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 53 #include <asm/uaccess.h> 54 #include <asm/mmu_context.h> 55 56 #ifdef CONFIG_KMOD 57 #include <linux/kmod.h> 58 #endif 59 60 int core_uses_pid; 61 char core_pattern[65] = "core"; 62 int suid_dumpable = 0; 63 64 EXPORT_SYMBOL(suid_dumpable); 65 /* The maximal length of core_pattern is also specified in sysctl.c */ 66 67 static struct linux_binfmt *formats; 68 static DEFINE_RWLOCK(binfmt_lock); 69 70 int register_binfmt(struct linux_binfmt * fmt) 71 { 72 struct linux_binfmt ** tmp = &formats; 73 74 if (!fmt) 75 return -EINVAL; 76 if (fmt->next) 77 return -EBUSY; 78 write_lock(&binfmt_lock); 79 while (*tmp) { 80 if (fmt == *tmp) { 81 write_unlock(&binfmt_lock); 82 return -EBUSY; 83 } 84 tmp = &(*tmp)->next; 85 } 86 fmt->next = formats; 87 formats = fmt; 88 write_unlock(&binfmt_lock); 89 return 0; 90 } 91 92 EXPORT_SYMBOL(register_binfmt); 93 94 int unregister_binfmt(struct linux_binfmt * fmt) 95 { 96 struct linux_binfmt ** tmp = &formats; 97 98 write_lock(&binfmt_lock); 99 while (*tmp) { 100 if (fmt == *tmp) { 101 *tmp = fmt->next; 102 write_unlock(&binfmt_lock); 103 return 0; 104 } 105 tmp = &(*tmp)->next; 106 } 107 write_unlock(&binfmt_lock); 108 return -EINVAL; 109 } 110 111 EXPORT_SYMBOL(unregister_binfmt); 112 113 static inline void put_binfmt(struct linux_binfmt * fmt) 114 { 115 module_put(fmt->module); 116 } 117 118 /* 119 * Note that a shared library must be both readable and executable due to 120 * security reasons. 121 * 122 * Also note that we take the address to load from from the file itself. 123 */ 124 asmlinkage long sys_uselib(const char __user * library) 125 { 126 struct file * file; 127 struct nameidata nd; 128 int error; 129 130 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ); 131 if (error) 132 goto out; 133 134 error = -EINVAL; 135 if (!S_ISREG(nd.dentry->d_inode->i_mode)) 136 goto exit; 137 138 error = vfs_permission(&nd, MAY_READ | MAY_EXEC); 139 if (error) 140 goto exit; 141 142 file = nameidata_to_filp(&nd, O_RDONLY); 143 error = PTR_ERR(file); 144 if (IS_ERR(file)) 145 goto out; 146 147 error = -ENOEXEC; 148 if(file->f_op) { 149 struct linux_binfmt * fmt; 150 151 read_lock(&binfmt_lock); 152 for (fmt = formats ; fmt ; fmt = fmt->next) { 153 if (!fmt->load_shlib) 154 continue; 155 if (!try_module_get(fmt->module)) 156 continue; 157 read_unlock(&binfmt_lock); 158 error = fmt->load_shlib(file); 159 read_lock(&binfmt_lock); 160 put_binfmt(fmt); 161 if (error != -ENOEXEC) 162 break; 163 } 164 read_unlock(&binfmt_lock); 165 } 166 fput(file); 167 out: 168 return error; 169 exit: 170 release_open_intent(&nd); 171 path_release(&nd); 172 goto out; 173 } 174 175 /* 176 * count() counts the number of strings in array ARGV. 177 */ 178 static int count(char __user * __user * argv, int max) 179 { 180 int i = 0; 181 182 if (argv != NULL) { 183 for (;;) { 184 char __user * p; 185 186 if (get_user(p, argv)) 187 return -EFAULT; 188 if (!p) 189 break; 190 argv++; 191 if(++i > max) 192 return -E2BIG; 193 cond_resched(); 194 } 195 } 196 return i; 197 } 198 199 /* 200 * 'copy_strings()' copies argument/environment strings from user 201 * memory to free pages in kernel mem. These are in a format ready 202 * to be put directly into the top of new user memory. 203 */ 204 static int copy_strings(int argc, char __user * __user * argv, 205 struct linux_binprm *bprm) 206 { 207 struct page *kmapped_page = NULL; 208 char *kaddr = NULL; 209 int ret; 210 211 while (argc-- > 0) { 212 char __user *str; 213 int len; 214 unsigned long pos; 215 216 if (get_user(str, argv+argc) || 217 !(len = strnlen_user(str, bprm->p))) { 218 ret = -EFAULT; 219 goto out; 220 } 221 222 if (bprm->p < len) { 223 ret = -E2BIG; 224 goto out; 225 } 226 227 bprm->p -= len; 228 /* XXX: add architecture specific overflow check here. */ 229 pos = bprm->p; 230 231 while (len > 0) { 232 int i, new, err; 233 int offset, bytes_to_copy; 234 struct page *page; 235 236 offset = pos % PAGE_SIZE; 237 i = pos/PAGE_SIZE; 238 page = bprm->page[i]; 239 new = 0; 240 if (!page) { 241 page = alloc_page(GFP_HIGHUSER); 242 bprm->page[i] = page; 243 if (!page) { 244 ret = -ENOMEM; 245 goto out; 246 } 247 new = 1; 248 } 249 250 if (page != kmapped_page) { 251 if (kmapped_page) 252 kunmap(kmapped_page); 253 kmapped_page = page; 254 kaddr = kmap(kmapped_page); 255 } 256 if (new && offset) 257 memset(kaddr, 0, offset); 258 bytes_to_copy = PAGE_SIZE - offset; 259 if (bytes_to_copy > len) { 260 bytes_to_copy = len; 261 if (new) 262 memset(kaddr+offset+len, 0, 263 PAGE_SIZE-offset-len); 264 } 265 err = copy_from_user(kaddr+offset, str, bytes_to_copy); 266 if (err) { 267 ret = -EFAULT; 268 goto out; 269 } 270 271 pos += bytes_to_copy; 272 str += bytes_to_copy; 273 len -= bytes_to_copy; 274 } 275 } 276 ret = 0; 277 out: 278 if (kmapped_page) 279 kunmap(kmapped_page); 280 return ret; 281 } 282 283 /* 284 * Like copy_strings, but get argv and its values from kernel memory. 