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/slab.h> 26 #include <linux/file.h> 27 #include <linux/fdtable.h> 28 #include <linux/mm.h> 29 #include <linux/stat.h> 30 #include <linux/fcntl.h> 31 #include <linux/smp_lock.h> 32 #include <linux/swap.h> 33 #include <linux/string.h> 34 #include <linux/init.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/utsname.h> 41 #include <linux/pid_namespace.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/tsacct_kern.h> 50 #include <linux/cn_proc.h> 51 #include <linux/audit.h> 52 53 #include <asm/uaccess.h> 54 #include <asm/mmu_context.h> 55 #include <asm/tlb.h> 56 57 #ifdef CONFIG_KMOD 58 #include <linux/kmod.h> 59 #endif 60 61 #ifdef __alpha__ 62 /* for /sbin/loader handling in search_binary_handler() */ 63 #include <linux/a.out.h> 64 #endif 65 66 int core_uses_pid; 67 char core_pattern[CORENAME_MAX_SIZE] = "core"; 68 int suid_dumpable = 0; 69 70 /* The maximal length of core_pattern is also specified in sysctl.c */ 71 72 static LIST_HEAD(formats); 73 static DEFINE_RWLOCK(binfmt_lock); 74 75 int register_binfmt(struct linux_binfmt * fmt) 76 { 77 if (!fmt) 78 return -EINVAL; 79 write_lock(&binfmt_lock); 80 list_add(&fmt->lh, &formats); 81 write_unlock(&binfmt_lock); 82 return 0; 83 } 84 85 EXPORT_SYMBOL(register_binfmt); 86 87 void unregister_binfmt(struct linux_binfmt * fmt) 88 { 89 write_lock(&binfmt_lock); 90 list_del(&fmt->lh); 91 write_unlock(&binfmt_lock); 92 } 93 94 EXPORT_SYMBOL(unregister_binfmt); 95 96 static inline void put_binfmt(struct linux_binfmt * fmt) 97 { 98 module_put(fmt->module); 99 } 100 101 /* 102 * Note that a shared library must be both readable and executable due to 103 * security reasons. 104 * 105 * Also note that we take the address to load from from the file itself. 106 */ 107 asmlinkage long sys_uselib(const char __user * library) 108 { 109 struct file * file; 110 struct nameidata nd; 111 int error; 112 113 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC); 114 if (error) 115 goto out; 116 117 error = -EINVAL; 118 if (!S_ISREG(nd.path.dentry->d_inode->i_mode)) 119 goto exit; 120 121 error = vfs_permission(&nd, MAY_READ | MAY_EXEC); 122 if (error) 123 goto exit; 124 125 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE); 126 error = PTR_ERR(file); 127 if (IS_ERR(file)) 128 goto out; 129 130 error = -ENOEXEC; 131 if(file->f_op) { 132 struct linux_binfmt * fmt; 133 134 read_lock(&binfmt_lock); 135 list_for_each_entry(fmt, &formats, lh) { 136 if (!fmt->load_shlib) 137 continue; 138 if (!try_module_get(fmt->module)) 139 continue; 140 read_unlock(&binfmt_lock); 141 error = fmt->load_shlib(file); 142 read_lock(&binfmt_lock); 143 put_binfmt(fmt); 144 if (error != -ENOEXEC) 145 break; 146 } 147 read_unlock(&binfmt_lock); 148 } 149 fput(file); 150 out: 151 return error; 152 exit: 153 release_open_intent(&nd); 154 path_put(&nd.path); 155 goto out; 156 } 157 158 #ifdef CONFIG_MMU 159 160 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 161 int write) 162 { 163 struct page *page; 164 int ret; 165 166 #ifdef CONFIG_STACK_GROWSUP 167 if (write) { 168 ret = expand_stack_downwards(bprm->vma, pos); 169 if (ret < 0) 170 return NULL; 171 } 172 #endif 173 ret = get_user_pages(current, bprm->mm, pos, 174 1, write, 1, &page, NULL); 175 if (ret <= 0) 176 return NULL; 177 178 if (write) { 179 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; 180 struct rlimit *rlim; 181 182 /* 183 * We've historically supported up to 32 pages (ARG_MAX) 184 * of argument strings even with small stacks 185 */ 186 if (size <= ARG_MAX) 187 return page; 188 189 /* 190 * Limit to 1/4-th the stack size for the argv+env strings. 191 * This ensures that: 192 * - the remaining binfmt code will not run out of stack space, 193 * - the program will have a reasonable amount of stack left 194 * to work from. 195 */ 196 rlim = current->signal->rlim; 197 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) { 198 put_page(page); 199 return NULL; 200 } 201 } 202 203 return page; 204 } 205 206 static void put_arg_page(struct page *page) 207 { 208 put_page(page); 209 } 210 211 static void free_arg_page(struct linux_binprm *bprm, int i) 212 { 213 } 214 215 static void free_arg_pages(struct linux_binprm *bprm) 216 { 217 } 218 219 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 220 struct page *page) 221 { 222 flush_cache_page(bprm->vma, pos, page_to_pfn(page)); 223 } 224 225 static int __bprm_mm_init(struct linux_binprm *bprm) 226 { 227 int err = -ENOMEM; 228 struct vm_area_struct *vma = NULL; 229 struct mm_struct *mm = bprm->mm; 230 231 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 232 if (!vma) 233 goto err; 234 235 down_write(&mm->mmap_sem); 236 vma->vm_mm = mm; 237 238 /* 239 * Place the stack at the largest stack address the architecture 240 * supports. Later, we'll move this to an appropriate place. We don't 241 * use STACK_TOP because that can depend on attributes which aren't 242 * configured yet. 243 */ 244 vma->vm_end = STACK_TOP_MAX; 245 vma->vm_start = vma->vm_end - PAGE_SIZE; 246 247 vma->vm_flags = VM_STACK_FLAGS; 248 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 249 err = insert_vm_struct(mm, vma); 250 if (err) { 251 up_write(&mm->mmap_sem); 252 goto err; 253 } 254 255 mm->stack_vm = mm->total_vm = 1; 256 up_write(&mm->mmap_sem); 257 258 bprm->p = vma->vm_end - sizeof(void *); 259 260 return 0; 261 262 err: 263 if (vma) { 264 bprm->vma = NULL; 265 kmem_cache_free(vm_area_cachep, vma); 266 } 267 268 return err; 269 } 270 271 static bool valid_arg_len(struct linux_binprm *bprm, long len) 272 { 273 return len <= MAX_ARG_STRLEN; 274 } 275 276 #else 277 278 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 279 int write) 280 { 281 struct page *page; 282 283 page = bprm->page[pos / PAGE_SIZE]; 284 if (!page && write) { 285 