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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/string.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/pid_namespace.h>
  43 #include <linux/module.h>
  44 #include <linux/namei.h>
  45 #include <linux/proc_fs.h>
  46 #include <linux/ptrace.h>
  47 #include <linux/mount.h>
  48 #include <linux/security.h>
  49 #include <linux/syscalls.h>
  50 #include <linux/rmap.h>
  51 #include <linux/tsacct_kern.h>
  52 #include <linux/cn_proc.h>
  53 #include <linux/audit.h>
  54
  55 #include <asm/uaccess.h>
  56 #include <asm/mmu_context.h>
  57 #include <asm/tlb.h>
  58
  59 #ifdef CONFIG_KMOD
  60 #include <linux/kmod.h>
  61 #endif
  62
  63 int core_uses_pid;
  64 char core_pattern[CORENAME_MAX_SIZE] = "core";
  65 int suid_dumpable = 0;
  66
  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 void unregister_binfmt(struct linux_binfmt * fmt)
  85 {
  86         write_lock(&binfmt_lock);
  87         list_del(&fmt->lh);
  88         write_unlock(&binfmt_lock);
  89 }
  90
  91 EXPORT_SYMBOL(unregister_binfmt);
  92
  93 static inline void put_binfmt(struct linux_binfmt * fmt)
  94 {
  95         module_put(fmt->module);
  96 }
  97
  98 /*
  99  * Note that a shared library must be both readable and executable due to
 100  * security reasons.
 101  *
 102  * Also note that we take the address to load from from the file itself.
 103  */
 104 asmlinkage long sys_uselib(const char __user * library)
 105 {
 106         struct file * file;
 107         struct nameidata nd;
 108         int error;
 109
 110         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 111         if (error)
 112                 goto out;
 113
 114         error = -EINVAL;
 115         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 116                 goto exit;
 117
 118         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
 119         if (error)
 120                 goto exit;
 121
 122         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 123         error = PTR_ERR(file);
 124         if (IS_ERR(file))
 125                 goto out;
 126
 127         error = -ENOEXEC;
 128         if(file->f_op) {
 129                 struct linux_binfmt * fmt;
 130
 131                 read_lock(&binfmt_lock);
 132                 list_for_each_entry(fmt, &formats, lh) {
 133                         if (!fmt->load_shlib)
 134                                 continue;
 135                         if (!try_module_get(fmt->module))
 136                                 continue;
 137                         read_unlock(&binfmt_lock);
 138                         error = fmt->load_shlib(file);
 139                         read_lock(&binfmt_lock);
 140                         put_binfmt(fmt);
 141                         if (error != -ENOEXEC)
 142                                 break;
 143                 }
 144                 read_unlock(&binfmt_lock);
 145         }
 146         fput(file);
 147 out:
 148         return error;
 149 exit:
 150         release_open_intent(&nd);
 151         path_put(&nd.path);
 152         goto out;
 153 }
 154
 155 #ifdef CONFIG_MMU
 156
 157 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 158                 int write)
 159 {
 160         struct page *page;
 161         int ret;
 162
 163 #ifdef CONFIG_STACK_GROWSUP
 164         if (write) {
 165                 ret = expand_stack_downwards(bprm->vma, pos);
 166                 if (ret < 0)
 167                         return NULL;
 168         }
 169 #endif
 170         ret = get_user_pages(current, bprm->mm, pos,
 171                         1, write, 1, &page, NULL);
 172         if (ret <= 0)
 173                 return NULL;
 174
 175         if (write) {
 176                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 177                 struct rlimit *rlim;
 178
 179                 /*
 180                  * We've historically supported up to 32 pages (ARG_MAX)
 181                  * of argument strings even with small stacks
 182                  */
 183                 if (size <= ARG_MAX)
 184                         return page;
 185
 186                 /*
 187                  * Limit to 1/4-th the stack size for the argv+env strings.
 188                  * This ensures that:
 189                  *  - the remaining binfmt code will not run out of stack space,
 190                  *  - the program will have a reasonable amount of stack left
 191                  *    to work from.
 192                  */
 193                 rlim = current->signal->rlim;
 194                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 195                         put_page(page);
 196                         return NULL;
 197                 }
 198         }
 199
 200         return page;
 201 }
 202
 203 static void put_arg_page(struct page *page)
 204 {
 205         put_page(page);
 206 }
 207
 208 static void free_arg_page(struct linux_binprm *bprm, int i)
 209 {
 210 }
 211
 212 static void free_arg_pages(struct linux_binprm *bprm)
 213 {
 214 }
 215
 216 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 217                 struct page *page)
 218 {
 219         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 220 }
 221
 222 static int __bprm_mm_init(struct linux_binprm *bprm)
 223 {
 224         int err = -ENOMEM;
 225         struct vm_area_struct *vma = NULL;
 226         struct mm_struct *mm = bprm->mm;
 227
 228         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 229         if (!vma)
 230                 goto err;
 231
 232         down_write(&mm->mmap_sem);
 233         vma->vm_mm = mm;
 234
 235         /*
 236          * Place the stack at the largest stack address the architecture
 237          * supports. Later, we'll move this to an appropriate place. We don't
 238          * use STACK_TOP because that can depend on attributes which aren't
 239          * configured yet.
 240          */
 241         vma->vm_end = STACK_TOP_MAX;
 242         vma->vm_start = vma->vm_end - PAGE_SIZE;
 243
 244         vma->vm_flags = VM_STACK_FLAGS;
 245         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 246         err = insert_vm_struct(mm, vma);
 247         if (err) {
 248                 up_write(&mm->mmap_sem);
 249                 goto err;
 250         }
 251
 252         mm->stack_vm = mm->total_vm = 1;
 253         up_write(&mm->mmap_sem);
 254
 255         bprm->p = vma->vm_end - sizeof(void *);
 256
 257         return 0;
 258
 259 err:
 260         if (vma) {
 261                 bprm->vma = NULL;
 262                 kmem_cache_free(vm_area_cachep, vma);
 263         }
 264
 265         return err;
 266 }
 267
 268 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 269 {
 270         return len <= MAX_ARG_STRLEN;
 271 }
 272
 273 #else
 274
 275 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 276                 int write)
 277 {
 278         struct page *page;
 279
 280         page = bprm->page[pos / PAGE_SIZE];
 281         if (!page && write) {
 282                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 283                 if (!page)
 284                         return NULL;
 285                 bprm->page[pos / PAGE_SIZE] = page;
 286         }
 287
 288         return page;
 289 }
 290
 291 static void put_arg_page(struct page *page)
 292 {
 293 }
 294
 295 static void free_arg_page(struct linux_binprm *bprm, int i)
 296 {
 297         if (bprm->page[i]) {
 298                 __free_page(bprm->page[i]);
 299                 bprm->page[i] = NULL;
 300         }
 301 }
 302
 303 static void free_arg_pages(struct linux_binprm *bprm)
 304 {
 305         int i;
 306
 307         for (i = 0; i < MAX_ARG_PAGES; i++)
 308                 free_arg_page(bprm, i);
 309 }
 310
 311 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 312                 struct page *page)
 313 {
 314 }
 315
 316 static int __bprm_mm_init(struct linux_binprm *bprm)
 317 {
 318         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 319         return 0;
 320 }
 321
 322 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 323 {
 324         return len <= bprm->p;
 325 }
 326
 327 #endif /* CONFIG_MMU */
 328
 329 /*
 330  * Create a new mm_struct and populate it with a temporary stack
 331  * vm_area_struct.  We don't have enough context at this point to set the stack
 332  * flags, permissions, and offset, so we use temporary values.  We'll update
 333  * them later in setup_arg_pages().
