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 retval = arch_dup_mmap(oldmm, mm); 725 out: 726 up_write(&mm->mmap_sem); 727 flush_tlb_mm(oldmm); 728 up_write(&oldmm->mmap_sem); 729 dup_userfaultfd_complete(&uf); 730 fail_uprobe_end: 731 uprobe_end_dup_mmap(); 732 return retval; 733 fail_nomem_anon_vma_fork: 734 mpol_put(vma_policy(tmp)); 735 fail_nomem_policy: 736 kmem_cache_free(vm_area_cachep, tmp); 737 fail_nomem: 738 retval = -ENOMEM; 739 vm_unacct_memory(charge); 740 goto out; 741 } 742 743 static inline int mm_alloc_pgd(struct mm_struct *mm) 744 { 745 mm->pgd = pgd_alloc(mm); 746 if (unlikely(!mm->pgd)) 747 return -ENOMEM; 748 return 0; 749 } 750 751 static inline void mm_free_pgd(struct mm_struct *mm) 752 { 753 pgd_free(mm, mm->pgd); 754 } 755 #else 756 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 757 { 758 down_write(&oldmm->mmap_sem); 759 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 760 up_write(&oldmm->mmap_sem); 761 return 0; 762 } 763 #define mm_alloc_pgd(mm) (0) 764 #define mm_free_pgd(mm) 765 #endif /* CONFIG_MMU */ 766 767 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 768 769 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 770 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 771 772 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; 773 774 static int __init coredump_filter_setup(char *s) 775 { 776 default_dump_filter = 777 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & 778 MMF_DUMP_FILTER_MASK; 779 return 1; 780 } 781 782 __setup("coredump_filter=", coredump_filter_setup); 783 784 #include <linux/init_task.h> 785 786 static void mm_init_aio(struct mm_struct *mm) 787 { 788 #ifdef CONFIG_AIO 789 spin_lock_init(&mm->ioctx_lock); 790 mm->ioctx_table = NULL; 791 #endif 792 } 793 794 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) 795 { 796 #ifdef CONFIG_MEMCG 797 mm->owner = p; 798 #endif 799 } 800 801 static void mm_init_uprobes_state(struct mm_struct *mm) 802 { 803 #ifdef CONFIG_UPROBES 804 mm->uprobes_state.xol_area = NULL; 805 #endif 806 } 807 808 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, 809 struct user_namespace *user_ns) 810 { 811 mm->mmap = NULL; 812 mm->mm_rb = RB_ROOT; 813 mm->vmacache_seqnum = 0; 814 atomic_set(&mm->mm_users, 1); 815 atomic_set(&mm->mm_count, 1); 816 init_rwsem(&mm->mmap_sem); 817 INIT_LIST_HEAD(&mm->mmlist); 818 mm->core_state = NULL; 819 mm_pgtables_bytes_init(mm); 820 mm->map_count = 0; 821 mm->locked_vm = 0; 822 mm->pinned_vm = 0; 823 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); 824 spin_lock_init(&mm->page_table_lock); 825 mm_init_cpumask(mm); 826 mm_init_aio(mm); 827 mm_init_owner(mm, p); 828 RCU_INIT_POINTER(mm->exe_file, NULL); 829 mmu_notifier_mm_init(mm); 830 hmm_mm_init(mm); 831 init_tlb_flush_pending(mm); 832 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 833 mm->pmd_huge_pte = NULL; 834 #endif 835 mm_init_uprobes_state(mm); 836 837 if (current->mm) { 838 mm->flags = current->mm->flags & MMF_INIT_MASK; 839 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; 840 } else { 841 mm->flags = default_dump_filter; 842 mm->def_flags = 0; 843 } 844 845 if (mm_alloc_pgd(mm)) 846 goto fail_nopgd; 847 848 if (init_new_context(p, mm)) 849 goto fail_nocontext; 850 851 mm->user_ns = get_user_ns(user_ns); 852 return mm; 853 854 fail_nocontext: 855 mm_free_pgd(mm); 856 fail_nopgd: 857 free_mm(mm); 858 return NULL; 859 } 860 861 static void check_mm(struct mm_struct *mm) 862 { 863 int i; 864 865 for (i = 0; i < NR_MM_COUNTERS; i++) { 866 long x = atomic_long_read(&mm->rss_stat.count[i]); 867 868 if (unlikely(x)) 869 printk(KERN_ALERT "BUG: Bad rss-counter state " 870 "mm:%p idx:%d val:%ld\n", mm, i, x); 871 } 872 873 if (mm_pgtables_bytes(mm)) 874 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n", 875 mm_pgtables_bytes(mm)); 876 877 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 878 VM_BUG_ON_MM(mm->pmd_huge_pte, mm); 879 #endif 880 } 881 882 /* 883 * Allocate and initialize an mm_struct. 884 */ 885 struct mm_struct *mm_alloc(void) 886 { 887 struct mm_struct *mm; 888 889 mm = allocate_mm(); 890 if (!mm) 891 return NULL; 892 893 memset(mm, 0, sizeof(*mm)); 894 return mm_init(mm, current, current_user_ns()); 895 } 896 897 /* 898 * Called when the last reference to the mm 899 * is dropped: either by a lazy thread or by 900 * mmput. Free the page directory and the mm. 901 */ 902 void __mmdrop(struct mm_struct *mm) 903 { 904 BUG_ON(mm == &init_mm); 905 mm_free_pgd(mm); 906 destroy_context(mm); 907 hmm_mm_destroy(mm); 908 mmu_notifier_mm_destroy(mm); 909 check_mm(mm); 910 put_user_ns(mm->user_ns); 911 free_mm(mm); 912 } 913 EXPORT_SYMBOL_GPL(__mmdrop); 914 915 static inline void __mmput(struct mm_struct *mm) 916 { 917 VM_BUG_ON(atomic_read(&mm->mm_users)); 918 919 uprobe_clear_state(mm); 920 exit_aio(mm); 921 ksm_exit(mm); 922 khugepaged_exit(mm); /* must run before exit_mmap */ 923 exit_mmap(mm); 924 mm_put_huge_zero_page(mm); 925 set_mm_exe_file(mm, NULL); 926 if (!list_empty(&mm->mmlist)) { 927 spin_lock(&mmlist_lock); 928 list_del(&mm->mmlist); 929 spin_unlock(&mmlist_lock); 930 } 931 if (mm->binfmt) 932 module_put(mm->binfmt->module); 933 mmdrop(mm); 934 } 935 936 /* 937 * Decrement the use count and release all resources for an mm. 938 */ 939 void mmput(struct mm_struct *mm) 940 { 941 might_sleep(); 942 943 if (atomic_dec_and_test(&mm->mm_users)) 944 __mmput(mm); 945 } 946 EXPORT_SYMBOL_GPL(mmput); 947 948 #ifdef CONFIG_MMU 949 static void mmput_async_fn(struct work_struct *work) 950 { 951 struct mm_struct *mm = container_of(work, struct mm_struct, 952 async_put_work); 953 954 __mmput(mm); 955 } 956 957 void mmput_async(struct mm_struct *mm) 958 { 959 if (atomic_dec_and_test(&mm->mm_users)) { 960 INIT_WORK(&mm->async_put_work, mmput_async_fn); 961 schedule_work(&mm->async_put_work); 962 } 963 } 964 #endif 965 966 /** 967 * set_mm_exe_file - change a reference to the mm's executable file 968 * 969 * This changes mm's executable file (shown as symlink /proc/[pid]/exe). 