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 #include "coredump.h" 66 67 #include <trace/events/sched.h> 68 69 int suid_dumpable = 0; 70 71 static LIST_HEAD(formats); 72 static DEFINE_RWLOCK(binfmt_lock); 73 74 void __register_binfmt(struct linux_binfmt * fmt, int insert) 75 { 76 BUG_ON(!fmt); 77 write_lock(&binfmt_lock); 78 insert ? list_add(&fmt->lh, &formats) : 79 list_add_tail(&fmt->lh, &formats); 80 write_unlock(&binfmt_lock); 81 } 82 83 EXPORT_SYMBOL(__register_binfmt); 84 85 void unregister_binfmt(struct linux_binfmt * fmt) 86 { 87 write_lock(&binfmt_lock); 88 list_del(&fmt->lh); 89 write_unlock(&binfmt_lock); 90 } 91 92 EXPORT_SYMBOL(unregister_binfmt); 93 94 static inline void put_binfmt(struct linux_binfmt * fmt) 95 { 96 module_put(fmt->module); 97 } 98 99 /* 100 * Note that a shared library must be both readable and executable due to 101 * security reasons. 102 * 103 * Also note that we take the address to load from from the file itself. 104 */ 105 SYSCALL_DEFINE1(uselib, const char __user *, library) 106 { 107 struct file *file; 108 struct filename *tmp = getname(library); 109 int error = PTR_ERR(tmp); 110 static const struct open_flags uselib_flags = { 111 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 112 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, 113 .intent = LOOKUP_OPEN 114 }; 115 116 if (IS_ERR(tmp)) 117 goto out; 118 119 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW); 120 putname(tmp); 121 error = PTR_ERR(file); 122 if (IS_ERR(file)) 123 goto out; 124 125 error = -EINVAL; 126 if (!S_ISREG(file_inode(file)->i_mode)) 127 goto exit; 128 129 error = -EACCES; 130 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 131 goto exit; 132 133 fsnotify_open(file); 134 135 error = -ENOEXEC; 136 if(file->f_op) { 137 struct linux_binfmt * fmt; 138 139 read_lock(&binfmt_lock); 140 list_for_each_entry(fmt, &formats, lh) { 141 if (!fmt->load_shlib) 142 continue; 143 if (!try_module_get(fmt->module)) 144 continue; 145 read_unlock(&binfmt_lock); 146 error = fmt->load_shlib(file); 147 read_lock(&binfmt_lock); 148 put_binfmt(fmt); 149 if (error != -ENOEXEC) 150 break; 151 } 152 read_unlock(&binfmt_lock); 153 } 154 exit: 155 fput(file); 156 out: 157 return error; 158 } 159 160 #ifdef CONFIG_MMU 161 /* 162 * The nascent bprm->mm is not visible until exec_mmap() but it can 163 * use a lot of memory, account these pages in current->mm temporary 164 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we 165 * change the counter back via acct_arg_size(0). 166 */ 167 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 168 { 169 struct mm_struct *mm = current->mm; 170 long diff = (long)(pages - bprm->vma_pages); 171 172 if (!mm || !diff) 173 return; 174 175 bprm->vma_pages = pages; 176 add_mm_counter(mm, MM_ANONPAGES, diff); 177 } 178 179 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 180 int write) 181 { 182 struct page *page; 183 int ret; 184 185 #ifdef CONFIG_STACK_GROWSUP 186 if (write) { 187 ret = expand_downwards(bprm->vma, pos); 188 if (ret < 0) 189 return NULL; 190 } 191 #endif 192 ret = get_user_pages(current, bprm->mm, pos, 193 1, write, 1, &page, NULL); 194 if (ret <= 0) 195 return NULL; 196 197 if (write) { 198 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; 199 struct rlimit *rlim; 200 201 acct_arg_size(bprm, size / PAGE_SIZE); 202 203 /* 204 * We've historically supported up to 32 pages (ARG_MAX) 205 * of argument strings even with small stacks 206 */ 207 if (size <= ARG_MAX) 208 return page; 209 210 /* 211 * Limit to 1/4-th the stack size for the argv+env strings. 212 * This ensures that: 213 * - the remaining binfmt code will not run out of stack space, 214 * - the program will have a reasonable amount of stack left 215 * to work from. 216 */ 217 rlim = current->signal->rlim; 218 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { 219 put_page(page); 220 return NULL; 221 } 222 } 223 224 return page; 225 } 226 227 static void put_arg_page(struct page *page) 228 { 229 put_page(page); 230 } 231 232 static void free_arg_page(struct linux_binprm *bprm, int i) 233 { 234 } 235 236 static void free_arg_pages(struct linux_binprm *bprm) 237 { 238 } 239 240 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 241 struct page *page) 242 { 243 flush_cache_page(bprm->vma, pos, page_to_pfn(page)); 244 } 245 246 static int __bprm_mm_init(struct linux_binprm *bprm) 247 { 248 int err; 249 struct vm_area_struct *vma = NULL; 250 struct mm_struct *mm = bprm->mm; 251 252 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 253 if (!vma) 254 return -ENOMEM; 255 256 down_write(&mm->mmap_sem); 257 vma->vm_mm = mm; 258 259 /* 260 * Place the stack at the largest stack address the architecture 261 * supports. Later, we'll move this to an appropriate place. We don't 262 * use STACK_TOP because that can depend on attributes which aren't 263 * configured yet. 264 */ 265 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); 266 vma->vm_end = STACK_TOP_MAX; 267 vma->vm_start = vma->vm_end - PAGE_SIZE; 268 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; 269 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 270 INIT_LIST_HEAD(&vma->anon_vma_chain); 271 272 err = insert_vm_struct(mm, vma); 273 if (err) 274 goto err; 275 276 mm->stack_vm = mm->total_vm = 1; 277 up_write(&mm->mmap_sem); 