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 58#include <asm/uaccess.h> 59#include <asm/mmu_context.h> 60#include <asm/tlb.h> 61#include "internal.h" 62 63int core_uses_pid; 64char core_pattern[CORENAME_MAX_SIZE] = "core"; 65unsigned int core_pipe_limit; 66int suid_dumpable = 0; 67 68/* The maximal length of core_pattern is also specified in sysctl.c */ 69 70static LIST_HEAD(formats); 71static DEFINE_RWLOCK(binfmt_lock); 72 73int __register_binfmt(struct linux_binfmt * fmt, int insert) 74{ 75 if (!fmt) 76 return -EINVAL; 77 write_lock(&binfmt_lock); 78 insert ? list_add(&fmt->lh, &formats) : 79 list_add_tail(&fmt->lh, &formats); 80 write_unlock(&binfmt_lock); 81 return 0; 82} 83 84EXPORT_SYMBOL(__register_binfmt); 85 86void unregister_binfmt(struct linux_binfmt * fmt) 87{ 88 write_lock(&binfmt_lock); 89 list_del(&fmt->lh); 90 write_unlock(&binfmt_lock); 91} 92 93EXPORT_SYMBOL(unregister_binfmt); 94 95static inline void put_binfmt(struct linux_binfmt * fmt) 96{ 97 module_put(fmt->module); 98} 99 100/* 101 * Note that a shared library must be both readable and executable due to 102 * security reasons. 103 * 104 * Also note that we take the address to load from from the file itself. 105 */ 106SYSCALL_DEFINE1(uselib, const char __user *, library) 107{ 108 struct file *file; 109 char *tmp = getname(library); 110 int error = PTR_ERR(tmp); 111 112 if (IS_ERR(tmp)) 113 goto out; 114 115 file = do_filp_open(AT_FDCWD, tmp, 116 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0, 117 MAY_READ | MAY_EXEC | MAY_OPEN); 118 putname(tmp); 119 error = PTR_ERR(file); 120 if (IS_ERR(file)) 121 goto out; 122 123 error = -EINVAL; 124 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) 125 goto exit; 126 127 error = -EACCES; 128 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 129 goto exit; 130 131 fsnotify_open(file); 132 133 error = -ENOEXEC; 134 if(file->f_op) { 135 struct linux_binfmt * fmt; 136 137 read_lock(&binfmt_lock); 138 list_for_each_entry(fmt, &formats, lh) { 139 if (!fmt->load_shlib) 140 continue; 141 if (!try_module_get(fmt->module)) 142 continue; 143 read_unlock(&binfmt_lock); 144 error = fmt->load_shlib(file); 145 read_lock(&binfmt_lock); 146 put_binfmt(fmt); 147 if (error != -ENOEXEC) 148 break; 149 } 150 read_unlock(&binfmt_lock); 151 } 152exit: 153 fput(file); 154out: 155 return error; 156} 157 158#ifdef CONFIG_MMU 159 160void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 161{ 162 struct mm_struct *mm = current->mm; 163 long diff = (long)(pages - bprm->vma_pages); 164 165 if (!mm || !diff) 166 return; 167 168 bprm->vma_pages = pages; 169 170#ifdef SPLIT_RSS_COUNTING 171 add_mm_counter(mm, MM_ANONPAGES, diff); 172#else 173 spin_lock(&mm->page_table_lock); 174 add_mm_counter(mm, MM_ANONPAGES, diff); 175 spin_unlock(&mm->page_table_lock); 176#endif 177} 178 179struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 180 int write) 181{ 182 struct page *page; 183 int ret; 184 185#ifdef CONFIG_STACK_GROWSUP 186 if (write) { 187 ret = expand_stack_downwards(bprm->vma, pos); 188 if (ret < 0) 189 return NULL; 190 } 191#endif 192 ret = get_user_pages(current, bprm->mm, pos, 193 1, write, 1, &page, NULL); 194 if (ret <= 0) 195 return NULL; 196 197 if (write) { 198 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; 199 struct rlimit *rlim; 200 201 acct_arg_size(bprm, size / PAGE_SIZE); 202 203 /* 204 * We've historically supported up to 32 pages (ARG_MAX) 205 * of argument strings even with small stacks 206 */ 207 if (size <= ARG_MAX) 208 return page; 209 210 /* 211 * Limit to 1/4-th the stack size for the argv+env strings. 212 * This ensures that: 213 * - the remaining binfmt code will not run out of stack space, 214 * - the program will have a reasonable amount of stack left 215 * to work from. 216 */ 217 rlim = current->signal->rlim; 218 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { 219 put_page(page); 220 return NULL; 221 } 222 } 223 224 return page; 225} 226 227static void put_arg_page(struct page *page) 228{ 229 put_page(page); 230} 231 232static void free_arg_page(struct linux_binprm *bprm, int i) 233{ 234} 235 236static void free_arg_pages(struct linux_binprm *bprm) 237{ 238} 239 240static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 241 struct page *page) 242{ 243 flush_cache_page(bprm->vma, pos, page_to_pfn(page)); 244} 245 246static int __bprm_mm_init(struct linux_binprm *bprm) 247{ 248 int err; 249 struct vm_area_struct *vma = NULL; 250 struct mm_struct *mm = bprm->mm; 251 252 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 253 if (!vma) 254 return -ENOMEM; 255 256 down_write(&mm->mmap_sem); 257 vma->vm_mm = mm; 258 259 /* 260 * Place the stack at the largest stack address the architecture 261 * supports. Later, we'll move this to an appropriate place. We don't 262 * use STACK_TOP because that can depend on attributes which aren't 263 * configured yet. 264 */ 265 BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); 266 vma->vm_end = STACK_TOP_MAX; 267 vma->vm_start = vma->vm_end - PAGE_SIZE; 268 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; 269 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 270 INIT_LIST_HEAD(&vma->anon_vma_chain); 271 272 err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); 273 if (err) 274 goto err; 275 276 err = insert_vm_struct(mm, vma); 277 if (err) 278 goto err; 279 280 mm->stack_vm = mm->total_vm = 1; 281 up_write(&mm->mmap_sem); 282 bprm->p = vma->vm_end - sizeof(void *); 283 return 0; 284err: 285 up_write(&mm->mmap_sem); 286 bprm->vma = NULL; 287 kmem_cache_free(vm_area_cachep, vma); 288 return err; 289} 290 291static bool valid_arg_len(struct linux_binprm *bprm, long len) 292{ 293 return len <= MAX_ARG_STRLEN; 294} 295 296#else 297 298void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) 299{ 300} 301 302struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, 303 int write) 304{ 305 struct page *page; 306 307 page = bprm->page[pos / PAGE_SIZE]; 308 if (!page && write) { 309 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); 310 if (!page) 311 return NULL; 312 bprm->page[pos / PAGE_SIZE] = page; 313 } 314 315 return page; 316} 317 318static void put_arg_page(struct page *page) 319{ 320} 321 322static void free_arg_page(struct linux_binprm *bprm, int i) 323{ 324 if (bprm->page[i]) { 325 __free_page(bprm->page[i]); 326 bprm->page[i] = NULL; 327 } 328} 329 330static void free_arg_pages(struct linux_binprm *bprm) 331{ 332 int i; 333 334 for (i = 0; i < MAX_ARG_PAGES; i++) 335 free_arg_page(bprm, i); 336} 337 338static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, 339 struct page *page) 340{ 341} 342 343static int __bprm_mm_init(struct linux_binprm *bprm) 344{ 345 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); 346 return 0; 347} 348 349static bool valid_arg_len(struct linux_binprm *bprm, long len) 350{ 351 return len <= bprm->p; 352} 353 354#endif /* CONFIG_MMU */ 355 356/* 357 * Create a new mm_struct and populate it with a temporary stack 358 * vm_area_struct. We don't have enough context at this point to set the stack 359 * flags, permissions, and offset, so we use temporary values. We'll update 360 * them later in setup_arg_pages(). 