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   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/slab.h>
  26 #include <linux/file.h>
  27 #include <linux/mman.h>
  28 #include <linux/a.out.h>
  29 #include <linux/stat.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/smp_lock.h>
  32 #include <linux/string.h>
  33 #include <linux/init.h>
  34 #include <linux/pagemap.h>
  35 #include <linux/highmem.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/key.h>
  38 #include <linux/personality.h>
  39 #include <linux/binfmts.h>
  40 #include <linux/swap.h>
  41 #include <linux/utsname.h>
  42 #include <linux/pid_namespace.h>
  43 #include <linux/module.h>
  44 #include <linux/namei.h>
  45 #include <linux/proc_fs.h>
  46 #include <linux/ptrace.h>
  47 #include <linux/mount.h>
  48 #include <linux/security.h>
  49 #include <linux/syscalls.h>
  50 #include <linux/rmap.h>
  51 #include <linux/tsacct_kern.h>
  52 #include <linux/cn_proc.h>
  53 #include <linux/audit.h>
  54
  55 #include <asm/uaccess.h>
  56 #include <asm/mmu_context.h>
  57 #include <asm/tlb.h>
  58
  59 #ifdef CONFIG_KMOD
  60 #include <linux/kmod.h>
  61 #endif
  62
  63 int core_uses_pid;
  64 char core_pattern[CORENAME_MAX_SIZE] = "core";
  65 int suid_dumpable = 0;
  66
  67 EXPORT_SYMBOL(suid_dumpable);
  68 /* The maximal length of core_pattern is also specified in sysctl.c */
  69
  70 static LIST_HEAD(formats);
  71 static DEFINE_RWLOCK(binfmt_lock);
  72
  73 int register_binfmt(struct linux_binfmt * fmt)
  74 {
  75         if (!fmt)
  76                 return -EINVAL;
  77         write_lock(&binfmt_lock);
  78         list_add(&fmt->lh, &formats);
  79         write_unlock(&binfmt_lock);
  80         return 0;
  81 }
  82
  83 EXPORT_SYMBOL(register_binfmt);
  84
  85 void unregister_binfmt(struct linux_binfmt * fmt)
  86 {
  87         write_lock(&binfmt_lock);
  88         list_del(&fmt->lh);
  89         write_unlock(&binfmt_lock);
  90 }
  91
  92 EXPORT_SYMBOL(unregister_binfmt);
  93
  94 static inline void put_binfmt(struct linux_binfmt * fmt)
  95 {
  96         module_put(fmt->module);
  97 }
  98
  99 /*
 100  * Note that a shared library must be both readable and executable due to
 101  * security reasons.
 102  *
 103  * Also note that we take the address to load from from the file itself.
 104  */
 105 asmlinkage long sys_uselib(const char __user * library)
 106 {
 107         struct file * file;
 108         struct nameidata nd;
 109         int error;
 110
 111         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 112         if (error)
 113                 goto out;
 114
 115         error = -EINVAL;
 116         if (!S_ISREG(nd.dentry->d_inode->i_mode))
 117                 goto exit;
 118
 119         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
 120         if (error)
 121                 goto exit;
 122
 123         file = nameidata_to_filp(&nd, O_RDONLY);
 124         error = PTR_ERR(file);
 125         if (IS_ERR(file))
 126                 goto out;
 127
 128         error = -ENOEXEC;
 129         if(file->f_op) {
 130                 struct linux_binfmt * fmt;
 131
 132                 read_lock(&binfmt_lock);
 133                 list_for_each_entry(fmt, &formats, lh) {
 134                         if (!fmt->load_shlib)
 135                                 continue;
 136                         if (!try_module_get(fmt->module))
 137                                 continue;
 138                         read_unlock(&binfmt_lock);
 139                         error = fmt->load_shlib(file);
 140                         read_lock(&binfmt_lock);
 141                         put_binfmt(fmt);
 142                         if (error != -ENOEXEC)
 143                                 break;
 144                 }
 145                 read_unlock(&binfmt_lock);
 146         }
 147         fput(file);
 148 out:
 149         return error;
 150 exit:
 151         release_open_intent(&nd);
 152         path_release(&nd);
 153         goto out;
 154 }
 155
 156 #ifdef CONFIG_MMU
 157
 158 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 159                 int write)
 160 {
 161         struct page *page;
 162         int ret;
 163
 164 #ifdef CONFIG_STACK_GROWSUP
 165         if (write) {
 166                 ret = expand_stack_downwards(bprm->vma, pos);
 167                 if (ret < 0)
 168                         return NULL;
 169         }
 170 #endif
 171         ret = get_user_pages(current, bprm->mm, pos,
 172                         1, write, 1, &page, NULL);
 173         if (ret <= 0)
 174                 return NULL;
 175
 176         if (write) {
 177                 struct rlimit *rlim = current->signal->rlim;
 178                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 179
 180                 /*
 181                  * Limit to 1/4-th the stack size for the argv+env strings.
 182                  * This ensures that:
 183                  *  - the remaining binfmt code will not run out of stack space,
 184                  *  - the program will have a reasonable amount of stack left
 185                  *    to work from.
 186                  */
 187                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 188                         put_page(page);
 189                         return NULL;
 190                 }
 191         }
 192
 193         return page;
 194 }
 195
 196 static void put_arg_page(struct page *page)
 197 {
 198         put_page(page);
 199 }
 200
 201 static void free_arg_page(struct linux_binprm *bprm, int i)
 202 {
 203 }
 204
 205 static void free_arg_pages(struct linux_binprm *bprm)
 206 {
 207 }
 208
 209 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 210                 struct page *page)
 211 {
 212         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 213 }
 214
 215 static int __bprm_mm_init(struct linux_binprm *bprm)
 216 {
 217         int err = -ENOMEM;
 218         struct vm_area_struct *vma = NULL;
 219         struct mm_struct *mm = bprm->mm;
 220
 221         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 222         if (!vma)
 223                 goto err;
 224
 225         down_write(&mm->mmap_sem);
 226         vma->vm_mm = mm;
 227
 228         /*
 229          * Place the stack at the largest stack address the architecture
 230          * supports. Later, we'll move this to an appropriate place. We don't
 231          * use STACK_TOP because that can depend on attributes which aren't
 232          * configured yet.