285 */ 286 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm) 287 { 288 int r; 289 mm_segment_t oldfs = get_fs(); 290 set_fs(KERNEL_DS); 291 r = copy_strings(argc, (char __user * __user *)argv, bprm); 292 set_fs(oldfs); 293 return r; 294 } 295 296 EXPORT_SYMBOL(copy_strings_kernel); 297 298 #ifdef CONFIG_MMU 299 /* 300 * This routine is used to map in a page into an address space: needed by 301 * execve() for the initial stack and environment pages. 302 * 303 * vma->vm_mm->mmap_sem is held for writing. 304 */ 305 void install_arg_page(struct vm_area_struct *vma, 306 struct page *page, unsigned long address) 307 { 308 struct mm_struct *mm = vma->vm_mm; 309 pte_t * pte; 310 spinlock_t *ptl; 311 312 if (unlikely(anon_vma_prepare(vma))) 313 goto out; 314 315 flush_dcache_page(page); 316 pte = get_locked_pte(mm, address, &ptl); 317 if (!pte) 318 goto out; 319 if (!pte_none(*pte)) { 320 pte_unmap_unlock(pte, ptl); 321 goto out; 322 } 323 inc_mm_counter(mm, anon_rss); 324 lru_cache_add_active(page); 325 set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte( 326 page, vma->vm_page_prot)))); 327 page_add_new_anon_rmap(page, vma, address); 328 pte_unmap_unlock(pte, ptl); 329 330 /* no need for flush_tlb */ 331 return; 332 out: 333 __free_page(page); 334 force_sig(SIGKILL, current); 335 } 336 337 #define EXTRA_STACK_VM_PAGES 20 /* random */ 338 339 int setup_arg_pages(struct linux_binprm *bprm, 340 unsigned long stack_top, 341 int executable_stack) 342 { 343 unsigned long stack_base; 344 struct vm_area_struct *mpnt; 345 struct mm_struct *mm = current->mm; 346 int i, ret; 347 long arg_size; 348 349 #ifdef CONFIG_STACK_GROWSUP 350 /* Move the argument and environment strings to the bottom of the 351 * stack space. 352 */ 353 int offset, j; 354 char *to, *from; 355 356 /* Start by shifting all the pages down */ 357 i = 0; 358 for (j = 0; j < MAX_ARG_PAGES; j++) { 359 struct page *page = bprm->page[j]; 360 if (!page) 361 continue; 362 bprm->page[i++] = page; 363 } 364 365 /* Now move them within their pages */ 366 offset = bprm->p % PAGE_SIZE; 367 to = kmap(bprm->page[0]); 368 for (j = 1; j < i; j++) { 369 memmove(to, to + offset, PAGE_SIZE - offset); 370 from = kmap(bprm->page[j]); 371 memcpy(to + PAGE_SIZE - offset, from, offset); 372 kunmap(bprm->page[j - 1]); 373 to = from; 374 } 375 memmove(to, to + offset, PAGE_SIZE - offset); 376 kunmap(bprm->page[j - 1]); 377 378 /* Limit stack size to 1GB */ 379 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max; 380 if (stack_base > (1 << 30)) 381 stack_base = 1 << 30; 382 stack_base = PAGE_ALIGN(stack_top - stack_base); 383 384 /* Adjust bprm->p to point to the end of the strings. */ 385 bprm->p = stack_base + PAGE_SIZE * i - offset; 386 387 mm->arg_start = stack_base; 388 arg_size = i << PAGE_SHIFT; 389 390 /* zero pages that were copied above */ 391 while (i < MAX_ARG_PAGES) 392 bprm->page[i++] = NULL; 393 #else 394 stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE); 395 stack_base = PAGE_ALIGN(stack_base); 396 bprm->p += stack_base; 397 mm->arg_start = bprm->p; 398 arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start); 399 #endif 400 401 arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE; 402 403 if (bprm->loader) 404 bprm->loader += stack_base; 405 bprm->exec += stack_base; 406 407 mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 408 if (!mpnt) 409 return -ENOMEM; 410 411 memset(mpnt, 0, sizeof(*mpnt)); 412 413 down_write(&mm->mmap_sem); 414 { 415 mpnt->vm_mm = mm; 416 #ifdef CONFIG_STACK_GROWSUP 417 mpnt->vm_start = stack_base; 418 mpnt->vm_end = stack_base + arg_size; 419 #else 420 mpnt->vm_end = stack_top; 421 mpnt->vm_start = mpnt->vm_end - arg_size; 422 #endif 423 /* Adjust stack execute permissions; explicitly enable 424 * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X 425 * and leave alone (arch default) otherwise. */ 426 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 427 mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC; 428 else if (executable_stack == EXSTACK_DISABLE_X) 429 mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC; 430 else 431 mpnt->vm_flags = VM_STACK_FLAGS; 432 mpnt->vm_flags |= mm->def_flags; 433 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7]; 434 if ((ret = insert_vm_struct(mm, mpnt))) { 435 up_write(&mm->mmap_sem); 436 kmem_cache_free(vm_area_cachep, mpnt); 437 return ret; 