361 */ 362int bprm_mm_init(struct linux_binprm *bprm) 363{ 364 int err; 365 struct mm_struct *mm = NULL; 366 367 bprm->mm = mm = mm_alloc(); 368 err = -ENOMEM; 369 if (!mm) 370 goto err; 371 372 err = init_new_context(current, mm); 373 if (err) 374 goto err; 375 376 err = __bprm_mm_init(bprm); 377 if (err) 378 goto err; 379 380 return 0; 381 382err: 383 if (mm) { 384 bprm->mm = NULL; 385 mmdrop(mm); 386 } 387 388 return err; 389} 390 391/* 392 * count() counts the number of strings in array ARGV. 393 */ 394static int count(const char __user * const __user * argv, int max) 395{ 396 int i = 0; 397 398 if (argv != NULL) { 399 for (;;) { 400 const char __user * p; 401 402 if (get_user(p, argv)) 403 return -EFAULT; 404 if (!p) 405 break; 406 argv++; 407 if (i++ >= max) 408 return -E2BIG; 409 410 if (fatal_signal_pending(current)) 411 return -ERESTARTNOHAND; 412 cond_resched(); 413 } 414 } 415 return i; 416} 417 418/* 419 * 'copy_strings()' copies argument/environment strings from the old 420 * processes's memory to the new process's stack. The call to get_user_pages() 421 * ensures the destination page is created and not swapped out. 422 */ 423static int copy_strings(int argc, const char __user *const __user *argv, 424 struct linux_binprm *bprm) 425{ 426 struct page *kmapped_page = NULL; 427 char *kaddr = NULL; 428 unsigned long kpos = 0; 429 int ret; 430 431 while (argc-- > 0) { 432 const char __user *str; 433 int len; 434 unsigned long pos; 435 436 if (get_user(str, argv+argc) || 437 !(len = strnlen_user(str, MAX_ARG_STRLEN))) { 438 ret = -EFAULT; 439 goto out; 440 } 441 442 if (!valid_arg_len(bprm, len)) { 443 ret = -E2BIG; 444 goto out; 445 } 446 447 /* We're going to work our way backwords. */ 448 pos = bprm->p; 449 str += len; 450 bprm->p -= len; 451 452 while (len > 0) { 453 int offset, bytes_to_copy; 454 455 if (fatal_signal_pending(current)) { 456 ret = -ERESTARTNOHAND; 457 goto out; 458 } 459 cond_resched(); 460 461 offset = pos % PAGE_SIZE; 462 if (offset == 0) 463 offset = PAGE_SIZE; 464 465 bytes_to_copy = offset; 466 if (bytes_to_copy > len) 467 bytes_to_copy = len; 468 469 offset -= bytes_to_copy; 470 pos -= bytes_to_copy; 471 str -= bytes_to_copy; 472 len -= bytes_to_copy; 473 474 if (!kmapped_page || kpos != (pos & PAGE_MASK)) { 475 struct page *page; 476 477 page = get_arg_page(bprm, pos, 1); 478 if (!page) { 479 ret = -E2BIG; 480 goto out; 481 } 482 483 if (kmapped_page) { 484 flush_kernel_dcache_page(kmapped_page); 485 kunmap(kmapped_page); 486 put_arg_page(kmapped_page); 487 } 488 kmapped_page = page; 489 kaddr = kmap(kmapped_page); 490 kpos = pos & PAGE_MASK; 491 flush_arg_page(bprm, kpos, kmapped_page); 492 } 493 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { 494 ret = -EFAULT; 495 goto out; 496 } 497 } 498 } 499 ret = 0; 500out: 501 if (kmapped_page) { 502 flush_kernel_dcache_page(kmapped_page); 503 kunmap(kmapped_page); 504 put_arg_page(kmapped_page); 505 } 506 return ret; 507} 508 509/* 510 * Like copy_strings, but get argv and its values from kernel memory. 511 */ 512int copy_strings_kernel(int argc, const char *const *argv, 513 struct linux_binprm *bprm) 514{ 515 int r; 516 mm_segment_t oldfs = get_fs(); 517 set_fs(KERNEL_DS); 518 r = copy_strings(argc, (const char __user *const __user *)argv, bprm); 519 set_fs(oldfs); 520 return r; 521} 522EXPORT_SYMBOL(copy_strings_kernel); 523 524#ifdef CONFIG_MMU 525 526/* 527 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once 528 * the binfmt code determines where the new stack should reside, we shift it to 529 * its final location. The process proceeds as follows: 530 * 531 * 1) Use shift to calculate the new vma endpoints. 532 * 2) Extend vma to cover both the old and new ranges. This ensures the 533 * arguments passed to subsequent functions are consistent. 534 * 3) Move vma's page tables to the new range. 535 * 4) Free up any cleared pgd range. 536 * 5) Shrink the vma to cover only the new range. 537 */ 538static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) 539{ 540 struct mm_struct *mm = vma->vm_mm; 541 unsigned long old_start = vma->vm_start; 542 unsigned long old_end = vma->vm_end; 543 unsigned long length = old_end - old_start; 544 unsigned long new_start = old_start - shift; 545 unsigned long new_end = old_end - shift; 546 struct mmu_gather *tlb; 547 548 BUG_ON(new_start > new_end); 549 550 /* 551 * ensure there are no vmas between where we want to go 552 * and where we are 553 */ 554 if (vma != find_vma(mm, new_start)) 555 return -EFAULT; 556 557 /* 558 * cover the whole range: [new_start, old_end) 559 */ 560 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) 561 return -ENOMEM; 562 563 /* 564 * move the page tables downwards, on failure we rely on 565 * process cleanup to remove whatever mess we made. 566 */ 567 if (length != move_page_tables(vma, old_start, 568 vma, new_start, length)) 569 return -ENOMEM; 570 571 lru_add_drain(); 572 tlb = tlb_gather_mmu(mm, 0); 573 if (new_end > old_start) { 574 /* 575 * when the old and new regions overlap clear from new_end. 576 */ 577 free_pgd_range(tlb, new_end, old_end, new_end, 578 vma->vm_next ? vma->vm_next->vm_start : 0); 579 } else { 580 /* 581 * otherwise, clean from old_start; this is done to not touch 582 * the address space in [new_end, old_start) some architectures 583 * have constraints on va-space that make this illegal (IA64) - 584 * for the others its just a little faster. 585 */ 586 free_pgd_range(tlb, old_start, old_end, new_end, 587 vma->vm_next ? vma->vm_next->vm_start : 0); 588 } 589 tlb_finish_mmu(tlb, new_end, old_end); 590 591 /* 592 * Shrink the vma to just the new range. Always succeeds. 593 */ 594 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); 595 596 return 0; 597} 598 599/* 600 * Finalizes the stack vm_area_struct. The flags and permissions are updated, 601 * the stack is optionally relocated, and some extra space is added. 