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/mnt_namespace.h> 21 #include <linux/personality.h> 22 #include <linux/mempolicy.h> 23 #include <linux/sem.h> 24 #include <linux/file.h> 25 #include <linux/key.h> 26 #include <linux/binfmts.h> 27 #include <linux/mman.h> 28 #include <linux/fs.h> 29 #include <linux/nsproxy.h> 30 #include <linux/capability.h> 31 #include <linux/cpu.h> 32 #include <linux/cgroup.h> 33 #include <linux/security.h> 34 #include <linux/swap.h> 35 #include <linux/syscalls.h> 36 #include <linux/jiffies.h> 37 #include <linux/futex.h> 38 #include <linux/task_io_accounting_ops.h> 39 #include <linux/rcupdate.h> 40 #include <linux/ptrace.h> 41 #include <linux/mount.h> 42 #include <linux/audit.h> 43 #include <linux/profile.h> 44 #include <linux/rmap.h> 45 #include <linux/acct.h> 46 #include <linux/tsacct_kern.h> 47 #include <linux/cn_proc.h> 48 #include <linux/freezer.h> 49 #include <linux/delayacct.h> 50 #include <linux/taskstats_kern.h> 51 #include <linux/random.h> 52 #include <linux/tty.h> 53 #include <linux/proc_fs.h> 54 #include <linux/blkdev.h> 55 56 #include <asm/pgtable.h> 57 #include <asm/pgalloc.h> 58 #include <asm/uaccess.h> 59 #include <asm/mmu_context.h> 60 #include <asm/cacheflush.h> 61 #include <asm/tlbflush.h> 62 63 /* 64 * Protected counters by write_lock_irq(&tasklist_lock) 65 */ 66 unsigned long total_forks; /* Handle normal Linux uptimes. */ 67 int nr_threads; /* The idle threads do not count.. */ 68 69 int max_threads; /* tunable limit on nr_threads */ 70 71 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 72 73 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 74 75 int nr_processes(void) 76 { 77 int cpu; 78 int total = 0; 79 80 for_each_online_cpu(cpu) 81 total += per_cpu(process_counts, cpu); 82 83 return total; 84 } 85 86 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 87 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) 88 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) 89 static struct kmem_cache *task_struct_cachep; 90 #endif 91 92 /* SLAB cache for signal_struct structures (tsk->signal) */ 93 static struct kmem_cache *signal_cachep; 94 95 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 96 struct kmem_cache *sighand_cachep; 97 98 /* SLAB cache for files_struct structures (tsk->files) */ 99 struct kmem_cache *files_cachep; 100 101 /* SLAB cache for fs_struct structures (tsk->fs) */ 102 struct kmem_cache *fs_cachep; 103 104 /* SLAB cache for vm_area_struct structures */ 105 struct kmem_cache *vm_area_cachep; 106 107 /* SLAB cache for mm_struct structures (tsk->mm) */ 108 static struct kmem_cache *mm_cachep; 109 110 void free_task(struct task_struct *tsk) 111 { 112 prop_local_destroy_single(&tsk->dirties); 113 free_thread_info(tsk->stack); 114 rt_mutex_debug_task_free(tsk); 115 free_task_struct(tsk); 116 } 117 EXPORT_SYMBOL(free_task); 118 119 void __put_task_struct(struct task_struct *tsk) 120 { 121 WARN_ON(!tsk->exit_state); 122 WARN_ON(atomic_read(&tsk->usage)); 123 WARN_ON(tsk == current); 124 125 security_task_free(tsk); 126 free_uid(tsk->user); 127 put_group_info(tsk->group_info); 128 delayacct_tsk_free(tsk); 129 130 if (!profile_handoff_task(tsk)) 131 free_task(tsk); 132 } 133 134 void __init fork_init(unsigned long mempages) 135 { 136 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 137 #ifndef ARCH_MIN_TASKALIGN 138 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES 139 #endif 140 /* create a slab on which task_structs can be allocated */ 141 task_struct_cachep = 142 kmem_cache_create("task_struct", sizeof(struct task_struct), 143 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL); 144 #endif 145 146 /* 147 * The default maximum number of threads is set to a safe 148 * value: the thread structures can take up at most half 149 * of memory. 150 */ 151 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); 152 153 /* 154 * we need to allow at least 20 threads to boot a system 155 */ 156 if(max_threads < 20) 157 max_threads = 20; 158 159 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 160 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 161 init_task.signal->rlim[RLIMIT_SIGPENDING] = 162 init_task.signal->rlim[RLIMIT_NPROC]; 163 } 164 165 static struct task_struct *dup_task_struct(struct task_struct *orig) 166 { 167 struct task_struct *tsk; 168 struct thread_info *ti; 169 int err; 170 171 prepare_to_copy(orig); 172 173 tsk = alloc_task_struct(); 174 if (!tsk) 175 return NULL; 176 177 ti = alloc_thread_info(tsk); 178 if (!ti) { 179 free_task_struct(tsk); 180 return NULL; 181 } 182 183 *tsk = *orig; 184 tsk->stack = ti; 185 186 err = prop_local_init_single(&tsk->dirties); 187 if (err) { 188 free_thread_info(ti); 189 free_task_struct(tsk); 190 return NULL; 191 } 192 193 setup_thread_stack(tsk, orig); 194 195 #ifdef CONFIG_CC_STACKPROTECTOR 196 tsk->stack_canary = get_random_int(); 197 #endif 198 199 /* One for us, one for whoever does the "release_task()" (usually parent) */ 200 atomic_set(&tsk->usage,2); 201 atomic_set(&tsk->fs_excl, 0); 202 #ifdef CONFIG_BLK_DEV_IO_TRACE 203 tsk->btrace_seq = 0; 204 #endif 205 tsk->splice_pipe = NULL; 206 return tsk; 207 } 208 209 #ifdef CONFIG_MMU 210 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 211 { 212 struct vm_area_struct *mpnt, *tmp, **pprev; 213 struct rb_node **rb_link, *rb_parent; 214 int retval; 215 unsigned long charge; 216 struct mempolicy *pol; 217 218 down_write(&oldmm->mmap_sem); 219 flush_cache_dup_mm(oldmm); 220 /* 221 * Not linked in yet - no deadlock potential: 222 */ 223 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); 224 225 mm->locked_vm = 0; 226 mm->mmap = NULL; 227 mm->mmap_cache = NULL; 228 mm->free_area_cache = oldmm->mmap_base; 229 mm->cached_hole_size = ~0UL; 230 mm->map_count = 0; 231 cpus_clear(mm->cpu_vm_mask); 232 mm->mm_rb = RB_ROOT; 233 rb_link = &mm->mm_rb.rb_node; 234 rb_parent = NULL; 235 pprev = &mm->mmap; 236 237 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 238 struct file *file; 239 240 if (mpnt->vm_flags & VM_DONTCOPY) { 241 long pages = vma_pages(mpnt); 242 mm->total_vm -= pages; 243 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, 244 -pages); 245 continue; 246 } 247 charge = 0; 248 if (mpnt->vm_flags & VM_ACCOUNT) { 249 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; 250 if (security_vm_enough_memory(len)) 251 goto fail_nomem; 252 charge = len; 253 } 254 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 255 if (!tmp) 256 goto fail_nomem; 257 *tmp = *mpnt; 258 pol = mpol_copy(vma_policy(mpnt)); 259 retval = PTR_ERR(pol); 260 if (IS_ERR(pol)) 261 goto fail_nomem_policy; 262 vma_set_policy(tmp, pol); 263 tmp->vm_flags &= ~VM_LOCKED; 264 tmp->vm_mm = mm; 265 tmp->vm_next = NULL; 266 anon_vma_link(tmp); 267 file = tmp->vm_file; 268 if (file) { 269 struct inode *inode = file->f_path.dentry->d_inode; 270 get_file(file); 271 if (tmp->vm_flags & VM_DENYWRITE) 272 atomic_dec(&inode->i_writecount); 273 274 /* insert tmp into the share list, just after mpnt */ 275 spin_lock(&file->f_mapping->i_mmap_lock); 276 tmp->vm_truncate_count = mpnt->vm_truncate_count; 277 flush_dcache_mmap_lock(file->f_mapping); 278 vma_prio_tree_add(tmp, mpnt); 279 flush_dcache_mmap_unlock(file->f_mapping); 280 spin_unlock(&file->f_mapping->i_mmap_lock); 281 } 282 283 /* 284 * Link in the new vma and copy the page table entries. 285 */ 286 *pprev = tmp; 287 pprev = &tmp->vm_next; 288 289 __vma_link_rb(mm, tmp, rb_link, rb_parent); 290 rb_link = &tmp->vm_rb.rb_right; 291 rb_parent = &tmp->vm_rb; 292 293 mm->map_count++; 294 retval = copy_page_range(mm, oldmm, mpnt); 295 296 if (tmp->vm_ops && tmp->vm_ops->open) 297 tmp->vm_ops->open(tmp); 298 299 if (retval) 300 goto out; 301 } 302 /* a new mm has just been created */ 303 arch_dup_mmap(oldmm, mm); 304 retval = 0; 305 out: 306 up_write(&mm->mmap_sem); 307 flush_tlb_mm(oldmm); 308 up_write(&oldmm->mmap_sem); 309 return retval; 310 fail_nomem_policy: 311 kmem_cache_free(vm_area_cachep, tmp); 312 fail_nomem: 313 retval = -ENOMEM; 314 vm_unacct_memory(charge); 315 goto out; 316 } 317 318 static inline int mm_alloc_pgd(struct mm_struct * mm) 319 { 320 mm->pgd = pgd_alloc(mm); 321 if (unlikely(!mm->pgd)) 322 return -ENOMEM; 323 return 0; 324 } 325 326 static inline void mm_free_pgd(struct mm_struct * mm) 327 { 328 pgd_free(mm->pgd); 329 } 330 #else 331 #define dup_mmap(mm, oldmm) (0) 332 #define mm_alloc_pgd(mm) (0) 333 #define mm_free_pgd(mm) 334 #endif /* CONFIG_MMU */ 335 336 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 337 338 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 339 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 340 341 #include <linux/init_task.h> 342 343 static struct mm_struct * mm_init(struct mm_struct * mm) 344 { 345 atomic_set(&mm->mm_users, 1); 346 atomic_set(&mm->mm_count, 1); 347 init_rwsem(&mm->mmap_sem); 348 INIT_LIST_HEAD(&mm->mmlist); 349 mm->flags = (current->mm) ? current->mm->flags 350 : MMF_DUMP_FILTER_DEFAULT; 351 mm->core_waiters = 0; 352 mm->nr_ptes = 0; 353 set_mm_counter(mm, file_rss, 0); 354 set_mm_counter(mm, anon_rss, 0); 355 spin_lock_init(&mm->page_table_lock); 356 rwlock_init(&mm->ioctx_list_lock); 357 mm->ioctx_list = NULL; 358 mm->free_area_cache = TASK_UNMAPPED_BASE; 359 mm->cached_hole_size = ~0UL; 360 361 if (likely(!mm_alloc_pgd(mm))) { 362 mm->def_flags = 0; 363 return mm; 364 } 365 free_mm(mm); 366 return NULL; 367 } 368 369 /* 370 * Allocate and initialize an mm_struct. 371 */ 372 struct mm_struct * mm_alloc(void) 373 { 374 struct mm_struct * mm; 375 376 mm = allocate_mm(); 377 if (mm) { 378 memset(mm, 0, sizeof(*mm)); 379 mm = mm_init(mm); 380 } 381 return mm; 382 } 383 384 /* 385 * Called when the last reference to the mm 386 * is dropped: either by a lazy thread or by 387 * mmput. Free the page directory and the mm. 388 */ 389 void fastcall __mmdrop(struct mm_struct *mm) 390 { 391 BUG_ON(mm == &init_mm); 392 mm_free_pgd(mm); 393 destroy_context(mm); 394 free_mm(mm); 395 } 396 EXPORT_SYMBOL_GPL(__mmdrop); 397 398 /* 399 * Decrement the use count and release all resources for an mm. 400 */ 401 void mmput(struct mm_struct *mm) 402 { 403 might_sleep(); 404 405 if (atomic_dec_and_test(&mm->mm_users)) { 406 exit_aio(mm); 407 exit_mmap(mm); 408 if (!list_empty(&mm->mmlist)) { 409 spin_lock(&mmlist_lock); 410 list_del(&mm->mmlist); 411 spin_unlock(&mmlist_lock); 412 } 413 put_swap_token(mm); 414 mmdrop(mm); 415 } 416 } 417 EXPORT_SYMBOL_GPL(mmput); 418 419 /** 420 * get_task_mm - acquire a reference to the task's mm 421 * 422 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning 423 * this kernel workthread has transiently adopted a user mm with use_mm, 424 * to do its AIO) is not set and if so returns a reference to it, after 425 * bumping up the use count. User must release the mm via mmput() 426 * after use. Typically used by /proc and ptrace. 427 */ 428 struct mm_struct *get_task_mm(struct task_struct *task) 429 { 430 struct mm_struct *mm; 431 432 task_lock(task); 433 mm = task->mm; 434 if (mm) { 435 if (task->flags & PF_BORROWED_MM) 436 mm = NULL; 437 else 438 atomic_inc(&mm->mm_users); 439 } 440 task_unlock(task); 441 return mm; 442 } 443 EXPORT_SYMBOL_GPL(get_task_mm); 444 445 /* Please note the differences between mmput and mm_release. 446 * mmput is called whenever we stop holding onto a mm_struct, 447 * error success whatever. 448 * 449 * mm_release is called after a mm_struct has been removed 450 * from the current process. 451 * 452 * This difference is important for error handling, when we 453 * only half set up a mm_struct for a new process and need to restore 454 * the old one. Because we mmput the new mm_struct before 455 * restoring the old one. . . 456 * Eric Biederman 10 January 1998 457 */ 458 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 459 { 460 struct completion *vfork_done = tsk->vfork_done; 461 462 /* Get rid of any cached register state */ 463 deactivate_mm(tsk, mm); 464 465 /* notify parent sleeping on vfork() */ 466 if (vfork_done) { 467 tsk->vfork_done = NULL; 468 complete(vfork_done); 469 } 470 471 /* 472 * If we're exiting normally, clear a user-space tid field if 473 * requested. We leave this alone when dying by signal, to leave 474 * the value intact in a core dump, and to save the unnecessary 475 * trouble otherwise. Userland only wants this done for a sys_exit. 476 */ 477 if (tsk->clear_child_tid 478 && !