fs/exec.c

   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/slab.h>
  26 #include <linux/file.h>
  27 #include <linux/fdtable.h>
  28 #include <linux/mm.h>
  29 #include <linux/stat.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/smp_lock.h>
  32 #include <linux/swap.h>
  33 #include <linux/string.h>
  34 #include <linux/init.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/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/tsacct_kern.h>
  50 #include <linux/cn_proc.h>
  51 #include <linux/audit.h>
  52
  53 #include <asm/uaccess.h>
  54 #include <asm/mmu_context.h>
  55 #include <asm/tlb.h>
  56
  57 #ifdef CONFIG_KMOD
  58 #include <linux/kmod.h>
  59 #endif
  60
  61 #ifdef __alpha__
  62 /* for /sbin/loader handling in search_binary_handler() */
  63 #include <linux/a.out.h>
  64 #endif
  65
  66 int core_uses_pid;
  67 char core_pattern[CORENAME_MAX_SIZE] = "core";
  68 int suid_dumpable = 0;
  69
  70 /* The maximal length of core_pattern is also specified in sysctl.c */
  71
  72 static LIST_HEAD(formats);
  73 static DEFINE_RWLOCK(binfmt_lock);
  74
  75 int register_binfmt(struct linux_binfmt * fmt)
  76 {
  77         if (!fmt)
  78                 return -EINVAL;
  79         write_lock(&binfmt_lock);
  80         list_add(&fmt->lh, &formats);
  81         write_unlock(&binfmt_lock);
  82         return 0;
  83 }
  84
  85 EXPORT_SYMBOL(register_binfmt);
  86
  87 void unregister_binfmt(struct linux_binfmt * fmt)
  88 {
  89         write_lock(&binfmt_lock);
  90         list_del(&fmt->lh);
  91         write_unlock(&binfmt_lock);
  92 }
  93
  94 EXPORT_SYMBOL(unregister_binfmt);
  95
  96 static inline void put_binfmt(struct linux_binfmt * fmt)
  97 {
  98         module_put(fmt->module);
  99 }
 100
 101 /*
 102  * Note that a shared library must be both readable and executable due to
 103  * security reasons.
 104  *
 105  * Also note that we take the address to load from from the file itself.
 106  */
 107 asmlinkage long sys_uselib(const char __user * library)
 108 {
 109         struct file * file;
 110         struct nameidata nd;
 111         int error;
 112
 113         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 114         if (error)
 115                 goto out;
 116
 117         error = -EINVAL;
 118         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 119                 goto exit;
 120
 121         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
 122         if (error)
 123                 goto exit;
 124
 125         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 126         error = PTR_ERR(file);
 127         if (IS_ERR(file))
 128                 goto out;
 129
 130         error = -ENOEXEC;
 131         if(file->f_op) {
 132                 struct linux_binfmt * fmt;
 133
 134                 read_lock(&binfmt_lock);
 135                 list_for_each_entry(fmt, &formats, lh) {
 136                         if (!fmt->load_shlib)
 137                                 continue;
 138                         if (!try_module_get(fmt->module))
 139                                 continue;
 140                         read_unlock(&binfmt_lock);
 141                         error = fmt->load_shlib(file);
 142                         read_lock(&binfmt_lock);
 143                         put_binfmt(fmt);
 144                         if (error != -ENOEXEC)
 145                                 break;
 146                 }
 147                 read_unlock(&binfmt_lock);
 148         }
 149         fput(file);
 150 out:
 151         return error;
 152 exit:
 153         release_open_intent(&nd);
 154         path_put(&nd.path);
 155         goto out;
 156 }
 157
 158 #ifdef CONFIG_MMU
 159
 160 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 161                 int write)
 162 {
 163         struct page *page;
 164         int ret;
 165
 166 #ifdef CONFIG_STACK_GROWSUP
 167         if (write) {
 168                 ret = expand_stack_downwards(bprm->vma, pos);
 169                 if (ret < 0)
 170                         return NULL;
 171         }
 172 #endif
 173         ret = get_user_pages(current, bprm->mm, pos,
 174                         1, write, 1, &page, NULL);
 175         if (ret <= 0)
 176                 return NULL;
 177
 178         if (write) {
 179                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 180                 struct rlimit *rlim;
 181
 182                 /*
 183                  * We've historically supported up to 32 pages (ARG_MAX)
 184                  * of argument strings even with small stacks
 185                  */
 186                 if (size <= ARG_MAX)
 187                         return page;
 188
 189                 /*
 190                  * Limit to 1/4-th the stack size for the argv+env strings.
 191                  * This ensures that:
 192                  *  - the remaining binfmt code will not run out of stack space,
 193                  *  - the program will have a reasonable amount of stack left
 194                  *    to work from.
 195                  */
 196                 rlim = current->signal->rlim;
 197                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 198                         put_page(page);
 199                         return NULL;
 200                 }
 201         }
 202
 203         return page;
 204 }
 205
 206 static void put_arg_page(struct page *page)
 207 {
 208         put_page(page);
 209 }
 210
 211 static void free_arg_page(struct linux_binprm *bprm, int i)
 212 {
 213 }
 214
 215 static void free_arg_pages(struct linux_binprm *bprm)
 216 {
 217 }
 218
 219 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 220                 struct page *page)
 221 {
 222         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 223 }
 224
 225 static int __bprm_mm_init(struct linux_binprm *bprm)
 226 {
 227         int err = -ENOMEM;
 228         struct vm_area_struct *vma = NULL;
 229         struct mm_struct *mm = bprm->mm;
 230
 231         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 232         if (!vma)
 233                 goto err;
 234
 235         down_write(&mm->mmap_sem);
 236         vma->vm_mm = mm;
 237
 238         /*
 239          * Place the stack at the largest stack address the architecture
 240          * supports. Later, we'll move this to an appropriate place. We don't
 241          * use STACK_TOP because that can depend on attributes which aren't
 242          * configured yet.
