fs/exec.c

   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/slab.h>
  27 #include <linux/file.h>
  28 #include <linux/mman.h>
  29 #include <linux/a.out.h>
  30 #include <linux/stat.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/smp_lock.h>
  33 #include <linux/init.h>
  34 #include <linux/pagemap.h>
  35 #include <linux/highmem.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/key.h>
  38 #include <linux/personality.h>
  39 #include <linux/binfmts.h>
  40 #include <linux/swap.h>
  41 #include <linux/utsname.h>
  42 #include <linux/module.h>
  43 #include <linux/namei.h>
  44 #include <linux/proc_fs.h>
  45 #include <linux/ptrace.h>
  46 #include <linux/mount.h>
  47 #include <linux/security.h>
  48 #include <linux/syscalls.h>
  49 #include <linux/rmap.h>
  50 #include <linux/acct.h>
  51 #include <linux/cn_proc.h>
  52
  53 #include <asm/uaccess.h>
  54 #include <asm/mmu_context.h>
  55
  56 #ifdef CONFIG_KMOD
  57 #include <linux/kmod.h>
  58 #endif
  59
  60 int core_uses_pid;
  61 char core_pattern[65] = "core";
  62 int suid_dumpable = 0;
  63
  64 EXPORT_SYMBOL(suid_dumpable);
  65 /* The maximal length of core_pattern is also specified in sysctl.c */
  66
  67 static struct linux_binfmt *formats;
  68 static DEFINE_RWLOCK(binfmt_lock);
  69
  70 int register_binfmt(struct linux_binfmt * fmt)
  71 {
  72         struct linux_binfmt ** tmp = &formats;
  73
  74         if (!fmt)
  75                 return -EINVAL;
  76         if (fmt->next)
  77                 return -EBUSY;
  78         write_lock(&binfmt_lock);
  79         while (*tmp) {
  80                 if (fmt == *tmp) {
  81                         write_unlock(&binfmt_lock);
  82                         return -EBUSY;
  83                 }
  84                 tmp = &(*tmp)->next;
  85         }
  86         fmt->next = formats;
  87         formats = fmt;
  88         write_unlock(&binfmt_lock);
  89         return 0;
  90 }
  91
  92 EXPORT_SYMBOL(register_binfmt);
  93
  94 int unregister_binfmt(struct linux_binfmt * fmt)
  95 {
  96         struct linux_binfmt ** tmp = &formats;
  97
  98         write_lock(&binfmt_lock);
  99         while (*tmp) {
 100                 if (fmt == *tmp) {
 101                         *tmp = fmt->next;
 102                         write_unlock(&binfmt_lock);
 103                         return 0;
 104                 }
 105                 tmp = &(*tmp)->next;
 106         }
 107         write_unlock(&binfmt_lock);
 108         return -EINVAL;
 109 }
 110
 111 EXPORT_SYMBOL(unregister_binfmt);
 112
 113 static inline void put_binfmt(struct linux_binfmt * fmt)
 114 {
 115         module_put(fmt->module);
 116 }
 117
 118 /*
 119  * Note that a shared library must be both readable and executable due to
 120  * security reasons.
 121  *
 122  * Also note that we take the address to load from from the file itself.
 123  */
 124 asmlinkage long sys_uselib(const char __user * library)
 125 {
 126         struct file * file;
 127         struct nameidata nd;
 128         int error;
 129
 130         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ);
 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 = vfs_permission(&nd, MAY_READ | MAY_EXEC);
 139         if (error)
 140                 goto exit;
 141
 142         file = nameidata_to_filp(&nd, 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         release_open_intent(&nd);
 171         path_release(&nd);
 172         goto out;
 173 }
 174
 175 /*
 176  * count() counts the number of strings in array ARGV.
 177  */
 178 static int count(char __user * __user * argv, int max)
 179 {
 180         int i = 0;
 181
 182         if (argv != NULL) {
 183                 for (;;) {
 184                         char __user * p;
 185
 186                         if (get_user(p, argv))
 187                                 return -EFAULT;
 188                         if (!p)
 189                                 break;
 190                         argv++;
 191                         if(++i > max)
 192                                 return -E2BIG;
 193                         cond_resched();
 194                 }
 195         }
 196         return i;
 197 }
 198
 199 /*
 200  * 'copy_strings()' copies argument/environment strings from user
 201  * memory to free pages in kernel mem. These are in a format ready
 202  * to be put directly into the top of new user memory.
 203  */
 204 static int copy_strings(int argc, char __user * __user * argv,
 205                         struct linux_binprm *bprm)
 206 {
 207         struct page *kmapped_page = NULL;
 208         char *kaddr = NULL;
 209         int ret;
 210
 211         while (argc-- > 0) {
 212                 char __user *str;
 213                 int len;
 214                 unsigned long pos;
 215
 216                 if (get_user(str, argv+argc) ||
 217                                 !(len = strnlen_user(str, bprm->p))) {
 218                         ret = -EFAULT;
 219                         goto out;
 220                 }
 221
 222                 if (bprm->p < len)  {
 223                         ret = -E2BIG;
 224                         goto out;
 225                 }
 226
 227                 bprm->p -= len;
 228                 /* XXX: add architecture specific overflow check here. */
 229                 pos = bprm->p;
 230
 231                 while (len > 0) {
 232                         int i, new, err;
 233                         int offset, bytes_to_copy;
 234                         struct page *page;
 235
 236                         offset = pos % PAGE_SIZE;
 237                         i = pos/PAGE_SIZE;
 238                         page = bprm->page[i];
 239                         new = 0;
 240                         if (!page) {
 241                                 page = alloc_page(GFP_HIGHUSER);
 242                                 bprm->page[i] = page;
 243                                 if (!page) {
 244                                         ret = -ENOMEM;
 245                                         goto out;
 246                                 }
 247                                 new = 1;
 248                         }
 249
 250                         if (page != kmapped_page) {
 251                                 if (kmapped_page)
 252                                         kunmap(kmapped_page);
 253                                 kmapped_page = page;
 254                                 kaddr = kmap(kmapped_page);
 255                         }
 256                         if (new && offset)
 257                                 memset(kaddr, 0, offset);
 258                         bytes_to_copy = PAGE_SIZE - offset;
 259                         if (bytes_to_copy > len) {
 260                                 bytes_to_copy = len;
 261                                 if (new)
 262                                         memset(kaddr+offset+len, 0,
 263                                                 PAGE_SIZE-offset-len);
 264                         }
 265                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
 266                         if (err) {
 267                                 ret = -EFAULT;
 268                                 goto out;
 269                         }
 270
 271                         pos += bytes_to_copy;
 272                         str += bytes_to_copy;
 273                         len -= bytes_to_copy;
 274                 }
 275         }
 276         ret = 0;
 277 out:
 278         if (kmapped_page)
 279                 kunmap(kmapped_page);
 280         return ret;
 281 }
 282
 283 /*
 284  * Like copy_strings, but get argv and its values from kernel memory.
