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/vmacache.h> 30#include <linux/stat.h> 31#include <linux/fcntl.h> 32#include <linux/swap.h> 33#include <linux/string.h> 34#include <linux/init.h> 35#include <linux/pagemap.h> 36#include <linux/perf_event.h> 37#include <linux/highmem.h> 38#include <linux/spinlock.h> 39#include <linux/key.h> 40#include <linux/personality.h> 41#include <linux/binfmts.h> 42#include <linux/utsname.h> 43#include <linux/pid_namespace.h> 44#include <linux/module.h> 45#include <linux/namei.h> 46#include <linux/mount.h> 47#include <linux/security.h> 48#include <linux/syscalls.h> 49#include <linux/tsacct_kern.h> 50#include <linux/cn_proc.h> 51#include <linux/audit.h> 52#include <linux/tracehook.h> 53#include <linux/kmod.h> 54#include <linux/fsnotify.h> 55#include <linux/fs_struct.h> 56#include <linux/pipe_fs_i.h> 57#include <linux/oom.h> 58#include <linux/compat.h> 59 60#include <asm/uaccess.h> 61#include <asm/mmu_context.h> 62#include <asm/tlb.h> 63 64#include <trace/events/task.h> 65#include "internal.h" 66 67#include <trace/events/sched.h> 68 69int suid_dumpable = 0; 70 71static LIST_HEAD(formats); 72static DEFINE_RWLOCK(binfmt_lock); 73 74void __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 85EXPORT_SYMBOL(__register_binfmt); 86 87void unregister_binfmt(struct linux_binfmt * fmt) 88{ 89 write_lock(&binfmt_lock); 90 list_del(&fmt->lh); 91 write_unlock(&binfmt_lock); 92} 93 94EXPORT_SYMBOL(unregister_binfmt); 95 96static inline void put_binfmt(struct linux_binfmt * fmt) 97{ 98 module_put(fmt->module); 99} 100 101#ifdef CONFIG_USELIB 102/* 103 * Note that a shared library must be both readable and executable due to 104 * security reasons. 105 * 106 * Also note that we take the address to load from from the file itself. 107 */ 108SYSCALL_DEFINE1(uselib, const char __user *, library) 109{ 110 struct linux_binfmt *fmt; 111 struct file *file; 112 struct filename *tmp = getname(library); 113 int error = PTR_ERR(tmp); 114 static const struct open_flags uselib_flags = { 115 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 116 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, 117 .intent = LOOKUP_OPEN, 118 .lookup_flags = LOOKUP_FOLLOW, 119 }; 120 121 if (IS_ERR(tmp)) 122 goto out; 123 124 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags); 125 putname(tmp); 126 error = PTR_ERR(file); 127 if (IS_ERR(file)) 128 goto out; 129 130 error = -EINVAL; 131 if (!S_ISREG(file_inode(file)->i_mode)) 132 goto exit; 133 134 error = -EACCES; 135 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 136 goto exit; 137 138 fsnotify_open(file); 139 140 error = -ENOEXEC; 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); 156exit: 157 fput(file); 158out: 159 return error; 160} 161#endif /* #ifdef CONFIG_USELIB */ 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 */ 170static 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 182static 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 230static void put_arg_page(struct page *page) 231{ 232 put_page(page); 233} 234 235static void free_arg_page(struct linux_binprm *bprm, int i) 236{ 237} 238 239static void free_arg_pages(struct linux_binprm *bprm) 240{ 241} 242 243static 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 249static 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 arch_bprm_mm_init(mm, vma); 281 up_write(&mm->mmap_sem); 282 bprm->p = vma->vm_end - sizeof(void *); 283 return 0; 284err: 285 up_write(&mm->mmap_sem); 286 bprm->vma = NULL; 287 kmem_cache_free(vm_area_cachep, vma); 288 return err; 289} 290 291static bool valid_arg_len(struct linux_binprm *bprm, long len) 292{ 293 return len <= MAX_ARG_STRLEN; 294} 295 296#else 297 298static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 299{ 300} 301 302static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 303 int write) 304{ 305 struct page *page; 306 307 page = bprm->page[pos / PAGE_SIZE]; 308 if (!page && write) { 309 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 310 if (!page) 311 return NULL; 312 bprm->page[pos / PAGE_SIZE] = page; 313 } 314 315 return page; 316} 317 318static void put_arg_page(struct page *page) 319{ 320} 321 322static void free_arg_page(struct