1 /* 2 * linux/fs/exec.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 /* 8 * #!-checking implemented by tytso. 9 */ 10 /* 11 * Demand-loading implemented 01.12.91 - no need to read anything but 12 * the header into memory. The inode of the executable is put into 13 * "current->executable", and page faults do the actual loading. Clean. 14 * 15 * Once more I can proudly say that linux stood up to being changed: it 16 * was less than 2 hours work to get demand-loading completely implemented. 17 * 18 * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead, 19 * current->executable is only used by the procfs. This allows a dispatch 20 * table to check for several different types of binary formats. We keep 21 * trying until we recognize the file or we run out of supported binary 22 * formats. 23 */ 24 25 #include <linux/config.h> 26 #include <linux/slab.h> 27 #include <linux/file.h> 28 #include <linux/mman.h> 29 #include <linux/a.out.h> 30 #include <linux/stat.h> 31 #include <linux/fcntl.h> 32 #include <linux/smp_lock.h> 33 #include <linux/init.h> 34 #include <linux/pagemap.h> 35 #include <linux/highmem.h> 36 #include <linux/spinlock.h> 37 #include <linux/key.h> 38 #include <linux/personality.h> 39 #include <linux/binfmts.h> 40 #include <linux/swap.h> 41 #include <linux/utsname.h> 42 #include <linux/module.h> 43 #include <linux/namei.h> 44 #include <linux/proc_fs.h> 45 #include <linux/ptrace.h> 46 #include <linux/mount.h> 47 #include <linux/security.h> 48 #include <linux/syscalls.h> 49 #include <linux/rmap.h> 50 #include <linux/acct.h> 51 #include <linux/cn_proc.h> 52 #include <linux/audit.h> 53 54 #include <asm/uaccess.h> 55 #include <asm/mmu_context.h> 56 57 #ifdef CONFIG_KMOD 58 #include <linux/kmod.h> 59 #endif 60 61 int core_uses_pid; 62 char core_pattern[65] = "core"; 63 int suid_dumpable = 0; 64 65 EXPORT_SYMBOL(suid_dumpable); 66 /* The maximal length of core_pattern is also specified in sysctl.c */ 67 68 static struct linux_binfmt *formats; 69 static DEFINE_RWLOCK(binfmt_lock); 70 71 int register_binfmt(struct linux_binfmt * fmt) 72 { 73 struct linux_binfmt ** tmp = &formats; 74 75 if (!fmt) 76 return -EINVAL; 77 if (fmt->next) 78 return -EBUSY; 79 write_lock(&binfmt_lock); 80 while (*tmp) { 81 if (fmt == *tmp) { 82 write_unlock(&binfmt_lock); 83 return -EBUSY; 84 } 85 tmp = &(*tmp)->next; 86 } 87 fmt->next = formats; 88 formats = fmt; 89 write_unlock(&binfmt_lock); 90 return 0; 91 } 92 93 EXPORT_SYMBOL(register_binfmt); 94 95 int unregister_binfmt(struct linux_binfmt * fmt) 96 { 97 struct linux_binfmt ** tmp = &formats; 98 99 write_lock(&binfmt_lock); 100 while (*tmp) { 101 if (fmt == *tmp) { 102 *tmp = fmt->next; 103 write_unlock(&binfmt_lock); 104 return 0; 105 } 106 tmp = &(*tmp)->next; 107 } 108 write_unlock(&binfmt_lock); 109 return -EINVAL; 110 } 111 112 EXPORT_SYMBOL(unregister_binfmt); 113 114 static inline void put_binfmt(struct linux_binfmt * fmt) 115 { 116 module_put(fmt->module); 117 } 118 119 /* 120 * Note that a shared library must be both readable and executable due to 121 * security reasons. 122 * 123 * Also note that we take the address to load from from the file itself. 124 */ 125 asmlinkage long sys_uselib(const char __user * library) 126 { 127 struct file * file; 128 struct nameidata nd; 129 int error; 130 131 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC); 132 if (error) 133 goto out; 134 135 error = -EINVAL; 136 if (!S_ISREG(nd.dentry->d_inode->i_mode)) 137 goto exit; 138 139 error = vfs_permission(&nd, MAY_READ | MAY_EXEC); 140 if (error) 141 goto exit; 142 143 file = nameidata_to_filp(&nd, O_RDONLY); 144 error = PTR_ERR(file); 145 if (IS_ERR(file)) 146 goto out; 147 148 error = -ENOEXEC; 149 if(file->f_op) { 150 struct linux_binfmt * fmt; 151 152 read_lock(&binfmt_lock); 153 for (fmt = formats ; fmt ; fmt = fmt->next) { 154 if (!fmt->load_shlib) 155 continue; 156 if (!try_module_get(fmt->module)) 157 continue; 158 read_unlock(&binfmt_lock); 159 error = fmt->load_shlib(file); 160 read_lock(&binfmt_lock); 161 put_binfmt(fmt); 162 if (error != -ENOEXEC) 163 break; 164 } 165 read_unlock(&binfmt_lock); 166 } 167 fput(file); 168 out: 169 return error; 170 exit: 171 release_open_intent(&nd); 172 path_release(&nd); 173 goto out; 174 } 175 176 /* 177 * count() counts the number of strings in array ARGV. 178 */ 179 static int count(char __user * __user * argv, int max) 180 { 181 int i = 0; 182 183 if (argv != NULL) { 184 for (;;) { 185 char __user * p; 186 187 if (get_user(p, argv)) 188 return -EFAULT; 189 if (!p) 190 break; 191 argv++; 192 if(++i > max) 193 return -E2BIG; 194 cond_resched(); 195 } 196 } 197 return i; 198 } 199 200 /* 201 * 'copy_strings()' copies argument/environment strings from user 202 * memory to free pages in kernel mem. These are in a format ready 203 * to be put directly into the top of new user memory. 