fs/exec.c

   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/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
  55 #include <asm/uaccess.h>
  56 #include <asm/mmu_context.h>
  57 #include <asm/tlb.h>
  58
  59 #ifdef __alpha__
  60 /* for /sbin/loader handling in search_binary_handler() */
  61 #include <linux/a.out.h>
  62 #endif
  63
  64 int core_uses_pid;
  65 char core_pattern[CORENAME_MAX_SIZE] = "core";
  66 int suid_dumpable = 0;
  67
  68 /* The maximal length of core_pattern is also specified in sysctl.c */
  69
  70 static LIST_HEAD(formats);
  71 static DEFINE_RWLOCK(binfmt_lock);
  72
  73 int register_binfmt(struct linux_binfmt * fmt)
  74 {
  75         if (!fmt)
  76                 return -EINVAL;
  77         write_lock(&binfmt_lock);
  78         list_add(&fmt->lh, &formats);
  79         write_unlock(&binfmt_lock);
  80         return 0;
  81 }
  82
  83 EXPORT_SYMBOL(register_binfmt);
  84
  85 void unregister_binfmt(struct linux_binfmt * fmt)
  86 {
  87         write_lock(&binfmt_lock);
  88         list_del(&fmt->lh);
  89         write_unlock(&binfmt_lock);
  90 }
  91
  92 EXPORT_SYMBOL(unregister_binfmt);
  93
  94 static inline void put_binfmt(struct linux_binfmt * fmt)
  95 {
  96         module_put(fmt->module);
  97 }
  98
  99 /*
 100  * Note that a shared library must be both readable and executable due to
 101  * security reasons.
 102  *
 103  * Also note that we take the address to load from from the file itself.
 104  */
 105 asmlinkage long sys_uselib(const char __user * library)
 106 {
 107         struct file *file;
 108         struct nameidata nd;
 109         char *tmp = getname(library);
 110         int error = PTR_ERR(tmp);
 111
 112         if (!IS_ERR(tmp)) {
 113                 error = path_lookup_open(AT_FDCWD, tmp,
 114                                          LOOKUP_FOLLOW, &nd,
 115                                          FMODE_READ|FMODE_EXEC);
 116                 putname(tmp);
 117         }
 118         if (error)
 119                 goto out;
 120
 121         error = -EINVAL;
 122         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 123                 goto exit;
 124
 125         error = -EACCES;
 126         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 127                 goto exit;
 128
 129         error = vfs_permission(&nd, MAY_READ | MAY_EXEC | MAY_OPEN);
 130         if (error)
 131                 goto exit;
 132
 133         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 134         error = PTR_ERR(file);
 135         if (IS_ERR(file))
 136                 goto out;
 137
 138         error = -ENOEXEC;
 139         if(file->f_op) {
 140                 struct linux_binfmt * fmt;
 141
 142                 read_lock(&binfmt_lock);
 143                 list_for_each_entry(fmt, &formats, lh) {
 144                         if (!fmt->load_shlib)
 145                                 continue;
 146                         if (!try_module_get(fmt->module))
 147                                 continue;
 148                         read_unlock(&binfmt_lock);
 149                         error = fmt->load_shlib(file);
 150                         read_lock(&binfmt_lock);
 151                         put_binfmt(fmt);
 152                         if (error != -ENOEXEC)
 153                                 break;
 154                 }
 155                 read_unlock(&binfmt_lock);
 156         }
 157         fput(file);
 158 out:
 159         return error;
 160 exit:
 161         release_open_intent(&nd);
 162         path_put(&nd.path);
 163         goto out;
 164 }
 165
 166 #ifdef CONFIG_MMU
 167
 168 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 169                 int write)
 170 {
 171         struct page *page;
 172         int ret;
 173
 174 #ifdef CONFIG_STACK_GROWSUP
 175         if (write) {
 176                 ret = expand_stack_downwards(bprm->vma, pos);
 177                 if (ret < 0)
 178                         return NULL;
 179         }
 180 #endif
 181         ret = get_user_pages(current, bprm->mm, pos,
 182                         1, write, 1, &page, NULL);
 183         if (ret <= 0)
 184                 return NULL;
 185
 186         if (write) {
 187                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 188                 struct rlimit *rlim;
 189
 190                 /*
 191                  * We've historically supported up to 32 pages (ARG_MAX)
 192                  * of argument strings even with small stacks
 193                  */
 194                 if (size <= ARG_MAX)
 195                         return page;
 196
 197                 /*
 198                  * Limit to 1/4-th the stack size for the argv+env strings.
 199                  * This ensures that:
 200                  *  - the remaining binfmt code will not run out of stack space,
 201                  *  - the program will have a reasonable amount of stack left
 202                  *    to work from.
 203                  */
 204                 rlim = current->signal->rlim;
 205                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 206                         put_page(page);
 207                         return NULL;
 208                 }
 209         }
 210
 211         return page;
 212 }
 213
 214 static void put_arg_page(struct page *page)
 215 {
 216         put_page(page);
 217 }
 218
 219 static void free_arg_page(struct linux_binprm *bprm, int i)
 220 {
 221 }
 222
 223 static void free_arg_pages(struct linux_binprm *bprm)
 224 {
 225 }
 226
 227 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 228                 struct page *page)
 229 {
 230         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 231 }
 232
 233 static int __bprm_mm_init(struct linux_binprm *bprm)
 234 {
 235         int err = -ENOMEM;
 236         struct vm_area_struct *vma = NULL;
 237         struct mm_struct *mm = bprm->mm;
 238
 239         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 240         if (!vma)
 241                 goto err;
 242
 243         down_write(&mm->mmap_sem);
 244         vma->vm_mm = mm;
 245
 246         /*
 247          * Place the stack at the largest stack address the architecture
 248          * supports. Later, we'll move this to an appropriate place. We don't
 249          * use STACK_TOP because that can depend on attributes which aren't
 250          * configured yet.