linux_binprm *bprm, int i) 323{ 324 if (bprm->page[i]) { 325 __free_page(bprm->page[i]); 326 bprm->page[i] = NULL; 327 } 328} 329 330static void free_arg_pages(struct linux_binprm *bprm) 331{ 332 int i; 333 334 for (i = 0; i < MAX_ARG_PAGES; i++) 335 free_arg_page(bprm, i); 336} 337 338static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 339 struct page *page) 340{ 341} 342 343static int __bprm_mm_init(struct linux_binprm *bprm) 344{ 345 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 346 return 0; 347} 348 349static bool valid_arg_len(struct linux_binprm *bprm, long len) 350{ 351 return len <= bprm->p; 352} 353 354#endif /* CONFIG_MMU */ 355 356/* 357 * Create a new mm_struct and populate it with a temporary stack 358 * vm_area_struct. We don't have enough context at this point to set the stack 359 * flags, permissions, and offset, so we use temporary values. We'll update 360 * them later in setup_arg_pages(). 361 */ 362static int bprm_mm_init(struct linux_binprm *bprm) 363{ 364 int err; 365 struct mm_struct *mm = NULL; 366 367 bprm->mm = mm = mm_alloc(); 368 err = -ENOMEM; 369 if (!mm) 370 goto err; 371 372 err = __bprm_mm_init(bprm); 373 if (err) 374 goto err; 375 376 return 0; 377 378err: 379 if (mm) { 380 bprm->mm = NULL; 381 mmdrop(mm); 382 } 383 384 return err; 385} 386 387struct 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 399static 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 */ 423static 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 */ 454static 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; 533out: 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 */ 545int 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} 560EXPORT_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 */ 576static 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, old_start, old_end); 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, old_start, 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 */ 641int 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 */ 658 stack_base = rlimit_max(RLIMIT_STACK); 659 if (stack_base > STACK_SIZE_MAX) 660 stack_base = STACK_SIZE_MAX; 661 662 /* Add space for stack randomization. */ 663 stack_base += (STACK_RND_MASK << PAGE_SHIFT); 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 746out_unlock: 747 up_write(&mm->mmap_sem); 748 return ret; 749} 750EXPORT_SYMBOL(setup_arg_pages); 751 752#endif /* CONFIG_MMU */ 753 754static struct file *do_open_execat(int fd, struct filename *name, int flags) 755{ 756 struct file *file; 757 int err; 758 struct open_flags open_exec_flags = { 759 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, 760 .acc_mode = MAY_EXEC | MAY_OPEN, 761 .intent = LOOKUP_OPEN, 762 .lookup_flags = LOOKUP_FOLLOW, 763 }; 764 765 if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) 766 return ERR_PTR(-EINVAL); 767 if (flags & AT_SYMLINK_NOFOLLOW) 768 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW; 769 if (flags & AT_EMPTY_PATH) 770 open_exec_flags.lookup_flags |= LOOKUP_EMPTY; 771 772 file = do_filp_open(fd, name, &open_exec_flags); 773 if (IS_ERR(file)) 774 goto out; 775 776 err = -EACCES; 777 if (!S_ISREG(file_inode(file)->i_mode)) 778 goto exit; 779 780 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 781 goto exit; 782 783 err = deny_write_access(file); 784 if (err) 785 goto exit; 786 787 if (name->name[0] != '\0') 788 fsnotify_open(file); 789 790out: 791 return file; 792 793exit: 794 fput(file); 795 return ERR_PTR(err); 796} 797 798struct file *open_exec(const char *name) 799{ 800 struct filename *filename = getname_kernel(name); 801 struct file *f = ERR_CAST(filename); 802 803 if (!IS_ERR(filename)) { 804 f = do_open_execat(AT_FDCWD, filename, 0); 805 putname(filename); 806 } 807 return f; 808} 809EXPORT_SYMBOL(open_exec); 810 811int kernel_read(struct file *file, loff_t offset, 812 char *addr, unsigned long count) 813{ 814 mm_segment_t old_fs; 815 loff_t pos = offset; 816 int result; 817 818 old_fs = get_fs(); 819 set_fs(get_ds()); 820 /* The cast to a user pointer is valid due to the set_fs() */ 821 result = vfs_read(file, (void __user *)addr, count, &pos); 822 set_fs(old_fs); 823 return result; 824} 825 