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   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 int suid_dumpable = 0;
  62
  63 EXPORT_SYMBOL(suid_dumpable);
  64 /* The maximal length of core_pattern is also specified in sysctl.c */
  65
  66 static struct linux_binfmt *formats;
  67 static DEFINE_RWLOCK(binfmt_lock);
  68
  69 int register_binfmt(struct linux_binfmt * fmt)
  70 {
  71         struct linux_binfmt ** tmp = &formats;
  72
  73         if (!fmt)
  74                 return -EINVAL;
  75         if (fmt->next)
  76                 return -EBUSY;
  77         write_lock(&binfmt_lock);
  78         while (*tmp) {
  79                 if (fmt == *tmp) {
  80                         write_unlock(&binfmt_lock);
  81                         return -EBUSY;
  82                 }
  83                 tmp = &(*tmp)->next;
  84         }
  85         fmt->next = formats;
  86         formats = fmt;
  87         write_unlock(&binfmt_lock);
  88         return 0;
  89 }
  90
  91 EXPORT_SYMBOL(register_binfmt);
  92
  93 int unregister_binfmt(struct linux_binfmt * fmt)
  94 {
  95         struct linux_binfmt ** tmp = &formats;
  96
  97         write_lock(&binfmt_lock);
  98         while (*tmp) {
  99                 if (fmt == *tmp) {
 100                         *tmp = fmt->next;
 101                         write_unlock(&binfmt_lock);
 102                         return 0;
 103                 }
 104                 tmp = &(*tmp)->next;
 105         }
 106         write_unlock(&binfmt_lock);
 107         return -EINVAL;
 108 }
 109
 110 EXPORT_SYMBOL(unregister_binfmt);
 111
 112 static inline void put_binfmt(struct linux_binfmt * fmt)
 113 {
 114         module_put(fmt->module);
 115 }
 116
 117 /*
 118  * Note that a shared library must be both readable and executable due to
 119  * security reasons.
 120  *
 121  * Also note that we take the address to load from from the file itself.
 122  */
 123 asmlinkage long sys_uselib(const char __user * library)
 124 {
 125         struct file * file;
 126         struct nameidata nd;
 127         int error;
 128
 129         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ);
 130         if (error)
 131                 goto out;
 132
 133         error = -EINVAL;
 134         if (!S_ISREG(nd.dentry->d_inode->i_mode))
 135                 goto exit;
 136
 137         error = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC, &nd);
 138         if (error)
 139                 goto exit;
 140
 141         file = nameidata_to_filp(&nd, O_RDONLY);
 142         error = PTR_ERR(file);
 143         if (IS_ERR(file))
 144                 goto out;
 145
 146         error = -ENOEXEC;
 147         if(file->f_op) {
 148                 struct linux_binfmt * fmt;
 149
 150                 read_lock(&binfmt_lock);
 151                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 152                         if (!fmt->load_shlib)
 153                                 continue;
 154                         if (!try_module_get(fmt->module))
 155                                 continue;
 156                         read_unlock(&binfmt_lock);
 157                         error = fmt->load_shlib(file);
 158                         read_lock(&binfmt_lock);
 159                         put_binfmt(fmt);
 160                         if (error != -ENOEXEC)
 161                                 break;
 162                 }
 163                 read_unlock(&binfmt_lock);
 164         }
 165         fput(file);
 166 out:
 167         return error;
 168 exit:
 169         release_open_intent(&nd);
 170         path_release(&nd);
 171         goto out;
 172 }
 173
 174 /*
 175  * count() counts the number of strings in array ARGV.
 176  */
 177 static int count(char __user * __user * argv, int max)
 178 {
 179         int i = 0;
 180
 181         if (argv != NULL) {
 182                 for (;;) {
 183                         char __user * p;
 184
 185                         if (get_user(p, argv))
 186                                 return -EFAULT;
 187                         if (!p)
 188                                 break;
 189                         argv++;
 190                         if(++i > max)
 191                                 return -E2BIG;
 192                         cond_resched();
 193                 }
 194         }
 195         return i;
 196 }
 197
 198 /*
 199  * 'copy_strings()' copies argument/environment strings from user
 200  * memory to free pages in kernel mem. These are in a format ready
 201  * to be put directly into the top of new user memory.
