SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 #include <linux/fs_struct.h>
  57
  58 #include <asm/uaccess.h>
  59 #include <asm/mmu_context.h>
  60 #include <asm/tlb.h>
  61 #include "internal.h"
  62
  63 int core_uses_pid;
  64 char core_pattern[CORENAME_MAX_SIZE] = "core";
  65 int suid_dumpable = 0;
  66
  67 /* The maximal length of core_pattern is also specified in sysctl.c */
  68
  69 static LIST_HEAD(formats);
  70 static DEFINE_RWLOCK(binfmt_lock);
  71
  72 int __register_binfmt(struct linux_binfmt * fmt, int insert)
  73 {
  74         if (!fmt)
  75                 return -EINVAL;
  76         write_lock(&binfmt_lock);
  77         insert ? list_add(&fmt->lh, &formats) :
  78                  list_add_tail(&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 SYSCALL_DEFINE1(uselib, const char __user *, library)
 106 {
 107         struct file *file;
 108         struct nameidata nd;
 109         char *tmp = getname(library);
 110         int error = PTR_ERR(tmp);
 111
 112         if (!IS_ERR(tmp)) {
 113                 error = path_lookup_open(AT_FDCWD, tmp,
 114                                          LOOKUP_FOLLOW, &nd,
 115                                          FMODE_READ|FMODE_EXEC);
 116                 putname(tmp);
 117         }
 118         if (error)
 119                 goto out;
 120
 121         error = -EINVAL;
 122         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 123                 goto exit;
 124
 125         error = -EACCES;
 126         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 127                 goto exit;
 128
 129         error = may_open(&nd.path, MAY_READ | MAY_EXEC | MAY_OPEN, 0);
 130         if (error)
 131                 goto exit;
 132
 133         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 134         error = PTR_ERR(file);
 135         if (IS_ERR(file))
 136                 goto out;
 137
 138         fsnotify_open(file->f_path.dentry);
 139
 140         error = -ENOEXEC;
 141         if(file->f_op) {
 142                 struct linux_binfmt * fmt;
 143
 144                 read_lock(&binfmt_lock);
 145                 list_for_each_entry(fmt, &formats, lh) {
 146                         if (!fmt->load_shlib)
 147                                 continue;
 148                         if (!try_module_get(fmt->module))
 149                                 continue;
 150                         read_unlock(&binfmt_lock);
 151                         error = fmt->load_shlib(file);
 152                         read_lock(&binfmt_lock);
 153                         put_binfmt(fmt);
 154                         if (error != -ENOEXEC)
 155                                 break;
 156                 }
 157                 read_unlock(&binfmt_lock);
 158         }
 159         fput(file);
 160 out:
 161         return error;
 162 exit:
 163         release_open_intent(&nd);
 164         path_put(&nd.path);
 165         goto out;
 166 }
 167
 168 #ifdef CONFIG_MMU
 169
 170 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 171                 int write)
 172 {
 173         struct page *page;
 174         int ret;
 175
 176 #ifdef CONFIG_STACK_GROWSUP
 177         if (write) {
 178                 ret = expand_stack_downwards(bprm->vma, pos);
 179                 if (ret < 0)
 180                         return NULL;
 181         }
 182 #endif
 183         ret = get_user_pages(current, bprm->mm, pos,
 184                         1, write, 1, &page, NULL);
 185         if (ret <= 0)
 186                 return NULL;
 187
 188         if (write) {
 189                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 190                 struct rlimit *rlim;
 191
 192                 /*
 193                  * We've historically supported up to 32 pages (ARG_MAX)
 194                  * of argument strings even with small stacks
 195                  */
 196                 if (size <= ARG_MAX)
 197                         return page;
 198
 199                 /*
 200                  * Limit to 1/4-th the stack size for the argv+env strings.
 201                  * This ensures that:
 202                  *  - the remaining binfmt code will not run out of stack space,
 203                  *  - the program will have a reasonable amount of stack left
 204                  *    to work from.
 205                  */
 206                 rlim = current->signal->rlim;
 207                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 208                         put_page(page);
 209                         return NULL;
 210                 }
 211         }
 212
 213         return page;
 214 }
 215
 216 static void put_arg_page(struct page *page)
 217 {
 218         put_page(page);
 219 }
 220
 221 static void free_arg_page(struct linux_binprm *bprm, int i)
 222 {
 223 }
 224
 225 static void free_arg_pages(struct linux_binprm *bprm)
 226 {
 227 }
 228
 229 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 230                 struct page *page)
 231 {
 232         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 233 }
 234
 235 static int __bprm_mm_init(struct linux_binprm *bprm)
 236 {
 237         int err;
 238         struct vm_area_struct *vma = NULL;
 239         struct mm_struct *mm = bprm->mm;
 240
 241         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 242         if (!vma)
 243                 return -ENOMEM;
 244
 245         down_write(&mm->mmap_sem);
 246         vma->vm_mm = mm;
 247
 248         /*
 249          * Place the stack at the largest stack address the architecture
 250          * supports. Later, we'll move this to an appropriate place. We don't
 251          * use STACK_TOP because that can depend on attributes which aren't
 252          * configured yet.
 253          */
 254         vma->vm_end = STACK_TOP_MAX;
 255         vma->vm_start = vma->vm_end - PAGE_SIZE;
 256         vma->vm_flags = VM_STACK_FLAGS;
 257         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 258         err = insert_vm_struct(mm, vma);
 259         if (err)
 260                 goto err;
 261
 262         mm->stack_vm = mm->total_vm = 1;
 263         up_write(&mm->mmap_sem);
 264         bprm->p = vma->vm_end - sizeof(void *);
 265         return 0;
 266 err:
 267         up_write(&mm->mmap_sem);
 268         bprm->vma = NULL;
 269         kmem_cache_free(vm_area_cachep, vma);
 270         return err;
 271 }
 272
 273 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 274 {
 275         return len <= MAX_ARG_STRLEN;
 276 }
 277
 278 #else
 279
 280 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 281                 int write)
 282 {
 283         struct page *page;
 284
 285         page = bprm->page[pos / PAGE_SIZE];
 286         if (!page && write) {
 287                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 288                 if (!page)
 289                         return NULL;
 290                 bprm->page[pos / PAGE_SIZE] = page;
 291         }
 292
 293         return page;
 294 }
 295
 296 static void put_arg_page(struct page *page)
 297 {
 298 }
 299
 300 static void free_arg_page(struct linux_binprm *bprm, int i)
 301 {
 302         if (bprm->page[i]) {
 303                 __free_page(bprm->page[i]);
 304                 bprm->page[i] = NULL;
 305         }
 306 }
 307
 308 static void free_arg_pages(struct linux_binprm *bprm)
 309 {
 310         int i;
 311
 312         for (i = 0; i < MAX_ARG_PAGES; i++)
 313                 free_arg_page(bprm, i);
 314 }
 315
 316 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 317                 struct page *page)
 318 {
 319 }
 320
 321 static int __bprm_mm_init(struct linux_binprm *bprm)
 322 {
 323         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 324         return 0;
 325 }
 326
 327 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 328 {
 329         return len <= bprm->p;
 330 }
 331
 332 #endif /* CONFIG_MMU */
 333
 334 /*
 335  * Create a new mm_struct and populate it with a temporary stack
 336  * vm_area_struct.  We don't have enough context at this point to set the stack
 337  * flags, permissions, and offset, so we use temporary values.  We'll update
 338  * them later in setup_arg_pages().
