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 #include <linux/vs_memory.h>
  52
  53 #include <asm/uaccess.h>
  54 #include <asm/mmu_context.h>
  55
  56 #ifdef CONFIG_KMOD
  57 #include <linux/kmod.h>
  58 #endif
  59
  60 int core_uses_pid;
  61 char core_pattern[65] = "core";
  62 /* The maximal length of core_pattern is also specified in sysctl.c */
  63
  64 static struct linux_binfmt *formats;
  65 static DEFINE_RWLOCK(binfmt_lock);
  66
  67 int register_binfmt(struct linux_binfmt * fmt)
  68 {
  69         struct linux_binfmt ** tmp = &formats;
  70
  71         if (!fmt)
  72                 return -EINVAL;
  73         if (fmt->next)
  74                 return -EBUSY;
  75         write_lock(&binfmt_lock);
  76         while (*tmp) {
  77                 if (fmt == *tmp) {
  78                         write_unlock(&binfmt_lock);
  79                         return -EBUSY;
  80                 }
  81                 tmp = &(*tmp)->next;
  82         }
  83         fmt->next = formats;
  84         formats = fmt;
  85         write_unlock(&binfmt_lock);
  86         return 0;
  87 }
  88
  89 EXPORT_SYMBOL(register_binfmt);
  90
  91 int unregister_binfmt(struct linux_binfmt * fmt)
  92 {
  93         struct linux_binfmt ** tmp = &formats;
  94
  95         write_lock(&binfmt_lock);
  96         while (*tmp) {
  97                 if (fmt == *tmp) {
  98                         *tmp = fmt->next;
  99                         write_unlock(&binfmt_lock);
 100                         return 0;
 101                 }
 102                 tmp = &(*tmp)->next;
 103         }
 104         write_unlock(&binfmt_lock);
 105         return -EINVAL;
 106 }
 107
 108 EXPORT_SYMBOL(unregister_binfmt);
 109
 110 static inline void put_binfmt(struct linux_binfmt * fmt)
 111 {
 112         module_put(fmt->module);
 113 }
 114
 115 /*
 116  * Note that a shared library must be both readable and executable due to
 117  * security reasons.
 118  *
 119  * Also note that we take the address to load from from the file itself.
 120  */
 121 asmlinkage long sys_uselib(const char __user * library)
 122 {
 123         struct file * file;
 124         struct nameidata nd;
 125         int error;
 126
 127         nd.intent.open.flags = FMODE_READ;
 128         error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 129         if (error)
 130                 goto out;
 131
 132         error = -EINVAL;
 133         if (!S_ISREG(nd.dentry->d_inode->i_mode))
 134                 goto exit;
 135
 136         error = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC, &nd);
 137         if (error)
 138                 goto exit;
 139
 140         file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
 141         error = PTR_ERR(file);
 142         if (IS_ERR(file))
 143                 goto out;
 144
 145         error = -ENOEXEC;
 146         if(file->f_op) {
 147                 struct linux_binfmt * fmt;
 148
 149                 read_lock(&binfmt_lock);
 150                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 151                         if (!fmt->load_shlib)
 152                                 continue;
 153                         if (!try_module_get(fmt->module))
 154                                 continue;
 155                         read_unlock(&binfmt_lock);
 156                         error = fmt->load_shlib(file);
 157                         read_lock(&binfmt_lock);
 158                         put_binfmt(fmt);
 159                         if (error != -ENOEXEC)
 160                                 break;
 161                 }
 162                 read_unlock(&binfmt_lock);
 163         }
 164         fput(file);
 165 out:
 166         return error;
 167 exit:
 168         path_release(&nd);
 169         goto out;
 170 }
 171
 172 /*
 173  * count() counts the number of strings in array ARGV.
 174  */
 175 static int count(char __user * __user * argv, int max)
 176 {
 177         int i = 0;
 178
 179         if (argv != NULL) {
 180                 for (;;) {
 181                         char __user * p;
 182
 183                         if (get_user(p, argv))
 184                                 return -EFAULT;
 185                         if (!p)
 186                                 break;
 187                         argv++;
 188                         if(++i > max)
 189                                 return -E2BIG;
 190                         cond_resched();
 191                 }
 192         }
 193         return i;
 194 }
 195
 196 /*
 197  * 'copy_strings()' copies argument/environment strings from user
 198  * memory to free pages in kernel mem. These are in a format ready
 199  * to be put directly into the top of new user memory.
 200  */
 201 int copy_strings(int argc,char __user * __user * argv, 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         // mm->rss++;
 331         vx_rsspages_inc(mm);
 332         lru_cache_add_active(page);
 333         set_pte(pte, pte_mkdirty(pte_mkwrite(mk_pte(
 334                                         page, vma->vm_page_prot))));
 335         page_add_anon_rmap(page, vma, address);
 336         pte_unmap(pte);
 337         spin_unlock(&mm->page_table_lock);
 338
 339         /* no need for flush_tlb */
 340         return;
 341 out:
 342         spin_unlock(&mm->page_table_lock);
 343 out_sig:
 344         __free_page(page);
 345         force_sig(SIGKILL, current);
 346 }
 347
 348 #define EXTRA_STACK_VM_PAGES    20      /* random */
 349
 350 int setup_arg_pages(struct linux_binprm *bprm,
 351                     unsigned long stack_top,
 352                     int executable_stack)
 353 {
 354         unsigned long stack_base;
 355         struct vm_area_struct *mpnt;
 356         struct mm_struct *mm = current->mm;
 357         int i, ret;
 358         long arg_size;
 359
 360 #ifdef CONFIG_STACK_GROWSUP
 361         /* Move the argument and environment strings to the bottom of the
 362          * stack space.