970 * 971 * Main users are mmput() and sys_execve(). Callers prevent concurrent 972 * invocations: in mmput() nobody alive left, in execve task is single 973 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the 974 * mm->exe_file, but does so without using set_mm_exe_file() in order 975 * to do avoid the need for any locks. 976 */ 977 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) 978 { 979 struct file *old_exe_file; 980 981 /* 982 * It is safe to dereference the exe_file without RCU as 983 * this function is only called if nobody else can access 984 * this mm -- see comment above for justification. 985 */ 986 old_exe_file = rcu_dereference_raw(mm->exe_file); 987 988 if (new_exe_file) 989 get_file(new_exe_file); 990 rcu_assign_pointer(mm->exe_file, new_exe_file); 991 if (old_exe_file) 992 fput(old_exe_file); 993 } 994 995 /** 996 * get_mm_exe_file - acquire a reference to the mm's executable file 997 * 998 * Returns %NULL if mm has no associated executable file. 999 * User must release file via fput(). 1000 */ 1001 struct file *get_mm_exe_file(struct mm_struct *mm) 1002 { 1003 struct file *exe_file; 1004 1005 rcu_read_lock(); 1006 exe_file = rcu_dereference(mm->exe_file); 1007 if (exe_file && !get_file_rcu(exe_file)) 1008 exe_file = NULL; 1009 rcu_read_unlock(); 1010 return exe_file; 1011 } 1012 EXPORT_SYMBOL(get_mm_exe_file); 1013 1014 /** 1015 * get_task_exe_file - acquire a reference to the task's executable file 1016 * 1017 * Returns %NULL if task's mm (if any) has no associated executable file or 1018 * this is a kernel thread with borrowed mm (see the comment above get_task_mm). 1019 * User must release file via fput(). 1020 */ 1021 struct file *get_task_exe_file(struct task_struct *task) 1022 { 1023 struct file *exe_file = NULL; 1024 struct mm_struct *mm; 1025 1026 task_lock(task); 1027 mm = task->mm; 1028 if (mm) { 1029 if (!(task->flags & PF_KTHREAD)) 1030 exe_file = get_mm_exe_file(mm); 1031 } 1032 task_unlock(task); 1033 return exe_file; 1034 } 1035 EXPORT_SYMBOL(get_task_exe_file); 1036 1037 /** 1038 * get_task_mm - acquire a reference to the task's mm 1039 * 1040 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning 1041 * this kernel workthread has transiently adopted a user mm with use_mm, 1042 * to do its AIO) is not set and if so returns a reference to it, after 1043 * bumping up the use count. User must release the mm via mmput() 1044 * after use. Typically used by /proc and ptrace. 1045 */ 1046 struct mm_struct *get_task_mm(struct task_struct *task) 1047 { 1048 struct mm_struct *mm; 1049 1050 task_lock(task); 1051 mm = task->mm; 1052 if (mm) { 1053 if (task->flags & PF_KTHREAD) 1054 mm = NULL; 1055 else 1056 mmget(mm); 1057 } 1058 task_unlock(task); 1059 return mm; 1060 } 1061 EXPORT_SYMBOL_GPL(get_task_mm); 1062 1063 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) 1064 { 1065 struct mm_struct *mm; 1066 int err; 1067 1068 err = mutex_lock_killable(&task->signal->cred_guard_mutex); 1069 if (err) 1070 return ERR_PTR(err); 1071 1072 mm = get_task_mm(task); 1073 if (mm && mm != current->mm && 1074 !ptrace_may_access(task, mode)) { 1075 mmput(mm); 1076 mm = ERR_PTR(-EACCES); 1077 } 1078 mutex_unlock(&task->signal->cred_guard_mutex); 1079 1080 return mm; 1081 } 1082 1083 static void complete_vfork_done(struct task_struct *tsk) 1084 { 1085 struct completion *vfork; 1086 1087 task_lock(tsk); 1088 vfork = tsk->vfork_done; 1089 if (likely(vfork)) { 1090 tsk->vfork_done = NULL; 1091 complete(vfork); 1092 } 1093 task_unlock(tsk); 1094 } 1095 1096 static int wait_for_vfork_done(struct task_struct *child, 1097 struct completion *vfork) 1098 { 1099 int killed; 1100 1101 freezer_do_not_count(); 1102 killed = wait_for_completion_killable(vfork); 1103 freezer_count(); 1104 1105 if (killed) { 1106 task_lock(child); 1107 child->vfork_done = NULL; 1108 task_unlock(child); 1109 } 1110 1111 put_task_struct(child); 1112 return killed; 1113 } 1114 1115 /* Please note the differences between mmput and mm_release. 1116 * mmput is called whenever we stop holding onto a mm_struct, 1117 * error success whatever. 1118 * 1119 * mm_release is called after a mm_struct has been removed 1120 * from the current process. 1121 * 1122 * This difference is important for error handling, when we 1123 * only half set up a mm_struct for a new process and need to restore 1124 * the old one. Because we mmput the new mm_struct before 1125 * restoring the old one. . . 1126 * Eric Biederman 10 January 1998 1127 */ 1128 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 1129 { 1130 /* Get rid of any futexes when releasing the mm */ 1131 #ifdef CONFIG_FUTEX 1132 if (unlikely(tsk->robust_list)) { 1133 exit_robust_list(tsk); 1134 tsk->robust_list = NULL; 1135 } 1136 #ifdef CONFIG_COMPAT 1137 if (unlikely(tsk->compat_robust_list)) { 1138 compat_exit_robust_list(tsk); 1139 tsk->compat_robust_list = NULL; 1140 } 1141 #endif 1142 if (unlikely(!list_empty(&tsk->pi_state_list))) 1143 exit_pi_state_list(tsk); 1144 #endif 1145 1146 uprobe_free_utask(tsk); 1147 1148 /* Get rid of any cached register state */ 1149 deactivate_mm(tsk, mm); 1150 1151 /* 1152 * Signal userspace if we're not exiting with a core dump 1153 * because we want to leave the value intact for debugging 1154 * purposes. 1155 */ 1156 if (tsk->clear_child_tid) { 1157 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) && 1158 atomic_read(&mm->mm_users) > 1) { 1159 /* 1160 * We don't check the error code - if userspace has 1161 * not set up a proper pointer then tough luck. 1162 */ 1163 put_user(0, tsk->clear_child_tid); 1164 sys_futex(tsk->clear_child_tid, FUTEX_WAKE, 1165 1, NULL, NULL, 0); 1166 } 1167 tsk->clear_child_tid = NULL; 1168 } 1169 1170 /* 1171 * All done, finally we can wake up parent and return this mm to him. 1172 * Also kthread_stop() uses this completion for synchronization. 1173 */ 1174 if (tsk->vfork_done) 1175 complete_vfork_done(tsk); 1176 } 1177 1178 /* 1179 * Allocate a new mm structure and copy contents from the 1180 * mm structure of the passed in task structure. 