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