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/fdtable.h> 26 #include <linux/key.h> 27 #include <linux/binfmts.h> 28 #include <linux/mman.h> 29 #include <linux/fs.h> 30 #include <linux/nsproxy.h> 31 #include <linux/capability.h> 32 #include <linux/cpu.h> 33 #include <linux/cgroup.h> 34 #include <linux/security.h> 35 #include <linux/swap.h> 36 #include <linux/syscalls.h> 37 #include <linux/jiffies.h> 38 #include <linux/futex.h> 39 #include <linux/task_io_accounting_ops.h> 40 #include <linux/rcupdate.h> 41 #include <linux/ptrace.h> 42 #include <linux/mount.h> 43 #include <linux/audit.h> 44 #include <linux/memcontrol.h> 45 #include <linux/profile.h> 46 #include <linux/rmap.h> 47 #include <linux/acct.h> 48 #include <linux/tsacct_kern.h> 49 #include <linux/cn_proc.h> 50 #include <linux/freezer.h> 51 #include <linux/delayacct.h> 52 #include <linux/taskstats_kern.h> 53 #include <linux/random.h> 54 #include <linux/tty.h> 55 #include <linux/proc_fs.h> 56 #include <linux/blkdev.h> 57 58 #include <asm/pgtable.h> 59 #include <asm/pgalloc.h> 60 #include <asm/uaccess.h> 61 #include <asm/mmu_context.h> 62 #include <asm/cacheflush.h> 63 #include <asm/tlbflush.h> 64 65 /* 66 * Protected counters by write_lock_irq(&tasklist_lock) 67 */ 68 unsigned long total_forks; /* Handle normal Linux uptimes. */ 69 int nr_threads; /* The idle threads do not count.. */ 70 71 int max_threads; /* tunable limit on nr_threads */ 72 73 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 74 75 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 76 77 int nr_processes(void) 78 { 79 int cpu; 80 int total = 0; 81 82 for_each_online_cpu(cpu) 83 total += per_cpu(process_counts, cpu); 84 85 return total; 86 } 87 88 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 89 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) 90 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) 91 static struct kmem_cache *task_struct_cachep; 92 #endif 93 94 /* SLAB cache for signal_struct structures (tsk->signal) */ 95 static struct kmem_cache *signal_cachep; 96 97 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 98 struct kmem_cache *sighand_cachep; 99 100 /* SLAB cache for files_struct structures (tsk->files) */ 101 struct kmem_cache *files_cachep; 102 103 /* SLAB cache for fs_struct structures (tsk->fs) */ 104 struct kmem_cache *fs_cachep; 105 106 /* SLAB cache for vm_area_struct structures */ 107 struct kmem_cache *vm_area_cachep; 108 109 /* SLAB cache for mm_struct structures (tsk->mm) */ 110 static struct kmem_cache *mm_cachep; 111 112 void free_task(struct task_struct *tsk) 113 { 114 prop_local_destroy_single(&tsk->dirties); 115 free_thread_info(tsk->stack); 116 rt_mutex_debug_task_free(tsk); 117 free_task_struct(tsk); 118 } 119 EXPORT_SYMBOL(free_task); 120 121 void __put_task_struct(struct task_struct *tsk) 122 { 123 WARN_ON(!tsk->exit_state); 124 WARN_ON(atomic_read(&tsk->usage)); 125 WARN_ON(tsk == current); 126 127 security_task_free(tsk); 128 free_uid(tsk->user); 129 put_group_info(tsk->group_info); 130 delayacct_tsk_free(tsk); 131 132 if (!profile_handoff_task(tsk)) 133 free_task(tsk); 134 } 135 136 /* 137 * macro override instead of weak attribute alias, to workaround 138 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. 139 */ 140 #ifndef arch_task_cache_init 141 #define arch_task_cache_init() 142 #endif 143 144 void __init fork_init(unsigned long mempages) 145 { 146 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 147 #ifndef ARCH_MIN_TASKALIGN 148 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES 149 #endif 150 /* create a slab on which task_structs can be allocated */ 151 task_struct_cachep = 152 kmem_cache_create("task_struct", sizeof(struct task_struct), 153 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL); 154 #endif 155 156 /* do the arch specific task caches init */ 157 arch_task_cache_init(); 158 159 /* 160 * The default maximum number of threads is set to a safe 161 * value: the thread structures can take up at most half 162 * of memory. 163 */ 164 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); 165 166 /* 167 * we need to allow at least 20 threads to boot a system 168 */ 169 if(max_threads < 20) 170 max_threads = 20; 171 172 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 173 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 174 init_task.signal->rlim[RLIMIT_SIGPENDING] = 175 init_task.signal->rlim[RLIMIT_NPROC]; 176 } 177 178 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, 179 struct task_struct *src) 180 { 181 *dst = *src; 182 return 0; 183 } 184 185 static struct task_struct *dup_task_struct(struct task_struct *orig) 186 { 187 struct task_struct *tsk; 188 struct thread_info *ti; 189 int err; 190 191 prepare_to_copy(orig); 192 193 tsk = alloc_task_struct(); 194 if (!tsk) 195 return NULL; 196 197 ti = alloc_thread_info(tsk); 198 if (!ti) { 199 free_task_struct(tsk); 200 return NULL; 201 } 202 203 err = arch_dup_task_struct(tsk, orig); 204 if (err) 205 goto out; 206 207 tsk->stack = ti; 208 209 err = prop_local_init_single(&tsk->dirties); 210 if (err) 211 goto out; 212 213 setup_thread_stack(tsk, orig); 214 215 #ifdef CONFIG_CC_STACKPROTECTOR 216 tsk->stack_canary = get_random_int(); 217 #endif 218 219 /* One for us, one for whoever does the "release_task()" (usually parent) */ 220 atomic_set(&tsk->usage,2); 221 atomic_set(&tsk->fs_excl, 0); 222 #ifdef CONFIG_BLK_DEV_IO_TRACE 223 tsk->btrace_seq = 0; 224 #endif 225 tsk->splice_pipe = NULL; 226 return tsk; 227 228 out: 229 free_thread_info(ti); 230 free_task_struct(tsk); 231 return NULL; 232 } 233 234 #ifdef CONFIG_MMU 235 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 236 { 237 struct vm_area_struct *mpnt, *tmp, **pprev; 238 struct rb_node **rb_link, *rb_parent; 239 int retval; 240 unsigned long charge; 241 struct mempolicy *pol; 242 243 down_write(&oldmm->mmap_sem); 244 flush_cache_dup_mm(oldmm); 245 /* 246 * Not linked in yet - no deadlock potential: 247 */ 248 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); 249 250 mm->locked_vm = 0; 251 mm->mmap = NULL; 252 mm->mmap_cache = NULL; 253 mm->free_area_cache = oldmm->mmap_base; 