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/perf_event.h>
  37 #include <linux/highmem.h>
  38 #include <linux/spinlock.h>
  39 #include <linux/key.h>
  40 #include <linux/personality.h>
  41 #include <linux/binfmts.h>
  42 #include <linux/utsname.h>
  43 #include <linux/pid_namespace.h>
  44 #include <linux/module.h>
  45 #include <linux/namei.h>
  46 #include <linux/proc_fs.h>
  47 #include <linux/mount.h>
  48 #include <linux/security.h>
  49 #include <linux/ima.h>
  50 #include <linux/syscalls.h>
  51 #include <linux/tsacct_kern.h>
  52 #include <linux/cn_proc.h>
  53 #include <linux/audit.h>
  54 #include <linux/tracehook.h>
  55 #include <linux/kmod.h>
  56 #include <linux/fsnotify.h>
  57 #include <linux/fs_struct.h>
  58 #include <linux/pipe_fs_i.h>
  59
  60 #include <asm/uaccess.h>
  61 #include <asm/mmu_context.h>
  62 #include <asm/tlb.h>
  63 #include "internal.h"
  64
  65 int core_uses_pid;
  66 char core_pattern[CORENAME_MAX_SIZE] = "core";
  67 unsigned int core_pipe_limit;
  68 int suid_dumpable = 0;
  69
  70 /* The maximal length of core_pattern is also specified in sysctl.c */
  71
  72 static LIST_HEAD(formats);
  73 static DEFINE_RWLOCK(binfmt_lock);
  74
  75 int __register_binfmt(struct linux_binfmt * fmt, int insert)
  76 {
  77         if (!fmt)
  78                 return -EINVAL;
  79         write_lock(&binfmt_lock);
  80         insert ? list_add(&fmt->lh, &formats) :
  81                  list_add_tail(&fmt->lh, &formats);
  82         write_unlock(&binfmt_lock);
  83         return 0;
  84 }
  85
  86 EXPORT_SYMBOL(__register_binfmt);
  87
  88 void unregister_binfmt(struct linux_binfmt * fmt)
  89 {
  90         write_lock(&binfmt_lock);
  91         list_del(&fmt->lh);
  92         write_unlock(&binfmt_lock);
  93 }
  94
  95 EXPORT_SYMBOL(unregister_binfmt);
  96
  97 static inline void put_binfmt(struct linux_binfmt * fmt)
  98 {
  99         module_put(fmt->module);
 100 }
 101
 102 /*
 103  * Note that a shared library must be both readable and executable due to
 104  * security reasons.
 105  *
 106  * Also note that we take the address to load from from the file itself.
 107  */
 108 SYSCALL_DEFINE1(uselib, const char __user *, library)
 109 {
 110         struct file *file;
 111         char *tmp = getname(library);
 112         int error = PTR_ERR(tmp);
 113
 114         if (IS_ERR(tmp))
 115                 goto out;
 116
 117         file = do_filp_open(AT_FDCWD, tmp,
 118                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
 119                                 MAY_READ | MAY_EXEC | MAY_OPEN);
 120         putname(tmp);
 121         error = PTR_ERR(file);
 122         if (IS_ERR(file))
 123                 goto out;
 124
 125         error = -EINVAL;
 126         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 127                 goto exit;
 128
 129         error = -EACCES;
 130         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 131                 goto exit;
 132
 133         fsnotify_open(file->f_path.dentry);
 134
 135         error = -ENOEXEC;
 136         if(file->f_op) {
 137                 struct linux_binfmt * fmt;
 138
 139                 read_lock(&binfmt_lock);
 140                 list_for_each_entry(fmt, &formats, lh) {
 141                         if (!fmt->load_shlib)
 142                                 continue;
 143                         if (!try_module_get(fmt->module))
 144                                 continue;
 145                         read_unlock(&binfmt_lock);
 146                         error = fmt->load_shlib(file);
 147                         read_lock(&binfmt_lock);
 148                         put_binfmt(fmt);
 149                         if (error != -ENOEXEC)
 150                                 break;
 151                 }
 152                 read_unlock(&binfmt_lock);
 153         }
 154 exit:
 155         fput(file);
 156 out:
 157         return error;
 158 }
 159
 160 #ifdef CONFIG_MMU
 161
 162 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 163                 int write)
 164 {
 165         struct page *page;
 166         int ret;
 167
 168 #ifdef CONFIG_STACK_GROWSUP
 169         if (write) {
 170                 ret = expand_stack_downwards(bprm->vma, pos);
 171                 if (ret < 0)
 172                         return NULL;
 173         }
 174 #endif
 175         ret = get_user_pages(current, bprm->mm, pos,
 176                         1, write, 1, &page, NULL);
 177         if (ret <= 0)
 178                 return NULL;
 179
 180         if (write) {
 181                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 182                 struct rlimit *rlim;
 183
 184                 /*
 185                  * We've historically supported up to 32 pages (ARG_MAX)
 186                  * of argument strings even with small stacks
 187                  */
 188                 if (size <= ARG_MAX)
 189                         return page;
 190
 191                 /*
 192                  * Limit to 1/4-th the stack size for the argv+env strings.
 193                  * This ensures that:
 194                  *  - the remaining binfmt code will not run out of stack space,
 195                  *  - the program will have a reasonable amount of stack left
 196                  *    to work from.
 197                  */
 198                 rlim = current->signal->rlim;
 199                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
 200                         put_page(page);
 201                         return NULL;
 202                 }
 203         }
 204
 205         return page;
 206 }
 207
 208 static void put_arg_page(struct page *page)
 209 {
 210         put_page(page);
 211 }
 212
 213 static void free_arg_page(struct linux_binprm *bprm, int i)
 214 {
 215 }
 216
 217 static void free_arg_pages(struct linux_binprm *bprm)
 218 {
 219 }
 220
 221 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 222                 struct page *page)
 223 {
 224         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 225 }
 226
 227 static int __bprm_mm_init(struct linux_binprm *bprm)
 228 {
 229         int err;
 230         struct vm_area_struct *vma = NULL;
 231         struct mm_struct *mm = bprm->mm;
 232
 233         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 234         if (!vma)
 235                 return -ENOMEM;
 236
 237         down_write(&mm->mmap_sem);
 238         vma->vm_mm = mm;
 239
 240         /*
 241          * Place the stack at the largest stack address the architecture
 242          * supports. Later, we'll move this to an appropriate place. We don't
 243          * use STACK_TOP because that can depend on attributes which aren't
 244          * configured yet.
