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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 #include <linux/kmod.h>
  54
  55 #include <asm/uaccess.h>
  56 #include <asm/mmu_context.h>
  57 #include <asm/tlb.h>
  58 #include "internal.h"
  59
  60 int core_uses_pid;
  61 char core_pattern[CORENAME_MAX_SIZE] = "core";
  62 int suid_dumpable = 0;
  63
  64 /* The maximal length of core_pattern is also specified in sysctl.c */
  65
  66 static LIST_HEAD(formats);
  67 static DEFINE_RWLOCK(binfmt_lock);
  68
  69 int register_binfmt(struct linux_binfmt * fmt)
  70 {
  71         if (!fmt)
  72                 return -EINVAL;
  73         write_lock(&binfmt_lock);
  74         list_add(&fmt->lh, &formats);
  75         write_unlock(&binfmt_lock);
  76         return 0;
  77 }
  78
  79 EXPORT_SYMBOL(register_binfmt);
  80
  81 void unregister_binfmt(struct linux_binfmt * fmt)
  82 {
  83         write_lock(&binfmt_lock);
  84         list_del(&fmt->lh);
  85         write_unlock(&binfmt_lock);
  86 }
  87
  88 EXPORT_SYMBOL(unregister_binfmt);
  89
  90 static inline void put_binfmt(struct linux_binfmt * fmt)
  91 {
  92         module_put(fmt->module);
  93 }
  94
  95 /*
  96  * Note that a shared library must be both readable and executable due to
  97  * security reasons.
  98  *
  99  * Also note that we take the address to load from from the file itself.
 100  */
 101 asmlinkage long sys_uselib(const char __user * library)
 102 {
 103         struct file *file;
 104         struct nameidata nd;
 105         char *tmp = getname(library);
 106         int error = PTR_ERR(tmp);
 107
 108         if (!IS_ERR(tmp)) {
 109                 error = path_lookup_open(AT_FDCWD, tmp,
 110                                          LOOKUP_FOLLOW, &nd,
 111                                          FMODE_READ|FMODE_EXEC);
 112                 putname(tmp);
 113         }
 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 = -EACCES;
 122         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 123                 goto exit;
 124
 125         error = inode_permission(nd.path.dentry->d_inode,
 126                                  MAY_READ | MAY_EXEC | MAY_OPEN);
 127         if (error)
 128                 goto exit;
 129
 130         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 131         error = PTR_ERR(file);
 132         if (IS_ERR(file))
 133                 goto out;
 134
 135         error = -ENOEXEC;
 136         if(file->f_op) {
 137                 struct linux_binfmt * fmt;
 138
 139                 read_lock(&binfmt_lock);
 140                 list_for_each_entry(fmt, &formats, lh) {
 141                         if (!fmt->load_shlib)
 142                                 continue;
 143                         if (!try_module_get(fmt->module))
 144                                 continue;
 145                         read_unlock(&binfmt_lock);
 146                         error = fmt->load_shlib(file);
 147                         read_lock(&binfmt_lock);
 148                         put_binfmt(fmt);
 149                         if (error != -ENOEXEC)
 150                                 break;
 151                 }
 152                 read_unlock(&binfmt_lock);
 153         }
 154         fput(file);
 155 out:
 156         return error;
 157 exit:
 158         release_open_intent(&nd);
 159         path_put(&nd.path);
 160         goto out;
 161 }
 162
 163 #ifdef CONFIG_MMU
 164
 165 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 166                 int write)
 167 {
 168         struct page *page;
 169         int ret;
 170
 171 #ifdef CONFIG_STACK_GROWSUP
 172         if (write) {
 173                 ret = expand_stack_downwards(bprm->vma, pos);
 174                 if (ret < 0)
 175                         return NULL;
 176         }
 177 #endif
 178         ret = get_user_pages(current, bprm->mm, pos,
 179                         1, write, 1, &page, NULL);
 180         if (ret <= 0)
 181                 return NULL;
 182
 183         if (write) {
 184                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 185                 struct rlimit *rlim;
 186
 187                 /*
 188                  * We've historically supported up to 32 pages (ARG_MAX)
 189                  * of argument strings even with small stacks
 190                  */
 191                 if (size <= ARG_MAX)
 192                         return page;
 193
 194                 /*
 195                  * Limit to 1/4-th the stack size for the argv+env strings.
 196                  * This ensures that:
 197                  *  - the remaining binfmt code will not run out of stack space,
 198                  *  - the program will have a reasonable amount of stack left
 199                  *    to work from.
 200                  */
 201                 rlim = current->signal->rlim;
 202                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 203                         put_page(page);
 204                         return NULL;
 205                 }
 206         }
 207
 208         return page;
 209 }
 210
 211 static void put_arg_page(struct page *page)
 212 {
 213         put_page(page);
 214 }
 215
 216 static void free_arg_page(struct linux_binprm *bprm, int i)
 217 {
 218 }
 219
 220 static void free_arg_pages(struct linux_binprm *bprm)
 221 {
 222 }
 223
 224 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 225                 struct page *page)
 226 {
 227         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 228 }
 229
 230 static int __bprm_mm_init(struct linux_binprm *bprm)
 231 {
 232         int err = -ENOMEM;
 233         struct vm_area_struct *vma = NULL;
 234         struct mm_struct *mm = bprm->mm;
 235
 236         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 237         if (!vma)
 238                 goto err;
 239
 240         down_write(&mm->mmap_sem);
 241         vma->vm_mm = mm;
 242
 243         /*
 244          * Place the stack at the largest stack address the architecture
 245          * supports. Later, we'll move this to an appropriate place. We don't
 246          * use STACK_TOP because that can depend on attributes which aren't
 247          * configured yet.
 248          */
 249         vma->vm_end = STACK_TOP_MAX;
 250         vma->vm_start = vma->vm_end - PAGE_SIZE;
 251
 252         vma->vm_flags = VM_STACK_FLAGS;
 253         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 254         err = insert_vm_struct(mm, vma);
 255         if (err) {
 256                 up_write(&mm->mmap_sem);
 257                 goto err;
 258         }
 259
 260         mm->stack_vm = mm->total_vm = 1;
 261         up_write(&mm->mmap_sem);
 262
 263         bprm->p = vma->vm_end - sizeof(void *);
 264
 265         return 0;
 266
 267 err:
 268         if (vma) {
 269                 bprm->vma = NULL;
 270                 kmem_cache_free(vm_area_cachep, vma);
 271         }
 272
 273         return err;
 274 }
 275
 276 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 277 {
 278         return len <= MAX_ARG_STRLEN;
 279 }
 280
 281 #else
 282
 283 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 284                 int write)
 285 {
 286         struct page *page;
 287
 288         page = bprm->page[pos / PAGE_SIZE];
 289         if (!page && write) {
 290                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 291                 if (!page)
 292                         return NULL;
 293                 bprm->page[pos / PAGE_SIZE] = page;
 294         }
 295
 296         return page;
 297 }
 298
 299 static void put_arg_page(struct page *page)
 300 {
 301 }
 302
 303 static void free_arg_page(struct linux_binprm *bprm, int i)
 304 {
 305         if (bprm->page[i]) {
 306                 __free_page(bprm->page[i]);
 307                 bprm->page[i] = NULL;
 308         }
 309 }
 310
 311 static void free_arg_pages(struct linux_binprm *bprm)
 312 {
 313         int i;
 314
 315         for (i = 0; i < MAX_ARG_PAGES; i++)
 316                 free_arg_page(bprm, i);
 317 }
 318
 319 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 320                 struct page *page)
 321 {
 322 }
 323
 324 static int __bprm_mm_init(struct linux_binprm *bprm)
 325 {
 326         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 327         return 0;
 328 }
 329
 330 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 331 {
 332         return len <= bprm->p;
 333 }
 334
 335 #endif /* CONFIG_MMU */
 336
 337 /*
 338  * Create a new mm_struct and populate it with a temporary stack
 339  * vm_area_struct.  We don't have enough context at this point to set the stack
 340  * flags, permissions, and offset, so we use temporary values.  We'll update
 341  * them later in setup_arg_pages().
