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 if (WARN_ON(!fmt->load_binary)) 78 return; 79 write_lock(&binfmt_lock); 80 insert ? list_add(&fmt->lh, &formats) : 81 list_add_tail(&fmt->lh, &formats); 82 write_unlock(&binfmt_lock); 83 } 84 85 EXPORT_SYMBOL(__register_binfmt); 86 87 void unregister_binfmt(struct linux_binfmt * fmt) 88 { 89 write_lock(&binfmt_lock); 90 list_del(&fmt->lh); 91 write_unlock(&binfmt_lock); 92 } 93 94 EXPORT_SYMBOL(unregister_binfmt); 95 96 static inline void put_binfmt(struct linux_binfmt * fmt) 97 { 98 module_put(fmt->module); 99 } 100 101 /* 102 * Note that a shared library must be both readable and executable due to 103 * security reasons. 104 * 105 * Also note that we take the address to load from from the file itself. 106 */ 107 SYSCALL_DEFINE1(uselib, const char __user *, library) 108 { 109 struct file *file; 110 struct filename *tmp = getname(library); 111 int error = PTR_ERR(tmp); 112 static const struct open_flags uselib_flags = { 113 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 114 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, 115 .intent = LOOKUP_OPEN, 116 .lookup_flags = LOOKUP_FOLLOW, 117 }; 118 119 if (IS_ERR(tmp)) 120 goto out; 121 122 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags); 123 putname(tmp); 124 error = PTR_ERR(file); 125 if (IS_ERR(file)) 126 goto out; 127 128 error = -EINVAL; 129 if (!S_ISREG(file_inode(file)->i_mode)) 130 goto exit; 131 132 error = -EACCES; 133 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 134 goto exit; 135 136 fsnotify_open(file); 137 138 error = -ENOEXEC; 139 if(file->f_op) { 140 struct linux_binfmt * fmt; 141 142 read_lock(&binfmt_lock); 143 list_for_each_entry(fmt, &formats, lh) { 144 if (!fmt->load_shlib) 145 continue; 146 if (!try_module_get(fmt->module)) 147 continue; 148 read_unlock(&binfmt_lock); 149 error = fmt->load_shlib(file); 150 read_lock(&binfmt_lock); 151 put_binfmt(fmt); 152 if (error != -ENOEXEC) 153 break; 154 } 155 read_unlock(&binfmt_lock); 156 } 157 exit: 158 fput(file); 159 out: 160 return error; 161 } 162 163 #ifdef CONFIG_MMU 164 /* 165 * The nascent bprm->mm is not visible until exec_mmap() but it can 166 * use a lot of memory, account these pages in current->mm temporary 167 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we 168 * change the counter back via acct_arg_size(0). 169 */ 170 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 171 { 172 struct mm_struct *mm = current->mm; 173 long diff = (long)(pages - bprm->vma_pages); 174 175 if (!mm || !diff) 176 return; 177 178 bprm->vma_pages = pages; 179 add_mm_counter(mm, MM_ANONPAGES, diff); 180 } 181 182 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 183 int write) 184 { 185 struct page *page; 186 int ret; 187 188 #ifdef CONFIG_STACK_GROWSUP 189 if (write) { 190 ret = expand_downwards(bprm->vma, pos); 191 if (ret < 0) 192 return NULL; 193 } 194 #endif 195 ret = get_user_pages(current, bprm->mm, pos, 196 1, write, 1, &page, NULL); 197 if (ret <= 0) 198 return NULL; 199 200 if (write) { 201 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; 202 struct rlimit *rlim; 203 204 acct_arg_size(bprm, size / PAGE_SIZE); 205 206 /* 207 * We've historically supported up to 32 pages (ARG_MAX) 208 * of argument strings even with small stacks 209 */ 210 if (size <= ARG_MAX) 211 return page; 212 213 /* 214 * Limit to 1/4-th the stack size for the argv+env strings. 215 * This ensures that: 216 * - the remaining binfmt code will not run out of stack space, 217 * - the program will have a reasonable amount of stack left 218 * to work from. 219 */ 220 rlim = current->signal->rlim; 221 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { 222 put_page(page); 223 return NULL; 224 } 225 } 226 227 return page; 228 } 229 230 static void put_arg_page(struct page *page) 231 { 232 put_page(page); 233 } 234 235 static void free_arg_page(struct linux_binprm *bprm, int i) 236 { 237 } 238 239 static void free_arg_pages(struct linux_binprm *bprm) 240 { 241 } 242 243 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 244 struct page *page) 245 { 246 flush_cache_page(bprm->vma, pos, page_to_pfn(page)); 247 } 248 249 static int __bprm_mm_init(struct linux_binprm *bprm) 250 { 251 int err; 252 struct vm_area_struct *vma = NULL; 253 struct mm_struct *mm = bprm->mm; 254 255 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 256 if (!vma) 257 return -ENOMEM; 258 259 down_write(&mm->mmap_sem); 260 vma->vm_mm = mm; 261 262 /* 263 * Place the stack at the largest stack address the architecture 264 * supports. Later, we'll move this to an appropriate place. We don't 265 * use STACK_TOP because that can depend on attributes which aren't 266 * configured yet. 267 */ 268 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); 269 vma->vm_end = STACK_TOP_MAX; 270 vma->vm_start = vma->vm_end - PAGE_SIZE; 271 vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; 272 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 273 INIT_LIST_HEAD(&vma->anon_vma_chain); 274 275 err = insert_vm_struct(mm, vma); 276 if (err) 277 goto err; 278 279 mm->stack_vm = mm->total_vm = 1; 280 up_write(&mm->mmap_sem); 281 bprm->p = vma->vm_end - sizeof(void *); 282 return 0; 283 err: 284 up_write(&mm->mmap_sem); 