 339  */
 340 int bprm_mm_init(struct linux_binprm *bprm)
 341 {
 342         int err;
 343         struct mm_struct *mm = NULL;
 344
 345         bprm->mm = mm = mm_alloc();
 346         err = -ENOMEM;
 347         if (!mm)
 348                 goto err;
 349
 350         err = init_new_context(current, mm);
 351         if (err)
 352                 goto err;
 353
 354         err = __bprm_mm_init(bprm);
 355         if (err)
 356                 goto err;
 357
 358         return 0;
 359
 360 err:
 361         if (mm) {
 362                 bprm->mm = NULL;
 363                 mmdrop(mm);
 364         }
 365
 366         return err;
 367 }
 368
 369 /*
 370  * count() counts the number of strings in array ARGV.
 371  */
 372 static int count(char __user * __user * argv, int max)
 373 {
 374         int i = 0;
 375
 376         if (argv != NULL) {
 377                 for (;;) {
 378                         char __user * p;
 379
 380                         if (get_user(p, argv))
 381                                 return -EFAULT;
 382                         if (!p)
 383                                 break;
 384                         argv++;
 385                         if (i++ >= max)
 386                                 return -E2BIG;
 387                         cond_resched();
 388                 }
 389         }
 390         return i;
 391 }
 392
 393 /*
 394  * 'copy_strings()' copies argument/environment strings from the old
 395  * processes's memory to the new process's stack.  The call to get_user_pages()
 396  * ensures the destination page is created and not swapped out.
 397  */
 398 static int copy_strings(int argc, char __user * __user * argv,
 399                         struct linux_binprm *bprm)
 400 {
 401         struct page *kmapped_page = NULL;
 402         char *kaddr = NULL;
 403         unsigned long kpos = 0;
 404         int ret;
 405
 406         while (argc-- > 0) {
 407                 char __user *str;
 408                 int len;
 409                 unsigned long pos;
 410
 411                 if (get_user(str, argv+argc) ||
 412                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 413                         ret = -EFAULT;
 414                         goto out;
 415                 }
 416
 417                 if (!valid_arg_len(bprm, len)) {
 418                         ret = -E2BIG;
 419                         goto out;
 420                 }
 421
 422                 /* We're going to work our way backwords. */
 423                 pos = bprm->p;
 424                 str += len;
 425                 bprm->p -= len;
 426
 427                 while (len > 0) {
 428                         int offset, bytes_to_copy;
 429
 430                         offset = pos % PAGE_SIZE;
 431                         if (offset == 0)
 432                                 offset = PAGE_SIZE;
 433
 434                         bytes_to_copy = offset;
 435                         if (bytes_to_copy > len)
 436                                 bytes_to_copy = len;
 437
 438                         offset -= bytes_to_copy;
 439                         pos -= bytes_to_copy;
 440                         str -= bytes_to_copy;
 441                         len -= bytes_to_copy;
 442
 443                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 444                                 struct page *page;
 445
 446                                 page = get_arg_page(bprm, pos, 1);
 447                                 if (!page) {
 448                                         ret = -E2BIG;
 449                                         goto out;
 450                                 }
 451
 452                                 if (kmapped_page) {
 453                                         flush_kernel_dcache_page(kmapped_page);
 454                                         kunmap(kmapped_page);
 455                                         put_arg_page(kmapped_page);
 456                                 }
 457                                 kmapped_page = page;
 458                                 kaddr = kmap(kmapped_page);
 459                                 kpos = pos & PAGE_MASK;
 460                                 flush_arg_page(bprm, kpos, kmapped_page);
 461                         }
 462                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 463                                 ret = -EFAULT;
 464                                 goto out;
 465                         }
 466                 }
 467         }
 468         ret = 0;
 469 out:
 470         if (kmapped_page) {
 471                 flush_kernel_dcache_page(kmapped_page);
 472                 kunmap(kmapped_page);
 473                 put_arg_page(kmapped_page);
 474         }
 475         return ret;
 476 }
 477
 478 /*
 479  * Like copy_strings, but get argv and its values from kernel memory.
 480  */
 481 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 482 {
 483         int r;
 484         mm_segment_t oldfs = get_fs();
 485         set_fs(KERNEL_DS);
 486         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 487         set_fs(oldfs);
 488         return r;
 489 }
 490 EXPORT_SYMBOL(copy_strings_kernel);
 491
 492 #ifdef CONFIG_MMU
 493
 494 /*
 495  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 496  * the binfmt code determines where the new stack should reside, we shift it to
 497  * its final location.  The process proceeds as follows:
 498  *
 499  * 1) Use shift to calculate the new vma endpoints.
 500  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 501  *    arguments passed to subsequent functions are consistent.
 502  * 3) Move vma's page tables to the new range.
 503  * 4) Free up any cleared pgd range.
 504  * 5) Shrink the vma to cover only the new range.
 505  */
 506 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 507 {
 508         struct mm_struct *mm = vma->vm_mm;
 509         unsigned long old_start = vma->vm_start;
 510         unsigned long old_end = vma->vm_end;
 511         unsigned long length = old_end - old_start;
 512         unsigned long new_start = old_start - shift;
 513         unsigned long new_end = old_end - shift;
 514         struct mmu_gather *tlb;
 515
 516         BUG_ON(new_start > new_end);
 517
 518         /*
 519          * ensure there are no vmas between where we want to go
 520          * and where we are
 521          */
 522         if (vma != find_vma(mm, new_start))
 523                 return -EFAULT;
 524
 525         /*
 526          * cover the whole range: [new_start, old_end)
 527          */
 528         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 529
 530         /*
 531          * move the page tables downwards, on failure we rely on
 532          * process cleanup to remove whatever mess we made.
 533          */
 534         if (length != move_page_tables(vma, old_start,
 535                                        vma, new_start, length))
 536                 return -ENOMEM;
 537
 538         lru_add_drain();
 539         tlb = tlb_gather_mmu(mm, 0);
 540         if (new_end > old_start) {
 541                 /*
 542                  * when the old and new regions overlap clear from new_end.
 543                  */
 544                 free_pgd_range(tlb, new_end, old_end, new_end,
 545                         vma->vm_next ? vma->vm_next->vm_start : 0);
 546         } else {
 547                 /*
 548                  * otherwise, clean from old_start; this is done to not touch
 549                  * the address space in [new_end, old_start) some architectures
 550                  * have constraints on va-space that make this illegal (IA64) -
 551                  * for the others its just a little faster.