204 */ 205 static int copy_strings(int argc, char __user * __user * argv, 206 struct linux_binprm *bprm) 207 { 208 struct page *kmapped_page = NULL; 209 char *kaddr = NULL; 210 int ret; 211 212 while (argc-- > 0) { 213 char __user *str; 214 int len; 215 unsigned long pos; 216 217 if (get_user(str, argv+argc) || 218 !(len = strnlen_user(str, bprm->p))) { 219 ret = -EFAULT; 220 goto out; 221 } 222 223 if (bprm->p < len) { 224 ret = -E2BIG; 225 goto out; 226 } 227 228 bprm->p -= len; 229 /* XXX: add architecture specific overflow check here. */ 230 pos = bprm->p; 231 232 while (len > 0) { 233 int i, new, err; 234 int offset, bytes_to_copy; 235 struct page *page; 236 237 offset = pos % PAGE_SIZE; 238 i = pos/PAGE_SIZE; 239 page = bprm->page[i]; 240 new = 0; 241 if (!page) { 242 page = alloc_page(GFP_HIGHUSER); 243 bprm->page[i] = page; 244 if (!page) { 245 ret = -ENOMEM; 246 goto out; 247 } 248 new = 1; 249 } 250 251 if (page != kmapped_page) { 252 if (kmapped_page) 253 kunmap(kmapped_page); 254 kmapped_page = page; 255 kaddr = kmap(kmapped_page); 256 } 257 if (new && offset) 258 memset(kaddr, 0, offset); 259 bytes_to_copy = PAGE_SIZE - offset; 260 if (bytes_to_copy > len) { 261 bytes_to_copy = len; 262 if (new) 263 memset(kaddr+offset+len, 0, 264 PAGE_SIZE-offset-len); 265 } 266 err = copy_from_user(kaddr+offset, str, bytes_to_copy); 267 if (err) { 268 ret = -EFAULT; 269 goto out; 270 } 271 272 pos += bytes_to_copy; 273 str += bytes_to_copy; 274 len -= bytes_to_copy; 275 } 276 } 277 ret = 0; 278 out: 279 if (kmapped_page) 280 kunmap(kmapped_page); 281 return ret; 282 } 283 284 /* 285 * Like copy_strings, but get argv and its values from kernel memory. 286 */ 287 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm) 288 { 289 int r; 290 mm_segment_t oldfs = get_fs(); 291 set_fs(KERNEL_DS); 292 r = copy_strings(argc, (char __user * __user *)argv, bprm); 293 set_fs(oldfs); 294 return r; 295 } 296 297 EXPORT_SYMBOL(copy_strings_kernel); 298 299 #ifdef CONFIG_MMU 300 /* 301 * This routine is used to map in a page into an address space: needed by 302 * execve() for the initial stack and environment pages. 303 * 304 * vma->vm_mm->mmap_sem is held for writing. 305 */ 306 void install_arg_page(struct vm_area_struct *vma, 307 struct page *page, unsigned long address) 308 { 309 struct mm_struct *mm = vma->vm_mm; 310 pte_t * pte; 311 spinlock_t *ptl; 312 313 if (unlikely(anon_vma_prepare(vma))) 314 goto out; 315 316 flush_dcache_page(page); 317 pte = get_locked_pte(mm, address, &ptl); 318 if (!pte) 319 goto out; 320 if (!pte_none(*pte)) { 321 pte_unmap_unlock(pte, ptl); 322 goto out; 323 } 324 inc_mm_counter(mm, anon_rss); 325 lru_cache_add_active(page); 326 set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte( 327 page, vma->vm_page_prot)))); 328 page_add_new_anon_rmap(page, vma, address); 329 pte_unmap_unlock(pte, ptl); 330 331 /* no need for flush_tlb */ 332 return; 333 out: 334 __free_page(page); 335 force_sig(SIGKILL, current); 336 } 337 338 #define EXTRA_STACK_VM_PAGES 20 /* random */ 339 340 int setup_arg_pages(struct linux_binprm *bprm, 341 unsigned long stack_top, 342 int executable_stack) 343 { 344 unsigned long stack_base; 345 struct vm_area_struct *mpnt; 346 struct mm_struct *mm = current->mm; 347 int i, ret; 348 long arg_size; 349 350 #ifdef CONFIG_STACK_GROWSUP 351 /* Move the argument and environment strings to the bottom of the 352 * stack space. 353 */ 354 int offset, j; 355 char *to, *from; 356 357 /* Start by shifting all the pages down */ 358 i = 0; 359 for (j = 0; j < MAX_ARG_PAGES; j++) { 360 struct page *page = bprm->page[j]; 361 if (!page) 362 continue; 363 bprm->page[i++] = page; 364 } 365 366 /* Now move them within their pages */ 367 offset = bprm->p % PAGE_SIZE; 368 to = kmap(bprm->page[0]); 369 for (j = 1; j < i; j++) { 370 memmove(to, to + offset, PAGE_SIZE - offset); 371 from = kmap(bprm->page[j]); 372 memcpy(to + PAGE_SIZE - offset, from, offset); 373 kunmap(bprm->page[j - 1]); 374 to = from; 375 } 376 memmove(to, to + offset, PAGE_SIZE - offset); 377 kunmap(bprm->page[j - 1]); 378 379 /* Limit stack size to 1GB */ 380 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max; 381 if (stack_base > (1 << 30)) 382 stack_base = 1 << 30; 383 stack_base = PAGE_ALIGN(stack_top - stack_base); 384 385 /* Adjust bprm->p to point to the end of the strings. */ 386 bprm->p = stack_base + PAGE_SIZE * i - offset; 387 388 mm->arg_start = stack_base; 389 arg_size = i << PAGE_SHIFT; 390 391 /* zero pages that were copied above */ 392 while (i < MAX_ARG_PAGES) 393 bprm->page[i++] = NULL; 394 #else 395 stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE); 396 stack_base = PAGE_ALIGN(stack_base); 397 bprm->p += stack_base; 398 mm->arg_start = bprm->p; 399 arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start); 400 #endif 401 402 arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE; 403 404 if (bprm->loader) 405 bprm->loader += stack_base; 406 bprm->exec += stack_base; 407 408 mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 409 