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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/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/pagemap.h>
  36 #include <linux/highmem.h>
  37 #include <linux/spinlock.h>
  38 #include <linux/key.h>
  39 #include <linux/personality.h>
  40 #include <linux/binfmts.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/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 #include <linux/tracehook.h>
  53
  54 #include <asm/uaccess.h>
  55 #include <asm/mmu_context.h>
  56 #include <asm/tlb.h>
  57
  58 #ifdef CONFIG_KMOD
  59 #include <linux/kmod.h>
  60 #endif
  61
  62 #ifdef __alpha__
  63 /* for /sbin/loader handling in search_binary_handler() */
  64 #include <linux/a.out.h>
  65 #endif
  66
  67 int core_uses_pid;
  68 char core_pattern[CORENAME_MAX_SIZE] = "core";
  69 int suid_dumpable = 0;
  70
  71 /* The maximal length of core_pattern is also specified in sysctl.c */
  72
  73 static LIST_HEAD(formats);
  74 static DEFINE_RWLOCK(binfmt_lock);
  75
  76 int register_binfmt(struct linux_binfmt * fmt)
  77 {
  78         if (!fmt)
  79                 return -EINVAL;
  80         write_lock(&binfmt_lock);
  81         list_add(&fmt->lh, &formats);
  82         write_unlock(&binfmt_lock);
  83         return 0;
  84 }
  85
  86 EXPORT_SYMBOL(register_binfmt);
  87
  88 void unregister_binfmt(struct linux_binfmt * fmt)
  89 {
  90         write_lock(&binfmt_lock);
  91         list_del(&fmt->lh);
  92         write_unlock(&binfmt_lock);
  93 }
  94
  95 EXPORT_SYMBOL(unregister_binfmt);
  96
  97 static inline void put_binfmt(struct linux_binfmt * fmt)
  98 {
  99         module_put(fmt->module);
 100 }
 101
 102 /*
 103  * Note that a shared library must be both readable and executable due to
 104  * security reasons.
 105  *
 106  * Also note that we take the address to load from from the file itself.
 107  */
 108 asmlinkage long sys_uselib(const char __user * library)
 109 {
 110         struct file *file;
 111         struct nameidata nd;
 112         char *tmp = getname(library);
 113         int error = PTR_ERR(tmp);
 114
 115         if (!IS_ERR(tmp)) {
 116                 error = path_lookup_open(AT_FDCWD, tmp,
 117                                          LOOKUP_FOLLOW, &nd,
 118                                          FMODE_READ|FMODE_EXEC);
 119                 putname(tmp);
 120         }
 121         if (error)
 122                 goto out;
 123
 124         error = -EINVAL;
 125         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 126                 goto exit;
 127
 128         error = -EACCES;
 129         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 130                 goto exit;
 131
 132         error = vfs_permission(&nd, MAY_READ | MAY_EXEC | MAY_OPEN);
 133         if (error)
 134                 goto exit;
 135
 136         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 137         error = PTR_ERR(file);
 138         if (IS_ERR(file))
 139                 goto out;
 140
 141         error = -ENOEXEC;
 142         if(file->f_op) {
 143                 struct linux_binfmt * fmt;
 144
 145                 read_lock(&binfmt_lock);
 146                 list_for_each_entry(fmt, &formats, lh) {
 147                         if (!fmt->load_shlib)
 148                                 continue;
 149                         if (!try_module_get(fmt->module))
 150                                 continue;
 151                         read_unlock(&binfmt_lock);
 152                         error = fmt->load_shlib(file);
 153                         read_lock(&binfmt_lock);
 154                         put_binfmt(fmt);
 155                         if (error != -ENOEXEC)
 156                                 break;
 157                 }
 158                 read_unlock(&binfmt_lock);
 159         }
 160         fput(file);
 161 out:
 162         return error;
 163 exit:
 164         release_open_intent(&nd);
 165         path_put(&nd.path);
 166         goto out;
 167 }
 168
 169 #ifdef CONFIG_MMU
 170
 171 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 172                 int write)
 173 {
 174         struct page *page;
 175         int ret;
 176
 177 #ifdef CONFIG_STACK_GROWSUP
 178         if (write) {
 179                 ret = expand_stack_downwards(bprm->vma, pos);
 180                 if (ret < 0)
 181                         return NULL;
 182         }
 183 #endif
 184         ret = get_user_pages(current, bprm->mm, pos,
 185                         1, write, 1, &page, NULL);
 186         if (ret <= 0)
 187                 return NULL;
 188
 189         if (write) {
 190                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 191                 struct rlimit *rlim;
 192
 193                 /*
 194                  * We've historically supported up to 32 pages (ARG_MAX)
 195                  * of argument strings even with small stacks
 196                  */
 197                 if (size <= ARG_MAX)
 198                         return page;
 199
 200                 /*
 201                  * Limit to 1/4-th the stack size for the argv+env strings.
 202                  * This ensures that:
 203                  *  - the remaining binfmt code will not run out of stack space,
 204                  *  - the program will have a reasonable amount of stack left
 205                  *    to work from.
 206                  */
 207                 rlim = current->signal->rlim;
 208                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 209                         put_page(page);
 210                         return NULL;
 211                 }
 212         }
 213
 214         return page;
 215 }
 216
 217 static void put_arg_page(struct page *page)
 218 {
 219         put_page(page);
 220 }
 221
 222 static void free_arg_page(struct linux_binprm *bprm, int i)
 223 {
 224 }
 225
 226 static void free_arg_pages(struct linux_binprm *bprm)
 227 {
 228 }
 229
 230 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 231                 struct page *page)
 232 {
 233         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 234 }
 235
 236 static int __bprm_mm_init(struct linux_binprm *bprm)
 237 {
 238         int err = -ENOMEM;
 239         struct vm_area_struct *vma = NULL;
 240         struct mm_struct *mm = bprm->mm;
 241
 242         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 243         if (!vma)
 244                 goto err;
 245
 246         down_write(&mm->mmap_sem);
 247         vma->vm_mm = mm;
 248
 249         /*
 250          * Place the stack at the largest stack address the architecture
 251          * supports. Later, we'll move this to an appropriate place. We don't
 252          * use STACK_TOP because that can depend on attributes which aren't
 253          * configured yet.