826EXPORT_SYMBOL(kernel_read); 827 828ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len) 829{ 830 ssize_t res = vfs_read(file, (void __user *)addr, len, &pos); 831 if (res > 0) 832 flush_icache_range(addr, addr + len); 833 return res; 834} 835EXPORT_SYMBOL(read_code); 836 837static int exec_mmap(struct mm_struct *mm) 838{ 839 struct task_struct *tsk; 840 struct mm_struct *old_mm, *active_mm; 841 842 /* Notify parent that we're no longer interested in the old VM */ 843 tsk = current; 844 old_mm = current->mm; 845 mm_release(tsk, old_mm); 846 847 if (old_mm) { 848 sync_mm_rss(old_mm); 849 /* 850 * Make sure that if there is a core dump in progress 851 * for the old mm, we get out and die instead of going 852 * through with the exec. We must hold mmap_sem around 853 * checking core_state and changing tsk->mm. 854 */ 855 down_read(&old_mm->mmap_sem); 856 if (unlikely(old_mm->core_state)) { 857 up_read(&old_mm->mmap_sem); 858 return -EINTR; 859 } 860 } 861 task_lock(tsk); 862 active_mm = tsk->active_mm; 863 tsk->mm = mm; 864 tsk->active_mm = mm; 865 activate_mm(active_mm, mm); 866 tsk->mm->vmacache_seqnum = 0; 867 vmacache_flush(tsk); 868 task_unlock(tsk); 869 if (old_mm) { 870 up_read(&old_mm->mmap_sem); 871 BUG_ON(active_mm != old_mm); 872 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); 873 mm_update_next_owner(old_mm); 874 mmput(old_mm); 875 return 0; 876 } 877 mmdrop(active_mm); 878 return 0; 879} 880 881/* 882 * This function makes sure the current process has its own signal table, 883 * so that flush_signal_handlers can later reset the handlers without 884 * disturbing other processes. (Other processes might share the signal 885 * table via the CLONE_SIGHAND option to clone().) 886 */ 887static int de_thread(struct task_struct *tsk) 888{ 889 struct signal_struct *sig = tsk->signal; 890 struct sighand_struct *oldsighand = tsk->sighand; 891 spinlock_t *lock = &oldsighand->siglock; 892 893 if (thread_group_empty(tsk)) 894 goto no_thread_group; 895 896 /* 897 * Kill all other threads in the thread group. 898 */ 899 spin_lock_irq(lock); 900 if (signal_group_exit(sig)) { 901 /* 902 * Another group action in progress, just 903 * return so that the signal is processed. 904 */ 905 spin_unlock_irq(lock); 906 return -EAGAIN; 907 } 908 909 sig->group_exit_task = tsk; 910 sig->notify_count = zap_other_threads(tsk); 911 if (!thread_group_leader(tsk)) 912 sig->notify_count--; 913 914 while (sig->notify_count) { 915 __set_current_state(TASK_KILLABLE); 916 spin_unlock_irq(lock); 917 schedule(); 918 if (unlikely(__fatal_signal_pending(tsk))) 919 goto killed; 920 spin_lock_irq(lock); 921 } 922 spin_unlock_irq(lock); 923 924 /* 925 * At this point all other threads have exited, all we have to 926 * do is to wait for the thread group leader to become inactive, 927 * and to assume its PID: 928 */ 929 if (!thread_group_leader(tsk)) { 930 struct task_struct *leader = tsk->group_leader; 931 932 for (;;) { 933 threadgroup_change_begin(tsk); 934 write_lock_irq(&tasklist_lock); 935 /* 936 * Do this under tasklist_lock to ensure that 937 * exit_notify() can't miss ->group_exit_task 938 */ 939 sig->notify_count = -1; 940 if (likely(leader->exit_state)) 941 break; 942 __set_current_state(TASK_KILLABLE); 943 write_unlock_irq(&tasklist_lock); 944 threadgroup_change_end(tsk); 945 schedule(); 946 if (unlikely(__fatal_signal_pending(tsk))) 947 goto killed; 948 } 949 950 /* 951 * The only record we have of the real-time age of a 952 * process, regardless of execs it's done, is start_time. 953 * All the past CPU time is accumulated in signal_struct 954 * from sister threads now dead. But in this non-leader 955 * exec, nothing survives from the original leader thread, 956 * whose birth marks the true age of this process now. 957 * When we take on its identity by switching to its PID, we 958 * also take its birthdate (always earlier than our own). 959 */ 960 tsk->start_time = leader->start_time; 961 tsk->real_start_time = leader->real_start_time; 962 963 BUG_ON(!same_thread_group(leader, tsk)); 964 BUG_ON(has_group_leader_pid(tsk)); 965 /* 966 * An exec() starts a new thread group with the 967 * TGID of the previous thread group. Rehash the 968 * two threads with a switched PID, and release 969 * the former thread group leader: 970 */ 971 972 /* Become a process group leader with the old leader's pid. 973 * The old leader becomes a thread of the this thread group. 