if (!mpnt) 410 return -ENOMEM; 411 412 memset(mpnt, 0, sizeof(*mpnt)); 413 414 down_write(&mm->mmap_sem); 415 { 416 mpnt->vm_mm = mm; 417 #ifdef CONFIG_STACK_GROWSUP 418 mpnt->vm_start = stack_base; 419 mpnt->vm_end = stack_base + arg_size; 420 #else 421 mpnt->vm_end = stack_top; 422 mpnt->vm_start = mpnt->vm_end - arg_size; 423 #endif 424 /* Adjust stack execute permissions; explicitly enable 425 * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X 426 * and leave alone (arch default) otherwise. */ 427 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 428 mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC; 429 else if (executable_stack == EXSTACK_DISABLE_X) 430 mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC; 431 else 432 mpnt->vm_flags = VM_STACK_FLAGS; 433 mpnt->vm_flags |= mm->def_flags; 434 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7]; 435 if ((ret = insert_vm_struct(mm, mpnt))) { 436 up_write(&mm->mmap_sem); 437 kmem_cache_free(vm_area_cachep, mpnt); 438 return ret; 439 } 440 mm->stack_vm = mm->total_vm = vma_pages(mpnt); 441 } 442 443 for (i = 0 ; i < MAX_ARG_PAGES ; i++) { 444 struct page *page = bprm->page[i]; 445 if (page) { 446 bprm->page[i] = NULL; 447 install_arg_page(mpnt, page, stack_base); 448 } 449 stack_base += PAGE_SIZE; 450 } 451 up_write(&mm->mmap_sem); 452 453 return 0; 454 } 455 456 EXPORT_SYMBOL(setup_arg_pages); 457 458 #define free_arg_pages(bprm) do { } while (0) 459 460 #else 461 462 static inline void free_arg_pages(struct linux_binprm *bprm) 463 { 464 int i; 465 466 for (i = 0; i < MAX_ARG_PAGES; i++) { 467 if (bprm->page[i]) 468 __free_page(bprm->page[i]); 469 bprm->page[i] = NULL; 470 } 471 } 472 473 #endif /* CONFIG_MMU */ 474 475 struct file *open_exec(const char *name) 476 { 477 struct nameidata nd; 478 int err; 479 struct file *file; 480 481 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC); 482 file = ERR_PTR(err); 483 484 if (!err) { 485 struct inode *inode = nd.dentry->d_inode; 486 file = ERR_PTR(-EACCES); 487 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) && 488 S_ISREG(inode->i_mode)) { 489 int err = vfs_permission(&nd, MAY_EXEC); 490 if (!err && !(inode->i_mode & 0111)) 491 err = -EACCES; 492 file = ERR_PTR(err); 493 if (!err) { 494 file = nameidata_to_filp(&nd, O_RDONLY); 495 if (!IS_ERR(file)) { 496 err = deny_write_access(file); 497 if (err) { 498 fput(file); 499 file = ERR_PTR(err); 500 } 501 } 502 out: 503 return file; 504 } 505 } 506 release_open_intent(&nd); 507 path_release(&nd); 508 } 509 goto out; 510 } 511 512 EXPORT_SYMBOL(open_exec); 513 514 int kernel_read(struct file *file, unsigned long offset, 515 char *addr, unsigned long count) 516 { 517 mm_segment_t old_fs; 518 loff_t pos = offset; 519 int result; 520 521 old_fs = get_fs(); 522 set_fs(get_ds()); 523 /* The cast to a user pointer is valid due to the set_fs() */ 524 result = vfs_read(file, (void __user *)addr, count, &pos); 525 set_fs(old_fs); 526 return result; 527 } 528 529 EXPORT_SYMBOL(kernel_read); 530 531 static int exec_mmap(struct mm_struct *mm) 532 { 533 struct task_struct *tsk; 534 struct mm_struct * old_mm, *active_mm; 535 536 /* Notify parent that we're no longer interested in the old VM */ 537 tsk = current; 538 old_mm = current->mm; 539 mm_release(tsk, old_mm); 540 541 if (old_mm) { 542 /* 543 * Make sure that if there is a core dump in progress 544 * for the old mm, we get out and die instead of going 545 * through with the exec. We must hold mmap_sem around 546 * checking core_waiters and changing tsk->mm. The 547 * core-inducing thread will increment core_waiters for 548 * each thread whose ->mm == old_mm. 549 */ 550 down_read(&old_mm->mmap_sem); 551 if (unlikely(old_mm->core_waiters)) { 552 up_read(&old_mm->mmap_sem); 553 return -EINTR; 554 } 555 } 556 task_lock(tsk); 557 active_mm = tsk->active_mm; 558 tsk->mm = mm; 559 tsk->active_mm = mm; 560 activate_mm(active_mm, mm); 561 task_unlock(tsk); 562 arch_pick_mmap_layout(mm); 563 if (old_mm) { 564 up_read(&old_mm->mmap_sem); 565 BUG_ON(active_mm != old_mm); 566 mmput(old_mm); 567 return 0; 568 } 569 mmdrop(active_mm); 570 return 0; 571 } 572 573 /* 574 * This function makes sure the current process has its own signal table, 575 * so that flush_signal_handlers can later reset the handlers without 576 * disturbing other processes. (Other processes might share the signal 577 * table via the CLONE_SIGHAND option to clone().) 578 */ 579 static int de_thread(struct task_struct *tsk) 580 { 581 struct signal_struct *sig = tsk->signal; 582 struct sighand_struct *newsighand, *oldsighand = tsk->sighand; 583 spinlock_t *lock = &oldsighand->siglock; 584 struct task_struct *leader = NULL; 585 int count; 586 587 /* 588 * If we don't share sighandlers, then we aren't sharing anything 589 * and we can just re-use it all. 590 */ 591 if (atomic_read(&oldsighand->count) <= 1) { 592 BUG_ON(atomic_read(&sig->count) != 1); 593 exit_itimers(sig); 594 return 0; 595 } 596 597 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 598 if (!newsighand) 599 return -ENOMEM; 600 601 if (thread_group_empty(current)) 602 goto no_thread_group; 603 604 /* 605 * Kill all other threads in the thread group. 