 254          */
 255         vma->vm_end = STACK_TOP_MAX;
 256         vma->vm_start = vma->vm_end - PAGE_SIZE;
 257
 258         vma->vm_flags = VM_STACK_FLAGS;
 259         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 260         err = insert_vm_struct(mm, vma);
 261         if (err) {
 262                 up_write(&mm->mmap_sem);
 263                 goto err;
 264         }
 265
 266         mm->stack_vm = mm->total_vm = 1;
 267         up_write(&mm->mmap_sem);
 268
 269         bprm->p = vma->vm_end - sizeof(void *);
 270
 271         return 0;
 272
 273 err:
 274         if (vma) {
 275                 bprm->vma = NULL;
 276                 kmem_cache_free(vm_area_cachep, vma);
 277         }
 278
 279         return err;
 280 }
 281
 282 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 283 {
 284         return len <= MAX_ARG_STRLEN;
 285 }
 286
 287 #else
 288
 289 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 290                 int write)
 291 {
 292         struct page *page;
 293
 294         page = bprm->page[pos / PAGE_SIZE];
 295         if (!page && write) {
 296                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 297                 if (!page)
 298                         return NULL;
 299                 bprm->page[pos / PAGE_SIZE] = page;
 300         }
 301
 302         return page;
 303 }
 304
 305 static void put_arg_page(struct page *page)
 306 {
 307 }
 308
 309 static void free_arg_page(struct linux_binprm *bprm, int i)
 310 {
 311         if (bprm->page[i]) {
 312                 __free_page(bprm->page[i]);
 313                 bprm->page[i] = NULL;
 314         }
 315 }
 316
 317 static void free_arg_pages(struct linux_binprm *bprm)
 318 {
 319         int i;
 320
 321         for (i = 0; i < MAX_ARG_PAGES; i++)
 322                 free_arg_page(bprm, i);
 323 }
 324
 325 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 326                 struct page *page)
 327 {
 328 }
 329
 330 static int __bprm_mm_init(struct linux_binprm *bprm)
 331 {
 332         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 333         return 0;
 334 }
 335
 336 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 337 {
 338         return len <= bprm->p;
 339 }
 340
 341 #endif /* CONFIG_MMU */
 342
 343 /*
 344  * Create a new mm_struct and populate it with a temporary stack
 345  * vm_area_struct.  We don't have enough context at this point to set the stack
 346  * flags, permissions, and offset, so we use temporary values.  We'll update
 347  * them later in setup_arg_pages().
 348  */
 349 int bprm_mm_init(struct linux_binprm *bprm)
 350 {
 351         int err;
 352         struct mm_struct *mm = NULL;
 353
 354         bprm->mm = mm = mm_alloc();
 355         err = -ENOMEM;
 356         if (!mm)
 357                 goto err;
 358
 359         err = init_new_context(current, mm);
 360         if (err)
 361                 goto err;
 362
 363         err = __bprm_mm_init(bprm);
 364         if (err)
 365                 goto err;
 366
 367         return 0;
 368
 369 err:
 370         if (mm) {
 371                 bprm->mm = NULL;
 372                 mmdrop(mm);
 373         }
 374
 375         return err;
 376 }
 377
 378 /*
 379  * count() counts the number of strings in array ARGV.
 380  */
 381 static int count(char __user * __user * argv, int max)
 382 {
 383         int i = 0;
 384
 385         if (argv != NULL) {
 386                 for (;;) {
 387                         char __user * p;
 388
 389                         if (get_user(p, argv))
 390                                 return -EFAULT;
 391                         if (!p)
 392                                 break;
 393                         argv++;
 394                         if (i++ >= max)
 395                                 return -E2BIG;
 396                         cond_resched();
 397                 }
 398         }
 399         return i;
 400 }
 401
 402 /*
 403  * 'copy_strings()' copies argument/environment strings from the old
 404  * processes's memory to the new process's stack.  The call to get_user_pages()
 405  * ensures the destination page is created and not swapped out.
 406  */
 407 static int copy_strings(int argc, char __user * __user * argv,
 408                         struct linux_binprm *bprm)
 409 {
 410         struct page *kmapped_page = NULL;
 411         char *kaddr = NULL;
 412         unsigned long kpos = 0;
 413         int ret;
 414
 415         while (argc-- > 0) {
 416                 char __user *str;
 417                 int len;
 418                 unsigned long pos;
 419
 420                 if (get_user(str, argv+argc) ||
 421                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 422                         ret = -EFAULT;
 423                         goto out;
 424                 }
 425
 426                 if (!valid_arg_len(bprm, len)) {
 427                         ret = -E2BIG;
 428                         goto out;
 429                 }
 430
 431                 /* We're going to work our way backwords. */
 432                 pos = bprm->p;
 433                 str += len;
 434                 bprm->p -= len;
 435
 436                 while (len > 0) {
 437                         int offset, bytes_to_copy;
 438
 439                         offset = pos % PAGE_SIZE;
 440                         if (offset == 0)
 441                                 offset = PAGE_SIZE;
 442
 443                         bytes_to_copy = offset;
 444                         if (bytes_to_copy > len)
 445                                 bytes_to_copy = len;
 446
 447                         offset -= bytes_to_copy;
 448                         pos -= bytes_to_copy;
 449                         str -= bytes_to_copy;
 450                         len -= bytes_to_copy;
 451
 452                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 453                                 struct page *page;
 454
 455                                 page = get_arg_page(bprm, pos, 1);
 456                                 if (!page) {
 457                                         ret = -E2BIG;
 458                                         goto out;
 459                                 }
 460
 461                                 if (kmapped_page) {
 462                                         flush_kernel_dcache_page(kmapped_page);
 463                                         kunmap(kmapped_page);
 464                                         put_arg_page(kmapped_page);
 465                                 }
 466                                 kmapped_page = page;
 467                                 kaddr = kmap(kmapped_page);
 468                                 kpos = pos & PAGE_MASK;
 469                                 flush_arg_page(bprm, kpos, kmapped_page);
 470                         }
 471                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 472                                 ret = -EFAULT;
 473                                 goto out;
 474                         }
 475                 }
 476         }
 477         ret = 0;
 478 out:
 479         if (kmapped_page) {
 480                 flush_kernel_dcache_page(kmapped_page);
 481                 kunmap(kmapped_page);
 482                 put_arg_page(kmapped_page);
 483         }
 484         return ret;
 485 }
 486
 487 /*
 488  * Like copy_strings, but get argv and its values from kernel memory.
 489  */
 490 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 491 {
 492         int r;
 493         mm_segment_t oldfs = get_fs();
 494         set_fs(KERNEL_DS);
 495         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 496         set_fs(oldfs);
 497         return r;
 498 }
 499 EXPORT_SYMBOL(copy_strings_kernel);
 500
 501 #ifdef CONFIG_MMU
 502
 503 /*
 504  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 505  * the binfmt code determines where the new stack should reside, we shift it to
 506  * its final location.  The process proceeds as follows:
 507  *
 508  * 1) Use shift to calculate the new vma endpoints.
 509  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 510  *    arguments passed to subsequent functions are consistent.
 511  * 3) Move vma's page tables to the new range.
 512  * 4) Free up any cleared pgd range.
 513  * 5) Shrink the vma to cover only the new range.
