fs/exec.c

   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/slab.h>
  27 #include <linux/file.h>
  28 #include <linux/mman.h>
  29 #include <linux/a.out.h>
  30 #include <linux/stat.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/smp_lock.h>
  33 #include <linux/init.h>
  34 #include <linux/pagemap.h>
  35 #include <linux/highmem.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/key.h>
  38 #include <linux/personality.h>
  39 #include <linux/binfmts.h>
  40 #include <linux/swap.h>
  41 #include <linux/utsname.h>
  42 #include <linux/module.h>
  43 #include <linux/namei.h>
  44 #include <linux/proc_fs.h>
  45 #include <linux/ptrace.h>
  46 #include <linux/mount.h>
  47 #include <linux/security.h>
  48 #include <linux/syscalls.h>
  49 #include <linux/rmap.h>
  50 #include <linux/acct.h>
  51
  52 #include <asm/uaccess.h>
  53 #include <asm/mmu_context.h>
  54
  55 #ifdef CONFIG_KMOD
  56 #include <linux/kmod.h>
  57 #endif
  58
  59 int core_uses_pid;
  60 char core_pattern[65] = "core";
  61 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         nd.intent.open.flags = FMODE_READ;
 130         error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
 131         if (error)
 132                 goto out;
 133
 134         error = -EINVAL;
 135         if (!S_ISREG(nd.dentry->d_inode->i_mode))
 136                 goto exit;
 137
 138         error = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC, &nd);
 139         if (error)
 140                 goto exit;
 141
 142         file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
 143         error = PTR_ERR(file);
 144         if (IS_ERR(file))
 145                 goto out;
 146
 147         error = -ENOEXEC;
 148         if(file->f_op) {
 149                 struct linux_binfmt * fmt;
 150
 151                 read_lock(&binfmt_lock);
 152                 for (fmt = formats ; fmt ; fmt = fmt->next) {
 153                         if (!fmt->load_shlib)
 154                                 continue;
 155                         if (!try_module_get(fmt->module))
 156                                 continue;
 157                         read_unlock(&binfmt_lock);
 158                         error = fmt->load_shlib(file);
 159                         read_lock(&binfmt_lock);
 160                         put_binfmt(fmt);
 161                         if (error != -ENOEXEC)
 162                                 break;
 163                 }
 164                 read_unlock(&binfmt_lock);
 165         }
 166         fput(file);
 167 out:
 168         return error;
 169 exit:
 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
 313         if (unlikely(anon_vma_prepare(vma)))
 314                 goto out_sig;
 315
 316         flush_dcache_page(page);
 317         pgd = pgd_offset(mm, address);
 318
 319         spin_lock(&mm->page_table_lock);
 320         pud = pud_alloc(mm, pgd, address);
 321         if (!pud)
 322                 goto out;
 323         pmd = pmd_alloc(mm, pud, address);
 324         if (!pmd)
 325                 goto out;
 326         pte = pte_alloc_map(mm, pmd, address);
 327         if (!pte)
 328                 goto out;
 329         if (!pte_none(*pte)) {
 330                 pte_unmap(pte);
 331                 goto out;
 332         }
 333         inc_mm_counter(mm, rss);
 334         lru_cache_add_active(page);
 335         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
 336                                         page, vma->vm_page_prot))));
 337         page_add_anon_rmap(page, vma, address);
 338         pte_unmap(pte);
 339         spin_unlock(&mm->page_table_lock);
 340
 341         /* no need for flush_tlb */
 342         return;
 343 out:
 344         spin_unlock(&mm->page_table_lock);
 345 out_sig:
 346         __free_page(page);
 347         force_sig(SIGKILL, current);
 348 }
 349
 350 #define EXTRA_STACK_VM_PAGES    20      /* random */
 351
 352 int setup_arg_pages(struct linux_binprm *bprm,
 353                     unsigned long stack_top,
 354                     int executable_stack)
 355 {
 356         unsigned long stack_base;
 357         struct vm_area_struct *mpnt;
 358         struct mm_struct *mm = current->mm;
 359         int i, ret;
 360         long arg_size;
 361
 362 #ifdef CONFIG_STACK_GROWSUP
 363         /* Move the argument and environment strings to the bottom of the
 364          * stack space.
