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/swap.h>
  32 #include <linux/string.h>
  33 #include <linux/init.h>
  34 #include <linux/pagemap.h>
  35 #include <linux/perf_event.h>
  36 #include <linux/highmem.h>
  37 #include <linux/spinlock.h>
  38 #include <linux/key.h>
  39 #include <linux/personality.h>
  40 #include <linux/binfmts.h>
  41 #include <linux/utsname.h>
  42 #include <linux/pid_namespace.h>
  43 #include <linux/module.h>
  44 #include <linux/namei.h>
  45 #include <linux/proc_fs.h>
  46 #include <linux/mount.h>
  47 #include <linux/security.h>
  48 #include <linux/syscalls.h>
  49 #include <linux/tsacct_kern.h>
  50 #include <linux/cn_proc.h>
  51 #include <linux/audit.h>
  52 #include <linux/tracehook.h>
  53 #include <linux/kmod.h>
  54 #include <linux/fsnotify.h>
  55 #include <linux/fs_struct.h>
  56 #include <linux/pipe_fs_i.h>
  57
  58 #include <asm/uaccess.h>
  59 #include <asm/mmu_context.h>
  60 #include <asm/tlb.h>
  61 #include "internal.h"
  62
  63 int core_uses_pid;
  64 char core_pattern[CORENAME_MAX_SIZE] = "core";
  65 unsigned int core_pipe_limit;
  66 int suid_dumpable = 0;
  67
  68 /* The maximal length of core_pattern is also specified in sysctl.c */
  69
  70 static LIST_HEAD(formats);
  71 static DEFINE_RWLOCK(binfmt_lock);
  72
  73 int __register_binfmt(struct linux_binfmt * fmt, int insert)
  74 {
  75         if (!fmt)
  76                 return -EINVAL;
  77         write_lock(&binfmt_lock);
  78         insert ? list_add(&fmt->lh, &formats) :
  79                  list_add_tail(&fmt->lh, &formats);
  80         write_unlock(&binfmt_lock);
  81         return 0;
  82 }
  83
  84 EXPORT_SYMBOL(__register_binfmt);
  85
  86 void unregister_binfmt(struct linux_binfmt * fmt)
  87 {
  88         write_lock(&binfmt_lock);
  89         list_del(&fmt->lh);
  90         write_unlock(&binfmt_lock);
  91 }
  92
  93 EXPORT_SYMBOL(unregister_binfmt);
  94
  95 static inline void put_binfmt(struct linux_binfmt * fmt)
  96 {
  97         module_put(fmt->module);
  98 }
  99
 100 /*
 101  * Note that a shared library must be both readable and executable due to
 102  * security reasons.
 103  *
 104  * Also note that we take the address to load from from the file itself.
 105  */
 106 SYSCALL_DEFINE1(uselib, const char __user *, library)
 107 {
 108         struct file *file;
 109         char *tmp = getname(library);
 110         int error = PTR_ERR(tmp);
 111
 112         if (IS_ERR(tmp))
 113                 goto out;
 114
 115         file = do_filp_open(AT_FDCWD, tmp,
 116                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
 117                                 MAY_READ | MAY_EXEC | MAY_OPEN);
 118         putname(tmp);
 119         error = PTR_ERR(file);
 120         if (IS_ERR(file))
 121                 goto out;
 122
 123         error = -EINVAL;
 124         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 125                 goto exit;
 126
 127         error = -EACCES;
 128         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 129                 goto exit;
 130
 131         fsnotify_open(file);
 132
 133         error = -ENOEXEC;
 134         if(file->f_op) {
 135                 struct linux_binfmt * fmt;
 136
 137                 read_lock(&binfmt_lock);
 138                 list_for_each_entry(fmt, &formats, lh) {
 139                         if (!fmt->load_shlib)
 140                                 continue;
 141                         if (!try_module_get(fmt->module))
 142                                 continue;
 143                         read_unlock(&binfmt_lock);
 144                         error = fmt->load_shlib(file);
 145                         read_lock(&binfmt_lock);
 146                         put_binfmt(fmt);
 147                         if (error != -ENOEXEC)
 148                                 break;
 149                 }
 150                 read_unlock(&binfmt_lock);
 151         }
 152 exit:
 153         fput(file);
 154 out:
 155         return error;
 156 }
 157
 158 #ifdef CONFIG_MMU
 159
 160 void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 161 {
 162         struct mm_struct *mm = current->mm;
 163         long diff = (long)(pages - bprm->vma_pages);
 164
 165         if (!mm || !diff)
 166                 return;
 167
 168         bprm->vma_pages = pages;
 169
 170 #ifdef SPLIT_RSS_COUNTING
 171         add_mm_counter(mm, MM_ANONPAGES, diff);
 172 #else
 173         spin_lock(&mm->page_table_lock);
 174         add_mm_counter(mm, MM_ANONPAGES, diff);
 175         spin_unlock(&mm->page_table_lock);
 176 #endif
 177 }
 178
 179 struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 180                 int write)
 181 {
 182         struct page *page;
 183         int ret;
 184
 185 #ifdef CONFIG_STACK_GROWSUP
 186         if (write) {
 187                 ret = expand_stack_downwards(bprm->vma, pos);
 188                 if (ret < 0)
 189                         return NULL;
 190         }
 191 #endif
 192         ret = get_user_pages(current, bprm->mm, pos,
 193                         1, write, 1, &page, NULL);
 194         if (ret <= 0)
 195                 return NULL;
 196
 197         if (write) {
 198                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 199                 struct rlimit *rlim;
 200
 201                 acct_arg_size(bprm, size / PAGE_SIZE);
 202
 203                 /*
 204                  * We've historically supported up to 32 pages (ARG_MAX)
 205                  * of argument strings even with small stacks
 206                  */
 207                 if (size <= ARG_MAX)
 208                         return page;
 209
 210                 /*
 211                  * Limit to 1/4-th the stack size for the argv+env strings.
 212                  * This ensures that:
 213                  *  - the remaining binfmt code will not run out of stack space,
 214                  *  - the program will have a reasonable amount of stack left
 215                  *    to work from.
 216                  */
 217                 rlim = current->signal->rlim;
 218                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 219                         put_page(page);
 220                         return NULL;
 221                 }
 222         }
 223
 224         return page;
 225 }
 226
 227 static void put_arg_page(struct page *page)
 228 {
 229         put_page(page);
 230 }
 231
 232 static void free_arg_page(struct linux_binprm *bprm, int i)
 233 {
 234 }
 235
 236 static void free_arg_pages(struct linux_binprm *bprm)
 237 {
 238 }
 239
 240 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 241                 struct page *page)
 242 {
 243         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 244 }
 245
 246 static int __bprm_mm_init(struct linux_binprm *bprm)
 247 {
 248         int err;
 249         struct vm_area_struct *vma = NULL;
 250         struct mm_struct *mm = bprm->mm;
 251
 252         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 253         if (!vma)
 254                 return -ENOMEM;
 255
 256         down_write(&mm->mmap_sem);
 257         vma->vm_mm = mm;
 258
 259         /*
 260          * Place the stack at the largest stack address the architecture
 261          * supports. Later, we'll move this to an appropriate place. We don't
 262          * use STACK_TOP because that can depend on attributes which aren't
 263          * configured yet.