 334  */
 335 int bprm_mm_init(struct linux_binprm *bprm)
 336 {
 337         int err;
 338         struct mm_struct *mm = NULL;
 339
 340         bprm->mm = mm = mm_alloc();
 341         err = -ENOMEM;
 342         if (!mm)
 343                 goto err;
 344
 345         err = init_new_context(current, mm);
 346         if (err)
 347                 goto err;
 348
 349         err = __bprm_mm_init(bprm);
 350         if (err)
 351                 goto err;
 352
 353         return 0;
 354
 355 err:
 356         if (mm) {
 357                 bprm->mm = NULL;
 358                 mmdrop(mm);
 359         }
 360
 361         return err;
 362 }
 363
 364 /*
 365  * count() counts the number of strings in array ARGV.
 366  */
 367 static int count(char __user * __user * argv, int max)
 368 {
 369         int i = 0;
 370
 371         if (argv != NULL) {
 372                 for (;;) {
 373                         char __user * p;
 374
 375                         if (get_user(p, argv))
 376                                 return -EFAULT;
 377                         if (!p)
 378                                 break;
 379                         argv++;
 380                         if(++i > max)
 381                                 return -E2BIG;
 382                         cond_resched();
 383                 }
 384         }
 385         return i;
 386 }
 387
 388 /*
 389  * 'copy_strings()' copies argument/environment strings from the old
 390  * processes's memory to the new process's stack.  The call to get_user_pages()
 391  * ensures the destination page is created and not swapped out.
 392  */
 393 static int copy_strings(int argc, char __user * __user * argv,
 394                         struct linux_binprm *bprm)
 395 {
 396         struct page *kmapped_page = NULL;
 397         char *kaddr = NULL;
 398         unsigned long kpos = 0;
 399         int ret;
 400
 401         while (argc-- > 0) {
 402                 char __user *str;
 403                 int len;
 404                 unsigned long pos;
 405
 406                 if (get_user(str, argv+argc) ||
 407                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 408                         ret = -EFAULT;
 409                         goto out;
 410                 }
 411
 412                 if (!valid_arg_len(bprm, len)) {
 413                         ret = -E2BIG;
 414                         goto out;
 415                 }
 416
 417                 /* We're going to work our way backwords. */
 418                 pos = bprm->p;
 419                 str += len;
 420                 bprm->p -= len;
 421
 422                 while (len > 0) {
 423                         int offset, bytes_to_copy;
 424
 425                         offset = pos % PAGE_SIZE;
 426                         if (offset == 0)
 427                                 offset = PAGE_SIZE;
 428
 429                         bytes_to_copy = offset;
 430                         if (bytes_to_copy > len)
 431                                 bytes_to_copy = len;
 432
 433                         offset -= bytes_to_copy;
 434                         pos -= bytes_to_copy;
 435                         str -= bytes_to_copy;
 436                         len -= bytes_to_copy;
 437
 438                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 439                                 struct page *page;
 440
 441                                 page = get_arg_page(bprm, pos, 1);
 442                                 if (!page) {
 443                                         ret = -E2BIG;
 444                                         goto out;
 445                                 }
 446
 447                                 if (kmapped_page) {
 448                                         flush_kernel_dcache_page(kmapped_page);
 449                                         kunmap(kmapped_page);
 450                                         put_arg_page(kmapped_page);
 451                                 }
 452                                 kmapped_page = page;
 453                                 kaddr = kmap(kmapped_page);
 454                                 kpos = pos & PAGE_MASK;
 455                                 flush_arg_page(bprm, kpos, kmapped_page);
 456                         }
 457                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 458                                 ret = -EFAULT;
 459                                 goto out;
 460                         }
 461                 }
 462         }
 463         ret = 0;
 464 out:
 465         if (kmapped_page) {
 466                 flush_kernel_dcache_page(kmapped_page);
 467                 kunmap(kmapped_page);
 468                 put_arg_page(kmapped_page);
 469         }
 470         return ret;
 471 }
 472
 473 /*
 474  * Like copy_strings, but get argv and its values from kernel memory.
 475  */
 476 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 477 {
 478         int r;
 479         mm_segment_t oldfs = get_fs();
 480         set_fs(KERNEL_DS);
 481         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 482         set_fs(oldfs);
 483         return r;
 484 }
 485 EXPORT_SYMBOL(copy_strings_kernel);
 486
 487 #ifdef CONFIG_MMU
 488
 489 /*
 490  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 491  * the binfmt code determines where the new stack should reside, we shift it to
 492  * its final location.  The process proceeds as follows:
 493  *
 494  * 1) Use shift to calculate the new vma endpoints.
 495  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 496  *    arguments passed to subsequent functions are consistent.
 497  * 3) Move vma's page tables to the new range.
 498  * 4) Free up any cleared pgd range.
 499  * 5) Shrink the vma to cover only the new range.
 500  */
 501 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 502 {
 503         struct mm_struct *mm = vma->vm_mm;
 504         unsigned long old_start = vma->vm_start;
 505         unsigned long old_end = vma->vm_end;
 506         unsigned long length = old_end - old_start;
 507         unsigned long new_start = old_start - shift;
 508         unsigned long new_end = old_end - shift;
 509         struct mmu_gather *tlb;
 510
 511         BUG_ON(new_start > new_end);
 512
 513         /*
 514          * ensure there are no vmas between where we want to go
 515          * and where we are
 516          */
 517         if (vma != find_vma(mm, new_start))
 518                 return -EFAULT;
 519
 520         /*
 521          * cover the whole range: [new_start, old_end)
 522          */
 523         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 524
 525         /*
 526          * move the page tables downwards, on failure we rely on
 527          * process cleanup to remove whatever mess we made.
 528          */
 529         if (length != move_page_tables(vma, old_start,
 530                                        vma, new_start, length))
 531                 return -ENOMEM;
 532
 533         lru_add_drain();
 534         tlb = tlb_gather_mmu(mm, 0);
 535         if (new_end > old_start) {
 536                 /*
 537                  * when the old and new regions overlap clear from new_end.