 202  */
 203 static int copy_strings(int argc, char __user * __user * argv,
 204                         struct linux_binprm *bprm)
 205 {
 206         struct page *kmapped_page = NULL;
 207         char *kaddr = NULL;
 208         int ret;
 209
 210         while (argc-- > 0) {
 211                 char __user *str;
 212                 int len;
 213                 unsigned long pos;
 214
 215                 if (get_user(str, argv+argc) ||
 216                                 !(len = strnlen_user(str, bprm->p))) {
 217                         ret = -EFAULT;
 218                         goto out;
 219                 }
 220
 221                 if (bprm->p < len)  {
 222                         ret = -E2BIG;
 223                         goto out;
 224                 }
 225
 226                 bprm->p -= len;
 227                 /* XXX: add architecture specific overflow check here. */
 228                 pos = bprm->p;
 229
 230                 while (len > 0) {
 231                         int i, new, err;
 232                         int offset, bytes_to_copy;
 233                         struct page *page;
 234
 235                         offset = pos % PAGE_SIZE;
 236                         i = pos/PAGE_SIZE;
 237                         page = bprm->page[i];
 238                         new = 0;
 239                         if (!page) {
 240                                 page = alloc_page(GFP_HIGHUSER);
 241                                 bprm->page[i] = page;
 242                                 if (!page) {
 243                                         ret = -ENOMEM;
 244                                         goto out;
 245                                 }
 246                                 new = 1;
 247                         }
 248
 249                         if (page != kmapped_page) {
 250                                 if (kmapped_page)
 251                                         kunmap(kmapped_page);
 252                                 kmapped_page = page;
 253                                 kaddr = kmap(kmapped_page);
 254                         }
 255                         if (new && offset)
 256                                 memset(kaddr, 0, offset);
 257                         bytes_to_copy = PAGE_SIZE - offset;
 258                         if (bytes_to_copy > len) {
 259                                 bytes_to_copy = len;
 260                                 if (new)
 261                                         memset(kaddr+offset+len, 0,
 262                                                 PAGE_SIZE-offset-len);
 263                         }
 264                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
 265                         if (err) {
 266                                 ret = -EFAULT;
 267                                 goto out;
 268                         }
 269
 270                         pos += bytes_to_copy;
 271                         str += bytes_to_copy;
 272                         len -= bytes_to_copy;
 273                 }
 274         }
 275         ret = 0;
 276 out:
 277         if (kmapped_page)
 278                 kunmap(kmapped_page);
 279         return ret;
 280 }
 281
 282 /*
 283  * Like copy_strings, but get argv and its values from kernel memory.
 284  */
 285 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 286 {
 287         int r;
 288         mm_segment_t oldfs = get_fs();
 289         set_fs(KERNEL_DS);
 290         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 291         set_fs(oldfs);
 292         return r;
 293 }
 294
 295 EXPORT_SYMBOL(copy_strings_kernel);
 296
 297 #ifdef CONFIG_MMU
 298 /*
 299  * This routine is used to map in a page into an address space: needed by
 300  * execve() for the initial stack and environment pages.
 301  *
 302  * vma->vm_mm->mmap_sem is held for writing.
 303  */
 304 void install_arg_page(struct vm_area_struct *vma,
 305                         struct page *page, unsigned long address)
 306 {
 307         struct mm_struct *mm = vma->vm_mm;
 308         pgd_t * pgd;
 309         pud_t * pud;
 310         pmd_t * pmd;
 311         pte_t * pte;
 312         spinlock_t *ptl;
 313
 314         if (unlikely(anon_vma_prepare(vma)))
 315                 goto out;
 316
 317         flush_dcache_page(page);
 318         pgd = pgd_offset(mm, address);
 319         pud = pud_alloc(mm, pgd, address);
 320         if (!pud)
 321                 goto out;
 322         pmd = pmd_alloc(mm, pud, address);
 323         if (!pmd)
 324                 goto out;
 325         pte = pte_alloc_map_lock(mm, pmd, address, &ptl);
 326         if (!pte)
 327                 goto out;
 328         if (!pte_none(*pte)) {
 329                 pte_unmap_unlock(pte, ptl);
 330                 goto out;
 331         }
 332         inc_mm_counter(mm, anon_rss);
 333         lru_cache_add_active(page);
 334         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
 335                                         page, vma->vm_page_prot))));
 336         page_add_anon_rmap(page, vma, address);
 337         pte_unmap_unlock(pte, ptl);
 338
 339         /* no need for flush_tlb */
 340         return;
 341 out:
 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         memset(mpnt, 0, sizeof(*mpnt));
 421
 422         down_write(&mm->mmap_sem);
 423         {
 424                 mpnt->vm_mm = mm;
 425 #ifdef CONFIG_STACK_GROWSUP
 426                 mpnt->vm_start = stack_base;
 427                 mpnt->vm_end = stack_base + arg_size;
 428 #else
 429                 mpnt->vm_end = stack_top;
 430                 mpnt->vm_start = mpnt->vm_end - arg_size;
 431 #endif
 432                 /* Adjust stack execute permissions; explicitly enable
 433                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
 434                  * and leave alone (arch default) otherwise. */
 435                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 436                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
 437                 else if (executable_stack == EXSTACK_DISABLE_X)
 438                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
 439                 else
 440                         mpnt->vm_flags = VM_STACK_FLAGS;
 441                 mpnt->vm_flags |= mm->def_flags;
 442                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
 443                 if ((ret = insert_vm_struct(mm, mpnt))) {
 444                         up_write(&mm->mmap_sem);
 445                         kmem_cache_free(vm_area_cachep, mpnt);
 446                         return ret;
 447                 }
 448                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
 449         }
 450
 451         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
 452                 struct page *page = bprm->page[i];
 453                 if (page) {
 454                         bprm->page[i] = NULL;