602 */ 603int setup_arg_pages(struct linux_binprm *bprm, 604 unsigned long stack_top, 605 int executable_stack) 606{ 607 unsigned long ret; 608 unsigned long stack_shift; 609 struct mm_struct *mm = current->mm; 610 struct vm_area_struct *vma = bprm->vma; 611 struct vm_area_struct *prev = NULL; 612 unsigned long vm_flags; 613 unsigned long stack_base; 614 unsigned long stack_size; 615 unsigned long stack_expand; 616 unsigned long rlim_stack; 617 618#ifdef CONFIG_STACK_GROWSUP 619 /* Limit stack size to 1GB */ 620 stack_base = rlimit_max(RLIMIT_STACK); 621 if (stack_base > (1 << 30)) 622 stack_base = 1 << 30; 623 624 /* Make sure we didn't let the argument array grow too large. */ 625 if (vma->vm_end - vma->vm_start > stack_base) 626 return -ENOMEM; 627 628 stack_base = PAGE_ALIGN(stack_top - stack_base); 629 630 stack_shift = vma->vm_start - stack_base; 631 mm->arg_start = bprm->p - stack_shift; 632 bprm->p = vma->vm_end - stack_shift; 633#else 634 stack_top = arch_align_stack(stack_top); 635 stack_top = PAGE_ALIGN(stack_top); 636 637 if (unlikely(stack_top < mmap_min_addr) || 638 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) 639 return -ENOMEM; 640 641 stack_shift = vma->vm_end - stack_top; 642 643 bprm->p -= stack_shift; 644 mm->arg_start = bprm->p; 645#endif 646 647 if (bprm->loader) 648 bprm->loader -= stack_shift; 649 bprm->exec -= stack_shift; 650 651 down_write(&mm->mmap_sem); 652 vm_flags = VM_STACK_FLAGS; 653 654 /* 655 * Adjust stack execute permissions; explicitly enable for 656 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone 657 * (arch default) otherwise. 658 */ 659 if (unlikely(executable_stack == EXSTACK_ENABLE_X)) 660 vm_flags |= VM_EXEC; 661 else if (executable_stack == EXSTACK_DISABLE_X) 662 vm_flags &= ~VM_EXEC; 663 vm_flags |= mm->def_flags; 664 vm_flags |= VM_STACK_INCOMPLETE_SETUP; 665 666 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, 667 vm_flags); 668 if (ret) 669 goto out_unlock; 670 BUG_ON(prev != vma); 671 672 /* Move stack pages down in memory. */ 673 if (stack_shift) { 674 ret = shift_arg_pages(vma, stack_shift); 675 if (ret) 676 goto out_unlock; 677 } 678 679 /* mprotect_fixup is overkill to remove the temporary stack flags */ 680 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; 681 682 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ 683 stack_size = vma->vm_end - vma->vm_start; 684 /* 685 * Align this down to a page boundary as expand_stack 686 * will align it up. 687 */ 688 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; 689#ifdef CONFIG_STACK_GROWSUP 690 if (stack_size + stack_expand > rlim_stack) 691 stack_base = vma->vm_start + rlim_stack; 692 else 693 stack_base = vma->vm_end + stack_expand; 694#else 695 if (stack_size + stack_expand > rlim_stack) 696 stack_base = vma->vm_end - rlim_stack; 697 else 698 stack_base = vma->vm_start - stack_expand; 699#endif 700 current->mm->start_stack = bprm->p; 701 ret = expand_stack(vma, stack_base); 702 if (ret) 703 ret = -EFAULT; 704 705out_unlock: 706 up_write(&mm->mmap_sem); 707 return ret; 708} 709EXPORT_SYMBOL(setup_arg_pages); 710 711#endif /* CONFIG_MMU */ 712 713struct file *open_exec(const char *name) 714{ 715 struct file *file; 716 int err; 717 718 file = do_filp_open(AT_FDCWD, name, 719 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0, 720 MAY_EXEC | MAY_OPEN); 721 if (IS_ERR(file)) 722 goto out; 723 724 err = -EACCES; 725 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) 726 goto exit; 727 728 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) 729 goto exit; 730 731 fsnotify_open(file); 732 733 err = deny_write_access(file); 734 if (err) 735 goto exit; 736 737out: 738 return file; 739 740exit: 741 fput(file); 742 return ERR_PTR(err); 743} 744EXPORT_SYMBOL(open_exec); 745 746int kernel_read(struct file *file, loff_t offset, 747 char *addr, unsigned long count) 748{ 749 mm_segment_t old_fs; 750 loff_t pos = offset; 751 int result; 752 753 old_fs = get_fs(); 754 set_fs(get_ds()); 755 /* The cast to a user pointer is valid due to the set_fs() */ 756 result = vfs_read(file, (void __user *)addr, count, &pos); 757 set_fs(old_fs); 758 return result; 759} 760 761EXPORT_SYMBOL(kernel_read); 762 763static int exec_mmap(struct mm_struct *mm) 764{ 765 struct task_struct *tsk; 766 struct mm_struct * old_mm, *active_mm; 767 768 /* Notify parent that we're no longer interested in the old VM */ 769 tsk = current; 770 old_mm = current->mm; 771 sync_mm_rss(tsk, old_mm); 772 mm_release(tsk, old_mm); 773 774 if (old_mm) { 775 /* 776 * Make sure that if there is a core dump in progress 777 * for the old mm, we get out and die instead of going 778 * through with the exec. We must hold mmap_sem around 779 * checking core_state and changing tsk->mm. 780 */ 781 down_read(&old_mm->mmap_sem); 782 if (unlikely(old_mm->core_state)) { 783 up_read(&old_mm->mmap_sem); 784 return -EINTR; 785 } 786 } 787 task_lock(tsk); 788 active_mm = tsk->active_mm; 789 tsk->mm = mm; 790 tsk->active_mm = mm; 791 activate_mm(active_mm, mm); 792 task_unlock(tsk); 793 arch_pick_mmap_layout(mm); 794 if (old_mm) { 795 up_read(&old_mm->mmap_sem); 796 BUG_ON(active_mm != old_mm); 797 mm_update_next_owner(old_mm); 798 mmput(old_mm); 799 return 0; 800 } 801 mmdrop(active_mm); 802 return 0; 803} 804 805/* 806 * This function makes sure the current process has its own signal table, 807 * so that flush_signal_handlers can later reset the handlers without 808 * disturbing other processes. (Other processes might share the signal 809 * table via the CLONE_SIGHAND option to clone().) 810 */ 811static int de_thread(struct task_struct *tsk) 812{ 813 struct signal_struct *sig = tsk->signal; 814 struct sighand_struct *oldsighand = tsk->sighand; 815 spinlock_t *lock = &oldsighand->siglock; 816 817 if (thread_group_empty(tsk)) 818 goto no_thread_group; 819 820 /* 821 * Kill all other threads in the thread group. 822 */ 823 spin_lock_irq(lock); 824 if (signal_group_exit(sig)) { 825 /* 826 * Another group action in progress, just 827 * return so that the signal is processed. 