1181 */ 1182 static struct mm_struct *dup_mm(struct task_struct *tsk) 1183 { 1184 struct mm_struct *mm, *oldmm = current->mm; 1185 int err; 1186 1187 mm = allocate_mm(); 1188 if (!mm) 1189 goto fail_nomem; 1190 1191 memcpy(mm, oldmm, sizeof(*mm)); 1192 1193 if (!mm_init(mm, tsk, mm->user_ns)) 1194 goto fail_nomem; 1195 1196 err = dup_mmap(mm, oldmm); 1197 if (err) 1198 goto free_pt; 1199 1200 mm->hiwater_rss = get_mm_rss(mm); 1201 mm->hiwater_vm = mm->total_vm; 1202 1203 if (mm->binfmt && !try_module_get(mm->binfmt->module)) 1204 goto free_pt; 1205 1206 return mm; 1207 1208 free_pt: 1209 /* don't put binfmt in mmput, we haven't got module yet */ 1210 mm->binfmt = NULL; 1211 mmput(mm); 1212 1213 fail_nomem: 1214 return NULL; 1215 } 1216 1217 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) 1218 { 1219 struct mm_struct *mm, *oldmm; 1220 int retval; 1221 1222 tsk->min_flt = tsk->maj_flt = 0; 1223 tsk->nvcsw = tsk->nivcsw = 0; 1224 #ifdef CONFIG_DETECT_HUNG_TASK 1225 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; 1226 #endif 1227 1228 tsk->mm = NULL; 1229 tsk->active_mm = NULL; 1230 1231 /* 1232 * Are we cloning a kernel thread? 1233 * 1234 * We need to steal a active VM for that.. 1235 */ 1236 oldmm = current->mm; 1237 if (!oldmm) 1238 return 0; 1239 1240 /* initialize the new vmacache entries */ 1241 vmacache_flush(tsk); 1242 1243 if (clone_flags & CLONE_VM) { 1244 mmget(oldmm); 1245 mm = oldmm; 1246 goto good_mm; 1247 } 1248 1249 retval = -ENOMEM; 1250 mm = dup_mm(tsk); 1251 if (!mm) 1252 goto fail_nomem; 1253 1254 good_mm: 1255 tsk->mm = mm; 1256 tsk->active_mm = mm; 1257 return 0; 1258 1259 fail_nomem: 1260 return retval; 1261 } 1262 1263 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 1264 { 1265 struct fs_struct *fs = current->fs; 1266 if (clone_flags & CLONE_FS) { 1267 /* tsk->fs is already what we want */ 1268 spin_lock(&fs->lock); 1269 if (fs->in_exec) { 1270 spin_unlock(&fs->lock); 1271 return -EAGAIN; 1272 } 1273 fs->users++; 1274 spin_unlock(&fs->lock); 1275 return 0; 1276 } 1277 tsk->fs = copy_fs_struct(fs); 1278 if (!tsk->fs) 1279 return -ENOMEM; 1280 return 0; 1281 } 1282 1283 static int copy_files(unsigned long clone_flags, struct task_struct *tsk) 1284 { 1285 struct files_struct *oldf, *newf; 1286 int error = 0; 1287 1288 /* 1289 * A background process may not have any files ... 1290 */ 1291 oldf = current->files; 1292 if (!oldf) 1293 goto out; 1294 1295 if (clone_flags & CLONE_FILES) { 1296 atomic_inc(&oldf->count); 1297 goto out; 1298 } 1299 1300 newf = dup_fd(oldf, &error); 1301 if (!newf) 1302 goto out; 1303 1304 tsk->files = newf; 1305 error = 0; 1306 out: 1307 return error; 1308 } 1309 1310 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 1311 { 1312 #ifdef CONFIG_BLOCK 1313 struct io_context *ioc = current->io_context; 1314 struct io_context *new_ioc; 1315 1316 if (!ioc) 1317 return 0; 1318 /* 1319 * Share io context with parent, if CLONE_IO is set 1320 */ 1321 if (clone_flags & CLONE_IO) { 1322 ioc_task_link(ioc); 1323 tsk->io_context = ioc; 1324 } else if (ioprio_valid(ioc->ioprio)) { 1325 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); 1326 if (unlikely(!new_ioc)) 1327 return -ENOMEM; 1328 1329 new_ioc->ioprio = ioc->ioprio; 1330 put_io_context(new_ioc); 1331 } 1332 #endif 1333 return 0; 1334 } 1335 1336 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 1337 { 1338 struct sighand_struct *sig; 1339 1340 if (clone_flags & CLONE_SIGHAND) { 1341 atomic_inc(¤t->sighand->count); 1342 return 0; 1343 } 1344 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 1345 rcu_assign_pointer(tsk->sighand, sig); 1346 if (!sig) 1347 return -ENOMEM; 1348 1349 atomic_set(&sig->count, 1); 1350 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 1351 return 0; 1352 } 1353 1354 void __cleanup_sighand(struct sighand_struct *sighand) 1355 { 1356 if (atomic_dec_and_test(&sighand->count)) { 1357 signalfd_cleanup(sighand); 1358 /* 1359 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it 1360 * without an RCU grace period, see __lock_task_sighand(). 1361 */ 1362 kmem_cache_free(sighand_cachep, sighand); 1363 } 1364 } 1365 1366 #ifdef CONFIG_POSIX_TIMERS 1367 /* 1368 * Initialize POSIX timer handling for a thread group. 1369 */ 1370 static void posix_cpu_timers_init_group(struct signal_struct *sig) 1371 { 1372 unsigned long cpu_limit; 1373 1374 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); 1375 if (cpu_limit != RLIM_INFINITY) { 1376 sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC; 1377 sig->cputimer.running = true; 1378 } 1379 1380 /* The timer lists. */ 1381 INIT_LIST_HEAD(&sig->cpu_timers[0]); 1382 INIT_LIST_HEAD(&sig->cpu_timers[1]); 1383 INIT_LIST_HEAD(&sig->cpu_timers[2]); 1384 } 1385 #else 1386 static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { } 1387 #endif 1388 1389 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 1390 { 1391 struct signal_struct *sig; 1392 1393 if (clone_flags & CLONE_THREAD) 1394 return 0; 1395 1396 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); 1397 tsk->signal = sig; 1398 if (!sig) 1399 return -ENOMEM; 1400 1401 sig->nr_threads = 1; 1402 atomic_set(&sig->live, 1); 1403 atomic_set(&sig->sigcnt, 1); 1404 1405 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ 1406 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); 1407 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); 1408 1409 init_waitqueue_head(&sig->wait_chldexit); 1410 sig->curr_target = tsk; 1411 init_sigpending(&sig->shared_pending); 1412 seqlock_init(&sig->stats_lock); 1413 prev_cputime_init(&sig->prev_cputime); 1414 1415 #ifdef CONFIG_POSIX_TIMERS 1416 INIT_LIST_HEAD(&sig->posix_timers); 1417 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 1418 sig->real_timer.function = it_real_fn; 1419 #endif 1420 1421 task_lock(current->group_leader); 1422 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 1423 task_unlock(current->group_leader); 1424 1425 posix_cpu_timers_init_group(sig); 1426 1427 tty_audit_fork(sig); 1428 sched_autogroup_fork(sig); 1429 1430 sig->oom_score_adj = current->signal->oom_score_adj; 1431 sig->oom_score_adj_min = current->signal->oom_score_adj_min; 