254 mm->cached_hole_size = ~0UL; 255 mm->map_count = 0; 256 cpus_clear(mm->cpu_vm_mask); 257 mm->mm_rb = RB_ROOT; 258 rb_link = &mm->mm_rb.rb_node; 259 rb_parent = NULL; 260 pprev = &mm->mmap; 261 262 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 263 struct file *file; 264 265 if (mpnt->vm_flags & VM_DONTCOPY) { 266 long pages = vma_pages(mpnt); 267 mm->total_vm -= pages; 268 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, 269 -pages); 270 continue; 271 } 272 charge = 0; 273 if (mpnt->vm_flags & VM_ACCOUNT) { 274 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; 275 if (security_vm_enough_memory(len)) 276 goto fail_nomem; 277 charge = len; 278 } 279 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 280 if (!tmp) 281 goto fail_nomem; 282 *tmp = *mpnt; 283 pol = mpol_dup(vma_policy(mpnt)); 284 retval = PTR_ERR(pol); 285 if (IS_ERR(pol)) 286 goto fail_nomem_policy; 287 vma_set_policy(tmp, pol); 288 tmp->vm_flags &= ~VM_LOCKED; 289 tmp->vm_mm = mm; 290 tmp->vm_next = NULL; 291 anon_vma_link(tmp); 292 file = tmp->vm_file; 293 if (file) { 294 struct inode *inode = file->f_path.dentry->d_inode; 295 get_file(file); 296 if (tmp->vm_flags & VM_DENYWRITE) 297 atomic_dec(&inode->i_writecount); 298 299 /* insert tmp into the share list, just after mpnt */ 300 spin_lock(&file->f_mapping->i_mmap_lock); 301 tmp->vm_truncate_count = mpnt->vm_truncate_count; 302 flush_dcache_mmap_lock(file->f_mapping); 303 vma_prio_tree_add(tmp, mpnt); 304 flush_dcache_mmap_unlock(file->f_mapping); 305 spin_unlock(&file->f_mapping->i_mmap_lock); 306 } 307 308 /* 309 * Link in the new vma and copy the page table entries. 310 */ 311 *pprev = tmp; 312 pprev = &tmp->vm_next; 313 314 __vma_link_rb(mm, tmp, rb_link, rb_parent); 315 rb_link = &tmp->vm_rb.rb_right; 316 rb_parent = &tmp->vm_rb; 317 318 mm->map_count++; 319 retval = copy_page_range(mm, oldmm, mpnt); 320 321 if (tmp->vm_ops && tmp->vm_ops->open) 322 tmp->vm_ops->open(tmp); 323 324 if (retval) 325 goto out; 326 } 327 /* a new mm has just been created */ 328 arch_dup_mmap(oldmm, mm); 329 retval = 0; 330 out: 331 up_write(&mm->mmap_sem); 332 flush_tlb_mm(oldmm); 333 up_write(&oldmm->mmap_sem); 334 return retval; 335 fail_nomem_policy: 336 kmem_cache_free(vm_area_cachep, tmp); 337 fail_nomem: 338 retval = -ENOMEM; 339 vm_unacct_memory(charge); 340 goto out; 341 } 342 343 static inline int mm_alloc_pgd(struct mm_struct * mm) 344 { 345 mm->pgd = pgd_alloc(mm); 346 if (unlikely(!mm->pgd)) 347 return -ENOMEM; 348 return 0; 349 } 350 351 static inline void mm_free_pgd(struct mm_struct * mm) 352 { 353 pgd_free(mm, mm->pgd); 354 } 355 #else 356 #define dup_mmap(mm, oldmm) (0) 357 #define mm_alloc_pgd(mm) (0) 358 #define mm_free_pgd(mm) 359 #endif /* CONFIG_MMU */ 360 361 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 362 363 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 364 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 365 366 #include <linux/init_task.h> 367 368 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) 369 { 370 atomic_set(&mm->mm_users, 1); 371 atomic_set(&mm->mm_count, 1); 372 init_rwsem(&mm->mmap_sem); 373 INIT_LIST_HEAD(&mm->mmlist); 374 mm->flags = (current->mm) ? current->mm->flags 375 : MMF_DUMP_FILTER_DEFAULT; 376 mm->core_waiters = 0; 377 mm->nr_ptes = 0; 378 set_mm_counter(mm, file_rss, 0); 379 set_mm_counter(mm, anon_rss, 0); 380 spin_lock_init(&mm->page_table_lock); 381 rwlock_init(&mm->ioctx_list_lock); 382 mm->ioctx_list = NULL; 383 mm->free_area_cache = TASK_UNMAPPED_BASE; 384 mm->cached_hole_size = ~0UL; 385 mm_init_owner(mm, p); 386 387 if (likely(!mm_alloc_pgd(mm))) { 388 mm->def_flags = 0; 389 return mm; 390 } 391 392 free_mm(mm); 393 return NULL; 394 } 395 396 /* 397 * Allocate and initialize an mm_struct. 398 */ 399 struct mm_struct * mm_alloc(void) 400 { 401 struct mm_struct * mm; 402 403 mm = allocate_mm(); 404 if (mm) { 405 memset(mm, 0, sizeof(*mm)); 406 mm = mm_init(mm, current); 407 } 408 return mm; 409 } 410 411 /* 412 * Called when the last reference to the mm 413 * is dropped: either by a lazy thread or by 414 * mmput. Free the page directory and the mm. 415 */ 416 void __mmdrop(struct mm_struct *mm) 417 { 418 BUG_ON(mm == &init_mm); 419 mm_free_pgd(mm); 420 destroy_context(mm); 421 free_mm(mm); 422 } 423 EXPORT_SYMBOL_GPL(__mmdrop); 424 425 /* 426 * Decrement the use count and release all resources for an mm. 427 */ 428 void mmput(struct mm_struct *mm) 429 { 430 might_sleep(); 431 432 if (atomic_dec_and_test(&mm->mm_users)) { 433 exit_aio(mm); 434 exit_mmap(mm); 435 set_mm_exe_file(mm, NULL); 436 if (!list_empty(&mm->mmlist)) { 437 spin_lock(&mmlist_lock); 438 list_del(&mm->mmlist); 439 spin_unlock(&mmlist_lock); 440 } 441 put_swap_token(mm); 442 mmdrop(mm); 443 } 444 } 445 EXPORT_SYMBOL_GPL(mmput); 446 447 /** 448 * get_task_mm - acquire a reference to the task's mm 449 * 450 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning 451 * this kernel workthread has transiently adopted a user mm with use_mm, 452 * to do its AIO) is not set and if so returns a reference to it, after 453 * bumping up the use count. User must release the mm via mmput() 454 * after use. Typically used by /proc and ptrace. 455 */ 456 struct mm_struct *get_task_mm(struct task_struct *task) 457 { 458 struct mm_struct *mm; 459 460 task_lock(task); 461 mm = task->mm; 462 if (mm) { 463 if (task->flags & PF_BORROWED_MM) 464 mm = NULL; 465 else 466 atomic_inc(&mm->mm_users); 467 } 468 task_unlock(task); 469 return mm; 470 } 471 EXPORT_SYMBOL_GPL(get_task_mm); 472 473 /* Please note the differences between mmput and mm_release. 474 * mmput is called whenever we stop holding onto a mm_struct, 475 * error success whatever. 476 * 477 * mm_release is called after a mm_struct has been removed 478 * from the current process. 479 * 480 * This difference is important for error handling, when we 481 * only half set up a mm_struct for a new process and need to restore 482 * the old one. Because we mmput the new mm_struct before 483 * restoring the old one. . . 