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   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/slab.h>
  26 #include <linux/file.h>
  27 #include <linux/mman.h>
  28 #include <linux/a.out.h>
  29 #include <linux/stat.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/smp_lock.h>
  32 #include <linux/init.h>
  33 #include <linux/pagemap.h>
  34 #include <linux/highmem.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/key.h>
  37 #include <linux/personality.h>
  38 #include <linux/binfmts.h>
  39 #include <linux/swap.h>
  40 #include <linux/utsname.h>
  41 #include <linux/pid_namespace.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/tsacct_kern.h>
  51 #include <linux/cn_proc.h>
  52 #include <linux/audit.h>
  53
  54 #include <asm/uaccess.h>
  55 #include <asm/mmu_context.h>
  56 #include <asm/tlb.h>
  57
  58 #ifdef CONFIG_KMOD
  59 #include <linux/kmod.h>
  60 #endif
  61
  62 int core_uses_pid;
  63 char core_pattern[CORENAME_MAX_SIZE] = "core";
  64 int suid_dumpable = 0;
  65
  66 EXPORT_SYMBOL(suid_dumpable);
  67 /* The maximal length of core_pattern is also specified in sysctl.c */
  68
  69 static LIST_HEAD(formats);
  70 static DEFINE_RWLOCK(binfmt_lock);
  71
  72 int register_binfmt(struct linux_binfmt * fmt)
  73 {
  74         if (!fmt)
  75                 return -EINVAL;
  76         write_lock(&binfmt_lock);
  77         list_add(&fmt->lh, &formats);
  78         write_unlock(&binfmt_lock);
  79         return 0;
  80 }
  81
  82 EXPORT_SYMBOL(register_binfmt);
  83
  84 int unregister_binfmt(struct linux_binfmt * fmt)
  85 {
  86         write_lock(&binfmt_lock);
  87         list_del(&fmt->lh);
  88         write_unlock(&binfmt_lock);
  89         return 0;
  90 }
  91
  92 EXPORT_SYMBOL(unregister_binfmt);
  93
  94 static inline void put_binfmt(struct linux_binfmt * fmt)
  95 {
  96         module_put(fmt->module);
  97 }
  98
  99 /*
 100  * Note that a shared library must be both readable and executable due to
 101  * security reasons.
 102  *
 103  * Also note that we take the address to load from from the file itself.
 104  */
 105 asmlinkage long sys_uselib(const char __user * library)
 106 {
 107         struct file * file;
 108         struct nameidata nd;
 109         int error;
 110
 111         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 112         if (error)
 113                 goto out;
 114
 115         error = -EACCES;
 116         if (nd.mnt->mnt_flags & MNT_NOEXEC)
 117                 goto exit;
 118         error = -EINVAL;
 119         if (!S_ISREG(nd.dentry->d_inode->i_mode))
 120                 goto exit;
 121
 122         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
 123         if (error)
 124                 goto exit;
 125
 126         file = nameidata_to_filp(&nd, O_RDONLY);
 127         error = PTR_ERR(file);
 128         if (IS_ERR(file))
 129                 goto out;
 130
 131         error = -ENOEXEC;
 132         if(file->f_op) {
 133                 struct linux_binfmt * fmt;
 134
 135                 read_lock(&binfmt_lock);
 136                 list_for_each_entry(fmt, &formats, lh) {
 137                         if (!fmt->load_shlib)
 138                                 continue;
 139                         if (!try_module_get(fmt->module))
 140                                 continue;
 141                         read_unlock(&binfmt_lock);
 142                         error = fmt->load_shlib(file);
 143                         read_lock(&binfmt_lock);
 144                         put_binfmt(fmt);
 145                         if (error != -ENOEXEC)
 146                                 break;
 147                 }
 148                 read_unlock(&binfmt_lock);
 149         }
 150         fput(file);
 151 out:
 152         return error;
 153 exit:
 154         release_open_intent(&nd);
 155         path_release(&nd);
 156         goto out;
 157 }
 158
 159 #ifdef CONFIG_MMU
 160
 161 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 162                 int write)
 163 {
 164         struct page *page;
 165         int ret;
 166
 167 #ifdef CONFIG_STACK_GROWSUP
 168         if (write) {
 169                 ret = expand_stack_downwards(bprm->vma, pos);
 170                 if (ret < 0)
 171                         return NULL;
 172         }
 173 #endif
 174         ret = get_user_pages(current, bprm->mm, pos,
 175                         1, write, 1, &page, NULL);
 176         if (ret <= 0)
 177                 return NULL;
 178
 179         if (write) {
 180                 struct rlimit *rlim = current->signal->rlim;
 181                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 182
 183                 /*
 184                  * Limit to 1/4-th the stack size for the argv+env strings.
 185                  * This ensures that:
 186                  *  - the remaining binfmt code will not run out of stack space,
 187                  *  - the program will have a reasonable amount of stack left
 188                  *    to work from.
 189                  */
 190                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 191                         put_page(page);
 192                         return NULL;
 193                 }
 194         }
 195
 196         return page;
 197 }
 198
 199 static void put_arg_page(struct page *page)
 200 {
 201         put_page(page);
 202 }
 203
 204 static void free_arg_page(struct linux_binprm *bprm, int i)
 205 {
 206 }
 207
 208 static void free_arg_pages(struct linux_binprm *bprm)
 209 {
 210 }
 211
 212 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 213                 struct page *page)
 214 {
 215         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 216 }
 217
 218 static int __bprm_mm_init(struct linux_binprm *bprm)
 219 {
 220         int err = -ENOMEM;
 221         struct vm_area_struct *vma = NULL;
 222         struct mm_struct *mm = bprm->mm;
 223
 224         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 225         if (!vma)
 226                 goto err;
 227
 228         down_write(&mm->mmap_sem);
 229         vma->vm_mm = mm;
 230
 231         /*
 232          * Place the stack at the largest stack address the architecture
 233          * supports. Later, we'll move this to an appropriate place. We don't
 234          * use STACK_TOP because that can depend on attributes which aren't
 235          * configured yet.