 538                  */
 539                 free_pgd_range(&tlb, new_end, old_end, new_end,
 540                         vma->vm_next ? vma->vm_next->vm_start : 0);
 541         } else {
 542                 /*
 543                  * otherwise, clean from old_start; this is done to not touch
 544                  * the address space in [new_end, old_start) some architectures
 545                  * have constraints on va-space that make this illegal (IA64) -
 546                  * for the others its just a little faster.
 547                  */
 548                 free_pgd_range(&tlb, old_start, old_end, new_end,
 549                         vma->vm_next ? vma->vm_next->vm_start : 0);
 550         }
 551         tlb_finish_mmu(tlb, new_end, old_end);
 552
 553         /*
 554          * shrink the vma to just the new range.
 555          */
 556         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 557
 558         return 0;
 559 }
 560
 561 #define EXTRA_STACK_VM_PAGES    20      /* random */
 562
 563 /*
 564  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 565  * the stack is optionally relocated, and some extra space is added.
 566  */
 567 int setup_arg_pages(struct linux_binprm *bprm,
 568                     unsigned long stack_top,
 569                     int executable_stack)
 570 {
 571         unsigned long ret;
 572         unsigned long stack_shift;
 573         struct mm_struct *mm = current->mm;
 574         struct vm_area_struct *vma = bprm->vma;
 575         struct vm_area_struct *prev = NULL;
 576         unsigned long vm_flags;
 577         unsigned long stack_base;
 578
 579 #ifdef CONFIG_STACK_GROWSUP
 580         /* Limit stack size to 1GB */
 581         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 582         if (stack_base > (1 << 30))
 583                 stack_base = 1 << 30;
 584
 585         /* Make sure we didn't let the argument array grow too large. */
 586         if (vma->vm_end - vma->vm_start > stack_base)
 587                 return -ENOMEM;
 588
 589         stack_base = PAGE_ALIGN(stack_top - stack_base);
 590
 591         stack_shift = vma->vm_start - stack_base;
 592         mm->arg_start = bprm->p - stack_shift;
 593         bprm->p = vma->vm_end - stack_shift;
 594 #else
 595         stack_top = arch_align_stack(stack_top);
 596         stack_top = PAGE_ALIGN(stack_top);
 597         stack_shift = vma->vm_end - stack_top;
 598
 599         bprm->p -= stack_shift;
 600         mm->arg_start = bprm->p;
 601 #endif
 602
 603         if (bprm->loader)
 604                 bprm->loader -= stack_shift;
 605         bprm->exec -= stack_shift;
 606
 607         down_write(&mm->mmap_sem);
 608         vm_flags = vma->vm_flags;
 609
 610         /*
 611          * Adjust stack execute permissions; explicitly enable for
 612          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 613          * (arch default) otherwise.
 614          */
 615         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 616                 vm_flags |= VM_EXEC;
 617         else if (executable_stack == EXSTACK_DISABLE_X)
 618                 vm_flags &= ~VM_EXEC;
 619         vm_flags |= mm->def_flags;
 620
 621         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 622                         vm_flags);
 623         if (ret)
 624                 goto out_unlock;
 625         BUG_ON(prev != vma);
 626
 627         /* Move stack pages down in memory. */
 628         if (stack_shift) {
 629                 ret = shift_arg_pages(vma, stack_shift);
 630                 if (ret) {
 631                         up_write(&mm->mmap_sem);
 632                         return ret;
 633                 }
 634         }
 635
 636 #ifdef CONFIG_STACK_GROWSUP
 637         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 638 #else
 639         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 640 #endif
 641         ret = expand_stack(vma, stack_base);
 642         if (ret)
 643                 ret = -EFAULT;
 644
 645 out_unlock:
 646         up_write(&mm->mmap_sem);
 647         return 0;
 648 }
 649 EXPORT_SYMBOL(setup_arg_pages);
 650
 651 #endif /* CONFIG_MMU */
 652
 653 struct file *open_exec(const char *name)
 654 {
 655         struct nameidata nd;
 656         int err;
 657         struct file *file;
 658
 659         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 660         file = ERR_PTR(err);
 661
 662         if (!err) {
 663                 struct inode *inode = nd.path.dentry->d_inode;
 664                 file = ERR_PTR(-EACCES);
 665                 if (S_ISREG(inode->i_mode)) {
 666                         int err = vfs_permission(&nd, MAY_EXEC);
 667                         file = ERR_PTR(err);
 668                         if (!err) {
 669                                 file = nameidata_to_filp(&nd,
 670                                                         O_RDONLY|O_LARGEFILE);
 671                                 if (!IS_ERR(file)) {
 672                                         err = deny_write_access(file);
 673                                         if (err) {
 674                                                 fput(file);
 675                                                 file = ERR_PTR(err);
 676                                         }
 677                                 }
 678 out:
 679                                 return file;
 680                         }
 681                 }
 682                 release_open_intent(&nd);
 683                 path_put(&nd.path);
 684         }
 685         goto out;
 686 }
 687
 688 EXPORT_SYMBOL(open_exec);
 689
 690 int kernel_read(struct file *file, unsigned long offset,
 691         char *addr, unsigned long count)
 692 {
 693         mm_segment_t old_fs;
 694         loff_t pos = offset;
 695         int result;
 696
 697         old_fs = get_fs();
 698         set_fs(get_ds());
 699         /* The cast to a user pointer is valid due to the set_fs() */
 700         result = vfs_read(file, (void __user *)addr, count, &pos);
 701         set_fs(old_fs);
 702         return result;
 703 }
 704
 705 EXPORT_SYMBOL(kernel_read);
 706
 707 static int exec_mmap(struct mm_struct *mm)
 708 {
 709         struct task_struct *tsk;
 710         struct mm_struct * old_mm, *active_mm;
 711
 712         /* Notify parent that we're no longer interested in the old VM */
 713         tsk = current;
 714         old_mm = current->mm;
 715         mm_release(tsk, old_mm);
 716
 717         if (old_mm) {
 718                 /*
 719                  * Make sure that if there is a core dump in progress
 720                  * for the old mm, we get out and die instead of going
 721                  * through with the exec.  We must hold mmap_sem around
 722                  * checking core_waiters and changing tsk->mm.  The
 723                  * core-inducing thread will increment core_waiters for
 724                  * each thread whose ->mm == old_mm.
 725                  */
 726                 down_read(&old_mm->mmap_sem);
 727                 if (unlikely(old_mm->core_waiters)) {
 728                         up_read(&old_mm->mmap_sem);
 729                         return -EINTR;
 730                 }
 731         }
 732         task_lock(tsk);
 733         active_mm = tsk->active_mm;
 734         tsk->mm = mm;
 735         tsk->active_mm = mm;
 736         activate_mm(active_mm, mm);
 737         task_unlock(tsk);
 738         arch_pick_mmap_layout(mm);
 739         if (old_mm) {
 740                 up_read(&old_mm->mmap_sem);
 741                 BUG_ON(active_mm != old_mm);
 742                 mmput(old_mm);
 743                 return 0;
 744         }
 745         mmdrop(active_mm);
 746         return 0;
 747 }
 748
 749 /*
 750  * This function makes sure the current process has its own signal table,
 751  * so that flush_signal_handlers can later reset the handlers without
 752  * disturbing other processes.  (Other processes might share the signal
 753  * table via the CLONE_SIGHAND option to clone().)
