fs/exec.c

   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/slab.h>
  26 #include <linux/file.h>
  27 #include <linux/fdtable.h>
  28 #include <linux/mm.h>
  29 #include <linux/stat.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/smp_lock.h>
  32 #include <linux/swap.h>
  33 #include <linux/string.h>
  34 #include <linux/init.h>
  35 #include <linux/pagemap.h>
  36 #include <linux/highmem.h>
  37 #include <linux/spinlock.h>
  38 #include <linux/key.h>
  39 #include <linux/personality.h>
  40 #include <linux/binfmts.h>
  41 #include <linux/utsname.h>
  42 #include <linux/pid_namespace.h>
  43 #include <linux/module.h>
  44 #include <linux/namei.h>
  45 #include <linux/proc_fs.h>
  46 #include <linux/mount.h>
  47 #include <linux/security.h>
  48 #include <linux/ima.h>
  49 #include <linux/syscalls.h>
  50 #include <linux/tsacct_kern.h>
  51 #include <linux/cn_proc.h>
  52 #include <linux/audit.h>
  53 #include <linux/tracehook.h>
  54 #include <linux/kmod.h>
  55 #include <linux/fsnotify.h>
  56
  57 #include <asm/uaccess.h>
  58 #include <asm/mmu_context.h>
  59 #include <asm/tlb.h>
  60 #include "internal.h"
  61
  62 int core_uses_pid;
  63 char core_pattern[CORENAME_MAX_SIZE] = "core";
  64 int suid_dumpable = 0;
  65
  66 /* The maximal length of core_pattern is also specified in sysctl.c */
  67
  68 static LIST_HEAD(formats);
  69 static DEFINE_RWLOCK(binfmt_lock);
  70
  71 int register_binfmt(struct linux_binfmt * fmt)
  72 {
  73         if (!fmt)
  74                 return -EINVAL;
  75         write_lock(&binfmt_lock);
  76         list_add(&fmt->lh, &formats);
  77         write_unlock(&binfmt_lock);
  78         return 0;
  79 }
  80
  81 EXPORT_SYMBOL(register_binfmt);
  82
  83 void unregister_binfmt(struct linux_binfmt * fmt)
  84 {
  85         write_lock(&binfmt_lock);
  86         list_del(&fmt->lh);
  87         write_unlock(&binfmt_lock);
  88 }
  89
  90 EXPORT_SYMBOL(unregister_binfmt);
  91
  92 static inline void put_binfmt(struct linux_binfmt * fmt)
  93 {
  94         module_put(fmt->module);
  95 }
  96
  97 /*
  98  * Note that a shared library must be both readable and executable due to
  99  * security reasons.
 100  *
 101  * Also note that we take the address to load from from the file itself.
 102  */
 103 SYSCALL_DEFINE1(uselib, const char __user *, library)
 104 {
 105         struct file *file;
 106         struct nameidata nd;
 107         char *tmp = getname(library);
 108         int error = PTR_ERR(tmp);
 109
 110         if (!IS_ERR(tmp)) {
 111                 error = path_lookup_open(AT_FDCWD, tmp,
 112                                          LOOKUP_FOLLOW, &nd,
 113                                          FMODE_READ|FMODE_EXEC);
 114                 putname(tmp);
 115         }
 116         if (error)
 117                 goto out;
 118
 119         error = -EINVAL;
 120         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 121                 goto exit;
 122
 123         error = -EACCES;
 124         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 125                 goto exit;
 126
 127         error = inode_permission(nd.path.dentry->d_inode,
 128                                  MAY_READ | MAY_EXEC | MAY_OPEN);
 129         if (error)
 130                 goto exit;
 131         error = ima_path_check(&nd.path, 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         fsnotify_open(file->f_path.dentry);
 141
 142         error = -ENOEXEC;
 143         if(file->f_op) {
 144                 struct linux_binfmt * fmt;
 145
 146                 read_lock(&binfmt_lock);
 147                 list_for_each_entry(fmt, &formats, lh) {
 148                         if (!fmt->load_shlib)
 149                                 continue;
 150                         if (!try_module_get(fmt->module))
 151                                 continue;
 152                         read_unlock(&binfmt_lock);
 153                         error = fmt->load_shlib(file);
 154                         read_lock(&binfmt_lock);
 155                         put_binfmt(fmt);
 156                         if (error != -ENOEXEC)
 157                                 break;
 158                 }
 159                 read_unlock(&binfmt_lock);
 160         }
 161         fput(file);
 162 out:
 163         return error;
 164 exit:
 165         release_open_intent(&nd);
 166         path_put(&nd.path);
 167         goto out;
 168 }
 169
 170 #ifdef CONFIG_MMU
 171
 172 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 173                 int write)
 174 {
 175         struct page *page;
 176         int ret;
 177
 178 #ifdef CONFIG_STACK_GROWSUP
 179         if (write) {
 180                 ret = expand_stack_downwards(bprm->vma, pos);
 181                 if (ret < 0)
 182                         return NULL;
 183         }
 184 #endif
 185         ret = get_user_pages(current, bprm->mm, pos,
 186                         1, write, 1, &page, NULL);
 187         if (ret <= 0)
 188                 return NULL;
 189
 190         if (write) {
 191                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 192                 struct rlimit *rlim;
 193
 194                 /*
 195                  * We've historically supported up to 32 pages (ARG_MAX)
 196                  * of argument strings even with small stacks
 197                  */
 198                 if (size <= ARG_MAX)
 199                         return page;
 200
 201                 /*
 202                  * Limit to 1/4-th the stack size for the argv+env strings.
 203                  * This ensures that:
 204                  *  - the remaining binfmt code will not run out of stack space,
 205                  *  - the program will have a reasonable amount of stack left
 206                  *    to work from.
 207                  */
 208                 rlim = current->signal->rlim;
 209                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 210                         put_page(page);
 211                         return NULL;
 212                 }
 213         }
 214
 215         return page;
 216 }
 217
 218 static void put_arg_page(struct page *page)
 219 {
 220         put_page(page);
 221 }
 222
 223 static void free_arg_page(struct linux_binprm *bprm, int i)
 224 {
 225 }
 226
 227 static void free_arg_pages(struct linux_binprm *bprm)
 228 {
 229 }
 230
 231 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 232                 struct page *page)
 233 {
 234         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 235 }
 236
 237 static int __bprm_mm_init(struct linux_binprm *bprm)
 238 {
 239         int err;
 240         struct vm_area_struct *vma = NULL;
 241         struct mm_struct *mm = bprm->mm;
 242
 243         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 244         if (!vma)
 245                 return -ENOMEM;
 246
 247         down_write(&mm->mmap_sem);
 248         vma->vm_mm = mm;
 249
 250         /*
 251          * Place the stack at the largest stack address the architecture
 252          * supports. Later, we'll move this to an appropriate place. We don't
 253          * use STACK_TOP because that can depend on attributes which aren't
 254          * configured yet.