1432 1433 mutex_init(&sig->cred_guard_mutex); 1434 1435 return 0; 1436 } 1437 1438 static void copy_seccomp(struct task_struct *p) 1439 { 1440 #ifdef CONFIG_SECCOMP 1441 /* 1442 * Must be called with sighand->lock held, which is common to 1443 * all threads in the group. Holding cred_guard_mutex is not 1444 * needed because this new task is not yet running and cannot 1445 * be racing exec. 1446 */ 1447 assert_spin_locked(¤t->sighand->siglock); 1448 1449 /* Ref-count the new filter user, and assign it. */ 1450 get_seccomp_filter(current); 1451 p->seccomp = current->seccomp; 1452 1453 /* 1454 * Explicitly enable no_new_privs here in case it got set 1455 * between the task_struct being duplicated and holding the 1456 * sighand lock. The seccomp state and nnp must be in sync. 1457 */ 1458 if (task_no_new_privs(current)) 1459 task_set_no_new_privs(p); 1460 1461 /* 1462 * If the parent gained a seccomp mode after copying thread 1463 * flags and between before we held the sighand lock, we have 1464 * to manually enable the seccomp thread flag here. 1465 */ 1466 if (p->seccomp.mode != SECCOMP_MODE_DISABLED) 1467 set_tsk_thread_flag(p, TIF_SECCOMP); 1468 #endif 1469 } 1470 1471 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) 1472 { 1473 current->clear_child_tid = tidptr; 1474 1475 return task_pid_vnr(current); 1476 } 1477 1478 static void rt_mutex_init_task(struct task_struct *p) 1479 { 1480 raw_spin_lock_init(&p->pi_lock); 1481 #ifdef CONFIG_RT_MUTEXES 1482 p->pi_waiters = RB_ROOT_CACHED; 1483 p->pi_top_task = NULL; 1484 p->pi_blocked_on = NULL; 1485 #endif 1486 } 1487 1488 #ifdef CONFIG_POSIX_TIMERS 1489 /* 1490 * Initialize POSIX timer handling for a single task. 1491 */ 1492 static void posix_cpu_timers_init(struct task_struct *tsk) 1493 { 1494 tsk->cputime_expires.prof_exp = 0; 1495 tsk->cputime_expires.virt_exp = 0; 1496 tsk->cputime_expires.sched_exp = 0; 1497 INIT_LIST_HEAD(&tsk->cpu_timers[0]); 1498 INIT_LIST_HEAD(&tsk->cpu_timers[1]); 1499 INIT_LIST_HEAD(&tsk->cpu_timers[2]); 1500 } 1501 #else 1502 static inline void posix_cpu_timers_init(struct task_struct *tsk) { } 1503 #endif 1504 1505 static inline void 1506 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) 1507 { 1508 task->pids[type].pid = pid; 1509 } 1510 1511 static inline void rcu_copy_process(struct task_struct *p) 1512 { 1513 #ifdef CONFIG_PREEMPT_RCU 1514 p->rcu_read_lock_nesting = 0; 1515 p->rcu_read_unlock_special.s = 0; 1516 p->rcu_blocked_node = NULL; 1517 INIT_LIST_HEAD(&p->rcu_node_entry); 1518 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 1519 #ifdef CONFIG_TASKS_RCU 1520 p->rcu_tasks_holdout = false; 1521 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list); 1522 p->rcu_tasks_idle_cpu = -1; 1523 #endif /* #ifdef CONFIG_TASKS_RCU */ 1524 } 1525 1526 /* 1527 * This creates a new process as a copy of the old one, 1528 * but does not actually start it yet. 1529 * 1530 * It copies the registers, and all the appropriate 1531 * parts of the process environment (as per the clone 1532 * flags). The actual kick-off is left to the caller. 1533 */ 1534 static __latent_entropy struct task_struct *copy_process( 1535 unsigned long clone_flags, 1536 unsigned long stack_start, 1537 unsigned long stack_size, 1538 int __user *child_tidptr, 1539 struct pid *pid, 1540 int trace, 1541 unsigned long tls, 1542 int node) 1543 { 1544 int retval; 1545 struct task_struct *p; 1546 1547 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1548 return ERR_PTR(-EINVAL); 1549 1550 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) 1551 return ERR_PTR(-EINVAL); 1552 1553 /* 1554 * Thread groups must share signals as well, and detached threads 1555 * can only be started up within the thread group. 1556 */ 1557 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1558 return ERR_PTR(-EINVAL); 1559 1560 /* 1561 * Shared signal handlers imply shared VM. By way of the above, 1562 * thread groups also imply shared VM. Blocking this case allows 1563 * for various simplifications in other code. 1564 */ 1565 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1566 return ERR_PTR(-EINVAL); 1567 1568 /* 1569 * Siblings of global init remain as zombies on exit since they are 1570 * not reaped by their parent (swapper). To solve this and to avoid 1571 * multi-rooted process trees, prevent global and container-inits 1572 * from creating siblings. 1573 */ 1574 if ((clone_flags & CLONE_PARENT) && 1575 current->signal->flags & SIGNAL_UNKILLABLE) 1576 return ERR_PTR(-EINVAL); 1577 1578 /* 1579 * If the new process will be in a different pid or user namespace 1580 * do not allow it to share a thread group with the forking task. 1581 */ 1582 if (clone_flags & CLONE_THREAD) { 1583 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || 1584 (task_active_pid_ns(current) != 1585 current->nsproxy->pid_ns_for_children)) 1586 return ERR_PTR(-EINVAL); 1587 } 1588 1589 retval = -ENOMEM; 1590 p = dup_task_struct(current, node); 1591 if (!p) 1592 goto fork_out; 1593 1594 /* 1595 * This _must_ happen before we call free_task(), i.e. before we jump 1596 * to any of the bad_fork_* labels. This is to avoid freeing 1597 * p->set_child_tid which is (ab)used as a kthread's data pointer for 1598 * kernel threads (PF_KTHREAD). 1599 */ 1600 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1601 /* 1602 * Clear TID on mm_release()? 1603 */ 1604 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; 1605 1606 ftrace_graph_init_task(p); 1607 1608 rt_mutex_init_task(p); 1609 1610 #ifdef CONFIG_PROVE_LOCKING 1611 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 1612 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1613 #endif 1614 retval = -EAGAIN; 1615 if (atomic_read(&p->real_cred->user->processes) >= 1616 task_rlimit(p, RLIMIT_NPROC)) { 1617 if (p->real_cred->user != INIT_USER && 1618 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) 1619 goto bad_fork_free; 1620 } 1621 current->flags &= ~PF_NPROC_EXCEEDED; 1622 1623 retval = copy_creds(p, clone_flags); 1624 if (retval < 0) 1625 goto bad_fork_free; 1626 1627 /* 1628 * If multiple threads are within copy_process(), then this check 1629 * triggers too late. This doesn't hurt, the check is only there 1630 * to stop root fork bombs. 