 365          */
 366         int offset, j;
 367         char *to, *from;
 368
 369         /* Start by shifting all the pages down */
 370         i = 0;
 371         for (j = 0; j < MAX_ARG_PAGES; j++) {
 372                 struct page *page = bprm->page[j];
 373                 if (!page)
 374                         continue;
 375                 bprm->page[i++] = page;
 376         }
 377
 378         /* Now move them within their pages */
 379         offset = bprm->p % PAGE_SIZE;
 380         to = kmap(bprm->page[0]);
 381         for (j = 1; j < i; j++) {
 382                 memmove(to, to + offset, PAGE_SIZE - offset);
 383                 from = kmap(bprm->page[j]);
 384                 memcpy(to + PAGE_SIZE - offset, from, offset);
 385                 kunmap(bprm->page[j - 1]);
 386                 to = from;
 387         }
 388         memmove(to, to + offset, PAGE_SIZE - offset);
 389         kunmap(bprm->page[j - 1]);
 390
 391         /* Limit stack size to 1GB */
 392         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 393         if (stack_base > (1 << 30))
 394                 stack_base = 1 << 30;
 395         stack_base = PAGE_ALIGN(stack_top - stack_base);
 396
 397         /* Adjust bprm->p to point to the end of the strings. */
 398         bprm->p = stack_base + PAGE_SIZE * i - offset;
 399
 400         mm->arg_start = stack_base;
 401         arg_size = i << PAGE_SHIFT;
 402
 403         /* zero pages that were copied above */
 404         while (i < MAX_ARG_PAGES)
 405                 bprm->page[i++] = NULL;
 406 #else
 407         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
 408         stack_base = PAGE_ALIGN(stack_base);
 409         bprm->p += stack_base;
 410         mm->arg_start = bprm->p;
 411         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
 412 #endif
 413
 414         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 415
 416         if (bprm->loader)
 417                 bprm->loader += stack_base;
 418         bprm->exec += stack_base;
 419
 420         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 421         if (!mpnt)
 422                 return -ENOMEM;
 423
 424         if (security_vm_enough_memory(arg_size >> PAGE_SHIFT)) {
 425                 kmem_cache_free(vm_area_cachep, mpnt);
 426                 return -ENOMEM;
 427         }
 428
 429         memset(mpnt, 0, sizeof(*mpnt));
 430
 431         down_write(&mm->mmap_sem);
 432         {
 433                 mpnt->vm_mm = mm;
 434 #ifdef CONFIG_STACK_GROWSUP
 435                 mpnt->vm_start = stack_base;
 436                 mpnt->vm_end = stack_base + arg_size;
 437 #else
 438                 mpnt->vm_end = stack_top;
 439                 mpnt->vm_start = mpnt->vm_end - arg_size;
 440 #endif
 441                 /* Adjust stack execute permissions; explicitly enable
 442                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
 443                  * and leave alone (arch default) otherwise. */
 444                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 445                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
 446                 else if (executable_stack == EXSTACK_DISABLE_X)
 447                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
 448                 else
 449                         mpnt->vm_flags = VM_STACK_FLAGS;
 450                 mpnt->vm_flags |= mm->def_flags;
 451                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
 452                 if ((ret = insert_vm_struct(mm, mpnt))) {
 453                         up_write(&mm->mmap_sem);
 454                         kmem_cache_free(vm_area_cachep, mpnt);
 455                         return ret;
 456                 }
 457                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
 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         else {
 646                 /*
 647                  * The SIGALRM timer survives the exec, but needs to point
 648                  * at us as the new group leader now.  We have a race with
 649                  * a timer firing now getting the old leader, so we need to
 650                  * synchronize with any firing (by calling del_timer_sync)
 651                  * before we can safely let the old group leader die.
 652                  */
 653                 sig->real_timer.data = (unsigned long)current;
 654                 if (del_timer_sync(&sig->real_timer))
 655                         add_timer(&sig->real_timer);
 656         }
 657         while (atomic_read(&sig->count) > count) {
 658                 sig->group_exit_task = current;
 659                 sig->notify_count = count;
 660                 __set_current_state(TASK_UNINTERRUPTIBLE);
 661                 spin_unlock_irq(lock);
 662                 schedule();
 663                 spin_lock_irq(lock);
 664         }
 665         sig->group_exit_task = NULL;
 666         sig->notify_count = 0;
 667         sig->real_timer.data = (unsigned long)current;
 668         spin_unlock_irq(lock);
 669
 670         /*
 671          * At this point all other threads have exited, all we have to
 672          * do is to wait for the thread group leader to become inactive,
 673          * and to assume its PID:
 674          */
 675         if (!thread_group_leader(current)) {
 676                 struct task_struct *leader = current->group_leader, *parent;
 677                 struct dentry *proc_dentry1, *proc_dentry2;
 678                 unsigned long exit_state, ptrace;
 679
 680                 /*
 681                  * Wait for the thread group leader to be a zombie.
 682                  * It should already be zombie at this point, most
 683                  * of the time.