 255          */
 256         vma->vm_end = STACK_TOP_MAX;
 257         vma->vm_start = vma->vm_end - PAGE_SIZE;
 258         vma->vm_flags = VM_STACK_FLAGS;
 259         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 260         err = insert_vm_struct(mm, vma);
 261         if (err)
 262                 goto err;
 263
 264         mm->stack_vm = mm->total_vm = 1;
 265         up_write(&mm->mmap_sem);
 266         bprm->p = vma->vm_end - sizeof(void *);
 267         return 0;
 268 err:
 269         up_write(&mm->mmap_sem);
 270         bprm->vma = NULL;
 271         kmem_cache_free(vm_area_cachep, vma);
 272         return err;
 273 }
 274
 275 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 276 {
 277         return len <= MAX_ARG_STRLEN;
 278 }
 279
 280 #else
 281
 282 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 283                 int write)
 284 {
 285         struct page *page;
 286
 287         page = bprm->page[pos / PAGE_SIZE];
 288         if (!page && write) {
 289                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 290                 if (!page)
 291                         return NULL;
 292                 bprm->page[pos / PAGE_SIZE] = page;
 293         }
 294
 295         return page;
 296 }
 297
 298 static void put_arg_page(struct page *page)
 299 {
 300 }
 301
 302 static void free_arg_page(struct linux_binprm *bprm, int i)
 303 {
 304         if (bprm->page[i]) {
 305                 __free_page(bprm->page[i]);
 306                 bprm->page[i] = NULL;
 307         }
 308 }
 309
 310 static void free_arg_pages(struct linux_binprm *bprm)
 311 {
 312         int i;
 313
 314         for (i = 0; i < MAX_ARG_PAGES; i++)
 315                 free_arg_page(bprm, i);
 316 }
 317
 318 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 319                 struct page *page)
 320 {
 321 }
 322
 323 static int __bprm_mm_init(struct linux_binprm *bprm)
 324 {
 325         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 326         return 0;
 327 }
 328
 329 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 330 {
 331         return len <= bprm->p;
 332 }
 333
 334 #endif /* CONFIG_MMU */
 335
 336 /*
 337  * Create a new mm_struct and populate it with a temporary stack
 338  * vm_area_struct.  We don't have enough context at this point to set the stack
 339  * flags, permissions, and offset, so we use temporary values.  We'll update
 340  * them later in setup_arg_pages().
 341  */
 342 int bprm_mm_init(struct linux_binprm *bprm)
 343 {
 344         int err;
 345         struct mm_struct *mm = NULL;
 346
 347         bprm->mm = mm = mm_alloc();
 348         err = -ENOMEM;
 349         if (!mm)
 350                 goto err;
 351
 352         err = init_new_context(current, mm);
 353         if (err)
 354                 goto err;
 355
 356         err = __bprm_mm_init(bprm);
 357         if (err)
 358                 goto err;
 359
 360         return 0;
 361
 362 err:
 363         if (mm) {
 364                 bprm->mm = NULL;
 365                 mmdrop(mm);
 366         }
 367
 368         return err;
 369 }
 370
 371 /*
 372  * count() counts the number of strings in array ARGV.
 373  */
 374 static int count(char __user * __user * argv, int max)
 375 {
 376         int i = 0;
 377
 378         if (argv != NULL) {
 379                 for (;;) {
 380                         char __user * p;
 381
 382                         if (get_user(p, argv))
 383                                 return -EFAULT;
 384                         if (!p)
 385                                 break;
 386                         argv++;
 387                         if (i++ >= max)
 388                                 return -E2BIG;
 389                         cond_resched();
 390                 }
 391         }
 392         return i;
 393 }
 394
 395 /*
 396  * 'copy_strings()' copies argument/environment strings from the old
 397  * processes's memory to the new process's stack.  The call to get_user_pages()
 398  * ensures the destination page is created and not swapped out.
 399  */
 400 static int copy_strings(int argc, char __user * __user * argv,
 401                         struct linux_binprm *bprm)
 402 {
 403         struct page *kmapped_page = NULL;
 404         char *kaddr = NULL;
 405         unsigned long kpos = 0;
 406         int ret;
 407
 408         while (argc-- > 0) {
 409                 char __user *str;
 410                 int len;
 411                 unsigned long pos;
 412
 413                 if (get_user(str, argv+argc) ||
 414                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 415                         ret = -EFAULT;
 416                         goto out;
 417                 }
 418
 419                 if (!valid_arg_len(bprm, len)) {
 420                         ret = -E2BIG;
 421                         goto out;
 422                 }
 423
 424                 /* We're going to work our way backwords. */
 425                 pos = bprm->p;
 426                 str += len;
 427                 bprm->p -= len;
 428
 429                 while (len > 0) {
 430                         int offset, bytes_to_copy;
 431
 432                         offset = pos % PAGE_SIZE;
 433                         if (offset == 0)
 434                                 offset = PAGE_SIZE;
 435
 436                         bytes_to_copy = offset;
 437                         if (bytes_to_copy > len)
 438                                 bytes_to_copy = len;
 439
 440                         offset -= bytes_to_copy;
 441                         pos -= bytes_to_copy;
 442                         str -= bytes_to_copy;
 443                         len -= bytes_to_copy;
 444
 445                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 446                                 struct page *page;
 447
 448                                 page = get_arg_page(bprm, pos, 1);
 449                                 if (!page) {
 450                                         ret = -E2BIG;
 451                                         goto out;
 452                                 }
 453
 454                                 if (kmapped_page) {
 455                                         flush_kernel_dcache_page(kmapped_page);
 456                                         kunmap(kmapped_page);
 457                                         put_arg_page(kmapped_page);
 458                                 }
 459                                 kmapped_page = page;
 460                                 kaddr = kmap(kmapped_page);
 461                                 kpos = pos & PAGE_MASK;
 462                                 flush_arg_page(bprm, kpos, kmapped_page);
 463                         }
 464                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 465                                 ret = -EFAULT;
 466                                 goto out;
 467                         }
 468                 }
 469         }
 470         ret = 0;
 471 out:
 472         if (kmapped_page) {
 473                 flush_kernel_dcache_page(kmapped_page);
 474                 kunmap(kmapped_page);
 475                 put_arg_page(kmapped_page);
 476         }
 477         return ret;
 478 }
 479
 480 /*
 481  * Like copy_strings, but get argv and its values from kernel memory.
 482  */
 483 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 484 {
 485         int r;
 486         mm_segment_t oldfs = get_fs();
 487         set_fs(KERNEL_DS);
 488         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 489         set_fs(oldfs);
 490         return r;
 491 }
 492 EXPORT_SYMBOL(copy_strings_kernel);
 493
 494 #ifdef CONFIG_MMU
 495
 496 /*
 497  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 498  * the binfmt code determines where the new stack should reside, we shift it to
 499  * its final location.  The process proceeds as follows:
 500  *
 501  * 1) Use shift to calculate the new vma endpoints.
 502  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 503  *    arguments passed to subsequent functions are consistent.
 504  * 3) Move vma's page tables to the new range.
 505  * 4) Free up any cleared pgd range.
 506  * 5) Shrink the vma to cover only the new range.
 507  */
 508 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 509 {
 510         struct mm_struct *mm = vma->vm_mm;
 511         unsigned long old_start = vma->vm_start;
 512         unsigned long old_end = vma->vm_end;
 513         unsigned long length = old_end - old_start;
 514         unsigned long new_start = old_start - shift;
 515         unsigned long new_end = old_end - shift;
 516         struct mmu_gather *tlb;
 517
 518         BUG_ON(new_start > new_end);
 519
 520         /*
 521          * ensure there are no vmas between where we want to go
 522          * and where we are
 523          */
 524         if (vma != find_vma(mm, new_start))
 525                 return -EFAULT;
 526
 527         /*
 528          * cover the whole range: [new_start, old_end)
 529          */
 530         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 531
 532         /*
 533          * move the page tables downwards, on failure we rely on
 534          * process cleanup to remove whatever mess we made.