 285  */
 286 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 287 {
 288         int r;
 289         mm_segment_t oldfs = get_fs();
 290         set_fs(KERNEL_DS);
 291         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 292         set_fs(oldfs);
 293         return r;
 294 }
 295
 296 EXPORT_SYMBOL(copy_strings_kernel);
 297
 298 #ifdef CONFIG_MMU
 299 /*
 300  * This routine is used to map in a page into an address space: needed by
 301  * execve() for the initial stack and environment pages.
 302  *
 303  * vma->vm_mm->mmap_sem is held for writing.
 304  */
 305 void install_arg_page(struct vm_area_struct *vma,
 306                         struct page *page, unsigned long address)
 307 {
 308         struct mm_struct *mm = vma->vm_mm;
 309         pgd_t * pgd;
 310         pud_t * pud;
 311         pmd_t * pmd;
 312         pte_t * pte;
 313         spinlock_t *ptl;
 314
 315         if (unlikely(anon_vma_prepare(vma)))
 316                 goto out;
 317
 318         flush_dcache_page(page);
 319         pgd = pgd_offset(mm, address);
 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_lock(mm, pmd, address, &ptl);
 327         if (!pte)
 328                 goto out;
 329         if (!pte_none(*pte)) {
 330                 pte_unmap_unlock(pte, ptl);
 331                 goto out;
 332         }
 333         inc_mm_counter(mm, anon_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_unlock(pte, ptl);
 339
 340         /* no need for flush_tlb */
 341         return;
 342 out:
 343         __free_page(page);
 344         force_sig(SIGKILL, current);
 345 }
 346
 347 #define EXTRA_STACK_VM_PAGES    20      /* random */
 348
 349 int setup_arg_pages(struct linux_binprm *bprm,
 350                     unsigned long stack_top,
 351                     int executable_stack)
 352 {
 353         unsigned long stack_base;
 354         struct vm_area_struct *mpnt;
 355         struct mm_struct *mm = current->mm;
 356         int i, ret;
 357         long arg_size;
 358
 359 #ifdef CONFIG_STACK_GROWSUP
 360         /* Move the argument and environment strings to the bottom of the
 361          * stack space.
 362          */
 363         int offset, j;
 364         char *to, *from;
 365
 366         /* Start by shifting all the pages down */
 367         i = 0;
 368         for (j = 0; j < MAX_ARG_PAGES; j++) {
 369                 struct page *page = bprm->page[j];
 370                 if (!page)
 371                         continue;
 372                 bprm->page[i++] = page;
 373         }
 374
 375         /* Now move them within their pages */
 376         offset = bprm->p % PAGE_SIZE;
 377         to = kmap(bprm->page[0]);
 378         for (j = 1; j < i; j++) {
 379                 memmove(to, to + offset, PAGE_SIZE - offset);
 380                 from = kmap(bprm->page[j]);
 381                 memcpy(to + PAGE_SIZE - offset, from, offset);
 382                 kunmap(bprm->page[j - 1]);
 383                 to = from;
 384         }
 385         memmove(to, to + offset, PAGE_SIZE - offset);
 386         kunmap(bprm->page[j - 1]);
 387
 388         /* Limit stack size to 1GB */
 389         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 390         if (stack_base > (1 << 30))
 391                 stack_base = 1 << 30;
 392         stack_base = PAGE_ALIGN(stack_top - stack_base);
 393
 394         /* Adjust bprm->p to point to the end of the strings. */
 395         bprm->p = stack_base + PAGE_SIZE * i - offset;
 396
 397         mm->arg_start = stack_base;
 398         arg_size = i << PAGE_SHIFT;
 399
 400         /* zero pages that were copied above */
 401         while (i < MAX_ARG_PAGES)
 402                 bprm->page[i++] = NULL;
 403 #else
 404         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
 405         stack_base = PAGE_ALIGN(stack_base);
 406         bprm->p += stack_base;
 407         mm->arg_start = bprm->p;
 408         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
 409 #endif
 410
 411         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 412
 413         if (bprm->loader)
 414                 bprm->loader += stack_base;
 415         bprm->exec += stack_base;
 416
 417         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 418         if (!mpnt)
 419                 return -ENOMEM;
 420
 421         memset(mpnt, 0, sizeof(*mpnt));
 422
 423         down_write(&mm->mmap_sem);
 424         {
 425                 mpnt->vm_mm = mm;
 426 #ifdef CONFIG_STACK_GROWSUP
 427                 mpnt->vm_start = stack_base;
 428                 mpnt->vm_end = stack_base + arg_size;
 429 #else
 430                 mpnt->vm_end = stack_top;
 431                 mpnt->vm_start = mpnt->vm_end - arg_size;
 432 #endif
 433                 /* Adjust stack execute permissions; explicitly enable
 434                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
 435                  * and leave alone (arch default) otherwise. */
 436                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 437                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
 438                 else if (executable_stack == EXSTACK_DISABLE_X)
 439                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
 440                 else
 441                         mpnt->vm_flags = VM_STACK_FLAGS;
 442                 mpnt->vm_flags |= mm->def_flags;
 443                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
 444                 if ((ret = insert_vm_struct(mm, mpnt))) {
 445                         up_write(&mm->mmap_sem);
 446                         kmem_cache_free(vm_area_cachep, mpnt);
 447                         return ret;
 448                 }
 449                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
 450         }
 451
 452         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
 453                 struct page *page = bprm->page[i];
 454                 if (page) {
 455                         bprm->page[i] = NULL;