 342  */
 343 int bprm_mm_init(struct linux_binprm *bprm)
 344 {
 345         int err;
 346         struct mm_struct *mm = NULL;
 347
 348         bprm->mm = mm = mm_alloc();
 349         err = -ENOMEM;
 350         if (!mm)
 351                 goto err;
 352
 353         err = init_new_context(current, mm);
 354         if (err)
 355                 goto err;
 356
 357         err = __bprm_mm_init(bprm);
 358         if (err)
 359                 goto err;
 360
 361         return 0;
 362
 363 err:
 364         if (mm) {
 365                 bprm->mm = NULL;
 366                 mmdrop(mm);
 367         }
 368
 369         return err;
 370 }
 371
 372 /*
 373  * count() counts the number of strings in array ARGV.
 374  */
 375 static int count(char __user * __user * argv, int max)
 376 {
 377         int i = 0;
 378
 379         if (argv != NULL) {
 380                 for (;;) {
 381                         char __user * p;
 382
 383                         if (get_user(p, argv))
 384                                 return -EFAULT;
 385                         if (!p)
 386                                 break;
 387                         argv++;
 388                         if (i++ >= max)
 389                                 return -E2BIG;
 390                         cond_resched();
 391                 }
 392         }
 393         return i;
 394 }
 395
 396 /*
 397  * 'copy_strings()' copies argument/environment strings from the old
 398  * processes's memory to the new process's stack.  The call to get_user_pages()
 399  * ensures the destination page is created and not swapped out.
 400  */
 401 static int copy_strings(int argc, char __user * __user * argv,
 402                         struct linux_binprm *bprm)
 403 {
 404         struct page *kmapped_page = NULL;
 405         char *kaddr = NULL;
 406         unsigned long kpos = 0;
 407         int ret;
 408
 409         while (argc-- > 0) {
 410                 char __user *str;
 411                 int len;
 412                 unsigned long pos;
 413
 414                 if (get_user(str, argv+argc) ||
 415                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 416                         ret = -EFAULT;
 417                         goto out;
 418                 }
 419
 420                 if (!valid_arg_len(bprm, len)) {
 421                         ret = -E2BIG;
 422                         goto out;
 423                 }
 424
 425                 /* We're going to work our way backwords. */
 426                 pos = bprm->p;
 427                 str += len;
 428                 bprm->p -= len;
 429
 430                 while (len > 0) {
 431                         int offset, bytes_to_copy;
 432
 433                         offset = pos % PAGE_SIZE;
 434                         if (offset == 0)
 435                                 offset = PAGE_SIZE;
 436
 437                         bytes_to_copy = offset;
 438                         if (bytes_to_copy > len)
 439                                 bytes_to_copy = len;
 440
 441                         offset -= bytes_to_copy;
 442                         pos -= bytes_to_copy;
 443                         str -= bytes_to_copy;
 444                         len -= bytes_to_copy;
 445
 446                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 447                                 struct page *page;
 448
 449                                 page = get_arg_page(bprm, pos, 1);
 450                                 if (!page) {
 451                                         ret = -E2BIG;
 452                                         goto out;
 453                                 }
 454
 455                                 if (kmapped_page) {
 456                                         flush_kernel_dcache_page(kmapped_page);
 457                                         kunmap(kmapped_page);
 458                                         put_arg_page(kmapped_page);
 459                                 }
 460                                 kmapped_page = page;
 461                                 kaddr = kmap(kmapped_page);
 462                                 kpos = pos & PAGE_MASK;
 463                                 flush_arg_page(bprm, kpos, kmapped_page);
 464                         }
 465                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 466                                 ret = -EFAULT;
 467                                 goto out;
 468                         }
 469                 }
 470         }
 471         ret = 0;
 472 out:
 473         if (kmapped_page) {
 474                 flush_kernel_dcache_page(kmapped_page);
 475                 kunmap(kmapped_page);
 476                 put_arg_page(kmapped_page);
 477         }
 478         return ret;
 479 }
 480
 481 /*
 482  * Like copy_strings, but get argv and its values from kernel memory.
 483  */
 484 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 485 {
 486         int r;
 487         mm_segment_t oldfs = get_fs();
 488         set_fs(KERNEL_DS);
 489         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 490         set_fs(oldfs);
 491         return r;
 492 }
 493 EXPORT_SYMBOL(copy_strings_kernel);
 494
 495 #ifdef CONFIG_MMU
 496
 497 /*
 498  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 499  * the binfmt code determines where the new stack should reside, we shift it to
 500  * its final location.  The process proceeds as follows:
 501  *
 502  * 1) Use shift to calculate the new vma endpoints.
 503  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 504  *    arguments passed to subsequent functions are consistent.
 505  * 3) Move vma's page tables to the new range.
 506  * 4) Free up any cleared pgd range.
 507  * 5) Shrink the vma to cover only the new range.
 508  */
 509 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 510 {
 511         struct mm_struct *mm = vma->vm_mm;
 512         unsigned long old_start = vma->vm_start;
 513         unsigned long old_end = vma->vm_end;
 514         unsigned long length = old_end - old_start;
 515         unsigned long new_start = old_start - shift;
 516         unsigned long new_end = old_end - shift;
 517         struct mmu_gather *tlb;
 518
 519         BUG_ON(new_start > new_end);
 520
 521         /*
 522          * ensure there are no vmas between where we want to go
 523          * and where we are
 524          */
 525         if (vma != find_vma(mm, new_start))
 526                 return -EFAULT;
 527
 528         /*
 529          * cover the whole range: [new_start, old_end)
 530          */
 531         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 532
 533         /*
 534          * move the page tables downwards, on failure we rely on
 535          * process cleanup to remove whatever mess we made.
 536          */
 537         if (length != move_page_tables(vma, old_start,
 538                                        vma, new_start, length))
 539                 return -ENOMEM;
 540
 541         lru_add_drain();
 542         tlb = tlb_gather_mmu(mm, 0);
 543         if (new_end > old_start) {
 544                 /*
 545                  * when the old and new regions overlap clear from new_end.