 535          */
 536         if (length != move_page_tables(vma, old_start,
 537                                        vma, new_start, length))
 538                 return -ENOMEM;
 539
 540         lru_add_drain();
 541         tlb = tlb_gather_mmu(mm, 0);
 542         if (new_end > old_start) {
 543                 /*
 544                  * when the old and new regions overlap clear from new_end.
 545                  */
 546                 free_pgd_range(tlb, new_end, old_end, new_end,
 547                         vma->vm_next ? vma->vm_next->vm_start : 0);
 548         } else {
 549                 /*
 550                  * otherwise, clean from old_start; this is done to not touch
 551                  * the address space in [new_end, old_start) some architectures
 552                  * have constraints on va-space that make this illegal (IA64) -
 553                  * for the others its just a little faster.
 554                  */
 555                 free_pgd_range(tlb, old_start, old_end, new_end,
 556                         vma->vm_next ? vma->vm_next->vm_start : 0);
 557         }
 558         tlb_finish_mmu(tlb, new_end, old_end);
 559
 560         /*
 561          * shrink the vma to just the new range.
 562          */
 563         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 564
 565         return 0;
 566 }
 567
 568 #define EXTRA_STACK_VM_PAGES    20      /* random */
 569
 570 /*
 571  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 572  * the stack is optionally relocated, and some extra space is added.
 573  */
 574 int setup_arg_pages(struct linux_binprm *bprm,
 575                     unsigned long stack_top,
 576                     int executable_stack)
 577 {
 578         unsigned long ret;
 579         unsigned long stack_shift;
 580         struct mm_struct *mm = current->mm;
 581         struct vm_area_struct *vma = bprm->vma;
 582         struct vm_area_struct *prev = NULL;
 583         unsigned long vm_flags;
 584         unsigned long stack_base;
 585
 586 #ifdef CONFIG_STACK_GROWSUP
 587         /* Limit stack size to 1GB */
 588         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 589         if (stack_base > (1 << 30))
 590                 stack_base = 1 << 30;
 591
 592         /* Make sure we didn't let the argument array grow too large. */
 593         if (vma->vm_end - vma->vm_start > stack_base)
 594                 return -ENOMEM;
 595
 596         stack_base = PAGE_ALIGN(stack_top - stack_base);
 597
 598         stack_shift = vma->vm_start - stack_base;
 599         mm->arg_start = bprm->p - stack_shift;
 600         bprm->p = vma->vm_end - stack_shift;
 601 #else
 602         stack_top = arch_align_stack(stack_top);
 603         stack_top = PAGE_ALIGN(stack_top);
 604         stack_shift = vma->vm_end - stack_top;
 605
 606         bprm->p -= stack_shift;
 607         mm->arg_start = bprm->p;
 608 #endif
 609
 610         if (bprm->loader)
 611                 bprm->loader -= stack_shift;
 612         bprm->exec -= stack_shift;
 613
 614         down_write(&mm->mmap_sem);
 615         vm_flags = VM_STACK_FLAGS;
 616
 617         /*
 618          * Adjust stack execute permissions; explicitly enable for
 619          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 620          * (arch default) otherwise.
 621          */
 622         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 623                 vm_flags |= VM_EXEC;
 624         else if (executable_stack == EXSTACK_DISABLE_X)
 625                 vm_flags &= ~VM_EXEC;
 626         vm_flags |= mm->def_flags;
 627
 628         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 629                         vm_flags);
 630         if (ret)
 631                 goto out_unlock;
 632         BUG_ON(prev != vma);
 633
 634         /* Move stack pages down in memory. */
 635         if (stack_shift) {
 636                 ret = shift_arg_pages(vma, stack_shift);
 637                 if (ret) {
 638                         up_write(&mm->mmap_sem);
 639                         return ret;
 640                 }
 641         }
 642
 643 #ifdef CONFIG_STACK_GROWSUP
 644         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 645 #else
 646         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 647 #endif
 648         ret = expand_stack(vma, stack_base);
 649         if (ret)
 650                 ret = -EFAULT;
 651
 652 out_unlock:
 653         up_write(&mm->mmap_sem);
 654         return 0;
 655 }
 656 EXPORT_SYMBOL(setup_arg_pages);
 657
 658 #endif /* CONFIG_MMU */
 659
 660 struct file *open_exec(const char *name)
 661 {
 662         struct nameidata nd;
 663         struct file *file;
 664         int err;
 665
 666         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
 667                                 FMODE_READ|FMODE_EXEC);
 668         if (err)
 669                 goto out;
 670
 671         err = -EACCES;
 672         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 673                 goto out_path_put;
 674
 675         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 676                 goto out_path_put;
 677
 678         err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN);
 679         if (err)
 680                 goto out_path_put;
 681         err = ima_path_check(&nd.path, MAY_EXEC | MAY_OPEN);
 682         if (err)
 683                 goto out_path_put;
 684
 685         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 686         if (IS_ERR(file))
 687                 return file;
 688
 689         fsnotify_open(file->f_path.dentry);
 690
 691         err = deny_write_access(file);
 692         if (err) {
 693                 fput(file);
 694                 goto out;
 695         }
 696
 697         return file;
 698
 699  out_path_put:
 700         release_open_intent(&nd);
 701         path_put(&nd.path);
 702  out:
 703         return ERR_PTR(err);
 704 }
 705 EXPORT_SYMBOL(open_exec);
 706
 707 int kernel_read(struct file *file, unsigned long offset,
 708         char *addr, unsigned long count)
 709 {
 710         mm_segment_t old_fs;
 711         loff_t pos = offset;
 712         int result;
 713
 714         old_fs = get_fs();
 715         set_fs(get_ds());
 716         /* The cast to a user pointer is valid due to the set_fs() */
 717         result = vfs_read(file, (void __user *)addr, count, &pos);
 718         set_fs(old_fs);
 719         return result;
 720 }
 721
 722 EXPORT_SYMBOL(kernel_read);
 723
 724 static int exec_mmap(struct mm_struct *mm)
 725 {
 726         struct task_struct *tsk;
 727         struct mm_struct * old_mm, *active_mm;
 728
 729         /* Notify parent that we're no longer interested in the old VM */
 730         tsk = current;
 731         old_mm = current->mm;
 732         mm_release(tsk, old_mm);
 733
 734         if (old_mm) {
 735                 /*
 736                  * Make sure that if there is a core dump in progress
 737                  * for the old mm, we get out and die instead of going
 738                  * through with the exec.  We must hold mmap_sem around
 739                  * checking core_state and changing tsk->mm.