 363          */
 364         int offset, j;
 365         char *to, *from;
 366
 367         /* Start by shifting all the pages down */
 368         i = 0;
 369         for (j = 0; j < MAX_ARG_PAGES; j++) {
 370                 struct page *page = bprm->page[j];
 371                 if (!page)
 372                         continue;
 373                 bprm->page[i++] = page;
 374         }
 375
 376         /* Now move them within their pages */
 377         offset = bprm->p % PAGE_SIZE;
 378         to = kmap(bprm->page[0]);
 379         for (j = 1; j < i; j++) {
 380                 memmove(to, to + offset, PAGE_SIZE - offset);
 381                 from = kmap(bprm->page[j]);
 382                 memcpy(to + PAGE_SIZE - offset, from, offset);
 383                 kunmap(bprm->page[j - 1]);
 384                 to = from;
 385         }
 386         memmove(to, to + offset, PAGE_SIZE - offset);
 387         kunmap(bprm->page[j - 1]);
 388
 389         /* Limit stack size to 1GB */
 390         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 391         if (stack_base > (1 << 30))
 392                 stack_base = 1 << 30;
 393         stack_base = PAGE_ALIGN(stack_top - stack_base);
 394
 395         /* Adjust bprm->p to point to the end of the strings. */
 396         bprm->p = stack_base + PAGE_SIZE * i - offset;
 397
 398         mm->arg_start = stack_base;
 399         arg_size = i << PAGE_SHIFT;
 400
 401         /* zero pages that were copied above */
 402         while (i < MAX_ARG_PAGES)
 403                 bprm->page[i++] = NULL;
 404 #else
 405         stack_base = stack_top - MAX_ARG_PAGES * PAGE_SIZE;
 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                 !vx_vmpages_avail(mm, arg_size >> PAGE_SHIFT)) {
 423                 kmem_cache_free(vm_area_cachep, mpnt);
 424                 return -ENOMEM;
 425         }
 426
 427         memset(mpnt, 0, sizeof(*mpnt));
 428
 429         down_write(&mm->mmap_sem);
 430         {
 431                 mpnt->vm_mm = mm;
 432 #ifdef CONFIG_STACK_GROWSUP
 433                 mpnt->vm_start = stack_base;
 434                 mpnt->vm_end = stack_base + arg_size;
 435 #else
 436                 mpnt->vm_end = stack_top;
 437                 mpnt->vm_start = mpnt->vm_end - arg_size;
 438 #endif
 439                 /* Adjust stack execute permissions; explicitly enable
 440                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
 441                  * and leave alone (arch default) otherwise. */
 442                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 443                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
 444                 else if (executable_stack == EXSTACK_DISABLE_X)
 445                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
 446                 else
 447                         mpnt->vm_flags = VM_STACK_FLAGS;
 448                 mpnt->vm_flags |= mm->def_flags;
 449                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
 450                 if ((ret = insert_vm_struct(mm, mpnt))) {
 451                         up_write(&mm->mmap_sem);
 452                         kmem_cache_free(vm_area_cachep, mpnt);
 453                         return ret;
 454                 }
 455                 // mm->stack_vm = mm->total_vm = vma_pages(mpnt);
 456                 vx_vmpages_sub(mm, mm->total_vm - vma_pages(mpnt));
 457                 mm->stack_vm = mm->total_vm;
 458         }
 459
 460         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
 461                 struct page *page = bprm->page[i];
 462                 if (page) {
 463                         bprm->page[i] = NULL;
 464                         install_arg_page(mpnt, page, stack_base);
 465                 }
 466                 stack_base += PAGE_SIZE;
 467         }
 468         up_write(&mm->mmap_sem);
 469
 470         return 0;
 471 }
 472
 473 EXPORT_SYMBOL(setup_arg_pages);
 474
 475 #define free_arg_pages(bprm) do { } while (0)
 476
 477 #else
 478
 479 static inline void free_arg_pages(struct linux_binprm *bprm)
 480 {
 481         int i;
 482
 483         for (i = 0; i < MAX_ARG_PAGES; i++) {
 484                 if (bprm->page[i])
 485                         __free_page(bprm->page[i]);
 486                 bprm->page[i] = NULL;
 487         }
 488 }
 489
 490 #endif /* CONFIG_MMU */
 491
 492 struct file *open_exec(const char *name)
 493 {
 494         struct nameidata nd;
 495         int err;
 496         struct file *file;
 497
 498         nd.intent.open.flags = FMODE_READ;
 499         err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 500         file = ERR_PTR(err);
 501
 502         if (!err) {
 503                 struct inode *inode = nd.dentry->d_inode;
 504                 file = ERR_PTR(-EACCES);
 505                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
 506                     S_ISREG(inode->i_mode)) {
 507                         int err = permission(inode, MAY_EXEC, &nd);
 508                         if (!err && !(inode->i_mode & 0111))
 509                                 err = -EACCES;
 510                         file = ERR_PTR(err);
 511                         if (!err) {
 512                                 file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
 513                                 if (!IS_ERR(file)) {
 514                                         err = deny_write_access(file);
 515                                         if (err) {
 516                                                 fput(file);
 517                                                 file = ERR_PTR(err);
 518                                         }
