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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/highmem.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/key.h>
  38 #include <linux/personality.h>
  39 #include <linux/binfmts.h>
  40 #include <linux/utsname.h>
  41 #include <linux/pid_namespace.h>
  42 #include <linux/module.h>
  43 #include <linux/namei.h>
  44 #include <linux/proc_fs.h>
  45 #include <linux/mount.h>
  46 #include <linux/security.h>
  47 #include <linux/syscalls.h>
  48 #include <linux/tsacct_kern.h>
  49 #include <linux/cn_proc.h>
  50 #include <linux/audit.h>
  51 #include <linux/tracehook.h>
  52
  53 #include <asm/uaccess.h>
  54 #include <asm/mmu_context.h>
  55 #include <asm/tlb.h>
  56
  57 #ifdef CONFIG_KMOD
  58 #include <linux/kmod.h>
  59 #endif
  60
  61 #ifdef __alpha__
  62 /* for /sbin/loader handling in search_binary_handler() */
  63 #include <linux/a.out.h>
  64 #endif
  65
  66 int core_uses_pid;
  67 char core_pattern[CORENAME_MAX_SIZE] = "core";
  68 int suid_dumpable = 0;
  69
  70 /* The maximal length of core_pattern is also specified in sysctl.c */
  71
  72 static LIST_HEAD(formats);
  73 static DEFINE_RWLOCK(binfmt_lock);
  74
  75 int register_binfmt(struct linux_binfmt * fmt)
  76 {
  77         if (!fmt)
  78                 return -EINVAL;
  79         write_lock(&binfmt_lock);
  80         list_add(&fmt->lh, &formats);
  81         write_unlock(&binfmt_lock);
  82         return 0;
  83 }
  84
  85 EXPORT_SYMBOL(register_binfmt);
  86
  87 void unregister_binfmt(struct linux_binfmt * fmt)
  88 {
  89         write_lock(&binfmt_lock);
  90         list_del(&fmt->lh);
  91         write_unlock(&binfmt_lock);
  92 }
  93
  94 EXPORT_SYMBOL(unregister_binfmt);
  95
  96 static inline void put_binfmt(struct linux_binfmt * fmt)
  97 {
  98         module_put(fmt->module);
  99 }
 100
 101 /*
 102  * Note that a shared library must be both readable and executable due to
 103  * security reasons.
 104  *
 105  * Also note that we take the address to load from from the file itself.
 106  */
 107 asmlinkage long sys_uselib(const char __user * library)
 108 {
 109         struct file *file;
 110         struct nameidata nd;
 111         char *tmp = getname(library);
 112         int error = PTR_ERR(tmp);
 113
 114         if (!IS_ERR(tmp)) {
 115                 error = path_lookup_open(AT_FDCWD, tmp,
 116                                          LOOKUP_FOLLOW, &nd,
 117                                          FMODE_READ|FMODE_EXEC);
 118                 putname(tmp);
 119         }
 120         if (error)
 121                 goto out;
 122
 123         error = -EINVAL;
 124         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 125                 goto exit;
 126
 127         error = -EACCES;
 128         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 129                 goto exit;
 130
 131         error = vfs_permission(&nd, MAY_READ | MAY_EXEC | MAY_OPEN);
 132         if (error)
 133                 goto exit;
 134
 135         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 136         error = PTR_ERR(file);
 137         if (IS_ERR(file))
 138                 goto out;
 139
 140         error = -ENOEXEC;
 141         if(file->f_op) {
 142                 struct linux_binfmt * fmt;
 143
 144                 read_lock(&binfmt_lock);
 145                 list_for_each_entry(fmt, &formats, lh) {
 146                         if (!fmt->load_shlib)
 147                                 continue;
 148                         if (!try_module_get(fmt->module))
 149                                 continue;
 150                         read_unlock(&binfmt_lock);
 151                         error = fmt->load_shlib(file);
 152                         read_lock(&binfmt_lock);
 153                         put_binfmt(fmt);
 154                         if (error != -ENOEXEC)
 155                                 break;
 156                 }
 157                 read_unlock(&binfmt_lock);
 158         }
 159         fput(file);
 160 out:
 161         return error;
 162 exit:
 163         release_open_intent(&nd);
 164         path_put(&nd.path);
 165         goto out;
 166 }
 167
 168 #ifdef CONFIG_MMU
 169
 170 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 171                 int write)
 172 {
 173         struct page *page;
 174         int ret;
 175
 176 #ifdef CONFIG_STACK_GROWSUP
 177         if (write) {
 178                 ret = expand_stack_downwards(bprm->vma, pos);
 179                 if (ret < 0)
 180                         return NULL;
 181         }
 182 #endif
 183         ret = get_user_pages(current, bprm->mm, pos,
 184                         1, write, 1, &page, NULL);
 185         if (ret <= 0)
 186                 return NULL;
 187
 188         if (write) {
 189                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 190                 struct rlimit *rlim;
 191
 192                 /*
 193                  * We've historically supported up to 32 pages (ARG_MAX)
 194                  * of argument strings even with small stacks
 195                  */
 196                 if (size <= ARG_MAX)
 197                         return page;
 198
 199                 /*
 200                  * Limit to 1/4-th the stack size for the argv+env strings.
 201                  * This ensures that:
 202                  *  - the remaining binfmt code will not run out of stack space,
 203                  *  - the program will have a reasonable amount of stack left
 204                  *    to work from.
 205                  */
 206                 rlim = current->signal->rlim;
 207                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 208                         put_page(page);
 209                         return NULL;
 210                 }
 211         }
 212
 213         return page;
 214 }
 215
 216 static void put_arg_page(struct page *page)
 217 {
 218         put_page(page);
 219 }
 220
 221 static void free_arg_page(struct linux_binprm *bprm, int i)
 222 {
 223 }
 224
 225 static void free_arg_pages(struct linux_binprm *bprm)
 226 {
 227 }
 228
 229 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 230                 struct page *page)
 231 {
 232         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 233 }
 234
 235 static int __bprm_mm_init(struct linux_binprm *bprm)
 236 {
 237         int err = -ENOMEM;
 238         struct vm_area_struct *vma = NULL;
 239         struct mm_struct *mm = bprm->mm;
 240
 241         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 242         if (!vma)
 243                 goto err;
 244
 245         down_write(&mm->mmap_sem);
 246         vma->vm_mm = mm;
 247
 248         /*
 249          * Place the stack at the largest stack address the architecture
 250          * supports. Later, we'll move this to an appropriate place. We don't
 251          * use STACK_TOP because that can depend on attributes which aren't
 252          * configured yet.