606 * We must hold tasklist_lock to call zap_other_threads. 607 */ 608 read_lock(&tasklist_lock); 609 spin_lock_irq(lock); 610 if (sig->flags & SIGNAL_GROUP_EXIT) { 611 /* 612 * Another group action in progress, just 613 * return so that the signal is processed. 614 */ 615 spin_unlock_irq(lock); 616 read_unlock(&tasklist_lock); 617 kmem_cache_free(sighand_cachep, newsighand); 618 return -EAGAIN; 619 } 620 621 /* 622 * child_reaper ignores SIGKILL, change it now. 623 * Reparenting needs write_lock on tasklist_lock, 624 * so it is safe to do it under read_lock. 625 */ 626 if (unlikely(current->group_leader == child_reaper)) 627 child_reaper = current; 628 629 zap_other_threads(current); 630 read_unlock(&tasklist_lock); 631 632 /* 633 * Account for the thread group leader hanging around: 634 */ 635 count = 1; 636 if (!thread_group_leader(current)) { 637 count = 2; 638 /* 639 * The SIGALRM timer survives the exec, but needs to point 640 * at us as the new group leader now. We have a race with 641 * a timer firing now getting the old leader, so we need to 642 * synchronize with any firing (by calling del_timer_sync) 643 * before we can safely let the old group leader die. 644 */ 645 sig->tsk = current; 646 spin_unlock_irq(lock); 647 if (hrtimer_cancel(&sig->real_timer)) 648 hrtimer_restart(&sig->real_timer); 649 spin_lock_irq(lock); 650 } 651 while (atomic_read(&sig->count) > count) { 652 sig->group_exit_task = current; 653 sig->notify_count = count; 654 __set_current_state(TASK_UNINTERRUPTIBLE); 655 spin_unlock_irq(lock); 656 schedule(); 657 spin_lock_irq(lock); 658 } 659 sig->group_exit_task = NULL; 660 sig->notify_count = 0; 661 spin_unlock_irq(lock); 662 663 /* 664 * At this point all other threads have exited, all we have to 665 * do is to wait for the thread group leader to become inactive, 666 * and to assume its PID: 667 */ 668 if (!thread_group_leader(current)) { 669 /* 670 * Wait for the thread group leader to be a zombie. 671 * It should already be zombie at this point, most 672 * of the time. 673 */ 674 leader = current->group_leader; 675 while (leader->exit_state != EXIT_ZOMBIE) 676 yield(); 677 678 /* 679 * The only record we have of the real-time age of a 680 * process, regardless of execs it's done, is start_time. 681 * All the past CPU time is accumulated in signal_struct 682 * from sister threads now dead. But in this non-leader 683 * exec, nothing survives from the original leader thread, 684 * whose birth marks the true age of this process now. 685 * When we take on its identity by switching to its PID, we 686 * also take its birthdate (always earlier than our own). 687 */ 688 current->start_time = leader->start_time; 689 690 write_lock_irq(&tasklist_lock); 691 692 BUG_ON(leader->tgid != current->tgid); 693 BUG_ON(current->pid == current->tgid); 694 /* 695 * An exec() starts a new thread group with the 696 * TGID of the previous thread group. Rehash the 697 * two threads with a switched PID, and release 698 * the former thread group leader: 699 */ 700 701 /* Become a process group leader with the old leader's pid. 702 * Note: The old leader also uses thispid until release_task 703 * is called. Odd but simple and correct. 704 */ 705 detach_pid(current, PIDTYPE_PID); 706 current->pid = leader->pid; 707 attach_pid(current, PIDTYPE_PID, current->pid); 708 attach_pid(current, PIDTYPE_PGID, current->signal->pgrp); 709 attach_pid(current, PIDTYPE_SID, current->signal->session); 710 list_replace_rcu(&leader->tasks, ¤t->tasks); 711 712 current->group_leader = current; 713 leader->group_leader = current; 714 715 /* Reduce leader to a thread */ 716 detach_pid(leader, PIDTYPE_PGID); 717 detach_pid(leader, PIDTYPE_SID); 718 719 current->exit_signal = SIGCHLD; 720 721 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 722 leader->exit_state = EXIT_DEAD; 723 724 write_unlock_irq(&tasklist_lock); 725 } 726 727 /* 728 * There may be one thread left which is just exiting, 729 * but it's safe to stop telling the group to kill themselves. 730 */ 731 sig->flags = 0; 732 733 no_thread_group: 734 exit_itimers(sig); 735 if (leader) 736 release_task(leader); 737 738 BUG_ON(atomic_read(&sig->count) != 1); 739 740 if (atomic_read(&oldsighand->count) == 1) { 741 /* 742 * Now that we nuked the rest of the thread group, 743 * it turns out we are not sharing sighand any more either. 