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/smp_lock.h> 18 #include <linux/module.h> 19 #include <linux/vmalloc.h> 20 #include <linux/completion.h> 21 #include <linux/namespace.h> 22 #include <linux/personality.h> 23 #include <linux/mempolicy.h> 24 #include <linux/sem.h> 25 #include <linux/file.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/cpuset.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/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/delayacct.h> 49 #include <linux/taskstats_kern.h> 50 #include <linux/random.h> 51 52 #include <asm/pgtable.h> 53 #include <asm/pgalloc.h> 54 #include <asm/uaccess.h> 55 #include <asm/mmu_context.h> 56 #include <asm/cacheflush.h> 57 #include <asm/tlbflush.h> 58 59 /* 60 * Protected counters by write_lock_irq(&tasklist_lock) 61 */ 62 unsigned long total_forks; /* Handle normal Linux uptimes. */ 63 int nr_threads; /* The idle threads do not count.. */ 64 65 int max_threads; /* tunable limit on nr_threads */ 66 67 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 68 69 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 70 71 int nr_processes(void) 72 { 73 int cpu; 74 int total = 0; 75 76 for_each_online_cpu(cpu) 77 total += per_cpu(process_counts, cpu); 78 79 return total; 80 } 81 82 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 83 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) 84 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) 85 static kmem_cache_t *task_struct_cachep; 86 #endif 87 88 /* SLAB cache for signal_struct structures (tsk->signal) */ 89 static kmem_cache_t *signal_cachep; 90 91 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 92 kmem_cache_t *sighand_cachep; 93 94 /* SLAB cache for files_struct structures (tsk->files) */ 95 kmem_cache_t *files_cachep; 96 97 /* SLAB cache for fs_struct structures (tsk->fs) */ 98 kmem_cache_t *fs_cachep; 99 100 /* SLAB cache for vm_area_struct structures */ 101 kmem_cache_t *vm_area_cachep; 102 103 /* SLAB cache for mm_struct structures (tsk->mm) */ 104 static kmem_cache_t *mm_cachep; 105 106 void free_task(struct task_struct *tsk) 107 { 108 free_thread_info(tsk->thread_info); 109 rt_mutex_debug_task_free(tsk); 110 free_task_struct(tsk); 111 } 112 EXPORT_SYMBOL(free_task); 113 114 void __put_task_struct(struct task_struct *tsk) 115 { 116 WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE))); 117 WARN_ON(atomic_read(&tsk->usage)); 118 WARN_ON(tsk == current); 119 120 security_task_free(tsk); 121 free_uid(tsk->user); 122 put_group_info(tsk->group_info); 123 delayacct_tsk_free(tsk); 124 125 if (!profile_handoff_task(tsk)) 126 free_task(tsk); 127 } 128 129 void __init fork_init(unsigned long mempages) 130 { 131 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 132 #ifndef ARCH_MIN_TASKALIGN 133 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES 134 #endif 135 /* create a slab on which task_structs can be allocated */ 136 task_struct_cachep = 137 kmem_cache_create("task_struct", sizeof(struct task_struct), 138 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL); 139 #endif 140 141 /* 142 * The default maximum number of threads is set to a safe 143 * value: the thread structures can take up at most half 144 * of memory. 145 */ 146 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); 147 148 /* 149 * we need to allow at least 20 threads to boot a system 150 */ 151 if(max_threads < 20) 152 max_threads = 20; 153 154 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 155 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 156 init_task.signal->rlim[RLIMIT_SIGPENDING] = 157 init_task.signal->rlim[RLIMIT_NPROC]; 158 } 159 160 static struct task_struct *dup_task_struct(struct task_struct *orig) 161 { 162 struct task_struct *tsk; 163 struct thread_info *ti; 164 165 prepare_to_copy(orig); 166 167 tsk = alloc_task_struct(); 168 if (!tsk) 169 return NULL; 170 171 ti = alloc_thread_info(tsk); 172 if (!ti) { 173 free_task_struct(tsk); 174 return NULL; 175 } 176 177 *tsk = *orig; 178 tsk->thread_info = ti; 179 setup_thread_stack(tsk, orig); 180 181 #ifdef CONFIG_CC_STACKPROTECTOR 182 tsk->stack_canary = get_random_int(); 183 #endif 184 185 /* One for us, one for whoever does the "release_task()" (usually parent) */ 186 atomic_set(&tsk->usage,2); 187 atomic_set(&tsk->fs_excl, 0); 188 #ifdef CONFIG_BLK_DEV_IO_TRACE 189 tsk->btrace_seq = 0; 190 #endif 191 tsk->splice_pipe = NULL; 192 return tsk; 193 } 194 195 #ifdef CONFIG_MMU 196 static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 197 { 198 struct vm_area_struct *mpnt, *tmp, **pprev; 199 struct rb_node **rb_link, *rb_parent; 200 int retval; 201 unsigned long charge; 202 struct mempolicy *pol; 203 204 down_write(&oldmm->mmap_sem); 205 flush_cache_mm(oldmm); 206 /* 207 * Not linked in yet - no deadlock potential: 208 */ 209 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); 210 211 mm->locked_vm = 0; 212 mm->mmap = NULL; 213 mm->mmap_cache = NULL; 214 mm->free_area_cache = oldmm->mmap_base; 215 mm->cached_hole_size = ~0UL; 216 mm->map_count = 0; 217 cpus_clear(mm->cpu_vm_mask); 218 mm->mm_rb = RB_ROOT; 219 rb_link = &mm->mm_rb.rb_node; 220 rb_parent = NULL; 221 pprev = &mm->mmap; 222 223 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 224 struct file *file; 225 226 if (mpnt->vm_flags & VM_DONTCOPY) { 227 long pages = vma_pages(mpnt); 228 mm->total_vm -= pages; 229 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, 230 -pages); 231 continue; 232 } 233 charge = 0; 234 if (mpnt->vm_flags & VM_ACCOUNT) { 235 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; 236 if (security_vm_enough_memory(len)) 237 goto fail_nomem; 238 charge = len; 239 } 240 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 241 if (!tmp) 242 goto fail_nomem; 243 *tmp = *mpnt; 244 pol = mpol_copy(vma_policy(mpnt)); 245 retval = PTR_ERR(pol); 246 if (IS_ERR(pol)) 247 goto fail_nomem_policy; 248 vma_set_policy(tmp, pol); 249 tmp->vm_flags &= ~VM_LOCKED; 250 tmp->vm_mm = mm; 251 tmp->vm_next = NULL; 252 anon_vma_link(tmp); 253 file = tmp->vm_file; 254 if (file) { 255 struct inode *inode = file->f_dentry->d_inode; 256 get_file(file); 257 if (tmp->vm_flags & VM_DENYWRITE) 258 atomic_dec(&inode->i_writecount); 259 260 /* insert tmp into the share list, just after mpnt */ 261 spin_lock(&file->f_mapping->i_mmap_lock); 262 tmp->vm_truncate_count = mpnt->vm_truncate_count; 263 flush_dcache_mmap_lock(file->f_mapping); 264 vma_prio_tree_add(tmp, mpnt); 265 flush_dcache_mmap_unlock(file->f_mapping); 266 spin_unlock(&file->f_mapping->i_mmap_lock); 267 } 268 269 /* 270 * Link in the new vma and copy the page table entries. 