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/swap.h> 32 #include <linux/string.h> 33 #include <linux/init.h> 34 #include <linux/pagemap.h> 35 #include <linux/perf_event.h> 36 #include <linux/highmem.h> 37 #include <linux/spinlock.h> 38 #include <linux/key.h> 39 #include <linux/personality.h> 40 #include <linux/binfmts.h> 41 #include <linux/utsname.h> 42 #include <linux/pid_namespace.h> 43 #include <linux/module.h> 44 #include <linux/namei.h> 45 #include <linux/mount.h> 46 #include <linux/security.h> 47 #include <linux/syscalls.h> 48 #include <linux/tsacct_kern.h> 49 #include <linux/cn_proc.h> 50 #include <linux/audit.h> 51 #include <linux/tracehook.h> 52 #include <linux/kmod.h> 53 #include <linux/fsnotify.h> 54 #include <linux/fs_struct.h> 55 #include <linux/pipe_fs_i.h> 56 #include <linux/oom.h> 57 #include <linux/compat.h> 58 59 #include <asm/uaccess.h> 60 #include <asm/mmu_context.h> 61 #include <asm/tlb.h> 62 63 #include <trace/events/task.h> 64 #include "internal.h" 65 66 int core_uses_pid; 67 char core_pattern[CORENAME_MAX_SIZE] = "core"; 68 unsigned int core_pipe_limit; 69 int suid_dumpable = 0; 70 71 struct core_name { 72 char *corename; 73 int used, size; 74 }; 75 static atomic_t call_count = ATOMIC_INIT(1); 76 77 /* The maximal length of core_pattern is also specified in sysctl.c */ 78 79 static LIST_HEAD(formats); 80 static DEFINE_RWLOCK(binfmt_lock); 81 82 int __register_binfmt(struct linux_binfmt * fmt, int insert) 83 { 84 if (!fmt) 85 return -EINVAL; 86 write_lock(&binfmt_lock); 87 insert ? list_add(&fmt->lh, &formats) : 88 list_add_tail(&fmt->lh, &formats); 89 write_unlock(&binfmt_lock); 90 return 0; 91 } 92 93 EXPORT_SYMBOL(__register_binfmt); 94 95 void unregister_binfmt(struct linux_binfmt * fmt) 96 { 97 write_lock(&binfmt_lock); 98 list_del(&fmt->lh); 99 write_unlock(&binfmt_lock); 100 } 101 102 EXPORT_SYMBOL(unregister_binfmt); 103 104 static inline void put_binfmt(struct linux_binfmt * fmt) 105 { 106 module_put(fmt->module); 107 } 108 109 /* 110 * Note that a shared library must be both readable and executable due to 111 * security reasons. 112 * 113 * Also note that we take the address to load from from the file itself. 114 */ 115 SYSCALL_DEFINE1(uselib, const char __user *, library) 116 { 117 struct file *file; 118 char *tmp = getname(library); 119 int error = PTR_ERR(tmp); 120 static const struct open_flags uselib_flags = { 121 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 122 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, 123 .intent = LOOKUP_OPEN 124 }; 125 126 if (IS_ERR(tmp)) 127 goto out; 128 129 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW); 130 putname(tmp); 131 error = PTR_ERR(file); 132 if (IS_ERR(file)) 133 goto out; 134 135 error = -EINVAL; 136 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) 137 goto exit; 138 139 error = -EACCES; 140 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 141 goto exit; 142 143 fsnotify_open(file); 144 145 error = -ENOEXEC; 146 if(file->f_op) { 147 struct linux_binfmt * fmt; 148 149 read_lock(&binfmt_lock); 150 list_for_each_entry(fmt, &formats, lh) { 151 if (!fmt->load_shlib) 152 continue; 153 if (!try_module_get(fmt->module)) 154 continue; 155 read_unlock(&binfmt_lock); 156 error = fmt->load_shlib(file); 157 read_lock(&binfmt_lock); 158 put_binfmt(fmt); 159 if (error != -ENOEXEC) 160 break; 161 } 162 read_unlock(&binfmt_lock); 163 } 164 exit: 165 fput(file); 166 out: 167 return error; 168 } 169 170 #ifdef CONFIG_MMU 171 /* 172 * The nascent bprm->mm is not visible until exec_mmap() but it can 173 * use a lot of memory, account these pages in current->mm temporary 174 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we 175 * change the counter back via acct_arg_size(0). 176 */ 177 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 178 { 179 struct mm_struct *mm = current->mm; 180 long diff = (long)(pages - bprm->vma_pages); 181 182 if (!mm || !diff) 183 return; 184 185 bprm->vma_pages = pages; 186 add_mm_counter(mm, MM_ANONPAGES, diff); 187 } 188 189 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 190 int write) 191 { 192 struct page *page; 193 int ret; 194 195 #ifdef CONFIG_STACK_GROWSUP 196 if (write) { 197 ret = expand_downwards(bprm->vma, pos); 198 if (ret < 0) 199 return NULL; 200 } 201 #endif 202 ret = get_user_pages(current, bprm->mm, pos, 203 1, write, 1, &page, NULL); 204 if (ret <= 0) 205 return NULL; 206 207 if (write) { 208 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; 209 struct rlimit *rlim; 210 211 acct_arg_size(bprm, size / PAGE_SIZE); 212 213 /* 214 * We've historically supported up to 32 pages (ARG_MAX) 215 * of argument strings even with small stacks 216 */ 217 if (size <= ARG_MAX) 218 return page; 219 220 /* 221 * Limit to 1/4-th the stack size for the argv+env strings. 222 * This ensures that: 223 * - the remaining binfmt code will not run out of stack space, 224 * - the program will have a reasonable amount of stack left 225 * to work from. 226 */ 227 rlim = current->signal->rlim; 228 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { 229 put_page(page); 230 return NULL; 231 } 232 } 233 234 return page; 235 } 236 237 static void put_arg_page(struct page *page) 238 { 239 put_page(page); 240 } 241 242 static void free_arg_page(struct linux_binprm *bprm, int i) 243 { 244 } 245 246 static void free_arg_pages(struct linux_binprm *bprm) 247 { 248 } 249 250 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 251 struct page *page) 252 { 253 flush_cache_page(bprm->vma, pos, page_to_pfn(page)); 254 } 255 256 static int __bprm_mm_init(struct linux_binprm *bprm) 257 { 258 int err; 259 struct vm_area_struct *vma = NULL; 260 struct mm_struct *mm = bprm->mm; 261 262 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 263 if (!vma) 264 return -ENOMEM; 265 266 down_write(&mm->mmap_sem); 267 vma->vm_mm = mm; 268 269 /* 270 * Place the stack at the largest stack address the architecture 271 * supports. Later, we'll move this to an appropriate place. We don't 272 * use STACK_TOP because that can depend on attributes which aren't 273 * configured yet. 274 */ 275 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); 276 vma->vm_end = STACK_TOP_MAX; 277 vma->vm_start = vma->vm_end - PAGE_SIZE; 278 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; 279 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 280 INIT_LIST_HEAD(&vma->anon_vma_chain); 281 282 err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); 283 if (err) 284 goto err; 285 286 err = insert_vm_struct(mm, vma); 287 if (err) 288 goto err; 289 290 mm->stack_vm = mm->total_vm = 1; 291 up_write(&mm->mmap_sem); 292 bprm->p = vma->vm_end - sizeof(void *); 293 return 0; 294 err: 295 up_write(&mm->mmap_sem); 296 bprm->vma = NULL; 297 kmem_cache_free(vm_area_cachep, vma); 298 return err; 299 } 300 301 static bool valid_arg_len(struct linux_binprm *bprm, long len) 302 { 303 return len <= MAX_ARG_STRLEN; 304 } 305 306 #else 307 308 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 309 { 310 } 311 312 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 313 int write) 314 { 315 struct page *page; 316 317 page = bprm->page[pos / PAGE_SIZE]; 318 if (!page && write) { 319 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 320 if (!page) 321 return NULL; 322 bprm->page[pos / PAGE_SIZE] = page; 323 } 324 325 return page; 326 } 327 328 static void put_arg_page(struct page *page) 329 { 330 } 331 332 static void free_arg_page(struct linux_binprm *bprm, int i) 333 { 334 if (bprm->page[i]) { 335 __free_page(bprm->page[i]); 336 bprm->page[i] = NULL; 337 } 338 } 339 340 static void free_arg_pages(struct linux_binprm *bprm) 341 { 342 int i; 343 344 for (i = 0; i < MAX_ARG_PAGES; i++) 345 free_arg_page(bprm, i); 346 } 347 348 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 349 struct page *page) 350 { 351 } 352 353 static int __bprm_mm_init(struct linux_binprm *bprm) 354 { 355 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 356 return 0; 357 } 358 359 static bool valid_arg_len(struct linux_binprm *bprm, long len) 360 { 361 return len <= bprm->p; 362 } 363 364 #endif /* CONFIG_MMU */ 365 366 /* 367 * Create a new mm_struct and populate it with a temporary stack 368 * vm_area_struct. We don't have enough context at this point to set the stack 369 * flags, permissions, and offset, so we use temporary values. We'll update 370 * them later in setup_arg_pages(). 