 253          */
 254         vma->vm_end = STACK_TOP_MAX;
 255         vma->vm_start = vma->vm_end - PAGE_SIZE;
 256
 257         vma->vm_flags = VM_STACK_FLAGS;
 258         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 259         err = insert_vm_struct(mm, vma);
 260         if (err) {
 261                 up_write(&mm->mmap_sem);
 262                 goto err;
 263         }
 264
 265         mm->stack_vm = mm->total_vm = 1;
 266         up_write(&mm->mmap_sem);
 267
 268         bprm->p = vma->vm_end - sizeof(void *);
 269
 270         return 0;
 271
 272 err:
 273         if (vma) {
 274                 bprm->vma = NULL;
 275                 kmem_cache_free(vm_area_cachep, vma);
 276         }
 277
 278         return err;
 279 }
 280
 281 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 282 {
 283         return len <= MAX_ARG_STRLEN;
 284 }
 285
 286 #else
 287
 288 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 289                 int write)
 290 {
 291         struct page *page;
 292
 293         page = bprm->page[pos / PAGE_SIZE];
 294         if (!page && write) {
 295                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 296                 if (!page)
 297                         return NULL;
 298                 bprm->page[pos / PAGE_SIZE] = page;
 299         }
 300
 301         return page;
 302 }
 303
 304 static void put_arg_page(struct page *page)
 305 {
 306 }
 307
 308 static void free_arg_page(struct linux_binprm *bprm, int i)
 309 {
 310         if (bprm->page[i]) {
 311                 __free_page(bprm->page[i]);
 312                 bprm->page[i] = NULL;
 313         }
 314 }
 315
 316 static void free_arg_pages(struct linux_binprm *bprm)
 317 {
 318         int i;
 319
 320         for (i = 0; i < MAX_ARG_PAGES; i++)
 321                 free_arg_page(bprm, i);
 322 }
 323
 324 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 325                 struct page *page)
 326 {
 327 }
 328
 329 static int __bprm_mm_init(struct linux_binprm *bprm)
 330 {
 331         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 332         return 0;
 333 }
 334
 335 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 336 {
 337         return len <= bprm->p;
 338 }
 339
 340 #endif /* CONFIG_MMU */
 341
 342 /*
 343  * Create a new mm_struct and populate it with a temporary stack
 344  * vm_area_struct.  We don't have enough context at this point to set the stack
 345  * flags, permissions, and offset, so we use temporary values.  We'll update
 346  * them later in setup_arg_pages().
 347  */
 348 int bprm_mm_init(struct linux_binprm *bprm)
 349 {
 350         int err;
 351         struct mm_struct *mm = NULL;
 352
 353         bprm->mm = mm = mm_alloc();
 354         err = -ENOMEM;
 355         if (!mm)
 356                 goto err;
 357
 358         err = init_new_context(current, mm);
 359         if (err)
 360                 goto err;
 361
 362         err = __bprm_mm_init(bprm);
 363         if (err)
 364                 goto err;
 365
 366         return 0;
 367
 368 err:
 369         if (mm) {
 370                 bprm->mm = NULL;
 371                 mmdrop(mm);
 372         }
 373
 374         return err;
 375 }
 376
 377 /*
 378  * count() counts the number of strings in array ARGV.
 379  */
 380 static int count(char __user * __user * argv, int max)
 381 {
 382         int i = 0;
 383
 384         if (argv != NULL) {
 385                 for (;;) {
 386                         char __user * p;
 387
 388                         if (get_user(p, argv))
 389                                 return -EFAULT;
 390                         if (!p)
 391                                 break;
 392                         argv++;
 393                         if(++i > max)
 394                                 return -E2BIG;
 395                         cond_resched();
 396                 }
 397         }
 398         return i;
 399 }
 400
 401 /*
 402  * 'copy_strings()' copies argument/environment strings from the old
 403  * processes's memory to the new process's stack.  The call to get_user_pages()
 404  * ensures the destination page is created and not swapped out.
 405  */
 406 static int copy_strings(int argc, char __user * __user * argv,
 407                         struct linux_binprm *bprm)
 408 {
 409         struct page *kmapped_page = NULL;
 410         char *kaddr = NULL;
 411         unsigned long kpos = 0;
 412         int ret;
 413
 414         while (argc-- > 0) {
 415                 char __user *str;
 416                 int len;
 417                 unsigned long pos;
 418
 419                 if (get_user(str, argv+argc) ||
 420                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 421                         ret = -EFAULT;
 422                         goto out;
 423                 }
 424
 425                 if (!valid_arg_len(bprm, len)) {
 426                         ret = -E2BIG;
 427                         goto out;
 428                 }
 429
 430                 /* We're going to work our way backwords. */
 431                 pos = bprm->p;
 432                 str += len;
 433                 bprm->p -= len;
 434
 435                 while (len > 0) {
 436                         int offset, bytes_to_copy;
 437
 438                         offset = pos % PAGE_SIZE;
 439                         if (offset == 0)
 440                                 offset = PAGE_SIZE;
 441
 442                         bytes_to_copy = offset;
 443                         if (bytes_to_copy > len)
 444                                 bytes_to_copy = len;
 445
 446                         offset -= bytes_to_copy;
 447                         pos -= bytes_to_copy;
 448                         str -= bytes_to_copy;
 449                         len -= bytes_to_copy;
 450
 451                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 452                                 struct page *page;
 453
 454                                 page = get_arg_page(bprm, pos, 1);
 455                                 if (!page) {
 456                                         ret = -E2BIG;
 457                                         goto out;
 458                                 }
 459
 460                                 if (kmapped_page) {
 461                                         flush_kernel_dcache_page(kmapped_page);
 462                                         kunmap(kmapped_page);
 463                                         put_arg_page(kmapped_page);
 464                                 }
 465                                 kmapped_page = page;
 466                                 kaddr = kmap(kmapped_page);
 467                                 kpos = pos & PAGE_MASK;
 468                                 flush_arg_page(bprm, kpos, kmapped_page);
 469                         }
 470                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 471                                 ret = -EFAULT;
 472                                 goto out;
 473                         }
 474                 }
 475         }
 476         ret = 0;
 477 out:
 478         if (kmapped_page) {
 479                 flush_kernel_dcache_page(kmapped_page);
 480                 kunmap(kmapped_page);
 481                 put_arg_page(kmapped_page);
 482         }
 483         return ret;
 484 }
 485
 486 /*
 487  * Like copy_strings, but get argv and its values from kernel memory.
 488  */
 489 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 490 {
 491         int r;
 492         mm_segment_t oldfs = get_fs();
 493         set_fs(KERNEL_DS);
 494         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 495         set_fs(oldfs);
 496         return r;
 497 }
 498 EXPORT_SYMBOL(copy_strings_kernel);
 499
 500 #ifdef CONFIG_MMU
 501
 502 /*
 503  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 504  * the binfmt code determines where the new stack should reside, we shift it to
 505  * its final location.  The process proceeds as follows:
 506  *
 507  * 1) Use shift to calculate the new vma endpoints.
 508  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 509  *    arguments passed to subsequent functions are consistent.
 510  * 3) Move vma's page tables to the new range.
 511  * 4) Free up any cleared pgd range.
 512  * 5) Shrink the vma to cover only the new range.