285 bprm->vma = NULL; 286 kmem_cache_free(vm_area_cachep, vma); 287 return err; 288 } 289 290 static bool valid_arg_len(struct linux_binprm *bprm, long len) 291 { 292 return len <= MAX_ARG_STRLEN; 293 } 294 295 #else 296 297 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 298 { 299 } 300 301 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 302 int write) 303 { 304 struct page *page; 305 306 page = bprm->page[pos / PAGE_SIZE]; 307 if (!page && write) { 308 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 309 if (!page) 310 return NULL; 311 bprm->page[pos / PAGE_SIZE] = page; 312 } 313 314 return page; 315 } 316 317 static void put_arg_page(struct page *page) 318 { 319 } 320 321 static void free_arg_page(struct linux_binprm *bprm, int i) 322 { 323 if (bprm->page[i]) { 324 __free_page(bprm->page[i]); 325 bprm->page[i] = NULL; 326 } 327 } 328 329 static void free_arg_pages(struct linux_binprm *bprm) 330 { 331 int i; 332 333 for (i = 0; i < MAX_ARG_PAGES; i++) 334 free_arg_page(bprm, i); 335 } 336 337 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 338 struct page *page) 339 { 340 } 341 342 static int __bprm_mm_init(struct linux_binprm *bprm) 343 { 344 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 345 return 0; 346 } 347 348 static bool valid_arg_len(struct linux_binprm *bprm, long len) 349 { 350 return len <= bprm->p; 351 } 352 353 #endif /* CONFIG_MMU */ 354 355 /* 356 * Create a new mm_struct and populate it with a temporary stack 357 * vm_area_struct. We don't have enough context at this point to set the stack 358 * flags, permissions, and offset, so we use temporary values. We'll update 359 * them later in setup_arg_pages(). 360 */ 361 static int bprm_mm_init(struct linux_binprm *bprm) 362 { 363 int err; 364 struct mm_struct *mm = NULL; 365 366 bprm->mm = mm = mm_alloc(); 367 err = -ENOMEM; 368 if (!mm) 369 goto err; 370 371 err = init_new_context(current, mm); 372 if (err) 373 goto err; 374 375 err = __bprm_mm_init(bprm); 376 if (err) 377 goto err; 378 379 return 0; 380 381 err: 382 if (mm) { 383 bprm->mm = NULL; 384 mmdrop(mm); 385 } 386 387 return err; 388 } 389 390 struct user_arg_ptr { 391 #ifdef CONFIG_COMPAT 392 bool is_compat; 393 #endif 394 union { 395 const char __user *const __user *native; 396 #ifdef CONFIG_COMPAT 397 const compat_uptr_t __user *compat; 398 #endif 399 } ptr; 400 }; 401 402 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) 403 { 404 const char __user *native; 405 406 #ifdef CONFIG_COMPAT 407 if (unlikely(argv.is_compat)) { 408 compat_uptr_t compat; 409 410 if (get_user(compat, argv.ptr.compat + nr)) 411 return ERR_PTR(-EFAULT); 412 413 return compat_ptr(compat); 414 } 415 #endif 416 417 if (get_user(native, argv.ptr.native + nr)) 418 return ERR_PTR(-EFAULT); 419 420 return native; 421 } 422 423 /* 424 * count() counts the number of strings in array ARGV. 425 */ 426 static int count(struct user_arg_ptr argv, int max) 427 { 428 int i = 0; 429 430 if (argv.ptr.native != NULL) { 431 for (;;) { 432 const char __user *p = get_user_arg_ptr(argv, i); 433 434 if (!p) 435 break; 436 437 if (IS_ERR(p)) 438 return -EFAULT; 439 440 if (i >= max) 441 return -E2BIG; 442 ++i; 443 444 if (fatal_signal_pending(current)) 445 return -ERESTARTNOHAND; 446 cond_resched(); 447 } 448 } 449 return i; 450 } 451 452 /* 453 * 'copy_strings()' copies argument/environment strings from the old 454 * processes's memory to the new process's stack. The call to get_user_pages() 455 * ensures the destination page is created and not swapped out. 456 */ 457 static int copy_strings(int argc, struct user_arg_ptr argv, 458 struct linux_binprm *bprm) 459 { 460 struct page *kmapped_page = NULL; 461 char *kaddr = NULL; 462 unsigned long kpos = 0; 463 int ret; 464 465 while (argc-- > 0) { 466 const char __user *str; 467 int len; 468 unsigned long pos; 469 470 ret = -EFAULT; 471 str = get_user_arg_ptr(argv, argc); 472 if (IS_ERR(str)) 473 goto out; 474 475 len = strnlen_user(str, MAX_ARG_STRLEN); 476 if (!len) 477 goto out; 478 479 ret = -E2BIG; 480 if (!valid_arg_len(bprm, len)) 481 goto out; 482 483 /* We're going to work our way backwords. */ 484 pos = bprm->p; 485 str += len; 486 bprm->p -= len; 487 488 while (len > 0) { 489 int offset, bytes_to_copy; 490 491 if (fatal_signal_pending(current)) { 492 ret = -ERESTARTNOHAND; 493 goto out; 494 } 495 cond_resched(); 496 497 offset = pos % PAGE_SIZE; 498 if (offset == 0) 499 offset = PAGE_SIZE; 500 501 bytes_to_copy = offset; 502 if (bytes_to_copy > len) 503 bytes_to_copy = len; 504 505 offset -= bytes_to_copy; 506 pos -= bytes_to_copy; 507 str -= bytes_to_copy; 508 len -= bytes_to_copy; 509 510 if (!kmapped_page || kpos != (pos & PAGE_MASK)) { 511 struct page *page; 512 513 page = get_arg_page(bprm, pos, 1); 514 if (!page) { 515 ret = -E2BIG; 516 goto out; 517 } 518 519 if (kmapped_page) { 520 flush_kernel_dcache_page(kmapped_page); 521 kunmap(kmapped_page); 522 put_arg_page(kmapped_page); 523 } 524 kmapped_page = page; 525 kaddr = kmap(kmapped_page); 526 kpos = pos & PAGE_MASK; 527 flush_arg_page(bprm, kpos, kmapped_page); 528 } 529 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { 530 ret = -EFAULT; 531 goto out; 532 } 533 } 534 } 535 ret = 0; 536 out: 537 if (kmapped_page) { 538 flush_kernel_dcache_page(kmapped_page); 539 kunmap(kmapped_page); 540 put_arg_page(kmapped_page); 541 } 542 return ret; 543 } 544 545 /* 546 * Like copy_strings, but get argv and its values from kernel memory. 