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/config.h>
  26 #include <linux/slab.h>
  27 #include <linux/file.h>
  28 #include <linux/mman.h>
  29 #include <linux/a.out.h>
  30 #include <linux/stat.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/smp_lock.h>
  33 #include <linux/init.h>
  34 #include <linux/pagemap.h>
  35 #include <linux/highmem.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/key.h>
  38 #include <linux/personality.h>
  39 #include <linux/binfmts.h>
  40 #include <linux/swap.h>
  41 #include <linux/utsname.h>
  42 #include <linux/module.h>
  43 #include <linux/namei.h>
  44 #include <linux/proc_fs.h>
  45 #include <linux/ptrace.h>
  46 #include <linux/mount.h>
  47 #include <linux/security.h>
  48 #include <linux/syscalls.h>
  49 #include <linux/rmap.h>
  50 #include <linux/acct.h>
  51
  52 #include <asm/uaccess.h>
  53 #include <asm/mmu_context.h>
  54
  55 #ifdef CONFIG_KMOD
  56 #include <linux/kmod.h>
  57 #endif
  58
  59 int core_uses_pid;
  60 char core_pattern[65] = "core";
  61 /* The maximal length of core_pattern is also specified in sysctl.c */
  62
  63 static struct linux_binfmt *formats;
  64 static DEFINE_RWLOCK(binfmt_lock);
  65
  66 int register_binfmt(struct linux_binfmt * fmt)
  67 {
  68         struct linux_binfmt ** tmp = &formats;
  69
  70         if (!fmt)
  71                 return -EINVAL;
  72         if (fmt->next)
  73                 return -EBUSY;
  74         write_lock(&binfmt_lock);
  75         while (*tmp) {
  76                 if (fmt == *tmp) {
  77                         write_unlock(&binfmt_lock);
  78                         return -EBUSY;
  79                 }
  80                 tmp = &(*tmp)->next;
  81         }
  82         fmt->next = formats;
  83         formats = fmt;
  84         write_unlock(&binfmt_lock);
  85         return 0;
  86 }
  87
  88 EXPORT_SYMBOL(register_binfmt);
  89
  90 int unregister_binfmt(struct linux_binfmt * fmt)
  91 {
  92         struct linux_binfmt ** tmp = &formats;
  93
  94         write_lock(&binfmt_lock);
  95         while (*tmp) {
  96                 if (fmt == *tmp) {
  97                         *tmp = fmt->next;
  98                         write_unlock(&binfmt_lock);
  99                         return 0;
 100                 }
 101                 tmp = &(*tmp)->next;
 102         }
 103         write_unlock(&binfmt_lock);
 104         return -EINVAL;
 105 }
 106
 107 EXPORT_SYMBOL(unregister_binfmt);
 108
 109 static inline void put_binfmt(struct linux_binfmt * fmt)
 110 {
 111         module_put(fmt->module);
 112 }
 113
 114 /*
 115  * Note that a shared library must be both readable and executable due to
 116  * security reasons.
 117  *
 118  * Also note that we take the address to load from from the file itself.
 119  */
 120 asmlinkage long sys_uselib(const char __user * library)
 121 {
 122         struct file * file;
 123         struct nameidata nd;
 124         int error;
 125
 126         nd.intent.open.flags = FMODE_READ;
 127         error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 128         if (error)
 129                 goto out;
 130
 131         error = -EINVAL;
 132         if (!S_ISREG(nd.dentry->d_inode->i_mode))
 133                 goto exit;
 134
 135         error = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC, &nd);
 136         if (error)
 137                 goto exit;
 138
 139         file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
 140         error = PTR_ERR(file);
 141         if (IS_ERR(file))
 142                 goto out;
 143
 144         error = -ENOEXEC;
 145         if(file->f_op) {
 146                 struct linux_binfmt * fmt;
 147
 148                 read_lock(&binfmt_lock);
 149                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 150                         if (!fmt->load_shlib)
 151                                 continue;
 152                         if (!try_module_get(fmt->module))
 153                                 continue;
 154                         read_unlock(&binfmt_lock);
 155                         error = fmt->load_shlib(file);
 156                         read_lock(&binfmt_lock);
 157                         put_binfmt(fmt);
 158                         if (error != -ENOEXEC)
 159                                 break;
 160                 }
 161                 read_unlock(&binfmt_lock);
 162         }
 163         fput(file);
 164 out:
 165         return error;
 166 exit:
 167         path_release(&nd);
 168         goto out;
 169 }
 170
 171 /*
 172  * count() counts the number of strings in array ARGV.
 173  */
 174 static int count(char __user * __user * argv, int max)
 175 {
 176         int i = 0;
 177
 178         if (argv != NULL) {
 179                 for (;;) {
 180                         char __user * p;
 181
 182                         if (get_user(p, argv))
 183                                 return -EFAULT;
 184                         if (!p)
 185                                 break;
 186                         argv++;
 187                         if(++i > max)
 188                                 return -E2BIG;
 189                         cond_resched();
 190                 }
 191         }
 192         return i;
 193 }
 194
 195 /*
 196  * 'copy_strings()' copies argument/environment strings from user
 197  * memory to free pages in kernel mem. These are in a format ready
 198  * to be put directly into the top of new user memory.