 514  */
 515 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 516 {
 517         struct mm_struct *mm = vma->vm_mm;
 518         unsigned long old_start = vma->vm_start;
 519         unsigned long old_end = vma->vm_end;
 520         unsigned long length = old_end - old_start;
 521         unsigned long new_start = old_start - shift;
 522         unsigned long new_end = old_end - shift;
 523         struct mmu_gather *tlb;
 524
 525         BUG_ON(new_start > new_end);
 526
 527         /*
 528          * ensure there are no vmas between where we want to go
 529          * and where we are
 530          */
 531         if (vma != find_vma(mm, new_start))
 532                 return -EFAULT;
 533
 534         /*
 535          * cover the whole range: [new_start, old_end)
 536          */
 537         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 538
 539         /*
 540          * move the page tables downwards, on failure we rely on
 541          * process cleanup to remove whatever mess we made.
 542          */
 543         if (length != move_page_tables(vma, old_start,
 544                                        vma, new_start, length))
 545                 return -ENOMEM;
 546
 547         lru_add_drain();
 548         tlb = tlb_gather_mmu(mm, 0);
 549         if (new_end > old_start) {
 550                 /*
 551                  * when the old and new regions overlap clear from new_end.
 552                  */
 553                 free_pgd_range(tlb, new_end, old_end, new_end,
 554                         vma->vm_next ? vma->vm_next->vm_start : 0);
 555         } else {
 556                 /*
 557                  * otherwise, clean from old_start; this is done to not touch
 558                  * the address space in [new_end, old_start) some architectures
 559                  * have constraints on va-space that make this illegal (IA64) -
 560                  * for the others its just a little faster.
 561                  */
 562                 free_pgd_range(tlb, old_start, old_end, new_end,
 563                         vma->vm_next ? vma->vm_next->vm_start : 0);
 564         }
 565         tlb_finish_mmu(tlb, new_end, old_end);
 566
 567         /*
 568          * shrink the vma to just the new range.
 569          */
 570         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 571
 572         return 0;
 573 }
 574
 575 #define EXTRA_STACK_VM_PAGES    20      /* random */
 576
 577 /*
 578  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 579  * the stack is optionally relocated, and some extra space is added.
 580  */
 581 int setup_arg_pages(struct linux_binprm *bprm,
 582                     unsigned long stack_top,
 583                     int executable_stack)
 584 {
 585         unsigned long ret;
 586         unsigned long stack_shift;
 587         struct mm_struct *mm = current->mm;
 588         struct vm_area_struct *vma = bprm->vma;
 589         struct vm_area_struct *prev = NULL;
 590         unsigned long vm_flags;
 591         unsigned long stack_base;
 592
 593 #ifdef CONFIG_STACK_GROWSUP
 594         /* Limit stack size to 1GB */
 595         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 596         if (stack_base > (1 << 30))
 597                 stack_base = 1 << 30;
 598
 599         /* Make sure we didn't let the argument array grow too large. */
 600         if (vma->vm_end - vma->vm_start > stack_base)
 601                 return -ENOMEM;
 602
 603         stack_base = PAGE_ALIGN(stack_top - stack_base);
 604
 605         stack_shift = vma->vm_start - stack_base;
 606         mm->arg_start = bprm->p - stack_shift;
 607         bprm->p = vma->vm_end - stack_shift;
 608 #else
 609         stack_top = arch_align_stack(stack_top);
 610         stack_top = PAGE_ALIGN(stack_top);
 611         stack_shift = vma->vm_end - stack_top;
 612
 613         bprm->p -= stack_shift;
 614         mm->arg_start = bprm->p;
 615 #endif
 616
 617         if (bprm->loader)
 618                 bprm->loader -= stack_shift;
 619         bprm->exec -= stack_shift;
 620
 621         down_write(&mm->mmap_sem);
 622         vm_flags = VM_STACK_FLAGS;
 623
 624         /*
 625          * Adjust stack execute permissions; explicitly enable for
 626          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 627          * (arch default) otherwise.
 628          */
 629         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 630                 vm_flags |= VM_EXEC;
 631         else if (executable_stack == EXSTACK_DISABLE_X)
 632                 vm_flags &= ~VM_EXEC;
 633         vm_flags |= mm->def_flags;
 634
 635         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 636                         vm_flags);
 637         if (ret)
 638                 goto out_unlock;
 639         BUG_ON(prev != vma);
 640
 641         /* Move stack pages down in memory. */
 642         if (stack_shift) {
 643                 ret = shift_arg_pages(vma, stack_shift);
 644                 if (ret) {
 645                         up_write(&mm->mmap_sem);
 646                         return ret;
 647                 }
 648         }
 649
 650 #ifdef CONFIG_STACK_GROWSUP
 651         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 652 #else
 653         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 654 #endif
 655         ret = expand_stack(vma, stack_base);
 656         if (ret)
 657                 ret = -EFAULT;
 658
 659 out_unlock:
 660         up_write(&mm->mmap_sem);
 661         return 0;
 662 }
 663 EXPORT_SYMBOL(setup_arg_pages);
 664
 665 #endif /* CONFIG_MMU */
 666
 667 struct file *open_exec(const char *name)
 668 {
 669         struct nameidata nd;
 670         struct file *file;
 671         int err;
 672
 673         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
 674                                 FMODE_READ|FMODE_EXEC);
 675         if (err)
 676                 goto out;
 677
 678         err = -EACCES;
 679         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 680                 goto out_path_put;
 681
 682         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 683                 goto out_path_put;
 684
 685         err = vfs_permission(&nd, MAY_EXEC | MAY_OPEN);
 686         if (err)
 687                 goto out_path_put;
 688
 689         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 690         if (IS_ERR(file))
 691                 return file;
 692
 693         err = deny_write_access(file);
 694         if (err) {
 695                 fput(file);
 696                 goto out;
 697         }
 698
 699         return file;
 700
 701  out_path_put:
 702         release_open_intent(&nd);
 703         path_put(&nd.path);
 704  out:
 705         return ERR_PTR(err);
 706 }
 707 EXPORT_SYMBOL(open_exec);
 708
 709 int kernel_read(struct file *file, unsigned long offset,
 710         char *addr, unsigned long count)
 711 {
 712         mm_segment_t old_fs;
 713         loff_t pos = offset;
 714         int result;
 715
 716         old_fs = get_fs();
 717         set_fs(get_ds());
 718         /* The cast to a user pointer is valid due to the set_fs() */
 719         result = vfs_read(file, (void __user *)addr, count, &pos);
 720         set_fs(old_fs);
 721         return result;
 722 }
 723
 724 EXPORT_SYMBOL(kernel_read);
 725
 726 static int exec_mmap(struct mm_struct *mm)
 727 {
 728         struct task_struct *tsk;
 729         struct mm_struct * old_mm, *active_mm;
 730
 731         /* Notify parent that we're no longer interested in the old VM */
 732         tsk = current;
 733         old_mm = current->mm;
 734         mm_release(tsk, old_mm);
 735
 736         if (old_mm) {
 737                 /*
 738                  * Make sure that if there is a core dump in progress
 739                  * for the old mm, we get out and die instead of going
 740                  * through with the exec.  We must hold mmap_sem around
 741                  * checking core_state and changing tsk->mm.