744 * So we can just keep it. 745 */ 746 kmem_cache_free(sighand_cachep, newsighand); 747 } else { 748 /* 749 * Move our state over to newsighand and switch it in. 750 */ 751 atomic_set(&newsighand->count, 1); 752 memcpy(newsighand->action, oldsighand->action, 753 sizeof(newsighand->action)); 754 755 write_lock_irq(&tasklist_lock); 756 spin_lock(&oldsighand->siglock); 757 spin_lock(&newsighand->siglock); 758 759 rcu_assign_pointer(current->sighand, newsighand); 760 recalc_sigpending(); 761 762 spin_unlock(&newsighand->siglock); 763 spin_unlock(&oldsighand->siglock); 764 write_unlock_irq(&tasklist_lock); 765 766 if (atomic_dec_and_test(&oldsighand->count)) 767 kmem_cache_free(sighand_cachep, oldsighand); 768 } 769 770 BUG_ON(!thread_group_leader(current)); 771 return 0; 772 } 773 774 /* 775 * These functions flushes out all traces of the currently running executable 776 * so that a new one can be started 777 */ 778 779 static void flush_old_files(struct files_struct * files) 780 { 781 long j = -1; 782 struct fdtable *fdt; 783 784 spin_lock(&files->file_lock); 785 for (;;) { 786 unsigned long set, i; 787 788 j++; 789 i = j * __NFDBITS; 790 fdt = files_fdtable(files); 791 if (i >= fdt->max_fds || i >= fdt->max_fdset) 792 break; 793 set = fdt->close_on_exec->fds_bits[j]; 794 if (!set) 795 continue; 796 fdt->close_on_exec->fds_bits[j] = 0; 797 spin_unlock(&files->file_lock); 798 for ( ; set ; i++,set >>= 1) { 799 if (set & 1) { 800 sys_close(i); 801 } 802 } 803 spin_lock(&files->file_lock); 804 805 } 806 spin_unlock(&files->file_lock); 807 } 808 809 void get_task_comm(char *buf, struct task_struct *tsk) 810 { 811 /* buf must be at least sizeof(tsk->comm) in size */ 812 task_lock(tsk); 813 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 814 task_unlock(tsk); 815 } 816 817 void set_task_comm(struct task_struct *tsk, char *buf) 818 { 819 task_lock(tsk); 820 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 821 task_unlock(tsk); 822 } 823 824 int flush_old_exec(struct linux_binprm * bprm) 825 { 826 char * name; 827 int i, ch, retval; 828 struct files_struct *files; 829 char tcomm[sizeof(current->comm)]; 830 831 /* 832 * Make sure we have a private signal table and that 833 * we are unassociated from the previous thread group. 834 */ 835 retval = de_thread(current); 836 if (retval) 837 goto out; 838 839 /* 840 * Make sure we have private file handles. Ask the 841 * fork helper to do the work for us and the exit 842 * helper to do the cleanup of the old one. 843 */ 844 files = current->files; /* refcounted so safe to hold */ 845 retval = unshare_files(); 846 if (retval) 847 goto out; 848 /* 849 * Release all of the old mmap stuff 850 */ 851 retval = exec_mmap(bprm->mm); 852 if (retval) 853 goto mmap_failed; 854 855 bprm->mm = NULL; /* We're using it now */ 856 857 /* This is the point of no return */ 858 put_files_struct(files); 859 860 current->sas_ss_sp = current->sas_ss_size = 0; 861 862 if (current->euid == current->uid && current->egid == current->gid) 863 current->mm->dumpable = 1; 864 else 865 current->mm->dumpable = suid_dumpable; 866 867 name = bprm->filename; 868 869 /* Copies the binary name from after last slash */ 870 for (i=0; (ch = *(name++)) != '\0';) { 871 if (ch == '/') 872 i = 0; /* overwrite what we wrote */ 873 else 874 if (i < (sizeof(tcomm) - 1)) 875 tcomm[i++] = ch; 876 } 877 tcomm[i] = '\0'; 878 set_task_comm(current, tcomm); 879 880 current->flags &= ~PF_RANDOMIZE; 881 flush_thread(); 882 883 /* Set the new mm task size. We have to do that late because it may 884 * depend on TIF_32BIT which is only updated in flush_thread() on 885 * some architectures like powerpc 886 */ 887 current->mm->task_size = TASK_SIZE; 888 889 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 890 file_permission(bprm->file, MAY_READ) || 891 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { 892 suid_keys(current); 893 current->mm->dumpable = suid_dumpable; 894 } 895 896 /* An exec changes our domain. We are no longer part of the thread 897 group */ 898 899 current->self_exec_id++; 900 901 flush_signal_handlers(current, 0); 902 flush_old_files(current->files); 903 904 return 0; 905 906 mmap_failed: 907 put_files_struct(current->files); 908 current->files = files; 909 out: 910 return retval; 911 } 912 913 EXPORT_SYMBOL(flush_old_exec); 914 915 /* 916 * Fill the binprm structure from the inode. 917 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 918 */ 919 int prepare_binprm(struct linux_binprm *bprm) 920 { 921 int mode; 922 struct inode * inode = bprm->file->f_dentry->d_inode; 923 int retval; 924 925 mode = inode->i_mode; 926 /* 927 * Check execute perms again - if the caller has CAP_DAC_OVERRIDE, 928 * generic_permission lets a non-executable through 929 */ 930 if (!(mode & 0111)) /* with at least _one_ execute bit set */ 931 return -EACCES; 932 if (bprm->file->f_op == NULL) 933 return -EACCES; 934 935 bprm->e_uid = current->euid; 936 bprm->e_gid = current->egid; 937 938 if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) { 939 /* Set-uid? */ 940 if (mode & S_ISUID) { 941 current->personality &= ~PER_CLEAR_ON_SETID; 942 bprm->e_uid = inode->i_uid; 943 } 944 945 /* Set-gid? */ 946 /* 947 * If setgid is set but no group execute bit then this 948 * is a candidate for mandatory locking, not a setgid 949 * executable. 