 251          */
 252         vma->vm_end = STACK_TOP_MAX;
 253         vma->vm_start = vma->vm_end - PAGE_SIZE;
 254
 255         vma->vm_flags = VM_STACK_FLAGS;
 256         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 257         err = insert_vm_struct(mm, vma);
 258         if (err) {
 259                 up_write(&mm->mmap_sem);
 260                 goto err;
 261         }
 262
 263         mm->stack_vm = mm->total_vm = 1;
 264         up_write(&mm->mmap_sem);
 265
 266         bprm->p = vma->vm_end - sizeof(void *);
 267
 268         return 0;
 269
 270 err:
 271         if (vma) {
 272                 bprm->vma = NULL;
 273                 kmem_cache_free(vm_area_cachep, vma);
 274         }
 275
 276         return err;
 277 }
 278
 279 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 280 {
 281         return len <= MAX_ARG_STRLEN;
 282 }
 283
 284 #else
 285
 286 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 287                 int write)
 288 {
 289         struct page *page;
 290
 291         page = bprm->page[pos / PAGE_SIZE];
 292         if (!page && write) {
 293                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 294                 if (!page)
 295                         return NULL;
 296                 bprm->page[pos / PAGE_SIZE] = page;
 297         }
 298
 299         return page;
 300 }
 301
 302 static void put_arg_page(struct page *page)
 303 {
 304 }
 305
 306 static void free_arg_page(struct linux_binprm *bprm, int i)
 307 {
 308         if (bprm->page[i]) {
 309                 __free_page(bprm->page[i]);
 310                 bprm->page[i] = NULL;
 311         }
 312 }
 313
 314 static void free_arg_pages(struct linux_binprm *bprm)
 315 {
 316         int i;
 317
 318         for (i = 0; i < MAX_ARG_PAGES; i++)
 319                 free_arg_page(bprm, i);
 320 }
 321
 322 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 323                 struct page *page)
 324 {
 325 }
 326
 327 static int __bprm_mm_init(struct linux_binprm *bprm)
 328 {
 329         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 330         return 0;
 331 }
 332
 333 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 334 {
 335         return len <= bprm->p;
 336 }
 337
 338 #endif /* CONFIG_MMU */
 339
 340 /*
 341  * Create a new mm_struct and populate it with a temporary stack
 342  * vm_area_struct.  We don't have enough context at this point to set the stack
 343  * flags, permissions, and offset, so we use temporary values.  We'll update
 344  * them later in setup_arg_pages().
 345  */
 346 int bprm_mm_init(struct linux_binprm *bprm)
 347 {
 348         int err;
 349         struct mm_struct *mm = NULL;
 350
 351         bprm->mm = mm = mm_alloc();
 352         err = -ENOMEM;
 353         if (!mm)
 354                 goto err;
 355
 356         err = init_new_context(current, mm);
 357         if (err)
 358                 goto err;
 359
 360         err = __bprm_mm_init(bprm);
 361         if (err)
 362                 goto err;
 363
 364         return 0;
 365
 366 err:
 367         if (mm) {
 368                 bprm->mm = NULL;
 369                 mmdrop(mm);
 370         }
 371
 372         return err;
 373 }
 374
 375 /*
 376  * count() counts the number of strings in array ARGV.
 377  */
 378 static int count(char __user * __user * argv, int max)
 379 {
 380         int i = 0;
 381
 382         if (argv != NULL) {
 383                 for (;;) {
 384                         char __user * p;
 385
 386                         if (get_user(p, argv))
 387                                 return -EFAULT;
 388                         if (!p)
 389                                 break;
 390                         argv++;
 391                         if (i++ >= max)
 392                                 return -E2BIG;
 393                         cond_resched();
 394                 }
 395         }
 396         return i;
 397 }
 398
 399 /*
 400  * 'copy_strings()' copies argument/environment strings from the old
 401  * processes's memory to the new process's stack.  The call to get_user_pages()
 402  * ensures the destination page is created and not swapped out.
 403  */
 404 static int copy_strings(int argc, char __user * __user * argv,
 405                         struct linux_binprm *bprm)
 406 {
 407         struct page *kmapped_page = NULL;
 408         char *kaddr = NULL;
 409         unsigned long kpos = 0;
 410         int ret;
 411
 412         while (argc-- > 0) {
 413                 char __user *str;
 414                 int len;
 415                 unsigned long pos;
 416
 417                 if (get_user(str, argv+argc) ||
 418                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 419                         ret = -EFAULT;
 420                         goto out;
 421                 }
 422
 423                 if (!valid_arg_len(bprm, len)) {
 424                         ret = -E2BIG;
 425                         goto out;
 426                 }
 427
 428                 /* We're going to work our way backwords. */
 429                 pos = bprm->p;
 430                 str += len;
 431                 bprm->p -= len;
 432
 433                 while (len > 0) {
 434                         int offset, bytes_to_copy;
 435
 436                         offset = pos % PAGE_SIZE;
 437                         if (offset == 0)
 438                                 offset = PAGE_SIZE;
 439
 440                         bytes_to_copy = offset;
 441                         if (bytes_to_copy > len)
 442                                 bytes_to_copy = len;
 443
 444                         offset -= bytes_to_copy;
 445                         pos -= bytes_to_copy;
 446                         str -= bytes_to_copy;
 447                         len -= bytes_to_copy;
 448
 449                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 450                                 struct page *page;
 451
 452                                 page = get_arg_page(bprm, pos, 1);
 453                                 if (!page) {
 454                                         ret = -E2BIG;
 455                                         goto out;
 456                                 }
 457
 458                                 if (kmapped_page) {
 459                                         flush_kernel_dcache_page(kmapped_page);
 460                                         kunmap(kmapped_page);
 461                                         put_arg_page(kmapped_page);
 462                                 }
 463                                 kmapped_page = page;
 464                                 kaddr = kmap(kmapped_page);
 465                                 kpos = pos & PAGE_MASK;
 466                                 flush_arg_page(bprm, kpos, kmapped_page);
 467                         }
 468                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 469                                 ret = -EFAULT;
 470                                 goto out;
 471                         }
 472                 }
 473         }
 474         ret = 0;
 475 out:
 476         if (kmapped_page) {
 477                 flush_kernel_dcache_page(kmapped_page);
 478                 kunmap(kmapped_page);
 479                 put_arg_page(kmapped_page);
 480         }
 481         return ret;
 482 }
 483
 484 /*
 485  * Like copy_strings, but get argv and its values from kernel memory.
 486  */
 487 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 488 {
 489         int r;
 490         mm_segment_t oldfs = get_fs();
 491         set_fs(KERNEL_DS);
 492         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 493         set_fs(oldfs);
 494         return r;
 495 }
 496 EXPORT_SYMBOL(copy_strings_kernel);
 497
 498 #ifdef CONFIG_MMU
 499
 500 /*
 501  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 502  * the binfmt code determines where the new stack should reside, we shift it to
 503  * its final location.  The process proceeds as follows:
 504  *
 505  * 1) Use shift to calculate the new vma endpoints.