371 */ 372 int bprm_mm_init(struct linux_binprm *bprm) 373 { 374 int err; 375 struct mm_struct *mm = NULL; 376 377 bprm->mm = mm = mm_alloc(); 378 err = -ENOMEM; 379 if (!mm) 380 goto err; 381 382 err = init_new_context(current, mm); 383 if (err) 384 goto err; 385 386 err = __bprm_mm_init(bprm); 387 if (err) 388 goto err; 389 390 return 0; 391 392 err: 393 if (mm) { 394 bprm->mm = NULL; 395 mmdrop(mm); 396 } 397 398 return err; 399 } 400 401 struct user_arg_ptr { 402 #ifdef CONFIG_COMPAT 403 bool is_compat; 404 #endif 405 union { 406 const char __user *const __user *native; 407 #ifdef CONFIG_COMPAT 408 compat_uptr_t __user *compat; 409 #endif 410 } ptr; 411 }; 412 413 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) 414 { 415 const char __user *native; 416 417 #ifdef CONFIG_COMPAT 418 if (unlikely(argv.is_compat)) { 419 compat_uptr_t compat; 420 421 if (get_user(compat, argv.ptr.compat + nr)) 422 return ERR_PTR(-EFAULT); 423 424 return compat_ptr(compat); 425 } 426 #endif 427 428 if (get_user(native, argv.ptr.native + nr)) 429 return ERR_PTR(-EFAULT); 430 431 return native; 432 } 433 434 /* 435 * count() counts the number of strings in array ARGV. 436 */ 437 static int count(struct user_arg_ptr argv, int max) 438 { 439 int i = 0; 440 441 if (argv.ptr.native != NULL) { 442 for (;;) { 443 const char __user *p = get_user_arg_ptr(argv, i); 444 445 if (!p) 446 break; 447 448 if (IS_ERR(p)) 449 return -EFAULT; 450 451 if (i++ >= max) 452 return -E2BIG; 453 454 if (fatal_signal_pending(current)) 455 return -ERESTARTNOHAND; 456 cond_resched(); 457 } 458 } 459 return i; 460 } 461 462 /* 463 * 'copy_strings()' copies argument/environment strings from the old 464 * processes's memory to the new process's stack. The call to get_user_pages() 465 * ensures the destination page is created and not swapped out. 466 */ 467 static int copy_strings(int argc, struct user_arg_ptr argv, 468 struct linux_binprm *bprm) 469 { 470 struct page *kmapped_page = NULL; 471 char *kaddr = NULL; 472 unsigned long kpos = 0; 473 int ret; 474 475 while (argc-- > 0) { 476 const char __user *str; 477 int len; 478 unsigned long pos; 479 480 ret = -EFAULT; 481 str = get_user_arg_ptr(argv, argc); 482 if (IS_ERR(str)) 483 goto out; 484 485 len = strnlen_user(str, MAX_ARG_STRLEN); 486 if (!len) 487 goto out; 488 489 ret = -E2BIG; 490 if (!valid_arg_len(bprm, len)) 491 goto out; 492 493 /* We're going to work our way backwords. */ 494 pos = bprm->p; 495 str += len; 496 bprm->p -= len; 497 498 while (len > 0) { 499 int offset, bytes_to_copy; 500 501 if (fatal_signal_pending(current)) { 502 ret = -ERESTARTNOHAND; 503 goto out; 504 } 505 cond_resched(); 506 507 offset = pos % PAGE_SIZE; 508 if (offset == 0) 509 offset = PAGE_SIZE; 510 511 bytes_to_copy = offset; 512 if (bytes_to_copy > len) 513 bytes_to_copy = len; 514 515 offset -= bytes_to_copy; 516 pos -= bytes_to_copy; 517 str -= bytes_to_copy; 518 len -= bytes_to_copy; 519 520 if (!kmapped_page || kpos != (pos & PAGE_MASK)) { 521 struct page *page; 522 523 page = get_arg_page(bprm, pos, 1); 524 if (!page) { 525 ret = -E2BIG; 526 goto out; 527 } 528 529 if (kmapped_page) { 530 flush_kernel_dcache_page(kmapped_page); 531 kunmap(kmapped_page); 532 put_arg_page(kmapped_page); 533 } 534 kmapped_page = page; 535 kaddr = kmap(kmapped_page); 536 kpos = pos & PAGE_MASK; 537 flush_arg_page(bprm, kpos, kmapped_page); 538 } 539 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { 540 ret = -EFAULT; 541 goto out; 542 } 543 } 544 } 545 ret = 0; 546 out: 547 if (kmapped_page) { 548 flush_kernel_dcache_page(kmapped_page); 549 kunmap(kmapped_page); 550 put_arg_page(kmapped_page); 551 } 552 return ret; 553 } 554 555 /* 556 * Like copy_strings, but get argv and its values from kernel memory. 557 */ 558 int copy_strings_kernel(int argc, const char *const *__argv, 559 struct linux_binprm *bprm) 560 { 561 int r; 562 mm_segment_t oldfs = get_fs(); 563 struct user_arg_ptr argv = { 564 .ptr.native = (const char __user *const __user *)__argv, 565 }; 566 567 set_fs(KERNEL_DS); 568 r = copy_strings(argc, argv, bprm); 569 set_fs(oldfs); 570 571 return r; 572 } 573 EXPORT_SYMBOL(copy_strings_kernel); 574 575 #ifdef CONFIG_MMU 576 577 /* 578 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once 579 * the binfmt code determines where the new stack should reside, we shift it to 580 * its final location. The process proceeds as follows: 581 * 582 * 1) Use shift to calculate the new vma endpoints. 583 * 2) Extend vma to cover both the old and new ranges. This ensures the 584 * arguments passed to subsequent functions are consistent. 585 * 3) Move vma's page tables to the new range. 586 * 4) Free up any cleared pgd range. 587 * 5) Shrink the vma to cover only the new range. 588 */ 589 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) 590 { 591 struct mm_struct *mm = vma->vm_mm; 592 unsigned long old_start = vma->vm_start; 593 unsigned long old_end = vma->vm_end; 594 unsigned long length = old_end - old_start; 595 unsigned long new_start = old_start - shift; 596 unsigned long new_end = old_end - shift; 597 struct mmu_gather tlb; 598 599 BUG_ON(new_start > new_end); 600 601 /* 602 * ensure there are no vmas between where we want to go 603 * and where we are 604 */ 605 if (vma != find_vma(mm, new_start)) 606 return -EFAULT; 607 608 /* 609 * cover the whole range: [new_start, old_end) 610 */ 611 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) 612 return -ENOMEM; 613 614 /* 615 * move the page tables downwards, on failure we rely on 616 * process cleanup to remove whatever mess we made. 617 */ 618 if (length != move_page_tables(vma, old_start, 619 vma, new_start, length)) 620 return -ENOMEM; 621 622 lru_add_drain(); 623 tlb_gather_mmu(&tlb, mm, 0); 624 if (new_end > old_start) { 625 /* 626 * when the old and new regions overlap clear from new_end. 627 */ 628 free_pgd_range(&tlb, new_end, old_end, new_end, 629 vma->vm_next ? vma->vm_next->vm_start : 0); 630 } else { 631 /* 632 * otherwise, clean from old_start; this is done to not touch 633 * the address space in [new_end, old_start) some architectures 634 * have constraints on va-space that make this illegal (IA64) - 635 * for the others its just a little faster. 636 */ 637 free_pgd_range(&tlb, old_start, old_end, new_end, 638 vma->vm_next ? vma->vm_next->vm_start : 0); 639 } 640 tlb_finish_mmu(&tlb, new_end, old_end); 641 642 /* 643 * Shrink the vma to just the new range. Always succeeds. 