 740                  */
 741                 down_read(&old_mm->mmap_sem);
 742                 if (unlikely(old_mm->core_state)) {
 743                         up_read(&old_mm->mmap_sem);
 744                         return -EINTR;
 745                 }
 746         }
 747         task_lock(tsk);
 748         active_mm = tsk->active_mm;
 749         tsk->mm = mm;
 750         tsk->active_mm = mm;
 751         activate_mm(active_mm, mm);
 752         task_unlock(tsk);
 753         arch_pick_mmap_layout(mm);
 754         if (old_mm) {
 755                 up_read(&old_mm->mmap_sem);
 756                 BUG_ON(active_mm != old_mm);
 757                 mm_update_next_owner(old_mm);
 758                 mmput(old_mm);
 759                 return 0;
 760         }
 761         mmdrop(active_mm);
 762         return 0;
 763 }
 764
 765 /*
 766  * This function makes sure the current process has its own signal table,
 767  * so that flush_signal_handlers can later reset the handlers without
 768  * disturbing other processes.  (Other processes might share the signal
 769  * table via the CLONE_SIGHAND option to clone().)
 770  */
 771 static int de_thread(struct task_struct *tsk)
 772 {
 773         struct signal_struct *sig = tsk->signal;
 774         struct sighand_struct *oldsighand = tsk->sighand;
 775         spinlock_t *lock = &oldsighand->siglock;
 776         int count;
 777
 778         if (thread_group_empty(tsk))
 779                 goto no_thread_group;
 780
 781         /*
 782          * Kill all other threads in the thread group.
 783          */
 784         spin_lock_irq(lock);
 785         if (signal_group_exit(sig)) {
 786                 /*
 787                  * Another group action in progress, just
 788                  * return so that the signal is processed.
 789                  */
 790                 spin_unlock_irq(lock);
 791                 return -EAGAIN;
 792         }
 793         sig->group_exit_task = tsk;
 794         zap_other_threads(tsk);
 795
 796         /* Account for the thread group leader hanging around: */
 797         count = thread_group_leader(tsk) ? 1 : 2;
 798         sig->notify_count = count;
 799         while (atomic_read(&sig->count) > count) {
 800                 __set_current_state(TASK_UNINTERRUPTIBLE);
 801                 spin_unlock_irq(lock);
 802                 schedule();
 803                 spin_lock_irq(lock);
 804         }
 805         spin_unlock_irq(lock);
 806
 807         /*
 808          * At this point all other threads have exited, all we have to
 809          * do is to wait for the thread group leader to become inactive,
 810          * and to assume its PID:
 811          */
 812         if (!thread_group_leader(tsk)) {
 813                 struct task_struct *leader = tsk->group_leader;
 814
 815                 sig->notify_count = -1; /* for exit_notify() */
 816                 for (;;) {
 817                         write_lock_irq(&tasklist_lock);
 818                         if (likely(leader->exit_state))
 819                                 break;
 820                         __set_current_state(TASK_UNINTERRUPTIBLE);
 821                         write_unlock_irq(&tasklist_lock);
 822                         schedule();
 823                 }
 824
 825                 /*
 826                  * The only record we have of the real-time age of a
 827                  * process, regardless of execs it's done, is start_time.
 828                  * All the past CPU time is accumulated in signal_struct
 829                  * from sister threads now dead.  But in this non-leader
 830                  * exec, nothing survives from the original leader thread,
 831                  * whose birth marks the true age of this process now.
 832                  * When we take on its identity by switching to its PID, we
 833                  * also take its birthdate (always earlier than our own).
 834                  */
 835                 tsk->start_time = leader->start_time;
 836
 837                 BUG_ON(!same_thread_group(leader, tsk));
 838                 BUG_ON(has_group_leader_pid(tsk));
 839                 /*
 840                  * An exec() starts a new thread group with the
 841                  * TGID of the previous thread group. Rehash the
 842                  * two threads with a switched PID, and release
 843                  * the former thread group leader:
 844                  */
 845
 846                 /* Become a process group leader with the old leader's pid.
 847                  * The old leader becomes a thread of the this thread group.
 848                  * Note: The old leader also uses this pid until release_task
 849                  *       is called.  Odd but simple and correct.
 850                  */
 851                 detach_pid(tsk, PIDTYPE_PID);
 852                 tsk->pid = leader->pid;
 853                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 854                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 855                 transfer_pid(leader, tsk, PIDTYPE_SID);
 856                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 857
 858                 tsk->group_leader = tsk;
 859                 leader->group_leader = tsk;
 860
 861                 tsk->exit_signal = SIGCHLD;
 862
 863                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 864                 leader->exit_state = EXIT_DEAD;
 865                 write_unlock_irq(&tasklist_lock);
 866
 867                 release_task(leader);
 868         }
 869
 870         sig->group_exit_task = NULL;
 871         sig->notify_count = 0;
 872
 873 no_thread_group:
 874         exit_itimers(sig);
 875         flush_itimer_signals();
 876
 877         if (atomic_read(&oldsighand->count) != 1) {
 878                 struct sighand_struct *newsighand;
 879                 /*
 880                  * This ->sighand is shared with the CLONE_SIGHAND
 881                  * but not CLONE_THREAD task, switch to the new one.
 882                  */
 883                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 884                 if (!newsighand)
 885                         return -ENOMEM;
 886
 887                 atomic_set(&newsighand->count, 1);
 888                 memcpy(newsighand->action, oldsighand->action,
 889                        sizeof(newsighand->action));
 890
 891                 write_lock_irq(&tasklist_lock);
 892                 spin_lock(&oldsighand->siglock);
 893                 rcu_assign_pointer(tsk->sighand, newsighand);
 894                 spin_unlock(&oldsighand->siglock);
 895                 write_unlock_irq(&tasklist_lock);
 896
 897                 __cleanup_sighand(oldsighand);
 898         }
 899
 900         BUG_ON(!thread_group_leader(tsk));
 901         return 0;
 902 }
 903
 904 /*
 905  * These functions flushes out all traces of the currently running executable
 906  * so that a new one can be started
 907  */
 908 static void flush_old_files(struct files_struct * files)
 909 {
 910         long j = -1;
 911         struct fdtable *fdt;
 912
 913         spin_lock(&files->file_lock);
 914         for (;;) {
 915                 unsigned long set, i;
 916
 917                 j++;
 918                 i = j * __NFDBITS;
 919                 fdt = files_fdtable(files);
 920                 if (i >= fdt->max_fds)
 921                         break;
 922                 set = fdt->close_on_exec->fds_bits[j];
 923                 if (!set)
 924                         continue;
 925                 fdt->close_on_exec->fds_bits[j] = 0;
 926                 spin_unlock(&files->file_lock);
 927                 for ( ; set ; i++,set >>= 1) {
 928                         if (set & 1) {
 929                                 sys_close(i);
 930                         }
 931                 }
 932                 spin_lock(&files->file_lock);
 933
 934         }
 935         spin_unlock(&files->file_lock);
 936 }
 937
 938 char *get_task_comm(char *buf, struct task_struct *tsk)
 939 {
 940         /* buf must be at least sizeof(tsk->comm) in size */
 941         task_lock(tsk);
 942         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 943         task_unlock(tsk);
 944         return buf;
 945 }
 946
 947 void set_task_comm(struct task_struct *tsk, char *buf)
 948 {
 949         task_lock(tsk);
 950         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 951         task_unlock(tsk);
 952 }
 953
 954 int flush_old_exec(struct linux_binprm * bprm)
 955 {
 956         char * name;
 957         int i, ch, retval;
 958         char tcomm[sizeof(current->comm)];
 959
 960         /*
 961          * Make sure we have a private signal table and that
 962          * we are unassociated from the previous thread group.