 456                         install_arg_page(mpnt, page, stack_base);
 457                 }
 458                 stack_base += PAGE_SIZE;
 459         }
 460         up_write(&mm->mmap_sem);
 461
 462         return 0;
 463 }
 464
 465 EXPORT_SYMBOL(setup_arg_pages);
 466
 467 #define free_arg_pages(bprm) do { } while (0)
 468
 469 #else
 470
 471 static inline void free_arg_pages(struct linux_binprm *bprm)
 472 {
 473         int i;
 474
 475         for (i = 0; i < MAX_ARG_PAGES; i++) {
 476                 if (bprm->page[i])
 477                         __free_page(bprm->page[i]);
 478                 bprm->page[i] = NULL;
 479         }
 480 }
 481
 482 #endif /* CONFIG_MMU */
 483
 484 struct file *open_exec(const char *name)
 485 {
 486         struct nameidata nd;
 487         int err;
 488         struct file *file;
 489
 490         err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ);
 491         file = ERR_PTR(err);
 492
 493         if (!err) {
 494                 struct inode *inode = nd.dentry->d_inode;
 495                 file = ERR_PTR(-EACCES);
 496                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
 497                     S_ISREG(inode->i_mode)) {
 498                         int err = vfs_permission(&nd, MAY_EXEC);
 499                         if (!err && !(inode->i_mode & 0111))
 500                                 err = -EACCES;
 501                         file = ERR_PTR(err);
 502                         if (!err) {
 503                                 file = nameidata_to_filp(&nd, O_RDONLY);
 504                                 if (!IS_ERR(file)) {
 505                                         err = deny_write_access(file);
 506                                         if (err) {
 507                                                 fput(file);
 508                                                 file = ERR_PTR(err);
 509                                         }
 510                                 }
 511 out:
 512                                 return file;
 513                         }
 514                 }
 515                 release_open_intent(&nd);
 516                 path_release(&nd);
 517         }
 518         goto out;
 519 }
 520
 521 EXPORT_SYMBOL(open_exec);
 522
 523 int kernel_read(struct file *file, unsigned long offset,
 524         char *addr, unsigned long count)
 525 {
 526         mm_segment_t old_fs;
 527         loff_t pos = offset;
 528         int result;
 529
 530         old_fs = get_fs();
 531         set_fs(get_ds());
 532         /* The cast to a user pointer is valid due to the set_fs() */
 533         result = vfs_read(file, (void __user *)addr, count, &pos);
 534         set_fs(old_fs);
 535         return result;
 536 }
 537
 538 EXPORT_SYMBOL(kernel_read);
 539
 540 static int exec_mmap(struct mm_struct *mm)
 541 {
 542         struct task_struct *tsk;
 543         struct mm_struct * old_mm, *active_mm;
 544
 545         /* Notify parent that we're no longer interested in the old VM */
 546         tsk = current;
 547         old_mm = current->mm;
 548         mm_release(tsk, old_mm);
 549
 550         if (old_mm) {
 551                 /*
 552                  * Make sure that if there is a core dump in progress
 553                  * for the old mm, we get out and die instead of going
 554                  * through with the exec.  We must hold mmap_sem around
 555                  * checking core_waiters and changing tsk->mm.  The
 556                  * core-inducing thread will increment core_waiters for
 557                  * each thread whose ->mm == old_mm.
 558                  */
 559                 down_read(&old_mm->mmap_sem);
 560                 if (unlikely(old_mm->core_waiters)) {
 561                         up_read(&old_mm->mmap_sem);
 562                         return -EINTR;
 563                 }
 564         }
 565         task_lock(tsk);
 566         active_mm = tsk->active_mm;
 567         tsk->mm = mm;
 568         tsk->active_mm = mm;
 569         activate_mm(active_mm, mm);
 570         task_unlock(tsk);
 571         arch_pick_mmap_layout(mm);
 572         if (old_mm) {
 573                 up_read(&old_mm->mmap_sem);
 574                 if (active_mm != old_mm) BUG();
 575                 mmput(old_mm);
 576                 return 0;
 577         }
 578         mmdrop(active_mm);
 579         return 0;
 580 }
 581
 582 /*
 583  * This function makes sure the current process has its own signal table,
 584  * so that flush_signal_handlers can later reset the handlers without
 585  * disturbing other processes.  (Other processes might share the signal
 586  * table via the CLONE_SIGHAND option to clone().)
 587  */
 588 static inline int de_thread(struct task_struct *tsk)
 589 {
 590         struct signal_struct *sig = tsk->signal;
 591         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
 592         spinlock_t *lock = &oldsighand->siglock;
 593         struct task_struct *leader = NULL;
 594         int count;
 595
 596         /*
 597          * If we don't share sighandlers, then we aren't sharing anything
 598          * and we can just re-use it all.
 599          */
 600         if (atomic_read(&oldsighand->count) <= 1) {
 601                 BUG_ON(atomic_read(&sig->count) != 1);
 602                 exit_itimers(sig);
 603                 return 0;
 604         }
 605
 606         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 607         if (!newsighand)
 608                 return -ENOMEM;
 609
 610         if (thread_group_empty(current))
 611                 goto no_thread_group;
 612
 613         /*
 614          * Kill all other threads in the thread group.
 615          * We must hold tasklist_lock to call zap_other_threads.
 616          */
 617         read_lock(&tasklist_lock);
 618         spin_lock_irq(lock);
 619         if (sig->flags & SIGNAL_GROUP_EXIT) {
 620                 /*
 621                  * Another group action in progress, just
 622                  * return so that the signal is processed.