 552                  */
 553                 free_pgd_range(tlb, old_start, old_end, new_end,
 554                         vma->vm_next ? vma->vm_next->vm_start : 0);
 555         }
 556         tlb_finish_mmu(tlb, new_end, old_end);
 557
 558         /*
 559          * shrink the vma to just the new range.
 560          */
 561         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 562
 563         return 0;
 564 }
 565
 566 #define EXTRA_STACK_VM_PAGES    20      /* random */
 567
 568 /*
 569  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 570  * the stack is optionally relocated, and some extra space is added.
 571  */
 572 int setup_arg_pages(struct linux_binprm *bprm,
 573                     unsigned long stack_top,
 574                     int executable_stack)
 575 {
 576         unsigned long ret;
 577         unsigned long stack_shift;
 578         struct mm_struct *mm = current->mm;
 579         struct vm_area_struct *vma = bprm->vma;
 580         struct vm_area_struct *prev = NULL;
 581         unsigned long vm_flags;
 582         unsigned long stack_base;
 583
 584 #ifdef CONFIG_STACK_GROWSUP
 585         /* Limit stack size to 1GB */
 586         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 587         if (stack_base > (1 << 30))
 588                 stack_base = 1 << 30;
 589
 590         /* Make sure we didn't let the argument array grow too large. */
 591         if (vma->vm_end - vma->vm_start > stack_base)
 592                 return -ENOMEM;
 593
 594         stack_base = PAGE_ALIGN(stack_top - stack_base);
 595
 596         stack_shift = vma->vm_start - stack_base;
 597         mm->arg_start = bprm->p - stack_shift;
 598         bprm->p = vma->vm_end - stack_shift;
 599 #else
 600         stack_top = arch_align_stack(stack_top);
 601         stack_top = PAGE_ALIGN(stack_top);
 602         stack_shift = vma->vm_end - stack_top;
 603
 604         bprm->p -= stack_shift;
 605         mm->arg_start = bprm->p;
 606 #endif
 607
 608         if (bprm->loader)
 609                 bprm->loader -= stack_shift;
 610         bprm->exec -= stack_shift;
 611
 612         down_write(&mm->mmap_sem);
 613         vm_flags = VM_STACK_FLAGS;
 614
 615         /*
 616          * Adjust stack execute permissions; explicitly enable for
 617          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 618          * (arch default) otherwise.
 619          */
 620         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 621                 vm_flags |= VM_EXEC;
 622         else if (executable_stack == EXSTACK_DISABLE_X)
 623                 vm_flags &= ~VM_EXEC;
 624         vm_flags |= mm->def_flags;
 625
 626         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 627                         vm_flags);
 628         if (ret)
 629                 goto out_unlock;
 630         BUG_ON(prev != vma);
 631
 632         /* Move stack pages down in memory. */
 633         if (stack_shift) {
 634                 ret = shift_arg_pages(vma, stack_shift);
 635                 if (ret) {
 636                         up_write(&mm->mmap_sem);
 637                         return ret;
 638                 }
 639         }
 640
 641 #ifdef CONFIG_STACK_GROWSUP
 642         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 643 #else
 644         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 645 #endif
 646         ret = expand_stack(vma, stack_base);
 647         if (ret)
 648                 ret = -EFAULT;
 649
 650 out_unlock:
 651         up_write(&mm->mmap_sem);
 652         return 0;
 653 }
 654 EXPORT_SYMBOL(setup_arg_pages);
 655
 656 #endif /* CONFIG_MMU */
 657
 658 struct file *open_exec(const char *name)
 659 {
 660         struct nameidata nd;
 661         struct file *file;
 662         int err;
 663
 664         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
 665                                 FMODE_READ|FMODE_EXEC);
 666         if (err)
 667                 goto out;
 668
 669         err = -EACCES;
 670         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
 671                 goto out_path_put;
 672
 673         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
 674                 goto out_path_put;
 675
 676         err = may_open(&nd.path, MAY_EXEC | MAY_OPEN, 0);
 677         if (err)
 678                 goto out_path_put;
 679
 680         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
 681         if (IS_ERR(file))
 682                 return file;
 683
 684         fsnotify_open(file->f_path.dentry);
 685
 686         err = deny_write_access(file);
 687         if (err) {
 688                 fput(file);
 689                 goto out;
 690         }
 691
 692         return file;
 693
 694  out_path_put:
 695         release_open_intent(&nd);
 696         path_put(&nd.path);
 697  out:
 698         return ERR_PTR(err);
 699 }
 700 EXPORT_SYMBOL(open_exec);
 701
 702 int kernel_read(struct file *file, unsigned long offset,
 703         char *addr, unsigned long count)
 704 {
 705         mm_segment_t old_fs;
 706         loff_t pos = offset;
 707         int result;
 708
 709         old_fs = get_fs();
 710         set_fs(get_ds());
 711         /* The cast to a user pointer is valid due to the set_fs() */
 712         result = vfs_read(file, (void __user *)addr, count, &pos);
 713         set_fs(old_fs);
 714         return result;
 715 }
 716
 717 EXPORT_SYMBOL(kernel_read);
 718
 719 static int exec_mmap(struct mm_struct *mm)
 720 {
 721         struct task_struct *tsk;
 722         struct mm_struct * old_mm, *active_mm;
 723
 724         /* Notify parent that we're no longer interested in the old VM */
 725         tsk = current;
 726         old_mm = current->mm;
 727         mm_release(tsk, old_mm);
 728
 729         if (old_mm) {
 730                 /*
 731                  * Make sure that if there is a core dump in progress
 732                  * for the old mm, we get out and die instead of going
 733                  * through with the exec.  We must hold mmap_sem around
 734                  * checking core_state and changing tsk->mm.
 735                  */
 736                 down_read(&old_mm->mmap_sem);
 737                 if (unlikely(old_mm->core_state)) {
 738                         up_read(&old_mm->mmap_sem);
 739                         return -EINTR;
 740                 }
 741         }
 742         task_lock(tsk);
 743         active_mm = tsk->active_mm;
 744         tsk->mm = mm;
 745         tsk->active_mm = mm;
 746         activate_mm(active_mm, mm);
 747         task_unlock(tsk);
 748         arch_pick_mmap_layout(mm);
 749         if (old_mm) {
 750                 up_read(&old_mm->mmap_sem);
 751                 BUG_ON(active_mm != old_mm);
 752                 mm_update_next_owner(old_mm);
 753                 mmput(old_mm);
 754                 return 0;
 755         }
 756         mmdrop(active_mm);
 757         return 0;
 758 }
 759
 760 /*
 761  * This function makes sure the current process has its own signal table,
 762  * so that flush_signal_handlers can later reset the handlers without
 763  * disturbing other processes.  (Other processes might share the signal
 764  * table via the CLONE_SIGHAND option to clone().)
 765  */
 766 static int de_thread(struct task_struct *tsk)
 767 {
 768         struct signal_struct *sig = tsk->signal;
 769         struct sighand_struct *oldsighand = tsk->sighand;
 770         spinlock_t *lock = &oldsighand->siglock;
 771         int count;
 772
 773         if (thread_group_empty(tsk))
 774                 goto no_thread_group;
 775
 776         /*
 777          * Kill all other threads in the thread group.