 233          */
 234         vma->vm_end = STACK_TOP_MAX;
 235         vma->vm_start = vma->vm_end - PAGE_SIZE;
 236
 237         vma->vm_flags = VM_STACK_FLAGS;
 238         vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
 239         err = insert_vm_struct(mm, vma);
 240         if (err) {
 241                 up_write(&mm->mmap_sem);
 242                 goto err;
 243         }
 244
 245         mm->stack_vm = mm->total_vm = 1;
 246         up_write(&mm->mmap_sem);
 247
 248         bprm->p = vma->vm_end - sizeof(void *);
 249
 250         return 0;
 251
 252 err:
 253         if (vma) {
 254                 bprm->vma = NULL;
 255                 kmem_cache_free(vm_area_cachep, vma);
 256         }
 257
 258         return err;
 259 }
 260
 261 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 262 {
 263         return len <= MAX_ARG_STRLEN;
 264 }
 265
 266 #else
 267
 268 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 269                 int write)
 270 {
 271         struct page *page;
 272
 273         page = bprm->page[pos / PAGE_SIZE];
 274         if (!page && write) {
 275                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 276                 if (!page)
 277                         return NULL;
 278                 bprm->page[pos / PAGE_SIZE] = page;
 279         }
 280
 281         return page;
 282 }
 283
 284 static void put_arg_page(struct page *page)
 285 {
 286 }
 287
 288 static void free_arg_page(struct linux_binprm *bprm, int i)
 289 {
 290         if (bprm->page[i]) {
 291                 __free_page(bprm->page[i]);
 292                 bprm->page[i] = NULL;
 293         }
 294 }
 295
 296 static void free_arg_pages(struct linux_binprm *bprm)
 297 {
 298         int i;
 299
 300         for (i = 0; i < MAX_ARG_PAGES; i++)
 301                 free_arg_page(bprm, i);
 302 }
 303
 304 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 305                 struct page *page)
 306 {
 307 }
 308
 309 static int __bprm_mm_init(struct linux_binprm *bprm)
 310 {
 311         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 312         return 0;
 313 }
 314
 315 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 316 {
 317         return len <= bprm->p;
 318 }
 319
 320 #endif /* CONFIG_MMU */
 321
 322 /*
 323  * Create a new mm_struct and populate it with a temporary stack
 324  * vm_area_struct.  We don't have enough context at this point to set the stack
 325  * flags, permissions, and offset, so we use temporary values.  We'll update
 326  * them later in setup_arg_pages().
 327  */
 328 int bprm_mm_init(struct linux_binprm *bprm)
 329 {
 330         int err;
 331         struct mm_struct *mm = NULL;
 332
 333         bprm->mm = mm = mm_alloc();
 334         err = -ENOMEM;
 335         if (!mm)
 336                 goto err;
 337
 338         err = init_new_context(current, mm);
 339         if (err)
 340                 goto err;
 341
 342         err = __bprm_mm_init(bprm);
 343         if (err)
 344                 goto err;
 345
 346         return 0;
 347
 348 err:
 349         if (mm) {
 350                 bprm->mm = NULL;
 351                 mmdrop(mm);
 352         }
 353
 354         return err;
 355 }
 356
 357 /*
 358  * count() counts the number of strings in array ARGV.
 359  */
 360 static int count(char __user * __user * argv, int max)
 361 {
 362         int i = 0;
 363
 364         if (argv != NULL) {
 365                 for (;;) {
 366                         char __user * p;
 367
 368                         if (get_user(p, argv))
 369                                 return -EFAULT;
 370                         if (!p)
 371                                 break;
 372                         argv++;
 373                         if(++i > max)
 374                                 return -E2BIG;
 375                         cond_resched();
 376                 }
 377         }
 378         return i;
 379 }
 380
 381 /*
 382  * 'copy_strings()' copies argument/environment strings from the old
 383  * processes's memory to the new process's stack.  The call to get_user_pages()
 384  * ensures the destination page is created and not swapped out.
 385  */
 386 static int copy_strings(int argc, char __user * __user * argv,
 387                         struct linux_binprm *bprm)
 388 {
 389         struct page *kmapped_page = NULL;
 390         char *kaddr = NULL;
 391         unsigned long kpos = 0;
 392         int ret;
 393
 394         while (argc-- > 0) {
 395                 char __user *str;
 396                 int len;
 397                 unsigned long pos;
 398
 399                 if (get_user(str, argv+argc) ||
 400                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 401                         ret = -EFAULT;
 402                         goto out;
 403                 }
 404
 405                 if (!valid_arg_len(bprm, len)) {
 406                         ret = -E2BIG;
 407                         goto out;
 408                 }
 409
 410                 /* We're going to work our way backwords. */
 411                 pos = bprm->p;
 412                 str += len;
 413                 bprm->p -= len;
 414
 415                 while (len > 0) {
 416                         int offset, bytes_to_copy;
 417
 418                         offset = pos % PAGE_SIZE;
 419                         if (offset == 0)
 420                                 offset = PAGE_SIZE;
 421
 422                         bytes_to_copy = offset;
 423                         if (bytes_to_copy > len)
 424                                 bytes_to_copy = len;
 425
 426                         offset -= bytes_to_copy;
 427                         pos -= bytes_to_copy;
 428                         str -= bytes_to_copy;
 429                         len -= bytes_to_copy;
 430
 431                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 432                                 struct page *page;
 433
 434                                 page = get_arg_page(bprm, pos, 1);
 435                                 if (!page) {
 436                                         ret = -E2BIG;
 437                                         goto out;
 438                                 }
 439
 440                                 if (kmapped_page) {
 441                                         flush_kernel_dcache_page(kmapped_page);
 442                                         kunmap(kmapped_page);
 443                                         put_arg_page(kmapped_page);
 444                                 }
 445                                 kmapped_page = page;
 446                                 kaddr = kmap(kmapped_page);
 447                                 kpos = pos & PAGE_MASK;
 448                                 flush_arg_page(bprm, kpos, kmapped_page);
 449                         }
 450                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 451                                 ret = -EFAULT;
 452                                 goto out;
 453                         }
 454                 }
 455         }
 456         ret = 0;
 457 out:
 458         if (kmapped_page) {
 459                 flush_kernel_dcache_page(kmapped_page);
 460                 kunmap(kmapped_page);
 461                 put_arg_page(kmapped_page);
 462         }
 463         return ret;
 464 }
 465
 466 /*
 467  * Like copy_strings, but get argv and its values from kernel memory.
 468  */
 469 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 470 {
 471         int r;
 472         mm_segment_t oldfs = get_fs();
 473         set_fs(KERNEL_DS);
 474         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 475         set_fs(oldfs);
 476         return r;
 477 }
 478 EXPORT_SYMBOL(copy_strings_kernel);
 479
 480 #ifdef CONFIG_MMU
 481
 482 /*
 483  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 484  * the binfmt code determines where the new stack should reside, we shift it to
 485  * its final location.  The process proceeds as follows:
 486  *
 487  * 1) Use shift to calculate the new vma endpoints.
 488  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 489  *    arguments passed to subsequent functions are consistent.
 490  * 3) Move vma's page tables to the new range.
 491  * 4) Free up any cleared pgd range.
 492  * 5) Shrink the vma to cover only the new range.
 493  */
 494 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 495 {
 496         struct mm_struct *mm = vma->vm_mm;
 497         unsigned long old_start = vma->vm_start;
 498         unsigned long old_end = vma->vm_end;
 499         unsigned long length = old_end - old_start;
 500         unsigned long new_start = old_start - shift;
 501         unsigned long new_end = old_end - shift;
 502         struct mmu_gather *tlb;
 503
 504         BUG_ON(new_start > new_end);
 505
 506         /*
 507          * ensure there are no vmas between where we want to go
 508          * and where we are
 509          */
 510         if (vma != find_vma(mm, new_start))
 511                 return -EFAULT;
 512
 513         /*
 514          * cover the whole range: [new_start, old_end)
 515          */
 516         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 517
 518         /*
 519          * move the page tables downwards, on failure we rely on
 520          * process cleanup to remove whatever mess we made.