 245          */
 246         vma->vm_end = STACK_TOP_MAX;
 247         vma->vm_start = vma->vm_end - PAGE_SIZE;
 248         vma->vm_flags = VM_STACK_FLAGS;
 249         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 250         err = insert_vm_struct(mm, vma);
 251         if (err)
 252                 goto err;
 253
 254         mm->stack_vm = mm->total_vm = 1;
 255         up_write(&mm->mmap_sem);
 256         bprm->p = vma->vm_end - sizeof(void *);
 257         return 0;
 258 err:
 259         up_write(&mm->mmap_sem);
 260         bprm->vma = NULL;
 261         kmem_cache_free(vm_area_cachep, vma);
 262         return err;
 263 }
 264
 265 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 266 {
 267         return len <= MAX_ARG_STRLEN;
 268 }
 269
 270 #else
 271
 272 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 273                 int write)
 274 {
 275         struct page *page;
 276
 277         page = bprm->page[pos / PAGE_SIZE];
 278         if (!page && write) {
 279                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 280                 if (!page)
 281                         return NULL;
 282                 bprm->page[pos / PAGE_SIZE] = page;
 283         }
 284
 285         return page;
 286 }
 287
 288 static void put_arg_page(struct page *page)
 289 {
 290 }
 291
 292 static void free_arg_page(struct linux_binprm *bprm, int i)
 293 {
 294         if (bprm->page[i]) {
 295                 __free_page(bprm->page[i]);
 296                 bprm->page[i] = NULL;
 297         }
 298 }
 299
 300 static void free_arg_pages(struct linux_binprm *bprm)
 301 {
 302         int i;
 303
 304         for (i = 0; i < MAX_ARG_PAGES; i++)
 305                 free_arg_page(bprm, i);
 306 }
 307
 308 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 309                 struct page *page)
 310 {
 311 }
 312
 313 static int __bprm_mm_init(struct linux_binprm *bprm)
 314 {
 315         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 316         return 0;
 317 }
 318
 319 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 320 {
 321         return len <= bprm->p;
 322 }
 323
 324 #endif /* CONFIG_MMU */
 325
 326 /*
 327  * Create a new mm_struct and populate it with a temporary stack
 328  * vm_area_struct.  We don't have enough context at this point to set the stack
 329  * flags, permissions, and offset, so we use temporary values.  We'll update
 330  * them later in setup_arg_pages().
 331  */
 332 int bprm_mm_init(struct linux_binprm *bprm)
 333 {
 334         int err;
 335         struct mm_struct *mm = NULL;
 336
 337         bprm->mm = mm = mm_alloc();
 338         err = -ENOMEM;
 339         if (!mm)
 340                 goto err;
 341
 342         err = init_new_context(current, mm);
 343         if (err)
 344                 goto err;
 345
 346         err = __bprm_mm_init(bprm);
 347         if (err)
 348                 goto err;
 349
 350         return 0;
 351
 352 err:
 353         if (mm) {
 354                 bprm->mm = NULL;
 355                 mmdrop(mm);
 356         }
 357
 358         return err;
 359 }
 360
 361 /*
 362  * count() counts the number of strings in array ARGV.
 363  */
 364 static int count(char __user * __user * argv, int max)
 365 {
 366         int i = 0;
 367
 368         if (argv != NULL) {
 369                 for (;;) {
 370                         char __user * p;
 371
 372                         if (get_user(p, argv))
 373                                 return -EFAULT;
 374                         if (!p)
 375                                 break;
 376                         argv++;
 377                         if (i++ >= max)
 378                                 return -E2BIG;
 379                         cond_resched();
 380                 }
 381         }
 382         return i;
 383 }
 384
 385 /*
 386  * 'copy_strings()' copies argument/environment strings from the old
 387  * processes's memory to the new process's stack.  The call to get_user_pages()
 388  * ensures the destination page is created and not swapped out.
 389  */
 390 static int copy_strings(int argc, char __user * __user * argv,
 391                         struct linux_binprm *bprm)
 392 {
 393         struct page *kmapped_page = NULL;
 394         char *kaddr = NULL;
 395         unsigned long kpos = 0;
 396         int ret;
 397
 398         while (argc-- > 0) {
 399                 char __user *str;
 400                 int len;
 401                 unsigned long pos;
 402
 403                 if (get_user(str, argv+argc) ||
 404                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 405                         ret = -EFAULT;
 406                         goto out;
 407                 }
 408
 409                 if (!valid_arg_len(bprm, len)) {
 410                         ret = -E2BIG;
 411                         goto out;
 412                 }
 413
 414                 /* We're going to work our way backwords. */
 415                 pos = bprm->p;
 416                 str += len;
 417                 bprm->p -= len;
 418
 419                 while (len > 0) {
 420                         int offset, bytes_to_copy;
 421
 422                         offset = pos % PAGE_SIZE;
 423                         if (offset == 0)
 424                                 offset = PAGE_SIZE;
 425
 426                         bytes_to_copy = offset;
 427                         if (bytes_to_copy > len)
 428                                 bytes_to_copy = len;
 429
 430                         offset -= bytes_to_copy;
 431                         pos -= bytes_to_copy;
 432                         str -= bytes_to_copy;
 433                         len -= bytes_to_copy;
 434
 435                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 436                                 struct page *page;
 437
 438                                 page = get_arg_page(bprm, pos, 1);
 439                                 if (!page) {
 440                                         ret = -E2BIG;
 441                                         goto out;
 442                                 }
 443
 444                                 if (kmapped_page) {
 445                                         flush_kernel_dcache_page(kmapped_page);
 446                                         kunmap(kmapped_page);
 447                                         put_arg_page(kmapped_page);
 448                                 }
 449                                 kmapped_page = page;
 450                                 kaddr = kmap(kmapped_page);
 451                                 kpos = pos & PAGE_MASK;
 452                                 flush_arg_page(bprm, kpos, kmapped_page);
 453                         }
 454                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 455                                 ret = -EFAULT;
 456                                 goto out;
 457                         }
 458                 }
 459         }
 460         ret = 0;
 461 out:
 462         if (kmapped_page) {
 463                 flush_kernel_dcache_page(kmapped_page);
 464                 kunmap(kmapped_page);
 465                 put_arg_page(kmapped_page);
 466         }
 467         return ret;
 468 }
 469
 470 /*
 471  * Like copy_strings, but get argv and its values from kernel memory.
 472  */
 473 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 474 {
 475         int r;
 476         mm_segment_t oldfs = get_fs();
 477         set_fs(KERNEL_DS);
 478         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 479         set_fs(oldfs);
 480         return r;
 481 }
 482 EXPORT_SYMBOL(copy_strings_kernel);
 483
 484 #ifdef CONFIG_MMU
 485
 486 /*
 487  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 488  * the binfmt code determines where the new stack should reside, we shift it to
 489  * its final location.  The process proceeds as follows:
 490  *
 491  * 1) Use shift to calculate the new vma endpoints.
 492  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 493  *    arguments passed to subsequent functions are consistent.
 494  * 3) Move vma's page tables to the new range.
 495  * 4) Free up any cleared pgd range.
 496  * 5) Shrink the vma to cover only the new range.
 497  */
 498 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 499 {
 500         struct mm_struct *mm = vma->vm_mm;
 501         unsigned long old_start = vma->vm_start;
 502         unsigned long old_end = vma->vm_end;
 503         unsigned long length = old_end - old_start;
 504         unsigned long new_start = old_start - shift;
 505         unsigned long new_end = old_end - shift;
 506         struct mmu_gather *tlb;
 507
 508         BUG_ON(new_start > new_end);
 509
 510         /*
 511          * ensure there are no vmas between where we want to go
 512          * and where we are
 513          */
 514         if (vma != find_vma(mm, new_start))
 515                 return -EFAULT;
 516
 517         /*
 518          * cover the whole range: [new_start, old_end)
 519          */
 520         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 521
 522         /*
 523          * move the page tables downwards, on failure we rely on
 524          * process cleanup to remove whatever mess we made.
 525          */
 526         if (length != move_page_tables(vma, old_start,
 527                                        vma, new_start, length))
 528                 return -ENOMEM;
 529
 530         lru_add_drain();
 531         tlb = tlb_gather_mmu(mm, 0);
 532         if (new_end > old_start) {
 533                 /*
 534                  * when the old and new regions overlap clear from new_end.