 506  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 507  *    arguments passed to subsequent functions are consistent.
 508  * 3) Move vma's page tables to the new range.
 509  * 4) Free up any cleared pgd range.
 510  * 5) Shrink the vma to cover only the new range.
 511  */
 512 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 513 {
 514         struct mm_struct *mm = vma->vm_mm;
 515         unsigned long old_start = vma->vm_start;
 516         unsigned long old_end = vma->vm_end;
 517         unsigned long length = old_end - old_start;
 518         unsigned long new_start = old_start - shift;
 519         unsigned long new_end = old_end - shift;
 520         struct mmu_gather *tlb;
 521
 522         BUG_ON(new_start > new_end);
 523
 524         /*
 525          * ensure there are no vmas between where we want to go
 526          * and where we are
 527          */
 528         if (vma != find_vma(mm, new_start))
 529                 return -EFAULT;
 530
 531         /*
 532          * cover the whole range: [new_start, old_end)
 533          */
 534         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 535
 536         /*
 537          * move the page tables downwards, on failure we rely on
 538          * process cleanup to remove whatever mess we made.
 539          */
 540         if (length != move_page_tables(vma, old_start,
 541                                        vma, new_start, length))
 542                 return -ENOMEM;
 543
 544         lru_add_drain();
 545         tlb = tlb_gather_mmu(mm, 0);
 546         if (new_end > old_start) {
 547                 /*
 548                  * when the old and new regions overlap clear from new_end.
 549                  */
 550                 free_pgd_range(tlb, new_end, old_end, new_end,
 551                         vma->vm_next ? vma->vm_next->vm_start : 0);
 552         } else {
 553                 /*
 554                  * otherwise, clean from old_start; this is done to not touch
 555                  * the address space in [new_end, old_start) some architectures
 556                  * have constraints on va-space that make this illegal (IA64) -
 557                  * for the others its just a little faster.
 558                  */
 559                 free_pgd_range(tlb, old_start, old_end, new_end,
 560                         vma->vm_next ? vma->vm_next->vm_start : 0);
 561         }
 562         tlb_finish_mmu(tlb, new_end, old_end);
 563
 564         /*
 565          * shrink the vma to just the new range.
 566          */
 567         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 568
 569         return 0;
 570 }
 571
 572 #define EXTRA_STACK_VM_PAGES    20      /* random */
 573
 574 /*
 575  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 576  * the stack is optionally relocated, and some extra space is added.
 577  */
 578 int setup_arg_pages(struct linux_binprm *bprm,
 579                     unsigned long stack_top,
 580                     int executable_stack)
 581 {
 582         unsigned long ret;
 583         unsigned long stack_shift;
 584         struct mm_struct *mm = current->mm;
 585         struct vm_area_struct *vma = bprm->vma;
 586         struct vm_area_struct *prev = NULL;
 587         unsigned long vm_flags;
 588         unsigned long stack_base;
 589
 590 #ifdef CONFIG_STACK_GROWSUP
 591         /* Limit stack size to 1GB */
 592         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 593         if (stack_base > (1 << 30))
 594                 stack_base = 1 << 30;
 595
 596         /* Make sure we didn't let the argument array grow too large. */
 597         if (vma->vm_end - vma->vm_start > stack_base)
 598                 return -ENOMEM;
 599
 600         stack_base = PAGE_ALIGN(stack_top - stack_base);
 601
 602         stack_shift = vma->vm_start - stack_base;
 603         mm->arg_start = bprm->p - stack_shift;
 604         bprm->p = vma->vm_end - stack_shift;
 605 #else
 606         stack_top = arch_align_stack(stack_top);
 607         stack_top = PAGE_ALIGN(stack_top);
 608         stack_shift = vma->vm_end - stack_top;
 609
 610         bprm->p -= stack_shift;
 611         mm->arg_start = bprm->p;
 612 #endif
 613
 614         if (bprm->loader)
 615                 bprm->loader -= stack_shift;
 616         bprm->exec -= stack_shift;
 617
 618         down_write(&mm->mmap_sem);
 619         vm_flags = VM_STACK_FLAGS;
 620
 621         /*
 622          * Adjust stack execute permissions; explicitly enable for
 623          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 624          * (arch default) otherwise.
 625          */
 626         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 627                 vm_flags |= VM_EXEC;
 628         else if (executable_stack == EXSTACK_DISABLE_X)
 629                 vm_flags &= ~VM_EXEC;
 630         vm_flags |= mm->def_flags;
 631
 632         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 633                         vm_flags);
 634         if (ret)
 635                 goto out_unlock;
 636         BUG_ON(prev != vma);
 637
 638         /* Move stack pages down in memory. */
 639         if (stack_shift) {
 640                 ret = shift_arg_pages(vma, stack_shift);
 641                 if (ret) {
 642                         up_write(&mm->mmap_sem);
 643                         return ret;
 644                 }
 645         }
 646
 647 #ifdef CONFIG_STACK_GROWSUP
 648         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 649 #else
 650         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 651 #endif
 652         ret = expand_stack(vma, stack_base);
 653         if (ret)
 654                 ret = -EFAULT;
 655
 656 out_unlock:
 657         up_write(&mm->mmap_sem);
 658         return 0;
 659 }
 660 EXPORT_SYMBOL(setup_arg_pages);
 661
 662 #endif /* CONFIG_MMU */
 663
 664 struct file *open_exec(const char *name)
 665 {
 666         struct nameidata nd;
 667         struct file *file;
 668         int err;
 669
 670         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
 671                                 FMODE_READ|FMODE_EXEC);
 672         if (err)
 673                 goto out;
 674
 675         err = -EACCES;
 676         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 677                 goto out_path_put;
 678
 679         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 680                 goto out_path_put;
 681
 682         err = vfs_permission(&nd, 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         err = deny_write_access(file);
 691         if (err) {
 692                 fput(file);
 693                 goto out;
 694         }
 695
 696         return file;
 697
 698  out_path_put:
 699         release_open_intent(&nd);
 700         path_put(&nd.path);
 701  out:
 702         return ERR_PTR(err);
 703 }
 704 EXPORT_SYMBOL(open_exec);
 705
 706 int kernel_read(struct file *file, unsigned long offset,
 707         char *addr, unsigned long count)
 708 {
 709         mm_segment_t old_fs;
 710         loff_t pos = offset;
 711         int result;
 712
 713         old_fs = get_fs();
 714         set_fs(get_ds());
 715         /* The cast to a user pointer is valid due to the set_fs() */
 716         result = vfs_read(file, (void __user *)addr, count, &pos);
 717         set_fs(old_fs);
 718         return result;
 719 }
 720
 721 EXPORT_SYMBOL(kernel_read);
 722
 723 static int exec_mmap(struct mm_struct *mm)
 724 {
 725         struct task_struct *tsk;
 726         struct mm_struct * old_mm, *active_mm;
 727
 728         /* Notify parent that we're no longer interested in the old VM */
 729         tsk = current;
 730         old_mm = current->mm;
 731         mm_release(tsk, old_mm);
 732
 733         if (old_mm) {
 734                 /*
 735                  * Make sure that if there is a core dump in progress
 736                  * for the old mm, we get out and die instead of going
 737                  * through with the exec.  We must hold mmap_sem around
 738                  * checking core_state and changing tsk->mm.