 243          */
 244         vma->vm_end = STACK_TOP_MAX;
 245         vma->vm_start = vma->vm_end - PAGE_SIZE;
 246
 247         vma->vm_flags = VM_STACK_FLAGS;
 248         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 249         err = insert_vm_struct(mm, vma);
 250         if (err) {
 251                 up_write(&mm->mmap_sem);
 252                 goto err;
 253         }
 254
 255         mm->stack_vm = mm->total_vm = 1;
 256         up_write(&mm->mmap_sem);
 257
 258         bprm->p = vma->vm_end - sizeof(void *);
 259
 260         return 0;
 261
 262 err:
 263         if (vma) {
 264                 bprm->vma = NULL;
 265                 kmem_cache_free(vm_area_cachep, vma);
 266         }
 267
 268         return err;
 269 }
 270
 271 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 272 {
 273         return len <= MAX_ARG_STRLEN;
 274 }
 275
 276 #else
 277
 278 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 279                 int write)
 280 {
 281         struct page *page;
 282
 283         page = bprm->page[pos / PAGE_SIZE];
 284         if (!page && write) {
 285                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 286                 if (!page)
 287                         return NULL;
 288                 bprm->page[pos / PAGE_SIZE] = page;
 289         }
 290
 291         return page;
 292 }
 293
 294 static void put_arg_page(struct page *page)
 295 {
 296 }
 297
 298 static void free_arg_page(struct linux_binprm *bprm, int i)
 299 {
 300         if (bprm->page[i]) {
 301                 __free_page(bprm->page[i]);
 302                 bprm->page[i] = NULL;
 303         }
 304 }
 305
 306 static void free_arg_pages(struct linux_binprm *bprm)
 307 {
 308         int i;
 309
 310         for (i = 0; i < MAX_ARG_PAGES; i++)
 311                 free_arg_page(bprm, i);
 312 }
 313
 314 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 315                 struct page *page)
 316 {
 317 }
 318
 319 static int __bprm_mm_init(struct linux_binprm *bprm)
 320 {
 321         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 322         return 0;
 323 }
 324
 325 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 326 {
 327         return len <= bprm->p;
 328 }
 329
 330 #endif /* CONFIG_MMU */
 331
 332 /*
 333  * Create a new mm_struct and populate it with a temporary stack
 334  * vm_area_struct.  We don't have enough context at this point to set the stack
 335  * flags, permissions, and offset, so we use temporary values.  We'll update
 336  * them later in setup_arg_pages().
 337  */
 338 int bprm_mm_init(struct linux_binprm *bprm)
 339 {
 340         int err;
 341         struct mm_struct *mm = NULL;
 342
 343         bprm->mm = mm = mm_alloc();
 344         err = -ENOMEM;
 345         if (!mm)
 346                 goto err;
 347
 348         err = init_new_context(current, mm);
 349         if (err)
 350                 goto err;
 351
 352         err = __bprm_mm_init(bprm);
 353         if (err)
 354                 goto err;
 355
 356         return 0;
 357
 358 err:
 359         if (mm) {
 360                 bprm->mm = NULL;
 361                 mmdrop(mm);
 362         }
 363
 364         return err;
 365 }
 366
 367 /*
 368  * count() counts the number of strings in array ARGV.
 369  */
 370 static int count(char __user * __user * argv, int max)
 371 {
 372         int i = 0;
 373
 374         if (argv != NULL) {
 375                 for (;;) {
 376                         char __user * p;
 377
 378                         if (get_user(p, argv))
 379                                 return -EFAULT;
 380                         if (!p)
 381                                 break;
 382                         argv++;
 383                         if(++i > max)
 384                                 return -E2BIG;
 385                         cond_resched();
 386                 }
 387         }
 388         return i;
 389 }
 390
 391 /*
 392  * 'copy_strings()' copies argument/environment strings from the old
 393  * processes's memory to the new process's stack.  The call to get_user_pages()
 394  * ensures the destination page is created and not swapped out.
 395  */
 396 static int copy_strings(int argc, char __user * __user * argv,
 397                         struct linux_binprm *bprm)
 398 {
 399         struct page *kmapped_page = NULL;
 400         char *kaddr = NULL;
 401         unsigned long kpos = 0;
 402         int ret;
 403
 404         while (argc-- > 0) {
 405                 char __user *str;
 406                 int len;
 407                 unsigned long pos;
 408
 409                 if (get_user(str, argv+argc) ||
 410                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 411                         ret = -EFAULT;
 412                         goto out;
 413                 }
 414
 415                 if (!valid_arg_len(bprm, len)) {
 416                         ret = -E2BIG;
 417                         goto out;
 418                 }
 419
 420                 /* We're going to work our way backwords. */
 421                 pos = bprm->p;
 422                 str += len;
 423                 bprm->p -= len;
 424
 425                 while (len > 0) {
 426                         int offset, bytes_to_copy;
 427
 428                         offset = pos % PAGE_SIZE;
 429                         if (offset == 0)
 430                                 offset = PAGE_SIZE;
 431
 432                         bytes_to_copy = offset;
 433                         if (bytes_to_copy > len)
 434                                 bytes_to_copy = len;
 435
 436                         offset -= bytes_to_copy;
 437                         pos -= bytes_to_copy;
 438                         str -= bytes_to_copy;
 439                         len -= bytes_to_copy;
 440
 441                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 442                                 struct page *page;
 443
 444                                 page = get_arg_page(bprm, pos, 1);
 445                                 if (!page) {
 446                                         ret = -E2BIG;
 447                                         goto out;
 448                                 }
 449
 450                                 if (kmapped_page) {
 451                                         flush_kernel_dcache_page(kmapped_page);
 452                                         kunmap(kmapped_page);
 453                                         put_arg_page(kmapped_page);
 454                                 }
 455                                 kmapped_page = page;
 456                                 kaddr = kmap(kmapped_page);
 457                                 kpos = pos & PAGE_MASK;
 458                                 flush_arg_page(bprm, kpos, kmapped_page);
 459                         }
 460                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 461                                 ret = -EFAULT;
 462                                 goto out;
 463                         }
 464                 }
 465         }
 466         ret = 0;
 467 out:
 468         if (kmapped_page) {
 469                 flush_kernel_dcache_page(kmapped_page);
 470                 kunmap(kmapped_page);
 471                 put_arg_page(kmapped_page);
 472         }
 473         return ret;
 474 }
 475
 476 /*
 477  * Like copy_strings, but get argv and its values from kernel memory.
 478  */
 479 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 480 {
 481         int r;
 482         mm_segment_t oldfs = get_fs();
 483         set_fs(KERNEL_DS);
 484         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 485         set_fs(oldfs);
 486         return r;
 487 }
 488 EXPORT_SYMBOL(copy_strings_kernel);
 489
 490 #ifdef CONFIG_MMU
 491
 492 /*
 493  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 494  * the binfmt code determines where the new stack should reside, we shift it to
 495  * its final location.  The process proceeds as follows:
 496  *
 497  * 1) Use shift to calculate the new vma endpoints.
 498  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 499  *    arguments passed to subsequent functions are consistent.
 500  * 3) Move vma's page tables to the new range.
 501  * 4) Free up any cleared pgd range.
 502  * 5) Shrink the vma to cover only the new range.
 503  */
 504 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 505 {
 506         struct mm_struct *mm = vma->vm_mm;
 507         unsigned long old_start = vma->vm_start;
 508         unsigned long old_end = vma->vm_end;
 509         unsigned long length = old_end - old_start;
 510         unsigned long new_start = old_start - shift;
 511         unsigned long new_end = old_end - shift;
 512         struct mmu_gather *tlb;
 513
 514         BUG_ON(new_start > new_end);
 515
 516         /*
 517          * ensure there are no vmas between where we want to go
 518          * and where we are
 519          */
 520         if (vma != find_vma(mm, new_start))
 521                 return -EFAULT;
 522
 523         /*
 524          * cover the whole range: [new_start, old_end)
 525          */
 526         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 527
 528         /*
 529          * move the page tables downwards, on failure we rely on
 530          * process cleanup to remove whatever mess we made.