484 * Eric Biederman 10 January 1998 485 */ 486 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 487 { 488 struct completion *vfork_done = tsk->vfork_done; 489 490 /* Get rid of any cached register state */ 491 deactivate_mm(tsk, mm); 492 493 /* notify parent sleeping on vfork() */ 494 if (vfork_done) { 495 tsk->vfork_done = NULL; 496 complete(vfork_done); 497 } 498 499 /* 500 * If we're exiting normally, clear a user-space tid field if 501 * requested. We leave this alone when dying by signal, to leave 502 * the value intact in a core dump, and to save the unnecessary 503 * trouble otherwise. Userland only wants this done for a sys_exit. 504 */ 505 if (tsk->clear_child_tid 506 && !(tsk->flags & PF_SIGNALED) 507 && atomic_read(&mm->mm_users) > 1) { 508 u32 __user * tidptr = tsk->clear_child_tid; 509 tsk->clear_child_tid = NULL; 510 511 /* 512 * We don't check the error code - if userspace has 513 * not set up a proper pointer then tough luck. 514 */ 515 put_user(0, tidptr); 516 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); 517 } 518 } 519 520 /* 521 * Allocate a new mm structure and copy contents from the 522 * mm structure of the passed in task structure. 523 */ 524 struct mm_struct *dup_mm(struct task_struct *tsk) 525 { 526 struct mm_struct *mm, *oldmm = current->mm; 527 int err; 528 529 if (!oldmm) 530 return NULL; 531 532 mm = allocate_mm(); 533 if (!mm) 534 goto fail_nomem; 535 536 memcpy(mm, oldmm, sizeof(*mm)); 537 538 /* Initializing for Swap token stuff */ 539 mm->token_priority = 0; 540 mm->last_interval = 0; 541 542 if (!mm_init(mm, tsk)) 543 goto fail_nomem; 544 545 if (init_new_context(tsk, mm)) 546 goto fail_nocontext; 547 548 dup_mm_exe_file(oldmm, mm); 549 550 err = dup_mmap(mm, oldmm); 551 if (err) 552 goto free_pt; 553 554 mm->hiwater_rss = get_mm_rss(mm); 555 mm->hiwater_vm = mm->total_vm; 556 557 return mm; 558 559 free_pt: 560 mmput(mm); 561 562 fail_nomem: 563 return NULL; 564 565 fail_nocontext: 566 /* 567 * If init_new_context() failed, we cannot use mmput() to free the mm 568 * because it calls destroy_context() 569 */ 570 mm_free_pgd(mm); 571 free_mm(mm); 572 return NULL; 573 } 574 575 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) 576 { 577 struct mm_struct * mm, *oldmm; 578 int retval; 579 580 tsk->min_flt = tsk->maj_flt = 0; 581 tsk->nvcsw = tsk->nivcsw = 0; 582 583 tsk->mm = NULL; 584 tsk->active_mm = NULL; 585 586 /* 587 * Are we cloning a kernel thread? 588 * 589 * We need to steal a active VM for that.. 590 */ 591 oldmm = current->mm; 592 if (!oldmm) 593 return 0; 594 595 if (clone_flags & CLONE_VM) { 596 atomic_inc(&oldmm->mm_users); 597 mm = oldmm; 598 goto good_mm; 599 } 600 601 retval = -ENOMEM; 602 mm = dup_mm(tsk); 603 if (!mm) 604 goto fail_nomem; 605 606 good_mm: 607 /* Initializing for Swap token stuff */ 608 mm->token_priority = 0; 609 mm->last_interval = 0; 610 611 tsk->mm = mm; 612 tsk->active_mm = mm; 613 return 0; 614 615 fail_nomem: 616 return retval; 617 } 618 619 static struct fs_struct *__copy_fs_struct(struct fs_struct *old) 620 { 621 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); 622 /* We don't need to lock fs - think why ;-) */ 623 if (fs) { 624 atomic_set(&fs->count, 1); 625 rwlock_init(&fs->lock); 626 fs->umask = old->umask; 627 read_lock(&old->lock); 628 fs->root = old->root; 629 path_get(&old->root); 630 fs->pwd = old->pwd; 631 path_get(&old->pwd); 632 if (old->altroot.dentry) { 633 fs->altroot = old->altroot; 634 path_get(&old->altroot); 635 } else { 636 fs->altroot.mnt = NULL; 637 fs->altroot.dentry = NULL; 638 } 639 read_unlock(&old->lock); 640 } 641 return fs; 642 } 643 644 struct fs_struct *copy_fs_struct(struct fs_struct *old) 645 { 646 return __copy_fs_struct(old); 647 } 648 649 EXPORT_SYMBOL_GPL(copy_fs_struct); 650 651 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 652 { 653 if (clone_flags & CLONE_FS) { 654 atomic_inc(¤t->fs->count); 655 return 0; 656 } 657 tsk->fs = __copy_fs_struct(current->fs); 658 if (!tsk->fs) 659 return -ENOMEM; 660 return 0; 661 } 662 663 static int count_open_files(struct fdtable *fdt) 664 { 665 int size = fdt->max_fds; 666 int i; 667 668 /* Find the last open fd */ 669 for (i = size/(8*sizeof(long)); i > 0; ) { 670 if (fdt->open_fds->fds_bits[--i]) 671 break; 672 } 673 i = (i+1) * 8 * sizeof(long); 674 return i; 675 } 676 677 static struct files_struct *alloc_files(void) 678 { 679 struct files_struct *newf; 680 struct fdtable *fdt; 681 682 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); 683 if (!newf) 684 goto out; 685 686 atomic_set(&newf->count, 1); 687 688 spin_lock_init(&newf->file_lock); 689 newf->next_fd = 0; 690 fdt = &newf->fdtab; 691 fdt->max_fds = NR_OPEN_DEFAULT; 692 fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init; 693 fdt->open_fds = (fd_set *)&newf->open_fds_init; 694 fdt->fd = &newf->fd_array[0]; 695 INIT_RCU_HEAD(&fdt->rcu); 696 fdt->next = NULL; 697 rcu_assign_pointer(newf->fdt, fdt); 698 out: 699 return newf; 700 } 701 702 /* 703 * Allocate a new files structure and copy contents from the 704 * passed in files structure. 705 * errorp will be valid only when the returned files_struct is NULL. 706 */ 707 static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) 708 { 709 struct files_struct *newf; 710 struct file **old_fds, **new_fds; 711 int open_files, size, i; 712 struct fdtable *old_fdt, *new_fdt; 713 714 *errorp = -ENOMEM; 715 newf = alloc_files(); 716 if (!newf) 717 goto out; 718 719 spin_lock(&oldf->file_lock); 720 old_fdt = files_fdtable(oldf); 721 new_fdt = files_fdtable(newf); 722 open_files = count_open_files(old_fdt); 723 724 /* 725 * Check whether we need to allocate a larger fd array and fd set. 726 * Note: we're not a clone task, so the open count won't change. 727 */ 728 if (open_files > new_fdt->max_fds) { 729 new_fdt->max_fds = 0; 730 spin_unlock(&oldf->file_lock); 731 spin_lock(&newf->file_lock); 732 *errorp = expand_files(newf, open_files-1); 733 spin_unlock(&newf->file_lock); 734 if (*errorp < 0) 735 goto out_release; 736 new_fdt = files_fdtable(newf); 737 /* 738 * Reacquire the oldf lock and a pointer to its fd table 739 * who knows it may have a new bigger fd table. We need 740 * the latest pointer. 