 623                  */
 624                 spin_unlock_irq(lock);
 625                 read_unlock(&tasklist_lock);
 626                 kmem_cache_free(sighand_cachep, newsighand);
 627                 return -EAGAIN;
 628         }
 629         zap_other_threads(current);
 630         read_unlock(&tasklist_lock);
 631
 632         /*
 633          * Account for the thread group leader hanging around:
 634          */
 635         count = 1;
 636         if (!thread_group_leader(current)) {
 637                 count = 2;
 638                 /*
 639                  * The SIGALRM timer survives the exec, but needs to point
 640                  * at us as the new group leader now.  We have a race with
 641                  * a timer firing now getting the old leader, so we need to
 642                  * synchronize with any firing (by calling del_timer_sync)
 643                  * before we can safely let the old group leader die.
 644                  */
 645                 sig->real_timer.data = (unsigned long)current;
 646                 spin_unlock_irq(lock);
 647                 if (del_timer_sync(&sig->real_timer))
 648                         add_timer(&sig->real_timer);
 649                 spin_lock_irq(lock);
 650         }
 651         while (atomic_read(&sig->count) > count) {
 652                 sig->group_exit_task = current;
 653                 sig->notify_count = count;
 654                 __set_current_state(TASK_UNINTERRUPTIBLE);
 655                 spin_unlock_irq(lock);
 656                 schedule();
 657                 spin_lock_irq(lock);
 658         }
 659         sig->group_exit_task = NULL;
 660         sig->notify_count = 0;
 661         spin_unlock_irq(lock);
 662
 663         /*
 664          * At this point all other threads have exited, all we have to
 665          * do is to wait for the thread group leader to become inactive,
 666          * and to assume its PID:
 667          */
 668         if (!thread_group_leader(current)) {
 669                 struct task_struct *parent;
 670                 struct dentry *proc_dentry1, *proc_dentry2;
 671                 unsigned long exit_state, ptrace;
 672
 673                 /*
 674                  * Wait for the thread group leader to be a zombie.
 675                  * It should already be zombie at this point, most
 676                  * of the time.
 677                  */
 678                 leader = current->group_leader;
 679                 while (leader->exit_state != EXIT_ZOMBIE)
 680                         yield();
 681
 682                 spin_lock(&leader->proc_lock);
 683                 spin_lock(&current->proc_lock);
 684                 proc_dentry1 = proc_pid_unhash(current);
 685                 proc_dentry2 = proc_pid_unhash(leader);
 686                 write_lock_irq(&tasklist_lock);
 687
 688                 BUG_ON(leader->tgid != current->tgid);
 689                 BUG_ON(current->pid == current->tgid);
 690                 /*
 691                  * An exec() starts a new thread group with the
 692                  * TGID of the previous thread group. Rehash the
 693                  * two threads with a switched PID, and release
 694                  * the former thread group leader:
 695                  */
 696                 ptrace = leader->ptrace;
 697                 parent = leader->parent;
 698                 if (unlikely(ptrace) && unlikely(parent == current)) {
 699                         /*
 700                          * Joker was ptracing his own group leader,
 701                          * and now he wants to be his own parent!
 702                          * We can't have that.
 703                          */
 704                         ptrace = 0;
 705                 }
 706
 707                 ptrace_unlink(current);
 708                 ptrace_unlink(leader);
 709                 remove_parent(current);
 710                 remove_parent(leader);
 711
 712                 switch_exec_pids(leader, current);
 713
 714                 current->parent = current->real_parent = leader->real_parent;
 715                 leader->parent = leader->real_parent = child_reaper;
 716                 current->group_leader = current;
 717                 leader->group_leader = leader;
 718
 719                 add_parent(current, current->parent);
 720                 add_parent(leader, leader->parent);
 721                 if (ptrace) {
 722                         current->ptrace = ptrace;
 723                         __ptrace_link(current, parent);
 724                 }
 725
 726                 list_del(&current->tasks);
 727                 list_add_tail(&current->tasks, &init_task.tasks);
 728                 current->exit_signal = SIGCHLD;
 729                 exit_state = leader->exit_state;
 730
 731                 write_unlock_irq(&tasklist_lock);
 732                 spin_unlock(&leader->proc_lock);
 733                 spin_unlock(&current->proc_lock);
 734                 proc_pid_flush(proc_dentry1);
 735                 proc_pid_flush(proc_dentry2);
 736
 737                 BUG_ON(exit_state != EXIT_ZOMBIE);
 738         }
 739
 740         /*
 741          * There may be one thread left which is just exiting,
 742          * but it's safe to stop telling the group to kill themselves.
 743          */
 744         sig->flags = 0;
 745
 746 no_thread_group:
 747         exit_itimers(sig);
 748         if (leader)
 749                 release_task(leader);
 750
 751         BUG_ON(atomic_read(&sig->count) != 1);
 752
 753         if (atomic_read(&oldsighand->count) == 1) {
 754                 /*
 755                  * Now that we nuked the rest of the thread group,
 756                  * it turns out we are not sharing sighand any more either.
 757                  * So we can just keep it.
 758                  */
 759                 kmem_cache_free(sighand_cachep, newsighand);
 760         } else {
 761                 /*
 762                  * Move our state over to newsighand and switch it in.