974 * Note: The old leader also uses this pid until release_task 975 * is called. Odd but simple and correct. 976 */ 977 tsk->pid = leader->pid; 978 change_pid(tsk, PIDTYPE_PID, task_pid(leader)); 979 transfer_pid(leader, tsk, PIDTYPE_PGID); 980 transfer_pid(leader, tsk, PIDTYPE_SID); 981 982 list_replace_rcu(&leader->tasks, &tsk->tasks); 983 list_replace_init(&leader->sibling, &tsk->sibling); 984 985 tsk->group_leader = tsk; 986 leader->group_leader = tsk; 987 988 tsk->exit_signal = SIGCHLD; 989 leader->exit_signal = -1; 990 991 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 992 leader->exit_state = EXIT_DEAD; 993 994 /* 995 * We are going to release_task()->ptrace_unlink() silently, 996 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees 997 * the tracer wont't block again waiting for this thread. 998 */ 999 if (unlikely(leader->ptrace)) 1000 __wake_up_parent(leader, leader->parent); 1001 write_unlock_irq(&tasklist_lock); 1002 threadgroup_change_end(tsk); 1003 1004 release_task(leader); 1005 } 1006 1007 sig->group_exit_task = NULL; 1008 sig->notify_count = 0; 1009 1010no_thread_group: 1011 /* we have changed execution domain */ 1012 tsk->exit_signal = SIGCHLD; 1013 1014 exit_itimers(sig); 1015 flush_itimer_signals(); 1016 1017 if (atomic_read(&oldsighand->count) != 1) { 1018 struct sighand_struct *newsighand; 1019 /* 1020 * This ->sighand is shared with the CLONE_SIGHAND 1021 * but not CLONE_THREAD task, switch to the new one. 1022 */ 1023 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 1024 if (!newsighand) 1025 return -ENOMEM; 1026 1027 atomic_set(&newsighand->count, 1); 1028 memcpy(newsighand->action, oldsighand->action, 1029 sizeof(newsighand->action)); 1030 1031 write_lock_irq(&tasklist_lock); 1032 spin_lock(&oldsighand->siglock); 1033 rcu_assign_pointer(tsk->sighand, newsighand); 1034 spin_unlock(&oldsighand->siglock); 1035 write_unlock_irq(&tasklist_lock); 1036 1037 __cleanup_sighand(oldsighand); 1038 } 1039 1040 BUG_ON(!thread_group_leader(tsk)); 1041 return 0; 1042 1043killed: 1044 /* protects against exit_notify() and __exit_signal() */ 1045 read_lock(&tasklist_lock); 1046 sig->group_exit_task = NULL; 1047 sig->notify_count = 0; 1048 read_unlock(&tasklist_lock); 1049 return -EAGAIN; 1050} 1051 1052char *get_task_comm(char *buf, struct task_struct *tsk) 1053{ 1054 /* buf must be at least sizeof(tsk->comm) in size */ 1055 task_lock(tsk); 1056 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 1057 task_unlock(tsk); 1058 return buf; 1059} 1060EXPORT_SYMBOL_GPL(get_task_comm); 1061 1062/* 1063 * These functions flushes out all traces of the currently running executable 1064 * so that a new one can be started 1065 */ 1066 1067void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) 1068{ 1069 task_lock(tsk); 1070 trace_task_rename(tsk, buf); 1071 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 1072 task_unlock(tsk); 1073 perf_event_comm(tsk, exec); 1074} 1075 1076int flush_old_exec(struct linux_binprm * bprm) 1077{ 1078 int retval; 1079 1080 /* 1081 * Make sure we have a private signal table and that 1082 * we are unassociated from the previous thread group. 1083 */ 1084 retval = de_thread(current); 1085 if (retval) 1086 goto out; 1087 1088 /* 1089 * Must be called _before_ exec_mmap() as bprm->mm is 1090 * not visibile until then. This also enables the update 1091 * to be lockless. 