 531          */
 532         if (length != move_page_tables(vma, old_start,
 533                                        vma, new_start, length))
 534                 return -ENOMEM;
 535
 536         lru_add_drain();
 537         tlb = tlb_gather_mmu(mm, 0);
 538         if (new_end > old_start) {
 539                 /*
 540                  * when the old and new regions overlap clear from new_end.
 541                  */
 542                 free_pgd_range(tlb, new_end, old_end, new_end,
 543                         vma->vm_next ? vma->vm_next->vm_start : 0);
 544         } else {
 545                 /*
 546                  * otherwise, clean from old_start; this is done to not touch
 547                  * the address space in [new_end, old_start) some architectures
 548                  * have constraints on va-space that make this illegal (IA64) -
 549                  * for the others its just a little faster.
 550                  */
 551                 free_pgd_range(tlb, old_start, old_end, new_end,
 552                         vma->vm_next ? vma->vm_next->vm_start : 0);
 553         }
 554         tlb_finish_mmu(tlb, new_end, old_end);
 555
 556         /*
 557          * shrink the vma to just the new range.
 558          */
 559         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 560
 561         return 0;
 562 }
 563
 564 #define EXTRA_STACK_VM_PAGES    20      /* random */
 565
 566 /*
 567  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 568  * the stack is optionally relocated, and some extra space is added.
 569  */
 570 int setup_arg_pages(struct linux_binprm *bprm,
 571                     unsigned long stack_top,
 572                     int executable_stack)
 573 {
 574         unsigned long ret;
 575         unsigned long stack_shift;
 576         struct mm_struct *mm = current->mm;
 577         struct vm_area_struct *vma = bprm->vma;
 578         struct vm_area_struct *prev = NULL;
 579         unsigned long vm_flags;
 580         unsigned long stack_base;
 581
 582 #ifdef CONFIG_STACK_GROWSUP
 583         /* Limit stack size to 1GB */
 584         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 585         if (stack_base > (1 << 30))
 586                 stack_base = 1 << 30;
 587
 588         /* Make sure we didn't let the argument array grow too large. */
 589         if (vma->vm_end - vma->vm_start > stack_base)
 590                 return -ENOMEM;
 591
 592         stack_base = PAGE_ALIGN(stack_top - stack_base);
 593
 594         stack_shift = vma->vm_start - stack_base;
 595         mm->arg_start = bprm->p - stack_shift;
 596         bprm->p = vma->vm_end - stack_shift;
 597 #else
 598         stack_top = arch_align_stack(stack_top);
 599         stack_top = PAGE_ALIGN(stack_top);
 600         stack_shift = vma->vm_end - stack_top;
 601
 602         bprm->p -= stack_shift;
 603         mm->arg_start = bprm->p;
 604 #endif
 605
 606         if (bprm->loader)
 607                 bprm->loader -= stack_shift;
 608         bprm->exec -= stack_shift;
 609
 610         down_write(&mm->mmap_sem);
 611         vm_flags = VM_STACK_FLAGS;
 612
 613         /*
 614          * Adjust stack execute permissions; explicitly enable for
 615          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 616          * (arch default) otherwise.
 617          */
 618         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 619                 vm_flags |= VM_EXEC;
 620         else if (executable_stack == EXSTACK_DISABLE_X)
 621                 vm_flags &= ~VM_EXEC;
 622         vm_flags |= mm->def_flags;
 623
 624         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 625                         vm_flags);
 626         if (ret)
 627                 goto out_unlock;
 628         BUG_ON(prev != vma);
 629
 630         /* Move stack pages down in memory. */
 631         if (stack_shift) {
 632                 ret = shift_arg_pages(vma, stack_shift);
 633                 if (ret) {
 634                         up_write(&mm->mmap_sem);
 635                         return ret;
 636                 }
 637         }
 638
 639 #ifdef CONFIG_STACK_GROWSUP
 640         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 641 #else
 642         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 643 #endif
 644         ret = expand_stack(vma, stack_base);
 645         if (ret)
 646                 ret = -EFAULT;
 647
 648 out_unlock:
 649         up_write(&mm->mmap_sem);
 650         return 0;
 651 }
 652 EXPORT_SYMBOL(setup_arg_pages);
 653
 654 #endif /* CONFIG_MMU */
 655
 656 struct file *open_exec(const char *name)
 657 {
 658         struct nameidata nd;
 659         int err;
 660         struct file *file;
 661
 662         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 663         file = ERR_PTR(err);
 664
 665         if (!err) {
 666                 struct inode *inode = nd.path.dentry->d_inode;
 667                 file = ERR_PTR(-EACCES);
 668                 if (S_ISREG(inode->i_mode)) {
 669                         int err = vfs_permission(&nd, MAY_EXEC);
 670                         file = ERR_PTR(err);
 671                         if (!err) {
 672                                 file = nameidata_to_filp(&nd,
 673                                                         O_RDONLY|O_LARGEFILE);
 674                                 if (!IS_ERR(file)) {
 675                                         err = deny_write_access(file);
 676                                         if (err) {
 677                                                 fput(file);
 678                                                 file = ERR_PTR(err);
 679                                         }
 680                                 }
 681 out:
 682                                 return file;
 683                         }
 684                 }
 685                 release_open_intent(&nd);
 686                 path_put(&nd.path);
 687         }
 688         goto out;
 689 }
 690
 691 EXPORT_SYMBOL(open_exec);
 692
 693 int kernel_read(struct file *file, unsigned long offset,
 694         char *addr, unsigned long count)
 695 {
 696         mm_segment_t old_fs;
 697         loff_t pos = offset;
 698         int result;
 699
 700         old_fs = get_fs();
 701         set_fs(get_ds());
 702         /* The cast to a user pointer is valid due to the set_fs() */
 703         result = vfs_read(file, (void __user *)addr, count, &pos);
 704         set_fs(old_fs);
 705         return result;
 706 }
 707
 708 EXPORT_SYMBOL(kernel_read);
 709
 710 static int exec_mmap(struct mm_struct *mm)
 711 {
 712         struct task_struct *tsk;
 713         struct mm_struct * old_mm, *active_mm;
 714
 715         /* Notify parent that we're no longer interested in the old VM */
 716         tsk = current;
 717         old_mm = current->mm;
 718         mm_release(tsk, old_mm);
 719
 720         if (old_mm) {
 721                 /*
 722                  * Make sure that if there is a core dump in progress
 723                  * for the old mm, we get out and die instead of going
 724                  * through with the exec.  We must hold mmap_sem around
 725                  * checking core_waiters and changing tsk->mm.  The
 726                  * core-inducing thread will increment core_waiters for
 727                  * each thread whose ->mm == old_mm.