 739                  */
 740                 down_read(&old_mm->mmap_sem);
 741                 if (unlikely(old_mm->core_state)) {
 742                         up_read(&old_mm->mmap_sem);
 743                         return -EINTR;
 744                 }
 745         }
 746         task_lock(tsk);
 747         active_mm = tsk->active_mm;
 748         tsk->mm = mm;
 749         tsk->active_mm = mm;
 750         activate_mm(active_mm, mm);
 751         task_unlock(tsk);
 752         arch_pick_mmap_layout(mm);
 753         if (old_mm) {
 754                 up_read(&old_mm->mmap_sem);
 755                 BUG_ON(active_mm != old_mm);
 756                 mm_update_next_owner(old_mm);
 757                 mmput(old_mm);
 758                 return 0;
 759         }
 760         mmdrop(active_mm);
 761         return 0;
 762 }
 763
 764 /*
 765  * This function makes sure the current process has its own signal table,
 766  * so that flush_signal_handlers can later reset the handlers without
 767  * disturbing other processes.  (Other processes might share the signal
 768  * table via the CLONE_SIGHAND option to clone().)
 769  */
 770 static int de_thread(struct task_struct *tsk)
 771 {
 772         struct signal_struct *sig = tsk->signal;
 773         struct sighand_struct *oldsighand = tsk->sighand;
 774         spinlock_t *lock = &oldsighand->siglock;
 775         struct task_struct *leader = NULL;
 776         int count;
 777
 778         if (thread_group_empty(tsk))
 779                 goto no_thread_group;
 780
 781         /*
 782          * Kill all other threads in the thread group.
 783          */
 784         spin_lock_irq(lock);
 785         if (signal_group_exit(sig)) {
 786                 /*
 787                  * Another group action in progress, just
 788                  * return so that the signal is processed.
 789                  */
 790                 spin_unlock_irq(lock);
 791                 return -EAGAIN;
 792         }
 793         sig->group_exit_task = tsk;
 794         zap_other_threads(tsk);
 795
 796         /* Account for the thread group leader hanging around: */
 797         count = thread_group_leader(tsk) ? 1 : 2;
 798         sig->notify_count = count;
 799         while (atomic_read(&sig->count) > count) {
 800                 __set_current_state(TASK_UNINTERRUPTIBLE);
 801                 spin_unlock_irq(lock);
 802                 schedule();
 803                 spin_lock_irq(lock);
 804         }
 805         spin_unlock_irq(lock);
 806
 807         /*
 808          * At this point all other threads have exited, all we have to
 809          * do is to wait for the thread group leader to become inactive,
 810          * and to assume its PID:
 811          */
 812         if (!thread_group_leader(tsk)) {
 813                 leader = tsk->group_leader;
 814
 815                 sig->notify_count = -1; /* for exit_notify() */
 816                 for (;;) {
 817                         write_lock_irq(&tasklist_lock);
 818                         if (likely(leader->exit_state))
 819                                 break;
 820                         __set_current_state(TASK_UNINTERRUPTIBLE);
 821                         write_unlock_irq(&tasklist_lock);
 822                         schedule();
 823                 }
 824
 825                 /*
 826                  * The only record we have of the real-time age of a
 827                  * process, regardless of execs it's done, is start_time.
 828                  * All the past CPU time is accumulated in signal_struct
 829                  * from sister threads now dead.  But in this non-leader
 830                  * exec, nothing survives from the original leader thread,
 831                  * whose birth marks the true age of this process now.
 832                  * When we take on its identity by switching to its PID, we
 833                  * also take its birthdate (always earlier than our own).
 834                  */
 835                 tsk->start_time = leader->start_time;
 836
 837                 BUG_ON(!same_thread_group(leader, tsk));
 838                 BUG_ON(has_group_leader_pid(tsk));
 839                 /*
 840                  * An exec() starts a new thread group with the
 841                  * TGID of the previous thread group. Rehash the
 842                  * two threads with a switched PID, and release
 843                  * the former thread group leader:
 844                  */
 845
 846                 /* Become a process group leader with the old leader's pid.
 847                  * The old leader becomes a thread of the this thread group.
 848                  * Note: The old leader also uses this pid until release_task
 849                  *       is called.  Odd but simple and correct.
 850                  */
 851                 detach_pid(tsk, PIDTYPE_PID);
 852                 tsk->pid = leader->pid;
 853                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 854                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 855                 transfer_pid(leader, tsk, PIDTYPE_SID);
 856                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 857
 858                 tsk->group_leader = tsk;
 859                 leader->group_leader = tsk;
 860
 861                 tsk->exit_signal = SIGCHLD;
 862
 863                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 864                 leader->exit_state = EXIT_DEAD;
 865
 866                 write_unlock_irq(&tasklist_lock);
 867         }
 868
 869         sig->group_exit_task = NULL;
 870         sig->notify_count = 0;
 871
 872 no_thread_group:
 873         exit_itimers(sig);
 874         flush_itimer_signals();
 875         if (leader)
 876                 release_task(leader);
 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         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1011                 suid_keys(current);
1012                 set_dumpable(current->mm, suid_dumpable);
1013                 current->pdeath_signal = 0;
1014         } else if (file_permission(bprm->file, MAY_READ) ||
1015                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1016                 suid_keys(current);
1017                 set_dumpable(current->mm, suid_dumpable);
1018         }
1019
1020         /* An exec changes our domain. We are no longer part of the thread
1021            group */
1022
1023         current->self_exec_id++;
1024
1025         flush_signal_handlers(current, 0);
1026         flush_old_files(current->files);
1027
1028         return 0;
1029
1030 out:
1031         return retval;
1032 }
1033
1034 EXPORT_SYMBOL(flush_old_exec);
1035
1036 /*
1037  * Fill the binprm structure from the inode.