1631 */ 1632 retval = -EAGAIN; 1633 if (nr_threads >= max_threads) 1634 goto bad_fork_cleanup_count; 1635 1636 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1637 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE); 1638 p->flags |= PF_FORKNOEXEC; 1639 INIT_LIST_HEAD(&p->children); 1640 INIT_LIST_HEAD(&p->sibling); 1641 rcu_copy_process(p); 1642 p->vfork_done = NULL; 1643 spin_lock_init(&p->alloc_lock); 1644 1645 init_sigpending(&p->pending); 1646 1647 p->utime = p->stime = p->gtime = 0; 1648 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME 1649 p->utimescaled = p->stimescaled = 0; 1650 #endif 1651 prev_cputime_init(&p->prev_cputime); 1652 1653 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN 1654 seqcount_init(&p->vtime.seqcount); 1655 p->vtime.starttime = 0; 1656 p->vtime.state = VTIME_INACTIVE; 1657 #endif 1658 1659 #if defined(SPLIT_RSS_COUNTING) 1660 memset(&p->rss_stat, 0, sizeof(p->rss_stat)); 1661 #endif 1662 1663 p->default_timer_slack_ns = current->timer_slack_ns; 1664 1665 task_io_accounting_init(&p->ioac); 1666 acct_clear_integrals(p); 1667 1668 posix_cpu_timers_init(p); 1669 1670 p->start_time = ktime_get_ns(); 1671 p->real_start_time = ktime_get_boot_ns(); 1672 p->io_context = NULL; 1673 p->audit_context = NULL; 1674 cgroup_fork(p); 1675 #ifdef CONFIG_NUMA 1676 p->mempolicy = mpol_dup(p->mempolicy); 1677 if (IS_ERR(p->mempolicy)) { 1678 retval = PTR_ERR(p->mempolicy); 1679 p->mempolicy = NULL; 1680 goto bad_fork_cleanup_threadgroup_lock; 1681 } 1682 #endif 1683 #ifdef CONFIG_CPUSETS 1684 p->cpuset_mem_spread_rotor = NUMA_NO_NODE; 1685 p->cpuset_slab_spread_rotor = NUMA_NO_NODE; 1686 seqcount_init(&p->mems_allowed_seq); 1687 #endif 1688 #ifdef CONFIG_TRACE_IRQFLAGS 1689 p->irq_events = 0; 1690 p->hardirqs_enabled = 0; 1691 p->hardirq_enable_ip = 0; 1692 p->hardirq_enable_event = 0; 1693 p->hardirq_disable_ip = _THIS_IP_; 1694 p->hardirq_disable_event = 0; 1695 p->softirqs_enabled = 1; 1696 p->softirq_enable_ip = _THIS_IP_; 1697 p->softirq_enable_event = 0; 1698 p->softirq_disable_ip = 0; 1699 p->softirq_disable_event = 0; 1700 p->hardirq_context = 0; 1701 p->softirq_context = 0; 1702 #endif 1703 1704 p->pagefault_disabled = 0; 1705 1706 #ifdef CONFIG_LOCKDEP 1707 p->lockdep_depth = 0; /* no locks held yet */ 1708 p->curr_chain_key = 0; 1709 p->lockdep_recursion = 0; 1710 lockdep_init_task(p); 1711 #endif 1712 1713 #ifdef CONFIG_DEBUG_MUTEXES 1714 p->blocked_on = NULL; /* not blocked yet */ 1715 #endif 1716 #ifdef CONFIG_BCACHE 1717 p->sequential_io = 0; 1718 p->sequential_io_avg = 0; 1719 #endif 1720 1721 /* Perform scheduler related setup. Assign this task to a CPU. */ 1722 retval = sched_fork(clone_flags, p); 1723 if (retval) 1724 goto bad_fork_cleanup_policy; 1725 1726 retval = perf_event_init_task(p); 1727 if (retval) 1728 goto bad_fork_cleanup_policy; 1729 retval = audit_alloc(p); 1730 if (retval) 1731 goto bad_fork_cleanup_perf; 1732 /* copy all the process information */ 1733 shm_init_task(p); 1734 retval = security_task_alloc(p, clone_flags); 1735 if (retval) 1736 goto bad_fork_cleanup_audit; 1737 retval = copy_semundo(clone_flags, p); 1738 if (retval) 1739 goto bad_fork_cleanup_security; 1740 retval = copy_files(clone_flags, p); 1741 if (retval) 1742 goto bad_fork_cleanup_semundo; 1743 retval = copy_fs(clone_flags, p); 1744 if (retval) 1745 goto bad_fork_cleanup_files; 1746 retval = copy_sighand(clone_flags, p); 1747 if (retval) 1748 goto bad_fork_cleanup_fs; 1749 retval = copy_signal(clone_flags, p); 1750 if (retval) 1751 goto bad_fork_cleanup_sighand; 1752 retval = copy_mm(clone_flags, p); 1753 if (retval) 1754 goto bad_fork_cleanup_signal; 1755 retval = copy_namespaces(clone_flags, p); 1756 if (retval) 1757 goto bad_fork_cleanup_mm; 1758 retval = copy_io(clone_flags, p); 1759 if (retval) 1760 goto bad_fork_cleanup_namespaces; 1761 retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls); 1762 if (retval) 1763 goto bad_fork_cleanup_io; 1764 1765 if (pid != &init_struct_pid) { 1766 pid = alloc_pid(p->nsproxy->pid_ns_for_children); 1767 if (IS_ERR(pid)) { 1768 retval = PTR_ERR(pid); 1769 goto bad_fork_cleanup_thread; 1770 } 1771 } 1772 1773 #ifdef CONFIG_BLOCK 1774 p->plug = NULL; 1775 #endif 1776 #ifdef CONFIG_FUTEX 1777 p->robust_list = NULL; 1778 #ifdef CONFIG_COMPAT 1779 p->compat_robust_list = NULL; 1780 #endif 1781 INIT_LIST_HEAD(&p->pi_state_list); 1782 p->pi_state_cache = NULL; 1783 #endif 1784 /* 1785 * sigaltstack should be cleared when sharing the same VM 1786 */ 1787 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1788 sas_ss_reset(p); 1789 1790 /* 1791 * Syscall tracing and stepping should be turned off in the 1792 * child regardless of CLONE_PTRACE. 1793 */ 1794 user_disable_single_step(p); 1795 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1796 #ifdef TIF_SYSCALL_EMU 1797 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1798 #endif 1799 clear_all_latency_tracing(p); 1800 1801 /* ok, now we should be set up.. */ 1802 p->pid = pid_nr(pid); 1803 if (clone_flags & CLONE_THREAD) { 1804 p->exit_signal = -1; 1805 p->group_leader = current->group_leader; 1806 p->tgid = current->tgid; 1807 } else { 1808 if (clone_flags & CLONE_PARENT) 1809 p->exit_signal = current->group_leader->exit_signal; 1810 else 1811 p->exit_signal = (clone_flags & CSIGNAL); 1812 p->group_leader = p; 1813 p->tgid = p->pid; 1814 } 1815 1816 p->nr_dirtied = 0; 1817 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); 1818 p->dirty_paused_when = 0; 1819 1820 p->pdeath_signal = 0; 1821 INIT_LIST_HEAD(&p->thread_group); 1822 p->task_works = NULL; 1823 1824 cgroup_threadgroup_change_begin(current); 1825 /* 1826 * Ensure that the cgroup subsystem policies allow the new process to be 1827 * forked. It should be noted the the new process's css_set can be changed 1828 * between here and cgroup_post_fork() if an organisation operation is in 1829 * progress. 