 728                  */
 729                 down_read(&old_mm->mmap_sem);
 730                 if (unlikely(old_mm->core_waiters)) {
 731                         up_read(&old_mm->mmap_sem);
 732                         return -EINTR;
 733                 }
 734         }
 735         task_lock(tsk);
 736         active_mm = tsk->active_mm;
 737         tsk->mm = mm;
 738         tsk->active_mm = mm;
 739         activate_mm(active_mm, mm);
 740         task_unlock(tsk);
 741         mm_update_next_owner(old_mm);
 742         arch_pick_mmap_layout(mm);
 743         if (old_mm) {
 744                 up_read(&old_mm->mmap_sem);
 745                 BUG_ON(active_mm != old_mm);
 746                 mmput(old_mm);
 747                 return 0;
 748         }
 749         mmdrop(active_mm);
 750         return 0;
 751 }
 752
 753 /*
 754  * This function makes sure the current process has its own signal table,
 755  * so that flush_signal_handlers can later reset the handlers without
 756  * disturbing other processes.  (Other processes might share the signal
 757  * table via the CLONE_SIGHAND option to clone().)
 758  */
 759 static int de_thread(struct task_struct *tsk)
 760 {
 761         struct signal_struct *sig = tsk->signal;
 762         struct sighand_struct *oldsighand = tsk->sighand;
 763         spinlock_t *lock = &oldsighand->siglock;
 764         struct task_struct *leader = NULL;
 765         int count;
 766
 767         if (thread_group_empty(tsk))
 768                 goto no_thread_group;
 769
 770         /*
 771          * Kill all other threads in the thread group.
 772          */
 773         spin_lock_irq(lock);
 774         if (signal_group_exit(sig)) {
 775                 /*
 776                  * Another group action in progress, just
 777                  * return so that the signal is processed.
 778                  */
 779                 spin_unlock_irq(lock);
 780                 return -EAGAIN;
 781         }
 782         sig->group_exit_task = tsk;
 783         zap_other_threads(tsk);
 784
 785         /* Account for the thread group leader hanging around: */
 786         count = thread_group_leader(tsk) ? 1 : 2;
 787         sig->notify_count = count;
 788         while (atomic_read(&sig->count) > count) {
 789                 __set_current_state(TASK_UNINTERRUPTIBLE);
 790                 spin_unlock_irq(lock);
 791                 schedule();
 792                 spin_lock_irq(lock);
 793         }
 794         spin_unlock_irq(lock);
 795
 796         /*
 797          * At this point all other threads have exited, all we have to
 798          * do is to wait for the thread group leader to become inactive,
 799          * and to assume its PID:
 800          */
 801         if (!thread_group_leader(tsk)) {
 802                 leader = tsk->group_leader;
 803
 804                 sig->notify_count = -1; /* for exit_notify() */
 805                 for (;;) {
 806                         write_lock_irq(&tasklist_lock);
 807                         if (likely(leader->exit_state))
 808                                 break;
 809                         __set_current_state(TASK_UNINTERRUPTIBLE);
 810                         write_unlock_irq(&tasklist_lock);
 811                         schedule();
 812                 }
 813
 814                 if (unlikely(task_child_reaper(tsk) == leader))
 815                         task_active_pid_ns(tsk)->child_reaper = tsk;
 816                 /*
 817                  * The only record we have of the real-time age of a
 818                  * process, regardless of execs it's done, is start_time.
 819                  * All the past CPU time is accumulated in signal_struct
 820                  * from sister threads now dead.  But in this non-leader
 821                  * exec, nothing survives from the original leader thread,
 822                  * whose birth marks the true age of this process now.
 823                  * When we take on its identity by switching to its PID, we
 824                  * also take its birthdate (always earlier than our own).
 825                  */
 826                 tsk->start_time = leader->start_time;
 827
 828                 BUG_ON(!same_thread_group(leader, tsk));
 829                 BUG_ON(has_group_leader_pid(tsk));
 830                 /*
 831                  * An exec() starts a new thread group with the
 832                  * TGID of the previous thread group. Rehash the
 833                  * two threads with a switched PID, and release
 834                  * the former thread group leader:
 835                  */
 836
 837                 /* Become a process group leader with the old leader's pid.
 838                  * The old leader becomes a thread of the this thread group.
 839                  * Note: The old leader also uses this pid until release_task
 840                  *       is called.  Odd but simple and correct.
 841                  */
 842                 detach_pid(tsk, PIDTYPE_PID);
 843                 tsk->pid = leader->pid;
 844                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 845                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 846                 transfer_pid(leader, tsk, PIDTYPE_SID);
 847                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 848
 849                 tsk->group_leader = tsk;
 850                 leader->group_leader = tsk;
 851
 852                 tsk->exit_signal = SIGCHLD;
 853
 854                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 855                 leader->exit_state = EXIT_DEAD;
 856
 857                 write_unlock_irq(&tasklist_lock);
 858         }
 859
 860         sig->group_exit_task = NULL;
 861         sig->notify_count = 0;
 862
 863 no_thread_group:
 864         exit_itimers(sig);
 865         flush_itimer_signals();
 866         if (leader)
 867                 release_task(leader);
 868
 869         if (atomic_read(&oldsighand->count) != 1) {
 870                 struct sighand_struct *newsighand;
 871                 /*
 872                  * This ->sighand is shared with the CLONE_SIGHAND
 873                  * but not CLONE_THREAD task, switch to the new one.
 874                  */
 875                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 876                 if (!newsighand)
 877                         return -ENOMEM;
 878
 879                 atomic_set(&newsighand->count, 1);
 880                 memcpy(newsighand->action, oldsighand->action,
 881                        sizeof(newsighand->action));
 882
 883                 write_lock_irq(&tasklist_lock);
 884                 spin_lock(&oldsighand->siglock);
 885                 rcu_assign_pointer(tsk->sighand, newsighand);
 886                 spin_unlock(&oldsighand->siglock);
 887                 write_unlock_irq(&tasklist_lock);
 888
 889                 __cleanup_sighand(oldsighand);
 890         }
 891
 892         BUG_ON(!thread_group_leader(tsk));
 893         return 0;
 894 }
 895
 896 /*
 897  * These functions flushes out all traces of the currently running executable
 898  * so that a new one can be started
 899  */
 900 static void flush_old_files(struct files_struct * files)
 901 {
 902         long j = -1;
 903         struct fdtable *fdt;
 904
 905         spin_lock(&files->file_lock);
 906         for (;;) {
 907                 unsigned long set, i;
 908
 909                 j++;
 910                 i = j * __NFDBITS;
 911                 fdt = files_fdtable(files);
 912                 if (i >= fdt->max_fds)
 913                         break;
 914                 set = fdt->close_on_exec->fds_bits[j];
 915                 if (!set)
 916                         continue;
 917                 fdt->close_on_exec->fds_bits[j] = 0;
 918                 spin_unlock(&files->file_lock);
 919                 for ( ; set ; i++,set >>= 1) {
 920                         if (set & 1) {
 921                                 sys_close(i);
 922                         }
 923                 }
 924                 spin_lock(&files->file_lock);
 925
 926         }
 927         spin_unlock(&files->file_lock);
 928 }
 929
 930 char *get_task_comm(char *buf, struct task_struct *tsk)
 931 {
 932         /* buf must be at least sizeof(tsk->comm) in size */
 933         task_lock(tsk);
 934         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 935         task_unlock(tsk);
 936         return buf;
 937 }
 938
 939 void set_task_comm(struct task_struct *tsk, char *buf)
 940 {
 941         task_lock(tsk);
 942         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 943         task_unlock(tsk);
 944 }
 945
 946 int flush_old_exec(struct linux_binprm * bprm)
 947 {
 948         char * name;
 949         int i, ch, retval;
 950         char tcomm[sizeof(current->comm)];
 951
 952         /*
 953          * Make sure we have a private signal table and that
 954          * we are unassociated from the previous thread group.