 546                  */
 547                 free_pgd_range(tlb, new_end, old_end, new_end,
 548                         vma->vm_next ? vma->vm_next->vm_start : 0);
 549         } else {
 550                 /*
 551                  * otherwise, clean from old_start; this is done to not touch
 552                  * the address space in [new_end, old_start) some architectures
 553                  * have constraints on va-space that make this illegal (IA64) -
 554                  * for the others its just a little faster.
 555                  */
 556                 free_pgd_range(tlb, old_start, old_end, new_end,
 557                         vma->vm_next ? vma->vm_next->vm_start : 0);
 558         }
 559         tlb_finish_mmu(tlb, new_end, old_end);
 560
 561         /*
 562          * shrink the vma to just the new range.
 563          */
 564         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 565
 566         return 0;
 567 }
 568
 569 #define EXTRA_STACK_VM_PAGES    20      /* random */
 570
 571 /*
 572  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 573  * the stack is optionally relocated, and some extra space is added.
 574  */
 575 int setup_arg_pages(struct linux_binprm *bprm,
 576                     unsigned long stack_top,
 577                     int executable_stack)
 578 {
 579         unsigned long ret;
 580         unsigned long stack_shift;
 581         struct mm_struct *mm = current->mm;
 582         struct vm_area_struct *vma = bprm->vma;
 583         struct vm_area_struct *prev = NULL;
 584         unsigned long vm_flags;
 585         unsigned long stack_base;
 586
 587 #ifdef CONFIG_STACK_GROWSUP
 588         /* Limit stack size to 1GB */
 589         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 590         if (stack_base > (1 << 30))
 591                 stack_base = 1 << 30;
 592
 593         /* Make sure we didn't let the argument array grow too large. */
 594         if (vma->vm_end - vma->vm_start > stack_base)
 595                 return -ENOMEM;
 596
 597         stack_base = PAGE_ALIGN(stack_top - stack_base);
 598
 599         stack_shift = vma->vm_start - stack_base;
 600         mm->arg_start = bprm->p - stack_shift;
 601         bprm->p = vma->vm_end - stack_shift;
 602 #else
 603         stack_top = arch_align_stack(stack_top);
 604         stack_top = PAGE_ALIGN(stack_top);
 605         stack_shift = vma->vm_end - stack_top;
 606
 607         bprm->p -= stack_shift;
 608         mm->arg_start = bprm->p;
 609 #endif
 610
 611         if (bprm->loader)
 612                 bprm->loader -= stack_shift;
 613         bprm->exec -= stack_shift;
 614
 615         down_write(&mm->mmap_sem);
 616         vm_flags = VM_STACK_FLAGS;
 617
 618         /*
 619          * Adjust stack execute permissions; explicitly enable for
 620          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 621          * (arch default) otherwise.
 622          */
 623         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 624                 vm_flags |= VM_EXEC;
 625         else if (executable_stack == EXSTACK_DISABLE_X)
 626                 vm_flags &= ~VM_EXEC;
 627         vm_flags |= mm->def_flags;
 628
 629         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 630                         vm_flags);
 631         if (ret)
 632                 goto out_unlock;
 633         BUG_ON(prev != vma);
 634
 635         /* Move stack pages down in memory. */
 636         if (stack_shift) {
 637                 ret = shift_arg_pages(vma, stack_shift);
 638                 if (ret) {
 639                         up_write(&mm->mmap_sem);
 640                         return ret;
 641                 }
 642         }
 643
 644 #ifdef CONFIG_STACK_GROWSUP
 645         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 646 #else
 647         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 648 #endif
 649         ret = expand_stack(vma, stack_base);
 650         if (ret)
 651                 ret = -EFAULT;
 652
 653 out_unlock:
 654         up_write(&mm->mmap_sem);
 655         return 0;
 656 }
 657 EXPORT_SYMBOL(setup_arg_pages);
 658
 659 #endif /* CONFIG_MMU */
 660
 661 struct file *open_exec(const char *name)
 662 {
 663         struct nameidata nd;
 664         struct file *file;
 665         int err;
 666
 667         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
 668                                 FMODE_READ|FMODE_EXEC);
 669         if (err)
 670                 goto out;
 671
 672         err = -EACCES;
 673         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 674                 goto out_path_put;
 675
 676         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 677                 goto out_path_put;
 678
 679         err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN);
 680         if (err)
 681                 goto out_path_put;
 682
 683         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 684         if (IS_ERR(file))
 685                 return file;
 686
 687         err = deny_write_access(file);
 688         if (err) {
 689                 fput(file);
 690                 goto out;
 691         }
 692
 693         return file;
 694
 695  out_path_put:
 696         release_open_intent(&nd);
 697         path_put(&nd.path);
 698  out:
 699         return ERR_PTR(err);
 700 }
 701 EXPORT_SYMBOL(open_exec);
 702
 703 int kernel_read(struct file *file, unsigned long offset,
 704         char *addr, unsigned long count)
 705 {
 706         mm_segment_t old_fs;
 707         loff_t pos = offset;
 708         int result;
 709
 710         old_fs = get_fs();
 711         set_fs(get_ds());
 712         /* The cast to a user pointer is valid due to the set_fs() */
 713         result = vfs_read(file, (void __user *)addr, count, &pos);
 714         set_fs(old_fs);
 715         return result;
 716 }
 717
 718 EXPORT_SYMBOL(kernel_read);
 719
 720 static int exec_mmap(struct mm_struct *mm)
 721 {
 722         struct task_struct *tsk;
 723         struct mm_struct * old_mm, *active_mm;
 724
 725         /* Notify parent that we're no longer interested in the old VM */
 726         tsk = current;
 727         old_mm = current->mm;
 728         mm_release(tsk, old_mm);
 729
 730         if (old_mm) {
 731                 /*
 732                  * Make sure that if there is a core dump in progress
 733                  * for the old mm, we get out and die instead of going
 734                  * through with the exec.  We must hold mmap_sem around
 735                  * checking core_state and changing tsk->mm.
 736                  */
 737                 down_read(&old_mm->mmap_sem);
 738                 if (unlikely(old_mm->core_state)) {
 739                         up_read(&old_mm->mmap_sem);
 740                         return -EINTR;
 741                 }
 742         }
 743         task_lock(tsk);
 744         active_mm = tsk->active_mm;
 745         tsk->mm = mm;
 746         tsk->active_mm = mm;
 747         activate_mm(active_mm, mm);
 748         task_unlock(tsk);
 749         arch_pick_mmap_layout(mm);
 750         if (old_mm) {
 751                 up_read(&old_mm->mmap_sem);
 752                 BUG_ON(active_mm != old_mm);
 753                 mm_update_next_owner(old_mm);
 754                 mmput(old_mm);
 755                 return 0;
 756         }
 757         mmdrop(active_mm);
 758         return 0;
 759 }
 760
 761 /*
 762  * This function makes sure the current process has its own signal table,
 763  * so that flush_signal_handlers can later reset the handlers without
 764  * disturbing other processes.  (Other processes might share the signal
 765  * table via the CLONE_SIGHAND option to clone().)
