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