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/smp_lock.h> 32 #include <linux/swap.h> 33 #include <linux/string.h> 34 #include <linux/init.h> 35 #include <linux/pagemap.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/ima.h> 49 #include <linux/syscalls.h> 50 #include <linux/tsacct_kern.h> 51 #include <linux/cn_proc.h> 52 #include <linux/audit.h> 53 #include <linux/tracehook.h> 54 #include <linux/kmod.h> 55 #include <linux/fsnotify.h> 56 #include <linux/fs_struct.h> 57 58 #include <asm/uaccess.h> 59 #include <asm/mmu_context.h> 60 #include <asm/tlb.h> 61 #include "internal.h" 62 63 int core_uses_pid; 64 char core_pattern[CORENAME_MAX_SIZE] = "core"; 65 int suid_dumpable = 0; 66 67 /* The maximal length of core_pattern is also specified in sysctl.c */ 68 69 static LIST_HEAD(formats); 70 static DEFINE_RWLOCK(binfmt_lock); 71 72 int register_binfmt(struct linux_binfmt * fmt) 73 { 74 if (!fmt) 75 return -EINVAL; 76 write_lock(&binfmt_lock); 77 list_add(&fmt->lh, &formats); 78 write_unlock(&binfmt_lock); 79 return 0; 80 } 81 82 EXPORT_SYMBOL(register_binfmt); 83 84 void unregister_binfmt(struct linux_binfmt * fmt) 85 { 86 write_lock(&binfmt_lock); 87 list_del(&fmt->lh); 88 write_unlock(&binfmt_lock); 89 } 90 91 EXPORT_SYMBOL(unregister_binfmt); 92 93 static inline void put_binfmt(struct linux_binfmt * fmt) 94 { 95 module_put(fmt->module); 96 } 97 98 /* 99 * Note that a shared library must be both readable and executable due to 100 * security reasons. 101 * 102 * Also note that we take the address to load from from the file itself. 103 */ 104 SYSCALL_DEFINE1(uselib, const char __user *, library) 105 { 106 struct file *file; 107 struct nameidata nd; 108 char *tmp = getname(library); 109 int error = PTR_ERR(tmp); 110 111 if (!IS_ERR(tmp)) { 112 error = path_lookup_open(AT_FDCWD, tmp, 113 LOOKUP_FOLLOW, &nd, 114 FMODE_READ|FMODE_EXEC); 115 putname(tmp); 116 } 117 if (error) 118 goto out; 119 120 error = -EINVAL; 121 if (!S_ISREG(nd.path.dentry->d_inode->i_mode)) 122 goto exit; 123 124 error = -EACCES; 125 if (nd.path.mnt->mnt_flags & MNT_NOEXEC) 126 goto exit; 127 128 error = inode_permission(nd.path.dentry->d_inode, 129 MAY_READ | MAY_EXEC | MAY_OPEN); 130 if (error) 131 goto exit; 132 error = ima_path_check(&nd.path, MAY_READ | MAY_EXEC | MAY_OPEN); 133 if (error) 134 goto exit; 135 136 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE); 137 error = PTR_ERR(file); 138 if (IS_ERR(file)) 139 goto out; 140 141 fsnotify_open(file->f_path.dentry); 142 143 error = -ENOEXEC; 144 if(file->f_op) { 145 struct linux_binfmt * fmt; 146 147 read_lock(&binfmt_lock); 148 list_for_each_entry(fmt, &formats, lh) { 149 if (!fmt->load_shlib) 150 continue; 151 if (!try_module_get(fmt->module)) 152 continue; 153 read_unlock(&binfmt_lock); 154 error = fmt->load_shlib(file); 155 read_lock(&binfmt_lock); 156 put_binfmt(fmt); 157 if (error != -ENOEXEC) 158 break; 159 } 160 read_unlock(&binfmt_lock); 161 } 162 fput(file); 163 out: 164 return error; 165 exit: 166 release_open_intent(&nd); 167 path_put(&nd.path); 168 goto out; 169 } 170 171 #ifdef CONFIG_MMU 172 173 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 174 int write) 175 { 176 struct page *page; 177 int ret; 178 179 #ifdef CONFIG_STACK_GROWSUP 180 if (write) { 181 ret = expand_stack_downwards(bprm->vma, pos); 182 if (ret < 0) 183 return NULL; 184 } 185 #endif 186 ret = get_user_pages(current, bprm->mm, pos, 187 1, write, 1, &page, NULL); 188 if (ret <= 0) 189 return NULL; 190 191 if (write) { 192 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; 193 struct rlimit *rlim; 194 195 /* 196 * We've historically supported up to 32 pages (ARG_MAX) 197 * of argument strings even with small stacks 198 */ 199 if (size <= ARG_MAX) 200 return page; 201 202 /* 203 * Limit to 1/4-th the stack size for the argv+env strings. 204 * This ensures that: 205 * - the remaining binfmt code will not run out of stack space, 206 * - the program will have a reasonable amount of stack left 207 * to work from. 208 */ 209 rlim = current->signal->rlim; 210 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) { 211 put_page(page); 212 return NULL; 213 } 214 } 215 216 return page; 217 } 218 219 static void put_arg_page(struct page *page) 220 { 221 put_page(page); 222 } 223 224 static void free_arg_page(struct linux_binprm *bprm, int i) 225 { 226 } 227 228 static void free_arg_pages(struct linux_binprm *bprm) 229 { 230 } 231 232 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 233 struct page *page) 234 { 235 flush_cache_page(bprm->vma, pos, page_to_pfn(page)); 236 } 237 238 static int __bprm_mm_init(struct linux_binprm *bprm) 239 { 240 int err; 241 struct vm_area_struct *vma = NULL; 242 struct mm_struct *mm = bprm->mm; 243 244 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 245 if (!vma) 246 return -ENOMEM; 247 248 down_write(&mm->mmap_sem); 249 vma->vm_mm = mm; 250 251 /* 252 * Place the stack at the largest stack address the architecture 253 * supports. Later, we'll move this to an appropriate place. We don't 254 * use STACK_TOP because that can depend on attributes which aren't 255 * configured yet. 256 */ 257 vma->vm_end = STACK_TOP_MAX; 258 vma->vm_start = vma->vm_end - PAGE_SIZE; 259 vma->vm_flags = VM_STACK_FLAGS; 260 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 261 err = insert_vm_struct(mm, vma); 262 if (err) 263 goto err; 264 265 mm->stack_vm = mm->total_vm = 1; 266 up_write(&mm->mmap_sem); 267 bprm->p = vma->vm_end - sizeof(void *); 268 return 0; 269 err: 270 up_write(&mm->mmap_sem); 271 bprm->vma = NULL; 272 kmem_cache_free(vm_area_cachep, vma); 273 return err; 274 } 275 276 static bool valid_arg_len(struct linux_binprm *bprm, long len) 277 { 278 return len <= MAX_ARG_STRLEN; 279 } 280 281 #else 282 283 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 284 int write) 285 { 286 struct page *page; 287 288 page = bprm->page[pos / PAGE_SIZE]; 289 if (!page && write) { 290 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 291 if (!page) 292 return NULL; 293 bprm->page[pos / PAGE_SIZE] = page; 294 } 295 296 return page; 297 } 298 299 static void put_arg_page(struct page *page) 300 { 301 } 302 303 static void free_arg_page(struct linux_binprm *bprm, int i) 304 { 305 if (bprm->page[i]) { 306 __free_page(bprm->page[i]); 307 bprm->page[i] = NULL; 308 } 309 } 310 311 static void free_arg_pages(struct linux_binprm *bprm) 312 { 313 int i; 314 315 for (i = 0; i < MAX_ARG_PAGES; i++) 316 free_arg_page(bprm, i); 317 } 318 319 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 320 struct page *page) 321 { 322 } 323 324 static int __bprm_mm_init(struct linux_binprm *bprm) 325 { 326 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 327 return 0; 328 } 329 330 static bool valid_arg_len(struct linux_binprm *bprm, long len) 331 { 332 return len <= bprm->p; 333 } 334 335 #endif /* CONFIG_MMU */ 336 337 /* 338 * Create a new mm_struct and populate it with a temporary stack 339 * vm_area_struct. We don't have enough context at this point to set the stack 340 * flags, permissions, and offset, so we use temporary values. We'll update 341 * them later in setup_arg_pages(). 342 */ 343 int bprm_mm_init(struct linux_binprm *bprm) 344 { 345 int err; 346 struct mm_struct *mm = NULL; 347 348 bprm->mm = mm = mm_alloc(); 349 err = -ENOMEM; 350 if (!mm) 351 goto err; 352 353 err = init_new_context(current, mm); 354 if (err) 355 goto err; 356 357 err = __bprm_mm_init(bprm); 358 if (err) 359 goto err; 360 361 return 0; 362 363 err: 364 if (mm) { 365 bprm->mm = NULL; 366 mmdrop(mm); 367 } 368 369 return err; 370 } 371 372 /* 373 * count() counts the number of strings in array ARGV. 374 */ 375 static int count(char __user * __user * argv, int max) 376 { 377 int i = 0; 378 379 if (argv != NULL) { 380 for (;;) { 381 char __user * p; 382 383 if (get_user(p, argv)) 384 return -EFAULT; 385 if (!p) 386 break; 387 argv++; 388 if (i++ >= max) 389 return -E2BIG; 390 cond_resched(); 391 } 392 } 393 return i; 394 } 395 396 /* 397 * 'copy_strings()' copies argument/environment strings from the old 398 * processes's memory to the new process's stack. The call to get_user_pages() 399 * ensures the destination page is created and not swapped out. 400 */ 401 static int copy_strings(int argc, char __user * __user * argv, 402 struct linux_binprm *bprm) 403 { 404 struct page *kmapped_page = NULL; 405 char *kaddr = NULL; 406 unsigned long kpos = 0; 407 int ret; 408 409 while (argc-- > 0) { 410 char __user *str; 411 int len; 412 unsigned long pos; 413 414 if (get_user(str, argv+argc) || 415 !(len = strnlen_user(str, MAX_ARG_STRLEN))) { 416 ret = -EFAULT; 417 goto out; 418 } 419 420 if (!valid_arg_len(bprm, len)) { 421 ret = -E2BIG; 422 goto out; 423 } 424 425 /* We're going to work our way backwords. */ 426 pos = bprm->p; 427 str += len; 428 bprm->p -= len; 429 430 while (len > 0) { 431 int offset, bytes_to_copy; 432 433 offset = pos % PAGE_SIZE; 434 if (offset == 0) 435 offset = PAGE_SIZE; 436 437 bytes_to_copy = offset; 438 if (bytes_to_copy > len) 439 bytes_to_copy = len; 440 441 offset -= bytes_to_copy; 442 pos -= bytes_to_copy; 443 str -= bytes_to_copy; 444 len -= bytes_to_copy; 445 446 if (!kmapped_page || kpos != (pos & PAGE_MASK)) { 447 struct page *page; 448 449 page = get_arg_page(bprm, pos, 1); 450 if (!page) { 451 ret = -E2BIG; 452 goto out; 453 } 454 455 if (kmapped_page) { 456 flush_kernel_dcache_page(kmapped_page); 457 kunmap(kmapped_page); 458 put_arg_page(kmapped_page); 459 } 460 kmapped_page = page; 461 kaddr = kmap(kmapped_page); 462 kpos = pos & PAGE_MASK; 463 flush_arg_page(bprm, kpos, kmapped_page); 464 } 465 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { 466 ret = -EFAULT; 467 goto out; 468 } 469 } 470 } 471 ret = 0; 472 out: 473 if (kmapped_page) { 474 flush_kernel_dcache_page(kmapped_page); 475 kunmap(kmapped_page); 476 put_arg_page(kmapped_page); 477 } 478 return ret; 479 } 480 481 /* 482 * Like copy_strings, but get argv and its values from kernel memory. 483 */ 484 int copy_strings_kernel(int argc,char ** argv, 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, (char __user * __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 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL); 532 533 /* 534 * move the page tables downwards, on failure we rely on 535 * process cleanup to remove whatever mess we made. 536 */ 537 if (length != move_page_tables(vma, old_start, 538 vma, new_start, length)) 539 return -ENOMEM; 540 541 lru_add_drain(); 542 tlb = tlb_gather_mmu(mm, 0); 543 if (new_end > old_start) { 544 /* 545 * when the old and new regions overlap clear from new_end. 546 */ 547 free_pgd_range(tlb, new_end, old_end, new_end, 548 vma->vm_next ? vma->vm_next->vm_start : 0); 549 } else { 550 /* 551 * otherwise, clean from old_start; this is done to not touch 552 * the address space in [new_end, old_start) some architectures 553 * have constraints on va-space that make this illegal (IA64) - 554 * for the others its just a little faster. 555 */ 556 free_pgd_range(tlb, old_start, old_end, new_end, 557 vma->vm_next ? vma->vm_next->vm_start : 0); 558 } 559 tlb_finish_mmu(tlb, new_end, old_end); 560 561 /* 562 * shrink the vma to just the new range. 563 */ 564 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); 565 566 return 0; 567 } 568 569 #define EXTRA_STACK_VM_PAGES 20 /* random */ 570 571 /* 572 * Finalizes the stack vm_area_struct. The flags and permissions are updated, 573 * the stack is optionally relocated, and some extra space is added. 