 742                  */
 743                 down_read(&old_mm->mmap_sem);
 744                 if (unlikely(old_mm->core_state)) {
 745                         up_read(&old_mm->mmap_sem);
 746                         return -EINTR;
 747                 }
 748         }
 749         task_lock(tsk);
 750         active_mm = tsk->active_mm;
 751         tsk->mm = mm;
 752         tsk->active_mm = mm;
 753         activate_mm(active_mm, mm);
 754         task_unlock(tsk);
 755         arch_pick_mmap_layout(mm);
 756         if (old_mm) {
 757                 up_read(&old_mm->mmap_sem);
 758                 BUG_ON(active_mm != old_mm);
 759                 mm_update_next_owner(old_mm);
 760                 mmput(old_mm);
 761                 return 0;
 762         }
 763         mmdrop(active_mm);
 764         return 0;
 765 }
 766
 767 /*
 768  * This function makes sure the current process has its own signal table,
 769  * so that flush_signal_handlers can later reset the handlers without
 770  * disturbing other processes.  (Other processes might share the signal
 771  * table via the CLONE_SIGHAND option to clone().)
 772  */
 773 static int de_thread(struct task_struct *tsk)
 774 {
 775         struct signal_struct *sig = tsk->signal;
 776         struct sighand_struct *oldsighand = tsk->sighand;
 777         spinlock_t *lock = &oldsighand->siglock;
 778         struct task_struct *leader = NULL;
 779         int count;
 780
 781         if (thread_group_empty(tsk))
 782                 goto no_thread_group;
 783
 784         /*
 785          * Kill all other threads in the thread group.
 786          */
 787         spin_lock_irq(lock);
 788         if (signal_group_exit(sig)) {
 789                 /*
 790                  * Another group action in progress, just
 791                  * return so that the signal is processed.
 792                  */
 793                 spin_unlock_irq(lock);
 794                 return -EAGAIN;
 795         }
 796         sig->group_exit_task = tsk;
 797         zap_other_threads(tsk);
 798
 799         /* Account for the thread group leader hanging around: */
 800         count = thread_group_leader(tsk) ? 1 : 2;
 801         sig->notify_count = count;
 802         while (atomic_read(&sig->count) > count) {
 803                 __set_current_state(TASK_UNINTERRUPTIBLE);
 804                 spin_unlock_irq(lock);
 805                 schedule();
 806                 spin_lock_irq(lock);
 807         }
 808         spin_unlock_irq(lock);
 809
 810         /*
 811          * At this point all other threads have exited, all we have to
 812          * do is to wait for the thread group leader to become inactive,
 813          * and to assume its PID:
 814          */
 815         if (!thread_group_leader(tsk)) {
 816                 leader = tsk->group_leader;
 817
 818                 sig->notify_count = -1; /* for exit_notify() */
 819                 for (;;) {
 820                         write_lock_irq(&tasklist_lock);
 821                         if (likely(leader->exit_state))
 822                                 break;
 823                         __set_current_state(TASK_UNINTERRUPTIBLE);
 824                         write_unlock_irq(&tasklist_lock);
 825                         schedule();
 826                 }
 827
 828                 /*
 829                  * The only record we have of the real-time age of a
 830                  * process, regardless of execs it's done, is start_time.
 831                  * All the past CPU time is accumulated in signal_struct
 832                  * from sister threads now dead.  But in this non-leader
 833                  * exec, nothing survives from the original leader thread,
 834                  * whose birth marks the true age of this process now.
 835                  * When we take on its identity by switching to its PID, we
 836                  * also take its birthdate (always earlier than our own).
 837                  */
 838                 tsk->start_time = leader->start_time;
 839
 840                 BUG_ON(!same_thread_group(leader, tsk));
 841                 BUG_ON(has_group_leader_pid(tsk));
 842                 /*
 843                  * An exec() starts a new thread group with the
 844                  * TGID of the previous thread group. Rehash the
 845                  * two threads with a switched PID, and release
 846                  * the former thread group leader:
 847                  */
 848
 849                 /* Become a process group leader with the old leader's pid.
 850                  * The old leader becomes a thread of the this thread group.
 851                  * Note: The old leader also uses this pid until release_task
 852                  *       is called.  Odd but simple and correct.
 853                  */
 854                 detach_pid(tsk, PIDTYPE_PID);
 855                 tsk->pid = leader->pid;
 856                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 857                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 858                 transfer_pid(leader, tsk, PIDTYPE_SID);
 859                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 860
 861                 tsk->group_leader = tsk;
 862                 leader->group_leader = tsk;
 863
 864                 tsk->exit_signal = SIGCHLD;
 865
 866                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 867                 leader->exit_state = EXIT_DEAD;
 868
 869                 write_unlock_irq(&tasklist_lock);
 870         }
 871
 872         sig->group_exit_task = NULL;
 873         sig->notify_count = 0;
 874
 875 no_thread_group:
 876         exit_itimers(sig);
 877         flush_itimer_signals();
 878         if (leader)
 879                 release_task(leader);
 880
 881         if (atomic_read(&oldsighand->count) != 1) {
 882                 struct sighand_struct *newsighand;
 883                 /*
 884                  * This ->sighand is shared with the CLONE_SIGHAND
 885                  * but not CLONE_THREAD task, switch to the new one.
 886                  */
 887                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 888                 if (!newsighand)
 889                         return -ENOMEM;
 890
 891                 atomic_set(&newsighand->count, 1);
 892                 memcpy(newsighand->action, oldsighand->action,
 893                        sizeof(newsighand->action));
 894
 895                 write_lock_irq(&tasklist_lock);
 896                 spin_lock(&oldsighand->siglock);
 897                 rcu_assign_pointer(tsk->sighand, newsighand);
 898                 spin_unlock(&oldsighand->siglock);
 899                 write_unlock_irq(&tasklist_lock);
 900
 901                 __cleanup_sighand(oldsighand);
 902         }
 903
 904         BUG_ON(!thread_group_leader(tsk));
 905         return 0;
 906 }
 907
 908 /*
 909  * These functions flushes out all traces of the currently running executable
 910  * so that a new one can be started
 911  */
 912 static void flush_old_files(struct files_struct * files)
 913 {
 914         long j = -1;
 915         struct fdtable *fdt;
 916
 917         spin_lock(&files->file_lock);
 918         for (;;) {
 919                 unsigned long set, i;
 920
 921                 j++;
 922                 i = j * __NFDBITS;
 923                 fdt = files_fdtable(files);
 924                 if (i >= fdt->max_fds)
 925                         break;
 926                 set = fdt->close_on_exec->fds_bits[j];
 927                 if (!set)
 928                         continue;
 929                 fdt->close_on_exec->fds_bits[j] = 0;
 930                 spin_unlock(&files->file_lock);
 931                 for ( ; set ; i++,set >>= 1) {
 932                         if (set & 1) {
 933                                 sys_close(i);
 934                         }
 935                 }
 936                 spin_lock(&files->file_lock);
 937
 938         }
 939         spin_unlock(&files->file_lock);
 940 }
 941
 942 char *get_task_comm(char *buf, struct task_struct *tsk)
 943 {
 944         /* buf must be at least sizeof(tsk->comm) in size */
 945         task_lock(tsk);
 946         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 947         task_unlock(tsk);
 948         return buf;
 949 }
 950
 951 void set_task_comm(struct task_struct *tsk, char *buf)
 952 {
 953         task_lock(tsk);
 954         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 955         task_unlock(tsk);
 956 }
 957
 958 int flush_old_exec(struct linux_binprm * bprm)
 959 {
 960         char * name;
 961         int i, ch, retval;
 962         char tcomm[sizeof(current->comm)];
 963
 964         /*
 965          * Make sure we have a private signal table and that
 966          * we are unassociated from the previous thread group.