 264          */
 265         BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 266         vma->vm_end = STACK_TOP_MAX;
 267         vma->vm_start = vma->vm_end - PAGE_SIZE;
 268         vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 269         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 270         INIT_LIST_HEAD(&vma->anon_vma_chain);
 271
 272         err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
 273         if (err)
 274                 goto err;
 275
 276         err = insert_vm_struct(mm, vma);
 277         if (err)
 278                 goto err;
 279
 280         mm->stack_vm = mm->total_vm = 1;
 281         up_write(&mm->mmap_sem);
 282         bprm->p = vma->vm_end - sizeof(void *);
 283         return 0;
 284 err:
 285         up_write(&mm->mmap_sem);
 286         bprm->vma = NULL;
 287         kmem_cache_free(vm_area_cachep, vma);
 288         return err;
 289 }
 290
 291 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 292 {
 293         return len <= MAX_ARG_STRLEN;
 294 }
 295
 296 #else
 297
 298 void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 299 {
 300 }
 301
 302 struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 303                 int write)
 304 {
 305         struct page *page;
 306
 307         page = bprm->page[pos / PAGE_SIZE];
 308         if (!page && write) {
 309                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 310                 if (!page)
 311                         return NULL;
 312                 bprm->page[pos / PAGE_SIZE] = page;
 313         }
 314
 315         return page;
 316 }
 317
 318 static void put_arg_page(struct page *page)
 319 {
 320 }
 321
 322 static void free_arg_page(struct linux_binprm *bprm, int i)
 323 {
 324         if (bprm->page[i]) {
 325                 __free_page(bprm->page[i]);
 326                 bprm->page[i] = NULL;
 327         }
 328 }
 329
 330 static void free_arg_pages(struct linux_binprm *bprm)
 331 {
 332         int i;
 333
 334         for (i = 0; i < MAX_ARG_PAGES; i++)
 335                 free_arg_page(bprm, i);
 336 }
 337
 338 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 339                 struct page *page)
 340 {
 341 }
 342
 343 static int __bprm_mm_init(struct linux_binprm *bprm)
 344 {
 345         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 346         return 0;
 347 }
 348
 349 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 350 {
 351         return len <= bprm->p;
 352 }
 353
 354 #endif /* CONFIG_MMU */
 355
 356 /*
 357  * Create a new mm_struct and populate it with a temporary stack
 358  * vm_area_struct.  We don't have enough context at this point to set the stack
 359  * flags, permissions, and offset, so we use temporary values.  We'll update
 360  * them later in setup_arg_pages().
 361  */
 362 int bprm_mm_init(struct linux_binprm *bprm)
 363 {
 364         int err;
 365         struct mm_struct *mm = NULL;
 366
 367         bprm->mm = mm = mm_alloc();
 368         err = -ENOMEM;
 369         if (!mm)
 370                 goto err;
 371
 372         err = init_new_context(current, mm);
 373         if (err)
 374                 goto err;
 375
 376         err = __bprm_mm_init(bprm);
 377         if (err)
 378                 goto err;
 379
 380         return 0;
 381
 382 err:
 383         if (mm) {
 384                 bprm->mm = NULL;
 385                 mmdrop(mm);
 386         }
 387
 388         return err;
 389 }
 390
 391 /*
 392  * count() counts the number of strings in array ARGV.
 393  */
 394 static int count(const char __user * const __user * argv, int max)
 395 {
 396         int i = 0;
 397
 398         if (argv != NULL) {
 399                 for (;;) {
 400                         const char __user * p;
 401
 402                         if (get_user(p, argv))
 403                                 return -EFAULT;
 404                         if (!p)
 405                                 break;
 406                         argv++;
 407                         if (i++ >= max)
 408                                 return -E2BIG;
 409
 410                         if (fatal_signal_pending(current))
 411                                 return -ERESTARTNOHAND;
 412                         cond_resched();
 413                 }
 414         }
 415         return i;
 416 }
 417
 418 /*
 419  * 'copy_strings()' copies argument/environment strings from the old
 420  * processes's memory to the new process's stack.  The call to get_user_pages()
 421  * ensures the destination page is created and not swapped out.
 422  */
 423 static int copy_strings(int argc, const char __user *const __user *argv,
 424                         struct linux_binprm *bprm)
 425 {
 426         struct page *kmapped_page = NULL;
 427         char *kaddr = NULL;
 428         unsigned long kpos = 0;
 429         int ret;
 430
 431         while (argc-- > 0) {
 432                 const char __user *str;
 433                 int len;
 434                 unsigned long pos;
 435
 436                 if (get_user(str, argv+argc) ||
 437                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
 438                         ret = -EFAULT;
 439                         goto out;
 440                 }
 441
 442                 if (!valid_arg_len(bprm, len)) {
 443                         ret = -E2BIG;
 444                         goto out;
 445                 }
 446
 447                 /* We're going to work our way backwords. */
 448                 pos = bprm->p;
 449                 str += len;
 450                 bprm->p -= len;
 451
 452                 while (len > 0) {
 453                         int offset, bytes_to_copy;
 454
 455                         if (fatal_signal_pending(current)) {
 456                                 ret = -ERESTARTNOHAND;
 457                                 goto out;
 458                         }
 459                         cond_resched();
 460
 461                         offset = pos % PAGE_SIZE;
 462                         if (offset == 0)
 463                                 offset = PAGE_SIZE;
 464
 465                         bytes_to_copy = offset;
 466                         if (bytes_to_copy > len)
 467                                 bytes_to_copy = len;
 468
 469                         offset -= bytes_to_copy;
 470                         pos -= bytes_to_copy;
 471                         str -= bytes_to_copy;
 472                         len -= bytes_to_copy;
 473
 474                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 475                                 struct page *page;
 476
 477                                 page = get_arg_page(bprm, pos, 1);
 478                                 if (!page) {
 479                                         ret = -E2BIG;
 480                                         goto out;
 481                                 }
 482
 483                                 if (kmapped_page) {
 484                                         flush_kernel_dcache_page(kmapped_page);
 485                                         kunmap(kmapped_page);
 486                                         put_arg_page(kmapped_page);
 487                                 }
 488                                 kmapped_page = page;
 489                                 kaddr = kmap(kmapped_page);
 490                                 kpos = pos & PAGE_MASK;
 491                                 flush_arg_page(bprm, kpos, kmapped_page);
 492                         }
 493                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 494                                 ret = -EFAULT;
 495                                 goto out;
 496                         }
 497                 }
 498         }
 499         ret = 0;
 500 out:
 501         if (kmapped_page) {
 502                 flush_kernel_dcache_page(kmapped_page);
 503                 kunmap(kmapped_page);
 504                 put_arg_page(kmapped_page);
 505         }
 506         return ret;
 507 }
 508
 509 /*
 510  * Like copy_strings, but get argv and its values from kernel memory.
 511  */
 512 int copy_strings_kernel(int argc, const char *const *argv,
 513                         struct linux_binprm *bprm)
 514 {
 515         int r;
 516         mm_segment_t oldfs = get_fs();
 517         set_fs(KERNEL_DS);
 518         r = copy_strings(argc, (const char __user *const  __user *)argv, bprm);
 519         set_fs(oldfs);
 520         return r;
 521 }
 522 EXPORT_SYMBOL(copy_strings_kernel);
 523
 524 #ifdef CONFIG_MMU
 525
 526 /*
 527  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 528  * the binfmt code determines where the new stack should reside, we shift it to
 529  * its final location.  The process proceeds as follows:
 530  *
 531  * 1) Use shift to calculate the new vma endpoints.
 532  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 533  *    arguments passed to subsequent functions are consistent.
 534  * 3) Move vma's page tables to the new range.
 535  * 4) Free up any cleared pgd range.
 536  * 5) Shrink the vma to cover only the new range.
 537  */
 538 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 539 {
 540         struct mm_struct *mm = vma->vm_mm;
 541         unsigned long old_start = vma->vm_start;
 542         unsigned long old_end = vma->vm_end;
 543         unsigned long length = old_end - old_start;
 544         unsigned long new_start = old_start - shift;
 545         unsigned long new_end = old_end - shift;
 546         struct mmu_gather *tlb;
 547
 548         BUG_ON(new_start > new_end);
 549
 550         /*
 551          * ensure there are no vmas between where we want to go
 552          * and where we are
 553          */
 554         if (vma != find_vma(mm, new_start))
 555                 return -EFAULT;
 556
 557         /*
 558          * cover the whole range: [new_start, old_end)
 559          */
 560         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 561                 return -ENOMEM;
 562
 563         /*
 564          * move the page tables downwards, on failure we rely on
 565          * process cleanup to remove whatever mess we made.
 566          */
 567         if (length != move_page_tables(vma, old_start,
 568                                        vma, new_start, length))
 569                 return -ENOMEM;
 570
 571         lru_add_drain();
 572         tlb = tlb_gather_mmu(mm, 0);
 573         if (new_end > old_start) {
 574                 /*
 575                  * when the old and new regions overlap clear from new_end.
