linux/fs/exec.c
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   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/mount.h>
  46#include <linux/security.h>
  47#include <linux/syscalls.h>
  48#include <linux/tsacct_kern.h>
  49#include <linux/cn_proc.h>
  50#include <linux/audit.h>
  51#include <linux/tracehook.h>
  52#include <linux/kmod.h>
  53#include <linux/fsnotify.h>
  54#include <linux/fs_struct.h>
  55#include <linux/pipe_fs_i.h>
  56#include <linux/oom.h>
  57#include <linux/compat.h>
  58
  59#include <asm/uaccess.h>
  60#include <asm/mmu_context.h>
  61#include <asm/tlb.h>
  62#include "internal.h"
  63
  64int core_uses_pid;
  65char core_pattern[CORENAME_MAX_SIZE] = "core";
  66unsigned int core_pipe_limit;
  67int suid_dumpable = 0;
  68
  69struct core_name {
  70        char *corename;
  71        int used, size;
  72};
  73static atomic_t call_count = ATOMIC_INIT(1);
  74
  75/* The maximal length of core_pattern is also specified in sysctl.c */
  76
  77static LIST_HEAD(formats);
  78static DEFINE_RWLOCK(binfmt_lock);
  79
  80int __register_binfmt(struct linux_binfmt * fmt, int insert)
  81{
  82        if (!fmt)
  83                return -EINVAL;
  84        write_lock(&binfmt_lock);
  85        insert ? list_add(&fmt->lh, &formats) :
  86                 list_add_tail(&fmt->lh, &formats);
  87        write_unlock(&binfmt_lock);
  88        return 0;       
  89}
  90
  91EXPORT_SYMBOL(__register_binfmt);
  92
  93void unregister_binfmt(struct linux_binfmt * fmt)
  94{
  95        write_lock(&binfmt_lock);
  96        list_del(&fmt->lh);
  97        write_unlock(&binfmt_lock);
  98}
  99
 100EXPORT_SYMBOL(unregister_binfmt);
 101
 102static inline void put_binfmt(struct linux_binfmt * fmt)
 103{
 104        module_put(fmt->module);
 105}
 106
 107/*
 108 * Note that a shared library must be both readable and executable due to
 109 * security reasons.
 110 *
 111 * Also note that we take the address to load from from the file itself.
 112 */
 113SYSCALL_DEFINE1(uselib, const char __user *, library)
 114{
 115        struct file *file;
 116        char *tmp = getname(library);
 117        int error = PTR_ERR(tmp);
 118        static const struct open_flags uselib_flags = {
 119                .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 120                .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
 121                .intent = LOOKUP_OPEN
 122        };
 123
 124        if (IS_ERR(tmp))
 125                goto out;
 126
 127        file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
 128        putname(tmp);
 129        error = PTR_ERR(file);
 130        if (IS_ERR(file))
 131                goto out;
 132
 133        error = -EINVAL;
 134        if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 135                goto exit;
 136
 137        error = -EACCES;
 138        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 139                goto exit;
 140
 141        fsnotify_open(file);
 142
 143        error = -ENOEXEC;
 144        if(file->f_op) {
 145                struct linux_binfmt * fmt;
 146
 147                read_lock(&binfmt_lock);
 148                list_for_each_entry(fmt, &formats, lh) {
 149                        if (!fmt->load_shlib)
 150                                continue;
 151                        if (!try_module_get(fmt->module))
 152                                continue;
 153                        read_unlock(&binfmt_lock);
 154                        error = fmt->load_shlib(file);
 155                        read_lock(&binfmt_lock);
 156                        put_binfmt(fmt);
 157                        if (error != -ENOEXEC)
 158                                break;
 159                }
 160                read_unlock(&binfmt_lock);
 161        }
 162exit:
 163        fput(file);
 164out:
 165        return error;
 166}
 167
 168#ifdef CONFIG_MMU
 169/*
 170 * The nascent bprm->mm is not visible until exec_mmap() but it can
 171 * use a lot of memory, account these pages in current->mm temporary
 172 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 173 * change the counter back via acct_arg_size(0).
