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