = &tmp->vm_rb.rb_right; 711 rb_parent = &tmp->vm_rb; 712 713 mm->map_count++; 714 if (!(tmp->vm_flags & VM_WIPEONFORK)) 715 retval = copy_page_range(mm, oldmm, mpnt); 716 717 if (tmp->vm_ops && tmp->vm_ops->open) 718 tmp->vm_ops->open(tmp); 719 720 if (retval) 721 goto out; 722 } 723 /* a new mm has just been created */ 724 arch_dup_mmap(oldmm, mm); 725 retval = 0; 726 out: 727 up_write(&mm->mmap_sem); 728 flush_tlb_mm(oldmm); 729 up_write(&oldmm->mmap_sem); 730 dup_userfaultfd_complete(&uf); 731 fail_uprobe_end: 732 uprobe_end_dup_mmap(); 733 return retval; 734 fail_nomem_anon_vma_fork: 735 mpol_put(vma_policy(tmp)); 736 fail_nomem_policy: 737 kmem_cache_free(vm_area_cachep, tmp); 738 fail_nomem: 739 retval = -ENOMEM; 740 vm_unacct_memory(charge); 741 goto out; 742 } 743 744 static inline int mm_alloc_pgd(struct mm_struct *mm) 745 { 746 mm->pgd = pgd_alloc(mm); 747 if (unlikely(!mm->pgd)) 748 return -ENOMEM; 749 return 0; 750 } 751 752 static inline void mm_free_pgd(struct mm_struct *mm) 753 { 754 pgd_free(mm, mm->pgd); 755 } 756 #else 757 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 758 { 759 down_write(&oldmm->mmap_sem); 760 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 761 up_write(&oldmm->mmap_sem); 762 return 0; 763 } 764 #define mm_alloc_pgd(mm) (0) 765 #define mm_free_pgd(mm) 766 #endif /* CONFIG_MMU */ 767 768 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 769 770 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 771 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 772 773 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; 774 775 static int __init coredump_filter_setup(char *s) 776 { 777 default_dump_filter = 778 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & 779 MMF_DUMP_FILTER_MASK; 780 return 1; 781 } 782 783 __setup("coredump_filter=", coredump_filter_setup); 784 785 #include <linux/init_task.h> 786 787 static void mm_init_aio(struct mm_struct *mm) 788 { 789 #ifdef CONFIG_AIO 790 spin_lock_init(&mm->ioctx_lock); 791 mm->ioctx_table = NULL; 792 #endif 793 } 794 795 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) 796 { 797 #ifdef CONFIG_MEMCG 798 mm->owner = p; 799 #endif 800 } 801 802 static void mm_init_uprobes_state(struct mm_struct *mm) 803 { 804 #ifdef CONFIG_UPROBES 805 mm->uprobes_state.xol_area = NULL; 806 #endif 807 } 808 809 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, 810 struct user_namespace *user_ns) 811 { 812 mm->mmap = NULL; 813 mm->mm_rb = RB_ROOT; 814 mm->vmacache_seqnum = 0; 815 atomic_set(&mm->mm_users, 1); 816 atomic_set(&mm->mm_count, 1); 817 init_rwsem(&mm->mmap_sem); 818 INIT_LIST_HEAD(&mm->mmlist); 819 mm->core_state = NULL; 820 mm_pgtables_bytes_init(mm); 821 mm->map_count = 0; 822 mm->locked_vm = 0; 823 mm->pinned_vm = 0; 824 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); 825 spin_lock_init(&mm->page_table_lock); 826 mm_init_cpumask(mm); 827 mm_init_aio(mm); 828 mm_init_owner(mm, p); 829 RCU_INIT_POINTER(mm->exe_file, NULL); 830 mmu_notifier_mm_init(mm); 831 hmm_mm_init(mm); 832 init_tlb_flush_pending(mm); 833 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 834 mm->pmd_huge_pte = NULL; 835 #endif 836 mm_init_uprobes_state(mm); 837 838 if (current->mm) { 839 mm->flags = current->mm->flags & MMF_INIT_MASK; 840 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; 841 } else { 842 mm->flags = default_dump_filter; 843 mm->def_flags = 0; 844 } 845 846 if (mm_alloc_pgd(mm)) 847 goto fail_nopgd; 848 849 if (init_new_context(p, mm)) 850 goto fail_nocontext; 851 852 mm->user_ns = get_user_ns(user_ns); 853 return mm; 854 855 fail_nocontext: 856 mm_free_pgd(mm); 857 fail_nopgd: 858 free_mm(mm); 859 return NULL; 860 } 861 862 static void check_mm(struct mm_struct *mm) 863 { 864 int i; 865 866 for (i = 0; i < NR_MM_COUNTERS; i++) { 867 long x = atomic_long_read(&mm->rss_stat.count[i]); 868 869 if (unlikely(x)) 870 printk(KERN_ALERT "BUG: Bad rss-counter state " 871 "mm:%p idx:%d val:%ld\n", mm, i, x); 872 } 873 874 if (mm_pgtables_bytes(mm)) 875 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n", 876 mm_pgtables_bytes(mm)); 877 878 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 879 VM_BUG_ON_MM(mm->pmd_huge_pte, mm); 880 #endif 881 } 882 883 /* 884 * Allocate and initialize an mm_struct. 885 */ 886 struct mm_struct *mm_alloc(void) 887 { 888 struct mm_struct *mm; 889 890 mm = allocate_mm(); 891 if (!mm) 892 return NULL; 893 894 memset(mm, 0, sizeof(*mm)); 895 return mm_init(mm, current, current_user_ns()); 896 } 897 898 /* 899 * Called when the last reference to the mm 900 * is dropped: either by a lazy thread or by 901 * mmput. Free the page directory and the mm. 902 */ 903 void __mmdrop(struct mm_struct *mm) 904 { 905 BUG_ON(mm == &init_mm); 906 mm_free_pgd(mm); 907 destroy_context(mm); 908 hmm_mm_destroy(mm); 909 mmu_notifier_mm_destroy(mm); 910 check_mm(mm); 911 put_user_ns(mm->user_ns); 912 free_mm(mm); 913 } 914 EXPORT_SYMBOL_GPL(__mmdrop); 915 916 static inline void __mmput(struct mm_struct *mm) 917 { 918 VM_BUG_ON(atomic_read(&mm->mm_users)); 919 920 uprobe_clear_state(mm); 921 exit_aio(mm); 922 ksm_exit(mm); 923 khugepaged_exit(mm); /* must run before exit_mmap */ 924 exit_mmap(mm); 925 mm_put_huge_zero_page(mm); 926 set_mm_exe_file(mm, NULL); 927 if (!list_empty(&mm->mmlist)) { 928 spin_lock(&mmlist_lock); 929 list_del(&mm->mmlist); 930 spin_unlock(&mmlist_lock); 931 } 932 if (mm->binfmt) 933 module_put(mm->binfmt->module); 934 mmdrop(mm); 935 } 936 937 /* 938 * Decrement the use count and release all resources for an mm. 939 */ 940 void mmput(struct mm_struct *mm) 941 { 942 might_sleep(); 943 944 if (atomic_dec_and_test(&mm->mm_users)) 945 __mmput(mm); 946 } 947 EXPORT_SYMBOL_GPL(mmput); 948 949 #ifdef CONFIG_MMU 950 static void mmput_async_fn(struct work_struct *work) 951 { 952 struct mm_struct *mm = container_of(work, struct mm_struct, 953 async_put_work); 954 955 __mmput(mm); 956 } 957 958 void mmput_async(struct mm_struct *mm) 959 { 960 if (atomic_dec_and_test(&mm->mm_users)) { 961 INIT_WORK(&mm->async_put_work, mmput_async_fn); 962 schedule_work(&mm->async_put_work); 963 } 964 } 965 #endif 966 967 /** 968 * set_mm_exe_file - change a reference to the mm's executable file 969 * 970 * This changes mm's executable file (shown as symlink /proc/[pid]/exe). 