741 */ 742 spin_lock(&oldf->file_lock); 743 old_fdt = files_fdtable(oldf); 744 } 745 746 old_fds = old_fdt->fd; 747 new_fds = new_fdt->fd; 748 749 memcpy(new_fdt->open_fds->fds_bits, 750 old_fdt->open_fds->fds_bits, open_files/8); 751 memcpy(new_fdt->close_on_exec->fds_bits, 752 old_fdt->close_on_exec->fds_bits, open_files/8); 753 754 for (i = open_files; i != 0; i--) { 755 struct file *f = *old_fds++; 756 if (f) { 757 get_file(f); 758 } else { 759 /* 760 * The fd may be claimed in the fd bitmap but not yet 761 * instantiated in the files array if a sibling thread 762 * is partway through open(). So make sure that this 763 * fd is available to the new process. 764 */ 765 FD_CLR(open_files - i, new_fdt->open_fds); 766 } 767 rcu_assign_pointer(*new_fds++, f); 768 } 769 spin_unlock(&oldf->file_lock); 770 771 /* compute the remainder to be cleared */ 772 size = (new_fdt->max_fds - open_files) * sizeof(struct file *); 773 774 /* This is long word aligned thus could use a optimized version */ 775 memset(new_fds, 0, size); 776 777 if (new_fdt->max_fds > open_files) { 778 int left = (new_fdt->max_fds-open_files)/8; 779 int start = open_files / (8 * sizeof(unsigned long)); 780 781 memset(&new_fdt->open_fds->fds_bits[start], 0, left); 782 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); 783 } 784 785 return newf; 786 787 out_release: 788 kmem_cache_free(files_cachep, newf); 789 out: 790 return NULL; 791 } 792 793 static int copy_files(unsigned long clone_flags, struct task_struct * tsk) 794 { 795 struct files_struct *oldf, *newf; 796 int error = 0; 797 798 /* 799 * A background process may not have any files ... 800 */ 801 oldf = current->files; 802 if (!oldf) 803 goto out; 804 805 if (clone_flags & CLONE_FILES) { 806 atomic_inc(&oldf->count); 807 goto out; 808 } 809 810 newf = dup_fd(oldf, &error); 811 if (!newf) 812 goto out; 813 814 tsk->files = newf; 815 error = 0; 816 out: 817 return error; 818 } 819 820 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 821 { 822 #ifdef CONFIG_BLOCK 823 struct io_context *ioc = current->io_context; 824 825 if (!ioc) 826 return 0; 827 /* 828 * Share io context with parent, if CLONE_IO is set 829 */ 830 if (clone_flags & CLONE_IO) { 831 tsk->io_context = ioc_task_link(ioc); 832 if (unlikely(!tsk->io_context)) 833 return -ENOMEM; 834 } else if (ioprio_valid(ioc->ioprio)) { 835 tsk->io_context = alloc_io_context(GFP_KERNEL, -1); 836 if (unlikely(!tsk->io_context)) 837 return -ENOMEM; 838 839 tsk->io_context->ioprio = ioc->ioprio; 840 } 841 #endif 842 return 0; 843 } 844 845 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 846 { 847 struct sighand_struct *sig; 848 849 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { 850 atomic_inc(¤t->sighand->count); 851 return 0; 852 } 853 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 854 rcu_assign_pointer(tsk->sighand, sig); 855 if (!sig) 856 return -ENOMEM; 857 atomic_set(&sig->count, 1); 858 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 859 return 0; 860 } 861 862 void __cleanup_sighand(struct sighand_struct *sighand) 863 { 864 if (atomic_dec_and_test(&sighand->count)) 865 kmem_cache_free(sighand_cachep, sighand); 866 } 867 868 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 869 { 870 struct signal_struct *sig; 871 int ret; 872 873 if (clone_flags & CLONE_THREAD) { 874 atomic_inc(¤t->signal->count); 875 atomic_inc(¤t->signal->live); 876 return 0; 877 } 878 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); 879 tsk->signal = sig; 880 if (!sig) 881 return -ENOMEM; 882 883 ret = copy_thread_group_keys(tsk); 884 if (ret < 0) { 885 kmem_cache_free(signal_cachep, sig); 886 return ret; 887 } 888 889 atomic_set(&sig->count, 1); 890 atomic_set(&sig->live, 1); 891 init_waitqueue_head(&sig->wait_chldexit); 892 sig->flags = 0; 893 sig->group_exit_code = 0; 894 sig->group_exit_task = NULL; 895 sig->group_stop_count = 0; 896 sig->curr_target = tsk; 897 init_sigpending(&sig->shared_pending); 898 INIT_LIST_HEAD(&sig->posix_timers); 899 900 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 901 sig->it_real_incr.tv64 = 0; 902 sig->real_timer.function = it_real_fn; 903 904 sig->it_virt_expires = cputime_zero; 905 sig->it_virt_incr = cputime_zero; 906 sig->it_prof_expires = cputime_zero; 907 sig->it_prof_incr = cputime_zero; 908 909 sig->leader = 0; /* session leadership doesn't inherit */ 910 sig->tty_old_pgrp = NULL; 911 912 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; 913 sig->gtime = cputime_zero; 914 sig->cgtime = cputime_zero; 915 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; 916 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; 917 sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0; 918 sig->sum_sched_runtime = 0; 919 INIT_LIST_HEAD(&sig->cpu_timers[0]); 920 INIT_LIST_HEAD(&sig->cpu_timers[1]); 921 INIT_LIST_HEAD(&sig->cpu_timers[2]); 922 taskstats_tgid_init(sig); 923 924 task_lock(current->group_leader); 925 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 926 task_unlock(current->group_leader); 927 928 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { 929 /* 930 * New sole thread in the process gets an expiry time 931 * of the whole CPU time limit. 932 */ 933 tsk->it_prof_expires = 934 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); 935 } 936 acct_init_pacct(&sig->pacct); 937 938 tty_audit_fork(sig); 939 940 return 0; 941 } 942 943 void __cleanup_signal(struct signal_struct *sig) 944 { 945 exit_thread_group_keys(sig); 946 kmem_cache_free(signal_cachep, sig); 947 } 948 949 static void cleanup_signal(struct task_struct *tsk) 950 { 951 struct signal_struct *sig = tsk->signal; 952 953 atomic_dec(&sig->live); 954 955 if (atomic_dec_and_test(&sig->count)) 956 __cleanup_signal(sig); 957 } 958 959 static void copy_flags(unsigned long clone_flags, struct task_struct *p) 960 { 961 unsigned long new_flags = p->flags; 962 963 new_flags &= ~PF_SUPERPRIV; 964 new_flags |= PF_FORKNOEXEC; 965 if (!