 236          */
 237         vma->vm_end = STACK_TOP_MAX;
 238         vma->vm_start = vma->vm_end - PAGE_SIZE;
 239
 240         vma->vm_flags = VM_STACK_FLAGS;
 241         vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
 242         err = insert_vm_struct(mm, vma);
 243         if (err) {
 244                 up_write(&mm->mmap_sem);
 245                 goto err;
 246         }
 247
 248         mm->stack_vm = mm->total_vm = 1;
 249         up_write(&mm->mmap_sem);
 250
 251         bprm->p = vma->vm_end - sizeof(void *);
 252
 253         return 0;
 254
 255 err:
 256         if (vma) {
 257                 bprm->vma = NULL;
 258                 kmem_cache_free(vm_area_cachep, vma);
 259         }
 260
 261         return err;
 262 }
 263
 264 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 265 {
 266         return len <= MAX_ARG_STRLEN;
 267 }
 268
 269 #else
 270
 271 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 272                 int write)
 273 {
 274         struct page *page;
 275
 276         page = bprm->page[pos / PAGE_SIZE];
 277         if (!page && write) {
 278                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 279                 if (!page)
 280                         return NULL;
 281                 bprm->page[pos / PAGE_SIZE] = page;
 282         }
 283
 284         return page;
 285 }
 286
 287 static void put_arg_page(struct page *page)
 288 {
 289 }
 290
 291 static void free_arg_page(struct linux_binprm *bprm, int i)
 292 {
 293         if (bprm->page[i]) {
 294                 __free_page(bprm->page[i]);
 295                 bprm->page[i] = NULL;
 296         }
 297 }
 298
 299 static void free_arg_pages(struct linux_binprm *bprm)
 300 {
 301         int i;
 302
 303         for (i = 0; i < MAX_ARG_PAGES; i++)
 304                 free_arg_page(bprm, i);
 305 }
 306
 307 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 308                 struct page *page)
 309 {
 310 }
 311
 312 static int __bprm_mm_init(struct linux_binprm *bprm)
 313 {
 314         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 315         return 0;
 316 }
 317
 318 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 319 {
 320         return len <= bprm->p;
 321 }
 322
 323 #endif /* CONFIG_MMU */
 324
 325 /*
 326  * Create a new mm_struct and populate it with a temporary stack
 327  * vm_area_struct.  We don't have enough context at this point to set the stack
 328  * flags, permissions, and offset, so we use temporary values.  We'll update
 329  * them later in setup_arg_pages().
 330  */
 331 int bprm_mm_init(struct linux_binprm *bprm)
 332 {
 333         int err;
 334         struct mm_struct *mm = NULL;
 335
 336         bprm->mm = mm = mm_alloc();
 337         err = -ENOMEM;
 338         if (!mm)
 339                 goto err;
 340
 341         err = init_new_context(current, mm);
 342         if (err)
 343                 goto err;
 344
 345         err = __bprm_mm_init(bprm);
 346         if (err)
 347                 goto err;
 348
 349         return 0;
 350
 351 err:
 352         if (mm) {
 353                 bprm->mm = NULL;
 354                 mmdrop(mm);
 355         }
 356
 357         return err;
 358 }
 359
 360 /*
 361  * count() counts the number of strings in array ARGV.
 362  */
 363 static int count(char __user * __user * argv, int max)
 364 {
 365         int i = 0;
 366
 367         if (argv != NULL) {
 368                 for (;;) {
 369                         char __user * p;
 370
 371                         if (get_user(p, argv))
 372                                 return -EFAULT;
 373                         if (!p)
 374                                 break;
 375                         argv++;
 376                         if(++i > max)
 377                                 return -E2BIG;
 378                         cond_resched();
 379                 }
 380         }
 381         return i;
 382 }
 383
 384 /*
 385  * 'copy_strings()' copies argument/environment strings from the old
 386  * processes's memory to the new process's stack.  The call to get_user_pages()
 387  * ensures the destination page is created and not swapped out.
 388  */
 389 static int copy_strings(int argc, char __user * __user * argv,
 390                         struct linux_binprm *bprm)
 391 {
 392         struct page *kmapped_page = NULL;
 393         char *kaddr = NULL;
 394         unsigned long kpos = 0;
 395         int ret;
 396
 397         while (argc-- > 0) {
 398                 char __user *str;
 399                 int len;
 400                 unsigned long pos;
 401
 402                 if (get_user(str, argv+argc) ||
 403                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 404                         ret = -EFAULT;
 405                         goto out;
 406                 }
 407
 408                 if (!valid_arg_len(bprm, len)) {
 409                         ret = -E2BIG;
 410                         goto out;
 411                 }
 412
 413                 /* We're going to work our way backwords. */
 414                 pos = bprm->p;
 415                 str += len;
 416                 bprm->p -= len;
 417
 418                 while (len > 0) {
 419                         int offset, bytes_to_copy;
 420
 421                         offset = pos % PAGE_SIZE;
 422                         if (offset == 0)
 423                                 offset = PAGE_SIZE;
 424
 425                         bytes_to_copy = offset;
 426                         if (bytes_to_copy > len)
 427                                 bytes_to_copy = len;
 428
 429                         offset -= bytes_to_copy;
 430                         pos -= bytes_to_copy;
 431                         str -= bytes_to_copy;
 432                         len -= bytes_to_copy;
 433
 434                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 435                                 struct page *page;
 436
 437                                 page = get_arg_page(bprm, pos, 1);
 438                                 if (!page) {
 439                                         ret = -E2BIG;
 440                                         goto out;
 441                                 }
 442
 443                                 if (kmapped_page) {
 444                                         flush_kernel_dcache_page(kmapped_page);
 445                                         kunmap(kmapped_page);
 446                                         put_arg_page(kmapped_page);
 447                                 }
 448                                 kmapped_page = page;
 449                                 kaddr = kmap(kmapped_page);
 450                                 kpos = pos & PAGE_MASK;
 451                                 flush_arg_page(bprm, kpos, kmapped_page);
 452                         }
 453                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 454                                 ret = -EFAULT;
 455                                 goto out;
 456                         }
 457                 }
 458         }
 459         ret = 0;
 460 out:
 461         if (kmapped_page) {
 462                 flush_kernel_dcache_page(kmapped_page);
 463                 kunmap(kmapped_page);
 464                 put_arg_page(kmapped_page);
 465         }
 466         return ret;
 467 }
 468
 469 /*
 470  * Like copy_strings, but get argv and its values from kernel memory.
 471  */
 472 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 473 {
 474         int r;
 475         mm_segment_t oldfs = get_fs();
 476         set_fs(KERNEL_DS);
 477         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 478         set_fs(oldfs);
 479         return r;
 480 }
 481 EXPORT_SYMBOL(copy_strings_kernel);
 482
 483 #ifdef CONFIG_MMU
 484
 485 /*
 486  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 487  * the binfmt code determines where the new stack should reside, we shift it to
 488  * its final location.  The process proceeds as follows:
 489  *
 490  * 1) Use shift to calculate the new vma endpoints.
 491  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 492  *    arguments passed to subsequent functions are consistent.
 493  * 3) Move vma's page tables to the new range.
 494  * 4) Free up any cleared pgd range.
 495  * 5) Shrink the vma to cover only the new range.
 496  */
 497 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 498 {
 499         struct mm_struct *mm = vma->vm_mm;
 500         unsigned long old_start = vma->vm_start;
 501         unsigned long old_end = vma->vm_end;
 502         unsigned long length = old_end - old_start;
 503         unsigned long new_start = old_start - shift;
 504         unsigned long new_end = old_end - shift;
 505         struct mmu_gather *tlb;
 506
 507         BUG_ON(new_start > new_end);
 508
 509         /*
 510          * ensure there are no vmas between where we want to go
 511          * and where we are
 512          */
 513         if (vma != find_vma(mm, new_start))
 514                 return -EFAULT;
 515
 516         /*
 517          * cover the whole range: [new_start, old_end)
 518          */
 519         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 520
 521         /*
 522          * move the page tables downwards, on failure we rely on
 523          * process cleanup to remove whatever mess we made.