 576                  */
 577                 free_pgd_range(tlb, new_end, old_end, new_end,
 578                         vma->vm_next ? vma->vm_next->vm_start : 0);
 579         } else {
 580                 /*
 581                  * otherwise, clean from old_start; this is done to not touch
 582                  * the address space in [new_end, old_start) some architectures
 583                  * have constraints on va-space that make this illegal (IA64) -
 584                  * for the others its just a little faster.
 585                  */
 586                 free_pgd_range(tlb, old_start, old_end, new_end,
 587                         vma->vm_next ? vma->vm_next->vm_start : 0);
 588         }
 589         tlb_finish_mmu(tlb, new_end, old_end);
 590
 591         /*
 592          * Shrink the vma to just the new range.  Always succeeds.
 593          */
 594         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 595
 596         return 0;
 597 }
 598
 599 /*
 600  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 601  * the stack is optionally relocated, and some extra space is added.
 602  */
 603 int setup_arg_pages(struct linux_binprm *bprm,
 604                     unsigned long stack_top,
 605                     int executable_stack)
 606 {
 607         unsigned long ret;
 608         unsigned long stack_shift;
 609         struct mm_struct *mm = current->mm;
 610         struct vm_area_struct *vma = bprm->vma;
 611         struct vm_area_struct *prev = NULL;
 612         unsigned long vm_flags;
 613         unsigned long stack_base;
 614         unsigned long stack_size;
 615         unsigned long stack_expand;
 616         unsigned long rlim_stack;
 617
 618 #ifdef CONFIG_STACK_GROWSUP
 619         /* Limit stack size to 1GB */
 620         stack_base = rlimit_max(RLIMIT_STACK);
 621         if (stack_base > (1 << 30))
 622                 stack_base = 1 << 30;
 623
 624         /* Make sure we didn't let the argument array grow too large. */
 625         if (vma->vm_end - vma->vm_start > stack_base)
 626                 return -ENOMEM;
 627
 628         stack_base = PAGE_ALIGN(stack_top - stack_base);
 629
 630         stack_shift = vma->vm_start - stack_base;
 631         mm->arg_start = bprm->p - stack_shift;
 632         bprm->p = vma->vm_end - stack_shift;
 633 #else
 634         stack_top = arch_align_stack(stack_top);
 635         stack_top = PAGE_ALIGN(stack_top);
 636
 637         if (unlikely(stack_top < mmap_min_addr) ||
 638             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 639                 return -ENOMEM;
 640
 641         stack_shift = vma->vm_end - stack_top;
 642
 643         bprm->p -= stack_shift;
 644         mm->arg_start = bprm->p;
 645 #endif
 646
 647         if (bprm->loader)
 648                 bprm->loader -= stack_shift;
 649         bprm->exec -= stack_shift;
 650
 651         down_write(&mm->mmap_sem);
 652         vm_flags = VM_STACK_FLAGS;
 653
 654         /*
 655          * Adjust stack execute permissions; explicitly enable for
 656          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 657          * (arch default) otherwise.
 658          */
 659         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 660                 vm_flags |= VM_EXEC;
 661         else if (executable_stack == EXSTACK_DISABLE_X)
 662                 vm_flags &= ~VM_EXEC;
 663         vm_flags |= mm->def_flags;
 664         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 665
 666         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 667                         vm_flags);
 668         if (ret)
 669                 goto out_unlock;
 670         BUG_ON(prev != vma);
 671
 672         /* Move stack pages down in memory. */
 673         if (stack_shift) {
 674                 ret = shift_arg_pages(vma, stack_shift);
 675                 if (ret)
 676                         goto out_unlock;
 677         }
 678
 679         /* mprotect_fixup is overkill to remove the temporary stack flags */
 680         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 681
 682         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 683         stack_size = vma->vm_end - vma->vm_start;
 684         /*
 685          * Align this down to a page boundary as expand_stack
 686          * will align it up.
 687          */
 688         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 689 #ifdef CONFIG_STACK_GROWSUP
 690         if (stack_size + stack_expand > rlim_stack)
 691                 stack_base = vma->vm_start + rlim_stack;
 692         else
 693                 stack_base = vma->vm_end + stack_expand;
 694 #else
 695         if (stack_size + stack_expand > rlim_stack)
 696                 stack_base = vma->vm_end - rlim_stack;
 697         else
 698                 stack_base = vma->vm_start - stack_expand;
 699 #endif
 700         current->mm->start_stack = bprm->p;
 701         ret = expand_stack(vma, stack_base);
 702         if (ret)
 703                 ret = -EFAULT;
 704
 705 out_unlock:
 706         up_write(&mm->mmap_sem);
 707         return ret;
 708 }
 709 EXPORT_SYMBOL(setup_arg_pages);
 710
 711 #endif /* CONFIG_MMU */
 712
 713 struct file *open_exec(const char *name)
 714 {
 715         struct file *file;
 716         int err;
 717
 718         file = do_filp_open(AT_FDCWD, name,
 719                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
 720                                 MAY_EXEC | MAY_OPEN);
 721         if (IS_ERR(file))
 722                 goto out;
 723
 724         err = -EACCES;
 725         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 726                 goto exit;
 727
 728         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 729                 goto exit;
 730
 731         fsnotify_open(file);
 732
 733         err = deny_write_access(file);
 734         if (err)
 735                 goto exit;
 736
 737 out:
 738         return file;
 739
 740 exit:
 741         fput(file);
 742         return ERR_PTR(err);
 743 }
 744 EXPORT_SYMBOL(open_exec);
 745
 746 int kernel_read(struct file *file, loff_t offset,
 747                 char *addr, unsigned long count)
 748 {
 749         mm_segment_t old_fs;
 750         loff_t pos = offset;
 751         int result;
 752
 753         old_fs = get_fs();
 754         set_fs(get_ds());
 755         /* The cast to a user pointer is valid due to the set_fs() */
 756         result = vfs_read(file, (void __user *)addr, count, &pos);
 757         set_fs(old_fs);
 758         return result;
 759 }
 760
 761 EXPORT_SYMBOL(kernel_read);
 762
 763 static int exec_mmap(struct mm_struct *mm)
 764 {
 765         struct task_struct *tsk;
 766         struct mm_struct * old_mm, *active_mm;
 767
 768         /* Notify parent that we're no longer interested in the old VM */
 769         tsk = current;
 770         old_mm = current->mm;
 771         sync_mm_rss(tsk, old_mm);
 772         mm_release(tsk, old_mm);
 773
 774         if (old_mm) {
 775                 /*
 776                  * Make sure that if there is a core dump in progress
 777                  * for the old mm, we get out and die instead of going
 778                  * through with the exec.  We must hold mmap_sem around
 779                  * checking core_state and changing tsk->mm.
 780                  */
 781                 down_read(&old_mm->mmap_sem);
 782                 if (unlikely(old_mm->core_state)) {
 783                         up_read(&old_mm->mmap_sem);
 784                         return -EINTR;
 785                 }
 786         }
 787         task_lock(tsk);
 788         active_mm = tsk->active_mm;
 789         tsk->mm = mm;
 790         tsk->active_mm = mm;
 791         activate_mm(active_mm, mm);
 792         task_unlock(tsk);
 793         arch_pick_mmap_layout(mm);
 794         if (old_mm) {
 795                 up_read(&old_mm->mmap_sem);
 796                 BUG_ON(active_mm != old_mm);
 797                 mm_update_next_owner(old_mm);
 798                 mmput(old_mm);
 799                 return 0;
 800         }
 801         mmdrop(active_mm);
 802         return 0;
 803 }
 804
 805 /*
 806  * This function makes sure the current process has its own signal table,
 807  * so that flush_signal_handlers can later reset the handlers without
 808  * disturbing other processes.  (Other processes might share the signal
 809  * table via the CLONE_SIGHAND option to clone().)
 810  */
 811 static int de_thread(struct task_struct *tsk)
 812 {
 813         struct signal_struct *sig = tsk->signal;
 814         struct sighand_struct *oldsighand = tsk->sighand;
 815         spinlock_t *lock = &oldsighand->siglock;
 816
 817         if (thread_group_empty(tsk))
 818                 goto no_thread_group;
 819
 820         /*
 821          * Kill all other threads in the thread group.
 822          */
 823         spin_lock_irq(lock);
 824         if (signal_group_exit(sig)) {
 825                 /*
 826                  * Another group action in progress, just
 827                  * return so that the signal is processed.