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 286 if (!page) 287 return NULL; 288 bprm->page[pos / PAGE_SIZE] = page; 289 } 290 291 return page; 292 } 293 294 static void put_arg_page(struct page *page) 295 { 296 } 297 298 static void free_arg_page(struct linux_binprm *bprm, int i) 299 { 300 if (bprm->page[i]) { 301 __free_page(bprm->page[i]); 302 bprm->page[i] = NULL; 303 } 304 } 305 306 static void free_arg_pages(struct linux_binprm *bprm) 307 { 308 int i; 309 310 for (i = 0; i < MAX_ARG_PAGES; i++) 311 free_arg_page(bprm, i); 312 } 313 314 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 315 struct page *page) 316 { 317 } 318 319 static int __bprm_mm_init(struct linux_binprm *bprm) 320 { 321 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 322 return 0; 323 } 324 325 static bool valid_arg_len(struct linux_binprm *bprm, long len) 326 { 327 return len <= bprm->p; 328 } 329 330 #endif /* CONFIG_MMU */ 331 332 /* 333 * Create a new mm_struct and populate it with a temporary stack 334 * vm_area_struct. We don't have enough context at this point to set the stack 335 * flags, permissions, and offset, so we use temporary values. We'll update 336 * them later in setup_arg_pages(). 337 */ 338 int bprm_mm_init(struct linux_binprm *bprm) 339 { 340 int err; 341 struct mm_struct *mm = NULL; 342 343 bprm->mm = mm = mm_alloc(); 344 err = -ENOMEM; 345 if (!mm) 346 goto err; 347 348 err = init_new_context(current, mm); 349 if (err) 350 goto err; 351 352 err = __bprm_mm_init(bprm); 353 if (err) 354 goto err; 355 356 return 0; 357 358 err: 359 if (mm) { 360 bprm->mm = NULL; 361 mmdrop(mm); 362 } 363 364 return err; 365 } 366 367 /* 368 * count() counts the number of strings in array ARGV. 369 */ 370 static int count(char __user * __user * argv, int max) 371 { 372 int i = 0; 373 374 if (argv != NULL) { 375 for (;;) { 376 char __user * p; 377 378 if (get_user(p, argv)) 379 return -EFAULT; 380 if (!p) 381 break; 382 argv++; 383 if(++i > max) 384 return -E2BIG; 385 cond_resched(); 386 } 387 } 388 return i; 389 } 390 391 /* 392 * 'copy_strings()' copies argument/environment strings from the old 393 * processes's memory to the new process's stack. The call to get_user_pages() 394 * ensures the destination page is created and not swapped out. 395 */ 396 static int copy_strings(int argc, char __user * __user * argv, 397 struct linux_binprm *bprm) 398 { 399 struct page *kmapped_page = NULL; 400 char *kaddr = NULL; 401 unsigned long kpos = 0; 402 int ret; 403 404 while (argc-- > 0) { 405 char __user *str; 406 int len; 407 unsigned long pos; 408 409 if (get_user(str, argv+argc) || 410 !(len = strnlen_user(str, MAX_ARG_STRLEN))) { 411 ret = -EFAULT; 412 goto out; 413 } 414 415 if (!valid_arg_len(bprm, len)) { 416 ret = -E2BIG; 417 goto out; 418 } 419 420 /* We're going to work our way backwords. */ 421 pos = bprm->p; 422 str += len; 423 bprm->p -= len; 424 425 while (len > 0) { 426 int offset, bytes_to_copy; 427 428 offset = pos % PAGE_SIZE; 429 if (offset == 0) 430 offset = PAGE_SIZE; 431 432 bytes_to_copy = offset; 433 if (bytes_to_copy > len) 434 bytes_to_copy = len; 435 436 offset -= bytes_to_copy; 437 pos -= bytes_to_copy; 438 str -= bytes_to_copy; 439 len -= bytes_to_copy; 440 441 if (!kmapped_page || kpos != (pos & PAGE_MASK)) { 442 struct page *page; 443 444 page = get_arg_page(bprm, pos, 1); 445 if (!page) { 446 ret = -E2BIG; 447 goto out; 448 } 449 450 if (kmapped_page) { 451 flush_kernel_dcache_page(kmapped_page); 452 kunmap(kmapped_page); 453 put_arg_page(kmapped_page); 454 } 455 kmapped_page = page; 456 kaddr = kmap(kmapped_page); 457 kpos = pos & PAGE_MASK; 458 flush_arg_page(bprm, kpos, kmapped_page); 459 } 460 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { 461 ret = -EFAULT; 462 goto out; 463 } 464 } 465 } 466 ret = 0; 467 out: 468 if (kmapped_page) { 469 flush_kernel_dcache_page(kmapped_page); 470 kunmap(kmapped_page); 471 put_arg_page(kmapped_page); 472 } 473 return ret; 474 } 475 476 /* 477 * Like copy_strings, but get argv and its values from kernel memory. 478 */ 479 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm) 480 { 481 int r; 482 mm_segment_t oldfs = get_fs(); 483 set_fs(KERNEL_DS); 484 r = copy_strings(argc, (char __user * __user *)argv, bprm); 485 set_fs(oldfs); 486 return r; 487 } 488 EXPORT_SYMBOL(copy_strings_kernel); 489 490 #ifdef CONFIG_MMU 491 492 /* 493 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once 494 * the binfmt code determines where the new stack should reside, we shift it to 495 * its final location. The process proceeds as follows: 496 * 497 * 1) Use shift to calculate the new vma endpoints. 498 * 2) Extend vma to cover both the old and new ranges. This ensures the 499 * arguments passed to subsequent functions are consistent. 500 * 3) Move vma's page tables to the new range. 501 * 4) Free up any cleared pgd range. 502 * 5) Shrink the vma to cover only the new range. 503 */ 504 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) 505 { 506 struct mm_struct *mm = vma->vm_mm; 507 unsigned long old_start = vma->vm_start; 508 unsigned long old_end = vma->vm_end; 509 unsigned long length = old_end - old_start; 510 unsigned long new_start = old_start - shift; 511 unsigned long new_end = old_end - shift; 512 struct mmu_gather *tlb; 513 514 BUG_ON(new_start > new_end); 515 516 /* 517 * ensure there are no vmas between where we want to go 518 * and where we are 519 */ 520 if (vma != find_vma(mm, new_start)) 521 return -EFAULT; 522 523 /* 524 * cover the whole range: [new_start, old_end) 525 */ 526 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL); 527 528 /* 529 * move the page tables downwards, on failure we rely on 530 * process cleanup to remove whatever mess we made. 531 */ 532 if (length != move_page_tables(vma, old_start, 533 vma, new_start, length)) 534 return -ENOMEM; 535 536 lru_add_drain(); 537 tlb = tlb_gather_mmu(mm, 0); 538 if (new_end > old_start) { 539 /* 540 * when the old and new regions overlap clear from new_end. 541 */ 542 free_pgd_range(tlb, new_end, old_end, new_end, 543 vma->vm_next ? vma->vm_next->vm_start : 0); 544 } else { 545 /* 546 * otherwise, clean from old_start; this is done to not touch 547 * the address space in [new_end, old_start) some architectures 548 * have constraints on va-space that make this illegal (IA64) - 549 * for the others its just a little faster. 