828 */ 829 spin_unlock_irq(lock); 830 return -EAGAIN; 831 } 832 833 sig->group_exit_task = tsk; 834 sig->notify_count = zap_other_threads(tsk); 835 if (!thread_group_leader(tsk)) 836 sig->notify_count--; 837 838 while (sig->notify_count) { 839 __set_current_state(TASK_UNINTERRUPTIBLE); 840 spin_unlock_irq(lock); 841 schedule(); 842 spin_lock_irq(lock); 843 } 844 spin_unlock_irq(lock); 845 846 /* 847 * At this point all other threads have exited, all we have to 848 * do is to wait for the thread group leader to become inactive, 849 * and to assume its PID: 850 */ 851 if (!thread_group_leader(tsk)) { 852 struct task_struct *leader = tsk->group_leader; 853 854 sig->notify_count = -1; /* for exit_notify() */ 855 for (;;) { 856 write_lock_irq(&tasklist_lock); 857 if (likely(leader->exit_state)) 858 break; 859 __set_current_state(TASK_UNINTERRUPTIBLE); 860 write_unlock_irq(&tasklist_lock); 861 schedule(); 862 } 863 864 /* 865 * The only record we have of the real-time age of a 866 * process, regardless of execs it's done, is start_time. 867 * All the past CPU time is accumulated in signal_struct 868 * from sister threads now dead. But in this non-leader 869 * exec, nothing survives from the original leader thread, 870 * whose birth marks the true age of this process now. 871 * When we take on its identity by switching to its PID, we 872 * also take its birthdate (always earlier than our own). 873 */ 874 tsk->start_time = leader->start_time; 875 876 BUG_ON(!same_thread_group(leader, tsk)); 877 BUG_ON(has_group_leader_pid(tsk)); 878 /* 879 * An exec() starts a new thread group with the 880 * TGID of the previous thread group. Rehash the 881 * two threads with a switched PID, and release 882 * the former thread group leader: 883 */ 884 885 /* Become a process group leader with the old leader's pid. 886 * The old leader becomes a thread of the this thread group. 887 * Note: The old leader also uses this pid until release_task 888 * is called. Odd but simple and correct. 889 */ 890 detach_pid(tsk, PIDTYPE_PID); 891 tsk->pid = leader->pid; 892 attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); 893 transfer_pid(leader, tsk, PIDTYPE_PGID); 894 transfer_pid(leader, tsk, PIDTYPE_SID); 895 896 list_replace_rcu(&leader->tasks, &tsk->tasks); 897 list_replace_init(&leader->sibling, &tsk->sibling); 898 899 tsk->group_leader = tsk; 900 leader->group_leader = tsk; 901 902 tsk->exit_signal = SIGCHLD; 903 904 BUG_ON(leader->exit_state != EXIT_ZOMBIE); 905 leader->exit_state = EXIT_DEAD; 906 write_unlock_irq(&tasklist_lock); 907 908 release_task(leader); 909 } 910 911 sig->group_exit_task = NULL; 912 sig->notify_count = 0; 913 914no_thread_group: 915 if (current->mm) 916 setmax_mm_hiwater_rss(&sig->maxrss, current->mm); 917 918 exit_itimers(sig); 919 flush_itimer_signals(); 920 921 if (atomic_read(&oldsighand->count) != 1) { 922 struct sighand_struct *newsighand; 923 /* 924 * This ->sighand is shared with the CLONE_SIGHAND 925 * but not CLONE_THREAD task, switch to the new one. 926 */ 927 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 928 if (!newsighand) 929 return -ENOMEM; 930 931 atomic_set(&newsighand->count, 1); 932 memcpy(newsighand->action, oldsighand->action, 933 sizeof(newsighand->action)); 934 935 write_lock_irq(&tasklist_lock); 936 spin_lock(&oldsighand->siglock); 937 rcu_assign_pointer(tsk->sighand, newsighand); 938 spin_unlock(&oldsighand->siglock); 939 write_unlock_irq(&tasklist_lock); 940 941 __cleanup_sighand(oldsighand); 942 } 943 944 BUG_ON(!thread_group_leader(tsk)); 945 return 0; 946} 947 948/* 949 * These functions flushes out all traces of the currently running executable 950 * so that a new one can be started 951 */ 952static void flush_old_files(struct files_struct * files) 953{ 954 long j = -1; 955 struct fdtable *fdt; 956 957 spin_lock(&files->file_lock); 958 for (;;) { 959 unsigned long set, i; 960 961 j++; 962 i = j * __NFDBITS; 963 fdt = files_fdtable(files); 964 if (i >= fdt->max_fds) 965 break; 966 set = fdt->close_on_exec->fds_bits[j]; 967 if (!set) 968 continue; 969 fdt->close_on_exec->fds_bits[j] = 0; 970 spin_unlock(&files->file_lock); 971 for ( ; set ; i++,set >>= 1) { 972 if (set & 1) { 973 sys_close(i); 974 } 975 } 976 spin_lock(&files->file_lock); 977 978 } 979 spin_unlock(&files->file_lock); 980} 981 982char *get_task_comm(char *buf, struct task_struct *tsk) 983{ 984 /* buf must be at least sizeof(tsk->comm) in size */ 985 task_lock(tsk); 986 strncpy(buf, tsk->comm, sizeof(tsk->comm)); 987 task_unlock(tsk); 988 return buf; 989} 990 991void set_task_comm(struct task_struct *tsk, char *buf) 992{ 993 task_lock(tsk); 994 995 /* 996 * Threads may access current->comm without holding 997 * the task lock, so write the string carefully. 998 * Readers without a lock may see incomplete new 999 * names but are safe from non-terminating string reads. 1000 */ 1001 memset(tsk->comm, 0, TASK_COMM_LEN); 1002 wmb(); 1003 strlcpy(tsk->comm, buf, sizeof(tsk->comm)); 1004 task_unlock(tsk); 1005 perf_event_comm(tsk); 1006} 1007 1008int flush_old_exec(struct linux_binprm * bprm) 1009{ 1010 int retval; 1011 1012 /* 1013 * Make sure we have a private signal table and that 1014 * we are unassociated from the previous thread group. 1015 */ 1016 retval = de_thread(current); 1017 if (retval) 1018 goto out; 1019 1020 set_mm_exe_file(bprm->mm, bprm->file); 1021 1022 /* 1023 * Release all of the old mmap stuff 1024 */ 1025 acct_arg_size(bprm, 0); 1026 retval = exec_mmap(bprm->mm); 1027 if (retval) 1028 goto out; 1029 1030 bprm->mm = NULL; /* We're using it now */ 1031 1032 current->flags &= ~PF_RANDOMIZE; 1033 flush_thread(); 1034 current->personality &= ~bprm->per_clear; 1035 1036 return 0; 1037 1038out: 1039 return retval; 1040} 1041EXPORT_SYMBOL(flush_old_exec); 1042 1043void setup_new_exec(struct linux_binprm * bprm) 1044{ 1045 int i, ch; 1046 const char *name; 1047 char tcomm[sizeof(current->comm)]; 1048 1049 arch_pick_mmap_layout(current->mm); 1050 1051 /* This is the point of no return */ 1052 current->sas_ss_sp = current->sas_ss_size = 0; 1053 1054 if (current_euid() == current_uid() && current_egid() == current_gid()) 1055 set_dumpable(current->mm, 1); 1056 else 1057 set_dumpable(current->mm, suid_dumpable); 1058 1059 name = bprm->filename; 1060 1061 /* Copies the binary name from after last slash */ 1062 for (i=0; (ch = *(name++)) != '\0';) { 1063 if (ch == '/') 1064 i = 0; /* overwrite what we wrote */ 1065 else 1066 if (i < (sizeof(tcomm) - 1)) 1067 tcomm[i++] = ch; 1068 } 1069 tcomm[i] = '\0'; 1070 set_task_comm(current, tcomm); 1071 1072 /* Set the new mm task size. We have to do that late because it may 1073 * depend on TIF_32BIT which is only updated in flush_thread() on 1074 * some architectures like powerpc 1075 */ 1076 current->mm->task_size = TASK_SIZE; 1077 1078 /* install the new credentials */ 1079 if (bprm->cred->uid != current_euid() || 1080 bprm->cred->gid != current_egid()) { 1081 current->pdeath_signal = 0; 1082 } else if (file_permission(bprm->file, MAY_READ) || 1083 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) { 1084 set_dumpable(current->mm, suid_dumpable); 1085 } 1086 1087 /* 1088 * Flush performance counters when crossing a 1089 * security domain: 1090 */ 1091 if (!get_dumpable(current->mm)) 1092 perf_event_exit_task(current); 1093 1094 /* An exec changes our domain. We are no longer part of the thread 1095 group */ 1096 1097 current->self_exec_id++; 1098 1099 flush_signal_handlers(current, 0); 1100 flush_old_files(current->files); 1101} 1102EXPORT_SYMBOL(setup_new_exec); 1103 1104/* 1105 * Prepare credentials and lock ->cred_guard_mutex. 