278 bprm->p = vma->vm_end - sizeof(void *); 279 return 0; 280 err: 281 up_write(&mm->mmap_sem); 282 bprm->vma = NULL; 283 kmem_cache_free(vm_area_cachep, vma); 284 return err; 285 } 286 287 static bool valid_arg_len(struct linux_binprm *bprm, long len) 288 { 289 return len <= MAX_ARG_STRLEN; 290 } 291 292 #else 293 294 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 295 { 296 } 297 298 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 299 int write) 300 { 301 struct page *page; 302 303 page = bprm->page[pos / PAGE_SIZE]; 304 if (!page && write) { 305 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 306 if (!page) 307 return NULL; 308 bprm->page[pos / PAGE_SIZE] = page; 309 } 310 311 return page; 312 } 313 314 static void put_arg_page(struct page *page) 315 { 316 } 317 318 static void free_arg_page(struct linux_binprm *bprm, int i) 319 { 320 if (bprm->page[i]) { 321 __free_page(bprm->page[i]); 322 bprm->page[i] = NULL; 323 } 324 } 325 326 static void free_arg_pages(struct linux_binprm *bprm) 327 { 328 int i; 329 330 for (i = 0; i < MAX_ARG_PAGES; i++) 331 free_arg_page(bprm, i); 332 } 333 334 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 335 struct page *page) 336 { 337 } 338 339 static int __bprm_mm_init(struct linux_binprm *bprm) 340 { 341 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 342 return 0; 343 } 344 345 static bool valid_arg_len(struct linux_binprm *bprm, long len) 346 { 347 return len <= bprm->p; 348 } 349 350 #endif /* CONFIG_MMU */ 351 352 /* 353 * Create a new mm_struct and populate it with a temporary stack 354 * vm_area_struct. We don't have enough context at this point to set the stack 355 * flags, permissions, and offset, so we use temporary values. We'll update 356 * them later in setup_arg_pages(). 357 */ 358 static int bprm_mm_init(struct linux_binprm *bprm) 359 { 360 int err; 361 struct mm_struct *mm = NULL; 362 363 bprm->mm = mm = mm_alloc(); 364 err = -ENOMEM; 365 if (!mm) 366 goto err; 367 368 err = init_new_context(current, mm); 369 if (err) 370 goto err; 371 372 err = __bprm_mm_init(bprm); 373 if (err) 374 goto err; 375 376 return 0; 377 378 err: 379 if (mm) { 380 bprm->mm = NULL; 381 mmdrop(mm); 382 } 383 384 return err; 385 } 386 387 struct user_arg_ptr { 388 #ifdef CONFIG_COMPAT 389 bool is_compat; 390 #endif 391 union { 392 const char __user *const __user *native; 393 #ifdef CONFIG_COMPAT 394 const compat_uptr_t __user *compat; 395 #endif 396 } ptr; 397 }; 398 399 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) 400 { 401 const char __user *native; 402 403 #ifdef CONFIG_COMPAT 404 if (unlikely(argv.is_compat)) { 405 compat_uptr_t compat; 406 407 if (get_user(compat, argv.ptr.compat + nr)) 408 return ERR_PTR(-EFAULT); 409 410 return compat_ptr(compat); 411 } 412 #endif 413 414 if (get_user(native, argv.ptr.native + nr)) 415 return ERR_PTR(-EFAULT); 416 417 return native; 418 } 419 420 /* 421 * count() counts the number of strings in array ARGV. 422 */ 423 static int count(struct user_arg_ptr argv, int max) 424 { 425 int i = 0; 426 427 if (argv.ptr.native != NULL) { 428 for (;;) { 429 const char __user *p = get_user_arg_ptr(argv, i); 430 431 if (!p) 432 break; 433 434 if (IS_ERR(p)) 435 return -EFAULT; 436 437 if (i >= max) 438 return -E2BIG; 439 ++i; 440 441 if (fatal_signal_pending(current)) 442 return -ERESTARTNOHAND; 443 cond_resched(); 444 } 445 } 446 return i; 447 } 448 449 /* 450 * 'copy_strings()' copies argument/environment strings from the old 451 * processes's memory to the new process's stack. The call to get_user_pages() 452 * ensures the destination page is created and not swapped out. 453 */ 454 static int copy_strings(int argc, struct user_arg_ptr argv, 455 struct linux_binprm *bprm) 456 { 457 struct page *kmapped_page = NULL; 458 char *kaddr = NULL; 459 unsigned long kpos = 0; 460 int ret; 461 462 while (argc-- > 0) { 463 const char __user *str; 464 int len; 465 unsigned long pos; 466 467 ret = -EFAULT; 468 str = get_user_arg_ptr(argv, argc); 469 if (IS_ERR(str)) 470 goto out; 471 472 len = strnlen_user(str, MAX_ARG_STRLEN); 473 if (!len) 474 goto out; 475 476 ret = -E2BIG; 477 if (!valid_arg_len(bprm, len)) 478 goto out; 479 480 /* We're going to work our way backwords. */ 481 pos = bprm->p; 482 str += len; 483 bprm->p -= len; 484 485 while (len > 0) { 486 int offset, bytes_to_copy; 487 488 if (fatal_signal_pending(current)) { 489 ret = -ERESTARTNOHAND; 490 goto out; 491 } 492 cond_resched(); 493 494 offset = pos % PAGE_SIZE; 495 if (offset == 0) 496 offset = PAGE_SIZE; 497 498 bytes_to_copy = offset; 499 if (bytes_to_copy > len) 500 bytes_to_copy = len; 501 502 offset -= bytes_to_copy; 503 pos -= bytes_to_copy; 504 str -= bytes_to_copy; 505 len -= bytes_to_copy; 506 507 if (!kmapped_page || kpos != (pos & PAGE_MASK)) { 508 struct page *page; 509 510 page = get_arg_page(bprm, pos, 1); 511 if (!page) { 512 ret = -E2BIG; 513 goto out; 514 } 515 516 if (kmapped_page) { 517 flush_kernel_dcache_page(kmapped_page); 518 kunmap(kmapped_page); 519 put_arg_page(kmapped_page); 520 } 521 kmapped_page = page; 522 kaddr = kmap(kmapped_page); 523 kpos = pos & PAGE_MASK; 524 flush_arg_page(bprm, kpos, kmapped_page); 525 } 526 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { 527 ret = -EFAULT; 528 goto out; 529 } 530 } 531 } 532 ret = 0; 533 out: 534 if (kmapped_page) { 535 flush_kernel_dcache_page(kmapped_page); 536 kunmap(kmapped_page); 537 put_arg_page(kmapped_page); 538 } 539 return ret; 540 } 541 542 /* 543 * Like copy_strings, but get argv and its values from kernel memory. 