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                         cond_resched();
 423
 424                         offset = pos % PAGE_SIZE;
 425                         if (offset == 0)
 426                                 offset = PAGE_SIZE;
 427
 428                         bytes_to_copy = offset;
 429                         if (bytes_to_copy > len)
 430                                 bytes_to_copy = len;
 431
 432                         offset -= bytes_to_copy;
 433                         pos -= bytes_to_copy;
 434                         str -= bytes_to_copy;
 435                         len -= bytes_to_copy;
 436
 437                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 438                                 struct page *page;
 439
 440                                 page = get_arg_page(bprm, pos, 1);
 441                                 if (!page) {
 442                                         ret = -E2BIG;
 443                                         goto out;
 444                                 }
 445
 446                                 if (kmapped_page) {
 447                                         flush_kernel_dcache_page(kmapped_page);
 448                                         kunmap(kmapped_page);
 449                                         put_arg_page(kmapped_page);
 450                                 }
 451                                 kmapped_page = page;
 452                                 kaddr = kmap(kmapped_page);
 453                                 kpos = pos & PAGE_MASK;
 454                                 flush_arg_page(bprm, kpos, kmapped_page);
 455                         }
 456                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 457                                 ret = -EFAULT;
 458                                 goto out;
 459                         }
 460                 }
 461         }
 462         ret = 0;
 463 out:
 464         if (kmapped_page) {
 465                 flush_kernel_dcache_page(kmapped_page);
 466                 kunmap(kmapped_page);
 467                 put_arg_page(kmapped_page);
 468         }
 469         return ret;
 470 }
 471
 472 /*
 473  * Like copy_strings, but get argv and its values from kernel memory.
 474  */
 475 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
 476 {
 477         int r;
 478         mm_segment_t oldfs = get_fs();
 479         set_fs(KERNEL_DS);
 480         r = copy_strings(argc, (char __user * __user *)argv, bprm);
 481         set_fs(oldfs);
 482         return r;
 483 }
 484 EXPORT_SYMBOL(copy_strings_kernel);
 485
 486 #ifdef CONFIG_MMU
 487
 488 /*
 489  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 490  * the binfmt code determines where the new stack should reside, we shift it to
 491  * its final location.  The process proceeds as follows:
 492  *
 493  * 1) Use shift to calculate the new vma endpoints.
 494  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 495  *    arguments passed to subsequent functions are consistent.
 496  * 3) Move vma's page tables to the new range.
 497  * 4) Free up any cleared pgd range.
 498  * 5) Shrink the vma to cover only the new range.
 499  */
 500 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 501 {
 502         struct mm_struct *mm = vma->vm_mm;
 503         unsigned long old_start = vma->vm_start;
 504         unsigned long old_end = vma->vm_end;
 505         unsigned long length = old_end - old_start;
 506         unsigned long new_start = old_start - shift;
 507         unsigned long new_end = old_end - shift;
 508         struct mmu_gather *tlb;
 509
 510         BUG_ON(new_start > new_end);
 511
 512         /*
 513          * ensure there are no vmas between where we want to go
 514          * and where we are
 515          */
 516         if (vma != find_vma(mm, new_start))
 517                 return -EFAULT;
 518
 519         /*
 520          * cover the whole range: [new_start, old_end)
 521          */
 522         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
 523
 524         /*
 525          * move the page tables downwards, on failure we rely on
 526          * process cleanup to remove whatever mess we made.
 527          */
 528         if (length != move_page_tables(vma, old_start,
 529                                        vma, new_start, length))
 530                 return -ENOMEM;
 531
 532         lru_add_drain();
 533         tlb = tlb_gather_mmu(mm, 0);
 534         if (new_end > old_start) {
 535                 /*
 536                  * when the old and new regions overlap clear from new_end.
 537                  */
 538                 free_pgd_range(tlb, new_end, old_end, new_end,
 539                         vma->vm_next ? vma->vm_next->vm_start : 0);
 540         } else {
 541                 /*
 542                  * otherwise, clean from old_start; this is done to not touch
 543                  * the address space in [new_end, old_start) some architectures
 544                  * have constraints on va-space that make this illegal (IA64) -
 545                  * for the others its just a little faster.
 546                  */
 547                 free_pgd_range(tlb, old_start, old_end, new_end,
 548                         vma->vm_next ? vma->vm_next->vm_start : 0);
 549         }
 550         tlb_finish_mmu(tlb, new_end, old_end);
 551
 552         /*
 553          * shrink the vma to just the new range.
 554          */
 555         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 556
 557         return 0;
 558 }
 559
 560 #define EXTRA_STACK_VM_PAGES    20      /* random */
 561
 562 /*
 563  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 564  * the stack is optionally relocated, and some extra space is added.
 565  */
 566 int setup_arg_pages(struct linux_binprm *bprm,
 567                     unsigned long stack_top,
 568                     int executable_stack)
 569 {
 570         unsigned long ret;
 571         unsigned long stack_shift;
 572         struct mm_struct *mm = current->mm;
 573         struct vm_area_struct *vma = bprm->vma;
 574         struct vm_area_struct *prev = NULL;
 575         unsigned long vm_flags;
 576         unsigned long stack_base;
 577         unsigned long stack_size;
 578         unsigned long stack_expand;
 579         unsigned long rlim_stack;
 580
 581 #ifdef CONFIG_STACK_GROWSUP
 582         /* Limit stack size to 1GB */
 583         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
 584         if (stack_base > (1 << 30))
 585                 stack_base = 1 << 30;
 586
 587         /* Make sure we didn't let the argument array grow too large. */
 588         if (vma->vm_end - vma->vm_start > stack_base)
 589                 return -ENOMEM;
 590
 591         stack_base = PAGE_ALIGN(stack_top - stack_base);
 592
 593         stack_shift = vma->vm_start - stack_base;
 594         mm->arg_start = bprm->p - stack_shift;
 595         bprm->p = vma->vm_end - stack_shift;
 596 #else
 597         stack_top = arch_align_stack(stack_top);
 598         stack_top = PAGE_ALIGN(stack_top);
 599
 600         if (unlikely(stack_top < mmap_min_addr) ||
 601             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 602                 return -ENOMEM;
 603
 604         stack_shift = vma->vm_end - stack_top;
 605
 606         bprm->p -= stack_shift;
 607         mm->arg_start = bprm->p;
 608 #endif
 609
 610         if (bprm->loader)
 611                 bprm->loader -= stack_shift;
 612         bprm->exec -= stack_shift;
 613
 614         down_write(&mm->mmap_sem);
 615         vm_flags = VM_STACK_FLAGS;
 616
 617         /*
 618          * Adjust stack execute permissions; explicitly enable for
 619          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 620          * (arch default) otherwise.