644 */ 645 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); 646 647 return 0; 648 } 649 650 /* 651 * Finalizes the stack vm_area_struct. The flags and permissions are updated, 652 * the stack is optionally relocated, and some extra space is added. 653 */ 654 int setup_arg_pages(struct linux_binprm *bprm, 655 unsigned long stack_top, 656 int executable_stack) 657 { 658 unsigned long ret; 659 unsigned long stack_shift; 660 struct mm_struct *mm = current->mm; 661 struct vm_area_struct *vma = bprm->vma; 662 struct vm_area_struct *prev = NULL; 663 unsigned long vm_flags; 664 unsigned long stack_base; 665 unsigned long stack_size; 666 unsigned long stack_expand; 667 unsigned long rlim_stack; 668 669 #ifdef CONFIG_STACK_GROWSUP 670 /* Limit stack size to 1GB */ 671 stack_base = rlimit_max(RLIMIT_STACK); 672 if (stack_base > (1 << 30)) 673 stack_base = 1 << 30; 674 675 /* Make sure we didn't let the argument array grow too large. */ 676 if (vma->vm_end - vma->vm_start > stack_base) 677 return -ENOMEM; 678 679 stack_base = PAGE_ALIGN(stack_top - stack_base); 680 681 stack_shift = vma->vm_start - stack_base; 682 mm->arg_start = bprm->p - stack_shift; 683 bprm->p = vma->vm_end - stack_shift; 684 #else 685 stack_top = arch_align_stack(stack_top); 686 stack_top = PAGE_ALIGN(stack_top); 687 688 if (unlikely(stack_top < mmap_min_addr) || 689 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) 690 return -ENOMEM; 691 692 stack_shift = vma->vm_end - stack_top; 693 694 bprm->p -= stack_shift; 695 mm->arg_start = bprm->p; 696 #endif 697 698 if (bprm->loader) 699 bprm->loader -= stack_shift; 700 bprm->exec -= stack_shift; 701 702 down_write(&mm->mmap_sem); 703 vm_flags = VM_STACK_FLAGS; 704 705 /* 706 * Adjust stack execute permissions; explicitly enable for 707 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone 708 * (arch default) otherwise. 709 */ 710 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 711 vm_flags |= VM_EXEC; 712 else if (executable_stack == EXSTACK_DISABLE_X) 713 vm_flags &= ~VM_EXEC; 714 vm_flags |= mm->def_flags; 715 vm_flags |= VM_STACK_INCOMPLETE_SETUP; 716 717 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, 718 vm_flags); 719 if (ret) 720 goto out_unlock; 721 BUG_ON(prev != vma); 722 723 /* Move stack pages down in memory. */ 724 if (stack_shift) { 725 ret = shift_arg_pages(vma, stack_shift); 726 if (ret) 727 goto out_unlock; 728 } 729 730 /* mprotect_fixup is overkill to remove the temporary stack flags */ 731 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; 732 733 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ 734 stack_size = vma->vm_end - vma->vm_start; 735 /* 736 * Align this down to a page boundary as expand_stack 737 * will align it up. 738 */ 739 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; 740 #ifdef CONFIG_STACK_GROWSUP 741 if (stack_size + stack_expand > rlim_stack) 742 stack_base = vma->vm_start + rlim_stack; 743 else 744 stack_base = vma->vm_end + stack_expand; 745 #else 746 if (stack_size + stack_expand > rlim_stack) 747 stack_base = vma->vm_end - rlim_stack; 748 else 749 stack_base = vma->vm_start - stack_expand; 750 #endif 751 current->mm->start_stack = bprm->p; 752 ret = expand_stack(vma, stack_base); 753 if (ret) 754 ret = -EFAULT; 755 756 out_unlock: 757 up_write(&mm->mmap_sem); 758 return ret; 759 } 760 EXPORT_SYMBOL(setup_arg_pages); 761 762 #endif /* CONFIG_MMU */ 763 764 struct file *open_exec(const char *name) 765 { 766 struct file *file; 767 int err; 768 static const struct open_flags open_exec_flags = { 769 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 770 .acc_mode = MAY_EXEC | MAY_OPEN, 771 .intent = LOOKUP_OPEN 772 }; 773 774 file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW); 775 if (IS_ERR(file)) 776 goto out; 777 778 err = -EACCES; 779 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) 780 goto exit; 781 782 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 783 goto exit; 784 785 fsnotify_open(file); 786 787 err = deny_write_access(file); 788 if (err) 789 goto exit; 790 791 out: 792 return file; 793 794 exit: 795 fput(file); 796 return ERR_PTR(err); 797 } 798 EXPORT_SYMBOL(open_exec); 799 800 int kernel_read(struct file *file, loff_t offset, 801 char *addr, unsigned long count) 802 { 803 mm_segment_t old_fs; 804 loff_t pos = offset; 805 int result; 806 807 old_fs = get_fs(); 808 set_fs(get_ds()); 809 /* The cast to a user pointer is valid due to the set_fs() */ 810 result = vfs_read(file, (void __user *)addr, count, &pos); 811 set_fs(old_fs); 812 return result; 813 } 814 815 EXPORT_SYMBOL(kernel_read); 816 817 static int exec_mmap(struct mm_struct *mm) 818 { 819 struct task_struct *tsk; 820 struct mm_struct * old_mm, *active_mm; 821 822 /* Notify parent that we're no longer interested in the old VM */ 823 tsk = current; 824 old_mm = current->mm; 825 sync_mm_rss(tsk, old_mm); 826 mm_release(tsk, old_mm); 827 828 if (old_mm) { 829 /* 830 * Make sure that if there is a core dump in progress 831 * for the old mm, we get out and die instead of going 832 * through with the exec. We must hold mmap_sem around 833 * checking core_state and changing tsk->mm. 834 */ 835 down_read(&old_mm->mmap_sem); 836 if (unlikely(old_mm->core_state)) { 837 up_read(&old_mm->mmap_sem); 838 return -EINTR; 839 } 840 } 841 task_lock(tsk); 842 active_mm = tsk->active_mm; 843 tsk->mm = mm; 844 tsk->active_mm = mm; 845 activate_mm(active_mm, mm); 846 task_unlock(tsk); 847 arch_pick_mmap_layout(mm); 848 if (old_mm) { 849 up_read(&old_mm->mmap_sem); 850 BUG_ON(active_mm != old_mm); 851 mm_update_next_owner(old_mm); 852 mmput(old_mm); 853 return 0; 854 } 855 mmdrop(active_mm); 856 return 0; 857 } 858 859 /* 860 * This function makes sure the current process has its own signal table, 861 * so that flush_signal_handlers can later reset the handlers without 862 * disturbing other processes. (Other processes might share the signal 863 * table via the CLONE_SIGHAND option to clone().) 864 */ 865 static int de_thread(struct task_struct *tsk) 866 { 867 struct signal_struct *sig = tsk->signal; 868 struct sighand_struct *oldsighand = tsk->sighand; 869 spinlock_t *lock = &oldsighand->siglock; 870 871 if (thread_group_empty(tsk)) 872 goto no_thread_group; 873 874 /* 875 * Kill all other threads in the thread group. 876 */ 877 spin_lock_irq(lock); 878 if (signal_group_exit(sig)) { 879 /* 880 * Another group action in progress, just 881 * return so that the signal is processed. 882 */ 883 spin_unlock_irq(lock); 884 return -EAGAIN; 885 } 886 887 sig->group_exit_task = tsk; 888 sig->notify_count = zap_other_threads(tsk); 889 if (!thread_group_leader(tsk)) 890 sig->notify_count--; 891 892 while (sig->notify_count) { 893 __set_current_state(TASK_UNINTERRUPTIBLE); 894 spin_unlock_irq(lock); 895 schedule(); 896 spin_lock_irq(lock); 897 } 898 spin_unlock_irq(lock); 899 900 /* 901 * At this point all other threads have exited, all we have to 902 * do is to wait for the thread group leader to become inactive, 903 * and to assume its PID: 904 */ 905 if (!thread_group_leader(tsk)) { 906 struct task_struct *leader = tsk->group_leader; 907 908 sig->notify_count = -1; /* for exit_notify() */ 909 for (;;) { 910 write_lock_irq(&tasklist_lock); 911 if (likely(leader->exit_state)) 912 break; 913 __set_current_state(TASK_UNINTERRUPTIBLE); 914 write_unlock_irq(&tasklist_lock); 915 schedule(); 916 } 917 918 /* 919 * The only record we have of the real-time age of a 920 * process, regardless of execs it's done, is start_time. 921 * All the past CPU time is accumulated in signal_struct 922 * from sister threads now dead. But in this non-leader 923 * exec, nothing survives from the original leader thread, 924 * whose birth marks the true age of this process now. 925 * When we take on its identity by switching to its PID, we 926 * also take its birthdate (always earlier than our own). 