 455                         install_arg_page(mpnt, page, stack_base);
 456                 }
 457                 stack_base += PAGE_SIZE;
 458         }
 459         up_write(&mm->mmap_sem);
 460
 461         return 0;
 462 }
 463
 464 EXPORT_SYMBOL(setup_arg_pages);
 465
 466 #define free_arg_pages(bprm) do { } while (0)
 467
 468 #else
 469
 470 static inline void free_arg_pages(struct linux_binprm *bprm)
 471 {
 472         int i;
 473
 474         for (i = 0; i < MAX_ARG_PAGES; i++) {
 475                 if (bprm->page[i])
 476                         __free_page(bprm->page[i]);
 477                 bprm->page[i] = NULL;
 478         }
 479 }
 480
 481 #endif /* CONFIG_MMU */
 482
 483 struct file *open_exec(const char *name)
 484 {
 485         struct nameidata nd;
 486         int err;
 487         struct file *file;
 488
 489         err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ);
 490         file = ERR_PTR(err);
 491
 492         if (!err) {
 493                 struct inode *inode = nd.dentry->d_inode;
 494                 file = ERR_PTR(-EACCES);
 495                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
 496                     S_ISREG(inode->i_mode)) {
 497                         int err = permission(inode, MAY_EXEC, &nd);
 498                         if (!err && !(inode->i_mode & 0111))
 499                                 err = -EACCES;
 500                         file = ERR_PTR(err);
 501                         if (!err) {
 502                                 file = nameidata_to_filp(&nd, O_RDONLY);
 503                                 if (!IS_ERR(file)) {
 504                                         err = deny_write_access(file);
 505                                         if (err) {
 506                                                 fput(file);
 507                                                 file = ERR_PTR(err);
 508                                         }
 509                                 }
 510 out:
 511                                 return file;
 512                         }
 513                 }
 514                 release_open_intent(&nd);
 515                 path_release(&nd);
 516         }
 517         goto out;
 518 }
 519
 520 EXPORT_SYMBOL(open_exec);
 521
 522 int kernel_read(struct file *file, unsigned long offset,
 523         char *addr, unsigned long count)
 524 {
 525         mm_segment_t old_fs;
 526         loff_t pos = offset;
 527         int result;
 528
 529         old_fs = get_fs();
 530         set_fs(get_ds());
 531         /* The cast to a user pointer is valid due to the set_fs() */
 532         result = vfs_read(file, (void __user *)addr, count, &pos);
 533         set_fs(old_fs);
 534         return result;
 535 }
 536
 537 EXPORT_SYMBOL(kernel_read);
 538
 539 static int exec_mmap(struct mm_struct *mm)
 540 {
 541         struct task_struct *tsk;
 542         struct mm_struct * old_mm, *active_mm;
 543
 544         /* Notify parent that we're no longer interested in the old VM */
 545         tsk = current;
 546         old_mm = current->mm;
 547         mm_release(tsk, old_mm);
 548
 549         if (old_mm) {
 550                 /*
 551                  * Make sure that if there is a core dump in progress
 552                  * for the old mm, we get out and die instead of going
 553                  * through with the exec.  We must hold mmap_sem around
 554                  * checking core_waiters and changing tsk->mm.  The
 555                  * core-inducing thread will increment core_waiters for
 556                  * each thread whose ->mm == old_mm.
 557                  */
 558                 down_read(&old_mm->mmap_sem);
 559                 if (unlikely(old_mm->core_waiters)) {
 560                         up_read(&old_mm->mmap_sem);
 561                         return -EINTR;
 562                 }
 563         }
 564         task_lock(tsk);
 565         active_mm = tsk->active_mm;
 566         tsk->mm = mm;
 567         tsk->active_mm = mm;
 568         activate_mm(active_mm, mm);
 569         task_unlock(tsk);
 570         arch_pick_mmap_layout(mm);
 571         if (old_mm) {
 572                 up_read(&old_mm->mmap_sem);
 573                 if (active_mm != old_mm) BUG();
 574                 mmput(old_mm);
 575                 return 0;
 576         }
 577         mmdrop(active_mm);
 578         return 0;
 579 }
 580
 581 /*
 582  * This function makes sure the current process has its own signal table,
 583  * so that flush_signal_handlers can later reset the handlers without
 584  * disturbing other processes.  (Other processes might share the signal
 585  * table via the CLONE_SIGHAND option to clone().)
 586  */
 587 static inline int de_thread(struct task_struct *tsk)
 588 {
 589         struct signal_struct *sig = tsk->signal;
 590         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
 591         spinlock_t *lock = &oldsighand->siglock;
 592         int count;
 593
 594         /*
 595          * If we don't share sighandlers, then we aren't sharing anything
 596          * and we can just re-use it all.
 597          */
 598         if (atomic_read(&oldsighand->count) <= 1) {
 599                 BUG_ON(atomic_read(&sig->count) != 1);
 600                 exit_itimers(sig);
 601                 return 0;
 602         }
 603
 604         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 605         if (!newsighand)
 606                 return -ENOMEM;
 607
 608         if (thread_group_empty(current))
 609                 goto no_thread_group;
 610
 611         /*
 612          * Kill all other threads in the thread group.
 613          * We must hold tasklist_lock to call zap_other_threads.
 614          */
 615         read_lock(&tasklist_lock);
 616         spin_lock_irq(lock);
 617         if (sig->flags & SIGNAL_GROUP_EXIT) {
 618                 /*
 619                  * Another group action in progress, just
 620                  * return so that the signal is processed.
 621                  */
 622                 spin_unlock_irq(lock);
 623                 read_unlock(&tasklist_lock);
 624                 kmem_cache_free(sighand_cachep, newsighand);
 625                 return -EAGAIN;
 626         }
 627         zap_other_threads(current);
 628         read_unlock(&tasklist_lock);
 629
 630         /*
 631          * Account for the thread group leader hanging around:
 632          */
 633         count = 1;
 634         if (!thread_group_leader(current)) {
 635                 count = 2;
 636                 /*
 637                  * The SIGALRM timer survives the exec, but needs to point
 638                  * at us as the new group leader now.  We have a race with
 639                  * a timer firing now getting the old leader, so we need to
 640                  * synchronize with any firing (by calling del_timer_sync)
 641                  * before we can safely let the old group leader die.