 754  */
 755 static int de_thread(struct task_struct *tsk)
 756 {
 757         struct signal_struct *sig = tsk->signal;
 758         struct sighand_struct *oldsighand = tsk->sighand;
 759         spinlock_t *lock = &oldsighand->siglock;
 760         struct task_struct *leader = NULL;
 761         int count;
 762
 763         if (thread_group_empty(tsk))
 764                 goto no_thread_group;
 765
 766         /*
 767          * Kill all other threads in the thread group.
 768          * We must hold tasklist_lock to call zap_other_threads.
 769          */
 770         read_lock(&tasklist_lock);
 771         spin_lock_irq(lock);
 772         if (signal_group_exit(sig)) {
 773                 /*
 774                  * Another group action in progress, just
 775                  * return so that the signal is processed.
 776                  */
 777                 spin_unlock_irq(lock);
 778                 read_unlock(&tasklist_lock);
 779                 return -EAGAIN;
 780         }
 781
 782         /*
 783          * child_reaper ignores SIGKILL, change it now.
 784          * Reparenting needs write_lock on tasklist_lock,
 785          * so it is safe to do it under read_lock.
 786          */
 787         if (unlikely(tsk->group_leader == task_child_reaper(tsk)))
 788                 task_active_pid_ns(tsk)->child_reaper = tsk;
 789
 790         sig->group_exit_task = tsk;
 791         zap_other_threads(tsk);
 792         read_unlock(&tasklist_lock);
 793
 794         /* Account for the thread group leader hanging around: */
 795         count = thread_group_leader(tsk) ? 1 : 2;
 796         sig->notify_count = count;
 797         while (atomic_read(&sig->count) > count) {
 798                 __set_current_state(TASK_UNINTERRUPTIBLE);
 799                 spin_unlock_irq(lock);
 800                 schedule();
 801                 spin_lock_irq(lock);
 802         }
 803         spin_unlock_irq(lock);
 804
 805         /*
 806          * At this point all other threads have exited, all we have to
 807          * do is to wait for the thread group leader to become inactive,
 808          * and to assume its PID:
 809          */
 810         if (!thread_group_leader(tsk)) {
 811                 leader = tsk->group_leader;
 812
 813                 sig->notify_count = -1;
 814                 for (;;) {
 815                         write_lock_irq(&tasklist_lock);
 816                         if (likely(leader->exit_state))
 817                                 break;
 818                         __set_current_state(TASK_UNINTERRUPTIBLE);
 819                         write_unlock_irq(&tasklist_lock);
 820                         schedule();
 821                 }
 822
 823                 /*
 824                  * The only record we have of the real-time age of a
 825                  * process, regardless of execs it's done, is start_time.
 826                  * All the past CPU time is accumulated in signal_struct
 827                  * from sister threads now dead.  But in this non-leader
 828                  * exec, nothing survives from the original leader thread,
 829                  * whose birth marks the true age of this process now.
 830                  * When we take on its identity by switching to its PID, we
 831                  * also take its birthdate (always earlier than our own).
 832                  */
 833                 tsk->start_time = leader->start_time;
 834
 835                 BUG_ON(!same_thread_group(leader, tsk));
 836                 BUG_ON(has_group_leader_pid(tsk));
 837                 /*
 838                  * An exec() starts a new thread group with the
 839                  * TGID of the previous thread group. Rehash the
 840                  * two threads with a switched PID, and release
 841                  * the former thread group leader:
 842                  */
 843
 844                 /* Become a process group leader with the old leader's pid.
 845                  * The old leader becomes a thread of the this thread group.
 846                  * Note: The old leader also uses this pid until release_task
 847                  *       is called.  Odd but simple and correct.
 848                  */
 849                 detach_pid(tsk, PIDTYPE_PID);
 850                 tsk->pid = leader->pid;
 851                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 852                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 853                 transfer_pid(leader, tsk, PIDTYPE_SID);
 854                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 855
 856                 tsk->group_leader = tsk;
 857                 leader->group_leader = tsk;
 858
 859                 tsk->exit_signal = SIGCHLD;
 860
 861                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 862                 leader->exit_state = EXIT_DEAD;
 863
 864                 write_unlock_irq(&tasklist_lock);
 865         }
 866
 867         sig->group_exit_task = NULL;
 868         sig->notify_count = 0;
 869
 870 no_thread_group:
 871         exit_itimers(sig);
 872         if (leader)
 873                 release_task(leader);
 874
 875         if (atomic_read(&oldsighand->count) != 1) {
 876                 struct sighand_struct *newsighand;
 877                 /*
 878                  * This ->sighand is shared with the CLONE_SIGHAND
 879                  * but not CLONE_THREAD task, switch to the new one.
 880                  */
 881                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 882                 if (!newsighand)
 883                         return -ENOMEM;
 884
 885                 atomic_set(&newsighand->count, 1);
 886                 memcpy(newsighand->action, oldsighand->action,
 887                        sizeof(newsighand->action));
 888
 889                 write_lock_irq(&tasklist_lock);
 890                 spin_lock(&oldsighand->siglock);
 891                 rcu_assign_pointer(tsk->sighand, newsighand);
 892                 spin_unlock(&oldsighand->siglock);
 893                 write_unlock_irq(&tasklist_lock);
 894
 895                 __cleanup_sighand(oldsighand);
 896         }
 897
 898         BUG_ON(!thread_group_leader(tsk));
 899         return 0;
 900 }
 901
 902 /*
 903  * These functions flushes out all traces of the currently running executable
 904  * so that a new one can be started
 905  */
 906 static void flush_old_files(struct files_struct * files)
 907 {
 908         long j = -1;
 909         struct fdtable *fdt;
 910
 911         spin_lock(&files->file_lock);
 912         for (;;) {
 913                 unsigned long set, i;
 914
 915                 j++;
 916                 i = j * __NFDBITS;
 917                 fdt = files_fdtable(files);
 918                 if (i >= fdt->max_fds)
 919                         break;
 920                 set = fdt->close_on_exec->fds_bits[j];
 921                 if (!set)
 922                         continue;
 923                 fdt->close_on_exec->fds_bits[j] = 0;
 924                 spin_unlock(&files->file_lock);
 925                 for ( ; set ; i++,set >>= 1) {
 926                         if (set & 1) {
 927                                 sys_close(i);
 928                         }
 929                 }
 930                 spin_lock(&files->file_lock);
 931
 932         }
 933         spin_unlock(&files->file_lock);
 934 }
 935
 936 char *get_task_comm(char *buf, struct task_struct *tsk)
 937 {
 938         /* buf must be at least sizeof(tsk->comm) in size */
 939         task_lock(tsk);
 940         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 941         task_unlock(tsk);
 942         return buf;
 943 }
 944
 945 void set_task_comm(struct task_struct *tsk, char *buf)
 946 {
 947         task_lock(tsk);
 948         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 949         task_unlock(tsk);
 950 }
 951
 952 int flush_old_exec(struct linux_binprm * bprm)
 953 {
 954         char * name;
 955         int i, ch, retval;
 956         struct files_struct *files;
 957         char tcomm[sizeof(current->comm)];
 958
 959         /*
 960          * Make sure we have a private signal table and that
 961          * we are unassociated from the previous thread group.