 513  */
 514 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 515 {
 516         struct mm_struct *mm = vma->vm_mm;
 517         unsigned long old_start = vma->vm_start;
 518         unsigned long old_end = vma->vm_end;
 519         unsigned long length = old_end - old_start;
 520         unsigned long new_start = old_start - shift;
 521         unsigned long new_end = old_end - shift;
 522         struct mmu_gather *tlb;
 523
 524         BUG_ON(new_start > new_end);
 525
 526         /*
 527          * ensure there are no vmas between where we want to go
 528          * and where we are
 529          */
 530         if (vma != find_vma(mm, new_start))
 531                 return -EFAULT;
 532
 533         /*
 534          * cover the whole range: [new_start, old_end)
 535          */
 536         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 537
 538         /*
 539          * move the page tables downwards, on failure we rely on
 540          * process cleanup to remove whatever mess we made.
 541          */
 542         if (length != move_page_tables(vma, old_start,
 543                                        vma, new_start, length))
 544                 return -ENOMEM;
 545
 546         lru_add_drain();
 547         tlb = tlb_gather_mmu(mm, 0);
 548         if (new_end > old_start) {
 549                 /*
 550                  * when the old and new regions overlap clear from new_end.
 551                  */
 552                 free_pgd_range(tlb, new_end, old_end, new_end,
 553                         vma->vm_next ? vma->vm_next->vm_start : 0);
 554         } else {
 555                 /*
 556                  * otherwise, clean from old_start; this is done to not touch
 557                  * the address space in [new_end, old_start) some architectures
 558                  * have constraints on va-space that make this illegal (IA64) -
 559                  * for the others its just a little faster.
 560                  */
 561                 free_pgd_range(tlb, old_start, old_end, new_end,
 562                         vma->vm_next ? vma->vm_next->vm_start : 0);
 563         }
 564         tlb_finish_mmu(tlb, new_end, old_end);
 565
 566         /*
 567          * shrink the vma to just the new range.
 568          */
 569         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 570
 571         return 0;
 572 }
 573
 574 #define EXTRA_STACK_VM_PAGES    20      /* random */
 575
 576 /*
 577  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 578  * the stack is optionally relocated, and some extra space is added.
 579  */
 580 int setup_arg_pages(struct linux_binprm *bprm,
 581                     unsigned long stack_top,
 582                     int executable_stack)
 583 {
 584         unsigned long ret;
 585         unsigned long stack_shift;
 586         struct mm_struct *mm = current->mm;
 587         struct vm_area_struct *vma = bprm->vma;
 588         struct vm_area_struct *prev = NULL;
 589         unsigned long vm_flags;
 590         unsigned long stack_base;
 591
 592 #ifdef CONFIG_STACK_GROWSUP
 593         /* Limit stack size to 1GB */
 594         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 595         if (stack_base > (1 << 30))
 596                 stack_base = 1 << 30;
 597
 598         /* Make sure we didn't let the argument array grow too large. */
 599         if (vma->vm_end - vma->vm_start > stack_base)
 600                 return -ENOMEM;
 601
 602         stack_base = PAGE_ALIGN(stack_top - stack_base);
 603
 604         stack_shift = vma->vm_start - stack_base;
 605         mm->arg_start = bprm->p - stack_shift;
 606         bprm->p = vma->vm_end - stack_shift;
 607 #else
 608         stack_top = arch_align_stack(stack_top);
 609         stack_top = PAGE_ALIGN(stack_top);
 610         stack_shift = vma->vm_end - stack_top;
 611
 612         bprm->p -= stack_shift;
 613         mm->arg_start = bprm->p;
 614 #endif
 615
 616         if (bprm->loader)
 617                 bprm->loader -= stack_shift;
 618         bprm->exec -= stack_shift;
 619
 620         down_write(&mm->mmap_sem);
 621         vm_flags = VM_STACK_FLAGS;
 622
 623         /*
 624          * Adjust stack execute permissions; explicitly enable for
 625          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 626          * (arch default) otherwise.
 627          */
 628         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 629                 vm_flags |= VM_EXEC;
 630         else if (executable_stack == EXSTACK_DISABLE_X)
 631                 vm_flags &= ~VM_EXEC;
 632         vm_flags |= mm->def_flags;
 633
 634         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 635                         vm_flags);
 636         if (ret)
 637                 goto out_unlock;
 638         BUG_ON(prev != vma);
 639
 640         /* Move stack pages down in memory. */
 641         if (stack_shift) {
 642                 ret = shift_arg_pages(vma, stack_shift);
 643                 if (ret) {
 644                         up_write(&mm->mmap_sem);
 645                         return ret;
 646                 }
 647         }
 648
 649 #ifdef CONFIG_STACK_GROWSUP
 650         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 651 #else
 652         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 653 #endif
 654         ret = expand_stack(vma, stack_base);
 655         if (ret)
 656                 ret = -EFAULT;
 657
 658 out_unlock:
 659         up_write(&mm->mmap_sem);
 660         return 0;
 661 }
 662 EXPORT_SYMBOL(setup_arg_pages);
 663
 664 #endif /* CONFIG_MMU */
 665
 666 struct file *open_exec(const char *name)
 667 {
 668         struct nameidata nd;
 669         struct file *file;
 670         int err;
 671
 672         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
 673                                 FMODE_READ|FMODE_EXEC);
 674         if (err)
 675                 goto out;
 676
 677         err = -EACCES;
 678         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 679                 goto out_path_put;
 680
 681         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 682                 goto out_path_put;
 683
 684         err = vfs_permission(&nd, MAY_EXEC | MAY_OPEN);
 685         if (err)
 686                 goto out_path_put;
 687
 688         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 689         if (IS_ERR(file))
 690                 return file;
 691
 692         err = deny_write_access(file);
 693         if (err) {
 694                 fput(file);
 695                 goto out;
 696         }
 697
 698         return file;
 699
 700  out_path_put:
 701         release_open_intent(&nd);
 702         path_put(&nd.path);
 703  out:
 704         return ERR_PTR(err);
 705 }
 706 EXPORT_SYMBOL(open_exec);
 707
 708 int kernel_read(struct file *file, unsigned long offset,
 709         char *addr, unsigned long count)
 710 {
 711         mm_segment_t old_fs;
 712         loff_t pos = offset;
 713         int result;
 714
 715         old_fs = get_fs();
 716         set_fs(get_ds());
 717         /* The cast to a user pointer is valid due to the set_fs() */
 718         result = vfs_read(file, (void __user *)addr, count, &pos);
 719         set_fs(old_fs);
 720         return result;
 721 }
 722
 723 EXPORT_SYMBOL(kernel_read);
 724
 725 static int exec_mmap(struct mm_struct *mm)
 726 {
 727         struct task_struct *tsk;
 728         struct mm_struct * old_mm, *active_mm;
 729
 730         /* Notify parent that we're no longer interested in the old VM */
 731         tsk = current;
 732         old_mm = current->mm;
 733         mm_release(tsk, old_mm);
 734
 735         if (old_mm) {
 736                 /*
 737                  * Make sure that if there is a core dump in progress
 738                  * for the old mm, we get out and die instead of going
 739                  * through with the exec.  We must hold mmap_sem around
 740                  * checking core_state and changing tsk->mm.