 199  */
 200 static int copy_strings(int argc, char __user * __user * argv,
 201                         struct linux_binprm *bprm)
 202 {
 203         struct page *kmapped_page = NULL;
 204         char *kaddr = NULL;
 205         int ret;
 206
 207         while (argc-- > 0) {
 208                 char __user *str;
 209                 int len;
 210                 unsigned long pos;
 211
 212                 if (get_user(str, argv+argc) ||
 213                                 !(len = strnlen_user(str, bprm->p))) {
 214                         ret = -EFAULT;
 215                         goto out;
 216                 }
 217
 218                 if (bprm->p < len)  {
 219                         ret = -E2BIG;
 220                         goto out;
 221                 }
 222
 223                 bprm->p -= len;
 224                 /* XXX: add architecture specific overflow check here. */
 225                 pos = bprm->p;
 226
 227                 while (len > 0) {
 228                         int i, new, err;
 229                         int offset, bytes_to_copy;
 230                         struct page *page;
 231
 232                         offset = pos % PAGE_SIZE;
 233                         i = pos/PAGE_SIZE;
 234                         page = bprm->page[i];
 235                         new = 0;
 236                         if (!page) {
 237                                 page = alloc_page(GFP_HIGHUSER);
 238                                 bprm->page[i] = page;
 239                                 if (!page) {
 240                                         ret = -ENOMEM;
 241                                         goto out;
 242                                 }
 243                                 new = 1;
 244                         }
 245
 246                         if (page != kmapped_page) {
 247                                 if (kmapped_page)
 248                                         kunmap(kmapped_page);
 249                                 kmapped_page = page;
 250                                 kaddr = kmap(kmapped_page);
 251                         }
 252                         if (new && offset)
 253                                 memset(kaddr, 0, offset);
 254                         bytes_to_copy = PAGE_SIZE - offset;
 255                         if (bytes_to_copy > len) {
 256                                 bytes_to_copy = len;
 257                                 if (new)
 258                                         memset(kaddr+offset+len, 0,
 259                                                 PAGE_SIZE-offset-len);
 260                         }
 261                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
 262                         if (err) {
 263                                 ret = -EFAULT;
 264                                 goto out;
 265                         }
 266
 267                         pos += bytes_to_copy;
 268                         str += bytes_to_copy;
 269                         len -= bytes_to_copy;
 270                 }
 271         }
 272         ret = 0;
 273 out:
 274         if (kmapped_page)
 275                 kunmap(kmapped_page);
 276         return ret;
 277 }
 278
 279 /*
 280  * Like copy_strings, but get argv and its values from kernel memory.
 281  */
 282 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 283 {
 284         int r;
 285         mm_segment_t oldfs = get_fs();
 286         set_fs(KERNEL_DS);
 287         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 288         set_fs(oldfs);
 289         return r;
 290 }
 291
 292 EXPORT_SYMBOL(copy_strings_kernel);
 293
 294 #ifdef CONFIG_MMU
 295 /*
 296  * This routine is used to map in a page into an address space: needed by
 297  * execve() for the initial stack and environment pages.
 298  *
 299  * vma->vm_mm->mmap_sem is held for writing.
 300  */
 301 void install_arg_page(struct vm_area_struct *vma,
 302                         struct page *page, unsigned long address)
 303 {
 304         struct mm_struct *mm = vma->vm_mm;
 305         pgd_t * pgd;
 306         pud_t * pud;
 307         pmd_t * pmd;
 308         pte_t * pte;
 309
 310         if (unlikely(anon_vma_prepare(vma)))
 311                 goto out_sig;
 312
 313         flush_dcache_page(page);
 314         pgd = pgd_offset(mm, address);
 315
 316         spin_lock(&mm->page_table_lock);
 317         pud = pud_alloc(mm, pgd, address);
 318         if (!pud)
 319                 goto out;
 320         pmd = pmd_alloc(mm, pud, address);
 321         if (!pmd)
 322                 goto out;
 323         pte = pte_alloc_map(mm, pmd, address);
 324         if (!pte)
 325                 goto out;
 326         if (!pte_none(*pte)) {
 327                 pte_unmap(pte);
 328                 goto out;
 329         }
 330         inc_mm_counter(mm, rss);
 331         lru_cache_add_active(page);
 332         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
 333                                         page, vma->vm_page_prot))));
 334         page_add_anon_rmap(page, vma, address);
 335         pte_unmap(pte);
 336         spin_unlock(&mm->page_table_lock);
 337
 338         /* no need for flush_tlb */
 339         return;
 340 out:
 341         spin_unlock(&mm->page_table_lock);
 342 out_sig:
 343         __free_page(page);
 344         force_sig(SIGKILL, current);
 345 }
 346
 347 #define EXTRA_STACK_VM_PAGES    20      /* random */
 348
 349 int setup_arg_pages(struct linux_binprm *bprm,
 350                     unsigned long stack_top,
 351                     int executable_stack)
 352 {
 353         unsigned long stack_base;
 354         struct vm_area_struct *mpnt;
 355         struct mm_struct *mm = current->mm;
 356         int i, ret;
 357         long arg_size;
 358
 359 #ifdef CONFIG_STACK_GROWSUP
 360         /* Move the argument and environment strings to the bottom of the
 361          * stack space.