550 */ 551 free_pgd_range(tlb, old_start, old_end, new_end, 552 vma->vm_next ? vma->vm_next->vm_start : 0); 553 } 554 tlb_finish_mmu(tlb, new_end, old_end); 555 556 /* 557 * shrink the vma to just the new range. 558 */ 559 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); 560 561 return 0; 562 } 563 564 #define EXTRA_STACK_VM_PAGES 20 /* random */ 565 566 /* 567 * Finalizes the stack vm_area_struct. The flags and permissions are updated, 568 * the stack is optionally relocated, and some extra space is added. 569 */ 570 int setup_arg_pages(struct linux_binprm *bprm, 571 unsigned long stack_top, 572 int executable_stack) 573 { 574 unsigned long ret; 575 unsigned long stack_shift; 576 struct mm_struct *mm = current->mm; 577 struct vm_area_struct *vma = bprm->vma; 578 struct vm_area_struct *prev = NULL; 579 unsigned long vm_flags; 580 unsigned long stack_base; 581 582 #ifdef CONFIG_STACK_GROWSUP 583 /* Limit stack size to 1GB */ 584 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max; 585 if (stack_base > (1 << 30)) 586 stack_base = 1 << 30; 587 588 /* Make sure we didn't let the argument array grow too large. */ 589 if (vma->vm_end - vma->vm_start > stack_base) 590 return -ENOMEM; 591 592 stack_base = PAGE_ALIGN(stack_top - stack_base); 593 594 stack_shift = vma->vm_start - stack_base; 595 mm->arg_start = bprm->p - stack_shift; 596 bprm->p = vma->vm_end - stack_shift; 597 #else 598 stack_top = arch_align_stack(stack_top); 599 stack_top = PAGE_ALIGN(stack_top); 600 stack_shift = vma->vm_end - stack_top; 601 602 bprm->p -= stack_shift; 603 mm->arg_start = bprm->p; 604 #endif 605 606 if (bprm->loader) 607 bprm->loader -= stack_shift; 608 bprm->exec -= stack_shift; 609 610 down_write(&mm->mmap_sem); 611 vm_flags = VM_STACK_FLAGS; 612 613 /* 614 * Adjust stack execute permissions; explicitly enable for 615 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone 616 * (arch default) otherwise. 617 */ 618 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 619 vm_flags |= VM_EXEC; 620 else if (executable_stack == EXSTACK_DISABLE_X) 621 vm_flags &= ~VM_EXEC; 622 vm_flags |= mm->def_flags; 623 624 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, 625 vm_flags); 626 if (ret) 627 goto out_unlock; 628 BUG_ON(prev != vma); 629 630 /* Move stack pages down in memory. */ 631 if (stack_shift) { 632 ret = shift_arg_pages(vma, stack_shift); 633 if (ret) { 634 up_write(&mm->mmap_sem); 635 return ret; 636 } 637 } 638 639 #ifdef CONFIG_STACK_GROWSUP 640 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE; 641 #else 642 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE; 643 #endif 644 ret = expand_stack(vma, stack_base); 645 if (ret) 646 ret = -EFAULT; 647 648 out_unlock: 649 up_write(&mm->mmap_sem); 650 return 0; 651 } 652 EXPORT_SYMBOL(setup_arg_pages); 653 654 #endif /* CONFIG_MMU */ 655 656 struct file *open_exec(const char *name) 657 { 658 struct nameidata nd; 659 int err; 660 struct file *file; 661 662 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC); 663 file = ERR_PTR(err); 664 665 if (!err) { 666 struct inode *inode = nd.path.dentry->d_inode; 667 file = ERR_PTR(-EACCES); 668 if (S_ISREG(inode->i_mode)) { 669 int err = vfs_permission(&nd, MAY_EXEC); 670 file = ERR_PTR(err); 671 if (!err) { 672 file = nameidata_to_filp(&nd, 673 O_RDONLY|O_LARGEFILE); 674 if (!IS_ERR(file)) { 675 err = deny_write_access(file); 676 if (err) { 677 fput(file); 678 file = ERR_PTR(err); 679 } 680 } 681 out: 682 return file; 683 } 684 } 685 release_open_intent(&nd); 686 path_put(&nd.path); 687 } 688 goto out; 689 } 690 691 EXPORT_SYMBOL(open_exec); 692 693 int kernel_read(struct file *file, unsigned long offset, 694 char *addr, unsigned long count) 695 { 696 mm_segment_t old_fs; 697 loff_t pos = offset; 698 int result; 699 700 old_fs = get_fs(); 701 set_fs(get_ds()); 702 /* The cast to a user pointer is valid due to the set_fs() */ 703 result = vfs_read(file, (void __user *)addr, count, &pos); 704 set_fs(old_fs); 705 return result; 706 } 707 708 EXPORT_SYMBOL(kernel_read); 709 710 static int exec_mmap(struct mm_struct *mm) 711 { 712 struct task_struct *tsk; 713 struct mm_struct * old_mm, *active_mm; 714 715 /* Notify parent that we're no longer interested in the old VM */ 716 tsk = current; 717 old_mm = current->mm; 718 mm_release(tsk, old_mm); 719 720 if (old_mm) { 721 /* 722 * Make sure that if there is a core dump in progress 723 * for the old mm, we get out and die instead of going 724 * through with the exec. We must hold mmap_sem around 725 * checking core_state and changing tsk->mm. 726 */ 727 down_read(&old_mm->mmap_sem); 728 if (unlikely(old_mm->core_state)) { 729 up_read(&old_mm->mmap_sem); 730 return -EINTR; 731 } 732 } 733 task_lock(tsk); 734 active_mm = tsk->active_mm; 735 tsk->mm = mm; 736 tsk->active_mm = mm; 737 activate_mm(active_mm, mm); 738 task_unlock(tsk); 739 mm_update_next_owner(old_mm); 740 arch_pick_mmap_layout(mm); 741 if (old_mm) { 742 up_read(&old_mm->mmap_sem); 743 BUG_ON(active_mm != old_mm); 744 mmput(old_mm); 745 return 0; 746 } 747 mmdrop(active_mm); 748 return 0; 749 } 750 751 /* 752 * This function makes sure the current process has its own signal table, 753 * so that flush_signal_handlers can later reset the handlers without 754 * disturbing other processes. (Other processes might share the signal 755 * table via the CLONE_SIGHAND option to clone().) 