 741                  */
 742                 down_read(&old_mm->mmap_sem);
 743                 if (unlikely(old_mm->core_state)) {
 744                         up_read(&old_mm->mmap_sem);
 745                         return -EINTR;
 746                 }
 747         }
 748         task_lock(tsk);
 749         active_mm = tsk->active_mm;
 750         tsk->mm = mm;
 751         tsk->active_mm = mm;
 752         activate_mm(active_mm, mm);
 753         task_unlock(tsk);
 754         mm_update_next_owner(old_mm);
 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                 mmput(old_mm);
 760                 return 0;
 761         }
 762         mmdrop(active_mm);
 763         return 0;
 764 }
 765
 766 /*
 767  * This function makes sure the current process has its own signal table,
 768  * so that flush_signal_handlers can later reset the handlers without
 769  * disturbing other processes.  (Other processes might share the signal
 770  * table via the CLONE_SIGHAND option to clone().)
 771  */
 772 static int de_thread(struct task_struct *tsk)
 773 {
 774         struct signal_struct *sig = tsk->signal;
 775         struct sighand_struct *oldsighand = tsk->sighand;
 776         spinlock_t *lock = &oldsighand->siglock;
 777         struct task_struct *leader = NULL;
 778         int count;
 779
 780         if (thread_group_empty(tsk))
 781                 goto no_thread_group;
 782
 783         /*
 784          * Kill all other threads in the thread group.
 785          */
 786         spin_lock_irq(lock);
 787         if (signal_group_exit(sig)) {
 788                 /*
 789                  * Another group action in progress, just
 790                  * return so that the signal is processed.
 791                  */
 792                 spin_unlock_irq(lock);
 793                 return -EAGAIN;
 794         }
 795         sig->group_exit_task = tsk;
 796         zap_other_threads(tsk);
 797
 798         /* Account for the thread group leader hanging around: */
 799         count = thread_group_leader(tsk) ? 1 : 2;
 800         sig->notify_count = count;
 801         while (atomic_read(&sig->count) > count) {
 802                 __set_current_state(TASK_UNINTERRUPTIBLE);
 803                 spin_unlock_irq(lock);
 804                 schedule();
 805                 spin_lock_irq(lock);
 806         }
 807         spin_unlock_irq(lock);
 808
 809         /*
 810          * At this point all other threads have exited, all we have to
 811          * do is to wait for the thread group leader to become inactive,
 812          * and to assume its PID:
 813          */
 814         if (!thread_group_leader(tsk)) {
 815                 leader = tsk->group_leader;
 816
 817                 sig->notify_count = -1; /* for exit_notify() */
 818                 for (;;) {
 819                         write_lock_irq(&tasklist_lock);
 820                         if (likely(leader->exit_state))
 821                                 break;
 822                         __set_current_state(TASK_UNINTERRUPTIBLE);
 823                         write_unlock_irq(&tasklist_lock);
 824                         schedule();
 825                 }
 826
 827                 if (unlikely(task_child_reaper(tsk) == leader))
 828                         task_active_pid_ns(tsk)->child_reaper = tsk;
 829                 /*
 830                  * The only record we have of the real-time age of a
 831                  * process, regardless of execs it's done, is start_time.
 832                  * All the past CPU time is accumulated in signal_struct
 833                  * from sister threads now dead.  But in this non-leader
 834                  * exec, nothing survives from the original leader thread,
 835                  * whose birth marks the true age of this process now.
 836                  * When we take on its identity by switching to its PID, we
 837                  * also take its birthdate (always earlier than our own).
 838                  */
 839                 tsk->start_time = leader->start_time;
 840
 841                 BUG_ON(!same_thread_group(leader, tsk));
 842                 BUG_ON(has_group_leader_pid(tsk));
 843                 /*
 844                  * An exec() starts a new thread group with the
 845                  * TGID of the previous thread group. Rehash the
 846                  * two threads with a switched PID, and release
 847                  * the former thread group leader:
 848                  */
 849
 850                 /* Become a process group leader with the old leader's pid.
 851                  * The old leader becomes a thread of the this thread group.
 852                  * Note: The old leader also uses this pid until release_task
 853                  *       is called.  Odd but simple and correct.
 854                  */
 855                 detach_pid(tsk, PIDTYPE_PID);
 856                 tsk->pid = leader->pid;
 857                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 858                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 859                 transfer_pid(leader, tsk, PIDTYPE_SID);
 860                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 861
 862                 tsk->group_leader = tsk;
 863                 leader->group_leader = tsk;
 864
 865                 tsk->exit_signal = SIGCHLD;
 866
 867                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 868                 leader->exit_state = EXIT_DEAD;
 869
 870                 write_unlock_irq(&tasklist_lock);
 871         }
 872
 873         sig->group_exit_task = NULL;
 874         sig->notify_count = 0;
 875
 876 no_thread_group:
 877         exit_itimers(sig);
 878         flush_itimer_signals();
 879         if (leader)
 880                 release_task(leader);
 881
 882         if (atomic_read(&oldsighand->count) != 1) {
 883                 struct sighand_struct *newsighand;
 884                 /*
 885                  * This ->sighand is shared with the CLONE_SIGHAND
 886                  * but not CLONE_THREAD task, switch to the new one.
 887                  */
 888                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 889                 if (!newsighand)
 890                         return -ENOMEM;
 891
 892                 atomic_set(&newsighand->count, 1);
 893                 memcpy(newsighand->action, oldsighand->action,
 894                        sizeof(newsighand->action));
 895
 896                 write_lock_irq(&tasklist_lock);
 897                 spin_lock(&oldsighand->siglock);
 898                 rcu_assign_pointer(tsk->sighand, newsighand);
 899                 spin_unlock(&oldsighand->siglock);
 900                 write_unlock_irq(&tasklist_lock);
 901
 902                 __cleanup_sighand(oldsighand);
 903         }
 904
 905         BUG_ON(!thread_group_leader(tsk));
 906         return 0;
 907 }
 908
 909 /*
 910  * These functions flushes out all traces of the currently running executable
 911  * so that a new one can be started
 912  */
 913 static void flush_old_files(struct files_struct * files)
 914 {
 915         long j = -1;
 916         struct fdtable *fdt;
 917
 918         spin_lock(&files->file_lock);
 919         for (;;) {
 920                 unsigned long set, i;
 921
 922                 j++;
 923                 i = j * __NFDBITS;
 924                 fdt = files_fdtable(files);
 925                 if (i >= fdt->max_fds)
 926                         break;
 927                 set = fdt->close_on_exec->fds_bits[j];
 928                 if (!set)
 929                         continue;
 930                 fdt->close_on_exec->fds_bits[j] = 0;
 931                 spin_unlock(&files->file_lock);
 932                 for ( ; set ; i++,set >>= 1) {
 933                         if (set & 1) {
 934                                 sys_close(i);
 935                         }
 936                 }
 937                 spin_lock(&files->file_lock);
 938
 939         }
 940         spin_unlock(&files->file_lock);
 941 }
 942
 943 char *get_task_comm(char *buf, struct task_struct *tsk)
 944 {
 945         /* buf must be at least sizeof(tsk->comm) in size */
 946         task_lock(tsk);
 947         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 948         task_unlock(tsk);
 949         return buf;
 950 }
 951
 952 void set_task_comm(struct task_struct *tsk, char *buf)
 953 {
 954         task_lock(tsk);
 955         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 956         task_unlock(tsk);
 957 }
 958
 959 int flush_old_exec(struct linux_binprm * bprm)
 960 {
 961         char * name;
 962         int i, ch, retval;
 963         char tcomm[sizeof(current->comm)];
 964
 965         /*
 966          * Make sure we have a private signal table and that
 967          * we are unassociated from the previous thread group.