 684                  */
 685                 while (leader->exit_state != EXIT_ZOMBIE)
 686                         yield();
 687
 688                 spin_lock(&leader->proc_lock);
 689                 spin_lock(&current->proc_lock);
 690                 proc_dentry1 = proc_pid_unhash(current);
 691                 proc_dentry2 = proc_pid_unhash(leader);
 692                 write_lock_irq(&tasklist_lock);
 693
 694                 BUG_ON(leader->tgid != current->tgid);
 695                 BUG_ON(current->pid == current->tgid);
 696                 /*
 697                  * An exec() starts a new thread group with the
 698                  * TGID of the previous thread group. Rehash the
 699                  * two threads with a switched PID, and release
 700                  * the former thread group leader:
 701                  */
 702                 ptrace = leader->ptrace;
 703                 parent = leader->parent;
 704                 if (unlikely(ptrace) && unlikely(parent == current)) {
 705                         /*
 706                          * Joker was ptracing his own group leader,
 707                          * and now he wants to be his own parent!
 708                          * We can't have that.
 709                          */
 710                         ptrace = 0;
 711                 }
 712
 713                 ptrace_unlink(current);
 714                 ptrace_unlink(leader);
 715                 remove_parent(current);
 716                 remove_parent(leader);
 717
 718                 switch_exec_pids(leader, current);
 719
 720                 current->parent = current->real_parent = leader->real_parent;
 721                 leader->parent = leader->real_parent = child_reaper;
 722                 current->group_leader = current;
 723                 leader->group_leader = leader;
 724
 725                 add_parent(current, current->parent);
 726                 add_parent(leader, leader->parent);
 727                 if (ptrace) {
 728                         current->ptrace = ptrace;
 729                         __ptrace_link(current, parent);
 730                 }
 731
 732                 list_del(&current->tasks);
 733                 list_add_tail(&current->tasks, &init_task.tasks);
 734                 current->exit_signal = SIGCHLD;
 735                 exit_state = leader->exit_state;
 736
 737                 write_unlock_irq(&tasklist_lock);
 738                 spin_unlock(&leader->proc_lock);
 739                 spin_unlock(&current->proc_lock);
 740                 proc_pid_flush(proc_dentry1);
 741                 proc_pid_flush(proc_dentry2);
 742
 743                 BUG_ON(exit_state != EXIT_ZOMBIE);
 744                 release_task(leader);
 745         }
 746
 747         /*
 748          * Now there are really no other threads at all,
 749          * so it's safe to stop telling them to kill themselves.
 750          */
 751         sig->flags = 0;
 752
 753 no_thread_group:
 754         BUG_ON(atomic_read(&sig->count) != 1);
 755         exit_itimers(sig);
 756
 757         if (atomic_read(&oldsighand->count) == 1) {
 758                 /*
 759                  * Now that we nuked the rest of the thread group,
 760                  * it turns out we are not sharing sighand any more either.
 761                  * So we can just keep it.
 762                  */
 763                 kmem_cache_free(sighand_cachep, newsighand);
 764         } else {
 765                 /*
 766                  * Move our state over to newsighand and switch it in.
 767                  */
 768                 spin_lock_init(&newsighand->siglock);
 769                 atomic_set(&newsighand->count, 1);
 770                 memcpy(newsighand->action, oldsighand->action,
 771                        sizeof(newsighand->action));
 772
 773                 write_lock_irq(&tasklist_lock);
 774                 spin_lock(&oldsighand->siglock);
 775                 spin_lock(&newsighand->siglock);
 776
 777                 current->sighand = newsighand;
 778                 recalc_sigpending();
 779
 780                 spin_unlock(&newsighand->siglock);
 781                 spin_unlock(&oldsighand->siglock);
 782                 write_unlock_irq(&tasklist_lock);
 783
 784                 if (atomic_dec_and_test(&oldsighand->count))
 785                         kmem_cache_free(sighand_cachep, oldsighand);
 786         }
 787
 788         BUG_ON(!thread_group_empty(current));
 789         BUG_ON(!thread_group_leader(current));
 790         return 0;
 791 }
 792
 793 /*
 794  * These functions flushes out all traces of the currently running executable
 795  * so that a new one can be started
 796  */
 797
 798 static inline void flush_old_files(struct files_struct * files)
 799 {
 800         long j = -1;
 801
 802         spin_lock(&files->file_lock);
 803         for (;;) {
 804                 unsigned long set, i;
 805
 806                 j++;
 807                 i = j * __NFDBITS;
 808                 if (i >= files->max_fds || i >= files->max_fdset)
 809                         break;
 810                 set = files->close_on_exec->fds_bits[j];
 811                 if (!set)
 812                         continue;
 813                 files->close_on_exec->fds_bits[j] = 0;
 814                 spin_unlock(&files->file_lock);
 815                 for ( ; set ; i++,set >>= 1) {
 816                         if (set & 1) {
 817                                 sys_close(i);
 818                         }
 819                 }
 820                 spin_lock(&files->file_lock);
 821
 822         }
 823         spin_unlock(&files->file_lock);
 824 }
 825
 826 void get_task_comm(char *buf, struct task_struct *tsk)
 827 {
 828         /* buf must be at least sizeof(tsk->comm) in size */
 829         task_lock(tsk);
 830         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 831         task_unlock(tsk);
 832 }
 833
 834 void set_task_comm(struct task_struct *tsk, char *buf)
 835 {
 836         task_lock(tsk);
 837         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 838         task_unlock(tsk);
 839 }
 840
 841 int flush_old_exec(struct linux_binprm * bprm)
 842 {
 843         char * name;
 844         int i, ch, retval;
 845         struct files_struct *files;
 846         char tcomm[sizeof(current->comm)];
 847
 848         /*
 849          * Make sure we have a private signal table and that
 850          * we are unassociated from the previous thread group.