 519                                 }
 520 out:
 521                                 return file;
 522                         }
 523                 }
 524                 path_release(&nd);
 525         }
 526         goto out;
 527 }
 528
 529 EXPORT_SYMBOL(open_exec);
 530
 531 int kernel_read(struct file *file, unsigned long offset,
 532         char *addr, unsigned long count)
 533 {
 534         mm_segment_t old_fs;
 535         loff_t pos = offset;
 536         int result;
 537
 538         old_fs = get_fs();
 539         set_fs(get_ds());
 540         /* The cast to a user pointer is valid due to the set_fs() */
 541         result = vfs_read(file, (void __user *)addr, count, &pos);
 542         set_fs(old_fs);
 543         return result;
 544 }
 545
 546 EXPORT_SYMBOL(kernel_read);
 547
 548 static int exec_mmap(struct mm_struct *mm)
 549 {
 550         struct task_struct *tsk;
 551         struct mm_struct * old_mm, *active_mm;
 552
 553         /* Notify parent that we're no longer interested in the old VM */
 554         tsk = current;
 555         old_mm = current->mm;
 556         mm_release(tsk, old_mm);
 557
 558         if (old_mm) {
 559                 /*
 560                  * Make sure that if there is a core dump in progress
 561                  * for the old mm, we get out and die instead of going
 562                  * through with the exec.  We must hold mmap_sem around
 563                  * checking core_waiters and changing tsk->mm.  The
 564                  * core-inducing thread will increment core_waiters for
 565                  * each thread whose ->mm == old_mm.
 566                  */
 567                 down_read(&old_mm->mmap_sem);
 568                 if (unlikely(old_mm->core_waiters)) {
 569                         up_read(&old_mm->mmap_sem);
 570                         return -EINTR;
 571                 }
 572         }
 573         task_lock(tsk);
 574         active_mm = tsk->active_mm;
 575         tsk->mm = mm;
 576         tsk->active_mm = mm;
 577         activate_mm(active_mm, mm);
 578         task_unlock(tsk);
 579         arch_pick_mmap_layout(mm);
 580         if (old_mm) {
 581                 up_read(&old_mm->mmap_sem);
 582                 if (active_mm != old_mm) BUG();
 583                 mmput(old_mm);
 584                 return 0;
 585         }
 586         mmdrop(active_mm);
 587         return 0;
 588 }
 589
 590 /*
 591  * This function makes sure the current process has its own signal table,
 592  * so that flush_signal_handlers can later reset the handlers without
 593  * disturbing other processes.  (Other processes might share the signal
 594  * table via the CLONE_SIGHAND option to clone().)
 595  */
 596 static inline int de_thread(struct task_struct *tsk)
 597 {
 598         struct signal_struct *sig = tsk->signal;
 599         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
 600         spinlock_t *lock = &oldsighand->siglock;
 601         int count;
 602
 603         /*
 604          * If we don't share sighandlers, then we aren't sharing anything
 605          * and we can just re-use it all.
 606          */
 607         if (atomic_read(&oldsighand->count) <= 1) {
 608                 BUG_ON(atomic_read(&sig->count) != 1);
 609                 exit_itimers(sig);
 610                 return 0;
 611         }
 612
 613         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 614         if (!newsighand)
 615                 return -ENOMEM;
 616
 617         if (thread_group_empty(current))
 618                 goto no_thread_group;
 619
 620         /*
 621          * Kill all other threads in the thread group.
 622          * We must hold tasklist_lock to call zap_other_threads.
 623          */
 624         read_lock(&tasklist_lock);
 625         spin_lock_irq(lock);
 626         if (sig->flags & SIGNAL_GROUP_EXIT) {
 627                 /*
 628                  * Another group action in progress, just
 629                  * return so that the signal is processed.
 630                  */
 631                 spin_unlock_irq(lock);
 632                 read_unlock(&tasklist_lock);
 633                 kmem_cache_free(sighand_cachep, newsighand);
 634                 return -EAGAIN;
 635         }
 636         zap_other_threads(current);
 637         read_unlock(&tasklist_lock);
 638
 639         /*
 640          * Account for the thread group leader hanging around:
 641          */
 642         count = 2;
 643         if (thread_group_leader(current))
 644                 count = 1;
 645         while (atomic_read(&sig->count) > count) {
 646                 sig->group_exit_task = current;
 647                 sig->notify_count = count;
 648                 __set_current_state(TASK_UNINTERRUPTIBLE);
 649                 spin_unlock_irq(lock);
 650                 schedule();
 651                 spin_lock_irq(lock);
 652         }
 653         sig->group_exit_task = NULL;
 654         sig->notify_count = 0;
 655         spin_unlock_irq(lock);
 656
 657         /*
 658          * At this point all other threads have exited, all we have to
 659          * do is to wait for the thread group leader to become inactive,
 660          * and to assume its PID:
 661          */
 662         if (!thread_group_leader(current)) {
 663                 struct task_struct *leader = current->group_leader, *parent;
 664                 struct dentry *proc_dentry1, *proc_dentry2;
 665                 unsigned long exit_state, ptrace;
 666
 667                 /*
 668                  * Wait for the thread group leader to be a zombie.
 669                  * It should already be zombie at this point, most
 670                  * of the time.