1830 */ 1831 retval = cgroup_can_fork(p); 1832 if (retval) 1833 goto bad_fork_free_pid; 1834 1835 /* 1836 * Make it visible to the rest of the system, but dont wake it up yet. 1837 * Need tasklist lock for parent etc handling! 1838 */ 1839 write_lock_irq(&tasklist_lock); 1840 1841 /* CLONE_PARENT re-uses the old parent */ 1842 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { 1843 p->real_parent = current->real_parent; 1844 p->parent_exec_id = current->parent_exec_id; 1845 } else { 1846 p->real_parent = current; 1847 p->parent_exec_id = current->self_exec_id; 1848 } 1849 1850 klp_copy_process(p); 1851 1852 spin_lock(¤t->sighand->siglock); 1853 1854 /* 1855 * Copy seccomp details explicitly here, in case they were changed 1856 * before holding sighand lock. 1857 */ 1858 copy_seccomp(p); 1859 1860 /* 1861 * Process group and session signals need to be delivered to just the 1862 * parent before the fork or both the parent and the child after the 1863 * fork. Restart if a signal comes in before we add the new process to 1864 * it's process group. 1865 * A fatal signal pending means that current will exit, so the new 1866 * thread can't slip out of an OOM kill (or normal SIGKILL). 1867 */ 1868 recalc_sigpending(); 1869 if (signal_pending(current)) { 1870 retval = -ERESTARTNOINTR; 1871 goto bad_fork_cancel_cgroup; 1872 } 1873 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) { 1874 retval = -ENOMEM; 1875 goto bad_fork_cancel_cgroup; 1876 } 1877 1878 if (likely(p->pid)) { 1879 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); 1880 1881 init_task_pid(p, PIDTYPE_PID, pid); 1882 if (thread_group_leader(p)) { 1883 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); 1884 init_task_pid(p, PIDTYPE_SID, task_session(current)); 1885 1886 if (is_child_reaper(pid)) { 1887 ns_of_pid(pid)->child_reaper = p; 1888 p->signal->flags |= SIGNAL_UNKILLABLE; 1889 } 1890 1891 p->signal->leader_pid = pid; 1892 p->signal->tty = tty_kref_get(current->signal->tty); 1893 /* 1894 * Inherit has_child_subreaper flag under the same 1895 * tasklist_lock with adding child to the process tree 1896 * for propagate_has_child_subreaper optimization. 1897 */ 1898 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper || 1899 p->real_parent->signal->is_child_subreaper; 1900 list_add_tail(&p->sibling, &p->real_parent->children); 1901 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1902 attach_pid(p, PIDTYPE_PGID); 1903 attach_pid(p, PIDTYPE_SID); 1904 __this_cpu_inc(process_counts); 1905 } else { 1906 current->signal->nr_threads++; 1907 atomic_inc(¤t->signal->live); 1908 atomic_inc(¤t->signal->sigcnt); 1909 list_add_tail_rcu(&p->thread_group, 1910 &p->group_leader->thread_group); 1911 list_add_tail_rcu(&p->thread_node, 1912 &p->signal->thread_head); 1913 } 1914 attach_pid(p, PIDTYPE_PID); 1915 nr_threads++; 1916 } 1917 1918 total_forks++; 1919 spin_unlock(¤t->sighand->siglock); 1920 syscall_tracepoint_update(p); 1921 write_unlock_irq(&tasklist_lock); 1922 1923 proc_fork_connector(p); 1924 cgroup_post_fork(p); 1925 cgroup_threadgroup_change_end(current); 1926 perf_event_fork(p); 1927 1928 trace_task_newtask(p, clone_flags); 1929 uprobe_copy_process(p, clone_flags); 1930 1931 return p; 1932 1933 bad_fork_cancel_cgroup: 1934 spin_unlock(¤t->sighand->siglock); 1935 write_unlock_irq(&tasklist_lock); 1936 cgroup_cancel_fork(p); 1937 bad_fork_free_pid: 1938 cgroup_threadgroup_change_end(current); 1939 if (pid != &init_struct_pid) 1940 free_pid(pid); 1941 bad_fork_cleanup_thread: 1942 exit_thread(p); 1943 bad_fork_cleanup_io: 1944 if (p->io_context) 1945 exit_io_context(p); 1946 bad_fork_cleanup_namespaces: 1947 exit_task_namespaces(p); 1948 bad_fork_cleanup_mm: 1949 if (p->mm) 1950 mmput(p->mm); 1951 bad_fork_cleanup_signal: 1952 if (!(clone_flags & CLONE_THREAD)) 1953 free_signal_struct(p->signal); 1954 bad_fork_cleanup_sighand: 1955 __cleanup_sighand(p->sighand); 1956 bad_fork_cleanup_fs: 1957 exit_fs(p); /* blocking */ 1958 bad_fork_cleanup_files: 1959 exit_files(p); /* blocking */ 1960 bad_fork_cleanup_semundo: 1961 exit_sem(p); 1962 bad_fork_cleanup_security: 1963 security_task_free(p); 1964 bad_fork_cleanup_audit: 1965 audit_free(p); 1966 bad_fork_cleanup_perf: 1967 perf_event_free_task(p); 1968 bad_fork_cleanup_policy: 1969 lockdep_free_task(p); 1970 #ifdef CONFIG_NUMA 1971 mpol_put(p->mempolicy); 1972 bad_fork_cleanup_threadgroup_lock: 1973 #endif 1974 delayacct_tsk_free(p); 1975 bad_fork_cleanup_count: 1976 atomic_dec(&p->cred->user->processes); 1977 exit_creds(p); 1978 bad_fork_free: 1979 p->state = TASK_DEAD; 1980 put_task_stack(p); 1981 free_task(p); 1982 fork_out: 1983 return ERR_PTR(retval); 1984 } 1985 1986 static inline void init_idle_pids(struct pid_link *links) 1987 { 1988 enum pid_type type; 1989 1990 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { 1991 INIT_HLIST_NODE(&links[type].node); /* not really needed */ 1992 links[type].pid = &init_struct_pid; 1993 } 1994 } 1995 1996 struct task_struct *fork_idle(int cpu) 1997 { 1998 struct task_struct *task; 1999 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0, 2000 cpu_to_node(cpu)); 2001 if (!IS_ERR(task)) { 2002 init_idle_pids(task->pids); 2003 init_idle(task, cpu); 2004 } 2005 2006 return task; 2007 } 2008 2009 /* 2010 * Ok, this is the main fork-routine. 2011 * 2012 * It copies the process, and if successful kick-starts 2013 * it and waits for it to finish using the VM if required. 2014 */ 2015 long _do_fork(unsigned long clone_flags, 2016 unsigned long stack_start, 2017 unsigned long stack_size, 2018 int __user *parent_tidptr, 2019 int __user *child_tidptr, 2020 unsigned long tls) 2021 { 2022 struct task_struct *p; 2023 int trace = 0; 2024 long nr; 2025 2026 /* 2027 * Determine whether and which event to report to ptracer. When 2028 * called from kernel_thread or CLONE_UNTRACED is explicitly 2029 * requested, no event is reported; otherwise, report if the event 2030 * for the type of forking is enabled. 2031 */ 2032 if (!