 174 */
 175static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 176{
 177        struct mm_struct *mm = current->mm;
 178        long diff = (long)(pages - bprm->vma_pages);
 179
 180        if (!mm || !diff)
 181                return;
 182
 183        bprm->vma_pages = pages;
 184
 185#ifdef SPLIT_RSS_COUNTING
 186        add_mm_counter(mm, MM_ANONPAGES, diff);
 187#else
 188        spin_lock(&mm->page_table_lock);
 189        add_mm_counter(mm, MM_ANONPAGES, diff);
 190        spin_unlock(&mm->page_table_lock);
 191#endif
 192}
 193
 194static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 195                int write)
 196{
 197        struct page *page;
 198        int ret;
 199
 200#ifdef CONFIG_STACK_GROWSUP
 201        if (write) {
 202                ret = expand_downwards(bprm->vma, pos);
 203                if (ret < 0)
 204                        return NULL;
 205        }
 206#endif
 207        ret = get_user_pages(current, bprm->mm, pos,
 208                        1, write, 1, &page, NULL);
 209        if (ret <= 0)
 210                return NULL;
 211
 212        if (write) {
 213                unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 214                struct rlimit *rlim;
 215
 216                acct_arg_size(bprm, size / PAGE_SIZE);
 217
 218                /*
 219                 * We've historically supported up to 32 pages (ARG_MAX)
 220                 * of argument strings even with small stacks
 221                 */
 222                if (size <= ARG_MAX)
 223                        return page;
 224
 225                /*
 226                 * Limit to 1/4-th the stack size for the argv+env strings.
 227                 * This ensures that:
 228                 *  - the remaining binfmt code will not run out of stack space,
 229                 *  - the program will have a reasonable amount of stack left
 230                 *    to work from.
 231                 */
 232                rlim = current->signal->rlim;
 233                if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 234                        put_page(page);
 235                        return NULL;
 236                }
 237        }
 238
 239        return page;
 240}
 241
 242static void put_arg_page(struct page *page)
 243{
 244        put_page(page);
 245}
 246
 247static void free_arg_page(struct linux_binprm *bprm, int i)
 248{
 249}
 250
 251static void free_arg_pages(struct linux_binprm *bprm)
 252{
 253}
 254
 255static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 256                struct page *page)
 257{
 258        flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 259}
 260
 261static int __bprm_mm_init(struct linux_binprm *bprm)
 262{
 263        int err;
 264        struct vm_area_struct *vma = NULL;
 265        struct mm_struct *mm = bprm->mm;
 266
 267        bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 268        if (!vma)
 269                return -ENOMEM;
 270
 271        down_write(&mm->mmap_sem);
 272        vma->vm_mm = mm;
 273
 274        /*
 275         * Place the stack at the largest stack address the architecture
 276         * supports. Later, we'll move this to an appropriate place. We don't
 277         * use STACK_TOP because that can depend on attributes which aren't
 278         * configured yet.
 279         */
 280        BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 281        vma->vm_end = STACK_TOP_MAX;
 282        vma->vm_start = vma->vm_end - PAGE_SIZE;
 283        vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 284        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 285        INIT_LIST_HEAD(&vma->anon_vma_chain);
 286
 287        err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
 288        if (err)
 289                goto err;
 290
 291        err = insert_vm_struct(mm, vma);
 292        if (err)
 293                goto err;
 294
 295        mm->stack_vm = mm->total_vm = 1;
 296        up_write(&mm->mmap_sem);
 297        bprm->p = vma->vm_end - sizeof(void *);
 298        return 0;
 299err:
 300        up_write(&mm->mmap_sem);
 301        bprm->vma = NULL;
 302        kmem_cache_free(vm_area_cachep, vma);
 303        return err;
 304}
 305
 306static bool valid_arg_len(struct linux_binprm *bprm, long len)
 307{
 308        return len <= MAX_ARG_STRLEN;
 309}
 310
 311#else
 312
 313static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 314{
 315}
 316
 317static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 318                int write)
 319{
 320        struct page *page;
 321
 322        page = bprm->page[pos / PAGE_SIZE];
 323        if (!page && write) {
 324                page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 325                if (!page)
 326                        return NULL;
 327                bprm->page[pos / PAGE_SIZE] = page;
 328        }
 329
 330        return page;
 331}
 332
 333static void put_arg_page(struct page *page)
 334{
 335}
 336
 337static void free_arg_page(struct linux_binprm *bprm, int i)
 338{
 339        if (bprm->page[i]) {
 340                __free_page(bprm->page[i]);
 341                bprm->page[i] = NULL;
 342        }
 343}
 344
 345static void free_arg_pages(struct linux_binprm *bprm)
 346{
 347        int i;
 348
 349        for (i = 0; i < MAX_ARG_PAGES; i++)
 350                free_arg_page(bprm, i);
 351}
 352
 353static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 354                struct page *page)
 355{
 356}
 357
 358static int __bprm_mm_init(struct linux_binprm *bprm)
 359{
 360        bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 361        return 0;
 362}
 363
 364static bool valid_arg_len(struct linux_binprm *bprm, long len)
 365{
 366        return len <= bprm->p;
 367}
 368
 369#endif /* CONFIG_MMU */
 370
 371/*
 372 * Create a new mm_struct and populate it with a temporary stack
 373 * vm_area_struct.  We don't have enough context at this point to set the stack
 374 * flags, permissions, and offset, so we use temporary values.  We'll update
 375 * them later in setup_arg_pages().