 967          */
 968         retval = de_thread(current);
 969         if (retval)
 970                 goto out;
 971
 972         set_mm_exe_file(bprm->mm, bprm->file);
 973
 974         /*
 975          * Release all of the old mmap stuff
 976          */
 977         retval = exec_mmap(bprm->mm);
 978         if (retval)
 979                 goto out;
 980
 981         bprm->mm = NULL;                /* We're using it now */
 982
 983         /* This is the point of no return */
 984         current->sas_ss_sp = current->sas_ss_size = 0;
 985
 986         if (current->euid == current->uid && current->egid == current->gid)
 987                 set_dumpable(current->mm, 1);
 988         else
 989                 set_dumpable(current->mm, suid_dumpable);
 990
 991         name = bprm->filename;
 992
 993         /* Copies the binary name from after last slash */
 994         for (i=0; (ch = *(name++)) != '\0';) {
 995                 if (ch == '/')
 996                         i = 0; /* overwrite what we wrote */
 997                 else
 998                         if (i < (sizeof(tcomm) - 1))
 999                                 tcomm[i++] = ch;
1000         }
1001         tcomm[i] = '\0';
1002         set_task_comm(current, tcomm);
1003
1004         current->flags &= ~PF_RANDOMIZE;
1005         flush_thread();
1006
1007         /* Set the new mm task size. We have to do that late because it may
1008          * depend on TIF_32BIT which is only updated in flush_thread() on
1009          * some architectures like powerpc
1010          */
1011         current->mm->task_size = TASK_SIZE;
1012
1013         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1014                 suid_keys(current);
1015                 set_dumpable(current->mm, suid_dumpable);
1016                 current->pdeath_signal = 0;
1017         } else if (file_permission(bprm->file, MAY_READ) ||
1018                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1019                 suid_keys(current);
1020                 set_dumpable(current->mm, suid_dumpable);
1021         }
1022
1023         /* An exec changes our domain. We are no longer part of the thread
1024            group */
1025
1026         current->self_exec_id++;
1027
1028         flush_signal_handlers(current, 0);
1029         flush_old_files(current->files);
1030
1031         return 0;
1032
1033 out:
1034         return retval;
1035 }
1036
1037 EXPORT_SYMBOL(flush_old_exec);
1038
1039 /*
1040  * Fill the binprm structure from the inode.
1041  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1042  */
1043 int prepare_binprm(struct linux_binprm *bprm)
1044 {
1045         int mode;
1046         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1047         int retval;
1048
1049         mode = inode->i_mode;
1050         if (bprm->file->f_op == NULL)
1051                 return -EACCES;
1052
1053         bprm->e_uid = current->euid;
1054         bprm->e_gid = current->egid;
1055
1056         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1057                 /* Set-uid? */
1058                 if (mode & S_ISUID) {
1059                         current->personality &= ~PER_CLEAR_ON_SETID;
1060                         bprm->e_uid = inode->i_uid;
1061                 }
1062
1063                 /* Set-gid? */
1064                 /*
1065                  * If setgid is set but no group execute bit then this
1066                  * is a candidate for mandatory locking, not a setgid
1067                  * executable.
1068                  */
1069                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1070                         current->personality &= ~PER_CLEAR_ON_SETID;
1071                         bprm->e_gid = inode->i_gid;
1072                 }
1073         }
1074
1075         /* fill in binprm security blob */
1076         retval = security_bprm_set(bprm);
1077         if (retval)
1078                 return retval;
1079
1080         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1081         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1082 }
1083
1084 EXPORT_SYMBOL(prepare_binprm);
1085
1086 static int unsafe_exec(struct task_struct *p)
1087 {
1088         int unsafe = tracehook_unsafe_exec(p);
1089
1090         if (atomic_read(&p->fs->count) > 1 ||
1091             atomic_read(&p->files->count) > 1 ||
1092             atomic_read(&p->sighand->count) > 1)
1093                 unsafe |= LSM_UNSAFE_SHARE;
1094
1095         return unsafe;
1096 }
1097
1098 void compute_creds(struct linux_binprm *bprm)
1099 {
1100         int unsafe;
1101
1102         if (bprm->e_uid != current->uid) {
1103                 suid_keys(current);
1104                 current->pdeath_signal = 0;
1105         }
1106         exec_keys(current);
1107
1108         task_lock(current);
1109         unsafe = unsafe_exec(current);
1110         security_bprm_apply_creds(bprm, unsafe);
1111         task_unlock(current);
1112         security_bprm_post_apply_creds(bprm);
1113 }
1114 EXPORT_SYMBOL(compute_creds);
1115
1116 /*
1117  * Arguments are '\0' separated strings found at the location bprm->p
1118  * points to; chop off the first by relocating brpm->p to right after
1119  * the first '\0' encountered.