 963          */
 964         retval = de_thread(current);
 965         if (retval)
 966                 goto out;
 967
 968         set_mm_exe_file(bprm->mm, bprm->file);
 969
 970         /*
 971          * Release all of the old mmap stuff
 972          */
 973         retval = exec_mmap(bprm->mm);
 974         if (retval)
 975                 goto out;
 976
 977         bprm->mm = NULL;                /* We're using it now */
 978
 979         /* This is the point of no return */
 980         current->sas_ss_sp = current->sas_ss_size = 0;
 981
 982         if (current_euid() == current_uid() && current_egid() == current_gid())
 983                 set_dumpable(current->mm, 1);
 984         else
 985                 set_dumpable(current->mm, suid_dumpable);
 986
 987         name = bprm->filename;
 988
 989         /* Copies the binary name from after last slash */
 990         for (i=0; (ch = *(name++)) != '\0';) {
 991                 if (ch == '/')
 992                         i = 0; /* overwrite what we wrote */
 993                 else
 994                         if (i < (sizeof(tcomm) - 1))
 995                                 tcomm[i++] = ch;
 996         }
 997         tcomm[i] = '\0';
 998         set_task_comm(current, tcomm);
 999
1000         current->flags &= ~PF_RANDOMIZE;
1001         flush_thread();
1002
1003         /* Set the new mm task size. We have to do that late because it may
1004          * depend on TIF_32BIT which is only updated in flush_thread() on
1005          * some architectures like powerpc
1006          */
1007         current->mm->task_size = TASK_SIZE;
1008
1009         /* install the new credentials */
1010         if (bprm->cred->uid != current_euid() ||
1011             bprm->cred->gid != current_egid()) {
1012                 current->pdeath_signal = 0;
1013         } else if (file_permission(bprm->file, MAY_READ) ||
1014                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1015                 set_dumpable(current->mm, suid_dumpable);
1016         }
1017
1018         current->personality &= ~bprm->per_clear;
1019
1020         /* An exec changes our domain. We are no longer part of the thread
1021            group */
1022
1023         current->self_exec_id++;
1024
1025         flush_signal_handlers(current, 0);
1026         flush_old_files(current->files);
1027
1028         return 0;
1029
1030 out:
1031         return retval;
1032 }
1033
1034 EXPORT_SYMBOL(flush_old_exec);
1035
1036 /*
1037  * install the new credentials for this executable
1038  */
1039 void install_exec_creds(struct linux_binprm *bprm)
1040 {
1041         security_bprm_committing_creds(bprm);
1042
1043         commit_creds(bprm->cred);
1044         bprm->cred = NULL;
1045
1046         /* cred_exec_mutex must be held at least to this point to prevent
1047          * ptrace_attach() from altering our determination of the task's
1048          * credentials; any time after this it may be unlocked */
1049
1050         security_bprm_committed_creds(bprm);
1051 }
1052 EXPORT_SYMBOL(install_exec_creds);
1053
1054 /*
1055  * determine how safe it is to execute the proposed program
1056  * - the caller must hold current->cred_exec_mutex to protect against
1057  *   PTRACE_ATTACH
1058  */
1059 void check_unsafe_exec(struct linux_binprm *bprm)
1060 {
1061         struct task_struct *p = current, *t;
1062         unsigned long flags;
1063         unsigned n_fs, n_sighand;
1064
1065         bprm->unsafe = tracehook_unsafe_exec(p);
1066
1067         n_fs = 1;
1068         n_sighand = 1;
1069         lock_task_sighand(p, &flags);
1070         for (t = next_thread(p); t != p; t = next_thread(t)) {
1071                 if (t->fs == p->fs)
1072                         n_fs++;
1073                 n_sighand++;
1074         }
1075
1076         if (atomic_read(&p->fs->count) > n_fs ||
1077             atomic_read(&p->sighand->count) > n_sighand)
1078                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1079
1080         unlock_task_sighand(p, &flags);
1081 }
1082
1083 /*
1084  * Fill the binprm structure from the inode.
1085  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1086  *
1087  * This may be called multiple times for binary chains (scripts for example).
1088  */
1089 int prepare_binprm(struct linux_binprm *bprm)
1090 {
1091         umode_t mode;
1092         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1093         int retval;
1094
1095         mode = inode->i_mode;
1096         if (bprm->file->f_op == NULL)
1097                 return -EACCES;
1098
1099         /* clear any previous set[ug]id data from a previous binary */
1100         bprm->cred->euid = current_euid();
1101         bprm->cred->egid = current_egid();
1102
1103         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1104                 /* Set-uid? */
1105                 if (mode & S_ISUID) {
1106                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1107                         bprm->cred->euid = inode->i_uid;
1108                 }
1109
1110                 /* Set-gid? */
1111                 /*
1112                  * If setgid is set but no group execute bit then this
1113                  * is a candidate for mandatory locking, not a setgid
1114                  * executable.
1115                  */
1116                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1117                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1118                         bprm->cred->egid = inode->i_gid;
1119                 }
1120         }
1121
1122         /* fill in binprm security blob */
1123         retval = security_bprm_set_creds(bprm);
1124         if (retval)
1125                 return retval;
1126         bprm->cred_prepared = 1;
1127
1128         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1129         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1130 }
1131
1132 EXPORT_SYMBOL(prepare_binprm);
1133
1134 /*
1135  * Arguments are '\0' separated strings found at the location bprm->p
1136  * points to; chop off the first by relocating brpm->p to right after
1137  * the first '\0' encountered.
1138  */
1139 int remove_arg_zero(struct linux_binprm *bprm)
1140 {
1141         int ret = 0;
1142         unsigned long offset;
1143         char *kaddr;
1144         struct page *page;
1145
1146         if (!bprm->argc)
1147                 return 0;
1148
1149         do {
1150                 offset = bprm->p & ~PAGE_MASK;
1151                 page = get_arg_page(bprm, bprm->p, 0);
1152                 if (!page) {
1153                         ret = -EFAULT;
1154                         goto out;
1155                 }
1156                 kaddr = kmap_atomic(page, KM_USER0);
1157
1158                 for (; offset < PAGE_SIZE && kaddr[offset];
1159                                 offset++, bprm->p++)
1160                         ;
1161
1162                 kunmap_atomic(kaddr, KM_USER0);
1163                 put_arg_page(page);
1164
1165                 if (offset == PAGE_SIZE)
1166                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1167         } while (offset == PAGE_SIZE);
1168
1169         bprm->p++;
1170         bprm->argc--;
1171         ret = 0;
1172
1173 out:
1174         return ret;
1175 }
1176 EXPORT_SYMBOL(remove_arg_zero);
1177
1178 /*
1179  * cycle the list of binary formats handler, until one recognizes the image
1180  */
1181 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1182 {
1183         unsigned int depth = bprm->recursion_depth;
1184         int try,retval;
1185         struct linux_binfmt *fmt;
1186
1187         retval = security_bprm_check(bprm);
1188         if (retval)
1189                 return retval;
1190         retval = ima_bprm_check(bprm);
1191         if (retval)
1192                 return retval;
1193
1194         /* kernel module loader fixup */
1195         /* so we don't try to load run modprobe in kernel space. */
1196         set_fs(USER_DS);
1197
1198         retval = audit_bprm(bprm);
1199         if (retval)
1200                 return retval;
1201
1202         retval = -ENOENT;
1203         for (try=0; try<2; try++) {
1204                 read_lock(&binfmt_lock);
1205                 list_for_each_entry(fmt, &formats, lh) {
1206                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1207                         if (!fn)
1208                                 continue;
1209                         if (!try_module_get(fmt->module))
1210                                 continue;
1211                         read_unlock(&binfmt_lock);
1212                         retval = fn(bprm, regs);
1213                         /*
1214                          * Restore the depth counter to its starting value
1215                          * in this call, so we don't have to rely on every
1216                          * load_binary function to restore it on return.