(tsk->flags & PF_SIGNALED) 479 && atomic_read(&mm->mm_users) > 1) { 480 u32 __user * tidptr = tsk->clear_child_tid; 481 tsk->clear_child_tid = NULL; 482 483 /* 484 * We don't check the error code - if userspace has 485 * not set up a proper pointer then tough luck. 486 */ 487 put_user(0, tidptr); 488 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); 489 } 490 } 491 492 /* 493 * Allocate a new mm structure and copy contents from the 494 * mm structure of the passed in task structure. 495 */ 496 static struct mm_struct *dup_mm(struct task_struct *tsk) 497 { 498 struct mm_struct *mm, *oldmm = current->mm; 499 int err; 500 501 if (!oldmm) 502 return NULL; 503 504 mm = allocate_mm(); 505 if (!mm) 506 goto fail_nomem; 507 508 memcpy(mm, oldmm, sizeof(*mm)); 509 510 /* Initializing for Swap token stuff */ 511 mm->token_priority = 0; 512 mm->last_interval = 0; 513 514 if (!mm_init(mm)) 515 goto fail_nomem; 516 517 if (init_new_context(tsk, mm)) 518 goto fail_nocontext; 519 520 err = dup_mmap(mm, oldmm); 521 if (err) 522 goto free_pt; 523 524 mm->hiwater_rss = get_mm_rss(mm); 525 mm->hiwater_vm = mm->total_vm; 526 527 return mm; 528 529 free_pt: 530 mmput(mm); 531 532 fail_nomem: 533 return NULL; 534 535 fail_nocontext: 536 /* 537 * If init_new_context() failed, we cannot use mmput() to free the mm 538 * because it calls destroy_context() 539 */ 540 mm_free_pgd(mm); 541 free_mm(mm); 542 return NULL; 543 } 544 545 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) 546 { 547 struct mm_struct * mm, *oldmm; 548 int retval; 549 550 tsk->min_flt = tsk->maj_flt = 0; 551 tsk->nvcsw = tsk->nivcsw = 0; 552 553 tsk->mm = NULL; 554 tsk->active_mm = NULL; 555 556 /* 557 * Are we cloning a kernel thread? 558 * 559 * We need to steal a active VM for that.. 560 */ 561 oldmm = current->mm; 562 if (!oldmm) 563 return 0; 564 565 if (clone_flags & CLONE_VM) { 566 atomic_inc(&oldmm->mm_users); 567 mm = oldmm; 568 goto good_mm; 569 } 570 571 retval = -ENOMEM; 572 mm = dup_mm(tsk); 573 if (!mm) 574 goto fail_nomem; 575 576 good_mm: 577 /* Initializing for Swap token stuff */ 578 mm->token_priority = 0; 579 mm->last_interval = 0; 580 581 tsk->mm = mm; 582 tsk->active_mm = mm; 583 return 0; 584 585 fail_nomem: 586 return retval; 587 } 588 589 static struct fs_struct *__copy_fs_struct(struct fs_struct *old) 590 { 591 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); 592 /* We don't need to lock fs - think why ;-) */ 593 if (fs) { 594 atomic_set(&fs->count, 1); 595 rwlock_init(&fs->lock); 596 fs->umask = old->umask; 597 read_lock(&old->lock); 598 fs->rootmnt = mntget(old->rootmnt); 599 fs->root = dget(old->root); 600 fs->pwdmnt = mntget(old->pwdmnt); 601 fs->pwd = dget(old->pwd); 602 if (old->altroot) { 603 fs->altrootmnt = mntget(old->altrootmnt); 604 fs->altroot = dget(old->altroot); 605 } else { 606 fs->altrootmnt = NULL; 607 fs->altroot = NULL; 608 } 609 read_unlock(&old->lock); 610 } 611 return fs; 612 } 613 614 struct fs_struct *copy_fs_struct(struct fs_struct *old) 615 { 616 return __copy_fs_struct(old); 617 } 618 619 EXPORT_SYMBOL_GPL(copy_fs_struct); 620 621 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 622 { 623 if (clone_flags & CLONE_FS) { 624 atomic_inc(¤t->fs->count); 625 return 0; 626 } 627 tsk->fs = __copy_fs_struct(current->fs); 628 if (!tsk->fs) 629 return -ENOMEM; 630 return 0; 631 } 632 633 static int count_open_files(struct fdtable *fdt) 634 { 635 int size = fdt->max_fds; 636 int i; 637 638 /* Find the last open fd */ 639 for (i = size/(8*sizeof(long)); i > 0; ) { 640 if (fdt->open_fds->fds_bits[--i]) 641 break; 642 } 643 i = (i+1) * 8 * sizeof(long); 644 return i; 645 } 646 647 static struct files_struct *alloc_files(void) 648 { 649 struct files_struct *newf; 650 struct fdtable *fdt; 651 652 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); 653 if (!newf) 654 goto out; 655 656 atomic_set(&newf->count, 1); 657 658 spin_lock_init(&newf->file_lock); 659 newf->next_fd = 0; 660 fdt = &newf->fdtab; 661 fdt->max_fds = NR_OPEN_DEFAULT; 662 fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init; 663 fdt->open_fds = (fd_set *)&newf->open_fds_init; 664 fdt->fd = &newf->fd_array[0]; 665 INIT_RCU_HEAD(&fdt->rcu); 666 fdt->next = NULL; 667 rcu_assign_pointer(newf->fdt, fdt); 668 out: 669 return newf; 670 } 671 672 /* 673 * Allocate a new files structure and copy contents from the 674 * passed in files structure. 675 * errorp will be valid only when the returned files_struct is NULL. 676 */ 677 static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) 678 { 679 struct files_struct *newf; 680 struct file **old_fds, **new_fds; 681 int open_files, size, i; 682 struct fdtable *old_fdt, *new_fdt; 683 684 *errorp = -ENOMEM; 685 newf = alloc_files(); 686 if (!newf) 687 goto out; 688 689 spin_lock(&oldf->file_lock); 690 old_fdt = files_fdtable(oldf); 691 new_fdt = files_fdtable(newf); 692 open_files = count_open_files(old_fdt); 693 694 /* 695 * Check whether we need to allocate a larger fd array and fd set. 696 * Note: we're not a clone task, so the open count won't change. 697 */ 698 if (open_files > new_fdt->max_fds) { 699 new_fdt->max_fds = 0; 700 spin_unlock(&oldf->file_lock); 701 spin_lock(&newf->file_lock); 702 *errorp = expand_files(newf, open_files-1); 703 spin_unlock(&newf->file_lock); 704 if (*errorp < 0) 705 goto out_release; 706 new_fdt = files_fdtable(newf); 707 /* 708 * Reacquire the oldf lock and a pointer to its fd table 709 * who knows it may have a new bigger fd table. We need 710 * the latest pointer. 