1106 * install_exec_creds() commits the new creds and drops the lock. 1107 * Or, if exec fails before, free_bprm() should release ->cred and 1108 * and unlock. 1109 */ 1110int prepare_bprm_creds(struct linux_binprm *bprm) 1111{ 1112 if (mutex_lock_interruptible(¤t->cred_guard_mutex)) 1113 return -ERESTARTNOINTR; 1114 1115 bprm->cred = prepare_exec_creds(); 1116 if (likely(bprm->cred)) 1117 return 0; 1118 1119 mutex_unlock(¤t->cred_guard_mutex); 1120 return -ENOMEM; 1121} 1122 1123void free_bprm(struct linux_binprm *bprm) 1124{ 1125 free_arg_pages(bprm); 1126 if (bprm->cred) { 1127 mutex_unlock(¤t->cred_guard_mutex); 1128 abort_creds(bprm->cred); 1129 } 1130 kfree(bprm); 1131} 1132 1133/* 1134 * install the new credentials for this executable 1135 */ 1136void install_exec_creds(struct linux_binprm *bprm) 1137{ 1138 security_bprm_committing_creds(bprm); 1139 1140 commit_creds(bprm->cred); 1141 bprm->cred = NULL; 1142 /* 1143 * cred_guard_mutex must be held at least to this point to prevent 1144 * ptrace_attach() from altering our determination of the task's 1145 * credentials; any time after this it may be unlocked. 1146 */ 1147 security_bprm_committed_creds(bprm); 1148 mutex_unlock(¤t->cred_guard_mutex); 1149} 1150EXPORT_SYMBOL(install_exec_creds); 1151 1152/* 1153 * determine how safe it is to execute the proposed program 1154 * - the caller must hold current->cred_guard_mutex to protect against 1155 * PTRACE_ATTACH 1156 */ 1157int check_unsafe_exec(struct linux_binprm *bprm) 1158{ 1159 struct task_struct *p = current, *t; 1160 unsigned n_fs; 1161 int res = 0; 1162 1163 bprm->unsafe = tracehook_unsafe_exec(p); 1164 1165 n_fs = 1; 1166 spin_lock(&p->fs->lock); 1167 rcu_read_lock(); 1168 for (t = next_thread(p); t != p; t = next_thread(t)) { 1169 if (t->fs == p->fs) 1170 n_fs++; 1171 } 1172 rcu_read_unlock(); 1173 1174 if (p->fs->users > n_fs) { 1175 bprm->unsafe |= LSM_UNSAFE_SHARE; 1176 } else { 1177 res = -EAGAIN; 1178 if (!p->fs->in_exec) { 1179 p->fs->in_exec = 1; 1180 res = 1; 1181 } 1182 } 1183 spin_unlock(&p->fs->lock); 1184 1185 return res; 1186} 1187 1188/* 1189 * Fill the binprm structure from the inode. 1190 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes 1191 * 1192 * This may be called multiple times for binary chains (scripts for example). 1193 */ 1194int prepare_binprm(struct linux_binprm *bprm) 1195{ 1196 umode_t mode; 1197 struct inode * inode = bprm->file->f_path.dentry->d_inode; 1198 int retval; 1199 1200 mode = inode->i_mode; 1201 if (bprm->file->f_op == NULL) 1202 return -EACCES; 1203 1204 /* clear any previous set[ug]id data from a previous binary */ 1205 bprm->cred->euid = current_euid(); 1206 bprm->cred->egid = current_egid(); 1207 1208 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { 1209 /* Set-uid? */ 1210 if (mode & S_ISUID) { 1211 bprm->per_clear |= PER_CLEAR_ON_SETID; 1212 bprm->cred->euid = inode->i_uid; 1213 } 1214 1215 /* Set-gid? */ 1216 /* 1217 * If setgid is set but no group execute bit then this 1218 * is a candidate for mandatory locking, not a setgid 1219 * executable. 1220 */ 1221 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { 1222 bprm->per_clear |= PER_CLEAR_ON_SETID; 1223 bprm->cred->egid = inode->i_gid; 1224 } 1225 } 1226 1227 /* fill in binprm security blob */ 1228 retval = security_bprm_set_creds(bprm); 1229 if (retval) 1230 return retval; 1231 bprm->cred_prepared = 1; 1232 1233 memset(bprm->buf, 0, BINPRM_BUF_SIZE); 1234 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); 1235} 1236 1237EXPORT_SYMBOL(prepare_binprm); 1238 1239/* 1240 * Arguments are '\0' separated strings found at the location bprm->p 1241 * points to; chop off the first by relocating brpm->p to right after 1242 * the first '\0' encountered. 1243 */ 1244int remove_arg_zero(struct linux_binprm *bprm) 1245{ 1246 int ret = 0; 1247 unsigned long offset; 1248 char *kaddr; 1249 struct page *page; 1250 1251 if (!bprm->argc) 1252 return 0; 1253 1254 do { 1255 offset = bprm->p & ~PAGE_MASK; 1256 page = get_arg_page(bprm, bprm->p, 0); 1257 if (!page) { 1258 ret = -EFAULT; 1259 goto out; 1260 } 1261 kaddr = kmap_atomic(page, KM_USER0); 1262 1263 for (; offset < PAGE_SIZE && kaddr[offset]; 1264 offset++, bprm->p++) 1265 ; 1266 1267 kunmap_atomic(kaddr, KM_USER0); 1268 put_arg_page(page); 1269 1270 if (offset == PAGE_SIZE) 1271 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); 1272 } while (offset == PAGE_SIZE); 1273 1274 bprm->p++; 1275 bprm->argc--; 1276 ret = 0; 1277 1278out: 1279 return ret; 1280} 1281EXPORT_SYMBOL(remove_arg_zero); 1282 1283/* 1284 * cycle the list of binary formats handler, until one recognizes the image 1285 */ 1286int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) 1287{ 1288 unsigned int depth = bprm->recursion_depth; 1289 int try,retval; 1290 struct linux_binfmt *fmt; 1291 1292 retval = security_bprm_check(bprm); 1293 if (retval) 1294 return retval; 1295 1296 /* kernel module loader fixup */ 1297 /* so we don't try to load run modprobe in kernel space. */ 1298 set_fs(USER_DS); 1299 1300 retval = audit_bprm(bprm); 1301 if (retval) 1302 return retval; 1303 1304 retval = -ENOENT; 1305 for (try=0; try<2; try++) { 1306 read_lock(&binfmt_lock); 1307 list_for_each_entry(fmt, &formats, lh) { 1308 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; 1309 if (!fn) 1310 continue; 1311 if (!try_module_get(fmt->module)) 1312 continue; 1313 read_unlock(&binfmt_lock); 1314 retval = fn(bprm, regs); 1315 /* 1316 * Restore the depth counter to its starting value 1317 * in this call, so we don't have to rely on every 1318 * load_binary function to restore it on return. 1319 */ 1320 bprm->recursion_depth = depth; 1321 if (retval >= 0) { 1322 if (depth == 0) 1323 tracehook_report_exec(fmt, bprm, regs); 1324 put_binfmt(fmt); 1325 allow_write_access(bprm->file); 1326 if (bprm->file) 1327 fput(bprm->file); 1328 bprm->file = NULL; 1329 current->did_exec = 1; 1330 proc_exec_connector(current); 1331 return retval; 1332 } 1333 read_lock(&binfmt_lock); 1334 put_binfmt(fmt); 1335 if (retval != -ENOEXEC || bprm->mm == NULL) 1336 break; 1337 if (!bprm->file) { 1338 read_unlock(&binfmt_lock); 1339 return retval; 1340 } 1341 } 1342 read_unlock(&binfmt_lock); 1343 if (retval != -ENOEXEC || bprm->mm == NULL) { 1344 break; 1345#ifdef CONFIG_MODULES 1346 } else { 1347#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) 1348 if (printable(bprm->buf[0]) && 1349 printable(bprm->buf[1]) && 1350 printable(bprm->buf[2]) && 1351 printable(bprm->buf[3])) 1352 break; /* -ENOEXEC */ 1353 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); 1354#endif 1355 } 1356 } 1357 return retval; 1358} 1359 1360EXPORT_SYMBOL(search_binary_handler); 1361 1362/* 1363 * sys_execve() executes a new program. 