547 */ 548 int copy_strings_kernel(int argc, const char *const *__argv, 549 struct linux_binprm *bprm) 550 { 551 int r; 552 mm_segment_t oldfs = get_fs(); 553 struct user_arg_ptr argv = { 554 .ptr.native = (const char __user *const __user *)__argv, 555 }; 556 557 set_fs(KERNEL_DS); 558 r = copy_strings(argc, argv, bprm); 559 set_fs(oldfs); 560 561 return r; 562 } 563 EXPORT_SYMBOL(copy_strings_kernel); 564 565 #ifdef CONFIG_MMU 566 567 /* 568 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once 569 * the binfmt code determines where the new stack should reside, we shift it to 570 * its final location. The process proceeds as follows: 571 * 572 * 1) Use shift to calculate the new vma endpoints. 573 * 2) Extend vma to cover both the old and new ranges. This ensures the 574 * arguments passed to subsequent functions are consistent. 575 * 3) Move vma's page tables to the new range. 576 * 4) Free up any cleared pgd range. 577 * 5) Shrink the vma to cover only the new range. 578 */ 579 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) 580 { 581 struct mm_struct *mm = vma->vm_mm; 582 unsigned long old_start = vma->vm_start; 583 unsigned long old_end = vma->vm_end; 584 unsigned long length = old_end - old_start; 585 unsigned long new_start = old_start - shift; 586 unsigned long new_end = old_end - shift; 587 struct mmu_gather tlb; 588 589 BUG_ON(new_start > new_end); 590 591 /* 592 * ensure there are no vmas between where we want to go 593 * and where we are 594 */ 595 if (vma != find_vma(mm, new_start)) 596 return -EFAULT; 597 598 /* 599 * cover the whole range: [new_start, old_end) 600 */ 601 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) 602 return -ENOMEM; 603 604 /* 605 * move the page tables downwards, on failure we rely on 606 * process cleanup to remove whatever mess we made. 607 */ 608 if (length != move_page_tables(vma, old_start, 609 vma, new_start, length, false)) 610 return -ENOMEM; 611 612 lru_add_drain(); 613 tlb_gather_mmu(&tlb, mm, old_start, old_end); 614 if (new_end > old_start) { 615 /* 616 * when the old and new regions overlap clear from new_end. 617 */ 618 free_pgd_range(&tlb, new_end, old_end, new_end, 619 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); 620 } else { 621 /* 622 * otherwise, clean from old_start; this is done to not touch 623 * the address space in [new_end, old_start) some architectures 624 * have constraints on va-space that make this illegal (IA64) - 625 * for the others its just a little faster. 626 */ 627 free_pgd_range(&tlb, old_start, old_end, new_end, 628 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); 629 } 630 tlb_finish_mmu(&tlb, old_start, old_end); 631 632 /* 633 * Shrink the vma to just the new range. Always succeeds. 634 */ 635 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); 636 637 return 0; 638 } 639 640 /* 641 * Finalizes the stack vm_area_struct. The flags and permissions are updated, 642 * the stack is optionally relocated, and some extra space is added. 643 */ 644 int setup_arg_pages(struct linux_binprm *bprm, 645 unsigned long stack_top, 646 int executable_stack) 647 { 648 unsigned long ret; 649 unsigned long stack_shift; 650 struct mm_struct *mm = current->mm; 651 struct vm_area_struct *vma = bprm->vma; 652 struct vm_area_struct *prev = NULL; 653 unsigned long vm_flags; 654 unsigned long stack_base; 655 unsigned long stack_size; 656 unsigned long stack_expand; 657 unsigned long rlim_stack; 658 659 #ifdef CONFIG_STACK_GROWSUP 660 /* Limit stack size to 1GB */ 661 stack_base = rlimit_max(RLIMIT_STACK); 662 if (stack_base > (1 << 30)) 663 stack_base = 1 << 30; 664 665 /* Make sure we didn't let the argument array grow too large. */ 666 if (vma->vm_end - vma->vm_start > stack_base) 667 return -ENOMEM; 668 669 stack_base = PAGE_ALIGN(stack_top - stack_base); 670 671 stack_shift = vma->vm_start - stack_base; 672 mm->arg_start = bprm->p - stack_shift; 673 bprm->p = vma->vm_end - stack_shift; 674 #else 675 stack_top = arch_align_stack(stack_top); 676 stack_top = PAGE_ALIGN(stack_top); 677 678 if (unlikely(stack_top < mmap_min_addr) || 679 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) 680 return -ENOMEM; 681 682 stack_shift = vma->vm_end - stack_top; 683 684 bprm->p -= stack_shift; 685 mm->arg_start = bprm->p; 686 #endif 687 688 if (bprm->loader) 689 bprm->loader -= stack_shift; 690 bprm->exec -= stack_shift; 691 692 down_write(&mm->mmap_sem); 693 vm_flags = VM_STACK_FLAGS; 694 695 /* 696 * Adjust stack execute permissions; explicitly enable for 697 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone 698 * (arch default) otherwise. 