 828                  */
 829                 spin_unlock_irq(lock);
 830                 return -EAGAIN;
 831         }
 832
 833         sig->group_exit_task = tsk;
 834         sig->notify_count = zap_other_threads(tsk);
 835         if (!thread_group_leader(tsk))
 836                 sig->notify_count--;
 837
 838         while (sig->notify_count) {
 839                 __set_current_state(TASK_UNINTERRUPTIBLE);
 840                 spin_unlock_irq(lock);
 841                 schedule();
 842                 spin_lock_irq(lock);
 843         }
 844         spin_unlock_irq(lock);
 845
 846         /*
 847          * At this point all other threads have exited, all we have to
 848          * do is to wait for the thread group leader to become inactive,
 849          * and to assume its PID:
 850          */
 851         if (!thread_group_leader(tsk)) {
 852                 struct task_struct *leader = tsk->group_leader;
 853
 854                 sig->notify_count = -1; /* for exit_notify() */
 855                 for (;;) {
 856                         write_lock_irq(&tasklist_lock);
 857                         if (likely(leader->exit_state))
 858                                 break;
 859                         __set_current_state(TASK_UNINTERRUPTIBLE);
 860                         write_unlock_irq(&tasklist_lock);
 861                         schedule();
 862                 }
 863
 864                 /*
 865                  * The only record we have of the real-time age of a
 866                  * process, regardless of execs it's done, is start_time.
 867                  * All the past CPU time is accumulated in signal_struct
 868                  * from sister threads now dead.  But in this non-leader
 869                  * exec, nothing survives from the original leader thread,
 870                  * whose birth marks the true age of this process now.
 871                  * When we take on its identity by switching to its PID, we
 872                  * also take its birthdate (always earlier than our own).
 873                  */
 874                 tsk->start_time = leader->start_time;
 875
 876                 BUG_ON(!same_thread_group(leader, tsk));
 877                 BUG_ON(has_group_leader_pid(tsk));
 878                 /*
 879                  * An exec() starts a new thread group with the
 880                  * TGID of the previous thread group. Rehash the
 881                  * two threads with a switched PID, and release
 882                  * the former thread group leader:
 883                  */
 884
 885                 /* Become a process group leader with the old leader's pid.
 886                  * The old leader becomes a thread of the this thread group.
 887                  * Note: The old leader also uses this pid until release_task
 888                  *       is called.  Odd but simple and correct.
 889                  */
 890                 detach_pid(tsk, PIDTYPE_PID);
 891                 tsk->pid = leader->pid;
 892                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 893                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 894                 transfer_pid(leader, tsk, PIDTYPE_SID);
 895
 896                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 897                 list_replace_init(&leader->sibling, &tsk->sibling);
 898
 899                 tsk->group_leader = tsk;
 900                 leader->group_leader = tsk;
 901
 902                 tsk->exit_signal = SIGCHLD;
 903
 904                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 905                 leader->exit_state = EXIT_DEAD;
 906                 write_unlock_irq(&tasklist_lock);
 907
 908                 release_task(leader);
 909         }
 910
 911         sig->group_exit_task = NULL;
 912         sig->notify_count = 0;
 913
 914 no_thread_group:
 915         if (current->mm)
 916                 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
 917
 918         exit_itimers(sig);
 919         flush_itimer_signals();
 920
 921         if (atomic_read(&oldsighand->count) != 1) {
 922                 struct sighand_struct *newsighand;
 923                 /*
 924                  * This ->sighand is shared with the CLONE_SIGHAND
 925                  * but not CLONE_THREAD task, switch to the new one.
 926                  */
 927                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 928                 if (!newsighand)
 929                         return -ENOMEM;
 930
 931                 atomic_set(&newsighand->count, 1);
 932                 memcpy(newsighand->action, oldsighand->action,
 933                        sizeof(newsighand->action));
 934
 935                 write_lock_irq(&tasklist_lock);
 936                 spin_lock(&oldsighand->siglock);
 937                 rcu_assign_pointer(tsk->sighand, newsighand);
 938                 spin_unlock(&oldsighand->siglock);
 939                 write_unlock_irq(&tasklist_lock);
 940
 941                 __cleanup_sighand(oldsighand);
 942         }
 943
 944         BUG_ON(!thread_group_leader(tsk));
 945         return 0;
 946 }
 947
 948 /*
 949  * These functions flushes out all traces of the currently running executable
 950  * so that a new one can be started
 951  */
 952 static void flush_old_files(struct files_struct * files)
 953 {
 954         long j = -1;
 955         struct fdtable *fdt;
 956
 957         spin_lock(&files->file_lock);
 958         for (;;) {
 959                 unsigned long set, i;
 960
 961                 j++;
 962                 i = j * __NFDBITS;
 963                 fdt = files_fdtable(files);
 964                 if (i >= fdt->max_fds)
 965                         break;
 966                 set = fdt->close_on_exec->fds_bits[j];
 967                 if (!set)
 968                         continue;
 969                 fdt->close_on_exec->fds_bits[j] = 0;
 970                 spin_unlock(&files->file_lock);
 971                 for ( ; set ; i++,set >>= 1) {
 972                         if (set & 1) {
 973                                 sys_close(i);
 974                         }
 975                 }
 976                 spin_lock(&files->file_lock);
 977
 978         }
 979         spin_unlock(&files->file_lock);
 980 }
 981
 982 char *get_task_comm(char *buf, struct task_struct *tsk)
 983 {
 984         /* buf must be at least sizeof(tsk->comm) in size */
 985         task_lock(tsk);
 986         strncpy(buf, tsk->comm, sizeof(tsk->comm));
 987         task_unlock(tsk);
 988         return buf;
 989 }
 990
 991 void set_task_comm(struct task_struct *tsk, char *buf)
 992 {
 993         task_lock(tsk);
 994
 995         /*
 996          * Threads may access current->comm without holding
 997          * the task lock, so write the string carefully.
 998          * Readers without a lock may see incomplete new
 999          * names but are safe from non-terminating string reads.
1000          */
1001         memset(tsk->comm, 0, TASK_COMM_LEN);
1002         wmb();
1003         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1004         task_unlock(tsk);
1005         perf_event_comm(tsk);
1006 }
1007
1008 int flush_old_exec(struct linux_binprm * bprm)
1009 {
1010         int retval;
1011
1012         /*
1013          * Make sure we have a private signal table and that
1014          * we are unassociated from the previous thread group.
1015          */
1016         retval = de_thread(current);
1017         if (retval)
1018                 goto out;
1019
1020         set_mm_exe_file(bprm->mm, bprm->file);
1021
1022         /*
1023          * Release all of the old mmap stuff
1024          */
1025         acct_arg_size(bprm, 0);
1026         retval = exec_mmap(bprm->mm);
1027         if (retval)
1028                 goto out;
1029
1030         bprm->mm = NULL;                /* We're using it now */
1031
1032         current->flags &= ~PF_RANDOMIZE;
1033         flush_thread();
1034         current->personality &= ~bprm->per_clear;
1035
1036         return 0;
1037
1038 out:
1039         return retval;
1040 }
1041 EXPORT_SYMBOL(flush_old_exec);
1042
1043 void setup_new_exec(struct linux_binprm * bprm)
1044 {
1045         int i, ch;
1046         const char *name;
1047         char tcomm[sizeof(current->comm)];
1048
1049         arch_pick_mmap_layout(current->mm);
1050
1051         /* This is the point of no return */
1052         current->sas_ss_sp = current->sas_ss_size = 0;
1053
1054         if (current_euid() == current_uid() && current_egid() == current_gid())
1055                 set_dumpable(current->mm, 1);
1056         else
1057                 set_dumpable(current->mm, suid_dumpable);
1058
1059         name = bprm->filename;
1060
1061         /* Copies the binary name from after last slash */
1062         for (i=0; (ch = *(name++)) != '\0';) {
1063                 if (ch == '/')
1064                         i = 0; /* overwrite what we wrote */
1065                 else
1066                         if (i < (sizeof(tcomm) - 1))
1067                                 tcomm[i++] = ch;
1068         }
1069         tcomm[i] = '\0';
1070         set_task_comm(current, tcomm);
1071
1072         /* Set the new mm task size. We have to do that late because it may
1073          * depend on TIF_32BIT which is only updated in flush_thread() on
1074          * some architectures like powerpc
1075          */
1076         current->mm->task_size = TASK_SIZE;
1077
1078         /* install the new credentials */
1079         if (bprm->cred->uid != current_euid() ||
1080             bprm->cred->gid != current_egid()) {
1081                 current->pdeath_signal = 0;
1082         } else if (file_permission(bprm->file, MAY_READ) ||
1083                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1084                 set_dumpable(current->mm, suid_dumpable);
1085         }
1086
1087         /*
1088          * Flush performance counters when crossing a
1089          * security domain:
1090          */
1091         if (!get_dumpable(current->mm))
1092                 perf_event_exit_task(current);
1093
1094         /* An exec changes our domain. We are no longer part of the thread
1095            group */
1096
1097         current->self_exec_id++;
1098
1099         flush_signal_handlers(current, 0);
1100         flush_old_files(current->files);
1101 }
1102 EXPORT_SYMBOL(setup_new_exec);
1103
1104 /*
1105  * Prepare credentials and lock ->cred_guard_mutex.