1364 */ 1365int do_execve(const char * filename, 1366 const char __user *const __user *argv, 1367 const char __user *const __user *envp, 1368 struct pt_regs * regs) 1369{ 1370 struct linux_binprm *bprm; 1371 struct file *file; 1372 struct files_struct *displaced; 1373 bool clear_in_exec; 1374 int retval; 1375 1376 retval = unshare_files(&displaced); 1377 if (retval) 1378 goto out_ret; 1379 1380 retval = -ENOMEM; 1381 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); 1382 if (!bprm) 1383 goto out_files; 1384 1385 retval = prepare_bprm_creds(bprm); 1386 if (retval) 1387 goto out_free; 1388 1389 retval = check_unsafe_exec(bprm); 1390 if (retval < 0) 1391 goto out_free; 1392 clear_in_exec = retval; 1393 current->in_execve = 1; 1394 1395 file = open_exec(filename); 1396 retval = PTR_ERR(file); 1397 if (IS_ERR(file)) 1398 goto out_unmark; 1399 1400 sched_exec(); 1401 1402 bprm->file = file; 1403 bprm->filename = filename; 1404 bprm->interp = filename; 1405 1406 retval = bprm_mm_init(bprm); 1407 if (retval) 1408 goto out_file; 1409 1410 bprm->argc = count(argv, MAX_ARG_STRINGS); 1411 if ((retval = bprm->argc) < 0) 1412 goto out; 1413 1414 bprm->envc = count(envp, MAX_ARG_STRINGS); 1415 if ((retval = bprm->envc) < 0) 1416 goto out; 1417 1418 retval = prepare_binprm(bprm); 1419 if (retval < 0) 1420 goto out; 1421 1422 retval = copy_strings_kernel(1, &bprm->filename, bprm); 1423 if (retval < 0) 1424 goto out; 1425 1426 bprm->exec = bprm->p; 1427 retval = copy_strings(bprm->envc, envp, bprm); 1428 if (retval < 0) 1429 goto out; 1430 1431 retval = copy_strings(bprm->argc, argv, bprm); 1432 if (retval < 0) 1433 goto out; 1434 1435 current->flags &= ~PF_KTHREAD; 1436 retval = search_binary_handler(bprm,regs); 1437 if (retval < 0) 1438 goto out; 1439 1440 /* execve succeeded */ 1441 current->fs->in_exec = 0; 1442 current->in_execve = 0; 1443 acct_update_integrals(current); 1444 free_bprm(bprm); 1445 if (displaced) 1446 put_files_struct(displaced); 1447 return retval; 1448 1449out: 1450 if (bprm->mm) { 1451 acct_arg_size(bprm, 0); 1452 mmput(bprm->mm); 1453 } 1454 1455out_file: 1456 if (bprm->file) { 1457 allow_write_access(bprm->file); 1458 fput(bprm->file); 1459 } 1460 1461out_unmark: 1462 if (clear_in_exec) 1463 current->fs->in_exec = 0; 1464 current->in_execve = 0; 1465 1466out_free: 1467 free_bprm(bprm); 1468 1469out_files: 1470 if (displaced) 1471 reset_files_struct(displaced); 1472out_ret: 1473 return retval; 1474} 1475 1476void set_binfmt(struct linux_binfmt *new) 1477{ 1478 struct mm_struct *mm = current->mm; 1479 1480 if (mm->binfmt) 1481 module_put(mm->binfmt->module); 1482 1483 mm->binfmt = new; 1484 if (new) 1485 __module_get(new->module); 1486} 1487 1488EXPORT_SYMBOL(set_binfmt); 1489 1490/* format_corename will inspect the pattern parameter, and output a 1491 * name into corename, which must have space for at least 1492 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. 1493 */ 1494static int format_corename(char *corename, long signr) 1495{ 1496 const struct cred *cred = current_cred(); 1497 const char *pat_ptr = core_pattern; 1498 int ispipe = (*pat_ptr == '|'); 1499 char *out_ptr = corename; 1500 char *const out_end = corename + CORENAME_MAX_SIZE; 1501 int rc; 1502 int pid_in_pattern = 0; 1503 1504 /* Repeat as long as we have more pattern to process and more output 1505 space */ 1506 while (*pat_ptr) { 1507 if (*pat_ptr != '%') { 1508 if (out_ptr == out_end) 1509 goto out; 1510 *out_ptr++ = *pat_ptr++; 1511 } else { 1512 switch (*++pat_ptr) { 1513 case 0: 1514 goto out; 1515 /* Double percent, output one percent */ 1516 case '%': 1517 if (out_ptr == out_end) 1518 goto out; 1519 *out_ptr++ = '%'; 1520 break; 1521 /* pid */ 1522 case 'p': 1523 pid_in_pattern = 1; 1524 rc = snprintf(out_ptr, out_end - out_ptr, 1525 "%d", task_tgid_vnr(current)); 1526 if (rc > out_end - out_ptr) 1527 goto out; 1528 out_ptr += rc; 1529 break; 1530 /* uid */ 1531 case 'u': 1532 rc = snprintf(out_ptr, out_end - out_ptr, 1533 "%d", cred->uid); 1534 if (rc > out_end - out_ptr) 1535 goto out; 1536 out_ptr += rc; 1537 break; 1538 /* gid */ 1539 case 'g': 1540 rc = snprintf(out_ptr, out_end - out_ptr, 1541 "%d", cred->gid); 1542 if (rc > out_end - out_ptr) 1543 goto out; 1544 out_ptr += rc; 1545 break; 1546 /* signal that caused the coredump */ 1547 case 's': 1548 rc = snprintf(out_ptr, out_end - out_ptr, 1549 "%ld", signr); 1550 if (rc > out_end - out_ptr) 1551 goto out; 1552 out_ptr += rc; 1553 break; 1554 /* UNIX time of coredump */ 1555 case 't': { 1556 struct timeval tv; 1557 do_gettimeofday(&tv); 1558 rc = snprintf(out_ptr, out_end - out_ptr, 1559 "%lu", tv.tv_sec); 1560 if (rc > out_end - out_ptr) 1561 goto out; 1562 out_ptr += rc; 1563 break; 1564 } 1565 /* hostname */ 1566 case 'h': 1567 down_read(&uts_sem); 1568 rc = snprintf(out_ptr, out_end - out_ptr, 1569 "%s", utsname()->nodename); 1570 up_read(&uts_sem); 1571 if (rc > out_end - out_ptr) 1572 goto out; 1573 out_ptr += rc; 1574 break; 1575 /* executable */ 1576 case 'e': 1577 rc = snprintf(out_ptr, out_end - out_ptr, 1578 "%s", current->comm); 1579 if (rc > out_end - out_ptr) 1580 goto out; 1581 out_ptr += rc; 1582 break; 1583 /* core limit size */ 1584 case 'c': 1585 rc = snprintf(out_ptr, out_end - out_ptr, 1586 "%lu", rlimit(RLIMIT_CORE)); 1587 if (rc > out_end - out_ptr) 1588 goto out; 1589 out_ptr += rc; 1590 break; 1591 default: 1592 break; 1593 } 1594 ++pat_ptr; 1595 } 1596 } 1597 /* Backward compatibility with core_uses_pid: 1598 * 1599 * If core_pattern does not include a %p (as is the default) 1600 * and core_uses_pid is set, then .%pid will be appended to 1601 * the filename. Do not do this for piped commands. */ 1602 if (!ispipe && !pid_in_pattern && core_uses_pid) { 1603 rc = snprintf(out_ptr, out_end - out_ptr, 1604 ".