1120  */
1121 int remove_arg_zero(struct linux_binprm *bprm)
1122 {
1123         int ret = 0;
1124         unsigned long offset;
1125         char *kaddr;
1126         struct page *page;
1127
1128         if (!bprm->argc)
1129                 return 0;
1130
1131         do {
1132                 offset = bprm->p & ~PAGE_MASK;
1133                 page = get_arg_page(bprm, bprm->p, 0);
1134                 if (!page) {
1135                         ret = -EFAULT;
1136                         goto out;
1137                 }
1138                 kaddr = kmap_atomic(page, KM_USER0);
1139
1140                 for (; offset < PAGE_SIZE && kaddr[offset];
1141                                 offset++, bprm->p++)
1142                         ;
1143
1144                 kunmap_atomic(kaddr, KM_USER0);
1145                 put_arg_page(page);
1146
1147                 if (offset == PAGE_SIZE)
1148                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1149         } while (offset == PAGE_SIZE);
1150
1151         bprm->p++;
1152         bprm->argc--;
1153         ret = 0;
1154
1155 out:
1156         return ret;
1157 }
1158 EXPORT_SYMBOL(remove_arg_zero);
1159
1160 /*
1161  * cycle the list of binary formats handler, until one recognizes the image
1162  */
1163 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1164 {
1165         int try,retval;
1166         struct linux_binfmt *fmt;
1167 #ifdef __alpha__
1168         /* handle /sbin/loader.. */
1169         {
1170             struct exec * eh = (struct exec *) bprm->buf;
1171
1172             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1173                 (eh->fh.f_flags & 0x3000) == 0x3000)
1174             {
1175                 struct file * file;
1176                 unsigned long loader;
1177
1178                 allow_write_access(bprm->file);
1179                 fput(bprm->file);
1180                 bprm->file = NULL;
1181
1182                 loader = bprm->vma->vm_end - sizeof(void *);
1183
1184                 file = open_exec("/sbin/loader");
1185                 retval = PTR_ERR(file);
1186                 if (IS_ERR(file))
1187                         return retval;
1188
1189                 /* Remember if the application is TASO.  */
1190                 bprm->taso = eh->ah.entry < 0x100000000UL;
1191
1192                 bprm->file = file;
1193                 bprm->loader = loader;
1194                 retval = prepare_binprm(bprm);
1195                 if (retval<0)
1196                         return retval;
1197                 /* should call search_binary_handler recursively here,
1198                    but it does not matter */
1199             }
1200         }
1201 #endif
1202         retval = security_bprm_check(bprm);
1203         if (retval)
1204                 return retval;
1205
1206         /* kernel module loader fixup */
1207         /* so we don't try to load run modprobe in kernel space. */
1208         set_fs(USER_DS);
1209
1210         retval = audit_bprm(bprm);
1211         if (retval)
1212                 return retval;
1213
1214         retval = -ENOENT;
1215         for (try=0; try<2; try++) {
1216                 read_lock(&binfmt_lock);
1217                 list_for_each_entry(fmt, &formats, lh) {
1218                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1219                         if (!fn)
1220                                 continue;
1221                         if (!try_module_get(fmt->module))
1222                                 continue;
1223                         read_unlock(&binfmt_lock);
1224                         retval = fn(bprm, regs);
1225                         if (retval >= 0) {
1226                                 tracehook_report_exec(fmt, bprm, regs);
1227                                 put_binfmt(fmt);
1228                                 allow_write_access(bprm->file);
1229                                 if (bprm->file)
1230                                         fput(bprm->file);
1231                                 bprm->file = NULL;
1232                                 current->did_exec = 1;
1233                                 proc_exec_connector(current);
1234                                 return retval;
1235                         }
1236                         read_lock(&binfmt_lock);
1237                         put_binfmt(fmt);
1238                         if (retval != -ENOEXEC || bprm->mm == NULL)
1239                                 break;
1240                         if (!bprm->file) {
1241                                 read_unlock(&binfmt_lock);
1242                                 return retval;
1243                         }
1244                 }
1245                 read_unlock(&binfmt_lock);
1246                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1247                         break;
1248 #ifdef CONFIG_KMOD
1249                 }else{
1250 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1251                         if (printable(bprm->buf[0]) &&
1252                             printable(bprm->buf[1]) &&
1253                             printable(bprm->buf[2]) &&
1254                             printable(bprm->buf[3]))
1255                                 break; /* -ENOEXEC */
1256                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1257 #endif
1258                 }
1259         }
1260         return retval;
1261 }
1262
1263 EXPORT_SYMBOL(search_binary_handler);
1264
1265 void free_bprm(struct linux_binprm *bprm)
1266 {
1267         free_arg_pages(bprm);
1268         kfree(bprm);
1269 }
1270
1271 /*
1272  * sys_execve() executes a new program.
1273  */
1274 int do_execve(char * filename,
1275         char __user *__user *argv,
1276         char __user *__user *envp,
1277         struct pt_regs * regs)
1278 {
1279         struct linux_binprm *bprm;
1280         struct file *file;
1281         struct files_struct *displaced;
1282         int retval;
1283
1284         retval = unshare_files(&displaced);
1285         if (retval)
1286                 goto out_ret;
1287
1288         retval = -ENOMEM;
1289         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1290         if (!bprm)
1291                 goto out_files;
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         retval = copy_strings(bprm->argc, argv, bprm);
1334         if (retval < 0)
1335                 goto out;
1336
1337         current->flags &= ~PF_KTHREAD;
1338         retval = search_binary_handler(bprm,regs);
1339         if (retval >= 0) {
1340                 /* execve success */
1341                 security_bprm_free(bprm);
1342                 acct_update_integrals(current);
1343                 free_bprm(bprm);
1344                 if (displaced)
1345                         put_files_struct(displaced);
1346                 return retval;
1347         }
1348
1349 out:
1350         if (bprm->security)
1351                 security_bprm_free(bprm);
1352
1353 out_mm:
1354         if (bprm->mm)
1355                 mmput (bprm->mm);
1356
1357 out_file:
1358         if (bprm->file) {
1359                 allow_write_access(bprm->file);
1360                 fput(bprm->file);
1361         }
1362 out_kfree:
1363         free_bprm(bprm);
1364
1365 out_files:
1366         if (displaced)
1367                 reset_files_struct(displaced);
1368 out_ret:
1369         return retval;
1370 }
1371
1372 int set_binfmt(struct linux_binfmt *new)
1373 {
1374         struct linux_binfmt *old = current->binfmt;
1375
1376         if (new) {
1377                 if (!try_module_get(new->module))
1378                         return -1;
1379         }
1380         current->binfmt = new;
1381         if (old)
1382                 module_put(old->module);
1383         return 0;
1384 }
1385
1386 EXPORT_SYMBOL(set_binfmt);
1387
1388 /* format_corename will inspect the pattern parameter, and output a
1389  * name into corename, which must have space for at least
1390  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1391  */
1392 static int format_corename(char *corename, int nr_threads, long signr)
1393 {
1394         const char *pat_ptr = core_pattern;
1395         int ispipe = (*pat_ptr == '|');
1396         char *out_ptr = corename;
1397         char *const out_end = corename + CORENAME_MAX_SIZE;
1398         int rc;
1399         int pid_in_pattern = 0;
1400
1401         /* Repeat as long as we have more pattern to process and more output
1402            space */
1403         while (*pat_ptr) {
1404                 if (*pat_ptr != '%') {
1405                         if (out_ptr == out_end)
1406                                 goto out;
1407                         *out_ptr++ = *pat_ptr++;
1408                 } else {
1409                         switch (*++pat_ptr) {
1410                         case 0:
1411                                 goto out;
1412                         /* Double percent, output one percent */
1413                         case '%':
1414                                 if (out_ptr == out_end)
1415                                         goto out;
1416                                 *out_ptr++ = '%';
1417                                 break;
1418                         /* pid */
1419                         case 'p':
1420                                 pid_in_pattern = 1;
1421                                 rc = snprintf(out_ptr, out_end - out_ptr,
1422                                               "%d", task_tgid_vnr(current));
1423                                 if (rc > out_end - out_ptr)
1424                                         goto out;
1425                                 out_ptr += rc;