971 * 972 * Main users are mmput() and sys_execve(). Callers prevent concurrent 973 * invocations: in mmput() nobody alive left, in execve task is single 974 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the 975 * mm->exe_file, but does so without using set_mm_exe_file() in order 976 * to do avoid the need for any locks. 977 */ 978 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) 979 { 980 struct file *old_exe_file; 981 982 /* 983 * It is safe to dereference the exe_file without RCU as 984 * this function is only called if nobody else can access 985 * this mm -- see comment above for justification. 986 */ 987 old_exe_file = rcu_dereference_raw(mm->exe_file); 988 989 if (new_exe_file) 990 get_file(new_exe_file); 991 rcu_assign_pointer(mm->exe_file, new_exe_file); 992 if (old_exe_file) 993 fput(old_exe_file); 994 } 995 996 /** 997 * get_mm_exe_file - acquire a reference to the mm's executable file 998 * 999 * Returns %NULL if mm has no associated executable file. 1000 * User must release file via fput(). 1001 */ 1002 struct file *get_mm_exe_file(struct mm_struct *mm) 1003 { 1004 struct file *exe_file; 1005 1006 rcu_read_lock(); 1007 exe_file = rcu_dereference(mm->exe_file); 1008 if (exe_file && !get_file_rcu(exe_file)) 1009 exe_file = NULL; 1010 rcu_read_unlock(); 1011 return exe_file; 1012 } 1013 EXPORT_SYMBOL(get_mm_exe_file); 1014 1015 /** 1016 * get_task_exe_file - acquire a reference to the task's executable file 1017 * 1018 * Returns %NULL if task's mm (if any) has no associated executable file or 1019 * this is a kernel thread with borrowed mm (see the comment above get_task_mm). 1020 * User must release file via fput(). 1021 */ 1022 struct file *get_task_exe_file(struct task_struct *task) 1023 { 1024 struct file *exe_file = NULL; 1025 struct mm_struct *mm; 1026 1027 task_lock(task); 1028 mm = task->mm; 1029 if (mm) { 1030 if (!(task->flags & PF_KTHREAD)) 1031 exe_file = get_mm_exe_file(mm); 1032 } 1033 task_unlock(task); 1034 return exe_file; 1035 } 1036 EXPORT_SYMBOL(get_task_exe_file); 1037 1038 /** 1039 * get_task_mm - acquire a reference to the task's mm 1040 * 1041 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning 1042 * this kernel workthread has transiently adopted a user mm with use_mm, 1043 * to do its AIO) is not set and if so returns a reference to it, after 1044 * bumping up the use count. User must release the mm via mmput() 1045 * after use. Typically used by /proc and ptrace. 1046 */ 1047 struct mm_struct *get_task_mm(struct task_struct *task) 1048 { 1049 struct mm_struct *mm; 1050 1051 task_lock(task); 1052 mm = task->mm; 1053 if (mm) { 1054 if (task->flags & PF_KTHREAD) 1055 mm = NULL; 1056 else 1057 mmget(mm); 1058 } 1059 task_unlock(task); 1060 return mm; 1061 } 1062 EXPORT_SYMBOL_GPL(get_task_mm); 1063 1064 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) 1065 { 1066 struct mm_struct *mm; 1067 int err; 1068 1069 err = mutex_lock_killable(&task->signal->cred_guard_mutex); 1070 if (err) 1071 return ERR_PTR(err); 1072 1073 mm = get_task_mm(task); 1074 if (mm && mm != current->mm && 1075 !ptrace_may_access(task, mode)) { 1076 mmput(mm); 1077 mm = ERR_PTR(-EACCES); 1078 } 1079 mutex_unlock(&task->signal->cred_guard_mutex); 1080 1081 return mm; 1082 } 1083 1084 static void complete_vfork_done(struct task_struct *tsk) 1085 { 1086 struct completion *vfork; 1087 1088 task_lock(tsk); 1089 vfork = tsk->vfork_done; 1090 if (likely(vfork)) { 1091 tsk->vfork_done = NULL; 1092 complete(vfork); 1093 } 1094 task_unlock(tsk); 1095 } 1096 1097 static int wait_for_vfork_done(struct task_struct *child, 1098 struct completion *vfork) 1099 { 1100 int killed; 1101 1102 freezer_do_not_count(); 1103 killed = wait_for_completion_killable(vfork); 1104 freezer_count(); 1105 1106 if (killed) { 1107 task_lock(child); 1108 child->vfork_done = NULL; 1109 task_unlock(child); 1110 } 1111 1112 put_task_struct(child); 1113 return killed; 1114 } 1115 1116 /* Please note the differences between mmput and mm_release. 1117 * mmput is called whenever we stop holding onto a mm_struct, 1118 * error success whatever. 1119 * 1120 * mm_release is called after a mm_struct has been removed 1121 * from the current process. 1122 * 1123 * This difference is important for error handling, when we 1124 * only half set up a mm_struct for a new process and need to restore 1125 * the old one. Because we mmput the new mm_struct before 1126 * restoring the old one. . . 1127 * Eric Biederman 10 January 1998 1128 */ 1129 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 1130 { 1131 /* Get rid of any futexes when releasing the mm */ 1132 #ifdef CONFIG_FUTEX 1133 if (unlikely(tsk->robust_list)) { 1134 exit_robust_list(tsk); 1135 tsk->robust_list = NULL; 1136 } 1137 #ifdef CONFIG_COMPAT 1138 if (unlikely(tsk->compat_robust_list)) { 1139 compat_exit_robust_list(tsk); 1140 tsk->compat_robust_list = NULL; 1141 } 1142 #endif 1143 if (unlikely(!list_empty(&tsk->pi_state_list))) 1144 exit_pi_state_list(tsk); 1145 #endif 1146 1147 uprobe_free_utask(tsk); 1148 1149 /* Get rid of any cached register state */ 1150 deactivate_mm(tsk, mm); 1151 1152 /* 1153 * Signal userspace if we're not exiting with a core dump 1154 * because we want to leave the value intact for debugging 1155 * purposes. 1156 */ 1157 if (tsk->clear_child_tid) { 1158 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) && 1159 atomic_read(&mm->mm_users) > 1) { 1160 /* 1161 * We don't check the error code - if userspace has 1162 * not set up a proper pointer then tough luck. 1163 */ 1164 put_user(0, tsk->clear_child_tid); 1165 sys_futex(tsk->clear_child_tid, FUTEX_WAKE, 1166 1, NULL, NULL, 0); 1167 } 1168 tsk->clear_child_tid = NULL; 1169 } 1170 1171 /* 1172 * All done, finally we can wake up parent and return this mm to him. 1173 * Also kthread_stop() uses this completion for synchronization. 