699 */ 700 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 701 vm_flags |= VM_EXEC; 702 else if (executable_stack == EXSTACK_DISABLE_X) 703 vm_flags &= ~VM_EXEC; 704 vm_flags |= mm->def_flags; 705 vm_flags |= VM_STACK_INCOMPLETE_SETUP; 706 707 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, 708 vm_flags); 709 if (ret) 710 goto out_unlock; 711 BUG_ON(prev != vma); 712 713 /* Move stack pages down in memory. */ 714 if (stack_shift) { 715 ret = shift_arg_pages(vma, stack_shift); 716 if (ret) 717 goto out_unlock; 718 } 719 720 /* mprotect_fixup is overkill to remove the temporary stack flags */ 721 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; 722 723 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ 724 stack_size = vma->vm_end - vma->vm_start; 725 /* 726 * Align this down to a page boundary as expand_stack 727 * will align it up. 728 */ 729 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; 730 #ifdef CONFIG_STACK_GROWSUP 731 if (stack_size + stack_expand > rlim_stack) 732 stack_base = vma->vm_start + rlim_stack; 733 else 734 stack_base = vma->vm_end + stack_expand; 735 #else 736 if (stack_size + stack_expand > rlim_stack) 737 stack_base = vma->vm_end - rlim_stack; 738 else 739 stack_base = vma->vm_start - stack_expand; 740 #endif 741 current->mm->start_stack = bprm->p; 742 ret = expand_stack(vma, stack_base); 743 if (ret) 744 ret = -EFAULT; 745 746 out_unlock: 747 up_write(&mm->mmap_sem); 748 return ret; 749 } 750 EXPORT_SYMBOL(setup_arg_pages); 751 752 #endif /* CONFIG_MMU */ 753 754 struct file *open_exec(const char *name) 755 { 756 struct file *file; 757 int err; 758 struct filename tmp = { .name = name }; 759 static const struct open_flags open_exec_flags = { 760 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 761 .acc_mode = MAY_EXEC | MAY_OPEN, 762 .intent = LOOKUP_OPEN, 763 .lookup_flags = LOOKUP_FOLLOW, 764 }; 765 766 file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags); 767 if (IS_ERR(file)) 768 goto out; 769 770 err = -EACCES; 771 if (!S_ISREG(file_inode(file)->i_mode)) 772 goto exit; 773 774 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 775 goto exit; 776 777 fsnotify_open(file); 778 779 err = deny_write_access(file); 780 if (err) 781 goto exit; 782 783 out: 784 return file; 785 786 exit: 787 fput(file); 788 return ERR_PTR(err); 789 } 790 EXPORT_SYMBOL(open_exec); 791 792 int kernel_read(struct file *file, loff_t offset, 793 char *addr, unsigned long count) 794 { 795 mm_segment_t old_fs; 796 loff_t pos = offset; 797 int result; 798 799 old_fs = get_fs(); 800 set_fs(get_ds()); 801 /* The cast to a user pointer is valid due to the set_fs() */ 802 result = vfs_read(file, (void __user *)addr, count, &pos); 803 set_fs(old_fs); 804 return result; 805 } 806 807 EXPORT_SYMBOL(kernel_read); 808 809 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len) 810 { 811 ssize_t res = file->f_op->read(file, (void __user *)addr, len, &pos); 812 if (res > 0) 813 flush_icache_range(addr, addr + len); 814 return res; 815 } 816 EXPORT_SYMBOL(read_code); 817 818 static int exec_mmap(struct mm_struct *mm) 819 { 820 struct task_struct *tsk; 821 struct mm_struct * old_mm, *active_mm; 822 823 /* Notify parent that we're no longer interested in the old VM */ 824 tsk = current; 825 old_mm = current->mm; 826 mm_release(tsk, old_mm); 827 828 if (old_mm) { 829 sync_mm_rss(old_mm); 830 /* 831 * Make sure that if there is a core dump in progress 832 * for the old mm, we get out and die instead of going 833 * through with the exec. We must hold mmap_sem around 834 * checking core_state and changing tsk->mm. 835 */ 836 down_read(&old_mm->mmap_sem); 837 if (unlikely(old_mm->core_state)) { 838 up_read(&old_mm->mmap_sem); 839 return -EINTR; 840 } 841 } 842 task_lock(tsk); 843 active_mm = tsk->active_mm; 844 tsk->mm = mm; 845 tsk->active_mm = mm; 846 activate_mm(active_mm, mm); 847 task_unlock(tsk); 848 arch_pick_mmap_layout(mm); 849 if (old_mm) { 850 up_read(&old_mm->mmap_sem); 851 BUG_ON(active_mm != old_mm); 852 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); 853 mm_update_next_owner(old_mm); 854 mmput(old_mm); 855 return 0; 856 } 857 mmdrop(active_mm); 858 return 0; 859 } 860 861 /* 862 * This function makes sure the current process has its own signal table, 863 * so that flush_signal_handlers can later reset the handlers without 864 * disturbing other processes. (Other processes might share the signal 865 * table via the CLONE_SIGHAND option to clone().) 866 */ 867 static int de_thread(struct task_struct *tsk) 868 { 869 struct signal_struct *sig = tsk->signal; 870 struct sighand_struct *oldsighand = tsk->sighand; 871 spinlock_t *lock = &oldsighand->siglock; 872 873 if (thread_group_empty(tsk)) 874 goto no_thread_group; 875 876 /* 877 * Kill all other threads in the thread group. 878 */ 879 spin_lock_irq(lock); 880 if (signal_group_exit(sig)) { 881 /* 882 * Another group action in progress, just 883 * return so that the signal is processed. 