1038  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1039  */
1040 int prepare_binprm(struct linux_binprm *bprm)
1041 {
1042         int mode;
1043         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1044         int retval;
1045
1046         mode = inode->i_mode;
1047         if (bprm->file->f_op == NULL)
1048                 return -EACCES;
1049
1050         bprm->e_uid = current->euid;
1051         bprm->e_gid = current->egid;
1052
1053         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1054                 /* Set-uid? */
1055                 if (mode & S_ISUID) {
1056                         current->personality &= ~PER_CLEAR_ON_SETID;
1057                         bprm->e_uid = inode->i_uid;
1058                 }
1059
1060                 /* Set-gid? */
1061                 /*
1062                  * If setgid is set but no group execute bit then this
1063                  * is a candidate for mandatory locking, not a setgid
1064                  * executable.
1065                  */
1066                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1067                         current->personality &= ~PER_CLEAR_ON_SETID;
1068                         bprm->e_gid = inode->i_gid;
1069                 }
1070         }
1071
1072         /* fill in binprm security blob */
1073         retval = security_bprm_set(bprm);
1074         if (retval)
1075                 return retval;
1076
1077         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1078         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1079 }
1080
1081 EXPORT_SYMBOL(prepare_binprm);
1082
1083 static int unsafe_exec(struct task_struct *p)
1084 {
1085         int unsafe = tracehook_unsafe_exec(p);
1086
1087         if (atomic_read(&p->fs->count) > 1 ||
1088             atomic_read(&p->files->count) > 1 ||
1089             atomic_read(&p->sighand->count) > 1)
1090                 unsafe |= LSM_UNSAFE_SHARE;
1091
1092         return unsafe;
1093 }
1094
1095 void compute_creds(struct linux_binprm *bprm)
1096 {
1097         int unsafe;
1098
1099         if (bprm->e_uid != current->uid) {
1100                 suid_keys(current);
1101                 current->pdeath_signal = 0;
1102         }
1103         exec_keys(current);
1104
1105         task_lock(current);
1106         unsafe = unsafe_exec(current);
1107         security_bprm_apply_creds(bprm, unsafe);
1108         task_unlock(current);
1109         security_bprm_post_apply_creds(bprm);
1110 }
1111 EXPORT_SYMBOL(compute_creds);
1112
1113 /*
1114  * Arguments are '\0' separated strings found at the location bprm->p
1115  * points to; chop off the first by relocating brpm->p to right after
1116  * the first '\0' encountered.
1117  */
1118 int remove_arg_zero(struct linux_binprm *bprm)
1119 {
1120         int ret = 0;
1121         unsigned long offset;
1122         char *kaddr;
1123         struct page *page;
1124
1125         if (!bprm->argc)
1126                 return 0;
1127
1128         do {
1129                 offset = bprm->p & ~PAGE_MASK;
1130                 page = get_arg_page(bprm, bprm->p, 0);
1131                 if (!page) {
1132                         ret = -EFAULT;
1133                         goto out;
1134                 }
1135                 kaddr = kmap_atomic(page, KM_USER0);
1136
1137                 for (; offset < PAGE_SIZE && kaddr[offset];
1138                                 offset++, bprm->p++)
1139                         ;
1140
1141                 kunmap_atomic(kaddr, KM_USER0);
1142                 put_arg_page(page);
1143
1144                 if (offset == PAGE_SIZE)
1145                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1146         } while (offset == PAGE_SIZE);
1147
1148         bprm->p++;
1149         bprm->argc--;
1150         ret = 0;
1151
1152 out:
1153         return ret;
1154 }
1155 EXPORT_SYMBOL(remove_arg_zero);
1156
1157 /*
1158  * cycle the list of binary formats handler, until one recognizes the image
1159  */
1160 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1161 {
1162         int try,retval;
1163         struct linux_binfmt *fmt;
1164 #ifdef __alpha__
1165         /* handle /sbin/loader.. */
1166         {
1167             struct exec * eh = (struct exec *) bprm->buf;
1168
1169             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1170                 (eh->fh.f_flags & 0x3000) == 0x3000)
1171             {
1172                 struct file * file;
1173                 unsigned long loader;
1174
1175                 allow_write_access(bprm->file);
1176                 fput(bprm->file);
1177                 bprm->file = NULL;
1178
1179                 loader = bprm->vma->vm_end - sizeof(void *);
1180
1181                 file = open_exec("/sbin/loader");
1182                 retval = PTR_ERR(file);
1183                 if (IS_ERR(file))
1184                         return retval;
1185
1186                 /* Remember if the application is TASO.  */
1187                 bprm->taso = eh->ah.entry < 0x100000000UL;
1188
1189                 bprm->file = file;
1190                 bprm->loader = loader;
1191                 retval = prepare_binprm(bprm);
1192                 if (retval<0)
1193                         return retval;
1194                 /* should call search_binary_handler recursively here,
1195                    but it does not matter */
1196             }
1197         }
1198 #endif
1199         retval = security_bprm_check(bprm);
1200         if (retval)
1201                 return retval;
1202
1203         /* kernel module loader fixup */
1204         /* so we don't try to load run modprobe in kernel space. */
1205         set_fs(USER_DS);
1206
1207         retval = audit_bprm(bprm);
1208         if (retval)
1209                 return retval;
1210
1211         retval = -ENOENT;
1212         for (try=0; try<2; try++) {
1213                 read_lock(&binfmt_lock);
1214                 list_for_each_entry(fmt, &formats, lh) {
1215                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1216                         if (!fn)
1217                                 continue;
1218                         if (!try_module_get(fmt->module))
1219                                 continue;
1220                         read_unlock(&binfmt_lock);
1221                         retval = fn(bprm, regs);
1222                         if (retval >= 0) {
1223                                 tracehook_report_exec(fmt, bprm, regs);
1224                                 put_binfmt(fmt);
1225                                 allow_write_access(bprm->file);
1226                                 if (bprm->file)
1227                                         fput(bprm->file);
1228                                 bprm->file = NULL;
1229                                 current->did_exec = 1;
1230                                 proc_exec_connector(current);
1231                                 return retval;
1232                         }
1233                         read_lock(&binfmt_lock);
1234                         put_binfmt(fmt);
1235                         if (retval != -ENOEXEC || bprm->mm == NULL)
1236                                 break;
1237                         if (!bprm->file) {
1238                                 read_unlock(&binfmt_lock);
1239                                 return retval;
1240                         }
1241                 }
1242                 read_unlock(&binfmt_lock);
1243                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1244                         break;
1245 #ifdef CONFIG_MODULES
1246                 } else {
1247 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1248                         if (printable(bprm->buf[0]) &&
1249                             printable(bprm->buf[1]) &&
1250                             printable(bprm->buf[2]) &&
1251                             printable(bprm->buf[3]))
1252                                 break; /* -ENOEXEC */
1253                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1254 #endif
1255                 }
1256         }
1257         return retval;
1258 }
1259
1260 EXPORT_SYMBOL(search_binary_handler);
1261
1262 void free_bprm(struct linux_binprm *bprm)
1263 {
1264         free_arg_pages(bprm);
1265         kfree(bprm);
1266 }
1267
1268 /*
1269  * sys_execve() executes a new program.