 766  */
 767 static int de_thread(struct task_struct *tsk)
 768 {
 769         struct signal_struct *sig = tsk->signal;
 770         struct sighand_struct *oldsighand = tsk->sighand;
 771         spinlock_t *lock = &oldsighand->siglock;
 772         int count;
 773
 774         if (thread_group_empty(tsk))
 775                 goto no_thread_group;
 776
 777         /*
 778          * Kill all other threads in the thread group.
 779          */
 780         spin_lock_irq(lock);
 781         if (signal_group_exit(sig)) {
 782                 /*
 783                  * Another group action in progress, just
 784                  * return so that the signal is processed.
 785                  */
 786                 spin_unlock_irq(lock);
 787                 return -EAGAIN;
 788         }
 789         sig->group_exit_task = tsk;
 790         zap_other_threads(tsk);
 791
 792         /* Account for the thread group leader hanging around: */
 793         count = thread_group_leader(tsk) ? 1 : 2;
 794         sig->notify_count = count;
 795         while (atomic_read(&sig->count) > count) {
 796                 __set_current_state(TASK_UNINTERRUPTIBLE);
 797                 spin_unlock_irq(lock);
 798                 schedule();
 799                 spin_lock_irq(lock);
 800         }
 801         spin_unlock_irq(lock);
 802
 803         /*
 804          * At this point all other threads have exited, all we have to
 805          * do is to wait for the thread group leader to become inactive,
 806          * and to assume its PID:
 807          */
 808         if (!thread_group_leader(tsk)) {
 809                 struct task_struct *leader = tsk->group_leader;
 810
 811                 sig->notify_count = -1; /* for exit_notify() */
 812                 for (;;) {
 813                         write_lock_irq(&tasklist_lock);
 814                         if (likely(leader->exit_state))
 815                                 break;
 816                         __set_current_state(TASK_UNINTERRUPTIBLE);
 817                         write_unlock_irq(&tasklist_lock);
 818                         schedule();
 819                 }
 820
 821                 /*
 822                  * The only record we have of the real-time age of a
 823                  * process, regardless of execs it's done, is start_time.
 824                  * All the past CPU time is accumulated in signal_struct
 825                  * from sister threads now dead.  But in this non-leader
 826                  * exec, nothing survives from the original leader thread,
 827                  * whose birth marks the true age of this process now.
 828                  * When we take on its identity by switching to its PID, we
 829                  * also take its birthdate (always earlier than our own).
 830                  */
 831                 tsk->start_time = leader->start_time;
 832
 833                 BUG_ON(!same_thread_group(leader, tsk));
 834                 BUG_ON(has_group_leader_pid(tsk));
 835                 /*
 836                  * An exec() starts a new thread group with the
 837                  * TGID of the previous thread group. Rehash the
 838                  * two threads with a switched PID, and release
 839                  * the former thread group leader:
 840                  */
 841
 842                 /* Become a process group leader with the old leader's pid.
 843                  * The old leader becomes a thread of the this thread group.
 844                  * Note: The old leader also uses this pid until release_task
 845                  *       is called.  Odd but simple and correct.
 846                  */
 847                 detach_pid(tsk, PIDTYPE_PID);
 848                 tsk->pid = leader->pid;
 849                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 850                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 851                 transfer_pid(leader, tsk, PIDTYPE_SID);
 852                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 853
 854                 tsk->group_leader = tsk;
 855                 leader->group_leader = tsk;
 856
 857                 tsk->exit_signal = SIGCHLD;
 858
 859                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 860                 leader->exit_state = EXIT_DEAD;
 861                 write_unlock_irq(&tasklist_lock);
 862
 863                 release_task(leader);
 864         }
 865
 866         sig->group_exit_task = NULL;
 867         sig->notify_count = 0;
 868
 869 no_thread_group:
 870         exit_itimers(sig);
 871         flush_itimer_signals();
 872
 873         if (atomic_read(&oldsighand->count) != 1) {
 874                 struct sighand_struct *newsighand;
 875                 /*
 876                  * This ->sighand is shared with the CLONE_SIGHAND
 877                  * but not CLONE_THREAD task, switch to the new one.
 878                  */
 879                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 880                 if (!newsighand)
 881                         return -ENOMEM;
 882
 883                 atomic_set(&newsighand->count, 1);
 884                 memcpy(newsighand->action, oldsighand->action,
 885                        sizeof(newsighand->action));
 886
 887                 write_lock_irq(&tasklist_lock);
 888                 spin_lock(&oldsighand->siglock);
 889                 rcu_assign_pointer(tsk->sighand, newsighand);
 890                 spin_unlock(&oldsighand->siglock);
 891                 write_unlock_irq(&tasklist_lock);
 892
 893                 __cleanup_sighand(oldsighand);
 894         }
 895
 896         BUG_ON(!thread_group_leader(tsk));
 897         return 0;
 898 }
 899
 900 /*
 901  * These functions flushes out all traces of the currently running executable
 902  * so that a new one can be started
 903  */
 904 static void flush_old_files(struct files_struct * files)
 905 {
 906         long j = -1;
 907         struct fdtable *fdt;
 908
 909         spin_lock(&files->file_lock);
 910         for (;;) {
 911                 unsigned long set, i;
 912
 913                 j++;
 914                 i = j * __NFDBITS;
 915                 fdt = files_fdtable(files);
 916                 if (i >= fdt->max_fds)
 917                         break;
 918                 set = fdt->close_on_exec->fds_bits[j];
 919                 if (!set)
 920                         continue;
 921                 fdt->close_on_exec->fds_bits[j] = 0;
 922                 spin_unlock(&files->file_lock);
 923                 for ( ; set ; i++,set >>= 1) {
 924                         if (set & 1) {
 925                                 sys_close(i);
 926                         }
 927                 }
 928                 spin_lock(&files->file_lock);
 929
 930         }
 931         spin_unlock(&files->file_lock);
 932 }
 933
 934 char *get_task_comm(char *buf, struct task_struct *tsk)
 935 {
 936         /* buf must be at least sizeof(tsk->comm) in size */
 937         task_lock(tsk);
 938         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 939         task_unlock(tsk);
 940         return buf;
 941 }
 942
 943 void set_task_comm(struct task_struct *tsk, char *buf)
 944 {
 945         task_lock(tsk);
 946         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 947         task_unlock(tsk);
 948 }
 949
 950 int flush_old_exec(struct linux_binprm * bprm)
 951 {
 952         char * name;
 953         int i, ch, retval;
 954         char tcomm[sizeof(current->comm)];
 955
 956         /*
 957          * Make sure we have a private signal table and that
 958          * we are unassociated from the previous thread group.