544 */ 545 int copy_strings_kernel(int argc, const char *const *__argv, 546 struct linux_binprm *bprm) 547 { 548 int r; 549 mm_segment_t oldfs = get_fs(); 550 struct user_arg_ptr argv = { 551 .ptr.native = (const char __user *const __user *)__argv, 552 }; 553 554 set_fs(KERNEL_DS); 555 r = copy_strings(argc, argv, bprm); 556 set_fs(oldfs); 557 558 return r; 559 } 560 EXPORT_SYMBOL(copy_strings_kernel); 561 562 #ifdef CONFIG_MMU 563 564 /* 565 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once 566 * the binfmt code determines where the new stack should reside, we shift it to 567 * its final location. The process proceeds as follows: 568 * 569 * 1) Use shift to calculate the new vma endpoints. 570 * 2) Extend vma to cover both the old and new ranges. This ensures the 571 * arguments passed to subsequent functions are consistent. 572 * 3) Move vma's page tables to the new range. 573 * 4) Free up any cleared pgd range. 574 * 5) Shrink the vma to cover only the new range. 575 */ 576 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) 577 { 578 struct mm_struct *mm = vma->vm_mm; 579 unsigned long old_start = vma->vm_start; 580 unsigned long old_end = vma->vm_end; 581 unsigned long length = old_end - old_start; 582 unsigned long new_start = old_start - shift; 583 unsigned long new_end = old_end - shift; 584 struct mmu_gather tlb; 585 586 BUG_ON(new_start > new_end); 587 588 /* 589 * ensure there are no vmas between where we want to go 590 * and where we are 591 */ 592 if (vma != find_vma(mm, new_start)) 593 return -EFAULT; 594 595 /* 596 * cover the whole range: [new_start, old_end) 597 */ 598 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) 599 return -ENOMEM; 600 601 /* 602 * move the page tables downwards, on failure we rely on 603 * process cleanup to remove whatever mess we made. 604 */ 605 if (length != move_page_tables(vma, old_start, 606 vma, new_start, length, false)) 607 return -ENOMEM; 608 609 lru_add_drain(); 610 tlb_gather_mmu(&tlb, mm, 0); 611 if (new_end > old_start) { 612 /* 613 * when the old and new regions overlap clear from new_end. 614 */ 615 free_pgd_range(&tlb, new_end, old_end, new_end, 616 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); 617 } else { 618 /* 619 * otherwise, clean from old_start; this is done to not touch 620 * the address space in [new_end, old_start) some architectures 621 * have constraints on va-space that make this illegal (IA64) - 622 * for the others its just a little faster. 623 */ 624 free_pgd_range(&tlb, old_start, old_end, new_end, 625 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); 626 } 627 tlb_finish_mmu(&tlb, new_end, old_end); 628 629 /* 630 * Shrink the vma to just the new range. Always succeeds. 631 */ 632 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); 633 634 return 0; 635 } 636 637 /* 638 * Finalizes the stack vm_area_struct. The flags and permissions are updated, 639 * the stack is optionally relocated, and some extra space is added. 640 */ 641 int setup_arg_pages(struct linux_binprm *bprm, 642 unsigned long stack_top, 643 int executable_stack) 644 { 645 unsigned long ret; 646 unsigned long stack_shift; 647 struct mm_struct *mm = current->mm; 648 struct vm_area_struct *vma = bprm->vma; 649 struct vm_area_struct *prev = NULL; 650 unsigned long vm_flags; 651 unsigned long stack_base; 652 unsigned long stack_size; 653 unsigned long stack_expand; 654 unsigned long rlim_stack; 655 656 #ifdef CONFIG_STACK_GROWSUP 657 /* Limit stack size to 1GB */ 658 stack_base = rlimit_max(RLIMIT_STACK); 659 if (stack_base > (1 << 30)) 660 stack_base = 1 << 30; 661 662 /* Make sure we didn't let the argument array grow too large. */ 663 if (vma->vm_end - vma->vm_start > stack_base) 664 return -ENOMEM; 665 666 stack_base = PAGE_ALIGN(stack_top - stack_base); 667 668 stack_shift = vma->vm_start - stack_base; 669 mm->arg_start = bprm->p - stack_shift; 670 bprm->p = vma->vm_end - stack_shift; 671 #else 672 stack_top = arch_align_stack(stack_top); 673 stack_top = PAGE_ALIGN(stack_top); 674 675 if (unlikely(stack_top < mmap_min_addr) || 676 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) 677 return -ENOMEM; 678 679 stack_shift = vma->vm_end - stack_top; 680 681 bprm->p -= stack_shift; 682 mm->arg_start = bprm->p; 683 #endif 684 685 if (bprm->loader) 686 bprm->loader -= stack_shift; 687 bprm->exec -= stack_shift; 688 689 down_write(&mm->mmap_sem); 690 vm_flags = VM_STACK_FLAGS; 691 692 /* 693 * Adjust stack execute permissions; explicitly enable for 694 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone 695 * (arch default) otherwise. 