950 */ 951 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 952 current->personality &= ~PER_CLEAR_ON_SETID; 953 bprm->e_gid = inode->i_gid; 954 } 955 } 956 957 /* fill in binprm security blob */ 958 retval = security_bprm_set(bprm); 959 if (retval) 960 return retval; 961 962 memset(bprm->buf,0,BINPRM_BUF_SIZE); 963 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE); 964 } 965 966 EXPORT_SYMBOL(prepare_binprm); 967 968 static int unsafe_exec(struct task_struct *p) 969 { 970 int unsafe = 0; 971 if (p->ptrace & PT_PTRACED) { 972 if (p->ptrace & PT_PTRACE_CAP) 973 unsafe |= LSM_UNSAFE_PTRACE_CAP; 974 else 975 unsafe |= LSM_UNSAFE_PTRACE; 976 } 977 if (atomic_read(&p->fs->count) > 1 || 978 atomic_read(&p->files->count) > 1 || 979 atomic_read(&p->sighand->count) > 1) 980 unsafe |= LSM_UNSAFE_SHARE; 981 982 return unsafe; 983 } 984 985 void compute_creds(struct linux_binprm *bprm) 986 { 987 int unsafe; 988 989 if (bprm->e_uid != current->uid) 990 suid_keys(current); 991 exec_keys(current); 992 993 task_lock(current); 994 unsafe = unsafe_exec(current); 995 security_bprm_apply_creds(bprm, unsafe); 996 task_unlock(current); 997 security_bprm_post_apply_creds(bprm); 998 } 999 1000 EXPORT_SYMBOL(compute_creds); 1001 1002 void remove_arg_zero(struct linux_binprm *bprm) 1003 { 1004 if (bprm->argc) { 1005 unsigned long offset; 1006 char * kaddr; 1007 struct page *page; 1008 1009 offset = bprm->p % PAGE_SIZE; 1010 goto inside; 1011 1012 while (bprm->p++, *(kaddr+offset++)) { 1013 if (offset != PAGE_SIZE) 1014 continue; 1015 offset = 0; 1016 kunmap_atomic(kaddr, KM_USER0); 1017 inside: 1018 page = bprm->page[bprm->p/PAGE_SIZE]; 1019 kaddr = kmap_atomic(page, KM_USER0); 1020 } 1021 kunmap_atomic(kaddr, KM_USER0); 1022 bprm->argc--; 1023 } 1024 } 1025 1026 EXPORT_SYMBOL(remove_arg_zero); 1027 1028 /* 1029 * cycle the list of binary formats handler, until one recognizes the image 1030 */ 1031 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) 1032 { 1033 int try,retval; 1034 struct linux_binfmt *fmt; 1035 #ifdef __alpha__ 1036 /* handle /sbin/loader.. */ 1037 { 1038 struct exec * eh = (struct exec *) bprm->buf; 1039 1040 if (!bprm->loader && eh->fh.f_magic == 0x183 && 1041 (eh->fh.f_flags & 0x3000) == 0x3000) 1042 { 1043 struct file * file; 1044 unsigned long loader; 1045 1046 allow_write_access(bprm->file); 1047 fput(bprm->file); 1048 bprm->file = NULL; 1049 1050 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *); 1051 1052 file = open_exec("/sbin/loader"); 1053 retval = PTR_ERR(file); 1054 if (IS_ERR(file)) 1055 return retval; 1056 1057 /* Remember if the application is TASO. */ 1058 bprm->sh_bang = eh->ah.entry < 0x100000000UL; 1059 1060 bprm->file = file; 1061 bprm->loader = loader; 1062 retval = prepare_binprm(bprm); 1063 if (retval<0) 1064 return retval; 1065 /* should call search_binary_handler recursively here, 1066 but it does not matter */ 1067 } 1068 } 1069 #endif 1070 retval = security_bprm_check(bprm); 1071 if (retval) 1072 return retval; 1073 1074 /* kernel module loader fixup */ 1075 /* so we don't try to load run modprobe in kernel space. */ 1076 set_fs(USER_DS); 1077 1078 retval = audit_bprm(bprm); 1079 if (retval) 1080 return retval; 1081 1082 retval = -ENOENT; 1083 for (try=0; try<2; try++) { 1084 read_lock(&binfmt_lock); 1085 for (fmt = formats ; fmt ; fmt = fmt->next) { 1086 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; 1087 if (!fn) 1088 continue; 1089 if (!try_module_get(fmt->module)) 1090 continue; 1091 read_unlock(&binfmt_lock); 1092 retval = fn(bprm, regs); 1093 if (retval >= 0) { 1094 put_binfmt(fmt); 1095 allow_write_access(bprm->file); 1096 if (bprm->file) 1097 fput(bprm->file); 1098 bprm->file = NULL; 1099 current->did_exec = 1; 1100 proc_exec_connector(current); 1101 return retval; 1102 } 1103 read_lock(&binfmt_lock); 1104 put_binfmt(fmt); 1105 if (retval != -ENOEXEC || bprm->mm == NULL) 1106 break; 1107 if (!bprm->file) { 1108 read_unlock(&binfmt_lock); 1109 return retval; 1110 } 1111 } 1112 read_unlock(&binfmt_lock); 1113 if (retval != -ENOEXEC || bprm->mm == NULL) { 1114 break; 1115 #ifdef CONFIG_KMOD 1116 }else{ 1117 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1118 if (printable(bprm->buf[0]) && 1119 printable(bprm->buf[1]) && 1120 printable(bprm->buf[2]) && 1121 printable(bprm->buf[3])) 1122 break; /* -ENOEXEC */ 1123 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1124 #endif 1125 } 1126 } 1127 return retval; 1128 } 1129 1130 EXPORT_SYMBOL(search_binary_handler); 1131 1132 /* 1133 * sys_execve() executes a new program. 