1426                                 break;
1427                         /* uid */
1428                         case 'u':
1429                                 rc = snprintf(out_ptr, out_end - out_ptr,
1430                                               "%d", current->uid);
1431                                 if (rc > out_end - out_ptr)
1432                                         goto out;
1433                                 out_ptr += rc;
1434                                 break;
1435                         /* gid */
1436                         case 'g':
1437                                 rc = snprintf(out_ptr, out_end - out_ptr,
1438                                               "%d", current->gid);
1439                                 if (rc > out_end - out_ptr)
1440                                         goto out;
1441                                 out_ptr += rc;
1442                                 break;
1443                         /* signal that caused the coredump */
1444                         case 's':
1445                                 rc = snprintf(out_ptr, out_end - out_ptr,
1446                                               "%ld", signr);
1447                                 if (rc > out_end - out_ptr)
1448                                         goto out;
1449                                 out_ptr += rc;
1450                                 break;
1451                         /* UNIX time of coredump */
1452                         case 't': {
1453                                 struct timeval tv;
1454                                 do_gettimeofday(&tv);
1455                                 rc = snprintf(out_ptr, out_end - out_ptr,
1456                                               "%lu", tv.tv_sec);
1457                                 if (rc > out_end - out_ptr)
1458                                         goto out;
1459                                 out_ptr += rc;
1460                                 break;
1461                         }
1462                         /* hostname */
1463                         case 'h':
1464                                 down_read(&uts_sem);
1465                                 rc = snprintf(out_ptr, out_end - out_ptr,
1466                                               "%s", utsname()->nodename);
1467                                 up_read(&uts_sem);
1468                                 if (rc > out_end - out_ptr)
1469                                         goto out;
1470                                 out_ptr += rc;
1471                                 break;
1472                         /* executable */
1473                         case 'e':
1474                                 rc = snprintf(out_ptr, out_end - out_ptr,
1475                                               "%s", current->comm);
1476                                 if (rc > out_end - out_ptr)
1477                                         goto out;
1478                                 out_ptr += rc;
1479                                 break;
1480                         /* core limit size */
1481                         case 'c':
1482                                 rc = snprintf(out_ptr, out_end - out_ptr,
1483                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1484                                 if (rc > out_end - out_ptr)
1485                                         goto out;
1486                                 out_ptr += rc;
1487                                 break;
1488                         default:
1489                                 break;
1490                         }
1491                         ++pat_ptr;
1492                 }
1493         }
1494         /* Backward compatibility with core_uses_pid:
1495          *
1496          * If core_pattern does not include a %p (as is the default)
1497          * and core_uses_pid is set, then .%pid will be appended to
1498          * the filename. Do not do this for piped commands. */
1499         if (!ispipe && !pid_in_pattern
1500             && (core_uses_pid || nr_threads)) {
1501                 rc = snprintf(out_ptr, out_end - out_ptr,
1502                               ".%d", task_tgid_vnr(current));
1503                 if (rc > out_end - out_ptr)
1504                         goto out;
1505                 out_ptr += rc;
1506         }
1507 out:
1508         *out_ptr = 0;
1509         return ispipe;
1510 }
1511
1512 static int zap_process(struct task_struct *start)
1513 {
1514         struct task_struct *t;
1515         int nr = 0;
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                         sigaddset(&t->pending.signal, SIGKILL);
1524                         signal_wake_up(t, 1);
1525                         nr++;
1526                 }
1527         } while_each_thread(start, t);
1528
1529         return nr;
1530 }
1531
1532 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1533                                 struct core_state *core_state, int exit_code)
1534 {
1535         struct task_struct *g, *p;
1536         unsigned long flags;
1537         int nr = -EAGAIN;
1538
1539         spin_lock_irq(&tsk->sighand->siglock);
1540         if (!signal_group_exit(tsk->signal)) {
1541                 mm->core_state = core_state;
1542                 tsk->signal->group_exit_code = exit_code;
1543                 nr = zap_process(tsk);
1544         }
1545         spin_unlock_irq(&tsk->sighand->siglock);
1546         if (unlikely(nr < 0))
1547                 return nr;
1548
1549         if (atomic_read(&mm->mm_users) == nr + 1)
1550                 goto done;
1551         /*
1552          * We should find and kill all tasks which use this mm, and we should
1553          * count them correctly into ->nr_threads. We don't take tasklist
1554          * lock, but this is safe wrt:
1555          *
1556          * fork:
1557          *      None of sub-threads can fork after zap_process(leader). All
1558          *      processes which were created before this point should be
1559          *      visible to zap_threads() because copy_process() adds the new
1560          *      process to the tail of init_task.tasks list, and lock/unlock
1561          *      of ->siglock provides a memory barrier.
1562          *
1563          * do_exit:
1564          *      The caller holds mm->mmap_sem. This means that the task which
1565          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1566          *      its ->mm.
1567          *
1568          * de_thread:
1569          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1570          *      we must see either old or new leader, this does not matter.
1571          *      However, it can change p->sighand, so lock_task_sighand(p)
1572          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1573          *      it can't fail.
1574          *
1575          *      Note also that "g" can be the old leader with ->mm == NULL
1576          *      and already unhashed and thus removed from ->thread_group.
1577          *      This is OK, __unhash_process()->list_del_rcu() does not
1578          *      clear the ->next pointer, we will find the new leader via
1579          *      next_thread().
1580          */
1581         rcu_read_lock();
1582         for_each_process(g) {
1583                 if (g == tsk->group_leader)
1584                         continue;
1585                 if (g->flags & PF_KTHREAD)
1586                         continue;
1587                 p = g;
1588                 do {
1589                         if (p->mm) {
1590                                 if (unlikely(p->mm == mm)) {
1591                                         lock_task_sighand(p, &flags);
1592                                         nr += zap_process(p);
1593                                         unlock_task_sighand(p, &flags);
1594                                 }
1595                                 break;
1596                         }
1597                 } while_each_thread(g, p);
1598         }
1599         rcu_read_unlock();
1600 done:
1601         atomic_set(&core_state->nr_threads, nr);
1602         return nr;
1603 }
1604
1605 static int coredump_wait(int exit_code, struct core_state *core_state)
1606 {
1607         struct task_struct *tsk = current;
1608         struct mm_struct *mm = tsk->mm;
1609         struct completion *vfork_done;
1610         int core_waiters;
1611
1612         init_completion(&core_state->startup);
1613         core_state->dumper.task = tsk;
1614         core_state->dumper.next = NULL;
1615         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1616         up_write(&mm->mmap_sem);
1617
1618         if (unlikely(core_waiters < 0))
1619                 goto fail;
1620
1621         /*
1622          * Make sure nobody is waiting for us to release the VM,
1623          * otherwise we can deadlock when we wait on each other
1624          */
1625         vfork_done = tsk->vfork_done;
1626         if (vfork_done) {
1627                 tsk->vfork_done = NULL;
1628                 complete(vfork_done);
1629         }
1630
1631         if (core_waiters)
1632                 wait_for_completion(&core_state->startup);
1633 fail:
1634         return core_waiters;
1635 }
1636
1637 static void coredump_finish(struct mm_struct *mm)
1638 {
1639         struct core_thread *curr, *next;
1640         struct task_struct *task;
1641
1642         next = mm->core_state->dumper.next;
1643         while ((curr = next) != NULL) {
1644                 next = curr->next;
1645                 task = curr->task;
1646                 /*
1647                  * see exit_mm(), curr->task must not see
1648                  * ->task == NULL before we read ->next.