 362          */
 363         int offset, j;
 364         char *to, *from;
 365
 366         /* Start by shifting all the pages down */
 367         i = 0;
 368         for (j = 0; j < MAX_ARG_PAGES; j++) {
 369                 struct page *page = bprm->page[j];
 370                 if (!page)
 371                         continue;
 372                 bprm->page[i++] = page;
 373         }
 374
 375         /* Now move them within their pages */
 376         offset = bprm->p % PAGE_SIZE;
 377         to = kmap(bprm->page[0]);
 378         for (j = 1; j < i; j++) {
 379                 memmove(to, to + offset, PAGE_SIZE - offset);
 380                 from = kmap(bprm->page[j]);
 381                 memcpy(to + PAGE_SIZE - offset, from, offset);
 382                 kunmap(bprm->page[j - 1]);
 383                 to = from;
 384         }
 385         memmove(to, to + offset, PAGE_SIZE - offset);
 386         kunmap(bprm->page[j - 1]);
 387
 388         /* Limit stack size to 1GB */
 389         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 390         if (stack_base > (1 << 30))
 391                 stack_base = 1 << 30;
 392         stack_base = PAGE_ALIGN(stack_top - stack_base);
 393
 394         /* Adjust bprm->p to point to the end of the strings. */
 395         bprm->p = stack_base + PAGE_SIZE * i - offset;
 396
 397         mm->arg_start = stack_base;
 398         arg_size = i << PAGE_SHIFT;
 399
 400         /* zero pages that were copied above */
 401         while (i < MAX_ARG_PAGES)
 402                 bprm->page[i++] = NULL;
 403 #else
 404         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
 405         stack_base = PAGE_ALIGN(stack_base);
 406         bprm->p += stack_base;
 407         mm->arg_start = bprm->p;
 408         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
 409 #endif
 410
 411         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 412
 413         if (bprm->loader)
 414                 bprm->loader += stack_base;
 415         bprm->exec += stack_base;
 416
 417         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 418         if (!mpnt)
 419                 return -ENOMEM;
 420
 421         if (security_vm_enough_memory(arg_size >> PAGE_SHIFT)) {
 422                 kmem_cache_free(vm_area_cachep, mpnt);
 423                 return -ENOMEM;
 424         }
 425
 426         memset(mpnt, 0, sizeof(*mpnt));
 427
 428         down_write(&mm->mmap_sem);
 429         {
 430                 mpnt->vm_mm = mm;
 431 #ifdef CONFIG_STACK_GROWSUP
 432                 mpnt->vm_start = stack_base;
 433                 mpnt->vm_end = stack_base + arg_size;
 434 #else
 435                 mpnt->vm_end = stack_top;
 436                 mpnt->vm_start = mpnt->vm_end - arg_size;
 437 #endif
 438                 /* Adjust stack execute permissions; explicitly enable
 439                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
 440                  * and leave alone (arch default) otherwise. */
 441                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 442                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
 443                 else if (executable_stack == EXSTACK_DISABLE_X)
 444                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
 445                 else
 446                         mpnt->vm_flags = VM_STACK_FLAGS;
 447                 mpnt->vm_flags |= mm->def_flags;
 448                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
 449                 if ((ret = insert_vm_struct(mm, mpnt))) {
 450                         up_write(&mm->mmap_sem);
 451                         kmem_cache_free(vm_area_cachep, mpnt);
 452                         return ret;
 453                 }
 454                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
 455         }
 456
 457         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
 458                 struct page *page = bprm->page[i];
 459                 if (page) {
 460                         bprm->page[i] = NULL;
 461                         install_arg_page(mpnt, page, stack_base);
 462                 }
 463                 stack_base += PAGE_SIZE;
 464         }
 465         up_write(&mm->mmap_sem);
 466
 467         return 0;
 468 }
 469
 470 EXPORT_SYMBOL(setup_arg_pages);
 471
 472 #define free_arg_pages(bprm) do { } while (0)
 473
 474 #else
 475
 476 static inline void free_arg_pages(struct linux_binprm *bprm)
 477 {
 478         int i;
 479
 480         for (i = 0; i < MAX_ARG_PAGES; i++) {
 481                 if (bprm->page[i])
 482                         __free_page(bprm->page[i]);
 483                 bprm->page[i] = NULL;
 484         }
 485 }
 486
 487 #endif /* CONFIG_MMU */
 488
 489 struct file *open_exec(const char *name)
 490 {
 491         struct nameidata nd;
 492         int err;
 493         struct file *file;
 494
 495         nd.intent.open.flags = FMODE_READ;
 496         err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 497         file = ERR_PTR(err);
 498
 499         if (!err) {
 500                 struct inode *inode = nd.dentry->d_inode;
 501                 file = ERR_PTR(-EACCES);
 502                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
 503                     S_ISREG(inode->i_mode)) {
 504                         int err = permission(inode, MAY_EXEC, &nd);
 505                         if (!err && !(inode->i_mode & 0111))
 506                                 err = -EACCES;
 507                         file = ERR_PTR(err);
 508                         if (!err) {
 509                                 file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
 510                                 if (!IS_ERR(file)) {
 511                                         err = deny_write_access(file);
 512                                         if (err) {
 513                                                 fput(file);
 514                                                 file = ERR_PTR(err);
 515                                         }
 516                                 }
 517 out:
 518                                 return file;
 519                         }
 520                 }
 521                 path_release(&nd);
 522         }
 523         goto out;
 524 }
 525
 526 EXPORT_SYMBOL(open_exec);
 527
 528 int kernel_read(struct file *file, unsigned long offset,
 529         char *addr, unsigned long count)
 530 {
 531         mm_segment_t old_fs;
 532         loff_t pos = offset;
 533         int result;
 534
 535         old_fs = get_fs();
 536         set_fs(get_ds());
 537         /* The cast to a user pointer is valid due to the set_fs() */
 538         result = vfs_read(file, (void __user *)addr, count, &pos);
 539         set_fs(old_fs);
 540         return result;
 541 }
 542
 543 EXPORT_SYMBOL(kernel_read);
 544
 545 static int exec_mmap(struct mm_struct *mm)
 546 {
 547         struct task_struct *tsk;
 548         struct mm_struct * old_mm, *active_mm;
 549
 550         /* Notify parent that we're no longer interested in the old VM */
 551         tsk = current;
 552         old_mm = current->mm;
 553         mm_release(tsk, old_mm);
 554
 555         if (old_mm) {
 556                 /*
 557                  * Make sure that if there is a core dump in progress
 558                  * for the old mm, we get out and die instead of going
 559                  * through with the exec.  We must hold mmap_sem around
 560                  * checking core_waiters and changing tsk->mm.  The
 561                  * core-inducing thread will increment core_waiters for
 562                  * each thread whose ->mm == old_mm.
 563                  */
 564                 down_read(&old_mm->mmap_sem);
 565                 if (unlikely(old_mm->core_waiters)) {
 566                         up_read(&old_mm->mmap_sem);
 567                         return -EINTR;
 568                 }
 569         }
 570         task_lock(tsk);
 571         active_mm = tsk->active_mm;
 572         tsk->mm = mm;
 573         tsk->active_mm = mm;
 574         activate_mm(active_mm, mm);
 575         task_unlock(tsk);
 576         arch_pick_mmap_layout(mm);
 577         if (old_mm) {
 578                 up_read(&old_mm->mmap_sem);
 579                 if (active_mm != old_mm) BUG();
 580                 mmput(old_mm);
 581                 return 0;
 582         }
 583         mmdrop(active_mm);
 584         return 0;
 585 }
 586
 587 /*
 588  * This function makes sure the current process has its own signal table,
 589  * so that flush_signal_handlers can later reset the handlers without
 590  * disturbing other processes.  (Other processes might share the signal
 591  * table via the CLONE_SIGHAND option to clone().)