 778          */
 779         spin_lock_irq(lock);
 780         if (signal_group_exit(sig)) {
 781                 /*
 782                  * Another group action in progress, just
 783                  * return so that the signal is processed.
 784                  */
 785                 spin_unlock_irq(lock);
 786                 return -EAGAIN;
 787         }
 788         sig->group_exit_task = tsk;
 789         zap_other_threads(tsk);
 790
 791         /* Account for the thread group leader hanging around: */
 792         count = thread_group_leader(tsk) ? 1 : 2;
 793         sig->notify_count = count;
 794         while (atomic_read(&sig->count) > count) {
 795                 __set_current_state(TASK_UNINTERRUPTIBLE);
 796                 spin_unlock_irq(lock);
 797                 schedule();
 798                 spin_lock_irq(lock);
 799         }
 800         spin_unlock_irq(lock);
 801
 802         /*
 803          * At this point all other threads have exited, all we have to
 804          * do is to wait for the thread group leader to become inactive,
 805          * and to assume its PID:
 806          */
 807         if (!thread_group_leader(tsk)) {
 808                 struct task_struct *leader = tsk->group_leader;
 809
 810                 sig->notify_count = -1; /* for exit_notify() */
 811                 for (;;) {
 812                         write_lock_irq(&tasklist_lock);
 813                         if (likely(leader->exit_state))
 814                                 break;
 815                         __set_current_state(TASK_UNINTERRUPTIBLE);
 816                         write_unlock_irq(&tasklist_lock);
 817                         schedule();
 818                 }
 819
 820                 /*
 821                  * The only record we have of the real-time age of a
 822                  * process, regardless of execs it's done, is start_time.
 823                  * All the past CPU time is accumulated in signal_struct
 824                  * from sister threads now dead.  But in this non-leader
 825                  * exec, nothing survives from the original leader thread,
 826                  * whose birth marks the true age of this process now.
 827                  * When we take on its identity by switching to its PID, we
 828                  * also take its birthdate (always earlier than our own).
 829                  */
 830                 tsk->start_time = leader->start_time;
 831
 832                 BUG_ON(!same_thread_group(leader, tsk));
 833                 BUG_ON(has_group_leader_pid(tsk));
 834                 /*
 835                  * An exec() starts a new thread group with the
 836                  * TGID of the previous thread group. Rehash the
 837                  * two threads with a switched PID, and release
 838                  * the former thread group leader:
 839                  */
 840
 841                 /* Become a process group leader with the old leader's pid.
 842                  * The old leader becomes a thread of the this thread group.
 843                  * Note: The old leader also uses this pid until release_task
 844                  *       is called.  Odd but simple and correct.
 845                  */
 846                 detach_pid(tsk, PIDTYPE_PID);
 847                 tsk->pid = leader->pid;
 848                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 849                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 850                 transfer_pid(leader, tsk, PIDTYPE_SID);
 851                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 852
 853                 tsk->group_leader = tsk;
 854                 leader->group_leader = tsk;
 855
 856                 tsk->exit_signal = SIGCHLD;
 857
 858                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 859                 leader->exit_state = EXIT_DEAD;
 860                 write_unlock_irq(&tasklist_lock);
 861
 862                 release_task(leader);
 863         }
 864
 865         sig->group_exit_task = NULL;
 866         sig->notify_count = 0;
 867
 868 no_thread_group:
 869         exit_itimers(sig);
 870         flush_itimer_signals();
 871
 872         if (atomic_read(&oldsighand->count) != 1) {
 873                 struct sighand_struct *newsighand;
 874                 /*
 875                  * This ->sighand is shared with the CLONE_SIGHAND
 876                  * but not CLONE_THREAD task, switch to the new one.
 877                  */
 878                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 879                 if (!newsighand)
 880                         return -ENOMEM;
 881
 882                 atomic_set(&newsighand->count, 1);
 883                 memcpy(newsighand->action, oldsighand->action,
 884                        sizeof(newsighand->action));
 885
 886                 write_lock_irq(&tasklist_lock);
 887                 spin_lock(&oldsighand->siglock);
 888                 rcu_assign_pointer(tsk->sighand, newsighand);
 889                 spin_unlock(&oldsighand->siglock);
 890                 write_unlock_irq(&tasklist_lock);
 891
 892                 __cleanup_sighand(oldsighand);
 893         }
 894
 895         BUG_ON(!thread_group_leader(tsk));
 896         return 0;
 897 }
 898
 899 /*
 900  * These functions flushes out all traces of the currently running executable
 901  * so that a new one can be started
 902  */
 903 static void flush_old_files(struct files_struct * files)
 904 {
 905         long j = -1;
 906         struct fdtable *fdt;
 907
 908         spin_lock(&files->file_lock);
 909         for (;;) {
 910                 unsigned long set, i;
 911
 912                 j++;
 913                 i = j * __NFDBITS;
 914                 fdt = files_fdtable(files);
 915                 if (i >= fdt->max_fds)
 916                         break;
 917                 set = fdt->close_on_exec->fds_bits[j];
 918                 if (!set)
 919                         continue;
 920                 fdt->close_on_exec->fds_bits[j] = 0;
 921                 spin_unlock(&files->file_lock);
 922                 for ( ; set ; i++,set >>= 1) {
 923                         if (set & 1) {
 924                                 sys_close(i);
 925                         }
 926                 }
 927                 spin_lock(&files->file_lock);
 928
 929         }
 930         spin_unlock(&files->file_lock);
 931 }
 932
 933 char *get_task_comm(char *buf, struct task_struct *tsk)
 934 {
 935         /* buf must be at least sizeof(tsk->comm) in size */
 936         task_lock(tsk);
 937         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 938         task_unlock(tsk);
 939         return buf;
 940 }
 941
 942 void set_task_comm(struct task_struct *tsk, char *buf)
 943 {
 944         task_lock(tsk);
 945         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 946         task_unlock(tsk);
 947 }
 948
 949 int flush_old_exec(struct linux_binprm * bprm)
 950 {
 951         char * name;
 952         int i, ch, retval;
 953         char tcomm[sizeof(current->comm)];
 954
 955         /*
 956          * Make sure we have a private signal table and that
 957          * we are unassociated from the previous thread group.