 535                  */
 536                 free_pgd_range(tlb, new_end, old_end, new_end,
 537                         vma->vm_next ? vma->vm_next->vm_start : 0);
 538         } else {
 539                 /*
 540                  * otherwise, clean from old_start; this is done to not touch
 541                  * the address space in [new_end, old_start) some architectures
 542                  * have constraints on va-space that make this illegal (IA64) -
 543                  * for the others its just a little faster.
 544                  */
 545                 free_pgd_range(tlb, old_start, old_end, new_end,
 546                         vma->vm_next ? vma->vm_next->vm_start : 0);
 547         }
 548         tlb_finish_mmu(tlb, new_end, old_end);
 549
 550         /*
 551          * shrink the vma to just the new range.
 552          */
 553         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 554
 555         return 0;
 556 }
 557
 558 #define EXTRA_STACK_VM_PAGES    20      /* random */
 559
 560 /*
 561  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 562  * the stack is optionally relocated, and some extra space is added.
 563  */
 564 int setup_arg_pages(struct linux_binprm *bprm,
 565                     unsigned long stack_top,
 566                     int executable_stack)
 567 {
 568         unsigned long ret;
 569         unsigned long stack_shift;
 570         struct mm_struct *mm = current->mm;
 571         struct vm_area_struct *vma = bprm->vma;
 572         struct vm_area_struct *prev = NULL;
 573         unsigned long vm_flags;
 574         unsigned long stack_base;
 575
 576 #ifdef CONFIG_STACK_GROWSUP
 577         /* Limit stack size to 1GB */
 578         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 579         if (stack_base > (1 << 30))
 580                 stack_base = 1 << 30;
 581
 582         /* Make sure we didn't let the argument array grow too large. */
 583         if (vma->vm_end - vma->vm_start > stack_base)
 584                 return -ENOMEM;
 585
 586         stack_base = PAGE_ALIGN(stack_top - stack_base);
 587
 588         stack_shift = vma->vm_start - stack_base;
 589         mm->arg_start = bprm->p - stack_shift;
 590         bprm->p = vma->vm_end - stack_shift;
 591 #else
 592         stack_top = arch_align_stack(stack_top);
 593         stack_top = PAGE_ALIGN(stack_top);
 594         stack_shift = vma->vm_end - stack_top;
 595
 596         bprm->p -= stack_shift;
 597         mm->arg_start = bprm->p;
 598 #endif
 599
 600         if (bprm->loader)
 601                 bprm->loader -= stack_shift;
 602         bprm->exec -= stack_shift;
 603
 604         down_write(&mm->mmap_sem);
 605         vm_flags = VM_STACK_FLAGS;
 606
 607         /*
 608          * Adjust stack execute permissions; explicitly enable for
 609          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 610          * (arch default) otherwise.
 611          */
 612         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 613                 vm_flags |= VM_EXEC;
 614         else if (executable_stack == EXSTACK_DISABLE_X)
 615                 vm_flags &= ~VM_EXEC;
 616         vm_flags |= mm->def_flags;
 617
 618         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 619                         vm_flags);
 620         if (ret)
 621                 goto out_unlock;
 622         BUG_ON(prev != vma);
 623
 624         /* Move stack pages down in memory. */
 625         if (stack_shift) {
 626                 ret = shift_arg_pages(vma, stack_shift);
 627                 if (ret) {
 628                         up_write(&mm->mmap_sem);
 629                         return ret;
 630                 }
 631         }
 632
 633 #ifdef CONFIG_STACK_GROWSUP
 634         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 635 #else
 636         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 637 #endif
 638         ret = expand_stack(vma, stack_base);
 639         if (ret)
 640                 ret = -EFAULT;
 641
 642 out_unlock:
 643         up_write(&mm->mmap_sem);
 644         return 0;
 645 }
 646 EXPORT_SYMBOL(setup_arg_pages);
 647
 648 #endif /* CONFIG_MMU */
 649
 650 struct file *open_exec(const char *name)
 651 {
 652         struct file *file;
 653         int err;
 654
 655         file = do_filp_open(AT_FDCWD, name,
 656                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
 657                                 MAY_EXEC | MAY_OPEN);
 658         if (IS_ERR(file))
 659                 goto out;
 660
 661         err = -EACCES;
 662         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 663                 goto exit;
 664
 665         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 666                 goto exit;
 667
 668         fsnotify_open(file->f_path.dentry);
 669
 670         err = deny_write_access(file);
 671         if (err)
 672                 goto exit;
 673
 674 out:
 675         return file;
 676
 677 exit:
 678         fput(file);
 679         return ERR_PTR(err);
 680 }
 681 EXPORT_SYMBOL(open_exec);
 682
 683 int kernel_read(struct file *file, loff_t offset,
 684                 char *addr, unsigned long count)
 685 {
 686         mm_segment_t old_fs;
 687         loff_t pos = offset;
 688         int result;
 689
 690         old_fs = get_fs();
 691         set_fs(get_ds());
 692         /* The cast to a user pointer is valid due to the set_fs() */
 693         result = vfs_read(file, (void __user *)addr, count, &pos);
 694         set_fs(old_fs);
 695         return result;
 696 }
 697
 698 EXPORT_SYMBOL(kernel_read);
 699
 700 static int exec_mmap(struct mm_struct *mm)
 701 {
 702         struct task_struct *tsk;
 703         struct mm_struct * old_mm, *active_mm;
 704
 705         /* Notify parent that we're no longer interested in the old VM */
 706         tsk = current;
 707         old_mm = current->mm;
 708         mm_release(tsk, old_mm);
 709
 710         if (old_mm) {
 711                 /*
 712                  * Make sure that if there is a core dump in progress
 713                  * for the old mm, we get out and die instead of going
 714                  * through with the exec.  We must hold mmap_sem around
 715                  * checking core_state and changing tsk->mm.
 716                  */
 717                 down_read(&old_mm->mmap_sem);
 718                 if (unlikely(old_mm->core_state)) {
 719                         up_read(&old_mm->mmap_sem);
 720                         return -EINTR;
 721                 }
 722         }
 723         task_lock(tsk);
 724         active_mm = tsk->active_mm;
 725         tsk->mm = mm;
 726         tsk->active_mm = mm;
 727         activate_mm(active_mm, mm);
 728         task_unlock(tsk);
 729         arch_pick_mmap_layout(mm);
 730         if (old_mm) {
 731                 up_read(&old_mm->mmap_sem);
 732                 BUG_ON(active_mm != old_mm);
 733                 mm_update_next_owner(old_mm);
 734                 mmput(old_mm);
 735                 return 0;
 736         }
 737         mmdrop(active_mm);
 738         return 0;
 739 }
 740
 741 /*
 742  * This function makes sure the current process has its own signal table,
 743  * so that flush_signal_handlers can later reset the handlers without
 744  * disturbing other processes.  (Other processes might share the signal
 745  * table via the CLONE_SIGHAND option to clone().)
 746  */
 747 static int de_thread(struct task_struct *tsk)
 748 {
 749         struct signal_struct *sig = tsk->signal;
 750         struct sighand_struct *oldsighand = tsk->sighand;
 751         spinlock_t *lock = &oldsighand->siglock;
 752         int count;
 753
 754         if (thread_group_empty(tsk))
 755                 goto no_thread_group;
 756
 757         /*
 758          * Kill all other threads in the thread group.
 759          */
 760         spin_lock_irq(lock);
 761         if (signal_group_exit(sig)) {
 762                 /*
 763                  * Another group action in progress, just
 764                  * return so that the signal is processed.