438 } 439 mm->stack_vm = mm->total_vm = vma_pages(mpnt); 440 } 441 442 for (i = 0 ; i < MAX_ARG_PAGES ; i++) { 443 struct page *page = bprm->page[i]; 444 if (page) { 445 bprm->page[i] = NULL; 446 install_arg_page(mpnt, page, stack_base); 447 } 448 stack_base += PAGE_SIZE; 449 } 450 up_write(&mm->mmap_sem); 451 452 return 0; 453 } 454 455 EXPORT_SYMBOL(setup_arg_pages); 456 457 #define free_arg_pages(bprm) do { } while (0) 458 459 #else 460 461 static inline void free_arg_pages(struct linux_binprm *bprm) 462 { 463 int i; 464 465 for (i = 0; i < MAX_ARG_PAGES; i++) { 466 if (bprm->page[i]) 467 __free_page(bprm->page[i]); 468 bprm->page[i] = NULL; 469 } 470 } 471 472 #endif /* CONFIG_MMU */ 473 474 struct file *open_exec(const char *name) 475 { 476 struct nameidata nd; 477 int err; 478 struct file *file; 479 480 err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ); 481 file = ERR_PTR(err); 482 483 if (!err) { 484 struct inode *inode = nd.dentry->d_inode; 485 file = ERR_PTR(-EACCES); 486 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) && 487 S_ISREG(inode->i_mode)) { 488 int err = vfs_permission(&nd, MAY_EXEC); 489 if (!err && !(inode->i_mode & 0111)) 490 err = -EACCES; 491 file = ERR_PTR(err); 492 if (!err) { 493 file = nameidata_to_filp(&nd, O_RDONLY); 494 if (!IS_ERR(file)) { 495 err = deny_write_access(file); 496 if (err) { 497 fput(file); 498 file = ERR_PTR(err); 499 } 500 } 501 out: 502 return file; 503 } 504 } 505 release_open_intent(&nd); 506 path_release(&nd); 507 } 508 goto out; 509 } 510 511 EXPORT_SYMBOL(open_exec); 512 513 int kernel_read(struct file *file, unsigned long offset, 514 char *addr, unsigned long count) 515 { 516 mm_segment_t old_fs; 517 loff_t pos = offset; 518 int result; 519 520 old_fs = get_fs(); 521 set_fs(get_ds()); 522 /* The cast to a user pointer is valid due to the set_fs() */ 523 result = vfs_read(file, (void __user *)addr, count, &pos); 524 set_fs(old_fs); 525 return result; 526 } 527 528 EXPORT_SYMBOL(kernel_read); 529 530 static int exec_mmap(struct mm_struct *mm) 531 { 532 struct task_struct *tsk; 533 struct mm_struct * old_mm, *active_mm; 534 535 /* Notify parent that we're no longer interested in the old VM */ 536 tsk = current; 537 old_mm = current->mm; 538 mm_release(tsk, old_mm); 539 540 if (old_mm) { 541 /* 542 * Make sure that if there is a core dump in progress 543 * for the old mm, we get out and die instead of going 544 * through with the exec. We must hold mmap_sem around 545 * checking core_waiters and changing tsk->mm. The 546 * core-inducing thread will increment core_waiters for 547 * each thread whose ->mm == old_mm. 548 */ 549 down_read(&old_mm->mmap_sem); 550 if (unlikely(old_mm->core_waiters)) { 551 up_read(&old_mm->mmap_sem); 552 return -EINTR; 553 } 554 } 555 task_lock(tsk); 556 active_mm = tsk->active_mm; 557 tsk->mm = mm; 558 tsk->active_mm = mm; 559 activate_mm(active_mm, mm); 560 task_unlock(tsk); 561 arch_pick_mmap_layout(mm); 562 if (old_mm) { 563 up_read(&old_mm->mmap_sem); 564 if (active_mm != old_mm) BUG(); 565 mmput(old_mm); 566 return 0; 567 } 568 mmdrop(active_mm); 569 return 0; 570 } 571 572 /* 573 * This function makes sure the current process has its own signal table, 574 * so that flush_signal_handlers can later reset the handlers without 575 * disturbing other processes. (Other processes might share the signal 576 * table via the CLONE_SIGHAND option to clone().) 577 */ 578 static inline int de_thread(struct task_struct *tsk) 579 { 580 struct signal_struct *sig = tsk->signal; 581 struct sighand_struct *newsighand, *oldsighand = tsk->sighand; 582 spinlock_t *lock = &oldsighand->siglock; 583 struct task_struct *leader = NULL; 584 int count; 585 586 /* 587 * If we don't share sighandlers, then we aren't sharing anything 588 * and we can just re-use it all. 589 */ 590 if (atomic_read(&oldsighand->count) <= 1) { 591 BUG_ON(atomic_read(&sig->count) != 1); 592 exit_itimers(sig); 593 return 0; 594 } 595 596 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 597 if (!newsighand) 598 return -ENOMEM; 599 600 if (thread_group_empty(current)) 601 goto no_thread_group; 602 603 /* 604 * Kill all other threads in the thread group. 605 * We must hold tasklist_lock to call zap_other_threads. 606 */ 607 read_lock(&tasklist_lock); 608 spin_lock_irq(lock); 609 if (sig->flags & SIGNAL_GROUP_EXIT) { 610 /* 611 * Another group action in progress, just 612 * return so that the signal is processed. 