 592  */
 593 static inline int de_thread(struct task_struct *tsk)
 594 {
 595         struct signal_struct *sig = tsk->signal;
 596         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
 597         spinlock_t *lock = &oldsighand->siglock;
 598         int count;
 599
 600         /*
 601          * If we don't share sighandlers, then we aren't sharing anything
 602          * and we can just re-use it all.
 603          */
 604         if (atomic_read(&oldsighand->count) <= 1) {
 605                 BUG_ON(atomic_read(&sig->count) != 1);
 606                 exit_itimers(sig);
 607                 return 0;
 608         }
 609
 610         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 611         if (!newsighand)
 612                 return -ENOMEM;
 613
 614         if (thread_group_empty(current))
 615                 goto no_thread_group;
 616
 617         /*
 618          * Kill all other threads in the thread group.
 619          * We must hold tasklist_lock to call zap_other_threads.
 620          */
 621         read_lock(&tasklist_lock);
 622         spin_lock_irq(lock);
 623         if (sig->flags & SIGNAL_GROUP_EXIT) {
 624                 /*
 625                  * Another group action in progress, just
 626                  * return so that the signal is processed.
 627                  */
 628                 spin_unlock_irq(lock);
 629                 read_unlock(&tasklist_lock);
 630                 kmem_cache_free(sighand_cachep, newsighand);
 631                 return -EAGAIN;
 632         }
 633         zap_other_threads(current);
 634         read_unlock(&tasklist_lock);
 635
 636         /*
 637          * Account for the thread group leader hanging around:
 638          */
 639         count = 2;
 640         if (thread_group_leader(current))
 641                 count = 1;
 642         while (atomic_read(&sig->count) > count) {
 643                 sig->group_exit_task = current;
 644                 sig->notify_count = count;
 645                 __set_current_state(TASK_UNINTERRUPTIBLE);
 646                 spin_unlock_irq(lock);
 647                 schedule();
 648                 spin_lock_irq(lock);
 649         }
 650         sig->group_exit_task = NULL;
 651         sig->notify_count = 0;
 652         spin_unlock_irq(lock);
 653
 654         /*
 655          * At this point all other threads have exited, all we have to
 656          * do is to wait for the thread group leader to become inactive,
 657          * and to assume its PID:
 658          */
 659         if (!thread_group_leader(current)) {
 660                 struct task_struct *leader = current->group_leader, *parent;
 661                 struct dentry *proc_dentry1, *proc_dentry2;
 662                 unsigned long exit_state, ptrace;
 663
 664                 /*
 665                  * Wait for the thread group leader to be a zombie.
 666                  * It should already be zombie at this point, most
 667                  * of the time.
 668                  */
 669                 while (leader->exit_state != EXIT_ZOMBIE)
 670                         yield();
 671
 672                 spin_lock(&leader->proc_lock);
 673                 spin_lock(&current->proc_lock);
 674                 proc_dentry1 = proc_pid_unhash(current);
 675                 proc_dentry2 = proc_pid_unhash(leader);
 676                 write_lock_irq(&tasklist_lock);
 677
 678                 if (leader->tgid != current->tgid)
 679                         BUG();
 680                 if (current->pid == current->tgid)
 681                         BUG();
 682                 /*
 683                  * An exec() starts a new thread group with the
 684                  * TGID of the previous thread group. Rehash the
 685                  * two threads with a switched PID, and release
 686                  * the former thread group leader:
 687                  */
 688                 ptrace = leader->ptrace;
 689                 parent = leader->parent;
 690                 if (unlikely(ptrace) && unlikely(parent == current)) {
 691                         /*
 692                          * Joker was ptracing his own group leader,
 693                          * and now he wants to be his own parent!
 694                          * We can't have that.
 695                          */
 696                         ptrace = 0;
 697                 }
 698
 699                 ptrace_unlink(current);
 700                 ptrace_unlink(leader);
 701                 remove_parent(current);
 702                 remove_parent(leader);
 703
 704                 switch_exec_pids(leader, current);
 705
 706                 current->parent = current->real_parent = leader->real_parent;
 707                 leader->parent = leader->real_parent = child_reaper;
 708                 current->group_leader = current;
 709                 leader->group_leader = leader;
 710
 711                 add_parent(current, current->parent);
 712                 add_parent(leader, leader->parent);
 713                 if (ptrace) {
 714                         current->ptrace = ptrace;
 715                         __ptrace_link(current, parent);
 716                 }
 717
 718                 list_del(&current->tasks);
 719                 list_add_tail(&current->tasks, &init_task.tasks);
 720                 current->exit_signal = SIGCHLD;
 721                 exit_state = leader->exit_state;
 722
 723                 write_unlock_irq(&tasklist_lock);
 724                 spin_unlock(&leader->proc_lock);
 725                 spin_unlock(&current->proc_lock);
 726                 proc_pid_flush(proc_dentry1);
 727                 proc_pid_flush(proc_dentry2);
 728
 729                 if (exit_state != EXIT_ZOMBIE)
 730                         BUG();
 731                 release_task(leader);
 732         }
 733
 734         /*
 735          * Now there are really no other threads at all,
 736          * so it's safe to stop telling them to kill themselves.
 737          */
 738         sig->flags = 0;
 739
 740 no_thread_group:
 741         BUG_ON(atomic_read(&sig->count) != 1);
 742         exit_itimers(sig);
 743
 744         if (atomic_read(&oldsighand->count) == 1) {
 745                 /*
 746                  * Now that we nuked the rest of the thread group,
 747                  * it turns out we are not sharing sighand any more either.
 748                  * So we can just keep it.
 749                  */
 750                 kmem_cache_free(sighand_cachep, newsighand);
 751         } else {
 752                 /*
 753                  * Move our state over to newsighand and switch it in.