 763                  */
 764                 spin_lock_init(&newsighand->siglock);
 765                 atomic_set(&newsighand->count, 1);
 766                 memcpy(newsighand->action, oldsighand->action,
 767                        sizeof(newsighand->action));
 768
 769                 write_lock_irq(&tasklist_lock);
 770                 spin_lock(&oldsighand->siglock);
 771                 spin_lock(&newsighand->siglock);
 772
 773                 current->sighand = newsighand;
 774                 recalc_sigpending();
 775
 776                 spin_unlock(&newsighand->siglock);
 777                 spin_unlock(&oldsighand->siglock);
 778                 write_unlock_irq(&tasklist_lock);
 779
 780                 if (atomic_dec_and_test(&oldsighand->count))
 781                         kmem_cache_free(sighand_cachep, oldsighand);
 782         }
 783
 784         BUG_ON(!thread_group_leader(current));
 785         return 0;
 786 }
 787
 788 /*
 789  * These functions flushes out all traces of the currently running executable
 790  * so that a new one can be started
 791  */
 792
 793 static inline void flush_old_files(struct files_struct * files)
 794 {
 795         long j = -1;
 796         struct fdtable *fdt;
 797
 798         spin_lock(&files->file_lock);
 799         for (;;) {
 800                 unsigned long set, i;
 801
 802                 j++;
 803                 i = j * __NFDBITS;
 804                 fdt = files_fdtable(files);
 805                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
 806                         break;
 807                 set = fdt->close_on_exec->fds_bits[j];
 808                 if (!set)
 809                         continue;
 810                 fdt->close_on_exec->fds_bits[j] = 0;
 811                 spin_unlock(&files->file_lock);
 812                 for ( ; set ; i++,set >>= 1) {
 813                         if (set & 1) {
 814                                 sys_close(i);
 815                         }
 816                 }
 817                 spin_lock(&files->file_lock);
 818
 819         }
 820         spin_unlock(&files->file_lock);
 821 }
 822
 823 void get_task_comm(char *buf, struct task_struct *tsk)
 824 {
 825         /* buf must be at least sizeof(tsk->comm) in size */
 826         task_lock(tsk);
 827         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 828         task_unlock(tsk);
 829 }
 830
 831 void set_task_comm(struct task_struct *tsk, char *buf)
 832 {
 833         task_lock(tsk);
 834         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 835         task_unlock(tsk);
 836 }
 837
 838 int flush_old_exec(struct linux_binprm * bprm)
 839 {
 840         char * name;
 841         int i, ch, retval;
 842         struct files_struct *files;
 843         char tcomm[sizeof(current->comm)];
 844
 845         /*
 846          * Make sure we have a private signal table and that
 847          * we are unassociated from the previous thread group.
 848          */
 849         retval = de_thread(current);
 850         if (retval)
 851                 goto out;
 852
 853         /*
 854          * Make sure we have private file handles. Ask the
 855          * fork helper to do the work for us and the exit
 856          * helper to do the cleanup of the old one.
 857          */
 858         files = current->files;         /* refcounted so safe to hold */
 859         retval = unshare_files();
 860         if (retval)
 861                 goto out;
 862         /*
 863          * Release all of the old mmap stuff
 864          */
 865         retval = exec_mmap(bprm->mm);
 866         if (retval)
 867                 goto mmap_failed;
 868
 869         bprm->mm = NULL;                /* We're using it now */
 870
 871         /* This is the point of no return */
 872         steal_locks(files);
 873         put_files_struct(files);
 874
 875         current->sas_ss_sp = current->sas_ss_size = 0;
 876
 877         if (current->euid == current->uid && current->egid == current->gid)
 878                 current->mm->dumpable = 1;
 879         else
 880                 current->mm->dumpable = suid_dumpable;
 881
 882         name = bprm->filename;
 883
 884         /* Copies the binary name from after last slash */
 885         for (i=0; (ch = *(name++)) != '\0';) {
 886                 if (ch == '/')
 887                         i = 0; /* overwrite what we wrote */
 888                 else
 889                         if (i < (sizeof(tcomm) - 1))
 890                                 tcomm[i++] = ch;
 891         }
 892         tcomm[i] = '\0';
 893         set_task_comm(current, tcomm);
 894
 895         current->flags &= ~PF_RANDOMIZE;
 896         flush_thread();
 897
 898         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
 899             file_permission(bprm->file, MAY_READ) ||
 900             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
 901                 suid_keys(current);
 902                 current->mm->dumpable = suid_dumpable;
 903         }
 904
 905         /* An exec changes our domain. We are no longer part of the thread
 906            group */
 907
 908         current->self_exec_id++;
 909
 910         flush_signal_handlers(current, 0);
 911         flush_old_files(current->files);
 912
 913         return 0;
 914
 915 mmap_failed:
 916         put_files_struct(current->files);
 917         current->files = files;
 918 out:
 919         return retval;
 920 }
 921
 922 EXPORT_SYMBOL(flush_old_exec);
 923
 924 /*
 925  * Fill the binprm structure from the inode.
 926  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 927  */
 928 int prepare_binprm(struct linux_binprm *bprm)
 929 {
 930         int mode;
 931         struct inode * inode = bprm->file->f_dentry->d_inode;
 932         int retval;
 933
 934         mode = inode->i_mode;
 935         /*
 936          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
 937          * generic_permission lets a non-executable through
 938          */
 939         if (!(mode & 0111))     /* with at least _one_ execute bit set */
 940                 return -EACCES;
 941         if (bprm->file->f_op == NULL)
 942                 return -EACCES;
 943
 944         bprm->e_uid = current->euid;
 945         bprm->e_gid = current->egid;
 946
 947         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
 948                 /* Set-uid? */
 949                 if (mode & S_ISUID) {
 950                         current->personality &= ~PER_CLEAR_ON_SETID;
 951                         bprm->e_uid = inode->i_uid;
 952                 }
 953
 954                 /* Set-gid? */
 955                 /*
 956                  * If setgid is set but no group execute bit then this
 957                  * is a candidate for mandatory locking, not a setgid
 958                  * executable.