1092 */ 1093 set_mm_exe_file(bprm->mm, bprm->file); 1094 1095 /* 1096 * Release all of the old mmap stuff 1097 */ 1098 acct_arg_size(bprm, 0); 1099 retval = exec_mmap(bprm->mm); 1100 if (retval) 1101 goto out; 1102 1103 bprm->mm = NULL; /* We're using it now */ 1104 1105 set_fs(USER_DS); 1106 current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | 1107 PF_NOFREEZE | PF_NO_SETAFFINITY); 1108 flush_thread(); 1109 current->personality &= ~bprm->per_clear; 1110 1111 return 0; 1112 1113out: 1114 return retval; 1115} 1116EXPORT_SYMBOL(flush_old_exec); 1117 1118void would_dump(struct linux_binprm *bprm, struct file *file) 1119{ 1120 if (inode_permission(file_inode(file), MAY_READ) < 0) 1121 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; 1122} 1123EXPORT_SYMBOL(would_dump); 1124 1125void setup_new_exec(struct linux_binprm * bprm) 1126{ 1127 arch_pick_mmap_layout(current->mm); 1128 1129 /* This is the point of no return */ 1130 current->sas_ss_sp = current->sas_ss_size = 0; 1131 1132 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) 1133 set_dumpable(current->mm, SUID_DUMP_USER); 1134 else 1135 set_dumpable(current->mm, suid_dumpable); 1136 1137 perf_event_exec(); 1138 __set_task_comm(current, kbasename(bprm->filename), true); 1139 1140 /* Set the new mm task size. We have to do that late because it may 1141 * depend on TIF_32BIT which is only updated in flush_thread() on 1142 * some architectures like powerpc 1143 */ 1144 current->mm->task_size = TASK_SIZE; 1145 1146 /* install the new credentials */ 1147 if (!uid_eq(bprm->cred->uid, current_euid()) || 1148 !gid_eq(bprm->cred->gid, current_egid())) { 1149 current->pdeath_signal = 0; 1150 } else { 1151 would_dump(bprm, bprm->file); 1152 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) 1153 set_dumpable(current->mm, suid_dumpable); 1154 } 1155 1156 /* An exec changes our domain. We are no longer part of the thread 1157 group */ 1158 current->self_exec_id++; 1159 flush_signal_handlers(current, 0); 1160 do_close_on_exec(current->files); 1161} 1162EXPORT_SYMBOL(setup_new_exec); 1163 1164/* 1165 * Prepare credentials and lock ->cred_guard_mutex. 1166 * install_exec_creds() commits the new creds and drops the lock. 1167 * Or, if exec fails before, free_bprm() should release ->cred and 1168 * and unlock. 1169 */ 1170int prepare_bprm_creds(struct linux_binprm *bprm) 1171{ 1172 if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) 1173 return -ERESTARTNOINTR; 1174 1175 bprm->cred = prepare_exec_creds(); 1176 if (likely(bprm->cred)) 1177 return 0; 1178 1179 mutex_unlock(¤t->signal->cred_guard_mutex); 1180 return -ENOMEM; 1181} 1182 1183static void free_bprm(struct linux_binprm *bprm) 1184{ 1185 free_arg_pages(bprm); 1186 if (bprm->cred) { 1187 mutex_unlock(¤t->signal->cred_guard_mutex); 1188 abort_creds(bprm->cred); 1189 } 1190 if (bprm->file) { 1191 allow_write_access(bprm->file); 1192 fput(bprm->file); 1193 } 1194 /* If a binfmt changed the interp, free it. */ 1195 if (bprm->interp != bprm->filename) 1196 kfree(bprm->interp); 1197 kfree(bprm); 1198} 1199 1200int bprm_change_interp(char *interp, struct linux_binprm *bprm) 1201{ 1202 /* If a binfmt changed the interp, free it first. */ 1203 if (bprm->interp != bprm->filename) 1204 kfree(bprm->interp); 1205 bprm->interp = kstrdup(interp, GFP_KERNEL); 1206 if (!bprm->interp) 1207 return -ENOMEM; 1208 return 0; 1209} 1210EXPORT_SYMBOL(bprm_change_interp); 1211 1212/* 1213 * install the new credentials for this executable 1214 */ 1215void install_exec_creds(struct linux_binprm *bprm) 1216{ 1217 security_bprm_committing_creds(bprm); 1218 1219 commit_creds(bprm->cred); 1220 bprm->cred = NULL; 1221 1222 /* 1223 * Disable monitoring for regular users 1224 * when executing setuid binaries. Must 1225 * wait until new credentials are committed 1226 * by commit_creds() above 1227 */ 1228 if (get_dumpable(current->mm) != SUID_DUMP_USER) 1229 perf_event_exit_task(current); 1230 /* 1231 * cred_guard_mutex must be held at least to this point to prevent 1232 * ptrace_attach() from altering our determination of the task's 1233 * credentials; any time after this it may be unlocked. 1234 */ 1235 security_bprm_committed_creds(bprm); 1236 mutex_unlock(¤t->signal->cred_guard_mutex); 1237} 1238EXPORT_SYMBOL(install_exec_creds); 1239 1240/* 1241 * determine how safe it is to execute the proposed program 1242 * - the caller must hold ->cred_guard_mutex to protect against 1243 * PTRACE_ATTACH or seccomp thread-sync 1244 */ 1245static void check_unsafe_exec(struct linux_binprm *bprm) 1246{ 1247 struct task_struct *p = current, *t; 1248 unsigned n_fs; 1249 1250 if (p->ptrace) { 1251 if (p->ptrace & PT_PTRACE_CAP) 1252 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP; 1253 else 1254 bprm->unsafe |= LSM_UNSAFE_PTRACE; 1255 } 1256 1257 /* 1258 * This isn't