 671                  */
 672                 while (leader->exit_state != EXIT_ZOMBIE)
 673                         yield();
 674
 675                 spin_lock(&leader->proc_lock);
 676                 spin_lock(&current->proc_lock);
 677                 proc_dentry1 = proc_pid_unhash(current);
 678                 proc_dentry2 = proc_pid_unhash(leader);
 679                 write_lock_irq(&tasklist_lock);
 680
 681                 if (leader->tgid != current->tgid)
 682                         BUG();
 683                 if (current->pid == current->tgid)
 684                         BUG();
 685                 /*
 686                  * An exec() starts a new thread group with the
 687                  * TGID of the previous thread group. Rehash the
 688                  * two threads with a switched PID, and release
 689                  * the former thread group leader:
 690                  */
 691                 ptrace = leader->ptrace;
 692                 parent = leader->parent;
 693                 if (unlikely(ptrace) && unlikely(parent == current)) {
 694                         /*
 695                          * Joker was ptracing his own group leader,
 696                          * and now he wants to be his own parent!
 697                          * We can't have that.
 698                          */
 699                         ptrace = 0;
 700                 }
 701
 702                 ptrace_unlink(current);
 703                 ptrace_unlink(leader);
 704                 remove_parent(current);
 705                 remove_parent(leader);
 706
 707                 switch_exec_pids(leader, current);
 708
 709                 current->parent = current->real_parent = leader->real_parent;
 710                 leader->parent = leader->real_parent = child_reaper;
 711                 current->group_leader = current;
 712                 leader->group_leader = leader;
 713
 714                 add_parent(current, current->parent);
 715                 add_parent(leader, leader->parent);
 716                 if (ptrace) {
 717                         current->ptrace = ptrace;
 718                         __ptrace_link(current, parent);
 719                 }
 720
 721                 list_del(&current->tasks);
 722                 list_add_tail(&current->tasks, &init_task.tasks);
 723                 current->exit_signal = SIGCHLD;
 724                 exit_state = leader->exit_state;
 725
 726                 write_unlock_irq(&tasklist_lock);
 727                 spin_unlock(&leader->proc_lock);
 728                 spin_unlock(&current->proc_lock);
 729                 proc_pid_flush(proc_dentry1);
 730                 proc_pid_flush(proc_dentry2);
 731
 732                 if (exit_state != EXIT_ZOMBIE)
 733                         BUG();
 734                 release_task(leader);
 735         }
 736
 737         /*
 738          * Now there are really no other threads at all,
 739          * so it's safe to stop telling them to kill themselves.
 740          */
 741         sig->flags = 0;
 742
 743 no_thread_group:
 744         BUG_ON(atomic_read(&sig->count) != 1);
 745         exit_itimers(sig);
 746
 747         if (atomic_read(&oldsighand->count) == 1) {
 748                 /*
 749                  * Now that we nuked the rest of the thread group,
 750                  * it turns out we are not sharing sighand any more either.
 751                  * So we can just keep it.
 752                  */
 753                 kmem_cache_free(sighand_cachep, newsighand);
 754         } else {
 755                 /*
 756                  * Move our state over to newsighand and switch it in.
 757                  */
 758                 spin_lock_init(&newsighand->siglock);
 759                 atomic_set(&newsighand->count, 1);
 760                 memcpy(newsighand->action, oldsighand->action,
 761                        sizeof(newsighand->action));
 762
 763                 write_lock_irq(&tasklist_lock);
 764                 spin_lock(&oldsighand->siglock);
 765                 spin_lock(&newsighand->siglock);
 766
 767                 current->sighand = newsighand;
 768                 recalc_sigpending();
 769
 770                 spin_unlock(&newsighand->siglock);
 771                 spin_unlock(&oldsighand->siglock);
 772                 write_unlock_irq(&tasklist_lock);
 773
 774                 if (atomic_dec_and_test(&oldsighand->count))
 775                         kmem_cache_free(sighand_cachep, oldsighand);
 776         }
 777
 778         if (!thread_group_empty(current))
 779                 BUG();
 780         if (!thread_group_leader(current))
 781                 BUG();
 782         return 0;
 783 }
 784
 785 /*
 786  * These functions flushes out all traces of the currently running executable
 787  * so that a new one can be started
 788  */
 789
 790 static inline void flush_old_files(struct files_struct * files)
 791 {
 792         long j = -1;
 793
 794         spin_lock(&files->file_lock);
 795         for (;;) {
 796                 unsigned long set, i;
 797
 798                 j++;
 799                 i = j * __NFDBITS;
 800                 if (i >= files->max_fds || i >= files->max_fdset)
 801                         break;
 802                 set = files->close_on_exec->fds_bits[j];
 803                 if (!set)
 804                         continue;
 805                 files->close_on_exec->fds_bits[j] = 0;
 806                 spin_unlock(&files->file_lock);
 807                 for ( ; set ; i++,set >>= 1) {
 808                         if (set & 1) {
 809                                 sys_close(i);
 810                         }
 811                 }
 812                 spin_lock(&files->file_lock);
 813
 814         }
 815         spin_unlock(&files->file_lock);
 816 }
 817
 818 void get_task_comm(char *buf, struct task_struct *tsk)
 819 {
 820         /* buf must be at least sizeof(tsk->comm) in size */
 821         task_lock(tsk);
 822         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 823         task_unlock(tsk);
 824 }
 825
 826 void set_task_comm(struct task_struct *tsk, char *buf)
 827 {
 828         task_lock(tsk);
 829         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 830         task_unlock(tsk);
 831 }
 832
 833 int flush_old_exec(struct linux_binprm * bprm)
 834 {
 835         char * name;
 836         int i, ch, retval;
 837         struct files_struct *files;
 838         char tcomm[sizeof(current->comm)];
 839
 840         /*
 841          * Make sure we have a private signal table and that
 842          * we are unassociated from the previous thread group.