271 */ 272 *pprev = tmp; 273 pprev = &tmp->vm_next; 274 275 __vma_link_rb(mm, tmp, rb_link, rb_parent); 276 rb_link = &tmp->vm_rb.rb_right; 277 rb_parent = &tmp->vm_rb; 278 279 mm->map_count++; 280 retval = copy_page_range(mm, oldmm, mpnt); 281 282 if (tmp->vm_ops && tmp->vm_ops->open) 283 tmp->vm_ops->open(tmp); 284 285 if (retval) 286 goto out; 287 } 288 retval = 0; 289 out: 290 up_write(&mm->mmap_sem); 291 flush_tlb_mm(oldmm); 292 up_write(&oldmm->mmap_sem); 293 return retval; 294 fail_nomem_policy: 295 kmem_cache_free(vm_area_cachep, tmp); 296 fail_nomem: 297 retval = -ENOMEM; 298 vm_unacct_memory(charge); 299 goto out; 300 } 301 302 static inline int mm_alloc_pgd(struct mm_struct * mm) 303 { 304 mm->pgd = pgd_alloc(mm); 305 if (unlikely(!mm->pgd)) 306 return -ENOMEM; 307 return 0; 308 } 309 310 static inline void mm_free_pgd(struct mm_struct * mm) 311 { 312 pgd_free(mm->pgd); 313 } 314 #else 315 #define dup_mmap(mm, oldmm) (0) 316 #define mm_alloc_pgd(mm) (0) 317 #define mm_free_pgd(mm) 318 #endif /* CONFIG_MMU */ 319 320 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 321 322 #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL)) 323 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 324 325 #include <linux/init_task.h> 326 327 static struct mm_struct * mm_init(struct mm_struct * mm) 328 { 329 atomic_set(&mm->mm_users, 1); 330 atomic_set(&mm->mm_count, 1); 331 init_rwsem(&mm->mmap_sem); 332 INIT_LIST_HEAD(&mm->mmlist); 333 mm->core_waiters = 0; 334 mm->nr_ptes = 0; 335 set_mm_counter(mm, file_rss, 0); 336 set_mm_counter(mm, anon_rss, 0); 337 spin_lock_init(&mm->page_table_lock); 338 rwlock_init(&mm->ioctx_list_lock); 339 mm->ioctx_list = NULL; 340 mm->free_area_cache = TASK_UNMAPPED_BASE; 341 mm->cached_hole_size = ~0UL; 342 343 if (likely(!mm_alloc_pgd(mm))) { 344 mm->def_flags = 0; 345 return mm; 346 } 347 free_mm(mm); 348 return NULL; 349 } 350 351 /* 352 * Allocate and initialize an mm_struct. 353 */ 354 struct mm_struct * mm_alloc(void) 355 { 356 struct mm_struct * mm; 357 358 mm = allocate_mm(); 359 if (mm) { 360 memset(mm, 0, sizeof(*mm)); 361 mm = mm_init(mm); 362 } 363 return mm; 364 } 365 366 /* 367 * Called when the last reference to the mm 368 * is dropped: either by a lazy thread or by 369 * mmput. Free the page directory and the mm. 370 */ 371 void fastcall __mmdrop(struct mm_struct *mm) 372 { 373 BUG_ON(mm == &init_mm); 374 mm_free_pgd(mm); 375 destroy_context(mm); 376 free_mm(mm); 377 } 378 379 /* 380 * Decrement the use count and release all resources for an mm. 381 */ 382 void mmput(struct mm_struct *mm) 383 { 384 might_sleep(); 385 386 if (atomic_dec_and_test(&mm->mm_users)) { 387 exit_aio(mm); 388 exit_mmap(mm); 389 if (!list_empty(&mm->mmlist)) { 390 spin_lock(&mmlist_lock); 391 list_del(&mm->mmlist); 392 spin_unlock(&mmlist_lock); 393 } 394 put_swap_token(mm); 395 mmdrop(mm); 396 } 397 } 398 EXPORT_SYMBOL_GPL(mmput); 399 400 /** 401 * get_task_mm - acquire a reference to the task's mm 402 * 403 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning 404 * this kernel workthread has transiently adopted a user mm with use_mm, 405 * to do its AIO) is not set and if so returns a reference to it, after 406 * bumping up the use count. User must release the mm via mmput() 407 * after use. Typically used by /proc and ptrace. 408 */ 409 struct mm_struct *get_task_mm(struct task_struct *task) 410 { 411 struct mm_struct *mm; 412 413 task_lock(task); 414 mm = task->mm; 415 if (mm) { 416 if (task->flags & PF_BORROWED_MM) 417 mm = NULL; 418 else 419 atomic_inc(&mm->mm_users); 420 } 421 task_unlock(task); 422 return mm; 423 } 424 EXPORT_SYMBOL_GPL(get_task_mm); 425 426 /* Please note the differences between mmput and mm_release. 427 * mmput is called whenever we stop holding onto a mm_struct, 428 * error success whatever. 429 * 430 * mm_release is called after a mm_struct has been removed 431 * from the current process. 432 * 433 * This difference is important for error handling, when we 434 * only half set up a mm_struct for a new process and need to restore 435 * the old one. Because we mmput the new mm_struct before 436 * restoring the old one. . . 437 * Eric Biederman 10 January 1998 438 */ 439 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 440 { 441 struct completion *vfork_done = tsk->vfork_done; 442 443 /* Get rid of any cached register state */ 444 deactivate_mm(tsk, mm); 445 446 /* notify parent sleeping on vfork() */ 447 if (vfork_done) { 448 tsk->vfork_done = NULL; 449 complete(vfork_done); 450 } 451 if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) { 452 u32 __user * tidptr = tsk->clear_child_tid; 453 tsk->clear_child_tid = NULL; 454 455 /* 456 * We don't check the error code - if userspace has 457 * not set up a proper pointer then tough luck. 458 */ 459 put_user(0, tidptr); 460 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); 461 } 462 } 463 464 /* 465 * Allocate a new mm structure and copy contents from the 466 * mm structure of the passed in task structure. 