 621          */
 622         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 623                 vm_flags |= VM_EXEC;
 624         else if (executable_stack == EXSTACK_DISABLE_X)
 625                 vm_flags &= ~VM_EXEC;
 626         vm_flags |= mm->def_flags;
 627
 628         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 629                         vm_flags);
 630         if (ret)
 631                 goto out_unlock;
 632         BUG_ON(prev != vma);
 633
 634         /* Move stack pages down in memory. */
 635         if (stack_shift) {
 636                 ret = shift_arg_pages(vma, stack_shift);
 637                 if (ret)
 638                         goto out_unlock;
 639         }
 640
 641         stack_expand = EXTRA_STACK_VM_PAGES * PAGE_SIZE;
 642         stack_size = vma->vm_end - vma->vm_start;
 643         /*
 644          * Align this down to a page boundary as expand_stack
 645          * will align it up.
 646          */
 647         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 648 #ifdef CONFIG_STACK_GROWSUP
 649         if (stack_size + stack_expand > rlim_stack)
 650                 stack_base = vma->vm_start + rlim_stack;
 651         else
 652                 stack_base = vma->vm_end + stack_expand;
 653 #else
 654         if (stack_size + stack_expand > rlim_stack)
 655                 stack_base = vma->vm_end - rlim_stack;
 656         else
 657                 stack_base = vma->vm_start - stack_expand;
 658 #endif
 659         ret = expand_stack(vma, stack_base);
 660         if (ret)
 661                 ret = -EFAULT;
 662
 663 out_unlock:
 664         up_write(&mm->mmap_sem);
 665         return ret;
 666 }
 667 EXPORT_SYMBOL(setup_arg_pages);
 668
 669 #endif /* CONFIG_MMU */
 670
 671 struct file *open_exec(const char *name)
 672 {
 673         struct file *file;
 674         int err;
 675
 676         file = do_filp_open(AT_FDCWD, name,
 677                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
 678                                 MAY_EXEC | MAY_OPEN);
 679         if (IS_ERR(file))
 680                 goto out;
 681
 682         err = -EACCES;
 683         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 684                 goto exit;
 685
 686         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 687                 goto exit;
 688
 689         fsnotify_open(file->f_path.dentry);
 690
 691         err = deny_write_access(file);
 692         if (err)
 693                 goto exit;
 694
 695 out:
 696         return file;
 697
 698 exit:
 699         fput(file);
 700         return ERR_PTR(err);
 701 }
 702 EXPORT_SYMBOL(open_exec);
 703
 704 int kernel_read(struct file *file, loff_t offset,
 705                 char *addr, unsigned long count)
 706 {
 707         mm_segment_t old_fs;
 708         loff_t pos = offset;
 709         int result;
 710
 711         old_fs = get_fs();
 712         set_fs(get_ds());
 713         /* The cast to a user pointer is valid due to the set_fs() */
 714         result = vfs_read(file, (void __user *)addr, count, &pos);
 715         set_fs(old_fs);
 716         return result;
 717 }
 718
 719 EXPORT_SYMBOL(kernel_read);
 720
 721 static int exec_mmap(struct mm_struct *mm)
 722 {
 723         struct task_struct *tsk;
 724         struct mm_struct * old_mm, *active_mm;
 725
 726         /* Notify parent that we're no longer interested in the old VM */
 727         tsk = current;
 728         old_mm = current->mm;
 729         mm_release(tsk, old_mm);
 730
 731         if (old_mm) {
 732                 /*
 733                  * Make sure that if there is a core dump in progress
 734                  * for the old mm, we get out and die instead of going
 735                  * through with the exec.  We must hold mmap_sem around
 736                  * checking core_state and changing tsk->mm.
 737                  */
 738                 down_read(&old_mm->mmap_sem);
 739                 if (unlikely(old_mm->core_state)) {
 740                         up_read(&old_mm->mmap_sem);
 741                         return -EINTR;
 742                 }
 743         }
 744         task_lock(tsk);
 745         active_mm = tsk->active_mm;
 746         tsk->mm = mm;
 747         tsk->active_mm = mm;
 748         activate_mm(active_mm, mm);
 749         task_unlock(tsk);
 750         arch_pick_mmap_layout(mm);
 751         if (old_mm) {
 752                 up_read(&old_mm->mmap_sem);
 753                 BUG_ON(active_mm != old_mm);
 754                 mm_update_next_owner(old_mm);
 755                 mmput(old_mm);
 756                 return 0;
 757         }
 758         mmdrop(active_mm);
 759         return 0;
 760 }
 761
 762 /*
 763  * This function makes sure the current process has its own signal table,
 764  * so that flush_signal_handlers can later reset the handlers without
 765  * disturbing other processes.  (Other processes might share the signal
 766  * table via the CLONE_SIGHAND option to clone().)
 767  */
 768 static int de_thread(struct task_struct *tsk)
 769 {
 770         struct signal_struct *sig = tsk->signal;
 771         struct sighand_struct *oldsighand = tsk->sighand;
 772         spinlock_t *lock = &oldsighand->siglock;
 773         int count;
 774
 775         if (thread_group_empty(tsk))
 776                 goto no_thread_group;
 777
 778         /*
 779          * Kill all other threads in the thread group.
 780          */
 781         spin_lock_irq(lock);
 782         if (signal_group_exit(sig)) {
 783                 /*
 784                  * Another group action in progress, just
 785                  * return so that the signal is processed.