756 */ 757 static int de_thread(struct task_struct *tsk) 758 { 759 struct signal_struct *sig = tsk->signal; 760 struct sighand_struct *oldsighand = tsk->sighand; 761 spinlock_t *lock = &oldsighand->siglock; 762 struct task_struct *leader = NULL; 763 int count; 764 765 if (thread_group_empty(tsk)) 766 goto no_thread_group; 767 768 /* 769 * Kill all other threads in the thread group. 770 */ 771 spin_lock_irq(lock); 772 if (signal_group_exit(sig)) { 773 /* 774 * Another group action in progress, just 775 * return so that the signal is processed. 776 */ 777 spin_unlock_irq(lock); 778 return -EAGAIN; 779 } 780 sig->group_exit_task = tsk; 781 zap_other_threads(tsk); 782 783 /* Account for the thread group leader hanging around: */ 784 count = thread_group_leader(tsk) ? 1 : 2; 785 sig->notify_count = count; 786 while (atomic_read(&sig->count) > count) { 787 __set_current_state(TASK_UNINTERRUPTIBLE); 788 spin_unlock_irq(lock); 789 schedule(); 790 spin_lock_irq(lock); 791 } 792 spin_unlock_irq(lock); 793 794 /* 795 * At this point all other threads have exited, all we have to 796 * do is to wait for the thread group leader to become inactive, 797 * and to assume its PID: 798 */ 799 if (!thread_group_leader(tsk)) { 800 leader = tsk->group_leader; 801 802 sig->notify_count = -1; /* for exit_notify() */ 803 for (;;) { 804 write_lock_irq(&tasklist_lock); 805 if (likely(leader->exit_state)) 806 break; 807 __set_current_state(TASK_UNINTERRUPTIBLE); 808 write_unlock_irq(&tasklist_lock); 809 schedule(); 810 } 811 812 if (unlikely(task_child_reaper(tsk) == leader)) 813 task_active_pid_ns(tsk)->child_reaper = tsk; 814 /* 815 * The only record we have of the real-time age of a 816 * process, regardless of execs it's done, is start_time. 817 * All the past CPU time is accumulated in signal_struct 818 * from sister threads now dead. But in this non-leader 819 * exec, nothing survives from the original leader thread, 820 * whose birth marks the true age of this process now. 821 * When we take on its identity by switching to its PID, we 822 * also take its birthdate (always earlier than our own). 823 */ 824 tsk->start_time = leader->start_time; 825 826 BUG_ON(!same_thread_group(leader, tsk)); 827 BUG_ON(has_group_leader_pid(tsk)); 828 /* 829 * An exec() starts a new thread group with the 830 * TGID of the previous thread group. Rehash the 831 * two threads with a switched PID, and release 832 * the former thread group leader: 833 */ 834 835 /* Become a process group leader with the old leader's pid. 836 * The old leader becomes a thread of the this thread group. 837 * Note: The old leader also uses this pid until release_task 838 * is called. Odd but simple and correct. 839 */ 840 detach_pid(tsk, PIDTYPE_PID); 841 tsk->pid = leader->pid; 842 attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); 843 transfer_pid(leader, tsk, PIDTYPE_PGID); 844 transfer_pid(leader, tsk, PIDTYPE_SID); 845 list_replace_rcu(&leader->tasks, &tsk->tasks); 846 847 tsk->group_leader = tsk; 848 leader->group_leader = tsk; 849 850 tsk->exit_signal = SIGCHLD; 851 852 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 853 leader->exit_state = EXIT_DEAD; 854 855 write_unlock_irq(&tasklist_lock); 856 } 857 858 sig->group_exit_task = NULL; 859 sig->notify_count = 0; 860 861 no_thread_group: 862 exit_itimers(sig); 863 flush_itimer_signals(); 864 if (leader) 865 release_task(leader); 866 867 if (atomic_read(&oldsighand->count) != 1) { 868 struct sighand_struct *newsighand; 869 /* 870 * This ->sighand is shared with the CLONE_SIGHAND 871 * but not CLONE_THREAD task, switch to the new one. 872 */ 873 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 874 if (!newsighand) 875 return -ENOMEM; 876 877 atomic_set(&newsighand->count, 1); 878 memcpy(newsighand->action, oldsighand->action, 879 sizeof(newsighand->action)); 880 881 write_lock_irq(&tasklist_lock); 882 spin_lock(&oldsighand->siglock); 883 rcu_assign_pointer(tsk->sighand, newsighand); 884 spin_unlock(&oldsighand->siglock); 885 write_unlock_irq(&tasklist_lock); 886 887 __cleanup_sighand(oldsighand); 888 } 889 890 BUG_ON(!thread_group_leader(tsk)); 891 return 0; 892 } 893 894 /* 895 * These functions flushes out all traces of the currently running executable 896 * so that a new one can be started 897 */ 898 static void flush_old_files(struct files_struct * files) 899 { 900 long j = -1; 901 struct fdtable *fdt; 902 903 spin_lock(&files->file_lock); 904 for (;;) { 905 unsigned long set, i; 906 907 j++; 908 i = j * __NFDBITS; 909 fdt = files_fdtable(files); 910 if (i >= fdt->max_fds) 911 break; 912 set = fdt->close_on_exec->fds_bits[j]; 913 if (!set) 914 continue; 915 fdt->close_on_exec->fds_bits[j] = 0; 916 spin_unlock(&files->file_lock); 917 for ( ; set ; i++,set >>= 1) { 918 if (set & 1) { 919 sys_close(i); 920 } 921 } 922 spin_lock(&files->file_lock); 923 924 } 925 spin_unlock(&files->file_lock); 926 } 927 928 char *get_task_comm(char *buf, struct task_struct *tsk) 929 { 930 /* buf must be at least sizeof(tsk->comm) in size */ 931 task_lock(tsk); 932 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 933 task_unlock(tsk); 934 return buf; 935 } 936 937 void set_task_comm(struct task_struct *tsk, char *buf) 938 { 939 task_lock(tsk); 940 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 941 task_unlock(tsk); 942 } 943 944 int flush_old_exec(struct linux_binprm * bprm) 945 { 946 char * name; 947 int i, ch, retval; 948 char tcomm[sizeof(current->comm)]; 949 950 /* 951 * Make sure we have a private signal table and that 952 * we are unassociated from the previous thread group. 