 958          */
 959         retval = de_thread(current);
 960         if (retval)
 961                 goto out;
 962
 963         set_mm_exe_file(bprm->mm, bprm->file);
 964
 965         /*
 966          * Release all of the old mmap stuff
 967          */
 968         retval = exec_mmap(bprm->mm);
 969         if (retval)
 970                 goto out;
 971
 972         bprm->mm = NULL;                /* We're using it now */
 973
 974         /* This is the point of no return */
 975         current->sas_ss_sp = current->sas_ss_size = 0;
 976
 977         if (current_euid() == current_uid() && current_egid() == current_gid())
 978                 set_dumpable(current->mm, 1);
 979         else
 980                 set_dumpable(current->mm, suid_dumpable);
 981
 982         name = bprm->filename;
 983
 984         /* Copies the binary name from after last slash */
 985         for (i=0; (ch = *(name++)) != '\0';) {
 986                 if (ch == '/')
 987                         i = 0; /* overwrite what we wrote */
 988                 else
 989                         if (i < (sizeof(tcomm) - 1))
 990                                 tcomm[i++] = ch;
 991         }
 992         tcomm[i] = '\0';
 993         set_task_comm(current, tcomm);
 994
 995         current->flags &= ~PF_RANDOMIZE;
 996         flush_thread();
 997
 998         /* Set the new mm task size. We have to do that late because it may
 999          * depend on TIF_32BIT which is only updated in flush_thread() on
1000          * some architectures like powerpc
1001          */
1002         current->mm->task_size = TASK_SIZE;
1003
1004         /* install the new credentials */
1005         if (bprm->cred->uid != current_euid() ||
1006             bprm->cred->gid != current_egid()) {
1007                 current->pdeath_signal = 0;
1008         } else if (file_permission(bprm->file, MAY_READ) ||
1009                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1010                 set_dumpable(current->mm, suid_dumpable);
1011         }
1012
1013         current->personality &= ~bprm->per_clear;
1014
1015         /* An exec changes our domain. We are no longer part of the thread
1016            group */
1017
1018         current->self_exec_id++;
1019
1020         flush_signal_handlers(current, 0);
1021         flush_old_files(current->files);
1022
1023         return 0;
1024
1025 out:
1026         return retval;
1027 }
1028
1029 EXPORT_SYMBOL(flush_old_exec);
1030
1031 /*
1032  * install the new credentials for this executable
1033  */
1034 void install_exec_creds(struct linux_binprm *bprm)
1035 {
1036         security_bprm_committing_creds(bprm);
1037
1038         commit_creds(bprm->cred);
1039         bprm->cred = NULL;
1040
1041         /* cred_exec_mutex must be held at least to this point to prevent
1042          * ptrace_attach() from altering our determination of the task's
1043          * credentials; any time after this it may be unlocked */
1044
1045         security_bprm_committed_creds(bprm);
1046 }
1047 EXPORT_SYMBOL(install_exec_creds);
1048
1049 /*
1050  * determine how safe it is to execute the proposed program
1051  * - the caller must hold current->cred_exec_mutex to protect against
1052  *   PTRACE_ATTACH
1053  */
1054 int check_unsafe_exec(struct linux_binprm *bprm)
1055 {
1056         struct task_struct *p = current, *t;
1057         unsigned n_fs;
1058         int res = 0;
1059
1060         bprm->unsafe = tracehook_unsafe_exec(p);
1061
1062         n_fs = 1;
1063         write_lock(&p->fs->lock);
1064         rcu_read_lock();
1065         for (t = next_thread(p); t != p; t = next_thread(t)) {
1066                 if (t->fs == p->fs)
1067                         n_fs++;
1068         }
1069         rcu_read_unlock();
1070
1071         if (p->fs->users > n_fs) {
1072                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1073         } else {
1074                 res = -EAGAIN;
1075                 if (!p->fs->in_exec) {
1076                         p->fs->in_exec = 1;
1077                         res = 1;
1078                 }
1079         }
1080         write_unlock(&p->fs->lock);
1081
1082         return res;
1083 }
1084
1085 /*
1086  * Fill the binprm structure from the inode.
1087  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1088  *
1089  * This may be called multiple times for binary chains (scripts for example).
1090  */
1091 int prepare_binprm(struct linux_binprm *bprm)
1092 {
1093         umode_t mode;
1094         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1095         int retval;
1096
1097         mode = inode->i_mode;
1098         if (bprm->file->f_op == NULL)
1099                 return -EACCES;
1100
1101         /* clear any previous set[ug]id data from a previous binary */
1102         bprm->cred->euid = current_euid();
1103         bprm->cred->egid = current_egid();
1104
1105         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1106                 /* Set-uid? */
1107                 if (mode & S_ISUID) {
1108                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1109                         bprm->cred->euid = inode->i_uid;
1110                 }
1111
1112                 /* Set-gid? */
1113                 /*
1114                  * If setgid is set but no group execute bit then this
1115                  * is a candidate for mandatory locking, not a setgid
1116                  * executable.
1117                  */
1118                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1119                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1120                         bprm->cred->egid = inode->i_gid;
1121                 }
1122         }
1123
1124         /* fill in binprm security blob */
1125         retval = security_bprm_set_creds(bprm);
1126         if (retval)
1127                 return retval;
1128         bprm->cred_prepared = 1;
1129
1130         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1131         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1132 }
1133
1134 EXPORT_SYMBOL(prepare_binprm);
1135
1136 /*
1137  * Arguments are '\0' separated strings found at the location bprm->p
1138  * points to; chop off the first by relocating brpm->p to right after
1139  * the first '\0' encountered.
1140  */
1141 int remove_arg_zero(struct linux_binprm *bprm)
1142 {
1143         int ret = 0;
1144         unsigned long offset;
1145         char *kaddr;
1146         struct page *page;
1147
1148         if (!bprm->argc)
1149                 return 0;
1150
1151         do {
1152                 offset = bprm->p & ~PAGE_MASK;
1153                 page = get_arg_page(bprm, bprm->p, 0);
1154                 if (!page) {
1155                         ret = -EFAULT;
1156                         goto out;
1157                 }
1158                 kaddr = kmap_atomic(page, KM_USER0);
1159
1160                 for (; offset < PAGE_SIZE && kaddr[offset];
1161                                 offset++, bprm->p++)
1162                         ;
1163
1164                 kunmap_atomic(kaddr, KM_USER0);
1165                 put_arg_page(page);
1166
1167                 if (offset == PAGE_SIZE)
1168                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1169         } while (offset == PAGE_SIZE);
1170
1171         bprm->p++;
1172         bprm->argc--;
1173         ret = 0;
1174
1175 out:
1176         return ret;
1177 }
1178 EXPORT_SYMBOL(remove_arg_zero);
1179
1180 /*
1181  * cycle the list of binary formats handler, until one recognizes the image
1182  */
1183 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1184 {
1185         unsigned int depth = bprm->recursion_depth;
1186         int try,retval;
1187         struct linux_binfmt *fmt;
1188
1189         retval = security_bprm_check(bprm);
1190         if (retval)
1191                 return retval;
1192         retval = ima_bprm_check(bprm);
1193         if (retval)
1194                 return retval;
1195
1196         /* kernel module loader fixup */
1197         /* so we don't try to load run modprobe in kernel space. */
1198         set_fs(USER_DS);
1199
1200         retval = audit_bprm(bprm);
1201         if (retval)
1202                 return retval;
1203
1204         retval = -ENOENT;
1205         for (try=0; try<2; try++) {
1206                 read_lock(&binfmt_lock);
1207                 list_for_each_entry(fmt, &formats, lh) {
1208                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1209                         if (!fn)
1210                                 continue;
1211                         if (!try_module_get(fmt->module))
1212                                 continue;
1213                         read_unlock(&binfmt_lock);
1214                         retval = fn(bprm, regs);
1215                         /*
1216                          * Restore the depth counter to its starting value
1217                          * in this call, so we don't have to rely on every
1218                          * load_binary function to restore it on return.