927 */ 928 tsk->start_time = leader->start_time; 929 930 BUG_ON(!same_thread_group(leader, tsk)); 931 BUG_ON(has_group_leader_pid(tsk)); 932 /* 933 * An exec() starts a new thread group with the 934 * TGID of the previous thread group. Rehash the 935 * two threads with a switched PID, and release 936 * the former thread group leader: 937 */ 938 939 /* Become a process group leader with the old leader's pid. 940 * The old leader becomes a thread of the this thread group. 941 * Note: The old leader also uses this pid until release_task 942 * is called. Odd but simple and correct. 943 */ 944 detach_pid(tsk, PIDTYPE_PID); 945 tsk->pid = leader->pid; 946 attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); 947 transfer_pid(leader, tsk, PIDTYPE_PGID); 948 transfer_pid(leader, tsk, PIDTYPE_SID); 949 950 list_replace_rcu(&leader->tasks, &tsk->tasks); 951 list_replace_init(&leader->sibling, &tsk->sibling); 952 953 tsk->group_leader = tsk; 954 leader->group_leader = tsk; 955 956 tsk->exit_signal = SIGCHLD; 957 leader->exit_signal = -1; 958 959 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 960 leader->exit_state = EXIT_DEAD; 961 962 /* 963 * We are going to release_task()->ptrace_unlink() silently, 964 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees 965 * the tracer wont't block again waiting for this thread. 966 */ 967 if (unlikely(leader->ptrace)) 968 __wake_up_parent(leader, leader->parent); 969 write_unlock_irq(&tasklist_lock); 970 971 release_task(leader); 972 } 973 974 sig->group_exit_task = NULL; 975 sig->notify_count = 0; 976 977 no_thread_group: 978 if (current->mm) 979 setmax_mm_hiwater_rss(&sig->maxrss, current->mm); 980 981 exit_itimers(sig); 982 flush_itimer_signals(); 983 984 if (atomic_read(&oldsighand->count) != 1) { 985 struct sighand_struct *newsighand; 986 /* 987 * This ->sighand is shared with the CLONE_SIGHAND 988 * but not CLONE_THREAD task, switch to the new one. 989 */ 990 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 991 if (!newsighand) 992 return -ENOMEM; 993 994 atomic_set(&newsighand->count, 1); 995 memcpy(newsighand->action, oldsighand->action, 996 sizeof(newsighand->action)); 997 998 write_lock_irq(&tasklist_lock); 999 spin_lock(&oldsighand->siglock); 1000 rcu_assign_pointer(tsk->sighand, newsighand); 1001 spin_unlock(&oldsighand->siglock); 1002 write_unlock_irq(&tasklist_lock); 1003 1004 __cleanup_sighand(oldsighand); 1005 } 1006 1007 BUG_ON(!thread_group_leader(tsk)); 1008 return 0; 1009 } 1010 1011 /* 1012 * These functions flushes out all traces of the currently running executable 1013 * so that a new one can be started 1014 */ 1015 static void flush_old_files(struct files_struct * files) 1016 { 1017 long j = -1; 1018 struct fdtable *fdt; 1019 1020 spin_lock(&files->file_lock); 1021 for (;;) { 1022 unsigned long set, i; 1023 1024 j++; 1025 i = j * __NFDBITS; 1026 fdt = files_fdtable(files); 1027 if (i >= fdt->max_fds) 1028 break; 1029 set = fdt->close_on_exec->fds_bits[j]; 1030 if (!set) 1031 continue; 1032 fdt->close_on_exec->fds_bits[j] = 0; 1033 spin_unlock(&files->file_lock); 1034 for ( ; set ; i++,set >>= 1) { 1035 if (set & 1) { 1036 sys_close(i); 1037 } 1038 } 1039 spin_lock(&files->file_lock); 1040 1041 } 1042 spin_unlock(&files->file_lock); 1043 } 1044 1045 char *get_task_comm(char *buf, struct task_struct *tsk) 1046 { 1047 /* buf must be at least sizeof(tsk->comm) in size */ 1048 task_lock(tsk); 1049 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 1050 task_unlock(tsk); 1051 return buf; 1052 } 1053 EXPORT_SYMBOL_GPL(get_task_comm); 1054 1055 void set_task_comm(struct task_struct *tsk, char *buf) 1056 { 1057 task_lock(tsk); 1058 1059 trace_task_rename(tsk, buf); 1060 1061 /* 1062 * Threads may access current->comm without holding 1063 * the task lock, so write the string carefully. 1064 * Readers without a lock may see incomplete new 1065 * names but are safe from non-terminating string reads. 1066 */ 1067 memset(tsk->comm, 0, TASK_COMM_LEN); 1068 wmb(); 1069 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 1070 task_unlock(tsk); 1071 perf_event_comm(tsk); 1072 } 1073 1074 static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len) 1075 { 1076 int i, ch; 1077 1078 /* Copies the binary name from after last slash */ 1079 for (i = 0; (ch = *(fn++)) != '\0';) { 1080 if (ch == '/') 1081 i = 0; /* overwrite what we wrote */ 1082 else 1083 if (i < len - 1) 1084 tcomm[i++] = ch; 1085 } 1086 tcomm[i] = '\0'; 1087 } 1088 1089 int flush_old_exec(struct linux_binprm * bprm) 1090 { 1091 int retval; 1092 1093 /* 1094 * Make sure we have a private signal table and that 1095 * we are unassociated from the previous thread group. 1096 */ 1097 retval = de_thread(current); 1098 if (retval) 1099 goto out; 1100 1101 set_mm_exe_file(bprm->mm, bprm->file); 1102 1103 filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm)); 1104 /* 1105 * Release all of the old mmap stuff 1106 */ 1107 acct_arg_size(bprm, 0); 1108 retval = exec_mmap(bprm->mm); 1109 if (retval) 1110 goto out; 1111 1112 bprm->mm = NULL; /* We're using it now */ 1113 1114 set_fs(USER_DS); 1115 current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD); 1116 flush_thread(); 1117 current->personality &= ~bprm->per_clear; 1118 1119 return 0; 1120 1121 out: 1122 return retval; 1123 } 1124 EXPORT_SYMBOL(flush_old_exec); 1125 1126 void would_dump(struct linux_binprm *bprm, struct file *file) 1127 { 1128 if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0) 1129 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; 1130 } 1131 EXPORT_SYMBOL(would_dump); 1132 1133 void setup_new_exec(struct linux_binprm * bprm) 1134 { 1135 arch_pick_mmap_layout(current->mm); 1136 1137 /* This is the point of no return */ 1138 current->sas_ss_sp = current->sas_ss_size = 0; 1139 1140 if (current_euid() == current_uid() && current_egid() == current_gid()) 1141 set_dumpable(current->mm, 1); 1142 else 1143 set_dumpable(current->mm, suid_dumpable); 1144 1145 set_task_comm(current, bprm->tcomm); 1146 1147 /* Set the new mm task size. We have to do that late because it may 1148 * depend on TIF_32BIT which is only updated in flush_thread() on 1149 * some architectures like powerpc 1150 */ 1151 current->mm->task_size = TASK_SIZE; 1152 1153 /* install the new credentials */ 1154 if (bprm->cred->uid != current_euid() || 1155 bprm->cred->gid != current_egid()) { 1156 current->pdeath_signal = 0; 1157 } else { 1158 would_dump(bprm, bprm->file); 1159 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) 1160 set_dumpable(current->mm, suid_dumpable); 1161 } 1162 1163 /* 1164 * Flush performance counters when crossing a 1165 * security domain: 1166 */ 1167 if (!get_dumpable(current->mm)) 1168 perf_event_exit_task(current); 1169 1170 /* An exec changes our domain. We are no longer part of the thread 1171 group */ 1172 1173 current->self_exec_id++; 1174 1175 flush_signal_handlers(current, 0); 1176 flush_old_files(current->files); 1177 } 1178 EXPORT_SYMBOL(setup_new_exec); 1179 1180 /* 1181 * Prepare credentials and lock ->cred_guard_mutex. 