 955          */
 956         retval = de_thread(current);
 957         if (retval)
 958                 goto out;
 959
 960         set_mm_exe_file(bprm->mm, bprm->file);
 961
 962         /*
 963          * Release all of the old mmap stuff
 964          */
 965         retval = exec_mmap(bprm->mm);
 966         if (retval)
 967                 goto out;
 968
 969         bprm->mm = NULL;                /* We're using it now */
 970
 971         /* This is the point of no return */
 972         current->sas_ss_sp = current->sas_ss_size = 0;
 973
 974         if (current->euid == current->uid && current->egid == current->gid)
 975                 set_dumpable(current->mm, 1);
 976         else
 977                 set_dumpable(current->mm, suid_dumpable);
 978
 979         name = bprm->filename;
 980
 981         /* Copies the binary name from after last slash */
 982         for (i=0; (ch = *(name++)) != '\0';) {
 983                 if (ch == '/')
 984                         i = 0; /* overwrite what we wrote */
 985                 else
 986                         if (i < (sizeof(tcomm) - 1))
 987                                 tcomm[i++] = ch;
 988         }
 989         tcomm[i] = '\0';
 990         set_task_comm(current, tcomm);
 991
 992         current->flags &= ~PF_RANDOMIZE;
 993         flush_thread();
 994
 995         /* Set the new mm task size. We have to do that late because it may
 996          * depend on TIF_32BIT which is only updated in flush_thread() on
 997          * some architectures like powerpc
 998          */
 999         current->mm->task_size = TASK_SIZE;
1000
1001         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1002                 suid_keys(current);
1003                 set_dumpable(current->mm, suid_dumpable);
1004                 current->pdeath_signal = 0;
1005         } else if (file_permission(bprm->file, MAY_READ) ||
1006                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1007                 suid_keys(current);
1008                 set_dumpable(current->mm, suid_dumpable);
1009         }
1010
1011         /* An exec changes our domain. We are no longer part of the thread
1012            group */
1013
1014         current->self_exec_id++;
1015
1016         flush_signal_handlers(current, 0);
1017         flush_old_files(current->files);
1018
1019         return 0;
1020
1021 out:
1022         return retval;
1023 }
1024
1025 EXPORT_SYMBOL(flush_old_exec);
1026
1027 /*
1028  * Fill the binprm structure from the inode.
1029  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1030  */
1031 int prepare_binprm(struct linux_binprm *bprm)
1032 {
1033         int mode;
1034         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1035         int retval;
1036
1037         mode = inode->i_mode;
1038         if (bprm->file->f_op == NULL)
1039                 return -EACCES;
1040
1041         bprm->e_uid = current->euid;
1042         bprm->e_gid = current->egid;
1043
1044         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1045                 /* Set-uid? */
1046                 if (mode & S_ISUID) {
1047                         current->personality &= ~PER_CLEAR_ON_SETID;
1048                         bprm->e_uid = inode->i_uid;
1049                 }
1050
1051                 /* Set-gid? */
1052                 /*
1053                  * If setgid is set but no group execute bit then this
1054                  * is a candidate for mandatory locking, not a setgid
1055                  * executable.
1056                  */
1057                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1058                         current->personality &= ~PER_CLEAR_ON_SETID;
1059                         bprm->e_gid = inode->i_gid;
1060                 }
1061         }
1062
1063         /* fill in binprm security blob */
1064         retval = security_bprm_set(bprm);
1065         if (retval)
1066                 return retval;
1067
1068         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1069         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1070 }
1071
1072 EXPORT_SYMBOL(prepare_binprm);
1073
1074 static int unsafe_exec(struct task_struct *p)
1075 {
1076         int unsafe = 0;
1077         if (p->ptrace & PT_PTRACED) {
1078                 if (p->ptrace & PT_PTRACE_CAP)
1079                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
1080                 else
1081                         unsafe |= LSM_UNSAFE_PTRACE;
1082         }
1083         if (atomic_read(&p->fs->count) > 1 ||
1084             atomic_read(&p->files->count) > 1 ||
1085             atomic_read(&p->sighand->count) > 1)
1086                 unsafe |= LSM_UNSAFE_SHARE;
1087
1088         return unsafe;
1089 }
1090
1091 void compute_creds(struct linux_binprm *bprm)
1092 {
1093         int unsafe;
1094
1095         if (bprm->e_uid != current->uid) {
1096                 suid_keys(current);
1097                 current->pdeath_signal = 0;
1098         }
1099         exec_keys(current);
1100
1101         task_lock(current);
1102         unsafe = unsafe_exec(current);
1103         security_bprm_apply_creds(bprm, unsafe);
1104         task_unlock(current);
1105         security_bprm_post_apply_creds(bprm);
1106 }
1107 EXPORT_SYMBOL(compute_creds);
1108
1109 /*
1110  * Arguments are '\0' separated strings found at the location bprm->p
1111  * points to; chop off the first by relocating brpm->p to right after
1112  * the first '\0' encountered.