 851          */
 852         retval = de_thread(current);
 853         if (retval)
 854                 goto out;
 855
 856         /*
 857          * Make sure we have private file handles. Ask the
 858          * fork helper to do the work for us and the exit
 859          * helper to do the cleanup of the old one.
 860          */
 861         files = current->files;         /* refcounted so safe to hold */
 862         retval = unshare_files();
 863         if (retval)
 864                 goto out;
 865         /*
 866          * Release all of the old mmap stuff
 867          */
 868         retval = exec_mmap(bprm->mm);
 869         if (retval)
 870                 goto mmap_failed;
 871
 872         bprm->mm = NULL;                /* We're using it now */
 873
 874         /* This is the point of no return */
 875         steal_locks(files);
 876         put_files_struct(files);
 877
 878         current->sas_ss_sp = current->sas_ss_size = 0;
 879
 880         if (current->euid == current->uid && current->egid == current->gid)
 881                 current->mm->dumpable = 1;
 882         else
 883                 current->mm->dumpable = suid_dumpable;
 884
 885         name = bprm->filename;
 886
 887         /* Copies the binary name from after last slash */
 888         for (i=0; (ch = *(name++)) != '\0';) {
 889                 if (ch == '/')
 890                         i = 0; /* overwrite what we wrote */
 891                 else
 892                         if (i < (sizeof(tcomm) - 1))
 893                                 tcomm[i++] = ch;
 894         }
 895         tcomm[i] = '\0';
 896         set_task_comm(current, tcomm);
 897
 898         current->flags &= ~PF_RANDOMIZE;
 899         flush_thread();
 900
 901         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
 902             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
 903             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
 904                 suid_keys(current);
 905                 current->mm->dumpable = suid_dumpable;
 906         }
 907
 908         /* An exec changes our domain. We are no longer part of the thread
 909            group */
 910
 911         current->self_exec_id++;
 912
 913         flush_signal_handlers(current, 0);
 914         flush_old_files(current->files);
 915
 916         return 0;
 917
 918 mmap_failed:
 919         put_files_struct(current->files);
 920         current->files = files;
 921 out:
 922         return retval;
 923 }
 924
 925 EXPORT_SYMBOL(flush_old_exec);
 926
 927 /*
 928  * Fill the binprm structure from the inode.
 929  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 930  */
 931 int prepare_binprm(struct linux_binprm *bprm)
 932 {
 933         int mode;
 934         struct inode * inode = bprm->file->f_dentry->d_inode;
 935         int retval;
 936
 937         mode = inode->i_mode;
 938         /*
 939          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
 940          * generic_permission lets a non-executable through
 941          */
 942         if (!(mode & 0111))     /* with at least _one_ execute bit set */
 943                 return -EACCES;
 944         if (bprm->file->f_op == NULL)
 945                 return -EACCES;
 946
 947         bprm->e_uid = current->euid;
 948         bprm->e_gid = current->egid;
 949
 950         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
 951                 /* Set-uid? */
 952                 if (mode & S_ISUID) {
 953                         current->personality &= ~PER_CLEAR_ON_SETID;
 954                         bprm->e_uid = inode->i_uid;
 955                 }
 956
 957                 /* Set-gid? */
 958                 /*
 959                  * If setgid is set but no group execute bit then this
 960                  * is a candidate for mandatory locking, not a setgid
 961                  * executable.