 786                  */
 787                 spin_unlock_irq(lock);
 788                 return -EAGAIN;
 789         }
 790         sig->group_exit_task = tsk;
 791         zap_other_threads(tsk);
 792
 793         /* Account for the thread group leader hanging around: */
 794         count = thread_group_leader(tsk) ? 1 : 2;
 795         sig->notify_count = count;
 796         while (atomic_read(&sig->count) > count) {
 797                 __set_current_state(TASK_UNINTERRUPTIBLE);
 798                 spin_unlock_irq(lock);
 799                 schedule();
 800                 spin_lock_irq(lock);
 801         }
 802         spin_unlock_irq(lock);
 803
 804         /*
 805          * At this point all other threads have exited, all we have to
 806          * do is to wait for the thread group leader to become inactive,
 807          * and to assume its PID:
 808          */
 809         if (!thread_group_leader(tsk)) {
 810                 struct task_struct *leader = tsk->group_leader;
 811
 812                 sig->notify_count = -1; /* for exit_notify() */
 813                 for (;;) {
 814                         write_lock_irq(&tasklist_lock);
 815                         if (likely(leader->exit_state))
 816                                 break;
 817                         __set_current_state(TASK_UNINTERRUPTIBLE);
 818                         write_unlock_irq(&tasklist_lock);
 819                         schedule();
 820                 }
 821
 822                 /*
 823                  * The only record we have of the real-time age of a
 824                  * process, regardless of execs it's done, is start_time.
 825                  * All the past CPU time is accumulated in signal_struct
 826                  * from sister threads now dead.  But in this non-leader
 827                  * exec, nothing survives from the original leader thread,
 828                  * whose birth marks the true age of this process now.
 829                  * When we take on its identity by switching to its PID, we
 830                  * also take its birthdate (always earlier than our own).
 831                  */
 832                 tsk->start_time = leader->start_time;
 833
 834                 BUG_ON(!same_thread_group(leader, tsk));
 835                 BUG_ON(has_group_leader_pid(tsk));
 836                 /*
 837                  * An exec() starts a new thread group with the
 838                  * TGID of the previous thread group. Rehash the
 839                  * two threads with a switched PID, and release
 840                  * the former thread group leader:
 841                  */
 842
 843                 /* Become a process group leader with the old leader's pid.
 844                  * The old leader becomes a thread of the this thread group.
 845                  * Note: The old leader also uses this pid until release_task
 846                  *       is called.  Odd but simple and correct.
 847                  */
 848                 detach_pid(tsk, PIDTYPE_PID);
 849                 tsk->pid = leader->pid;
 850                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 851                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 852                 transfer_pid(leader, tsk, PIDTYPE_SID);
 853                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 854
 855                 tsk->group_leader = tsk;
 856                 leader->group_leader = tsk;
 857
 858                 tsk->exit_signal = SIGCHLD;
 859
 860                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 861                 leader->exit_state = EXIT_DEAD;
 862                 write_unlock_irq(&tasklist_lock);
 863
 864                 release_task(leader);
 865         }
 866
 867         sig->group_exit_task = NULL;
 868         sig->notify_count = 0;
 869
 870 no_thread_group:
 871         if (current->mm)
 872                 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
 873
 874         exit_itimers(sig);
 875         flush_itimer_signals();
 876
 877         if (atomic_read(&oldsighand->count) != 1) {
 878                 struct sighand_struct *newsighand;
 879                 /*
 880                  * This ->sighand is shared with the CLONE_SIGHAND
 881                  * but not CLONE_THREAD task, switch to the new one.
 882                  */
 883                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 884                 if (!newsighand)
 885                         return -ENOMEM;
 886
 887                 atomic_set(&newsighand->count, 1);
 888                 memcpy(newsighand->action, oldsighand->action,
 889                        sizeof(newsighand->action));
 890
 891                 write_lock_irq(&tasklist_lock);
 892                 spin_lock(&oldsighand->siglock);
 893                 rcu_assign_pointer(tsk->sighand, newsighand);
 894                 spin_unlock(&oldsighand->siglock);
 895                 write_unlock_irq(&tasklist_lock);
 896
 897                 __cleanup_sighand(oldsighand);
 898         }
 899
 900         BUG_ON(!thread_group_leader(tsk));
 901         return 0;
 902 }
 903
 904 /*
 905  * These functions flushes out all traces of the currently running executable
 906  * so that a new one can be started
 907  */
 908 static void flush_old_files(struct files_struct * files)
 909 {
 910         long j = -1;
 911         struct fdtable *fdt;
 912
 913         spin_lock(&files->file_lock);
 914         for (;;) {
 915                 unsigned long set, i;
 916
 917                 j++;
 918                 i = j * __NFDBITS;
 919                 fdt = files_fdtable(files);
 920                 if (i >= fdt->max_fds)
 921                         break;
 922                 set = fdt->close_on_exec->fds_bits[j];
 923                 if (!set)
 924                         continue;
 925                 fdt->close_on_exec->fds_bits[j] = 0;
 926                 spin_unlock(&files->file_lock);
 927                 for ( ; set ; i++,set >>= 1) {
 928                         if (set & 1) {
 929                                 sys_close(i);
 930                         }
 931                 }
 932                 spin_lock(&files->file_lock);
 933
 934         }
 935         spin_unlock(&files->file_lock);
 936 }
 937
 938 char *get_task_comm(char *buf, struct task_struct *tsk)
 939 {
 940         /* buf must be at least sizeof(tsk->comm) in size */
 941         task_lock(tsk);
 942         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 943         task_unlock(tsk);
 944         return buf;
 945 }
 946
 947 void set_task_comm(struct task_struct *tsk, char *buf)
 948 {
 949         task_lock(tsk);
 950         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
 951         task_unlock(tsk);
 952         perf_event_comm(tsk);
 953 }
 954
 955 int flush_old_exec(struct linux_binprm * bprm)
 956 {
 957         int retval;
 958
 959         /*
 960          * Make sure we have a private signal table and that
 961          * we are unassociated from the previous thread group.