%d", task_tgid_vnr(current)); 1605 if (rc > out_end - out_ptr) 1606 goto out; 1607 out_ptr += rc; 1608 } 1609out: 1610 *out_ptr = 0; 1611 return ispipe; 1612} 1613 1614static int zap_process(struct task_struct *start, int exit_code) 1615{ 1616 struct task_struct *t; 1617 int nr = 0; 1618 1619 start->signal->flags = SIGNAL_GROUP_EXIT; 1620 start->signal->group_exit_code = exit_code; 1621 start->signal->group_stop_count = 0; 1622 1623 t = start; 1624 do { 1625 if (t != current && t->mm) { 1626 sigaddset(&t->pending.signal, SIGKILL); 1627 signal_wake_up(t, 1); 1628 nr++; 1629 } 1630 } while_each_thread(start, t); 1631 1632 return nr; 1633} 1634 1635static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, 1636 struct core_state *core_state, int exit_code) 1637{ 1638 struct task_struct *g, *p; 1639 unsigned long flags; 1640 int nr = -EAGAIN; 1641 1642 spin_lock_irq(&tsk->sighand->siglock); 1643 if (!signal_group_exit(tsk->signal)) { 1644 mm->core_state = core_state; 1645 nr = zap_process(tsk, exit_code); 1646 } 1647 spin_unlock_irq(&tsk->sighand->siglock); 1648 if (unlikely(nr < 0)) 1649 return nr; 1650 1651 if (atomic_read(&mm->mm_users) == nr + 1) 1652 goto done; 1653 /* 1654 * We should find and kill all tasks which use this mm, and we should 1655 * count them correctly into ->nr_threads. We don't take tasklist 1656 * lock, but this is safe wrt: 1657 * 1658 * fork: 1659 * None of sub-threads can fork after zap_process(leader). All 1660 * processes which were created before this point should be 1661 * visible to zap_threads() because copy_process() adds the new 1662 * process to the tail of init_task.tasks list, and lock/unlock 1663 * of ->siglock provides a memory barrier. 1664 * 1665 * do_exit: 1666 * The caller holds mm->mmap_sem. This means that the task which 1667 * uses this mm can't pass exit_mm(), so it can't exit or clear 1668 * its ->mm. 1669 * 1670 * de_thread: 1671 * It does list_replace_rcu(&leader->tasks, ¤t->tasks), 1672 * we must see either old or new leader, this does not matter. 1673 * However, it can change p->sighand, so lock_task_sighand(p) 1674 * must be used. Since p->mm != NULL and we hold ->mmap_sem 1675 * it can't fail. 1676 * 1677 * Note also that "g" can be the old leader with ->mm == NULL 1678 * and already unhashed and thus removed from ->thread_group. 1679 * This is OK, __unhash_process()->list_del_rcu() does not 1680 * clear the ->next pointer, we will find the new leader via 1681 * next_thread(). 1682 */ 1683 rcu_read_lock(); 1684 for_each_process(g) { 1685 if (g == tsk->group_leader) 1686 continue; 1687 if (g->flags & PF_KTHREAD) 1688 continue; 1689 p = g; 1690 do { 1691 if (p->mm) { 1692 if (unlikely(p->mm == mm)) { 1693 lock_task_sighand(p, &flags); 1694 nr += zap_process(p, exit_code); 1695 unlock_task_sighand(p, &flags); 1696 } 1697 break; 1698 } 1699 } while_each_thread(g, p); 1700 } 1701 rcu_read_unlock(); 1702done: 1703 atomic_set(&core_state->nr_threads, nr); 1704 return nr; 1705} 1706 1707static int coredump_wait(int exit_code, struct core_state *core_state) 1708{ 1709 struct task_struct *tsk = current; 1710 struct mm_struct *mm = tsk->mm; 1711 struct completion *vfork_done; 1712 int core_waiters = -EBUSY; 1713 1714 init_completion(&core_state->startup); 1715 core_state->dumper.task = tsk; 1716 core_state->dumper.next = NULL; 1717 1718 down_write(&mm->mmap_sem); 1719 if (!mm->core_state) 1720 core_waiters = zap_threads(tsk, mm, core_state, exit_code); 1721 up_write(&mm->mmap_sem); 1722 1723 if (unlikely(core_waiters < 0)) 1724 goto fail; 1725 1726 /* 1727 * Make sure nobody is waiting for us to release the VM, 1728 * otherwise we can deadlock when we wait on each other 1729 */ 1730 vfork_done = tsk->vfork_done; 1731 if (vfork_done) { 1732 tsk->vfork_done = NULL; 1733 complete(vfork_done); 1734 } 1735 1736 if (core_waiters) 1737 wait_for_completion(&core_state->startup); 1738fail: 1739 return core_waiters; 1740} 1741 1742static void coredump_finish(struct mm_struct *mm) 1743{ 1744 struct core_thread *curr, *next; 1745 struct task_struct *task; 1746 1747 next = mm->core_state->dumper.next; 1748 while ((curr = next) != NULL) { 1749 next = curr->next; 1750 task = curr->task; 1751 /* 1752 * see exit_mm(), curr->task must not see 1753 * ->task == NULL before we read ->next. 1754 */ 1755 smp_mb(); 1756 curr->task = NULL; 1757 wake_up_process(task); 1758 } 1759 1760 mm->core_state = NULL; 1761} 1762 1763/* 1764 * set_dumpable converts traditional three-value dumpable to two flags and 1765 * stores them into mm->flags. It modifies lower two bits of mm->flags, but 1766 * these bits are not changed atomically. So get_dumpable can observe the 1767 * intermediate state. To avoid doing unexpected behavior, get get_dumpable 1768 * return either old dumpable or new one by paying attention to the order of 1769 * modifying the bits. 1770 * 1771 * dumpable | mm->flags (binary) 1772 * old new | initial interim final 1773 * ---------+----------------------- 1774 * 0 1 | 00 01 01 1775 * 0 2 | 00 10(*) 11 1776 * 1 0 | 01 00 00 1777 * 1 2 | 01 11 11 1778 * 2 0 | 11 10(*) 00 1779 * 2 1 | 11 11 01 1780 * 1781 * (*) get_dumpable regards interim value of 10 as 11. 1782 */ 1783void set_dumpable(struct mm_struct *mm, int value) 1784{ 1785 switch (value) { 1786 case 0: 1787 clear_bit(MMF_DUMPABLE, &mm->flags); 1788 smp_wmb(); 1789 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1790 break; 1791 case 1: 1792 set_bit(MMF_DUMPABLE, &mm->flags); 1793 smp_wmb(); 1794 clear_bit(MMF_DUMP_SECURELY, &mm->flags); 1795 break; 1796 case 2: 1797 set_bit(MMF_DUMP_SECURELY, &mm->flags); 1798 smp_wmb(); 1799 set_bit(MMF_DUMPABLE, &mm->flags); 1800 break; 1801 } 1802} 1803 1804static int __get_dumpable(unsigned long mm_flags) 1805{ 1806 int ret; 1807 1808 ret = mm_flags & MMF_DUMPABLE_MASK; 1809 return (ret >= 2) ? 2 : ret; 1810} 1811 1812int get_dumpable(struct mm_struct *mm) 1813{ 1814 return __get_dumpable(mm->flags); 1815} 1816 1817static void wait_for_dump_helpers(struct file *file) 1818{ 1819 struct pipe_inode_info *pipe; 1820 1821 pipe = file->f_path.dentry->d_inode->i_pipe; 1822 1823 pipe_lock(pipe); 1824 pipe->readers++; 1825 pipe->writers--; 1826 1827 while ((pipe->readers > 1) && (!signal_pending(current))) { 1828 wake_up_interruptible_sync(&pipe->wait); 1829 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); 1830 pipe_wait(pipe); 1831 } 1832 1833 pipe->readers--; 1834 pipe->writers++; 1835 pipe_unlock(pipe); 1836 1837} 1838 1839 1840/* 1841 * uhm_pipe_setup 1842 * helper function to customize the process used 1843 * to collect the core in userspace. Specifically 1844 * it sets up a pipe and installs it as fd 0 (stdin) 1845 * for the process. Returns 0 on success, or 1846 * PTR_ERR on failure. 