(clone_flags & CLONE_PTRACE)) 966 p->ptrace = 0; 967 p->flags = new_flags; 968 clear_freeze_flag(p); 969 } 970 971 asmlinkage long sys_set_tid_address(int __user *tidptr) 972 { 973 current->clear_child_tid = tidptr; 974 975 return task_pid_vnr(current); 976 } 977 978 static void rt_mutex_init_task(struct task_struct *p) 979 { 980 spin_lock_init(&p->pi_lock); 981 #ifdef CONFIG_RT_MUTEXES 982 plist_head_init(&p->pi_waiters, &p->pi_lock); 983 p->pi_blocked_on = NULL; 984 #endif 985 } 986 987 #ifdef CONFIG_MM_OWNER 988 void mm_init_owner(struct mm_struct *mm, struct task_struct *p) 989 { 990 mm->owner = p; 991 } 992 #endif /* CONFIG_MM_OWNER */ 993 994 /* 995 * This creates a new process as a copy of the old one, 996 * but does not actually start it yet. 997 * 998 * It copies the registers, and all the appropriate 999 * parts of the process environment (as per the clone 1000 * flags). The actual kick-off is left to the caller. 1001 */ 1002 static struct task_struct *copy_process(unsigned long clone_flags, 1003 unsigned long stack_start, 1004 struct pt_regs *regs, 1005 unsigned long stack_size, 1006 int __user *child_tidptr, 1007 struct pid *pid) 1008 { 1009 int retval; 1010 struct task_struct *p; 1011 int cgroup_callbacks_done = 0; 1012 1013 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1014 return ERR_PTR(-EINVAL); 1015 1016 /* 1017 * Thread groups must share signals as well, and detached threads 1018 * can only be started up within the thread group. 1019 */ 1020 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1021 return ERR_PTR(-EINVAL); 1022 1023 /* 1024 * Shared signal handlers imply shared VM. By way of the above, 1025 * thread groups also imply shared VM. Blocking this case allows 1026 * for various simplifications in other code. 1027 */ 1028 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1029 return ERR_PTR(-EINVAL); 1030 1031 retval = security_task_create(clone_flags); 1032 if (retval) 1033 goto fork_out; 1034 1035 retval = -ENOMEM; 1036 p = dup_task_struct(current); 1037 if (!p) 1038 goto fork_out; 1039 1040 rt_mutex_init_task(p); 1041 1042 #ifdef CONFIG_TRACE_IRQFLAGS 1043 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 1044 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1045 #endif 1046 retval = -EAGAIN; 1047 if (atomic_read(&p->user->processes) >= 1048 p->signal->rlim[RLIMIT_NPROC].rlim_cur) { 1049 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && 1050 p->user != current->nsproxy->user_ns->root_user) 1051 goto bad_fork_free; 1052 } 1053 1054 atomic_inc(&p->user->__count); 1055 atomic_inc(&p->user->processes); 1056 get_group_info(p->group_info); 1057 1058 /* 1059 * If multiple threads are within copy_process(), then this check 1060 * triggers too late. This doesn't hurt, the check is only there 1061 * to stop root fork bombs. 1062 */ 1063 if (nr_threads >= max_threads) 1064 goto bad_fork_cleanup_count; 1065 1066 if (!try_module_get(task_thread_info(p)->exec_domain->module)) 1067 goto bad_fork_cleanup_count; 1068 1069 if (p->binfmt && !try_module_get(p->binfmt->module)) 1070 goto bad_fork_cleanup_put_domain; 1071 1072 p->did_exec = 0; 1073 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1074 copy_flags(clone_flags, p); 1075 INIT_LIST_HEAD(&p->children); 1076 INIT_LIST_HEAD(&p->sibling); 1077 #ifdef CONFIG_PREEMPT_RCU 1078 p->rcu_read_lock_nesting = 0; 1079 p->rcu_flipctr_idx = 0; 1080 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 1081 p->vfork_done = NULL; 1082 spin_lock_init(&p->alloc_lock); 1083 1084 clear_tsk_thread_flag(p, TIF_SIGPENDING); 1085 init_sigpending(&p->pending); 1086 1087 p->utime = cputime_zero; 1088 p->stime = cputime_zero; 1089 p->gtime = cputime_zero; 1090 p->utimescaled = cputime_zero; 1091 p->stimescaled = cputime_zero; 1092 p->prev_utime = cputime_zero; 1093 p->prev_stime = cputime_zero; 1094 1095 #ifdef CONFIG_DETECT_SOFTLOCKUP 1096 p->last_switch_count = 0; 1097 p->last_switch_timestamp = 0; 1098 #endif 1099 1100 #ifdef CONFIG_TASK_XACCT 1101 p->rchar = 0; /* I/O counter: bytes read */ 1102 p->wchar = 0; /* I/O counter: bytes written */ 1103 p->syscr = 0; /* I/O counter: read syscalls */ 1104 p->syscw = 0; /* I/O counter: write syscalls */ 1105 #endif 1106 task_io_accounting_init(p); 1107 acct_clear_integrals(p); 1108 1109 p->it_virt_expires = cputime_zero; 1110 p->it_prof_expires = cputime_zero; 1111 p->it_sched_expires = 0; 1112 INIT_LIST_HEAD(&p->cpu_timers[0]); 1113 INIT_LIST_HEAD(&p->cpu_timers[1]); 1114 INIT_LIST_HEAD(&p->cpu_timers[2]); 1115 1116 p->lock_depth = -1; /* -1 = no lock */ 1117 do_posix_clock_monotonic_gettime(&p->start_time); 1118 p->real_start_time = p->start_time; 1119 monotonic_to_bootbased(&p->real_start_time); 1120 #ifdef CONFIG_SECURITY 1121 p->security = NULL; 1122 #endif 1123 p->cap_bset = current->cap_bset; 1124 p->io_context = NULL; 1125 p->audit_context = NULL; 1126 cgroup_fork(p); 1127 #ifdef CONFIG_NUMA 1128 p->mempolicy = mpol_dup(p->mempolicy); 1129 if (IS_ERR(p->mempolicy)) { 1130 retval = PTR_ERR(p->mempolicy); 1131 p->mempolicy = NULL; 1132 goto bad_fork_cleanup_cgroup; 1133 } 1134 mpol_fix_fork_child_flag(p); 1135 #endif 1136 #ifdef CONFIG_TRACE_IRQFLAGS 1137 p->irq_events = 0; 1138 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1139 p->hardirqs_enabled = 1; 1140 #else 1141 p->hardirqs_enabled = 0; 1142 #endif 1143 p->hardirq_enable_ip = 0; 1144 p->hardirq_enable_event = 0; 1145 p->hardirq_disable_ip = _THIS_IP_; 1146 p->hardirq_disable_event = 0; 1147 p->softirqs_enabled = 1; 1148 p->softirq_enable_ip = _THIS_IP_; 1149 p->softirq_enable_event = 0; 1150 p->softirq_disable_ip = 0; 1151 p->softirq_disable_event = 0; 1152 p->hardirq_context = 0; 1153 p->softirq_context = 0; 1154 #endif 1155 #ifdef CONFIG_LOCKDEP 1156 p->lockdep_depth = 0; /* no locks held yet */ 1157 p->curr_chain_key = 0; 1158 p->lockdep_recursion = 0; 1159 #endif 1160 1161 #ifdef CONFIG_DEBUG_MUTEXES 1162 p->blocked_on = NULL; /* not blocked yet */ 1163 #endif 1164 1165 /* Perform scheduler related setup. Assign this task to a CPU. */ 1166 sched_fork(p, clone_flags); 1167 1168 if ((retval = security_task_alloc(p))) 1169 goto bad_fork_cleanup_policy; 1170 if ((retval = audit_alloc(p))) 1171 goto bad_fork_cleanup_security; 1172 /* copy all the process information */ 1173 if ((retval = copy_semundo(clone_flags, p))) 1174 goto bad_fork_cleanup_audit; 