 962                  */
 963                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 964                         current->personality &= ~PER_CLEAR_ON_SETID;
 965                         bprm->e_gid = inode->i_gid;
 966                 }
 967         }
 968
 969         /* fill in binprm security blob */
 970         retval = security_bprm_set(bprm);
 971         if (retval)
 972                 return retval;
 973
 974         memset(bprm->buf,0,BINPRM_BUF_SIZE);
 975         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
 976 }
 977
 978 EXPORT_SYMBOL(prepare_binprm);
 979
 980 static inline int unsafe_exec(struct task_struct *p)
 981 {
 982         int unsafe = 0;
 983         if (p->ptrace & PT_PTRACED) {
 984                 if (p->ptrace & PT_PTRACE_CAP)
 985                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
 986                 else
 987                         unsafe |= LSM_UNSAFE_PTRACE;
 988         }
 989         if (atomic_read(&p->fs->count) > 1 ||
 990             atomic_read(&p->files->count) > 1 ||
 991             atomic_read(&p->sighand->count) > 1)
 992                 unsafe |= LSM_UNSAFE_SHARE;
 993
 994         return unsafe;
 995 }
 996
 997 void compute_creds(struct linux_binprm *bprm)
 998 {
 999         int unsafe;
1000
1001         if (bprm->e_uid != current->uid)
1002                 suid_keys(current);
1003         exec_keys(current);
1004
1005         task_lock(current);
1006         unsafe = unsafe_exec(current);
1007         security_bprm_apply_creds(bprm, unsafe);
1008         task_unlock(current);
1009         security_bprm_post_apply_creds(bprm);
1010 }
1011
1012 EXPORT_SYMBOL(compute_creds);
1013
1014 void remove_arg_zero(struct linux_binprm *bprm)
1015 {
1016         if (bprm->argc) {
1017                 unsigned long offset;
1018                 char * kaddr;
1019                 struct page *page;
1020
1021                 offset = bprm->p % PAGE_SIZE;
1022                 goto inside;
1023
1024                 while (bprm->p++, *(kaddr+offset++)) {
1025                         if (offset != PAGE_SIZE)
1026                                 continue;
1027                         offset = 0;
1028                         kunmap_atomic(kaddr, KM_USER0);
1029 inside:
1030                         page = bprm->page[bprm->p/PAGE_SIZE];
1031                         kaddr = kmap_atomic(page, KM_USER0);
1032                 }
1033                 kunmap_atomic(kaddr, KM_USER0);
1034                 bprm->argc--;
1035         }
1036 }
1037
1038 EXPORT_SYMBOL(remove_arg_zero);
1039
1040 /*
1041  * cycle the list of binary formats handler, until one recognizes the image
1042  */
1043 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1044 {
1045         int try,retval;
1046         struct linux_binfmt *fmt;
1047 #ifdef __alpha__
1048         /* handle /sbin/loader.. */
1049         {
1050             struct exec * eh = (struct exec *) bprm->buf;
1051
1052             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1053                 (eh->fh.f_flags & 0x3000) == 0x3000)
1054             {
1055                 struct file * file;
1056                 unsigned long loader;
1057
1058                 allow_write_access(bprm->file);
1059                 fput(bprm->file);
1060                 bprm->file = NULL;
1061
1062                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1063
1064                 file = open_exec("/sbin/loader");
1065                 retval = PTR_ERR(file);
1066                 if (IS_ERR(file))
1067                         return retval;
1068
1069                 /* Remember if the application is TASO.  */
1070                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1071
1072                 bprm->file = file;
1073                 bprm->loader = loader;
1074                 retval = prepare_binprm(bprm);
1075                 if (retval<0)
1076                         return retval;
1077                 /* should call search_binary_handler recursively here,
1078                    but it does not matter */
1079             }
1080         }
1081 #endif
1082         retval = security_bprm_check(bprm);
1083         if (retval)
1084                 return retval;
1085
1086         /* kernel module loader fixup */
1087         /* so we don't try to load run modprobe in kernel space. */
1088         set_fs(USER_DS);
1089         retval = -ENOENT;
1090         for (try=0; try<2; try++) {
1091                 read_lock(&binfmt_lock);
1092                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1093                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1094                         if (!fn)
1095                                 continue;
1096                         if (!try_module_get(fmt->module))
1097                                 continue;
1098                         read_unlock(&binfmt_lock);
1099                         retval = fn(bprm, regs);
1100                         if (retval >= 0) {
1101                                 put_binfmt(fmt);
1102                                 allow_write_access(bprm->file);
1103                                 if (bprm->file)
1104                                         fput(bprm->file);
1105                                 bprm->file = NULL;
1106                                 current->did_exec = 1;
1107                                 return retval;
1108                         }
1109                         read_lock(&binfmt_lock);
1110                         put_binfmt(fmt);
1111                         if (retval != -ENOEXEC || bprm->mm == NULL)
1112                                 break;
1113                         if (!bprm->file) {
1114                                 read_unlock(&binfmt_lock);
1115                                 return retval;
1116                         }
1117                 }
1118                 read_unlock(&binfmt_lock);
1119                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1120                         break;
1121 #ifdef CONFIG_KMOD
1122                 }else{
1123 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1124                         if (printable(bprm->buf[0]) &&
1125                             printable(bprm->buf[1]) &&
1126                             printable(bprm->buf[2]) &&
1127                             printable(bprm->buf[3]))
1128                                 break; /* -ENOEXEC */
1129                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1130 #endif
1131                 }
1132         }
1133         return retval;
1134 }
1135
1136 EXPORT_SYMBOL(search_binary_handler);
1137
1138 /*
1139  * sys_execve() executes a new program.