1134 */ 1135 int do_execve(char * filename, 1136 char __user *__user *argv, 1137 char __user *__user *envp, 1138 struct pt_regs * regs) 1139 { 1140 struct linux_binprm *bprm; 1141 struct file *file; 1142 int retval; 1143 int i; 1144 1145 retval = -ENOMEM; 1146 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1147 if (!bprm) 1148 goto out_ret; 1149 1150 file = open_exec(filename); 1151 retval = PTR_ERR(file); 1152 if (IS_ERR(file)) 1153 goto out_kfree; 1154 1155 sched_exec(); 1156 1157 bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *); 1158 1159 bprm->file = file; 1160 bprm->filename = filename; 1161 bprm->interp = filename; 1162 bprm->mm = mm_alloc(); 1163 retval = -ENOMEM; 1164 if (!bprm->mm) 1165 goto out_file; 1166 1167 retval = init_new_context(current, bprm->mm); 1168 if (retval < 0) 1169 goto out_mm; 1170 1171 bprm->argc = count(argv, bprm->p / sizeof(void *)); 1172 if ((retval = bprm->argc) < 0) 1173 goto out_mm; 1174 1175 bprm->envc = count(envp, bprm->p / sizeof(void *)); 1176 if ((retval = bprm->envc) < 0) 1177 goto out_mm; 1178 1179 retval = security_bprm_alloc(bprm); 1180 if (retval) 1181 goto out; 1182 1183 retval = prepare_binprm(bprm); 1184 if (retval < 0) 1185 goto out; 1186 1187 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1188 if (retval < 0) 1189 goto out; 1190 1191 bprm->exec = bprm->p; 1192 retval = copy_strings(bprm->envc, envp, bprm); 1193 if (retval < 0) 1194 goto out; 1195 1196 retval = copy_strings(bprm->argc, argv, bprm); 1197 if (retval < 0) 1198 goto out; 1199 1200 retval = search_binary_handler(bprm,regs); 1201 if (retval >= 0) { 1202 free_arg_pages(bprm); 1203 1204 /* execve success */ 1205 security_bprm_free(bprm); 1206 acct_update_integrals(current); 1207 kfree(bprm); 1208 return retval; 1209 } 1210 1211 out: 1212 /* Something went wrong, return the inode and free the argument pages*/ 1213 for (i = 0 ; i < MAX_ARG_PAGES ; i++) { 1214 struct page * page = bprm->page[i]; 1215 if (page) 1216 __free_page(page); 1217 } 1218 1219 if (bprm->security) 1220 security_bprm_free(bprm); 1221 1222 out_mm: 1223 if (bprm->mm) 1224 mmdrop(bprm->mm); 1225 1226 out_file: 1227 if (bprm->file) { 1228 allow_write_access(bprm->file); 1229 fput(bprm->file); 1230 } 1231 1232 out_kfree: 1233 kfree(bprm); 1234 1235 out_ret: 1236 return retval; 1237 } 1238 1239 int set_binfmt(struct linux_binfmt *new) 1240 { 1241 struct linux_binfmt *old = current->binfmt; 1242 1243 if (new) { 1244 if (!try_module_get(new->module)) 1245 return -1; 1246 } 1247 current->binfmt = new; 1248 if (old) 1249 module_put(old->module); 1250 return 0; 1251 } 1252 1253 EXPORT_SYMBOL(set_binfmt); 1254 1255 #define CORENAME_MAX_SIZE 64 1256 1257 /* format_corename will inspect the pattern parameter, and output a 1258 * name into corename, which must have space for at least 1259 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 1260 */ 1261 static void format_corename(char *corename, const char *pattern, long signr) 1262 { 1263 const char *pat_ptr = pattern; 1264 char *out_ptr = corename; 1265 char *const out_end = corename + CORENAME_MAX_SIZE; 1266 int rc; 1267 int pid_in_pattern = 0; 1268 1269 /* Repeat as long as we have more pattern to process and more output 1270 space */ 1271 while (*pat_ptr) { 1272 if (*pat_ptr != '%') { 1273 if (out_ptr == out_end) 1274 goto out; 1275 *out_ptr++ = *pat_ptr++; 1276 } else { 1277 switch (*++pat_ptr) { 1278 case 0: 1279 goto out; 1280 /* Double percent, output one percent */ 1281 case '%': 1282 if (out_ptr == out_end) 1283 goto out; 1284 *out_ptr++ = '%'; 1285 break; 1286 /* pid */ 1287 case 'p': 1288 pid_in_pattern = 1; 1289 rc = snprintf(out_ptr, out_end - out_ptr, 1290 "%d", current->tgid); 1291 if (rc > out_end - out_ptr) 1292 goto out; 1293 out_ptr += rc; 1294 break; 1295 /* uid */ 1296 case 'u': 1297 rc = snprintf(out_ptr, out_end - out_ptr, 1298 "%d", current->uid); 1299 if (rc > out_end - out_ptr) 1300 goto out; 1301 out_ptr += rc; 1302 break; 1303 /* gid */ 1304 case 'g': 1305 rc = snprintf(out_ptr, out_end - out_ptr, 1306 "%d", current->gid); 1307 if (rc > out_end - out_ptr) 1308 goto out; 1309 out_ptr += rc; 1310 break; 1311 /* signal that caused the coredump */ 1312 case 's': 1313 rc = snprintf(out_ptr, out_end - out_ptr, 1314 "%ld", signr); 1315 if (rc > out_end - out_ptr) 1316 goto out; 1317 out_ptr += rc; 1318 break; 1319 /* UNIX time of coredump */ 1320 case 't': { 1321 struct timeval tv; 1322 do_gettimeofday(&tv); 1323 rc = snprintf(out_ptr, out_end - out_ptr, 1324 "%lu", tv.tv_sec); 1325 if (rc > out_end - out_ptr) 1326 goto out; 1327 out_ptr += rc; 1328 break; 1329 } 1330 /* hostname */ 1331 case 'h': 1332 down_read(&uts_sem); 1333 rc = snprintf(out_ptr, out_end - out_ptr, 1334 "%s", system_utsname.nodename); 1335 up_read(&uts_sem); 1336 if (rc > out_end - out_ptr) 1337 goto out; 1338 out_ptr += rc; 1339 break; 1340 /* executable */ 1341 case 'e': 1342 rc = snprintf(out_ptr, out_end - out_ptr, 1343 "%s", current->comm); 1344 if (rc > out_end - out_ptr) 1345 goto out; 1346 out_ptr += rc; 1347 break; 1348 default: 1349 break; 1350 } 1351 ++pat_ptr; 1352 } 1353 } 1354 /* Backward compatibility with core_uses_pid: 1355 * 1356 * If core_pattern does not include a %p (as is the default) 1357 * and core_uses_pid is set, then .