711 */ 712 spin_lock(&oldf->file_lock); 713 old_fdt = files_fdtable(oldf); 714 } 715 716 old_fds = old_fdt->fd; 717 new_fds = new_fdt->fd; 718 719 memcpy(new_fdt->open_fds->fds_bits, 720 old_fdt->open_fds->fds_bits, open_files/8); 721 memcpy(new_fdt->close_on_exec->fds_bits, 722 old_fdt->close_on_exec->fds_bits, open_files/8); 723 724 for (i = open_files; i != 0; i--) { 725 struct file *f = *old_fds++; 726 if (f) { 727 get_file(f); 728 } else { 729 /* 730 * The fd may be claimed in the fd bitmap but not yet 731 * instantiated in the files array if a sibling thread 732 * is partway through open(). So make sure that this 733 * fd is available to the new process. 734 */ 735 FD_CLR(open_files - i, new_fdt->open_fds); 736 } 737 rcu_assign_pointer(*new_fds++, f); 738 } 739 spin_unlock(&oldf->file_lock); 740 741 /* compute the remainder to be cleared */ 742 size = (new_fdt->max_fds - open_files) * sizeof(struct file *); 743 744 /* This is long word aligned thus could use a optimized version */ 745 memset(new_fds, 0, size); 746 747 if (new_fdt->max_fds > open_files) { 748 int left = (new_fdt->max_fds-open_files)/8; 749 int start = open_files / (8 * sizeof(unsigned long)); 750 751 memset(&new_fdt->open_fds->fds_bits[start], 0, left); 752 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); 753 } 754 755 return newf; 756 757 out_release: 758 kmem_cache_free(files_cachep, newf); 759 out: 760 return NULL; 761 } 762 763 static int copy_files(unsigned long clone_flags, struct task_struct * tsk) 764 { 765 struct files_struct *oldf, *newf; 766 int error = 0; 767 768 /* 769 * A background process may not have any files ... 770 */ 771 oldf = current->files; 772 if (!oldf) 773 goto out; 774 775 if (clone_flags & CLONE_FILES) { 776 atomic_inc(&oldf->count); 777 goto out; 778 } 779 780 /* 781 * Note: we may be using current for both targets (See exec.c) 782 * This works because we cache current->files (old) as oldf. Don't 783 * break this. 784 */ 785 tsk->files = NULL; 786 newf = dup_fd(oldf, &error); 787 if (!newf) 788 goto out; 789 790 tsk->files = newf; 791 error = 0; 792 out: 793 return error; 794 } 795 796 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 797 { 798 #ifdef CONFIG_BLOCK 799 struct io_context *ioc = current->io_context; 800 801 if (!ioc) 802 return 0; 803 /* 804 * Share io context with parent, if CLONE_IO is set 805 */ 806 if (clone_flags & CLONE_IO) { 807 tsk->io_context = ioc_task_link(ioc); 808 if (unlikely(!tsk->io_context)) 809 return -ENOMEM; 810 } else if (ioprio_valid(ioc->ioprio)) { 811 tsk->io_context = alloc_io_context(GFP_KERNEL, -1); 812 if (unlikely(!tsk->io_context)) 813 return -ENOMEM; 814 815 tsk->io_context->ioprio = ioc->ioprio; 816 } 817 #endif 818 return 0; 819 } 820 821 /* 822 * Helper to unshare the files of the current task. 823 * We don't want to expose copy_files internals to 824 * the exec layer of the kernel. 825 */ 826 827 int unshare_files(void) 828 { 829 struct files_struct *files = current->files; 830 int rc; 831 832 BUG_ON(!files); 833 834 /* This can race but the race causes us to copy when we don't 835 need to and drop the copy */ 836 if(atomic_read(&files->count) == 1) 837 { 838 atomic_inc(&files->count); 839 return 0; 840 } 841 rc = copy_files(0, current); 842 if(rc) 843 current->files = files; 844 return rc; 845 } 846 847 EXPORT_SYMBOL(unshare_files); 848 849 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 850 { 851 struct sighand_struct *sig; 852 853 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { 854 atomic_inc(¤t->sighand->count); 855 return 0; 856 } 857 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 858 rcu_assign_pointer(tsk->sighand, sig); 859 if (!sig) 860 return -ENOMEM; 861 atomic_set(&sig->count, 1); 862 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 863 return 0; 864 } 865 866 void __cleanup_sighand(struct sighand_struct *sighand) 867 { 868 if (atomic_dec_and_test(&sighand->count)) 869 kmem_cache_free(sighand_cachep, sighand); 870 } 871 872 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 873 { 874 struct signal_struct *sig; 875 int ret; 876 877 if (clone_flags & CLONE_THREAD) { 878 atomic_inc(¤t->signal->count); 879 atomic_inc(¤t->signal->live); 880 return 0; 881 } 882 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); 883 tsk->signal = sig; 884 if (!sig) 885 return -ENOMEM; 886 887 ret = copy_thread_group_keys(tsk); 888 if (ret < 0) { 889 kmem_cache_free(signal_cachep, sig); 890 return ret; 891 } 892 893 atomic_set(&sig->count, 1); 894 atomic_set(&sig->live, 1); 895 init_waitqueue_head(&sig->wait_chldexit); 896 sig->flags = 0; 897 sig->group_exit_code = 0; 898 sig->group_exit_task = NULL; 899 sig->group_stop_count = 0; 900 sig->curr_target = NULL; 901 init_sigpending(&sig->shared_pending); 902 INIT_LIST_HEAD(&sig->posix_timers); 903 904 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 905 sig->it_real_incr.tv64 = 0; 906 sig->real_timer.function = it_real_fn; 907 sig->tsk = tsk; 908 909 sig->it_virt_expires = cputime_zero; 910 sig->it_virt_incr = cputime_zero; 911 sig->it_prof_expires = cputime_zero; 912 sig->it_prof_incr = cputime_zero; 913 914 sig->leader = 0; /* session leadership doesn't inherit */ 915 sig->tty_old_pgrp = NULL; 916 917 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; 918 sig->gtime = cputime_zero; 919 sig->cgtime = cputime_zero; 920 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; 921 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; 922 sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0; 923 sig->sum_sched_runtime = 0; 924 INIT_LIST_HEAD(&sig->cpu_timers[0]); 925 INIT_LIST_HEAD(&sig->cpu_timers[1]); 926 INIT_LIST_HEAD(&sig->cpu_timers[2]); 927 taskstats_tgid_init(sig); 928 929 task_lock(current->group_leader); 930 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 931 task_unlock(current->group_leader); 932 933 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { 934 /* 935 * New sole thread in the process gets an expiry time 936 * of the whole CPU time limit. 