 524          */
 525         if (length != move_page_tables(vma, old_start,
 526                                        vma, new_start, length))
 527                 return -ENOMEM;
 528
 529         lru_add_drain();
 530         tlb = tlb_gather_mmu(mm, 0);
 531         if (new_end > old_start) {
 532                 /*
 533                  * when the old and new regions overlap clear from new_end.
 534                  */
 535                 free_pgd_range(&tlb, new_end, old_end, new_end,
 536                         vma->vm_next ? vma->vm_next->vm_start : 0);
 537         } else {
 538                 /*
 539                  * otherwise, clean from old_start; this is done to not touch
 540                  * the address space in [new_end, old_start) some architectures
 541                  * have constraints on va-space that make this illegal (IA64) -
 542                  * for the others its just a little faster.
 543                  */
 544                 free_pgd_range(&tlb, old_start, old_end, new_end,
 545                         vma->vm_next ? vma->vm_next->vm_start : 0);
 546         }
 547         tlb_finish_mmu(tlb, new_end, old_end);
 548
 549         /*
 550          * shrink the vma to just the new range.
 551          */
 552         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 553
 554         return 0;
 555 }
 556
 557 #define EXTRA_STACK_VM_PAGES    20      /* random */
 558
 559 /*
 560  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 561  * the stack is optionally relocated, and some extra space is added.
 562  */
 563 int setup_arg_pages(struct linux_binprm *bprm,
 564                     unsigned long stack_top,
 565                     int executable_stack)
 566 {
 567         unsigned long ret;
 568         unsigned long stack_shift;
 569         struct mm_struct *mm = current->mm;
 570         struct vm_area_struct *vma = bprm->vma;
 571         struct vm_area_struct *prev = NULL;
 572         unsigned long vm_flags;
 573         unsigned long stack_base;
 574
 575 #ifdef CONFIG_STACK_GROWSUP
 576         /* Limit stack size to 1GB */
 577         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 578         if (stack_base > (1 << 30))
 579                 stack_base = 1 << 30;
 580
 581         /* Make sure we didn't let the argument array grow too large. */
 582         if (vma->vm_end - vma->vm_start > stack_base)
 583                 return -ENOMEM;
 584
 585         stack_base = PAGE_ALIGN(stack_top - stack_base);
 586
 587         stack_shift = vma->vm_start - stack_base;
 588         mm->arg_start = bprm->p - stack_shift;
 589         bprm->p = vma->vm_end - stack_shift;
 590 #else
 591         stack_top = arch_align_stack(stack_top);
 592         stack_top = PAGE_ALIGN(stack_top);
 593         stack_shift = vma->vm_end - stack_top;
 594
 595         bprm->p -= stack_shift;
 596         mm->arg_start = bprm->p;
 597 #endif
 598
 599         if (bprm->loader)
 600                 bprm->loader -= stack_shift;
 601         bprm->exec -= stack_shift;
 602
 603         down_write(&mm->mmap_sem);
 604         vm_flags = vma->vm_flags;
 605
 606         /*
 607          * Adjust stack execute permissions; explicitly enable for
 608          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 609          * (arch default) otherwise.
 610          */
 611         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 612                 vm_flags |= VM_EXEC;
 613         else if (executable_stack == EXSTACK_DISABLE_X)
 614                 vm_flags &= ~VM_EXEC;
 615         vm_flags |= mm->def_flags;
 616
 617         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 618                         vm_flags);
 619         if (ret)
 620                 goto out_unlock;
 621         BUG_ON(prev != vma);
 622
 623         /* Move stack pages down in memory. */
 624         if (stack_shift) {
 625                 ret = shift_arg_pages(vma, stack_shift);
 626                 if (ret) {
 627                         up_write(&mm->mmap_sem);
 628                         return ret;
 629                 }
 630         }
 631
 632 #ifdef CONFIG_STACK_GROWSUP
 633         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 634 #else
 635         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 636 #endif
 637         ret = expand_stack(vma, stack_base);
 638         if (ret)
 639                 ret = -EFAULT;
 640
 641 out_unlock:
 642         up_write(&mm->mmap_sem);
 643         return 0;
 644 }
 645 EXPORT_SYMBOL(setup_arg_pages);
 646
 647 #endif /* CONFIG_MMU */
 648
 649 struct file *open_exec(const char *name)
 650 {
 651         struct nameidata nd;
 652         int err;
 653         struct file *file;
 654
 655         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 656         file = ERR_PTR(err);
 657
 658         if (!err) {
 659                 struct inode *inode = nd.dentry->d_inode;
 660                 file = ERR_PTR(-EACCES);
 661                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
 662                     S_ISREG(inode->i_mode)) {
 663                         int err = vfs_permission(&nd, MAY_EXEC);
 664                         file = ERR_PTR(err);
 665                         if (!err) {
 666                                 file = nameidata_to_filp(&nd, O_RDONLY);
 667                                 if (!IS_ERR(file)) {
 668                                         err = deny_write_access(file);
 669                                         if (err) {
 670                                                 fput(file);
 671                                                 file = ERR_PTR(err);
 672                                         }
 673                                 }
 674 out:
 675                                 return file;
 676                         }
 677                 }
 678                 release_open_intent(&nd);
 679                 path_release(&nd);
 680         }
 681         goto out;
 682 }
 683
 684 EXPORT_SYMBOL(open_exec);
 685
 686 int kernel_read(struct file *file, unsigned long offset,
 687         char *addr, unsigned long count)
 688 {
 689         mm_segment_t old_fs;
 690         loff_t pos = offset;
 691         int result;
 692
 693         old_fs = get_fs();
 694         set_fs(get_ds());
 695         /* The cast to a user pointer is valid due to the set_fs() */
 696         result = vfs_read(file, (void __user *)addr, count, &pos);
 697         set_fs(old_fs);
 698         return result;
 699 }
 700
 701 EXPORT_SYMBOL(kernel_read);
 702
 703 static int exec_mmap(struct mm_struct *mm)
 704 {
 705         struct task_struct *tsk;
 706         struct mm_struct * old_mm, *active_mm;
 707
 708         /* Notify parent that we're no longer interested in the old VM */
 709         tsk = current;
 710         old_mm = current->mm;
 711         mm_release(tsk, old_mm);
 712
 713         if (old_mm) {
 714                 /*
 715                  * Make sure that if there is a core dump in progress
 716                  * for the old mm, we get out and die instead of going
 717                  * through with the exec.  We must hold mmap_sem around
 718                  * checking core_waiters and changing tsk->mm.  The
 719                  * core-inducing thread will increment core_waiters for
 720                  * each thread whose ->mm == old_mm.