1182 * install_exec_creds() commits the new creds and drops the lock. 1183 * Or, if exec fails before, free_bprm() should release ->cred and 1184 * and unlock. 1185 */ 1186 int prepare_bprm_creds(struct linux_binprm *bprm) 1187 { 1188 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) 1189 return -ERESTARTNOINTR; 1190 1191 bprm->cred = prepare_exec_creds(); 1192 if (likely(bprm->cred)) 1193 return 0; 1194 1195 mutex_unlock(¤t->signal->cred_guard_mutex); 1196 return -ENOMEM; 1197 } 1198 1199 void free_bprm(struct linux_binprm *bprm) 1200 { 1201 free_arg_pages(bprm); 1202 if (bprm->cred) { 1203 mutex_unlock(¤t->signal->cred_guard_mutex); 1204 abort_creds(bprm->cred); 1205 } 1206 kfree(bprm); 1207 } 1208 1209 /* 1210 * install the new credentials for this executable 1211 */ 1212 void install_exec_creds(struct linux_binprm *bprm) 1213 { 1214 security_bprm_committing_creds(bprm); 1215 1216 commit_creds(bprm->cred); 1217 bprm->cred = NULL; 1218 /* 1219 * cred_guard_mutex must be held at least to this point to prevent 1220 * ptrace_attach() from altering our determination of the task's 1221 * credentials; any time after this it may be unlocked. 1222 */ 1223 security_bprm_committed_creds(bprm); 1224 mutex_unlock(¤t->signal->cred_guard_mutex); 1225 } 1226 EXPORT_SYMBOL(install_exec_creds); 1227 1228 /* 1229 * determine how safe it is to execute the proposed program 1230 * - the caller must hold ->cred_guard_mutex to protect against 1231 * PTRACE_ATTACH 1232 */ 1233 static int check_unsafe_exec(struct linux_binprm *bprm) 1234 { 1235 struct task_struct *p = current, *t; 1236 unsigned n_fs; 1237 int res = 0; 1238 1239 if (p->ptrace) { 1240 if (p->ptrace & PT_PTRACE_CAP) 1241 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; 1242 else 1243 bprm->unsafe |= LSM_UNSAFE_PTRACE; 1244 } 1245 1246 n_fs = 1; 1247 spin_lock(&p->fs->lock); 1248 rcu_read_lock(); 1249 for (t = next_thread(p); t != p; t = next_thread(t)) { 1250 if (t->fs == p->fs) 1251 n_fs++; 1252 } 1253 rcu_read_unlock(); 1254 1255 if (p->fs->users > n_fs) { 1256 bprm->unsafe |= LSM_UNSAFE_SHARE; 1257 } else { 1258 res = -EAGAIN; 1259 if (!p->fs->in_exec) { 1260 p->fs->in_exec = 1; 1261 res = 1; 1262 } 1263 } 1264 spin_unlock(&p->fs->lock); 1265 1266 return res; 1267 } 1268 1269 /* 1270 * Fill the binprm structure from the inode. 1271 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1272 * 1273 * This may be called multiple times for binary chains (scripts for example). 1274 */ 1275 int prepare_binprm(struct linux_binprm *bprm) 1276 { 1277 umode_t mode; 1278 struct inode * inode = bprm->file->f_path.dentry->d_inode; 1279 int retval; 1280 1281 mode = inode->i_mode; 1282 if (bprm->file->f_op == NULL) 1283 return -EACCES; 1284 1285 /* clear any previous set[ug]id data from a previous binary */ 1286 bprm->cred->euid = current_euid(); 1287 bprm->cred->egid = current_egid(); 1288 1289 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { 1290 /* Set-uid? */ 1291 if (mode & S_ISUID) { 1292 bprm->per_clear |= PER_CLEAR_ON_SETID; 1293 bprm->cred->euid = inode->i_uid; 1294 } 1295 1296 /* Set-gid? */ 1297 /* 1298 * If setgid is set but no group execute bit then this 1299 * is a candidate for mandatory locking, not a setgid 1300 * executable. 1301 */ 1302 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1303 bprm->per_clear |= PER_CLEAR_ON_SETID; 1304 bprm->cred->egid = inode->i_gid; 1305 } 1306 } 1307 1308 /* fill in binprm security blob */ 1309 retval = security_bprm_set_creds(bprm); 1310 if (retval) 1311 return retval; 1312 bprm->cred_prepared = 1; 1313 1314 memset(bprm->buf, 0, BINPRM_BUF_SIZE); 1315 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); 1316 } 1317 1318 EXPORT_SYMBOL(prepare_binprm); 1319 1320 /* 1321 * Arguments are '\0' separated strings found at the location bprm->p 1322 * points to; chop off the first by relocating brpm->p to right after 1323 * the first '\0' encountered. 1324 */ 1325 int remove_arg_zero(struct linux_binprm *bprm) 1326 { 1327 int ret = 0; 1328 unsigned long offset; 1329 char *kaddr; 1330 struct page *page; 1331 1332 if (!bprm->argc) 1333 return 0; 1334 1335 do { 1336 offset = bprm->p & ~PAGE_MASK; 1337 page = get_arg_page(bprm, bprm->p, 0); 1338 if (!page) { 1339 ret = -EFAULT; 1340 goto out; 1341 } 1342 kaddr = kmap_atomic(page, KM_USER0); 1343 1344 for (; offset < PAGE_SIZE && kaddr[offset]; 1345 offset++, bprm->p++) 1346 ; 1347 1348 kunmap_atomic(kaddr, KM_USER0); 1349 put_arg_page(page); 1350 1351 if (offset == PAGE_SIZE) 1352 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1353 } while (offset == PAGE_SIZE); 1354 1355 bprm->p++; 1356 bprm->argc--; 1357 ret = 0; 1358 1359 out: 1360 return ret; 1361 } 1362 EXPORT_SYMBOL(remove_arg_zero); 1363 1364 /* 1365 * cycle the list of binary formats handler, until one recognizes the image 1366 */ 1367 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) 1368 { 1369 unsigned int depth = bprm->recursion_depth; 1370 int try,retval; 1371 struct linux_binfmt *fmt; 1372 pid_t old_pid; 1373 1374 retval = security_bprm_check(bprm); 1375 if (retval) 1376 return retval; 1377 1378 retval = audit_bprm(bprm); 1379 if (retval) 1380 return retval; 1381 1382 /* Need to fetch pid before load_binary changes it */ 1383 rcu_read_lock(); 1384 old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); 1385 rcu_read_unlock(); 1386 1387 retval = -ENOENT; 1388 for (try=0; try<2; try++) { 1389 read_lock(&binfmt_lock); 1390 list_for_each_entry(fmt, &formats, lh) { 1391 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; 1392 if (!fn) 1393 continue; 1394 if (!try_module_get(fmt->module)) 1395 continue; 1396 read_unlock(&binfmt_lock); 1397 retval = fn(bprm, regs); 1398 /* 1399 * Restore the depth counter to its starting value 1400 * in this call, so we don't have to rely on every 1401 * load_binary function to restore it on return. 1402 */ 1403 bprm->recursion_depth = depth; 1404 if (retval >= 0) { 1405 if (depth == 0) 1406 ptrace_event(PTRACE_EVENT_EXEC, 1407 old_pid); 1408 put_binfmt(fmt); 1409 allow_write_access(bprm->file); 1410 if (bprm->file) 1411 fput(bprm->file); 1412 bprm->file = NULL; 1413 current->did_exec = 1; 1414 proc_exec_connector(current); 1415 return retval; 1416 } 1417 read_lock(&binfmt_lock); 1418 put_binfmt(fmt); 1419 if (retval != -ENOEXEC || bprm->mm == NULL) 1420 break; 1421 if (!bprm->file) { 1422 read_unlock(&binfmt_lock); 1423 return retval; 1424 } 1425 } 1426 read_unlock(&binfmt_lock); 1427 #ifdef CONFIG_MODULES 1428 if (retval != -ENOEXEC || bprm->mm == NULL) { 1429 break; 1430 } else { 1431 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1432 if (printable(bprm->buf[0]) && 1433 printable(bprm->buf[1]) && 1434 printable(bprm->buf[2]) && 1435 printable(bprm->buf[3])) 1436 break; /* -ENOEXEC */ 1437 if (try) 1438 break; /* -ENOEXEC */ 1439 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1440 } 1441 #else 1442 break; 1443 #endif 1444 } 1445 return retval; 1446 } 1447 1448 EXPORT_SYMBOL(search_binary_handler); 1449 1450 /* 1451 * sys_execve() executes a new program. 