696 */ 697 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 698 vm_flags |= VM_EXEC; 699 else if (executable_stack == EXSTACK_DISABLE_X) 700 vm_flags &= ~VM_EXEC; 701 vm_flags |= mm->def_flags; 702 vm_flags |= VM_STACK_INCOMPLETE_SETUP; 703 704 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, 705 vm_flags); 706 if (ret) 707 goto out_unlock; 708 BUG_ON(prev != vma); 709 710 /* Move stack pages down in memory. */ 711 if (stack_shift) { 712 ret = shift_arg_pages(vma, stack_shift); 713 if (ret) 714 goto out_unlock; 715 } 716 717 /* mprotect_fixup is overkill to remove the temporary stack flags */ 718 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; 719 720 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ 721 stack_size = vma->vm_end - vma->vm_start; 722 /* 723 * Align this down to a page boundary as expand_stack 724 * will align it up. 725 */ 726 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; 727 #ifdef CONFIG_STACK_GROWSUP 728 if (stack_size + stack_expand > rlim_stack) 729 stack_base = vma->vm_start + rlim_stack; 730 else 731 stack_base = vma->vm_end + stack_expand; 732 #else 733 if (stack_size + stack_expand > rlim_stack) 734 stack_base = vma->vm_end - rlim_stack; 735 else 736 stack_base = vma->vm_start - stack_expand; 737 #endif 738 current->mm->start_stack = bprm->p; 739 ret = expand_stack(vma, stack_base); 740 if (ret) 741 ret = -EFAULT; 742 743 out_unlock: 744 up_write(&mm->mmap_sem); 745 return ret; 746 } 747 EXPORT_SYMBOL(setup_arg_pages); 748 749 #endif /* CONFIG_MMU */ 750 751 struct file *open_exec(const char *name) 752 { 753 struct file *file; 754 int err; 755 struct filename tmp = { .name = name }; 756 static const struct open_flags open_exec_flags = { 757 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 758 .acc_mode = MAY_EXEC | MAY_OPEN, 759 .intent = LOOKUP_OPEN 760 }; 761 762 file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags, LOOKUP_FOLLOW); 763 if (IS_ERR(file)) 764 goto out; 765 766 err = -EACCES; 767 if (!S_ISREG(file_inode(file)->i_mode)) 768 goto exit; 769 770 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 771 goto exit; 772 773 fsnotify_open(file); 774 775 err = deny_write_access(file); 776 if (err) 777 goto exit; 778 779 out: 780 return file; 781 782 exit: 783 fput(file); 784 return ERR_PTR(err); 785 } 786 EXPORT_SYMBOL(open_exec); 787 788 int kernel_read(struct file *file, loff_t offset, 789 char *addr, unsigned long count) 790 { 791 mm_segment_t old_fs; 792 loff_t pos = offset; 793 int result; 794 795 old_fs = get_fs(); 796 set_fs(get_ds()); 797 /* The cast to a user pointer is valid due to the set_fs() */ 798 result = vfs_read(file, (void __user *)addr, count, &pos); 799 set_fs(old_fs); 800 return result; 801 } 802 803 EXPORT_SYMBOL(kernel_read); 804 805 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len) 806 { 807 ssize_t res = file->f_op->read(file, (void __user *)addr, len, &pos); 808 if (res > 0) 809 flush_icache_range(addr, addr + len); 810 return res; 811 } 812 EXPORT_SYMBOL(read_code); 813 814 static int exec_mmap(struct mm_struct *mm) 815 { 816 struct task_struct *tsk; 817 struct mm_struct * old_mm, *active_mm; 818 819 /* Notify parent that we're no longer interested in the old VM */ 820 tsk = current; 821 old_mm = current->mm; 822 mm_release(tsk, old_mm); 823 824 if (old_mm) { 825 sync_mm_rss(old_mm); 826 /* 827 * Make sure that if there is a core dump in progress 828 * for the old mm, we get out and die instead of going 829 * through with the exec. We must hold mmap_sem around 830 * checking core_state and changing tsk->mm. 831 */ 832 down_read(&old_mm->mmap_sem); 833 if (unlikely(old_mm->core_state)) { 834 up_read(&old_mm->mmap_sem); 835 return -EINTR; 836 } 837 } 838 task_lock(tsk); 839 active_mm = tsk->active_mm; 840 tsk->mm = mm; 841 tsk->active_mm = mm; 842 activate_mm(active_mm, mm); 843 task_unlock(tsk); 844 arch_pick_mmap_layout(mm); 845 if (old_mm) { 846 up_read(&old_mm->mmap_sem); 847 BUG_ON(active_mm != old_mm); 848 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); 849 mm_update_next_owner(old_mm); 850 mmput(old_mm); 851 return 0; 852 } 853 mmdrop(active_mm); 854 return 0; 855 } 856 857 /* 858 * This function makes sure the current process has its own signal table, 859 * so that flush_signal_handlers can later reset the handlers without 860 * disturbing other processes. (Other processes might share the signal 861 * table via the CLONE_SIGHAND option to clone().) 862 */ 863 static int de_thread(struct task_struct *tsk) 864 { 865 struct signal_struct *sig = tsk->signal; 866 struct sighand_struct *oldsighand = tsk->sighand; 867 spinlock_t *lock = &oldsighand->siglock; 868 869 if (thread_group_empty(tsk)) 870 goto no_thread_group; 871 872 /* 873 * Kill all other threads in the thread group. 874 */ 875 spin_lock_irq(lock); 876 if (signal_group_exit(sig)) { 877 /* 878 * Another group action in progress, just 879 * return so that the signal is processed. 880 */ 881 spin_unlock_irq(lock); 882 return -EAGAIN; 883 } 884 885 sig->group_exit_task = tsk; 886 sig->notify_count = zap_other_threads(tsk); 887 if (!thread_group_leader(tsk)) 888 sig->notify_count--; 889 890 while (sig->notify_count) { 891 __set_current_state(TASK_KILLABLE); 892 spin_unlock_irq(lock); 893 schedule(); 894 if (unlikely(__fatal_signal_pending(tsk))) 895 goto killed; 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 threadgroup_change_begin(tsk); 911 write_lock_irq(&tasklist_lock); 912 if (likely(leader->exit_state)) 913 break; 914 __set_current_state(TASK_KILLABLE); 915 write_unlock_irq(&tasklist_lock); 916 threadgroup_change_end(tsk); 917 schedule(); 918 if (unlikely(__fatal_signal_pending(tsk))) 919 goto killed; 920 } 921 922 /* 923 * The only record we have of the real-time age of a 924 * process, regardless of execs it's done, is start_time. 925 * All the past CPU time is accumulated in signal_struct 926 * from sister threads now dead. But in this non-leader 927 * exec, nothing survives from the original leader thread, 928 * whose birth marks the true age of this process now. 929 * When we take on its identity by switching to its PID, we 930 * also take its birthdate (always earlier than our own). 