 959          */
 960         retval = de_thread(current);
 961         if (retval)
 962                 goto out;
 963
 964         set_mm_exe_file(bprm->mm, bprm->file);
 965
 966         /*
 967          * Release all of the old mmap stuff
 968          */
 969         retval = exec_mmap(bprm->mm);
 970         if (retval)
 971                 goto out;
 972
 973         bprm->mm = NULL;                /* We're using it now */
 974
 975         /* This is the point of no return */
 976         current->sas_ss_sp = current->sas_ss_size = 0;
 977
 978         if (current_euid() == current_uid() && current_egid() == current_gid())
 979                 set_dumpable(current->mm, 1);
 980         else
 981                 set_dumpable(current->mm, suid_dumpable);
 982
 983         name = bprm->filename;
 984
 985         /* Copies the binary name from after last slash */
 986         for (i=0; (ch = *(name++)) != '\0';) {
 987                 if (ch == '/')
 988                         i = 0; /* overwrite what we wrote */
 989                 else
 990                         if (i < (sizeof(tcomm) - 1))
 991                                 tcomm[i++] = ch;
 992         }
 993         tcomm[i] = '\0';
 994         set_task_comm(current, tcomm);
 995
 996         current->flags &= ~PF_RANDOMIZE;
 997         flush_thread();
 998
 999         /* Set the new mm task size. We have to do that late because it may
1000          * depend on TIF_32BIT which is only updated in flush_thread() on
1001          * some architectures like powerpc
1002          */
1003         current->mm->task_size = TASK_SIZE;
1004
1005         /* install the new credentials */
1006         if (bprm->cred->uid != current_euid() ||
1007             bprm->cred->gid != current_egid()) {
1008                 current->pdeath_signal = 0;
1009         } else if (file_permission(bprm->file, MAY_READ) ||
1010                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1011                 set_dumpable(current->mm, suid_dumpable);
1012         }
1013
1014         current->personality &= ~bprm->per_clear;
1015
1016         /* An exec changes our domain. We are no longer part of the thread
1017            group */
1018
1019         current->self_exec_id++;
1020
1021         flush_signal_handlers(current, 0);
1022         flush_old_files(current->files);
1023
1024         return 0;
1025
1026 out:
1027         return retval;
1028 }
1029
1030 EXPORT_SYMBOL(flush_old_exec);
1031
1032 /*
1033  * install the new credentials for this executable
1034  */
1035 void install_exec_creds(struct linux_binprm *bprm)
1036 {
1037         security_bprm_committing_creds(bprm);
1038
1039         commit_creds(bprm->cred);
1040         bprm->cred = NULL;
1041
1042         /* cred_exec_mutex must be held at least to this point to prevent
1043          * ptrace_attach() from altering our determination of the task's
1044          * credentials; any time after this it may be unlocked */
1045
1046         security_bprm_committed_creds(bprm);
1047 }
1048 EXPORT_SYMBOL(install_exec_creds);
1049
1050 /*
1051  * determine how safe it is to execute the proposed program
1052  * - the caller must hold current->cred_exec_mutex to protect against
1053  *   PTRACE_ATTACH
1054  */
1055 void check_unsafe_exec(struct linux_binprm *bprm)
1056 {
1057         struct task_struct *p = current;
1058
1059         bprm->unsafe = tracehook_unsafe_exec(p);
1060
1061         if (atomic_read(&p->fs->count) > 1 ||
1062             atomic_read(&p->files->count) > 1 ||
1063             atomic_read(&p->sighand->count) > 1)
1064                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1065 }
1066
1067 /*
1068  * Fill the binprm structure from the inode.
1069  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1070  *
1071  * This may be called multiple times for binary chains (scripts for example).
1072  */
1073 int prepare_binprm(struct linux_binprm *bprm)
1074 {
1075         umode_t mode;
1076         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1077         int retval;
1078
1079         mode = inode->i_mode;
1080         if (bprm->file->f_op == NULL)
1081                 return -EACCES;
1082
1083         /* clear any previous set[ug]id data from a previous binary */
1084         bprm->cred->euid = current_euid();
1085         bprm->cred->egid = current_egid();
1086
1087         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1088                 /* Set-uid? */
1089                 if (mode & S_ISUID) {
1090                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1091                         bprm->cred->euid = inode->i_uid;
1092                 }
1093
1094                 /* Set-gid? */
1095                 /*
1096                  * If setgid is set but no group execute bit then this
1097                  * is a candidate for mandatory locking, not a setgid
1098                  * executable.
1099                  */
1100                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1101                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1102                         bprm->cred->egid = inode->i_gid;
1103                 }
1104         }
1105
1106         /* fill in binprm security blob */
1107         retval = security_bprm_set_creds(bprm);
1108         if (retval)
1109                 return retval;
1110         bprm->cred_prepared = 1;
1111
1112         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1113         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1114 }
1115
1116 EXPORT_SYMBOL(prepare_binprm);
1117
1118 /*
1119  * Arguments are '\0' separated strings found at the location bprm->p
1120  * points to; chop off the first by relocating brpm->p to right after
1121  * the first '\0' encountered.
1122  */
1123 int remove_arg_zero(struct linux_binprm *bprm)
1124 {
1125         int ret = 0;
1126         unsigned long offset;
1127         char *kaddr;
1128         struct page *page;
1129
1130         if (!bprm->argc)
1131                 return 0;
1132
1133         do {
1134                 offset = bprm->p & ~PAGE_MASK;
1135                 page = get_arg_page(bprm, bprm->p, 0);
1136                 if (!page) {
1137                         ret = -EFAULT;
1138                         goto out;
1139                 }
1140                 kaddr = kmap_atomic(page, KM_USER0);
1141
1142                 for (; offset < PAGE_SIZE && kaddr[offset];
1143                                 offset++, bprm->p++)
1144                         ;
1145
1146                 kunmap_atomic(kaddr, KM_USER0);
1147                 put_arg_page(page);
1148
1149                 if (offset == PAGE_SIZE)
1150                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1151         } while (offset == PAGE_SIZE);
1152
1153         bprm->p++;
1154         bprm->argc--;
1155         ret = 0;
1156
1157 out:
1158         return ret;
1159 }
1160 EXPORT_SYMBOL(remove_arg_zero);
1161
1162 /*
1163  * cycle the list of binary formats handler, until one recognizes the image
1164  */
1165 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1166 {
1167         unsigned int depth = bprm->recursion_depth;
1168         int try,retval;
1169         struct linux_binfmt *fmt;
1170
1171         retval = security_bprm_check(bprm);
1172         if (retval)
1173                 return retval;
1174
1175         /* kernel module loader fixup */
1176         /* so we don't try to load run modprobe in kernel space. */
1177         set_fs(USER_DS);
1178
1179         retval = audit_bprm(bprm);
1180         if (retval)
1181                 return retval;
1182
1183         retval = -ENOENT;
1184         for (try=0; try<2; try++) {
1185                 read_lock(&binfmt_lock);
1186                 list_for_each_entry(fmt, &formats, lh) {
1187                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1188                         if (!fn)
1189                                 continue;
1190                         if (!try_module_get(fmt->module))
1191                                 continue;
1192                         read_unlock(&binfmt_lock);
1193                         retval = fn(bprm, regs);
1194                         /*
1195                          * Restore the depth counter to its starting value
1196                          * in this call, so we don't have to rely on every
1197                          * load_binary function to restore it on return.