 721                  */
 722                 down_read(&old_mm->mmap_sem);
 723                 if (unlikely(old_mm->core_waiters)) {
 724                         up_read(&old_mm->mmap_sem);
 725                         return -EINTR;
 726                 }
 727         }
 728         task_lock(tsk);
 729         active_mm = tsk->active_mm;
 730         tsk->mm = mm;
 731         tsk->active_mm = mm;
 732         activate_mm(active_mm, mm);
 733         task_unlock(tsk);
 734         arch_pick_mmap_layout(mm);
 735         if (old_mm) {
 736                 up_read(&old_mm->mmap_sem);
 737                 BUG_ON(active_mm != old_mm);
 738                 mmput(old_mm);
 739                 return 0;
 740         }
 741         mmdrop(active_mm);
 742         return 0;
 743 }
 744
 745 /*
 746  * This function makes sure the current process has its own signal table,
 747  * so that flush_signal_handlers can later reset the handlers without
 748  * disturbing other processes.  (Other processes might share the signal
 749  * table via the CLONE_SIGHAND option to clone().)
 750  */
 751 static int de_thread(struct task_struct *tsk)
 752 {
 753         struct signal_struct *sig = tsk->signal;
 754         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
 755         spinlock_t *lock = &oldsighand->siglock;
 756         struct task_struct *leader = NULL;
 757         int count;
 758
 759         /*
 760          * If we don't share sighandlers, then we aren't sharing anything
 761          * and we can just re-use it all.
 762          */
 763         if (atomic_read(&oldsighand->count) <= 1) {
 764                 exit_itimers(sig);
 765                 return 0;
 766         }
 767
 768         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 769         if (!newsighand)
 770                 return -ENOMEM;
 771
 772         if (thread_group_empty(tsk))
 773                 goto no_thread_group;
 774
 775         /*
 776          * Kill all other threads in the thread group.
 777          * We must hold tasklist_lock to call zap_other_threads.
 778          */
 779         read_lock(&tasklist_lock);
 780         spin_lock_irq(lock);
 781         if (sig->flags & SIGNAL_GROUP_EXIT) {
 782                 /*
 783                  * Another group action in progress, just
 784                  * return so that the signal is processed.
 785                  */
 786                 spin_unlock_irq(lock);
 787                 read_unlock(&tasklist_lock);
 788                 kmem_cache_free(sighand_cachep, newsighand);
 789                 return -EAGAIN;
 790         }
 791
 792         /*
 793          * child_reaper ignores SIGKILL, change it now.
 794          * Reparenting needs write_lock on tasklist_lock,
 795          * so it is safe to do it under read_lock.
 796          */
 797         if (unlikely(tsk->group_leader == child_reaper(tsk)))
 798                 tsk->nsproxy->pid_ns->child_reaper = tsk;
 799
 800         zap_other_threads(tsk);
 801         read_unlock(&tasklist_lock);
 802
 803         /*
 804          * Account for the thread group leader hanging around:
 805          */
 806         count = 1;
 807         if (!thread_group_leader(tsk)) {
 808                 count = 2;
 809                 /*
 810                  * The SIGALRM timer survives the exec, but needs to point
 811                  * at us as the new group leader now.  We have a race with
 812                  * a timer firing now getting the old leader, so we need to
 813                  * synchronize with any firing (by calling del_timer_sync)
 814                  * before we can safely let the old group leader die.
 815                  */
 816                 sig->tsk = tsk;
 817                 spin_unlock_irq(lock);
 818                 if (hrtimer_cancel(&sig->real_timer))
 819                         hrtimer_restart(&sig->real_timer);
 820                 spin_lock_irq(lock);
 821         }
 822         while (atomic_read(&sig->count) > count) {
 823                 sig->group_exit_task = tsk;
 824                 sig->notify_count = count;
 825                 __set_current_state(TASK_UNINTERRUPTIBLE);
 826                 spin_unlock_irq(lock);
 827                 schedule();
 828                 spin_lock_irq(lock);
 829         }
 830         sig->group_exit_task = NULL;
 831         sig->notify_count = 0;
 832         spin_unlock_irq(lock);
 833
 834         /*
 835          * At this point all other threads have exited, all we have to
 836          * do is to wait for the thread group leader to become inactive,
 837          * and to assume its PID:
 838          */
 839         if (!thread_group_leader(tsk)) {
 840                 /*
 841                  * Wait for the thread group leader to be a zombie.
 842                  * It should already be zombie at this point, most
 843                  * of the time.
 844                  */
 845                 leader = tsk->group_leader;
 846                 while (leader->exit_state != EXIT_ZOMBIE)
 847                         yield();
 848
 849                 /*
 850                  * The only record we have of the real-time age of a
 851                  * process, regardless of execs it's done, is start_time.
 852                  * All the past CPU time is accumulated in signal_struct
 853                  * from sister threads now dead.  But in this non-leader
 854                  * exec, nothing survives from the original leader thread,
 855                  * whose birth marks the true age of this process now.
 856                  * When we take on its identity by switching to its PID, we
 857                  * also take its birthdate (always earlier than our own).
 858                  */
 859                 tsk->start_time = leader->start_time;
 860
 861                 write_lock_irq(&tasklist_lock);
 862
 863                 BUG_ON(leader->tgid != tsk->tgid);
 864                 BUG_ON(tsk->pid == tsk->tgid);
 865                 /*
 866                  * An exec() starts a new thread group with the
 867                  * TGID of the previous thread group. Rehash the
 868                  * two threads with a switched PID, and release
 869                  * the former thread group leader:
 870                  */
 871
 872                 /* Become a process group leader with the old leader's pid.
 873                  * The old leader becomes a thread of the this thread group.
 874                  * Note: The old leader also uses this pid until release_task
 875                  *       is called.  Odd but simple and correct.
 876                  */
 877                 detach_pid(tsk, PIDTYPE_PID);
 878                 tsk->pid = leader->pid;
 879                 attach_pid(tsk, PIDTYPE_PID,  find_pid(tsk->pid));
 880                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 881                 transfer_pid(leader, tsk, PIDTYPE_SID);
 882                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 883
 884                 tsk->group_leader = tsk;
 885                 leader->group_leader = tsk;
 886
 887                 tsk->exit_signal = SIGCHLD;
 888
 889                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 890                 leader->exit_state = EXIT_DEAD;
 891
 892                 write_unlock_irq(&tasklist_lock);
 893         }
 894
 895         /*
 896          * There may be one thread left which is just exiting,
 897          * but it's safe to stop telling the group to kill themselves.
 898          */
 899         sig->flags = 0;
 900
 901 no_thread_group:
 902         exit_itimers(sig);
 903         if (leader)
 904                 release_task(leader);
 905
 906         if (atomic_read(&oldsighand->count) == 1) {
 907                 /*
 908                  * Now that we nuked the rest of the thread group,
 909                  * it turns out we are not sharing sighand any more either.