 521          */
 522         if (length != move_page_tables(vma, old_start,
 523                                        vma, new_start, length))
 524                 return -ENOMEM;
 525
 526         lru_add_drain();
 527         tlb = tlb_gather_mmu(mm, 0);
 528         if (new_end > old_start) {
 529                 /*
 530                  * when the old and new regions overlap clear from new_end.
 531                  */
 532                 free_pgd_range(&tlb, new_end, old_end, new_end,
 533                         vma->vm_next ? vma->vm_next->vm_start : 0);
 534         } else {
 535                 /*
 536                  * otherwise, clean from old_start; this is done to not touch
 537                  * the address space in [new_end, old_start) some architectures
 538                  * have constraints on va-space that make this illegal (IA64) -
 539                  * for the others its just a little faster.
 540                  */
 541                 free_pgd_range(&tlb, old_start, old_end, new_end,
 542                         vma->vm_next ? vma->vm_next->vm_start : 0);
 543         }
 544         tlb_finish_mmu(tlb, new_end, old_end);
 545
 546         /*
 547          * shrink the vma to just the new range.
 548          */
 549         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 550
 551         return 0;
 552 }
 553
 554 #define EXTRA_STACK_VM_PAGES    20      /* random */
 555
 556 /*
 557  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 558  * the stack is optionally relocated, and some extra space is added.
 559  */
 560 int setup_arg_pages(struct linux_binprm *bprm,
 561                     unsigned long stack_top,
 562                     int executable_stack)
 563 {
 564         unsigned long ret;
 565         unsigned long stack_shift;
 566         struct mm_struct *mm = current->mm;
 567         struct vm_area_struct *vma = bprm->vma;
 568         struct vm_area_struct *prev = NULL;
 569         unsigned long vm_flags;
 570         unsigned long stack_base;
 571
 572 #ifdef CONFIG_STACK_GROWSUP
 573         /* Limit stack size to 1GB */
 574         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 575         if (stack_base > (1 << 30))
 576                 stack_base = 1 << 30;
 577
 578         /* Make sure we didn't let the argument array grow too large. */
 579         if (vma->vm_end - vma->vm_start > stack_base)
 580                 return -ENOMEM;
 581
 582         stack_base = PAGE_ALIGN(stack_top - stack_base);
 583
 584         stack_shift = vma->vm_start - stack_base;
 585         mm->arg_start = bprm->p - stack_shift;
 586         bprm->p = vma->vm_end - stack_shift;
 587 #else
 588         stack_top = arch_align_stack(stack_top);
 589         stack_top = PAGE_ALIGN(stack_top);
 590         stack_shift = vma->vm_end - stack_top;
 591
 592         bprm->p -= stack_shift;
 593         mm->arg_start = bprm->p;
 594 #endif
 595
 596         if (bprm->loader)
 597                 bprm->loader -= stack_shift;
 598         bprm->exec -= stack_shift;
 599
 600         down_write(&mm->mmap_sem);
 601         vm_flags = vma->vm_flags;
 602
 603         /*
 604          * Adjust stack execute permissions; explicitly enable for
 605          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 606          * (arch default) otherwise.
 607          */
 608         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 609                 vm_flags |= VM_EXEC;
 610         else if (executable_stack == EXSTACK_DISABLE_X)
 611                 vm_flags &= ~VM_EXEC;
 612         vm_flags |= mm->def_flags;
 613
 614         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 615                         vm_flags);
 616         if (ret)
 617                 goto out_unlock;
 618         BUG_ON(prev != vma);
 619
 620         /* Move stack pages down in memory. */
 621         if (stack_shift) {
 622                 ret = shift_arg_pages(vma, stack_shift);
 623                 if (ret) {
 624                         up_write(&mm->mmap_sem);
 625                         return ret;
 626                 }
 627         }
 628
 629 #ifdef CONFIG_STACK_GROWSUP
 630         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 631 #else
 632         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 633 #endif
 634         ret = expand_stack(vma, stack_base);
 635         if (ret)
 636                 ret = -EFAULT;
 637
 638 out_unlock:
 639         up_write(&mm->mmap_sem);
 640         return 0;
 641 }
 642 EXPORT_SYMBOL(setup_arg_pages);
 643
 644 #endif /* CONFIG_MMU */
 645
 646 struct file *open_exec(const char *name)
 647 {
 648         struct nameidata nd;
 649         int err;
 650         struct file *file;
 651
 652         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
 653         file = ERR_PTR(err);
 654
 655         if (!err) {
 656                 struct inode *inode = nd.dentry->d_inode;
 657                 file = ERR_PTR(-EACCES);
 658                 if (S_ISREG(inode->i_mode)) {
 659                         int err = vfs_permission(&nd, MAY_EXEC);
 660                         file = ERR_PTR(err);
 661                         if (!err) {
 662                                 file = nameidata_to_filp(&nd, O_RDONLY);
 663                                 if (!IS_ERR(file)) {
 664                                         err = deny_write_access(file);
 665                                         if (err) {
 666                                                 fput(file);
 667                                                 file = ERR_PTR(err);
 668                                         }
 669                                 }
 670 out:
 671                                 return file;
 672                         }
 673                 }
 674                 release_open_intent(&nd);
 675                 path_release(&nd);
 676         }
 677         goto out;
 678 }
 679
 680 EXPORT_SYMBOL(open_exec);
 681
 682 int kernel_read(struct file *file, unsigned long offset,
 683         char *addr, unsigned long count)
 684 {
 685         mm_segment_t old_fs;
 686         loff_t pos = offset;
 687         int result;
 688
 689         old_fs = get_fs();
 690         set_fs(get_ds());
 691         /* The cast to a user pointer is valid due to the set_fs() */
 692         result = vfs_read(file, (void __user *)addr, count, &pos);
 693         set_fs(old_fs);
 694         return result;
 695 }
 696
 697 EXPORT_SYMBOL(kernel_read);
 698
 699 static int exec_mmap(struct mm_struct *mm)
 700 {
 701         struct task_struct *tsk;
 702         struct mm_struct * old_mm, *active_mm;
 703
 704         /* Notify parent that we're no longer interested in the old VM */
 705         tsk = current;
 706         old_mm = current->mm;
 707         mm_release(tsk, old_mm);
 708
 709         if (old_mm) {
 710                 /*
 711                  * Make sure that if there is a core dump in progress
 712                  * for the old mm, we get out and die instead of going
 713                  * through with the exec.  We must hold mmap_sem around
 714                  * checking core_waiters and changing tsk->mm.  The
 715                  * core-inducing thread will increment core_waiters for
 716                  * each thread whose ->mm == old_mm.