 765                  */
 766                 spin_unlock_irq(lock);
 767                 return -EAGAIN;
 768         }
 769         sig->group_exit_task = tsk;
 770         zap_other_threads(tsk);
 771
 772         /* Account for the thread group leader hanging around: */
 773         count = thread_group_leader(tsk) ? 1 : 2;
 774         sig->notify_count = count;
 775         while (atomic_read(&sig->count) > count) {
 776                 __set_current_state(TASK_UNINTERRUPTIBLE);
 777                 spin_unlock_irq(lock);
 778                 schedule();
 779                 spin_lock_irq(lock);
 780         }
 781         spin_unlock_irq(lock);
 782
 783         /*
 784          * At this point all other threads have exited, all we have to
 785          * do is to wait for the thread group leader to become inactive,
 786          * and to assume its PID:
 787          */
 788         if (!thread_group_leader(tsk)) {
 789                 struct task_struct *leader = tsk->group_leader;
 790
 791                 sig->notify_count = -1; /* for exit_notify() */
 792                 for (;;) {
 793                         write_lock_irq(&tasklist_lock);
 794                         if (likely(leader->exit_state))
 795                                 break;
 796                         __set_current_state(TASK_UNINTERRUPTIBLE);
 797                         write_unlock_irq(&tasklist_lock);
 798                         schedule();
 799                 }
 800
 801                 /*
 802                  * The only record we have of the real-time age of a
 803                  * process, regardless of execs it's done, is start_time.
 804                  * All the past CPU time is accumulated in signal_struct
 805                  * from sister threads now dead.  But in this non-leader
 806                  * exec, nothing survives from the original leader thread,
 807                  * whose birth marks the true age of this process now.
 808                  * When we take on its identity by switching to its PID, we
 809                  * also take its birthdate (always earlier than our own).
 810                  */
 811                 tsk->start_time = leader->start_time;
 812
 813                 BUG_ON(!same_thread_group(leader, tsk));
 814                 BUG_ON(has_group_leader_pid(tsk));
 815                 /*
 816                  * An exec() starts a new thread group with the
 817                  * TGID of the previous thread group. Rehash the
 818                  * two threads with a switched PID, and release
 819                  * the former thread group leader:
 820                  */
 821
 822                 /* Become a process group leader with the old leader's pid.
 823                  * The old leader becomes a thread of the this thread group.
 824                  * Note: The old leader also uses this pid until release_task
 825                  *       is called.  Odd but simple and correct.
 826                  */
 827                 detach_pid(tsk, PIDTYPE_PID);
 828                 tsk->pid = leader->pid;
 829                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 830                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 831                 transfer_pid(leader, tsk, PIDTYPE_SID);
 832                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 833
 834                 tsk->group_leader = tsk;
 835                 leader->group_leader = tsk;
 836
 837                 tsk->exit_signal = SIGCHLD;
 838
 839                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 840                 leader->exit_state = EXIT_DEAD;
 841                 write_unlock_irq(&tasklist_lock);
 842
 843                 release_task(leader);
 844         }
 845
 846         sig->group_exit_task = NULL;
 847         sig->notify_count = 0;
 848
 849 no_thread_group:
 850         if (current->mm)
 851                 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
 852
 853         exit_itimers(sig);
 854         flush_itimer_signals();
 855
 856         if (atomic_read(&oldsighand->count) != 1) {
 857                 struct sighand_struct *newsighand;
 858                 /*
 859                  * This ->sighand is shared with the CLONE_SIGHAND
 860                  * but not CLONE_THREAD task, switch to the new one.
 861                  */
 862                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 863                 if (!newsighand)
 864                         return -ENOMEM;
 865
 866                 atomic_set(&newsighand->count, 1);
 867                 memcpy(newsighand->action, oldsighand->action,
 868                        sizeof(newsighand->action));
 869
 870                 write_lock_irq(&tasklist_lock);
 871                 spin_lock(&oldsighand->siglock);
 872                 rcu_assign_pointer(tsk->sighand, newsighand);
 873                 spin_unlock(&oldsighand->siglock);
 874                 write_unlock_irq(&tasklist_lock);
 875
 876                 __cleanup_sighand(oldsighand);
 877         }
 878
 879         BUG_ON(!thread_group_leader(tsk));
 880         return 0;
 881 }
 882
 883 /*
 884  * These functions flushes out all traces of the currently running executable
 885  * so that a new one can be started
 886  */
 887 static void flush_old_files(struct files_struct * files)
 888 {
 889         long j = -1;
 890         struct fdtable *fdt;
 891
 892         spin_lock(&files->file_lock);
 893         for (;;) {
 894                 unsigned long set, i;
 895
 896                 j++;
 897                 i = j * __NFDBITS;
 898                 fdt = files_fdtable(files);
 899                 if (i >= fdt->max_fds)
 900                         break;
 901                 set = fdt->close_on_exec->fds_bits[j];
 902                 if (!set)
 903                         continue;
 904                 fdt->close_on_exec->fds_bits[j] = 0;
 905                 spin_unlock(&files->file_lock);
 906                 for ( ; set ; i++,set >>= 1) {
 907                         if (set & 1) {
 908                                 sys_close(i);
 909                         }
 910                 }
 911                 spin_lock(&files->file_lock);
 912
 913         }
 914         spin_unlock(&files->file_lock);
 915 }
 916
 917 char *get_task_comm(char *buf, struct task_struct *tsk)
 918 {
 919         /* buf must be at least sizeof(tsk->comm) in size */
 920         task_lock(tsk);
 921         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 922         task_unlock(tsk);
 923         return buf;
 924 }
 925
 926 void set_task_comm(struct task_struct *tsk, char *buf)
 927 {
 928         task_lock(tsk);
 929         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 930         task_unlock(tsk);
 931         perf_event_comm(tsk);
 932 }
 933
 934 int flush_old_exec(struct linux_binprm * bprm)
 935 {
 936         char * name;
 937         int i, ch, retval;
 938         char tcomm[sizeof(current->comm)];
 939
 940         /*
 941          * Make sure we have a private signal table and that
 942          * we are unassociated from the previous thread group.
 943          */
 944         retval = de_thread(current);
 945         if (retval)
 946                 goto out;
 947
 948         set_mm_exe_file(bprm->mm, bprm->file);
 949
 950         /*
 951          * Release all of the old mmap stuff
 952          */
 953         retval = exec_mmap(bprm->mm);
 954         if (retval)
 955                 goto out;
 956
 957         bprm->mm = NULL;                /* We're using it now */
 958
 959         /* This is the point of no return */
 960         current->sas_ss_sp = current->sas_ss_size = 0;
 961
 962         if (current_euid() == current_uid() && current_egid() == current_gid())
 963                 set_dumpable(current->mm, 1);
 964         else
 965                 set_dumpable(current->mm, suid_dumpable);
 966
 967         name = bprm->filename;
 968
 969         /* Copies the binary name from after last slash */
 970         for (i=0; (ch = *(name++)) != '\0';) {
 971                 if (ch == '/')
 972                         i = 0; /* overwrite what we wrote */
 973                 else
 974                         if (i < (sizeof(tcomm) - 1))
 975                                 tcomm[i++] = ch;
 976         }
 977         tcomm[i] = '\0';
 978         set_task_comm(current, tcomm);
 979
 980         current->flags &= ~PF_RANDOMIZE;
 981         flush_thread();
 982
 983         /* Set the new mm task size. We have to do that late because it may
 984          * depend on TIF_32BIT which is only updated in flush_thread() on
 985          * some architectures like powerpc
 986          */
 987         current->mm->task_size = TASK_SIZE;
 988
 989         /* install the new credentials */
 990         if (bprm->cred->uid != current_euid() ||
 991             bprm->cred->gid != current_egid()) {
 992                 current->pdeath_signal = 0;
 993         } else if (file_permission(bprm->file, MAY_READ) ||
 994                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
 995                 set_dumpable(current->mm, suid_dumpable);
 996         }
 997
 998         current->personality &= ~bprm->per_clear;
 999
1000         /*
1001          * Flush performance counters when crossing a
1002          * security domain:
1003          */
1004         if (!get_dumpable(current->mm))
1005                 perf_event_exit_task(current);
1006
1007         /* An exec changes our domain. We are no longer part of the thread
1008            group */
1009
1010         current->self_exec_id++;
1011
1012         flush_signal_handlers(current, 0);
1013         flush_old_files(current->files);
1014
1015         return 0;
1016
1017 out:
1018         return retval;
1019 }
1020
1021 EXPORT_SYMBOL(flush_old_exec);
1022
1023 /*
1024  * Prepare credentials and lock ->cred_guard_mutex.