1106  * install_exec_creds() commits the new creds and drops the lock.
1107  * Or, if exec fails before, free_bprm() should release ->cred and
1108  * and unlock.
1109  */
1110 int prepare_bprm_creds(struct linux_binprm *bprm)
1111 {
1112         if (mutex_lock_interruptible(&current->cred_guard_mutex))
1113                 return -ERESTARTNOINTR;
1114
1115         bprm->cred = prepare_exec_creds();
1116         if (likely(bprm->cred))
1117                 return 0;
1118
1119         mutex_unlock(&current->cred_guard_mutex);
1120         return -ENOMEM;
1121 }
1122
1123 void free_bprm(struct linux_binprm *bprm)
1124 {
1125         free_arg_pages(bprm);
1126         if (bprm->cred) {
1127                 mutex_unlock(&current->cred_guard_mutex);
1128                 abort_creds(bprm->cred);
1129         }
1130         kfree(bprm);
1131 }
1132
1133 /*
1134  * install the new credentials for this executable
1135  */
1136 void install_exec_creds(struct linux_binprm *bprm)
1137 {
1138         security_bprm_committing_creds(bprm);
1139
1140         commit_creds(bprm->cred);
1141         bprm->cred = NULL;
1142         /*
1143          * cred_guard_mutex must be held at least to this point to prevent
1144          * ptrace_attach() from altering our determination of the task's
1145          * credentials; any time after this it may be unlocked.
1146          */
1147         security_bprm_committed_creds(bprm);
1148         mutex_unlock(&current->cred_guard_mutex);
1149 }
1150 EXPORT_SYMBOL(install_exec_creds);
1151
1152 /*
1153  * determine how safe it is to execute the proposed program
1154  * - the caller must hold current->cred_guard_mutex to protect against
1155  *   PTRACE_ATTACH
1156  */
1157 int check_unsafe_exec(struct linux_binprm *bprm)
1158 {
1159         struct task_struct *p = current, *t;
1160         unsigned n_fs;
1161         int res = 0;
1162
1163         bprm->unsafe = tracehook_unsafe_exec(p);
1164
1165         n_fs = 1;
1166         spin_lock(&p->fs->lock);
1167         rcu_read_lock();
1168         for (t = next_thread(p); t != p; t = next_thread(t)) {
1169                 if (t->fs == p->fs)
1170                         n_fs++;
1171         }
1172         rcu_read_unlock();
1173
1174         if (p->fs->users > n_fs) {
1175                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1176         } else {
1177                 res = -EAGAIN;
1178                 if (!p->fs->in_exec) {
1179                         p->fs->in_exec = 1;
1180                         res = 1;
1181                 }
1182         }
1183         spin_unlock(&p->fs->lock);
1184
1185         return res;
1186 }
1187
1188 /*
1189  * Fill the binprm structure from the inode.
1190  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1191  *
1192  * This may be called multiple times for binary chains (scripts for example).
1193  */
1194 int prepare_binprm(struct linux_binprm *bprm)
1195 {
1196         umode_t mode;
1197         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1198         int retval;
1199
1200         mode = inode->i_mode;
1201         if (bprm->file->f_op == NULL)
1202                 return -EACCES;
1203
1204         /* clear any previous set[ug]id data from a previous binary */
1205         bprm->cred->euid = current_euid();
1206         bprm->cred->egid = current_egid();
1207
1208         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1209                 /* Set-uid? */
1210                 if (mode & S_ISUID) {
1211                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1212                         bprm->cred->euid = inode->i_uid;
1213                 }
1214
1215                 /* Set-gid? */
1216                 /*
1217                  * If setgid is set but no group execute bit then this
1218                  * is a candidate for mandatory locking, not a setgid
1219                  * executable.
1220                  */
1221                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1222                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1223                         bprm->cred->egid = inode->i_gid;
1224                 }
1225         }
1226
1227         /* fill in binprm security blob */
1228         retval = security_bprm_set_creds(bprm);
1229         if (retval)
1230                 return retval;
1231         bprm->cred_prepared = 1;
1232
1233         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1234         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1235 }
1236
1237 EXPORT_SYMBOL(prepare_binprm);
1238
1239 /*
1240  * Arguments are '\0' separated strings found at the location bprm->p
1241  * points to; chop off the first by relocating brpm->p to right after
1242  * the first '\0' encountered.
1243  */
1244 int remove_arg_zero(struct linux_binprm *bprm)
1245 {
1246         int ret = 0;
1247         unsigned long offset;
1248         char *kaddr;
1249         struct page *page;
1250
1251         if (!bprm->argc)
1252                 return 0;
1253
1254         do {
1255                 offset = bprm->p & ~PAGE_MASK;
1256                 page = get_arg_page(bprm, bprm->p, 0);
1257                 if (!page) {
1258                         ret = -EFAULT;
1259                         goto out;
1260                 }
1261                 kaddr = kmap_atomic(page, KM_USER0);
1262
1263                 for (; offset < PAGE_SIZE && kaddr[offset];
1264                                 offset++, bprm->p++)
1265                         ;
1266
1267                 kunmap_atomic(kaddr, KM_USER0);
1268                 put_arg_page(page);
1269
1270                 if (offset == PAGE_SIZE)
1271                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1272         } while (offset == PAGE_SIZE);
1273
1274         bprm->p++;
1275         bprm->argc--;
1276         ret = 0;
1277
1278 out:
1279         return ret;
1280 }
1281 EXPORT_SYMBOL(remove_arg_zero);
1282
1283 /*
1284  * cycle the list of binary formats handler, until one recognizes the image
1285  */
1286 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1287 {
1288         unsigned int depth = bprm->recursion_depth;
1289         int try,retval;
1290         struct linux_binfmt *fmt;
1291
1292         retval = security_bprm_check(bprm);
1293         if (retval)
1294                 return retval;
1295
1296         /* kernel module loader fixup */
1297         /* so we don't try to load run modprobe in kernel space. */
1298         set_fs(USER_DS);
1299
1300         retval = audit_bprm(bprm);
1301         if (retval)
1302                 return retval;
1303
1304         retval = -ENOENT;
1305         for (try=0; try<2; try++) {
1306                 read_lock(&binfmt_lock);
1307                 list_for_each_entry(fmt, &formats, lh) {
1308                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1309                         if (!fn)
1310                                 continue;
1311                         if (!try_module_get(fmt->module))
1312                                 continue;
1313                         read_unlock(&binfmt_lock);
1314                         retval = fn(bprm, regs);
1315                         /*
1316                          * Restore the depth counter to its starting value
1317                          * in this call, so we don't have to rely on every
1318                          * load_binary function to restore it on return.