 959                  */
 960                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
 961                         current->personality &= ~PER_CLEAR_ON_SETID;
 962                         bprm->e_gid = inode->i_gid;
 963                 }
 964         }
 965
 966         /* fill in binprm security blob */
 967         retval = security_bprm_set(bprm);
 968         if (retval)
 969                 return retval;
 970
 971         memset(bprm->buf,0,BINPRM_BUF_SIZE);
 972         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
 973 }
 974
 975 EXPORT_SYMBOL(prepare_binprm);
 976
 977 static inline int unsafe_exec(struct task_struct *p)
 978 {
 979         int unsafe = 0;
 980         if (p->ptrace & PT_PTRACED) {
 981                 if (p->ptrace & PT_PTRACE_CAP)
 982                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
 983                 else
 984                         unsafe |= LSM_UNSAFE_PTRACE;
 985         }
 986         if (atomic_read(&p->fs->count) > 1 ||
 987             atomic_read(&p->files->count) > 1 ||
 988             atomic_read(&p->sighand->count) > 1)
 989                 unsafe |= LSM_UNSAFE_SHARE;
 990
 991         return unsafe;
 992 }
 993
 994 void compute_creds(struct linux_binprm *bprm)
 995 {
 996         int unsafe;
 997
 998         if (bprm->e_uid != current->uid)
 999                 suid_keys(current);
1000         exec_keys(current);
1001
1002         task_lock(current);
1003         unsafe = unsafe_exec(current);
1004         security_bprm_apply_creds(bprm, unsafe);
1005         task_unlock(current);
1006         security_bprm_post_apply_creds(bprm);
1007 }
1008
1009 EXPORT_SYMBOL(compute_creds);
1010
1011 void remove_arg_zero(struct linux_binprm *bprm)
1012 {
1013         if (bprm->argc) {
1014                 unsigned long offset;
1015                 char * kaddr;
1016                 struct page *page;
1017
1018                 offset = bprm->p % PAGE_SIZE;
1019                 goto inside;
1020
1021                 while (bprm->p++, *(kaddr+offset++)) {
1022                         if (offset != PAGE_SIZE)
1023                                 continue;
1024                         offset = 0;
1025                         kunmap_atomic(kaddr, KM_USER0);
1026 inside:
1027                         page = bprm->page[bprm->p/PAGE_SIZE];
1028                         kaddr = kmap_atomic(page, KM_USER0);
1029                 }
1030                 kunmap_atomic(kaddr, KM_USER0);
1031                 bprm->argc--;
1032         }
1033 }
1034
1035 EXPORT_SYMBOL(remove_arg_zero);
1036
1037 /*
1038  * cycle the list of binary formats handler, until one recognizes the image
1039  */
1040 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1041 {
1042         int try,retval;
1043         struct linux_binfmt *fmt;
1044 #ifdef __alpha__
1045         /* handle /sbin/loader.. */
1046         {
1047             struct exec * eh = (struct exec *) bprm->buf;
1048
1049             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1050                 (eh->fh.f_flags & 0x3000) == 0x3000)
1051             {
1052                 struct file * file;
1053                 unsigned long loader;
1054
1055                 allow_write_access(bprm->file);
1056                 fput(bprm->file);
1057                 bprm->file = NULL;
1058
1059                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1060
1061                 file = open_exec("/sbin/loader");
1062                 retval = PTR_ERR(file);
1063                 if (IS_ERR(file))
1064                         return retval;
1065
1066                 /* Remember if the application is TASO.  */
1067                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1068
1069                 bprm->file = file;
1070                 bprm->loader = loader;
1071                 retval = prepare_binprm(bprm);
1072                 if (retval<0)
1073                         return retval;
1074                 /* should call search_binary_handler recursively here,
1075                    but it does not matter */
1076             }
1077         }
1078 #endif
1079         retval = security_bprm_check(bprm);
1080         if (retval)
1081                 return retval;
1082
1083         /* kernel module loader fixup */
1084         /* so we don't try to load run modprobe in kernel space. */
1085         set_fs(USER_DS);
1086         retval = -ENOENT;
1087         for (try=0; try<2; try++) {
1088                 read_lock(&binfmt_lock);
1089                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1090                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1091                         if (!fn)
1092                                 continue;
1093                         if (!try_module_get(fmt->module))
1094                                 continue;
1095                         read_unlock(&binfmt_lock);
1096                         retval = fn(bprm, regs);
1097                         if (retval >= 0) {
1098                                 put_binfmt(fmt);
1099                                 allow_write_access(bprm->file);
1100                                 if (bprm->file)
1101                                         fput(bprm->file);
1102                                 bprm->file = NULL;
1103                                 current->did_exec = 1;
1104                                 proc_exec_connector(current);
1105                                 return retval;
1106                         }
1107                         read_lock(&binfmt_lock);
1108                         put_binfmt(fmt);
1109                         if (retval != -ENOEXEC || bprm->mm == NULL)
1110                                 break;
1111                         if (!bprm->file) {
1112                                 read_unlock(&binfmt_lock);
1113                                 return retval;
1114                         }
1115                 }
1116                 read_unlock(&binfmt_lock);
1117                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1118                         break;
1119 #ifdef CONFIG_KMOD
1120                 }else{
1121 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1122                         if (printable(bprm->buf[0]) &&
1123                             printable(bprm->buf[1]) &&
1124                             printable(bprm->buf[2]) &&
1125                             printable(bprm->buf[3]))
1126                                 break; /* -ENOEXEC */
1127                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1128 #endif
1129                 }
1130         }
1131         return retval;
1132 }
1133
1134 EXPORT_SYMBOL(search_binary_handler);
1135
1136 /*
1137  * sys_execve() executes a new program.