1452 */ 1453 static int do_execve_common(const char *filename, 1454 struct user_arg_ptr argv, 1455 struct user_arg_ptr envp, 1456 struct pt_regs *regs) 1457 { 1458 struct linux_binprm *bprm; 1459 struct file *file; 1460 struct files_struct *displaced; 1461 bool clear_in_exec; 1462 int retval; 1463 const struct cred *cred = current_cred(); 1464 1465 /* 1466 * We move the actual failure in case of RLIMIT_NPROC excess from 1467 * set*uid() to execve() because too many poorly written programs 1468 * don't check setuid() return code. Here we additionally recheck 1469 * whether NPROC limit is still exceeded. 1470 */ 1471 if ((current->flags & PF_NPROC_EXCEEDED) && 1472 atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) { 1473 retval = -EAGAIN; 1474 goto out_ret; 1475 } 1476 1477 /* We're below the limit (still or again), so we don't want to make 1478 * further execve() calls fail. */ 1479 current->flags &= ~PF_NPROC_EXCEEDED; 1480 1481 retval = unshare_files(&displaced); 1482 if (retval) 1483 goto out_ret; 1484 1485 retval = -ENOMEM; 1486 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1487 if (!bprm) 1488 goto out_files; 1489 1490 retval = prepare_bprm_creds(bprm); 1491 if (retval) 1492 goto out_free; 1493 1494 retval = check_unsafe_exec(bprm); 1495 if (retval < 0) 1496 goto out_free; 1497 clear_in_exec = retval; 1498 current->in_execve = 1; 1499 1500 file = open_exec(filename); 1501 retval = PTR_ERR(file); 1502 if (IS_ERR(file)) 1503 goto out_unmark; 1504 1505 sched_exec(); 1506 1507 bprm->file = file; 1508 bprm->filename = filename; 1509 bprm->interp = filename; 1510 1511 retval = bprm_mm_init(bprm); 1512 if (retval) 1513 goto out_file; 1514 1515 bprm->argc = count(argv, MAX_ARG_STRINGS); 1516 if ((retval = bprm->argc) < 0) 1517 goto out; 1518 1519 bprm->envc = count(envp, MAX_ARG_STRINGS); 1520 if ((retval = bprm->envc) < 0) 1521 goto out; 1522 1523 retval = prepare_binprm(bprm); 1524 if (retval < 0) 1525 goto out; 1526 1527 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1528 if (retval < 0) 1529 goto out; 1530 1531 bprm->exec = bprm->p; 1532 retval = copy_strings(bprm->envc, envp, bprm); 1533 if (retval < 0) 1534 goto out; 1535 1536 retval = copy_strings(bprm->argc, argv, bprm); 1537 if (retval < 0) 1538 goto out; 1539 1540 retval = search_binary_handler(bprm,regs); 1541 if (retval < 0) 1542 goto out; 1543 1544 /* execve succeeded */ 1545 current->fs->in_exec = 0; 1546 current->in_execve = 0; 1547 acct_update_integrals(current); 1548 free_bprm(bprm); 1549 if (displaced) 1550 put_files_struct(displaced); 1551 return retval; 1552 1553 out: 1554 if (bprm->mm) { 1555 acct_arg_size(bprm, 0); 1556 mmput(bprm->mm); 1557 } 1558 1559 out_file: 1560 if (bprm->file) { 1561 allow_write_access(bprm->file); 1562 fput(bprm->file); 1563 } 1564 1565 out_unmark: 1566 if (clear_in_exec) 1567 current->fs->in_exec = 0; 1568 current->in_execve = 0; 1569 1570 out_free: 1571 free_bprm(bprm); 1572 1573 out_files: 1574 if (displaced) 1575 reset_files_struct(displaced); 1576 out_ret: 1577 return retval; 1578 } 1579 1580 int do_execve(const char *filename, 1581 const char __user *const __user *__argv, 1582 const char __user *const __user *__envp, 1583 struct pt_regs *regs) 1584 { 1585 struct user_arg_ptr argv = { .ptr.native = __argv }; 1586 struct user_arg_ptr envp = { .ptr.native = __envp }; 1587 return do_execve_common(filename, argv, envp, regs); 1588 } 1589 1590 #ifdef CONFIG_COMPAT 1591 int compat_do_execve(char *filename, 1592 compat_uptr_t __user *__argv, 1593 compat_uptr_t __user *__envp, 1594 struct pt_regs *regs) 1595 { 1596 struct user_arg_ptr argv = { 1597 .is_compat = true, 1598 .ptr.compat = __argv, 1599 }; 1600 struct user_arg_ptr envp = { 1601 .is_compat = true, 1602 .ptr.compat = __envp, 1603 }; 1604 return do_execve_common(filename, argv, envp, regs); 1605 } 1606 #endif 1607 1608 void set_binfmt(struct linux_binfmt *new) 1609 { 1610 struct mm_struct *mm = current->mm; 1611 1612 if (mm->binfmt) 1613 module_put(mm->binfmt->module); 1614 1615 mm->binfmt = new; 1616 if (new) 1617 __module_get(new->module); 1618 } 1619 1620 EXPORT_SYMBOL(set_binfmt); 1621 1622 static int expand_corename(struct core_name *cn) 1623 { 1624 char *old_corename = cn->corename; 1625 1626 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count); 1627 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL); 1628 1629 if (!cn->corename) { 1630 kfree(old_corename); 1631 return -ENOMEM; 1632 } 1633 1634 return 0; 1635 } 1636 1637 static int cn_printf(struct core_name *cn, const char *fmt, ...) 1638 { 1639 char *cur; 1640 int need; 1641 int ret; 1642 va_list arg; 1643 1644 va_start(arg, fmt); 1645 need = vsnprintf(NULL, 0, fmt, arg); 1646 va_end(arg); 1647 1648 if (likely(need < cn->size - cn->used - 1)) 1649 goto out_printf; 1650 1651 ret = expand_corename(cn); 1652 if (ret) 1653 goto expand_fail; 1654 1655 out_printf: 1656 cur = cn->corename + cn->used; 1657 va_start(arg, fmt); 1658 vsnprintf(cur, need + 1, fmt, arg); 1659 va_end(arg); 1660 cn->used += need; 1661 return 0; 1662 1663 expand_fail: 1664 return ret; 1665 } 1666 1667 static void cn_escape(char *str) 1668 { 1669 for (; *str; str++) 1670 if (*str == '/') 1671 *str = '!'; 1672 } 1673 1674 static int cn_print_exe_file(struct core_name *cn) 1675 { 1676 struct file *exe_file; 1677 char *pathbuf, *path; 1678 int ret; 1679 1680 exe_file = get_mm_exe_file(current->mm); 1681 if (!exe_file) { 1682 char *commstart = cn->corename + cn->used; 1683 ret = cn_printf(cn, "%s (path unknown)", current->comm); 1684 cn_escape(commstart); 1685 return ret; 1686 } 1687 1688 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY); 1689 if (!pathbuf) { 1690 ret = -ENOMEM; 1691 goto put_exe_file; 1692 } 1693 1694 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX); 1695 if (IS_ERR(path)) { 1696 ret = PTR_ERR(path); 1697 goto free_buf; 1698 } 1699 1700 cn_escape(path); 1701 1702 ret = cn_printf(cn, "%s", path); 1703 1704 free_buf: 1705 kfree(pathbuf); 1706 put_exe_file: 1707 fput(exe_file); 1708 return ret; 1709 } 1710 1711 /* format_corename will inspect the pattern parameter, and output a 1712 * name into corename, which must have space for at least 1713 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 1714 */ 1715 static int format_corename(struct core_name *cn, long signr) 1716 { 1717 const struct cred *cred = current_cred(); 1718 const char *pat_ptr = core_pattern; 1719 int ispipe = (*pat_ptr == '|'); 1720 int pid_in_pattern = 0; 1721 int err = 0; 1722 1723 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count); 1724 cn->corename = kmalloc(cn->size, GFP_KERNEL); 1725 cn->used = 0; 1726 1727 if (!cn->corename) 1728 return -ENOMEM; 1729 1730 /* Repeat as long as we have more pattern to process and more output 1731 space */ 1732 while (*pat_ptr) { 1733 if (*pat_ptr != '%') { 1734 if (*pat_ptr == 0) 1735 goto out; 1736 err = cn_printf(cn, "%c", *pat_ptr++); 1737 } else { 1738 switch (*++pat_ptr) { 1739 /* single % at the end, drop that */ 1740 case 0: 1741 goto out; 1742 /* Double percent, output one percent */ 1743 case '%': 1744 err = cn_printf(cn, "%c", '%'); 1745 break; 1746 /* pid */ 1747 case 'p': 1748 pid_in_pattern = 1; 1749 err = cn_printf(cn, "%d", 1750 task_tgid_vnr(current)); 1751 break; 1752 /* uid */ 1753 case 'u': 1754 err = cn_printf(cn, "%d", cred->uid); 1755 break; 1756 /* gid */ 1757 case 'g': 1758 err = cn_printf(cn, "%d", cred->gid); 1759 break; 1760 /* signal that caused the coredump */ 1761 case 's': 1762 err = cn_printf(cn, "%ld", signr); 1763 break; 1764 /* UNIX time of coredump */ 1765 case 't': { 1766 struct timeval tv; 1767 do_gettimeofday(&tv); 1768 err = cn_printf(cn, "%lu", tv.tv_sec); 1769 break; 1770 } 1771 /* hostname */ 1772 case 'h': { 1773 char *namestart = cn->corename + cn->used; 1774 down_read(&uts_sem); 1775 err = cn_printf(cn, "%s", 1776 utsname()->nodename); 1777 up_read(&uts_sem); 1778 cn_escape(namestart); 1779 break; 1780 } 1781 /* executable */ 1782 case 'e': { 1783 char *commstart = cn->corename + cn->used; 1784 err = cn_printf(cn, "%s", current->comm); 1785 cn_escape(commstart); 1786 break; 1787 } 1788 case 'E': 1789 err = cn_print_exe_file(cn); 1790 break; 1791 /* core limit size */ 1792 case 'c': 1793 err = cn_printf(cn, "%lu", 1794 rlimit(RLIMIT_CORE)); 1795 break; 1796 default: 1797 break; 1798 } 1799 ++pat_ptr; 1800 } 1801 1802 if (err) 1803 return err; 1804 } 1805 1806 /* Backward compatibility with core_uses_pid: 1807 * 1808 * If core_pattern does not include a %p (as is the default) 1809 * and core_uses_pid is set, then .