1217                          */
1218                         bprm->recursion_depth = depth;
1219                         if (retval >= 0) {
1220                                 if (depth == 0)
1221                                         tracehook_report_exec(fmt, bprm, regs);
1222                                 put_binfmt(fmt);
1223                                 allow_write_access(bprm->file);
1224                                 if (bprm->file)
1225                                         fput(bprm->file);
1226                                 bprm->file = NULL;
1227                                 current->did_exec = 1;
1228                                 proc_exec_connector(current);
1229                                 return retval;
1230                         }
1231                         read_lock(&binfmt_lock);
1232                         put_binfmt(fmt);
1233                         if (retval != -ENOEXEC || bprm->mm == NULL)
1234                                 break;
1235                         if (!bprm->file) {
1236                                 read_unlock(&binfmt_lock);
1237                                 return retval;
1238                         }
1239                 }
1240                 read_unlock(&binfmt_lock);
1241                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1242                         break;
1243 #ifdef CONFIG_MODULES
1244                 } else {
1245 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1246                         if (printable(bprm->buf[0]) &&
1247                             printable(bprm->buf[1]) &&
1248                             printable(bprm->buf[2]) &&
1249                             printable(bprm->buf[3]))
1250                                 break; /* -ENOEXEC */
1251                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1252 #endif
1253                 }
1254         }
1255         return retval;
1256 }
1257
1258 EXPORT_SYMBOL(search_binary_handler);
1259
1260 void free_bprm(struct linux_binprm *bprm)
1261 {
1262         free_arg_pages(bprm);
1263         if (bprm->cred)
1264                 abort_creds(bprm->cred);
1265         kfree(bprm);
1266 }
1267
1268 /*
1269  * sys_execve() executes a new program.
1270  */
1271 int do_execve(char * filename,
1272         char __user *__user *argv,
1273         char __user *__user *envp,
1274         struct pt_regs * regs)
1275 {
1276         struct linux_binprm *bprm;
1277         struct file *file;
1278         struct files_struct *displaced;
1279         int retval;
1280
1281         retval = unshare_files(&displaced);
1282         if (retval)
1283                 goto out_ret;
1284
1285         retval = -ENOMEM;
1286         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1287         if (!bprm)
1288                 goto out_files;
1289
1290         retval = mutex_lock_interruptible(&current->cred_exec_mutex);
1291         if (retval < 0)
1292                 goto out_free;
1293         current->in_execve = 1;
1294
1295         retval = -ENOMEM;
1296         bprm->cred = prepare_exec_creds();
1297         if (!bprm->cred)
1298                 goto out_unlock;
1299         check_unsafe_exec(bprm);
1300
1301         file = open_exec(filename);
1302         retval = PTR_ERR(file);
1303         if (IS_ERR(file))
1304                 goto out_unlock;
1305
1306         sched_exec();
1307
1308         bprm->file = file;
1309         bprm->filename = filename;
1310         bprm->interp = filename;
1311
1312         retval = bprm_mm_init(bprm);
1313         if (retval)
1314                 goto out_file;
1315
1316         bprm->argc = count(argv, MAX_ARG_STRINGS);
1317         if ((retval = bprm->argc) < 0)
1318                 goto out;
1319
1320         bprm->envc = count(envp, MAX_ARG_STRINGS);
1321         if ((retval = bprm->envc) < 0)
1322                 goto out;
1323
1324         retval = prepare_binprm(bprm);
1325         if (retval < 0)
1326                 goto out;
1327
1328         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1329         if (retval < 0)
1330                 goto out;
1331
1332         bprm->exec = bprm->p;
1333         retval = copy_strings(bprm->envc, envp, bprm);
1334         if (retval < 0)
1335                 goto out;
1336
1337         retval = copy_strings(bprm->argc, argv, bprm);
1338         if (retval < 0)
1339                 goto out;
1340
1341         current->flags &= ~PF_KTHREAD;
1342         retval = search_binary_handler(bprm,regs);
1343         if (retval < 0)
1344                 goto out;
1345
1346         /* execve succeeded */
1347         current->in_execve = 0;
1348         mutex_unlock(&current->cred_exec_mutex);
1349         acct_update_integrals(current);
1350         free_bprm(bprm);
1351         if (displaced)
1352                 put_files_struct(displaced);
1353         return retval;
1354
1355 out:
1356         if (bprm->mm)
1357                 mmput (bprm->mm);
1358
1359 out_file:
1360         if (bprm->file) {
1361                 allow_write_access(bprm->file);
1362                 fput(bprm->file);
1363         }
1364
1365 out_unlock:
1366         current->in_execve = 0;
1367         mutex_unlock(&current->cred_exec_mutex);
1368
1369 out_free:
1370         free_bprm(bprm);
1371
1372 out_files:
1373         if (displaced)
1374                 reset_files_struct(displaced);
1375 out_ret:
1376         return retval;
1377 }
1378
1379 int set_binfmt(struct linux_binfmt *new)
1380 {
1381         struct linux_binfmt *old = current->binfmt;
1382
1383         if (new) {
1384                 if (!try_module_get(new->module))
1385                         return -1;
1386         }
1387         current->binfmt = new;
1388         if (old)
1389                 module_put(old->module);
1390         return 0;
1391 }
1392
1393 EXPORT_SYMBOL(set_binfmt);
1394
1395 /* format_corename will inspect the pattern parameter, and output a
1396  * name into corename, which must have space for at least
1397  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1398  */
1399 static int format_corename(char *corename, long signr)
1400 {
1401         const struct cred *cred = current_cred();
1402         const char *pat_ptr = core_pattern;
1403         int ispipe = (*pat_ptr == '|');
1404         char *out_ptr = corename;
1405         char *const out_end = corename + CORENAME_MAX_SIZE;
1406         int rc;
1407         int pid_in_pattern = 0;
1408
1409         /* Repeat as long as we have more pattern to process and more output
1410            space */
1411         while (*pat_ptr) {
1412                 if (*pat_ptr != '%') {
1413                         if (out_ptr == out_end)
1414                                 goto out;
1415                         *out_ptr++ = *pat_ptr++;
1416                 } else {
1417                         switch (*++pat_ptr) {
1418                         case 0:
1419                                 goto out;
1420                         /* Double percent, output one percent */
1421                         case '%':
1422                                 if (out_ptr == out_end)
1423                                         goto out;
1424                                 *out_ptr++ = '%';
1425                                 break;
1426                         /* pid */
1427                         case 'p':
1428                                 pid_in_pattern = 1;
1429                                 rc = snprintf(out_ptr, out_end - out_ptr,
1430                                               "%d", task_tgid_vnr(current));
1431                                 if (rc > out_end - out_ptr)
1432                                         goto out;
1433                                 out_ptr += rc;
1434                                 break;
1435                         /* uid */
1436                         case 'u':
1437                                 rc = snprintf(out_ptr, out_end - out_ptr,
1438                                               "%d", cred->uid);
1439                                 if (rc > out_end - out_ptr)
1440                                         goto out;
1441                                 out_ptr += rc;
1442                                 break;
1443                         /* gid */
1444                         case 'g':
1445                                 rc = snprintf(out_ptr, out_end - out_ptr,
1446                                               "%d", cred->gid);
1447                                 if (rc > out_end - out_ptr)
1448                                         goto out;
1449                                 out_ptr += rc;
1450                                 break;
1451                         /* signal that caused the coredump */
1452                         case 's':