884 */ 885 spin_unlock_irq(lock); 886 return -EAGAIN; 887 } 888 889 sig->group_exit_task = tsk; 890 sig->notify_count = zap_other_threads(tsk); 891 if (!thread_group_leader(tsk)) 892 sig->notify_count--; 893 894 while (sig->notify_count) { 895 __set_current_state(TASK_KILLABLE); 896 spin_unlock_irq(lock); 897 schedule(); 898 if (unlikely(__fatal_signal_pending(tsk))) 899 goto killed; 900 spin_lock_irq(lock); 901 } 902 spin_unlock_irq(lock); 903 904 /* 905 * At this point all other threads have exited, all we have to 906 * do is to wait for the thread group leader to become inactive, 907 * and to assume its PID: 908 */ 909 if (!thread_group_leader(tsk)) { 910 struct task_struct *leader = tsk->group_leader; 911 912 sig->notify_count = -1; /* for exit_notify() */ 913 for (;;) { 914 threadgroup_change_begin(tsk); 915 write_lock_irq(&tasklist_lock); 916 if (likely(leader->exit_state)) 917 break; 918 __set_current_state(TASK_KILLABLE); 919 write_unlock_irq(&tasklist_lock); 920 threadgroup_change_end(tsk); 921 schedule(); 922 if (unlikely(__fatal_signal_pending(tsk))) 923 goto killed; 924 } 925 926 /* 927 * The only record we have of the real-time age of a 928 * process, regardless of execs it's done, is start_time. 929 * All the past CPU time is accumulated in signal_struct 930 * from sister threads now dead. But in this non-leader 931 * exec, nothing survives from the original leader thread, 932 * whose birth marks the true age of this process now. 933 * When we take on its identity by switching to its PID, we 934 * also take its birthdate (always earlier than our own). 935 */ 936 tsk->start_time = leader->start_time; 937 tsk->real_start_time = leader->real_start_time; 938 939 BUG_ON(!same_thread_group(leader, tsk)); 940 BUG_ON(has_group_leader_pid(tsk)); 941 /* 942 * An exec() starts a new thread group with the 943 * TGID of the previous thread group. Rehash the 944 * two threads with a switched PID, and release 945 * the former thread group leader: 946 */ 947 948 /* Become a process group leader with the old leader's pid. 949 * The old leader becomes a thread of the this thread group. 950 * Note: The old leader also uses this pid until release_task 951 * is called. Odd but simple and correct. 952 */ 953 tsk->pid = leader->pid; 954 change_pid(tsk, PIDTYPE_PID, task_pid(leader)); 955 transfer_pid(leader, tsk, PIDTYPE_PGID); 956 transfer_pid(leader, tsk, PIDTYPE_SID); 957 958 list_replace_rcu(&leader->tasks, &tsk->tasks); 959 list_replace_init(&leader->sibling, &tsk->sibling); 960 961 tsk->group_leader = tsk; 962 leader->group_leader = tsk; 963 964 tsk->exit_signal = SIGCHLD; 965 leader->exit_signal = -1; 966 967 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 968 leader->exit_state = EXIT_DEAD; 969 970 /* 971 * We are going to release_task()->ptrace_unlink() silently, 972 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees 973 * the tracer wont't block again waiting for this thread. 974 */ 975 if (unlikely(leader->ptrace)) 976 __wake_up_parent(leader, leader->parent); 977 write_unlock_irq(&tasklist_lock); 978 threadgroup_change_end(tsk); 979 980 release_task(leader); 981 } 982 983 sig->group_exit_task = NULL; 984 sig->notify_count = 0; 985 986 no_thread_group: 987 /* we have changed execution domain */ 988 tsk->exit_signal = SIGCHLD; 989 990 exit_itimers(sig); 991 flush_itimer_signals(); 992 993 if (atomic_read(&oldsighand->count) != 1) { 994 struct sighand_struct *newsighand; 995 /* 996 * This ->sighand is shared with the CLONE_SIGHAND 997 * but not CLONE_THREAD task, switch to the new one. 998 */ 999 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 1000 if (!newsighand) 1001 return -ENOMEM; 1002 1003 atomic_set(&newsighand->count, 1); 1004 memcpy(newsighand->action, oldsighand->action, 1005 sizeof(newsighand->action)); 1006 1007 write_lock_irq(&tasklist_lock); 1008 spin_lock(&oldsighand->siglock); 1009 rcu_assign_pointer(tsk->sighand, newsighand); 1010 spin_unlock(&oldsighand->siglock); 1011 write_unlock_irq(&tasklist_lock); 1012 1013 __cleanup_sighand(oldsighand); 1014 } 1015 1016 BUG_ON(!thread_group_leader(tsk)); 1017 return 0; 1018 1019 killed: 1020 /* protects against exit_notify() and __exit_signal() */ 1021 read_lock(&tasklist_lock); 1022 sig->group_exit_task = NULL; 1023 sig->notify_count = 0; 1024 read_unlock(&tasklist_lock); 1025 return -EAGAIN; 1026 } 1027 1028 char *get_task_comm(char *buf, struct task_struct *tsk) 1029 { 1030 /* buf must be at least sizeof(tsk->comm) in size */ 1031 task_lock(tsk); 1032 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 1033 task_unlock(tsk); 1034 return buf; 1035 } 1036 EXPORT_SYMBOL_GPL(get_task_comm); 1037 1038 /* 1039 * These functions flushes out all traces of the currently running executable 1040 * so that a new one can be started 1041 */ 1042 1043 void set_task_comm(struct task_struct *tsk, char *buf) 1044 { 1045 task_lock(tsk); 1046 trace_task_rename(tsk, buf); 1047 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 1048 task_unlock(tsk); 1049 perf_event_comm(tsk); 1050 } 1051 1052 static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len) 1053 { 1054 int i, ch; 1055 1056 /* Copies the binary name from after last slash */ 1057 for (i = 0; (ch = *(fn++)) != '\0';) { 1058 if (ch == '/') 1059 i = 0; /* overwrite what we wrote */ 1060 else 1061 if (i < len - 1) 1062 tcomm[i++] = ch; 1063 } 1064 tcomm[i] = '\0'; 1065 } 1066 1067 int flush_old_exec(struct linux_binprm * bprm) 1068 { 1069 int retval; 1070 1071 /* 1072 * Make sure we have a private signal table and that 1073 * we are unassociated from the previous thread group. 