%pid will be appended to 1810 * the filename. Do not do this for piped commands. */ 1811 if (!ispipe && !pid_in_pattern && core_uses_pid) { 1812 err = cn_printf(cn, ".%d", task_tgid_vnr(current)); 1813 if (err) 1814 return err; 1815 } 1816 out: 1817 return ispipe; 1818 } 1819 1820 static int zap_process(struct task_struct *start, int exit_code) 1821 { 1822 struct task_struct *t; 1823 int nr = 0; 1824 1825 start->signal->flags = SIGNAL_GROUP_EXIT; 1826 start->signal->group_exit_code = exit_code; 1827 start->signal->group_stop_count = 0; 1828 1829 t = start; 1830 do { 1831 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK); 1832 if (t != current && t->mm) { 1833 sigaddset(&t->pending.signal, SIGKILL); 1834 signal_wake_up(t, 1); 1835 nr++; 1836 } 1837 } while_each_thread(start, t); 1838 1839 return nr; 1840 } 1841 1842 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 1843 struct core_state *core_state, int exit_code) 1844 { 1845 struct task_struct *g, *p; 1846 unsigned long flags; 1847 int nr = -EAGAIN; 1848 1849 spin_lock_irq(&tsk->sighand->siglock); 1850 if (!signal_group_exit(tsk->signal)) { 1851 mm->core_state = core_state; 1852 nr = zap_process(tsk, exit_code); 1853 } 1854 spin_unlock_irq(&tsk->sighand->siglock); 1855 if (unlikely(nr < 0)) 1856 return nr; 1857 1858 if (atomic_read(&mm->mm_users) == nr + 1) 1859 goto done; 1860 /* 1861 * We should find and kill all tasks which use this mm, and we should 1862 * count them correctly into ->nr_threads. We don't take tasklist 1863 * lock, but this is safe wrt: 1864 * 1865 * fork: 1866 * None of sub-threads can fork after zap_process(leader). All 1867 * processes which were created before this point should be 1868 * visible to zap_threads() because copy_process() adds the new 1869 * process to the tail of init_task.tasks list, and lock/unlock 1870 * of ->siglock provides a memory barrier. 1871 * 1872 * do_exit: 1873 * The caller holds mm->mmap_sem. This means that the task which 1874 * uses this mm can't pass exit_mm(), so it can't exit or clear 1875 * its ->mm. 1876 * 1877 * de_thread: 1878 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 1879 * we must see either old or new leader, this does not matter. 1880 * However, it can change p->sighand, so lock_task_sighand(p) 1881 * must be used. Since p->mm != NULL and we hold ->mmap_sem 1882 * it can't fail. 1883 * 1884 * Note also that "g" can be the old leader with ->mm == NULL 1885 * and already unhashed and thus removed from ->thread_group. 1886 * This is OK, __unhash_process()->list_del_rcu() does not 1887 * clear the ->next pointer, we will find the new leader via 1888 * next_thread(). 1889 */ 1890 rcu_read_lock(); 1891 for_each_process(g) { 1892 if (g == tsk->group_leader) 1893 continue; 1894 if (g->flags & PF_KTHREAD) 1895 continue; 1896 p = g; 1897 do { 1898 if (p->mm) { 1899 if (unlikely(p->mm == mm)) { 1900 lock_task_sighand(p, &flags); 1901 nr += zap_process(p, exit_code); 1902 unlock_task_sighand(p, &flags); 1903 } 1904 break; 1905 } 1906 } while_each_thread(g, p); 1907 } 1908 rcu_read_unlock(); 1909 done: 1910 atomic_set(&core_state->nr_threads, nr); 1911 return nr; 1912 } 1913 1914 static int coredump_wait(int exit_code, struct core_state *core_state) 1915 { 1916 struct task_struct *tsk = current; 1917 struct mm_struct *mm = tsk->mm; 1918 int core_waiters = -EBUSY; 1919 1920 init_completion(&core_state->startup); 1921 core_state->dumper.task = tsk; 1922 core_state->dumper.next = NULL; 1923 1924 down_write(&mm->mmap_sem); 1925 if (!mm->core_state) 1926 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 1927 up_write(&mm->mmap_sem); 1928 1929 if (core_waiters > 0) 1930 wait_for_completion(&core_state->startup); 1931 1932 return core_waiters; 1933 } 1934 1935 static void coredump_finish(struct mm_struct *mm) 1936 { 1937 struct core_thread *curr, *next; 1938 struct task_struct *task; 1939 1940 next = mm->core_state->dumper.next; 1941 while ((curr = next) != NULL) { 1942 next = curr->next; 1943 task = curr->task; 1944 /* 1945 * see exit_mm(), curr->task must not see 1946 * ->task == NULL before we read ->next. 1947 */ 1948 smp_mb(); 1949 curr->task = NULL; 1950 wake_up_process(task); 1951 } 1952 1953 mm->core_state = NULL; 1954 } 1955 1956 /* 1957 * set_dumpable converts traditional three-value dumpable to two flags and 1958 * stores them into mm->flags. It modifies lower two bits of mm->flags, but 1959 * these bits are not changed atomically. So get_dumpable can observe the 1960 * intermediate state. To avoid doing unexpected behavior, get get_dumpable 1961 * return either old dumpable or new one by paying attention to the order of 1962 * modifying the bits. 1963 * 1964 * dumpable | mm->flags (binary) 1965 * old new | initial interim final 1966 * ---------+----------------------- 1967 * 0 1 | 00 01 01 1968 * 0 2 | 00 10(*) 11 1969 * 1 0 | 01 00 00 1970 * 1 2 | 01 11 11 1971 * 2 0 | 11 10(*) 00 1972 * 2 1 | 11 11 01 1973 * 1974 * (*) get_dumpable regards interim value of 10 as 11. 1975 */ 1976 void set_dumpable(struct mm_struct *mm, int value) 1977 { 1978 switch (value) { 1979 case 0: 1980 clear_bit(MMF_DUMPABLE, &mm->flags); 1981 smp_wmb(); 1982 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1983 break; 1984 case 1: 1985 set_bit(MMF_DUMPABLE, &mm->flags); 1986 smp_wmb(); 1987 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1988 break; 1989 case 2: 1990 set_bit(MMF_DUMP_SECURELY, &mm->flags); 1991 smp_wmb(); 1992 set_bit(MMF_DUMPABLE, &mm->flags); 1993 break; 1994 } 1995 } 1996 1997 static int __get_dumpable(unsigned long mm_flags) 1998 { 1999 int ret; 2000 2001 ret = mm_flags & MMF_DUMPABLE_MASK; 2002 return (ret >= 2) ? 2 : ret; 2003 } 2004 2005 int get_dumpable(struct mm_struct *mm) 2006 { 2007 return __get_dumpable(mm->flags); 2008 } 2009 2010 static void wait_for_dump_helpers(struct file *file) 2011 { 2012 struct pipe_inode_info *pipe; 2013 2014 pipe = file->f_path.dentry->d_inode->i_pipe; 2015 2016 pipe_lock(pipe); 2017 pipe->readers++; 2018 pipe->writers--; 2019 2020 while ((pipe->readers > 1) && (!signal_pending(current))) { 2021 wake_up_interruptible_sync(&pipe->wait); 2022 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); 2023 pipe_wait(pipe); 2024 } 2025 2026 pipe->readers--; 2027 pipe->writers++; 2028 pipe_unlock(pipe); 2029 2030 } 2031 2032 2033 /* 2034 * umh_pipe_setup 2035 * helper function to customize the process used 2036 * to collect the core in userspace. Specifically 2037 * it sets up a pipe and installs it as fd 0 (stdin) 2038 * for the process. Returns 0 on success, or 2039 * PTR_ERR on failure. 