1319                          */
1320                         bprm->recursion_depth = depth;
1321                         if (retval >= 0) {
1322                                 if (depth == 0)
1323                                         tracehook_report_exec(fmt, bprm, regs);
1324                                 put_binfmt(fmt);
1325                                 allow_write_access(bprm->file);
1326                                 if (bprm->file)
1327                                         fput(bprm->file);
1328                                 bprm->file = NULL;
1329                                 current->did_exec = 1;
1330                                 proc_exec_connector(current);
1331                                 return retval;
1332                         }
1333                         read_lock(&binfmt_lock);
1334                         put_binfmt(fmt);
1335                         if (retval != -ENOEXEC || bprm->mm == NULL)
1336                                 break;
1337                         if (!bprm->file) {
1338                                 read_unlock(&binfmt_lock);
1339                                 return retval;
1340                         }
1341                 }
1342                 read_unlock(&binfmt_lock);
1343                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1344                         break;
1345 #ifdef CONFIG_MODULES
1346                 } else {
1347 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1348                         if (printable(bprm->buf[0]) &&
1349                             printable(bprm->buf[1]) &&
1350                             printable(bprm->buf[2]) &&
1351                             printable(bprm->buf[3]))
1352                                 break; /* -ENOEXEC */
1353                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1354 #endif
1355                 }
1356         }
1357         return retval;
1358 }
1359
1360 EXPORT_SYMBOL(search_binary_handler);
1361
1362 /*
1363  * sys_execve() executes a new program.
1364  */
1365 int do_execve(const char * filename,
1366         const char __user *const __user *argv,
1367         const char __user *const __user *envp,
1368         struct pt_regs * regs)
1369 {
1370         struct linux_binprm *bprm;
1371         struct file *file;
1372         struct files_struct *displaced;
1373         bool clear_in_exec;
1374         int retval;
1375
1376         retval = unshare_files(&displaced);
1377         if (retval)
1378                 goto out_ret;
1379
1380         retval = -ENOMEM;
1381         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1382         if (!bprm)
1383                 goto out_files;
1384
1385         retval = prepare_bprm_creds(bprm);
1386         if (retval)
1387                 goto out_free;
1388
1389         retval = check_unsafe_exec(bprm);
1390         if (retval < 0)
1391                 goto out_free;
1392         clear_in_exec = retval;
1393         current->in_execve = 1;
1394
1395         file = open_exec(filename);
1396         retval = PTR_ERR(file);
1397         if (IS_ERR(file))
1398                 goto out_unmark;
1399
1400         sched_exec();
1401
1402         bprm->file = file;
1403         bprm->filename = filename;
1404         bprm->interp = filename;
1405
1406         retval = bprm_mm_init(bprm);
1407         if (retval)
1408                 goto out_file;
1409
1410         bprm->argc = count(argv, MAX_ARG_STRINGS);
1411         if ((retval = bprm->argc) < 0)
1412                 goto out;
1413
1414         bprm->envc = count(envp, MAX_ARG_STRINGS);
1415         if ((retval = bprm->envc) < 0)
1416                 goto out;
1417
1418         retval = prepare_binprm(bprm);
1419         if (retval < 0)
1420                 goto out;
1421
1422         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1423         if (retval < 0)
1424                 goto out;
1425
1426         bprm->exec = bprm->p;
1427         retval = copy_strings(bprm->envc, envp, bprm);
1428         if (retval < 0)
1429                 goto out;
1430
1431         retval = copy_strings(bprm->argc, argv, bprm);
1432         if (retval < 0)
1433                 goto out;
1434
1435         current->flags &= ~PF_KTHREAD;
1436         retval = search_binary_handler(bprm,regs);
1437         if (retval < 0)
1438                 goto out;
1439
1440         /* execve succeeded */
1441         current->fs->in_exec = 0;
1442         current->in_execve = 0;
1443         acct_update_integrals(current);
1444         free_bprm(bprm);
1445         if (displaced)
1446                 put_files_struct(displaced);
1447         return retval;
1448
1449 out:
1450         if (bprm->mm) {
1451                 acct_arg_size(bprm, 0);
1452                 mmput(bprm->mm);
1453         }
1454
1455 out_file:
1456         if (bprm->file) {
1457                 allow_write_access(bprm->file);
1458                 fput(bprm->file);
1459         }
1460
1461 out_unmark:
1462         if (clear_in_exec)
1463                 current->fs->in_exec = 0;
1464         current->in_execve = 0;
1465
1466 out_free:
1467         free_bprm(bprm);
1468
1469 out_files:
1470         if (displaced)
1471                 reset_files_struct(displaced);
1472 out_ret:
1473         return retval;
1474 }
1475
1476 void set_binfmt(struct linux_binfmt *new)
1477 {
1478         struct mm_struct *mm = current->mm;
1479
1480         if (mm->binfmt)
1481                 module_put(mm->binfmt->module);
1482
1483         mm->binfmt = new;
1484         if (new)
1485                 __module_get(new->module);
1486 }
1487
1488 EXPORT_SYMBOL(set_binfmt);
1489
1490 /* format_corename will inspect the pattern parameter, and output a
1491  * name into corename, which must have space for at least
1492  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1493  */
1494 static int format_corename(char *corename, long signr)
1495 {
1496         const struct cred *cred = current_cred();
1497         const char *pat_ptr = core_pattern;
1498         int ispipe = (*pat_ptr == '|');
1499         char *out_ptr = corename;
1500         char *const out_end = corename + CORENAME_MAX_SIZE;
1501         int rc;
1502         int pid_in_pattern = 0;
1503
1504         /* Repeat as long as we have more pattern to process and more output
1505            space */
1506         while (*pat_ptr) {
1507                 if (*pat_ptr != '%') {
1508                         if (out_ptr == out_end)
1509                                 goto out;
1510                         *out_ptr++ = *pat_ptr++;
1511                 } else {
1512                         switch (*++pat_ptr) {
1513                         case 0:
1514                                 goto out;
1515                         /* Double percent, output one percent */
1516                         case '%':
1517                                 if (out_ptr == out_end)
1518                                         goto out;
1519                                 *out_ptr++ = '%';
1520                                 break;
1521                         /* pid */
1522                         case 'p':
1523                                 pid_in_pattern = 1;
1524                                 rc = snprintf(out_ptr, out_end - out_ptr,
1525                                               "%d", task_tgid_vnr(current));
1526                                 if (rc > out_end - out_ptr)
1527                                         goto out;
1528                                 out_ptr += rc;
1529                                 break;
1530                         /* uid */
1531                         case 'u':
1532                                 rc = snprintf(out_ptr, out_end - out_ptr,
1533                                               "%d", cred->uid);
1534                                 if (rc > out_end - out_ptr)
1535                                         goto out;
1536                                 out_ptr += rc;
1537                                 break;
1538                         /* gid */
1539                         case 'g':
1540                                 rc = snprintf(out_ptr, out_end - out_ptr,
1541                                               "%d", cred->gid);
1542                                 if (rc > out_end - out_ptr)
1543                                         goto out;
1544                                 out_ptr += rc;
1545                                 break;
1546                         /* signal that caused the coredump */
1547                         case 's':
1548                                 rc = snprintf(out_ptr, out_end - out_ptr,
1549                                               "%ld", signr);
1550                                 if (rc > out_end - out_ptr)
1551                                         goto out;
1552                                 out_ptr += rc;
1553                                 break;
1554                         /* UNIX time of coredump */
1555                         case 't': {
1556                                 struct timeval tv;
1557                                 do_gettimeofday(&tv);
1558                                 rc = snprintf(out_ptr, out_end - out_ptr,
1559                                               "%lu", tv.tv_sec);
1560                                 if (rc > out_end - out_ptr)
1561                                         goto out;
1562                                 out_ptr += rc;
1563                                 break;
1564                         }
1565                         /* hostname */
1566                         case 'h':
1567                                 down_read(&uts_sem);
1568                                 rc = snprintf(out_ptr, out_end - out_ptr,
1569                                               "%s", utsname()->nodename);
1570                                 up_read(&uts_sem);
1571                                 if (rc > out_end - out_ptr)
1572                                         goto out;
1573                                 out_ptr += rc;
1574                                 break;
1575                         /* executable */
1576                         case 'e':
1577                                 rc = snprintf(out_ptr, out_end - out_ptr,