 376 */
 377int bprm_mm_init(struct linux_binprm *bprm)
 378{
 379        int err;
 380        struct mm_struct *mm = NULL;
 381
 382        bprm->mm = mm = mm_alloc();
 383        err = -ENOMEM;
 384        if (!mm)
 385                goto err;
 386
 387        err = init_new_context(current, mm);
 388        if (err)
 389                goto err;
 390
 391        err = __bprm_mm_init(bprm);
 392        if (err)
 393                goto err;
 394
 395        return 0;
 396
 397err:
 398        if (mm) {
 399                bprm->mm = NULL;
 400                mmdrop(mm);
 401        }
 402
 403        return err;
 404}
 405
 406struct user_arg_ptr {
 407#ifdef CONFIG_COMPAT
 408        bool is_compat;
 409#endif
 410        union {
 411                const char __user *const __user *native;
 412#ifdef CONFIG_COMPAT
 413                compat_uptr_t __user *compat;
 414#endif
 415        } ptr;
 416};
 417
 418static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 419{
 420        const char __user *native;
 421
 422#ifdef CONFIG_COMPAT
 423        if (unlikely(argv.is_compat)) {
 424                compat_uptr_t compat;
 425
 426                if (get_user(compat, argv.ptr.compat + nr))
 427                        return ERR_PTR(-EFAULT);
 428
 429                return compat_ptr(compat);
 430        }
 431#endif
 432
 433        if (get_user(native, argv.ptr.native + nr))
 434                return ERR_PTR(-EFAULT);
 435
 436        return native;
 437}
 438
 439/*
 440 * count() counts the number of strings in array ARGV.
 441 */
 442static int count(struct user_arg_ptr argv, int max)
 443{
 444        int i = 0;
 445
 446        if (argv.ptr.native != NULL) {
 447                for (;;) {
 448                        const char __user *p = get_user_arg_ptr(argv, i);
 449
 450                        if (!p)
 451                                break;
 452
 453                        if (IS_ERR(p))
 454                                return -EFAULT;
 455
 456                        if (i++ >= max)
 457                                return -E2BIG;
 458
 459                        if (fatal_signal_pending(current))
 460                                return -ERESTARTNOHAND;
 461                        cond_resched();
 462                }
 463        }
 464        return i;
 465}
 466
 467/*
 468 * 'copy_strings()' copies argument/environment strings from the old
 469 * processes's memory to the new process's stack.  The call to get_user_pages()
 470 * ensures the destination page is created and not swapped out.
 471 */
 472static int copy_strings(int argc, struct user_arg_ptr argv,
 473                        struct linux_binprm *bprm)
 474{
 475        struct page *kmapped_page = NULL;
 476        char *kaddr = NULL;
 477        unsigned long kpos = 0;
 478        int ret;
 479
 480        while (argc-- > 0) {
 481                const char __user *str;
 482                int len;
 483                unsigned long pos;
 484
 485                ret = -EFAULT;
 486                str = get_user_arg_ptr(argv, argc);
 487                if (IS_ERR(str))
 488                        goto out;
 489
 490                len = strnlen_user(str, MAX_ARG_STRLEN);
 491                if (!len)
 492                        goto out;
 493
 494                ret = -E2BIG;
 495                if (!valid_arg_len(bprm, len))
 496                        goto out;
 497
 498                /* We're going to work our way backwords. */
 499                pos = bprm->p;
 500                str += len;
 501                bprm->p -= len;
 502
 503                while (len > 0) {
 504                        int offset, bytes_to_copy;
 505
 506                        if (fatal_signal_pending(current)) {
 507                                ret = -ERESTARTNOHAND;
 508                                goto out;
 509                        }
 510                        cond_resched();
 511
 512                        offset = pos % PAGE_SIZE;
 513                        if (offset == 0)
 514                                offset = PAGE_SIZE;
 515
 516                        bytes_to_copy = offset;
 517                        if (bytes_to_copy > len)
 518                                bytes_to_copy = len;
 519
 520                        offset -= bytes_to_copy;
 521                        pos -= bytes_to_copy;
 522                        str -= bytes_to_copy;
 523                        len -= bytes_to_copy;
 524
 525                        if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 526                                struct page *page;
 527
 528                                page = get_arg_page(bprm, pos, 1);
 529                                if (!page) {
 530                                        ret = -E2BIG;
 531                                        goto out;
 532                                }
 533
 534                                if (kmapped_page) {
 535                                        flush_kernel_dcache_page(kmapped_page);
 536                                        kunmap(kmapped_page);
 537                                        put_arg_page(kmapped_page);
 538                                }
 539                                kmapped_page = page;
 540                                kaddr = kmap(kmapped_page);
 541                                kpos = pos & PAGE_MASK;
 542                                flush_arg_page(bprm, kpos, kmapped_page);
 543                        }
 544                        if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 545                                ret = -EFAULT;
 546                                goto out;
 547                        }
 548                }
 549        }
 550        ret = 0;
 551out:
 552        if (kmapped_page) {
 553                flush_kernel_dcache_page(kmapped_page);
 554                kunmap(kmapped_page);
 555                put_arg_page(kmapped_page);
 556        }
 557        return ret;
 558}
 559
 560/*
 561 * Like copy_strings, but get argv and its values from kernel memory.