 962          */
 963         retval = de_thread(current);
 964         if (retval)
 965                 goto out;
 966
 967         /*
 968          * Make sure we have private file handles. Ask the
 969          * fork helper to do the work for us and the exit
 970          * helper to do the cleanup of the old one.
 971          */
 972         files = current->files;         /* refcounted so safe to hold */
 973         retval = unshare_files();
 974         if (retval)
 975                 goto out;
 976         /*
 977          * Release all of the old mmap stuff
 978          */
 979         retval = exec_mmap(bprm->mm);
 980         if (retval)
 981                 goto mmap_failed;
 982
 983         bprm->mm = NULL;                /* We're using it now */
 984
 985         /* This is the point of no return */
 986         put_files_struct(files);
 987
 988         current->sas_ss_sp = current->sas_ss_size = 0;
 989
 990         if (current->euid == current->uid && current->egid == current->gid)
 991                 set_dumpable(current->mm, 1);
 992         else
 993                 set_dumpable(current->mm, suid_dumpable);
 994
 995         name = bprm->filename;
 996
 997         /* Copies the binary name from after last slash */
 998         for (i=0; (ch = *(name++)) != '\0';) {
 999                 if (ch == '/')
1000                         i = 0; /* overwrite what we wrote */
1001                 else
1002                         if (i < (sizeof(tcomm) - 1))
1003                                 tcomm[i++] = ch;
1004         }
1005         tcomm[i] = '\0';
1006         set_task_comm(current, tcomm);
1007
1008         current->flags &= ~PF_RANDOMIZE;
1009         flush_thread();
1010
1011         /* Set the new mm task size. We have to do that late because it may
1012          * depend on TIF_32BIT which is only updated in flush_thread() on
1013          * some architectures like powerpc
1014          */
1015         current->mm->task_size = TASK_SIZE;
1016
1017         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1018                 suid_keys(current);
1019                 set_dumpable(current->mm, suid_dumpable);
1020                 current->pdeath_signal = 0;
1021         } else if (file_permission(bprm->file, MAY_READ) ||
1022                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1023                 suid_keys(current);
1024                 set_dumpable(current->mm, suid_dumpable);
1025         }
1026
1027         /* An exec changes our domain. We are no longer part of the thread
1028            group */
1029
1030         current->self_exec_id++;
1031
1032         flush_signal_handlers(current, 0);
1033         flush_old_files(current->files);
1034
1035         return 0;
1036
1037 mmap_failed:
1038         reset_files_struct(current, files);
1039 out:
1040         return retval;
1041 }
1042
1043 EXPORT_SYMBOL(flush_old_exec);
1044
1045 /*
1046  * Fill the binprm structure from the inode.
1047  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1048  */
1049 int prepare_binprm(struct linux_binprm *bprm)
1050 {
1051         int mode;
1052         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1053         int retval;
1054
1055         mode = inode->i_mode;
1056         if (bprm->file->f_op == NULL)
1057                 return -EACCES;
1058
1059         bprm->e_uid = current->euid;
1060         bprm->e_gid = current->egid;
1061
1062         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1063                 /* Set-uid? */
1064                 if (mode & S_ISUID) {
1065                         current->personality &= ~PER_CLEAR_ON_SETID;
1066                         bprm->e_uid = inode->i_uid;
1067                 }
1068
1069                 /* Set-gid? */
1070                 /*
1071                  * If setgid is set but no group execute bit then this
1072                  * is a candidate for mandatory locking, not a setgid
1073                  * executable.
1074                  */
1075                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1076                         current->personality &= ~PER_CLEAR_ON_SETID;
1077                         bprm->e_gid = inode->i_gid;
1078                 }
1079         }
1080
1081         /* fill in binprm security blob */
1082         retval = security_bprm_set(bprm);
1083         if (retval)
1084                 return retval;
1085
1086         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1087         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1088 }
1089
1090 EXPORT_SYMBOL(prepare_binprm);
1091
1092 static int unsafe_exec(struct task_struct *p)
1093 {
1094         int unsafe = 0;
1095         if (p->ptrace & PT_PTRACED) {
1096                 if (p->ptrace & PT_PTRACE_CAP)
1097                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
1098                 else
1099                         unsafe |= LSM_UNSAFE_PTRACE;
1100         }
1101         if (atomic_read(&p->fs->count) > 1 ||
1102             atomic_read(&p->files->count) > 1 ||
1103             atomic_read(&p->sighand->count) > 1)
1104                 unsafe |= LSM_UNSAFE_SHARE;
1105
1106         return unsafe;
1107 }
1108
1109 void compute_creds(struct linux_binprm *bprm)
1110 {
1111         int unsafe;
1112
1113         if (bprm->e_uid != current->uid) {
1114                 suid_keys(current);
1115                 current->pdeath_signal = 0;
1116         }
1117         exec_keys(current);
1118
1119         task_lock(current);
1120         unsafe = unsafe_exec(current);
1121         security_bprm_apply_creds(bprm, unsafe);
1122         task_unlock(current);
1123         security_bprm_post_apply_creds(bprm);
1124 }
1125 EXPORT_SYMBOL(compute_creds);
1126
1127 /*
1128  * Arguments are '\0' separated strings found at the location bprm->p
1129  * points to; chop off the first by relocating brpm->p to right after
1130  * the first '\0' encountered.