467 */ 468 static struct mm_struct *dup_mm(struct task_struct *tsk) 469 { 470 struct mm_struct *mm, *oldmm = current->mm; 471 int err; 472 473 if (!oldmm) 474 return NULL; 475 476 mm = allocate_mm(); 477 if (!mm) 478 goto fail_nomem; 479 480 memcpy(mm, oldmm, sizeof(*mm)); 481 482 if (!mm_init(mm)) 483 goto fail_nomem; 484 485 if (init_new_context(tsk, mm)) 486 goto fail_nocontext; 487 488 err = dup_mmap(mm, oldmm); 489 if (err) 490 goto free_pt; 491 492 mm->hiwater_rss = get_mm_rss(mm); 493 mm->hiwater_vm = mm->total_vm; 494 495 return mm; 496 497 free_pt: 498 mmput(mm); 499 500 fail_nomem: 501 return NULL; 502 503 fail_nocontext: 504 /* 505 * If init_new_context() failed, we cannot use mmput() to free the mm 506 * because it calls destroy_context() 507 */ 508 mm_free_pgd(mm); 509 free_mm(mm); 510 return NULL; 511 } 512 513 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) 514 { 515 struct mm_struct * mm, *oldmm; 516 int retval; 517 518 tsk->min_flt = tsk->maj_flt = 0; 519 tsk->nvcsw = tsk->nivcsw = 0; 520 521 tsk->mm = NULL; 522 tsk->active_mm = NULL; 523 524 /* 525 * Are we cloning a kernel thread? 526 * 527 * We need to steal a active VM for that.. 528 */ 529 oldmm = current->mm; 530 if (!oldmm) 531 return 0; 532 533 if (clone_flags & CLONE_VM) { 534 atomic_inc(&oldmm->mm_users); 535 mm = oldmm; 536 goto good_mm; 537 } 538 539 retval = -ENOMEM; 540 mm = dup_mm(tsk); 541 if (!mm) 542 goto fail_nomem; 543 544 good_mm: 545 tsk->mm = mm; 546 tsk->active_mm = mm; 547 return 0; 548 549 fail_nomem: 550 return retval; 551 } 552 553 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old) 554 { 555 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); 556 /* We don't need to lock fs - think why ;-) */ 557 if (fs) { 558 atomic_set(&fs->count, 1); 559 rwlock_init(&fs->lock); 560 fs->umask = old->umask; 561 read_lock(&old->lock); 562 fs->rootmnt = mntget(old->rootmnt); 563 fs->root = dget(old->root); 564 fs->pwdmnt = mntget(old->pwdmnt); 565 fs->pwd = dget(old->pwd); 566 if (old->altroot) { 567 fs->altrootmnt = mntget(old->altrootmnt); 568 fs->altroot = dget(old->altroot); 569 } else { 570 fs->altrootmnt = NULL; 571 fs->altroot = NULL; 572 } 573 read_unlock(&old->lock); 574 } 575 return fs; 576 } 577 578 struct fs_struct *copy_fs_struct(struct fs_struct *old) 579 { 580 return __copy_fs_struct(old); 581 } 582 583 EXPORT_SYMBOL_GPL(copy_fs_struct); 584 585 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk) 586 { 587 if (clone_flags & CLONE_FS) { 588 atomic_inc(¤t->fs->count); 589 return 0; 590 } 591 tsk->fs = __copy_fs_struct(current->fs); 592 if (!tsk->fs) 593 return -ENOMEM; 594 return 0; 595 } 596 597 static int count_open_files(struct fdtable *fdt) 598 { 599 int size = fdt->max_fdset; 600 int i; 601 602 /* Find the last open fd */ 603 for (i = size/(8*sizeof(long)); i > 0; ) { 604 if (fdt->open_fds->fds_bits[--i]) 605 break; 606 } 607 i = (i+1) * 8 * sizeof(long); 608 return i; 609 } 610 611 static struct files_struct *alloc_files(void) 612 { 613 struct files_struct *newf; 614 struct fdtable *fdt; 615 616 newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL); 617 if (!newf) 618 goto out; 619 620 atomic_set(&newf->count, 1); 621 622 spin_lock_init(&newf->file_lock); 623 newf->next_fd = 0; 624 fdt = &newf->fdtab; 625 fdt->max_fds = NR_OPEN_DEFAULT; 626 fdt->max_fdset = EMBEDDED_FD_SET_SIZE; 627 fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init; 628 fdt->open_fds = (fd_set *)&newf->open_fds_init; 629 fdt->fd = &newf->fd_array[0]; 630 INIT_RCU_HEAD(&fdt->rcu); 631 fdt->free_files = NULL; 632 fdt->next = NULL; 633 rcu_assign_pointer(newf->fdt, fdt); 634 out: 635 return newf; 636 } 637 638 /* 639 * Allocate a new files structure and copy contents from the 640 * passed in files structure. 641 * errorp will be valid only when the returned files_struct is NULL. 642 */ 643 static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) 644 { 645 struct files_struct *newf; 646 struct file **old_fds, **new_fds; 647 int open_files, size, i, expand; 648 struct fdtable *old_fdt, *new_fdt; 649 650 *errorp = -ENOMEM; 651 newf = alloc_files(); 652 if (!newf) 653 goto out; 654 655 spin_lock(&oldf->file_lock); 656 old_fdt = files_fdtable(oldf); 657 new_fdt = files_fdtable(newf); 658 size = old_fdt->max_fdset; 659 open_files = count_open_files(old_fdt); 660 expand = 0; 661 662 /* 663 * Check whether we need to allocate a larger fd array or fd set. 664 * Note: we're not a clone task, so the open count won't change. 665 */ 666 if (open_files > new_fdt->max_fdset) { 667 new_fdt->max_fdset = 0; 668 expand = 1; 669 } 670 if (open_files > new_fdt->max_fds) { 671 new_fdt->max_fds = 0; 672 expand = 1; 673 } 674 675 /* if the old fdset gets grown now, we'll only copy up to "size" fds */ 676 if (expand) { 677 spin_unlock(&oldf->file_lock); 678 spin_lock(&newf->file_lock); 679 *errorp = expand_files(newf, open_files-1); 680 spin_unlock(&newf->file_lock); 681 if (*errorp < 0) 682 goto out_release; 683 new_fdt = files_fdtable(newf); 684 /* 685 * Reacquire the oldf lock and a pointer to its fd table 686 * who knows it may have a new bigger fd table. We need 687 * the latest pointer. 688 */ 689 spin_lock(&oldf->file_lock); 690 old_fdt = files_fdtable(oldf); 691 } 692 693 old_fds = old_fdt->fd; 694 new_fds = new_fdt->fd; 695 696 memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8); 697 memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8); 698 699 for (i = open_files; i != 0; i--) { 700 struct file *f = *old_fds++; 701 if (f) { 702 get_file(f); 703 } else { 704 /* 705 * The fd may be claimed in the fd bitmap but not yet 706 * instantiated in the files array if a sibling thread 707 * is partway through open(). So make sure that this 708 * fd is available to the new process. 