1174 */ 1175 if (tsk->vfork_done) 1176 complete_vfork_done(tsk); 1177 } 1178 1179 /* 1180 * Allocate a new mm structure and copy contents from the 1181 * mm structure of the passed in task structure. 1182 */ 1183 static struct mm_struct *dup_mm(struct task_struct *tsk) 1184 { 1185 struct mm_struct *mm, *oldmm = current->mm; 1186 int err; 1187 1188 mm = allocate_mm(); 1189 if (!mm) 1190 goto fail_nomem; 1191 1192 memcpy(mm, oldmm, sizeof(*mm)); 1193 1194 if (!mm_init(mm, tsk, mm->user_ns)) 1195 goto fail_nomem; 1196 1197 err = dup_mmap(mm, oldmm); 1198 if (err) 1199 goto free_pt; 1200 1201 mm->hiwater_rss = get_mm_rss(mm); 1202 mm->hiwater_vm = mm->total_vm; 1203 1204 if (mm->binfmt && !try_module_get(mm->binfmt->module)) 1205 goto free_pt; 1206 1207 return mm; 1208 1209 free_pt: 1210 /* don't put binfmt in mmput, we haven't got module yet */ 1211 mm->binfmt = NULL; 1212 mmput(mm); 1213 1214 fail_nomem: 1215 return NULL; 1216 } 1217 1218 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) 1219 { 1220 struct mm_struct *mm, *oldmm; 1221 int retval; 1222 1223 tsk->min_flt = tsk->maj_flt = 0; 1224 tsk->nvcsw = tsk->nivcsw = 0; 1225 #ifdef CONFIG_DETECT_HUNG_TASK 1226 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; 1227 #endif 1228 1229 tsk->mm = NULL; 1230 tsk->active_mm = NULL; 1231 1232 /* 1233 * Are we cloning a kernel thread? 1234 * 1235 * We need to steal a active VM for that.. 1236 */ 1237 oldmm = current->mm; 1238 if (!oldmm) 1239 return 0; 1240 1241 /* initialize the new vmacache entries */ 1242 vmacache_flush(tsk); 1243 1244 if (clone_flags & CLONE_VM) { 1245 mmget(oldmm); 1246 mm = oldmm; 1247 goto good_mm; 1248 } 1249 1250 retval = -ENOMEM; 1251 mm = dup_mm(tsk); 1252 if (!mm) 1253 goto fail_nomem; 1254 1255 good_mm: 1256 tsk->mm = mm; 1257 tsk->active_mm = mm; 1258 return 0; 1259 1260 fail_nomem: 1261 return retval; 1262 } 1263 1264 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 1265 { 1266 struct fs_struct *fs = current->fs; 1267 if (clone_flags & CLONE_FS) { 1268 /* tsk->fs is already what we want */ 1269 spin_lock(&fs->lock); 1270 if (fs->in_exec) { 1271 spin_unlock(&fs->lock); 1272 return -EAGAIN; 1273 } 1274 fs->users++; 1275 spin_unlock(&fs->lock); 1276 return 0; 1277 } 1278 tsk->fs = copy_fs_struct(fs); 1279 if (!tsk->fs) 1280 return -ENOMEM; 1281 return 0; 1282 } 1283 1284 static int copy_files(unsigned long clone_flags, struct task_struct *tsk) 1285 { 1286 struct files_struct *oldf, *newf; 1287 int error = 0; 1288 1289 /* 1290 * A background process may not have any files ... 1291 */ 1292 oldf = current->files; 1293 if (!oldf) 1294 goto out; 1295 1296 if (clone_flags & CLONE_FILES) { 1297 atomic_inc(&oldf->count); 1298 goto out; 1299 } 1300 1301 newf = dup_fd(oldf, &error); 1302 if (!newf) 1303 goto out; 1304 1305 tsk->files = newf; 1306 error = 0; 1307 out: 1308 return error; 1309 } 1310 1311 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 1312 { 1313 #ifdef CONFIG_BLOCK 1314 struct io_context *ioc = current->io_context; 1315 struct io_context *new_ioc; 1316 1317 if (!ioc) 1318 return 0; 1319 /* 1320 * Share io context with parent, if CLONE_IO is set 1321 */ 1322 if (clone_flags & CLONE_IO) { 1323 ioc_task_link(ioc); 1324 tsk->io_context = ioc; 1325 } else if (ioprio_valid(ioc->ioprio)) { 1326 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); 1327 if (unlikely(!new_ioc)) 1328 return -ENOMEM; 1329 1330 new_ioc->ioprio = ioc->ioprio; 1331 put_io_context(new_ioc); 1332 } 1333 #endif 1334 return 0; 1335 } 1336 1337 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 1338 { 1339 struct sighand_struct *sig; 1340 1341 if (clone_flags & CLONE_SIGHAND) { 1342 atomic_inc(¤t->sighand->count); 1343 return 0; 1344 } 1345 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 1346 rcu_assign_pointer(tsk->sighand, sig); 1347 if (!sig) 1348 return -ENOMEM; 1349 1350 atomic_set(&sig->count, 1); 1351 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 1352 return 0; 1353 } 1354 1355 void __cleanup_sighand(struct sighand_struct *sighand) 1356 { 1357 if (atomic_dec_and_test(&sighand->count)) { 1358 signalfd_cleanup(sighand); 1359 /* 1360 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it 1361 * without an RCU grace period, see __lock_task_sighand(). 1362 */ 1363 kmem_cache_free(sighand_cachep, sighand); 1364 } 1365 } 1366 1367 #ifdef CONFIG_POSIX_TIMERS 1368 /* 1369 * Initialize POSIX timer handling for a thread group. 1370 */ 1371 static void posix_cpu_timers_init_group(struct signal_struct *sig) 1372 { 1373 unsigned long cpu_limit; 1374 1375 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); 1376 if (cpu_limit != RLIM_INFINITY) { 1377 sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC; 1378 sig->cputimer.running = true; 1379 } 1380 1381 /* The timer lists. */ 1382 INIT_LIST_HEAD(&sig->cpu_timers[0]); 1383 INIT_LIST_HEAD(&sig->cpu_timers[1]); 1384 INIT_LIST_HEAD(&sig->cpu_timers[2]); 1385 } 1386 #else 1387 static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { } 1388 #endif 1389 1390 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 1391 { 1392 struct signal_struct *sig; 1393 1394 if (clone_flags & CLONE_THREAD) 1395 return 0; 1396 1397 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); 1398 tsk->signal = sig; 1399 if (!sig) 1400 return -ENOMEM; 1401 1402 sig->nr_threads = 1; 1403 atomic_set(&sig->live, 1); 1404 atomic_set(&sig->sigcnt, 1); 1405 1406 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ 1407 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); 1408 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); 1409 1410 init_waitqueue_head(&sig->wait_chldexit); 1411 sig->curr_target = tsk; 1412 init_sigpending(&sig->shared_pending); 1413 seqlock_init(&sig->stats_lock); 1414 prev_cputime_init(&sig->prev_cputime); 1415 1416 #ifdef CONFIG_POSIX_TIMERS 1417 INIT_LIST_HEAD(&sig->posix_timers); 1418 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 1419 sig->real_timer.function = it_real_fn; 1420 #endif 1421 1422 task_lock(current->group_leader); 1423 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 1424 task_unlock(current->group_leader); 1425 1426 posix_cpu_timers_init_group(sig); 1427 1428 