 642                  */
 643                 sig->real_timer.data = (unsigned long)current;
 644                 if (del_timer_sync(&sig->real_timer))
 645                         add_timer(&sig->real_timer);
 646         }
 647         while (atomic_read(&sig->count) > count) {
 648                 sig->group_exit_task = current;
 649                 sig->notify_count = count;
 650                 __set_current_state(TASK_UNINTERRUPTIBLE);
 651                 spin_unlock_irq(lock);
 652                 schedule();
 653                 spin_lock_irq(lock);
 654         }
 655         sig->group_exit_task = NULL;
 656         sig->notify_count = 0;
 657         sig->real_timer.data = (unsigned long)current;
 658         spin_unlock_irq(lock);
 659
 660         /*
 661          * At this point all other threads have exited, all we have to
 662          * do is to wait for the thread group leader to become inactive,
 663          * and to assume its PID:
 664          */
 665         if (!thread_group_leader(current)) {
 666                 struct task_struct *leader = current->group_leader, *parent;
 667                 struct dentry *proc_dentry1, *proc_dentry2;
 668                 unsigned long exit_state, ptrace;
 669
 670                 /*
 671                  * Wait for the thread group leader to be a zombie.
 672                  * It should already be zombie at this point, most
 673                  * of the time.
 674                  */
 675                 while (leader->exit_state != EXIT_ZOMBIE)
 676                         yield();
 677
 678                 spin_lock(&leader->proc_lock);
 679                 spin_lock(&current->proc_lock);
 680                 proc_dentry1 = proc_pid_unhash(current);
 681                 proc_dentry2 = proc_pid_unhash(leader);
 682                 write_lock_irq(&tasklist_lock);
 683
 684                 BUG_ON(leader->tgid != current->tgid);
 685                 BUG_ON(current->pid == current->tgid);
 686                 /*
 687                  * An exec() starts a new thread group with the
 688                  * TGID of the previous thread group. Rehash the
 689                  * two threads with a switched PID, and release
 690                  * the former thread group leader:
 691                  */
 692                 ptrace = leader->ptrace;
 693                 parent = leader->parent;
 694                 if (unlikely(ptrace) && unlikely(parent == current)) {
 695                         /*
 696                          * Joker was ptracing his own group leader,
 697                          * and now he wants to be his own parent!
 698                          * We can't have that.
 699                          */
 700                         ptrace = 0;
 701                 }
 702
 703                 ptrace_unlink(current);
 704                 ptrace_unlink(leader);
 705                 remove_parent(current);
 706                 remove_parent(leader);
 707
 708                 switch_exec_pids(leader, current);
 709
 710                 current->parent = current->real_parent = leader->real_parent;
 711                 leader->parent = leader->real_parent = child_reaper;
 712                 current->group_leader = current;
 713                 leader->group_leader = leader;
 714
 715                 add_parent(current, current->parent);
 716                 add_parent(leader, leader->parent);
 717                 if (ptrace) {
 718                         current->ptrace = ptrace;
 719                         __ptrace_link(current, parent);
 720                 }
 721
 722                 list_del(&current->tasks);
 723                 list_add_tail(&current->tasks, &init_task.tasks);
 724                 current->exit_signal = SIGCHLD;
 725                 exit_state = leader->exit_state;
 726
 727                 write_unlock_irq(&tasklist_lock);
 728                 spin_unlock(&leader->proc_lock);
 729                 spin_unlock(&current->proc_lock);
 730                 proc_pid_flush(proc_dentry1);
 731                 proc_pid_flush(proc_dentry2);
 732
 733                 BUG_ON(exit_state != EXIT_ZOMBIE);
 734                 release_task(leader);
 735         }
 736
 737         /*
 738          * There may be one thread left which is just exiting,
 739          * but it's safe to stop telling the group 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         BUG_ON(!thread_group_leader(current));
 779         return 0;
 780 }
 781
 782 /*
 783  * These functions flushes out all traces of the currently running executable
 784  * so that a new one can be started
 785  */
 786
 787 static inline void flush_old_files(struct files_struct * files)
 788 {
 789         long j = -1;
 790         struct fdtable *fdt;
 791
 792         spin_lock(&files->file_lock);
 793         for (;;) {
 794                 unsigned long set, i;
 795
 796                 j++;
 797                 i = j * __NFDBITS;
 798                 fdt = files_fdtable(files);
 799                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
 800                         break;
 801                 set = fdt->close_on_exec->fds_bits[j];
 802                 if (!set)
 803                         continue;
 804                 fdt->close_on_exec->fds_bits[j] = 0;
 805                 spin_unlock(&files->file_lock);
 806                 for ( ; set ; i++,set >>= 1) {
 807                         if (set & 1) {
 808                                 sys_close(i);
 809                         }
 810                 }
 811                 spin_lock(&files->file_lock);
 812
 813         }
 814         spin_unlock(&files->file_lock);
 815 }
 816
 817 void get_task_comm(char *buf, struct task_struct *tsk)
 818 {
 819         /* buf must be at least sizeof(tsk->comm) in size */
 820         task_lock(tsk);
 821         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 822         task_unlock(tsk);
 823 }
 824
 825 void set_task_comm(struct task_struct *tsk, char *buf)
 826 {
 827         task_lock(tsk);
 828         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 829         task_unlock(tsk);
 830 }
 831
 832 int flush_old_exec(struct linux_binprm * bprm)
 833 {
 834         char * name;
 835         int i, ch, retval;
 836         struct files_struct *files;
 837         char tcomm[sizeof(current->comm)];
 838
 839         /*
 840          * Make sure we have a private signal table and that
 841          * we are unassociated from the previous thread group.