1140  */
1141 int do_execve(char * filename,
1142         char __user *__user *argv,
1143         char __user *__user *envp,
1144         struct pt_regs * regs)
1145 {
1146         struct linux_binprm *bprm;
1147         struct file *file;
1148         int retval;
1149         int i;
1150
1151         retval = -ENOMEM;
1152         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1153         if (!bprm)
1154                 goto out_ret;
1155         memset(bprm, 0, sizeof(*bprm));
1156
1157         file = open_exec(filename);
1158         retval = PTR_ERR(file);
1159         if (IS_ERR(file))
1160                 goto out_kfree;
1161
1162         sched_exec();
1163
1164         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1165
1166         bprm->file = file;
1167         bprm->filename = filename;
1168         bprm->interp = filename;
1169         bprm->mm = mm_alloc();
1170         retval = -ENOMEM;
1171         if (!bprm->mm)
1172                 goto out_file;
1173
1174         retval = init_new_context(current, bprm->mm);
1175         if (retval < 0)
1176                 goto out_mm;
1177
1178         bprm->argc = count(argv, bprm->p / sizeof(void *));
1179         if ((retval = bprm->argc) < 0)
1180                 goto out_mm;
1181
1182         bprm->envc = count(envp, bprm->p / sizeof(void *));
1183         if ((retval = bprm->envc) < 0)
1184                 goto out_mm;
1185
1186         retval = security_bprm_alloc(bprm);
1187         if (retval)
1188                 goto out;
1189
1190         retval = prepare_binprm(bprm);
1191         if (retval < 0)
1192                 goto out;
1193
1194         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1195         if (retval < 0)
1196                 goto out;
1197
1198         bprm->exec = bprm->p;
1199         retval = copy_strings(bprm->envc, envp, bprm);
1200         if (retval < 0)
1201                 goto out;
1202
1203         retval = copy_strings(bprm->argc, argv, bprm);
1204         if (retval < 0)
1205                 goto out;
1206
1207         retval = search_binary_handler(bprm,regs);
1208         if (retval >= 0) {
1209                 free_arg_pages(bprm);
1210
1211                 /* execve success */
1212                 security_bprm_free(bprm);
1213                 acct_update_integrals(current);
1214                 update_mem_hiwater(current);
1215                 kfree(bprm);
1216                 return retval;
1217         }
1218
1219 out:
1220         /* Something went wrong, return the inode and free the argument pages*/
1221         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1222                 struct page * page = bprm->page[i];
1223                 if (page)
1224                         __free_page(page);
1225         }
1226
1227         if (bprm->security)
1228                 security_bprm_free(bprm);
1229
1230 out_mm:
1231         if (bprm->mm)
1232                 mmdrop(bprm->mm);
1233
1234 out_file:
1235         if (bprm->file) {
1236                 allow_write_access(bprm->file);
1237                 fput(bprm->file);
1238         }
1239
1240 out_kfree:
1241         kfree(bprm);
1242
1243 out_ret:
1244         return retval;
1245 }
1246
1247 int set_binfmt(struct linux_binfmt *new)
1248 {
1249         struct linux_binfmt *old = current->binfmt;
1250
1251         if (new) {
1252                 if (!try_module_get(new->module))
1253                         return -1;
1254         }
1255         current->binfmt = new;
1256         if (old)
1257                 module_put(old->module);
1258         return 0;
1259 }
1260
1261 EXPORT_SYMBOL(set_binfmt);
1262
1263 #define CORENAME_MAX_SIZE 64
1264
1265 /* format_corename will inspect the pattern parameter, and output a
1266  * name into corename, which must have space for at least
1267  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1268  */
1269 static void format_corename(char *corename, const char *pattern, long signr)
1270 {
1271         const char *pat_ptr = pattern;
1272         char *out_ptr = corename;
1273         char *const out_end = corename + CORENAME_MAX_SIZE;
1274         int rc;
1275         int pid_in_pattern = 0;
1276
1277         /* Repeat as long as we have more pattern to process and more output
1278            space */
1279         while (*pat_ptr) {
1280                 if (*pat_ptr != '%') {
1281                         if (out_ptr == out_end)
1282                                 goto out;
1283                         *out_ptr++ = *pat_ptr++;
1284                 } else {
1285                         switch (*++pat_ptr) {
1286                         case 0:
1287                                 goto out;
1288                         /* Double percent, output one percent */
1289                         case '%':
1290                                 if (out_ptr == out_end)
1291                                         goto out;
1292                                 *out_ptr++ = '%';
1293                                 break;
1294                         /* pid */
1295                         case 'p':
1296                                 pid_in_pattern = 1;
1297                                 rc = snprintf(out_ptr, out_end - out_ptr,
1298                                               "%d", current->tgid);