 754                  */
 755                 spin_lock_init(&newsighand->siglock);
 756                 atomic_set(&newsighand->count, 1);
 757                 memcpy(newsighand->action, oldsighand->action,
 758                        sizeof(newsighand->action));
 759
 760                 write_lock_irq(&tasklist_lock);
 761                 spin_lock(&oldsighand->siglock);
 762                 spin_lock(&newsighand->siglock);
 763
 764                 current->sighand = newsighand;
 765                 recalc_sigpending();
 766
 767                 spin_unlock(&newsighand->siglock);
 768                 spin_unlock(&oldsighand->siglock);
 769                 write_unlock_irq(&tasklist_lock);
 770
 771                 if (atomic_dec_and_test(&oldsighand->count))
 772                         kmem_cache_free(sighand_cachep, oldsighand);
 773         }
 774
 775         if (!thread_group_empty(current))
 776                 BUG();
 777         if (!thread_group_leader(current))
 778                 BUG();
 779         return 0;
 780 }
 781
 782 /*
 783  * These functions flushes out all traces of the currently running executable
 784  * so that a new one can be started
 785  */
 786
 787 static inline void flush_old_files(struct files_struct * files)
 788 {
 789         long j = -1;
 790
 791         spin_lock(&files->file_lock);
 792         for (;;) {
 793                 unsigned long set, i;
 794
 795                 j++;
 796                 i = j * __NFDBITS;
 797                 if (i >= files->max_fds || i >= files->max_fdset)
 798                         break;
 799                 set = files->close_on_exec->fds_bits[j];
 800                 if (!set)
 801                         continue;
 802                 files->close_on_exec->fds_bits[j] = 0;
 803                 spin_unlock(&files->file_lock);
 804                 for ( ; set ; i++,set >>= 1) {
 805                         if (set & 1) {
 806                                 sys_close(i);
 807                         }
 808                 }
 809                 spin_lock(&files->file_lock);
 810
 811         }
 812         spin_unlock(&files->file_lock);
 813 }
 814
 815 void get_task_comm(char *buf, struct task_struct *tsk)
 816 {
 817         /* buf must be at least sizeof(tsk->comm) in size */
 818         task_lock(tsk);
 819         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 820         task_unlock(tsk);
 821 }
 822
 823 void set_task_comm(struct task_struct *tsk, char *buf)
 824 {
 825         task_lock(tsk);
 826         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 827         task_unlock(tsk);
 828 }
 829
 830 int flush_old_exec(struct linux_binprm * bprm)
 831 {
 832         char * name;
 833         int i, ch, retval;
 834         struct files_struct *files;
 835         char tcomm[sizeof(current->comm)];
 836
 837         /*
 838          * Make sure we have a private signal table and that
 839          * we are unassociated from the previous thread group.
 840          */
 841         retval = de_thread(current);
 842         if (retval)
 843                 goto out;
 844
 845         /*
 846          * Make sure we have private file handles. Ask the
 847          * fork helper to do the work for us and the exit
 848          * helper to do the cleanup of the old one.
 849          */
 850         files = current->files;         /* refcounted so safe to hold */
 851         retval = unshare_files();
 852         if (retval)
 853                 goto out;
 854         /*
 855          * Release all of the old mmap stuff
 856          */
 857         retval = exec_mmap(bprm->mm);
 858         if (retval)
 859                 goto mmap_failed;
 860
 861         bprm->mm = NULL;                /* We're using it now */
 862
 863         /* This is the point of no return */
 864         steal_locks(files);
 865         put_files_struct(files);
 866
 867         current->sas_ss_sp = current->sas_ss_size = 0;
 868
 869         if (current->euid == current->uid && current->egid == current->gid)
 870                 current->mm->dumpable = 1;
 871         name = bprm->filename;
 872         for (i=0; (ch = *(name++)) != '\0';) {
 873                 if (ch == '/')
 874                         i = 0;
 875                 else
 876                         if (i < (sizeof(tcomm) - 1))
 877                                 tcomm[i++] = ch;
 878         }
 879         tcomm[i] = '\0';
 880         set_task_comm(current, tcomm);
 881
 882         current->flags &= ~PF_RANDOMIZE;
 883         flush_thread();
 884
 885         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
 886             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
 887             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
 888                 suid_keys(current);
 889                 current->mm->dumpable = 0;
 890         }
 891
 892         /* An exec changes our domain. We are no longer part of the thread
 893            group */
 894
 895         current->self_exec_id++;
 896
 897         flush_signal_handlers(current, 0);
 898         flush_old_files(current->files);
 899
 900         return 0;
 901
 902 mmap_failed:
 903         put_files_struct(current->files);
 904         current->files = files;
 905 out:
 906         return retval;
 907 }
 908
 909 EXPORT_SYMBOL(flush_old_exec);
 910
 911 /*
 912  * Fill the binprm structure from the inode.
 913  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 914  */
 915 int prepare_binprm(struct linux_binprm *bprm)
 916 {
 917         int mode;
 918         struct inode * inode = bprm->file->f_dentry->d_inode;
 919         int retval;
 920
 921         mode = inode->i_mode;
 922         /*
 923          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
 924          * generic_permission lets a non-executable through
 925          */
 926         if (!(mode & 0111))     /* with at least _one_ execute bit set */
 927                 return -EACCES;
 928         if (bprm->file->f_op == NULL)
 929                 return -EACCES;
 930
 931         bprm->e_uid = current->euid;
 932         bprm->e_gid = current->egid;
 933
 934         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
 935                 /* Set-uid? */
 936                 if (mode & S_ISUID) {
 937                         current->personality &= ~PER_CLEAR_ON_SETID;
 938                         bprm->e_uid = inode->i_uid;
 939                 }
 940
 941                 /* Set-gid? */
 942                 /*
 943                  * If setgid is set but no group execute bit then this
 944                  * is a candidate for mandatory locking, not a setgid
 945                  * executable.