 910                  * So we can just keep it.
 911                  */
 912                 kmem_cache_free(sighand_cachep, newsighand);
 913         } else {
 914                 /*
 915                  * Move our state over to newsighand and switch it in.
 916                  */
 917                 atomic_set(&newsighand->count, 1);
 918                 memcpy(newsighand->action, oldsighand->action,
 919                        sizeof(newsighand->action));
 920
 921                 write_lock_irq(&tasklist_lock);
 922                 spin_lock(&oldsighand->siglock);
 923                 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
 924
 925                 rcu_assign_pointer(tsk->sighand, newsighand);
 926                 recalc_sigpending();
 927
 928                 spin_unlock(&newsighand->siglock);
 929                 spin_unlock(&oldsighand->siglock);
 930                 write_unlock_irq(&tasklist_lock);
 931
 932                 __cleanup_sighand(oldsighand);
 933         }
 934
 935         BUG_ON(!thread_group_leader(tsk));
 936         return 0;
 937 }
 938
 939 /*
 940  * These functions flushes out all traces of the currently running executable
 941  * so that a new one can be started
 942  */
 943
 944 static void flush_old_files(struct files_struct * files)
 945 {
 946         long j = -1;
 947         struct fdtable *fdt;
 948
 949         spin_lock(&files->file_lock);
 950         for (;;) {
 951                 unsigned long set, i;
 952
 953                 j++;
 954                 i = j * __NFDBITS;
 955                 fdt = files_fdtable(files);
 956                 if (i >= fdt->max_fds)
 957                         break;
 958                 set = fdt->close_on_exec->fds_bits[j];
 959                 if (!set)
 960                         continue;
 961                 fdt->close_on_exec->fds_bits[j] = 0;
 962                 spin_unlock(&files->file_lock);
 963                 for ( ; set ; i++,set >>= 1) {
 964                         if (set & 1) {
 965                                 sys_close(i);
 966                         }
 967                 }
 968                 spin_lock(&files->file_lock);
 969
 970         }
 971         spin_unlock(&files->file_lock);
 972 }
 973
 974 void get_task_comm(char *buf, struct task_struct *tsk)
 975 {
 976         /* buf must be at least sizeof(tsk->comm) in size */
 977         task_lock(tsk);
 978         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 979         task_unlock(tsk);
 980 }
 981
 982 void set_task_comm(struct task_struct *tsk, char *buf)
 983 {
 984         task_lock(tsk);
 985         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 986         task_unlock(tsk);
 987 }
 988
 989 int flush_old_exec(struct linux_binprm * bprm)
 990 {
 991         char * name;
 992         int i, ch, retval;
 993         struct files_struct *files;
 994         char tcomm[sizeof(current->comm)];
 995
 996         /*
 997          * Make sure we have a private signal table and that
 998          * we are unassociated from the previous thread group.
 999          */
1000         retval = de_thread(current);
1001         if (retval)
1002                 goto out;
1003
1004         /*
1005          * Make sure we have private file handles. Ask the
1006          * fork helper to do the work for us and the exit
1007          * helper to do the cleanup of the old one.
1008          */
1009         files = current->files;         /* refcounted so safe to hold */
1010         retval = unshare_files();
1011         if (retval)
1012                 goto out;
1013         /*
1014          * Release all of the old mmap stuff
1015          */
1016         retval = exec_mmap(bprm->mm);
1017         if (retval)
1018                 goto mmap_failed;
1019
1020         bprm->mm = NULL;                /* We're using it now */
1021
1022         /* This is the point of no return */
1023         put_files_struct(files);
1024
1025         current->sas_ss_sp = current->sas_ss_size = 0;
1026
1027         if (current->euid == current->uid && current->egid == current->gid)
1028                 set_dumpable(current->mm, 1);
1029         else
1030                 set_dumpable(current->mm, suid_dumpable);
1031
1032         name = bprm->filename;
1033
1034         /* Copies the binary name from after last slash */
1035         for (i=0; (ch = *(name++)) != '\0';) {
1036                 if (ch == '/')
1037                         i = 0; /* overwrite what we wrote */
1038                 else
1039                         if (i < (sizeof(tcomm) - 1))
1040                                 tcomm[i++] = ch;
1041         }
1042         tcomm[i] = '\0';
1043         set_task_comm(current, tcomm);
1044
1045         current->flags &= ~PF_RANDOMIZE;
1046         flush_thread();
1047
1048         /* Set the new mm task size. We have to do that late because it may
1049          * depend on TIF_32BIT which is only updated in flush_thread() on
1050          * some architectures like powerpc
1051          */
1052         current->mm->task_size = TASK_SIZE;
1053
1054         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1055                 suid_keys(current);
1056                 set_dumpable(current->mm, suid_dumpable);
1057                 current->pdeath_signal = 0;
1058         } else if (file_permission(bprm->file, MAY_READ) ||
1059                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1060                 suid_keys(current);
1061                 set_dumpable(current->mm, suid_dumpable);
1062         }
1063
1064         /* An exec changes our domain. We are no longer part of the thread
1065            group */
1066
1067         current->self_exec_id++;
1068
1069         flush_signal_handlers(current, 0);
1070         flush_old_files(current->files);
1071
1072         return 0;
1073
1074 mmap_failed:
1075         reset_files_struct(current, files);
1076 out:
1077         return retval;
1078 }
1079
1080 EXPORT_SYMBOL(flush_old_exec);
1081
1082 /*
1083  * Fill the binprm structure from the inode.
1084  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1085  */
1086 int prepare_binprm(struct linux_binprm *bprm)
1087 {
1088         int mode;
1089         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1090         int retval;
1091
1092         mode = inode->i_mode;
1093         if (bprm->file->f_op == NULL)
1094                 return -EACCES;
1095
1096         bprm->e_uid = current->euid;
1097         bprm->e_gid = current->egid;
1098
1099         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1100                 /* Set-uid? */
1101                 if (mode & S_ISUID) {
1102                         current->personality &= ~PER_CLEAR_ON_SETID;
1103                         bprm->e_uid = inode->i_uid;
1104                 }
1105
1106                 /* Set-gid? */
1107                 /*
1108                  * If setgid is set but no group execute bit then this
1109                  * is a candidate for mandatory locking, not a setgid
1110                  * executable.