931 */ 932 tsk->start_time = leader->start_time; 933 934 BUG_ON(!same_thread_group(leader, tsk)); 935 BUG_ON(has_group_leader_pid(tsk)); 936 /* 937 * An exec() starts a new thread group with the 938 * TGID of the previous thread group. Rehash the 939 * two threads with a switched PID, and release 940 * the former thread group leader: 941 */ 942 943 /* Become a process group leader with the old leader's pid. 944 * The old leader becomes a thread of the this thread group. 945 * Note: The old leader also uses this pid until release_task 946 * is called. Odd but simple and correct. 947 */ 948 detach_pid(tsk, PIDTYPE_PID); 949 tsk->pid = leader->pid; 950 attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); 951 transfer_pid(leader, tsk, PIDTYPE_PGID); 952 transfer_pid(leader, tsk, PIDTYPE_SID); 953 954 list_replace_rcu(&leader->tasks, &tsk->tasks); 955 list_replace_init(&leader->sibling, &tsk->sibling); 956 957 tsk->group_leader = tsk; 958 leader->group_leader = tsk; 959 960 tsk->exit_signal = SIGCHLD; 961 leader->exit_signal = -1; 962 963 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 964 leader->exit_state = EXIT_DEAD; 965 966 /* 967 * We are going to release_task()->ptrace_unlink() silently, 968 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees 969 * the tracer wont't block again waiting for this thread. 970 */ 971 if (unlikely(leader->ptrace)) 972 __wake_up_parent(leader, leader->parent); 973 write_unlock_irq(&tasklist_lock); 974 threadgroup_change_end(tsk); 975 976 release_task(leader); 977 } 978 979 sig->group_exit_task = NULL; 980 sig->notify_count = 0; 981 982 no_thread_group: 983 /* we have changed execution domain */ 984 tsk->exit_signal = SIGCHLD; 985 986 exit_itimers(sig); 987 flush_itimer_signals(); 988 989 if (atomic_read(&oldsighand->count) != 1) { 990 struct sighand_struct *newsighand; 991 /* 992 * This ->sighand is shared with the CLONE_SIGHAND 993 * but not CLONE_THREAD task, switch to the new one. 994 */ 995 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 996 if (!newsighand) 997 return -ENOMEM; 998 999 atomic_set(&newsighand->count, 1); 1000 memcpy(newsighand->action, oldsighand->action, 1001 sizeof(newsighand->action)); 1002 1003 write_lock_irq(&tasklist_lock); 1004 spin_lock(&oldsighand->siglock); 1005 rcu_assign_pointer(tsk->sighand, newsighand); 1006 spin_unlock(&oldsighand->siglock); 1007 write_unlock_irq(&tasklist_lock); 1008 1009 __cleanup_sighand(oldsighand); 1010 } 1011 1012 BUG_ON(!thread_group_leader(tsk)); 1013 return 0; 1014 1015 killed: 1016 /* protects against exit_notify() and __exit_signal() */ 1017 read_lock(&tasklist_lock); 1018 sig->group_exit_task = NULL; 1019 sig->notify_count = 0; 1020 read_unlock(&tasklist_lock); 1021 return -EAGAIN; 1022 } 1023 1024 char *get_task_comm(char *buf, struct task_struct *tsk) 1025 { 1026 /* buf must be at least sizeof(tsk->comm) in size */ 1027 task_lock(tsk); 1028 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 1029 task_unlock(tsk); 1030 return buf; 1031 } 1032 EXPORT_SYMBOL_GPL(get_task_comm); 1033 1034 /* 1035 * These functions flushes out all traces of the currently running executable 1036 * so that a new one can be started 1037 */ 1038 1039 void set_task_comm(struct task_struct *tsk, char *buf) 1040 { 1041 task_lock(tsk); 1042 trace_task_rename(tsk, buf); 1043 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 1044 task_unlock(tsk); 1045 perf_event_comm(tsk); 1046 } 1047 1048 static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len) 1049 { 1050 int i, ch; 1051 1052 /* Copies the binary name from after last slash */ 1053 for (i = 0; (ch = *(fn++)) != '\0';) { 1054 if (ch == '/') 1055 i = 0; /* overwrite what we wrote */ 1056 else 1057 if (i < len - 1) 1058 tcomm[i++] = ch; 1059 } 1060 tcomm[i] = '\0'; 1061 } 1062 1063 int flush_old_exec(struct linux_binprm * bprm) 1064 { 1065 int retval; 1066 1067 /* 1068 * Make sure we have a private signal table and that 1069 * we are unassociated from the previous thread group. 1070 */ 1071 retval = de_thread(current); 1072 if (retval) 1073 goto out; 1074 1075 set_mm_exe_file(bprm->mm, bprm->file); 1076 1077 filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm)); 1078 /* 1079 * Release all of the old mmap stuff 1080 */ 1081 acct_arg_size(bprm, 0); 1082 retval = exec_mmap(bprm->mm); 1083 if (retval) 1084 goto out; 1085 1086 bprm->mm = NULL; /* We're using it now */ 1087 1088 set_fs(USER_DS); 1089 current->flags &= 1090 ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE); 1091 flush_thread(); 1092 current->personality &= ~bprm->per_clear; 1093 1094 return 0; 1095 1096 out: 1097 return retval; 1098 } 1099 EXPORT_SYMBOL(flush_old_exec); 1100 1101 void would_dump(struct linux_binprm *bprm, struct file *file) 1102 { 1103 if (inode_permission(file_inode(file), MAY_READ) < 0) 1104 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; 1105 } 1106 EXPORT_SYMBOL(would_dump); 1107 1108 void