 946                  */
 947                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 948                         current->personality &= ~PER_CLEAR_ON_SETID;
 949                         bprm->e_gid = inode->i_gid;
 950                 }
 951         }
 952
 953         /* fill in binprm security blob */
 954         retval = security_bprm_set(bprm);
 955         if (retval)
 956                 return retval;
 957
 958         memset(bprm->buf,0,BINPRM_BUF_SIZE);
 959         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
 960 }
 961
 962 EXPORT_SYMBOL(prepare_binprm);
 963
 964 static inline int unsafe_exec(struct task_struct *p)
 965 {
 966         int unsafe = 0;
 967         if (p->ptrace & PT_PTRACED) {
 968                 if (p->ptrace & PT_PTRACE_CAP)
 969                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
 970                 else
 971                         unsafe |= LSM_UNSAFE_PTRACE;
 972         }
 973         if (atomic_read(&p->fs->count) > 1 ||
 974             atomic_read(&p->files->count) > 1 ||
 975             atomic_read(&p->sighand->count) > 1)
 976                 unsafe |= LSM_UNSAFE_SHARE;
 977
 978         return unsafe;
 979 }
 980
 981 void compute_creds(struct linux_binprm *bprm)
 982 {
 983         int unsafe;
 984
 985         if (bprm->e_uid != current->uid)
 986                 suid_keys(current);
 987         exec_keys(current);
 988
 989         task_lock(current);
 990         unsafe = unsafe_exec(current);
 991         security_bprm_apply_creds(bprm, unsafe);
 992         task_unlock(current);
 993         security_bprm_post_apply_creds(bprm);
 994 }
 995
 996 EXPORT_SYMBOL(compute_creds);
 997
 998 void remove_arg_zero(struct linux_binprm *bprm)
 999 {
1000         if (bprm->argc) {
1001                 unsigned long offset;
1002                 char * kaddr;
1003                 struct page *page;
1004
1005                 offset = bprm->p % PAGE_SIZE;
1006                 goto inside;
1007
1008                 while (bprm->p++, *(kaddr+offset++)) {
1009                         if (offset != PAGE_SIZE)
1010                                 continue;
1011                         offset = 0;
1012                         kunmap_atomic(kaddr, KM_USER0);
1013 inside:
1014                         page = bprm->page[bprm->p/PAGE_SIZE];
1015                         kaddr = kmap_atomic(page, KM_USER0);
1016                 }
1017                 kunmap_atomic(kaddr, KM_USER0);
1018                 bprm->argc--;
1019         }
1020 }
1021
1022 EXPORT_SYMBOL(remove_arg_zero);
1023
1024 /*
1025  * cycle the list of binary formats handler, until one recognizes the image
1026  */
1027 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1028 {
1029         int try,retval;
1030         struct linux_binfmt *fmt;
1031 #ifdef __alpha__
1032         /* handle /sbin/loader.. */
1033         {
1034             struct exec * eh = (struct exec *) bprm->buf;
1035
1036             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1037                 (eh->fh.f_flags & 0x3000) == 0x3000)
1038             {
1039                 struct file * file;
1040                 unsigned long loader;
1041
1042                 allow_write_access(bprm->file);
1043                 fput(bprm->file);
1044                 bprm->file = NULL;
1045
1046                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1047
1048                 file = open_exec("/sbin/loader");
1049                 retval = PTR_ERR(file);
1050                 if (IS_ERR(file))
1051                         return retval;
1052
1053                 /* Remember if the application is TASO.  */
1054                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1055
1056                 bprm->file = file;
1057                 bprm->loader = loader;
1058                 retval = prepare_binprm(bprm);
1059                 if (retval<0)
1060                         return retval;
1061                 /* should call search_binary_handler recursively here,
1062                    but it does not matter */
1063             }
1064         }
1065 #endif
1066         retval = security_bprm_check(bprm);
1067         if (retval)
1068                 return retval;
1069
1070         /* kernel module loader fixup */
1071         /* so we don't try to load run modprobe in kernel space. */
1072         set_fs(USER_DS);
1073         retval = -ENOENT;
1074         for (try=0; try<2; try++) {
1075                 read_lock(&binfmt_lock);
1076                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1077                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1078                         if (!fn)
1079                                 continue;
1080                         if (!try_module_get(fmt->module))
1081                                 continue;
1082                         read_unlock(&binfmt_lock);
1083                         retval = fn(bprm, regs);
1084                         if (retval >= 0) {
1085                                 put_binfmt(fmt);
1086                                 allow_write_access(bprm->file);
1087                                 if (bprm->file)
1088                                         fput(bprm->file);
1089                                 bprm->file = NULL;
1090                                 current->did_exec = 1;
1091                                 return retval;
1092                         }
1093                         read_lock(&binfmt_lock);
1094                         put_binfmt(fmt);
1095                         if (retval != -ENOEXEC || bprm->mm == NULL)
1096                                 break;
1097                         if (!bprm->file) {
1098                                 read_unlock(&binfmt_lock);
1099                                 return retval;
1100                         }
1101                 }
1102                 read_unlock(&binfmt_lock);
1103                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1104                         break;
1105 #ifdef CONFIG_KMOD
1106                 }else{
1107 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1108                         if (printable(bprm->buf[0]) &&
1109                             printable(bprm->buf[1]) &&
1110                             printable(bprm->buf[2]) &&
1111                             printable(bprm->buf[3]))
1112                                 break; /* -ENOEXEC */
1113                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1114 #endif
1115                 }
1116         }
1117         return retval;
1118 }
1119
1120 EXPORT_SYMBOL(search_binary_handler);
1121
1122 /*
1123  * sys_execve() executes a new program.
