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