613 */ 614 spin_unlock_irq(lock); 615 read_unlock(&tasklist_lock); 616 kmem_cache_free(sighand_cachep, newsighand); 617 return -EAGAIN; 618 } 619 zap_other_threads(current); 620 read_unlock(&tasklist_lock); 621 622 /* 623 * Account for the thread group leader hanging around: 624 */ 625 count = 1; 626 if (!thread_group_leader(current)) { 627 count = 2; 628 /* 629 * The SIGALRM timer survives the exec, but needs to point 630 * at us as the new group leader now. We have a race with 631 * a timer firing now getting the old leader, so we need to 632 * synchronize with any firing (by calling del_timer_sync) 633 * before we can safely let the old group leader die. 634 */ 635 sig->real_timer.data = current; 636 spin_unlock_irq(lock); 637 if (hrtimer_cancel(&sig->real_timer)) 638 hrtimer_restart(&sig->real_timer); 639 spin_lock_irq(lock); 640 } 641 while (atomic_read(&sig->count) > count) { 642 sig->group_exit_task = current; 643 sig->notify_count = count; 644 __set_current_state(TASK_UNINTERRUPTIBLE); 645 spin_unlock_irq(lock); 646 schedule(); 647 spin_lock_irq(lock); 648 } 649 sig->group_exit_task = NULL; 650 sig->notify_count = 0; 651 spin_unlock_irq(lock); 652 653 /* 654 * At this point all other threads have exited, all we have to 655 * do is to wait for the thread group leader to become inactive, 656 * and to assume its PID: 657 */ 658 if (!thread_group_leader(current)) { 659 struct task_struct *parent; 660 struct dentry *proc_dentry1, *proc_dentry2; 661 unsigned long ptrace; 662 663 /* 664 * Wait for the thread group leader to be a zombie. 665 * It should already be zombie at this point, most 666 * of the time. 667 */ 668 leader = current->group_leader; 669 while (leader->exit_state != EXIT_ZOMBIE) 670 yield(); 671 672 spin_lock(&leader->proc_lock); 673 spin_lock(¤t->proc_lock); 674 proc_dentry1 = proc_pid_unhash(current); 675 proc_dentry2 = proc_pid_unhash(leader); 676 write_lock_irq(&tasklist_lock); 677 678 BUG_ON(leader->tgid != current->tgid); 679 BUG_ON(current->pid == current->tgid); 680 /* 681 * An exec() starts a new thread group with the 682 * TGID of the previous thread group. Rehash the 683 * two threads with a switched PID, and release 684 * the former thread group leader: 685 */ 686 ptrace = leader->ptrace; 687 parent = leader->parent; 688 if (unlikely(ptrace) && unlikely(parent == current)) { 689 /* 690 * Joker was ptracing his own group leader, 691 * and now he wants to be his own parent! 692 * We can't have that. 693 */ 694 ptrace = 0; 695 } 696 697 ptrace_unlink(current); 698 ptrace_unlink(leader); 699 remove_parent(current); 700 remove_parent(leader); 701 702 switch_exec_pids(leader, current); 703 704 current->parent = current->real_parent = leader->real_parent; 705 leader->parent = leader->real_parent = child_reaper; 706 current->group_leader = current; 707 leader->group_leader = leader; 708 709 add_parent(current, current->parent); 710 add_parent(leader, leader->parent); 711 if (ptrace) { 712 current->ptrace = ptrace; 713 __ptrace_link(current, parent); 714 } 715 716 list_del(¤t->tasks); 717 list_add_tail(¤t->tasks, &init_task.tasks); 718 current->exit_signal = SIGCHLD; 719 720 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 721 leader->exit_state = EXIT_DEAD; 722 723 write_unlock_irq(&tasklist_lock); 724 spin_unlock(&leader->proc_lock); 725 spin_unlock(¤t->proc_lock); 726 proc_pid_flush(proc_dentry1); 727 proc_pid_flush(proc_dentry2); 728 } 729 730 /* 731 * There may be one thread left which is just exiting, 732 * but it's safe to stop telling the group to kill themselves. 733 */ 734 sig->flags = 0; 735 736 no_thread_group: 737 exit_itimers(sig); 738 if (leader) 739 release_task(leader); 740 741 BUG_ON(atomic_read(&sig->count) != 1); 742 743 if (atomic_read(&oldsighand->count) == 1) { 744 /* 745 * Now that we nuked the rest of the thread group, 746 * it turns out we are not sharing sighand any more either. 747 * So we can just keep it. 748 */ 749 kmem_cache_free(sighand_cachep, newsighand); 750 } else { 751 /* 752 * Move our state over to newsighand and switch it in. 753 */ 754 spin_lock_init(&newsighand->siglock); 755 atomic_set(&newsighand->count, 1); 756 memcpy(newsighand->action, oldsighand->action, 757 sizeof(newsighand->action)); 758 759 write_lock_irq(&tasklist_lock); 760 spin_lock(&oldsighand->siglock); 761 spin_lock(&newsighand->siglock); 762 763 rcu_assign_pointer(current->sighand, newsighand); 764 recalc_sigpending(); 765 766 spin_unlock(&newsighand->siglock); 767 spin_unlock(&oldsighand->siglock); 768 write_unlock_irq(&tasklist_lock); 769 770 if (atomic_dec_and_test(&oldsighand->count)) 771 sighand_free(oldsighand); 772 } 773 774 BUG_ON(!thread_group_leader(current)); 775 return 0; 776 } 777 778 /* 779 * These functions flushes out all traces of the currently running executable 780 * so that a new one can be started 781 */ 782 783 static inline void flush_old_files(struct