1219                          */
1220                         bprm->recursion_depth = depth;
1221                         if (retval >= 0) {
1222                                 if (depth == 0)
1223                                         tracehook_report_exec(fmt, bprm, regs);
1224                                 put_binfmt(fmt);
1225                                 allow_write_access(bprm->file);
1226                                 if (bprm->file)
1227                                         fput(bprm->file);
1228                                 bprm->file = NULL;
1229                                 current->did_exec = 1;
1230                                 proc_exec_connector(current);
1231                                 return retval;
1232                         }
1233                         read_lock(&binfmt_lock);
1234                         put_binfmt(fmt);
1235                         if (retval != -ENOEXEC || bprm->mm == NULL)
1236                                 break;
1237                         if (!bprm->file) {
1238                                 read_unlock(&binfmt_lock);
1239                                 return retval;
1240                         }
1241                 }
1242                 read_unlock(&binfmt_lock);
1243                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1244                         break;
1245 #ifdef CONFIG_MODULES
1246                 } else {
1247 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1248                         if (printable(bprm->buf[0]) &&
1249                             printable(bprm->buf[1]) &&
1250                             printable(bprm->buf[2]) &&
1251                             printable(bprm->buf[3]))
1252                                 break; /* -ENOEXEC */
1253                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1254 #endif
1255                 }
1256         }
1257         return retval;
1258 }
1259
1260 EXPORT_SYMBOL(search_binary_handler);
1261
1262 void free_bprm(struct linux_binprm *bprm)
1263 {
1264         free_arg_pages(bprm);
1265         if (bprm->cred)
1266                 abort_creds(bprm->cred);
1267         kfree(bprm);
1268 }
1269
1270 /*
1271  * sys_execve() executes a new program.
1272  */
1273 int do_execve(char * filename,
1274         char __user *__user *argv,
1275         char __user *__user *envp,
1276         struct pt_regs * regs)
1277 {
1278         struct linux_binprm *bprm;
1279         struct file *file;
1280         struct files_struct *displaced;
1281         bool clear_in_exec;
1282         int retval;
1283
1284         retval = unshare_files(&displaced);
1285         if (retval)
1286                 goto out_ret;
1287
1288         retval = -ENOMEM;
1289         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1290         if (!bprm)
1291                 goto out_files;
1292
1293         retval = mutex_lock_interruptible(&current->cred_exec_mutex);
1294         if (retval < 0)
1295                 goto out_free;
1296         current->in_execve = 1;
1297
1298         retval = -ENOMEM;
1299         bprm->cred = prepare_exec_creds();
1300         if (!bprm->cred)
1301                 goto out_unlock;
1302
1303         retval = check_unsafe_exec(bprm);
1304         if (retval < 0)
1305                 goto out_unlock;
1306         clear_in_exec = retval;
1307
1308         file = open_exec(filename);
1309         retval = PTR_ERR(file);
1310         if (IS_ERR(file))
1311                 goto out_unmark;
1312
1313         sched_exec();
1314
1315         bprm->file = file;
1316         bprm->filename = filename;
1317         bprm->interp = filename;
1318
1319         retval = bprm_mm_init(bprm);
1320         if (retval)
1321                 goto out_file;
1322
1323         bprm->argc = count(argv, MAX_ARG_STRINGS);
1324         if ((retval = bprm->argc) < 0)
1325                 goto out;
1326
1327         bprm->envc = count(envp, MAX_ARG_STRINGS);
1328         if ((retval = bprm->envc) < 0)
1329                 goto out;
1330
1331         retval = prepare_binprm(bprm);
1332         if (retval < 0)
1333                 goto out;
1334
1335         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1336         if (retval < 0)
1337                 goto out;
1338
1339         bprm->exec = bprm->p;
1340         retval = copy_strings(bprm->envc, envp, bprm);
1341         if (retval < 0)
1342                 goto out;
1343
1344         retval = copy_strings(bprm->argc, argv, bprm);
1345         if (retval < 0)
1346                 goto out;
1347
1348         current->flags &= ~PF_KTHREAD;
1349         retval = search_binary_handler(bprm,regs);
1350         if (retval < 0)
1351                 goto out;
1352
1353         /* execve succeeded */
1354         current->fs->in_exec = 0;
1355         current->in_execve = 0;
1356         mutex_unlock(&current->cred_exec_mutex);
1357         acct_update_integrals(current);
1358         free_bprm(bprm);
1359         if (displaced)
1360                 put_files_struct(displaced);
1361         return retval;
1362
1363 out:
1364         if (bprm->mm)
1365                 mmput (bprm->mm);
1366
1367 out_file:
1368         if (bprm->file) {
1369                 allow_write_access(bprm->file);
1370                 fput(bprm->file);
1371         }
1372
1373 out_unmark:
1374         if (clear_in_exec)
1375                 current->fs->in_exec = 0;
1376
1377 out_unlock:
1378         current->in_execve = 0;
1379         mutex_unlock(&current->cred_exec_mutex);
1380
1381 out_free:
1382         free_bprm(bprm);
1383
1384 out_files:
1385         if (displaced)
1386                 reset_files_struct(displaced);
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, long signr)
1412 {
1413         const struct cred *cred = current_cred();
1414         const char *pat_ptr = core_pattern;
1415         int ispipe = (*pat_ptr == '|');
1416         char *out_ptr = corename;
1417         char *const out_end = corename + CORENAME_MAX_SIZE;
1418         int rc;
1419         int pid_in_pattern = 0;
1420
1421         /* Repeat as long as we have more pattern to process and more output
1422            space */
1423         while (*pat_ptr) {
1424                 if (*pat_ptr != '%') {
1425                         if (out_ptr == out_end)
1426                                 goto out;
1427                         *out_ptr++ = *pat_ptr++;
1428                 } else {
1429                         switch (*++pat_ptr) {
1430                         case 0:
1431                                 goto out;
1432                         /* Double percent, output one percent */
1433                         case '%':
1434                                 if (out_ptr == out_end)
1435                                         goto out;
1436                                 *out_ptr++ = '%';
1437                                 break;
1438                         /* pid */
1439                         case 'p':
1440                                 pid_in_pattern = 1;
1441                                 rc = snprintf(out_ptr, out_end - out_ptr,
1442                                               "%d", task_tgid_vnr(current));
1443                                 if (rc > out_end - out_ptr)
1444                                         goto out;
1445                                 out_ptr += rc;
1446                                 break;
1447                         /* uid */
1448                         case 'u':
1449                                 rc = snprintf(out_ptr, out_end - out_ptr,
1450                                               "%d", cred->uid);
1451                                 if (rc > out_end - out_ptr)
1452                                         goto out;
1453                                 out_ptr += rc;
1454                                 break;
1455                         /* gid */
1456                         case 'g':
1457                                 rc = snprintf(out_ptr, out_end - out_ptr,
1458                                               "%d", cred->gid);
1459                                 if (rc > out_end - out_ptr)
1460                                         goto out;
1461                                 out_ptr += rc;
1462                                 break;
1463                         /* signal that caused the coredump */
1464                         case 's':
1465                                 rc = snprintf(out_ptr, out_end - out_ptr,
1466                                               "%ld", signr);
1467                                 if (rc > out_end - out_ptr)