1113  */
1114 int remove_arg_zero(struct linux_binprm *bprm)
1115 {
1116         int ret = 0;
1117         unsigned long offset;
1118         char *kaddr;
1119         struct page *page;
1120
1121         if (!bprm->argc)
1122                 return 0;
1123
1124         do {
1125                 offset = bprm->p & ~PAGE_MASK;
1126                 page = get_arg_page(bprm, bprm->p, 0);
1127                 if (!page) {
1128                         ret = -EFAULT;
1129                         goto out;
1130                 }
1131                 kaddr = kmap_atomic(page, KM_USER0);
1132
1133                 for (; offset < PAGE_SIZE && kaddr[offset];
1134                                 offset++, bprm->p++)
1135                         ;
1136
1137                 kunmap_atomic(kaddr, KM_USER0);
1138                 put_arg_page(page);
1139
1140                 if (offset == PAGE_SIZE)
1141                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1142         } while (offset == PAGE_SIZE);
1143
1144         bprm->p++;
1145         bprm->argc--;
1146         ret = 0;
1147
1148 out:
1149         return ret;
1150 }
1151 EXPORT_SYMBOL(remove_arg_zero);
1152
1153 /*
1154  * cycle the list of binary formats handler, until one recognizes the image
1155  */
1156 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1157 {
1158         int try,retval;
1159         struct linux_binfmt *fmt;
1160 #ifdef __alpha__
1161         /* handle /sbin/loader.. */
1162         {
1163             struct exec * eh = (struct exec *) bprm->buf;
1164
1165             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1166                 (eh->fh.f_flags & 0x3000) == 0x3000)
1167             {
1168                 struct file * file;
1169                 unsigned long loader;
1170
1171                 allow_write_access(bprm->file);
1172                 fput(bprm->file);
1173                 bprm->file = NULL;
1174
1175                 loader = bprm->vma->vm_end - sizeof(void *);
1176
1177                 file = open_exec("/sbin/loader");
1178                 retval = PTR_ERR(file);
1179                 if (IS_ERR(file))
1180                         return retval;
1181
1182                 /* Remember if the application is TASO.  */
1183                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1184
1185                 bprm->file = file;
1186                 bprm->loader = loader;
1187                 retval = prepare_binprm(bprm);
1188                 if (retval<0)
1189                         return retval;
1190                 /* should call search_binary_handler recursively here,
1191                    but it does not matter */
1192             }
1193         }
1194 #endif
1195         retval = security_bprm_check(bprm);
1196         if (retval)
1197                 return retval;
1198
1199         /* kernel module loader fixup */
1200         /* so we don't try to load run modprobe in kernel space. */
1201         set_fs(USER_DS);
1202
1203         retval = audit_bprm(bprm);
1204         if (retval)
1205                 return retval;
1206
1207         retval = -ENOENT;
1208         for (try=0; try<2; try++) {
1209                 read_lock(&binfmt_lock);
1210                 list_for_each_entry(fmt, &formats, lh) {
1211                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1212                         if (!fn)
1213                                 continue;
1214                         if (!try_module_get(fmt->module))
1215                                 continue;
1216                         read_unlock(&binfmt_lock);
1217                         retval = fn(bprm, regs);
1218                         if (retval >= 0) {
1219                                 put_binfmt(fmt);
1220                                 allow_write_access(bprm->file);
1221                                 if (bprm->file)
1222                                         fput(bprm->file);
1223                                 bprm->file = NULL;
1224                                 current->did_exec = 1;
1225                                 proc_exec_connector(current);
1226                                 return retval;
1227                         }
1228                         read_lock(&binfmt_lock);
1229                         put_binfmt(fmt);
1230                         if (retval != -ENOEXEC || bprm->mm == NULL)
1231                                 break;
1232                         if (!bprm->file) {
1233                                 read_unlock(&binfmt_lock);
1234                                 return retval;
1235                         }
1236                 }
1237                 read_unlock(&binfmt_lock);
1238                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1239                         break;
1240 #ifdef CONFIG_KMOD
1241                 }else{
1242 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1243                         if (printable(bprm->buf[0]) &&
1244                             printable(bprm->buf[1]) &&
1245                             printable(bprm->buf[2]) &&
1246                             printable(bprm->buf[3]))
1247                                 break; /* -ENOEXEC */
1248                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1249 #endif
1250                 }
1251         }
1252         return retval;
1253 }
1254
1255 EXPORT_SYMBOL(search_binary_handler);
1256
1257 void free_bprm(struct linux_binprm *bprm)
1258 {
1259         free_arg_pages(bprm);
1260         kfree(bprm);
1261 }
1262
1263 /*
1264  * sys_execve() executes a new program.
1265  */
1266 int do_execve(char * filename,
1267         char __user *__user *argv,
1268         char __user *__user *envp,
1269         struct pt_regs * regs)
1270 {
1271         struct linux_binprm *bprm;
1272         struct file *file;
1273         struct files_struct *displaced;
1274         int retval;
1275
1276         retval = unshare_files(&displaced);
1277         if (retval)
1278                 goto out_ret;
1279
1280         retval = -ENOMEM;
1281         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1282         if (!bprm)
1283                 goto out_files;
1284
1285         file = open_exec(filename);
1286         retval = PTR_ERR(file);
1287         if (IS_ERR(file))
1288                 goto out_kfree;
1289
1290         sched_exec();
1291
1292         bprm->file = file;
1293         bprm->filename = filename;
1294         bprm->interp = filename;
1295
1296         retval = bprm_mm_init(bprm);
1297         if (retval)
1298                 goto out_file;
1299
1300         bprm->argc = count(argv, MAX_ARG_STRINGS);
1301         if ((retval = bprm->argc) < 0)
1302                 goto out_mm;
1303
1304         bprm->envc = count(envp, MAX_ARG_STRINGS);
1305         if ((retval = bprm->envc) < 0)
1306                 goto out_mm;
1307
1308         retval = security_bprm_alloc(bprm);
1309         if (retval)
1310                 goto out;
1311
1312         retval = prepare_binprm(bprm);
1313         if (retval < 0)
1314                 goto out;
1315
1316         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1317         if (retval < 0)
1318                 goto out;
1319
1320         bprm->exec = bprm->p;
1321         retval = copy_strings(bprm->envc, envp, bprm);
1322         if (retval < 0)
1323                 goto out;
1324
1325         retval = copy_strings(bprm->argc, argv, bprm);
1326         if (retval < 0)
1327                 goto out;
1328
1329         current->flags &= ~PF_KTHREAD;
1330         retval = search_binary_handler(bprm,regs);
1331         if (retval >= 0) {
1332                 /* execve success */
1333                 security_bprm_free(bprm);
1334                 acct_update_integrals(current);
1335                 free_bprm(bprm);
1336                 if (displaced)
1337                         put_files_struct(displaced);
1338                 return retval;
1339         }
1340
1341 out:
1342         if (bprm->security)
1343                 security_bprm_free(bprm);
1344
1345 out_mm:
1346         if (bprm->mm)
1347                 mmput (bprm->mm);
1348
1349 out_file:
1350         if (bprm->file) {
1351                 allow_write_access(bprm->file);
1352                 fput(bprm->file);
1353         }
1354 out_kfree:
1355         free_bprm(bprm);
1356
1357 out_files:
1358         if (displaced)
1359                 reset_files_struct(displaced);
1360 out_ret:
1361         return retval;
1362 }
1363
1364 int set_binfmt(struct linux_binfmt *new)
1365 {
1366         struct linux_binfmt *old = current->binfmt;
1367
1368         if (new) {
1369                 if (!try_module_get(new->module))
1370                         return -1;
1371         }
1372         current->binfmt = new;
1373         if (old)
1374                 module_put(old->module);
1375         return 0;
1376 }
1377
1378 EXPORT_SYMBOL(set_binfmt);
1379
1380 /* format_corename will inspect the pattern parameter, and output a
1381  * name into corename, which must have space for at least