 962          */
 963         retval = de_thread(current);
 964         if (retval)
 965                 goto out;
 966
 967         set_mm_exe_file(bprm->mm, bprm->file);
 968
 969         /*
 970          * Release all of the old mmap stuff
 971          */
 972         retval = exec_mmap(bprm->mm);
 973         if (retval)
 974                 goto out;
 975
 976         bprm->mm = NULL;                /* We're using it now */
 977
 978         current->flags &= ~PF_RANDOMIZE;
 979         flush_thread();
 980         current->personality &= ~bprm->per_clear;
 981
 982         return 0;
 983
 984 out:
 985         return retval;
 986 }
 987 EXPORT_SYMBOL(flush_old_exec);
 988
 989 void setup_new_exec(struct linux_binprm * bprm)
 990 {
 991         int i, ch;
 992         char * name;
 993         char tcomm[sizeof(current->comm)];
 994
 995         arch_pick_mmap_layout(current->mm);
 996
 997         /* This is the point of no return */
 998         current->sas_ss_sp = current->sas_ss_size = 0;
 999
1000         if (current_euid() == current_uid() && current_egid() == current_gid())
1001                 set_dumpable(current->mm, 1);
1002         else
1003                 set_dumpable(current->mm, suid_dumpable);
1004
1005         name = bprm->filename;
1006
1007         /* Copies the binary name from after last slash */
1008         for (i=0; (ch = *(name++)) != '\0';) {
1009                 if (ch == '/')
1010                         i = 0; /* overwrite what we wrote */
1011                 else
1012                         if (i < (sizeof(tcomm) - 1))
1013                                 tcomm[i++] = ch;
1014         }
1015         tcomm[i] = '\0';
1016         set_task_comm(current, tcomm);
1017
1018         /* Set the new mm task size. We have to do that late because it may
1019          * depend on TIF_32BIT which is only updated in flush_thread() on
1020          * some architectures like powerpc
1021          */
1022         current->mm->task_size = TASK_SIZE;
1023
1024         /* install the new credentials */
1025         if (bprm->cred->uid != current_euid() ||
1026             bprm->cred->gid != current_egid()) {
1027                 current->pdeath_signal = 0;
1028         } else if (file_permission(bprm->file, MAY_READ) ||
1029                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1030                 set_dumpable(current->mm, suid_dumpable);
1031         }
1032
1033         /*
1034          * Flush performance counters when crossing a
1035          * security domain:
1036          */
1037         if (!get_dumpable(current->mm))
1038                 perf_event_exit_task(current);
1039
1040         /* An exec changes our domain. We are no longer part of the thread
1041            group */
1042
1043         current->self_exec_id++;
1044
1045         flush_signal_handlers(current, 0);
1046         flush_old_files(current->files);
1047 }
1048 EXPORT_SYMBOL(setup_new_exec);
1049
1050 /*
1051  * Prepare credentials and lock ->cred_guard_mutex.
1052  * install_exec_creds() commits the new creds and drops the lock.
1053  * Or, if exec fails before, free_bprm() should release ->cred and
1054  * and unlock.
1055  */
1056 int prepare_bprm_creds(struct linux_binprm *bprm)
1057 {
1058         if (mutex_lock_interruptible(&current->cred_guard_mutex))
1059                 return -ERESTARTNOINTR;
1060
1061         bprm->cred = prepare_exec_creds();
1062         if (likely(bprm->cred))
1063                 return 0;
1064
1065         mutex_unlock(&current->cred_guard_mutex);
1066         return -ENOMEM;
1067 }
1068
1069 void free_bprm(struct linux_binprm *bprm)
1070 {
1071         free_arg_pages(bprm);
1072         if (bprm->cred) {
1073                 mutex_unlock(&current->cred_guard_mutex);
1074                 abort_creds(bprm->cred);
1075         }
1076         kfree(bprm);
1077 }
1078
1079 /*
1080  * install the new credentials for this executable
1081  */
1082 void install_exec_creds(struct linux_binprm *bprm)
1083 {
1084         security_bprm_committing_creds(bprm);
1085
1086         commit_creds(bprm->cred);
1087         bprm->cred = NULL;
1088         /*
1089          * cred_guard_mutex must be held at least to this point to prevent
1090          * ptrace_attach() from altering our determination of the task's
1091          * credentials; any time after this it may be unlocked.
1092          */
1093         security_bprm_committed_creds(bprm);
1094         mutex_unlock(&current->cred_guard_mutex);
1095 }
1096 EXPORT_SYMBOL(install_exec_creds);
1097
1098 /*
1099  * determine how safe it is to execute the proposed program
1100  * - the caller must hold current->cred_guard_mutex to protect against
1101  *   PTRACE_ATTACH
1102  */
1103 int check_unsafe_exec(struct linux_binprm *bprm)
1104 {
1105         struct task_struct *p = current, *t;
1106         unsigned n_fs;
1107         int res = 0;
1108
1109         bprm->unsafe = tracehook_unsafe_exec(p);
1110
1111         n_fs = 1;
1112         write_lock(&p->fs->lock);
1113         rcu_read_lock();
1114         for (t = next_thread(p); t != p; t = next_thread(t)) {
1115                 if (t->fs == p->fs)
1116                         n_fs++;
1117         }
1118         rcu_read_unlock();
1119
1120         if (p->fs->users > n_fs) {
1121                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1122         } else {
1123                 res = -EAGAIN;
1124                 if (!p->fs->in_exec) {
1125                         p->fs->in_exec = 1;
1126                         res = 1;
1127                 }
1128         }
1129         write_unlock(&p->fs->lock);
1130
1131         return res;
1132 }
1133
1134 /*
1135  * Fill the binprm structure from the inode.
1136  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1137  *
1138  * This may be called multiple times for binary chains (scripts for example).
1139  */
1140 int prepare_binprm(struct linux_binprm *bprm)
1141 {
1142         umode_t mode;
1143         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1144         int retval;
1145
1146         mode = inode->i_mode;
1147         if (bprm->file->f_op == NULL)
1148                 return -EACCES;
1149
1150         /* clear any previous set[ug]id data from a previous binary */
1151         bprm->cred->euid = current_euid();
1152         bprm->cred->egid = current_egid();
1153
1154         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1155                 /* Set-uid? */
1156                 if (mode & S_ISUID) {
1157                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1158                         bprm->cred->euid = inode->i_uid;
1159                 }
1160
1161                 /* Set-gid? */
1162                 /*
1163                  * If setgid is set but no group execute bit then this
1164                  * is a candidate for mandatory locking, not a setgid
1165                  * executable.
1166                  */
1167                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1168                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1169                         bprm->cred->egid = inode->i_gid;
1170                 }
1171         }
1172
1173         /* fill in binprm security blob */
1174         retval = security_bprm_set_creds(bprm);
1175         if (retval)
1176                 return retval;
1177         bprm->cred_prepared = 1;
1178
1179         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1180         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1181 }
1182
1183 EXPORT_SYMBOL(prepare_binprm);
1184
1185 /*
1186  * Arguments are '\0' separated strings found at the location bprm->p
1187  * points to; chop off the first by relocating brpm->p to right after
1188  * the first '\0' encountered.