 968          */
 969         retval = de_thread(current);
 970         if (retval)
 971                 goto out;
 972
 973         set_mm_exe_file(bprm->mm, bprm->file);
 974
 975         /*
 976          * Release all of the old mmap stuff
 977          */
 978         retval = exec_mmap(bprm->mm);
 979         if (retval)
 980                 goto out;
 981
 982         bprm->mm = NULL;                /* We're using it now */
 983
 984         /* This is the point of no return */
 985         current->sas_ss_sp = current->sas_ss_size = 0;
 986
 987         if (current->euid == current->uid && current->egid == current->gid)
 988                 set_dumpable(current->mm, 1);
 989         else
 990                 set_dumpable(current->mm, suid_dumpable);
 991
 992         name = bprm->filename;
 993
 994         /* Copies the binary name from after last slash */
 995         for (i=0; (ch = *(name++)) != '\0';) {
 996                 if (ch == '/')
 997                         i = 0; /* overwrite what we wrote */
 998                 else
 999                         if (i < (sizeof(tcomm) - 1))
1000                                 tcomm[i++] = ch;
1001         }
1002         tcomm[i] = '\0';
1003         set_task_comm(current, tcomm);
1004
1005         current->flags &= ~PF_RANDOMIZE;
1006         flush_thread();
1007
1008         /* Set the new mm task size. We have to do that late because it may
1009          * depend on TIF_32BIT which is only updated in flush_thread() on
1010          * some architectures like powerpc
1011          */
1012         current->mm->task_size = TASK_SIZE;
1013
1014         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1015                 suid_keys(current);
1016                 set_dumpable(current->mm, suid_dumpable);
1017                 current->pdeath_signal = 0;
1018         } else if (file_permission(bprm->file, MAY_READ) ||
1019                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1020                 suid_keys(current);
1021                 set_dumpable(current->mm, suid_dumpable);
1022         }
1023
1024         /* An exec changes our domain. We are no longer part of the thread
1025            group */
1026
1027         current->self_exec_id++;
1028
1029         flush_signal_handlers(current, 0);
1030         flush_old_files(current->files);
1031
1032         return 0;
1033
1034 out:
1035         return retval;
1036 }
1037
1038 EXPORT_SYMBOL(flush_old_exec);
1039
1040 /*
1041  * Fill the binprm structure from the inode.
1042  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1043  */
1044 int prepare_binprm(struct linux_binprm *bprm)
1045 {
1046         int mode;
1047         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1048         int retval;
1049
1050         mode = inode->i_mode;
1051         if (bprm->file->f_op == NULL)
1052                 return -EACCES;
1053
1054         bprm->e_uid = current->euid;
1055         bprm->e_gid = current->egid;
1056
1057         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1058                 /* Set-uid? */
1059                 if (mode & S_ISUID) {
1060                         current->personality &= ~PER_CLEAR_ON_SETID;
1061                         bprm->e_uid = inode->i_uid;
1062                 }
1063
1064                 /* Set-gid? */
1065                 /*
1066                  * If setgid is set but no group execute bit then this
1067                  * is a candidate for mandatory locking, not a setgid
1068                  * executable.
1069                  */
1070                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1071                         current->personality &= ~PER_CLEAR_ON_SETID;
1072                         bprm->e_gid = inode->i_gid;
1073                 }
1074         }
1075
1076         /* fill in binprm security blob */
1077         retval = security_bprm_set(bprm);
1078         if (retval)
1079                 return retval;
1080
1081         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1082         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1083 }
1084
1085 EXPORT_SYMBOL(prepare_binprm);
1086
1087 static int unsafe_exec(struct task_struct *p)
1088 {
1089         int unsafe = tracehook_unsafe_exec(p);
1090
1091         if (atomic_read(&p->fs->count) > 1 ||
1092             atomic_read(&p->files->count) > 1 ||
1093             atomic_read(&p->sighand->count) > 1)
1094                 unsafe |= LSM_UNSAFE_SHARE;
1095
1096         return unsafe;
1097 }
1098
1099 void compute_creds(struct linux_binprm *bprm)
1100 {
1101         int unsafe;
1102
1103         if (bprm->e_uid != current->uid) {
1104                 suid_keys(current);
1105                 current->pdeath_signal = 0;
1106         }
1107         exec_keys(current);
1108
1109         task_lock(current);
1110         unsafe = unsafe_exec(current);
1111         security_bprm_apply_creds(bprm, unsafe);
1112         task_unlock(current);
1113         security_bprm_post_apply_creds(bprm);
1114 }
1115 EXPORT_SYMBOL(compute_creds);
1116
1117 /*
1118  * Arguments are '\0' separated strings found at the location bprm->p
1119  * points to; chop off the first by relocating brpm->p to right after
1120  * the first '\0' encountered.