937 */ 938 tsk->it_prof_expires = 939 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); 940 } 941 acct_init_pacct(&sig->pacct); 942 943 tty_audit_fork(sig); 944 945 return 0; 946 } 947 948 void __cleanup_signal(struct signal_struct *sig) 949 { 950 exit_thread_group_keys(sig); 951 kmem_cache_free(signal_cachep, sig); 952 } 953 954 static void cleanup_signal(struct task_struct *tsk) 955 { 956 struct signal_struct *sig = tsk->signal; 957 958 atomic_dec(&sig->live); 959 960 if (atomic_dec_and_test(&sig->count)) 961 __cleanup_signal(sig); 962 } 963 964 static void copy_flags(unsigned long clone_flags, struct task_struct *p) 965 { 966 unsigned long new_flags = p->flags; 967 968 new_flags &= ~PF_SUPERPRIV; 969 new_flags |= PF_FORKNOEXEC; 970 if (!(clone_flags & CLONE_PTRACE)) 971 p->ptrace = 0; 972 p->flags = new_flags; 973 clear_freeze_flag(p); 974 } 975 976 asmlinkage long sys_set_tid_address(int __user *tidptr) 977 { 978 current->clear_child_tid = tidptr; 979 980 return task_pid_vnr(current); 981 } 982 983 static void rt_mutex_init_task(struct task_struct *p) 984 { 985 spin_lock_init(&p->pi_lock); 986 #ifdef CONFIG_RT_MUTEXES 987 plist_head_init(&p->pi_waiters, &p->pi_lock); 988 p->pi_blocked_on = NULL; 989 #endif 990 } 991 992 /* 993 * This creates a new process as a copy of the old one, 994 * but does not actually start it yet. 995 * 996 * It copies the registers, and all the appropriate 997 * parts of the process environment (as per the clone 998 * flags). The actual kick-off is left to the caller. 999 */ 1000 static struct task_struct *copy_process(unsigned long clone_flags, 1001 unsigned long stack_start, 1002 struct pt_regs *regs, 1003 unsigned long stack_size, 1004 int __user *child_tidptr, 1005 struct pid *pid) 1006 { 1007 int retval; 1008 struct task_struct *p; 1009 int cgroup_callbacks_done = 0; 1010 1011 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1012 return ERR_PTR(-EINVAL); 1013 1014 /* 1015 * Thread groups must share signals as well, and detached threads 1016 * can only be started up within the thread group. 1017 */ 1018 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1019 return ERR_PTR(-EINVAL); 1020 1021 /* 1022 * Shared signal handlers imply shared VM. By way of the above, 1023 * thread groups also imply shared VM. Blocking this case allows 1024 * for various simplifications in other code. 1025 */ 1026 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1027 return ERR_PTR(-EINVAL); 1028 1029 retval = security_task_create(clone_flags); 1030 if (retval) 1031 goto fork_out; 1032 1033 retval = -ENOMEM; 1034 p = dup_task_struct(current); 1035 if (!p) 1036 goto fork_out; 1037 1038 rt_mutex_init_task(p); 1039 1040 #ifdef CONFIG_TRACE_IRQFLAGS 1041 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 1042 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1043 #endif 1044 retval = -EAGAIN; 1045 if (atomic_read(&p->user->processes) >= 1046 p->signal->rlim[RLIMIT_NPROC].rlim_cur) { 1047 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && 1048 p->user != current->nsproxy->user_ns->root_user) 1049 goto bad_fork_free; 1050 } 1051 1052 atomic_inc(&p->user->__count); 1053 atomic_inc(&p->user->processes); 1054 get_group_info(p->group_info); 1055 1056 /* 1057 * If multiple threads are within copy_process(), then this check 1058 * triggers too late. This doesn't hurt, the check is only there 1059 * to stop root fork bombs. 1060 */ 1061 if (nr_threads >= max_threads) 1062 goto bad_fork_cleanup_count; 1063 1064 if (!try_module_get(task_thread_info(p)->exec_domain->module)) 1065 goto bad_fork_cleanup_count; 1066 1067 if (p->binfmt && !try_module_get(p->binfmt->module)) 1068 goto bad_fork_cleanup_put_domain; 1069 1070 p->did_exec = 0; 1071 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1072 copy_flags(clone_flags, p); 1073 INIT_LIST_HEAD(&p->children); 1074 INIT_LIST_HEAD(&p->sibling); 1075 #ifdef CONFIG_PREEMPT_RCU 1076 p->rcu_read_lock_nesting = 0; 1077 p->rcu_flipctr_idx = 0; 1078 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 1079 p->vfork_done = NULL; 1080 spin_lock_init(&p->alloc_lock); 1081 1082 clear_tsk_thread_flag(p, TIF_SIGPENDING); 1083 init_sigpending(&p->pending); 1084 1085 p->utime = cputime_zero; 1086 p->stime = cputime_zero; 1087 p->gtime = cputime_zero; 1088 p->utimescaled = cputime_zero; 1089 p->stimescaled = cputime_zero; 1090 p->prev_utime = cputime_zero; 1091 p->prev_stime = cputime_zero; 1092 1093 #ifdef CONFIG_DETECT_SOFTLOCKUP 1094 p->last_switch_count = 0; 1095 p->last_switch_timestamp = 0; 1096 #endif 1097 1098 #ifdef CONFIG_TASK_XACCT 1099 p->rchar = 0; /* I/O counter: bytes read */ 1100 p->wchar = 0; /* I/O counter: bytes written */ 1101 p->syscr = 0; /* I/O counter: read syscalls */ 1102 p->syscw = 0; /* I/O counter: write syscalls */ 1103 #endif 1104 task_io_accounting_init(p); 1105 acct_clear_integrals(p); 1106 1107 p->it_virt_expires = cputime_zero; 1108 p->it_prof_expires = cputime_zero; 1109 p->it_sched_expires = 0; 1110 INIT_LIST_HEAD(&p->cpu_timers[0]); 1111 INIT_LIST_HEAD(&p->cpu_timers[1]); 1112 INIT_LIST_HEAD(&p->cpu_timers[2]); 1113 1114 p->lock_depth = -1; /* -1 = no lock */ 1115 do_posix_clock_monotonic_gettime(&p->start_time); 1116 p->real_start_time = p->start_time; 1117 monotonic_to_bootbased(&p->real_start_time); 1118 #ifdef CONFIG_SECURITY 1119 p->security = NULL; 1120 #endif 1121 p->io_context = NULL; 1122 p->audit_context = NULL; 1123 cgroup_fork(p); 1124 #ifdef CONFIG_NUMA 1125 p->mempolicy = mpol_copy(p->mempolicy); 1126 if (IS_ERR(p->mempolicy)) { 1127 retval = PTR_ERR(p->mempolicy); 1128 p->mempolicy = NULL; 1129 goto bad_fork_cleanup_cgroup; 1130 } 1131 mpol_fix_fork_child_flag(p); 1132 #endif 1133 #ifdef CONFIG_TRACE_IRQFLAGS 1134 p->irq_events = 0; 1135 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1136 p->hardirqs_enabled = 1; 1137 #else 1138 p->hardirqs_enabled = 0; 1139 #endif 1140 p->hardirq_enable_ip = 0; 1141 p->hardirq_enable_event = 0; 1142 p->hardirq_disable_ip = _THIS_IP_; 1143 p->hardirq_disable_event = 0; 1144 p->softirqs_enabled = 1; 1145 p->softirq_enable_ip = _THIS_IP_; 1146 p->softirq_enable_event = 0; 1147 p->softirq_disable_ip = 0; 1148 p->softirq_disable_event = 0; 1149 p->hardirq_context = 0; 1150 p->softirq_context = 0; 1151 #endif 1152 #ifdef CONFIG_LOCKDEP 1153 p->lockdep_depth = 0; /* no locks held yet */ 