1847 * Note that it also sets the core limit to 1. This 1848 * is a special value that we use to trap recursive 1849 * core dumps 1850 */ 1851static int umh_pipe_setup(struct subprocess_info *info) 1852{ 1853 struct file *rp, *wp; 1854 struct fdtable *fdt; 1855 struct coredump_params *cp = (struct coredump_params *)info->data; 1856 struct files_struct *cf = current->files; 1857 1858 wp = create_write_pipe(0); 1859 if (IS_ERR(wp)) 1860 return PTR_ERR(wp); 1861 1862 rp = create_read_pipe(wp, 0); 1863 if (IS_ERR(rp)) { 1864 free_write_pipe(wp); 1865 return PTR_ERR(rp); 1866 } 1867 1868 cp->file = wp; 1869 1870 sys_close(0); 1871 fd_install(0, rp); 1872 spin_lock(&cf->file_lock); 1873 fdt = files_fdtable(cf); 1874 FD_SET(0, fdt->open_fds); 1875 FD_CLR(0, fdt->close_on_exec); 1876 spin_unlock(&cf->file_lock); 1877 1878 /* and disallow core files too */ 1879 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; 1880 1881 return 0; 1882} 1883 1884void do_coredump(long signr, int exit_code, struct pt_regs *regs) 1885{ 1886 struct core_state core_state; 1887 char corename[CORENAME_MAX_SIZE + 1]; 1888 struct mm_struct *mm = current->mm; 1889 struct linux_binfmt * binfmt; 1890 const struct cred *old_cred; 1891 struct cred *cred; 1892 int retval = 0; 1893 int flag = 0; 1894 int ispipe; 1895 static atomic_t core_dump_count = ATOMIC_INIT(0); 1896 struct coredump_params cprm = { 1897 .signr = signr, 1898 .regs = regs, 1899 .limit = rlimit(RLIMIT_CORE), 1900 /* 1901 * We must use the same mm->flags while dumping core to avoid 1902 * inconsistency of bit flags, since this flag is not protected 1903 * by any locks. 1904 */ 1905 .mm_flags = mm->flags, 1906 }; 1907 1908 audit_core_dumps(signr); 1909 1910 binfmt = mm->binfmt; 1911 if (!binfmt || !binfmt->core_dump) 1912 goto fail; 1913 if (!__get_dumpable(cprm.mm_flags)) 1914 goto fail; 1915 1916 cred = prepare_creds(); 1917 if (!cred) 1918 goto fail; 1919 /* 1920 * We cannot trust fsuid as being the "true" uid of the 1921 * process nor do we know its entire history. We only know it 1922 * was tainted so we dump it as root in mode 2. 1923 */ 1924 if (__get_dumpable(cprm.mm_flags) == 2) { 1925 /* Setuid core dump mode */ 1926 flag = O_EXCL; /* Stop rewrite attacks */ 1927 cred->fsuid = 0; /* Dump root private */ 1928 } 1929 1930 retval = coredump_wait(exit_code, &core_state); 1931 if (retval < 0) 1932 goto fail_creds; 1933 1934 old_cred = override_creds(cred); 1935 1936 /* 1937 * Clear any false indication of pending signals that might 1938 * be seen by the filesystem code called to write the core file. 1939 */ 1940 clear_thread_flag(TIF_SIGPENDING); 1941 1942 ispipe = format_corename(corename, signr); 1943 1944 if (ispipe) { 1945 int dump_count; 1946 char **helper_argv; 1947 1948 if (cprm.limit == 1) { 1949 /* 1950 * Normally core limits are irrelevant to pipes, since 1951 * we're not writing to the file system, but we use 1952 * cprm.limit of 1 here as a speacial value. Any 1953 * non-1 limit gets set to RLIM_INFINITY below, but 1954 * a limit of 0 skips the dump. This is a consistent 1955 * way to catch recursive crashes. We can still crash 1956 * if the core_pattern binary sets RLIM_CORE = !1 1957 * but it runs as root, and can do lots of stupid things 1958 * Note that we use task_tgid_vnr here to grab the pid 1959 * of the process group leader. That way we get the 1960 * right pid if a thread in a multi-threaded 1961 * core_pattern process dies. 1962 */ 1963 printk(KERN_WARNING 1964 "Process %d(%s) has RLIMIT_CORE set to 1\n", 1965 task_tgid_vnr(current), current->comm); 1966 printk(KERN_WARNING "Aborting core\n"); 1967 goto fail_unlock; 1968 } 1969 cprm.limit = RLIM_INFINITY; 1970 1971 dump_count = atomic_inc_return(&core_dump_count); 1972 if (core_pipe_limit && (core_pipe_limit < dump_count)) { 1973 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", 1974 task_tgid_vnr(current), current->comm); 1975 printk(KERN_WARNING "Skipping core dump\n"); 1976 goto fail_dropcount; 1977 } 1978 1979 helper_argv = argv_split(GFP_KERNEL, corename+1, NULL); 1980 if (!helper_argv) { 1981 printk(KERN_WARNING "%s failed to allocate memory\n", 1982 __func__); 1983 goto fail_dropcount; 1984 } 1985 1986 retval = call_usermodehelper_fns(helper_argv[0], helper_argv, 1987 NULL, UMH_WAIT_EXEC, umh_pipe_setup, 1988 NULL, &cprm); 1989 argv_free(helper_argv); 1990 if (retval) { 1991 printk(KERN_INFO "Core dump to %s pipe failed\n", 1992 corename); 1993 goto close_fail; 1994 } 1995 } else { 1996 struct inode *inode; 1997 1998 if (cprm.limit < binfmt->min_coredump) 1999 goto fail_unlock; 2000 2001 cprm.file = filp_open(corename, 2002 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 2003 0600); 2004 if (IS_ERR(cprm.file)) 2005 goto fail_unlock; 2006 2007 inode = cprm.file->f_path.dentry->d_inode; 2008 if (inode->i_nlink > 1) 2009 goto close_fail; 2010 if (d_unhashed(cprm.file->f_path.dentry)) 2011 goto close_fail; 2012 /* 2013 * AK: actually i see no reason to not allow this for named 2014 * pipes etc, but keep the previous behaviour for now. 2015 */ 2016 if (!S_ISREG(inode->i_mode)) 2017 goto close_fail; 2018 /* 2019 * Dont allow local users get cute and trick others to coredump 2020 * into their pre-created files. 2021 */ 2022 if (inode->i_uid != current_fsuid()) 2023 goto close_fail; 2024 if (!cprm.file->f_op || !cprm.file->f_op->write) 2025 goto close_fail; 2026 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) 2027 goto close_fail; 2028 } 2029 2030 retval = binfmt->core_dump(&cprm); 2031 if (retval) 2032 current->signal->group_exit_code |= 0x80; 2033 2034 if (ispipe && core_pipe_limit) 2035 wait_for_dump_helpers(cprm.file); 2036close_fail: 2037 if (cprm.file) 2038 filp_close(cprm.file, NULL); 2039fail_dropcount: 2040 if (ispipe) 2041 atomic_dec(&core_dump_count); 2042fail_unlock: 2043 coredump_finish(mm); 2044 revert_creds(old_cred); 2045fail_creds: 2046 put_cred(cred); 2047fail: 2048 return; 2049} 2050 2051/* 2052 * Core dumping helper functions. These are the only things you should 2053 * do on a core-file: use only these functions to write out all the 2054 * necessary info. 2055 */ 2056int dump_write(struct file *file, const void *addr, int nr) 2057{ 2058 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr; 2059} 2060EXPORT_SYMBOL(dump_write); 2061 2062int dump_seek(struct file *file, loff_t off) 2063{ 2064 int ret = 1; 2065 2066 if (file->f_op->llseek && file->f_op->llseek != no_llseek) { 2067 if (file->f_op->llseek(file, off, SEEK_CUR) < 0) 2068 return 0; 2069 } else { 2070 char *buf = (char *)get_zeroed_page(GFP_KERNEL); 2071 2072 if (!buf) 2073 return 0; 2074 while (off > 0) { 2075 unsigned long n = off; 2076 2077 if (n > PAGE_SIZE) 2078 n = PAGE_SIZE; 2079 if (!dump_write(file, buf, n)) { 2080 ret = 0; 2081 break; 2082 } 2083 off -= n; 2084 } 2085 free_page((unsigned long)buf); 2086 } 2087 return ret; 2088} 2089EXPORT_SYMBOL(dump_seek); 2090