1025  * install_exec_creds() commits the new creds and drops the lock.
1026  * Or, if exec fails before, free_bprm() should release ->cred and
1027  * and unlock.
1028  */
1029 int prepare_bprm_creds(struct linux_binprm *bprm)
1030 {
1031         if (mutex_lock_interruptible(&current->cred_guard_mutex))
1032                 return -ERESTARTNOINTR;
1033
1034         bprm->cred = prepare_exec_creds();
1035         if (likely(bprm->cred))
1036                 return 0;
1037
1038         mutex_unlock(&current->cred_guard_mutex);
1039         return -ENOMEM;
1040 }
1041
1042 void free_bprm(struct linux_binprm *bprm)
1043 {
1044         free_arg_pages(bprm);
1045         if (bprm->cred) {
1046                 mutex_unlock(&current->cred_guard_mutex);
1047                 abort_creds(bprm->cred);
1048         }
1049         kfree(bprm);
1050 }
1051
1052 /*
1053  * install the new credentials for this executable
1054  */
1055 void install_exec_creds(struct linux_binprm *bprm)
1056 {
1057         security_bprm_committing_creds(bprm);
1058
1059         commit_creds(bprm->cred);
1060         bprm->cred = NULL;
1061         /*
1062          * cred_guard_mutex must be held at least to this point to prevent
1063          * ptrace_attach() from altering our determination of the task's
1064          * credentials; any time after this it may be unlocked.
1065          */
1066         security_bprm_committed_creds(bprm);
1067         mutex_unlock(&current->cred_guard_mutex);
1068 }
1069 EXPORT_SYMBOL(install_exec_creds);
1070
1071 /*
1072  * determine how safe it is to execute the proposed program
1073  * - the caller must hold current->cred_guard_mutex to protect against
1074  *   PTRACE_ATTACH
1075  */
1076 int check_unsafe_exec(struct linux_binprm *bprm)
1077 {
1078         struct task_struct *p = current, *t;
1079         unsigned n_fs;
1080         int res = 0;
1081
1082         bprm->unsafe = tracehook_unsafe_exec(p);
1083
1084         n_fs = 1;
1085         write_lock(&p->fs->lock);
1086         rcu_read_lock();
1087         for (t = next_thread(p); t != p; t = next_thread(t)) {
1088                 if (t->fs == p->fs)
1089                         n_fs++;
1090         }
1091         rcu_read_unlock();
1092
1093         if (p->fs->users > n_fs) {
1094                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1095         } else {
1096                 res = -EAGAIN;
1097                 if (!p->fs->in_exec) {
1098                         p->fs->in_exec = 1;
1099                         res = 1;
1100                 }
1101         }
1102         write_unlock(&p->fs->lock);
1103
1104         return res;
1105 }
1106
1107 /*
1108  * Fill the binprm structure from the inode.
1109  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1110  *
1111  * This may be called multiple times for binary chains (scripts for example).
1112  */
1113 int prepare_binprm(struct linux_binprm *bprm)
1114 {
1115         umode_t mode;
1116         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1117         int retval;
1118
1119         mode = inode->i_mode;
1120         if (bprm->file->f_op == NULL)
1121                 return -EACCES;
1122
1123         /* clear any previous set[ug]id data from a previous binary */
1124         bprm->cred->euid = current_euid();
1125         bprm->cred->egid = current_egid();
1126
1127         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1128                 /* Set-uid? */
1129                 if (mode & S_ISUID) {
1130                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1131                         bprm->cred->euid = inode->i_uid;
1132                 }
1133
1134                 /* Set-gid? */
1135                 /*
1136                  * If setgid is set but no group execute bit then this
1137                  * is a candidate for mandatory locking, not a setgid
1138                  * executable.
1139                  */
1140                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1141                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1142                         bprm->cred->egid = inode->i_gid;
1143                 }
1144         }
1145
1146         /* fill in binprm security blob */
1147         retval = security_bprm_set_creds(bprm);
1148         if (retval)
1149                 return retval;
1150         bprm->cred_prepared = 1;
1151
1152         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1153         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1154 }
1155
1156 EXPORT_SYMBOL(prepare_binprm);
1157
1158 /*
1159  * Arguments are '\0' separated strings found at the location bprm->p
1160  * points to; chop off the first by relocating brpm->p to right after
1161  * the first '\0' encountered.
1162  */
1163 int remove_arg_zero(struct linux_binprm *bprm)
1164 {
1165         int ret = 0;
1166         unsigned long offset;
1167         char *kaddr;
1168         struct page *page;
1169
1170         if (!bprm->argc)
1171                 return 0;
1172
1173         do {
1174                 offset = bprm->p & ~PAGE_MASK;
1175                 page = get_arg_page(bprm, bprm->p, 0);
1176                 if (!page) {
1177                         ret = -EFAULT;
1178                         goto out;
1179                 }
1180                 kaddr = kmap_atomic(page, KM_USER0);
1181
1182                 for (; offset < PAGE_SIZE && kaddr[offset];
1183                                 offset++, bprm->p++)
1184                         ;
1185
1186                 kunmap_atomic(kaddr, KM_USER0);
1187                 put_arg_page(page);
1188
1189                 if (offset == PAGE_SIZE)
1190                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1191         } while (offset == PAGE_SIZE);
1192
1193         bprm->p++;
1194         bprm->argc--;
1195         ret = 0;
1196
1197 out:
1198         return ret;
1199 }
1200 EXPORT_SYMBOL(remove_arg_zero);
1201
1202 /*
1203  * cycle the list of binary formats handler, until one recognizes the image
1204  */
1205 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1206 {
1207         unsigned int depth = bprm->recursion_depth;
1208         int try,retval;
1209         struct linux_binfmt *fmt;
1210
1211         retval = security_bprm_check(bprm);
1212         if (retval)
1213                 return retval;
1214         retval = ima_bprm_check(bprm);
1215         if (retval)
1216                 return retval;
1217
1218         /* kernel module loader fixup */
1219         /* so we don't try to load run modprobe in kernel space. */
1220         set_fs(USER_DS);
1221
1222         retval = audit_bprm(bprm);
1223         if (retval)
1224                 return retval;
1225
1226         retval = -ENOENT;
1227         for (try=0; try<2; try++) {
1228                 read_lock(&binfmt_lock);
1229                 list_for_each_entry(fmt, &formats, lh) {
1230                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1231                         if (!fn)
1232                                 continue;
1233                         if (!try_module_get(fmt->module))
1234                                 continue;
1235                         read_unlock(&binfmt_lock);
1236                         retval = fn(bprm, regs);
1237                         /*
1238                          * Restore the depth counter to its starting value
1239                          * in this call, so we don't have to rely on every
1240                          * load_binary function to restore it on return.