953 */ 954 retval = de_thread(current); 955 if (retval) 956 goto out; 957 958 set_mm_exe_file(bprm->mm, bprm->file); 959 960 /* 961 * Release all of the old mmap stuff 962 */ 963 retval = exec_mmap(bprm->mm); 964 if (retval) 965 goto out; 966 967 bprm->mm = NULL; /* We're using it now */ 968 969 /* This is the point of no return */ 970 current->sas_ss_sp = current->sas_ss_size = 0; 971 972 if (current->euid == current->uid && current->egid == current->gid) 973 set_dumpable(current->mm, 1); 974 else 975 set_dumpable(current->mm, suid_dumpable); 976 977 name = bprm->filename; 978 979 /* Copies the binary name from after last slash */ 980 for (i=0; (ch = *(name++)) != '\0';) { 981 if (ch == '/') 982 i = 0; /* overwrite what we wrote */ 983 else 984 if (i < (sizeof(tcomm) - 1)) 985 tcomm[i++] = ch; 986 } 987 tcomm[i] = '\0'; 988 set_task_comm(current, tcomm); 989 990 current->flags &= ~PF_RANDOMIZE; 991 flush_thread(); 992 993 /* Set the new mm task size. We have to do that late because it may 994 * depend on TIF_32BIT which is only updated in flush_thread() on 995 * some architectures like powerpc 996 */ 997 current->mm->task_size = TASK_SIZE; 998 999 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) { 1000 suid_keys(current); 1001 set_dumpable(current->mm, suid_dumpable); 1002 current->pdeath_signal = 0; 1003 } else if (file_permission(bprm->file, MAY_READ) || 1004 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { 1005 suid_keys(current); 1006 set_dumpable(current->mm, suid_dumpable); 1007 } 1008 1009 /* An exec changes our domain. We are no longer part of the thread 1010 group */ 1011 1012 current->self_exec_id++; 1013 1014 flush_signal_handlers(current, 0); 1015 flush_old_files(current->files); 1016 1017 return 0; 1018 1019 out: 1020 return retval; 1021 } 1022 1023 EXPORT_SYMBOL(flush_old_exec); 1024 1025 /* 1026 * Fill the binprm structure from the inode. 1027 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1028 */ 1029 int prepare_binprm(struct linux_binprm *bprm) 1030 { 1031 int mode; 1032 struct inode * inode = bprm->file->f_path.dentry->d_inode; 1033 int retval; 1034 1035 mode = inode->i_mode; 1036 if (bprm->file->f_op == NULL) 1037 return -EACCES; 1038 1039 bprm->e_uid = current->euid; 1040 bprm->e_gid = current->egid; 1041 1042 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { 1043 /* Set-uid? */ 1044 if (mode & S_ISUID) { 1045 current->personality &= ~PER_CLEAR_ON_SETID; 1046 bprm->e_uid = inode->i_uid; 1047 } 1048 1049 /* Set-gid? */ 1050 /* 1051 * If setgid is set but no group execute bit then this 1052 * is a candidate for mandatory locking, not a setgid 1053 * executable. 1054 */ 1055 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1056 current->personality &= ~PER_CLEAR_ON_SETID; 1057 bprm->e_gid = inode->i_gid; 1058 } 1059 } 1060 1061 /* fill in binprm security blob */ 1062 retval = security_bprm_set(bprm); 1063 if (retval) 1064 return retval; 1065 1066 memset(bprm->buf,0,BINPRM_BUF_SIZE); 1067 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE); 1068 } 1069 1070 EXPORT_SYMBOL(prepare_binprm); 1071 1072 static int unsafe_exec(struct task_struct *p) 1073 { 1074 int unsafe = 0; 1075 if (p->ptrace & PT_PTRACED) { 1076 if (p->ptrace & PT_PTRACE_CAP) 1077 unsafe |= LSM_UNSAFE_PTRACE_CAP; 1078 else 1079 unsafe |= LSM_UNSAFE_PTRACE; 1080 } 1081 if (atomic_read(&p->fs->count) > 1 || 1082 atomic_read(&p->files->count) > 1 || 1083 atomic_read(&p->sighand->count) > 1) 1084 unsafe |= LSM_UNSAFE_SHARE; 1085 1086 return unsafe; 1087 } 1088 1089 void compute_creds(struct linux_binprm *bprm) 1090 { 1091 int unsafe; 1092 1093 if (bprm->e_uid != current->uid) { 1094 suid_keys(current); 1095 current->pdeath_signal = 0; 1096 } 1097 exec_keys(current); 1098 1099 task_lock(current); 1100 unsafe = unsafe_exec(current); 1101 security_bprm_apply_creds(bprm, unsafe); 1102 task_unlock(current); 1103 security_bprm_post_apply_creds(bprm); 1104 } 1105 EXPORT_SYMBOL(compute_creds); 1106 1107 /* 1108 * Arguments are '\0' separated strings found at the location bprm->p 1109 * points to; chop off the first by relocating brpm->p to right after 1110 * the first '\0' encountered. 1111 */ 1112 int remove_arg_zero(struct linux_binprm *bprm) 1113 { 1114 int ret = 0; 1115 unsigned long offset; 1116 char *kaddr; 1117 struct page *page; 1118 1119 if (!bprm->argc) 1120 return 0; 1121 1122 do { 1123 offset = bprm->p & ~PAGE_MASK; 1124 page = get_arg_page(bprm, bprm->p, 0); 1125 if (!page) { 1126 ret = -EFAULT; 1127 goto out; 1128 } 1129 kaddr = kmap_atomic(page, KM_USER0); 1130 1131 for (; offset < PAGE_SIZE && kaddr[offset]; 1132 offset++, bprm->p++) 1133 ; 1134 1135 kunmap_atomic(kaddr, KM_USER0); 1136 put_arg_page(page); 1137 1138 if (offset == PAGE_SIZE) 1139 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1140 } while (offset == PAGE_SIZE); 1141 1142 bprm->p++; 1143 bprm->argc--; 1144 ret = 0; 1145 1146 out: 1147 return ret; 1148 } 1149 EXPORT_SYMBOL(remove_arg_zero); 1150 1151 /* 1152 * cycle the list of binary formats handler, until one recognizes the image 1153 */ 1154 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) 1155 { 1156 int try,retval; 1157 struct linux_binfmt *fmt; 1158 #ifdef __alpha__ 1159 /* handle /sbin/loader.. */ 1160 { 1161 struct exec * eh = (struct exec *) bprm->buf; 1162 1163 if (!bprm->loader && eh->fh.f_magic == 0x183 && 1164 (eh->fh.f_flags & 0x3000) == 0x3000) 1165 { 1166 struct file * file; 1167 unsigned long loader; 1168 1169 allow_write_access(bprm->file); 1170 fput(bprm->file); 1171 bprm->file = NULL; 1172 1173 loader = bprm->vma->vm_end - sizeof(void *); 1174 1175 file = open_exec("/sbin/loader"); 1176 retval = PTR_ERR(file); 1177 if (IS_ERR(file)) 1178 return retval; 1179 1180 /* Remember if the application is TASO. */ 1181 bprm->sh_bang = eh->ah.entry < 0x100000000UL; 1182 1183 bprm->file = file; 1184 bprm->loader = loader; 1185 retval = prepare_binprm(bprm); 1186 if (retval<0) 