setup_new_exec(struct linux_binprm * bprm) 1109 { 1110 arch_pick_mmap_layout(current->mm); 1111 1112 /* This is the point of no return */ 1113 current->sas_ss_sp = current->sas_ss_size = 0; 1114 1115 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) 1116 set_dumpable(current->mm, SUID_DUMP_USER); 1117 else 1118 set_dumpable(current->mm, suid_dumpable); 1119 1120 set_task_comm(current, bprm->tcomm); 1121 1122 /* Set the new mm task size. We have to do that late because it may 1123 * depend on TIF_32BIT which is only updated in flush_thread() on 1124 * some architectures like powerpc 1125 */ 1126 current->mm->task_size = TASK_SIZE; 1127 1128 /* install the new credentials */ 1129 if (!uid_eq(bprm->cred->uid, current_euid()) || 1130 !gid_eq(bprm->cred->gid, current_egid())) { 1131 current->pdeath_signal = 0; 1132 } else { 1133 would_dump(bprm, bprm->file); 1134 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) 1135 set_dumpable(current->mm, suid_dumpable); 1136 } 1137 1138 /* An exec changes our domain. We are no longer part of the thread 1139 group */ 1140 1141 current->self_exec_id++; 1142 1143 flush_signal_handlers(current, 0); 1144 do_close_on_exec(current->files); 1145 } 1146 EXPORT_SYMBOL(setup_new_exec); 1147 1148 /* 1149 * Prepare credentials and lock ->cred_guard_mutex. 1150 * install_exec_creds() commits the new creds and drops the lock. 1151 * Or, if exec fails before, free_bprm() should release ->cred and 1152 * and unlock. 1153 */ 1154 int prepare_bprm_creds(struct linux_binprm *bprm) 1155 { 1156 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) 1157 return -ERESTARTNOINTR; 1158 1159 bprm->cred = prepare_exec_creds(); 1160 if (likely(bprm->cred)) 1161 return 0; 1162 1163 mutex_unlock(¤t->signal->cred_guard_mutex); 1164 return -ENOMEM; 1165 } 1166 1167 void free_bprm(struct linux_binprm *bprm) 1168 { 1169 free_arg_pages(bprm); 1170 if (bprm->cred) { 1171 mutex_unlock(¤t->signal->cred_guard_mutex); 1172 abort_creds(bprm->cred); 1173 } 1174 /* If a binfmt changed the interp, free it. */ 1175 if (bprm->interp != bprm->filename) 1176 kfree(bprm->interp); 1177 kfree(bprm); 1178 } 1179 1180 int bprm_change_interp(char *interp, struct linux_binprm *bprm) 1181 { 1182 /* If a binfmt changed the interp, free it first. */ 1183 if (bprm->interp != bprm->filename) 1184 kfree(bprm->interp); 1185 bprm->interp = kstrdup(interp, GFP_KERNEL); 1186 if (!bprm->interp) 1187 return -ENOMEM; 1188 return 0; 1189 } 1190 EXPORT_SYMBOL(bprm_change_interp); 1191 1192 /* 1193 * install the new credentials for this executable 1194 */ 1195 void install_exec_creds(struct linux_binprm *bprm) 1196 { 1197 security_bprm_committing_creds(bprm); 1198 1199 commit_creds(bprm->cred); 1200 bprm->cred = NULL; 1201 1202 /* 1203 * Disable monitoring for regular users 1204 * when executing setuid binaries. Must 1205 * wait until new credentials are committed 1206 * by commit_creds() above 1207 */ 1208 if (get_dumpable(current->mm) != SUID_DUMP_USER) 1209 perf_event_exit_task(current); 1210 /* 1211 * cred_guard_mutex must be held at least to this point to prevent 1212 * ptrace_attach() from altering our determination of the task's 1213 * credentials; any time after this it may be unlocked. 1214 */ 1215 security_bprm_committed_creds(bprm); 1216 mutex_unlock(¤t->signal->cred_guard_mutex); 1217 } 1218 EXPORT_SYMBOL(install_exec_creds); 1219 1220 /* 1221 * determine how safe it is to execute the proposed program 1222 * - the caller must hold ->cred_guard_mutex to protect against 1223 * PTRACE_ATTACH 1224 */ 1225 static int check_unsafe_exec(struct linux_binprm *bprm) 1226 { 1227 struct task_struct *p = current, *t; 1228 unsigned n_fs; 1229 int res = 0; 1230 1231 if (p->ptrace) { 1232 if (p->ptrace & PT_PTRACE_CAP) 1233 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; 1234 else 1235 bprm->unsafe |= LSM_UNSAFE_PTRACE; 1236 } 1237 1238 /* 1239 * This isn't strictly necessary, but it makes it harder for LSMs to 1240 * mess up. 1241 */ 1242 if (current->no_new_privs) 1243 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; 1244 1245 n_fs = 1; 1246 spin_lock(&p->fs->lock); 1247 rcu_read_lock(); 1248 for (t = next_thread(p); t != p; t = next_thread(t)) { 1249 if (t->fs == p->fs) 1250 n_fs++; 1251 } 1252 rcu_read_unlock(); 1253 1254 if (p->fs->users > n_fs) { 1255 bprm->unsafe |= LSM_UNSAFE_SHARE; 1256 } else { 1257 res = -EAGAIN; 1258 if (!p->fs->in_exec) { 1259 p->fs->in_exec = 1; 1260 res = 1; 1261 } 1262 } 1263 spin_unlock(&p->fs->lock); 1264 1265 return res; 1266 } 1267 1268 /* 1269 * Fill the binprm structure from the inode. 1270 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1271 * 1272 * This may be called multiple times for binary chains (scripts for example). 1273 */ 1274 int prepare_binprm(struct linux_binprm *bprm) 1275 { 1276 umode_t mode; 1277 struct inode * inode = file_inode(bprm->file); 1278 int retval; 1279 1280 mode = inode->i_mode; 1281 if (bprm->file->f_op == NULL) 1282 return -EACCES; 1283 1284 /* clear any previous set[ug]id data from a previous binary */ 1285 bprm->cred->euid = current_euid(); 1286 bprm->cred->egid = current_egid(); 1287 1288 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) && 1289 !current->no_new_privs && 1290 kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) && 1291 kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) { 1292 /* Set-uid? */ 1293 if (mode & S_ISUID) { 1294 bprm->per_clear |= PER_CLEAR_ON_SETID; 1295 bprm->cred->euid = inode->i_uid; 1296 } 1297 1298 /* Set-gid? */ 1299 /* 1300 * If setgid is set but no group execute bit then this 1301 * is a candidate for mandatory locking, not a setgid 1302 * executable. 