tty_audit_fork(sig); 1429 sched_autogroup_fork(sig); 1430 1431 sig->oom_score_adj = current->signal->oom_score_adj; 1432 sig->oom_score_adj_min = current->signal->oom_score_adj_min; 1433 1434 mutex_init(&sig->cred_guard_mutex); 1435 1436 return 0; 1437 } 1438 1439 static void copy_seccomp(struct task_struct *p) 1440 { 1441 #ifdef CONFIG_SECCOMP 1442 /* 1443 * Must be called with sighand->lock held, which is common to 1444 * all threads in the group. Holding cred_guard_mutex is not 1445 * needed because this new task is not yet running and cannot 1446 * be racing exec. 1447 */ 1448 assert_spin_locked(¤t->sighand->siglock); 1449 1450 /* Ref-count the new filter user, and assign it. */ 1451 get_seccomp_filter(current); 1452 p->seccomp = current->seccomp; 1453 1454 /* 1455 * Explicitly enable no_new_privs here in case it got set 1456 * between the task_struct being duplicated and holding the 1457 * sighand lock. The seccomp state and nnp must be in sync. 1458 */ 1459 if (task_no_new_privs(current)) 1460 task_set_no_new_privs(p); 1461 1462 /* 1463 * If the parent gained a seccomp mode after copying thread 1464 * flags and between before we held the sighand lock, we have 1465 * to manually enable the seccomp thread flag here. 1466 */ 1467 if (p->seccomp.mode != SECCOMP_MODE_DISABLED) 1468 set_tsk_thread_flag(p, TIF_SECCOMP); 1469 #endif 1470 } 1471 1472 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) 1473 { 1474 current->clear_child_tid = tidptr; 1475 1476 return task_pid_vnr(current); 1477 } 1478 1479 static void rt_mutex_init_task(struct task_struct *p) 1480 { 1481 raw_spin_lock_init(&p->pi_lock); 1482 #ifdef CONFIG_RT_MUTEXES 1483 p->pi_waiters = RB_ROOT_CACHED; 1484 p->pi_top_task = NULL; 1485 p->pi_blocked_on = NULL; 1486 #endif 1487 } 1488 1489 #ifdef CONFIG_POSIX_TIMERS 1490 /* 1491 * Initialize POSIX timer handling for a single task. 1492 */ 1493 static void posix_cpu_timers_init(struct task_struct *tsk) 1494 { 1495 tsk->cputime_expires.prof_exp = 0; 1496 tsk->cputime_expires.virt_exp = 0; 1497 tsk->cputime_expires.sched_exp = 0; 1498 INIT_LIST_HEAD(&tsk->cpu_timers[0]); 1499 INIT_LIST_HEAD(&tsk->cpu_timers[1]); 1500 INIT_LIST_HEAD(&tsk->cpu_timers[2]); 1501 } 1502 #else 1503 static inline void posix_cpu_timers_init(struct task_struct *tsk) { } 1504 #endif 1505 1506 static inline void 1507 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) 1508 { 1509 task->pids[type].pid = pid; 1510 } 1511 1512 static inline void rcu_copy_process(struct task_struct *p) 1513 { 1514 #ifdef CONFIG_PREEMPT_RCU 1515 p->rcu_read_lock_nesting = 0; 1516 p->rcu_read_unlock_special.s = 0; 1517 p->rcu_blocked_node = NULL; 1518 INIT_LIST_HEAD(&p->rcu_node_entry); 1519 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 1520 #ifdef CONFIG_TASKS_RCU 1521 p->rcu_tasks_holdout = false; 1522 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list); 1523 p->rcu_tasks_idle_cpu = -1; 1524 #endif /* #ifdef CONFIG_TASKS_RCU */ 1525 } 1526 1527 /* 1528 * This creates a new process as a copy of the old one, 1529 * but does not actually start it yet. 1530 * 1531 * It copies the registers, and all the appropriate 1532 * parts of the process environment (as per the clone 1533 * flags). The actual kick-off is left to the caller. 1534 */ 1535 static __latent_entropy struct task_struct *copy_process( 1536 unsigned long clone_flags, 1537 unsigned long stack_start, 1538 unsigned long stack_size, 1539 int __user *child_tidptr, 1540 struct pid *pid, 1541 int trace, 1542 unsigned long tls, 1543 int node) 1544 { 1545 int retval; 1546 struct task_struct *p; 1547 1548 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1549 return ERR_PTR(-EINVAL); 1550 1551 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) 1552 return ERR_PTR(-EINVAL); 1553 1554 /* 1555 * Thread groups must share signals as well, and detached threads 1556 * can only be started up within the thread group. 1557 */ 1558 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1559 return ERR_PTR(-EINVAL); 1560 1561 /* 1562 * Shared signal handlers imply shared VM. By way of the above, 1563 * thread groups also imply shared VM. Blocking this case allows 1564 * for various simplifications in other code. 1565 */ 1566 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1567 return ERR_PTR(-EINVAL); 1568 1569 /* 1570 * Siblings of global init remain as zombies on exit since they are 1571 * not reaped by their parent (swapper). To solve this and to avoid 1572 * multi-rooted process trees, prevent global and container-inits 1573 * from creating siblings. 1574 */ 1575 if ((clone_flags & CLONE_PARENT) && 1576 current->signal->flags & SIGNAL_UNKILLABLE) 1577 return ERR_PTR(-EINVAL); 1578 1579 /* 1580 * If the new process will be in a different pid or user namespace 1581 * do not allow it to share a thread group with the forking task. 1582 */ 1583 if (clone_flags & CLONE_THREAD) { 1584 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || 1585 (task_active_pid_ns(current) != 1586 current->nsproxy->pid_ns_for_children)) 1587 return ERR_PTR(-EINVAL); 1588 } 1589 1590 retval = -ENOMEM; 1591 p = dup_task_struct(current, node); 1592 if (!p) 1593 goto fork_out; 1594 1595 /* 1596 * This _must_ happen before we call free_task(), i.e. before we jump 1597 * to any of the bad_fork_* labels. This is to avoid freeing 1598 * p->set_child_tid which is (ab)used as a kthread's data pointer for 1599 * kernel threads (PF_KTHREAD). 1600 */ 1601 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1602 /* 1603 * Clear TID on mm_release()? 1604 */ 1605 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; 1606 1607 ftrace_graph_init_task(p); 1608 1609 rt_mutex_init_task(p); 1610 1611 #ifdef CONFIG_PROVE_LOCKING 1612 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 1613 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1614 #endif 1615 retval = -EAGAIN; 1616 if (atomic_read(&p->real_cred->user->processes) >= 1617 task_rlimit(p, RLIMIT_NPROC)) { 1618 if (p->real_cred->user != INIT_USER && 1619 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) 1620 goto bad_fork_free; 1621 } 1622 current->flags &= ~PF_NPROC_EXCEEDED; 1623 1624 retval = copy_creds(p, clone_flags); 1625 if (retval < 0) 1626 goto bad_fork_free; 1627 1628 /* 1629 * If multiple threads are within copy_process(), then this check 1630 * triggers too late. This doesn't hurt, the check is only there 1631 * to stop root fork bombs. 