1074 */ 1075 retval = de_thread(current); 1076 if (retval) 1077 goto out; 1078 1079 set_mm_exe_file(bprm->mm, bprm->file); 1080 1081 filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm)); 1082 /* 1083 * Release all of the old mmap stuff 1084 */ 1085 acct_arg_size(bprm, 0); 1086 retval = exec_mmap(bprm->mm); 1087 if (retval) 1088 goto out; 1089 1090 bprm->mm = NULL; /* We're using it now */ 1091 1092 set_fs(USER_DS); 1093 current->flags &= 1094 ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE); 1095 flush_thread(); 1096 current->personality &= ~bprm->per_clear; 1097 1098 return 0; 1099 1100 out: 1101 return retval; 1102 } 1103 EXPORT_SYMBOL(flush_old_exec); 1104 1105 void would_dump(struct linux_binprm *bprm, struct file *file) 1106 { 1107 if (inode_permission(file_inode(file), MAY_READ) < 0) 1108 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; 1109 } 1110 EXPORT_SYMBOL(would_dump); 1111 1112 void setup_new_exec(struct linux_binprm * bprm) 1113 { 1114 arch_pick_mmap_layout(current->mm); 1115 1116 /* This is the point of no return */ 1117 current->sas_ss_sp = current->sas_ss_size = 0; 1118 1119 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) 1120 set_dumpable(current->mm, SUID_DUMP_USER); 1121 else 1122 set_dumpable(current->mm, suid_dumpable); 1123 1124 set_task_comm(current, bprm->tcomm); 1125 1126 /* Set the new mm task size. We have to do that late because it may 1127 * depend on TIF_32BIT which is only updated in flush_thread() on 1128 * some architectures like powerpc 1129 */ 1130 current->mm->task_size = TASK_SIZE; 1131 1132 /* install the new credentials */ 1133 if (!uid_eq(bprm->cred->uid, current_euid()) || 1134 !gid_eq(bprm->cred->gid, current_egid())) { 1135 current->pdeath_signal = 0; 1136 } else { 1137 would_dump(bprm, bprm->file); 1138 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) 1139 set_dumpable(current->mm, suid_dumpable); 1140 } 1141 1142 /* An exec changes our domain. We are no longer part of the thread 1143 group */ 1144 1145 current->self_exec_id++; 1146 1147 flush_signal_handlers(current, 0); 1148 do_close_on_exec(current->files); 1149 } 1150 EXPORT_SYMBOL(setup_new_exec); 1151 1152 /* 1153 * Prepare credentials and lock ->cred_guard_mutex. 1154 * install_exec_creds() commits the new creds and drops the lock. 1155 * Or, if exec fails before, free_bprm() should release ->cred and 1156 * and unlock. 1157 */ 1158 int prepare_bprm_creds(struct linux_binprm *bprm) 1159 { 1160 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) 1161 return -ERESTARTNOINTR; 1162 1163 bprm->cred = prepare_exec_creds(); 1164 if (likely(bprm->cred)) 1165 return 0; 1166 1167 mutex_unlock(¤t->signal->cred_guard_mutex); 1168 return -ENOMEM; 1169 } 1170 1171 void free_bprm(struct linux_binprm *bprm) 1172 { 1173 free_arg_pages(bprm); 1174 if (bprm->cred) { 1175 mutex_unlock(¤t->signal->cred_guard_mutex); 1176 abort_creds(bprm->cred); 1177 } 1178 /* If a binfmt changed the interp, free it. */ 1179 if (bprm->interp != bprm->filename) 1180 kfree(bprm->interp); 1181 kfree(bprm); 1182 } 1183 1184 int bprm_change_interp(char *interp, struct linux_binprm *bprm) 1185 { 1186 /* If a binfmt changed the interp, free it first. */ 1187 if (bprm->interp != bprm->filename) 1188 kfree(bprm->interp); 1189 bprm->interp = kstrdup(interp, GFP_KERNEL); 1190 if (!bprm->interp) 1191 return -ENOMEM; 1192 return 0; 1193 } 1194 EXPORT_SYMBOL(bprm_change_interp); 1195 1196 /* 1197 * install the new credentials for this executable 1198 */ 1199 void install_exec_creds(struct linux_binprm *bprm) 1200 { 1201 security_bprm_committing_creds(bprm); 1202 1203 commit_creds(bprm->cred); 1204 bprm->cred = NULL; 1205 1206 /* 1207 * Disable monitoring for regular users 1208 * when executing setuid binaries. Must 1209 * wait until new credentials are committed 1210 * by commit_creds() above 1211 */ 1212 if (get_dumpable(current->mm) != SUID_DUMP_USER) 1213 perf_event_exit_task(current); 1214 /* 1215 * cred_guard_mutex must be held at least to this point to prevent 1216 * ptrace_attach() from altering our determination of the task's 1217 * credentials; any time after this it may be unlocked. 1218 */ 1219 security_bprm_committed_creds(bprm); 1220 mutex_unlock(¤t->signal->cred_guard_mutex); 1221 } 1222 EXPORT_SYMBOL(install_exec_creds); 1223 1224 /* 1225 * determine how safe it is to execute the proposed program 1226 * - the caller must hold ->cred_guard_mutex to protect against 1227 * PTRACE_ATTACH 1228 */ 1229 static int check_unsafe_exec(struct linux_binprm *bprm) 1230 { 1231 struct task_struct *p = current, *t; 1232 unsigned n_fs; 1233 int res = 0; 1234 1235 if (p->ptrace) { 1236 if (p->ptrace & PT_PTRACE_CAP) 1237 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; 1238 else 1239 bprm->unsafe |= LSM_UNSAFE_PTRACE; 1240 } 1241 1242 /* 1243 * This isn't strictly necessary, but it makes it harder for LSMs to 1244 * mess up. 1245 */ 1246 if (current->no_new_privs) 1247 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; 1248 1249 n_fs = 1; 1250 spin_lock(&p->fs->lock); 1251 rcu_read_lock(); 1252 for (t = next_thread(p); t != p; t = next_thread(t)) { 1253 if (t->fs == p->fs) 1254 n_fs++; 1255 } 1256 rcu_read_unlock(); 1257 1258 if (p->fs->users > n_fs) { 1259 bprm->unsafe |= LSM_UNSAFE_SHARE; 1260 } else { 1261 res = -EAGAIN; 1262 if (!p->fs->in_exec) { 1263 p->fs->in_exec = 1; 1264 res = 1; 1265 } 1266 } 1267 spin_unlock(&p->fs->lock); 1268 1269 return res; 1270 } 1271 1272 /* 1273 * Fill the binprm structure from the inode. 