 843          */
 844         retval = de_thread(current);
 845         if (retval)
 846                 goto out;
 847
 848         /*
 849          * Make sure we have private file handles. Ask the
 850          * fork helper to do the work for us and the exit
 851          * helper to do the cleanup of the old one.
 852          */
 853         files = current->files;         /* refcounted so safe to hold */
 854         retval = unshare_files();
 855         if (retval)
 856                 goto out;
 857         /*
 858          * Release all of the old mmap stuff
 859          */
 860         retval = exec_mmap(bprm->mm);
 861         if (retval)
 862                 goto mmap_failed;
 863
 864         bprm->mm = NULL;                /* We're using it now */
 865
 866         /* This is the point of no return */
 867         steal_locks(files);
 868         put_files_struct(files);
 869
 870         current->sas_ss_sp = current->sas_ss_size = 0;
 871
 872         if (current->euid == current->uid && current->egid == current->gid)
 873                 current->mm->dumpable = 1;
 874         name = bprm->filename;
 875         for (i=0; (ch = *(name++)) != '\0';) {
 876                 if (ch == '/')
 877                         i = 0;
 878                 else
 879                         if (i < (sizeof(tcomm) - 1))
 880                                 tcomm[i++] = ch;
 881         }
 882         tcomm[i] = '\0';
 883         set_task_comm(current, tcomm);
 884
 885         flush_thread();
 886
 887         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
 888             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
 889             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
 890                 suid_keys(current);
 891                 current->mm->dumpable = 0;
 892         }
 893
 894         /* An exec changes our domain. We are no longer part of the thread
 895            group */
 896
 897         current->self_exec_id++;
 898
 899         flush_signal_handlers(current, 0);
 900         flush_old_files(current->files);
 901
 902         return 0;
 903
 904 mmap_failed:
 905         put_files_struct(current->files);
 906         current->files = files;
 907 out:
 908         return retval;
 909 }
 910
 911 EXPORT_SYMBOL(flush_old_exec);
 912
 913 /*
 914  * Fill the binprm structure from the inode.
 915  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 916  */
 917 int prepare_binprm(struct linux_binprm *bprm)
 918 {
 919         int mode;
 920         struct inode * inode = bprm->file->f_dentry->d_inode;
 921         int retval;
 922
 923         mode = inode->i_mode;
 924         /*
 925          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
 926          * generic_permission lets a non-executable through
 927          */
 928         if (!(mode & 0111))     /* with at least _one_ execute bit set */
 929                 return -EACCES;
 930         if (bprm->file->f_op == NULL)
 931                 return -EACCES;
 932
 933         bprm->e_uid = current->euid;
 934         bprm->e_gid = current->egid;
 935
 936         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
 937                 /* Set-uid? */
 938                 if (mode & S_ISUID) {
 939                         current->personality &= ~PER_CLEAR_ON_SETID;
 940                         bprm->e_uid = inode->i_uid;
 941                 }
 942
 943                 /* Set-gid? */
 944                 /*
 945                  * If setgid is set but no group execute bit then this
 946                  * is a candidate for mandatory locking, not a setgid
 947                  * executable.
 948                  */
 949                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 950                         current->personality &= ~PER_CLEAR_ON_SETID;
 951                         bprm->e_gid = inode->i_gid;
 952                 }
 953         }
 954
 955         /* fill in binprm security blob */
 956         retval = security_bprm_set(bprm);
 957         if (retval)
 958                 return retval;
 959
 960         memset(bprm->buf,0,BINPRM_BUF_SIZE);
 961         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
 962 }
 963
 964 EXPORT_SYMBOL(prepare_binprm);
 965
 966 static inline int unsafe_exec(struct task_struct *p)
 967 {
 968         int unsafe = 0;
 969         if (p->ptrace & PT_PTRACED) {
 970                 if (p->ptrace & PT_PTRACE_CAP)
 971                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
 972                 else
 973                         unsafe |= LSM_UNSAFE_PTRACE;
 974         }
 975         if (atomic_read(&p->fs->count) > 1 ||
 976             atomic_read(&p->files->count) > 1 ||
 977             atomic_read(&p->sighand->count) > 1)
 978                 unsafe |= LSM_UNSAFE_SHARE;
 979
 980         return unsafe;
 981 }
 982
 983 void compute_creds(struct linux_binprm *bprm)
 984 {
 985         int unsafe;
 986
 987         if (bprm->e_uid != current->uid)
 988                 suid_keys(current);
 989         exec_keys(current);
 990
 991         task_lock(current);
 992         unsafe = unsafe_exec(current);