1453                                 rc = snprintf(out_ptr, out_end - out_ptr,
1454                                               "%ld", signr);
1455                                 if (rc > out_end - out_ptr)
1456                                         goto out;
1457                                 out_ptr += rc;
1458                                 break;
1459                         /* UNIX time of coredump */
1460                         case 't': {
1461                                 struct timeval tv;
1462                                 do_gettimeofday(&tv);
1463                                 rc = snprintf(out_ptr, out_end - out_ptr,
1464                                               "%lu", tv.tv_sec);
1465                                 if (rc > out_end - out_ptr)
1466                                         goto out;
1467                                 out_ptr += rc;
1468                                 break;
1469                         }
1470                         /* hostname */
1471                         case 'h':
1472                                 down_read(&uts_sem);
1473                                 rc = snprintf(out_ptr, out_end - out_ptr,
1474                                               "%s", utsname()->nodename);
1475                                 up_read(&uts_sem);
1476                                 if (rc > out_end - out_ptr)
1477                                         goto out;
1478                                 out_ptr += rc;
1479                                 break;
1480                         /* executable */
1481                         case 'e':
1482                                 rc = snprintf(out_ptr, out_end - out_ptr,
1483                                               "%s", current->comm);
1484                                 if (rc > out_end - out_ptr)
1485                                         goto out;
1486                                 out_ptr += rc;
1487                                 break;
1488                         /* core limit size */
1489                         case 'c':
1490                                 rc = snprintf(out_ptr, out_end - out_ptr,
1491                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1492                                 if (rc > out_end - out_ptr)
1493                                         goto out;
1494                                 out_ptr += rc;
1495                                 break;
1496                         default:
1497                                 break;
1498                         }
1499                         ++pat_ptr;
1500                 }
1501         }
1502         /* Backward compatibility with core_uses_pid:
1503          *
1504          * If core_pattern does not include a %p (as is the default)
1505          * and core_uses_pid is set, then .%pid will be appended to
1506          * the filename. Do not do this for piped commands. */
1507         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1508                 rc = snprintf(out_ptr, out_end - out_ptr,
1509                               ".%d", task_tgid_vnr(current));
1510                 if (rc > out_end - out_ptr)
1511                         goto out;
1512                 out_ptr += rc;
1513         }
1514 out:
1515         *out_ptr = 0;
1516         return ispipe;
1517 }
1518
1519 static int zap_process(struct task_struct *start)
1520 {
1521         struct task_struct *t;
1522         int nr = 0;
1523
1524         start->signal->flags = SIGNAL_GROUP_EXIT;
1525         start->signal->group_stop_count = 0;
1526
1527         t = start;
1528         do {
1529                 if (t != current && t->mm) {
1530                         sigaddset(&t->pending.signal, SIGKILL);
1531                         signal_wake_up(t, 1);
1532                         nr++;
1533                 }
1534         } while_each_thread(start, t);
1535
1536         return nr;
1537 }
1538
1539 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1540                                 struct core_state *core_state, int exit_code)
1541 {
1542         struct task_struct *g, *p;
1543         unsigned long flags;
1544         int nr = -EAGAIN;
1545
1546         spin_lock_irq(&tsk->sighand->siglock);
1547         if (!signal_group_exit(tsk->signal)) {
1548                 mm->core_state = core_state;
1549                 tsk->signal->group_exit_code = exit_code;
1550                 nr = zap_process(tsk);
1551         }
1552         spin_unlock_irq(&tsk->sighand->siglock);
1553         if (unlikely(nr < 0))
1554                 return nr;
1555
1556         if (atomic_read(&mm->mm_users) == nr + 1)
1557                 goto done;
1558         /*
1559          * We should find and kill all tasks which use this mm, and we should
1560          * count them correctly into ->nr_threads. We don't take tasklist
1561          * lock, but this is safe wrt:
1562          *
1563          * fork:
1564          *      None of sub-threads can fork after zap_process(leader). All
1565          *      processes which were created before this point should be
1566          *      visible to zap_threads() because copy_process() adds the new
1567          *      process to the tail of init_task.tasks list, and lock/unlock
1568          *      of ->siglock provides a memory barrier.
1569          *
1570          * do_exit:
1571          *      The caller holds mm->mmap_sem. This means that the task which
1572          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1573          *      its ->mm.
1574          *
1575          * de_thread:
1576          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1577          *      we must see either old or new leader, this does not matter.
1578          *      However, it can change p->sighand, so lock_task_sighand(p)
1579          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1580          *      it can't fail.
1581          *
1582          *      Note also that "g" can be the old leader with ->mm == NULL
1583          *      and already unhashed and thus removed from ->thread_group.
1584          *      This is OK, __unhash_process()->list_del_rcu() does not
1585          *      clear the ->next pointer, we will find the new leader via
1586          *      next_thread().
1587          */
1588         rcu_read_lock();
1589         for_each_process(g) {
1590                 if (g == tsk->group_leader)
1591                         continue;
1592                 if (g->flags & PF_KTHREAD)
1593                         continue;
1594                 p = g;
1595                 do {
1596                         if (p->mm) {
1597                                 if (unlikely(p->mm == mm)) {
1598                                         lock_task_sighand(p, &flags);
1599                                         nr += zap_process(p);
1600                                         unlock_task_sighand(p, &flags);
1601                                 }
1602                                 break;
1603                         }
1604                 } while_each_thread(g, p);
1605         }
1606         rcu_read_unlock();
1607 done:
1608         atomic_set(&core_state->nr_threads, nr);
1609         return nr;
1610 }
1611
1612 static int coredump_wait(int exit_code, struct core_state *core_state)
1613 {
1614         struct task_struct *tsk = current;
1615         struct mm_struct *mm = tsk->mm;
1616         struct completion *vfork_done;
1617         int core_waiters;
1618
1619         init_completion(&core_state->startup);
1620         core_state->dumper.task = tsk;
1621         core_state->dumper.next = NULL;
1622         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1623         up_write(&mm->mmap_sem);
1624
1625         if (unlikely(core_waiters < 0))
1626                 goto fail;
1627
1628         /*
1629          * Make sure nobody is waiting for us to release the VM,
1630          * otherwise we can deadlock when we wait on each other
1631          */
1632         vfork_done = tsk->vfork_done;
1633         if (vfork_done) {
1634                 tsk->vfork_done = NULL;
1635                 complete(vfork_done);
1636         }
1637
1638         if (core_waiters)
1639                 wait_for_completion(&core_state->startup);
1640 fail:
1641         return core_waiters;
1642 }
1643
1644 static void coredump_finish(struct mm_struct *mm)
1645 {
1646         struct core_thread *curr, *next;
1647         struct task_struct *task;
1648
1649         next = mm->core_state->dumper.next;
1650         while ((curr = next) != NULL) {
1651                 next = curr->next;
1652                 task = curr->task;
1653                 /*
1654                  * see exit_mm(), curr->task must not see
1655                  * ->task == NULL before we read ->next.