1299                                 if (rc > out_end - out_ptr)
1300                                         goto out;
1301                                 out_ptr += rc;
1302                                 break;
1303                         /* uid */
1304                         case 'u':
1305                                 rc = snprintf(out_ptr, out_end - out_ptr,
1306                                               "%d", current->uid);
1307                                 if (rc > out_end - out_ptr)
1308                                         goto out;
1309                                 out_ptr += rc;
1310                                 break;
1311                         /* gid */
1312                         case 'g':
1313                                 rc = snprintf(out_ptr, out_end - out_ptr,
1314                                               "%d", current->gid);
1315                                 if (rc > out_end - out_ptr)
1316                                         goto out;
1317                                 out_ptr += rc;
1318                                 break;
1319                         /* signal that caused the coredump */
1320                         case 's':
1321                                 rc = snprintf(out_ptr, out_end - out_ptr,
1322                                               "%ld", signr);
1323                                 if (rc > out_end - out_ptr)
1324                                         goto out;
1325                                 out_ptr += rc;
1326                                 break;
1327                         /* UNIX time of coredump */
1328                         case 't': {
1329                                 struct timeval tv;
1330                                 do_gettimeofday(&tv);
1331                                 rc = snprintf(out_ptr, out_end - out_ptr,
1332                                               "%lu", tv.tv_sec);
1333                                 if (rc > out_end - out_ptr)
1334                                         goto out;
1335                                 out_ptr += rc;
1336                                 break;
1337                         }
1338                         /* hostname */
1339                         case 'h':
1340                                 down_read(&uts_sem);
1341                                 rc = snprintf(out_ptr, out_end - out_ptr,
1342                                               "%s", system_utsname.nodename);
1343                                 up_read(&uts_sem);
1344                                 if (rc > out_end - out_ptr)
1345                                         goto out;
1346                                 out_ptr += rc;
1347                                 break;
1348                         /* executable */
1349                         case 'e':
1350                                 rc = snprintf(out_ptr, out_end - out_ptr,
1351                                               "%s", current->comm);
1352                                 if (rc > out_end - out_ptr)
1353                                         goto out;
1354                                 out_ptr += rc;
1355                                 break;
1356                         default:
1357                                 break;
1358                         }
1359                         ++pat_ptr;
1360                 }
1361         }
1362         /* Backward compatibility with core_uses_pid:
1363          *
1364          * If core_pattern does not include a %p (as is the default)
1365          * and core_uses_pid is set, then .%pid will be appended to
1366          * the filename */
1367         if (!pid_in_pattern
1368             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1369                 rc = snprintf(out_ptr, out_end - out_ptr,
1370                               ".%d", current->tgid);
1371                 if (rc > out_end - out_ptr)
1372                         goto out;
1373                 out_ptr += rc;
1374         }
1375       out:
1376         *out_ptr = 0;
1377 }
1378
1379 static void zap_threads (struct mm_struct *mm)
1380 {
1381         struct task_struct *g, *p;
1382         struct task_struct *tsk = current;
1383         struct completion *vfork_done = tsk->vfork_done;
1384         int traced = 0;
1385
1386         /*
1387          * Make sure nobody is waiting for us to release the VM,
1388          * otherwise we can deadlock when we wait on each other
1389          */
1390         if (vfork_done) {
1391                 tsk->vfork_done = NULL;
1392                 complete(vfork_done);
1393         }
1394
1395         read_lock(&tasklist_lock);
1396         do_each_thread(g,p)
1397                 if (mm == p->mm && p != tsk) {
1398                         force_sig_specific(SIGKILL, p);
1399                         mm->core_waiters++;
1400                         if (unlikely(p->ptrace) &&
1401                             unlikely(p->parent->mm == mm))
1402                                 traced = 1;
1403                 }
1404         while_each_thread(g,p);
1405
1406         read_unlock(&tasklist_lock);
1407
1408         if (unlikely(traced)) {
1409                 /*
1410                  * We are zapping a thread and the thread it ptraces.