1124  */
1125 int do_execve(char * filename,
1126         char __user *__user *argv,
1127         char __user *__user *envp,
1128         struct pt_regs * regs)
1129 {
1130         struct linux_binprm *bprm;
1131         struct file *file;
1132         int retval;
1133         int i;
1134
1135         retval = -ENOMEM;
1136         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1137         if (!bprm)
1138                 goto out_ret;
1139         memset(bprm, 0, sizeof(*bprm));
1140
1141         file = open_exec(filename);
1142         retval = PTR_ERR(file);
1143         if (IS_ERR(file))
1144                 goto out_kfree;
1145
1146         sched_exec();
1147
1148         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1149
1150         bprm->file = file;
1151         bprm->filename = filename;
1152         bprm->interp = filename;
1153         bprm->mm = mm_alloc();
1154         retval = -ENOMEM;
1155         if (!bprm->mm)
1156                 goto out_file;
1157
1158         retval = init_new_context(current, bprm->mm);
1159         if (retval < 0)
1160                 goto out_mm;
1161
1162         bprm->argc = count(argv, bprm->p / sizeof(void *));
1163         if ((retval = bprm->argc) < 0)
1164                 goto out_mm;
1165
1166         bprm->envc = count(envp, bprm->p / sizeof(void *));
1167         if ((retval = bprm->envc) < 0)
1168                 goto out_mm;
1169
1170         retval = security_bprm_alloc(bprm);
1171         if (retval)
1172                 goto out;
1173
1174         retval = prepare_binprm(bprm);
1175         if (retval < 0)
1176                 goto out;
1177
1178         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1179         if (retval < 0)
1180                 goto out;
1181
1182         bprm->exec = bprm->p;
1183         retval = copy_strings(bprm->envc, envp, bprm);
1184         if (retval < 0)
1185                 goto out;
1186
1187         retval = copy_strings(bprm->argc, argv, bprm);
1188         if (retval < 0)
1189                 goto out;
1190
1191         retval = search_binary_handler(bprm,regs);
1192         if (retval >= 0) {
1193                 free_arg_pages(bprm);
1194
1195                 /* execve success */
1196                 security_bprm_free(bprm);
1197                 acct_update_integrals(current);
1198                 update_mem_hiwater(current);
1199                 kfree(bprm);
1200                 return retval;
1201         }
1202
1203 out:
1204         /* Something went wrong, return the inode and free the argument pages*/
1205         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1206                 struct page * page = bprm->page[i];
1207                 if (page)
1208                         __free_page(page);
1209         }
1210
1211         if (bprm->security)
1212                 security_bprm_free(bprm);
1213
1214 out_mm:
1215         if (bprm->mm)
1216                 mmdrop(bprm->mm);
1217
1218 out_file:
1219         if (bprm->file) {
1220                 allow_write_access(bprm->file);
1221                 fput(bprm->file);
1222         }
1223
1224 out_kfree:
1225         kfree(bprm);
1226
1227 out_ret:
1228         return retval;
1229 }
1230
1231 int set_binfmt(struct linux_binfmt *new)
1232 {
1233         struct linux_binfmt *old = current->binfmt;
1234
1235         if (new) {
1236                 if (!try_module_get(new->module))
1237                         return -1;
1238         }
1239         current->binfmt = new;
1240         if (old)
1241                 module_put(old->module);
1242         return 0;
1243 }
1244
1245 EXPORT_SYMBOL(set_binfmt);
1246
1247 #define CORENAME_MAX_SIZE 64
1248
1249 /* format_corename will inspect the pattern parameter, and output a
1250  * name into corename, which must have space for at least
1251  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1252  */
1253 static void format_corename(char *corename, const char *pattern, long signr)
1254 {
1255         const char *pat_ptr = pattern;
1256         char *out_ptr = corename;
1257         char *const out_end = corename + CORENAME_MAX_SIZE;
1258         int rc;
1259         int pid_in_pattern = 0;
1260
1261         /* Repeat as long as we have more pattern to process and more output
1262            space */
1263         while (*pat_ptr) {
1264                 if (*pat_ptr != '%') {
1265                         if (out_ptr == out_end)
1266                                 goto out;
1267                         *out_ptr++ = *pat_ptr++;
1268                 } else {
1269                         switch (*++pat_ptr) {
1270                         case 0:
1271                                 goto out;
1272                         /* Double percent, output one percent */
1273                         case '%':
1274                                 if (out_ptr == out_end)
1275                                         goto out;
1276                                 *out_ptr++ = '%';
1277                                 break;
1278                         /* pid */
1279                         case 'p':
1280                                 pid_in_pattern = 1;
1281                                 rc = snprintf(out_ptr, out_end - out_ptr,
1282                                               "%d", current->tgid);
1283                                 if (rc > out_end - out_ptr)
1284                                         goto out;
1285                                 out_ptr += rc;
1286                                 break;
1287                         /* uid */
1288                         case 'u':
1289                                 rc = snprintf(out_ptr, out_end - out_ptr,
1290                                               "%d", current->uid);
1291                                 if (rc > out_end - out_ptr)
1292                                         goto out;
1293                                 out_ptr += rc;
1294                                 break;
1295                         /* gid */
1296                         case 'g':
1297                                 rc = snprintf(out_ptr, out_end - out_ptr,
1298                                               "%d", current->gid);
1299                                 if (rc > out_end - out_ptr)
1300                                         goto out;
1301                                 out_ptr += rc;
1302                                 break;
1303                         /* signal that caused the coredump */
1304                         case 's':
1305                                 rc = snprintf(out_ptr, out_end - out_ptr,
1306                                               "%ld", signr);
1307                                 if (rc > out_end - out_ptr)
1308                                         goto out;
1309                                 out_ptr += rc;
1310                                 break;
1311                         /* UNIX time of coredump */
1312                         case 't': {
1313                                 struct timeval tv;
1314                                 do_gettimeofday(&tv);
1315                                 rc = snprintf(out_ptr, out_end - out_ptr,
1316                                               "%lu", tv.tv_sec);