strictly necessary, but it makes it harder for LSMs to 1259 * mess up. 1260 */ 1261 if (task_no_new_privs(current)) 1262 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; 1263 1264 t = p; 1265 n_fs = 1; 1266 spin_lock(&p->fs->lock); 1267 rcu_read_lock(); 1268 while_each_thread(p, t) { 1269 if (t->fs == p->fs) 1270 n_fs++; 1271 } 1272 rcu_read_unlock(); 1273 1274 if (p->fs->users > n_fs) 1275 bprm->unsafe |= LSM_UNSAFE_SHARE; 1276 else 1277 p->fs->in_exec = 1; 1278 spin_unlock(&p->fs->lock); 1279} 1280 1281static void bprm_fill_uid(struct linux_binprm *bprm) 1282{ 1283 struct inode *inode; 1284 unsigned int mode; 1285 kuid_t uid; 1286 kgid_t gid; 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 return; 1294 1295 if (task_no_new_privs(current)) 1296 return; 1297 1298 inode = file_inode(bprm->file); 1299 mode = READ_ONCE(inode->i_mode); 1300 if (!(mode & (S_ISUID|S_ISGID))) 1301 return; 1302 1303 /* Be careful if suid/sgid is set */ 1304 mutex_lock(&inode->i_mutex); 1305 1306 /* reload atomically mode/uid/gid now that lock held */ 1307 mode = inode->i_mode; 1308 uid = inode->i_uid; 1309 gid = inode->i_gid; 1310 mutex_unlock(&inode->i_mutex); 1311 1312 /* We ignore suid/sgid if there are no mappings for them in the ns */ 1313 if (!kuid_has_mapping(bprm->cred->user_ns, uid) || 1314 !kgid_has_mapping(bprm->cred->user_ns, gid)) 1315 return; 1316 1317 if (mode & S_ISUID) { 1318 bprm->per_clear |= PER_CLEAR_ON_SETID; 1319 bprm->cred->euid = uid; 1320 } 1321 1322 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1323 bprm->per_clear |= PER_CLEAR_ON_SETID; 1324 bprm->cred->egid = gid; 1325 } 1326} 1327 1328/* 1329 * Fill the binprm structure from the inode. 1330 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1331 * 1332 * This may be called multiple times for binary chains (scripts for example). 1333 */ 1334int prepare_binprm(struct linux_binprm *bprm) 1335{ 1336 int retval; 1337 1338 bprm_fill_uid(bprm); 1339 1340 /* fill in binprm security blob */ 1341 retval = security_bprm_set_creds(bprm); 1342 if (retval) 1343 return retval; 1344 bprm->cred_prepared = 1; 1345 1346 memset(bprm->buf, 0, BINPRM_BUF_SIZE); 1347 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); 1348} 1349 1350EXPORT_SYMBOL(prepare_binprm); 1351 1352/* 1353 * Arguments are '\0' separated strings found at the location bprm->p 1354 * points to; chop off the first by relocating brpm->p to right after 1355 * the first '\0' encountered. 1356 */ 1357int remove_arg_zero(struct linux_binprm *bprm) 1358{ 1359 int ret = 0; 1360 unsigned long offset; 1361 char *kaddr; 1362 struct page *page; 1363 1364 if (!bprm->argc) 1365 return 0; 1366 1367 do { 1368 offset = bprm->p & ~PAGE_MASK; 1369 page = get_arg_page(bprm, bprm->p, 0); 1370 if (!page) { 1371 ret = -EFAULT; 1372 goto out; 1373 } 1374 kaddr = kmap_atomic(page); 1375 1376 for (; offset < PAGE_SIZE && kaddr[offset]; 1377 offset++, bprm->p++) 1378 ; 1379 1380 kunmap_atomic(kaddr); 1381 put_arg_page(page); 1382 1383 if (offset == PAGE_SIZE) 1384 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1385 } while (offset == PAGE_SIZE); 1386 1387 bprm->p++; 1388 bprm->argc--; 1389 ret = 0; 1390 1391out: 1392 return ret; 1393} 1394EXPORT_SYMBOL(remove_arg_zero); 1395 1396#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1397/* 1398 * cycle the list of binary formats handler, until one recognizes the image 1399 */ 1400int search_binary_handler(struct linux_binprm *bprm) 1401{ 1402 bool need_retry = IS_ENABLED(CONFIG_MODULES); 1403 struct linux_binfmt *fmt; 1404 int retval; 1405 1406 /* This allows 4 levels of binfmt rewrites before failing hard. */ 1407 if (bprm->recursion_depth > 5) 1408 return -ELOOP; 1409 1410 retval = security_bprm_check(bprm); 1411 if (retval) 1412 return retval; 1413 1414 retval = -ENOENT; 1415 retry: 1416 read_lock(&binfmt_lock); 1417 list_for_each_entry(fmt, &formats, lh) { 1418 if (!try_module_get(fmt->module)) 1419 continue; 1420 read_unlock(&binfmt_lock); 1421 bprm->recursion_depth++; 1422 retval = fmt->load_binary(bprm); 1423 read_lock(&binfmt_lock); 1424 put_binfmt(fmt); 1425 bprm->recursion_depth--; 1426 if (retval < 0 && !bprm->mm) { 1427 /* we got to flush_old_exec() and failed after