1578                                               "%s", current->comm);
1579                                 if (rc > out_end - out_ptr)
1580                                         goto out;
1581                                 out_ptr += rc;
1582                                 break;
1583                         /* core limit size */
1584                         case 'c':
1585                                 rc = snprintf(out_ptr, out_end - out_ptr,
1586                                               "%lu", rlimit(RLIMIT_CORE));
1587                                 if (rc > out_end - out_ptr)
1588                                         goto out;
1589                                 out_ptr += rc;
1590                                 break;
1591                         default:
1592                                 break;
1593                         }
1594                         ++pat_ptr;
1595                 }
1596         }
1597         /* Backward compatibility with core_uses_pid:
1598          *
1599          * If core_pattern does not include a %p (as is the default)
1600          * and core_uses_pid is set, then .%pid will be appended to
1601          * the filename. Do not do this for piped commands. */
1602         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1603                 rc = snprintf(out_ptr, out_end - out_ptr,
1604                               ".%d", task_tgid_vnr(current));
1605                 if (rc > out_end - out_ptr)
1606                         goto out;
1607                 out_ptr += rc;
1608         }
1609 out:
1610         *out_ptr = 0;
1611         return ispipe;
1612 }
1613
1614 static int zap_process(struct task_struct *start, int exit_code)
1615 {
1616         struct task_struct *t;
1617         int nr = 0;
1618
1619         start->signal->flags = SIGNAL_GROUP_EXIT;
1620         start->signal->group_exit_code = exit_code;
1621         start->signal->group_stop_count = 0;
1622
1623         t = start;
1624         do {
1625                 if (t != current && t->mm) {
1626                         sigaddset(&t->pending.signal, SIGKILL);
1627                         signal_wake_up(t, 1);
1628                         nr++;
1629                 }
1630         } while_each_thread(start, t);
1631
1632         return nr;
1633 }
1634
1635 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1636                                 struct core_state *core_state, int exit_code)
1637 {
1638         struct task_struct *g, *p;
1639         unsigned long flags;
1640         int nr = -EAGAIN;
1641
1642         spin_lock_irq(&tsk->sighand->siglock);
1643         if (!signal_group_exit(tsk->signal)) {
1644                 mm->core_state = core_state;
1645                 nr = zap_process(tsk, exit_code);
1646         }
1647         spin_unlock_irq(&tsk->sighand->siglock);
1648         if (unlikely(nr < 0))
1649                 return nr;
1650
1651         if (atomic_read(&mm->mm_users) == nr + 1)
1652                 goto done;
1653         /*
1654          * We should find and kill all tasks which use this mm, and we should
1655          * count them correctly into ->nr_threads. We don't take tasklist
1656          * lock, but this is safe wrt:
1657          *
1658          * fork:
1659          *      None of sub-threads can fork after zap_process(leader). All
1660          *      processes which were created before this point should be
1661          *      visible to zap_threads() because copy_process() adds the new
1662          *      process to the tail of init_task.tasks list, and lock/unlock
1663          *      of ->siglock provides a memory barrier.
1664          *
1665          * do_exit:
1666          *      The caller holds mm->mmap_sem. This means that the task which
1667          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1668          *      its ->mm.
1669          *
1670          * de_thread:
1671          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1672          *      we must see either old or new leader, this does not matter.
1673          *      However, it can change p->sighand, so lock_task_sighand(p)
1674          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1675          *      it can't fail.
1676          *
1677          *      Note also that "g" can be the old leader with ->mm == NULL
1678          *      and already unhashed and thus removed from ->thread_group.
1679          *      This is OK, __unhash_process()->list_del_rcu() does not
1680          *      clear the ->next pointer, we will find the new leader via
1681          *      next_thread().
1682          */
1683         rcu_read_lock();
1684         for_each_process(g) {
1685                 if (g == tsk->group_leader)
1686                         continue;
1687                 if (g->flags & PF_KTHREAD)
1688                         continue;
1689                 p = g;
1690                 do {
1691                         if (p->mm) {
1692                                 if (unlikely(p->mm == mm)) {
1693                                         lock_task_sighand(p, &flags);
1694                                         nr += zap_process(p, exit_code);
1695                                         unlock_task_sighand(p, &flags);
1696                                 }
1697                                 break;
1698                         }
1699                 } while_each_thread(g, p);
1700         }
1701         rcu_read_unlock();
1702 done:
1703         atomic_set(&core_state->nr_threads, nr);
1704         return nr;
1705 }
1706
1707 static int coredump_wait(int exit_code, struct core_state *core_state)
1708 {
1709         struct task_struct *tsk = current;
1710         struct mm_struct *mm = tsk->mm;
1711         struct completion *vfork_done;
1712         int core_waiters = -EBUSY;
1713
1714         init_completion(&core_state->startup);
1715         core_state->dumper.task = tsk;
1716         core_state->dumper.next = NULL;
1717
1718         down_write(&mm->mmap_sem);
1719         if (!mm->core_state)
1720                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1721         up_write(&mm->mmap_sem);
1722
1723         if (unlikely(core_waiters < 0))
1724                 goto fail;
1725
1726         /*
1727          * Make sure nobody is waiting for us to release the VM,
1728          * otherwise we can deadlock when we wait on each other
1729          */
1730         vfork_done = tsk->vfork_done;
1731         if (vfork_done) {
1732                 tsk->vfork_done = NULL;
1733                 complete(vfork_done);
1734         }
1735
1736         if (core_waiters)
1737                 wait_for_completion(&core_state->startup);
1738 fail:
1739         return core_waiters;
1740 }
1741
1742 static void coredump_finish(struct mm_struct *mm)
1743 {
1744         struct core_thread *curr, *next;
1745         struct task_struct *task;
1746
1747         next = mm->core_state->dumper.next;
1748         while ((curr = next) != NULL) {
1749                 next = curr->next;
1750                 task = curr->task;
1751                 /*
1752                  * see exit_mm(), curr->task must not see
1753                  * ->task == NULL before we read ->next.
1754                  */
1755                 smp_mb();
1756                 curr->task = NULL;
1757                 wake_up_process(task);
1758         }
1759
1760         mm->core_state = NULL;
1761 }
1762
1763 /*
1764  * set_dumpable converts traditional three-value dumpable to two flags and
1765  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1766  * these bits are not changed atomically.  So get_dumpable can observe the
1767  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1768  * return either old dumpable or new one by paying attention to the order of
1769  * modifying the bits.
1770  *
1771  * dumpable |   mm->flags (binary)
1772  * old  new | initial interim  final
1773  * ---------+-----------------------
1774  *  0    1  |   00      01      01
1775  *  0    2  |   00      10(*)   11
1776  *  1    0  |   01      00      00
1777  *  1    2  |   01      11      11
1778  *  2    0  |   11      10(*)   00
1779  *  2    1  |   11      11      01
1780  *
1781  * (*) get_dumpable regards interim value of 10 as 11.
1782  */
1783 void set_dumpable(struct mm_struct *mm, int value)
1784 {
1785         switch (value) {
1786         case 0:
1787                 clear_bit(MMF_DUMPABLE, &mm->flags);
1788                 smp_wmb();
1789                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1790                 break;
1791         case 1:
1792                 set_bit(MMF_DUMPABLE, &mm->flags);
1793                 smp_wmb();
1794                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1795                 break;
1796         case 2:
1797                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1798                 smp_wmb();
1799                 set_bit(MMF_DUMPABLE, &mm->flags);
1800                 break;
1801         }
1802 }
1803
1804 static int __get_dumpable(unsigned long mm_flags)
1805 {
1806         int ret;
1807
1808         ret = mm_flags & MMF_DUMPABLE_MASK;
1809         return (ret >= 2) ? 2 : ret;
1810 }
1811
1812 int get_dumpable(struct mm_struct *mm)
1813 {
1814         return __get_dumpable(mm->flags);
1815 }
1816
1817 static void wait_for_dump_helpers(struct file *file)
1818 {
1819         struct pipe_inode_info *pipe;
1820
1821         pipe = file->f_path.dentry->d_inode->i_pipe;
1822
1823         pipe_lock(pipe);
1824         pipe->readers++;
1825         pipe->writers--;
1826
1827         while ((pipe->readers > 1) && (!signal_pending(current))) {
1828                 wake_up_interruptible_sync(&pipe->wait);
1829                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1830                 pipe_wait(pipe);
1831         }
1832
1833         pipe->readers--;
1834         pipe->writers++;
1835         pipe_unlock(pipe);
1836
1837 }
1838
1839
1840 /*
1841  * uhm_pipe_setup
1842  * helper function to customize the process used
1843  * to collect the core in userspace.  Specifically
1844  * it sets up a pipe and installs it as fd 0 (stdin)
1845  * for the process.  Returns 0 on success, or
1846  * PTR_ERR on failure.