574 */ 575 int setup_arg_pages(struct linux_binprm *bprm, 576 unsigned long stack_top, 577 int executable_stack) 578 { 579 unsigned long ret; 580 unsigned long stack_shift; 581 struct mm_struct *mm = current->mm; 582 struct vm_area_struct *vma = bprm->vma; 583 struct vm_area_struct *prev = NULL; 584 unsigned long vm_flags; 585 unsigned long stack_base; 586 587 #ifdef CONFIG_STACK_GROWSUP 588 /* Limit stack size to 1GB */ 589 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max; 590 if (stack_base > (1 << 30)) 591 stack_base = 1 << 30; 592 593 /* Make sure we didn't let the argument array grow too large. */ 594 if (vma->vm_end - vma->vm_start > stack_base) 595 return -ENOMEM; 596 597 stack_base = PAGE_ALIGN(stack_top - stack_base); 598 599 stack_shift = vma->vm_start - stack_base; 600 mm->arg_start = bprm->p - stack_shift; 601 bprm->p = vma->vm_end - stack_shift; 602 #else 603 stack_top = arch_align_stack(stack_top); 604 stack_top = PAGE_ALIGN(stack_top); 605 stack_shift = vma->vm_end - stack_top; 606 607 bprm->p -= stack_shift; 608 mm->arg_start = bprm->p; 609 #endif 610 611 if (bprm->loader) 612 bprm->loader -= stack_shift; 613 bprm->exec -= stack_shift; 614 615 down_write(&mm->mmap_sem); 616 vm_flags = VM_STACK_FLAGS; 617 618 /* 619 * Adjust stack execute permissions; explicitly enable for 620 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone 621 * (arch default) otherwise. 622 */ 623 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 624 vm_flags |= VM_EXEC; 625 else if (executable_stack == EXSTACK_DISABLE_X) 626 vm_flags &= ~VM_EXEC; 627 vm_flags |= mm->def_flags; 628 629 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, 630 vm_flags); 631 if (ret) 632 goto out_unlock; 633 BUG_ON(prev != vma); 634 635 /* Move stack pages down in memory. */ 636 if (stack_shift) { 637 ret = shift_arg_pages(vma, stack_shift); 638 if (ret) { 639 up_write(&mm->mmap_sem); 640 return ret; 641 } 642 } 643 644 #ifdef CONFIG_STACK_GROWSUP 645 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE; 646 #else 647 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE; 648 #endif 649 ret = expand_stack(vma, stack_base); 650 if (ret) 651 ret = -EFAULT; 652 653 out_unlock: 654 up_write(&mm->mmap_sem); 655 return 0; 656 } 657 EXPORT_SYMBOL(setup_arg_pages); 658 659 #endif /* CONFIG_MMU */ 660 661 struct file *open_exec(const char *name) 662 { 663 struct nameidata nd; 664 struct file *file; 665 int err; 666 667 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, 668 FMODE_READ|FMODE_EXEC); 669 if (err) 670 goto out; 671 672 err = -EACCES; 673 if (!S_ISREG(nd.path.dentry->d_inode->i_mode)) 674 goto out_path_put; 675 676 if (nd.path.mnt->mnt_flags & MNT_NOEXEC) 677 goto out_path_put; 678 679 err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN); 680 if (err) 681 goto out_path_put; 682 err = ima_path_check(&nd.path, MAY_EXEC | MAY_OPEN); 683 if (err) 684 goto out_path_put; 685 686 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE); 687 if (IS_ERR(file)) 688 return file; 689 690 fsnotify_open(file->f_path.dentry); 691 692 err = deny_write_access(file); 693 if (err) { 694 fput(file); 695 goto out; 696 } 697 698 return file; 699 700 out_path_put: 701 release_open_intent(&nd); 702 path_put(&nd.path); 703 out: 704 return ERR_PTR(err); 705 } 706 EXPORT_SYMBOL(open_exec); 707 708 int kernel_read(struct file *file, unsigned long offset, 709 char *addr, unsigned long count) 710 { 711 mm_segment_t old_fs; 712 loff_t pos = offset; 713 int result; 714 715 old_fs = get_fs(); 716 set_fs(get_ds()); 717 /* The cast to a user pointer is valid due to the set_fs() */ 718 result = vfs_read(file, (void __user *)addr, count, &pos); 719 set_fs(old_fs); 720 return result; 721 } 722 723 EXPORT_SYMBOL(kernel_read); 724 725 static int exec_mmap(struct mm_struct *mm) 726 { 727 struct task_struct *tsk; 728 struct mm_struct * old_mm, *active_mm; 729 730 /* Notify parent that we're no longer interested in the old VM */ 731 tsk = current; 732 old_mm = current->mm; 733 mm_release(tsk, old_mm); 734 735 if (old_mm) { 736 /* 737 * Make sure that if there is a core dump in progress 738 * for the old mm, we get out and die instead of going 739 * through with the exec. We must hold mmap_sem around 740 * checking core_state and changing tsk->mm. 741 */ 742 down_read(&old_mm->mmap_sem); 743 if (unlikely(old_mm->core_state)) { 744 up_read(&old_mm->mmap_sem); 745 return -EINTR; 746 } 747 } 748 task_lock(tsk); 749 active_mm = tsk->active_mm; 750 tsk->mm = mm; 751 tsk->active_mm = mm; 752 activate_mm(active_mm, mm); 753 task_unlock(tsk); 754 arch_pick_mmap_layout(mm); 755 if (old_mm) { 756 up_read(&old_mm->mmap_sem); 757 BUG_ON(active_mm != old_mm); 758 mm_update_next_owner(old_mm); 759 mmput(old_mm); 760 return 0; 761 } 762 mmdrop(active_mm); 763 return 0; 764 } 765 766 /* 767 * This function makes sure the current process has its own signal table, 768 * so that flush_signal_handlers can later reset the handlers without 769 * disturbing other processes. (Other processes might share the signal 770 * table via the CLONE_SIGHAND option to clone().) 771 */ 772 static int de_thread(struct task_struct *tsk) 773 { 774 struct signal_struct *sig = tsk->signal; 775 struct sighand_struct *oldsighand = tsk->sighand; 776 spinlock_t *lock = &oldsighand->siglock; 777 int count; 778 779 if (thread_group_empty(tsk)) 780 goto no_thread_group; 781 782 /* 783 * Kill all other threads in the thread group. 784 */ 785 spin_lock_irq(lock); 786 if (signal_group_exit(sig)) { 787 /* 788 * Another group action in progress, just 789 * return so that the signal is processed. 790 */ 791 spin_unlock_irq(lock); 792 return -EAGAIN; 793 } 794 sig->group_exit_task = tsk; 795 zap_other_threads(tsk); 796 797 /* Account for the thread group leader hanging around: */ 798 count = thread_group_leader(tsk) ? 