 717                  */
 718                 down_read(&old_mm->mmap_sem);
 719                 if (unlikely(old_mm->core_waiters)) {
 720                         up_read(&old_mm->mmap_sem);
 721                         return -EINTR;
 722                 }
 723         }
 724         task_lock(tsk);
 725         active_mm = tsk->active_mm;
 726         tsk->mm = mm;
 727         tsk->active_mm = mm;
 728         activate_mm(active_mm, mm);
 729         task_unlock(tsk);
 730         arch_pick_mmap_layout(mm);
 731         if (old_mm) {
 732                 up_read(&old_mm->mmap_sem);
 733                 BUG_ON(active_mm != old_mm);
 734                 mmput(old_mm);
 735                 return 0;
 736         }
 737         mmdrop(active_mm);
 738         return 0;
 739 }
 740
 741 /*
 742  * This function makes sure the current process has its own signal table,
 743  * so that flush_signal_handlers can later reset the handlers without
 744  * disturbing other processes.  (Other processes might share the signal
 745  * table via the CLONE_SIGHAND option to clone().)
 746  */
 747 static int de_thread(struct task_struct *tsk)
 748 {
 749         struct signal_struct *sig = tsk->signal;
 750         struct sighand_struct *oldsighand = tsk->sighand;
 751         spinlock_t *lock = &oldsighand->siglock;
 752         struct task_struct *leader = NULL;
 753         int count;
 754
 755         /*
 756          * If we don't share sighandlers, then we aren't sharing anything
 757          * and we can just re-use it all.
 758          */
 759         if (atomic_read(&oldsighand->count) <= 1) {
 760                 exit_itimers(sig);
 761                 return 0;
 762         }
 763
 764         if (thread_group_empty(tsk))
 765                 goto no_thread_group;
 766
 767         /*
 768          * Kill all other threads in the thread group.
 769          * We must hold tasklist_lock to call zap_other_threads.
 770          */
 771         read_lock(&tasklist_lock);
 772         spin_lock_irq(lock);
 773         if (sig->flags & SIGNAL_GROUP_EXIT) {
 774                 /*
 775                  * Another group action in progress, just
 776                  * return so that the signal is processed.
 777                  */
 778                 spin_unlock_irq(lock);
 779                 read_unlock(&tasklist_lock);
 780                 return -EAGAIN;
 781         }
 782
 783         /*
 784          * child_reaper ignores SIGKILL, change it now.
 785          * Reparenting needs write_lock on tasklist_lock,
 786          * so it is safe to do it under read_lock.
 787          */
 788         if (unlikely(tsk->group_leader == child_reaper(tsk)))
 789                 tsk->nsproxy->pid_ns->child_reaper = tsk;
 790
 791         zap_other_threads(tsk);
 792         read_unlock(&tasklist_lock);
 793
 794         /*
 795          * Account for the thread group leader hanging around:
 796          */
 797         count = 1;
 798         if (!thread_group_leader(tsk)) {
 799                 count = 2;
 800                 /*
 801                  * The SIGALRM timer survives the exec, but needs to point
 802                  * at us as the new group leader now.  We have a race with
 803                  * a timer firing now getting the old leader, so we need to
 804                  * synchronize with any firing (by calling del_timer_sync)
 805                  * before we can safely let the old group leader die.
 806                  */
 807                 sig->tsk = tsk;
 808                 spin_unlock_irq(lock);
 809                 if (hrtimer_cancel(&sig->real_timer))
 810                         hrtimer_restart(&sig->real_timer);
 811                 spin_lock_irq(lock);
 812         }
 813         while (atomic_read(&sig->count) > count) {
 814                 sig->group_exit_task = tsk;
 815                 sig->notify_count = count;
 816                 __set_current_state(TASK_UNINTERRUPTIBLE);
 817                 spin_unlock_irq(lock);
 818                 schedule();
 819                 spin_lock_irq(lock);
 820         }
 821         sig->group_exit_task = NULL;
 822         sig->notify_count = 0;
 823         spin_unlock_irq(lock);
 824
 825         /*
 826          * At this point all other threads have exited, all we have to
 827          * do is to wait for the thread group leader to become inactive,
 828          * and to assume its PID:
 829          */
 830         if (!thread_group_leader(tsk)) {
 831                 /*
 832                  * Wait for the thread group leader to be a zombie.
 833                  * It should already be zombie at this point, most
 834                  * of the time.
 835                  */
 836                 leader = tsk->group_leader;
 837                 while (leader->exit_state != EXIT_ZOMBIE)
 838                         yield();
 839
 840                 /*
 841                  * The only record we have of the real-time age of a
 842                  * process, regardless of execs it's done, is start_time.
 843                  * All the past CPU time is accumulated in signal_struct
 844                  * from sister threads now dead.  But in this non-leader
 845                  * exec, nothing survives from the original leader thread,
 846                  * whose birth marks the true age of this process now.
 847                  * When we take on its identity by switching to its PID, we
 848                  * also take its birthdate (always earlier than our own).
 849                  */
 850                 tsk->start_time = leader->start_time;
 851
 852                 write_lock_irq(&tasklist_lock);
 853
 854                 BUG_ON(leader->tgid != tsk->tgid);
 855                 BUG_ON(tsk->pid == tsk->tgid);
 856                 /*
 857                  * An exec() starts a new thread group with the
 858                  * TGID of the previous thread group. Rehash the
 859                  * two threads with a switched PID, and release
 860                  * the former thread group leader:
 861                  */
 862
 863                 /* Become a process group leader with the old leader's pid.
 864                  * The old leader becomes a thread of the this thread group.
 865                  * Note: The old leader also uses this pid until release_task
 866                  *       is called.  Odd but simple and correct.
 867                  */
 868                 detach_pid(tsk, PIDTYPE_PID);
 869                 tsk->pid = leader->pid;
 870                 attach_pid(tsk, PIDTYPE_PID,  find_pid(tsk->pid));
 871                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 872                 transfer_pid(leader, tsk, PIDTYPE_SID);
 873                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 874
 875                 tsk->group_leader = tsk;
 876                 leader->group_leader = tsk;
 877
 878                 tsk->exit_signal = SIGCHLD;
 879
 880                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 881                 leader->exit_state = EXIT_DEAD;
 882
 883                 write_unlock_irq(&tasklist_lock);
 884         }
 885
 886         /*
 887          * There may be one thread left which is just exiting,
 888          * but it's safe to stop telling the group to kill themselves.
 889          */
 890         sig->flags = 0;
 891
 892 no_thread_group:
 893         exit_itimers(sig);
 894         if (leader)
 895                 release_task(leader);
 896
 897         if (atomic_read(&oldsighand->count) != 1) {
 898                 struct sighand_struct *newsighand;
 899                 /*
 900                  * This ->sighand is shared with the CLONE_SIGHAND
 901                  * but not CLONE_THREAD task, switch to the new one.