1847  * Note that it also sets the core limit to 1.  This
1848  * is a special value that we use to trap recursive
1849  * core dumps
1850  */
1851 static int umh_pipe_setup(struct subprocess_info *info)
1852 {
1853         struct file *rp, *wp;
1854         struct fdtable *fdt;
1855         struct coredump_params *cp = (struct coredump_params *)info->data;
1856         struct files_struct *cf = current->files;
1857
1858         wp = create_write_pipe(0);
1859         if (IS_ERR(wp))
1860                 return PTR_ERR(wp);
1861
1862         rp = create_read_pipe(wp, 0);
1863         if (IS_ERR(rp)) {
1864                 free_write_pipe(wp);
1865                 return PTR_ERR(rp);
1866         }
1867
1868         cp->file = wp;
1869
1870         sys_close(0);
1871         fd_install(0, rp);
1872         spin_lock(&cf->file_lock);
1873         fdt = files_fdtable(cf);
1874         FD_SET(0, fdt->open_fds);
1875         FD_CLR(0, fdt->close_on_exec);
1876         spin_unlock(&cf->file_lock);
1877
1878         /* and disallow core files too */
1879         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
1880
1881         return 0;
1882 }
1883
1884 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1885 {
1886         struct core_state core_state;
1887         char corename[CORENAME_MAX_SIZE + 1];
1888         struct mm_struct *mm = current->mm;
1889         struct linux_binfmt * binfmt;
1890         const struct cred *old_cred;
1891         struct cred *cred;
1892         int retval = 0;
1893         int flag = 0;
1894         int ispipe;
1895         static atomic_t core_dump_count = ATOMIC_INIT(0);
1896         struct coredump_params cprm = {
1897                 .signr = signr,
1898                 .regs = regs,
1899                 .limit = rlimit(RLIMIT_CORE),
1900                 /*
1901                  * We must use the same mm->flags while dumping core to avoid
1902                  * inconsistency of bit flags, since this flag is not protected
1903                  * by any locks.
1904                  */
1905                 .mm_flags = mm->flags,
1906         };
1907
1908         audit_core_dumps(signr);
1909
1910         binfmt = mm->binfmt;
1911         if (!binfmt || !binfmt->core_dump)
1912                 goto fail;
1913         if (!__get_dumpable(cprm.mm_flags))
1914                 goto fail;
1915
1916         cred = prepare_creds();
1917         if (!cred)
1918                 goto fail;
1919         /*
1920          *      We cannot trust fsuid as being the "true" uid of the
1921          *      process nor do we know its entire history. We only know it
1922          *      was tainted so we dump it as root in mode 2.
1923          */
1924         if (__get_dumpable(cprm.mm_flags) == 2) {
1925                 /* Setuid core dump mode */
1926                 flag = O_EXCL;          /* Stop rewrite attacks */
1927                 cred->fsuid = 0;        /* Dump root private */
1928         }
1929
1930         retval = coredump_wait(exit_code, &core_state);
1931         if (retval < 0)
1932                 goto fail_creds;
1933
1934         old_cred = override_creds(cred);
1935
1936         /*
1937          * Clear any false indication of pending signals that might
1938          * be seen by the filesystem code called to write the core file.
1939          */
1940         clear_thread_flag(TIF_SIGPENDING);
1941
1942         ispipe = format_corename(corename, signr);
1943
1944         if (ispipe) {
1945                 int dump_count;
1946                 char **helper_argv;
1947
1948                 if (cprm.limit == 1) {
1949                         /*
1950                          * Normally core limits are irrelevant to pipes, since
1951                          * we're not writing to the file system, but we use
1952                          * cprm.limit of 1 here as a speacial value. Any
1953                          * non-1 limit gets set to RLIM_INFINITY below, but
1954                          * a limit of 0 skips the dump.  This is a consistent
1955                          * way to catch recursive crashes.  We can still crash
1956                          * if the core_pattern binary sets RLIM_CORE =  !1
1957                          * but it runs as root, and can do lots of stupid things
1958                          * Note that we use task_tgid_vnr here to grab the pid
1959                          * of the process group leader.  That way we get the
1960                          * right pid if a thread in a multi-threaded
1961                          * core_pattern process dies.
1962                          */
1963                         printk(KERN_WARNING
1964                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
1965                                 task_tgid_vnr(current), current->comm);
1966                         printk(KERN_WARNING "Aborting core\n");
1967                         goto fail_unlock;
1968                 }
1969                 cprm.limit = RLIM_INFINITY;
1970
1971                 dump_count = atomic_inc_return(&core_dump_count);
1972                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
1973                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
1974                                task_tgid_vnr(current), current->comm);
1975                         printk(KERN_WARNING "Skipping core dump\n");
1976                         goto fail_dropcount;
1977                 }
1978
1979                 helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
1980                 if (!helper_argv) {
1981                         printk(KERN_WARNING "%s failed to allocate memory\n",
1982                                __func__);
1983                         goto fail_dropcount;
1984                 }
1985
1986                 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
1987                                         NULL, UMH_WAIT_EXEC, umh_pipe_setup,
1988                                         NULL, &cprm);
1989                 argv_free(helper_argv);
1990                 if (retval) {
1991                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1992                                corename);
1993                         goto close_fail;
1994                 }
1995         } else {
1996                 struct inode *inode;
1997
1998                 if (cprm.limit < binfmt->min_coredump)
1999                         goto fail_unlock;
2000
2001                 cprm.file = filp_open(corename,
2002                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2003                                  0600);
2004                 if (IS_ERR(cprm.file))
2005                         goto fail_unlock;
2006
2007                 inode = cprm.file->f_path.dentry->d_inode;
2008                 if (inode->i_nlink > 1)
2009                         goto close_fail;
2010                 if (d_unhashed(cprm.file->f_path.dentry))
2011                         goto close_fail;
2012                 /*
2013                  * AK: actually i see no reason to not allow this for named
2014                  * pipes etc, but keep the previous behaviour for now.
2015                  */
2016                 if (!S_ISREG(inode->i_mode))
2017                         goto close_fail;
2018                 /*
2019                  * Dont allow local users get cute and trick others to coredump
2020                  * into their pre-created files.
2021                  */
2022                 if (inode->i_uid != current_fsuid())
2023                         goto close_fail;
2024                 if (!cprm.file->f_op || !cprm.file->f_op->write)
2025                         goto close_fail;
2026                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2027                         goto close_fail;
2028         }
2029
2030         retval = binfmt->core_dump(&cprm);
2031         if (retval)
2032                 current->signal->group_exit_code |= 0x80;
2033
2034         if (ispipe && core_pipe_limit)
2035                 wait_for_dump_helpers(cprm.file);
2036 close_fail:
2037         if (cprm.file)
2038                 filp_close(cprm.file, NULL);
2039 fail_dropcount:
2040         if (ispipe)
2041                 atomic_dec(&core_dump_count);
2042 fail_unlock:
2043         coredump_finish(mm);
2044         revert_creds(old_cred);
2045 fail_creds:
2046         put_cred(cred);
2047 fail:
2048         return;
2049 }
2050
2051 /*
2052  * Core dumping helper functions.  These are the only things you should
2053  * do on a core-file: use only these functions to write out all the
2054  * necessary info.
2055  */
2056 int dump_write(struct file *file, const void *addr, int nr)
2057 {
2058         return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2059 }
2060 EXPORT_SYMBOL(dump_write);
2061
2062 int dump_seek(struct file *file, loff_t off)
2063 {
2064         int ret = 1;
2065
2066         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2067                 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2068                         return 0;
2069         } else {
2070                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2071
2072                 if (!buf)
2073                         return 0;
2074                 while (off > 0) {
2075                         unsigned long n = off;
2076
2077                         if (n > PAGE_SIZE)
2078                                 n = PAGE_SIZE;
2079                         if (!dump_write(file, buf, n)) {
2080                                 ret = 0;
2081                                 break;
2082                         }
2083                         off -= n;
2084                 }
2085                 free_page((unsigned long)buf);
2086         }
2087         return ret;
2088 }
2089 EXPORT_SYMBOL(dump_seek);