1 : 2; 799 sig->notify_count = count; 800 while (atomic_read(&sig->count) > count) { 801 __set_current_state(TASK_UNINTERRUPTIBLE); 802 spin_unlock_irq(lock); 803 schedule(); 804 spin_lock_irq(lock); 805 } 806 spin_unlock_irq(lock); 807 808 /* 809 * At this point all other threads have exited, all we have to 810 * do is to wait for the thread group leader to become inactive, 811 * and to assume its PID: 812 */ 813 if (!thread_group_leader(tsk)) { 814 struct task_struct *leader = tsk->group_leader; 815 816 sig->notify_count = -1; /* for exit_notify() */ 817 for (;;) { 818 write_lock_irq(&tasklist_lock); 819 if (likely(leader->exit_state)) 820 break; 821 __set_current_state(TASK_UNINTERRUPTIBLE); 822 write_unlock_irq(&tasklist_lock); 823 schedule(); 824 } 825 826 /* 827 * The only record we have of the real-time age of a 828 * process, regardless of execs it's done, is start_time. 829 * All the past CPU time is accumulated in signal_struct 830 * from sister threads now dead. But in this non-leader 831 * exec, nothing survives from the original leader thread, 832 * whose birth marks the true age of this process now. 833 * When we take on its identity by switching to its PID, we 834 * also take its birthdate (always earlier than our own). 835 */ 836 tsk->start_time = leader->start_time; 837 838 BUG_ON(!same_thread_group(leader, tsk)); 839 BUG_ON(has_group_leader_pid(tsk)); 840 /* 841 * An exec() starts a new thread group with the 842 * TGID of the previous thread group. Rehash the 843 * two threads with a switched PID, and release 844 * the former thread group leader: 845 */ 846 847 /* Become a process group leader with the old leader's pid. 848 * The old leader becomes a thread of the this thread group. 849 * Note: The old leader also uses this pid until release_task 850 * is called. Odd but simple and correct. 851 */ 852 detach_pid(tsk, PIDTYPE_PID); 853 tsk->pid = leader->pid; 854 attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); 855 transfer_pid(leader, tsk, PIDTYPE_PGID); 856 transfer_pid(leader, tsk, PIDTYPE_SID); 857 list_replace_rcu(&leader->tasks, &tsk->tasks); 858 859 tsk->group_leader = tsk; 860 leader->group_leader = tsk; 861 862 tsk->exit_signal = SIGCHLD; 863 864 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 865 leader->exit_state = EXIT_DEAD; 866 write_unlock_irq(&tasklist_lock); 867 868 release_task(leader); 869 } 870 871 sig->group_exit_task = NULL; 872 sig->notify_count = 0; 873 874 no_thread_group: 875 exit_itimers(sig); 876 flush_itimer_signals(); 877 878 if (atomic_read(&oldsighand->count) != 1) { 879 struct sighand_struct *newsighand; 880 /* 881 * This ->sighand is shared with the CLONE_SIGHAND 882 * but not CLONE_THREAD task, switch to the new one. 883 */ 884 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 885 if (!newsighand) 886 return -ENOMEM; 887 888 atomic_set(&newsighand->count, 1); 889 memcpy(newsighand->action, oldsighand->action, 890 sizeof(newsighand->action)); 891 892 write_lock_irq(&tasklist_lock); 893 spin_lock(&oldsighand->siglock); 894 rcu_assign_pointer(tsk->sighand, newsighand); 895 spin_unlock(&oldsighand->siglock); 896 write_unlock_irq(&tasklist_lock); 897 898 __cleanup_sighand(oldsighand); 899 } 900 901 BUG_ON(!thread_group_leader(tsk)); 902 return 0; 903 } 904 905 /* 906 * These functions flushes out all traces of the currently running executable 907 * so that a new one can be started 908 */ 909 static void flush_old_files(struct files_struct * files) 910 { 911 long j = -1; 912 struct fdtable *fdt; 913 914 spin_lock(&files->file_lock); 915 for (;;) { 916 unsigned long set, i; 917 918 j++; 919 i = j * __NFDBITS; 920 fdt = files_fdtable(files); 921 if (i >= fdt->max_fds) 922 break; 923 set = fdt->close_on_exec->fds_bits[j]; 924 if (!set) 925 continue; 926 fdt->close_on_exec->fds_bits[j] = 0; 927 spin_unlock(&files->file_lock); 928 for ( ; set ; i++,set >>= 1) { 929 if (set & 1) { 930 sys_close(i); 931 } 932 } 933 spin_lock(&files->file_lock); 934 935 } 936 spin_unlock(&files->file_lock); 937 } 938 939 char *get_task_comm(char *buf, struct task_struct *tsk) 940 { 941 /* buf must be at least sizeof(tsk->comm) in size */ 942 task_lock(tsk); 943 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 944 task_unlock(tsk); 945 return buf; 946 } 947 948 void set_task_comm(struct task_struct *tsk, char *buf) 949 { 950 task_lock(tsk); 951 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 952 task_unlock(tsk); 953 } 954 955 int flush_old_exec(struct linux_binprm * bprm) 956 { 957 char * name; 958 int i, ch, retval; 959 char tcomm[sizeof(current->comm)]; 960 961 /* 962 * Make sure we have a private signal table and that 963 * we are unassociated from the previous thread group. 964 */ 965 retval = de_thread(current); 966 if (retval) 967 goto out; 968 969 set_mm_exe_file(bprm->mm, bprm->file); 970 971 /* 972 * Release all of the old mmap stuff 973 */ 974 retval = exec_mmap(bprm->mm); 975 if (retval) 976 goto out; 977 978 bprm->mm = NULL; /* We're using it now */ 979 980 /* This is the point of no return */ 981 current->sas_ss_sp = current->sas_ss_size = 0; 982 983 if (current_euid() == current_uid() && current_egid() == current_gid()) 984 set_dumpable(current->mm, 1); 985 else 986 set_dumpable(current->mm, suid_dumpable); 987 988 name = bprm->filename; 989 990 /* Copies the binary name from after last slash */ 991 for (i=0; (ch = *(name++)) != '\0';) { 992 if (ch == '/') 993 i = 0; /* overwrite what we wrote */ 994 else 995 if (i < (sizeof(tcomm) - 1)) 996 tcomm[i++] = ch; 997 } 998 tcomm[i] = '\0'; 999 set_task_comm(current, tcomm); 1000 1001 current->flags &= ~PF_RANDOMIZE; 1002 flush_thread(); 1003 1004 /* Set the new mm task size. We have to do that late because it may 1005 * depend on TIF_32BIT which is only updated in flush_thread() on 1006 * some architectures like powerpc 1007 */ 1008 current->mm->task_size = TASK_SIZE; 1009 1010 /* install the new credentials */ 1011 if (bprm->cred->uid != current_euid() || 1012 bprm->cred->gid != current_egid()) { 1013 current->pdeath_signal = 0; 1014 } else if (file_permission(bprm->file, MAY_READ) || 1015 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) { 1016 set_dumpable(current->mm, suid_dumpable); 1017 } 1018 1019 current->personality &= ~bprm->per_clear; 1020 1021 /* An exec changes our domain. We are no longer part of the thread 1022 group */ 1023 1024 current->self_exec_id++; 1025 1026 flush_signal_handlers(current, 0); 1027 flush_old_files(current->files); 1028 1029 return 0; 1030 1031 out: 1032 return retval; 1033 } 1034 1035 EXPORT_SYMBOL(flush_old_exec); 1036 1037 /* 1038 * install the new credentials for this executable 1039 */ 1040 void install_exec_creds(struct linux_binprm *bprm) 1041 { 1042 security_bprm_committing_creds(bprm); 1043 1044 commit_creds(bprm->cred); 1045 bprm->cred = NULL; 1046 1047 /* cred_exec_mutex must be held at least to this point to prevent 1048 * ptrace_attach() from altering our determination of the task's 1049 * credentials; any time after this it may be unlocked */ 1050 1051 security_bprm_committed_creds(bprm); 1052 } 1053 EXPORT_SYMBOL(install_exec_creds); 1054 1055 /* 1056 * determine how safe it is to execute the proposed program 1057 * - the caller must hold current->cred_exec_mutex to protect against 1058 * PTRACE_ATTACH 1059 */ 1060 int check_unsafe_exec(struct linux_binprm *bprm) 1061 { 1062 struct task_struct *p = current, *t; 1063 unsigned long flags; 1064 unsigned n_fs; 1065 int res = 0; 1066 1067 bprm->unsafe = tracehook_unsafe_exec(p); 1068 1069 n_fs = 1; 1070 write_lock(&p->fs->lock); 1071 lock_task_sighand(p, &flags); 1072 for (t = next_thread(p); t != p; t = next_thread(t)) { 1073 if (t->fs == p->fs) 1074 n_fs++; 1075 } 1076 1077 if (p->fs->users > n_fs) { 1078 bprm->unsafe |= LSM_UNSAFE_SHARE; 1079 } else { 1080 if (p->fs->in_exec) 1081 res = -EAGAIN; 1082 p->fs->in_exec = 1; 1083 } 1084 1085 unlock_task_sighand(p, &flags); 1086 write_unlock(&p->fs->lock); 1087 1088 return res; 1089 } 1090 1091 /* 1092 * Fill the binprm structure from the inode. 1093 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1094 * 1095 * This may be called multiple times for binary chains (scripts for example). 1096 */ 1097 int prepare_binprm(struct linux_binprm *bprm) 1098 { 1099 umode_t mode; 1100 struct inode * inode = bprm->file->f_path.dentry->d_inode; 1101 int retval; 1102 1103 mode = inode->i_mode; 1104 if (bprm->file->f_op == NULL) 1105 return -EACCES; 1106 1107 /* clear any previous set[ug]id data from a previous binary */ 1108 bprm->cred->euid = current_euid(); 1109 bprm->cred->egid = current_egid(); 1110 1111 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { 1112 /* Set-uid? */ 1113 if (mode & S_ISUID) { 1114 bprm->per_clear |= PER_CLEAR_ON_SETID; 1115 bprm->cred->euid = inode->i_uid; 1116 } 1117 1118 /* Set-gid? */ 1119 /* 1120 * If setgid is set but no group execute bit then this 1121 * is a candidate for mandatory locking, not a setgid 1122 * executable. 1123 */ 1124 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1125 bprm->per_clear |= PER_CLEAR_ON_SETID; 1126 bprm->cred->egid = inode->i_gid; 1127 } 1128 } 1129 1130 /* fill in binprm security blob */ 1131 retval = security_bprm_set_creds(bprm); 1132 if (retval) 1133 return retval; 1134 bprm->cred_prepared = 1; 1135 1136 memset(bprm->buf, 0, BINPRM_BUF_SIZE); 1137 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); 1138 } 1139 1140 EXPORT_SYMBOL(prepare_binprm); 1141 1142 /* 1143 * Arguments are '\0' separated strings found at the location bprm->p 1144 * points to; chop off the first by relocating brpm->p to right after 1145 * the first '\0' encountered. 1146 */ 1147 int remove_arg_zero(struct linux_binprm *bprm) 1148 { 1149 int ret = 0; 1150 unsigned long offset; 1151 char *kaddr; 1152 struct page *page; 1153 1154 if (!bprm->argc) 1155 return 0; 1156 1157 do { 1158 offset = bprm->p & ~PAGE_MASK; 1159 page = get_arg_page(bprm, bprm->p, 0); 1160 if (!page) { 1161 ret = -EFAULT; 1162 goto out; 1163 } 1164 kaddr = kmap_atomic(page, KM_USER0); 1165 1166 for (; offset < PAGE_SIZE && kaddr[offset]; 1167 offset++, bprm->p++) 1168 ; 1169 1170 kunmap_atomic(kaddr, KM_USER0); 1171 put_arg_page(page); 1172 1173 if (offset == PAGE_SIZE) 1174 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1175 } while (offset == PAGE_SIZE); 1176 1177 bprm->p++; 1178 bprm->argc--; 1179 ret = 0; 1180 1181 out: 1182 return ret; 1183 } 1184 EXPORT_SYMBOL(remove_arg_zero); 1185 1186 /* 1187 * cycle the list of binary formats handler, until one recognizes the image 1188 */ 1189 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) 1190 { 1191 unsigned int depth = bprm->recursion_depth; 1192 int try,retval; 1193 struct linux_binfmt *fmt; 1194 1195 retval = security_bprm_check(bprm); 1196 if (retval) 1197 return retval; 1198 retval = ima_bprm_check(bprm); 1199 if (retval) 1200 return retval; 1201 1202 /* kernel module loader fixup */ 1203 /* so we don't try to load run modprobe in kernel space. */ 1204 set_fs(USER_DS); 1205 1206 retval = audit_bprm(bprm); 1207 if (retval) 1208 return retval; 1209 1210 retval = -ENOENT; 1211 for (try=0; try<2; try++) { 1212 read_lock(&binfmt_lock); 1213 list_for_each_entry(fmt, &formats, lh) { 1214 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; 1215 if (!fn) 1216 continue; 1217 if (!try_module_get(fmt->module)) 1218 continue; 1219 read_unlock(&binfmt_lock); 1220 retval = fn(bprm, regs); 1221 /* 1222 * Restore the depth counter to its starting value 1223 * in this call, so we don't have to rely on every 1224 * load_binary function to restore it on return. 