1111                  */
1112                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1113                         current->personality &= ~PER_CLEAR_ON_SETID;
1114                         bprm->e_gid = inode->i_gid;
1115                 }
1116         }
1117
1118         /* fill in binprm security blob */
1119         retval = security_bprm_set(bprm);
1120         if (retval)
1121                 return retval;
1122
1123         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1124         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1125 }
1126
1127 EXPORT_SYMBOL(prepare_binprm);
1128
1129 static int unsafe_exec(struct task_struct *p)
1130 {
1131         int unsafe = 0;
1132         if (p->ptrace & PT_PTRACED) {
1133                 if (p->ptrace & PT_PTRACE_CAP)
1134                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
1135                 else
1136                         unsafe |= LSM_UNSAFE_PTRACE;
1137         }
1138         if (atomic_read(&p->fs->count) > 1 ||
1139             atomic_read(&p->files->count) > 1 ||
1140             atomic_read(&p->sighand->count) > 1)
1141                 unsafe |= LSM_UNSAFE_SHARE;
1142
1143         return unsafe;
1144 }
1145
1146 void compute_creds(struct linux_binprm *bprm)
1147 {
1148         int unsafe;
1149
1150         if (bprm->e_uid != current->uid) {
1151                 suid_keys(current);
1152                 current->pdeath_signal = 0;
1153         }
1154         exec_keys(current);
1155
1156         task_lock(current);
1157         unsafe = unsafe_exec(current);
1158         security_bprm_apply_creds(bprm, unsafe);
1159         task_unlock(current);
1160         security_bprm_post_apply_creds(bprm);
1161 }
1162 EXPORT_SYMBOL(compute_creds);
1163
1164 /*
1165  * Arguments are '\0' separated strings found at the location bprm->p
1166  * points to; chop off the first by relocating brpm->p to right after
1167  * the first '\0' encountered.
1168  */
1169 int remove_arg_zero(struct linux_binprm *bprm)
1170 {
1171         int ret = 0;
1172         unsigned long offset;
1173         char *kaddr;
1174         struct page *page;
1175
1176         if (!bprm->argc)
1177                 return 0;
1178
1179         do {
1180                 offset = bprm->p & ~PAGE_MASK;
1181                 page = get_arg_page(bprm, bprm->p, 0);
1182                 if (!page) {
1183                         ret = -EFAULT;
1184                         goto out;
1185                 }
1186                 kaddr = kmap_atomic(page, KM_USER0);
1187
1188                 for (; offset < PAGE_SIZE && kaddr[offset];
1189                                 offset++, bprm->p++)
1190                         ;
1191
1192                 kunmap_atomic(kaddr, KM_USER0);
1193                 put_arg_page(page);
1194
1195                 if (offset == PAGE_SIZE)
1196                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1197         } while (offset == PAGE_SIZE);
1198
1199         bprm->p++;
1200         bprm->argc--;
1201         ret = 0;
1202
1203 out:
1204         return ret;
1205 }
1206 EXPORT_SYMBOL(remove_arg_zero);
1207
1208 /*
1209  * cycle the list of binary formats handler, until one recognizes the image
1210  */
1211 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1212 {
1213         int try,retval;
1214         struct linux_binfmt *fmt;
1215 #ifdef __alpha__
1216         /* handle /sbin/loader.. */
1217         {
1218             struct exec * eh = (struct exec *) bprm->buf;
1219
1220             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1221                 (eh->fh.f_flags & 0x3000) == 0x3000)
1222             {
1223                 struct file * file;
1224                 unsigned long loader;
1225
1226                 allow_write_access(bprm->file);
1227                 fput(bprm->file);
1228                 bprm->file = NULL;
1229
1230                 loader = bprm->vma->vm_end - sizeof(void *);
1231
1232                 file = open_exec("/sbin/loader");
1233                 retval = PTR_ERR(file);
1234                 if (IS_ERR(file))
1235                         return retval;
1236
1237                 /* Remember if the application is TASO.  */
1238                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1239
1240                 bprm->file = file;
1241                 bprm->loader = loader;
1242                 retval = prepare_binprm(bprm);
1243                 if (retval<0)
1244                         return retval;
1245                 /* should call search_binary_handler recursively here,
1246                    but it does not matter */
1247             }
1248         }
1249 #endif
1250         retval = security_bprm_check(bprm);
1251         if (retval)
1252                 return retval;
1253
1254         /* kernel module loader fixup */
1255         /* so we don't try to load run modprobe in kernel space. */
1256         set_fs(USER_DS);
1257
1258         retval = audit_bprm(bprm);
1259         if (retval)
1260                 return retval;
1261
1262         retval = -ENOENT;
1263         for (try=0; try<2; try++) {
1264                 read_lock(&binfmt_lock);
1265                 list_for_each_entry(fmt, &formats, lh) {
1266                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1267                         if (!fn)
1268                                 continue;
1269                         if (!try_module_get(fmt->module))
1270                                 continue;
1271                         read_unlock(&binfmt_lock);
1272                         retval = fn(bprm, regs);
1273                         if (retval >= 0) {
1274                                 put_binfmt(fmt);
1275                                 allow_write_access(bprm->file);
1276                                 if (bprm->file)
1277                                         fput(bprm->file);
1278                                 bprm->file = NULL;
1279                                 current->did_exec = 1;
1280                                 proc_exec_connector(current);
1281                                 return retval;
1282                         }
1283                         read_lock(&binfmt_lock);
1284                         put_binfmt(fmt);
1285                         if (retval != -ENOEXEC || bprm->mm == NULL)
1286                                 break;
1287                         if (!bprm->file) {
1288                                 read_unlock(&binfmt_lock);
1289                                 return retval;
1290                         }
1291                 }
1292                 read_unlock(&binfmt_lock);
1293                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1294                         break;
1295 #ifdef CONFIG_KMOD
1296                 }else{
1297 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1298                         if (printable(bprm->buf[0]) &&
1299                             printable(bprm->buf[1]) &&
1300                             printable(bprm->buf[2]) &&
1301                             printable(bprm->buf[3]))
1302                                 break; /* -ENOEXEC */
1303                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1304 #endif
1305                 }
1306         }
1307         return retval;
1308 }
1309
1310 EXPORT_SYMBOL(search_binary_handler);
1311
1312 /*
1313  * sys_execve() executes a new program.