1649                  */
1650                 smp_mb();
1651                 curr->task = NULL;
1652                 wake_up_process(task);
1653         }
1654
1655         mm->core_state = NULL;
1656 }
1657
1658 /*
1659  * set_dumpable converts traditional three-value dumpable to two flags and
1660  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1661  * these bits are not changed atomically.  So get_dumpable can observe the
1662  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1663  * return either old dumpable or new one by paying attention to the order of
1664  * modifying the bits.
1665  *
1666  * dumpable |   mm->flags (binary)
1667  * old  new | initial interim  final
1668  * ---------+-----------------------
1669  *  0    1  |   00      01      01
1670  *  0    2  |   00      10(*)   11
1671  *  1    0  |   01      00      00
1672  *  1    2  |   01      11      11
1673  *  2    0  |   11      10(*)   00
1674  *  2    1  |   11      11      01
1675  *
1676  * (*) get_dumpable regards interim value of 10 as 11.
1677  */
1678 void set_dumpable(struct mm_struct *mm, int value)
1679 {
1680         switch (value) {
1681         case 0:
1682                 clear_bit(MMF_DUMPABLE, &mm->flags);
1683                 smp_wmb();
1684                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1685                 break;
1686         case 1:
1687                 set_bit(MMF_DUMPABLE, &mm->flags);
1688                 smp_wmb();
1689                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1690                 break;
1691         case 2:
1692                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1693                 smp_wmb();
1694                 set_bit(MMF_DUMPABLE, &mm->flags);
1695                 break;
1696         }
1697 }
1698
1699 int get_dumpable(struct mm_struct *mm)
1700 {
1701         int ret;
1702
1703         ret = mm->flags & 0x3;
1704         return (ret >= 2) ? 2 : ret;
1705 }
1706
1707 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1708 {
1709         struct core_state core_state;
1710         char corename[CORENAME_MAX_SIZE + 1];
1711         struct mm_struct *mm = current->mm;
1712         struct linux_binfmt * binfmt;
1713         struct inode * inode;
1714         struct file * file;
1715         int retval = 0;
1716         int fsuid = current->fsuid;
1717         int flag = 0;
1718         int ispipe = 0;
1719         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1720         char **helper_argv = NULL;
1721         int helper_argc = 0;
1722         char *delimit;
1723
1724         audit_core_dumps(signr);
1725
1726         binfmt = current->binfmt;
1727         if (!binfmt || !binfmt->core_dump)
1728                 goto fail;
1729         down_write(&mm->mmap_sem);
1730         /*
1731          * If another thread got here first, or we are not dumpable, bail out.
1732          */
1733         if (mm->core_state || !get_dumpable(mm)) {
1734                 up_write(&mm->mmap_sem);
1735                 goto fail;
1736         }
1737
1738         /*
1739          *      We cannot trust fsuid as being the "true" uid of the
1740          *      process nor do we know its entire history. We only know it
1741          *      was tainted so we dump it as root in mode 2.
1742          */
1743         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1744                 flag = O_EXCL;          /* Stop rewrite attacks */
1745                 current->fsuid = 0;     /* Dump root private */
1746         }
1747
1748         retval = coredump_wait(exit_code, &core_state);
1749         if (retval < 0)
1750                 goto fail;
1751
1752         /*
1753          * Clear any false indication of pending signals that might
1754          * be seen by the filesystem code called to write the core file.
1755          */
1756         clear_thread_flag(TIF_SIGPENDING);
1757
1758         /*
1759          * lock_kernel() because format_corename() is controlled by sysctl, which
1760          * uses lock_kernel()
1761          */
1762         lock_kernel();
1763         ispipe = format_corename(corename, retval, signr);
1764         unlock_kernel();
1765         /*
1766          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1767          * to a pipe.  Since we're not writing directly to the filesystem
1768          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1769          * created unless the pipe reader choses to write out the core file
1770          * at which point file size limits and permissions will be imposed
1771          * as it does with any other process
1772          */
1773         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1774                 goto fail_unlock;
1775
1776         if (ispipe) {
1777                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1778                 /* Terminate the string before the first option */
1779                 delimit = strchr(corename, ' ');
1780                 if (delimit)
1781                         *delimit = '\0';
1782                 delimit = strrchr(helper_argv[0], '/');
1783                 if (delimit)
1784                         delimit++;
1785                 else
1786                         delimit = helper_argv[0];
1787                 if (!strcmp(delimit, current->comm)) {
1788                         printk(KERN_NOTICE "Recursive core dump detected, "
1789                                         "aborting\n");
1790                         goto fail_unlock;
1791                 }
1792
1793                 core_limit = RLIM_INFINITY;
1794
1795                 /* SIGPIPE can happen, but it's just never processed */
1796                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1797                                 &file)) {
1798                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1799                                corename);
1800                         goto fail_unlock;
1801                 }
1802         } else
1803                 file = filp_open(corename,
1804                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1805                                  0600);
1806         if (IS_ERR(file))
1807                 goto fail_unlock;
1808         inode = file->f_path.dentry->d_inode;
1809         if (inode->i_nlink > 1)
1810                 goto close_fail;        /* multiple links - don't dump */
1811         if (!ispipe && d_unhashed(file->f_path.dentry))
1812                 goto close_fail;
1813
1814         /* AK: actually i see no reason to not allow this for named pipes etc.,
1815            but keep the previous behaviour for now. */
1816         if (!ispipe && !S_ISREG(inode->i_mode))
1817                 goto close_fail;
1818         /*
1819          * Dont allow local users get cute and trick others to coredump
1820          * into their pre-created files:
1821          */
1822         if (inode->i_uid != current->fsuid)
1823                 goto close_fail;
1824         if (!file->f_op)
1825                 goto close_fail;
1826         if (!file->f_op->write)
1827                 goto close_fail;
1828         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1829                 goto close_fail;
1830
1831         retval = binfmt->core_dump(signr, regs, file, core_limit);
1832
1833         if (retval)
1834                 current->signal->group_exit_code |= 0x80;
1835 close_fail:
1836         filp_close(file, NULL);
1837 fail_unlock:
1838         if (helper_argv)
1839                 argv_free(helper_argv);
1840
1841         current->fsuid = fsuid;
1842         coredump_finish(mm);
1843 fail:
1844         return retval;
1845 }