1225 */ 1226 bprm->recursion_depth = depth; 1227 if (retval >= 0) { 1228 if (depth == 0) 1229 tracehook_report_exec(fmt, bprm, regs); 1230 put_binfmt(fmt); 1231 allow_write_access(bprm->file); 1232 if (bprm->file) 1233 fput(bprm->file); 1234 bprm->file = NULL; 1235 current->did_exec = 1; 1236 proc_exec_connector(current); 1237 return retval; 1238 } 1239 read_lock(&binfmt_lock); 1240 put_binfmt(fmt); 1241 if (retval != -ENOEXEC || bprm->mm == NULL) 1242 break; 1243 if (!bprm->file) { 1244 read_unlock(&binfmt_lock); 1245 return retval; 1246 } 1247 } 1248 read_unlock(&binfmt_lock); 1249 if (retval != -ENOEXEC || bprm->mm == NULL) { 1250 break; 1251 #ifdef CONFIG_MODULES 1252 } else { 1253 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1254 if (printable(bprm->buf[0]) && 1255 printable(bprm->buf[1]) && 1256 printable(bprm->buf[2]) && 1257 printable(bprm->buf[3])) 1258 break; /* -ENOEXEC */ 1259 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1260 #endif 1261 } 1262 } 1263 return retval; 1264 } 1265 1266 EXPORT_SYMBOL(search_binary_handler); 1267 1268 void free_bprm(struct linux_binprm *bprm) 1269 { 1270 free_arg_pages(bprm); 1271 if (bprm->cred) 1272 abort_creds(bprm->cred); 1273 kfree(bprm); 1274 } 1275 1276 /* 1277 * sys_execve() executes a new program. 1278 */ 1279 int do_execve(char * filename, 1280 char __user *__user *argv, 1281 char __user *__user *envp, 1282 struct pt_regs * regs) 1283 { 1284 struct linux_binprm *bprm; 1285 struct file *file; 1286 struct files_struct *displaced; 1287 int retval; 1288 1289 retval = unshare_files(&displaced); 1290 if (retval) 1291 goto out_ret; 1292 1293 retval = -ENOMEM; 1294 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1295 if (!bprm) 1296 goto out_files; 1297 1298 retval = mutex_lock_interruptible(¤t->cred_exec_mutex); 1299 if (retval < 0) 1300 goto out_free; 1301 current->in_execve = 1; 1302 1303 retval = -ENOMEM; 1304 bprm->cred = prepare_exec_creds(); 1305 if (!bprm->cred) 1306 goto out_unlock; 1307 1308 retval = check_unsafe_exec(bprm); 1309 if (retval) 1310 goto out_unlock; 1311 1312 file = open_exec(filename); 1313 retval = PTR_ERR(file); 1314 if (IS_ERR(file)) 1315 goto out_unmark; 1316 1317 sched_exec(); 1318 1319 bprm->file = file; 1320 bprm->filename = filename; 1321 bprm->interp = filename; 1322 1323 retval = bprm_mm_init(bprm); 1324 if (retval) 1325 goto out_file; 1326 1327 bprm->argc = count(argv, MAX_ARG_STRINGS); 1328 if ((retval = bprm->argc) < 0) 1329 goto out; 1330 1331 bprm->envc = count(envp, MAX_ARG_STRINGS); 1332 if ((retval = bprm->envc) < 0) 1333 goto out; 1334 1335 retval = prepare_binprm(bprm); 1336 if (retval < 0) 1337 goto out; 1338 1339 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1340 if (retval < 0) 1341 goto out; 1342 1343 bprm->exec = bprm->p; 1344 retval = copy_strings(bprm->envc, envp, bprm); 1345 if (retval < 0) 1346 goto out; 1347 1348 retval = copy_strings(bprm->argc, argv, bprm); 1349 if (retval < 0) 1350 goto out; 1351 1352 current->flags &= ~PF_KTHREAD; 1353 retval = search_binary_handler(bprm,regs); 1354 if (retval < 0) 1355 goto out; 1356 1357 /* execve succeeded */ 1358 write_lock(¤t->fs->lock); 1359 current->fs->in_exec = 0; 1360 write_unlock(¤t->fs->lock); 1361 current->in_execve = 0; 1362 mutex_unlock(¤t->cred_exec_mutex); 1363 acct_update_integrals(current); 1364 free_bprm(bprm); 1365 if (displaced) 1366 put_files_struct(displaced); 1367 return retval; 1368 1369 out: 1370 if (bprm->mm) 1371 mmput (bprm->mm); 1372 1373 out_file: 1374 if (bprm->file) { 1375 allow_write_access(bprm->file); 1376 fput(bprm->file); 1377 } 1378 1379 out_unmark: 1380 write_lock(¤t->fs->lock); 1381 current->fs->in_exec = 0; 1382 write_unlock(¤t->fs->lock); 1383 1384 out_unlock: 1385 current->in_execve = 0; 1386 mutex_unlock(¤t->cred_exec_mutex); 1387 1388 out_free: 1389 free_bprm(bprm); 1390 1391 out_files: 1392 if (displaced) 1393 reset_files_struct(displaced); 1394 out_ret: 1395 return retval; 1396 } 1397 1398 int set_binfmt(struct linux_binfmt *new) 1399 { 1400 struct linux_binfmt *old = current->binfmt; 1401 1402 if (new) { 1403 if (!try_module_get(new->module)) 1404 return -1; 1405 } 1406 current->binfmt = new; 1407 if (old) 1408 module_put(old->module); 1409 return 0; 1410 } 1411 1412 EXPORT_SYMBOL(set_binfmt); 1413 1414 /* format_corename will inspect the pattern parameter, and output a 1415 * name into corename, which must have space for at least 1416 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 1417 */ 1418 static int format_corename(char *corename, long signr) 1419 { 1420 const struct cred *cred = current_cred(); 1421 const char *pat_ptr = core_pattern; 1422 int ispipe = (*pat_ptr == '|'); 1423 char *out_ptr = corename; 1424 char *const out_end = corename + CORENAME_MAX_SIZE; 1425 int rc; 1426 int pid_in_pattern = 0; 1427 1428 /* Repeat as long as we have more pattern to process and more output 1429 space */ 1430 while (*pat_ptr) { 1431 if (*pat_ptr != '%') { 1432 if (out_ptr == out_end) 1433 goto out; 1434 *out_ptr++ = *pat_ptr++; 1435 } else { 1436 switch (*++pat_ptr) { 1437 case 0: 1438 goto out; 1439 /* Double percent, output one percent */ 1440 case '%': 1441 if (out_ptr == out_end) 1442 goto out; 1443 *out_ptr++ = '%'; 1444 break; 1445 /* pid */ 1446 case 'p': 1447 pid_in_pattern = 1; 1448 rc = snprintf(out_ptr, out_end - out_ptr, 1449 "%d", task_tgid_vnr(current)); 1450 if (rc > out_end - out_ptr) 1451 goto out; 1452 out_ptr += rc; 1453 break; 1454 /* uid */ 1455 case 'u': 1456 rc = snprintf(out_ptr, out_end - out_ptr, 1457 "%d", cred->uid); 1458 if (rc > out_end - out_ptr) 1459 goto out; 1460 out_ptr += rc; 1461 break; 1462 /* gid */ 1463 case 'g': 1464 rc = snprintf(out_ptr, out_end - out_ptr, 1465 "%d", cred->gid); 1466 if (rc > out_end - out_ptr) 1467 goto out; 1468 out_ptr += rc; 1469 break; 1470 /* signal that caused the coredump */ 1471 case 's': 1472 rc = snprintf(out_ptr, out_end - out_ptr, 1473 "%ld", signr); 1474 if (rc > out_end - out_ptr) 1475 goto out; 1476 out_ptr += rc; 1477 break; 1478 /* UNIX time of coredump */ 1479 case 't': { 