1656                  */
1657                 smp_mb();
1658                 curr->task = NULL;
1659                 wake_up_process(task);
1660         }
1661
1662         mm->core_state = NULL;
1663 }
1664
1665 /*
1666  * set_dumpable converts traditional three-value dumpable to two flags and
1667  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1668  * these bits are not changed atomically.  So get_dumpable can observe the
1669  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1670  * return either old dumpable or new one by paying attention to the order of
1671  * modifying the bits.
1672  *
1673  * dumpable |   mm->flags (binary)
1674  * old  new | initial interim  final
1675  * ---------+-----------------------
1676  *  0    1  |   00      01      01
1677  *  0    2  |   00      10(*)   11
1678  *  1    0  |   01      00      00
1679  *  1    2  |   01      11      11
1680  *  2    0  |   11      10(*)   00
1681  *  2    1  |   11      11      01
1682  *
1683  * (*) get_dumpable regards interim value of 10 as 11.
1684  */
1685 void set_dumpable(struct mm_struct *mm, int value)
1686 {
1687         switch (value) {
1688         case 0:
1689                 clear_bit(MMF_DUMPABLE, &mm->flags);
1690                 smp_wmb();
1691                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1692                 break;
1693         case 1:
1694                 set_bit(MMF_DUMPABLE, &mm->flags);
1695                 smp_wmb();
1696                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1697                 break;
1698         case 2:
1699                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1700                 smp_wmb();
1701                 set_bit(MMF_DUMPABLE, &mm->flags);
1702                 break;
1703         }
1704 }
1705
1706 int get_dumpable(struct mm_struct *mm)
1707 {
1708         int ret;
1709
1710         ret = mm->flags & 0x3;
1711         return (ret >= 2) ? 2 : ret;
1712 }
1713
1714 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1715 {
1716         struct core_state core_state;
1717         char corename[CORENAME_MAX_SIZE + 1];
1718         struct mm_struct *mm = current->mm;
1719         struct linux_binfmt * binfmt;
1720         struct inode * inode;
1721         struct file * file;
1722         const struct cred *old_cred;
1723         struct cred *cred;
1724         int retval = 0;
1725         int flag = 0;
1726         int ispipe = 0;
1727         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1728         char **helper_argv = NULL;
1729         int helper_argc = 0;
1730         char *delimit;
1731
1732         audit_core_dumps(signr);
1733
1734         binfmt = current->binfmt;
1735         if (!binfmt || !binfmt->core_dump)
1736                 goto fail;
1737
1738         cred = prepare_creds();
1739         if (!cred) {
1740                 retval = -ENOMEM;
1741                 goto fail;
1742         }
1743
1744         down_write(&mm->mmap_sem);
1745         /*
1746          * If another thread got here first, or we are not dumpable, bail out.
1747          */
1748         if (mm->core_state || !get_dumpable(mm)) {
1749                 up_write(&mm->mmap_sem);
1750                 put_cred(cred);
1751                 goto fail;
1752         }
1753
1754         /*
1755          *      We cannot trust fsuid as being the "true" uid of the
1756          *      process nor do we know its entire history. We only know it
1757          *      was tainted so we dump it as root in mode 2.
1758          */
1759         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1760                 flag = O_EXCL;          /* Stop rewrite attacks */
1761                 cred->fsuid = 0;        /* Dump root private */
1762         }
1763
1764         retval = coredump_wait(exit_code, &core_state);
1765         if (retval < 0) {
1766                 put_cred(cred);
1767                 goto fail;
1768         }
1769
1770         old_cred = override_creds(cred);
1771
1772         /*
1773          * Clear any false indication of pending signals that might
1774          * be seen by the filesystem code called to write the core file.
1775          */
1776         clear_thread_flag(TIF_SIGPENDING);
1777
1778         /*
1779          * lock_kernel() because format_corename() is controlled by sysctl, which
1780          * uses lock_kernel()
1781          */
1782         lock_kernel();
1783         ispipe = format_corename(corename, signr);
1784         unlock_kernel();
1785         /*
1786          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1787          * to a pipe.  Since we're not writing directly to the filesystem
1788          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1789          * created unless the pipe reader choses to write out the core file
1790          * at which point file size limits and permissions will be imposed
1791          * as it does with any other process
1792          */
1793         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1794                 goto fail_unlock;
1795
1796         if (ispipe) {
1797                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1798                 if (!helper_argv) {
1799                         printk(KERN_WARNING "%s failed to allocate memory\n",
1800                                __func__);
1801                         goto fail_unlock;
1802                 }
1803                 /* Terminate the string before the first option */
1804                 delimit = strchr(corename, ' ');
1805                 if (delimit)
1806                         *delimit = '\0';
1807                 delimit = strrchr(helper_argv[0], '/');
1808                 if (delimit)
1809                         delimit++;
1810                 else
1811                         delimit = helper_argv[0];
1812                 if (!strcmp(delimit, current->comm)) {
1813                         printk(KERN_NOTICE "Recursive core dump detected, "
1814                                         "aborting\n");
1815                         goto fail_unlock;
1816                 }
1817
1818                 core_limit = RLIM_INFINITY;
1819
1820                 /* SIGPIPE can happen, but it's just never processed */
1821                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1822                                 &file)) {
1823                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1824                                corename);
1825                         goto fail_unlock;
1826                 }
1827         } else
1828                 file = filp_open(corename,
1829                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1830                                  0600);
1831         if (IS_ERR(file))
1832                 goto fail_unlock;
1833         inode = file->f_path.dentry->d_inode;
1834         if (inode->i_nlink > 1)
1835                 goto close_fail;        /* multiple links - don't dump */
1836         if (!ispipe && d_unhashed(file->f_path.dentry))
1837                 goto close_fail;
1838
1839         /* AK: actually i see no reason to not allow this for named pipes etc.,
1840            but keep the previous behaviour for now. */
1841         if (!ispipe && !S_ISREG(inode->i_mode))
1842                 goto close_fail;
1843         /*
1844          * Dont allow local users get cute and trick others to coredump
1845          * into their pre-created files:
1846          */
1847         if (inode->i_uid != current_fsuid())
1848                 goto close_fail;
1849         if (!file->f_op)
1850                 goto close_fail;
1851         if (!file->f_op->write)
1852                 goto close_fail;
1853         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1854                 goto close_fail;
1855
1856         retval = binfmt->core_dump(signr, regs, file, core_limit);
1857
1858         if (retval)
1859                 current->signal->group_exit_code |= 0x80;
1860 close_fail:
1861         filp_close(file, NULL);
1862 fail_unlock:
1863         if (helper_argv)
1864                 argv_free(helper_argv);
1865
1866         revert_creds(old_cred);
1867         put_cred(cred);
1868         coredump_finish(mm);
1869 fail:
1870         return;
1871 }