 902                  */
 903                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 904                 if (!newsighand)
 905                         return -ENOMEM;
 906
 907                 atomic_set(&newsighand->count, 1);
 908                 memcpy(newsighand->action, oldsighand->action,
 909                        sizeof(newsighand->action));
 910
 911                 write_lock_irq(&tasklist_lock);
 912                 spin_lock(&oldsighand->siglock);
 913                 rcu_assign_pointer(tsk->sighand, newsighand);
 914                 spin_unlock(&oldsighand->siglock);
 915                 write_unlock_irq(&tasklist_lock);
 916
 917                 __cleanup_sighand(oldsighand);
 918         }
 919
 920         BUG_ON(!thread_group_leader(tsk));
 921         return 0;
 922 }
 923
 924 /*
 925  * These functions flushes out all traces of the currently running executable
 926  * so that a new one can be started
 927  */
 928 static void flush_old_files(struct files_struct * files)
 929 {
 930         long j = -1;
 931         struct fdtable *fdt;
 932
 933         spin_lock(&files->file_lock);
 934         for (;;) {
 935                 unsigned long set, i;
 936
 937                 j++;
 938                 i = j * __NFDBITS;
 939                 fdt = files_fdtable(files);
 940                 if (i >= fdt->max_fds)
 941                         break;
 942                 set = fdt->close_on_exec->fds_bits[j];
 943                 if (!set)
 944                         continue;
 945                 fdt->close_on_exec->fds_bits[j] = 0;
 946                 spin_unlock(&files->file_lock);
 947                 for ( ; set ; i++,set >>= 1) {
 948                         if (set & 1) {
 949                                 sys_close(i);
 950                         }
 951                 }
 952                 spin_lock(&files->file_lock);
 953
 954         }
 955         spin_unlock(&files->file_lock);
 956 }
 957
 958 void get_task_comm(char *buf, struct task_struct *tsk)
 959 {
 960         /* buf must be at least sizeof(tsk->comm) in size */
 961         task_lock(tsk);
 962         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 963         task_unlock(tsk);
 964 }
 965
 966 void set_task_comm(struct task_struct *tsk, char *buf)
 967 {
 968         task_lock(tsk);
 969         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 970         task_unlock(tsk);
 971 }
 972
 973 int flush_old_exec(struct linux_binprm * bprm)
 974 {
 975         char * name;
 976         int i, ch, retval;
 977         struct files_struct *files;
 978         char tcomm[sizeof(current->comm)];
 979
 980         /*
 981          * Make sure we have a private signal table and that
 982          * we are unassociated from the previous thread group.
 983          */
 984         retval = de_thread(current);
 985         if (retval)
 986                 goto out;
 987
 988         /*
 989          * Make sure we have private file handles. Ask the
 990          * fork helper to do the work for us and the exit
 991          * helper to do the cleanup of the old one.
 992          */
 993         files = current->files;         /* refcounted so safe to hold */
 994         retval = unshare_files();
 995         if (retval)
 996                 goto out;
 997         /*
 998          * Release all of the old mmap stuff
 999          */
1000         retval = exec_mmap(bprm->mm);
1001         if (retval)
1002                 goto mmap_failed;
1003
1004         bprm->mm = NULL;                /* We're using it now */
1005
1006         /* This is the point of no return */
1007         put_files_struct(files);
1008
1009         current->sas_ss_sp = current->sas_ss_size = 0;
1010
1011         if (current->euid == current->uid && current->egid == current->gid)
1012                 set_dumpable(current->mm, 1);
1013         else
1014                 set_dumpable(current->mm, suid_dumpable);
1015
1016         name = bprm->filename;
1017
1018         /* Copies the binary name from after last slash */
1019         for (i=0; (ch = *(name++)) != '\0';) {
1020                 if (ch == '/')
1021                         i = 0; /* overwrite what we wrote */
1022                 else
1023                         if (i < (sizeof(tcomm) - 1))
1024                                 tcomm[i++] = ch;
1025         }
1026         tcomm[i] = '\0';
1027         set_task_comm(current, tcomm);
1028
1029         current->flags &= ~PF_RANDOMIZE;
1030         flush_thread();
1031
1032         /* Set the new mm task size. We have to do that late because it may
1033          * depend on TIF_32BIT which is only updated in flush_thread() on
1034          * some architectures like powerpc
1035          */
1036         current->mm->task_size = TASK_SIZE;
1037
1038         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1039                 suid_keys(current);
1040                 set_dumpable(current->mm, suid_dumpable);
1041                 current->pdeath_signal = 0;
1042         } else if (file_permission(bprm->file, MAY_READ) ||
1043                         (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1044                 suid_keys(current);
1045                 set_dumpable(current->mm, suid_dumpable);
1046         }
1047
1048         /* An exec changes our domain. We are no longer part of the thread
1049            group */
1050
1051         current->self_exec_id++;
1052
1053         flush_signal_handlers(current, 0);
1054         flush_old_files(current->files);
1055
1056         return 0;
1057
1058 mmap_failed:
1059         reset_files_struct(current, files);
1060 out:
1061         return retval;
1062 }
1063
1064 EXPORT_SYMBOL(flush_old_exec);
1065
1066 /*
1067  * Fill the binprm structure from the inode.
1068  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1069  */
1070 int prepare_binprm(struct linux_binprm *bprm)
1071 {
1072         int mode;
1073         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1074         int retval;
1075
1076         mode = inode->i_mode;
1077         if (bprm->file->f_op == NULL)
1078                 return -EACCES;
1079
1080         bprm->e_uid = current->euid;
1081         bprm->e_gid = current->egid;
1082
1083         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1084                 /* Set-uid? */
1085                 if (mode & S_ISUID) {
1086                         current->personality &= ~PER_CLEAR_ON_SETID;
1087                         bprm->e_uid = inode->i_uid;
1088                 }
1089
1090                 /* Set-gid? */
1091                 /*
1092                  * If setgid is set but no group execute bit then this
1093                  * is a candidate for mandatory locking, not a setgid
1094                  * executable.
1095                  */
1096                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1097                         current->personality &= ~PER_CLEAR_ON_SETID;
1098                         bprm->e_gid = inode->i_gid;
1099                 }
1100         }
1101
1102         /* fill in binprm security blob */
1103         retval = security_bprm_set(bprm);
1104         if (retval)
1105                 return retval;
1106
1107         memset(bprm->buf,0,BINPRM_BUF_SIZE);
1108         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1109 }
1110
1111 EXPORT_SYMBOL(prepare_binprm);
1112
1113 static int unsafe_exec(struct task_struct *p)
1114 {
1115         int unsafe = 0;
1116         if (p->ptrace & PT_PTRACED) {
1117                 if (p->ptrace & PT_PTRACE_CAP)
1118                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
1119                 else
1120                         unsafe |= LSM_UNSAFE_PTRACE;
1121         }
1122         if (atomic_read(&p->fs->count) > 1 ||
1123             atomic_read(&p->files->count) > 1 ||
1124             atomic_read(&p->sighand->count) > 1)
1125                 unsafe |= LSM_UNSAFE_SHARE;
1126
1127         return unsafe;
1128 }
1129
1130 void compute_creds(struct linux_binprm *bprm)
1131 {
1132         int unsafe;
1133
1134         if (bprm->e_uid != current->uid) {
1135                 suid_keys(current);
1136                 current->pdeath_signal = 0;
1137         }
1138         exec_keys(current);
1139
1140         task_lock(current);
1141         unsafe = unsafe_exec(current);
1142         security_bprm_apply_creds(bprm, unsafe);
1143         task_unlock(current);
1144         security_bprm_post_apply_creds(bprm);
1145 }
1146 EXPORT_SYMBOL(compute_creds);
1147
1148 /*
1149  * Arguments are '\0' separated strings found at the location bprm->p
1150  * points to; chop off the first by relocating brpm->p to right after
1151  * the first '\0' encountered.