1241                          */
1242                         bprm->recursion_depth = depth;
1243                         if (retval >= 0) {
1244                                 if (depth == 0)
1245                                         tracehook_report_exec(fmt, bprm, regs);
1246                                 put_binfmt(fmt);
1247                                 allow_write_access(bprm->file);
1248                                 if (bprm->file)
1249                                         fput(bprm->file);
1250                                 bprm->file = NULL;
1251                                 current->did_exec = 1;
1252                                 proc_exec_connector(current);
1253                                 return retval;
1254                         }
1255                         read_lock(&binfmt_lock);
1256                         put_binfmt(fmt);
1257                         if (retval != -ENOEXEC || bprm->mm == NULL)
1258                                 break;
1259                         if (!bprm->file) {
1260                                 read_unlock(&binfmt_lock);
1261                                 return retval;
1262                         }
1263                 }
1264                 read_unlock(&binfmt_lock);
1265                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1266                         break;
1267 #ifdef CONFIG_MODULES
1268                 } else {
1269 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1270                         if (printable(bprm->buf[0]) &&
1271                             printable(bprm->buf[1]) &&
1272                             printable(bprm->buf[2]) &&
1273                             printable(bprm->buf[3]))
1274                                 break; /* -ENOEXEC */
1275                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1276 #endif
1277                 }
1278         }
1279         return retval;
1280 }
1281
1282 EXPORT_SYMBOL(search_binary_handler);
1283
1284 /*
1285  * sys_execve() executes a new program.
1286  */
1287 int do_execve(char * filename,
1288         char __user *__user *argv,
1289         char __user *__user *envp,
1290         struct pt_regs * regs)
1291 {
1292         struct linux_binprm *bprm;
1293         struct file *file;
1294         struct files_struct *displaced;
1295         bool clear_in_exec;
1296         int retval;
1297
1298         retval = unshare_files(&displaced);
1299         if (retval)
1300                 goto out_ret;
1301
1302         retval = -ENOMEM;
1303         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1304         if (!bprm)
1305                 goto out_files;
1306
1307         retval = prepare_bprm_creds(bprm);
1308         if (retval)
1309                 goto out_free;
1310
1311         retval = check_unsafe_exec(bprm);
1312         if (retval < 0)
1313                 goto out_free;
1314         clear_in_exec = retval;
1315         current->in_execve = 1;
1316
1317         file = open_exec(filename);
1318         retval = PTR_ERR(file);
1319         if (IS_ERR(file))
1320                 goto out_unmark;
1321
1322         sched_exec();
1323
1324         bprm->file = file;
1325         bprm->filename = filename;
1326         bprm->interp = filename;
1327
1328         retval = bprm_mm_init(bprm);
1329         if (retval)
1330                 goto out_file;
1331
1332         bprm->argc = count(argv, MAX_ARG_STRINGS);
1333         if ((retval = bprm->argc) < 0)
1334                 goto out;
1335
1336         bprm->envc = count(envp, MAX_ARG_STRINGS);
1337         if ((retval = bprm->envc) < 0)
1338                 goto out;
1339
1340         retval = prepare_binprm(bprm);
1341         if (retval < 0)
1342                 goto out;
1343
1344         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1345         if (retval < 0)
1346                 goto out;
1347
1348         bprm->exec = bprm->p;
1349         retval = copy_strings(bprm->envc, envp, bprm);
1350         if (retval < 0)
1351                 goto out;
1352
1353         retval = copy_strings(bprm->argc, argv, bprm);
1354         if (retval < 0)
1355                 goto out;
1356
1357         current->flags &= ~PF_KTHREAD;
1358         retval = search_binary_handler(bprm,regs);
1359         if (retval < 0)
1360                 goto out;
1361
1362         current->stack_start = current->mm->start_stack;
1363
1364         /* execve succeeded */
1365         current->fs->in_exec = 0;
1366         current->in_execve = 0;
1367         acct_update_integrals(current);
1368         free_bprm(bprm);
1369         if (displaced)
1370                 put_files_struct(displaced);
1371         return retval;
1372
1373 out:
1374         if (bprm->mm)
1375                 mmput (bprm->mm);
1376
1377 out_file:
1378         if (bprm->file) {
1379                 allow_write_access(bprm->file);
1380                 fput(bprm->file);
1381         }
1382
1383 out_unmark:
1384         if (clear_in_exec)
1385                 current->fs->in_exec = 0;
1386         current->in_execve = 0;
1387
1388 out_free:
1389         free_bprm(bprm);
1390
1391 out_files:
1392         if (displaced)
1393                 reset_files_struct(displaced);
1394 out_ret:
1395         return retval;
1396 }
1397
1398 void set_binfmt(struct linux_binfmt *new)
1399 {
1400         struct mm_struct *mm = current->mm;
1401
1402         if (mm->binfmt)
1403                 module_put(mm->binfmt->module);
1404
1405         mm->binfmt = new;
1406         if (new)
1407                 __module_get(new->module);
1408 }
1409
1410 EXPORT_SYMBOL(set_binfmt);
1411
1412 /* format_corename will inspect the pattern parameter, and output a
1413  * name into corename, which must have space for at least
1414  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1415  */
1416 static int format_corename(char *corename, long signr)
1417 {
1418         const struct cred *cred = current_cred();
1419         const char *pat_ptr = core_pattern;
1420         int ispipe = (*pat_ptr == '|');
1421         char *out_ptr = corename;
1422         char *const out_end = corename + CORENAME_MAX_SIZE;
1423         int rc;
1424         int pid_in_pattern = 0;
1425
1426         /* Repeat as long as we have more pattern to process and more output
1427            space */
1428         while (*pat_ptr) {
1429                 if (*pat_ptr != '%') {
1430                         if (out_ptr == out_end)
1431                                 goto out;
1432                         *out_ptr++ = *pat_ptr++;
1433                 } else {
1434                         switch (*++pat_ptr) {
1435                         case 0:
1436                                 goto out;
1437                         /* Double percent, output one percent */
1438                         case '%':
1439                                 if (out_ptr == out_end)
1440                                         goto out;
1441                                 *out_ptr++ = '%';
1442                                 break;
1443                         /* pid */
1444                         case 'p':
1445                                 pid_in_pattern = 1;
1446                                 rc = snprintf(out_ptr, out_end - out_ptr,
1447                                               "%d", task_tgid_vnr(current));
1448                                 if (rc > out_end - out_ptr)
1449                                         goto out;
1450                                 out_ptr += rc;
1451                                 break;
1452                         /* uid */
1453                         case 'u':
1454                                 rc = snprintf(out_ptr, out_end - out_ptr,
1455                                               "%d", cred->uid);
1456                                 if (rc > out_end - out_ptr)
1457                                         goto out;
1458                                 out_ptr += rc;
1459                                 break;
1460                         /* gid */
1461                         case 'g':
1462                                 rc = snprintf(out_ptr, out_end - out_ptr,
1463                                               "%d", cred->gid);
1464                                 if (rc > out_end - out_ptr)
1465                                         goto out;
1466                                 out_ptr += rc;
1467                                 break;
1468                         /* signal that caused the coredump */
1469                         case 's':
1470                                 rc = snprintf(out_ptr, out_end - out_ptr,
1471                                               "%ld", signr);
1472                                 if (rc > out_end - out_ptr)
1473                                         goto out;
1474                                 out_ptr += rc;
1475                                 break;
1476                         /* UNIX time of coredump */
1477                         case 't': {
1478                                 struct timeval tv;
1479                                 do_gettimeofday(&tv);
1480                                 rc = snprintf(out_ptr, out_end - out_ptr,