1270  */
1271 int do_execve(char * filename,
1272         char __user *__user *argv,
1273         char __user *__user *envp,
1274         struct pt_regs * regs)
1275 {
1276         struct linux_binprm *bprm;
1277         struct file *file;
1278         struct files_struct *displaced;
1279         int retval;
1280
1281         retval = unshare_files(&displaced);
1282         if (retval)
1283                 goto out_ret;
1284
1285         retval = -ENOMEM;
1286         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1287         if (!bprm)
1288                 goto out_files;
1289
1290         file = open_exec(filename);
1291         retval = PTR_ERR(file);
1292         if (IS_ERR(file))
1293                 goto out_kfree;
1294
1295         sched_exec();
1296
1297         bprm->file = file;
1298         bprm->filename = filename;
1299         bprm->interp = filename;
1300
1301         retval = bprm_mm_init(bprm);
1302         if (retval)
1303                 goto out_file;
1304
1305         bprm->argc = count(argv, MAX_ARG_STRINGS);
1306         if ((retval = bprm->argc) < 0)
1307                 goto out_mm;
1308
1309         bprm->envc = count(envp, MAX_ARG_STRINGS);
1310         if ((retval = bprm->envc) < 0)
1311                 goto out_mm;
1312
1313         retval = security_bprm_alloc(bprm);
1314         if (retval)
1315                 goto out;
1316
1317         retval = prepare_binprm(bprm);
1318         if (retval < 0)
1319                 goto out;
1320
1321         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1322         if (retval < 0)
1323                 goto out;
1324
1325         bprm->exec = bprm->p;
1326         retval = copy_strings(bprm->envc, envp, bprm);
1327         if (retval < 0)
1328                 goto out;
1329
1330         retval = copy_strings(bprm->argc, argv, bprm);
1331         if (retval < 0)
1332                 goto out;
1333
1334         current->flags &= ~PF_KTHREAD;
1335         retval = search_binary_handler(bprm,regs);
1336         if (retval >= 0) {
1337                 /* execve success */
1338                 security_bprm_free(bprm);
1339                 acct_update_integrals(current);
1340                 free_bprm(bprm);
1341                 if (displaced)
1342                         put_files_struct(displaced);
1343                 return retval;
1344         }
1345
1346 out:
1347         if (bprm->security)
1348                 security_bprm_free(bprm);
1349
1350 out_mm:
1351         if (bprm->mm)
1352                 mmput (bprm->mm);
1353
1354 out_file:
1355         if (bprm->file) {
1356                 allow_write_access(bprm->file);
1357                 fput(bprm->file);
1358         }
1359 out_kfree:
1360         free_bprm(bprm);
1361
1362 out_files:
1363         if (displaced)
1364                 reset_files_struct(displaced);
1365 out_ret:
1366         return retval;
1367 }
1368
1369 int set_binfmt(struct linux_binfmt *new)
1370 {
1371         struct linux_binfmt *old = current->binfmt;
1372
1373         if (new) {
1374                 if (!try_module_get(new->module))
1375                         return -1;
1376         }
1377         current->binfmt = new;
1378         if (old)
1379                 module_put(old->module);
1380         return 0;
1381 }
1382
1383 EXPORT_SYMBOL(set_binfmt);
1384
1385 /* format_corename will inspect the pattern parameter, and output a
1386  * name into corename, which must have space for at least
1387  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1388  */
1389 static int format_corename(char *corename, long signr)
1390 {
1391         const char *pat_ptr = core_pattern;
1392         int ispipe = (*pat_ptr == '|');
1393         char *out_ptr = corename;
1394         char *const out_end = corename + CORENAME_MAX_SIZE;
1395         int rc;
1396         int pid_in_pattern = 0;
1397
1398         /* Repeat as long as we have more pattern to process and more output
1399            space */
1400         while (*pat_ptr) {
1401                 if (*pat_ptr != '%') {
1402                         if (out_ptr == out_end)
1403                                 goto out;
1404                         *out_ptr++ = *pat_ptr++;
1405                 } else {
1406                         switch (*++pat_ptr) {
1407                         case 0:
1408                                 goto out;
1409                         /* Double percent, output one percent */
1410                         case '%':
1411                                 if (out_ptr == out_end)
1412                                         goto out;
1413                                 *out_ptr++ = '%';
1414                                 break;
1415                         /* pid */
1416                         case 'p':
1417                                 pid_in_pattern = 1;
1418                                 rc = snprintf(out_ptr, out_end - out_ptr,
1419                                               "%d", task_tgid_vnr(current));
1420                                 if (rc > out_end - out_ptr)
1421                                         goto out;
1422                                 out_ptr += rc;
1423                                 break;
1424                         /* uid */
1425                         case 'u':
1426                                 rc = snprintf(out_ptr, out_end - out_ptr,
1427                                               "%d", current->uid);
1428                                 if (rc > out_end - out_ptr)
1429                                         goto out;
1430                                 out_ptr += rc;
1431                                 break;
1432                         /* gid */
1433                         case 'g':
1434                                 rc = snprintf(out_ptr, out_end - out_ptr,
1435                                               "%d", current->gid);
1436                                 if (rc > out_end - out_ptr)
1437                                         goto out;
1438                                 out_ptr += rc;
1439                                 break;
1440                         /* signal that caused the coredump */
1441                         case 's':
1442                                 rc = snprintf(out_ptr, out_end - out_ptr,
1443                                               "%ld", signr);
1444                                 if (rc > out_end - out_ptr)
1445                                         goto out;
1446                                 out_ptr += rc;
1447                                 break;
1448                         /* UNIX time of coredump */
1449                         case 't': {
1450                                 struct timeval tv;
1451                                 do_gettimeofday(&tv);
1452                                 rc = snprintf(out_ptr, out_end - out_ptr,
1453                                               "%lu", tv.tv_sec);
1454                                 if (rc > out_end - out_ptr)
1455                                         goto out;
1456                                 out_ptr += rc;
1457                                 break;
1458                         }
1459                         /* hostname */
1460                         case 'h':
1461                                 down_read(&uts_sem);
1462                                 rc = snprintf(out_ptr, out_end - out_ptr,
1463                                               "%s", utsname()->nodename);
1464                                 up_read(&uts_sem);