1632 */ 1633 retval = -EAGAIN; 1634 if (nr_threads >= max_threads) 1635 goto bad_fork_cleanup_count; 1636 1637 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1638 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE); 1639 p->flags |= PF_FORKNOEXEC; 1640 INIT_LIST_HEAD(&p->children); 1641 INIT_LIST_HEAD(&p->sibling); 1642 rcu_copy_process(p); 1643 p->vfork_done = NULL; 1644 spin_lock_init(&p->alloc_lock); 1645 1646 init_sigpending(&p->pending); 1647 1648 p->utime = p->stime = p->gtime = 0; 1649 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME 1650 p->utimescaled = p->stimescaled = 0; 1651 #endif 1652 prev_cputime_init(&p->prev_cputime); 1653 1654 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN 1655 seqcount_init(&p->vtime.seqcount); 1656 p->vtime.starttime = 0; 1657 p->vtime.state = VTIME_INACTIVE; 1658 #endif 1659 1660 #if defined(SPLIT_RSS_COUNTING) 1661 memset(&p->rss_stat, 0, sizeof(p->rss_stat)); 1662 #endif 1663 1664 p->default_timer_slack_ns = current->timer_slack_ns; 1665 1666 task_io_accounting_init(&p->ioac); 1667 acct_clear_integrals(p); 1668 1669 posix_cpu_timers_init(p); 1670 1671 p->start_time = ktime_get_ns(); 1672 p->real_start_time = ktime_get_boot_ns(); 1673 p->io_context = NULL; 1674 p->audit_context = NULL; 1675 cgroup_fork(p); 1676 #ifdef CONFIG_NUMA 1677 p->mempolicy = mpol_dup(p->mempolicy); 1678 if (IS_ERR(p->mempolicy)) { 1679 retval = PTR_ERR(p->mempolicy); 1680 p->mempolicy = NULL; 1681 goto bad_fork_cleanup_threadgroup_lock; 1682 } 1683 #endif 1684 #ifdef CONFIG_CPUSETS 1685 p->cpuset_mem_spread_rotor = NUMA_NO_NODE; 1686 p->cpuset_slab_spread_rotor = NUMA_NO_NODE; 1687 seqcount_init(&p->mems_allowed_seq); 1688 #endif 1689 #ifdef CONFIG_TRACE_IRQFLAGS 1690 p->irq_events = 0; 1691 p->hardirqs_enabled = 0; 1692 p->hardirq_enable_ip = 0; 1693 p->hardirq_enable_event = 0; 1694 p->hardirq_disable_ip = _THIS_IP_; 1695 p->hardirq_disable_event = 0; 1696 p->softirqs_enabled = 1; 1697 p->softirq_enable_ip = _THIS_IP_; 1698 p->softirq_enable_event = 0; 1699 p->softirq_disable_ip = 0; 1700 p->softirq_disable_event = 0; 1701 p->hardirq_context = 0; 1702 p->softirq_context = 0; 1703 #endif 1704 1705 p->pagefault_disabled = 0; 1706 1707 #ifdef CONFIG_LOCKDEP 1708 p->lockdep_depth = 0; /* no locks held yet */ 1709 p->curr_chain_key = 0; 1710 p->lockdep_recursion = 0; 1711 lockdep_init_task(p); 1712 #endif 1713 1714 #ifdef CONFIG_DEBUG_MUTEXES 1715 p->blocked_on = NULL; /* not blocked yet */ 1716 #endif 1717 #ifdef CONFIG_BCACHE 1718 p->sequential_io = 0; 1719 p->sequential_io_avg = 0; 1720 #endif 1721 1722 /* Perform scheduler related setup. Assign this task to a CPU. */ 1723 retval = sched_fork(clone_flags, p); 1724 if (retval) 1725 goto bad_fork_cleanup_policy; 1726 1727 retval = perf_event_init_task(p); 1728 if (retval) 1729 goto bad_fork_cleanup_policy; 1730 retval = audit_alloc(p); 1731 if (retval) 1732 goto bad_fork_cleanup_perf; 1733 /* copy all the process information */ 1734 shm_init_task(p); 1735 retval = security_task_alloc(p, clone_flags); 1736 if (retval) 1737 goto bad_fork_cleanup_audit; 1738 retval = copy_semundo(clone_flags, p); 1739 if (retval) 1740 goto bad_fork_cleanup_security; 1741 retval = copy_files(clone_flags, p); 1742 if (retval) 1743 goto bad_fork_cleanup_semundo; 1744 retval = copy_fs(clone_flags, p); 1745 if (retval) 1746 goto bad_fork_cleanup_files; 1747 retval = copy_sighand(clone_flags, p); 1748 if (retval) 1749 goto bad_fork_cleanup_fs; 1750 retval = copy_signal(clone_flags, p); 1751 if (retval) 1752 goto bad_fork_cleanup_sighand; 1753 retval = copy_mm(clone_flags, p); 1754 if (retval) 1755 goto bad_fork_cleanup_signal; 1756 retval = copy_namespaces(clone_flags, p); 1757 if (retval) 1758 goto bad_fork_cleanup_mm; 1759 retval = copy_io(clone_flags, p); 1760 if (retval) 1761 goto bad_fork_cleanup_namespaces; 1762 retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls); 1763 if (retval) 1764 goto bad_fork_cleanup_io; 1765 1766 if (pid != &init_struct_pid) { 1767 pid = alloc_pid(p->nsproxy->pid_ns_for_children); 1768 if (IS_ERR(pid)) { 1769 retval = PTR_ERR(pid); 1770 goto bad_fork_cleanup_thread; 1771 } 1772 } 1773 1774 #ifdef CONFIG_BLOCK 1775 p->plug = NULL; 1776 #endif 1777 #ifdef CONFIG_FUTEX 1778 p->robust_list = NULL; 1779 #ifdef CONFIG_COMPAT 1780 p->compat_robust_list = NULL; 1781 #endif 1782 INIT_LIST_HEAD(&p->pi_state_list); 1783 p->pi_state_cache = NULL; 1784 #endif 1785 /* 1786 * sigaltstack should be cleared when sharing the same VM 1787 */ 1788 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1789 sas_ss_reset(p); 1790 1791 /* 1792 * Syscall tracing and stepping should be turned off in the 1793 * child regardless of CLONE_PTRACE. 1794 */ 1795 user_disable_single_step(p); 1796 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1797 #ifdef TIF_SYSCALL_EMU 1798 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1799 #endif 1800 clear_all_latency_tracing(p); 1801 1802 /* ok, now we should be set up.. */ 1803 p->pid = pid_nr(pid); 1804 if (clone_flags & CLONE_THREAD) { 1805 p->exit_signal = -1; 1806 p->group_leader = current->group_leader; 1807 p->tgid = current->tgid; 1808 } else { 1809 if (clone_flags & CLONE_PARENT) 1810 p->exit_signal = current->group_leader->exit_signal; 1811 else 1812 p->exit_signal = (clone_flags & CSIGNAL); 1813 p->group_leader = p; 1814 p->tgid = p->pid; 1815 } 1816 1817 p->nr_dirtied = 0; 1818 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); 1819 p->dirty_paused_when = 0; 1820 1821 p->pdeath_signal = 0; 1822 INIT_LIST_HEAD(&p->thread_group); 1823 p->task_works = NULL; 1824 1825 cgroup_threadgroup_change_begin(current); 1826 /* 1827 * Ensure that the cgroup subsystem policies allow the new process to be 1828 * forked. It should be noted the the new process's css_set can be changed 1829 * between here and cgroup_post_fork() if an organisation operation is in 1830 * progress. 