files_struct * files) 784 { 785 long j = -1; 786 struct fdtable *fdt; 787 788 spin_lock(&files->file_lock); 789 for (;;) { 790 unsigned long set, i; 791 792 j++; 793 i = j * __NFDBITS; 794 fdt = files_fdtable(files); 795 if (i >= fdt->max_fds || i >= fdt->max_fdset) 796 break; 797 set = fdt->close_on_exec->fds_bits[j]; 798 if (!set) 799 continue; 800 fdt->close_on_exec->fds_bits[j] = 0; 801 spin_unlock(&files->file_lock); 802 for ( ; set ; i++,set >>= 1) { 803 if (set & 1) { 804 sys_close(i); 805 } 806 } 807 spin_lock(&files->file_lock); 808 809 } 810 spin_unlock(&files->file_lock); 811 } 812 813 void get_task_comm(char *buf, struct task_struct *tsk) 814 { 815 /* buf must be at least sizeof(tsk->comm) in size */ 816 task_lock(tsk); 817 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 818 task_unlock(tsk); 819 } 820 821 void set_task_comm(struct task_struct *tsk, char *buf) 822 { 823 task_lock(tsk); 824 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 825 task_unlock(tsk); 826 } 827 828 int flush_old_exec(struct linux_binprm * bprm) 829 { 830 char * name; 831 int i, ch, retval; 832 struct files_struct *files; 833 char tcomm[sizeof(current->comm)]; 834 835 /* 836 * Make sure we have a private signal table and that 837 * we are unassociated from the previous thread group. 838 */ 839 retval = de_thread(current); 840 if (retval) 841 goto out; 842 843 /* 844 * Make sure we have private file handles. Ask the 845 * fork helper to do the work for us and the exit 846 * helper to do the cleanup of the old one. 847 */ 848 files = current->files; /* refcounted so safe to hold */ 849 retval = unshare_files(); 850 if (retval) 851 goto out; 852 /* 853 * Release all of the old mmap stuff 854 */ 855 retval = exec_mmap(bprm->mm); 856 if (retval) 857 goto mmap_failed; 858 859 bprm->mm = NULL; /* We're using it now */ 860 861 /* This is the point of no return */ 862 steal_locks(files); 863 put_files_struct(files); 864 865 current->sas_ss_sp = current->sas_ss_size = 0; 866 867 if (current->euid == current->uid && current->egid == current->gid) 868 current->mm->dumpable = 1; 869 else 870 current->mm->dumpable = suid_dumpable; 871 872 name = bprm->filename; 873 874 /* Copies the binary name from after last slash */ 875 for (i=0; (ch = *(name++)) != '\0';) { 876 if (ch == '/') 877 i = 0; /* overwrite what we wrote */ 878 else 879 if (i < (sizeof(tcomm) - 1)) 880 tcomm[i++] = ch; 881 } 882 tcomm[i] = '\0'; 883 set_task_comm(current, tcomm); 884 885 current->flags &= ~PF_RANDOMIZE; 886 flush_thread(); 887 888 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 889 file_permission(bprm->file, MAY_READ) || 890 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { 891 suid_keys(current); 892 current->mm->dumpable = suid_dumpable; 893 } 894 895 /* An exec changes our domain. We are no longer part of the thread 896 group */ 897 898 current->self_exec_id++; 899 900 flush_signal_handlers(current, 0); 901 flush_old_files(current->files); 902 903 return 0; 904 905 mmap_failed: 906 put_files_struct(current->files); 907 current->files = files; 908 out: 909 return retval; 910 } 911 912 EXPORT_SYMBOL(flush_old_exec); 913 914 /* 915 * Fill the binprm structure from the inode. 916 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 917 */ 918 int prepare_binprm(struct linux_binprm *bprm) 919 { 920 int mode; 921 struct inode * inode = bprm->file->f_dentry->d_inode; 922 int retval; 923 924 mode = inode->i_mode; 925 /* 926 * Check execute perms again - if the caller has CAP_DAC_OVERRIDE, 927 * generic_permission lets a non-executable through 928 */ 929 if (!(mode & 0111)) /* with at least _one_ execute bit set */ 930 return -EACCES; 931 if (bprm->file->f_op == NULL) 932 return -EACCES; 933 934 bprm->e_uid = current->euid; 935 bprm->e_gid = current->egid; 936 937 if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) { 938 /* Set-uid? */ 939 if (mode & S_ISUID) { 940 current->personality &= ~PER_CLEAR_ON_SETID; 941 bprm->e_uid = inode->i_uid; 942 } 943 944 /* Set-gid? */ 945 /* 946 * If setgid is set but no group execute bit then this 947 * is a candidate for mandatory locking, not a setgid 948 * executable. 