2040 * Note that it also sets the core limit to 1. This 2041 * is a special value that we use to trap recursive 2042 * core dumps 2043 */ 2044 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) 2045 { 2046 struct file *rp, *wp; 2047 struct fdtable *fdt; 2048 struct coredump_params *cp = (struct coredump_params *)info->data; 2049 struct files_struct *cf = current->files; 2050 2051 wp = create_write_pipe(0); 2052 if (IS_ERR(wp)) 2053 return PTR_ERR(wp); 2054 2055 rp = create_read_pipe(wp, 0); 2056 if (IS_ERR(rp)) { 2057 free_write_pipe(wp); 2058 return PTR_ERR(rp); 2059 } 2060 2061 cp->file = wp; 2062 2063 sys_close(0); 2064 fd_install(0, rp); 2065 spin_lock(&cf->file_lock); 2066 fdt = files_fdtable(cf); 2067 FD_SET(0, fdt->open_fds); 2068 FD_CLR(0, fdt->close_on_exec); 2069 spin_unlock(&cf->file_lock); 2070 2071 /* and disallow core files too */ 2072 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; 2073 2074 return 0; 2075 } 2076 2077 void do_coredump(long signr, int exit_code, struct pt_regs *regs) 2078 { 2079 struct core_state core_state; 2080 struct core_name cn; 2081 struct mm_struct *mm = current->mm; 2082 struct linux_binfmt * binfmt; 2083 const struct cred *old_cred; 2084 struct cred *cred; 2085 int retval = 0; 2086 int flag = 0; 2087 int ispipe; 2088 static atomic_t core_dump_count = ATOMIC_INIT(0); 2089 struct coredump_params cprm = { 2090 .signr = signr, 2091 .regs = regs, 2092 .limit = rlimit(RLIMIT_CORE), 2093 /* 2094 * We must use the same mm->flags while dumping core to avoid 2095 * inconsistency of bit flags, since this flag is not protected 2096 * by any locks. 2097 */ 2098 .mm_flags = mm->flags, 2099 }; 2100 2101 audit_core_dumps(signr); 2102 2103 binfmt = mm->binfmt; 2104 if (!binfmt || !binfmt->core_dump) 2105 goto fail; 2106 if (!__get_dumpable(cprm.mm_flags)) 2107 goto fail; 2108 2109 cred = prepare_creds(); 2110 if (!cred) 2111 goto fail; 2112 /* 2113 * We cannot trust fsuid as being the "true" uid of the 2114 * process nor do we know its entire history. We only know it 2115 * was tainted so we dump it as root in mode 2. 2116 */ 2117 if (__get_dumpable(cprm.mm_flags) == 2) { 2118 /* Setuid core dump mode */ 2119 flag = O_EXCL; /* Stop rewrite attacks */ 2120 cred->fsuid = 0; /* Dump root private */ 2121 } 2122 2123 retval = coredump_wait(exit_code, &core_state); 2124 if (retval < 0) 2125 goto fail_creds; 2126 2127 old_cred = override_creds(cred); 2128 2129 /* 2130 * Clear any false indication of pending signals that might 2131 * be seen by the filesystem code called to write the core file. 2132 */ 2133 clear_thread_flag(TIF_SIGPENDING); 2134 2135 ispipe = format_corename(&cn, signr); 2136 2137 if (ispipe) { 2138 int dump_count; 2139 char **helper_argv; 2140 2141 if (ispipe < 0) { 2142 printk(KERN_WARNING "format_corename failed\n"); 2143 printk(KERN_WARNING "Aborting core\n"); 2144 goto fail_corename; 2145 } 2146 2147 if (cprm.limit == 1) { 2148 /* 2149 * Normally core limits are irrelevant to pipes, since 2150 * we're not writing to the file system, but we use 2151 * cprm.limit of 1 here as a speacial value. Any 2152 * non-1 limit gets set to RLIM_INFINITY below, but 2153 * a limit of 0 skips the dump. This is a consistent 2154 * way to catch recursive crashes. We can still crash 2155 * if the core_pattern binary sets RLIM_CORE = !1 2156 * but it runs as root, and can do lots of stupid things 2157 * Note that we use task_tgid_vnr here to grab the pid 2158 * of the process group leader. That way we get the 2159 * right pid if a thread in a multi-threaded 2160 * core_pattern process dies. 2161 */ 2162 printk(KERN_WARNING 2163 "Process %d(%s) has RLIMIT_CORE set to 1\n", 2164 task_tgid_vnr(current), current->comm); 2165 printk(KERN_WARNING "Aborting core\n"); 2166 goto fail_unlock; 2167 } 2168 cprm.limit = RLIM_INFINITY; 2169 2170 dump_count = atomic_inc_return(&core_dump_count); 2171 if (core_pipe_limit && (core_pipe_limit < dump_count)) { 2172 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", 2173 task_tgid_vnr(current), current->comm); 2174 printk(KERN_WARNING "Skipping core dump\n"); 2175 goto fail_dropcount; 2176 } 2177 2178 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL); 2179 if (!helper_argv) { 2180 printk(KERN_WARNING "%s failed to allocate memory\n", 2181 __func__); 2182 goto fail_dropcount; 2183 } 2184 2185 retval = call_usermodehelper_fns(helper_argv[0], helper_argv, 2186 NULL, UMH_WAIT_EXEC, umh_pipe_setup, 2187 NULL, &cprm); 2188 argv_free(helper_argv); 2189 if (retval) { 2190 printk(KERN_INFO "Core dump to %s pipe failed\n", 2191 cn.corename); 2192 goto close_fail; 2193 } 2194 } else { 2195 struct inode *inode; 2196 2197 if (cprm.limit < binfmt->min_coredump) 2198 goto fail_unlock; 2199 2200 cprm.file = filp_open(cn.corename, 2201 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 2202 0600); 2203 if (IS_ERR(cprm.file)) 2204 goto fail_unlock; 2205 2206 inode = cprm.file->f_path.dentry->d_inode; 2207 if (inode->i_nlink > 1) 2208 goto close_fail; 2209 if (d_unhashed(cprm.file->f_path.dentry)) 2210 goto close_fail; 2211 /* 2212 * AK: actually i see no reason to not allow this for named 2213 * pipes etc, but keep the previous behaviour for now. 2214 */ 2215 if (!S_ISREG(inode->i_mode)) 2216 goto close_fail; 2217 /* 2218 * Dont allow local users get cute and trick others to coredump 2219 * into their pre-created files. 2220 */ 2221 if (inode->i_uid != current_fsuid()) 2222 goto close_fail; 2223 if (!cprm.file->f_op || !cprm.file->f_op->write) 2224 goto close_fail; 2225 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) 2226 goto close_fail; 2227 } 2228 2229 retval = binfmt->core_dump(&cprm); 2230 if (retval) 2231 current->signal->group_exit_code |= 0x80; 2232 2233 if (ispipe && core_pipe_limit) 2234 wait_for_dump_helpers(cprm.file); 2235 close_fail: 2236 if (cprm.file) 2237 filp_close(cprm.file, NULL); 2238 fail_dropcount: 2239 if (ispipe) 2240 atomic_dec(&core_dump_count); 2241 fail_unlock: 2242 kfree(cn.corename); 2243 fail_corename: 2244 coredump_finish(mm); 2245 revert_creds(old_cred); 2246 fail_creds: 2247 put_cred(cred); 2248 fail: 2249 return; 2250 } 2251 2252 /* 2253 * Core dumping helper functions. These are the only things you should 2254 * do on a core-file: use only these functions to write out all the 2255 * necessary info. 2256 */ 2257 int dump_write(struct file *file, const void *addr, int nr) 2258 { 2259 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr; 2260 } 2261 EXPORT_SYMBOL(dump_write); 2262 2263 int dump_seek(struct file *file, loff_t off) 2264 { 2265 int ret = 1; 2266 2267 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 2268 if (file->f_op->llseek(file, off, SEEK_CUR) < 0) 2269 return 0; 2270 } else { 2271 char *buf = (char *)get_zeroed_page(GFP_KERNEL); 2272 2273 if (!buf) 2274 return 0; 2275 while (off > 0) { 2276 unsigned long n = off; 2277 2278 if (n > PAGE_SIZE) 2279 n = PAGE_SIZE; 2280 if (!dump_write(file, buf, n)) { 2281 ret = 0; 2282 break; 2283 } 2284 off -= n; 2285 } 2286 free_page((unsigned long)buf); 2287 } 2288 return ret; 2289 } 2290 EXPORT_SYMBOL(dump_seek); 2291