1831 */ 1832 retval = cgroup_can_fork(p); 1833 if (retval) 1834 goto bad_fork_free_pid; 1835 1836 /* 1837 * Make it visible to the rest of the system, but dont wake it up yet. 1838 * Need tasklist lock for parent etc handling! 1839 */ 1840 write_lock_irq(&tasklist_lock); 1841 1842 /* CLONE_PARENT re-uses the old parent */ 1843 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { 1844 p->real_parent = current->real_parent; 1845 p->parent_exec_id = current->parent_exec_id; 1846 } else { 1847 p->real_parent = current; 1848 p->parent_exec_id = current->self_exec_id; 1849 } 1850 1851 klp_copy_process(p); 1852 1853 spin_lock(¤t->sighand->siglock); 1854 1855 /* 1856 * Copy seccomp details explicitly here, in case they were changed 1857 * before holding sighand lock. 1858 */ 1859 copy_seccomp(p); 1860 1861 /* 1862 * Process group and session signals need to be delivered to just the 1863 * parent before the fork or both the parent and the child after the 1864 * fork. Restart if a signal comes in before we add the new process to 1865 * it's process group. 1866 * A fatal signal pending means that current will exit, so the new 1867 * thread can't slip out of an OOM kill (or normal SIGKILL). 1868 */ 1869 recalc_sigpending(); 1870 if (signal_pending(current)) { 1871 retval = -ERESTARTNOINTR; 1872 goto bad_fork_cancel_cgroup; 1873 } 1874 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) { 1875 retval = -ENOMEM; 1876 goto bad_fork_cancel_cgroup; 1877 } 1878 1879 if (likely(p->pid)) { 1880 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); 1881 1882 init_task_pid(p, PIDTYPE_PID, pid); 1883 if (thread_group_leader(p)) { 1884 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); 1885 init_task_pid(p, PIDTYPE_SID, task_session(current)); 1886 1887 if (is_child_reaper(pid)) { 1888 ns_of_pid(pid)->child_reaper = p; 1889 p->signal->flags |= SIGNAL_UNKILLABLE; 1890 } 1891 1892 p->signal->leader_pid = pid; 1893 p->signal->tty = tty_kref_get(current->signal->tty); 1894 /* 1895 * Inherit has_child_subreaper flag under the same 1896 * tasklist_lock with adding child to the process tree 1897 * for propagate_has_child_subreaper optimization. 1898 */ 1899 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper || 1900 p->real_parent->signal->is_child_subreaper; 1901 list_add_tail(&p->sibling, &p->real_parent->children); 1902 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1903 attach_pid(p, PIDTYPE_PGID); 1904 attach_pid(p, PIDTYPE_SID); 1905 __this_cpu_inc(process_counts); 1906 } else { 1907 current->signal->nr_threads++; 1908 atomic_inc(¤t->signal->live); 1909 atomic_inc(¤t->signal->sigcnt); 1910 list_add_tail_rcu(&p->thread_group, 1911 &p->group_leader->thread_group); 1912 list_add_tail_rcu(&p->thread_node, 1913 &p->signal->thread_head); 1914 } 1915 attach_pid(p, PIDTYPE_PID); 1916 nr_threads++; 1917 } 1918 1919 total_forks++; 1920 spin_unlock(¤t->sighand->siglock); 1921 syscall_tracepoint_update(p); 1922 write_unlock_irq(&tasklist_lock); 1923 1924 proc_fork_connector(p); 1925 cgroup_post_fork(p); 1926 cgroup_threadgroup_change_end(current); 1927 perf_event_fork(p); 1928 1929 trace_task_newtask(p, clone_flags); 1930 uprobe_copy_process(p, clone_flags); 1931 1932 return p; 1933 1934 bad_fork_cancel_cgroup: 1935 spin_unlock(¤t->sighand->siglock); 1936 write_unlock_irq(&tasklist_lock); 1937 cgroup_cancel_fork(p); 1938 bad_fork_free_pid: 1939 cgroup_threadgroup_change_end(current); 1940 if (pid != &init_struct_pid) 1941 free_pid(pid); 1942 bad_fork_cleanup_thread: 1943 exit_thread(p); 1944 bad_fork_cleanup_io: 1945 if (p->io_context) 1946 exit_io_context(p); 1947 bad_fork_cleanup_namespaces: 1948 exit_task_namespaces(p); 1949 bad_fork_cleanup_mm: 1950 if (p->mm) 1951 mmput(p->mm); 1952 bad_fork_cleanup_signal: 1953 if (!(clone_flags & CLONE_THREAD)) 1954 free_signal_struct(p->signal); 1955 bad_fork_cleanup_sighand: 1956 __cleanup_sighand(p->sighand); 1957 bad_fork_cleanup_fs: 1958 exit_fs(p); /* blocking */ 1959 bad_fork_cleanup_files: 1960 exit_files(p); /* blocking */ 1961 bad_fork_cleanup_semundo: 1962 exit_sem(p); 1963 bad_fork_cleanup_security: 1964 security_task_free(p); 1965 bad_fork_cleanup_audit: 1966 audit_free(p); 1967 bad_fork_cleanup_perf: 1968 perf_event_free_task(p); 1969 bad_fork_cleanup_policy: 1970 lockdep_free_task(p); 1971 #ifdef CONFIG_NUMA 1972 mpol_put(p->mempolicy); 1973 bad_fork_cleanup_threadgroup_lock: 1974 #endif 1975 delayacct_tsk_free(p); 1976 bad_fork_cleanup_count: 1977 atomic_dec(&p->cred->user->processes); 1978 exit_creds(p); 1979 bad_fork_free: 1980 p->state = TASK_DEAD; 1981 put_task_stack(p); 1982 free_task(p); 1983 fork_out: 1984 return ERR_PTR(retval); 1985 } 1986 1987 static inline void init_idle_pids(struct pid_link *links) 1988 { 1989 enum pid_type type; 1990 1991 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { 1992 INIT_HLIST_NODE(&links[type].node); /* not really needed */ 1993 links[type].pid = &init_struct_pid; 1994 } 1995 } 1996 1997 struct task_struct *fork_idle(int cpu) 1998 { 1999 struct task_struct *task; 2000 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0, 2001 cpu_to_node(cpu)); 2002 if (!IS_ERR(task)) { 2003 init_idle_pids(task->pids); 2004 init_idle(task, cpu); 2005 } 2006 2007 return task; 2008 } 2009 2010 /* 2011 * Ok, this is the main fork-routine. 2012 * 2013 * It copies the process, and if successful kick-starts 2014 * it and waits for it to finish using the VM if required. 2015 */ 2016 long _do_fork(unsigned long clone_flags, 2017 unsigned long stack_start, 2018 unsigned long stack_size, 2019 int __user *parent_tidptr, 2020 int __user *child_tidptr, 2021 unsigned long tls) 2022 { 2023 struct task_struct *p; 2024 int trace = 0; 2025 long nr; 2026 2027 /* 2028 * Determine whether and which event to report to ptracer. When 2029 * called from kernel_thread or CLONE_UNTRACED is explicitly 2030 * requested, no event is reported; otherwise, report if the event 2031 * for the type of forking is enabled. 2032 */ 2033 if (!