709 */ 710 FD_CLR(open_files - i, new_fdt->open_fds); 711 } 712 rcu_assign_pointer(*new_fds++, f); 713 } 714 spin_unlock(&oldf->file_lock); 715 716 /* compute the remainder to be cleared */ 717 size = (new_fdt->max_fds - open_files) * sizeof(struct file *); 718 719 /* This is long word aligned thus could use a optimized version */ 720 memset(new_fds, 0, size); 721 722 if (new_fdt->max_fdset > open_files) { 723 int left = (new_fdt->max_fdset-open_files)/8; 724 int start = open_files / (8 * sizeof(unsigned long)); 725 726 memset(&new_fdt->open_fds->fds_bits[start], 0, left); 727 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); 728 } 729 730 out: 731 return newf; 732 733 out_release: 734 free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset); 735 free_fdset (new_fdt->open_fds, new_fdt->max_fdset); 736 free_fd_array(new_fdt->fd, new_fdt->max_fds); 737 kmem_cache_free(files_cachep, newf); 738 return NULL; 739 } 740 741 static int copy_files(unsigned long clone_flags, struct task_struct * tsk) 742 { 743 struct files_struct *oldf, *newf; 744 int error = 0; 745 746 /* 747 * A background process may not have any files ... 748 */ 749 oldf = current->files; 750 if (!oldf) 751 goto out; 752 753 if (clone_flags & CLONE_FILES) { 754 atomic_inc(&oldf->count); 755 goto out; 756 } 757 758 /* 759 * Note: we may be using current for both targets (See exec.c) 760 * This works because we cache current->files (old) as oldf. Don't 761 * break this. 762 */ 763 tsk->files = NULL; 764 newf = dup_fd(oldf, &error); 765 if (!newf) 766 goto out; 767 768 tsk->files = newf; 769 error = 0; 770 out: 771 return error; 772 } 773 774 /* 775 * Helper to unshare the files of the current task. 776 * We don't want to expose copy_files internals to 777 * the exec layer of the kernel. 778 */ 779 780 int unshare_files(void) 781 { 782 struct files_struct *files = current->files; 783 int rc; 784 785 BUG_ON(!files); 786 787 /* This can race but the race causes us to copy when we don't 788 need to and drop the copy */ 789 if(atomic_read(&files->count) == 1) 790 { 791 atomic_inc(&files->count); 792 return 0; 793 } 794 rc = copy_files(0, current); 795 if(rc) 796 current->files = files; 797 return rc; 798 } 799 800 EXPORT_SYMBOL(unshare_files); 801 802 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk) 803 { 804 struct sighand_struct *sig; 805 806 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { 807 atomic_inc(¤t->sighand->count); 808 return 0; 809 } 810 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 811 rcu_assign_pointer(tsk->sighand, sig); 812 if (!sig) 813 return -ENOMEM; 814 atomic_set(&sig->count, 1); 815 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 816 return 0; 817 } 818 819 void __cleanup_sighand(struct sighand_struct *sighand) 820 { 821 if (atomic_dec_and_test(&sighand->count)) 822 kmem_cache_free(sighand_cachep, sighand); 823 } 824 825 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk) 826 { 827 struct signal_struct *sig; 828 int ret; 829 830 if (clone_flags & CLONE_THREAD) { 831 atomic_inc(¤t->signal->count); 832 atomic_inc(¤t->signal->live); 833 taskstats_tgid_alloc(current->signal); 834 return 0; 835 } 836 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); 837 tsk->signal = sig; 838 if (!sig) 839 return -ENOMEM; 840 841 ret = copy_thread_group_keys(tsk); 842 if (ret < 0) { 843 kmem_cache_free(signal_cachep, sig); 844 return ret; 845 } 846 847 atomic_set(&sig->count, 1); 848 atomic_set(&sig->live, 1); 849 init_waitqueue_head(&sig->wait_chldexit); 850 sig->flags = 0; 851 sig->group_exit_code = 0; 852 sig->group_exit_task = NULL; 853 sig->group_stop_count = 0; 854 sig->curr_target = NULL; 855 init_sigpending(&sig->shared_pending); 856 INIT_LIST_HEAD(&sig->posix_timers); 857 858 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL); 859 sig->it_real_incr.tv64 = 0; 860 sig->real_timer.function = it_real_fn; 861 sig->tsk = tsk; 862 863 sig->it_virt_expires = cputime_zero; 864 sig->it_virt_incr = cputime_zero; 865 sig->it_prof_expires = cputime_zero; 866 sig->it_prof_incr = cputime_zero; 867 868 sig->leader = 0; /* session leadership doesn't inherit */ 869 sig->tty_old_pgrp = 0; 870 871 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; 872 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; 873 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; 874 sig->sched_time = 0; 875 INIT_LIST_HEAD(&sig->cpu_timers[0]); 876 INIT_LIST_HEAD(&sig->cpu_timers[1]); 877 INIT_LIST_HEAD(&sig->cpu_timers[2]); 878 taskstats_tgid_init(sig); 879 880 task_lock(current->group_leader); 881 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 882 task_unlock(current->group_leader); 883 884 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { 885 /* 886 * New sole thread in the process gets an expiry time 887 * of the whole CPU time limit. 888 */ 889 tsk->it_prof_expires = 890 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); 891 } 892 acct_init_pacct(&sig->pacct); 893 894 return 0; 895 } 896 897 void __cleanup_signal(struct signal_struct *sig) 898 { 899 exit_thread_group_keys(sig); 900 taskstats_tgid_free(sig); 901 kmem_cache_free(signal_cachep, sig); 902 } 903 904 static inline void cleanup_signal(struct task_struct *tsk) 905 { 906 struct signal_struct *sig = tsk->signal; 907 908 atomic_dec(&sig->live); 909 910 if (atomic_dec_and_test(&sig->count)) 911 __cleanup_signal(sig); 912 } 913 914 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) 915 { 916 unsigned long new_flags = p->flags; 917 918 new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE); 919 new_flags |= PF_FORKNOEXEC; 920 if (!