1468                                         goto out;
1469                                 out_ptr += rc;
1470                                 break;
1471                         /* UNIX time of coredump */
1472                         case 't': {
1473                                 struct timeval tv;
1474                                 do_gettimeofday(&tv);
1475                                 rc = snprintf(out_ptr, out_end - out_ptr,
1476                                               "%lu", tv.tv_sec);
1477                                 if (rc > out_end - out_ptr)
1478                                         goto out;
1479                                 out_ptr += rc;
1480                                 break;
1481                         }
1482                         /* hostname */
1483                         case 'h':
1484                                 down_read(&uts_sem);
1485                                 rc = snprintf(out_ptr, out_end - out_ptr,
1486                                               "%s", utsname()->nodename);
1487                                 up_read(&uts_sem);
1488                                 if (rc > out_end - out_ptr)
1489                                         goto out;
1490                                 out_ptr += rc;
1491                                 break;
1492                         /* executable */
1493                         case 'e':
1494                                 rc = snprintf(out_ptr, out_end - out_ptr,
1495                                               "%s", current->comm);
1496                                 if (rc > out_end - out_ptr)
1497                                         goto out;
1498                                 out_ptr += rc;
1499                                 break;
1500                         /* core limit size */
1501                         case 'c':
1502                                 rc = snprintf(out_ptr, out_end - out_ptr,
1503                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1504                                 if (rc > out_end - out_ptr)
1505                                         goto out;
1506                                 out_ptr += rc;
1507                                 break;
1508                         default:
1509                                 break;
1510                         }
1511                         ++pat_ptr;
1512                 }
1513         }
1514         /* Backward compatibility with core_uses_pid:
1515          *
1516          * If core_pattern does not include a %p (as is the default)
1517          * and core_uses_pid is set, then .%pid will be appended to
1518          * the filename. Do not do this for piped commands. */
1519         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1520                 rc = snprintf(out_ptr, out_end - out_ptr,
1521                               ".%d", task_tgid_vnr(current));
1522                 if (rc > out_end - out_ptr)
1523                         goto out;
1524                 out_ptr += rc;
1525         }
1526 out:
1527         *out_ptr = 0;
1528         return ispipe;
1529 }
1530
1531 static int zap_process(struct task_struct *start)
1532 {
1533         struct task_struct *t;
1534         int nr = 0;
1535
1536         start->signal->flags = SIGNAL_GROUP_EXIT;
1537         start->signal->group_stop_count = 0;
1538
1539         t = start;
1540         do {
1541                 if (t != current && t->mm) {
1542                         sigaddset(&t->pending.signal, SIGKILL);
1543                         signal_wake_up(t, 1);
1544                         nr++;
1545                 }
1546         } while_each_thread(start, t);
1547
1548         return nr;
1549 }
1550
1551 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1552                                 struct core_state *core_state, int exit_code)
1553 {
1554         struct task_struct *g, *p;
1555         unsigned long flags;
1556         int nr = -EAGAIN;
1557
1558         spin_lock_irq(&tsk->sighand->siglock);
1559         if (!signal_group_exit(tsk->signal)) {
1560                 mm->core_state = core_state;
1561                 tsk->signal->group_exit_code = exit_code;
1562                 nr = zap_process(tsk);
1563         }
1564         spin_unlock_irq(&tsk->sighand->siglock);
1565         if (unlikely(nr < 0))
1566                 return nr;
1567
1568         if (atomic_read(&mm->mm_users) == nr + 1)
1569                 goto done;
1570         /*
1571          * We should find and kill all tasks which use this mm, and we should
1572          * count them correctly into ->nr_threads. We don't take tasklist
1573          * lock, but this is safe wrt:
1574          *
1575          * fork:
1576          *      None of sub-threads can fork after zap_process(leader). All
1577          *      processes which were created before this point should be
1578          *      visible to zap_threads() because copy_process() adds the new
1579          *      process to the tail of init_task.tasks list, and lock/unlock
1580          *      of ->siglock provides a memory barrier.
1581          *
1582          * do_exit:
1583          *      The caller holds mm->mmap_sem. This means that the task which
1584          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1585          *      its ->mm.
1586          *
1587          * de_thread:
1588          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1589          *      we must see either old or new leader, this does not matter.
1590          *      However, it can change p->sighand, so lock_task_sighand(p)
1591          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1592          *      it can't fail.
1593          *
1594          *      Note also that "g" can be the old leader with ->mm == NULL
1595          *      and already unhashed and thus removed from ->thread_group.
1596          *      This is OK, __unhash_process()->list_del_rcu() does not
1597          *      clear the ->next pointer, we will find the new leader via
1598          *      next_thread().
1599          */
1600         rcu_read_lock();
1601         for_each_process(g) {
1602                 if (g == tsk->group_leader)
1603                         continue;
1604                 if (g->flags & PF_KTHREAD)
1605                         continue;
1606                 p = g;
1607                 do {
1608                         if (p->mm) {
1609                                 if (unlikely(p->mm == mm)) {
1610                                         lock_task_sighand(p, &flags);
1611                                         nr += zap_process(p);
1612                                         unlock_task_sighand(p, &flags);
1613                                 }
1614                                 break;
1615                         }
1616                 } while_each_thread(g, p);
1617         }
1618         rcu_read_unlock();
1619 done:
1620         atomic_set(&core_state->nr_threads, nr);
1621         return nr;
1622 }
1623
1624 static int coredump_wait(int exit_code, struct core_state *core_state)
1625 {
1626         struct task_struct *tsk = current;
1627         struct mm_struct *mm = tsk->mm;
1628         struct completion *vfork_done;
1629         int core_waiters;
1630
1631         init_completion(&core_state->startup);
1632         core_state->dumper.task = tsk;
1633         core_state->dumper.next = NULL;
1634         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1635         up_write(&mm->mmap_sem);
1636
1637         if (unlikely(core_waiters < 0))
1638                 goto fail;
1639
1640         /*
1641          * Make sure nobody is waiting for us to release the VM,
1642          * otherwise we can deadlock when we wait on each other
1643          */
1644         vfork_done = tsk->vfork_done;
1645         if (vfork_done) {
1646                 tsk->vfork_done = NULL;
1647                 complete(vfork_done);
1648         }
1649
1650         if (core_waiters)
1651                 wait_for_completion(&core_state->startup);
1652 fail:
1653         return core_waiters;
1654 }
1655
1656 static void coredump_finish(struct mm_struct *mm)
1657 {
1658         struct core_thread *curr, *next;
1659         struct task_struct *task;
1660
1661         next = mm->core_state->dumper.next;
1662         while ((curr = next) != NULL) {
1663                 next = curr->next;
1664                 task = curr->task;
1665                 /*
1666                  * see exit_mm(), curr->task must not see
1667                  * ->task == NULL before we read ->next.