1121  */
1122 int remove_arg_zero(struct linux_binprm *bprm)
1123 {
1124         int ret = 0;
1125         unsigned long offset;
1126         char *kaddr;
1127         struct page *page;
1128
1129         if (!bprm->argc)
1130                 return 0;
1131
1132         do {
1133                 offset = bprm->p & ~PAGE_MASK;
1134                 page = get_arg_page(bprm, bprm->p, 0);
1135                 if (!page) {
1136                         ret = -EFAULT;
1137                         goto out;
1138                 }
1139                 kaddr = kmap_atomic(page, KM_USER0);
1140
1141                 for (; offset < PAGE_SIZE && kaddr[offset];
1142                                 offset++, bprm->p++)
1143                         ;
1144
1145                 kunmap_atomic(kaddr, KM_USER0);
1146                 put_arg_page(page);
1147
1148                 if (offset == PAGE_SIZE)
1149                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1150         } while (offset == PAGE_SIZE);
1151
1152         bprm->p++;
1153         bprm->argc--;
1154         ret = 0;
1155
1156 out:
1157         return ret;
1158 }
1159 EXPORT_SYMBOL(remove_arg_zero);
1160
1161 /*
1162  * cycle the list of binary formats handler, until one recognizes the image
1163  */
1164 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1165 {
1166         int try,retval;
1167         struct linux_binfmt *fmt;
1168 #ifdef __alpha__
1169         /* handle /sbin/loader.. */
1170         {
1171             struct exec * eh = (struct exec *) bprm->buf;
1172
1173             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1174                 (eh->fh.f_flags & 0x3000) == 0x3000)
1175             {
1176                 struct file * file;
1177                 unsigned long loader;
1178
1179                 allow_write_access(bprm->file);
1180                 fput(bprm->file);
1181                 bprm->file = NULL;
1182
1183                 loader = bprm->vma->vm_end - sizeof(void *);
1184
1185                 file = open_exec("/sbin/loader");
1186                 retval = PTR_ERR(file);
1187                 if (IS_ERR(file))
1188                         return retval;
1189
1190                 /* Remember if the application is TASO.  */
1191                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1192
1193                 bprm->file = file;
1194                 bprm->loader = loader;
1195                 retval = prepare_binprm(bprm);
1196                 if (retval<0)
1197                         return retval;
1198                 /* should call search_binary_handler recursively here,
1199                    but it does not matter */
1200             }
1201         }
1202 #endif
1203         retval = security_bprm_check(bprm);
1204         if (retval)
1205                 return retval;
1206
1207         /* kernel module loader fixup */
1208         /* so we don't try to load run modprobe in kernel space. */
1209         set_fs(USER_DS);
1210
1211         retval = audit_bprm(bprm);
1212         if (retval)
1213                 return retval;
1214
1215         retval = -ENOENT;
1216         for (try=0; try<2; try++) {
1217                 read_lock(&binfmt_lock);
1218                 list_for_each_entry(fmt, &formats, lh) {
1219                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1220                         if (!fn)
1221                                 continue;
1222                         if (!try_module_get(fmt->module))
1223                                 continue;
1224                         read_unlock(&binfmt_lock);
1225                         retval = fn(bprm, regs);
1226                         if (retval >= 0) {
1227                                 tracehook_report_exec(fmt, bprm, regs);
1228                                 put_binfmt(fmt);
1229                                 allow_write_access(bprm->file);
1230                                 if (bprm->file)
1231                                         fput(bprm->file);
1232                                 bprm->file = NULL;
1233                                 current->did_exec = 1;
1234                                 proc_exec_connector(current);
1235                                 return retval;
1236                         }
1237                         read_lock(&binfmt_lock);
1238                         put_binfmt(fmt);
1239                         if (retval != -ENOEXEC || bprm->mm == NULL)
1240                                 break;
1241                         if (!bprm->file) {
1242                                 read_unlock(&binfmt_lock);
1243                                 return retval;
1244                         }
1245                 }
1246                 read_unlock(&binfmt_lock);
1247                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1248                         break;
1249 #ifdef CONFIG_KMOD
1250                 }else{
1251 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1252                         if (printable(bprm->buf[0]) &&
1253                             printable(bprm->buf[1]) &&
1254                             printable(bprm->buf[2]) &&
1255                             printable(bprm->buf[3]))
1256                                 break; /* -ENOEXEC */
1257                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1258 #endif
1259                 }
1260         }
1261         return retval;
1262 }
1263
1264 EXPORT_SYMBOL(search_binary_handler);
1265
1266 void free_bprm(struct linux_binprm *bprm)
1267 {
1268         free_arg_pages(bprm);
1269         kfree(bprm);
1270 }
1271
1272 /*
1273  * sys_execve() executes a new program.
1274  */
1275 int do_execve(char * filename,
1276         char __user *__user *argv,
1277         char __user *__user *envp,
1278         struct pt_regs * regs)
1279 {
1280         struct linux_binprm *bprm;
1281         struct file *file;
1282         struct files_struct *displaced;
1283         int retval;
1284
1285         retval = unshare_files(&displaced);
1286         if (retval)
1287                 goto out_ret;
1288
1289         retval = -ENOMEM;
1290         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1291         if (!bprm)
1292                 goto out_files;
1293
1294         file = open_exec(filename);
1295         retval = PTR_ERR(file);
1296         if (IS_ERR(file))
1297                 goto out_kfree;
1298
1299         sched_exec();
1300
1301         bprm->file = file;
1302         bprm->filename = filename;
1303         bprm->interp = filename;
1304
1305         retval = bprm_mm_init(bprm);
1306         if (retval)
1307                 goto out_file;
1308
1309         bprm->argc = count(argv, MAX_ARG_STRINGS);
1310         if ((retval = bprm->argc) < 0)
1311                 goto out_mm;
1312
1313         bprm->envc = count(envp, MAX_ARG_STRINGS);
1314         if ((retval = bprm->envc) < 0)
1315                 goto out_mm;
1316
1317         retval = security_bprm_alloc(bprm);
1318         if (retval)
1319                 goto out;
1320
1321         retval = prepare_binprm(bprm);
1322         if (retval < 0)
1323                 goto out;
1324
1325         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1326         if (retval < 0)
1327                 goto out;
1328
1329         bprm->exec = bprm->p;
1330         retval = copy_strings(bprm->envc, envp, bprm);
1331         if (retval < 0)
1332                 goto out;
1333
1334         retval = copy_strings(bprm->argc, argv, bprm);
1335         if (retval < 0)
1336                 goto out;
1337
1338         current->flags &= ~PF_KTHREAD;
1339         retval = search_binary_handler(bprm,regs);
1340         if (retval >= 0) {
1341                 /* execve success */
1342                 security_bprm_free(bprm);
1343                 acct_update_integrals(current);
1344                 free_bprm(bprm);
1345                 if (displaced)
1346                         put_files_struct(displaced);
1347                 return retval;
1348         }
1349
1350 out:
1351         if (bprm->security)
1352                 security_bprm_free(bprm);
1353
1354 out_mm:
1355         if (bprm->mm)
1356                 mmput (bprm->mm);
1357
1358 out_file:
1359         if (bprm->file) {
1360                 allow_write_access(bprm->file);
1361                 fput(bprm->file);
1362         }
1363 out_kfree:
1364         free_bprm(bprm);
1365
1366 out_files:
1367         if (displaced)
1368                 reset_files_struct(displaced);
1369 out_ret:
1370         return retval;
1371 }
1372
1373 int set_binfmt(struct linux_binfmt *new)
1374 {
1375         struct linux_binfmt *old = current->binfmt;
1376
1377         if (new) {
1378                 if (!try_module_get(new->module))
1379                         return -1;
1380         }
1381         current->binfmt = new;
1382         if (old)
1383                 module_put(old->module);
1384         return 0;
1385 }
1386
1387 EXPORT_SYMBOL(set_binfmt);
1388
1389 /* format_corename will inspect the pattern parameter, and output a
1390  * name into corename, which must have space for at least
1391  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1392  */
1393 static int format_corename(char *corename, int nr_threads, long signr)
1394 {
1395         const char *pat_ptr = core_pattern;
1396         int ispipe = (*pat_ptr == '|');
1397         char *out_ptr = corename;
1398         char *const out_end = corename + CORENAME_MAX_SIZE;
1399         int rc;
1400         int pid_in_pattern = 0;
1401
1402         /* Repeat as long as we have more pattern to process and more output
1403            space */
1404         while (*pat_ptr) {
1405                 if (*pat_ptr != '%') {
1406                         if (out_ptr == out_end)
1407                                 goto out;
1408                         *out_ptr++ = *pat_ptr++;
1409                 } else {
1410                         switch (*++pat_ptr) {
1411                         case 0:
1412                                 goto out;
1413                         /* Double percent, output one percent */
1414                         case '%':
1415                                 if (out_ptr == out_end)
1416                                         goto out;
1417                                 *out_ptr++ = '%';
1418                                 break;