1303 */ 1304 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1305 bprm->per_clear |= PER_CLEAR_ON_SETID; 1306 bprm->cred->egid = inode->i_gid; 1307 } 1308 } 1309 1310 /* fill in binprm security blob */ 1311 retval = security_bprm_set_creds(bprm); 1312 if (retval) 1313 return retval; 1314 bprm->cred_prepared = 1; 1315 1316 memset(bprm->buf, 0, BINPRM_BUF_SIZE); 1317 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); 1318 } 1319 1320 EXPORT_SYMBOL(prepare_binprm); 1321 1322 /* 1323 * Arguments are '\0' separated strings found at the location bprm->p 1324 * points to; chop off the first by relocating brpm->p to right after 1325 * the first '\0' encountered. 1326 */ 1327 int remove_arg_zero(struct linux_binprm *bprm) 1328 { 1329 int ret = 0; 1330 unsigned long offset; 1331 char *kaddr; 1332 struct page *page; 1333 1334 if (!bprm->argc) 1335 return 0; 1336 1337 do { 1338 offset = bprm->p & ~PAGE_MASK; 1339 page = get_arg_page(bprm, bprm->p, 0); 1340 if (!page) { 1341 ret = -EFAULT; 1342 goto out; 1343 } 1344 kaddr = kmap_atomic(page); 1345 1346 for (; offset < PAGE_SIZE && kaddr[offset]; 1347 offset++, bprm->p++) 1348 ; 1349 1350 kunmap_atomic(kaddr); 1351 put_arg_page(page); 1352 1353 if (offset == PAGE_SIZE) 1354 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1355 } while (offset == PAGE_SIZE); 1356 1357 bprm->p++; 1358 bprm->argc--; 1359 ret = 0; 1360 1361 out: 1362 return ret; 1363 } 1364 EXPORT_SYMBOL(remove_arg_zero); 1365 1366 /* 1367 * cycle the list of binary formats handler, until one recognizes the image 1368 */ 1369 int search_binary_handler(struct linux_binprm *bprm) 1370 { 1371 unsigned int depth = bprm->recursion_depth; 1372 int try,retval; 1373 struct linux_binfmt *fmt; 1374 pid_t old_pid, old_vpid; 1375 1376 /* This allows 4 levels of binfmt rewrites before failing hard. */ 1377 if (depth > 5) 1378 return -ELOOP; 1379 1380 retval = security_bprm_check(bprm); 1381 if (retval) 1382 return retval; 1383 1384 retval = audit_bprm(bprm); 1385 if (retval) 1386 return retval; 1387 1388 /* Need to fetch pid before load_binary changes it */ 1389 old_pid = current->pid; 1390 rcu_read_lock(); 1391 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); 1392 rcu_read_unlock(); 1393 1394 retval = -ENOENT; 1395 for (try=0; try<2; try++) { 1396 read_lock(&binfmt_lock); 1397 list_for_each_entry(fmt, &formats, lh) { 1398 int (*fn)(struct linux_binprm *) = fmt->load_binary; 1399 if (!fn) 1400 continue; 1401 if (!try_module_get(fmt->module)) 1402 continue; 1403 read_unlock(&binfmt_lock); 1404 bprm->recursion_depth = depth + 1; 1405 retval = fn(bprm); 1406 bprm->recursion_depth = depth; 1407 if (retval >= 0) { 1408 if (depth == 0) { 1409 trace_sched_process_exec(current, old_pid, bprm); 1410 ptrace_event(PTRACE_EVENT_EXEC, old_vpid); 1411 } 1412 put_binfmt(fmt); 1413 allow_write_access(bprm->file); 1414 if (bprm->file) 1415 fput(bprm->file); 1416 bprm->file = NULL; 1417 current->did_exec = 1; 1418 proc_exec_connector(current); 1419 return retval; 1420 } 1421 read_lock(&binfmt_lock); 1422 put_binfmt(fmt); 1423 if (retval != -ENOEXEC || bprm->mm == NULL) 1424 break; 1425 if (!bprm->file) { 1426 read_unlock(&binfmt_lock); 1427 return retval; 1428 } 1429 } 1430 read_unlock(&binfmt_lock); 1431 #ifdef CONFIG_MODULES 1432 if (retval != -ENOEXEC || bprm->mm == NULL) { 1433 break; 1434 } else { 1435 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1436 if (printable(bprm->buf[0]) && 1437 printable(bprm->buf[1]) && 1438 printable(bprm->buf[2]) && 1439 printable(bprm->buf[3])) 1440 break; /* -ENOEXEC */ 1441 if (try) 1442 break; /* -ENOEXEC */ 1443 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1444 } 1445 #else 1446 break; 1447 #endif 1448 } 1449 return retval; 1450 } 1451 1452 EXPORT_SYMBOL(search_binary_handler); 1453 1454 /* 1455 * sys_execve() executes a new program. 1456 */ 1457 static int do_execve_common(const char *filename, 1458 struct user_arg_ptr argv, 1459 struct user_arg_ptr envp) 1460 { 1461 struct linux_binprm *bprm; 1462 struct file *file; 1463 struct files_struct *displaced; 1464 bool clear_in_exec; 1465 int retval; 1466 const struct cred *cred = current_cred(); 1467 1468 /* 1469 * We move the actual failure in case of RLIMIT_NPROC excess from 1470 * set*uid() to execve() because too many poorly written programs 1471 * don't check setuid() return code. Here we additionally recheck 1472 * whether NPROC limit is still exceeded. 