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