1187 return retval; 1188 /* should call search_binary_handler recursively here, 1189 but it does not matter */ 1190 } 1191 } 1192 #endif 1193 retval = security_bprm_check(bprm); 1194 if (retval) 1195 return retval; 1196 1197 /* kernel module loader fixup */ 1198 /* so we don't try to load run modprobe in kernel space. */ 1199 set_fs(USER_DS); 1200 1201 retval = audit_bprm(bprm); 1202 if (retval) 1203 return retval; 1204 1205 retval = -ENOENT; 1206 for (try=0; try<2; try++) { 1207 read_lock(&binfmt_lock); 1208 list_for_each_entry(fmt, &formats, lh) { 1209 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; 1210 if (!fn) 1211 continue; 1212 if (!try_module_get(fmt->module)) 1213 continue; 1214 read_unlock(&binfmt_lock); 1215 retval = fn(bprm, regs); 1216 if (retval >= 0) { 1217 put_binfmt(fmt); 1218 allow_write_access(bprm->file); 1219 if (bprm->file) 1220 fput(bprm->file); 1221 bprm->file = NULL; 1222 current->did_exec = 1; 1223 proc_exec_connector(current); 1224 return retval; 1225 } 1226 read_lock(&binfmt_lock); 1227 put_binfmt(fmt); 1228 if (retval != -ENOEXEC || bprm->mm == NULL) 1229 break; 1230 if (!bprm->file) { 1231 read_unlock(&binfmt_lock); 1232 return retval; 1233 } 1234 } 1235 read_unlock(&binfmt_lock); 1236 if (retval != -ENOEXEC || bprm->mm == NULL) { 1237 break; 1238 #ifdef CONFIG_KMOD 1239 }else{ 1240 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1241 if (printable(bprm->buf[0]) && 1242 printable(bprm->buf[1]) && 1243 printable(bprm->buf[2]) && 1244 printable(bprm->buf[3])) 1245 break; /* -ENOEXEC */ 1246 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1247 #endif 1248 } 1249 } 1250 return retval; 1251 } 1252 1253 EXPORT_SYMBOL(search_binary_handler); 1254 1255 void free_bprm(struct linux_binprm *bprm) 1256 { 1257 free_arg_pages(bprm); 1258 kfree(bprm); 1259 } 1260 1261 /* 1262 * sys_execve() executes a new program. 1263 */ 1264 int do_execve(char * filename, 1265 char __user *__user *argv, 1266 char __user *__user *envp, 1267 struct pt_regs * regs) 1268 { 1269 struct linux_binprm *bprm; 1270 struct file *file; 1271 struct files_struct *displaced; 1272 int retval; 1273 1274 retval = unshare_files(&displaced); 1275 if (retval) 1276 goto out_ret; 1277 1278 retval = -ENOMEM; 1279 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1280 if (!bprm) 1281 goto out_files; 1282 1283 file = open_exec(filename); 1284 retval = PTR_ERR(file); 1285 if (IS_ERR(file)) 1286 goto out_kfree; 1287 1288 sched_exec(); 1289 1290 bprm->file = file; 1291 bprm->filename = filename; 1292 bprm->interp = filename; 1293 1294 retval = bprm_mm_init(bprm); 1295 if (retval) 1296 goto out_file; 1297 1298 bprm->argc = count(argv, MAX_ARG_STRINGS); 1299 if ((retval = bprm->argc) < 0) 1300 goto out_mm; 1301 1302 bprm->envc = count(envp, MAX_ARG_STRINGS); 1303 if ((retval = bprm->envc) < 0) 1304 goto out_mm; 1305 1306 retval = security_bprm_alloc(bprm); 1307 if (retval) 1308 goto out; 1309 1310 retval = prepare_binprm(bprm); 1311 if (retval < 0) 1312 goto out; 1313 1314 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1315 if (retval < 0) 1316 goto out; 1317 1318 bprm->exec = bprm->p; 1319 retval = copy_strings(bprm->envc, envp, bprm); 1320 if (retval < 0) 1321 goto out; 1322 1323 retval = copy_strings(bprm->argc, argv, bprm); 1324 if (retval < 0) 1325 goto out; 1326 1327 current->flags &= ~PF_KTHREAD; 1328 retval = search_binary_handler(bprm,regs); 1329 if (retval >= 0) { 1330 /* execve success */ 1331 security_bprm_free(bprm); 1332 acct_update_integrals(current); 1333 free_bprm(bprm); 1334 if (displaced) 1335 put_files_struct(displaced); 1336 return retval; 1337 } 1338 1339 out: 1340 if (bprm->security) 1341 security_bprm_free(bprm); 1342 1343 out_mm: 1344 if (bprm->mm) 1345 mmput (bprm->mm); 1346 1347 out_file: 1348 if (bprm->file) { 1349 allow_write_access(bprm->file); 1350 fput(bprm->file); 1351 } 1352 out_kfree: 1353 free_bprm(bprm); 1354 1355 out_files: 1356 if (displaced) 1357 reset_files_struct(displaced); 1358 out_ret: 1359 return retval; 1360 } 1361 1362 int set_binfmt(struct linux_binfmt *new) 1363 { 1364 struct linux_binfmt *old = current->binfmt; 1365 1366 if (new) { 1367 if (!try_module_get(new->module)) 1368 return -1; 1369 } 1370 current->binfmt = new; 1371 if (old) 1372 module_put(old->module); 1373 return 0; 1374 } 1375 1376 EXPORT_SYMBOL(set_binfmt); 1377 1378 /* format_corename will inspect the pattern parameter, and output a 1379 * name into corename, which must have space for at least 1380 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 1381 */ 1382 static int format_corename(char *corename, int nr_threads, long signr) 1383 { 1384 const char *pat_ptr = core_pattern; 1385 int ispipe = (*pat_ptr == '|'); 1386 char *out_ptr = corename; 1387 char *const out_end = corename + CORENAME_MAX_SIZE; 1388 int rc; 1389 int pid_in_pattern = 0; 1390 1391 /* Repeat as long as we have more pattern to process and more output 1392 space */ 1393 while (*pat_ptr) { 1394 if (*pat_ptr != '%') { 1395 if (out_ptr == out_end) 1396 goto out; 1397 *out_ptr++ = *pat_ptr++; 1398 } else { 1399 switch (*++pat_ptr) { 1400 case 0: 1401 goto out; 1402 /* Double percent, output one percent */ 1403 case '%': 1404 if (out_ptr == out_end) 1405 goto out; 1406 *out_ptr++ = '%'; 1407 break; 1408 /* pid */ 1409 case 'p': 1410 pid_in_pattern = 1; 1411 rc = snprintf(out_ptr, out_end - out_ptr, 1412 "%d", task_tgid_vnr(current)); 1413 if (rc > out_end - out_ptr) 1414 goto out; 1415 out_ptr += rc; 1416 break; 1417 /* uid */ 1418 case 'u': 1419 rc = snprintf(out_ptr, out_end - out_ptr, 1420 "%d", current->uid); 1421 if (rc > out_end - out_ptr) 1422 goto out; 1423 out_ptr += rc; 1424 break; 1425 /* gid */ 1426 case 'g': 1427 rc = snprintf(out_ptr, out_end - out_ptr, 1428 "%d", current->gid); 1429 if (rc > out_end - out_ptr) 1430 