1189  */
1190 int remove_arg_zero(struct linux_binprm *bprm)
1191 {
1192         int ret = 0;
1193         unsigned long offset;
1194         char *kaddr;
1195         struct page *page;
1196
1197         if (!bprm->argc)
1198                 return 0;
1199
1200         do {
1201                 offset = bprm->p & ~PAGE_MASK;
1202                 page = get_arg_page(bprm, bprm->p, 0);
1203                 if (!page) {
1204                         ret = -EFAULT;
1205                         goto out;
1206                 }
1207                 kaddr = kmap_atomic(page, KM_USER0);
1208
1209                 for (; offset < PAGE_SIZE && kaddr[offset];
1210                                 offset++, bprm->p++)
1211                         ;
1212
1213                 kunmap_atomic(kaddr, KM_USER0);
1214                 put_arg_page(page);
1215
1216                 if (offset == PAGE_SIZE)
1217                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1218         } while (offset == PAGE_SIZE);
1219
1220         bprm->p++;
1221         bprm->argc--;
1222         ret = 0;
1223
1224 out:
1225         return ret;
1226 }
1227 EXPORT_SYMBOL(remove_arg_zero);
1228
1229 /*
1230  * cycle the list of binary formats handler, until one recognizes the image
1231  */
1232 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1233 {
1234         unsigned int depth = bprm->recursion_depth;
1235         int try,retval;
1236         struct linux_binfmt *fmt;
1237
1238         retval = security_bprm_check(bprm);
1239         if (retval)
1240                 return retval;
1241         retval = ima_bprm_check(bprm);
1242         if (retval)
1243                 return retval;
1244
1245         /* kernel module loader fixup */
1246         /* so we don't try to load run modprobe in kernel space. */
1247         set_fs(USER_DS);
1248
1249         retval = audit_bprm(bprm);
1250         if (retval)
1251                 return retval;
1252
1253         retval = -ENOENT;
1254         for (try=0; try<2; try++) {
1255                 read_lock(&binfmt_lock);
1256                 list_for_each_entry(fmt, &formats, lh) {
1257                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1258                         if (!fn)
1259                                 continue;
1260                         if (!try_module_get(fmt->module))
1261                                 continue;
1262                         read_unlock(&binfmt_lock);
1263                         retval = fn(bprm, regs);
1264                         /*
1265                          * Restore the depth counter to its starting value
1266                          * in this call, so we don't have to rely on every
1267                          * load_binary function to restore it on return.
1268                          */
1269                         bprm->recursion_depth = depth;
1270                         if (retval >= 0) {
1271                                 if (depth == 0)
1272                                         tracehook_report_exec(fmt, bprm, regs);
1273                                 put_binfmt(fmt);
1274                                 allow_write_access(bprm->file);
1275                                 if (bprm->file)
1276                                         fput(bprm->file);
1277                                 bprm->file = NULL;
1278                                 current->did_exec = 1;
1279                                 proc_exec_connector(current);
1280                                 return retval;
1281                         }
1282                         read_lock(&binfmt_lock);
1283                         put_binfmt(fmt);
1284                         if (retval != -ENOEXEC || bprm->mm == NULL)
1285                                 break;
1286                         if (!bprm->file) {
1287                                 read_unlock(&binfmt_lock);
1288                                 return retval;
1289                         }
1290                 }
1291                 read_unlock(&binfmt_lock);
1292                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1293                         break;
1294 #ifdef CONFIG_MODULES
1295                 } else {
1296 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1297                         if (printable(bprm->buf[0]) &&
1298                             printable(bprm->buf[1]) &&
1299                             printable(bprm->buf[2]) &&
1300                             printable(bprm->buf[3]))
1301                                 break; /* -ENOEXEC */
1302                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1303 #endif
1304                 }
1305         }
1306         return retval;
1307 }
1308
1309 EXPORT_SYMBOL(search_binary_handler);
1310
1311 /*
1312  * sys_execve() executes a new program.
1313  */
1314 int do_execve(char * filename,
1315         char __user *__user *argv,
1316         char __user *__user *envp,
1317         struct pt_regs * regs)
1318 {
1319         struct linux_binprm *bprm;
1320         struct file *file;
1321         struct files_struct *displaced;
1322         bool clear_in_exec;
1323         int retval;
1324
1325         retval = unshare_files(&displaced);
1326         if (retval)
1327                 goto out_ret;
1328
1329         retval = -ENOMEM;
1330         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1331         if (!bprm)
1332                 goto out_files;
1333
1334         retval = prepare_bprm_creds(bprm);
1335         if (retval)
1336                 goto out_free;
1337
1338         retval = check_unsafe_exec(bprm);
1339         if (retval < 0)
1340                 goto out_free;
1341         clear_in_exec = retval;
1342         current->in_execve = 1;
1343
1344         file = open_exec(filename);
1345         retval = PTR_ERR(file);
1346         if (IS_ERR(file))
1347                 goto out_unmark;
1348
1349         sched_exec();
1350
1351         bprm->file = file;
1352         bprm->filename = filename;
1353         bprm->interp = filename;
1354
1355         retval = bprm_mm_init(bprm);
1356         if (retval)
1357                 goto out_file;
1358
1359         bprm->argc = count(argv, MAX_ARG_STRINGS);
1360         if ((retval = bprm->argc) < 0)
1361                 goto out;
1362
1363         bprm->envc = count(envp, MAX_ARG_STRINGS);
1364         if ((retval = bprm->envc) < 0)
1365                 goto out;
1366
1367         retval = prepare_binprm(bprm);
1368         if (retval < 0)
1369                 goto out;
1370
1371         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1372         if (retval < 0)
1373                 goto out;
1374
1375         bprm->exec = bprm->p;
1376         retval = copy_strings(bprm->envc, envp, bprm);
1377         if (retval < 0)
1378                 goto out;
1379
1380         retval = copy_strings(bprm->argc, argv, bprm);
1381         if (retval < 0)
1382                 goto out;
1383
1384         current->flags &= ~PF_KTHREAD;
1385         retval = search_binary_handler(bprm,regs);
1386         if (retval < 0)
1387                 goto out;
1388
1389         /* execve succeeded */
1390         current->fs->in_exec = 0;
1391         current->in_execve = 0;
1392         acct_update_integrals(current);
1393         free_bprm(bprm);
1394         if (displaced)
1395                 put_files_struct(displaced);
1396         return retval;
1397
1398 out:
1399         if (bprm->mm)
1400                 mmput (bprm->mm);
1401
1402 out_file:
1403         if (bprm->file) {
1404                 allow_write_access(bprm->file);
1405                 fput(bprm->file);
1406         }
1407
1408 out_unmark:
1409         if (clear_in_exec)
1410                 current->fs->in_exec = 0;
1411         current->in_execve = 0;
1412
1413 out_free:
1414         free_bprm(bprm);
1415
1416 out_files:
1417         if (displaced)
1418                 reset_files_struct(displaced);
1419 out_ret:
1420         return retval;
1421 }
1422
1423 void set_binfmt(struct linux_binfmt *new)
1424 {
1425         struct mm_struct *mm = current->mm;
1426
1427         if (mm->binfmt)
1428                 module_put(mm->binfmt->module);
1429
1430         mm->binfmt = new;
1431         if (new)
1432                 __module_get(new->module);