1198                          */
1199                         bprm->recursion_depth = depth;
1200                         if (retval >= 0) {
1201                                 if (depth == 0)
1202                                         tracehook_report_exec(fmt, bprm, regs);
1203                                 put_binfmt(fmt);
1204                                 allow_write_access(bprm->file);
1205                                 if (bprm->file)
1206                                         fput(bprm->file);
1207                                 bprm->file = NULL;
1208                                 current->did_exec = 1;
1209                                 proc_exec_connector(current);
1210                                 return retval;
1211                         }
1212                         read_lock(&binfmt_lock);
1213                         put_binfmt(fmt);
1214                         if (retval != -ENOEXEC || bprm->mm == NULL)
1215                                 break;
1216                         if (!bprm->file) {
1217                                 read_unlock(&binfmt_lock);
1218                                 return retval;
1219                         }
1220                 }
1221                 read_unlock(&binfmt_lock);
1222                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1223                         break;
1224 #ifdef CONFIG_MODULES
1225                 } else {
1226 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1227                         if (printable(bprm->buf[0]) &&
1228                             printable(bprm->buf[1]) &&
1229                             printable(bprm->buf[2]) &&
1230                             printable(bprm->buf[3]))
1231                                 break; /* -ENOEXEC */
1232                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1233 #endif
1234                 }
1235         }
1236         return retval;
1237 }
1238
1239 EXPORT_SYMBOL(search_binary_handler);
1240
1241 void free_bprm(struct linux_binprm *bprm)
1242 {
1243         free_arg_pages(bprm);
1244         if (bprm->cred)
1245                 abort_creds(bprm->cred);
1246         kfree(bprm);
1247 }
1248
1249 /*
1250  * sys_execve() executes a new program.
1251  */
1252 int do_execve(char * filename,
1253         char __user *__user *argv,
1254         char __user *__user *envp,
1255         struct pt_regs * regs)
1256 {
1257         struct linux_binprm *bprm;
1258         struct file *file;
1259         struct files_struct *displaced;
1260         int retval;
1261
1262         retval = unshare_files(&displaced);
1263         if (retval)
1264                 goto out_ret;
1265
1266         retval = -ENOMEM;
1267         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1268         if (!bprm)
1269                 goto out_files;
1270
1271         retval = mutex_lock_interruptible(&current->cred_exec_mutex);
1272         if (retval < 0)
1273                 goto out_free;
1274
1275         retval = -ENOMEM;
1276         bprm->cred = prepare_exec_creds();
1277         if (!bprm->cred)
1278                 goto out_unlock;
1279         check_unsafe_exec(bprm);
1280
1281         file = open_exec(filename);
1282         retval = PTR_ERR(file);
1283         if (IS_ERR(file))
1284                 goto out_unlock;
1285
1286         sched_exec();
1287
1288         bprm->file = file;
1289         bprm->filename = filename;
1290         bprm->interp = filename;
1291
1292         retval = bprm_mm_init(bprm);
1293         if (retval)
1294                 goto out_file;
1295
1296         bprm->argc = count(argv, MAX_ARG_STRINGS);
1297         if ((retval = bprm->argc) < 0)
1298                 goto out;
1299
1300         bprm->envc = count(envp, MAX_ARG_STRINGS);
1301         if ((retval = bprm->envc) < 0)
1302                 goto out;
1303
1304         retval = prepare_binprm(bprm);
1305         if (retval < 0)
1306                 goto out;
1307
1308         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1309         if (retval < 0)
1310                 goto out;
1311
1312         bprm->exec = bprm->p;
1313         retval = copy_strings(bprm->envc, envp, bprm);
1314         if (retval < 0)
1315                 goto out;
1316
1317         retval = copy_strings(bprm->argc, argv, bprm);
1318         if (retval < 0)
1319                 goto out;
1320
1321         current->flags &= ~PF_KTHREAD;
1322         retval = search_binary_handler(bprm,regs);
1323         if (retval < 0)
1324                 goto out;
1325
1326         /* execve succeeded */
1327         mutex_unlock(&current->cred_exec_mutex);
1328         acct_update_integrals(current);
1329         free_bprm(bprm);
1330         if (displaced)
1331                 put_files_struct(displaced);
1332         return retval;
1333
1334 out:
1335         if (bprm->mm)
1336                 mmput (bprm->mm);
1337
1338 out_file:
1339         if (bprm->file) {
1340                 allow_write_access(bprm->file);
1341                 fput(bprm->file);
1342         }
1343
1344 out_unlock:
1345         mutex_unlock(&current->cred_exec_mutex);
1346
1347 out_free:
1348         free_bprm(bprm);
1349
1350 out_files:
1351         if (displaced)
1352                 reset_files_struct(displaced);
1353 out_ret:
1354         return retval;
1355 }
1356
1357 int set_binfmt(struct linux_binfmt *new)
1358 {
1359         struct linux_binfmt *old = current->binfmt;
1360
1361         if (new) {
1362                 if (!try_module_get(new->module))
1363                         return -1;
1364         }
1365         current->binfmt = new;
1366         if (old)
1367                 module_put(old->module);
1368         return 0;
1369 }
1370
1371 EXPORT_SYMBOL(set_binfmt);
1372
1373 /* format_corename will inspect the pattern parameter, and output a
1374  * name into corename, which must have space for at least
1375  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1376  */
1377 static int format_corename(char *corename, long signr)
1378 {
1379         const struct cred *cred = current_cred();
1380         const char *pat_ptr = core_pattern;
1381         int ispipe = (*pat_ptr == '|');
1382         char *out_ptr = corename;
1383         char *const out_end = corename + CORENAME_MAX_SIZE;
1384         int rc;
1385         int pid_in_pattern = 0;
1386
1387         /* Repeat as long as we have more pattern to process and more output
1388            space */
1389         while (*pat_ptr) {
1390                 if (*pat_ptr != '%') {
1391                         if (out_ptr == out_end)
1392                                 goto out;
1393                         *out_ptr++ = *pat_ptr++;
1394                 } else {
1395                         switch (*++pat_ptr) {
1396                         case 0:
1397                                 goto out;
1398                         /* Double percent, output one percent */
1399                         case '%':
1400                                 if (out_ptr == out_end)
1401                                         goto out;
1402                                 *out_ptr++ = '%';
1403                                 break;
1404                         /* pid */
1405                         case 'p':
1406                                 pid_in_pattern = 1;
1407                                 rc = snprintf(out_ptr, out_end - out_ptr,
1408                                               "%d", task_tgid_vnr(current));
1409                                 if (rc > out_end - out_ptr)
1410                                         goto out;
1411                                 out_ptr += rc;
1412                                 break;
1413                         /* uid */
1414                         case 'u':
1415                                 rc = snprintf(out_ptr, out_end - out_ptr,
1416                                               "%d", cred->uid);
1417                                 if (rc > out_end - out_ptr)
1418                                         goto out;
1419                                 out_ptr += rc;
1420                                 break;
1421                         /* gid */
1422                         case 'g':
1423                                 rc = snprintf(out_ptr, out_end - out_ptr,
1424                                               "%d", cred->gid);
1425                                 if (rc > out_end - out_ptr)
1426                                         goto out;
1427                                 out_ptr += rc;
1428                                 break;
1429                         /* signal that caused the coredump */
1430                         case 's':
1431                                 rc = snprintf(out_ptr, out_end - out_ptr,