1382  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1383  */
1384 static int format_corename(char *corename, const char *pattern, long signr)
1385 {
1386         const char *pat_ptr = pattern;
1387         char *out_ptr = corename;
1388         char *const out_end = corename + CORENAME_MAX_SIZE;
1389         int rc;
1390         int pid_in_pattern = 0;
1391         int ispipe = 0;
1392
1393         if (*pattern == '|')
1394                 ispipe = 1;
1395
1396         /* Repeat as long as we have more pattern to process and more output
1397            space */
1398         while (*pat_ptr) {
1399                 if (*pat_ptr != '%') {
1400                         if (out_ptr == out_end)
1401                                 goto out;
1402                         *out_ptr++ = *pat_ptr++;
1403                 } else {
1404                         switch (*++pat_ptr) {
1405                         case 0:
1406                                 goto out;
1407                         /* Double percent, output one percent */
1408                         case '%':
1409                                 if (out_ptr == out_end)
1410                                         goto out;
1411                                 *out_ptr++ = '%';
1412                                 break;
1413                         /* pid */
1414                         case 'p':
1415                                 pid_in_pattern = 1;
1416                                 rc = snprintf(out_ptr, out_end - out_ptr,
1417                                               "%d", task_tgid_vnr(current));
1418                                 if (rc > out_end - out_ptr)
1419                                         goto out;
1420                                 out_ptr += rc;
1421                                 break;
1422                         /* uid */
1423                         case 'u':
1424                                 rc = snprintf(out_ptr, out_end - out_ptr,
1425                                               "%d", current->uid);
1426                                 if (rc > out_end - out_ptr)
1427                                         goto out;
1428                                 out_ptr += rc;
1429                                 break;
1430                         /* gid */
1431                         case 'g':
1432                                 rc = snprintf(out_ptr, out_end - out_ptr,
1433                                               "%d", current->gid);
1434                                 if (rc > out_end - out_ptr)
1435                                         goto out;
1436                                 out_ptr += rc;
1437                                 break;
1438                         /* signal that caused the coredump */
1439                         case 's':
1440                                 rc = snprintf(out_ptr, out_end - out_ptr,
1441                                               "%ld", signr);
1442                                 if (rc > out_end - out_ptr)
1443                                         goto out;
1444                                 out_ptr += rc;
1445                                 break;
1446                         /* UNIX time of coredump */
1447                         case 't': {
1448                                 struct timeval tv;
1449                                 do_gettimeofday(&tv);
1450                                 rc = snprintf(out_ptr, out_end - out_ptr,
1451                                               "%lu", tv.tv_sec);
1452                                 if (rc > out_end - out_ptr)
1453                                         goto out;
1454                                 out_ptr += rc;
1455                                 break;
1456                         }
1457                         /* hostname */
1458                         case 'h':
1459                                 down_read(&uts_sem);
1460                                 rc = snprintf(out_ptr, out_end - out_ptr,
1461                                               "%s", utsname()->nodename);
1462                                 up_read(&uts_sem);
1463                                 if (rc > out_end - out_ptr)
1464                                         goto out;
1465                                 out_ptr += rc;
1466                                 break;
1467                         /* executable */
1468                         case 'e':
1469                                 rc = snprintf(out_ptr, out_end - out_ptr,
1470                                               "%s", current->comm);
1471                                 if (rc > out_end - out_ptr)
1472                                         goto out;
1473                                 out_ptr += rc;
1474                                 break;
1475                         /* core limit size */
1476                         case 'c':
1477                                 rc = snprintf(out_ptr, out_end - out_ptr,
1478                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1479                                 if (rc > out_end - out_ptr)
1480                                         goto out;
1481                                 out_ptr += rc;
1482                                 break;
1483                         default:
1484                                 break;
1485                         }
1486                         ++pat_ptr;
1487                 }
1488         }
1489         /* Backward compatibility with core_uses_pid:
1490          *
1491          * If core_pattern does not include a %p (as is the default)
1492          * and core_uses_pid is set, then .%pid will be appended to
1493          * the filename. Do not do this for piped commands. */
1494         if (!ispipe && !pid_in_pattern
1495             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1496                 rc = snprintf(out_ptr, out_end - out_ptr,
1497                               ".%d", task_tgid_vnr(current));
1498                 if (rc > out_end - out_ptr)
1499                         goto out;
1500                 out_ptr += rc;
1501         }
1502 out:
1503         *out_ptr = 0;
1504         return ispipe;
1505 }
1506
1507 static void zap_process(struct task_struct *start)
1508 {
1509         struct task_struct *t;
1510
1511         start->signal->flags = SIGNAL_GROUP_EXIT;
1512         start->signal->group_stop_count = 0;
1513
1514         t = start;
1515         do {
1516                 if (t != current && t->mm) {
1517                         t->mm->core_waiters++;
1518                         sigaddset(&t->pending.signal, SIGKILL);
1519                         signal_wake_up(t, 1);
1520                 }
1521         } while_each_thread(start, t);
1522 }
1523
1524 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1525                                 int exit_code)
1526 {
1527         struct task_struct *g, *p;
1528         unsigned long flags;
1529         int err = -EAGAIN;
1530
1531         spin_lock_irq(&tsk->sighand->siglock);
1532         if (!signal_group_exit(tsk->signal)) {
1533                 tsk->signal->group_exit_code = exit_code;
1534                 zap_process(tsk);
1535                 err = 0;
1536         }
1537         spin_unlock_irq(&tsk->sighand->siglock);
1538         if (err)
1539                 return err;
1540
1541         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1542                 goto done;
1543         /*
1544          * We should find and kill all tasks which use this mm, and we should
1545          * count them correctly into mm->core_waiters. We don't take tasklist
1546          * lock, but this is safe wrt:
1547          *
1548          * fork:
1549          *      None of sub-threads can fork after zap_process(leader). All
1550          *      processes which were created before this point should be
1551          *      visible to zap_threads() because copy_process() adds the new
1552          *      process to the tail of init_task.tasks list, and lock/unlock
1553          *      of ->siglock provides a memory barrier.
1554          *
1555          * do_exit:
1556          *      The caller holds mm->mmap_sem. This means that the task which
1557          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1558          *      its ->mm.
1559          *
1560          * de_thread:
1561          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1562          *      we must see either old or new leader, this does not matter.
1563          *      However, it can change p->sighand, so lock_task_sighand(p)
1564          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1565          *      it can't fail.
1566          *
1567          *      Note also that "g" can be the old leader with ->mm == NULL
1568          *      and already unhashed and thus removed from ->thread_group.
1569          *      This is OK, __unhash_process()->list_del_rcu() does not
1570          *      clear the ->next pointer, we will find the new leader via
1571          *      next_thread().