 842          */
 843         retval = de_thread(current);
 844         if (retval)
 845                 goto out;
 846
 847         /*
 848          * Make sure we have private file handles. Ask the
 849          * fork helper to do the work for us and the exit
 850          * helper to do the cleanup of the old one.
 851          */
 852         files = current->files;         /* refcounted so safe to hold */
 853         retval = unshare_files();
 854         if (retval)
 855                 goto out;
 856         /*
 857          * Release all of the old mmap stuff
 858          */
 859         retval = exec_mmap(bprm->mm);
 860         if (retval)
 861                 goto mmap_failed;
 862
 863         bprm->mm = NULL;                /* We're using it now */
 864
 865         /* This is the point of no return */
 866         steal_locks(files);
 867         put_files_struct(files);
 868
 869         current->sas_ss_sp = current->sas_ss_size = 0;
 870
 871         if (current->euid == current->uid && current->egid == current->gid)
 872                 current->mm->dumpable = 1;
 873         else
 874                 current->mm->dumpable = suid_dumpable;
 875
 876         name = bprm->filename;
 877
 878         /* Copies the binary name from after last slash */
 879         for (i=0; (ch = *(name++)) != '\0';) {
 880                 if (ch == '/')
 881                         i = 0; /* overwrite what we wrote */
 882                 else
 883                         if (i < (sizeof(tcomm) - 1))
 884                                 tcomm[i++] = ch;
 885         }
 886         tcomm[i] = '\0';
 887         set_task_comm(current, tcomm);
 888
 889         current->flags &= ~PF_RANDOMIZE;
 890         flush_thread();
 891
 892         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
 893             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
 894             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
 895                 suid_keys(current);
 896                 current->mm->dumpable = suid_dumpable;
 897         }
 898
 899         /* An exec changes our domain. We are no longer part of the thread
 900            group */
 901
 902         current->self_exec_id++;
 903
 904         flush_signal_handlers(current, 0);
 905         flush_old_files(current->files);
 906
 907         return 0;
 908
 909 mmap_failed:
 910         put_files_struct(current->files);
 911         current->files = files;
 912 out:
 913         return retval;
 914 }
 915
 916 EXPORT_SYMBOL(flush_old_exec);
 917
 918 /*
 919  * Fill the binprm structure from the inode.
 920  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 921  */
 922 int prepare_binprm(struct linux_binprm *bprm)
 923 {
 924         int mode;
 925         struct inode * inode = bprm->file->f_dentry->d_inode;
 926         int retval;
 927
 928         mode = inode->i_mode;
 929         /*
 930          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
 931          * generic_permission lets a non-executable through
 932          */
 933         if (!(mode & 0111))     /* with at least _one_ execute bit set */
 934                 return -EACCES;
 935         if (bprm->file->f_op == NULL)
 936                 return -EACCES;
 937
 938         bprm->e_uid = current->euid;
 939         bprm->e_gid = current->egid;
 940
 941         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
 942                 /* Set-uid? */
 943                 if (mode & S_ISUID) {
 944                         current->personality &= ~PER_CLEAR_ON_SETID;
 945                         bprm->e_uid = inode->i_uid;
 946                 }
 947
 948                 /* Set-gid? */
 949                 /*
 950                  * If setgid is set but no group execute bit then this
 951                  * is a candidate for mandatory locking, not a setgid
 952                  * executable.
 953                  */
 954                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 955                         current->personality &= ~PER_CLEAR_ON_SETID;
 956                         bprm->e_gid = inode->i_gid;
 957                 }
 958         }
 959
 960         /* fill in binprm security blob */
 961         retval = security_bprm_set(bprm);
 962         if (retval)
 963                 return retval;
 964
 965         memset(bprm->buf,0,BINPRM_BUF_SIZE);
 966         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
 967 }
 968
 969 EXPORT_SYMBOL(prepare_binprm);
 970
 971 static inline int unsafe_exec(struct task_struct *p)
 972 {
 973         int unsafe = 0;
 974         if (p->ptrace & PT_PTRACED) {
 975                 if (p->ptrace & PT_PTRACE_CAP)
 976                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
 977                 else
 978                         unsafe |= LSM_UNSAFE_PTRACE;
 979         }
 980         if (atomic_read(&p->fs->count) > 1 ||
 981             atomic_read(&p->files->count) > 1 ||
 982             atomic_read(&p->sighand->count) > 1)
 983                 unsafe |= LSM_UNSAFE_SHARE;
 984
 985         return unsafe;
 986 }
 987
 988 void compute_creds(struct linux_binprm *bprm)
 989 {
 990         int unsafe;
 991
 992         if (bprm->e_uid != current->uid)
 993                 suid_keys(current);
 994         exec_keys(current);
 995
 996         task_lock(current);
 997         unsafe = unsafe_exec(current);
 998         security_bprm_apply_creds(bprm, unsafe);
 999         task_unlock(current);
1000         security_bprm_post_apply_creds(bprm);
1001 }
1002
1003 EXPORT_SYMBOL(compute_creds);
1004
1005 void remove_arg_zero(struct linux_binprm *bprm)
1006 {
1007         if (bprm->argc) {
1008                 unsigned long offset;
1009                 char * kaddr;
1010                 struct page *page;
1011
1012                 offset = bprm->p % PAGE_SIZE;
1013                 goto inside;
1014
1015                 while (bprm->p++, *(kaddr+offset++)) {
1016                         if (offset != PAGE_SIZE)
1017                                 continue;
1018                         offset = 0;
1019                         kunmap_atomic(kaddr, KM_USER0);
1020 inside:
1021                         page = bprm->page[bprm->p/PAGE_SIZE];
1022                         kaddr = kmap_atomic(page, KM_USER0);
1023                 }
1024                 kunmap_atomic(kaddr, KM_USER0);
1025                 bprm->argc--;
1026         }
1027 }
1028
1029 EXPORT_SYMBOL(remove_arg_zero);
1030
1031 /*
1032  * cycle the list of binary formats handler, until one recognizes the image
1033  */
1034 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1035 {
1036         int try,retval;
1037         struct linux_binfmt *fmt;
1038 #ifdef __alpha__
1039         /* handle /sbin/loader.. */
1040         {
1041             struct exec * eh = (struct exec *) bprm->buf;
1042
1043             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1044                 (eh->fh.f_flags & 0x3000) == 0x3000)
1045             {
1046                 struct file * file;