1432                                               "%ld", signr);
1433                                 if (rc > out_end - out_ptr)
1434                                         goto out;
1435                                 out_ptr += rc;
1436                                 break;
1437                         /* UNIX time of coredump */
1438                         case 't': {
1439                                 struct timeval tv;
1440                                 do_gettimeofday(&tv);
1441                                 rc = snprintf(out_ptr, out_end - out_ptr,
1442                                               "%lu", tv.tv_sec);
1443                                 if (rc > out_end - out_ptr)
1444                                         goto out;
1445                                 out_ptr += rc;
1446                                 break;
1447                         }
1448                         /* hostname */
1449                         case 'h':
1450                                 down_read(&uts_sem);
1451                                 rc = snprintf(out_ptr, out_end - out_ptr,
1452                                               "%s", utsname()->nodename);
1453                                 up_read(&uts_sem);
1454                                 if (rc > out_end - out_ptr)
1455                                         goto out;
1456                                 out_ptr += rc;
1457                                 break;
1458                         /* executable */
1459                         case 'e':
1460                                 rc = snprintf(out_ptr, out_end - out_ptr,
1461                                               "%s", current->comm);
1462                                 if (rc > out_end - out_ptr)
1463                                         goto out;
1464                                 out_ptr += rc;
1465                                 break;
1466                         /* core limit size */
1467                         case 'c':
1468                                 rc = snprintf(out_ptr, out_end - out_ptr,
1469                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1470                                 if (rc > out_end - out_ptr)
1471                                         goto out;
1472                                 out_ptr += rc;
1473                                 break;
1474                         default:
1475                                 break;
1476                         }
1477                         ++pat_ptr;
1478                 }
1479         }
1480         /* Backward compatibility with core_uses_pid:
1481          *
1482          * If core_pattern does not include a %p (as is the default)
1483          * and core_uses_pid is set, then .%pid will be appended to
1484          * the filename. Do not do this for piped commands. */
1485         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1486                 rc = snprintf(out_ptr, out_end - out_ptr,
1487                               ".%d", task_tgid_vnr(current));
1488                 if (rc > out_end - out_ptr)
1489                         goto out;
1490                 out_ptr += rc;
1491         }
1492 out:
1493         *out_ptr = 0;
1494         return ispipe;
1495 }
1496
1497 static int zap_process(struct task_struct *start)
1498 {
1499         struct task_struct *t;
1500         int nr = 0;
1501
1502         start->signal->flags = SIGNAL_GROUP_EXIT;
1503         start->signal->group_stop_count = 0;
1504
1505         t = start;
1506         do {
1507                 if (t != current && t->mm) {
1508                         sigaddset(&t->pending.signal, SIGKILL);
1509                         signal_wake_up(t, 1);
1510                         nr++;
1511                 }
1512         } while_each_thread(start, t);
1513
1514         return nr;
1515 }
1516
1517 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1518                                 struct core_state *core_state, int exit_code)
1519 {
1520         struct task_struct *g, *p;
1521         unsigned long flags;
1522         int nr = -EAGAIN;
1523
1524         spin_lock_irq(&tsk->sighand->siglock);
1525         if (!signal_group_exit(tsk->signal)) {
1526                 mm->core_state = core_state;
1527                 tsk->signal->group_exit_code = exit_code;
1528                 nr = zap_process(tsk);
1529         }
1530         spin_unlock_irq(&tsk->sighand->siglock);
1531         if (unlikely(nr < 0))
1532                 return nr;
1533
1534         if (atomic_read(&mm->mm_users) == nr + 1)
1535                 goto done;
1536         /*
1537          * We should find and kill all tasks which use this mm, and we should
1538          * count them correctly into ->nr_threads. We don't take tasklist
1539          * lock, but this is safe wrt:
1540          *
1541          * fork:
1542          *      None of sub-threads can fork after zap_process(leader). All
1543          *      processes which were created before this point should be
1544          *      visible to zap_threads() because copy_process() adds the new
1545          *      process to the tail of init_task.tasks list, and lock/unlock
1546          *      of ->siglock provides a memory barrier.
1547          *
1548          * do_exit:
1549          *      The caller holds mm->mmap_sem. This means that the task which
1550          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1551          *      its ->mm.
1552          *
1553          * de_thread:
1554          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1555          *      we must see either old or new leader, this does not matter.
1556          *      However, it can change p->sighand, so lock_task_sighand(p)
1557          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1558          *      it can't fail.
1559          *
1560          *      Note also that "g" can be the old leader with ->mm == NULL
1561          *      and already unhashed and thus removed from ->thread_group.
1562          *      This is OK, __unhash_process()->list_del_rcu() does not
1563          *      clear the ->next pointer, we will find the new leader via
1564          *      next_thread().
1565          */
1566         rcu_read_lock();
1567         for_each_process(g) {
1568                 if (g == tsk->group_leader)
1569                         continue;
1570                 if (g->flags & PF_KTHREAD)
1571                         continue;
1572                 p = g;
1573                 do {
1574                         if (p->mm) {
1575                                 if (unlikely(p->mm == mm)) {
1576                                         lock_task_sighand(p, &flags);
1577                                         nr += zap_process(p);
1578                                         unlock_task_sighand(p, &flags);
1579                                 }
1580                                 break;
1581                         }
1582                 } while_each_thread(g, p);
1583         }
1584         rcu_read_unlock();
1585 done:
1586         atomic_set(&core_state->nr_threads, nr);
1587         return nr;
1588 }
1589
1590 static int coredump_wait(int exit_code, struct core_state *core_state)
1591 {
1592         struct task_struct *tsk = current;
1593         struct mm_struct *mm = tsk->mm;
1594         struct completion *vfork_done;
1595         int core_waiters;
1596
1597         init_completion(&core_state->startup);
1598         core_state->dumper.task = tsk;
1599         core_state->dumper.next = NULL;
1600         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1601         up_write(&mm->mmap_sem);
1602
1603         if (unlikely(core_waiters < 0))
1604                 goto fail;
1605
1606         /*
1607          * Make sure nobody is waiting for us to release the VM,
1608          * otherwise we can deadlock when we wait on each other
1609          */
1610         vfork_done = tsk->vfork_done;
1611         if (vfork_done) {
1612                 tsk->vfork_done = NULL;
1613                 complete(vfork_done);
1614         }
1615
1616         if (core_waiters)
1617                 wait_for_completion(&core_state->startup);
1618 fail:
1619         return core_waiters;
1620 }
1621
1622 static void coredump_finish(struct mm_struct *mm)
1623 {
1624         struct core_thread *curr, *next;
1625         struct task_struct *task;
1626
1627         next = mm->core_state->dumper.next;
1628         while ((curr = next) != NULL) {
1629                 next = curr->next;
1630                 task = curr->task;
1631                 /*
1632                  * see exit_mm(), curr->task must not see
1633                  * ->task == NULL before we read ->next.