%pid will be appended to 1358 * the filename */ 1359 if (!pid_in_pattern 1360 && (core_uses_pid || atomic_read(¤t->mm->mm_users) != 1)) { 1361 rc = snprintf(out_ptr, out_end - out_ptr, 1362 ".%d", current->tgid); 1363 if (rc > out_end - out_ptr) 1364 goto out; 1365 out_ptr += rc; 1366 } 1367 out: 1368 *out_ptr = 0; 1369 } 1370 1371 static void zap_process(struct task_struct *start) 1372 { 1373 struct task_struct *t; 1374 1375 start->signal->flags = SIGNAL_GROUP_EXIT; 1376 start->signal->group_stop_count = 0; 1377 1378 t = start; 1379 do { 1380 if (t != current && t->mm) { 1381 t->mm->core_waiters++; 1382 sigaddset(&t->pending.signal, SIGKILL); 1383 signal_wake_up(t, 1); 1384 } 1385 } while ((t = next_thread(t)) != start); 1386 } 1387 1388 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 1389 int exit_code) 1390 { 1391 struct task_struct *g, *p; 1392 unsigned long flags; 1393 int err = -EAGAIN; 1394 1395 spin_lock_irq(&tsk->sighand->siglock); 1396 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) { 1397 tsk->signal->group_exit_code = exit_code; 1398 zap_process(tsk); 1399 err = 0; 1400 } 1401 spin_unlock_irq(&tsk->sighand->siglock); 1402 if (err) 1403 return err; 1404 1405 if (atomic_read(&mm->mm_users) == mm->core_waiters + 1) 1406 goto done; 1407 1408 rcu_read_lock(); 1409 for_each_process(g) { 1410 if (g == tsk->group_leader) 1411 continue; 1412 1413 p = g; 1414 do { 1415 if (p->mm) { 1416 if (p->mm == mm) { 1417 /* 1418 * p->sighand can't disappear, but 1419 * may be changed by de_thread() 1420 */ 1421 lock_task_sighand(p, &flags); 1422 zap_process(p); 1423 unlock_task_sighand(p, &flags); 1424 } 1425 break; 1426 } 1427 } while ((p = next_thread(p)) != g); 1428 } 1429 rcu_read_unlock(); 1430 done: 1431 return mm->core_waiters; 1432 } 1433 1434 static int coredump_wait(int exit_code) 1435 { 1436 struct task_struct *tsk = current; 1437 struct mm_struct *mm = tsk->mm; 1438 struct completion startup_done; 1439 struct completion *vfork_done; 1440 int core_waiters; 1441 1442 init_completion(&mm->core_done); 1443 init_completion(&startup_done); 1444 mm->core_startup_done = &startup_done; 1445 1446 core_waiters = zap_threads(tsk, mm, exit_code); 1447 up_write(&mm->mmap_sem); 1448 1449 if (unlikely(core_waiters < 0)) 1450 goto fail; 1451 1452 /* 1453 * Make sure nobody is waiting for us to release the VM, 1454 * otherwise we can deadlock when we wait on each other 1455 */ 1456 vfork_done = tsk->vfork_done; 1457 if (vfork_done) { 1458 tsk->vfork_done = NULL; 1459 complete(vfork_done); 1460 } 1461 1462 if (core_waiters) 1463 wait_for_completion(&startup_done); 1464 fail: 1465 BUG_ON(mm->core_waiters); 1466 return core_waiters; 1467 } 1468 1469 int do_coredump(long signr, int exit_code, struct pt_regs * regs) 1470 { 1471 char corename[CORENAME_MAX_SIZE + 1]; 1472 struct mm_struct *mm = current->mm; 1473 struct linux_binfmt * binfmt; 1474 struct inode * inode; 1475 struct file * file; 1476 int retval = 0; 1477 int fsuid = current->fsuid; 1478 int flag = 0; 1479 1480 binfmt = current->binfmt; 1481 if (!binfmt || !binfmt->core_dump) 1482 goto fail; 1483 down_write(&mm->mmap_sem); 1484 if (!mm->dumpable) { 1485 up_write(&mm->mmap_sem); 1486 goto fail; 1487 } 1488 1489 /* 1490 * We cannot trust fsuid as being the "true" uid of the 1491 * process nor do we know its entire history. We only know it 1492 * was tainted so we dump it as root in mode 2. 1493 */ 1494 if (mm->dumpable == 2) { /* Setuid core dump mode */ 1495 flag = O_EXCL; /* Stop rewrite attacks */ 1496 current->fsuid = 0; /* Dump root private */ 1497 } 1498 mm->dumpable = 0; 1499 1500 retval = coredump_wait(exit_code); 1501 if (retval < 0) 1502 goto fail; 1503 1504 /* 1505 * Clear any false indication of pending signals that might 1506 * be seen by the filesystem code called to write the core file. 1507 */ 1508 clear_thread_flag(TIF_SIGPENDING); 1509 1510 if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump) 1511 goto fail_unlock; 1512 1513 /* 1514 * lock_kernel() because format_corename() is controlled by sysctl, which 1515 * uses lock_kernel() 1516 */ 1517 lock_kernel(); 1518 format_corename(corename, core_pattern, signr); 1519 unlock_kernel(); 1520 file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600); 1521 if (IS_ERR(file)) 1522 goto fail_unlock; 1523 inode = file->f_dentry->d_inode; 1524 if (inode->i_nlink > 1) 1525 goto close_fail; /* multiple links - don't dump */ 1526 if (d_unhashed(file->f_dentry)) 1527 goto close_fail; 1528 1529 if (!S_ISREG(inode->i_mode)) 1530 goto close_fail; 1531 if (!file->f_op) 1532 goto close_fail; 1533 if (!file->f_op->write) 1534 goto close_fail; 1535 if (do_truncate(file->f_dentry, 0, 0, file) != 0) 1536 goto close_fail; 1537 1538 retval = binfmt->core_dump(signr, regs, file); 1539 1540 if (retval) 1541 current->signal->group_exit_code |= 0x80; 1542 close_fail: 1543 filp_close(file, NULL); 1544 fail_unlock: 1545 current->fsuid = fsuid; 1546 complete_all(&mm->core_done); 1547 fail: 1548 return retval; 1549 } 1550