1047                 unsigned long loader;
1048
1049                 allow_write_access(bprm->file);
1050                 fput(bprm->file);
1051                 bprm->file = NULL;
1052
1053                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1054
1055                 file = open_exec("/sbin/loader");
1056                 retval = PTR_ERR(file);
1057                 if (IS_ERR(file))
1058                         return retval;
1059
1060                 /* Remember if the application is TASO.  */
1061                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1062
1063                 bprm->file = file;
1064                 bprm->loader = loader;
1065                 retval = prepare_binprm(bprm);
1066                 if (retval<0)
1067                         return retval;
1068                 /* should call search_binary_handler recursively here,
1069                    but it does not matter */
1070             }
1071         }
1072 #endif
1073         retval = security_bprm_check(bprm);
1074         if (retval)
1075                 return retval;
1076
1077         /* kernel module loader fixup */
1078         /* so we don't try to load run modprobe in kernel space. */
1079         set_fs(USER_DS);
1080         retval = -ENOENT;
1081         for (try=0; try<2; try++) {
1082                 read_lock(&binfmt_lock);
1083                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1084                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1085                         if (!fn)
1086                                 continue;
1087                         if (!try_module_get(fmt->module))
1088                                 continue;
1089                         read_unlock(&binfmt_lock);
1090                         retval = fn(bprm, regs);
1091                         if (retval >= 0) {
1092                                 put_binfmt(fmt);
1093                                 allow_write_access(bprm->file);
1094                                 if (bprm->file)
1095                                         fput(bprm->file);
1096                                 bprm->file = NULL;
1097                                 current->did_exec = 1;
1098                                 return retval;
1099                         }
1100                         read_lock(&binfmt_lock);
1101                         put_binfmt(fmt);
1102                         if (retval != -ENOEXEC || bprm->mm == NULL)
1103                                 break;
1104                         if (!bprm->file) {
1105                                 read_unlock(&binfmt_lock);
1106                                 return retval;
1107                         }
1108                 }
1109                 read_unlock(&binfmt_lock);
1110                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1111                         break;
1112 #ifdef CONFIG_KMOD
1113                 }else{
1114 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1115                         if (printable(bprm->buf[0]) &&
1116                             printable(bprm->buf[1]) &&
1117                             printable(bprm->buf[2]) &&
1118                             printable(bprm->buf[3]))
1119                                 break; /* -ENOEXEC */
1120                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1121 #endif
1122                 }
1123         }
1124         return retval;
1125 }
1126
1127 EXPORT_SYMBOL(search_binary_handler);
1128
1129 /*
1130  * sys_execve() executes a new program.
1131  */
1132 int do_execve(char * filename,
1133         char __user *__user *argv,
1134         char __user *__user *envp,
1135         struct pt_regs * regs)
1136 {
1137         struct linux_binprm *bprm;
1138         struct file *file;
1139         int retval;
1140         int i;
1141
1142         retval = -ENOMEM;
1143         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1144         if (!bprm)
1145                 goto out_ret;
1146         memset(bprm, 0, sizeof(*bprm));
1147
1148         file = open_exec(filename);
1149         retval = PTR_ERR(file);
1150         if (IS_ERR(file))
1151                 goto out_kfree;
1152
1153         sched_exec();
1154
1155         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1156
1157         bprm->file = file;
1158         bprm->filename = filename;
1159         bprm->interp = filename;
1160         bprm->mm = mm_alloc();
1161         retval = -ENOMEM;
1162         if (!bprm->mm)
1163                 goto out_file;
1164
1165         retval = init_new_context(current, bprm->mm);
1166         if (retval < 0)
1167                 goto out_mm;
1168
1169         bprm->argc = count(argv, bprm->p / sizeof(void *));
1170         if ((retval = bprm->argc) < 0)
1171                 goto out_mm;
1172
1173         bprm->envc = count(envp, bprm->p / sizeof(void *));
1174         if ((retval = bprm->envc) < 0)
1175                 goto out_mm;
1176
1177         retval = security_bprm_alloc(bprm);
1178         if (retval)
1179                 goto out;
1180
1181         retval = prepare_binprm(bprm);
1182         if (retval < 0)
1183                 goto out;
1184
1185         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1186         if (retval < 0)
1187                 goto out;
1188
1189         bprm->exec = bprm->p;
1190         retval = copy_strings(bprm->envc, envp, bprm);
1191         if (retval < 0)
1192                 goto out;
1193
1194         retval = copy_strings(bprm->argc, argv, bprm);
1195         if (retval < 0)
1196                 goto out;
1197
1198         retval = search_binary_handler(bprm,regs);
1199         if (retval >= 0) {
1200                 free_arg_pages(bprm);
1201
1202                 /* execve success */
1203                 security_bprm_free(bprm);
1204                 acct_update_integrals(current);
1205                 kfree(bprm);
1206                 return retval;
1207         }
1208
1209 out:
1210         /* Something went wrong, return the inode and free the argument pages*/
1211         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1212                 struct page * page = bprm->page[i];
1213                 if (page)
1214                         __free_page(page);
1215         }
1216
1217         if (bprm->security)
1218                 security_bprm_free(bprm);
1219
1220 out_mm:
1221         if (bprm->mm)
1222                 mmdrop(bprm->mm);
1223
1224 out_file:
1225         if (bprm->file) {
1226                 allow_write_access(bprm->file);
1227                 fput(bprm->file);
1228         }
1229
1230 out_kfree:
1231         kfree(bprm);
1232
1233 out_ret:
1234         return retval;
1235 }
1236
1237 int set_binfmt(struct linux_binfmt *new)
1238 {
1239         struct linux_binfmt *old = current->binfmt;
1240
1241         if (new) {
1242                 if (!try_module_get(new->module))
1243                         return -1;
1244         }
1245         current->binfmt = new;
1246         if (old)