(clone_flags & CLONE_UNTRACED)) { 2034 if (clone_flags & CLONE_VFORK) 2035 trace = PTRACE_EVENT_VFORK; 2036 else if ((clone_flags & CSIGNAL) != SIGCHLD) 2037 trace = PTRACE_EVENT_CLONE; 2038 else 2039 trace = PTRACE_EVENT_FORK; 2040 2041 if (likely(!ptrace_event_enabled(current, trace))) 2042 trace = 0; 2043 } 2044 2045 p = copy_process(clone_flags, stack_start, stack_size, 2046 child_tidptr, NULL, trace, tls, NUMA_NO_NODE); 2047 add_latent_entropy(); 2048 /* 2049 * Do this prior waking up the new thread - the thread pointer 2050 * might get invalid after that point, if the thread exits quickly. 2051 */ 2052 if (!IS_ERR(p)) { 2053 struct completion vfork; 2054 struct pid *pid; 2055 2056 trace_sched_process_fork(current, p); 2057 2058 pid = get_task_pid(p, PIDTYPE_PID); 2059 nr = pid_vnr(pid); 2060 2061 if (clone_flags & CLONE_PARENT_SETTID) 2062 put_user(nr, parent_tidptr); 2063 2064 if (clone_flags & CLONE_VFORK) { 2065 p->vfork_done = &vfork; 2066 init_completion(&vfork); 2067 get_task_struct(p); 2068 } 2069 2070 wake_up_new_task(p); 2071 2072 /* forking complete and child started to run, tell ptracer */ 2073 if (unlikely(trace)) 2074 ptrace_event_pid(trace, pid); 2075 2076 if (clone_flags & CLONE_VFORK) { 2077 if (!wait_for_vfork_done(p, &vfork)) 2078 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); 2079 } 2080 2081 put_pid(pid); 2082 } else { 2083 nr = PTR_ERR(p); 2084 } 2085 return nr; 2086 } 2087 2088 #ifndef CONFIG_HAVE_COPY_THREAD_TLS 2089 /* For compatibility with architectures that call do_fork directly rather than 2090 * using the syscall entry points below. */ 2091 long do_fork(unsigned long clone_flags, 2092 unsigned long stack_start, 2093 unsigned long stack_size, 2094 int __user *parent_tidptr, 2095 int __user *child_tidptr) 2096 { 2097 return _do_fork(clone_flags, stack_start, stack_size, 2098 parent_tidptr, child_tidptr, 0); 2099 } 2100 #endif 2101 2102 /* 2103 * Create a kernel thread. 2104 */ 2105 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 2106 { 2107 return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, 2108 (unsigned long)arg, NULL, NULL, 0); 2109 } 2110 2111 #ifdef __ARCH_WANT_SYS_FORK 2112 SYSCALL_DEFINE0(fork) 2113 { 2114 #ifdef CONFIG_MMU 2115 return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0); 2116 #else 2117 /* can not support in nommu mode */ 2118 return -EINVAL; 2119 #endif 2120 } 2121 #endif 2122 2123 #ifdef __ARCH_WANT_SYS_VFORK 2124 SYSCALL_DEFINE0(vfork) 2125 { 2126 return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, 2127 0, NULL, NULL, 0); 2128 } 2129 #endif 2130 2131 #ifdef __ARCH_WANT_SYS_CLONE 2132 #ifdef CONFIG_CLONE_BACKWARDS 2133 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 2134 int __user *, parent_tidptr, 2135 unsigned long, tls, 2136 int __user *, child_tidptr) 2137 #elif defined(CONFIG_CLONE_BACKWARDS2) 2138 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, 2139 int __user *, parent_tidptr, 2140 int __user *, child_tidptr, 2141 unsigned long, tls) 2142 #elif defined(CONFIG_CLONE_BACKWARDS3) 2143 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, 2144 int, stack_size, 2145 int __user *, parent_tidptr, 2146 int __user *, child_tidptr, 2147 unsigned long, tls) 2148 #else 2149 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 2150 int __user *, parent_tidptr, 2151 int __user *, child_tidptr, 2152 unsigned long, tls) 2153 #endif 2154 { 2155 return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls); 2156 } 2157 #endif 2158 2159 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data) 2160 { 2161 struct task_struct *leader, *parent, *child; 2162 int res; 2163 2164 read_lock(&tasklist_lock); 2165 leader = top = top->group_leader; 2166 down: 2167 for_each_thread(leader, parent) { 2168 list_for_each_entry(child, &parent->children, sibling) { 2169 res = visitor(child, data); 2170 if (res) { 2171 if (res < 0) 2172 goto out; 2173 leader = child; 2174 goto down; 2175 } 2176 up: 2177 ; 2178 } 2179 } 2180 2181 if (leader != top) { 2182 child = leader; 2183 parent = child->real_parent; 2184 leader = parent->group_leader; 2185 goto up; 2186 } 2187 out: 2188 read_unlock(&tasklist_lock); 2189 } 2190 2191 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 2192 #define ARCH_MIN_MMSTRUCT_ALIGN 0 2193 #endif 2194 2195 static void sighand_ctor(void *data) 2196 { 2197 struct sighand_struct *sighand = data; 2198 2199 spin_lock_init(&sighand->siglock); 2200 init_waitqueue_head(&sighand->signalfd_wqh); 2201 } 2202 2203 void __init proc_caches_init(void) 2204 { 2205 sighand_cachep = kmem_cache_create("sighand_cache", 2206 sizeof(struct sighand_struct), 0, 2207 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU| 2208 SLAB_ACCOUNT, sighand_ctor); 2209 signal_cachep = kmem_cache_create("signal_cache", 2210 sizeof(struct signal_struct), 0, 2211 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2212 NULL); 2213 files_cachep = kmem_cache_create("files_cache", 2214 sizeof(struct files_struct), 0, 2215 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2216 NULL); 2217 fs_cachep = kmem_cache_create("fs_cache", 2218 sizeof(struct fs_struct), 0, 2219 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2220 NULL); 2221 /* 2222 * FIXME! The "sizeof(struct mm_struct)" currently includes the 2223 * whole struct cpumask for the OFFSTACK case. We could change 2224 * this to *only* allocate as much of it as required by the 2225 * maximum number of CPU's we can ever have. The cpumask_allocation 2226 * is at the end of the structure, exactly for that reason. 2227 */ 2228 mm_cachep = kmem_cache_create("mm_struct", 2229 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 2230 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2231 NULL); 2232 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); 2233 mmap_init(); 2234 nsproxy_cache_init(); 2235 } 2236 2237 /* 2238 * Check constraints on flags passed to the unshare system call. 2239 */ 2240 static int check_unshare_flags(unsigned long unshare_flags) 2241 { 2242 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 2243 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 2244 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| 2245 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP)) 2246 return -EINVAL; 2247 /* 2248 * Not implemented, but pretend it works if there is nothing 2249 * to unshare. Note that unsharing the address space or the 2250 * signal handlers also need to unshare the signal queues (aka 2251 * CLONE_THREAD). 