1154 p->curr_chain_key = 0; 1155 p->lockdep_recursion = 0; 1156 #endif 1157 1158 #ifdef CONFIG_DEBUG_MUTEXES 1159 p->blocked_on = NULL; /* not blocked yet */ 1160 #endif 1161 1162 /* Perform scheduler related setup. Assign this task to a CPU. */ 1163 sched_fork(p, clone_flags); 1164 1165 if ((retval = security_task_alloc(p))) 1166 goto bad_fork_cleanup_policy; 1167 if ((retval = audit_alloc(p))) 1168 goto bad_fork_cleanup_security; 1169 /* copy all the process information */ 1170 if ((retval = copy_semundo(clone_flags, p))) 1171 goto bad_fork_cleanup_audit; 1172 if ((retval = copy_files(clone_flags, p))) 1173 goto bad_fork_cleanup_semundo; 1174 if ((retval = copy_fs(clone_flags, p))) 1175 goto bad_fork_cleanup_files; 1176 if ((retval = copy_sighand(clone_flags, p))) 1177 goto bad_fork_cleanup_fs; 1178 if ((retval = copy_signal(clone_flags, p))) 1179 goto bad_fork_cleanup_sighand; 1180 if ((retval = copy_mm(clone_flags, p))) 1181 goto bad_fork_cleanup_signal; 1182 if ((retval = copy_keys(clone_flags, p))) 1183 goto bad_fork_cleanup_mm; 1184 if ((retval = copy_namespaces(clone_flags, p))) 1185 goto bad_fork_cleanup_keys; 1186 if ((retval = copy_io(clone_flags, p))) 1187 goto bad_fork_cleanup_namespaces; 1188 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); 1189 if (retval) 1190 goto bad_fork_cleanup_io; 1191 1192 if (pid != &init_struct_pid) { 1193 retval = -ENOMEM; 1194 pid = alloc_pid(task_active_pid_ns(p)); 1195 if (!pid) 1196 goto bad_fork_cleanup_io; 1197 1198 if (clone_flags & CLONE_NEWPID) { 1199 retval = pid_ns_prepare_proc(task_active_pid_ns(p)); 1200 if (retval < 0) 1201 goto bad_fork_free_pid; 1202 } 1203 } 1204 1205 p->pid = pid_nr(pid); 1206 p->tgid = p->pid; 1207 if (clone_flags & CLONE_THREAD) 1208 p->tgid = current->tgid; 1209 1210 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1211 /* 1212 * Clear TID on mm_release()? 1213 */ 1214 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; 1215 #ifdef CONFIG_FUTEX 1216 p->robust_list = NULL; 1217 #ifdef CONFIG_COMPAT 1218 p->compat_robust_list = NULL; 1219 #endif 1220 INIT_LIST_HEAD(&p->pi_state_list); 1221 p->pi_state_cache = NULL; 1222 #endif 1223 /* 1224 * sigaltstack should be cleared when sharing the same VM 1225 */ 1226 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1227 p->sas_ss_sp = p->sas_ss_size = 0; 1228 1229 /* 1230 * Syscall tracing should be turned off in the child regardless 1231 * of CLONE_PTRACE. 1232 */ 1233 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1234 #ifdef TIF_SYSCALL_EMU 1235 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1236 #endif 1237 clear_all_latency_tracing(p); 1238 1239 /* Our parent execution domain becomes current domain 1240 These must match for thread signalling to apply */ 1241 p->parent_exec_id = p->self_exec_id; 1242 1243 /* ok, now we should be set up.. */ 1244 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); 1245 p->pdeath_signal = 0; 1246 p->exit_state = 0; 1247 1248 /* 1249 * Ok, make it visible to the rest of the system. 1250 * We dont wake it up yet. 1251 */ 1252 p->group_leader = p; 1253 INIT_LIST_HEAD(&p->thread_group); 1254 INIT_LIST_HEAD(&p->ptrace_children); 1255 INIT_LIST_HEAD(&p->ptrace_list); 1256 1257 /* Now that the task is set up, run cgroup callbacks if 1258 * necessary. We need to run them before the task is visible 1259 * on the tasklist. */ 1260 cgroup_fork_callbacks(p); 1261 cgroup_callbacks_done = 1; 1262 1263 /* Need tasklist lock for parent etc handling! */ 1264 write_lock_irq(&tasklist_lock); 1265 1266 /* 1267 * The task hasn't been attached yet, so its cpus_allowed mask will 1268 * not be changed, nor will its assigned CPU. 1269 * 1270 * The cpus_allowed mask of the parent may have changed after it was 1271 * copied first time - so re-copy it here, then check the child's CPU 1272 * to ensure it is on a valid CPU (and if not, just force it back to 1273 * parent's CPU). This avoids alot of nasty races. 1274 */ 1275 p->cpus_allowed = current->cpus_allowed; 1276 p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed; 1277 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) || 1278 !cpu_online(task_cpu(p)))) 1279 set_task_cpu(p, smp_processor_id()); 1280 1281 /* CLONE_PARENT re-uses the old parent */ 1282 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) 1283 p->real_parent = current->real_parent; 1284 else 1285 p->real_parent = current; 1286 p->parent = p->real_parent; 1287 1288 spin_lock(¤t->sighand->siglock); 1289 1290 /* 1291 * Process group and session signals need to be delivered to just the 1292 * parent before the fork or both the parent and the child after the 1293 * fork. Restart if a signal comes in before we add the new process to 1294 * it's process group. 1295 * A fatal signal pending means that current will exit, so the new 1296 * thread can't slip out of an OOM kill (or normal SIGKILL). 1297 */ 1298 recalc_sigpending(); 1299 if (signal_pending(current)) { 1300 spin_unlock(¤t->sighand->siglock); 1301 write_unlock_irq(&tasklist_lock); 1302 retval = -ERESTARTNOINTR; 1303 goto bad_fork_free_pid; 1304 } 1305 1306 if (clone_flags & CLONE_THREAD) { 1307 p->group_leader = current->group_leader; 1308 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); 1309 1310 if (!cputime_eq(current->signal->it_virt_expires, 1311 cputime_zero) || 1312 !cputime_eq(current->signal->it_prof_expires, 1313 cputime_zero) || 1314 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || 1315 !list_empty(¤t->signal->cpu_timers[0]) || 1316 !list_empty(¤t->signal->cpu_timers[1]) || 1317 !list_empty(¤t->signal->cpu_timers[2])) { 1318 /* 1319 * Have child wake up on its first tick to check 1320 * for process CPU timers. 