1247                 module_put(old->module);
1248         return 0;
1249 }
1250
1251 EXPORT_SYMBOL(set_binfmt);
1252
1253 #define CORENAME_MAX_SIZE 64
1254
1255 /* format_corename will inspect the pattern parameter, and output a
1256  * name into corename, which must have space for at least
1257  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1258  */
1259 static void format_corename(char *corename, const char *pattern, long signr)
1260 {
1261         const char *pat_ptr = pattern;
1262         char *out_ptr = corename;
1263         char *const out_end = corename + CORENAME_MAX_SIZE;
1264         int rc;
1265         int pid_in_pattern = 0;
1266
1267         /* Repeat as long as we have more pattern to process and more output
1268            space */
1269         while (*pat_ptr) {
1270                 if (*pat_ptr != '%') {
1271                         if (out_ptr == out_end)
1272                                 goto out;
1273                         *out_ptr++ = *pat_ptr++;
1274                 } else {
1275                         switch (*++pat_ptr) {
1276                         case 0:
1277                                 goto out;
1278                         /* Double percent, output one percent */
1279                         case '%':
1280                                 if (out_ptr == out_end)
1281                                         goto out;
1282                                 *out_ptr++ = '%';
1283                                 break;
1284                         /* pid */
1285                         case 'p':
1286                                 pid_in_pattern = 1;
1287                                 rc = snprintf(out_ptr, out_end - out_ptr,
1288                                               "%d", current->tgid);
1289                                 if (rc > out_end - out_ptr)
1290                                         goto out;
1291                                 out_ptr += rc;
1292                                 break;
1293                         /* uid */
1294                         case 'u':
1295                                 rc = snprintf(out_ptr, out_end - out_ptr,
1296                                               "%d", current->uid);
1297                                 if (rc > out_end - out_ptr)
1298                                         goto out;
1299                                 out_ptr += rc;
1300                                 break;
1301                         /* gid */
1302                         case 'g':
1303                                 rc = snprintf(out_ptr, out_end - out_ptr,
1304                                               "%d", current->gid);
1305                                 if (rc > out_end - out_ptr)
1306                                         goto out;
1307                                 out_ptr += rc;
1308                                 break;
1309                         /* signal that caused the coredump */
1310                         case 's':
1311                                 rc = snprintf(out_ptr, out_end - out_ptr,
1312                                               "%ld", signr);
1313                                 if (rc > out_end - out_ptr)
1314                                         goto out;
1315                                 out_ptr += rc;
1316                                 break;
1317                         /* UNIX time of coredump */
1318                         case 't': {
1319                                 struct timeval tv;
1320                                 do_gettimeofday(&tv);
1321                                 rc = snprintf(out_ptr, out_end - out_ptr,
1322                                               "%lu", tv.tv_sec);
1323                                 if (rc > out_end - out_ptr)
1324                                         goto out;
1325                                 out_ptr += rc;
1326                                 break;
1327                         }
1328                         /* hostname */
1329                         case 'h':
1330                                 down_read(&uts_sem);
1331                                 rc = snprintf(out_ptr, out_end - out_ptr,
1332                                               "%s", system_utsname.nodename);
1333                                 up_read(&uts_sem);
1334                                 if (rc > out_end - out_ptr)
1335                                         goto out;
1336                                 out_ptr += rc;
1337                                 break;
1338                         /* executable */
1339                         case 'e':
1340                                 rc = snprintf(out_ptr, out_end - out_ptr,
1341                                               "%s", current->comm);
1342                                 if (rc > out_end - out_ptr)
1343                                         goto out;
1344                                 out_ptr += rc;
1345                                 break;
1346                         default:
1347                                 break;
1348                         }
1349                         ++pat_ptr;
1350                 }
1351         }
1352         /* Backward compatibility with core_uses_pid:
1353          *
1354          * If core_pattern does not include a %p (as is the default)
1355          * and core_uses_pid is set, then .%pid will be appended to
1356          * the filename */
1357         if (!pid_in_pattern
1358             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1359                 rc = snprintf(out_ptr, out_end - out_ptr,
1360                               ".%d", current->tgid);
1361                 if (rc > out_end - out_ptr)
1362                         goto out;
1363                 out_ptr += rc;
1364         }
1365       out:
1366         *out_ptr = 0;
1367 }
1368
1369 static void zap_threads (struct mm_struct *mm)
1370 {
1371         struct task_struct *g, *p;
1372         struct task_struct *tsk = current;
1373         struct completion *vfork_done = tsk->vfork_done;
1374         int traced = 0;
1375
1376         /*
1377          * Make sure nobody is waiting for us to release the VM,
1378          * otherwise we can deadlock when we wait on each other
1379          */
1380         if (vfork_done) {
1381                 tsk->vfork_done = NULL;
1382                 complete(vfork_done);
1383         }
1384
1385         read_lock(&tasklist_lock);
1386         do_each_thread(g,p)
1387                 if (mm == p->mm && p != tsk) {
1388                         force_sig_specific(SIGKILL, p);
1389                         mm->core_waiters++;
1390                         if (unlikely(p->ptrace) &&
1391                             unlikely(p->parent->mm == mm))
1392                                 traced = 1;
1393                 }
1394         while_each_thread(g,p);
1395
1396         read_unlock(&tasklist_lock);
1397
1398         if (unlikely(traced)) {
1399                 /*
1400                  * We are zapping a thread and the thread it ptraces.