(clone_flags & CLONE_UNTRACED)) { 2033 if (clone_flags & CLONE_VFORK) 2034 trace = PTRACE_EVENT_VFORK; 2035 else if ((clone_flags & CSIGNAL) != SIGCHLD) 2036 trace = PTRACE_EVENT_CLONE; 2037 else 2038 trace = PTRACE_EVENT_FORK; 2039 2040 if (likely(!ptrace_event_enabled(current, trace))) 2041 trace = 0; 2042 } 2043 2044 p = copy_process(clone_flags, stack_start, stack_size, 2045 child_tidptr, NULL, trace, tls, NUMA_NO_NODE); 2046 add_latent_entropy(); 2047 /* 2048 * Do this prior waking up the new thread - the thread pointer 2049 * might get invalid after that point, if the thread exits quickly. 2050 */ 2051 if (!IS_ERR(p)) { 2052 struct completion vfork; 2053 struct pid *pid; 2054 2055 trace_sched_process_fork(current, p); 2056 2057 pid = get_task_pid(p, PIDTYPE_PID); 2058 nr = pid_vnr(pid); 2059 2060 if (clone_flags & CLONE_PARENT_SETTID) 2061 put_user(nr, parent_tidptr); 2062 2063 if (clone_flags & CLONE_VFORK) { 2064 p->vfork_done = &vfork; 2065 init_completion(&vfork); 2066 get_task_struct(p); 2067 } 2068 2069 wake_up_new_task(p); 2070 2071 /* forking complete and child started to run, tell ptracer */ 2072 if (unlikely(trace)) 2073 ptrace_event_pid(trace, pid); 2074 2075 if (clone_flags & CLONE_VFORK) { 2076 if (!wait_for_vfork_done(p, &vfork)) 2077 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); 2078 } 2079 2080 put_pid(pid); 2081 } else { 2082 nr = PTR_ERR(p); 2083 } 2084 return nr; 2085 } 2086 2087 #ifndef CONFIG_HAVE_COPY_THREAD_TLS 2088 /* For compatibility with architectures that call do_fork directly rather than 2089 * using the syscall entry points below. */ 2090 long do_fork(unsigned long clone_flags, 2091 unsigned long stack_start, 2092 unsigned long stack_size, 2093 int __user *parent_tidptr, 2094 int __user *child_tidptr) 2095 { 2096 return _do_fork(clone_flags, stack_start, stack_size, 2097 parent_tidptr, child_tidptr, 0); 2098 } 2099 #endif 2100 2101 /* 2102 * Create a kernel thread. 2103 */ 2104 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 2105 { 2106 return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, 2107 (unsigned long)arg, NULL, NULL, 0); 2108 } 2109 2110 #ifdef __ARCH_WANT_SYS_FORK 2111 SYSCALL_DEFINE0(fork) 2112 { 2113 #ifdef CONFIG_MMU 2114 return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0); 2115 #else 2116 /* can not support in nommu mode */ 2117 return -EINVAL; 2118 #endif 2119 } 2120 #endif 2121 2122 #ifdef __ARCH_WANT_SYS_VFORK 2123 SYSCALL_DEFINE0(vfork) 2124 { 2125 return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, 2126 0, NULL, NULL, 0); 2127 } 2128 #endif 2129 2130 #ifdef __ARCH_WANT_SYS_CLONE 2131 #ifdef CONFIG_CLONE_BACKWARDS 2132 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 2133 int __user *, parent_tidptr, 2134 unsigned long, tls, 2135 int __user *, child_tidptr) 2136 #elif defined(CONFIG_CLONE_BACKWARDS2) 2137 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, 2138 int __user *, parent_tidptr, 2139 int __user *, child_tidptr, 2140 unsigned long, tls) 2141 #elif defined(CONFIG_CLONE_BACKWARDS3) 2142 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, 2143 int, stack_size, 2144 int __user *, parent_tidptr, 2145 int __user *, child_tidptr, 2146 unsigned long, tls) 2147 #else 2148 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 2149 int __user *, parent_tidptr, 2150 int __user *, child_tidptr, 2151 unsigned long, tls) 2152 #endif 2153 { 2154 return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls); 2155 } 2156 #endif 2157 2158 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data) 2159 { 2160 struct task_struct *leader, *parent, *child; 2161 int res; 2162 2163 read_lock(&tasklist_lock); 2164 leader = top = top->group_leader; 2165 down: 2166 for_each_thread(leader, parent) { 2167 list_for_each_entry(child, &parent->children, sibling) { 2168 res = visitor(child, data); 2169 if (res) { 2170 if (res < 0) 2171 goto out; 2172 leader = child; 2173 goto down; 2174 } 2175 up: 2176 ; 2177 } 2178 } 2179 2180 if (leader != top) { 2181 child = leader; 2182 parent = child->real_parent; 2183 leader = parent->group_leader; 2184 goto up; 2185 } 2186 out: 2187 read_unlock(&tasklist_lock); 2188 } 2189 2190 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 2191 #define ARCH_MIN_MMSTRUCT_ALIGN 0 2192 #endif 2193 2194 static void sighand_ctor(void *data) 2195 { 2196 struct sighand_struct *sighand = data; 2197 2198 spin_lock_init(&sighand->siglock); 2199 init_waitqueue_head(&sighand->signalfd_wqh); 2200 } 2201 2202 void __init proc_caches_init(void) 2203 { 2204 sighand_cachep = kmem_cache_create("sighand_cache", 2205 sizeof(struct sighand_struct), 0, 2206 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU| 2207 SLAB_ACCOUNT, sighand_ctor); 2208 signal_cachep = kmem_cache_create("signal_cache", 2209 sizeof(struct signal_struct), 0, 2210 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2211 NULL); 2212 files_cachep = kmem_cache_create("files_cache", 2213 sizeof(struct files_struct), 0, 2214 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2215 NULL); 2216 fs_cachep = kmem_cache_create("fs_cache", 2217 sizeof(struct fs_struct), 0, 2218 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2219 NULL); 2220 /* 2221 * FIXME! The "sizeof(struct mm_struct)" currently includes the 2222 * whole struct cpumask for the OFFSTACK case. We could change 2223 * this to *only* allocate as much of it as required by the 2224 * maximum number of CPU's we can ever have. The cpumask_allocation 2225 * is at the end of the structure, exactly for that reason. 2226 */ 2227 mm_cachep = kmem_cache_create("mm_struct", 2228 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 2229 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, 2230 NULL); 2231 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); 2232 mmap_init(); 2233 nsproxy_cache_init(); 2234 } 2235 2236 /* 2237 * Check constraints on flags passed to the unshare system call. 2238 */ 2239 static int check_unshare_flags(unsigned long unshare_flags) 2240 { 2241 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 2242 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 2243 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| 2244 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP)) 2245 return -EINVAL; 2246 /* 2247 * Not implemented, but pretend it works if there is nothing 2248 * to unshare. Note that unsharing the address space or the 2249 * signal handlers also need to unshare the signal queues (aka 2250 * CLONE_THREAD). 