1274 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1275 * 1276 * This may be called multiple times for binary chains (scripts for example). 1277 */ 1278 int prepare_binprm(struct linux_binprm *bprm) 1279 { 1280 umode_t mode; 1281 struct inode * inode = file_inode(bprm->file); 1282 int retval; 1283 1284 mode = inode->i_mode; 1285 if (bprm->file->f_op == NULL) 1286 return -EACCES; 1287 1288 /* clear any previous set[ug]id data from a previous binary */ 1289 bprm->cred->euid = current_euid(); 1290 bprm->cred->egid = current_egid(); 1291 1292 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) && 1293 !current->no_new_privs && 1294 kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) && 1295 kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) { 1296 /* Set-uid? */ 1297 if (mode & S_ISUID) { 1298 bprm->per_clear |= PER_CLEAR_ON_SETID; 1299 bprm->cred->euid = inode->i_uid; 1300 } 1301 1302 /* Set-gid? */ 1303 /* 1304 * If setgid is set but no group execute bit then this 1305 * is a candidate for mandatory locking, not a setgid 1306 * executable. 1307 */ 1308 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1309 bprm->per_clear |= PER_CLEAR_ON_SETID; 1310 bprm->cred->egid = inode->i_gid; 1311 } 1312 } 1313 1314 /* fill in binprm security blob */ 1315 retval = security_bprm_set_creds(bprm); 1316 if (retval) 1317 return retval; 1318 bprm->cred_prepared = 1; 1319 1320 memset(bprm->buf, 0, BINPRM_BUF_SIZE); 1321 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); 1322 } 1323 1324 EXPORT_SYMBOL(prepare_binprm); 1325 1326 /* 1327 * Arguments are '\0' separated strings found at the location bprm->p 1328 * points to; chop off the first by relocating brpm->p to right after 1329 * the first '\0' encountered. 1330 */ 1331 int remove_arg_zero(struct linux_binprm *bprm) 1332 { 1333 int ret = 0; 1334 unsigned long offset; 1335 char *kaddr; 1336 struct page *page; 1337 1338 if (!bprm->argc) 1339 return 0; 1340 1341 do { 1342 offset = bprm->p & ~PAGE_MASK; 1343 page = get_arg_page(bprm, bprm->p, 0); 1344 if (!page) { 1345 ret = -EFAULT; 1346 goto out; 1347 } 1348 kaddr = kmap_atomic(page); 1349 1350 for (; offset < PAGE_SIZE && kaddr[offset]; 1351 offset++, bprm->p++) 1352 ; 1353 1354 kunmap_atomic(kaddr); 1355 put_arg_page(page); 1356 1357 if (offset == PAGE_SIZE) 1358 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1359 } while (offset == PAGE_SIZE); 1360 1361 bprm->p++; 1362 bprm->argc--; 1363 ret = 0; 1364 1365 out: 1366 return ret; 1367 } 1368 EXPORT_SYMBOL(remove_arg_zero); 1369 1370 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1371 /* 1372 * cycle the list of binary formats handler, until one recognizes the image 1373 */ 1374 int search_binary_handler(struct linux_binprm *bprm) 1375 { 1376 bool need_retry = IS_ENABLED(CONFIG_MODULES); 1377 struct linux_binfmt *fmt; 1378 int retval; 1379 1380 /* This allows 4 levels of binfmt rewrites before failing hard. */ 1381 if (bprm->recursion_depth > 5) 1382 return -ELOOP; 1383 1384 retval = security_bprm_check(bprm); 1385 if (retval) 1386 return retval; 1387 1388 retval = audit_bprm(bprm); 1389 if (retval) 1390 return retval; 1391 1392 retval = -ENOENT; 1393 retry: 1394 read_lock(&binfmt_lock); 1395 list_for_each_entry(fmt, &formats, lh) { 1396 if (!try_module_get(fmt->module)) 1397 continue; 1398 read_unlock(&binfmt_lock); 1399 bprm->recursion_depth++; 1400 retval = fmt->load_binary(bprm); 1401 bprm->recursion_depth--; 1402 if (retval >= 0 || retval != -ENOEXEC || 1403 bprm->mm == NULL || bprm->file == NULL) { 1404 put_binfmt(fmt); 1405 return retval; 1406 } 1407 read_lock(&binfmt_lock); 1408 put_binfmt(fmt); 1409 } 1410 read_unlock(&binfmt_lock); 1411 1412 if (need_retry && retval == -ENOEXEC) { 1413 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) && 1414 printable(bprm->buf[2]) && printable(bprm->buf[3])) 1415 return retval; 1416 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0) 1417 return retval; 1418 need_retry = false; 1419 goto retry; 1420 } 1421 1422 return retval; 1423 } 1424 EXPORT_SYMBOL(search_binary_handler); 1425 1426 static int exec_binprm(struct linux_binprm *bprm) 1427 { 1428 pid_t old_pid, old_vpid; 1429 int ret; 1430 1431 /* Need to fetch pid before load_binary changes it */ 1432 old_pid = current->pid; 1433 rcu_read_lock(); 1434 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); 1435 rcu_read_unlock(); 1436 1437 ret = search_binary_handler(bprm); 1438 if (ret >= 0) { 1439 trace_sched_process_exec(current, old_pid, bprm); 1440 ptrace_event(PTRACE_EVENT_EXEC, old_vpid); 1441 current->did_exec = 1; 1442 proc_exec_connector(current); 1443 1444 if (bprm->file) { 1445 allow_write_access(bprm->file); 1446 fput(bprm->file); 1447 bprm->file = NULL; /* to catch use-after-free */ 1448 } 1449 } 1450 1451 return ret; 1452 } 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 1467 /* 1468 * We move the actual failure in case of RLIMIT_NPROC excess from 1469 * set*uid() to execve() because too many poorly written programs 1470 * don't check setuid() return code. Here we additionally recheck 1471 * whether NPROC limit is still exceeded. 