1433 }
1434
1435 EXPORT_SYMBOL(set_binfmt);
1436
1437 /* format_corename will inspect the pattern parameter, and output a
1438  * name into corename, which must have space for at least
1439  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1440  */
1441 static int format_corename(char *corename, long signr)
1442 {
1443         const struct cred *cred = current_cred();
1444         const char *pat_ptr = core_pattern;
1445         int ispipe = (*pat_ptr == '|');
1446         char *out_ptr = corename;
1447         char *const out_end = corename + CORENAME_MAX_SIZE;
1448         int rc;
1449         int pid_in_pattern = 0;
1450
1451         /* Repeat as long as we have more pattern to process and more output
1452            space */
1453         while (*pat_ptr) {
1454                 if (*pat_ptr != '%') {
1455                         if (out_ptr == out_end)
1456                                 goto out;
1457                         *out_ptr++ = *pat_ptr++;
1458                 } else {
1459                         switch (*++pat_ptr) {
1460                         case 0:
1461                                 goto out;
1462                         /* Double percent, output one percent */
1463                         case '%':
1464                                 if (out_ptr == out_end)
1465                                         goto out;
1466                                 *out_ptr++ = '%';
1467                                 break;
1468                         /* pid */
1469                         case 'p':
1470                                 pid_in_pattern = 1;
1471                                 rc = snprintf(out_ptr, out_end - out_ptr,
1472                                               "%d", task_tgid_vnr(current));
1473                                 if (rc > out_end - out_ptr)
1474                                         goto out;
1475                                 out_ptr += rc;
1476                                 break;
1477                         /* uid */
1478                         case 'u':
1479                                 rc = snprintf(out_ptr, out_end - out_ptr,
1480                                               "%d", cred->uid);
1481                                 if (rc > out_end - out_ptr)
1482                                         goto out;
1483                                 out_ptr += rc;
1484                                 break;
1485                         /* gid */
1486                         case 'g':
1487                                 rc = snprintf(out_ptr, out_end - out_ptr,
1488                                               "%d", cred->gid);
1489                                 if (rc > out_end - out_ptr)
1490                                         goto out;
1491                                 out_ptr += rc;
1492                                 break;
1493                         /* signal that caused the coredump */
1494                         case 's':
1495                                 rc = snprintf(out_ptr, out_end - out_ptr,
1496                                               "%ld", signr);
1497                                 if (rc > out_end - out_ptr)
1498                                         goto out;
1499                                 out_ptr += rc;
1500                                 break;
1501                         /* UNIX time of coredump */
1502                         case 't': {
1503                                 struct timeval tv;
1504                                 do_gettimeofday(&tv);
1505                                 rc = snprintf(out_ptr, out_end - out_ptr,
1506                                               "%lu", tv.tv_sec);
1507                                 if (rc > out_end - out_ptr)
1508                                         goto out;
1509                                 out_ptr += rc;
1510                                 break;
1511                         }
1512                         /* hostname */
1513                         case 'h':
1514                                 down_read(&uts_sem);
1515                                 rc = snprintf(out_ptr, out_end - out_ptr,
1516                                               "%s", utsname()->nodename);
1517                                 up_read(&uts_sem);
1518                                 if (rc > out_end - out_ptr)
1519                                         goto out;
1520                                 out_ptr += rc;
1521                                 break;
1522                         /* executable */
1523                         case 'e':
1524                                 rc = snprintf(out_ptr, out_end - out_ptr,
1525                                               "%s", current->comm);
1526                                 if (rc > out_end - out_ptr)
1527                                         goto out;
1528                                 out_ptr += rc;
1529                                 break;
1530                         /* core limit size */
1531                         case 'c':
1532                                 rc = snprintf(out_ptr, out_end - out_ptr,
1533                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1534                                 if (rc > out_end - out_ptr)
1535                                         goto out;
1536                                 out_ptr += rc;
1537                                 break;
1538                         default:
1539                                 break;
1540                         }
1541                         ++pat_ptr;
1542                 }
1543         }
1544         /* Backward compatibility with core_uses_pid:
1545          *
1546          * If core_pattern does not include a %p (as is the default)
1547          * and core_uses_pid is set, then .%pid will be appended to
1548          * the filename. Do not do this for piped commands. */
1549         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1550                 rc = snprintf(out_ptr, out_end - out_ptr,
1551                               ".%d", task_tgid_vnr(current));
1552                 if (rc > out_end - out_ptr)
1553                         goto out;
1554                 out_ptr += rc;
1555         }
1556 out:
1557         *out_ptr = 0;
1558         return ispipe;
1559 }
1560
1561 static int zap_process(struct task_struct *start)
1562 {
1563         struct task_struct *t;
1564         int nr = 0;
1565
1566         start->signal->flags = SIGNAL_GROUP_EXIT;
1567         start->signal->group_stop_count = 0;
1568
1569         t = start;
1570         do {
1571                 if (t != current && t->mm) {
1572                         sigaddset(&t->pending.signal, SIGKILL);
1573                         signal_wake_up(t, 1);
1574                         nr++;
1575                 }
1576         } while_each_thread(start, t);
1577
1578         return nr;
1579 }
1580
1581 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1582                                 struct core_state *core_state, int exit_code)
1583 {
1584         struct task_struct *g, *p;
1585         unsigned long flags;
1586         int nr = -EAGAIN;
1587
1588         spin_lock_irq(&tsk->sighand->siglock);
1589         if (!signal_group_exit(tsk->signal)) {
1590                 mm->core_state = core_state;
1591                 tsk->signal->group_exit_code = exit_code;
1592                 nr = zap_process(tsk);
1593         }
1594         spin_unlock_irq(&tsk->sighand->siglock);
1595         if (unlikely(nr < 0))
1596                 return nr;
1597
1598         if (atomic_read(&mm->mm_users) == nr + 1)
1599                 goto done;
1600         /*
1601          * We should find and kill all tasks which use this mm, and we should
1602          * count them correctly into ->nr_threads. We don't take tasklist
1603          * lock, but this is safe wrt:
1604          *
1605          * fork:
1606          *      None of sub-threads can fork after zap_process(leader). All
1607          *      processes which were created before this point should be
1608          *      visible to zap_threads() because copy_process() adds the new
1609          *      process to the tail of init_task.tasks list, and lock/unlock
1610          *      of ->siglock provides a memory barrier.
