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