1175 if ((retval = copy_files(clone_flags, p))) 1176 goto bad_fork_cleanup_semundo; 1177 if ((retval = copy_fs(clone_flags, p))) 1178 goto bad_fork_cleanup_files; 1179 if ((retval = copy_sighand(clone_flags, p))) 1180 goto bad_fork_cleanup_fs; 1181 if ((retval = copy_signal(clone_flags, p))) 1182 goto bad_fork_cleanup_sighand; 1183 if ((retval = copy_mm(clone_flags, p))) 1184 goto bad_fork_cleanup_signal; 1185 if ((retval = copy_keys(clone_flags, p))) 1186 goto bad_fork_cleanup_mm; 1187 if ((retval = copy_namespaces(clone_flags, p))) 1188 goto bad_fork_cleanup_keys; 1189 if ((retval = copy_io(clone_flags, p))) 1190 goto bad_fork_cleanup_namespaces; 1191 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); 1192 if (retval) 1193 goto bad_fork_cleanup_io; 1194 1195 if (pid != &init_struct_pid) { 1196 retval = -ENOMEM; 1197 pid = alloc_pid(task_active_pid_ns(p)); 1198 if (!pid) 1199 goto bad_fork_cleanup_io; 1200 1201 if (clone_flags & CLONE_NEWPID) { 1202 retval = pid_ns_prepare_proc(task_active_pid_ns(p)); 1203 if (retval < 0) 1204 goto bad_fork_free_pid; 1205 } 1206 } 1207 1208 p->pid = pid_nr(pid); 1209 p->tgid = p->pid; 1210 if (clone_flags & CLONE_THREAD) 1211 p->tgid = current->tgid; 1212 1213 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1214 /* 1215 * Clear TID on mm_release()? 1216 */ 1217 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; 1218 #ifdef CONFIG_FUTEX 1219 p->robust_list = NULL; 1220 #ifdef CONFIG_COMPAT 1221 p->compat_robust_list = NULL; 1222 #endif 1223 INIT_LIST_HEAD(&p->pi_state_list); 1224 p->pi_state_cache = NULL; 1225 #endif 1226 /* 1227 * sigaltstack should be cleared when sharing the same VM 1228 */ 1229 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1230 p->sas_ss_sp = p->sas_ss_size = 0; 1231 1232 /* 1233 * Syscall tracing should be turned off in the child regardless 1234 * of CLONE_PTRACE. 1235 */ 1236 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1237 #ifdef TIF_SYSCALL_EMU 1238 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1239 #endif 1240 clear_all_latency_tracing(p); 1241 1242 /* Our parent execution domain becomes current domain 1243 These must match for thread signalling to apply */ 1244 p->parent_exec_id = p->self_exec_id; 1245 1246 /* ok, now we should be set up.. */ 1247 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); 1248 p->pdeath_signal = 0; 1249 p->exit_state = 0; 1250 1251 /* 1252 * Ok, make it visible to the rest of the system. 1253 * We dont wake it up yet. 1254 */ 1255 p->group_leader = p; 1256 INIT_LIST_HEAD(&p->thread_group); 1257 INIT_LIST_HEAD(&p->ptrace_children); 1258 INIT_LIST_HEAD(&p->ptrace_list); 1259 1260 /* Now that the task is set up, run cgroup callbacks if 1261 * necessary. We need to run them before the task is visible 1262 * on the tasklist. */ 1263 cgroup_fork_callbacks(p); 1264 cgroup_callbacks_done = 1; 1265 1266 /* Need tasklist lock for parent etc handling! */ 1267 write_lock_irq(&tasklist_lock); 1268 1269 /* 1270 * The task hasn't been attached yet, so its cpus_allowed mask will 1271 * not be changed, nor will its assigned CPU. 1272 * 1273 * The cpus_allowed mask of the parent may have changed after it was 1274 * copied first time - so re-copy it here, then check the child's CPU 1275 * to ensure it is on a valid CPU (and if not, just force it back to 1276 * parent's CPU). This avoids alot of nasty races. 1277 */ 1278 p->cpus_allowed = current->cpus_allowed; 1279 p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed; 1280 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) || 1281 !cpu_online(task_cpu(p)))) 1282 set_task_cpu(p, smp_processor_id()); 1283 1284 /* CLONE_PARENT re-uses the old parent */ 1285 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) 1286 p->real_parent = current->real_parent; 1287 else 1288 p->real_parent = current; 1289 p->parent = p->real_parent; 1290 1291 spin_lock(¤t->sighand->siglock); 1292 1293 /* 1294 * Process group and session signals need to be delivered to just the 1295 * parent before the fork or both the parent and the child after the 1296 * fork. Restart if a signal comes in before we add the new process to 1297 * it's process group. 1298 * A fatal signal pending means that current will exit, so the new 1299 * thread can't slip out of an OOM kill (or normal SIGKILL). 1300 */ 1301 recalc_sigpending(); 1302 if (signal_pending(current)) { 1303 spin_unlock(¤t->sighand->siglock); 1304 write_unlock_irq(&tasklist_lock); 1305 retval = -ERESTARTNOINTR; 1306 goto bad_fork_free_pid; 1307 } 1308 1309 if (clone_flags & CLONE_THREAD) { 1310 p->group_leader = current->group_leader; 1311 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); 1312 1313 if (!cputime_eq(current->signal->it_virt_expires, 1314 cputime_zero) || 1315 !cputime_eq(current->signal->it_prof_expires, 1316 cputime_zero) || 1317 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || 1318 !list_empty(¤t->signal->cpu_timers[0]) || 1319 !list_empty(¤t->signal->cpu_timers[1]) || 1320 !list_empty(¤t->signal->cpu_timers[2])) { 1321 /* 1322 * Have child wake up on its first tick to check 1323 * for process CPU timers. 1324 */ 1325 p->it_prof_expires = jiffies_to_cputime(1); 1326 } 1327 } 1328 1329 if (likely(p->pid)) { 1330 add_parent(p); 1331 if (unlikely(p->ptrace & PT_PTRACED)) 1332 __ptrace_link(p, current->parent); 1333 1334 if (thread_group_leader(p)) { 1335 if (clone_flags & CLONE_NEWPID) 1336 p->nsproxy->pid_ns->child_reaper = p; 1337 1338 p->signal->leader_pid = pid; 1339 p->signal->tty = current->signal->tty; 1340 set_task_pgrp(p, task_pgrp_nr(current)); 1341 set_task_session(p, task_session_nr(current)); 1342 attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); 1343 attach_pid(p, PIDTYPE_SID, task_session(current)); 1344 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1345 __get_cpu_var(process_counts)++; 1346 } 1347 attach_pid(p, PIDTYPE_PID, pid); 1348 nr_threads++; 1349 } 1350 1351 total_forks++; 1352 spin_unlock(¤t->sighand->siglock); 1353 write_unlock_irq(&tasklist_lock); 1354 proc_fork_connector(p); 1355 cgroup_post_fork(p); 1356 return p; 1357 1358 bad_fork_free_pid: 1359 if (pid != &init_struct_pid) 1360 free_pid(pid); 1361 bad_fork_cleanup_io: 1362 put_io_context(p->io_context); 1363 bad_fork_cleanup_namespaces: 1364 exit_task_namespaces(p); 1365 bad_fork_cleanup_keys: 1366 exit_keys(p); 1367 bad_fork_cleanup_mm: 1368 if (p->mm) 1369 mmput(p->mm); 1370 bad_fork_cleanup_signal: 1371 cleanup_signal(p); 1372 bad_fork_cleanup_sighand: 1373 __cleanup_sighand(p->sighand); 1374 bad_fork_cleanup_fs: 1375 exit_fs(p); /* blocking */ 1376 bad_fork_cleanup_files: 1377 exit_files(p); /* blocking */ 1378 bad_fork_cleanup_semundo: 1379 exit_sem(p); 1380 bad_fork_cleanup_audit: 1381 audit_free(p); 1382 bad_fork_cleanup_security: 1383 security_task_free(p); 1384 bad_fork_cleanup_policy: 1385 #ifdef CONFIG_NUMA 1386 mpol_put(p->mempolicy); 1387 bad_fork_cleanup_cgroup: 1388 #endif 1389 cgroup_exit(p, cgroup_callbacks_done); 1390 delayacct_tsk_free(p); 1391 if (p->binfmt) 1392 module_put(p->binfmt->module); 1393 bad_fork_cleanup_put_domain: 1394 module_put(task_thread_info(p)->exec_domain->module); 1395 bad_fork_cleanup_count: 1396 put_group_info(p->group_info); 1397 atomic_dec(&p->user->processes); 1398 free_uid(p->user); 1399 bad_fork_free: 1400 free_task(p); 1401 fork_out: 1402 return ERR_PTR(retval); 1403 } 1404 1405 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) 1406 { 1407 memset(regs, 0, sizeof(struct pt_regs)); 1408 return regs; 1409 } 1410 1411 struct task_struct * __cpuinit fork_idle(int cpu) 1412 { 1413 struct task_struct *task; 1414 struct pt_regs regs; 1415 1416 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, 1417 &init_struct_pid); 1418 if (!IS_ERR(task)) 1419 init_idle(task, cpu); 1420 1421 return task; 1422 } 1423 1424 static int fork_traceflag(unsigned clone_flags) 1425 { 1426 if (clone_flags & CLONE_UNTRACED) 1427 return 0; 1428 else if (clone_flags & CLONE_VFORK) { 1429 if (current->ptrace & PT_TRACE_VFORK) 1430 return PTRACE_EVENT_VFORK; 1431 } else if ((clone_flags & CSIGNAL) != SIGCHLD) { 1432 if (current->ptrace & PT_TRACE_CLONE) 1433 return PTRACE_EVENT_CLONE; 1434 } else if (current->ptrace & PT_TRACE_FORK) 1435 return PTRACE_EVENT_FORK; 1436 1437 return 0; 1438 } 1439 1440 /* 1441 * Ok, this is the main fork-routine. 1442 * 1443 * It copies the process, and if successful kick-starts 1444 * it and waits for it to finish using the VM if required. 1445 */ 1446 long do_fork(unsigned long clone_flags, 1447 unsigned long stack_start, 1448 struct pt_regs *regs, 1449 unsigned long stack_size, 1450 int __user *parent_tidptr, 1451 int __user *child_tidptr) 1452 { 1453 struct task_struct *p; 1454 int trace = 0; 1455 long nr; 1456 1457 /* 1458 * We hope to recycle these flags after 2.6.26 1459 */ 1460 if (unlikely(clone_flags & CLONE_STOPPED)) { 1461 static int __read_mostly count = 100; 1462 1463 if (count > 0 && printk_ratelimit()) { 1464 char comm[TASK_COMM_LEN]; 1465 1466 count--; 1467 printk(KERN_INFO "fork(): process `%s' used deprecated " 1468 "clone flags 0x%lx\n", 1469 get_task_comm(comm, current), 1470 clone_flags & CLONE_STOPPED); 1471 } 1472 } 1473 1474 if (unlikely(current->ptrace)) { 1475 trace = fork_traceflag (clone_flags); 1476 if (trace) 1477 clone_flags |= CLONE_PTRACE; 1478 } 1479 1480 p = copy_process(clone_flags, stack_start, regs, stack_size, 1481 child_tidptr, NULL); 1482 /* 1483 * Do this prior waking up the new thread - the thread pointer 1484 * might get invalid after that point, if the thread exits quickly. 1485 */ 1486 if (!IS_ERR(p)) { 1487 struct completion vfork; 1488 1489 nr = task_pid_vnr(p); 1490 1491 if (clone_flags & CLONE_PARENT_SETTID) 1492 put_user(nr, parent_tidptr); 1493 1494 if (clone_flags & CLONE_VFORK) { 1495 p->vfork_done = &vfork; 1496 init_completion(&vfork); 1497 } 1498 1499 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { 1500 /* 1501 * We'll start up with an immediate SIGSTOP. 1502 */ 1503 sigaddset(&p->pending.signal, SIGSTOP); 1504 set_tsk_thread_flag(p, TIF_SIGPENDING); 1505 } 1506 1507 if (!(clone_flags & CLONE_STOPPED)) 1508 wake_up_new_task(p, clone_flags); 1509 else 1510 __set_task_state(p, TASK_STOPPED); 1511 1512 if (unlikely (trace)) { 1513 current->ptrace_message = nr; 1514 ptrace_notify ((trace << 8) | SIGTRAP); 1515 } 1516 1517 if (clone_flags & CLONE_VFORK) { 1518 freezer_do_not_count(); 1519 wait_for_completion(&vfork); 1520 freezer_count(); 1521 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) { 1522 current->ptrace_message = nr; 1523 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); 1524 } 1525 } 1526 } else { 1527 nr = PTR_ERR(p); 1528 } 1529 return nr; 1530 } 1531 1532 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 1533 #define ARCH_MIN_MMSTRUCT_ALIGN 0 1534 #endif 1535 1536 static void sighand_ctor(struct kmem_cache *cachep, void *data) 1537 { 1538 struct sighand_struct *sighand = data; 1539 1540 spin_lock_init(&sighand->siglock); 1541 init_waitqueue_head(&sighand->signalfd_wqh); 1542 } 1543 1544 void __init proc_caches_init(void) 1545 { 1546 sighand_cachep = kmem_cache_create("sighand_cache", 1547 sizeof(struct sighand_struct), 0, 1548 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, 1549 sighand_ctor); 1550 signal_cachep = kmem_cache_create("signal_cache", 1551 sizeof(struct signal_struct), 0, 1552 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1553 files_cachep = kmem_cache_create("files_cache", 1554 sizeof(struct files_struct), 0, 1555 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1556 fs_cachep = kmem_cache_create("fs_cache", 1557 sizeof(struct fs_struct), 0, 1558 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1559 vm_area_cachep = kmem_cache_create("vm_area_struct", 1560 sizeof(struct vm_area_struct), 0, 1561 SLAB_PANIC, NULL); 1562 mm_cachep = kmem_cache_create("mm_struct", 1563 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 1564 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1565 } 1566 1567 /* 1568 * Check constraints on flags passed to the unshare system call and 1569 * force unsharing of additional process context as appropriate. 