1465                                 if (rc > out_end - out_ptr)
1466                                         goto out;
1467                                 out_ptr += rc;
1468                                 break;
1469                         /* executable */
1470                         case 'e':
1471                                 rc = snprintf(out_ptr, out_end - out_ptr,
1472                                               "%s", current->comm);
1473                                 if (rc > out_end - out_ptr)
1474                                         goto out;
1475                                 out_ptr += rc;
1476                                 break;
1477                         /* core limit size */
1478                         case 'c':
1479                                 rc = snprintf(out_ptr, out_end - out_ptr,
1480                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1481                                 if (rc > out_end - out_ptr)
1482                                         goto out;
1483                                 out_ptr += rc;
1484                                 break;
1485                         default:
1486                                 break;
1487                         }
1488                         ++pat_ptr;
1489                 }
1490         }
1491         /* Backward compatibility with core_uses_pid:
1492          *
1493          * If core_pattern does not include a %p (as is the default)
1494          * and core_uses_pid is set, then .%pid will be appended to
1495          * the filename. Do not do this for piped commands. */
1496         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1497                 rc = snprintf(out_ptr, out_end - out_ptr,
1498                               ".%d", task_tgid_vnr(current));
1499                 if (rc > out_end - out_ptr)
1500                         goto out;
1501                 out_ptr += rc;
1502         }
1503 out:
1504         *out_ptr = 0;
1505         return ispipe;
1506 }
1507
1508 static int zap_process(struct task_struct *start)
1509 {
1510         struct task_struct *t;
1511         int nr = 0;
1512
1513         start->signal->flags = SIGNAL_GROUP_EXIT;
1514         start->signal->group_stop_count = 0;
1515
1516         t = start;
1517         do {
1518                 if (t != current && t->mm) {
1519                         sigaddset(&t->pending.signal, SIGKILL);
1520                         signal_wake_up(t, 1);
1521                         nr++;
1522                 }
1523         } while_each_thread(start, t);
1524
1525         return nr;
1526 }
1527
1528 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1529                                 struct core_state *core_state, int exit_code)
1530 {
1531         struct task_struct *g, *p;
1532         unsigned long flags;
1533         int nr = -EAGAIN;
1534
1535         spin_lock_irq(&tsk->sighand->siglock);
1536         if (!signal_group_exit(tsk->signal)) {
1537                 mm->core_state = core_state;
1538                 tsk->signal->group_exit_code = exit_code;
1539                 nr = zap_process(tsk);
1540         }
1541         spin_unlock_irq(&tsk->sighand->siglock);
1542         if (unlikely(nr < 0))
1543                 return nr;
1544
1545         if (atomic_read(&mm->mm_users) == nr + 1)
1546                 goto done;
1547         /*
1548          * We should find and kill all tasks which use this mm, and we should
1549          * count them correctly into ->nr_threads. We don't take tasklist
1550          * lock, but this is safe wrt:
1551          *
1552          * fork:
1553          *      None of sub-threads can fork after zap_process(leader). All
1554          *      processes which were created before this point should be
1555          *      visible to zap_threads() because copy_process() adds the new
1556          *      process to the tail of init_task.tasks list, and lock/unlock
1557          *      of ->siglock provides a memory barrier.
1558          *
1559          * do_exit:
1560          *      The caller holds mm->mmap_sem. This means that the task which
1561          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1562          *      its ->mm.
1563          *
1564          * de_thread:
1565          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1566          *      we must see either old or new leader, this does not matter.
1567          *      However, it can change p->sighand, so lock_task_sighand(p)
1568          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1569          *      it can't fail.
1570          *
1571          *      Note also that "g" can be the old leader with ->mm == NULL
1572          *      and already unhashed and thus removed from ->thread_group.
1573          *      This is OK, __unhash_process()->list_del_rcu() does not
1574          *      clear the ->next pointer, we will find the new leader via
1575          *      next_thread().
1576          */
1577         rcu_read_lock();
1578         for_each_process(g) {
1579                 if (g == tsk->group_leader)
1580                         continue;
1581                 if (g->flags & PF_KTHREAD)
1582                         continue;
1583                 p = g;
1584                 do {
1585                         if (p->mm) {
1586                                 if (unlikely(p->mm == mm)) {
1587                                         lock_task_sighand(p, &flags);
1588                                         nr += zap_process(p);
1589                                         unlock_task_sighand(p, &flags);
1590                                 }
1591                                 break;
1592                         }
1593                 } while_each_thread(g, p);
1594         }
1595         rcu_read_unlock();
1596 done:
1597         atomic_set(&core_state->nr_threads, nr);
1598         return nr;
1599 }
1600
1601 static int coredump_wait(int exit_code, struct core_state *core_state)
1602 {
1603         struct task_struct *tsk = current;
1604         struct mm_struct *mm = tsk->mm;
1605         struct completion *vfork_done;
1606         int core_waiters;
1607
1608         init_completion(&core_state->startup);
1609         core_state->dumper.task = tsk;
1610         core_state->dumper.next = NULL;
1611         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1612         up_write(&mm->mmap_sem);
1613
1614         if (unlikely(core_waiters < 0))
1615                 goto fail;
1616
1617         /*
1618          * Make sure nobody is waiting for us to release the VM,
1619          * otherwise we can deadlock when we wait on each other
1620          */
1621         vfork_done = tsk->vfork_done;
1622         if (vfork_done) {
1623                 tsk->vfork_done = NULL;
1624                 complete(vfork_done);
1625         }
1626
1627         if (core_waiters)
1628                 wait_for_completion(&core_state->startup);
1629 fail:
1630         return core_waiters;
1631 }
1632
1633 static void coredump_finish(struct mm_struct *mm)
1634 {
1635         struct core_thread *curr, *next;
1636         struct task_struct *task;
1637
1638         next = mm->core_state->dumper.next;
1639         while ((curr = next) != NULL) {
1640                 next = curr->next;
1641                 task = curr->task;
1642                 /*
1643                  * see exit_mm(), curr->task must not see
1644                  * ->task == NULL before we read ->next.