1138  */
1139 int do_execve(char * filename,
1140         char __user *__user *argv,
1141         char __user *__user *envp,
1142         struct pt_regs * regs)
1143 {
1144         struct linux_binprm *bprm;
1145         struct file *file;
1146         int retval;
1147         int i;
1148
1149         retval = -ENOMEM;
1150         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1151         if (!bprm)
1152                 goto out_ret;
1153         memset(bprm, 0, sizeof(*bprm));
1154
1155         file = open_exec(filename);
1156         retval = PTR_ERR(file);
1157         if (IS_ERR(file))
1158                 goto out_kfree;
1159
1160         sched_exec();
1161
1162         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1163
1164         bprm->file = file;
1165         bprm->filename = filename;
1166         bprm->interp = filename;
1167         bprm->mm = mm_alloc();
1168         retval = -ENOMEM;
1169         if (!bprm->mm)
1170                 goto out_file;
1171
1172         retval = init_new_context(current, bprm->mm);
1173         if (retval < 0)
1174                 goto out_mm;
1175
1176         bprm->argc = count(argv, bprm->p / sizeof(void *));
1177         if ((retval = bprm->argc) < 0)
1178                 goto out_mm;
1179
1180         bprm->envc = count(envp, bprm->p / sizeof(void *));
1181         if ((retval = bprm->envc) < 0)
1182                 goto out_mm;
1183
1184         retval = security_bprm_alloc(bprm);
1185         if (retval)
1186                 goto out;
1187
1188         retval = prepare_binprm(bprm);
1189         if (retval < 0)
1190                 goto out;
1191
1192         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1193         if (retval < 0)
1194                 goto out;
1195
1196         bprm->exec = bprm->p;
1197         retval = copy_strings(bprm->envc, envp, bprm);
1198         if (retval < 0)
1199                 goto out;
1200
1201         retval = copy_strings(bprm->argc, argv, bprm);
1202         if (retval < 0)
1203                 goto out;
1204
1205         retval = search_binary_handler(bprm,regs);
1206         if (retval >= 0) {
1207                 free_arg_pages(bprm);
1208
1209                 /* execve success */
1210                 security_bprm_free(bprm);
1211                 acct_update_integrals(current);
1212                 kfree(bprm);
1213                 return retval;
1214         }
1215
1216 out:
1217         /* Something went wrong, return the inode and free the argument pages*/
1218         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1219                 struct page * page = bprm->page[i];
1220                 if (page)
1221                         __free_page(page);
1222         }
1223
1224         if (bprm->security)
1225                 security_bprm_free(bprm);
1226
1227 out_mm:
1228         if (bprm->mm)
1229                 mmdrop(bprm->mm);
1230
1231 out_file:
1232         if (bprm->file) {
1233                 allow_write_access(bprm->file);
1234                 fput(bprm->file);
1235         }
1236
1237 out_kfree:
1238         kfree(bprm);
1239
1240 out_ret:
1241         return retval;
1242 }
1243
1244 int set_binfmt(struct linux_binfmt *new)
1245 {
1246         struct linux_binfmt *old = current->binfmt;
1247
1248         if (new) {
1249                 if (!try_module_get(new->module))
1250                         return -1;
1251         }
1252         current->binfmt = new;
1253         if (old)
1254                 module_put(old->module);
1255         return 0;
1256 }
1257
1258 EXPORT_SYMBOL(set_binfmt);
1259
1260 #define CORENAME_MAX_SIZE 64
1261
1262 /* format_corename will inspect the pattern parameter, and output a
1263  * name into corename, which must have space for at least
1264  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1265  */
1266 static void format_corename(char *corename, const char *pattern, long signr)
1267 {
1268         const char *pat_ptr = pattern;
1269         char *out_ptr = corename;
1270         char *const out_end = corename + CORENAME_MAX_SIZE;
1271         int rc;
1272         int pid_in_pattern = 0;
1273
1274         /* Repeat as long as we have more pattern to process and more output
1275            space */
1276         while (*pat_ptr) {
1277                 if (*pat_ptr != '%') {
1278                         if (out_ptr == out_end)
1279                                 goto out;
1280                         *out_ptr++ = *pat_ptr++;
1281                 } else {
1282                         switch (*++pat_ptr) {
1283                         case 0:
1284                                 goto out;
1285                         /* Double percent, output one percent */
1286                         case '%':
1287                                 if (out_ptr == out_end)
1288                                         goto out;
1289                                 *out_ptr++ = '%';
1290                                 break;
1291                         /* pid */
1292                         case 'p':
1293                                 pid_in_pattern = 1;
1294                                 rc = snprintf(out_ptr, out_end - out_ptr,
1295                                               "%d", current->tgid);
1296                                 if (rc > out_end - out_ptr)
1297                                         goto out;
1298                                 out_ptr += rc;
1299                                 break;
1300                         /* uid */
1301                         case 'u':
1302                                 rc = snprintf(out_ptr, out_end - out_ptr,
1303                                               "%d", current->uid);
1304                                 if (rc > out_end - out_ptr)
1305                                         goto out;
1306                                 out_ptr += rc;
1307                                 break;
1308                         /* gid */
1309                         case 'g':
1310                                 rc = snprintf(out_ptr, out_end - out_ptr,
1311                                               "%d", current->gid);
1312                                 if (rc > out_end - out_ptr)
1313                                         goto out;
1314                                 out_ptr += rc;
1315                                 break;
1316                         /* signal that caused the coredump */
1317                         case 's':
1318                                 rc = snprintf(out_ptr, out_end - out_ptr,
1319                                               "%ld", signr);
1320                                 if (rc > out_end - out_ptr)
1321                                         goto out;
1322                                 out_ptr += rc;
1323                                 break;
1324                         /* UNIX time of coredump */
1325                         case 't': {
1326                                 struct timeval tv;
1327                                 do_gettimeofday(&tv);
1328                                 rc = snprintf(out_ptr, out_end - out_ptr,
1329                                               "%lu", tv.tv_sec);
1330                                 if (rc > out_end - out_ptr)
1331                                         goto out;
1332                                 out_ptr += rc;
1333                                 break;
1334                         }
1335                         /* hostname */
1336                         case 'h':
1337                                 down_read(&uts_sem);
1338                                 rc = snprintf(out_ptr, out_end - out_ptr,
1339                                               "%s", system_utsname.nodename);
1340                                 up_read(&uts_sem);
1341                                 if (rc > out_end - out_ptr)
1342                                         goto out;
1343                                 out_ptr += rc;
1344                                 break;
1345                         /* executable */
1346                         case 'e':
1347                                 rc = snprintf(out_ptr, out_end - out_ptr,
1348                                               "%s", current->comm);
1349                                 if (rc > out_end - out_ptr)
1350                                         goto out;
1351                                 out_ptr += rc;
1352                                 break;
1353                         default:
1354                                 break;
1355                         }
1356                         ++pat_ptr;
1357                 }
1358         }
1359         /* Backward compatibility with core_uses_pid:
1360          *
1361          * If core_pattern does not include a %p (as is the default)
1362          * and core_uses_pid is set, then .%pid will be appended to
1363          * the filename */
1364         if (!pid_in_pattern
1365             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1366                 rc = snprintf(out_ptr, out_end - out_ptr,
1367                               ".%d", current->tgid);
1368                 if (rc > out_end - out_ptr)
1369                         goto out;
1370                 out_ptr += rc;
1371         }
1372       out:
1373         *out_ptr = 0;
1374 }
1375
1376 static void zap_threads (struct mm_struct *mm)
1377 {
1378         struct task_struct *g, *p;
1379         struct task_struct *tsk = current;
1380         struct completion *vfork_done = tsk->vfork_done;
1381         int traced = 0;
1382
1383         /*
1384          * Make sure nobody is waiting for us to release the VM,
1385          * otherwise we can deadlock when we wait on each other
1386          */
1387         if (vfork_done) {
1388                 tsk->vfork_done = NULL;
1389                 complete(vfork_done);
1390         }
1391
1392         read_lock(&tasklist_lock);
1393         do_each_thread(g,p)
1394                 if (mm == p->mm && p != tsk) {
1395                         force_sig_specific(SIGKILL, p);
1396                         mm->core_waiters++;
1397                         if (unlikely(p->ptrace) &&
1398                             unlikely(p->parent->mm == mm))
1399                                 traced = 1;
1400                 }
1401         while_each_thread(g,p);
1402
1403         read_unlock(&tasklist_lock);
1404
1405         if (unlikely(traced)) {
1406                 /*
1407                  * We are zapping a thread and the thread it ptraces.