1321 */ 1322 p->it_prof_expires = jiffies_to_cputime(1); 1323 } 1324 } 1325 1326 if (likely(p->pid)) { 1327 add_parent(p); 1328 if (unlikely(p->ptrace & PT_PTRACED)) 1329 __ptrace_link(p, current->parent); 1330 1331 if (thread_group_leader(p)) { 1332 if (clone_flags & CLONE_NEWPID) 1333 p->nsproxy->pid_ns->child_reaper = p; 1334 1335 p->signal->tty = current->signal->tty; 1336 set_task_pgrp(p, task_pgrp_nr(current)); 1337 set_task_session(p, task_session_nr(current)); 1338 attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); 1339 attach_pid(p, PIDTYPE_SID, task_session(current)); 1340 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1341 __get_cpu_var(process_counts)++; 1342 } 1343 attach_pid(p, PIDTYPE_PID, pid); 1344 nr_threads++; 1345 } 1346 1347 total_forks++; 1348 spin_unlock(¤t->sighand->siglock); 1349 write_unlock_irq(&tasklist_lock); 1350 proc_fork_connector(p); 1351 cgroup_post_fork(p); 1352 return p; 1353 1354 bad_fork_free_pid: 1355 if (pid != &init_struct_pid) 1356 free_pid(pid); 1357 bad_fork_cleanup_io: 1358 put_io_context(p->io_context); 1359 bad_fork_cleanup_namespaces: 1360 exit_task_namespaces(p); 1361 bad_fork_cleanup_keys: 1362 exit_keys(p); 1363 bad_fork_cleanup_mm: 1364 if (p->mm) 1365 mmput(p->mm); 1366 bad_fork_cleanup_signal: 1367 cleanup_signal(p); 1368 bad_fork_cleanup_sighand: 1369 __cleanup_sighand(p->sighand); 1370 bad_fork_cleanup_fs: 1371 exit_fs(p); /* blocking */ 1372 bad_fork_cleanup_files: 1373 exit_files(p); /* blocking */ 1374 bad_fork_cleanup_semundo: 1375 exit_sem(p); 1376 bad_fork_cleanup_audit: 1377 audit_free(p); 1378 bad_fork_cleanup_security: 1379 security_task_free(p); 1380 bad_fork_cleanup_policy: 1381 #ifdef CONFIG_NUMA 1382 mpol_free(p->mempolicy); 1383 bad_fork_cleanup_cgroup: 1384 #endif 1385 cgroup_exit(p, cgroup_callbacks_done); 1386 delayacct_tsk_free(p); 1387 if (p->binfmt) 1388 module_put(p->binfmt->module); 1389 bad_fork_cleanup_put_domain: 1390 module_put(task_thread_info(p)->exec_domain->module); 1391 bad_fork_cleanup_count: 1392 put_group_info(p->group_info); 1393 atomic_dec(&p->user->processes); 1394 free_uid(p->user); 1395 bad_fork_free: 1396 free_task(p); 1397 fork_out: 1398 return ERR_PTR(retval); 1399 } 1400 1401 noinline struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs) 1402 { 1403 memset(regs, 0, sizeof(struct pt_regs)); 1404 return regs; 1405 } 1406 1407 struct task_struct * __cpuinit fork_idle(int cpu) 1408 { 1409 struct task_struct *task; 1410 struct pt_regs regs; 1411 1412 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, 1413 &init_struct_pid); 1414 if (!IS_ERR(task)) 1415 init_idle(task, cpu); 1416 1417 return task; 1418 } 1419 1420 static int fork_traceflag(unsigned clone_flags) 1421 { 1422 if (clone_flags & CLONE_UNTRACED) 1423 return 0; 1424 else if (clone_flags & CLONE_VFORK) { 1425 if (current->ptrace & PT_TRACE_VFORK) 1426 return PTRACE_EVENT_VFORK; 1427 } else if ((clone_flags & CSIGNAL) != SIGCHLD) { 1428 if (current->ptrace & PT_TRACE_CLONE) 1429 return PTRACE_EVENT_CLONE; 1430 } else if (current->ptrace & PT_TRACE_FORK) 1431 return PTRACE_EVENT_FORK; 1432 1433 return 0; 1434 } 1435 1436 /* 1437 * Ok, this is the main fork-routine. 1438 * 1439 * It copies the process, and if successful kick-starts 1440 * it and waits for it to finish using the VM if required. 1441 */ 1442 long do_fork(unsigned long clone_flags, 1443 unsigned long stack_start, 1444 struct pt_regs *regs, 1445 unsigned long stack_size, 1446 int __user *parent_tidptr, 1447 int __user *child_tidptr) 1448 { 1449 struct task_struct *p; 1450 int trace = 0; 1451 long nr; 1452 1453 if (unlikely(current->ptrace)) { 1454 trace = fork_traceflag (clone_flags); 1455 if (trace) 1456 clone_flags |= CLONE_PTRACE; 1457 } 1458 1459 p = copy_process(clone_flags, stack_start, regs, stack_size, 1460 child_tidptr, NULL); 1461 /* 1462 * Do this prior waking up the new thread - the thread pointer 1463 * might get invalid after that point, if the thread exits quickly. 1464 */ 1465 if (!IS_ERR(p)) { 1466 struct completion vfork; 1467 1468 /* 1469 * this is enough to call pid_nr_ns here, but this if 1470 * improves optimisation of regular fork() 1471 */ 1472 nr = (clone_flags & CLONE_NEWPID) ? 1473 task_pid_nr_ns(p, current->nsproxy->pid_ns) : 1474 task_pid_vnr(p); 1475 1476 if (clone_flags & CLONE_PARENT_SETTID) 1477 put_user(nr, parent_tidptr); 1478 1479 if (clone_flags & CLONE_VFORK) { 1480 p->vfork_done = &vfork; 1481 init_completion(&vfork); 1482 } 1483 1484 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { 1485 /* 1486 * We'll start up with an immediate SIGSTOP. 1487 */ 1488 sigaddset(&p->pending.signal, SIGSTOP); 1489 set_tsk_thread_flag(p, TIF_SIGPENDING); 1490 } 1491 1492 if (!(clone_flags & CLONE_STOPPED)) 1493 wake_up_new_task(p, clone_flags); 1494 else 1495 p->state = TASK_STOPPED; 1496 1497 if (unlikely (trace)) { 1498 current->ptrace_message = nr; 1499 ptrace_notify ((trace << 8) | SIGTRAP); 1500 } 1501 1502 if (clone_flags & CLONE_VFORK) { 1503 freezer_do_not_count(); 1504 wait_for_completion(&vfork); 1505 freezer_count(); 1506 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) { 1507 current->ptrace_message = nr; 1508 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); 1509 } 1510 } 1511 } else { 1512 nr = PTR_ERR(p); 1513 } 1514 return nr; 1515 } 1516 1517 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 1518 #define ARCH_MIN_MMSTRUCT_ALIGN 0 1519 #endif 1520 1521 static void sighand_ctor(struct kmem_cache *cachep, void *data) 1522 { 1523 struct sighand_struct *sighand = data; 1524 1525 spin_lock_init(&sighand->siglock); 1526 init_waitqueue_head(&sighand->signalfd_wqh); 1527 } 1528 1529 void __init proc_caches_init(void) 1530 { 1531 sighand_cachep = kmem_cache_create("sighand_cache", 1532 sizeof(struct sighand_struct), 0, 1533 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, 1534 sighand_ctor); 1535 signal_cachep = kmem_cache_create("signal_cache", 1536 sizeof(struct signal_struct), 0, 1537 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1538 files_cachep = kmem_cache_create("files_cache", 1539 sizeof(struct files_struct), 0, 1540 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1541 fs_cachep = kmem_cache_create("fs_cache", 1542 sizeof(struct fs_struct), 0, 1543 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1544 vm_area_cachep = kmem_cache_create("vm_area_struct", 1545 sizeof(struct vm_area_struct), 0, 1546 SLAB_PANIC, NULL); 1547 mm_cachep = kmem_cache_create("mm_struct", 1548 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 1549 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1550 } 1551 1552 /* 1553 * Check constraints on flags passed to the unshare system call and 1554 * force unsharing of additional process context as appropriate. 