 993         security_bprm_apply_creds(bprm, unsafe);
 994         task_unlock(current);
 995         security_bprm_post_apply_creds(bprm);
 996 }
 997
 998 EXPORT_SYMBOL(compute_creds);
 999
1000 void remove_arg_zero(struct linux_binprm *bprm)
1001 {
1002         if (bprm->argc) {
1003                 unsigned long offset;
1004                 char * kaddr;
1005                 struct page *page;
1006
1007                 offset = bprm->p % PAGE_SIZE;
1008                 goto inside;
1009
1010                 while (bprm->p++, *(kaddr+offset++)) {
1011                         if (offset != PAGE_SIZE)
1012                                 continue;
1013                         offset = 0;
1014                         kunmap_atomic(kaddr, KM_USER0);
1015 inside:
1016                         page = bprm->page[bprm->p/PAGE_SIZE];
1017                         kaddr = kmap_atomic(page, KM_USER0);
1018                 }
1019                 kunmap_atomic(kaddr, KM_USER0);
1020                 bprm->argc--;
1021         }
1022 }
1023
1024 EXPORT_SYMBOL(remove_arg_zero);
1025
1026 /*
1027  * cycle the list of binary formats handler, until one recognizes the image
1028  */
1029 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1030 {
1031         int try,retval;
1032         struct linux_binfmt *fmt;
1033 #ifdef __alpha__
1034         /* handle /sbin/loader.. */
1035         {
1036             struct exec * eh = (struct exec *) bprm->buf;
1037
1038             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1039                 (eh->fh.f_flags & 0x3000) == 0x3000)
1040             {
1041                 struct file * file;
1042                 unsigned long loader;
1043
1044                 allow_write_access(bprm->file);
1045                 fput(bprm->file);
1046                 bprm->file = NULL;
1047
1048                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1049
1050                 file = open_exec("/sbin/loader");
1051                 retval = PTR_ERR(file);
1052                 if (IS_ERR(file))
1053                         return retval;
1054
1055                 /* Remember if the application is TASO.  */
1056                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1057
1058                 bprm->file = file;
1059                 bprm->loader = loader;
1060                 retval = prepare_binprm(bprm);
1061                 if (retval<0)
1062                         return retval;
1063                 /* should call search_binary_handler recursively here,
1064                    but it does not matter */
1065             }
1066         }
1067 #endif
1068         retval = security_bprm_check(bprm);
1069         if (retval)
1070                 return retval;
1071
1072         /* kernel module loader fixup */
1073         /* so we don't try to load run modprobe in kernel space. */
1074         set_fs(USER_DS);
1075         retval = -ENOENT;
1076         for (try=0; try<2; try++) {
1077                 read_lock(&binfmt_lock);
1078                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1079                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1080                         if (!fn)
1081                                 continue;
1082                         if (!try_module_get(fmt->module))
1083                                 continue;
1084                         read_unlock(&binfmt_lock);
1085                         retval = fn(bprm, regs);
1086                         if (retval >= 0) {
1087                                 put_binfmt(fmt);
1088                                 allow_write_access(bprm->file);
1089                                 if (bprm->file)
1090                                         fput(bprm->file);
1091                                 bprm->file = NULL;
1092                                 current->did_exec = 1;
1093                                 return retval;
1094                         }
1095                         read_lock(&binfmt_lock);
1096                         put_binfmt(fmt);
1097                         if (retval != -ENOEXEC || bprm->mm == NULL)
1098                                 break;
1099                         if (!bprm->file) {
1100                                 read_unlock(&binfmt_lock);
1101                                 return retval;
1102                         }
1103                 }
1104                 read_unlock(&binfmt_lock);
1105                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1106                         break;
1107 #ifdef CONFIG_KMOD
1108                 }else{
1109 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1110                         if (printable(bprm->buf[0]) &&
1111                             printable(bprm->buf[1]) &&
1112                             printable(bprm->buf[2]) &&
1113                             printable(bprm->buf[3]))
1114                                 break; /* -ENOEXEC */
1115                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1116 #endif
1117                 }
1118         }
1119         return retval;
1120 }
1121
1122 EXPORT_SYMBOL(search_binary_handler);
1123
1124 /*
1125  * sys_execve() executes a new program.