1473 */ 1474 if ((current->flags & PF_NPROC_EXCEEDED) && 1475 atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) { 1476 retval = -EAGAIN; 1477 goto out_ret; 1478 } 1479 1480 /* We're below the limit (still or again), so we don't want to make 1481 * further execve() calls fail. */ 1482 current->flags &= ~PF_NPROC_EXCEEDED; 1483 1484 retval = unshare_files(&displaced); 1485 if (retval) 1486 goto out_ret; 1487 1488 retval = -ENOMEM; 1489 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1490 if (!bprm) 1491 goto out_files; 1492 1493 retval = prepare_bprm_creds(bprm); 1494 if (retval) 1495 goto out_free; 1496 1497 retval = check_unsafe_exec(bprm); 1498 if (retval < 0) 1499 goto out_free; 1500 clear_in_exec = retval; 1501 current->in_execve = 1; 1502 1503 file = open_exec(filename); 1504 retval = PTR_ERR(file); 1505 if (IS_ERR(file)) 1506 goto out_unmark; 1507 1508 sched_exec(); 1509 1510 bprm->file = file; 1511 bprm->filename = filename; 1512 bprm->interp = filename; 1513 1514 retval = bprm_mm_init(bprm); 1515 if (retval) 1516 goto out_file; 1517 1518 bprm->argc = count(argv, MAX_ARG_STRINGS); 1519 if ((retval = bprm->argc) < 0) 1520 goto out; 1521 1522 bprm->envc = count(envp, MAX_ARG_STRINGS); 1523 if ((retval = bprm->envc) < 0) 1524 goto out; 1525 1526 retval = prepare_binprm(bprm); 1527 if (retval < 0) 1528 goto out; 1529 1530 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1531 if (retval < 0) 1532 goto out; 1533 1534 bprm->exec = bprm->p; 1535 retval = copy_strings(bprm->envc, envp, bprm); 1536 if (retval < 0) 1537 goto out; 1538 1539 retval = copy_strings(bprm->argc, argv, bprm); 1540 if (retval < 0) 1541 goto out; 1542 1543 retval = search_binary_handler(bprm); 1544 if (retval < 0) 1545 goto out; 1546 1547 /* execve succeeded */ 1548 current->fs->in_exec = 0; 1549 current->in_execve = 0; 1550 acct_update_integrals(current); 1551 free_bprm(bprm); 1552 if (displaced) 1553 put_files_struct(displaced); 1554 return retval; 1555 1556 out: 1557 if (bprm->mm) { 1558 acct_arg_size(bprm, 0); 1559 mmput(bprm->mm); 1560 } 1561 1562 out_file: 1563 if (bprm->file) { 1564 allow_write_access(bprm->file); 1565 fput(bprm->file); 1566 } 1567 1568 out_unmark: 1569 if (clear_in_exec) 1570 current->fs->in_exec = 0; 1571 current->in_execve = 0; 1572 1573 out_free: 1574 free_bprm(bprm); 1575 1576 out_files: 1577 if (displaced) 1578 reset_files_struct(displaced); 1579 out_ret: 1580 return retval; 1581 } 1582 1583 int do_execve(const char *filename, 1584 const char __user *const __user *__argv, 1585 const char __user *const __user *__envp) 1586 { 1587 struct user_arg_ptr argv = { .ptr.native = __argv }; 1588 struct user_arg_ptr envp = { .ptr.native = __envp }; 1589 return do_execve_common(filename, argv, envp); 1590 } 1591 1592 #ifdef CONFIG_COMPAT 1593 static int compat_do_execve(const char *filename, 1594 const compat_uptr_t __user *__argv, 1595 const compat_uptr_t __user *__envp) 1596 { 1597 struct user_arg_ptr argv = { 1598 .is_compat = true, 1599 .ptr.compat = __argv, 1600 }; 1601 struct user_arg_ptr envp = { 1602 .is_compat = true, 1603 .ptr.compat = __envp, 1604 }; 1605 return do_execve_common(filename, argv, envp); 1606 } 1607 #endif 1608 1609 void set_binfmt(struct linux_binfmt *new) 1610 { 1611 struct mm_struct *mm = current->mm; 1612 1613 if (mm->binfmt) 1614 module_put(mm->binfmt->module); 1615 1616 mm->binfmt = new; 1617 if (new) 1618 __module_get(new->module); 1619 } 1620 1621 EXPORT_SYMBOL(set_binfmt); 1622 1623 /* 1624 * set_dumpable converts traditional three-value dumpable to two flags and 1625 * stores them into mm->flags. It modifies lower two bits of mm->flags, but 1626 * these bits are not changed atomically. So get_dumpable can observe the 1627 * intermediate state. To avoid doing unexpected behavior, get get_dumpable 1628 * return either old dumpable or new one by paying attention to the order of 1629 * modifying the bits. 1630 * 1631 * dumpable | mm->flags (binary) 1632 * old new | initial interim final 1633 * ---------+----------------------- 1634 * 0 1 | 00 01 01 1635 * 0 2 | 00 10(*) 11 1636 * 1 0 | 01 00 00 1637 * 1 2 | 01 11 11 1638 * 2 0 | 11 10(*) 00 1639 * 2 1 | 11 11 01 1640 * 1641 * (*) get_dumpable regards interim value of 10 as 11. 1642 */ 1643 void set_dumpable(struct mm_struct *mm, int value) 1644 { 1645 switch (value) { 1646 case SUID_DUMP_DISABLE: 1647 clear_bit(MMF_DUMPABLE, &mm->flags); 1648 smp_wmb(); 1649 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1650 break; 1651 case SUID_DUMP_USER: 1652 set_bit(MMF_DUMPABLE, &mm->flags); 1653 smp_wmb(); 1654 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1655 break; 1656 case SUID_DUMP_ROOT: 1657 set_bit(MMF_DUMP_SECURELY, &mm->flags); 1658 smp_wmb(); 1659 set_bit(MMF_DUMPABLE, &mm->flags); 1660 break; 1661 } 1662 } 1663 1664 int __get_dumpable(unsigned long mm_flags) 1665 { 1666 int ret; 1667 1668 ret = mm_flags & MMF_DUMPABLE_MASK; 1669 return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret; 1670 } 1671 1672 int get_dumpable(struct mm_struct *mm) 1673 { 1674 return __get_dumpable(mm->flags); 1675 } 1676 1677 SYSCALL_DEFINE3(execve, 1678 const char __user *, filename, 1679 const char __user *const __user *, argv, 1680 const char __user *const __user *, envp) 1681 { 1682 struct filename *path = getname(filename); 1683 int error = PTR_ERR(path); 1684 if (!IS_ERR(path)) { 1685 error = do_execve(path->name, argv, envp); 1686 putname(path); 1687 } 1688 return error; 1689 } 1690 #ifdef CONFIG_COMPAT 1691 asmlinkage long compat_sys_execve(const char __user * filename, 1692 const compat_uptr_t __user * argv, 1693 const compat_uptr_t __user * envp) 1694 { 1695 struct filename *path = getname(filename); 1696 int error = PTR_ERR(path); 1697 if (!IS_ERR(path)) { 1698 error = compat_do_execve(path->name, argv, envp); 1699 putname(path); 1700 } 1701 return error; 1702 } 1703 #endif 1704