goto out; 1431 out_ptr += rc; 1432 break; 1433 /* signal that caused the coredump */ 1434 case 's': 1435 rc = snprintf(out_ptr, out_end - out_ptr, 1436 "%ld", signr); 1437 if (rc > out_end - out_ptr) 1438 goto out; 1439 out_ptr += rc; 1440 break; 1441 /* UNIX time of coredump */ 1442 case 't': { 1443 struct timeval tv; 1444 do_gettimeofday(&tv); 1445 rc = snprintf(out_ptr, out_end - out_ptr, 1446 "%lu", tv.tv_sec); 1447 if (rc > out_end - out_ptr) 1448 goto out; 1449 out_ptr += rc; 1450 break; 1451 } 1452 /* hostname */ 1453 case 'h': 1454 down_read(&uts_sem); 1455 rc = snprintf(out_ptr, out_end - out_ptr, 1456 "%s", utsname()->nodename); 1457 up_read(&uts_sem); 1458 if (rc > out_end - out_ptr) 1459 goto out; 1460 out_ptr += rc; 1461 break; 1462 /* executable */ 1463 case 'e': 1464 rc = snprintf(out_ptr, out_end - out_ptr, 1465 "%s", current->comm); 1466 if (rc > out_end - out_ptr) 1467 goto out; 1468 out_ptr += rc; 1469 break; 1470 /* core limit size */ 1471 case 'c': 1472 rc = snprintf(out_ptr, out_end - out_ptr, 1473 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur); 1474 if (rc > out_end - out_ptr) 1475 goto out; 1476 out_ptr += rc; 1477 break; 1478 default: 1479 break; 1480 } 1481 ++pat_ptr; 1482 } 1483 } 1484 /* Backward compatibility with core_uses_pid: 1485 * 1486 * If core_pattern does not include a %p (as is the default) 1487 * and core_uses_pid is set, then .%pid will be appended to 1488 * the filename. Do not do this for piped commands. */ 1489 if (!ispipe && !pid_in_pattern 1490 && (core_uses_pid || nr_threads)) { 1491 rc = snprintf(out_ptr, out_end - out_ptr, 1492 ".%d", task_tgid_vnr(current)); 1493 if (rc > out_end - out_ptr) 1494 goto out; 1495 out_ptr += rc; 1496 } 1497 out: 1498 *out_ptr = 0; 1499 return ispipe; 1500 } 1501 1502 static int zap_process(struct task_struct *start) 1503 { 1504 struct task_struct *t; 1505 int nr = 0; 1506 1507 start->signal->flags = SIGNAL_GROUP_EXIT; 1508 start->signal->group_stop_count = 0; 1509 1510 t = start; 1511 do { 1512 if (t != current && t->mm) { 1513 sigaddset(&t->pending.signal, SIGKILL); 1514 signal_wake_up(t, 1); 1515 nr++; 1516 } 1517 } while_each_thread(start, t); 1518 1519 return nr; 1520 } 1521 1522 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 1523 struct core_state *core_state, int exit_code) 1524 { 1525 struct task_struct *g, *p; 1526 unsigned long flags; 1527 int nr = -EAGAIN; 1528 1529 spin_lock_irq(&tsk->sighand->siglock); 1530 if (!signal_group_exit(tsk->signal)) { 1531 mm->core_state = core_state; 1532 tsk->signal->group_exit_code = exit_code; 1533 nr = zap_process(tsk); 1534 } 1535 spin_unlock_irq(&tsk->sighand->siglock); 1536 if (unlikely(nr < 0)) 1537 return nr; 1538 1539 if (atomic_read(&mm->mm_users) == nr + 1) 1540 goto done; 1541 /* 1542 * We should find and kill all tasks which use this mm, and we should 1543 * count them correctly into ->nr_threads. We don't take tasklist 1544 * lock, but this is safe wrt: 1545 * 1546 * fork: 1547 * None of sub-threads can fork after zap_process(leader). All 1548 * processes which were created before this point should be 1549 * visible to zap_threads() because copy_process() adds the new 1550 * process to the tail of init_task.tasks list, and lock/unlock 1551 * of ->siglock provides a memory barrier. 1552 * 1553 * do_exit: 1554 * The caller holds mm->mmap_sem. This means that the task which 1555 * uses this mm can't pass exit_mm(), so it can't exit or clear 1556 * its ->mm. 1557 * 1558 * de_thread: 1559 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 1560 * we must see either old or new leader, this does not matter. 1561 * However, it can change p->sighand, so lock_task_sighand(p) 1562 * must be used. Since p->mm != NULL and we hold ->mmap_sem 1563 * it can't fail. 1564 * 1565 * Note also that "g" can be the old leader with ->mm == NULL 1566 * and already unhashed and thus removed from ->thread_group. 1567 * This is OK, __unhash_process()->list_del_rcu() does not 1568 * clear the ->next pointer, we will find the new leader via 1569 * next_thread(). 1570 */ 1571 rcu_read_lock(); 1572 for_each_process(g) { 1573 if (g == tsk->group_leader) 1574 continue; 1575 if (g->flags & PF_KTHREAD) 1576 continue; 1577 p = g; 1578 do { 1579 if (p->mm) { 1580 if (unlikely(p->mm == mm)) { 1581 lock_task_sighand(p, &flags); 1582 nr += zap_process(p); 1583 unlock_task_sighand(p, &flags); 1584 } 1585 break; 1586 } 1587 } while_each_thread(g, p); 1588 } 1589 rcu_read_unlock(); 1590 done: 1591 atomic_set(&core_state->nr_threads, nr); 1592 return nr; 1593 } 1594 1595 static int coredump_wait(int exit_code, struct core_state *core_state) 1596 { 1597 struct task_struct *tsk = current; 1598 struct mm_struct *mm = tsk->mm; 1599 struct completion *vfork_done; 1600 int core_waiters; 1601 1602 init_completion(&core_state->startup); 1603 core_state->dumper.task = tsk; 1604 core_state->dumper.next = NULL; 1605 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 1606 up_write(&mm->mmap_sem); 1607 1608 if (unlikely(core_waiters < 0)) 1609 goto fail; 1610 1611 /* 1612 * Make sure nobody is waiting for us to release the VM, 1613 * otherwise we can deadlock when we wait on each other 1614 */ 1615 vfork_done = tsk->vfork_done; 1616 if (vfork_done) { 1617 tsk->vfork_done = NULL; 1618 complete(vfork_done); 1619 } 1620 1621 if (core_waiters) 1622 wait_for_completion(&core_state->startup); 1623 fail: 1624 return core_waiters; 1625 } 1626 1627 static void coredump_finish(struct mm_struct *mm) 1628 { 1629 struct core_thread *curr, *next; 1630 struct task_struct *task; 1631 1632 next = mm->core_state->dumper.next; 1633 while ((curr = next) != NULL) { 1634 next = curr->next; 1635 task = curr->task; 1636 /* 1637 * see exit_mm(), curr->task must not see 1638 * ->task == NULL before we read ->next. 1639 */ 1640 smp_mb(); 1641 curr->task = NULL; 1642 wake_up_process(task); 1643 } 1644 1645 mm->core_state = NULL; 1646 } 1647 1648 /* 1649 * set_dumpable converts traditional three-value dumpable to two flags and 1650 * stores them into mm->flags. It modifies lower two bits of mm->flags, but 1651 * these bits are not changed atomically. So get_dumpable can observe the 1652 * intermediate state. To avoid doing unexpected behavior, get get_dumpable 1653 * return either old dumpable or new one by paying attention to the order of 1654 * modifying the bits. 1655 * 1656 * dumpable | mm->flags (binary) 1657 * old new | initial interim final 1658 * ---------+----------------------- 1659 * 0 1 | 00 01 01 1660 * 0 2 | 00 10(*) 11 1661 * 1 0 | 01 00 00 1662 * 1 2 | 01 11 11 1663 * 2 0 | 11 10(*) 00 1664 * 2 1 | 11 11 01 1665 * 1666 * (*) get_dumpable regards interim value of 10 as 11. 