1131  */
1132 int remove_arg_zero(struct linux_binprm *bprm)
1133 {
1134         int ret = 0;
1135         unsigned long offset;
1136         char *kaddr;
1137         struct page *page;
1138
1139         if (!bprm->argc)
1140                 return 0;
1141
1142         do {
1143                 offset = bprm->p & ~PAGE_MASK;
1144                 page = get_arg_page(bprm, bprm->p, 0);
1145                 if (!page) {
1146                         ret = -EFAULT;
1147                         goto out;
1148                 }
1149                 kaddr = kmap_atomic(page, KM_USER0);
1150
1151                 for (; offset < PAGE_SIZE && kaddr[offset];
1152                                 offset++, bprm->p++)
1153                         ;
1154
1155                 kunmap_atomic(kaddr, KM_USER0);
1156                 put_arg_page(page);
1157
1158                 if (offset == PAGE_SIZE)
1159                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1160         } while (offset == PAGE_SIZE);
1161
1162         bprm->p++;
1163         bprm->argc--;
1164         ret = 0;
1165
1166 out:
1167         return ret;
1168 }
1169 EXPORT_SYMBOL(remove_arg_zero);
1170
1171 /*
1172  * cycle the list of binary formats handler, until one recognizes the image
1173  */
1174 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1175 {
1176         int try,retval;
1177         struct linux_binfmt *fmt;
1178 #if defined(__alpha__) && defined(CONFIG_ARCH_SUPPORTS_AOUT)
1179         /* handle /sbin/loader.. */
1180         {
1181             struct exec * eh = (struct exec *) bprm->buf;
1182
1183             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1184                 (eh->fh.f_flags & 0x3000) == 0x3000)
1185             {
1186                 struct file * file;
1187                 unsigned long loader;
1188
1189                 allow_write_access(bprm->file);
1190                 fput(bprm->file);
1191                 bprm->file = NULL;
1192
1193                 loader = bprm->vma->vm_end - sizeof(void *);
1194
1195                 file = open_exec("/sbin/loader");
1196                 retval = PTR_ERR(file);
1197                 if (IS_ERR(file))
1198                         return retval;
1199
1200                 /* Remember if the application is TASO.  */
1201                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1202
1203                 bprm->file = file;
1204                 bprm->loader = loader;
1205                 retval = prepare_binprm(bprm);
1206                 if (retval<0)
1207                         return retval;
1208                 /* should call search_binary_handler recursively here,
1209                    but it does not matter */
1210             }
1211         }
1212 #endif
1213         retval = security_bprm_check(bprm);
1214         if (retval)
1215                 return retval;
1216
1217         /* kernel module loader fixup */
1218         /* so we don't try to load run modprobe in kernel space. */
1219         set_fs(USER_DS);
1220
1221         retval = audit_bprm(bprm);
1222         if (retval)
1223                 return retval;
1224
1225         retval = -ENOENT;
1226         for (try=0; try<2; try++) {
1227                 read_lock(&binfmt_lock);
1228                 list_for_each_entry(fmt, &formats, lh) {
1229                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1230                         if (!fn)
1231                                 continue;
1232                         if (!try_module_get(fmt->module))
1233                                 continue;
1234                         read_unlock(&binfmt_lock);
1235                         retval = fn(bprm, regs);
1236                         if (retval >= 0) {
1237                                 put_binfmt(fmt);
1238                                 allow_write_access(bprm->file);
1239                                 if (bprm->file)
1240                                         fput(bprm->file);
1241                                 bprm->file = NULL;
1242                                 current->did_exec = 1;
1243                                 proc_exec_connector(current);
1244                                 return retval;
1245                         }
1246                         read_lock(&binfmt_lock);
1247                         put_binfmt(fmt);
1248                         if (retval != -ENOEXEC || bprm->mm == NULL)
1249                                 break;
1250                         if (!bprm->file) {
1251                                 read_unlock(&binfmt_lock);
1252                                 return retval;
1253                         }
1254                 }
1255                 read_unlock(&binfmt_lock);
1256                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1257                         break;
1258 #ifdef CONFIG_KMOD
1259                 }else{
1260 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1261                         if (printable(bprm->buf[0]) &&
1262                             printable(bprm->buf[1]) &&
1263                             printable(bprm->buf[2]) &&
1264                             printable(bprm->buf[3]))
1265                                 break; /* -ENOEXEC */
1266                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1267 #endif
1268                 }
1269         }
1270         return retval;
1271 }
1272
1273 EXPORT_SYMBOL(search_binary_handler);
1274
1275 /*
1276  * sys_execve() executes a new program.
1277  */
1278 int do_execve(char * filename,
1279         char __user *__user *argv,
1280         char __user *__user *envp,
1281         struct pt_regs * regs)
1282 {
1283         struct linux_binprm *bprm;
1284         struct file *file;
1285         unsigned long env_p;
1286         int retval;
1287
1288         retval = -ENOMEM;
1289         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1290         if (!bprm)
1291                 goto out_ret;
1292
1293         file = open_exec(filename);
1294         retval = PTR_ERR(file);
1295         if (IS_ERR(file))
1296                 goto out_kfree;
1297
1298         sched_exec();
1299
1300         bprm->file = file;
1301         bprm->filename = filename;
1302         bprm->interp = filename;
1303
1304         retval = bprm_mm_init(bprm);
1305         if (retval)
1306                 goto out_file;
1307
1308         bprm->argc = count(argv, MAX_ARG_STRINGS);
1309         if ((retval = bprm->argc) < 0)
1310                 goto out_mm;
1311
1312         bprm->envc = count(envp, MAX_ARG_STRINGS);
1313         if ((retval = bprm->envc) < 0)
1314                 goto out_mm;
1315
1316         retval = security_bprm_alloc(bprm);
1317         if (retval)
1318                 goto out;
1319
1320         retval = prepare_binprm(bprm);
1321         if (retval < 0)
1322                 goto out;
1323
1324         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1325         if (retval < 0)
1326                 goto out;
1327
1328         bprm->exec = bprm->p;
1329         retval = copy_strings(bprm->envc, envp, bprm);
1330         if (retval < 0)
1331                 goto out;
1332
1333         env_p = bprm->p;
1334         retval = copy_strings(bprm->argc, argv, bprm);
1335         if (retval < 0)
1336                 goto out;
1337         bprm->argv_len = env_p - bprm->p;
1338
1339         retval = search_binary_handler(bprm,regs);
1340         if (retval >= 0) {
1341                 /* execve success */
1342                 free_arg_pages(bprm);
1343                 security_bprm_free(bprm);
1344                 acct_update_integrals(current);
1345                 kfree(bprm);
1346                 return retval;
1347         }
1348
1349 out:
1350         free_arg_pages(bprm);
1351         if (bprm->security)
1352                 security_bprm_free(bprm);
1353
1354 out_mm:
1355         if (bprm->mm)
1356                 mmput (bprm->mm);
1357
1358 out_file:
1359         if (bprm->file) {
1360                 allow_write_access(bprm->file);
1361                 fput(bprm->file);
1362         }
1363 out_kfree:
1364         kfree(bprm);
1365
1366 out_ret:
1367         return retval;
1368 }
1369
1370 int set_binfmt(struct linux_binfmt *new)
1371 {
1372         struct linux_binfmt *old = current->binfmt;
1373
1374         if (new) {
1375                 if (!try_module_get(new->module))
1376                         return -1;
1377         }
1378         current->binfmt = new;
1379         if (old)
1380                 module_put(old->module);
1381         return 0;
1382 }
1383
1384 EXPORT_SYMBOL(set_binfmt);
1385
1386 /* format_corename will inspect the pattern parameter, and output a
1387  * name into corename, which must have space for at least
1388  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1389  */
1390 static int format_corename(char *corename, const char *pattern, long signr)
1391 {
1392         const char *pat_ptr = pattern;
1393         char *out_ptr = corename;
1394         char *const out_end = corename + CORENAME_MAX_SIZE;
1395         int rc;
1396         int pid_in_pattern = 0;
1397         int ispipe = 0;
1398
1399         if (*pattern == '|')
1400                 ispipe = 1;
1401
1402         /* Repeat as long as we have more pattern to process and more output
1403            space */
1404         while (*pat_ptr) {
1405                 if (*pat_ptr != '%') {