1317                                 if (rc > out_end - out_ptr)
1318                                         goto out;
1319                                 out_ptr += rc;
1320                                 break;
1321                         }
1322                         /* hostname */
1323                         case 'h':
1324                                 down_read(&uts_sem);
1325                                 rc = snprintf(out_ptr, out_end - out_ptr,
1326                                               "%s", system_utsname.nodename);
1327                                 up_read(&uts_sem);
1328                                 if (rc > out_end - out_ptr)
1329                                         goto out;
1330                                 out_ptr += rc;
1331                                 break;
1332                         /* executable */
1333                         case 'e':
1334                                 rc = snprintf(out_ptr, out_end - out_ptr,
1335                                               "%s", current->comm);
1336                                 if (rc > out_end - out_ptr)
1337                                         goto out;
1338                                 out_ptr += rc;
1339                                 break;
1340                         default:
1341                                 break;
1342                         }
1343                         ++pat_ptr;
1344                 }
1345         }
1346         /* Backward compatibility with core_uses_pid:
1347          *
1348          * If core_pattern does not include a %p (as is the default)
1349          * and core_uses_pid is set, then .%pid will be appended to
1350          * the filename */
1351         if (!pid_in_pattern
1352             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1353                 rc = snprintf(out_ptr, out_end - out_ptr,
1354                               ".%d", current->tgid);
1355                 if (rc > out_end - out_ptr)
1356                         goto out;
1357                 out_ptr += rc;
1358         }
1359       out:
1360         *out_ptr = 0;
1361 }
1362
1363 static void zap_threads (struct mm_struct *mm)
1364 {
1365         struct task_struct *g, *p;
1366         struct task_struct *tsk = current;
1367         struct completion *vfork_done = tsk->vfork_done;
1368         int traced = 0;
1369
1370         /*
1371          * Make sure nobody is waiting for us to release the VM,
1372          * otherwise we can deadlock when we wait on each other
1373          */
1374         if (vfork_done) {
1375                 tsk->vfork_done = NULL;
1376                 complete(vfork_done);
1377         }
1378
1379         read_lock(&tasklist_lock);
1380         do_each_thread(g,p)
1381                 if (mm == p->mm && p != tsk) {
1382                         force_sig_specific(SIGKILL, p);
1383                         mm->core_waiters++;
1384                         if (unlikely(p->ptrace) &&
1385                             unlikely(p->parent->mm == mm))
1386                                 traced = 1;
1387                 }
1388         while_each_thread(g,p);
1389
1390         read_unlock(&tasklist_lock);
1391
1392         if (unlikely(traced)) {
1393                 /*
1394                  * We are zapping a thread and the thread it ptraces.
1395                  * If the tracee went into a ptrace stop for exit tracing,
1396                  * we could deadlock since the tracer is waiting for this
1397                  * coredump to finish.  Detach them so they can both die.
1398                  */
1399                 write_lock_irq(&tasklist_lock);
1400                 do_each_thread(g,p) {
1401                         if (mm == p->mm && p != tsk &&
1402                             p->ptrace && p->parent->mm == mm) {
1403                                 __ptrace_unlink(p);
1404                         }
1405                 } while_each_thread(g,p);
1406                 write_unlock_irq(&tasklist_lock);
1407         }
1408 }
1409
1410 static void coredump_wait(struct mm_struct *mm)
1411 {
1412         DECLARE_COMPLETION(startup_done);
1413
1414         mm->core_waiters++; /* let other threads block */
1415         mm->core_startup_done = &startup_done;
1416
1417         /* give other threads a chance to run: */
1418         yield();
1419
1420         zap_threads(mm);
1421         if (--mm->core_waiters) {
1422                 up_write(&mm->mmap_sem);
1423                 wait_for_completion(&startup_done);
1424         } else
1425                 up_write(&mm->mmap_sem);
1426         BUG_ON(mm->core_waiters);
1427 }
1428
1429 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1430 {
1431         char corename[CORENAME_MAX_SIZE + 1];
1432         struct mm_struct *mm = current->mm;
1433         struct linux_binfmt * binfmt;
1434         struct inode * inode;
1435         struct file * file;
1436         int retval = 0;
1437
1438         binfmt = current->binfmt;
1439         if (!binfmt || !binfmt->core_dump)
1440                 goto fail;
1441         down_write(&mm->mmap_sem);
1442         if (!mm->dumpable) {
1443                 up_write(&mm->mmap_sem);
1444                 goto fail;
1445         }
1446         mm->dumpable = 0;
1447         init_completion(&mm->core_done);
1448         spin_lock_irq(&current->sighand->siglock);
1449         current->signal->flags = SIGNAL_GROUP_EXIT;
1450         current->signal->group_exit_code = exit_code;
1451         spin_unlock_irq(&current->sighand->siglock);
1452         coredump_wait(mm);
1453
1454         /*
1455          * Clear any false indication of pending signals that might
1456          * be seen by the filesystem code called to write the core file.
1457          */
1458         current->signal->group_stop_count = 0;
1459         clear_thread_flag(TIF_SIGPENDING);
1460
1461         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1462                 goto fail_unlock;
1463
1464         /*
1465          * lock_kernel() because format_corename() is controlled by sysctl, which
1466          * uses lock_kernel()
1467          */
1468         lock_kernel();
1469         format_corename(corename, core_pattern, signr);
1470         unlock_kernel();
1471         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE, 0600);
1472         if (IS_ERR(file))
1473                 goto fail_unlock;
1474         inode = file->f_dentry->d_inode;
1475         if (inode->i_nlink > 1)
1476                 goto close_fail;        /* multiple links - don't dump */
1477         if (d_unhashed(file->f_dentry))
1478                 goto close_fail;
1479
1480         if (!S_ISREG(inode->i_mode))
1481                 goto close_fail;
1482         if (!file->f_op)
1483                 goto close_fail;
1484         if (!file->f_op->write)
1485                 goto close_fail;
1486         if (do_truncate(file->f_dentry, 0) != 0)
1487                 goto close_fail;
1488
1489         retval = binfmt->core_dump(signr, regs, file);
1490
1491         if (retval)
1492                 current->signal->group_exit_code |= 0x80;
1493 close_fail:
1494         filp_close(file, NULL);
1495 fail_unlock:
1496         complete_all(&mm->core_done);
1497 fail:
1498         return retval;
1499 }