2251 */ 2252 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { 2253 if (!thread_group_empty(current)) 2254 return -EINVAL; 2255 } 2256 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) { 2257 if (atomic_read(¤t->sighand->count) > 1) 2258 return -EINVAL; 2259 } 2260 if (unshare_flags & CLONE_VM) { 2261 if (!current_is_single_threaded()) 2262 return -EINVAL; 2263 } 2264 2265 return 0; 2266 } 2267 2268 /* 2269 * Unshare the filesystem structure if it is being shared 2270 */ 2271 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 2272 { 2273 struct fs_struct *fs = current->fs; 2274 2275 if (!(unshare_flags & CLONE_FS) || !fs) 2276 return 0; 2277 2278 /* don't need lock here; in the worst case we'll do useless copy */ 2279 if (fs->users == 1) 2280 return 0; 2281 2282 *new_fsp = copy_fs_struct(fs); 2283 if (!*new_fsp) 2284 return -ENOMEM; 2285 2286 return 0; 2287 } 2288 2289 /* 2290 * Unshare file descriptor table if it is being shared 2291 */ 2292 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 2293 { 2294 struct files_struct *fd = current->files; 2295 int error = 0; 2296 2297 if ((unshare_flags & CLONE_FILES) && 2298 (fd && atomic_read(&fd->count) > 1)) { 2299 *new_fdp = dup_fd(fd, &error); 2300 if (!*new_fdp) 2301 return error; 2302 } 2303 2304 return 0; 2305 } 2306 2307 /* 2308 * unshare allows a process to 'unshare' part of the process 2309 * context which was originally shared using clone. copy_* 2310 * functions used by do_fork() cannot be used here directly 2311 * because they modify an inactive task_struct that is being 2312 * constructed. Here we are modifying the current, active, 2313 * task_struct. 2314 */ 2315 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) 2316 { 2317 struct fs_struct *fs, *new_fs = NULL; 2318 struct files_struct *fd, *new_fd = NULL; 2319 struct cred *new_cred = NULL; 2320 struct nsproxy *new_nsproxy = NULL; 2321 int do_sysvsem = 0; 2322 int err; 2323 2324 /* 2325 * If unsharing a user namespace must also unshare the thread group 2326 * and unshare the filesystem root and working directories. 2327 */ 2328 if (unshare_flags & CLONE_NEWUSER) 2329 unshare_flags |= CLONE_THREAD | CLONE_FS; 2330 /* 2331 * If unsharing vm, must also unshare signal handlers. 2332 */ 2333 if (unshare_flags & CLONE_VM) 2334 unshare_flags |= CLONE_SIGHAND; 2335 /* 2336 * If unsharing a signal handlers, must also unshare the signal queues. 2337 */ 2338 if (unshare_flags & CLONE_SIGHAND) 2339 unshare_flags |= CLONE_THREAD; 2340 /* 2341 * If unsharing namespace, must also unshare filesystem information. 2342 */ 2343 if (unshare_flags & CLONE_NEWNS) 2344 unshare_flags |= CLONE_FS; 2345 2346 err = check_unshare_flags(unshare_flags); 2347 if (err) 2348 goto bad_unshare_out; 2349 /* 2350 * CLONE_NEWIPC must also detach from the undolist: after switching 2351 * to a new ipc namespace, the semaphore arrays from the old 2352 * namespace are unreachable. 2353 */ 2354 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) 2355 do_sysvsem = 1; 2356 err = unshare_fs(unshare_flags, &new_fs); 2357 if (err) 2358 goto bad_unshare_out; 2359 err = unshare_fd(unshare_flags, &new_fd); 2360 if (err) 2361 goto bad_unshare_cleanup_fs; 2362 err = unshare_userns(unshare_flags, &new_cred); 2363 if (err) 2364 goto bad_unshare_cleanup_fd; 2365 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 2366 new_cred, new_fs); 2367 if (err) 2368 goto bad_unshare_cleanup_cred; 2369 2370 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { 2371 if (do_sysvsem) { 2372 /* 2373 * CLONE_SYSVSEM is equivalent to sys_exit(). 2374 */ 2375 exit_sem(current); 2376 } 2377 if (unshare_flags & CLONE_NEWIPC) { 2378 /* Orphan segments in old ns (see sem above). */ 2379 exit_shm(current); 2380 shm_init_task(current); 2381 } 2382 2383 if (new_nsproxy) 2384 switch_task_namespaces(current, new_nsproxy); 2385 2386 task_lock(current); 2387 2388 if (new_fs) { 2389 fs = current->fs; 2390 spin_lock(&fs->lock); 2391 current->fs = new_fs; 2392 if (--fs->users) 2393 new_fs = NULL; 2394 else 2395 new_fs = fs; 2396 spin_unlock(&fs->lock); 2397 } 2398 2399 if (new_fd) { 2400 fd = current->files; 2401 current->files = new_fd; 2402 new_fd = fd; 2403 } 2404 2405 task_unlock(current); 2406 2407 if (new_cred) { 2408 /* Install the new user namespace */ 2409 commit_creds(new_cred); 2410 new_cred = NULL; 2411 } 2412 } 2413 2414 perf_event_namespaces(current); 2415 2416 bad_unshare_cleanup_cred: 2417 if (new_cred) 2418 put_cred(new_cred); 2419 bad_unshare_cleanup_fd: 2420 if (new_fd) 2421 put_files_struct(new_fd); 2422 2423 bad_unshare_cleanup_fs: 2424 if (new_fs) 2425 free_fs_struct(new_fs); 2426 2427 bad_unshare_out: 2428 return err; 2429 } 2430 2431 /* 2432 * Helper to unshare the files of the current task. 2433 * We don't want to expose copy_files internals to 2434 * the exec layer of the kernel. 2435 */ 2436 2437 int unshare_files(struct files_struct **displaced) 2438 { 2439 struct task_struct *task = current; 2440 struct files_struct *copy = NULL; 2441 int error; 2442 2443 error = unshare_fd(CLONE_FILES, ©); 2444 if (error || !copy) { 2445 *displaced = NULL; 2446 return error; 2447 } 2448 *displaced = task->files; 2449 task_lock(task); 2450 task->files = copy; 2451 task_unlock(task); 2452 return 0; 2453 } 2454 2455 int sysctl_max_threads(struct ctl_table *table, int write, 2456 void __user *buffer, size_t *lenp, loff_t *ppos) 2457 { 2458 struct ctl_table t; 2459 int ret; 2460 int threads = max_threads; 2461 int min = MIN_THREADS; 2462 int max = MAX_THREADS; 2463 2464 t = *table; 2465 t.data = &threads; 2466 t.extra1 = &min; 2467 t.extra2 = &max; 2468 2469 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 2470 if (ret || !write) 2471 return ret; 2472 2473 set_max_threads(threads); 2474 2475 return 0; 2476 } 2477