(clone_flags & CLONE_PTRACE)) 921 p->ptrace = 0; 922 p->flags = new_flags; 923 } 924 925 asmlinkage long sys_set_tid_address(int __user *tidptr) 926 { 927 current->clear_child_tid = tidptr; 928 929 return current->pid; 930 } 931 932 static inline void rt_mutex_init_task(struct task_struct *p) 933 { 934 #ifdef CONFIG_RT_MUTEXES 935 spin_lock_init(&p->pi_lock); 936 plist_head_init(&p->pi_waiters, &p->pi_lock); 937 p->pi_blocked_on = NULL; 938 #endif 939 } 940 941 /* 942 * This creates a new process as a copy of the old one, 943 * but does not actually start it yet. 944 * 945 * It copies the registers, and all the appropriate 946 * parts of the process environment (as per the clone 947 * flags). The actual kick-off is left to the caller. 948 */ 949 static struct task_struct *copy_process(unsigned long clone_flags, 950 unsigned long stack_start, 951 struct pt_regs *regs, 952 unsigned long stack_size, 953 int __user *parent_tidptr, 954 int __user *child_tidptr, 955 int pid) 956 { 957 int retval; 958 struct task_struct *p = NULL; 959 960 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 961 return ERR_PTR(-EINVAL); 962 963 /* 964 * Thread groups must share signals as well, and detached threads 965 * can only be started up within the thread group. 966 */ 967 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 968 return ERR_PTR(-EINVAL); 969 970 /* 971 * Shared signal handlers imply shared VM. By way of the above, 972 * thread groups also imply shared VM. Blocking this case allows 973 * for various simplifications in other code. 974 */ 975 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 976 return ERR_PTR(-EINVAL); 977 978 retval = security_task_create(clone_flags); 979 if (retval) 980 goto fork_out; 981 982 retval = -ENOMEM; 983 p = dup_task_struct(current); 984 if (!p) 985 goto fork_out; 986 987 #ifdef CONFIG_TRACE_IRQFLAGS 988 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 989 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 990 #endif 991 retval = -EAGAIN; 992 if (atomic_read(&p->user->processes) >= 993 p->signal->rlim[RLIMIT_NPROC].rlim_cur) { 994 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && 995 p->user != &root_user) 996 goto bad_fork_free; 997 } 998 999 atomic_inc(&p->user->__count); 1000 atomic_inc(&p->user->processes); 1001 get_group_info(p->group_info); 1002 1003 /* 1004 * If multiple threads are within copy_process(), then this check 1005 * triggers too late. This doesn't hurt, the check is only there 1006 * to stop root fork bombs. 1007 */ 1008 if (nr_threads >= max_threads) 1009 goto bad_fork_cleanup_count; 1010 1011 if (!try_module_get(task_thread_info(p)->exec_domain->module)) 1012 goto bad_fork_cleanup_count; 1013 1014 if (p->binfmt && !try_module_get(p->binfmt->module)) 1015 goto bad_fork_cleanup_put_domain; 1016 1017 p->did_exec = 0; 1018 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1019 copy_flags(clone_flags, p); 1020 p->pid = pid; 1021 retval = -EFAULT; 1022 if (clone_flags & CLONE_PARENT_SETTID) 1023 if (put_user(p->pid, parent_tidptr)) 1024 goto bad_fork_cleanup_delays_binfmt; 1025 1026 INIT_LIST_HEAD(&p->children); 1027 INIT_LIST_HEAD(&p->sibling); 1028 p->vfork_done = NULL; 1029 spin_lock_init(&p->alloc_lock); 1030 1031 clear_tsk_thread_flag(p, TIF_SIGPENDING); 1032 init_sigpending(&p->pending); 1033 1034 p->utime = cputime_zero; 1035 p->stime = cputime_zero; 1036 p->sched_time = 0; 1037 p->rchar = 0; /* I/O counter: bytes read */ 1038 p->wchar = 0; /* I/O counter: bytes written */ 1039 p->syscr = 0; /* I/O counter: read syscalls */ 1040 p->syscw = 0; /* I/O counter: write syscalls */ 1041 acct_clear_integrals(p); 1042 1043 p->it_virt_expires = cputime_zero; 1044 p->it_prof_expires = cputime_zero; 1045 p->it_sched_expires = 0; 1046 INIT_LIST_HEAD(&p->cpu_timers[0]); 1047 INIT_LIST_HEAD(&p->cpu_timers[1]); 1048 INIT_LIST_HEAD(&p->cpu_timers[2]); 1049 1050 p->lock_depth = -1; /* -1 = no lock */ 1051 do_posix_clock_monotonic_gettime(&p->start_time); 1052 p->security = NULL; 1053 p->io_context = NULL; 1054 p->io_wait = NULL; 1055 p->audit_context = NULL; 1056 cpuset_fork(p); 1057 #ifdef CONFIG_NUMA 1058 p->mempolicy = mpol_copy(p->mempolicy); 1059 if (IS_ERR(p->mempolicy)) { 1060 retval = PTR_ERR(p->mempolicy); 1061 p->mempolicy = NULL; 1062 goto bad_fork_cleanup_cpuset; 1063 } 1064 mpol_fix_fork_child_flag(p); 1065 #endif 1066 #ifdef CONFIG_TRACE_IRQFLAGS 1067 p->irq_events = 0; 1068 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1069 p->hardirqs_enabled = 1; 1070 #else 1071 p->hardirqs_enabled = 0; 1072 #endif 1073 p->hardirq_enable_ip = 0; 1074 p->hardirq_enable_event = 0; 1075 p->hardirq_disable_ip = _THIS_IP_; 1076 p->hardirq_disable_event = 0; 1077 p->softirqs_enabled = 1; 1078 p->softirq_enable_ip = _THIS_IP_; 1079 p->softirq_enable_event = 0; 1080 p->softirq_disable_ip = 0; 1081 p->softirq_disable_event = 0; 1082 p->hardirq_context = 0; 1083 p->softirq_context = 0; 1084 #endif 1085 #ifdef CONFIG_LOCKDEP 1086 p->lockdep_depth = 0; /* no locks held yet */ 1087 p->curr_chain_key = 0; 1088 p->lockdep_recursion = 0; 1089 #endif 1090 1091 rt_mutex_init_task(p); 1092 1093 #ifdef CONFIG_DEBUG_MUTEXES 1094 p->blocked_on = NULL; /* not blocked yet */ 1095 #endif 1096 1097 p->tgid = p->pid; 1098 if (clone_flags & CLONE_THREAD) 1099 p->tgid = current->tgid; 1100 1101 if ((retval = security_task_alloc(p))) 1102 goto bad_fork_cleanup_policy; 1103 if ((retval = audit_alloc(p))) 1104 goto bad_fork_cleanup_security; 1105 /* copy all the process information */ 1106 if ((retval = copy_semundo(clone_flags, p))) 1107 goto bad_fork_cleanup_audit; 1108 if ((retval = copy_files(clone_flags, p))) 1109 goto bad_fork_cleanup_semundo; 1110 if ((retval = copy_fs(clone_flags, p))) 1111 goto bad_fork_cleanup_files; 1112 if ((retval = copy_sighand(clone_flags, p))) 1113 goto bad_fork_cleanup_fs; 1114 if ((retval = copy_signal(clone_flags, p))) 1115 goto bad_fork_cleanup_sighand; 1116 if ((retval = copy_mm(clone_flags, p))) 1117 goto bad_fork_cleanup_signal; 1118 if ((retval = copy_keys(clone_flags, p))) 1119 goto bad_fork_cleanup_mm; 1120 if ((retval = copy_namespaces(clone_flags, p))) 1121 goto bad_fork_cleanup_keys; 1122 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); 1123 if (retval) 1124 goto bad_fork_cleanup_namespaces; 1125 1126 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1127 /* 1128 * Clear TID on mm_release()? 