it */ 1428 read_unlock(&binfmt_lock); 1429 force_sigsegv(SIGSEGV, current); 1430 return retval; 1431 } 1432 if (retval != -ENOEXEC || !bprm->file) { 1433 read_unlock(&binfmt_lock); 1434 return retval; 1435 } 1436 } 1437 read_unlock(&binfmt_lock); 1438 1439 if (need_retry) { 1440 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) && 1441 printable(bprm->buf[2]) && printable(bprm->buf[3])) 1442 return retval; 1443 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0) 1444 return retval; 1445 need_retry = false; 1446 goto retry; 1447 } 1448 1449 return retval; 1450} 1451EXPORT_SYMBOL(search_binary_handler); 1452 1453static int exec_binprm(struct linux_binprm *bprm) 1454{ 1455 pid_t old_pid, old_vpid; 1456 int ret; 1457 1458 /* Need to fetch pid before load_binary changes it */ 1459 old_pid = current->pid; 1460 rcu_read_lock(); 1461 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); 1462 rcu_read_unlock(); 1463 1464 ret = search_binary_handler(bprm); 1465 if (ret >= 0) { 1466 audit_bprm(bprm); 1467 trace_sched_process_exec(current, old_pid, bprm); 1468 ptrace_event(PTRACE_EVENT_EXEC, old_vpid); 1469 proc_exec_connector(current); 1470 } 1471 1472 return ret; 1473} 1474 1475/* 1476 * sys_execve() executes a new program. 1477 */ 1478static int do_execveat_common(int fd, struct filename *filename, 1479 struct user_arg_ptr argv, 1480 struct user_arg_ptr envp, 1481 int flags) 1482{ 1483 char *pathbuf = NULL; 1484 struct linux_binprm *bprm; 1485 struct file *file; 1486 struct files_struct *displaced; 1487 int retval; 1488 1489 if (IS_ERR(filename)) 1490 return PTR_ERR(filename); 1491 1492 /* 1493 * We move the actual failure in case of RLIMIT_NPROC excess from 1494 * set*uid() to execve() because too many poorly written programs 1495 * don't check setuid() return code. Here we additionally recheck 1496 * whether NPROC limit is still exceeded. 1497 */ 1498 if ((current->flags & PF_NPROC_EXCEEDED) && 1499 atomic_read(¤t_user()->processes) > rlimit(RLIMIT_NPROC)) { 1500 retval = -EAGAIN; 1501 goto out_ret; 1502 } 1503 1504 /* We're below the limit (still or again), so we don't want to make 1505 * further execve() calls fail. */ 1506 current->flags &= ~PF_NPROC_EXCEEDED; 1507 1508 retval = unshare_files(&displaced); 1509 if (retval) 1510 goto out_ret; 1511 1512 retval = -ENOMEM; 1513 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1514 if (!bprm) 1515 goto out_files; 1516 1517 retval = prepare_bprm_creds(bprm); 1518 if (retval) 1519 goto out_free; 1520 1521 check_unsafe_exec(bprm); 1522 current->in_execve = 1; 1523 1524 file = do_open_execat(fd, filename, flags); 1525 retval = PTR_ERR(file); 1526 if (IS_ERR(file)) 1527 goto out_unmark; 1528 1529 sched_exec(); 1530 1531 bprm->file = file; 1532 if (fd == AT_FDCWD || filename->name[0] == '/') { 1533 bprm->filename = filename->name; 1534 } else { 1535 if (filename->name[0] == '\0') 1536 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd); 1537 else 1538 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s", 1539 fd, filename->name); 1540 if (!pathbuf) { 1541 retval = -ENOMEM; 1542 goto out_unmark; 1543 } 1544 /* 1545 * Record that a name derived from an O_CLOEXEC fd will be 1546 * inaccessible after exec. Relies on having exclusive access to 1547 * current->files (due to unshare_files above). 1548 */ 1549 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt))) 1550 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE; 1551 bprm->filename = pathbuf; 1552 } 1553 bprm->interp = bprm->filename; 1554 1555 retval = bprm_mm_init(bprm); 1556 if (retval) 1557 goto out_unmark; 1558 1559 bprm->argc = count(argv, MAX_ARG_STRINGS); 1560 if ((retval = bprm->argc) < 0) 1561 goto out; 1562 1563 bprm->envc = count(envp, MAX_ARG_STRINGS); 1564 if ((retval = bprm->envc) < 0) 1565 goto out; 1566 1567 retval = prepare_binprm(bprm); 1568 if (retval < 0) 1569 goto out; 1570 1571 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1572 if (retval < 0) 1573 goto out; 1574 1575 bprm->exec = bprm->p; 1576 retval = copy_strings(bprm->envc, envp, bprm); 1577 if (retval < 0) 1578 goto out; 1579 1580 retval = copy_strings(bprm->argc, argv, bprm); 1581 if (retval < 0) 1582 goto out; 1583 1584 retval = exec_binprm(bprm); 1585 if (retval < 0) 1586 goto out; 1587 1588 /* execve succeeded */ 1589 current->fs->in_exec = 0; 1590 current->in_execve = 0; 1591 acct_update_integrals(current); 1592 task_numa_free(current); 1593 free_bprm(bprm); 1594 kfree(pathbuf); 1595 putname(filename); 1596 if (displaced) 1597 put_files_struct(displaced); 1598 return retval; 1599 1600out: 1601 if (bprm->mm) { 1602 acct_arg_size(bprm, 0); 1603 mmput(bprm->mm); 1604 } 1605 1606out_unmark: 1607 current->fs->in_exec = 0; 1608 current->in_execve = 0; 1609 1610out_free: 1611 free_bprm(bprm); 1612 kfree(pathbuf); 1613 1614out_files: 1615 if (displaced) 1616 reset_files_struct(displaced); 1617out_ret: 1618 putname(filename); 1619 return retval; 1620} 1621 1622int do_execve(struct filename *filename, 1623 const char __user *const __user *__argv, 1624 const char __user *const __user *__envp) 1625{ 1626 struct user_arg_ptr argv = { .ptr.native = __argv }; 1627 struct user_arg_ptr envp = { .ptr.native = __envp }; 1628 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0); 1629} 1630 1631int do_execveat(int fd, struct filename *filename, 1632 const char __user *const __user *__argv, 1633 const char __user *const __user *__envp, 1634 int flags) 1635{ 1636 struct user_arg_ptr argv = { .ptr.native = __argv }; 1637 struct user_arg_ptr envp = { .ptr.native = __envp }; 1638 1639 return do_execveat_common(fd, filename, argv, envp, flags); 1640} 1641 1642#ifdef CONFIG_COMPAT 1643static int compat_do_execve(struct filename *filename, 1644 const compat_uptr_t __user *__argv, 1645 const compat_uptr_t __user *__envp) 1646{ 1647 struct user_arg_ptr argv = { 1648 .is_compat = true, 1649 .ptr.compat = __argv, 1650 }; 1651 struct user_arg_ptr envp = { 1652 .is_compat = true, 1653 .ptr.compat = __envp, 1654 }; 1655 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0); 1656} 1657 1658static int compat_do_execveat(int fd, struct filename *filename, 1659 const compat_uptr_t __user *__argv, 1660 const compat_uptr_t __user *__envp, 1661 int flags) 1662{ 1663 struct user_arg_ptr argv = { 1664 .is_compat = true, 1665 .ptr.compat = __argv, 1666 }; 1667 struct user_arg_ptr envp = { 1668 .is_compat = true, 1669 .ptr.compat = __envp, 1670 }; 1671 return do_execveat_common(fd, filename, argv, envp, flags); 1672} 1673#endif 1674 1675void set_binfmt(struct linux_binfmt *new) 1676{ 1677 struct mm_struct *mm = current->mm; 1678 1679 if (mm->binfmt) 1680 module_put(mm->binfmt->module); 1681 1682 mm->binfmt = new; 1683 if (new) 1684 __module_get(new->module); 1685} 1686EXPORT_SYMBOL(set_binfmt); 1687 1688/* 1689 * set_dumpable stores three-value SUID_DUMP_* into mm->flags. 1690 */ 1691void set_dumpable(struct mm_struct *mm, int value) 1692{ 1693 unsigned long old, new; 1694 1695 if (WARN_ON((unsigned)value > SUID_DUMP_ROOT)) 1696 return; 1697 1698 do { 1699 old = ACCESS_ONCE(mm->flags); 1700 new = (old & ~MMF_DUMPABLE_MASK) | value; 1701 } while (cmpxchg(&mm->flags, old, new) != old); 1702} 1703 1704SYSCALL_DEFINE3(execve, 1705 const char __user *, filename, 1706 const char __user *const __user *, argv, 1707 const char __user *const __user *, envp) 1708{ 1709 return do_execve(getname(filename), argv, envp); 1710} 1711 1712SYSCALL_DEFINE5(execveat, 1713 int, fd, const char __user *, filename, 1714 const char __user *const __user *, argv, 1715 const char __user *const __user *, envp, 1716 int, flags) 1717{ 1718 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0; 1719 1720 return do_execveat(fd, 1721 getname_flags(filename, lookup_flags, NULL), 1722 argv, envp, flags); 1723} 1724 1725#ifdef CONFIG_COMPAT 1726COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename, 1727 const compat_uptr_t __user *, argv, 1728 const compat_uptr_t __user *, envp) 1729{ 1730 return compat_do_execve(getname(filename), argv, envp); 1731} 1732 1733COMPAT_SYSCALL_DEFINE5(execveat, int, fd, 1734 const char __user *, filename, 1735 const compat_uptr_t __user *, argv, 1736 const compat_uptr_t __user *, envp, 1737 int, flags) 1738{ 1739 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0; 1740 1741 return compat_do_execveat(fd, 1742 getname_flags(filename, lookup_flags, NULL), 1743 argv, envp, flags); 1744} 1745#endif 1746