1314  */
1315 int do_execve(char * filename,
1316         char __user *__user *argv,
1317         char __user *__user *envp,
1318         struct pt_regs * regs)
1319 {
1320         struct linux_binprm *bprm;
1321         struct file *file;
1322         unsigned long env_p;
1323         int retval;
1324
1325         retval = -ENOMEM;
1326         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1327         if (!bprm)
1328                 goto out_ret;
1329
1330         file = open_exec(filename);
1331         retval = PTR_ERR(file);
1332         if (IS_ERR(file))
1333                 goto out_kfree;
1334
1335         sched_exec();
1336
1337         bprm->file = file;
1338         bprm->filename = filename;
1339         bprm->interp = filename;
1340
1341         retval = bprm_mm_init(bprm);
1342         if (retval)
1343                 goto out_file;
1344
1345         bprm->argc = count(argv, MAX_ARG_STRINGS);
1346         if ((retval = bprm->argc) < 0)
1347                 goto out_mm;
1348
1349         bprm->envc = count(envp, MAX_ARG_STRINGS);
1350         if ((retval = bprm->envc) < 0)
1351                 goto out_mm;
1352
1353         retval = security_bprm_alloc(bprm);
1354         if (retval)
1355                 goto out;
1356
1357         retval = prepare_binprm(bprm);
1358         if (retval < 0)
1359                 goto out;
1360
1361         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1362         if (retval < 0)
1363                 goto out;
1364
1365         bprm->exec = bprm->p;
1366         retval = copy_strings(bprm->envc, envp, bprm);
1367         if (retval < 0)
1368                 goto out;
1369
1370         env_p = bprm->p;
1371         retval = copy_strings(bprm->argc, argv, bprm);
1372         if (retval < 0)
1373                 goto out;
1374         bprm->argv_len = env_p - bprm->p;
1375
1376         retval = search_binary_handler(bprm,regs);
1377         if (retval >= 0) {
1378                 /* execve success */
1379                 free_arg_pages(bprm);
1380                 security_bprm_free(bprm);
1381                 acct_update_integrals(current);
1382                 kfree(bprm);
1383                 return retval;
1384         }
1385
1386 out:
1387         free_arg_pages(bprm);
1388         if (bprm->security)
1389                 security_bprm_free(bprm);
1390
1391 out_mm:
1392         if (bprm->mm)
1393                 mmput (bprm->mm);
1394
1395 out_file:
1396         if (bprm->file) {
1397                 allow_write_access(bprm->file);
1398                 fput(bprm->file);
1399         }
1400 out_kfree:
1401         kfree(bprm);
1402
1403 out_ret:
1404         return retval;
1405 }
1406
1407 int set_binfmt(struct linux_binfmt *new)
1408 {
1409         struct linux_binfmt *old = current->binfmt;
1410
1411         if (new) {
1412                 if (!try_module_get(new->module))
1413                         return -1;
1414         }
1415         current->binfmt = new;
1416         if (old)
1417                 module_put(old->module);
1418         return 0;
1419 }
1420
1421 EXPORT_SYMBOL(set_binfmt);
1422
1423 /* format_corename will inspect the pattern parameter, and output a
1424  * name into corename, which must have space for at least
1425  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1426  */
1427 static int format_corename(char *corename, const char *pattern, long signr)
1428 {
1429         const char *pat_ptr = pattern;
1430         char *out_ptr = corename;
1431         char *const out_end = corename + CORENAME_MAX_SIZE;
1432         int rc;
1433         int pid_in_pattern = 0;
1434         int ispipe = 0;
1435
1436         if (*pattern == '|')
1437                 ispipe = 1;
1438
1439         /* Repeat as long as we have more pattern to process and more output
1440            space */
1441         while (*pat_ptr) {
1442                 if (*pat_ptr != '%') {
1443                         if (out_ptr == out_end)
1444                                 goto out;
1445                         *out_ptr++ = *pat_ptr++;
1446                 } else {
1447                         switch (*++pat_ptr) {
1448                         case 0:
1449                                 goto out;
1450                         /* Double percent, output one percent */
1451                         case '%':
1452                                 if (out_ptr == out_end)
1453                                         goto out;
1454                                 *out_ptr++ = '%';
1455                                 break;
1456                         /* pid */
1457                         case 'p':
1458                                 pid_in_pattern = 1;
1459                                 rc = snprintf(out_ptr, out_end - out_ptr,
1460                                               "%d", current->tgid);
1461                                 if (rc > out_end - out_ptr)
1462                                         goto out;
1463                                 out_ptr += rc;
1464                                 break;
1465                         /* uid */
1466                         case 'u':
1467                                 rc = snprintf(out_ptr, out_end - out_ptr,
1468                                               "%d", current->uid);
1469                                 if (rc > out_end - out_ptr)
1470                                         goto out;
1471                                 out_ptr += rc;
1472                                 break;
1473                         /* gid */
1474                         case 'g':
1475                                 rc = snprintf(out_ptr, out_end - out_ptr,
1476                                               "%d", current->gid);
1477                                 if (rc > out_end - out_ptr)
1478                                         goto out;
1479                                 out_ptr += rc;
1480                                 break;
1481                         /* signal that caused the coredump */
1482                         case 's':
1483                                 rc = snprintf(out_ptr, out_end - out_ptr,
1484                                               "%ld", signr);
1485                                 if (rc > out_end - out_ptr)
1486                                         goto out;
1487                                 out_ptr += rc;
1488                                 break;
1489                         /* UNIX time of coredump */
1490                         case 't': {
1491                                 struct timeval tv;
1492                                 do_gettimeofday(&tv);
1493                                 rc = snprintf(out_ptr, out_end - out_ptr,
1494                                               "%lu", tv.tv_sec);
1495                                 if (rc > out_end - out_ptr)
1496                                         goto out;
1497                                 out_ptr += rc;
1498                                 break;
1499                         }
1500                         /* hostname */
1501                         case 'h':
1502                                 down_read(&uts_sem);
1503                                 rc = snprintf(out_ptr, out_end - out_ptr,
1504                                               "%s", utsname()->nodename);
1505                                 up_read(&uts_sem);
1506                                 if (rc > out_end - out_ptr)
1507                                         goto out;
1508                                 out_ptr += rc;
1509                                 break;
1510                         /* executable */
1511                         case 'e':
1512                                 rc = snprintf(out_ptr, out_end - out_ptr,
1513                                               "%s", current->comm);
1514                                 if (rc > out_end - out_ptr)
1515                                         goto out;
1516                                 out_ptr += rc;
1517                                 break;
1518                         default:
1519                                 break;
1520                         }
1521                         ++pat_ptr;
1522                 }
1523         }
1524         /* Backward compatibility with core_uses_pid:
1525          *
1526          * If core_pattern does not include a %p (as is the default)
1527          * and core_uses_pid is set, then .%pid will be appended to
1528          * the filename. Do not do this for piped commands. */
1529         if (!ispipe && !pid_in_pattern
1530             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1531                 rc = snprintf(out_ptr, out_end - out_ptr,
1532                               ".%d", current->tgid);
1533                 if (rc > out_end - out_ptr)
1534                         goto out;
1535                 out_ptr += rc;
1536         }
1537 out:
1538         *out_ptr = 0;
1539         return ispipe;
1540 }
1541