1480 struct timeval tv; 1481 do_gettimeofday(&tv); 1482 rc = snprintf(out_ptr, out_end - out_ptr, 1483 "%lu", tv.tv_sec); 1484 if (rc > out_end - out_ptr) 1485 goto out; 1486 out_ptr += rc; 1487 break; 1488 } 1489 /* hostname */ 1490 case 'h': 1491 down_read(&uts_sem); 1492 rc = snprintf(out_ptr, out_end - out_ptr, 1493 "%s", utsname()->nodename); 1494 up_read(&uts_sem); 1495 if (rc > out_end - out_ptr) 1496 goto out; 1497 out_ptr += rc; 1498 break; 1499 /* executable */ 1500 case 'e': 1501 rc = snprintf(out_ptr, out_end - out_ptr, 1502 "%s", current->comm); 1503 if (rc > out_end - out_ptr) 1504 goto out; 1505 out_ptr += rc; 1506 break; 1507 /* core limit size */ 1508 case 'c': 1509 rc = snprintf(out_ptr, out_end - out_ptr, 1510 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur); 1511 if (rc > out_end - out_ptr) 1512 goto out; 1513 out_ptr += rc; 1514 break; 1515 default: 1516 break; 1517 } 1518 ++pat_ptr; 1519 } 1520 } 1521 /* Backward compatibility with core_uses_pid: 1522 * 1523 * If core_pattern does not include a %p (as is the default) 1524 * and core_uses_pid is set, then .%pid will be appended to 1525 * the filename. Do not do this for piped commands. */ 1526 if (!ispipe && !pid_in_pattern && core_uses_pid) { 1527 rc = snprintf(out_ptr, out_end - out_ptr, 1528 ".%d", task_tgid_vnr(current)); 1529 if (rc > out_end - out_ptr) 1530 goto out; 1531 out_ptr += rc; 1532 } 1533 out: 1534 *out_ptr = 0; 1535 return ispipe; 1536 } 1537 1538 static int zap_process(struct task_struct *start) 1539 { 1540 struct task_struct *t; 1541 int nr = 0; 1542 1543 start->signal->flags = SIGNAL_GROUP_EXIT; 1544 start->signal->group_stop_count = 0; 1545 1546 t = start; 1547 do { 1548 if (t != current && t->mm) { 1549 sigaddset(&t->pending.signal, SIGKILL); 1550 signal_wake_up(t, 1); 1551 nr++; 1552 } 1553 } while_each_thread(start, t); 1554 1555 return nr; 1556 } 1557 1558 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 1559 struct core_state *core_state, int exit_code) 1560 { 1561 struct task_struct *g, *p; 1562 unsigned long flags; 1563 int nr = -EAGAIN; 1564 1565 spin_lock_irq(&tsk->sighand->siglock); 1566 if (!signal_group_exit(tsk->signal)) { 1567 mm->core_state = core_state; 1568 tsk->signal->group_exit_code = exit_code; 1569 nr = zap_process(tsk); 1570 } 1571 spin_unlock_irq(&tsk->sighand->siglock); 1572 if (unlikely(nr < 0)) 1573 return nr; 1574 1575 if (atomic_read(&mm->mm_users) == nr + 1) 1576 goto done; 1577 /* 1578 * We should find and kill all tasks which use this mm, and we should 1579 * count them correctly into ->nr_threads. We don't take tasklist 1580 * lock, but this is safe wrt: 1581 * 1582 * fork: 1583 * None of sub-threads can fork after zap_process(leader). All 1584 * processes which were created before this point should be 1585 * visible to zap_threads() because copy_process() adds the new 1586 * process to the tail of init_task.tasks list, and lock/unlock 1587 * of ->siglock provides a memory barrier. 1588 * 1589 * do_exit: 1590 * The caller holds mm->mmap_sem. This means that the task which 1591 * uses this mm can't pass exit_mm(), so it can't exit or clear 1592 * its ->mm. 1593 * 1594 * de_thread: 1595 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 1596 * we must see either old or new leader, this does not matter. 1597 * However, it can change p->sighand, so lock_task_sighand(p) 1598 * must be used. Since p->mm != NULL and we hold ->mmap_sem 1599 * it can't fail. 1600 * 1601 * Note also that "g" can be the old leader with ->mm == NULL 1602 * and already unhashed and thus removed from ->thread_group. 1603 * This is OK, __unhash_process()->list_del_rcu() does not 1604 * clear the ->next pointer, we will find the new leader via 1605 * next_thread(). 1606 */ 1607 rcu_read_lock(); 1608 for_each_process(g) { 1609 if (g == tsk->group_leader) 1610 continue; 1611 if (g->flags & PF_KTHREAD) 1612 continue; 1613 p = g; 1614 do { 1615 if (p->mm) { 1616 if (unlikely(p->mm == mm)) { 1617 lock_task_sighand(p, &flags); 1618 nr += zap_process(p); 1619 unlock_task_sighand(p, &flags); 1620 } 1621 break; 1622 } 1623 } while_each_thread(g, p); 1624 } 1625 rcu_read_unlock(); 1626 done: 1627 atomic_set(&core_state->nr_threads, nr); 1628 return nr; 1629 } 1630 1631 static int coredump_wait(int exit_code, struct core_state *core_state) 1632 { 1633 struct task_struct *tsk = current; 1634 struct mm_struct *mm = tsk->mm; 1635 struct completion *vfork_done; 1636 int core_waiters; 1637 1638 init_completion(&core_state->startup); 1639 core_state->dumper.task = tsk; 1640 core_state->dumper.next = NULL; 1641 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 1642 up_write(&mm->mmap_sem); 1643 1644 if (unlikely(core_waiters < 0)) 1645 goto fail; 1646 1647 /* 1648 * Make sure nobody is waiting for us to release the VM, 1649 * otherwise we can deadlock when we wait on each other 1650 */ 1651 vfork_done = tsk->vfork_done; 1652 if (vfork_done) { 1653 tsk->vfork_done = NULL; 1654 complete(vfork_done); 1655 } 1656 1657 if (core_waiters) 1658 wait_for_completion(&core_state->startup); 1659 fail: 1660 return core_waiters; 1661 } 1662 1663 static void coredump_finish(struct mm_struct *mm) 1664 { 1665 struct core_thread *curr, *next; 1666 struct task_struct *task; 1667 1668 next = mm->core_state->dumper.next; 1669 while ((curr = next) != NULL) { 1670 next = curr->next; 1671 task = curr->task; 1672 /* 1673 * see exit_mm(), curr->task must not see 1674 * ->task == NULL before we read ->next. 1675 */ 1676 smp_mb(); 1677 curr->task = NULL; 1678 wake_up_process(task); 1679 } 1680 1681 mm->core_state = NULL; 1682 } 1683 1684 /* 1685 * set_dumpable converts traditional three-value dumpable to two flags and 1686 * stores them into mm->flags. It modifies lower two bits of mm->flags, but 1687 * these bits are not changed atomically. So get_dumpable can observe the 1688 * intermediate state. To avoid doing unexpected behavior, get get_dumpable 1689 * return either old dumpable or new one by paying attention to the order of 1690 * modifying the bits. 1691 * 1692 * dumpable | mm->flags (binary) 1693 * old new | initial interim final 1694 * ---------+----------------------- 1695 * 0 1 | 00 01 01 1696 * 0 2 | 00 10(*) 11 1697 * 1 0 | 01 00 00 1698 * 1 2 | 01 11 11 1699 * 2 0 | 11 10(*) 00 1700 * 2 1 | 11 11 01 1701 * 1702 * (*) get_dumpable regards interim value of 10 as 11. 