1126  */
1127 int do_execve(char * filename,
1128         char __user *__user *argv,
1129         char __user *__user *envp,
1130         struct pt_regs * regs)
1131 {
1132         struct linux_binprm *bprm;
1133         struct file *file;
1134         int retval;
1135         int i;
1136
1137         retval = -ENOMEM;
1138         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1139         if (!bprm)
1140                 goto out_ret;
1141         memset(bprm, 0, sizeof(*bprm));
1142
1143         file = open_exec(filename);
1144         retval = PTR_ERR(file);
1145         if (IS_ERR(file))
1146                 goto out_kfree;
1147
1148         sched_exec();
1149
1150         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1151
1152         bprm->file = file;
1153         bprm->filename = filename;
1154         bprm->interp = filename;
1155         bprm->mm = mm_alloc();
1156         retval = -ENOMEM;
1157         if (!bprm->mm)
1158                 goto out_file;
1159
1160         retval = init_new_context(current, bprm->mm);
1161         if (retval < 0)
1162                 goto out_mm;
1163
1164         bprm->argc = count(argv, bprm->p / sizeof(void *));
1165         if ((retval = bprm->argc) < 0)
1166                 goto out_mm;
1167
1168         bprm->envc = count(envp, bprm->p / sizeof(void *));
1169         if ((retval = bprm->envc) < 0)
1170                 goto out_mm;
1171
1172         retval = security_bprm_alloc(bprm);
1173         if (retval)
1174                 goto out;
1175
1176         retval = prepare_binprm(bprm);
1177         if (retval < 0)
1178                 goto out;
1179
1180         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1181         if (retval < 0)
1182                 goto out;
1183
1184         bprm->exec = bprm->p;
1185         retval = copy_strings(bprm->envc, envp, bprm);
1186         if (retval < 0)
1187                 goto out;
1188
1189         retval = copy_strings(bprm->argc, argv, bprm);
1190         if (retval < 0)
1191                 goto out;
1192
1193         retval = search_binary_handler(bprm,regs);
1194         if (retval >= 0) {
1195                 free_arg_pages(bprm);
1196
1197                 /* execve success */
1198                 security_bprm_free(bprm);
1199                 acct_update_integrals();
1200                 update_mem_hiwater();
1201                 kfree(bprm);
1202                 return retval;
1203         }
1204
1205 out:
1206         /* Something went wrong, return the inode and free the argument pages*/
1207         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1208                 struct page * page = bprm->page[i];
1209                 if (page)
1210                         __free_page(page);
1211         }
1212
1213         if (bprm->security)
1214                 security_bprm_free(bprm);
1215
1216 out_mm:
1217         if (bprm->mm)
1218                 mmdrop(bprm->mm);
1219
1220 out_file:
1221         if (bprm->file) {
1222                 allow_write_access(bprm->file);
1223                 fput(bprm->file);
1224         }
1225
1226 out_kfree:
1227         kfree(bprm);
1228
1229 out_ret:
1230         return retval;
1231 }
1232
1233 int set_binfmt(struct linux_binfmt *new)
1234 {
1235         struct linux_binfmt *old = current->binfmt;
1236
1237         if (new) {
1238                 if (!try_module_get(new->module))
1239                         return -1;
1240         }
1241         current->binfmt = new;
1242         if (old)
1243                 module_put(old->module);
1244         return 0;
1245 }
1246
1247 EXPORT_SYMBOL(set_binfmt);
1248
1249 #define CORENAME_MAX_SIZE 64
1250
1251 /* format_corename will inspect the pattern parameter, and output a
1252  * name into corename, which must have space for at least
1253  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1254  */
1255 static void format_corename(char *corename, const char *pattern, long signr)
1256 {
1257         const char *pat_ptr = pattern;
1258         char *out_ptr = corename;
1259         char *const out_end = corename + CORENAME_MAX_SIZE;
1260         int rc;
1261         int pid_in_pattern = 0;
1262
1263         /* Repeat as long as we have more pattern to process and more output
1264            space */
1265         while (*pat_ptr) {
1266                 if (*pat_ptr != '%') {
1267                         if (out_ptr == out_end)
1268                                 goto out;
1269                         *out_ptr++ = *pat_ptr++;
1270                 } else {
1271                         switch (*++pat_ptr) {
1272                         case 0:
1273                                 goto out;
1274                         /* Double percent, output one percent */
1275                         case '%':
1276                                 if (out_ptr == out_end)
1277                                         goto out;
1278                                 *out_ptr++ = '%';
1279                                 break;
1280                         /* pid */
1281                         case 'p':
1282                                 pid_in_pattern = 1;
1283                                 rc = snprintf(out_ptr, out_end - out_ptr,
1284                                               "%d", current->tgid);
1285                                 if (rc > out_end - out_ptr)
1286                                         goto out;
1287                                 out_ptr += rc;
1288                                 break;
1289                         /* uid */
1290                         case 'u':
1291                                 rc = snprintf(out_ptr, out_end - out_ptr,
1292                                               "%d", current->uid);
1293                                 if (rc > out_end - out_ptr)
1294                                         goto out;
1295                                 out_ptr += rc;
1296                                 break;
1297                         /* gid */
1298                         case 'g':
1299                                 rc = snprintf(out_ptr, out_end - out_ptr,
1300                                               "%d", current->gid);
1301                                 if (rc > out_end - out_ptr)
1302                                         goto out;
1303                                 out_ptr += rc;
1304                                 break;
1305                         /* signal that caused the coredump */
1306                         case 's':
1307                                 rc = snprintf(out_ptr, out_end - out_ptr,
1308                                               "%ld", signr);
1309                                 if (rc > out_end - out_ptr)
1310                                         goto out;
1311                                 out_ptr += rc;
1312                                 break;
1313                         /* UNIX time of coredump */
1314                         case 't': {
1315                                 struct timeval tv;
1316                                 do_gettimeofday(&tv);
1317                                 rc = snprintf(out_ptr, out_end - out_ptr,
1318                                               "%lu", tv.tv_sec);
1319                                 if (rc > out_end - out_ptr)