1542 static void zap_process(struct task_struct *start)
1543 {
1544         struct task_struct *t;
1545
1546         start->signal->flags = SIGNAL_GROUP_EXIT;
1547         start->signal->group_stop_count = 0;
1548
1549         t = start;
1550         do {
1551                 if (t != current && t->mm) {
1552                         t->mm->core_waiters++;
1553                         sigaddset(&t->pending.signal, SIGKILL);
1554                         signal_wake_up(t, 1);
1555                 }
1556         } while ((t = next_thread(t)) != start);
1557 }
1558
1559 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1560                                 int exit_code)
1561 {
1562         struct task_struct *g, *p;
1563         unsigned long flags;
1564         int err = -EAGAIN;
1565
1566         spin_lock_irq(&tsk->sighand->siglock);
1567         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1568                 tsk->signal->group_exit_code = exit_code;
1569                 zap_process(tsk);
1570                 err = 0;
1571         }
1572         spin_unlock_irq(&tsk->sighand->siglock);
1573         if (err)
1574                 return err;
1575
1576         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1577                 goto done;
1578
1579         rcu_read_lock();
1580         for_each_process(g) {
1581                 if (g == tsk->group_leader)
1582                         continue;
1583
1584                 p = g;
1585                 do {
1586                         if (p->mm) {
1587                                 if (p->mm == mm) {
1588                                         /*
1589                                          * p->sighand can't disappear, but
1590                                          * may be changed by de_thread()
1591                                          */
1592                                         lock_task_sighand(p, &flags);
1593                                         zap_process(p);
1594                                         unlock_task_sighand(p, &flags);
1595                                 }
1596                                 break;
1597                         }
1598                 } while ((p = next_thread(p)) != g);
1599         }
1600         rcu_read_unlock();
1601 done:
1602         return mm->core_waiters;
1603 }
1604
1605 static int coredump_wait(int exit_code)
1606 {
1607         struct task_struct *tsk = current;
1608         struct mm_struct *mm = tsk->mm;
1609         struct completion startup_done;
1610         struct completion *vfork_done;
1611         int core_waiters;
1612
1613         init_completion(&mm->core_done);
1614         init_completion(&startup_done);
1615         mm->core_startup_done = &startup_done;
1616
1617         core_waiters = zap_threads(tsk, mm, exit_code);
1618         up_write(&mm->mmap_sem);
1619
1620         if (unlikely(core_waiters < 0))
1621                 goto fail;
1622
1623         /*
1624          * Make sure nobody is waiting for us to release the VM,
1625          * otherwise we can deadlock when we wait on each other
1626          */
1627         vfork_done = tsk->vfork_done;
1628         if (vfork_done) {
1629                 tsk->vfork_done = NULL;
1630                 complete(vfork_done);
1631         }
1632
1633         if (core_waiters)
1634                 wait_for_completion(&startup_done);
1635 fail:
1636         BUG_ON(mm->core_waiters);
1637         return core_waiters;
1638 }
1639
1640 /*
1641  * set_dumpable converts traditional three-value dumpable to two flags and
1642  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1643  * these bits are not changed atomically.  So get_dumpable can observe the
1644  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1645  * return either old dumpable or new one by paying attention to the order of
1646  * modifying the bits.
1647  *
1648  * dumpable |   mm->flags (binary)
1649  * old  new | initial interim  final
1650  * ---------+-----------------------
1651  *  0    1  |   00      01      01
1652  *  0    2  |   00      10(*)   11
1653  *  1    0  |   01      00      00
1654  *  1    2  |   01      11      11
1655  *  2    0  |   11      10(*)   00
1656  *  2    1  |   11      11      01
1657  *
1658  * (*) get_dumpable regards interim value of 10 as 11.
1659  */
1660 void set_dumpable(struct mm_struct *mm, int value)
1661 {
1662         switch (value) {
1663         case 0:
1664                 clear_bit(MMF_DUMPABLE, &mm->flags);
1665                 smp_wmb();
1666                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1667                 break;
1668         case 1:
1669                 set_bit(MMF_DUMPABLE, &mm->flags);
1670                 smp_wmb();
1671                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1672                 break;
1673         case 2:
1674                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1675                 smp_wmb();
1676                 set_bit(MMF_DUMPABLE, &mm->flags);
1677                 break;
1678         }
1679 }
1680 EXPORT_SYMBOL_GPL(set_dumpable);
1681
1682 int get_dumpable(struct mm_struct *mm)
1683 {
1684         int ret;
1685
1686         ret = mm->flags & 0x3;
1687         return (ret >= 2) ? 2 : ret;
1688 }
1689
1690 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1691 {
1692         char corename[CORENAME_MAX_SIZE + 1];
1693         struct mm_struct *mm = current->mm;
1694         struct linux_binfmt * binfmt;
1695         struct inode * inode;
1696         struct file * file;
1697         int retval = 0;
1698         int fsuid = current->fsuid;
1699         int flag = 0;
1700         int ispipe = 0;
1701
1702         audit_core_dumps(signr);
1703
1704         binfmt = current->binfmt;
1705         if (!binfmt || !binfmt->core_dump)
1706                 goto fail;
1707         down_write(&mm->mmap_sem);
1708         if (!get_dumpable(mm)) {
1709                 up_write(&mm->mmap_sem);
1710                 goto fail;
1711         }
1712
1713         /*
1714          *      We cannot trust fsuid as being the "true" uid of the
1715          *      process nor do we know its entire history. We only know it
1716          *      was tainted so we dump it as root in mode 2.
1717          */
1718         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1719                 flag = O_EXCL;          /* Stop rewrite attacks */
1720                 current->fsuid = 0;     /* Dump root private */
1721         }
1722         set_dumpable(mm, 0);
1723
1724         retval = coredump_wait(exit_code);
1725         if (retval < 0)
1726                 goto fail;
1727
1728         /*
1729          * Clear any false indication of pending signals that might
1730          * be seen by the filesystem code called to write the core file.
1731          */
1732         clear_thread_flag(TIF_SIGPENDING);
1733
1734         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1735                 goto fail_unlock;
1736
1737         /*
1738          * lock_kernel() because format_corename() is controlled by sysctl, which
1739          * uses lock_kernel()
1740          */
1741         lock_kernel();
1742         ispipe = format_corename(corename, core_pattern, signr);
1743         unlock_kernel();
1744         if (ispipe) {
1745                 /* SIGPIPE can happen, but it's just never processed */
1746                 if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1747                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1748                                corename);
1749                         goto fail_unlock;
1750                 }
1751         } else
1752                 file = filp_open(corename,
1753                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1754                                  0600);
1755         if (IS_ERR(file))
1756                 goto fail_unlock;
1757         inode = file->f_path.dentry->d_inode;
1758         if (inode->i_nlink > 1)
1759                 goto close_fail;        /* multiple links - don't dump */
1760         if (!ispipe && d_unhashed(file->f_path.dentry))
1761                 goto close_fail;
1762
1763         /* AK: actually i see no reason to not allow this for named pipes etc.,
1764            but keep the previous behaviour for now. */
1765         if (!ispipe && !S_ISREG(inode->i_mode))
1766                 goto close_fail;
1767         if (!file->f_op)
1768                 goto close_fail;
1769         if (!file->f_op->write)
1770                 goto close_fail;
1771         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1772                 goto close_fail;
1773
1774         retval = binfmt->core_dump(signr, regs, file);
1775
1776         if (retval)
1777                 current->signal->group_exit_code |= 0x80;
1778 close_fail:
1779         filp_close(file, NULL);
1780 fail_unlock:
1781         current->fsuid = fsuid;
1782         complete_all(&mm->core_done);
1783 fail:
1784         return retval;
1785 }