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