1555 */ 1556 static void check_unshare_flags(unsigned long *flags_ptr) 1557 { 1558 /* 1559 * If unsharing a thread from a thread group, must also 1560 * unshare vm. 1561 */ 1562 if (*flags_ptr & CLONE_THREAD) 1563 *flags_ptr |= CLONE_VM; 1564 1565 /* 1566 * If unsharing vm, must also unshare signal handlers. 1567 */ 1568 if (*flags_ptr & CLONE_VM) 1569 *flags_ptr |= CLONE_SIGHAND; 1570 1571 /* 1572 * If unsharing signal handlers and the task was created 1573 * using CLONE_THREAD, then must unshare the thread 1574 */ 1575 if ((*flags_ptr & CLONE_SIGHAND) && 1576 (atomic_read(¤t->signal->count) > 1)) 1577 *flags_ptr |= CLONE_THREAD; 1578 1579 /* 1580 * If unsharing namespace, must also unshare filesystem information. 1581 */ 1582 if (*flags_ptr & CLONE_NEWNS) 1583 *flags_ptr |= CLONE_FS; 1584 } 1585 1586 /* 1587 * Unsharing of tasks created with CLONE_THREAD is not supported yet 1588 */ 1589 static int unshare_thread(unsigned long unshare_flags) 1590 { 1591 if (unshare_flags & CLONE_THREAD) 1592 return -EINVAL; 1593 1594 return 0; 1595 } 1596 1597 /* 1598 * Unshare the filesystem structure if it is being shared 1599 */ 1600 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 1601 { 1602 struct fs_struct *fs = current->fs; 1603 1604 if ((unshare_flags & CLONE_FS) && 1605 (fs && atomic_read(&fs->count) > 1)) { 1606 *new_fsp = __copy_fs_struct(current->fs); 1607 if (!*new_fsp) 1608 return -ENOMEM; 1609 } 1610 1611 return 0; 1612 } 1613 1614 /* 1615 * Unsharing of sighand is not supported yet 1616 */ 1617 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) 1618 { 1619 struct sighand_struct *sigh = current->sighand; 1620 1621 if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) 1622 return -EINVAL; 1623 else 1624 return 0; 1625 } 1626 1627 /* 1628 * Unshare vm if it is being shared 1629 */ 1630 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) 1631 { 1632 struct mm_struct *mm = current->mm; 1633 1634 if ((unshare_flags & CLONE_VM) && 1635 (mm && atomic_read(&mm->mm_users) > 1)) { 1636 return -EINVAL; 1637 } 1638 1639 return 0; 1640 } 1641 1642 /* 1643 * Unshare file descriptor table if it is being shared 1644 */ 1645 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 1646 { 1647 struct files_struct *fd = current->files; 1648 int error = 0; 1649 1650 if ((unshare_flags & CLONE_FILES) && 1651 (fd && atomic_read(&fd->count) > 1)) { 1652 *new_fdp = dup_fd(fd, &error); 1653 if (!*new_fdp) 1654 return error; 1655 } 1656 1657 return 0; 1658 } 1659 1660 /* 1661 * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not 1662 * supported yet 1663 */ 1664 static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp) 1665 { 1666 if (unshare_flags & CLONE_SYSVSEM) 1667 return -EINVAL; 1668 1669 return 0; 1670 } 1671 1672 /* 1673 * unshare allows a process to 'unshare' part of the process 1674 * context which was originally shared using clone. copy_* 1675 * functions used by do_fork() cannot be used here directly 1676 * because they modify an inactive task_struct that is being 1677 * constructed. Here we are modifying the current, active, 1678 * task_struct. 1679 */ 1680 asmlinkage long sys_unshare(unsigned long unshare_flags) 1681 { 1682 int err = 0; 1683 struct fs_struct *fs, *new_fs = NULL; 1684 struct sighand_struct *new_sigh = NULL; 1685 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; 1686 struct files_struct *fd, *new_fd = NULL; 1687 struct sem_undo_list *new_ulist = NULL; 1688 struct nsproxy *new_nsproxy = NULL; 1689 1690 check_unshare_flags(&unshare_flags); 1691 1692 /* Return -EINVAL for all unsupported flags */ 1693 err = -EINVAL; 1694 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 1695 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 1696 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER| 1697 CLONE_NEWNET)) 1698 goto bad_unshare_out; 1699 1700 if ((err = unshare_thread(unshare_flags))) 1701 goto bad_unshare_out; 1702 if ((err = unshare_fs(unshare_flags, &new_fs))) 1703 goto bad_unshare_cleanup_thread; 1704 if ((err = unshare_sighand(unshare_flags, &new_sigh))) 1705 goto bad_unshare_cleanup_fs; 1706 if ((err = unshare_vm(unshare_flags, &new_mm))) 1707 goto bad_unshare_cleanup_sigh; 1708 if ((err = unshare_fd(unshare_flags, &new_fd))) 1709 goto bad_unshare_cleanup_vm; 1710 if ((err = unshare_semundo(unshare_flags, &new_ulist))) 1711 goto bad_unshare_cleanup_fd; 1712 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 1713 new_fs))) 1714 goto bad_unshare_cleanup_semundo; 1715 1716 if (new_fs || new_mm || new_fd || new_ulist || new_nsproxy) { 1717 1718 if (new_nsproxy) { 1719 switch_task_namespaces(current, new_nsproxy); 1720 new_nsproxy = NULL; 1721 } 1722 1723 task_lock(current); 1724 1725 if (new_fs) { 1726 fs = current->fs; 1727 current->fs = new_fs; 1728 new_fs = fs; 1729 } 1730 1731 if (new_mm) { 1732 mm = current->mm; 1733 active_mm = current->active_mm; 1734 current->mm = new_mm; 1735 current->active_mm = new_mm; 1736 activate_mm(active_mm, new_mm); 1737 new_mm = mm; 1738 } 1739 1740 if (new_fd) { 1741 fd = current->files; 1742 current->files = new_fd; 1743 new_fd = fd; 1744 } 1745 1746 task_unlock(current); 1747 } 1748 1749 if (new_nsproxy) 1750 put_nsproxy(new_nsproxy); 1751 1752 bad_unshare_cleanup_semundo: 1753 bad_unshare_cleanup_fd: 1754 if (new_fd) 1755 put_files_struct(new_fd); 1756 1757 bad_unshare_cleanup_vm: 1758 if (new_mm) 1759 mmput(new_mm); 1760 1761 bad_unshare_cleanup_sigh: 1762 if (new_sigh) 1763 if (atomic_dec_and_test(&new_sigh->count)) 1764 kmem_cache_free(sighand_cachep, new_sigh); 1765 1766 bad_unshare_cleanup_fs: 1767 if (new_fs) 1768 put_fs_struct(new_fs); 1769 1770 bad_unshare_cleanup_thread: 1771 bad_unshare_out: 1772 return err; 1773 } 1774