1570 */ 1571 static void check_unshare_flags(unsigned long *flags_ptr) 1572 { 1573 /* 1574 * If unsharing a thread from a thread group, must also 1575 * unshare vm. 1576 */ 1577 if (*flags_ptr & CLONE_THREAD) 1578 *flags_ptr |= CLONE_VM; 1579 1580 /* 1581 * If unsharing vm, must also unshare signal handlers. 1582 */ 1583 if (*flags_ptr & CLONE_VM) 1584 *flags_ptr |= CLONE_SIGHAND; 1585 1586 /* 1587 * If unsharing signal handlers and the task was created 1588 * using CLONE_THREAD, then must unshare the thread 1589 */ 1590 if ((*flags_ptr & CLONE_SIGHAND) && 1591 (atomic_read(¤t->signal->count) > 1)) 1592 *flags_ptr |= CLONE_THREAD; 1593 1594 /* 1595 * If unsharing namespace, must also unshare filesystem information. 1596 */ 1597 if (*flags_ptr & CLONE_NEWNS) 1598 *flags_ptr |= CLONE_FS; 1599 } 1600 1601 /* 1602 * Unsharing of tasks created with CLONE_THREAD is not supported yet 1603 */ 1604 static int unshare_thread(unsigned long unshare_flags) 1605 { 1606 if (unshare_flags & CLONE_THREAD) 1607 return -EINVAL; 1608 1609 return 0; 1610 } 1611 1612 /* 1613 * Unshare the filesystem structure if it is being shared 1614 */ 1615 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 1616 { 1617 struct fs_struct *fs = current->fs; 1618 1619 if ((unshare_flags & CLONE_FS) && 1620 (fs && atomic_read(&fs->count) > 1)) { 1621 *new_fsp = __copy_fs_struct(current->fs); 1622 if (!*new_fsp) 1623 return -ENOMEM; 1624 } 1625 1626 return 0; 1627 } 1628 1629 /* 1630 * Unsharing of sighand is not supported yet 1631 */ 1632 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) 1633 { 1634 struct sighand_struct *sigh = current->sighand; 1635 1636 if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) 1637 return -EINVAL; 1638 else 1639 return 0; 1640 } 1641 1642 /* 1643 * Unshare vm if it is being shared 1644 */ 1645 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) 1646 { 1647 struct mm_struct *mm = current->mm; 1648 1649 if ((unshare_flags & CLONE_VM) && 1650 (mm && atomic_read(&mm->mm_users) > 1)) { 1651 return -EINVAL; 1652 } 1653 1654 return 0; 1655 } 1656 1657 /* 1658 * Unshare file descriptor table if it is being shared 1659 */ 1660 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 1661 { 1662 struct files_struct *fd = current->files; 1663 int error = 0; 1664 1665 if ((unshare_flags & CLONE_FILES) && 1666 (fd && atomic_read(&fd->count) > 1)) { 1667 *new_fdp = dup_fd(fd, &error); 1668 if (!*new_fdp) 1669 return error; 1670 } 1671 1672 return 0; 1673 } 1674 1675 /* 1676 * unshare allows a process to 'unshare' part of the process 1677 * context which was originally shared using clone. copy_* 1678 * functions used by do_fork() cannot be used here directly 1679 * because they modify an inactive task_struct that is being 1680 * constructed. Here we are modifying the current, active, 1681 * task_struct. 1682 */ 1683 asmlinkage long sys_unshare(unsigned long unshare_flags) 1684 { 1685 int err = 0; 1686 struct fs_struct *fs, *new_fs = NULL; 1687 struct sighand_struct *new_sigh = NULL; 1688 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; 1689 struct files_struct *fd, *new_fd = NULL; 1690 struct nsproxy *new_nsproxy = NULL; 1691 int do_sysvsem = 0; 1692 1693 check_unshare_flags(&unshare_flags); 1694 1695 /* Return -EINVAL for all unsupported flags */ 1696 err = -EINVAL; 1697 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 1698 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 1699 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER| 1700 CLONE_NEWNET)) 1701 goto bad_unshare_out; 1702 1703 /* 1704 * CLONE_NEWIPC must also detach from the undolist: after switching 1705 * to a new ipc namespace, the semaphore arrays from the old 1706 * namespace are unreachable. 1707 */ 1708 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) 1709 do_sysvsem = 1; 1710 if ((err = unshare_thread(unshare_flags))) 1711 goto bad_unshare_out; 1712 if ((err = unshare_fs(unshare_flags, &new_fs))) 1713 goto bad_unshare_cleanup_thread; 1714 if ((err = unshare_sighand(unshare_flags, &new_sigh))) 1715 goto bad_unshare_cleanup_fs; 1716 if ((err = unshare_vm(unshare_flags, &new_mm))) 1717 goto bad_unshare_cleanup_sigh; 1718 if ((err = unshare_fd(unshare_flags, &new_fd))) 1719 goto bad_unshare_cleanup_vm; 1720 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 1721 new_fs))) 1722 goto bad_unshare_cleanup_fd; 1723 1724 if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) { 1725 if (do_sysvsem) { 1726 /* 1727 * CLONE_SYSVSEM is equivalent to sys_exit(). 1728 */ 1729 exit_sem(current); 1730 } 1731 1732 if (new_nsproxy) { 1733 switch_task_namespaces(current, new_nsproxy); 1734 new_nsproxy = NULL; 1735 } 1736 1737 task_lock(current); 1738 1739 if (new_fs) { 1740 fs = current->fs; 1741 current->fs = new_fs; 1742 new_fs = fs; 1743 } 1744 1745 if (new_mm) { 1746 mm = current->mm; 1747 active_mm = current->active_mm; 1748 current->mm = new_mm; 1749 current->active_mm = new_mm; 1750 activate_mm(active_mm, new_mm); 1751 new_mm = mm; 1752 } 1753 1754 if (new_fd) { 1755 fd = current->files; 1756 current->files = new_fd; 1757 new_fd = fd; 1758 } 1759 1760 task_unlock(current); 1761 } 1762 1763 if (new_nsproxy) 1764 put_nsproxy(new_nsproxy); 1765 1766 bad_unshare_cleanup_fd: 1767 if (new_fd) 1768 put_files_struct(new_fd); 1769 1770 bad_unshare_cleanup_vm: 1771 if (new_mm) 1772 mmput(new_mm); 1773 1774 bad_unshare_cleanup_sigh: 1775 if (new_sigh) 1776 if (atomic_dec_and_test(&new_sigh->count)) 1777 kmem_cache_free(sighand_cachep, new_sigh); 1778 1779 bad_unshare_cleanup_fs: 1780 if (new_fs) 1781 put_fs_struct(new_fs); 1782 1783 bad_unshare_cleanup_thread: 1784 bad_unshare_out: 1785 return err; 1786 } 1787 1788 /* 1789 * Helper to unshare the files of the current task. 1790 * We don't want to expose copy_files internals to 1791 * the exec layer of the kernel. 1792 */ 1793 1794 int unshare_files(struct files_struct **displaced) 1795 { 1796 struct task_struct *task = current; 1797 struct files_struct *copy = NULL; 1798 int error; 1799 1800 error = unshare_fd(CLONE_FILES, ©); 1801 if (error || !copy) { 1802 *displaced = NULL; 1803 return error; 1804 } 1805 *displaced = task->files; 1806 task_lock(task); 1807 task->files = copy; 1808 task_unlock(task); 1809 return 0; 1810 } 1811