1401                  * If the tracee went into a ptrace stop for exit tracing,
1402                  * we could deadlock since the tracer is waiting for this
1403                  * coredump to finish.  Detach them so they can both die.
1404                  */
1405                 write_lock_irq(&tasklist_lock);
1406                 do_each_thread(g,p) {
1407                         if (mm == p->mm && p != tsk &&
1408                             p->ptrace && p->parent->mm == mm) {
1409                                 __ptrace_unlink(p);
1410                         }
1411                 } while_each_thread(g,p);
1412                 write_unlock_irq(&tasklist_lock);
1413         }
1414 }
1415
1416 static void coredump_wait(struct mm_struct *mm)
1417 {
1418         DECLARE_COMPLETION(startup_done);
1419
1420         mm->core_waiters++; /* let other threads block */
1421         mm->core_startup_done = &startup_done;
1422
1423         /* give other threads a chance to run: */
1424         yield();
1425
1426         zap_threads(mm);
1427         if (--mm->core_waiters) {
1428                 up_write(&mm->mmap_sem);
1429                 wait_for_completion(&startup_done);
1430         } else
1431                 up_write(&mm->mmap_sem);
1432         BUG_ON(mm->core_waiters);
1433 }
1434
1435 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1436 {
1437         char corename[CORENAME_MAX_SIZE + 1];
1438         struct mm_struct *mm = current->mm;
1439         struct linux_binfmt * binfmt;
1440         struct inode * inode;
1441         struct file * file;
1442         int retval = 0;
1443         int fsuid = current->fsuid;
1444         int flag = 0;
1445
1446         binfmt = current->binfmt;
1447         if (!binfmt || !binfmt->core_dump)
1448                 goto fail;
1449         down_write(&mm->mmap_sem);
1450         if (!mm->dumpable) {
1451                 up_write(&mm->mmap_sem);
1452                 goto fail;
1453         }
1454
1455         /*
1456          *      We cannot trust fsuid as being the "true" uid of the
1457          *      process nor do we know its entire history. We only know it
1458          *      was tainted so we dump it as root in mode 2.
1459          */
1460         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1461                 flag = O_EXCL;          /* Stop rewrite attacks */
1462                 current->fsuid = 0;     /* Dump root private */
1463         }
1464         mm->dumpable = 0;
1465         init_completion(&mm->core_done);
1466         spin_lock_irq(&current->sighand->siglock);
1467         current->signal->flags = SIGNAL_GROUP_EXIT;
1468         current->signal->group_exit_code = exit_code;
1469         spin_unlock_irq(&current->sighand->siglock);
1470         coredump_wait(mm);
1471
1472         /*
1473          * Clear any false indication of pending signals that might
1474          * be seen by the filesystem code called to write the core file.
1475          */
1476         current->signal->group_stop_count = 0;
1477         clear_thread_flag(TIF_SIGPENDING);
1478
1479         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1480                 goto fail_unlock;
1481
1482         /*
1483          * lock_kernel() because format_corename() is controlled by sysctl, which
1484          * uses lock_kernel()
1485          */
1486         lock_kernel();
1487         format_corename(corename, core_pattern, signr);
1488         unlock_kernel();
1489         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1490         if (IS_ERR(file))
1491                 goto fail_unlock;
1492         inode = file->f_dentry->d_inode;
1493         if (inode->i_nlink > 1)
1494                 goto close_fail;        /* multiple links - don't dump */
1495         if (d_unhashed(file->f_dentry))
1496                 goto close_fail;
1497
1498         if (!S_ISREG(inode->i_mode))
1499                 goto close_fail;
1500         if (!file->f_op)
1501                 goto close_fail;
1502         if (!file->f_op->write)
1503                 goto close_fail;
1504         if (do_truncate(file->f_dentry, 0) != 0)
1505                 goto close_fail;
1506
1507         retval = binfmt->core_dump(signr, regs, file);
1508
1509         if (retval)
1510                 current->signal->group_exit_code |= 0x80;
1511 close_fail:
1512         filp_close(file, NULL);
1513 fail_unlock:
1514         current->fsuid = fsuid;
1515         complete_all(&mm->core_done);
1516 fail:
1517         return retval;
1518 }