1419                         /* pid */
1420                         case 'p':
1421                                 pid_in_pattern = 1;
1422                                 rc = snprintf(out_ptr, out_end - out_ptr,
1423                                               "%d", task_tgid_vnr(current));
1424                                 if (rc > out_end - out_ptr)
1425                                         goto out;
1426                                 out_ptr += rc;
1427                                 break;
1428                         /* uid */
1429                         case 'u':
1430                                 rc = snprintf(out_ptr, out_end - out_ptr,
1431                                               "%d", current->uid);
1432                                 if (rc > out_end - out_ptr)
1433                                         goto out;
1434                                 out_ptr += rc;
1435                                 break;
1436                         /* gid */
1437                         case 'g':
1438                                 rc = snprintf(out_ptr, out_end - out_ptr,
1439                                               "%d", current->gid);
1440                                 if (rc > out_end - out_ptr)
1441                                         goto out;
1442                                 out_ptr += rc;
1443                                 break;
1444                         /* signal that caused the coredump */
1445                         case 's':
1446                                 rc = snprintf(out_ptr, out_end - out_ptr,
1447                                               "%ld", signr);
1448                                 if (rc > out_end - out_ptr)
1449                                         goto out;
1450                                 out_ptr += rc;
1451                                 break;
1452                         /* UNIX time of coredump */
1453                         case 't': {
1454                                 struct timeval tv;
1455                                 do_gettimeofday(&tv);
1456                                 rc = snprintf(out_ptr, out_end - out_ptr,
1457                                               "%lu", tv.tv_sec);
1458                                 if (rc > out_end - out_ptr)
1459                                         goto out;
1460                                 out_ptr += rc;
1461                                 break;
1462                         }
1463                         /* hostname */
1464                         case 'h':
1465                                 down_read(&uts_sem);
1466                                 rc = snprintf(out_ptr, out_end - out_ptr,
1467                                               "%s", utsname()->nodename);
1468                                 up_read(&uts_sem);
1469                                 if (rc > out_end - out_ptr)
1470                                         goto out;
1471                                 out_ptr += rc;
1472                                 break;
1473                         /* executable */
1474                         case 'e':
1475                                 rc = snprintf(out_ptr, out_end - out_ptr,
1476                                               "%s", current->comm);
1477                                 if (rc > out_end - out_ptr)
1478                                         goto out;
1479                                 out_ptr += rc;
1480                                 break;
1481                         /* core limit size */
1482                         case 'c':
1483                                 rc = snprintf(out_ptr, out_end - out_ptr,
1484                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1485                                 if (rc > out_end - out_ptr)
1486                                         goto out;
1487                                 out_ptr += rc;
1488                                 break;
1489                         default:
1490                                 break;
1491                         }
1492                         ++pat_ptr;
1493                 }
1494         }
1495         /* Backward compatibility with core_uses_pid:
1496          *
1497          * If core_pattern does not include a %p (as is the default)
1498          * and core_uses_pid is set, then .%pid will be appended to
1499          * the filename. Do not do this for piped commands. */
1500         if (!ispipe && !pid_in_pattern
1501             && (core_uses_pid || nr_threads)) {
1502                 rc = snprintf(out_ptr, out_end - out_ptr,
1503                               ".%d", task_tgid_vnr(current));
1504                 if (rc > out_end - out_ptr)
1505                         goto out;
1506                 out_ptr += rc;
1507         }
1508 out:
1509         *out_ptr = 0;
1510         return ispipe;
1511 }
1512
1513 static int zap_process(struct task_struct *start)
1514 {
1515         struct task_struct *t;
1516         int nr = 0;
1517
1518         start->signal->flags = SIGNAL_GROUP_EXIT;
1519         start->signal->group_stop_count = 0;
1520
1521         t = start;
1522         do {
1523                 if (t != current && t->mm) {
1524                         sigaddset(&t->pending.signal, SIGKILL);
1525                         signal_wake_up(t, 1);
1526                         nr++;
1527                 }
1528         } while_each_thread(start, t);
1529
1530         return nr;
1531 }
1532
1533 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1534                                 struct core_state *core_state, int exit_code)
1535 {
1536         struct task_struct *g, *p;
1537         unsigned long flags;
1538         int nr = -EAGAIN;
1539
1540         spin_lock_irq(&tsk->sighand->siglock);
1541         if (!signal_group_exit(tsk->signal)) {
1542                 mm->core_state = core_state;
1543                 tsk->signal->group_exit_code = exit_code;
1544                 nr = zap_process(tsk);
1545         }
1546         spin_unlock_irq(&tsk->sighand->siglock);
1547         if (unlikely(nr < 0))
1548                 return nr;
1549
1550         if (atomic_read(&mm->mm_users) == nr + 1)
1551                 goto done;
1552         /*
1553          * We should find and kill all tasks which use this mm, and we should
1554          * count them correctly into ->nr_threads. We don't take tasklist
1555          * lock, but this is safe wrt:
1556          *
1557          * fork:
1558          *      None of sub-threads can fork after zap_process(leader). All
1559          *      processes which were created before this point should be
1560          *      visible to zap_threads() because copy_process() adds the new
1561          *      process to the tail of init_task.tasks list, and lock/unlock
1562          *      of ->siglock provides a memory barrier.
1563          *
1564          * do_exit:
1565          *      The caller holds mm->mmap_sem. This means that the task which
1566          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1567          *      its ->mm.
1568          *
1569          * de_thread:
1570          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1571          *      we must see either old or new leader, this does not matter.
1572          *      However, it can change p->sighand, so lock_task_sighand(p)
1573          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1574          *      it can't fail.
1575          *
1576          *      Note also that "g" can be the old leader with ->mm == NULL
1577          *      and already unhashed and thus removed from ->thread_group.
1578          *      This is OK, __unhash_process()->list_del_rcu() does not
1579          *      clear the ->next pointer, we will find the new leader via
1580          *      next_thread().
1581          */
1582         rcu_read_lock();
1583         for_each_process(g) {
1584                 if (g == tsk->group_leader)
1585                         continue;
1586                 if (g->flags & PF_KTHREAD)
1587                         continue;
1588                 p = g;
1589                 do {
1590                         if (p->mm) {
1591                                 if (unlikely(p->mm == mm)) {
1592                                         lock_task_sighand(p, &flags);
1593                                         nr += zap_process(p);
1594                                         unlock_task_sighand(p, &flags);
1595                                 }
1596                                 break;
1597                         }
1598                 } while_each_thread(g, p);
1599         }
1600         rcu_read_unlock();
1601 done:
1602         atomic_set(&core_state->nr_threads, nr);
1603         return nr;
1604 }
1605
1606 static int coredump_wait(int exit_code, struct core_state *core_state)
1607 {
1608         struct task_struct *tsk = current;
1609         struct mm_struct *mm = tsk->mm;
1610         struct completion *vfork_done;
1611         int core_waiters;
1612
1613         init_completion(&core_state->startup);
1614         core_state->dumper.task = tsk;
1615         core_state->dumper.next = NULL;
1616         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1617         up_write(&mm->mmap_sem);
1618
1619         if (unlikely(core_waiters < 0))
1620                 goto fail;
1621
1622         /*
1623          * Make sure nobody is waiting for us to release the VM,
1624          * otherwise we can deadlock when we wait on each other
1625          */
1626         vfork_done = tsk->vfork_done;
1627         if (vfork_done) {
1628                 tsk->vfork_done = NULL;
1629                 complete(vfork_done);
1630         }
1631
1632         if (core_waiters)
1633                 wait_for_completion(&core_state->startup);
1634 fail:
1635         return core_waiters;
1636 }
1637
1638 static void coredump_finish(struct mm_struct *mm)
1639 {
1640         struct core_thread *curr, *next;
1641         struct task_struct *task;
1642
1643         next = mm->core_state->dumper.next;
1644         while ((curr = next) != NULL) {
1645                 next = curr->next;
1646                 task = curr->task;
1647                 /*
1648                  * see exit_mm(), curr->task must not see
1649                  * ->task == NULL before we read ->next.