1572          */
1573         rcu_read_lock();
1574         for_each_process(g) {
1575                 if (g == tsk->group_leader)
1576                         continue;
1577
1578                 p = g;
1579                 do {
1580                         if (p->mm) {
1581                                 if (p->mm == mm) {
1582                                         lock_task_sighand(p, &flags);
1583                                         zap_process(p);
1584                                         unlock_task_sighand(p, &flags);
1585                                 }
1586                                 break;
1587                         }
1588                 } while_each_thread(g, p);
1589         }
1590         rcu_read_unlock();
1591 done:
1592         return mm->core_waiters;
1593 }
1594
1595 static int coredump_wait(int exit_code)
1596 {
1597         struct task_struct *tsk = current;
1598         struct mm_struct *mm = tsk->mm;
1599         struct completion startup_done;
1600         struct completion *vfork_done;
1601         int core_waiters;
1602
1603         init_completion(&mm->core_done);
1604         init_completion(&startup_done);
1605         mm->core_startup_done = &startup_done;
1606
1607         core_waiters = zap_threads(tsk, mm, exit_code);
1608         up_write(&mm->mmap_sem);
1609
1610         if (unlikely(core_waiters < 0))
1611                 goto fail;
1612
1613         /*
1614          * Make sure nobody is waiting for us to release the VM,
1615          * otherwise we can deadlock when we wait on each other
1616          */
1617         vfork_done = tsk->vfork_done;
1618         if (vfork_done) {
1619                 tsk->vfork_done = NULL;
1620                 complete(vfork_done);
1621         }
1622
1623         if (core_waiters)
1624                 wait_for_completion(&startup_done);
1625 fail:
1626         BUG_ON(mm->core_waiters);
1627         return core_waiters;
1628 }
1629
1630 /*
1631  * set_dumpable converts traditional three-value dumpable to two flags and
1632  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1633  * these bits are not changed atomically.  So get_dumpable can observe the
1634  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1635  * return either old dumpable or new one by paying attention to the order of
1636  * modifying the bits.
1637  *
1638  * dumpable |   mm->flags (binary)
1639  * old  new | initial interim  final
1640  * ---------+-----------------------
1641  *  0    1  |   00      01      01
1642  *  0    2  |   00      10(*)   11
1643  *  1    0  |   01      00      00
1644  *  1    2  |   01      11      11
1645  *  2    0  |   11      10(*)   00
1646  *  2    1  |   11      11      01
1647  *
1648  * (*) get_dumpable regards interim value of 10 as 11.
1649  */
1650 void set_dumpable(struct mm_struct *mm, int value)
1651 {
1652         switch (value) {
1653         case 0:
1654                 clear_bit(MMF_DUMPABLE, &mm->flags);
1655                 smp_wmb();
1656                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1657                 break;
1658         case 1:
1659                 set_bit(MMF_DUMPABLE, &mm->flags);
1660                 smp_wmb();
1661                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1662                 break;
1663         case 2:
1664                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1665                 smp_wmb();
1666                 set_bit(MMF_DUMPABLE, &mm->flags);
1667                 break;
1668         }
1669 }
1670
1671 int get_dumpable(struct mm_struct *mm)
1672 {
1673         int ret;
1674
1675         ret = mm->flags & 0x3;
1676         return (ret >= 2) ? 2 : ret;
1677 }
1678
1679 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1680 {
1681         char corename[CORENAME_MAX_SIZE + 1];
1682         struct mm_struct *mm = current->mm;
1683         struct linux_binfmt * binfmt;
1684         struct inode * inode;
1685         struct file * file;
1686         int retval = 0;
1687         int fsuid = current->fsuid;
1688         int flag = 0;
1689         int ispipe = 0;
1690         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1691         char **helper_argv = NULL;
1692         int helper_argc = 0;
1693         char *delimit;
1694
1695         audit_core_dumps(signr);
1696
1697         binfmt = current->binfmt;
1698         if (!binfmt || !binfmt->core_dump)
1699                 goto fail;
1700         down_write(&mm->mmap_sem);
1701         /*
1702          * If another thread got here first, or we are not dumpable, bail out.
1703          */
1704         if (mm->core_waiters || !get_dumpable(mm)) {
1705                 up_write(&mm->mmap_sem);
1706                 goto fail;
1707         }
1708
1709         /*
1710          *      We cannot trust fsuid as being the "true" uid of the
1711          *      process nor do we know its entire history. We only know it
1712          *      was tainted so we dump it as root in mode 2.
1713          */
1714         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1715                 flag = O_EXCL;          /* Stop rewrite attacks */
1716                 current->fsuid = 0;     /* Dump root private */
1717         }
1718
1719         retval = coredump_wait(exit_code);
1720         if (retval < 0)
1721                 goto fail;
1722
1723         /*
1724          * Clear any false indication of pending signals that might
1725          * be seen by the filesystem code called to write the core file.
1726          */
1727         clear_thread_flag(TIF_SIGPENDING);
1728
1729         /*
1730          * lock_kernel() because format_corename() is controlled by sysctl, which
1731          * uses lock_kernel()
1732          */
1733         lock_kernel();
1734         ispipe = format_corename(corename, core_pattern, signr);
1735         unlock_kernel();
1736         /*
1737          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1738          * to a pipe.  Since we're not writing directly to the filesystem
1739          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1740          * created unless the pipe reader choses to write out the core file
1741          * at which point file size limits and permissions will be imposed
1742          * as it does with any other process
1743          */
1744         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1745                 goto fail_unlock;
1746
1747         if (ispipe) {
1748                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1749                 /* Terminate the string before the first option */
1750                 delimit = strchr(corename, ' ');
1751                 if (delimit)
1752                         *delimit = '\0';
1753                 delimit = strrchr(helper_argv[0], '/');
1754                 if (delimit)
1755                         delimit++;
1756                 else
1757                         delimit = helper_argv[0];
1758                 if (!strcmp(delimit, current->comm)) {
1759                         printk(KERN_NOTICE "Recursive core dump detected, "
1760                                         "aborting\n");
1761                         goto fail_unlock;
1762                 }
1763
1764                 core_limit = RLIM_INFINITY;
1765
1766                 /* SIGPIPE can happen, but it's just never processed */
1767                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1768                                 &file)) {
1769                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1770                                corename);
1771                         goto fail_unlock;
1772                 }
1773         } else
1774                 file = filp_open(corename,
1775                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1776                                  0600);
1777         if (IS_ERR(file))
1778                 goto fail_unlock;
1779         inode = file->f_path.dentry->d_inode;
1780         if (inode->i_nlink > 1)
1781                 goto close_fail;        /* multiple links - don't dump */
1782         if (!ispipe && d_unhashed(file->f_path.dentry))
1783                 goto close_fail;
1784
1785         /* AK: actually i see no reason to not allow this for named pipes etc.,
1786            but keep the previous behaviour for now. */
1787         if (!ispipe && !S_ISREG(inode->i_mode))
1788                 goto close_fail;
1789         /*
1790          * Dont allow local users get cute and trick others to coredump
1791          * into their pre-created files:
1792          */
1793         if (inode->i_uid != current->fsuid)
1794                 goto close_fail;
1795         if (!file->f_op)
1796                 goto close_fail;
1797         if (!file->f_op->write)
1798                 goto close_fail;
1799         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1800                 goto close_fail;
1801
1802         retval = binfmt->core_dump(signr, regs, file, core_limit);
1803
1804         if (retval)
1805                 current->signal->group_exit_code |= 0x80;
1806 close_fail:
1807         filp_close(file, NULL);
1808 fail_unlock:
1809         if (helper_argv)
1810                 argv_free(helper_argv);
1811
1812         current->fsuid = fsuid;
1813         complete_all(&mm->core_done);
1814 fail:
1815         return retval;
1816 }