1411                  * If the tracee went into a ptrace stop for exit tracing,
1412                  * we could deadlock since the tracer is waiting for this
1413                  * coredump to finish.  Detach them so they can both die.
1414                  */
1415                 write_lock_irq(&tasklist_lock);
1416                 do_each_thread(g,p) {
1417                         if (mm == p->mm && p != tsk &&
1418                             p->ptrace && p->parent->mm == mm) {
1419                                 __ptrace_unlink(p);
1420                         }
1421                 } while_each_thread(g,p);
1422                 write_unlock_irq(&tasklist_lock);
1423         }
1424 }
1425
1426 static void coredump_wait(struct mm_struct *mm)
1427 {
1428         DECLARE_COMPLETION(startup_done);
1429
1430         mm->core_waiters++; /* let other threads block */
1431         mm->core_startup_done = &startup_done;
1432
1433         /* give other threads a chance to run: */
1434         yield();
1435
1436         zap_threads(mm);
1437         if (--mm->core_waiters) {
1438                 up_write(&mm->mmap_sem);
1439                 wait_for_completion(&startup_done);
1440         } else
1441                 up_write(&mm->mmap_sem);
1442         BUG_ON(mm->core_waiters);
1443 }
1444
1445 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1446 {
1447         char corename[CORENAME_MAX_SIZE + 1];
1448         struct mm_struct *mm = current->mm;
1449         struct linux_binfmt * binfmt;
1450         struct inode * inode;
1451         struct file * file;
1452         int retval = 0;
1453         int fsuid = current->fsuid;
1454         int flag = 0;
1455
1456         binfmt = current->binfmt;
1457         if (!binfmt || !binfmt->core_dump)
1458                 goto fail;
1459         down_write(&mm->mmap_sem);
1460         if (!mm->dumpable) {
1461                 up_write(&mm->mmap_sem);
1462                 goto fail;
1463         }
1464
1465         /*
1466          *      We cannot trust fsuid as being the "true" uid of the
1467          *      process nor do we know its entire history. We only know it
1468          *      was tainted so we dump it as root in mode 2.
1469          */
1470         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1471                 flag = O_EXCL;          /* Stop rewrite attacks */
1472                 current->fsuid = 0;     /* Dump root private */
1473         }
1474         mm->dumpable = 0;
1475         init_completion(&mm->core_done);
1476         spin_lock_irq(&current->sighand->siglock);
1477         current->signal->flags = SIGNAL_GROUP_EXIT;
1478         current->signal->group_exit_code = exit_code;
1479         spin_unlock_irq(&current->sighand->siglock);
1480         coredump_wait(mm);
1481
1482         /*
1483          * Clear any false indication of pending signals that might
1484          * be seen by the filesystem code called to write the core file.
1485          */
1486         current->signal->group_stop_count = 0;
1487         clear_thread_flag(TIF_SIGPENDING);
1488
1489         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1490                 goto fail_unlock;
1491
1492         /*
1493          * lock_kernel() because format_corename() is controlled by sysctl, which
1494          * uses lock_kernel()
1495          */
1496         lock_kernel();
1497         format_corename(corename, core_pattern, signr);
1498         unlock_kernel();
1499         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1500         if (IS_ERR(file))
1501                 goto fail_unlock;
1502         inode = file->f_dentry->d_inode;
1503         if (inode->i_nlink > 1)
1504                 goto close_fail;        /* multiple links - don't dump */
1505         if (d_unhashed(file->f_dentry))
1506                 goto close_fail;
1507
1508         if (!S_ISREG(inode->i_mode))
1509                 goto close_fail;
1510         if (!file->f_op)
1511                 goto close_fail;
1512         if (!file->f_op->write)
1513                 goto close_fail;
1514         if (do_truncate(file->f_dentry, 0) != 0)
1515                 goto close_fail;
1516
1517         retval = binfmt->core_dump(signr, regs, file);
1518
1519         if (retval)
1520                 current->signal->group_exit_code |= 0x80;
1521 close_fail:
1522         filp_close(file, NULL);
1523 fail_unlock:
1524         current->fsuid = fsuid;
1525         complete_all(&mm->core_done);
1526 fail:
1527         return retval;
1528 }