1472 */ 1473 if ((current->flags & PF_NPROC_EXCEEDED) && 1474 atomic_read(¤t_user()->processes) > rlimit(RLIMIT_NPROC)) { 1475 retval = -EAGAIN; 1476 goto out_ret; 1477 } 1478 1479 /* We're below the limit (still or again), so we don't want to make 1480 * further execve() calls fail. */ 1481 current->flags &= ~PF_NPROC_EXCEEDED; 1482 1483 retval = unshare_files(&displaced); 1484 if (retval) 1485 goto out_ret; 1486 1487 retval = -ENOMEM; 1488 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1489 if (!bprm) 1490 goto out_files; 1491 1492 retval = prepare_bprm_creds(bprm); 1493 if (retval) 1494 goto out_free; 1495 1496 retval = check_unsafe_exec(bprm); 1497 if (retval < 0) 1498 goto out_free; 1499 clear_in_exec = retval; 1500 current->in_execve = 1; 1501 1502 file = open_exec(filename); 1503 retval = PTR_ERR(file); 1504 if (IS_ERR(file)) 1505 goto out_unmark; 1506 1507 sched_exec(); 1508 1509 bprm->file = file; 1510 bprm->filename = filename; 1511 bprm->interp = filename; 1512 1513 retval = bprm_mm_init(bprm); 1514 if (retval) 1515 goto out_file; 1516 1517 bprm->argc = count(argv, MAX_ARG_STRINGS); 1518 if ((retval = bprm->argc) < 0) 1519 goto out; 1520 1521 bprm->envc = count(envp, MAX_ARG_STRINGS); 1522 if ((retval = bprm->envc) < 0) 1523 goto out; 1524 1525 retval = prepare_binprm(bprm); 1526 if (retval < 0) 1527 goto out; 1528 1529 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1530 if (retval < 0) 1531 goto out; 1532 1533 bprm->exec = bprm->p; 1534 retval = copy_strings(bprm->envc, envp, bprm); 1535 if (retval < 0) 1536 goto out; 1537 1538 retval = copy_strings(bprm->argc, argv, bprm); 1539 if (retval < 0) 1540 goto out; 1541 1542 retval = exec_binprm(bprm); 1543 if (retval < 0) 1544 goto out; 1545 1546 /* execve succeeded */ 1547 current->fs->in_exec = 0; 1548 current->in_execve = 0; 1549 acct_update_integrals(current); 1550 free_bprm(bprm); 1551 if (displaced) 1552 put_files_struct(displaced); 1553 return retval; 1554 1555 out: 1556 if (bprm->mm) { 1557 acct_arg_size(bprm, 0); 1558 mmput(bprm->mm); 1559 } 1560 1561 out_file: 1562 if (bprm->file) { 1563 allow_write_access(bprm->file); 1564 fput(bprm->file); 1565 } 1566 1567 out_unmark: 1568 if (clear_in_exec) 1569 current->fs->in_exec = 0; 1570 current->in_execve = 0; 1571 1572 out_free: 1573 free_bprm(bprm); 1574 1575 out_files: 1576 if (displaced) 1577 reset_files_struct(displaced); 1578 out_ret: 1579 return retval; 1580 } 1581 1582 int do_execve(const char *filename, 1583 const char __user *const __user *__argv, 1584 const char __user *const __user *__envp) 1585 { 1586 struct user_arg_ptr argv = { .ptr.native = __argv }; 1587 struct user_arg_ptr envp = { .ptr.native = __envp }; 1588 return do_execve_common(filename, argv, envp); 1589 } 1590 1591 #ifdef CONFIG_COMPAT 1592 static int compat_do_execve(const char *filename, 1593 const compat_uptr_t __user *__argv, 1594 const compat_uptr_t __user *__envp) 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); 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 /* 1623 * set_dumpable converts traditional three-value dumpable to two flags and 1624 * stores them into mm->flags. It modifies lower two bits of mm->flags, but 1625 * these bits are not changed atomically. So get_dumpable can observe the 1626 * intermediate state. To avoid doing unexpected behavior, get get_dumpable 1627 * return either old dumpable or new one by paying attention to the order of 1628 * modifying the bits. 1629 * 1630 * dumpable | mm->flags (binary) 1631 * old new | initial interim final 1632 * ---------+----------------------- 1633 * 0 1 | 00 01 01 1634 * 0 2 | 00 10(*) 11 1635 * 1 0 | 01 00 00 1636 * 1 2 | 01 11 11 1637 * 2 0 | 11 10(*) 00 1638 * 2 1 | 11 11 01 1639 * 1640 * (*) get_dumpable regards interim value of 10 as 11. 1641 */ 1642 void set_dumpable(struct mm_struct *mm, int value) 1643 { 1644 switch (value) { 1645 case SUID_DUMP_DISABLE: 1646 clear_bit(MMF_DUMPABLE, &mm->flags); 1647 smp_wmb(); 1648 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1649 break; 1650 case SUID_DUMP_USER: 1651 set_bit(MMF_DUMPABLE, &mm->flags); 1652 smp_wmb(); 1653 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1654 break; 1655 case SUID_DUMP_ROOT: 1656 set_bit(MMF_DUMP_SECURELY, &mm->flags); 1657 smp_wmb(); 1658 set_bit(MMF_DUMPABLE, &mm->flags); 1659 break; 1660 } 1661 } 1662 1663 int __get_dumpable(unsigned long mm_flags) 1664 { 1665 int ret; 1666 1667 ret = mm_flags & MMF_DUMPABLE_MASK; 1668 return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret; 1669 } 1670 1671 int get_dumpable(struct mm_struct *mm) 1672 { 1673 return __get_dumpable(mm->flags); 1674 } 1675 1676 SYSCALL_DEFINE3(execve, 1677 const char __user *, filename, 1678 const char __user *const __user *, argv, 1679 const char __user *const __user *, envp) 1680 { 1681 struct filename *path = getname(filename); 1682 int error = PTR_ERR(path); 1683 if (!IS_ERR(path)) { 1684 error = do_execve(path->name, argv, envp); 1685 putname(path); 1686 } 1687 return error; 1688 } 1689 #ifdef CONFIG_COMPAT 1690 asmlinkage long compat_sys_execve(const char __user * filename, 1691 const compat_uptr_t __user * argv, 1692 const compat_uptr_t __user * envp) 1693 { 1694 struct filename *path = getname(filename); 1695 int error = PTR_ERR(path); 1696 if (!IS_ERR(path)) { 1697 error = compat_do_execve(path->name, argv, envp); 1698 putname(path); 1699 } 1700 return error; 1701 } 1702 #endif 1703