1406                         if (out_ptr == out_end)
1407                                 goto out;
1408                         *out_ptr++ = *pat_ptr++;
1409                 } else {
1410                         switch (*++pat_ptr) {
1411                         case 0:
1412                                 goto out;
1413                         /* Double percent, output one percent */
1414                         case '%':
1415                                 if (out_ptr == out_end)
1416                                         goto out;
1417                                 *out_ptr++ = '%';
1418                                 break;
1419                         /* pid */
1420                         case 'p':
1421                                 pid_in_pattern = 1;
1422                                 rc = snprintf(out_ptr, out_end - out_ptr,
1423                                               "%d", task_tgid_vnr(current));
1424                                 if (rc > out_end - out_ptr)
1425                                         goto out;
1426                                 out_ptr += rc;
1427                                 break;
1428                         /* uid */
1429                         case 'u':
1430                                 rc = snprintf(out_ptr, out_end - out_ptr,
1431                                               "%d", current->uid);
1432                                 if (rc > out_end - out_ptr)
1433                                         goto out;
1434                                 out_ptr += rc;
1435                                 break;
1436                         /* gid */
1437                         case 'g':
1438                                 rc = snprintf(out_ptr, out_end - out_ptr,
1439                                               "%d", current->gid);
1440                                 if (rc > out_end - out_ptr)
1441                                         goto out;
1442                                 out_ptr += rc;
1443                                 break;
1444                         /* signal that caused the coredump */
1445                         case 's':
1446                                 rc = snprintf(out_ptr, out_end - out_ptr,
1447                                               "%ld", signr);
1448                                 if (rc > out_end - out_ptr)
1449                                         goto out;
1450                                 out_ptr += rc;
1451                                 break;
1452                         /* UNIX time of coredump */
1453                         case 't': {
1454                                 struct timeval tv;
1455                                 do_gettimeofday(&tv);
1456                                 rc = snprintf(out_ptr, out_end - out_ptr,
1457                                               "%lu", tv.tv_sec);
1458                                 if (rc > out_end - out_ptr)
1459                                         goto out;
1460                                 out_ptr += rc;
1461                                 break;
1462                         }
1463                         /* hostname */
1464                         case 'h':
1465                                 down_read(&uts_sem);
1466                                 rc = snprintf(out_ptr, out_end - out_ptr,
1467                                               "%s", utsname()->nodename);
1468                                 up_read(&uts_sem);
1469                                 if (rc > out_end - out_ptr)
1470                                         goto out;
1471                                 out_ptr += rc;
1472                                 break;
1473                         /* executable */
1474                         case 'e':
1475                                 rc = snprintf(out_ptr, out_end - out_ptr,
1476                                               "%s", current->comm);
1477                                 if (rc > out_end - out_ptr)
1478                                         goto out;
1479                                 out_ptr += rc;
1480                                 break;
1481                         /* core limit size */
1482                         case 'c':
1483                                 rc = snprintf(out_ptr, out_end - out_ptr,
1484                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1485                                 if (rc > out_end - out_ptr)
1486                                         goto out;
1487                                 out_ptr += rc;
1488                                 break;
1489                         default:
1490                                 break;
1491                         }
1492                         ++pat_ptr;
1493                 }
1494         }
1495         /* Backward compatibility with core_uses_pid:
1496          *
1497          * If core_pattern does not include a %p (as is the default)
1498          * and core_uses_pid is set, then .%pid will be appended to
1499          * the filename. Do not do this for piped commands. */
1500         if (!ispipe && !pid_in_pattern
1501             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1502                 rc = snprintf(out_ptr, out_end - out_ptr,
1503                               ".%d", task_tgid_vnr(current));
1504                 if (rc > out_end - out_ptr)
1505                         goto out;
1506                 out_ptr += rc;
1507         }
1508 out:
1509         *out_ptr = 0;
1510         return ispipe;
1511 }
1512
1513 static void zap_process(struct task_struct *start)
1514 {
1515         struct task_struct *t;
1516
1517         start->signal->flags = SIGNAL_GROUP_EXIT;
1518         start->signal->group_stop_count = 0;
1519
1520         t = start;
1521         do {
1522                 if (t != current && t->mm) {
1523                         t->mm->core_waiters++;
1524                         sigaddset(&t->pending.signal, SIGKILL);
1525                         signal_wake_up(t, 1);
1526                 }
1527         } while ((t = next_thread(t)) != start);
1528 }
1529
1530 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1531                                 int exit_code)
1532 {
1533         struct task_struct *g, *p;
1534         unsigned long flags;
1535         int err = -EAGAIN;
1536
1537         spin_lock_irq(&tsk->sighand->siglock);
1538         if (!signal_group_exit(tsk->signal)) {
1539                 tsk->signal->group_exit_code = exit_code;
1540                 zap_process(tsk);
1541                 err = 0;
1542         }
1543         spin_unlock_irq(&tsk->sighand->siglock);
1544         if (err)
1545                 return err;
1546
1547         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1548                 goto done;
1549
1550         rcu_read_lock();
1551         for_each_process(g) {
1552                 if (g == tsk->group_leader)
1553                         continue;
1554
1555                 p = g;
1556                 do {
1557                         if (p->mm) {
1558                                 if (p->mm == mm) {
1559                                         /*
1560                                          * p->sighand can't disappear, but
1561                                          * may be changed by de_thread()
1562                                          */
1563                                         lock_task_sighand(p, &flags);
1564                                         zap_process(p);
1565                                         unlock_task_sighand(p, &flags);
1566                                 }
1567                                 break;
1568                         }
1569                 } while ((p = next_thread(p)) != g);
1570         }
1571         rcu_read_unlock();
1572 done:
1573         return mm->core_waiters;
1574 }
1575
1576 static int coredump_wait(int exit_code)
1577 {
1578         struct task_struct *tsk = current;
1579         struct mm_struct *mm = tsk->mm;
1580         struct completion startup_done;
1581         struct completion *vfork_done;
1582         int core_waiters;
1583
1584         init_completion(&mm->core_done);
1585         init_completion(&startup_done);
1586         mm->core_startup_done = &startup_done;
1587
1588         core_waiters = zap_threads(tsk, mm, exit_code);
1589         up_write(&mm->mmap_sem);
1590
1591         if (unlikely(core_waiters < 0))
1592                 goto fail;
1593
1594         /*
1595          * Make sure nobody is waiting for us to release the VM,
1596          * otherwise we can deadlock when we wait on each other
1597          */
1598         vfork_done = tsk->vfork_done;
1599         if (vfork_done) {
1600                 tsk->vfork_done = NULL;
1601                 complete(vfork_done);
1602         }
1603
1604         if (core_waiters)
1605                 wait_for_completion(&startup_done);
1606 fail:
1607         BUG_ON(mm->core_waiters);
1608         return core_waiters;
1609 }
1610
1611 /*
1612  * set_dumpable converts traditional three-value dumpable to two flags and
1613  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1614  * these bits are not changed atomically.  So get_dumpable can observe the
1615  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1616  * return either old dumpable or new one by paying attention to the order of
1617  * modifying the bits.