1408                  * If the tracee went into a ptrace stop for exit tracing,
1409                  * we could deadlock since the tracer is waiting for this
1410                  * coredump to finish.  Detach them so they can both die.
1411                  */
1412                 write_lock_irq(&tasklist_lock);
1413                 do_each_thread(g,p) {
1414                         if (mm == p->mm && p != tsk &&
1415                             p->ptrace && p->parent->mm == mm) {
1416                                 __ptrace_unlink(p);
1417                         }
1418                 } while_each_thread(g,p);
1419                 write_unlock_irq(&tasklist_lock);
1420         }
1421 }
1422
1423 static void coredump_wait(struct mm_struct *mm)
1424 {
1425         DECLARE_COMPLETION(startup_done);
1426         int core_waiters;
1427
1428         mm->core_startup_done = &startup_done;
1429
1430         zap_threads(mm);
1431         core_waiters = mm->core_waiters;
1432         up_write(&mm->mmap_sem);
1433
1434         if (core_waiters)
1435                 wait_for_completion(&startup_done);
1436         BUG_ON(mm->core_waiters);
1437 }
1438
1439 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1440 {
1441         char corename[CORENAME_MAX_SIZE + 1];
1442         struct mm_struct *mm = current->mm;
1443         struct linux_binfmt * binfmt;
1444         struct inode * inode;
1445         struct file * file;
1446         int retval = 0;
1447         int fsuid = current->fsuid;
1448         int flag = 0;
1449
1450         binfmt = current->binfmt;
1451         if (!binfmt || !binfmt->core_dump)
1452                 goto fail;
1453         down_write(&mm->mmap_sem);
1454         if (!mm->dumpable) {
1455                 up_write(&mm->mmap_sem);
1456                 goto fail;
1457         }
1458
1459         /*
1460          *      We cannot trust fsuid as being the "true" uid of the
1461          *      process nor do we know its entire history. We only know it
1462          *      was tainted so we dump it as root in mode 2.
1463          */
1464         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1465                 flag = O_EXCL;          /* Stop rewrite attacks */
1466                 current->fsuid = 0;     /* Dump root private */
1467         }
1468         mm->dumpable = 0;
1469
1470         retval = -EAGAIN;
1471         spin_lock_irq(&current->sighand->siglock);
1472         if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
1473                 current->signal->flags = SIGNAL_GROUP_EXIT;
1474                 current->signal->group_exit_code = exit_code;
1475                 retval = 0;
1476         }
1477         spin_unlock_irq(&current->sighand->siglock);
1478         if (retval) {
1479                 up_write(&mm->mmap_sem);
1480                 goto fail;
1481         }
1482
1483         init_completion(&mm->core_done);
1484         coredump_wait(mm);
1485
1486         /*
1487          * Clear any false indication of pending signals that might
1488          * be seen by the filesystem code called to write the core file.
1489          */
1490         current->signal->group_stop_count = 0;
1491         clear_thread_flag(TIF_SIGPENDING);
1492
1493         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1494                 goto fail_unlock;
1495
1496         /*
1497          * lock_kernel() because format_corename() is controlled by sysctl, which
1498          * uses lock_kernel()
1499          */
1500         lock_kernel();
1501         format_corename(corename, core_pattern, signr);
1502         unlock_kernel();
1503         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1504         if (IS_ERR(file))
1505                 goto fail_unlock;
1506         inode = file->f_dentry->d_inode;
1507         if (inode->i_nlink > 1)
1508                 goto close_fail;        /* multiple links - don't dump */
1509         if (d_unhashed(file->f_dentry))
1510                 goto close_fail;
1511
1512         if (!S_ISREG(inode->i_mode))
1513                 goto close_fail;
1514         if (!file->f_op)
1515                 goto close_fail;
1516         if (!file->f_op->write)
1517                 goto close_fail;
1518         if (do_truncate(file->f_dentry, 0, file) != 0)
1519                 goto close_fail;
1520
1521         retval = binfmt->core_dump(signr, regs, file);
1522
1523         if (retval)
1524                 current->signal->group_exit_code |= 0x80;
1525 close_fail:
1526         filp_close(file, NULL);
1527 fail_unlock:
1528         current->fsuid = fsuid;
1529         complete_all(&mm->core_done);
1530 fail:
1531         return retval;
1532 }