1129 */ 1130 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; 1131 p->robust_list = NULL; 1132 #ifdef CONFIG_COMPAT 1133 p->compat_robust_list = NULL; 1134 #endif 1135 INIT_LIST_HEAD(&p->pi_state_list); 1136 p->pi_state_cache = NULL; 1137 1138 /* 1139 * sigaltstack should be cleared when sharing the same VM 1140 */ 1141 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1142 p->sas_ss_sp = p->sas_ss_size = 0; 1143 1144 /* 1145 * Syscall tracing should be turned off in the child regardless 1146 * of CLONE_PTRACE. 1147 */ 1148 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1149 #ifdef TIF_SYSCALL_EMU 1150 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1151 #endif 1152 1153 /* Our parent execution domain becomes current domain 1154 These must match for thread signalling to apply */ 1155 p->parent_exec_id = p->self_exec_id; 1156 1157 /* ok, now we should be set up.. */ 1158 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); 1159 p->pdeath_signal = 0; 1160 p->exit_state = 0; 1161 1162 /* 1163 * Ok, make it visible to the rest of the system. 1164 * We dont wake it up yet. 1165 */ 1166 p->group_leader = p; 1167 INIT_LIST_HEAD(&p->thread_group); 1168 INIT_LIST_HEAD(&p->ptrace_children); 1169 INIT_LIST_HEAD(&p->ptrace_list); 1170 1171 /* Perform scheduler related setup. Assign this task to a CPU. */ 1172 sched_fork(p, clone_flags); 1173 1174 /* Need tasklist lock for parent etc handling! */ 1175 write_lock_irq(&tasklist_lock); 1176 1177 /* for sys_ioprio_set(IOPRIO_WHO_PGRP) */ 1178 p->ioprio = current->ioprio; 1179 1180 /* 1181 * The task hasn't been attached yet, so its cpus_allowed mask will 1182 * not be changed, nor will its assigned CPU. 1183 * 1184 * The cpus_allowed mask of the parent may have changed after it was 1185 * copied first time - so re-copy it here, then check the child's CPU 1186 * to ensure it is on a valid CPU (and if not, just force it back to 1187 * parent's CPU). This avoids alot of nasty races. 1188 */ 1189 p->cpus_allowed = current->cpus_allowed; 1190 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) || 1191 !cpu_online(task_cpu(p)))) 1192 set_task_cpu(p, smp_processor_id()); 1193 1194 /* CLONE_PARENT re-uses the old parent */ 1195 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) 1196 p->real_parent = current->real_parent; 1197 else 1198 p->real_parent = current; 1199 p->parent = p->real_parent; 1200 1201 spin_lock(¤t->sighand->siglock); 1202 1203 /* 1204 * Process group and session signals need to be delivered to just the 1205 * parent before the fork or both the parent and the child after the 1206 * fork. Restart if a signal comes in before we add the new process to 1207 * it's process group. 1208 * A fatal signal pending means that current will exit, so the new 1209 * thread can't slip out of an OOM kill (or normal SIGKILL). 1210 */ 1211 recalc_sigpending(); 1212 if (signal_pending(current)) { 1213 spin_unlock(¤t->sighand->siglock); 1214 write_unlock_irq(&tasklist_lock); 1215 retval = -ERESTARTNOINTR; 1216 goto bad_fork_cleanup_namespaces; 1217 } 1218 1219 if (clone_flags & CLONE_THREAD) { 1220 p->group_leader = current->group_leader; 1221 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); 1222 1223 if (!cputime_eq(current->signal->it_virt_expires, 1224 cputime_zero) || 1225 !cputime_eq(current->signal->it_prof_expires, 1226 cputime_zero) || 1227 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || 1228 !list_empty(¤t->signal->cpu_timers[0]) || 1229 !list_empty(¤t->signal->cpu_timers[1]) || 1230 !list_empty(¤t->signal->cpu_timers[2])) { 1231 /* 1232 * Have child wake up on its first tick to check 1233 * for process CPU timers. 1234 */ 1235 p->it_prof_expires = jiffies_to_cputime(1); 1236 } 1237 } 1238 1239 if (likely(p->pid)) { 1240 add_parent(p); 1241 if (unlikely(p->ptrace & PT_PTRACED)) 1242 __ptrace_link(p, current->parent); 1243 1244 if (thread_group_leader(p)) { 1245 p->signal->tty = current->signal->tty; 1246 p->signal->pgrp = process_group(current); 1247 p->signal->session = current->signal->session; 1248 attach_pid(p, PIDTYPE_PGID, process_group(p)); 1249 attach_pid(p, PIDTYPE_SID, p->signal->session); 1250 1251 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1252 __get_cpu_var(process_counts)++; 1253 } 1254 attach_pid(p, PIDTYPE_PID, p->pid); 1255 nr_threads++; 1256 } 1257 1258 total_forks++; 1259 spin_unlock(¤t->sighand->siglock); 1260 write_unlock_irq(&tasklist_lock); 1261 proc_fork_connector(p); 1262 return p; 1263 1264 bad_fork_cleanup_namespaces: 1265 exit_task_namespaces(p); 1266 bad_fork_cleanup_keys: 1267 exit_keys(p); 1268 bad_fork_cleanup_mm: 1269 if (p->mm) 1270 mmput(p->mm); 1271 bad_fork_cleanup_signal: 1272 cleanup_signal(p); 1273 bad_fork_cleanup_sighand: 1274 __cleanup_sighand(p->sighand); 1275 bad_fork_cleanup_fs: 1276 exit_fs(p); /* blocking */ 1277 bad_fork_cleanup_files: 1278 exit_files(p); /* blocking */ 1279 bad_fork_cleanup_semundo: 1280 exit_sem(p); 1281 bad_fork_cleanup_audit: 1282 audit_free(p); 1283 bad_fork_cleanup_security: 1284 security_task_free(p); 1285 bad_fork_cleanup_policy: 1286 #ifdef CONFIG_NUMA 1287 mpol_free(p->mempolicy); 1288 bad_fork_cleanup_cpuset: 