1152  */
1153 int remove_arg_zero(struct linux_binprm *bprm)
1154 {
1155         int ret = 0;
1156         unsigned long offset;
1157         char *kaddr;
1158         struct page *page;
1159
1160         if (!bprm->argc)
1161                 return 0;
1162
1163         do {
1164                 offset = bprm->p & ~PAGE_MASK;
1165                 page = get_arg_page(bprm, bprm->p, 0);
1166                 if (!page) {
1167                         ret = -EFAULT;
1168                         goto out;
1169                 }
1170                 kaddr = kmap_atomic(page, KM_USER0);
1171
1172                 for (; offset < PAGE_SIZE && kaddr[offset];
1173                                 offset++, bprm->p++)
1174                         ;
1175
1176                 kunmap_atomic(kaddr, KM_USER0);
1177                 put_arg_page(page);
1178
1179                 if (offset == PAGE_SIZE)
1180                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1181         } while (offset == PAGE_SIZE);
1182
1183         bprm->p++;
1184         bprm->argc--;
1185         ret = 0;
1186
1187 out:
1188         return ret;
1189 }
1190 EXPORT_SYMBOL(remove_arg_zero);
1191
1192 /*
1193  * cycle the list of binary formats handler, until one recognizes the image
1194  */
1195 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1196 {
1197         int try,retval;
1198         struct linux_binfmt *fmt;
1199 #ifdef __alpha__
1200         /* handle /sbin/loader.. */
1201         {
1202             struct exec * eh = (struct exec *) bprm->buf;
1203
1204             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1205                 (eh->fh.f_flags & 0x3000) == 0x3000)
1206             {
1207                 struct file * file;
1208                 unsigned long loader;
1209
1210                 allow_write_access(bprm->file);
1211                 fput(bprm->file);
1212                 bprm->file = NULL;
1213
1214                 loader = bprm->vma->vm_end - sizeof(void *);
1215
1216                 file = open_exec("/sbin/loader");
1217                 retval = PTR_ERR(file);
1218                 if (IS_ERR(file))
1219                         return retval;
1220
1221                 /* Remember if the application is TASO.  */
1222                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1223
1224                 bprm->file = file;
1225                 bprm->loader = loader;
1226                 retval = prepare_binprm(bprm);
1227                 if (retval<0)
1228                         return retval;
1229                 /* should call search_binary_handler recursively here,
1230                    but it does not matter */
1231             }
1232         }
1233 #endif
1234         retval = security_bprm_check(bprm);
1235         if (retval)
1236                 return retval;
1237
1238         /* kernel module loader fixup */
1239         /* so we don't try to load run modprobe in kernel space. */
1240         set_fs(USER_DS);
1241
1242         retval = audit_bprm(bprm);
1243         if (retval)
1244                 return retval;
1245
1246         retval = -ENOENT;
1247         for (try=0; try<2; try++) {
1248                 read_lock(&binfmt_lock);
1249                 list_for_each_entry(fmt, &formats, lh) {
1250                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1251                         if (!fn)
1252                                 continue;
1253                         if (!try_module_get(fmt->module))
1254                                 continue;
1255                         read_unlock(&binfmt_lock);
1256                         retval = fn(bprm, regs);
1257                         if (retval >= 0) {
1258                                 put_binfmt(fmt);
1259                                 allow_write_access(bprm->file);
1260                                 if (bprm->file)
1261                                         fput(bprm->file);
1262                                 bprm->file = NULL;
1263                                 current->did_exec = 1;
1264                                 proc_exec_connector(current);
1265                                 return retval;
1266                         }
1267                         read_lock(&binfmt_lock);
1268                         put_binfmt(fmt);
1269                         if (retval != -ENOEXEC || bprm->mm == NULL)
1270                                 break;
1271                         if (!bprm->file) {
1272                                 read_unlock(&binfmt_lock);
1273                                 return retval;
1274                         }
1275                 }
1276                 read_unlock(&binfmt_lock);
1277                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1278                         break;
1279 #ifdef CONFIG_KMOD
1280                 }else{
1281 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1282                         if (printable(bprm->buf[0]) &&
1283                             printable(bprm->buf[1]) &&
1284                             printable(bprm->buf[2]) &&
1285                             printable(bprm->buf[3]))
1286                                 break; /* -ENOEXEC */
1287                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1288 #endif
1289                 }
1290         }
1291         return retval;
1292 }
1293
1294 EXPORT_SYMBOL(search_binary_handler);
1295
1296 /*
1297  * sys_execve() executes a new program.
1298  */
1299 int do_execve(char * filename,
1300         char __user *__user *argv,
1301         char __user *__user *envp,
1302         struct pt_regs * regs)
1303 {
1304         struct linux_binprm *bprm;
1305         struct file *file;
1306         unsigned long env_p;
1307         int retval;
1308
1309         retval = -ENOMEM;
1310         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1311         if (!bprm)
1312                 goto out_ret;
1313
1314         file = open_exec(filename);
1315         retval = PTR_ERR(file);
1316         if (IS_ERR(file))
1317                 goto out_kfree;
1318
1319         sched_exec();
1320
1321         bprm->file = file;
1322         bprm->filename = filename;
1323         bprm->interp = filename;
1324
1325         retval = bprm_mm_init(bprm);
1326         if (retval)
1327                 goto out_file;
1328
1329         bprm->argc = count(argv, MAX_ARG_STRINGS);
1330         if ((retval = bprm->argc) < 0)
1331                 goto out_mm;
1332
1333         bprm->envc = count(envp, MAX_ARG_STRINGS);
1334         if ((retval = bprm->envc) < 0)
1335                 goto out_mm;
1336
1337         retval = security_bprm_alloc(bprm);
1338         if (retval)
1339                 goto out;
1340
1341         retval = prepare_binprm(bprm);
1342         if (retval < 0)
1343                 goto out;
1344
1345         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1346         if (retval < 0)
1347                 goto out;
1348
1349         bprm->exec = bprm->p;
1350         retval = copy_strings(bprm->envc, envp, bprm);
1351         if (retval < 0)
1352                 goto out;
1353
1354         env_p = bprm->p;
1355         retval = copy_strings(bprm->argc, argv, bprm);
1356         if (retval < 0)
1357                 goto out;
1358         bprm->argv_len = env_p - bprm->p;
1359
1360         retval = search_binary_handler(bprm,regs);
1361         if (retval >= 0) {
1362                 /* execve success */
1363                 free_arg_pages(bprm);
1364                 security_bprm_free(bprm);
1365                 acct_update_integrals(current);
1366                 kfree(bprm);
1367                 return retval;
1368         }
1369
1370 out:
1371         free_arg_pages(bprm);
1372         if (bprm->security)
1373                 security_bprm_free(bprm);
1374
1375 out_mm:
1376         if (bprm->mm)
1377                 mmput (bprm->mm);
1378
1379 out_file:
1380         if (bprm->file) {
1381                 allow_write_access(bprm->file);
1382                 fput(bprm->file);
1383         }
1384 out_kfree:
1385         kfree(bprm);
1386
1387 out_ret:
1388         return retval;
1389 }
1390
1391 int set_binfmt(struct linux_binfmt *new)
1392 {
1393         struct linux_binfmt *old = current->binfmt;
1394
1395         if (new) {
1396                 if (!try_module_get(new->module))
1397                         return -1;
1398         }
1399         current->binfmt = new;
1400         if (old)
1401                 module_put(old->module);
1402         return 0;
1403 }
1404
1405 EXPORT_SYMBOL(set_binfmt);
1406
1407 /* format_corename will inspect the pattern parameter, and output a
1408  * name into corename, which must have space for at least
1409  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1410  */
1411 static int format_corename(char *corename, const char *pattern, long signr)
1412 {
1413         const char *pat_ptr = pattern;
1414         char *out_ptr = corename;
1415         char *const out_end = corename + CORENAME_MAX_SIZE;
1416         int rc;
1417         int pid_in_pattern = 0;
1418         int ispipe = 0;
1419
1420         if (*pattern == '|')
1421                 ispipe = 1;
1422
1423         /* Repeat as long as we have more pattern to process and more output
1424            space */
1425         while (*pat_ptr) {
1426                 if (*pat_ptr != '%') {