1667 */ 1668 void set_dumpable(struct mm_struct *mm, int value) 1669 { 1670 switch (value) { 1671 case 0: 1672 clear_bit(MMF_DUMPABLE, &mm->flags); 1673 smp_wmb(); 1674 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1675 break; 1676 case 1: 1677 set_bit(MMF_DUMPABLE, &mm->flags); 1678 smp_wmb(); 1679 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1680 break; 1681 case 2: 1682 set_bit(MMF_DUMP_SECURELY, &mm->flags); 1683 smp_wmb(); 1684 set_bit(MMF_DUMPABLE, &mm->flags); 1685 break; 1686 } 1687 } 1688 1689 int get_dumpable(struct mm_struct *mm) 1690 { 1691 int ret; 1692 1693 ret = mm->flags & 0x3; 1694 return (ret >= 2) ? 2 : ret; 1695 } 1696 1697 int do_coredump(long signr, int exit_code, struct pt_regs * regs) 1698 { 1699 struct core_state core_state; 1700 char corename[CORENAME_MAX_SIZE + 1]; 1701 struct mm_struct *mm = current->mm; 1702 struct linux_binfmt * binfmt; 1703 struct inode * inode; 1704 struct file * file; 1705 int retval = 0; 1706 int fsuid = current->fsuid; 1707 int flag = 0; 1708 int ispipe = 0; 1709 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur; 1710 char **helper_argv = NULL; 1711 int helper_argc = 0; 1712 char *delimit; 1713 1714 audit_core_dumps(signr); 1715 1716 binfmt = current->binfmt; 1717 if (!binfmt || !binfmt->core_dump) 1718 goto fail; 1719 down_write(&mm->mmap_sem); 1720 /* 1721 * If another thread got here first, or we are not dumpable, bail out. 1722 */ 1723 if (mm->core_state || !get_dumpable(mm)) { 1724 up_write(&mm->mmap_sem); 1725 goto fail; 1726 } 1727 1728 /* 1729 * We cannot trust fsuid as being the "true" uid of the 1730 * process nor do we know its entire history. We only know it 1731 * was tainted so we dump it as root in mode 2. 1732 */ 1733 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ 1734 flag = O_EXCL; /* Stop rewrite attacks */ 1735 current->fsuid = 0; /* Dump root private */ 1736 } 1737 1738 retval = coredump_wait(exit_code, &core_state); 1739 if (retval < 0) 1740 goto fail; 1741 1742 /* 1743 * Clear any false indication of pending signals that might 1744 * be seen by the filesystem code called to write the core file. 1745 */ 1746 clear_thread_flag(TIF_SIGPENDING); 1747 1748 /* 1749 * lock_kernel() because format_corename() is controlled by sysctl, which 1750 * uses lock_kernel() 1751 */ 1752 lock_kernel(); 1753 ispipe = format_corename(corename, retval, signr); 1754 unlock_kernel(); 1755 /* 1756 * Don't bother to check the RLIMIT_CORE value if core_pattern points 1757 * to a pipe. Since we're not writing directly to the filesystem 1758 * RLIMIT_CORE doesn't really apply, as no actual core file will be 1759 * created unless the pipe reader choses to write out the core file 1760 * at which point file size limits and permissions will be imposed 1761 * as it does with any other process 1762 */ 1763 if ((!ispipe) && (core_limit < binfmt->min_coredump)) 1764 goto fail_unlock; 1765 1766 if (ispipe) { 1767 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc); 1768 /* Terminate the string before the first option */ 1769 delimit = strchr(corename, ' '); 1770 if (delimit) 1771 *delimit = '\0'; 1772 delimit = strrchr(helper_argv[0], '/'); 1773 if (delimit) 1774 delimit++; 1775 else 1776 delimit = helper_argv[0]; 1777 if (!strcmp(delimit, current->comm)) { 1778 printk(KERN_NOTICE "Recursive core dump detected, " 1779 "aborting\n"); 1780 goto fail_unlock; 1781 } 1782 1783 core_limit = RLIM_INFINITY; 1784 1785 /* SIGPIPE can happen, but it's just never processed */ 1786 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL, 1787 &file)) { 1788 printk(KERN_INFO "Core dump to %s pipe failed\n", 1789 corename); 1790 goto fail_unlock; 1791 } 1792 } else 1793 file = filp_open(corename, 1794 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 1795 0600); 1796 if (IS_ERR(file)) 1797 goto fail_unlock; 1798 inode = file->f_path.dentry->d_inode; 1799 if (inode->i_nlink > 1) 1800 goto close_fail; /* multiple links - don't dump */ 1801 if (!ispipe && d_unhashed(file->f_path.dentry)) 1802 goto close_fail; 1803 1804 /* AK: actually i see no reason to not allow this for named pipes etc., 1805 but keep the previous behaviour for now. */ 1806 if (!ispipe && !S_ISREG(inode->i_mode)) 1807 goto close_fail; 1808 /* 1809 * Dont allow local users get cute and trick others to coredump 1810 * into their pre-created files: 1811 */ 1812 if (inode->i_uid != current->fsuid) 1813 goto close_fail; 1814 if (!file->f_op) 1815 goto close_fail; 1816 if (!file->f_op->write) 1817 goto close_fail; 1818 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0) 1819 goto close_fail; 1820 1821 retval = binfmt->core_dump(signr, regs, file, core_limit); 1822 1823 if (retval) 1824 current->signal->group_exit_code |= 0x80; 1825 close_fail: 1826 filp_close(file, NULL); 1827 fail_unlock: 1828 if (helper_argv) 1829 argv_free(helper_argv); 1830 1831 current->fsuid = fsuid; 1832 coredump_finish(mm); 1833 fail: 1834 return retval; 1835 } 1836