1650                  */
1651                 smp_mb();
1652                 curr->task = NULL;
1653                 wake_up_process(task);
1654         }
1655
1656         mm->core_state = NULL;
1657 }
1658
1659 /*
1660  * set_dumpable converts traditional three-value dumpable to two flags and
1661  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1662  * these bits are not changed atomically.  So get_dumpable can observe the
1663  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1664  * return either old dumpable or new one by paying attention to the order of
1665  * modifying the bits.
1666  *
1667  * dumpable |   mm->flags (binary)
1668  * old  new | initial interim  final
1669  * ---------+-----------------------
1670  *  0    1  |   00      01      01
1671  *  0    2  |   00      10(*)   11
1672  *  1    0  |   01      00      00
1673  *  1    2  |   01      11      11
1674  *  2    0  |   11      10(*)   00
1675  *  2    1  |   11      11      01
1676  *
1677  * (*) get_dumpable regards interim value of 10 as 11.
1678  */
1679 void set_dumpable(struct mm_struct *mm, int value)
1680 {
1681         switch (value) {
1682         case 0:
1683                 clear_bit(MMF_DUMPABLE, &mm->flags);
1684                 smp_wmb();
1685                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1686                 break;
1687         case 1:
1688                 set_bit(MMF_DUMPABLE, &mm->flags);
1689                 smp_wmb();
1690                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1691                 break;
1692         case 2:
1693                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1694                 smp_wmb();
1695                 set_bit(MMF_DUMPABLE, &mm->flags);
1696                 break;
1697         }
1698 }
1699
1700 int get_dumpable(struct mm_struct *mm)
1701 {
1702         int ret;
1703
1704         ret = mm->flags & 0x3;
1705         return (ret >= 2) ? 2 : ret;
1706 }
1707
1708 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1709 {
1710         struct core_state core_state;
1711         char corename[CORENAME_MAX_SIZE + 1];
1712         struct mm_struct *mm = current->mm;
1713         struct linux_binfmt * binfmt;
1714         struct inode * inode;
1715         struct file * file;
1716         int retval = 0;
1717         int fsuid = current->fsuid;
1718         int flag = 0;
1719         int ispipe = 0;
1720         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1721         char **helper_argv = NULL;
1722         int helper_argc = 0;
1723         char *delimit;
1724
1725         audit_core_dumps(signr);
1726
1727         binfmt = current->binfmt;
1728         if (!binfmt || !binfmt->core_dump)
1729                 goto fail;
1730         down_write(&mm->mmap_sem);
1731         /*
1732          * If another thread got here first, or we are not dumpable, bail out.
1733          */
1734         if (mm->core_state || !get_dumpable(mm)) {
1735                 up_write(&mm->mmap_sem);
1736                 goto fail;
1737         }
1738
1739         /*
1740          *      We cannot trust fsuid as being the "true" uid of the
1741          *      process nor do we know its entire history. We only know it
1742          *      was tainted so we dump it as root in mode 2.
1743          */
1744         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1745                 flag = O_EXCL;          /* Stop rewrite attacks */
1746                 current->fsuid = 0;     /* Dump root private */
1747         }
1748
1749         retval = coredump_wait(exit_code, &core_state);
1750         if (retval < 0)
1751                 goto fail;
1752
1753         /*
1754          * Clear any false indication of pending signals that might
1755          * be seen by the filesystem code called to write the core file.
1756          */
1757         clear_thread_flag(TIF_SIGPENDING);
1758
1759         /*
1760          * lock_kernel() because format_corename() is controlled by sysctl, which
1761          * uses lock_kernel()
1762          */
1763         lock_kernel();
1764         ispipe = format_corename(corename, retval, signr);
1765         unlock_kernel();
1766         /*
1767          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1768          * to a pipe.  Since we're not writing directly to the filesystem
1769          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1770          * created unless the pipe reader choses to write out the core file
1771          * at which point file size limits and permissions will be imposed
1772          * as it does with any other process
1773          */
1774         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1775                 goto fail_unlock;
1776
1777         if (ispipe) {
1778                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1779                 /* Terminate the string before the first option */
1780                 delimit = strchr(corename, ' ');
1781                 if (delimit)
1782                         *delimit = '\0';
1783                 delimit = strrchr(helper_argv[0], '/');
1784                 if (delimit)
1785                         delimit++;
1786                 else
1787                         delimit = helper_argv[0];
1788                 if (!strcmp(delimit, current->comm)) {
1789                         printk(KERN_NOTICE "Recursive core dump detected, "
1790                                         "aborting\n");
1791                         goto fail_unlock;
1792                 }
1793
1794                 core_limit = RLIM_INFINITY;
1795
1796                 /* SIGPIPE can happen, but it's just never processed */
1797                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1798                                 &file)) {
1799                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1800                                corename);
1801                         goto fail_unlock;
1802                 }
1803         } else
1804                 file = filp_open(corename,
1805                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1806                                  0600);
1807         if (IS_ERR(file))
1808                 goto fail_unlock;
1809         inode = file->f_path.dentry->d_inode;
1810         if (inode->i_nlink > 1)
1811                 goto close_fail;        /* multiple links - don't dump */
1812         if (!ispipe && d_unhashed(file->f_path.dentry))
1813                 goto close_fail;
1814
1815         /* AK: actually i see no reason to not allow this for named pipes etc.,
1816            but keep the previous behaviour for now. */
1817         if (!ispipe && !S_ISREG(inode->i_mode))
1818                 goto close_fail;
1819         /*
1820          * Dont allow local users get cute and trick others to coredump
1821          * into their pre-created files:
1822          */
1823         if (inode->i_uid != current->fsuid)
1824                 goto close_fail;
1825         if (!file->f_op)
1826                 goto close_fail;
1827         if (!file->f_op->write)
1828                 goto close_fail;
1829         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1830                 goto close_fail;
1831
1832         retval = binfmt->core_dump(signr, regs, file, core_limit);
1833
1834         if (retval)
1835                 current->signal->group_exit_code |= 0x80;
1836 close_fail:
1837         filp_close(file, NULL);
1838 fail_unlock:
1839         if (helper_argv)
1840                 argv_free(helper_argv);
1841
1842         current->fsuid = fsuid;
1843         coredump_finish(mm);
1844 fail:
1845         return retval;
1846 }