1427                         if (out_ptr == out_end)
1428                                 goto out;
1429                         *out_ptr++ = *pat_ptr++;
1430                 } else {
1431                         switch (*++pat_ptr) {
1432                         case 0:
1433                                 goto out;
1434                         /* Double percent, output one percent */
1435                         case '%':
1436                                 if (out_ptr == out_end)
1437                                         goto out;
1438                                 *out_ptr++ = '%';
1439                                 break;
1440                         /* pid */
1441                         case 'p':
1442                                 pid_in_pattern = 1;
1443                                 rc = snprintf(out_ptr, out_end - out_ptr,
1444                                               "%d", current->tgid);
1445                                 if (rc > out_end - out_ptr)
1446                                         goto out;
1447                                 out_ptr += rc;
1448                                 break;
1449                         /* uid */
1450                         case 'u':
1451                                 rc = snprintf(out_ptr, out_end - out_ptr,
1452                                               "%d", current->uid);
1453                                 if (rc > out_end - out_ptr)
1454                                         goto out;
1455                                 out_ptr += rc;
1456                                 break;
1457                         /* gid */
1458                         case 'g':
1459                                 rc = snprintf(out_ptr, out_end - out_ptr,
1460                                               "%d", current->gid);
1461                                 if (rc > out_end - out_ptr)
1462                                         goto out;
1463                                 out_ptr += rc;
1464                                 break;
1465                         /* signal that caused the coredump */
1466                         case 's':
1467                                 rc = snprintf(out_ptr, out_end - out_ptr,
1468                                               "%ld", signr);
1469                                 if (rc > out_end - out_ptr)
1470                                         goto out;
1471                                 out_ptr += rc;
1472                                 break;
1473                         /* UNIX time of coredump */
1474                         case 't': {
1475                                 struct timeval tv;
1476                                 do_gettimeofday(&tv);
1477                                 rc = snprintf(out_ptr, out_end - out_ptr,
1478                                               "%lu", tv.tv_sec);
1479                                 if (rc > out_end - out_ptr)
1480                                         goto out;
1481                                 out_ptr += rc;
1482                                 break;
1483                         }
1484                         /* hostname */
1485                         case 'h':
1486                                 down_read(&uts_sem);
1487                                 rc = snprintf(out_ptr, out_end - out_ptr,
1488                                               "%s", utsname()->nodename);
1489                                 up_read(&uts_sem);
1490                                 if (rc > out_end - out_ptr)
1491                                         goto out;
1492                                 out_ptr += rc;
1493                                 break;
1494                         /* executable */
1495                         case 'e':
1496                                 rc = snprintf(out_ptr, out_end - out_ptr,
1497                                               "%s", current->comm);
1498                                 if (rc > out_end - out_ptr)
1499                                         goto out;
1500                                 out_ptr += rc;
1501                                 break;
1502                         /* core limit size */
1503                         case 'c':
1504                                 rc = snprintf(out_ptr, out_end - out_ptr,
1505                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1506                                 if (rc > out_end - out_ptr)
1507                                         goto out;
1508                                 out_ptr += rc;
1509                                 break;
1510                         default:
1511                                 break;
1512                         }
1513                         ++pat_ptr;
1514                 }
1515         }
1516         /* Backward compatibility with core_uses_pid:
1517          *
1518          * If core_pattern does not include a %p (as is the default)
1519          * and core_uses_pid is set, then .%pid will be appended to
1520          * the filename. Do not do this for piped commands. */
1521         if (!ispipe && !pid_in_pattern
1522             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1523                 rc = snprintf(out_ptr, out_end - out_ptr,
1524                               ".%d", current->tgid);
1525                 if (rc > out_end - out_ptr)
1526                         goto out;
1527                 out_ptr += rc;
1528         }
1529 out:
1530         *out_ptr = 0;
1531         return ispipe;
1532 }
1533
1534 static void zap_process(struct task_struct *start)
1535 {
1536         struct task_struct *t;
1537
1538         start->signal->flags = SIGNAL_GROUP_EXIT;
1539         start->signal->group_stop_count = 0;
1540
1541         t = start;
1542         do {
1543                 if (t != current && t->mm) {
1544                         t->mm->core_waiters++;
1545                         sigaddset(&t->pending.signal, SIGKILL);
1546                         signal_wake_up(t, 1);
1547                 }
1548         } while ((t = next_thread(t)) != start);
1549 }
1550
1551 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1552                                 int exit_code)
1553 {
1554         struct task_struct *g, *p;
1555         unsigned long flags;
1556         int err = -EAGAIN;
1557
1558         spin_lock_irq(&tsk->sighand->siglock);
1559         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1560                 tsk->signal->group_exit_code = exit_code;
1561                 zap_process(tsk);
1562                 err = 0;
1563         }
1564         spin_unlock_irq(&tsk->sighand->siglock);
1565         if (err)
1566                 return err;
1567
1568         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1569                 goto done;
1570
1571         rcu_read_lock();
1572         for_each_process(g) {
1573                 if (g == tsk->group_leader)
1574                         continue;
1575
1576                 p = g;
1577                 do {
1578                         if (p->mm) {
1579                                 if (p->mm == mm) {
1580                                         /*
1581                                          * p->sighand can't disappear, but
1582                                          * may be changed by de_thread()
1583                                          */
1584                                         lock_task_sighand(p, &flags);
1585                                         zap_process(p);
1586                                         unlock_task_sighand(p, &flags);
1587                                 }
1588                                 break;
1589                         }
1590                 } while ((p = next_thread(p)) != g);
1591         }
1592         rcu_read_unlock();
1593 done:
1594         return mm->core_waiters;
1595 }
1596
1597 static int coredump_wait(int exit_code)
1598 {
1599         struct task_struct *tsk = current;
1600         struct mm_struct *mm = tsk->mm;
1601         struct completion startup_done;
1602         struct completion *vfork_done;
1603         int core_waiters;
1604
1605         init_completion(&mm->core_done);
1606         init_completion(&startup_done);
1607         mm->core_startup_done = &startup_done;
1608
1609         core_waiters = zap_threads(tsk, mm, exit_code);
1610         up_write(&mm->mmap_sem);
1611
1612         if (unlikely(core_waiters < 0))
1613                 goto fail;
1614
1615         /*
1616          * Make sure nobody is waiting for us to release the VM,
1617          * otherwise we can deadlock when we wait on each other
1618          */
1619         vfork_done = tsk->vfork_done;
1620         if (vfork_done) {
1621                 tsk->vfork_done = NULL;
1622                 complete(vfork_done);
1623         }
1624
1625         if (core_waiters)
1626                 wait_for_completion(&startup_done);
1627 fail:
1628         BUG_ON(mm->core_waiters);
1629         return core_waiters;
1630 }
1631
1632 /*
1633  * set_dumpable converts traditional three-value dumpable to two flags and
1634  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1635  * these bits are not changed atomically.  So get_dumpable can observe the
1636  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1637  * return either old dumpable or new one by paying attention to the order of
1638  * modifying the bits.