1611          *
1612          * do_exit:
1613          *      The caller holds mm->mmap_sem. This means that the task which
1614          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1615          *      its ->mm.
1616          *
1617          * de_thread:
1618          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1619          *      we must see either old or new leader, this does not matter.
1620          *      However, it can change p->sighand, so lock_task_sighand(p)
1621          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1622          *      it can't fail.
1623          *
1624          *      Note also that "g" can be the old leader with ->mm == NULL
1625          *      and already unhashed and thus removed from ->thread_group.
1626          *      This is OK, __unhash_process()->list_del_rcu() does not
1627          *      clear the ->next pointer, we will find the new leader via
1628          *      next_thread().
1629          */
1630         rcu_read_lock();
1631         for_each_process(g) {
1632                 if (g == tsk->group_leader)
1633                         continue;
1634                 if (g->flags & PF_KTHREAD)
1635                         continue;
1636                 p = g;
1637                 do {
1638                         if (p->mm) {
1639                                 if (unlikely(p->mm == mm)) {
1640                                         lock_task_sighand(p, &flags);
1641                                         nr += zap_process(p);
1642                                         unlock_task_sighand(p, &flags);
1643                                 }
1644                                 break;
1645                         }
1646                 } while_each_thread(g, p);
1647         }
1648         rcu_read_unlock();
1649 done:
1650         atomic_set(&core_state->nr_threads, nr);
1651         return nr;
1652 }
1653
1654 static int coredump_wait(int exit_code, struct core_state *core_state)
1655 {
1656         struct task_struct *tsk = current;
1657         struct mm_struct *mm = tsk->mm;
1658         struct completion *vfork_done;
1659         int core_waiters;
1660
1661         init_completion(&core_state->startup);
1662         core_state->dumper.task = tsk;
1663         core_state->dumper.next = NULL;
1664         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1665         up_write(&mm->mmap_sem);
1666
1667         if (unlikely(core_waiters < 0))
1668                 goto fail;
1669
1670         /*
1671          * Make sure nobody is waiting for us to release the VM,
1672          * otherwise we can deadlock when we wait on each other
1673          */
1674         vfork_done = tsk->vfork_done;
1675         if (vfork_done) {
1676                 tsk->vfork_done = NULL;
1677                 complete(vfork_done);
1678         }
1679
1680         if (core_waiters)
1681                 wait_for_completion(&core_state->startup);
1682 fail:
1683         return core_waiters;
1684 }
1685
1686 static void coredump_finish(struct mm_struct *mm)
1687 {
1688         struct core_thread *curr, *next;
1689         struct task_struct *task;
1690
1691         next = mm->core_state->dumper.next;
1692         while ((curr = next) != NULL) {
1693                 next = curr->next;
1694                 task = curr->task;
1695                 /*
1696                  * see exit_mm(), curr->task must not see
1697                  * ->task == NULL before we read ->next.
1698                  */
1699                 smp_mb();
1700                 curr->task = NULL;
1701                 wake_up_process(task);
1702         }
1703
1704         mm->core_state = NULL;
1705 }
1706
1707 /*
1708  * set_dumpable converts traditional three-value dumpable to two flags and
1709  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1710  * these bits are not changed atomically.  So get_dumpable can observe the
1711  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1712  * return either old dumpable or new one by paying attention to the order of
1713  * modifying the bits.
1714  *
1715  * dumpable |   mm->flags (binary)
1716  * old  new | initial interim  final
1717  * ---------+-----------------------
1718  *  0    1  |   00      01      01
1719  *  0    2  |   00      10(*)   11
1720  *  1    0  |   01      00      00
1721  *  1    2  |   01      11      11
1722  *  2    0  |   11      10(*)   00
1723  *  2    1  |   11      11      01
1724  *
1725  * (*) get_dumpable regards interim value of 10 as 11.