949 */ 950 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 951 current->personality &= ~PER_CLEAR_ON_SETID; 952 bprm->e_gid = inode->i_gid; 953 } 954 } 955 956 /* fill in binprm security blob */ 957 retval = security_bprm_set(bprm); 958 if (retval) 959 return retval; 960 961 memset(bprm->buf,0,BINPRM_BUF_SIZE); 962 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE); 963 } 964 965 EXPORT_SYMBOL(prepare_binprm); 966 967 static inline int unsafe_exec(struct task_struct *p) 968 { 969 int unsafe = 0; 970 if (p->ptrace & PT_PTRACED) { 971 if (p->ptrace & PT_PTRACE_CAP) 972 unsafe |= LSM_UNSAFE_PTRACE_CAP; 973 else 974 unsafe |= LSM_UNSAFE_PTRACE; 975 } 976 if (atomic_read(&p->fs->count) > 1 || 977 atomic_read(&p->files->count) > 1 || 978 atomic_read(&p->sighand->count) > 1) 979 unsafe |= LSM_UNSAFE_SHARE; 980 981 return unsafe; 982 } 983 984 void compute_creds(struct linux_binprm *bprm) 985 { 986 int unsafe; 987 988 if (bprm->e_uid != current->uid) 989 suid_keys(current); 990 exec_keys(current); 991 992 task_lock(current); 993 unsafe = unsafe_exec(current); 994 security_bprm_apply_creds(bprm, unsafe); 995 task_unlock(current); 996 security_bprm_post_apply_creds(bprm); 997 } 998 999 EXPORT_SYMBOL(compute_creds); 1000 1001 void remove_arg_zero(struct linux_binprm *bprm) 1002 { 1003 if (bprm->argc) { 1004 unsigned long offset; 1005 char * kaddr; 1006 struct page *page; 1007 1008 offset = bprm->p % PAGE_SIZE; 1009 goto inside; 1010 1011 while (bprm->p++, *(kaddr+offset++)) { 1012 if (offset != PAGE_SIZE) 1013 continue; 1014 offset = 0; 1015 kunmap_atomic(kaddr, KM_USER0); 1016 inside: 1017 page = bprm->page[bprm->p/PAGE_SIZE]; 1018 kaddr = kmap_atomic(page, KM_USER0); 1019 } 1020 kunmap_atomic(kaddr, KM_USER0); 1021 bprm->argc--; 1022 } 1023 } 1024 1025 EXPORT_SYMBOL(remove_arg_zero); 1026 1027 /* 1028 * cycle the list of binary formats handler, until one recognizes the image 1029 */ 1030 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) 1031 { 1032 int try,retval; 1033 struct linux_binfmt *fmt; 1034 #ifdef __alpha__ 1035 /* handle /sbin/loader.. */ 1036 { 1037 struct exec * eh = (struct exec *) bprm->buf; 1038 1039 if (!bprm->loader && eh->fh.f_magic == 0x183 && 1040 (eh->fh.f_flags & 0x3000) == 0x3000) 1041 { 1042 struct file * file; 1043 unsigned long loader; 1044 1045 allow_write_access(bprm->file); 1046 fput(bprm->file); 1047 bprm->file = NULL; 1048 1049 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *); 1050 1051 file = open_exec("/sbin/loader"); 1052 retval = PTR_ERR(file); 1053 if (IS_ERR(file)) 1054 return retval; 1055 1056 /* Remember if the application is TASO. */ 1057 bprm->sh_bang = eh->ah.entry < 0x100000000UL; 1058 1059 bprm->file = file; 1060 bprm->loader = loader; 1061 retval = prepare_binprm(bprm); 1062 if (retval<0) 1063 return retval; 1064 /* should call search_binary_handler recursively here, 1065 but it does not matter */ 1066 } 1067 } 1068 #endif 1069 retval = security_bprm_check(bprm); 1070 if (retval) 1071 return retval; 1072 1073 /* kernel module loader fixup */ 1074 /* so we don't try to load run modprobe in kernel space. */ 1075 set_fs(USER_DS); 1076 retval = -ENOENT; 1077 for (try=0; try<2; try++) { 1078 read_lock(&binfmt_lock); 1079 for (fmt = formats ; fmt ; fmt = fmt->next) { 1080 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; 1081 if (!fn) 1082 continue; 1083 if (!try_module_get(fmt->module)) 1084 continue; 1085 read_unlock(&binfmt_lock); 1086 retval = fn(bprm, regs); 1087 if (retval >= 0) { 1088 put_binfmt(fmt); 1089 allow_write_access(bprm->file); 1090 if (bprm->file) 1091 fput(bprm->file); 1092 bprm->file = NULL; 1093 current->did_exec = 1; 1094 proc_exec_connector(current); 1095 return retval; 1096 } 1097 read_lock(&binfmt_lock); 1098 put_binfmt(fmt); 1099 if (retval != -ENOEXEC || bprm->mm == NULL) 1100 break; 1101 if (!bprm->file) { 1102 read_unlock(&binfmt_lock); 1103 return retval; 1104 } 1105 } 1106 read_unlock(&binfmt_lock); 1107 if (retval != -ENOEXEC || bprm->mm == NULL) { 1108 break; 1109 #ifdef CONFIG_KMOD 1110 }else{ 1111 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1112 if (printable(bprm->buf[0]) && 1113 printable(bprm->buf[1]) && 1114 printable(bprm->buf[2]) && 1115 printable(bprm->buf[3])) 1116 break; /* -ENOEXEC */ 1117 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1118 #endif 1119 } 1120 } 1121 return retval; 1122 } 1123 1124 EXPORT_SYMBOL(search_binary_handler); 1125 1126 /* 1127 * sys_execve() executes a new program. 