1703 */ 1704 void set_dumpable(struct mm_struct *mm, int value) 1705 { 1706 switch (value) { 1707 case 0: 1708 clear_bit(MMF_DUMPABLE, &mm->flags); 1709 smp_wmb(); 1710 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1711 break; 1712 case 1: 1713 set_bit(MMF_DUMPABLE, &mm->flags); 1714 smp_wmb(); 1715 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1716 break; 1717 case 2: 1718 set_bit(MMF_DUMP_SECURELY, &mm->flags); 1719 smp_wmb(); 1720 set_bit(MMF_DUMPABLE, &mm->flags); 1721 break; 1722 } 1723 } 1724 1725 int get_dumpable(struct mm_struct *mm) 1726 { 1727 int ret; 1728 1729 ret = mm->flags & 0x3; 1730 return (ret >= 2) ? 2 : ret; 1731 } 1732 1733 void do_coredump(long signr, int exit_code, struct pt_regs *regs) 1734 { 1735 struct core_state core_state; 1736 char corename[CORENAME_MAX_SIZE + 1]; 1737 struct mm_struct *mm = current->mm; 1738 struct linux_binfmt * binfmt; 1739 struct inode * inode; 1740 struct file * file; 1741 const struct cred *old_cred; 1742 struct cred *cred; 1743 int retval = 0; 1744 int flag = 0; 1745 int ispipe = 0; 1746 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur; 1747 char **helper_argv = NULL; 1748 int helper_argc = 0; 1749 char *delimit; 1750 1751 audit_core_dumps(signr); 1752 1753 binfmt = current->binfmt; 1754 if (!binfmt || !binfmt->core_dump) 1755 goto fail; 1756 1757 cred = prepare_creds(); 1758 if (!cred) { 1759 retval = -ENOMEM; 1760 goto fail; 1761 } 1762 1763 down_write(&mm->mmap_sem); 1764 /* 1765 * If another thread got here first, or we are not dumpable, bail out. 1766 */ 1767 if (mm->core_state || !get_dumpable(mm)) { 1768 up_write(&mm->mmap_sem); 1769 put_cred(cred); 1770 goto fail; 1771 } 1772 1773 /* 1774 * We cannot trust fsuid as being the "true" uid of the 1775 * process nor do we know its entire history. We only know it 1776 * was tainted so we dump it as root in mode 2. 1777 */ 1778 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ 1779 flag = O_EXCL; /* Stop rewrite attacks */ 1780 cred->fsuid = 0; /* Dump root private */ 1781 } 1782 1783 retval = coredump_wait(exit_code, &core_state); 1784 if (retval < 0) { 1785 put_cred(cred); 1786 goto fail; 1787 } 1788 1789 old_cred = override_creds(cred); 1790 1791 /* 1792 * Clear any false indication of pending signals that might 1793 * be seen by the filesystem code called to write the core file. 1794 */ 1795 clear_thread_flag(TIF_SIGPENDING); 1796 1797 /* 1798 * lock_kernel() because format_corename() is controlled by sysctl, which 1799 * uses lock_kernel() 1800 */ 1801 lock_kernel(); 1802 ispipe = format_corename(corename, signr); 1803 unlock_kernel(); 1804 /* 1805 * Don't bother to check the RLIMIT_CORE value if core_pattern points 1806 * to a pipe. Since we're not writing directly to the filesystem 1807 * RLIMIT_CORE doesn't really apply, as no actual core file will be 1808 * created unless the pipe reader choses to write out the core file 1809 * at which point file size limits and permissions will be imposed 1810 * as it does with any other process 1811 */ 1812 if ((!ispipe) && (core_limit < binfmt->min_coredump)) 1813 goto fail_unlock; 1814 1815 if (ispipe) { 1816 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc); 1817 if (!helper_argv) { 1818 printk(KERN_WARNING "%s failed to allocate memory\n", 1819 __func__); 1820 goto fail_unlock; 1821 } 1822 /* Terminate the string before the first option */ 1823 delimit = strchr(corename, ' '); 1824 if (delimit) 1825 *delimit = '\0'; 1826 delimit = strrchr(helper_argv[0], '/'); 1827 if (delimit) 1828 delimit++; 1829 else 1830 delimit = helper_argv[0]; 1831 if (!strcmp(delimit, current->comm)) { 1832 printk(KERN_NOTICE "Recursive core dump detected, " 1833 "aborting\n"); 1834 goto fail_unlock; 1835 } 1836 1837 core_limit = RLIM_INFINITY; 1838 1839 /* SIGPIPE can happen, but it's just never processed */ 1840 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL, 1841 &file)) { 1842 printk(KERN_INFO "Core dump to %s pipe failed\n", 1843 corename); 1844 goto fail_unlock; 1845 } 1846 } else 1847 file = filp_open(corename, 1848 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 1849 0600); 1850 if (IS_ERR(file)) 1851 goto fail_unlock; 1852 inode = file->f_path.dentry->d_inode; 1853 if (inode->i_nlink > 1) 1854 goto close_fail; /* multiple links - don't dump */ 1855 if (!ispipe && d_unhashed(file->f_path.dentry)) 1856 goto close_fail; 1857 1858 /* AK: actually i see no reason to not allow this for named pipes etc., 1859 but keep the previous behaviour for now. */ 1860 if (!ispipe && !S_ISREG(inode->i_mode)) 1861 goto close_fail; 1862 /* 1863 * Dont allow local users get cute and trick others to coredump 1864 * into their pre-created files: 1865 */ 1866 if (inode->i_uid != current_fsuid()) 1867 goto close_fail; 1868 if (!file->f_op) 1869 goto close_fail; 1870 if (!file->f_op->write) 1871 goto close_fail; 1872 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0) 1873 goto close_fail; 1874 1875 retval = binfmt->core_dump(signr, regs, file, core_limit); 1876 1877 if (retval) 1878 current->signal->group_exit_code |= 0x80; 1879 close_fail: 1880 filp_close(file, NULL); 1881 fail_unlock: 1882 if (helper_argv) 1883 argv_free(helper_argv); 1884 1885 revert_creds(old_cred); 1886 put_cred(cred); 1887 coredump_finish(mm); 1888 fail: 1889 return; 1890 } 1891