1634                  */
1635                 smp_mb();
1636                 curr->task = NULL;
1637                 wake_up_process(task);
1638         }
1639
1640         mm->core_state = NULL;
1641 }
1642
1643 /*
1644  * set_dumpable converts traditional three-value dumpable to two flags and
1645  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1646  * these bits are not changed atomically.  So get_dumpable can observe the
1647  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1648  * return either old dumpable or new one by paying attention to the order of
1649  * modifying the bits.
1650  *
1651  * dumpable |   mm->flags (binary)
1652  * old  new | initial interim  final
1653  * ---------+-----------------------
1654  *  0    1  |   00      01      01
1655  *  0    2  |   00      10(*)   11
1656  *  1    0  |   01      00      00
1657  *  1    2  |   01      11      11
1658  *  2    0  |   11      10(*)   00
1659  *  2    1  |   11      11      01
1660  *
1661  * (*) get_dumpable regards interim value of 10 as 11.
1662  */
1663 void set_dumpable(struct mm_struct *mm, int value)
1664 {
1665         switch (value) {
1666         case 0:
1667                 clear_bit(MMF_DUMPABLE, &mm->flags);
1668                 smp_wmb();
1669                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1670                 break;
1671         case 1:
1672                 set_bit(MMF_DUMPABLE, &mm->flags);
1673                 smp_wmb();
1674                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1675                 break;
1676         case 2:
1677                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1678                 smp_wmb();
1679                 set_bit(MMF_DUMPABLE, &mm->flags);
1680                 break;
1681         }
1682 }
1683
1684 int get_dumpable(struct mm_struct *mm)
1685 {
1686         int ret;
1687
1688         ret = mm->flags & 0x3;
1689         return (ret >= 2) ? 2 : ret;
1690 }
1691
1692 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1693 {
1694         struct core_state core_state;
1695         char corename[CORENAME_MAX_SIZE + 1];
1696         struct mm_struct *mm = current->mm;
1697         struct linux_binfmt * binfmt;
1698         struct inode * inode;
1699         struct file * file;
1700         const struct cred *old_cred;
1701         struct cred *cred;
1702         int retval = 0;
1703         int flag = 0;
1704         int ispipe = 0;
1705         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1706         char **helper_argv = NULL;
1707         int helper_argc = 0;
1708         char *delimit;
1709
1710         audit_core_dumps(signr);
1711
1712         binfmt = current->binfmt;
1713         if (!binfmt || !binfmt->core_dump)
1714                 goto fail;
1715
1716         cred = prepare_creds();
1717         if (!cred) {
1718                 retval = -ENOMEM;
1719                 goto fail;
1720         }
1721
1722         down_write(&mm->mmap_sem);
1723         /*
1724          * If another thread got here first, or we are not dumpable, bail out.
1725          */
1726         if (mm->core_state || !get_dumpable(mm)) {
1727                 up_write(&mm->mmap_sem);
1728                 put_cred(cred);
1729                 goto fail;
1730         }
1731
1732         /*
1733          *      We cannot trust fsuid as being the "true" uid of the
1734          *      process nor do we know its entire history. We only know it
1735          *      was tainted so we dump it as root in mode 2.
1736          */
1737         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1738                 flag = O_EXCL;          /* Stop rewrite attacks */
1739                 cred->fsuid = 0;        /* Dump root private */
1740         }
1741
1742         retval = coredump_wait(exit_code, &core_state);
1743         if (retval < 0) {
1744                 put_cred(cred);
1745                 goto fail;
1746         }
1747
1748         old_cred = override_creds(cred);
1749
1750         /*
1751          * Clear any false indication of pending signals that might
1752          * be seen by the filesystem code called to write the core file.
1753          */
1754         clear_thread_flag(TIF_SIGPENDING);
1755
1756         /*
1757          * lock_kernel() because format_corename() is controlled by sysctl, which
1758          * uses lock_kernel()
1759          */
1760         lock_kernel();
1761         ispipe = format_corename(corename, signr);
1762         unlock_kernel();
1763         /*
1764          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1765          * to a pipe.  Since we're not writing directly to the filesystem
1766          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1767          * created unless the pipe reader choses to write out the core file
1768          * at which point file size limits and permissions will be imposed
1769          * as it does with any other process
1770          */
1771         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1772                 goto fail_unlock;
1773
1774         if (ispipe) {
1775                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1776                 /* Terminate the string before the first option */
1777                 delimit = strchr(corename, ' ');
1778                 if (delimit)
1779                         *delimit = '\0';
1780                 delimit = strrchr(helper_argv[0], '/');
1781                 if (delimit)
1782                         delimit++;
1783                 else
1784                         delimit = helper_argv[0];
1785                 if (!strcmp(delimit, current->comm)) {
1786                         printk(KERN_NOTICE "Recursive core dump detected, "
1787                                         "aborting\n");
1788                         goto fail_unlock;
1789                 }
1790
1791                 core_limit = RLIM_INFINITY;
1792
1793                 /* SIGPIPE can happen, but it's just never processed */
1794                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1795                                 &file)) {
1796                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1797                                corename);
1798                         goto fail_unlock;
1799                 }
1800         } else
1801                 file = filp_open(corename,
1802                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1803                                  0600);
1804         if (IS_ERR(file))
1805                 goto fail_unlock;
1806         inode = file->f_path.dentry->d_inode;
1807         if (inode->i_nlink > 1)
1808                 goto close_fail;        /* multiple links - don't dump */
1809         if (!ispipe && d_unhashed(file->f_path.dentry))
1810                 goto close_fail;
1811
1812         /* AK: actually i see no reason to not allow this for named pipes etc.,
1813            but keep the previous behaviour for now. */
1814         if (!ispipe && !S_ISREG(inode->i_mode))
1815                 goto close_fail;
1816         /*
1817          * Dont allow local users get cute and trick others to coredump
1818          * into their pre-created files:
1819          */
1820         if (inode->i_uid != current_fsuid())
1821                 goto close_fail;
1822         if (!file->f_op)
1823                 goto close_fail;
1824         if (!file->f_op->write)
1825                 goto close_fail;
1826         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1827                 goto close_fail;
1828
1829         retval = binfmt->core_dump(signr, regs, file, core_limit);
1830
1831         if (retval)
1832                 current->signal->group_exit_code |= 0x80;
1833 close_fail:
1834         filp_close(file, NULL);
1835 fail_unlock:
1836         if (helper_argv)
1837                 argv_free(helper_argv);
1838
1839         revert_creds(old_cred);
1840         put_cred(cred);
1841         coredump_finish(mm);
1842 fail:
1843         return retval;
1844 }