1645                  */
1646                 smp_mb();
1647                 curr->task = NULL;
1648                 wake_up_process(task);
1649         }
1650
1651         mm->core_state = NULL;
1652 }
1653
1654 /*
1655  * set_dumpable converts traditional three-value dumpable to two flags and
1656  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1657  * these bits are not changed atomically.  So get_dumpable can observe the
1658  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1659  * return either old dumpable or new one by paying attention to the order of
1660  * modifying the bits.
1661  *
1662  * dumpable |   mm->flags (binary)
1663  * old  new | initial interim  final
1664  * ---------+-----------------------
1665  *  0    1  |   00      01      01
1666  *  0    2  |   00      10(*)   11
1667  *  1    0  |   01      00      00
1668  *  1    2  |   01      11      11
1669  *  2    0  |   11      10(*)   00
1670  *  2    1  |   11      11      01
1671  *
1672  * (*) get_dumpable regards interim value of 10 as 11.
1673  */
1674 void set_dumpable(struct mm_struct *mm, int value)
1675 {
1676         switch (value) {
1677         case 0:
1678                 clear_bit(MMF_DUMPABLE, &mm->flags);
1679                 smp_wmb();
1680                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1681                 break;
1682         case 1:
1683                 set_bit(MMF_DUMPABLE, &mm->flags);
1684                 smp_wmb();
1685                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1686                 break;
1687         case 2:
1688                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1689                 smp_wmb();
1690                 set_bit(MMF_DUMPABLE, &mm->flags);
1691                 break;
1692         }
1693 }
1694
1695 int get_dumpable(struct mm_struct *mm)
1696 {
1697         int ret;
1698
1699         ret = mm->flags & 0x3;
1700         return (ret >= 2) ? 2 : ret;
1701 }
1702
1703 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1704 {
1705         struct core_state core_state;
1706         char corename[CORENAME_MAX_SIZE + 1];
1707         struct mm_struct *mm = current->mm;
1708         struct linux_binfmt * binfmt;
1709         struct inode * inode;
1710         struct file * file;
1711         int retval = 0;
1712         int fsuid = current->fsuid;
1713         int flag = 0;
1714         int ispipe = 0;
1715         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1716         char **helper_argv = NULL;
1717         int helper_argc = 0;
1718         char *delimit;
1719
1720         audit_core_dumps(signr);
1721
1722         binfmt = current->binfmt;
1723         if (!binfmt || !binfmt->core_dump)
1724                 goto fail;
1725         down_write(&mm->mmap_sem);
1726         /*
1727          * If another thread got here first, or we are not dumpable, bail out.
1728          */
1729         if (mm->core_state || !get_dumpable(mm)) {
1730                 up_write(&mm->mmap_sem);
1731                 goto fail;
1732         }
1733
1734         /*
1735          *      We cannot trust fsuid as being the "true" uid of the
1736          *      process nor do we know its entire history. We only know it
1737          *      was tainted so we dump it as root in mode 2.
1738          */
1739         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1740                 flag = O_EXCL;          /* Stop rewrite attacks */
1741                 current->fsuid = 0;     /* Dump root private */
1742         }
1743
1744         retval = coredump_wait(exit_code, &core_state);
1745         if (retval < 0)
1746                 goto fail;
1747
1748         /*
1749          * Clear any false indication of pending signals that might
1750          * be seen by the filesystem code called to write the core file.
1751          */
1752         clear_thread_flag(TIF_SIGPENDING);
1753
1754         /*
1755          * lock_kernel() because format_corename() is controlled by sysctl, which
1756          * uses lock_kernel()
1757          */
1758         lock_kernel();
1759         ispipe = format_corename(corename, signr);
1760         unlock_kernel();
1761         /*
1762          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1763          * to a pipe.  Since we're not writing directly to the filesystem
1764          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1765          * created unless the pipe reader choses to write out the core file
1766          * at which point file size limits and permissions will be imposed
1767          * as it does with any other process
1768          */
1769         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1770                 goto fail_unlock;
1771
1772         if (ispipe) {
1773                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1774                 /* Terminate the string before the first option */
1775                 delimit = strchr(corename, ' ');
1776                 if (delimit)
1777                         *delimit = '\0';
1778                 delimit = strrchr(helper_argv[0], '/');
1779                 if (delimit)
1780                         delimit++;
1781                 else
1782                         delimit = helper_argv[0];
1783                 if (!strcmp(delimit, current->comm)) {
1784                         printk(KERN_NOTICE "Recursive core dump detected, "
1785                                         "aborting\n");
1786                         goto fail_unlock;
1787                 }
1788
1789                 core_limit = RLIM_INFINITY;
1790
1791                 /* SIGPIPE can happen, but it's just never processed */
1792                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1793                                 &file)) {
1794                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1795                                corename);
1796                         goto fail_unlock;
1797                 }
1798         } else
1799                 file = filp_open(corename,
1800                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1801                                  0600);
1802         if (IS_ERR(file))
1803                 goto fail_unlock;
1804         inode = file->f_path.dentry->d_inode;
1805         if (inode->i_nlink > 1)
1806                 goto close_fail;        /* multiple links - don't dump */
1807         if (!ispipe && d_unhashed(file->f_path.dentry))
1808                 goto close_fail;
1809
1810         /* AK: actually i see no reason to not allow this for named pipes etc.,
1811            but keep the previous behaviour for now. */
1812         if (!ispipe && !S_ISREG(inode->i_mode))
1813                 goto close_fail;
1814         /*
1815          * Dont allow local users get cute and trick others to coredump
1816          * into their pre-created files:
1817          */
1818         if (inode->i_uid != current->fsuid)
1819                 goto close_fail;
1820         if (!file->f_op)
1821                 goto close_fail;
1822         if (!file->f_op->write)
1823                 goto close_fail;
1824         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1825                 goto close_fail;
1826
1827         retval = binfmt->core_dump(signr, regs, file, core_limit);
1828
1829         if (retval)
1830                 current->signal->group_exit_code |= 0x80;
1831 close_fail:
1832         filp_close(file, NULL);
1833 fail_unlock:
1834         if (helper_argv)
1835                 argv_free(helper_argv);
1836
1837         current->fsuid = fsuid;
1838         coredump_finish(mm);
1839 fail:
1840         return retval;
1841 }