1289 #endif 1290 cpuset_exit(p); 1291 bad_fork_cleanup_delays_binfmt: 1292 delayacct_tsk_free(p); 1293 if (p->binfmt) 1294 module_put(p->binfmt->module); 1295 bad_fork_cleanup_put_domain: 1296 module_put(task_thread_info(p)->exec_domain->module); 1297 bad_fork_cleanup_count: 1298 put_group_info(p->group_info); 1299 atomic_dec(&p->user->processes); 1300 free_uid(p->user); 1301 bad_fork_free: 1302 free_task(p); 1303 fork_out: 1304 return ERR_PTR(retval); 1305 } 1306 1307 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs) 1308 { 1309 memset(regs, 0, sizeof(struct pt_regs)); 1310 return regs; 1311 } 1312 1313 struct task_struct * __devinit fork_idle(int cpu) 1314 { 1315 struct task_struct *task; 1316 struct pt_regs regs; 1317 1318 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0); 1319 if (!task) 1320 return ERR_PTR(-ENOMEM); 1321 init_idle(task, cpu); 1322 1323 return task; 1324 } 1325 1326 static inline int fork_traceflag (unsigned clone_flags) 1327 { 1328 if (clone_flags & CLONE_UNTRACED) 1329 return 0; 1330 else if (clone_flags & CLONE_VFORK) { 1331 if (current->ptrace & PT_TRACE_VFORK) 1332 return PTRACE_EVENT_VFORK; 1333 } else if ((clone_flags & CSIGNAL) != SIGCHLD) { 1334 if (current->ptrace & PT_TRACE_CLONE) 1335 return PTRACE_EVENT_CLONE; 1336 } else if (current->ptrace & PT_TRACE_FORK) 1337 return PTRACE_EVENT_FORK; 1338 1339 return 0; 1340 } 1341 1342 /* 1343 * Ok, this is the main fork-routine. 1344 * 1345 * It copies the process, and if successful kick-starts 1346 * it and waits for it to finish using the VM if required. 1347 */ 1348 long do_fork(unsigned long clone_flags, 1349 unsigned long stack_start, 1350 struct pt_regs *regs, 1351 unsigned long stack_size, 1352 int __user *parent_tidptr, 1353 int __user *child_tidptr) 1354 { 1355 struct task_struct *p; 1356 int trace = 0; 1357 struct pid *pid = alloc_pid(); 1358 long nr; 1359 1360 if (!pid) 1361 return -EAGAIN; 1362 nr = pid->nr; 1363 if (unlikely(current->ptrace)) { 1364 trace = fork_traceflag (clone_flags); 1365 if (trace) 1366 clone_flags |= CLONE_PTRACE; 1367 } 1368 1369 p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, nr); 1370 /* 1371 * Do this prior waking up the new thread - the thread pointer 1372 * might get invalid after that point, if the thread exits quickly. 1373 */ 1374 if (!IS_ERR(p)) { 1375 struct completion vfork; 1376 1377 if (clone_flags & CLONE_VFORK) { 1378 p->vfork_done = &vfork; 1379 init_completion(&vfork); 1380 } 1381 1382 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { 1383 /* 1384 * We'll start up with an immediate SIGSTOP. 1385 */ 1386 sigaddset(&p->pending.signal, SIGSTOP); 1387 set_tsk_thread_flag(p, TIF_SIGPENDING); 1388 } 1389 1390 if (!(clone_flags & CLONE_STOPPED)) 1391 wake_up_new_task(p, clone_flags); 1392 else 1393 p->state = TASK_STOPPED; 1394 1395 if (unlikely (trace)) { 1396 current->ptrace_message = nr; 1397 ptrace_notify ((trace << 8) | SIGTRAP); 1398 } 1399 1400 if (clone_flags & CLONE_VFORK) { 1401 wait_for_completion(&vfork); 1402 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) { 1403 current->ptrace_message = nr; 1404 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); 1405 } 1406 } 1407 } else { 1408 free_pid(pid); 1409 nr = PTR_ERR(p); 1410 } 1411 return nr; 1412 } 1413 1414 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 1415 #define ARCH_MIN_MMSTRUCT_ALIGN 0 1416 #endif 1417 1418 static void sighand_ctor(void *data, kmem_cache_t *cachep, unsigned long flags) 1419 { 1420 struct sighand_struct *sighand = data; 1421 1422 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == 1423 SLAB_CTOR_CONSTRUCTOR) 1424 spin_lock_init(&sighand->siglock); 1425 } 1426 1427 void __init proc_caches_init(void) 1428 { 1429 sighand_cachep = kmem_cache_create("sighand_cache", 1430 sizeof(struct sighand_struct), 0, 1431 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, 1432 sighand_ctor, NULL); 1433 signal_cachep = kmem_cache_create("signal_cache", 1434 sizeof(struct signal_struct), 0, 1435 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 1436 files_cachep = kmem_cache_create("files_cache", 1437 sizeof(struct files_struct), 0, 1438 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 1439 fs_cachep = kmem_cache_create("fs_cache", 1440 sizeof(struct fs_struct), 0, 1441 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 1442 vm_area_cachep = kmem_cache_create("vm_area_struct", 1443 sizeof(struct vm_area_struct), 0, 1444 SLAB_PANIC, NULL, NULL); 1445 mm_cachep = kmem_cache_create("mm_struct", 1446 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 1447 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 1448 } 1449 1450 1451 /* 1452 * Check constraints on flags passed to the unshare system call and 1453 * force unsharing of additional process context as appropriate. 1454 */ 1455 static inline void check_unshare_flags(unsigned long *flags_ptr) 1456 { 1457 /* 1458 * If unsharing a thread from a thread group, must also 1459 * unshare vm. 1460 */ 1461 if (*flags_ptr & CLONE_THREAD) 1462 *flags_ptr |= CLONE_VM; 1463 1464 /* 1465 * If unsharing vm, must also unshare signal handlers. 1466 */ 1467 if (*flags_ptr & CLONE_VM) 1468 *flags_ptr |= CLONE_SIGHAND; 1469 1470 /* 1471 * If unsharing signal handlers and the task was created 1472 * using CLONE_THREAD, then must unshare the thread 1473 */ 1474 if ((*flags_ptr & CLONE_SIGHAND) && 1475 (atomic_read(¤t->signal->count) > 1)) 1476 *flags_ptr |= CLONE_THREAD; 1477 1478 /* 1479 * If unsharing namespace, must also unshare filesystem information. 