1668                  */
1669                 smp_mb();
1670                 curr->task = NULL;
1671                 wake_up_process(task);
1672         }
1673
1674         mm->core_state = NULL;
1675 }
1676
1677 /*
1678  * set_dumpable converts traditional three-value dumpable to two flags and
1679  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1680  * these bits are not changed atomically.  So get_dumpable can observe the
1681  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1682  * return either old dumpable or new one by paying attention to the order of
1683  * modifying the bits.
1684  *
1685  * dumpable |   mm->flags (binary)
1686  * old  new | initial interim  final
1687  * ---------+-----------------------
1688  *  0    1  |   00      01      01
1689  *  0    2  |   00      10(*)   11
1690  *  1    0  |   01      00      00
1691  *  1    2  |   01      11      11
1692  *  2    0  |   11      10(*)   00
1693  *  2    1  |   11      11      01
1694  *
1695  * (*) get_dumpable regards interim value of 10 as 11.
1696  */
1697 void set_dumpable(struct mm_struct *mm, int value)
1698 {
1699         switch (value) {
1700         case 0:
1701                 clear_bit(MMF_DUMPABLE, &mm->flags);
1702                 smp_wmb();
1703                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1704                 break;
1705         case 1:
1706                 set_bit(MMF_DUMPABLE, &mm->flags);
1707                 smp_wmb();
1708                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1709                 break;
1710         case 2:
1711                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1712                 smp_wmb();
1713                 set_bit(MMF_DUMPABLE, &mm->flags);
1714                 break;
1715         }
1716 }
1717
1718 int get_dumpable(struct mm_struct *mm)
1719 {
1720         int ret;
1721
1722         ret = mm->flags & 0x3;
1723         return (ret >= 2) ? 2 : ret;
1724 }
1725
1726 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1727 {
1728         struct core_state core_state;
1729         char corename[CORENAME_MAX_SIZE + 1];
1730         struct mm_struct *mm = current->mm;
1731         struct linux_binfmt * binfmt;
1732         struct inode * inode;
1733         struct file * file;
1734         const struct cred *old_cred;
1735         struct cred *cred;
1736         int retval = 0;
1737         int flag = 0;
1738         int ispipe = 0;
1739         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1740         char **helper_argv = NULL;
1741         int helper_argc = 0;
1742         char *delimit;
1743
1744         audit_core_dumps(signr);
1745
1746         binfmt = current->binfmt;
1747         if (!binfmt || !binfmt->core_dump)
1748                 goto fail;
1749
1750         cred = prepare_creds();
1751         if (!cred) {
1752                 retval = -ENOMEM;
1753                 goto fail;
1754         }
1755
1756         down_write(&mm->mmap_sem);
1757         /*
1758          * If another thread got here first, or we are not dumpable, bail out.
1759          */
1760         if (mm->core_state || !get_dumpable(mm)) {
1761                 up_write(&mm->mmap_sem);
1762                 put_cred(cred);
1763                 goto fail;
1764         }
1765
1766         /*
1767          *      We cannot trust fsuid as being the "true" uid of the
1768          *      process nor do we know its entire history. We only know it
1769          *      was tainted so we dump it as root in mode 2.
1770          */
1771         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1772                 flag = O_EXCL;          /* Stop rewrite attacks */
1773                 cred->fsuid = 0;        /* Dump root private */
1774         }
1775
1776         retval = coredump_wait(exit_code, &core_state);
1777         if (retval < 0) {
1778                 put_cred(cred);
1779                 goto fail;
1780         }
1781
1782         old_cred = override_creds(cred);
1783
1784         /*
1785          * Clear any false indication of pending signals that might
1786          * be seen by the filesystem code called to write the core file.
1787          */
1788         clear_thread_flag(TIF_SIGPENDING);
1789
1790         /*
1791          * lock_kernel() because format_corename() is controlled by sysctl, which
1792          * uses lock_kernel()
1793          */
1794         lock_kernel();
1795         ispipe = format_corename(corename, signr);
1796         unlock_kernel();
1797         /*
1798          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1799          * to a pipe.  Since we're not writing directly to the filesystem
1800          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1801          * created unless the pipe reader choses to write out the core file
1802          * at which point file size limits and permissions will be imposed
1803          * as it does with any other process
1804          */
1805         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1806                 goto fail_unlock;
1807
1808         if (ispipe) {
1809                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1810                 if (!helper_argv) {
1811                         printk(KERN_WARNING "%s failed to allocate memory\n",
1812                                __func__);
1813                         goto fail_unlock;
1814                 }
1815                 /* Terminate the string before the first option */
1816                 delimit = strchr(corename, ' ');
1817                 if (delimit)
1818                         *delimit = '\0';
1819                 delimit = strrchr(helper_argv[0], '/');
1820                 if (delimit)
1821                         delimit++;
1822                 else
1823                         delimit = helper_argv[0];
1824                 if (!strcmp(delimit, current->comm)) {
1825                         printk(KERN_NOTICE "Recursive core dump detected, "
1826                                         "aborting\n");
1827                         goto fail_unlock;
1828                 }
1829
1830                 core_limit = RLIM_INFINITY;
1831
1832                 /* SIGPIPE can happen, but it's just never processed */
1833                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1834                                 &file)) {
1835                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1836                                corename);
1837                         goto fail_unlock;
1838                 }
1839         } else
1840                 file = filp_open(corename,
1841                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1842                                  0600);
1843         if (IS_ERR(file))
1844                 goto fail_unlock;
1845         inode = file->f_path.dentry->d_inode;
1846         if (inode->i_nlink > 1)
1847                 goto close_fail;        /* multiple links - don't dump */
1848         if (!ispipe && d_unhashed(file->f_path.dentry))
1849                 goto close_fail;
1850
1851         /* AK: actually i see no reason to not allow this for named pipes etc.,
1852            but keep the previous behaviour for now. */
1853         if (!ispipe && !S_ISREG(inode->i_mode))
1854                 goto close_fail;
1855         /*
1856          * Dont allow local users get cute and trick others to coredump
1857          * into their pre-created files:
1858          */
1859         if (inode->i_uid != current_fsuid())
1860                 goto close_fail;
1861         if (!file->f_op)
1862                 goto close_fail;
1863         if (!file->f_op->write)
1864                 goto close_fail;
1865         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1866                 goto close_fail;
1867
1868         retval = binfmt->core_dump(signr, regs, file, core_limit);
1869
1870         if (retval)
1871                 current->signal->group_exit_code |= 0x80;
1872 close_fail:
1873         filp_close(file, NULL);
1874 fail_unlock:
1875         if (helper_argv)
1876                 argv_free(helper_argv);
1877
1878         revert_creds(old_cred);
1879         put_cred(cred);
1880         coredump_finish(mm);
1881 fail:
1882         return;
1883 }