1481                                               "%lu", tv.tv_sec);
1482                                 if (rc > out_end - out_ptr)
1483                                         goto out;
1484                                 out_ptr += rc;
1485                                 break;
1486                         }
1487                         /* hostname */
1488                         case 'h':
1489                                 down_read(&uts_sem);
1490                                 rc = snprintf(out_ptr, out_end - out_ptr,
1491                                               "%s", utsname()->nodename);
1492                                 up_read(&uts_sem);
1493                                 if (rc > out_end - out_ptr)
1494                                         goto out;
1495                                 out_ptr += rc;
1496                                 break;
1497                         /* executable */
1498                         case 'e':
1499                                 rc = snprintf(out_ptr, out_end - out_ptr,
1500                                               "%s", current->comm);
1501                                 if (rc > out_end - out_ptr)
1502                                         goto out;
1503                                 out_ptr += rc;
1504                                 break;
1505                         /* core limit size */
1506                         case 'c':
1507                                 rc = snprintf(out_ptr, out_end - out_ptr,
1508                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1509                                 if (rc > out_end - out_ptr)
1510                                         goto out;
1511                                 out_ptr += rc;
1512                                 break;
1513                         default:
1514                                 break;
1515                         }
1516                         ++pat_ptr;
1517                 }
1518         }
1519         /* Backward compatibility with core_uses_pid:
1520          *
1521          * If core_pattern does not include a %p (as is the default)
1522          * and core_uses_pid is set, then .%pid will be appended to
1523          * the filename. Do not do this for piped commands. */
1524         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1525                 rc = snprintf(out_ptr, out_end - out_ptr,
1526                               ".%d", task_tgid_vnr(current));
1527                 if (rc > out_end - out_ptr)
1528                         goto out;
1529                 out_ptr += rc;
1530         }
1531 out:
1532         *out_ptr = 0;
1533         return ispipe;
1534 }
1535
1536 static int zap_process(struct task_struct *start)
1537 {
1538         struct task_struct *t;
1539         int nr = 0;
1540
1541         start->signal->flags = SIGNAL_GROUP_EXIT;
1542         start->signal->group_stop_count = 0;
1543
1544         t = start;
1545         do {
1546                 if (t != current && t->mm) {
1547                         sigaddset(&t->pending.signal, SIGKILL);
1548                         signal_wake_up(t, 1);
1549                         nr++;
1550                 }
1551         } while_each_thread(start, t);
1552
1553         return nr;
1554 }
1555
1556 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1557                                 struct core_state *core_state, int exit_code)
1558 {
1559         struct task_struct *g, *p;
1560         unsigned long flags;
1561         int nr = -EAGAIN;
1562
1563         spin_lock_irq(&tsk->sighand->siglock);
1564         if (!signal_group_exit(tsk->signal)) {
1565                 mm->core_state = core_state;
1566                 tsk->signal->group_exit_code = exit_code;
1567                 nr = zap_process(tsk);
1568         }
1569         spin_unlock_irq(&tsk->sighand->siglock);
1570         if (unlikely(nr < 0))
1571                 return nr;
1572
1573         if (atomic_read(&mm->mm_users) == nr + 1)
1574                 goto done;
1575         /*
1576          * We should find and kill all tasks which use this mm, and we should
1577          * count them correctly into ->nr_threads. We don't take tasklist
1578          * lock, but this is safe wrt:
1579          *
1580          * fork:
1581          *      None of sub-threads can fork after zap_process(leader). All
1582          *      processes which were created before this point should be
1583          *      visible to zap_threads() because copy_process() adds the new
1584          *      process to the tail of init_task.tasks list, and lock/unlock
1585          *      of ->siglock provides a memory barrier.
1586          *
1587          * do_exit:
1588          *      The caller holds mm->mmap_sem. This means that the task which
1589          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1590          *      its ->mm.
1591          *
1592          * de_thread:
1593          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1594          *      we must see either old or new leader, this does not matter.
1595          *      However, it can change p->sighand, so lock_task_sighand(p)
1596          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1597          *      it can't fail.
1598          *
1599          *      Note also that "g" can be the old leader with ->mm == NULL
1600          *      and already unhashed and thus removed from ->thread_group.
1601          *      This is OK, __unhash_process()->list_del_rcu() does not
1602          *      clear the ->next pointer, we will find the new leader via
1603          *      next_thread().
1604          */
1605         rcu_read_lock();
1606         for_each_process(g) {
1607                 if (g == tsk->group_leader)
1608                         continue;
1609                 if (g->flags & PF_KTHREAD)
1610                         continue;
1611                 p = g;
1612                 do {
1613                         if (p->mm) {
1614                                 if (unlikely(p->mm == mm)) {
1615                                         lock_task_sighand(p, &flags);
1616                                         nr += zap_process(p);
1617                                         unlock_task_sighand(p, &flags);
1618                                 }
1619                                 break;
1620                         }
1621                 } while_each_thread(g, p);
1622         }
1623         rcu_read_unlock();
1624 done:
1625         atomic_set(&core_state->nr_threads, nr);
1626         return nr;
1627 }
1628
1629 static int coredump_wait(int exit_code, struct core_state *core_state)
1630 {
1631         struct task_struct *tsk = current;
1632         struct mm_struct *mm = tsk->mm;
1633         struct completion *vfork_done;
1634         int core_waiters;
1635
1636         init_completion(&core_state->startup);
1637         core_state->dumper.task = tsk;
1638         core_state->dumper.next = NULL;
1639         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1640         up_write(&mm->mmap_sem);
1641
1642         if (unlikely(core_waiters < 0))
1643                 goto fail;
1644
1645         /*
1646          * Make sure nobody is waiting for us to release the VM,
1647          * otherwise we can deadlock when we wait on each other
1648          */
1649         vfork_done = tsk->vfork_done;
1650         if (vfork_done) {
1651                 tsk->vfork_done = NULL;
1652                 complete(vfork_done);
1653         }
1654
1655         if (core_waiters)
1656                 wait_for_completion(&core_state->startup);
1657 fail:
1658         return core_waiters;
1659 }
1660
1661 static void coredump_finish(struct mm_struct *mm)
1662 {
1663         struct core_thread *curr, *next;
1664         struct task_struct *task;
1665
1666         next = mm->core_state->dumper.next;
1667         while ((curr = next) != NULL) {
1668                 next = curr->next;
1669                 task = curr->task;
1670                 /*
1671                  * see exit_mm(), curr->task must not see
1672                  * ->task == NULL before we read ->next.
1673                  */
1674                 smp_mb();
1675                 curr->task = NULL;
1676                 wake_up_process(task);
1677         }
1678
1679         mm->core_state = NULL;
1680 }
1681
1682 /*
1683  * set_dumpable converts traditional three-value dumpable to two flags and
1684  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1685  * these bits are not changed atomically.  So get_dumpable can observe the
1686  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1687  * return either old dumpable or new one by paying attention to the order of
1688  * modifying the bits.
1689  *
1690  * dumpable |   mm->flags (binary)
1691  * old  new | initial interim  final
1692  * ---------+-----------------------
1693  *  0    1  |   00      01      01
1694  *  0    2  |   00      10(*)   11
1695  *  1    0  |   01      00      00
1696  *  1    2  |   01      11      11
1697  *  2    0  |   11      10(*)   00
1698  *  2    1  |   11      11      01
1699  *
1700  * (*) get_dumpable regards interim value of 10 as 11.