1128 */ 1129 int do_execve(char * filename, 1130 char __user *__user *argv, 1131 char __user *__user *envp, 1132 struct pt_regs * regs) 1133 { 1134 struct linux_binprm *bprm; 1135 struct file *file; 1136 int retval; 1137 int i; 1138 1139 retval = -ENOMEM; 1140 bprm = kmalloc(sizeof(*bprm), GFP_KERNEL); 1141 if (!bprm) 1142 goto out_ret; 1143 memset(bprm, 0, sizeof(*bprm)); 1144 1145 file = open_exec(filename); 1146 retval = PTR_ERR(file); 1147 if (IS_ERR(file)) 1148 goto out_kfree; 1149 1150 sched_exec(); 1151 1152 bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *); 1153 1154 bprm->file = file; 1155 bprm->filename = filename; 1156 bprm->interp = filename; 1157 bprm->mm = mm_alloc(); 1158 retval = -ENOMEM; 1159 if (!bprm->mm) 1160 goto out_file; 1161 1162 retval = init_new_context(current, bprm->mm); 1163 if (retval < 0) 1164 goto out_mm; 1165 1166 bprm->argc = count(argv, bprm->p / sizeof(void *)); 1167 if ((retval = bprm->argc) < 0) 1168 goto out_mm; 1169 1170 bprm->envc = count(envp, bprm->p / sizeof(void *)); 1171 if ((retval = bprm->envc) < 0) 1172 goto out_mm; 1173 1174 retval = security_bprm_alloc(bprm); 1175 if (retval) 1176 goto out; 1177 1178 retval = prepare_binprm(bprm); 1179 if (retval < 0) 1180 goto out; 1181 1182 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1183 if (retval < 0) 1184 goto out; 1185 1186 bprm->exec = bprm->p; 1187 retval = copy_strings(bprm->envc, envp, bprm); 1188 if (retval < 0) 1189 goto out; 1190 1191 retval = copy_strings(bprm->argc, argv, bprm); 1192 if (retval < 0) 1193 goto out; 1194 1195 retval = search_binary_handler(bprm,regs); 1196 if (retval >= 0) { 1197 free_arg_pages(bprm); 1198 1199 /* execve success */ 1200 security_bprm_free(bprm); 1201 acct_update_integrals(current); 1202 kfree(bprm); 1203 return retval; 1204 } 1205 1206 out: 1207 /* Something went wrong, return the inode and free the argument pages*/ 1208 for (i = 0 ; i < MAX_ARG_PAGES ; i++) { 1209 struct page * page = bprm->page[i]; 1210 if (page) 1211 __free_page(page); 1212 } 1213 1214 if (bprm->security) 1215 security_bprm_free(bprm); 1216 1217 out_mm: 1218 if (bprm->mm) 1219 mmdrop(bprm->mm); 1220 1221 out_file: 1222 if (bprm->file) { 1223 allow_write_access(bprm->file); 1224 fput(bprm->file); 1225 } 1226 1227 out_kfree: 1228 kfree(bprm); 1229 1230 out_ret: 1231 return retval; 1232 } 1233 1234 int set_binfmt(struct linux_binfmt *new) 1235 { 1236 struct linux_binfmt *old = current->binfmt; 1237 1238 if (new) { 1239 if (!try_module_get(new->module)) 1240 return -1; 1241 } 1242 current->binfmt = new; 1243 if (old) 1244 module_put(old->module); 1245 return 0; 1246 } 1247 1248 EXPORT_SYMBOL(set_binfmt); 1249 1250 #define CORENAME_MAX_SIZE 64 1251 1252 /* format_corename will inspect the pattern parameter, and output a 1253 * name into corename, which must have space for at least 1254 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 1255 */ 1256 static void format_corename(char *corename, const char *pattern, long signr) 1257 { 1258 const char *pat_ptr = pattern; 1259 char *out_ptr = corename; 1260 char *const out_end = corename + CORENAME_MAX_SIZE; 1261 int rc; 1262 int pid_in_pattern = 0; 1263 1264 /* Repeat as long as we have more pattern to process and more output 1265 space */ 1266 while (*pat_ptr) { 1267 if (*pat_ptr != '%') { 1268 if (out_ptr == out_end) 1269 goto out; 1270 *out_ptr++ = *pat_ptr++; 1271 } else { 1272 switch (*++pat_ptr) { 1273 case 0: 1274 goto out; 1275 /* Double percent, output one percent */ 1276 case '%': 1277 if (out_ptr == out_end) 1278 goto out; 1279 *out_ptr++ = '%'; 1280 break; 1281 /* pid */ 1282 case 'p': 1283 pid_in_pattern = 1; 1284 rc = snprintf(out_ptr, out_end - out_ptr, 1285 "%d", current->tgid); 1286 if (rc > out_end - out_ptr) 1287 goto out; 1288 out_ptr += rc; 1289 break; 1290 /* uid */ 1291 case 'u': 1292 rc = snprintf(out_ptr, out_end - out_ptr, 1293 "%d", current->uid); 1294 if (rc > out_end - out_ptr) 1295 goto out; 1296 out_ptr += rc; 1297 break; 1298 /* gid */ 1299 case 'g': 1300 rc = snprintf(out_ptr, out_end - out_ptr, 1301 "%d", current->gid); 1302 if (rc > out_end - out_ptr) 1303 goto out; 1304 out_ptr += rc; 1305 break; 1306 /* signal that caused the coredump */ 1307 case 's': 1308 rc = snprintf(out_ptr, out_end - out_ptr, 1309 "%ld", signr); 1310 if (rc > out_end - out_ptr) 1311 goto out; 1312 out_ptr += rc; 1313 break; 1314 /* UNIX time of coredump */ 1315 case 't': { 1316 struct timeval tv; 1317 do_gettimeofday(&tv); 1318 rc = snprintf(out_ptr, out_end - out_ptr, 1319 "%lu", tv.tv_sec); 1320 if (rc > out_end - out_ptr) 1321 goto out; 1322 out_ptr += rc; 1323 break; 1324 } 1325 /* hostname */ 1326 case 'h': 1327 down_read(&uts_sem); 1328 rc = snprintf(out_ptr, out_end - out_ptr, 1329 "%s", system_utsname.nodename); 1330 up_read(&uts_sem); 1331 if (rc > out_end - out_ptr) 1332 goto out; 1333 out_ptr += rc; 1334 break; 1335 /* executable */ 1336 case 'e': 1337 rc = snprintf(out_ptr, out_end - out_ptr, 1338 "%s", current->comm); 1339 if (rc > out_end - out_ptr) 1340 goto out; 1341 out_ptr += rc; 1342 break; 1343 default: 1344 break; 1345 } 1346 ++pat_ptr; 1347 } 1348 } 1349 /* Backward compatibility with core_uses_pid: 1350 * 1351 * If core_pattern does not include a %p (as is the default) 1352 * and core_uses_pid is set, then .