1726  */
1727 void set_dumpable(struct mm_struct *mm, int value)
1728 {
1729         switch (value) {
1730         case 0:
1731                 clear_bit(MMF_DUMPABLE, &mm->flags);
1732                 smp_wmb();
1733                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1734                 break;
1735         case 1:
1736                 set_bit(MMF_DUMPABLE, &mm->flags);
1737                 smp_wmb();
1738                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1739                 break;
1740         case 2:
1741                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1742                 smp_wmb();
1743                 set_bit(MMF_DUMPABLE, &mm->flags);
1744                 break;
1745         }
1746 }
1747
1748 int get_dumpable(struct mm_struct *mm)
1749 {
1750         int ret;
1751
1752         ret = mm->flags & 0x3;
1753         return (ret >= 2) ? 2 : ret;
1754 }
1755
1756 static void wait_for_dump_helpers(struct file *file)
1757 {
1758         struct pipe_inode_info *pipe;
1759
1760         pipe = file->f_path.dentry->d_inode->i_pipe;
1761
1762         pipe_lock(pipe);
1763         pipe->readers++;
1764         pipe->writers--;
1765
1766         while ((pipe->readers > 1) && (!signal_pending(current))) {
1767                 wake_up_interruptible_sync(&pipe->wait);
1768                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1769                 pipe_wait(pipe);
1770         }
1771
1772         pipe->readers--;
1773         pipe->writers++;
1774         pipe_unlock(pipe);
1775
1776 }
1777
1778
1779 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1780 {
1781         struct core_state core_state;
1782         char corename[CORENAME_MAX_SIZE + 1];
1783         struct mm_struct *mm = current->mm;
1784         struct linux_binfmt * binfmt;
1785         struct inode * inode;
1786         struct file * file;
1787         const struct cred *old_cred;
1788         struct cred *cred;
1789         int retval = 0;
1790         int flag = 0;
1791         int ispipe = 0;
1792         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1793         char **helper_argv = NULL;
1794         int helper_argc = 0;
1795         int dump_count = 0;
1796         static atomic_t core_dump_count = ATOMIC_INIT(0);
1797
1798         audit_core_dumps(signr);
1799
1800         binfmt = mm->binfmt;
1801         if (!binfmt || !binfmt->core_dump)
1802                 goto fail;
1803
1804         cred = prepare_creds();
1805         if (!cred) {
1806                 retval = -ENOMEM;
1807                 goto fail;
1808         }
1809
1810         down_write(&mm->mmap_sem);
1811         /*
1812          * If another thread got here first, or we are not dumpable, bail out.
1813          */
1814         if (mm->core_state || !get_dumpable(mm)) {
1815                 up_write(&mm->mmap_sem);
1816                 put_cred(cred);
1817                 goto fail;
1818         }
1819
1820         /*
1821          *      We cannot trust fsuid as being the "true" uid of the
1822          *      process nor do we know its entire history. We only know it
1823          *      was tainted so we dump it as root in mode 2.
1824          */
1825         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1826                 flag = O_EXCL;          /* Stop rewrite attacks */
1827                 cred->fsuid = 0;        /* Dump root private */
1828         }
1829
1830         retval = coredump_wait(exit_code, &core_state);
1831         if (retval < 0) {
1832                 put_cred(cred);
1833                 goto fail;
1834         }
1835
1836         old_cred = override_creds(cred);
1837
1838         /*
1839          * Clear any false indication of pending signals that might
1840          * be seen by the filesystem code called to write the core file.
1841          */
1842         clear_thread_flag(TIF_SIGPENDING);
1843
1844         /*
1845          * lock_kernel() because format_corename() is controlled by sysctl, which
1846          * uses lock_kernel()
1847          */
1848         lock_kernel();
1849         ispipe = format_corename(corename, signr);
1850         unlock_kernel();
1851
1852         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1853                 goto fail_unlock;
1854
1855         if (ispipe) {
1856                 if (core_limit == 0) {
1857                         /*
1858                          * Normally core limits are irrelevant to pipes, since
1859                          * we're not writing to the file system, but we use
1860                          * core_limit of 0 here as a speacial value. Any
1861                          * non-zero limit gets set to RLIM_INFINITY below, but
1862                          * a limit of 0 skips the dump.  This is a consistent
1863                          * way to catch recursive crashes.  We can still crash
1864                          * if the core_pattern binary sets RLIM_CORE =  !0
1865                          * but it runs as root, and can do lots of stupid things
1866                          * Note that we use task_tgid_vnr here to grab the pid
1867                          * of the process group leader.  That way we get the
1868                          * right pid if a thread in a multi-threaded
1869                          * core_pattern process dies.
1870                          */
1871                         printk(KERN_WARNING
1872                                 "Process %d(%s) has RLIMIT_CORE set to 0\n",
1873                                 task_tgid_vnr(current), current->comm);
1874                         printk(KERN_WARNING "Aborting core\n");
1875                         goto fail_unlock;
1876                 }
1877
1878                 dump_count = atomic_inc_return(&core_dump_count);
1879                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
1880                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
1881                                task_tgid_vnr(current), current->comm);
1882                         printk(KERN_WARNING "Skipping core dump\n");
1883                         goto fail_dropcount;
1884                 }
1885
1886                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1887                 if (!helper_argv) {
1888                         printk(KERN_WARNING "%s failed to allocate memory\n",
1889                                __func__);
1890                         goto fail_dropcount;
1891                 }
1892
1893                 core_limit = RLIM_INFINITY;
1894
1895                 /* SIGPIPE can happen, but it's just never processed */
1896                 if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
1897                                 &file)) {
1898                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1899                                corename);
1900                         goto fail_dropcount;
1901                 }
1902         } else
1903                 file = filp_open(corename,
1904                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1905                                  0600);
1906         if (IS_ERR(file))
1907                 goto fail_dropcount;
1908         inode = file->f_path.dentry->d_inode;
1909         if (inode->i_nlink > 1)
1910                 goto close_fail;        /* multiple links - don't dump */
1911         if (!ispipe && d_unhashed(file->f_path.dentry))
1912                 goto close_fail;
1913
1914         /* AK: actually i see no reason to not allow this for named pipes etc.,
1915            but keep the previous behaviour for now. */
1916         if (!ispipe && !S_ISREG(inode->i_mode))
1917                 goto close_fail;
1918         /*
1919          * Dont allow local users get cute and trick others to coredump
1920          * into their pre-created files:
1921          * Note, this is not relevant for pipes
1922          */
1923         if (!ispipe && (inode->i_uid != current_fsuid()))
1924                 goto close_fail;
1925         if (!file->f_op)
1926                 goto close_fail;
1927         if (!file->f_op->write)
1928                 goto close_fail;
1929         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1930                 goto close_fail;
1931
1932         retval = binfmt->core_dump(signr, regs, file, core_limit);
1933
1934         if (retval)
1935                 current->signal->group_exit_code |= 0x80;
1936 close_fail:
1937         if (ispipe && core_pipe_limit)
1938                 wait_for_dump_helpers(file);
1939         filp_close(file, NULL);
1940 fail_dropcount:
1941         if (dump_count)
1942                 atomic_dec(&core_dump_count);
1943 fail_unlock:
1944         if (helper_argv)
1945                 argv_free(helper_argv);
1946
1947         revert_creds(old_cred);
1948         put_cred(cred);
1949         coredump_finish(mm);
1950 fail:
1951         return;
1952 }