1618  *
1619  * dumpable |   mm->flags (binary)
1620  * old  new | initial interim  final
1621  * ---------+-----------------------
1622  *  0    1  |   00      01      01
1623  *  0    2  |   00      10(*)   11
1624  *  1    0  |   01      00      00
1625  *  1    2  |   01      11      11
1626  *  2    0  |   11      10(*)   00
1627  *  2    1  |   11      11      01
1628  *
1629  * (*) get_dumpable regards interim value of 10 as 11.
1630  */
1631 void set_dumpable(struct mm_struct *mm, int value)
1632 {
1633         switch (value) {
1634         case 0:
1635                 clear_bit(MMF_DUMPABLE, &mm->flags);
1636                 smp_wmb();
1637                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1638                 break;
1639         case 1:
1640                 set_bit(MMF_DUMPABLE, &mm->flags);
1641                 smp_wmb();
1642                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1643                 break;
1644         case 2:
1645                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1646                 smp_wmb();
1647                 set_bit(MMF_DUMPABLE, &mm->flags);
1648                 break;
1649         }
1650 }
1651
1652 int get_dumpable(struct mm_struct *mm)
1653 {
1654         int ret;
1655
1656         ret = mm->flags & 0x3;
1657         return (ret >= 2) ? 2 : ret;
1658 }
1659
1660 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1661 {
1662         char corename[CORENAME_MAX_SIZE + 1];
1663         struct mm_struct *mm = current->mm;
1664         struct linux_binfmt * binfmt;
1665         struct inode * inode;
1666         struct file * file;
1667         int retval = 0;
1668         int fsuid = current->fsuid;
1669         int flag = 0;
1670         int ispipe = 0;
1671         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1672         char **helper_argv = NULL;
1673         int helper_argc = 0;
1674         char *delimit;
1675
1676         audit_core_dumps(signr);
1677
1678         binfmt = current->binfmt;
1679         if (!binfmt || !binfmt->core_dump)
1680                 goto fail;
1681         down_write(&mm->mmap_sem);
1682         /*
1683          * If another thread got here first, or we are not dumpable, bail out.
1684          */
1685         if (mm->core_waiters || !get_dumpable(mm)) {
1686                 up_write(&mm->mmap_sem);
1687                 goto fail;
1688         }
1689
1690         /*
1691          *      We cannot trust fsuid as being the "true" uid of the
1692          *      process nor do we know its entire history. We only know it
1693          *      was tainted so we dump it as root in mode 2.
1694          */
1695         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1696                 flag = O_EXCL;          /* Stop rewrite attacks */
1697                 current->fsuid = 0;     /* Dump root private */
1698         }
1699
1700         retval = coredump_wait(exit_code);
1701         if (retval < 0)
1702                 goto fail;
1703
1704         /*
1705          * Clear any false indication of pending signals that might
1706          * be seen by the filesystem code called to write the core file.
1707          */
1708         clear_thread_flag(TIF_SIGPENDING);
1709
1710         /*
1711          * lock_kernel() because format_corename() is controlled by sysctl, which
1712          * uses lock_kernel()
1713          */
1714         lock_kernel();
1715         ispipe = format_corename(corename, core_pattern, signr);
1716         unlock_kernel();
1717         /*
1718          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1719          * to a pipe.  Since we're not writing directly to the filesystem
1720          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1721          * created unless the pipe reader choses to write out the core file
1722          * at which point file size limits and permissions will be imposed
1723          * as it does with any other process
1724          */
1725         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1726                 goto fail_unlock;
1727
1728         if (ispipe) {
1729                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1730                 /* Terminate the string before the first option */
1731                 delimit = strchr(corename, ' ');
1732                 if (delimit)
1733                         *delimit = '\0';
1734                 delimit = strrchr(helper_argv[0], '/');
1735                 if (delimit)
1736                         delimit++;
1737                 else
1738                         delimit = helper_argv[0];
1739                 if (!strcmp(delimit, current->comm)) {
1740                         printk(KERN_NOTICE "Recursive core dump detected, "
1741                                         "aborting\n");
1742                         goto fail_unlock;
1743                 }
1744
1745                 core_limit = RLIM_INFINITY;
1746
1747                 /* SIGPIPE can happen, but it's just never processed */
1748                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1749                                 &file)) {
1750                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1751                                corename);
1752                         goto fail_unlock;
1753                 }
1754         } else
1755                 file = filp_open(corename,
1756                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1757                                  0600);
1758         if (IS_ERR(file))
1759                 goto fail_unlock;
1760         inode = file->f_path.dentry->d_inode;
1761         if (inode->i_nlink > 1)
1762                 goto close_fail;        /* multiple links - don't dump */
1763         if (!ispipe && d_unhashed(file->f_path.dentry))
1764                 goto close_fail;
1765
1766         /* AK: actually i see no reason to not allow this for named pipes etc.,
1767            but keep the previous behaviour for now. */
1768         if (!ispipe && !S_ISREG(inode->i_mode))
1769                 goto close_fail;
1770         /*
1771          * Dont allow local users get cute and trick others to coredump
1772          * into their pre-created files:
1773          */
1774         if (inode->i_uid != current->fsuid)
1775                 goto close_fail;
1776         if (!file->f_op)
1777                 goto close_fail;
1778         if (!file->f_op->write)
1779                 goto close_fail;
1780         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1781                 goto close_fail;
1782
1783         retval = binfmt->core_dump(signr, regs, file, core_limit);
1784
1785         if (retval)
1786                 current->signal->group_exit_code |= 0x80;
1787 close_fail:
1788         filp_close(file, NULL);
1789 fail_unlock:
1790         if (helper_argv)
1791                 argv_free(helper_argv);
1792
1793         current->fsuid = fsuid;
1794         complete_all(&mm->core_done);
1795 fail:
1796         return retval;
1797 }