1701  */
1702 void set_dumpable(struct mm_struct *mm, int value)
1703 {
1704         switch (value) {
1705         case 0:
1706                 clear_bit(MMF_DUMPABLE, &mm->flags);
1707                 smp_wmb();
1708                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1709                 break;
1710         case 1:
1711                 set_bit(MMF_DUMPABLE, &mm->flags);
1712                 smp_wmb();
1713                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1714                 break;
1715         case 2:
1716                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1717                 smp_wmb();
1718                 set_bit(MMF_DUMPABLE, &mm->flags);
1719                 break;
1720         }
1721 }
1722
1723 int get_dumpable(struct mm_struct *mm)
1724 {
1725         int ret;
1726
1727         ret = mm->flags & 0x3;
1728         return (ret >= 2) ? 2 : ret;
1729 }
1730
1731 static void wait_for_dump_helpers(struct file *file)
1732 {
1733         struct pipe_inode_info *pipe;
1734
1735         pipe = file->f_path.dentry->d_inode->i_pipe;
1736
1737         pipe_lock(pipe);
1738         pipe->readers++;
1739         pipe->writers--;
1740
1741         while ((pipe->readers > 1) && (!signal_pending(current))) {
1742                 wake_up_interruptible_sync(&pipe->wait);
1743                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1744                 pipe_wait(pipe);
1745         }
1746
1747         pipe->readers--;
1748         pipe->writers++;
1749         pipe_unlock(pipe);
1750
1751 }
1752
1753
1754 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1755 {
1756         struct core_state core_state;
1757         char corename[CORENAME_MAX_SIZE + 1];
1758         struct mm_struct *mm = current->mm;
1759         struct linux_binfmt * binfmt;
1760         struct inode * inode;
1761         struct file * file;
1762         const struct cred *old_cred;
1763         struct cred *cred;
1764         int retval = 0;
1765         int flag = 0;
1766         int ispipe = 0;
1767         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1768         char **helper_argv = NULL;
1769         int helper_argc = 0;
1770         int dump_count = 0;
1771         static atomic_t core_dump_count = ATOMIC_INIT(0);
1772
1773         audit_core_dumps(signr);
1774
1775         binfmt = mm->binfmt;
1776         if (!binfmt || !binfmt->core_dump)
1777                 goto fail;
1778
1779         cred = prepare_creds();
1780         if (!cred) {
1781                 retval = -ENOMEM;
1782                 goto fail;
1783         }
1784
1785         down_write(&mm->mmap_sem);
1786         /*
1787          * If another thread got here first, or we are not dumpable, bail out.
1788          */
1789         if (mm->core_state || !get_dumpable(mm)) {
1790                 up_write(&mm->mmap_sem);
1791                 put_cred(cred);
1792                 goto fail;
1793         }
1794
1795         /*
1796          *      We cannot trust fsuid as being the "true" uid of the
1797          *      process nor do we know its entire history. We only know it
1798          *      was tainted so we dump it as root in mode 2.
1799          */
1800         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1801                 flag = O_EXCL;          /* Stop rewrite attacks */
1802                 cred->fsuid = 0;        /* Dump root private */
1803         }
1804
1805         retval = coredump_wait(exit_code, &core_state);
1806         if (retval < 0) {
1807                 put_cred(cred);
1808                 goto fail;
1809         }
1810
1811         old_cred = override_creds(cred);
1812
1813         /*
1814          * Clear any false indication of pending signals that might
1815          * be seen by the filesystem code called to write the core file.
1816          */
1817         clear_thread_flag(TIF_SIGPENDING);
1818
1819         /*
1820          * lock_kernel() because format_corename() is controlled by sysctl, which
1821          * uses lock_kernel()
1822          */
1823         lock_kernel();
1824         ispipe = format_corename(corename, signr);
1825         unlock_kernel();
1826
1827         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1828                 goto fail_unlock;
1829
1830         if (ispipe) {
1831                 if (core_limit == 0) {
1832                         /*
1833                          * Normally core limits are irrelevant to pipes, since
1834                          * we're not writing to the file system, but we use
1835                          * core_limit of 0 here as a speacial value. Any
1836                          * non-zero limit gets set to RLIM_INFINITY below, but
1837                          * a limit of 0 skips the dump.  This is a consistent
1838                          * way to catch recursive crashes.  We can still crash
1839                          * if the core_pattern binary sets RLIM_CORE =  !0
1840                          * but it runs as root, and can do lots of stupid things
1841                          * Note that we use task_tgid_vnr here to grab the pid
1842                          * of the process group leader.  That way we get the
1843                          * right pid if a thread in a multi-threaded
1844                          * core_pattern process dies.
1845                          */
1846                         printk(KERN_WARNING
1847                                 "Process %d(%s) has RLIMIT_CORE set to 0\n",
1848                                 task_tgid_vnr(current), current->comm);
1849                         printk(KERN_WARNING "Aborting core\n");
1850                         goto fail_unlock;
1851                 }
1852
1853                 dump_count = atomic_inc_return(&core_dump_count);
1854                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
1855                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
1856                                task_tgid_vnr(current), current->comm);
1857                         printk(KERN_WARNING "Skipping core dump\n");
1858                         goto fail_dropcount;
1859                 }
1860
1861                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1862                 if (!helper_argv) {
1863                         printk(KERN_WARNING "%s failed to allocate memory\n",
1864                                __func__);
1865                         goto fail_dropcount;
1866                 }
1867
1868                 core_limit = RLIM_INFINITY;
1869
1870                 /* SIGPIPE can happen, but it's just never processed */
1871                 if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
1872                                 &file)) {
1873                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1874                                corename);
1875                         goto fail_dropcount;
1876                 }
1877         } else
1878                 file = filp_open(corename,
1879                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1880                                  0600);
1881         if (IS_ERR(file))
1882                 goto fail_dropcount;
1883         inode = file->f_path.dentry->d_inode;
1884         if (inode->i_nlink > 1)
1885                 goto close_fail;        /* multiple links - don't dump */
1886         if (!ispipe && d_unhashed(file->f_path.dentry))
1887                 goto close_fail;
1888
1889         /* AK: actually i see no reason to not allow this for named pipes etc.,
1890            but keep the previous behaviour for now. */
1891         if (!ispipe && !S_ISREG(inode->i_mode))
1892                 goto close_fail;
1893         /*
1894          * Dont allow local users get cute and trick others to coredump
1895          * into their pre-created files:
1896          */
1897         if (inode->i_uid != current_fsuid())
1898                 goto close_fail;
1899         if (!file->f_op)
1900                 goto close_fail;
1901         if (!file->f_op->write)
1902                 goto close_fail;
1903         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1904                 goto close_fail;
1905
1906         retval = binfmt->core_dump(signr, regs, file, core_limit);
1907
1908         if (retval)
1909                 current->signal->group_exit_code |= 0x80;
1910 close_fail:
1911         if (ispipe && core_pipe_limit)
1912                 wait_for_dump_helpers(file);
1913         filp_close(file, NULL);
1914 fail_dropcount:
1915         if (dump_count)
1916                 atomic_dec(&core_dump_count);
1917 fail_unlock:
1918         if (helper_argv)
1919                 argv_free(helper_argv);
1920
1921         revert_creds(old_cred);
1922         put_cred(cred);
1923         coredump_finish(mm);
1924 fail:
1925         return;
1926 }