1320                                         goto out;
1321                                 out_ptr += rc;
1322                                 break;
1323                         }
1324                         /* hostname */
1325                         case 'h':
1326                                 down_read(&uts_sem);
1327                                 rc = snprintf(out_ptr, out_end - out_ptr,
1328                                               "%s", system_utsname.nodename);
1329                                 up_read(&uts_sem);
1330                                 if (rc > out_end - out_ptr)
1331                                         goto out;
1332                                 out_ptr += rc;
1333                                 break;
1334                         /* executable */
1335                         case 'e':
1336                                 rc = snprintf(out_ptr, out_end - out_ptr,
1337                                               "%s", current->comm);
1338                                 if (rc > out_end - out_ptr)
1339                                         goto out;
1340                                 out_ptr += rc;
1341                                 break;
1342                         default:
1343                                 break;
1344                         }
1345                         ++pat_ptr;
1346                 }
1347         }
1348         /* Backward compatibility with core_uses_pid:
1349          *
1350          * If core_pattern does not include a %p (as is the default)
1351          * and core_uses_pid is set, then .%pid will be appended to
1352          * the filename */
1353         if (!pid_in_pattern
1354             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1355                 rc = snprintf(out_ptr, out_end - out_ptr,
1356                               ".%d", current->tgid);
1357                 if (rc > out_end - out_ptr)
1358                         goto out;
1359                 out_ptr += rc;
1360         }
1361       out:
1362         *out_ptr = 0;
1363 }
1364
1365 static void zap_threads (struct mm_struct *mm)
1366 {
1367         struct task_struct *g, *p;
1368         struct task_struct *tsk = current;
1369         struct completion *vfork_done = tsk->vfork_done;
1370         int traced = 0;
1371
1372         /*
1373          * Make sure nobody is waiting for us to release the VM,
1374          * otherwise we can deadlock when we wait on each other
1375          */
1376         if (vfork_done) {
1377                 tsk->vfork_done = NULL;
1378                 complete(vfork_done);
1379         }
1380
1381         read_lock(&tasklist_lock);
1382         do_each_thread(g,p)
1383                 if (mm == p->mm && p != tsk) {
1384                         force_sig_specific(SIGKILL, p);
1385                         mm->core_waiters++;
1386                         if (unlikely(p->ptrace) &&
1387                             unlikely(p->parent->mm == mm))
1388                                 traced = 1;
1389                 }
1390         while_each_thread(g,p);
1391
1392         read_unlock(&tasklist_lock);
1393
1394         if (unlikely(traced)) {
1395                 /*
1396                  * We are zapping a thread and the thread it ptraces.
1397                  * If the tracee went into a ptrace stop for exit tracing,
1398                  * we could deadlock since the tracer is waiting for this
1399                  * coredump to finish.  Detach them so they can both die.
1400                  */
1401                 write_lock_irq(&tasklist_lock);
1402                 do_each_thread(g,p) {
1403                         if (mm == p->mm && p != tsk &&
1404                             p->ptrace && p->parent->mm == mm) {
1405                                 __ptrace_unlink(p);
1406                         }
1407                 } while_each_thread(g,p);
1408                 write_unlock_irq(&tasklist_lock);
1409         }
1410 }
1411
1412 static void coredump_wait(struct mm_struct *mm)
1413 {
1414         DECLARE_COMPLETION(startup_done);
1415
1416         mm->core_waiters++; /* let other threads block */
1417         mm->core_startup_done = &startup_done;
1418
1419         /* give other threads a chance to run: */
1420         yield();
1421
1422         zap_threads(mm);
1423         if (--mm->core_waiters) {
1424                 up_write(&mm->mmap_sem);
1425                 wait_for_completion(&startup_done);
1426         } else
1427                 up_write(&mm->mmap_sem);
1428         BUG_ON(mm->core_waiters);
1429 }
1430
1431 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1432 {
1433         char corename[CORENAME_MAX_SIZE + 1];
1434         struct mm_struct *mm = current->mm;
1435         struct linux_binfmt * binfmt;
1436         struct inode * inode;
1437         struct file * file;
1438         int retval = 0;
1439
1440         binfmt = current->binfmt;
1441         if (!binfmt || !binfmt->core_dump)
1442                 goto fail;
1443         down_write(&mm->mmap_sem);
1444         if (!mm->dumpable) {
1445                 up_write(&mm->mmap_sem);
1446                 goto fail;
1447         }
1448         mm->dumpable = 0;
1449         init_completion(&mm->core_done);
1450         spin_lock_irq(&current->sighand->siglock);
1451         current->signal->flags = SIGNAL_GROUP_EXIT;
1452         current->signal->group_exit_code = exit_code;
1453         spin_unlock_irq(&current->sighand->siglock);
1454         coredump_wait(mm);
1455
1456         /*
1457          * Clear any false indication of pending signals that might
1458          * be seen by the filesystem code called to write the core file.
1459          */
1460         current->signal->group_stop_count = 0;
1461         clear_thread_flag(TIF_SIGPENDING);
1462
1463         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1464                 goto fail_unlock;
1465
1466         /*
1467          * lock_kernel() because format_corename() is controlled by sysctl, which
1468          * uses lock_kernel()
1469          */
1470         lock_kernel();
1471         format_corename(corename, core_pattern, signr);
1472         unlock_kernel();
1473         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE, 0600);
1474         if (IS_ERR(file))
1475                 goto fail_unlock;
1476         inode = file->f_dentry->d_inode;
1477         if (inode->i_nlink > 1)
1478                 goto close_fail;        /* multiple links - don't dump */
1479         if (d_unhashed(file->f_dentry))
1480                 goto close_fail;
1481
1482         if (!S_ISREG(inode->i_mode))
1483                 goto close_fail;
1484         if (!file->f_op)
1485                 goto close_fail;
1486         if (!file->f_op->write)
1487                 goto close_fail;
1488         if (do_truncate(file->f_dentry, 0) != 0)
1489                 goto close_fail;
1490
1491         retval = binfmt->core_dump(signr, regs, file);
1492
1493         if (retval)
1494                 current->signal->group_exit_code |= 0x80;
1495 close_fail:
1496         filp_close(file, NULL);
1497 fail_unlock:
1498         complete_all(&mm->core_done);
1499 fail:
1500         return retval;
1501 }