%pid will be appended to 1353 * the filename */ 1354 if (!pid_in_pattern 1355 && (core_uses_pid || atomic_read(¤t->mm->mm_users) != 1)) { 1356 rc = snprintf(out_ptr, out_end - out_ptr, 1357 ".%d", current->tgid); 1358 if (rc > out_end - out_ptr) 1359 goto out; 1360 out_ptr += rc; 1361 } 1362 out: 1363 *out_ptr = 0; 1364 } 1365 1366 static void zap_threads (struct mm_struct *mm) 1367 { 1368 struct task_struct *g, *p; 1369 struct task_struct *tsk = current; 1370 struct completion *vfork_done = tsk->vfork_done; 1371 int traced = 0; 1372 1373 /* 1374 * Make sure nobody is waiting for us to release the VM, 1375 * otherwise we can deadlock when we wait on each other 1376 */ 1377 if (vfork_done) { 1378 tsk->vfork_done = NULL; 1379 complete(vfork_done); 1380 } 1381 1382 read_lock(&tasklist_lock); 1383 do_each_thread(g,p) 1384 if (mm == p->mm && p != tsk) { 1385 force_sig_specific(SIGKILL, p); 1386 mm->core_waiters++; 1387 if (unlikely(p->ptrace) && 1388 unlikely(p->parent->mm == mm)) 1389 traced = 1; 1390 } 1391 while_each_thread(g,p); 1392 1393 read_unlock(&tasklist_lock); 1394 1395 if (unlikely(traced)) { 1396 /* 1397 * We are zapping a thread and the thread it ptraces. 1398 * If the tracee went into a ptrace stop for exit tracing, 1399 * we could deadlock since the tracer is waiting for this 1400 * coredump to finish. Detach them so they can both die. 1401 */ 1402 write_lock_irq(&tasklist_lock); 1403 do_each_thread(g,p) { 1404 if (mm == p->mm && p != tsk && 1405 p->ptrace && p->parent->mm == mm) { 1406 __ptrace_unlink(p); 1407 } 1408 } while_each_thread(g,p); 1409 write_unlock_irq(&tasklist_lock); 1410 } 1411 } 1412 1413 static void coredump_wait(struct mm_struct *mm) 1414 { 1415 DECLARE_COMPLETION(startup_done); 1416 int core_waiters; 1417 1418 mm->core_startup_done = &startup_done; 1419 1420 zap_threads(mm); 1421 core_waiters = mm->core_waiters; 1422 up_write(&mm->mmap_sem); 1423 1424 if (core_waiters) 1425 wait_for_completion(&startup_done); 1426 BUG_ON(mm->core_waiters); 1427 } 1428 1429 int do_coredump(long signr, int exit_code, struct pt_regs * regs) 1430 { 1431 char corename[CORENAME_MAX_SIZE + 1]; 1432 struct mm_struct *mm = current->mm; 1433 struct linux_binfmt * binfmt; 1434 struct inode * inode; 1435 struct file * file; 1436 int retval = 0; 1437 int fsuid = current->fsuid; 1438 int flag = 0; 1439 1440 binfmt = current->binfmt; 1441 if (!binfmt || !binfmt->core_dump) 1442 goto fail; 1443 down_write(&mm->mmap_sem); 1444 if (!mm->dumpable) { 1445 up_write(&mm->mmap_sem); 1446 goto fail; 1447 } 1448 1449 /* 1450 * We cannot trust fsuid as being the "true" uid of the 1451 * process nor do we know its entire history. We only know it 1452 * was tainted so we dump it as root in mode 2. 1453 */ 1454 if (mm->dumpable == 2) { /* Setuid core dump mode */ 1455 flag = O_EXCL; /* Stop rewrite attacks */ 1456 current->fsuid = 0; /* Dump root private */ 1457 } 1458 mm->dumpable = 0; 1459 1460 retval = -EAGAIN; 1461 spin_lock_irq(¤t->sighand->siglock); 1462 if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) { 1463 current->signal->flags = SIGNAL_GROUP_EXIT; 1464 current->signal->group_exit_code = exit_code; 1465 current->signal->group_stop_count = 0; 1466 retval = 0; 1467 } 1468 spin_unlock_irq(¤t->sighand->siglock); 1469 if (retval) { 1470 up_write(&mm->mmap_sem); 1471 goto fail; 1472 } 1473 1474 init_completion(&mm->core_done); 1475 coredump_wait(mm); 1476 1477 /* 1478 * Clear any false indication of pending signals that might 1479 * be seen by the filesystem code called to write the core file. 1480 */ 1481 clear_thread_flag(TIF_SIGPENDING); 1482 1483 if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump) 1484 goto fail_unlock; 1485 1486 /* 1487 * lock_kernel() because format_corename() is controlled by sysctl, which 1488 * uses lock_kernel() 1489 */ 1490 lock_kernel(); 1491 format_corename(corename, core_pattern, signr); 1492 unlock_kernel(); 1493 file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600); 1494 if (IS_ERR(file)) 1495 goto fail_unlock; 1496 inode = file->f_dentry->d_inode; 1497 if (inode->i_nlink > 1) 1498 goto close_fail; /* multiple links - don't dump */ 1499 if (d_unhashed(file->f_dentry)) 1500 goto close_fail; 1501 1502 if (!S_ISREG(inode->i_mode)) 1503 goto close_fail; 1504 if (!file->f_op) 1505 goto close_fail; 1506 if (!file->f_op->write) 1507 goto close_fail; 1508 if (do_truncate(file->f_dentry, 0, 0, file) != 0) 1509 goto close_fail; 1510 1511 retval = binfmt->core_dump(signr, regs, file); 1512 1513 if (retval) 1514 current->signal->group_exit_code |= 0x80; 1515 close_fail: 1516 filp_close(file, NULL); 1517 fail_unlock: 1518 current->fsuid = fsuid; 1519 complete_all(&mm->core_done); 1520 fail: 1521 return retval; 1522 } 1523