1639  *
1640  * dumpable |   mm->flags (binary)
1641  * old  new | initial interim  final
1642  * ---------+-----------------------
1643  *  0    1  |   00      01      01
1644  *  0    2  |   00      10(*)   11
1645  *  1    0  |   01      00      00
1646  *  1    2  |   01      11      11
1647  *  2    0  |   11      10(*)   00
1648  *  2    1  |   11      11      01
1649  *
1650  * (*) get_dumpable regards interim value of 10 as 11.
1651  */
1652 void set_dumpable(struct mm_struct *mm, int value)
1653 {
1654         switch (value) {
1655         case 0:
1656                 clear_bit(MMF_DUMPABLE, &mm->flags);
1657                 smp_wmb();
1658                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1659                 break;
1660         case 1:
1661                 set_bit(MMF_DUMPABLE, &mm->flags);
1662                 smp_wmb();
1663                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1664                 break;
1665         case 2:
1666                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1667                 smp_wmb();
1668                 set_bit(MMF_DUMPABLE, &mm->flags);
1669                 break;
1670         }
1671 }
1672 EXPORT_SYMBOL_GPL(set_dumpable);
1673
1674 int get_dumpable(struct mm_struct *mm)
1675 {
1676         int ret;
1677
1678         ret = mm->flags & 0x3;
1679         return (ret >= 2) ? 2 : ret;
1680 }
1681
1682 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1683 {
1684         char corename[CORENAME_MAX_SIZE + 1];
1685         struct mm_struct *mm = current->mm;
1686         struct linux_binfmt * binfmt;
1687         struct inode * inode;
1688         struct file * file;
1689         int retval = 0;
1690         int fsuid = current->fsuid;
1691         int flag = 0;
1692         int ispipe = 0;
1693         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1694         char **helper_argv = NULL;
1695         int helper_argc = 0;
1696         char *delimit;
1697
1698         audit_core_dumps(signr);
1699
1700         binfmt = current->binfmt;
1701         if (!binfmt || !binfmt->core_dump)
1702                 goto fail;
1703         down_write(&mm->mmap_sem);
1704         if (!get_dumpable(mm)) {
1705                 up_write(&mm->mmap_sem);
1706                 goto fail;
1707         }
1708
1709         /*
1710          *      We cannot trust fsuid as being the "true" uid of the
1711          *      process nor do we know its entire history. We only know it
1712          *      was tainted so we dump it as root in mode 2.
1713          */
1714         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1715                 flag = O_EXCL;          /* Stop rewrite attacks */
1716                 current->fsuid = 0;     /* Dump root private */
1717         }
1718         set_dumpable(mm, 0);
1719
1720         retval = coredump_wait(exit_code);
1721         if (retval < 0)
1722                 goto fail;
1723
1724         /*
1725          * Clear any false indication of pending signals that might
1726          * be seen by the filesystem code called to write the core file.
1727          */
1728         clear_thread_flag(TIF_SIGPENDING);
1729
1730         /*
1731          * lock_kernel() because format_corename() is controlled by sysctl, which
1732          * uses lock_kernel()
1733          */
1734         lock_kernel();
1735         ispipe = format_corename(corename, core_pattern, signr);
1736         unlock_kernel();
1737         /*
1738          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1739          * to a pipe.  Since we're not writing directly to the filesystem
1740          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1741          * created unless the pipe reader choses to write out the core file
1742          * at which point file size limits and permissions will be imposed
1743          * as it does with any other process
1744          */
1745         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1746                 goto fail_unlock;
1747
1748         if (ispipe) {
1749                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1750                 /* Terminate the string before the first option */
1751                 delimit = strchr(corename, ' ');
1752                 if (delimit)
1753                         *delimit = '\0';
1754                 delimit = strrchr(helper_argv[0], '/');
1755                 if (delimit)
1756                         delimit++;
1757                 else
1758                         delimit = helper_argv[0];
1759                 if (!strcmp(delimit, current->comm)) {
1760                         printk(KERN_NOTICE "Recursive core dump detected, "
1761                                         "aborting\n");
1762                         goto fail_unlock;
1763                 }
1764
1765                 core_limit = RLIM_INFINITY;
1766
1767                 /* SIGPIPE can happen, but it's just never processed */
1768                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1769                                 &file)) {
1770                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1771                                corename);
1772                         goto fail_unlock;
1773                 }
1774         } else
1775                 file = filp_open(corename,
1776                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1777                                  0600);
1778         if (IS_ERR(file))
1779                 goto fail_unlock;
1780         inode = file->f_path.dentry->d_inode;
1781         if (inode->i_nlink > 1)
1782                 goto close_fail;        /* multiple links - don't dump */
1783         if (!ispipe && d_unhashed(file->f_path.dentry))
1784                 goto close_fail;
1785
1786         /* AK: actually i see no reason to not allow this for named pipes etc.,
1787            but keep the previous behaviour for now. */
1788         if (!ispipe && !S_ISREG(inode->i_mode))
1789                 goto close_fail;
1790         if (!file->f_op)
1791                 goto close_fail;
1792         if (!file->f_op->write)
1793                 goto close_fail;
1794         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1795                 goto close_fail;
1796
1797         retval = binfmt->core_dump(signr, regs, file, core_limit);
1798
1799         if (retval)
1800                 current->signal->group_exit_code |= 0x80;
1801 close_fail:
1802         filp_close(file, NULL);
1803 fail_unlock:
1804         if (helper_argv)
1805                 argv_free(helper_argv);
1806
1807         current->fsuid = fsuid;
1808         complete_all(&mm->core_done);
1809 fail:
1810         return retval;
1811 }