2252 */ 2253 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { 2254 if (!thread_group_empty(current)) 2255 return -EINVAL; 2256 } 2257 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) { 2258 if (atomic_read(¤t->sighand->count) > 1) 2259 return -EINVAL; 2260 } 2261 if (unshare_flags & CLONE_VM) { 2262 if (!current_is_single_threaded()) 2263 return -EINVAL; 2264 } 2265 2266 return 0; 2267 } 2268 2269 /* 2270 * Unshare the filesystem structure if it is being shared 2271 */ 2272 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 2273 { 2274 struct fs_struct *fs = current->fs; 2275 2276 if (!(unshare_flags & CLONE_FS) || !fs) 2277 return 0; 2278 2279 /* don't need lock here; in the worst case we'll do useless copy */ 2280 if (fs->users == 1) 2281 return 0; 2282 2283 *new_fsp = copy_fs_struct(fs); 2284 if (!*new_fsp) 2285 return -ENOMEM; 2286 2287 return 0; 2288 } 2289 2290 /* 2291 * Unshare file descriptor table if it is being shared 2292 */ 2293 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 2294 { 2295 struct files_struct *fd = current->files; 2296 int error = 0; 2297 2298 if ((unshare_flags & CLONE_FILES) && 2299 (fd && atomic_read(&fd->count) > 1)) { 2300 *new_fdp = dup_fd(fd, &error); 2301 if (!*new_fdp) 2302 return error; 2303 } 2304 2305 return 0; 2306 } 2307 2308 /* 2309 * unshare allows a process to 'unshare' part of the process 2310 * context which was originally shared using clone. copy_* 2311 * functions used by do_fork() cannot be used here directly 2312 * because they modify an inactive task_struct that is being 2313 * constructed. Here we are modifying the current, active, 2314 * task_struct. 2315 */ 2316 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) 2317 { 2318 struct fs_struct *fs, *new_fs = NULL; 2319 struct files_struct *fd, *new_fd = NULL; 2320 struct cred *new_cred = NULL; 2321 struct nsproxy *new_nsproxy = NULL; 2322 int do_sysvsem = 0; 2323 int err; 2324 2325 /* 2326 * If unsharing a user namespace must also unshare the thread group 2327 * and unshare the filesystem root and working directories. 2328 */ 2329 if (unshare_flags & CLONE_NEWUSER) 2330 unshare_flags |= CLONE_THREAD | CLONE_FS; 2331 /* 2332 * If unsharing vm, must also unshare signal handlers. 2333 */ 2334 if (unshare_flags & CLONE_VM) 2335 unshare_flags |= CLONE_SIGHAND; 2336 /* 2337 * If unsharing a signal handlers, must also unshare the signal queues. 2338 */ 2339 if (unshare_flags & CLONE_SIGHAND) 2340 unshare_flags |= CLONE_THREAD; 2341 /* 2342 * If unsharing namespace, must also unshare filesystem information. 2343 */ 2344 if (unshare_flags & CLONE_NEWNS) 2345 unshare_flags |= CLONE_FS; 2346 2347 err = check_unshare_flags(unshare_flags); 2348 if (err) 2349 goto bad_unshare_out; 2350 /* 2351 * CLONE_NEWIPC must also detach from the undolist: after switching 2352 * to a new ipc namespace, the semaphore arrays from the old 2353 * namespace are unreachable. 2354 */ 2355 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) 2356 do_sysvsem = 1; 2357 err = unshare_fs(unshare_flags, &new_fs); 2358 if (err) 2359 goto bad_unshare_out; 2360 err = unshare_fd(unshare_flags, &new_fd); 2361 if (err) 2362 goto bad_unshare_cleanup_fs; 2363 err = unshare_userns(unshare_flags, &new_cred); 2364 if (err) 2365 goto bad_unshare_cleanup_fd; 2366 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 2367 new_cred, new_fs); 2368 if (err) 2369 goto bad_unshare_cleanup_cred; 2370 2371 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { 2372 if (do_sysvsem) { 2373 /* 2374 * CLONE_SYSVSEM is equivalent to sys_exit(). 2375 */ 2376 exit_sem(current); 2377 } 2378 if (unshare_flags & CLONE_NEWIPC) { 2379 /* Orphan segments in old ns (see sem above). */ 2380 exit_shm(current); 2381 shm_init_task(current); 2382 } 2383 2384 if (new_nsproxy) 2385 switch_task_namespaces(current, new_nsproxy); 2386 2387 task_lock(current); 2388 2389 if (new_fs) { 2390 fs = current->fs; 2391 spin_lock(&fs->lock); 2392 current->fs = new_fs; 2393 if (--fs->users) 2394 new_fs = NULL; 2395 else 2396 new_fs = fs; 2397 spin_unlock(&fs->lock); 2398 } 2399 2400 if (new_fd) { 2401 fd = current->files; 2402 current->files = new_fd; 2403 new_fd = fd; 2404 } 2405 2406 task_unlock(current); 2407 2408 if (new_cred) { 2409 /* Install the new user namespace */ 2410 commit_creds(new_cred); 2411 new_cred = NULL; 2412 } 2413 } 2414 2415 perf_event_namespaces(current); 2416 2417 bad_unshare_cleanup_cred: 2418 if (new_cred) 2419 put_cred(new_cred); 2420 bad_unshare_cleanup_fd: 2421 if (new_fd) 2422 put_files_struct(new_fd); 2423 2424 bad_unshare_cleanup_fs: 2425 if (new_fs) 2426 free_fs_struct(new_fs); 2427 2428 bad_unshare_out: 2429 return err; 2430 } 2431 2432 /* 2433 * Helper to unshare the files of the current task. 2434 * We don't want to expose copy_files internals to 2435 * the exec layer of the kernel. 2436 */ 2437 2438 int unshare_files(struct files_struct **displaced) 2439 { 2440 struct task_struct *task = current; 2441 struct files_struct *copy = NULL; 2442 int error; 2443 2444 error = unshare_fd(CLONE_FILES, ©); 2445 if (error || !copy) { 2446 *displaced = NULL; 2447 return error; 2448 } 2449 *displaced = task->files; 2450 task_lock(task); 2451 task->files = copy; 2452 task_unlock(task); 2453 return 0; 2454 } 2455 2456 int sysctl_max_threads(struct ctl_table *table, int write, 2457 void __user *buffer, size_t *lenp, loff_t *ppos) 2458 { 2459 struct ctl_table t; 2460 int ret; 2461 int threads = max_threads; 2462 int min = MIN_THREADS; 2463 int max = MAX_THREADS; 2464 2465 t = *table; 2466 t.data = &threads; 2467 t.extra1 = &min; 2468 t.extra2 = &max; 2469 2470 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 2471 if (ret || !write) 2472 return ret; 2473 2474 set_max_threads(threads); 2475 2476 return 0; 2477 } 2478