1480 */ 1481 if (*flags_ptr & CLONE_NEWNS) 1482 *flags_ptr |= CLONE_FS; 1483 } 1484 1485 /* 1486 * Unsharing of tasks created with CLONE_THREAD is not supported yet 1487 */ 1488 static int unshare_thread(unsigned long unshare_flags) 1489 { 1490 if (unshare_flags & CLONE_THREAD) 1491 return -EINVAL; 1492 1493 return 0; 1494 } 1495 1496 /* 1497 * Unshare the filesystem structure if it is being shared 1498 */ 1499 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 1500 { 1501 struct fs_struct *fs = current->fs; 1502 1503 if ((unshare_flags & CLONE_FS) && 1504 (fs && atomic_read(&fs->count) > 1)) { 1505 *new_fsp = __copy_fs_struct(current->fs); 1506 if (!*new_fsp) 1507 return -ENOMEM; 1508 } 1509 1510 return 0; 1511 } 1512 1513 /* 1514 * Unshare the namespace structure if it is being shared 1515 */ 1516 static int unshare_namespace(unsigned long unshare_flags, struct namespace **new_nsp, struct fs_struct *new_fs) 1517 { 1518 struct namespace *ns = current->nsproxy->namespace; 1519 1520 if ((unshare_flags & CLONE_NEWNS) && ns) { 1521 if (!capable(CAP_SYS_ADMIN)) 1522 return -EPERM; 1523 1524 *new_nsp = dup_namespace(current, new_fs ? new_fs : current->fs); 1525 if (!*new_nsp) 1526 return -ENOMEM; 1527 } 1528 1529 return 0; 1530 } 1531 1532 /* 1533 * Unsharing of sighand for tasks created with CLONE_SIGHAND is not 1534 * supported yet 1535 */ 1536 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) 1537 { 1538 struct sighand_struct *sigh = current->sighand; 1539 1540 if ((unshare_flags & CLONE_SIGHAND) && 1541 (sigh && atomic_read(&sigh->count) > 1)) 1542 return -EINVAL; 1543 else 1544 return 0; 1545 } 1546 1547 /* 1548 * Unshare vm if it is being shared 1549 */ 1550 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) 1551 { 1552 struct mm_struct *mm = current->mm; 1553 1554 if ((unshare_flags & CLONE_VM) && 1555 (mm && atomic_read(&mm->mm_users) > 1)) { 1556 return -EINVAL; 1557 } 1558 1559 return 0; 1560 } 1561 1562 /* 1563 * Unshare file descriptor table if it is being shared 1564 */ 1565 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 1566 { 1567 struct files_struct *fd = current->files; 1568 int error = 0; 1569 1570 if ((unshare_flags & CLONE_FILES) && 1571 (fd && atomic_read(&fd->count) > 1)) { 1572 *new_fdp = dup_fd(fd, &error); 1573 if (!*new_fdp) 1574 return error; 1575 } 1576 1577 return 0; 1578 } 1579 1580 /* 1581 * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not 1582 * supported yet 1583 */ 1584 static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp) 1585 { 1586 if (unshare_flags & CLONE_SYSVSEM) 1587 return -EINVAL; 1588 1589 return 0; 1590 } 1591 1592 /* 1593 * unshare allows a process to 'unshare' part of the process 1594 * context which was originally shared using clone. copy_* 1595 * functions used by do_fork() cannot be used here directly 1596 * because they modify an inactive task_struct that is being 1597 * constructed. Here we are modifying the current, active, 1598 * task_struct. 1599 */ 1600 asmlinkage long sys_unshare(unsigned long unshare_flags) 1601 { 1602 int err = 0; 1603 struct fs_struct *fs, *new_fs = NULL; 1604 struct namespace *ns, *new_ns = NULL; 1605 struct sighand_struct *sigh, *new_sigh = NULL; 1606 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; 1607 struct files_struct *fd, *new_fd = NULL; 1608 struct sem_undo_list *new_ulist = NULL; 1609 struct nsproxy *new_nsproxy, *old_nsproxy; 1610 1611 check_unshare_flags(&unshare_flags); 1612 1613 /* Return -EINVAL for all unsupported flags */ 1614 err = -EINVAL; 1615 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 1616 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM)) 1617 goto bad_unshare_out; 1618 1619 if ((err = unshare_thread(unshare_flags))) 1620 goto bad_unshare_out; 1621 if ((err = unshare_fs(unshare_flags, &new_fs))) 1622 goto bad_unshare_cleanup_thread; 1623 if ((err = unshare_namespace(unshare_flags, &new_ns, new_fs))) 1624 goto bad_unshare_cleanup_fs; 1625 if ((err = unshare_sighand(unshare_flags, &new_sigh))) 1626 goto bad_unshare_cleanup_ns; 1627 if ((err = unshare_vm(unshare_flags, &new_mm))) 1628 goto bad_unshare_cleanup_sigh; 1629 if ((err = unshare_fd(unshare_flags, &new_fd))) 1630 goto bad_unshare_cleanup_vm; 1631 if ((err = unshare_semundo(unshare_flags, &new_ulist))) 1632 goto bad_unshare_cleanup_fd; 1633 1634 if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist) { 1635 1636 old_nsproxy = current->nsproxy; 1637 new_nsproxy = dup_namespaces(old_nsproxy); 1638 if (!new_nsproxy) { 1639 err = -ENOMEM; 1640 goto bad_unshare_cleanup_semundo; 1641 } 1642 1643 task_lock(current); 1644 current->nsproxy = new_nsproxy; 1645 1646 if (new_fs) { 1647 fs = current->fs; 1648 current->fs = new_fs; 1649 new_fs = fs; 1650 } 1651 1652 if (new_ns) { 1653 ns = current->nsproxy->namespace; 1654 current->nsproxy->namespace = new_ns; 1655 new_ns = ns; 1656 } 1657 1658 if (new_sigh) { 1659 sigh = current->sighand; 1660 rcu_assign_pointer(current->sighand, new_sigh); 1661 new_sigh = sigh; 1662 } 1663 1664 if (new_mm) { 1665 mm = current->mm; 1666 active_mm = current->active_mm; 1667 current->mm = new_mm; 1668 current->active_mm = new_mm; 1669 activate_mm(active_mm, new_mm); 1670 new_mm = mm; 1671 } 1672 1673 if (new_fd) { 1674 fd = current->files; 1675 current->files = new_fd; 1676 new_fd = fd; 1677 } 1678 1679 task_unlock(current); 1680 put_nsproxy(old_nsproxy); 1681 } 1682 1683 bad_unshare_cleanup_semundo: 1684 bad_unshare_cleanup_fd: 1685 if (new_fd) 1686 put_files_struct(new_fd); 1687 1688 bad_unshare_cleanup_vm: 1689 if (new_mm) 1690 mmput(new_mm); 1691 1692 bad_unshare_cleanup_sigh: 1693 if (new_sigh) 1694 if (atomic_dec_and_test(&new_sigh->count)) 1695 kmem_cache_free(sighand_cachep, new_sigh); 1696 1697 bad_unshare_cleanup_ns: 1698 if (new_ns) 1699 put_namespace(new_ns); 1700 1701 bad_unshare_cleanup_fs: 1702 if (new_fs) 1703 put_fs_struct(new_fs); 1704 1705 bad_unshare_cleanup_thread: 1706 bad_unshare_out: 1707 return err; 1708 } 1709