 562 */
 563int copy_strings_kernel(int argc, const char *const *__argv,
 564                        struct linux_binprm *bprm)
 565{
 566        int r;
 567        mm_segment_t oldfs = get_fs();
 568        struct user_arg_ptr argv = {
 569                .ptr.native = (const char __user *const  __user *)__argv,
 570        };
 571
 572        set_fs(KERNEL_DS);
 573        r = copy_strings(argc, argv, bprm);
 574        set_fs(oldfs);
 575
 576        return r;
 577}
 578EXPORT_SYMBOL(copy_strings_kernel);
 579
 580#ifdef CONFIG_MMU
 581
 582/*
 583 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 584 * the binfmt code determines where the new stack should reside, we shift it to
 585 * its final location.  The process proceeds as follows:
 586 *
 587 * 1) Use shift to calculate the new vma endpoints.
 588 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 589 *    arguments passed to subsequent functions are consistent.
 590 * 3) Move vma's page tables to the new range.
 591 * 4) Free up any cleared pgd range.
 592 * 5) Shrink the vma to cover only the new range.
 593 */
 594static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 595{
 596        struct mm_struct *mm = vma->vm_mm;
 597        unsigned long old_start = vma->vm_start;
 598        unsigned long old_end = vma->vm_end;
 599        unsigned long length = old_end - old_start;
 600        unsigned long new_start = old_start - shift;
 601        unsigned long new_end = old_end - shift;
 602        struct mmu_gather tlb;
 603
 604        BUG_ON(new_start > new_end);
 605
 606        /*
 607         * ensure there are no vmas between where we want to go
 608         * and where we are
 609         */
 610        if (vma != find_vma(mm, new_start))
 611                return -EFAULT;
 612
 613        /*
 614         * cover the whole range: [new_start, old_end)
 615         */
 616        if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 617                return -ENOMEM;
 618
 619        /*
 620         * move the page tables downwards, on failure we rely on
 621         * process cleanup to remove whatever mess we made.
 622         */
 623        if (length != move_page_tables(vma, old_start,
 624                                       vma, new_start, length))
 625                return -ENOMEM;
 626
 627        lru_add_drain();
 628        tlb_gather_mmu(&tlb, mm, 0);
 629        if (new_end > old_start) {
 630                /*
 631                 * when the old and new regions overlap clear from new_end.
 632                 */
 633                free_pgd_range(&tlb, new_end, old_end, new_end,
 634                        vma->vm_next ? vma->vm_next->vm_start : 0);
 635        } else {
 636                /*
 637                 * otherwise, clean from old_start; this is done to not touch
 638                 * the address space in [new_end, old_start) some architectures
 639                 * have constraints on va-space that make this illegal (IA64) -
 640                 * for the others its just a little faster.
 641                 */
 642                free_pgd_range(&tlb, old_start, old_end, new_end,
 643                        vma->vm_next ? vma->vm_next->vm_start : 0);
 644        }
 645        tlb_finish_mmu(&tlb, new_end, old_end);
 646
 647        /*
 648         * Shrink the vma to just the new range.  Always succeeds.
 649         */
 650        vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 651
 652        return 0;
 653}
 654
 655/*
 656 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 657 * the stack is optionally relocated, and some extra space is added.
 658 */
 659int setup_arg_pages(struct linux_binprm *bprm,
 660                    unsigned long stack_top,
 661                    int executable_stack)
 662{
 663        unsigned long ret;
 664        unsigned long stack_shift;
 665        struct mm_struct *mm = current->mm;
 666        struct vm_area_struct *vma = bprm->vma;
 667        struct vm_area_struct *prev = NULL;
 668        unsigned long vm_flags;
 669        unsigned long stack_base;
 670        unsigned long stack_size;
 671        unsigned long stack_expand;
 672        unsigned long rlim_stack;
 673
 674#ifdef CONFIG_STACK_GROWSUP
 675        /* Limit stack size to 1GB */
 676        stack_base = rlimit_max(RLIMIT_STACK);
 677        if (stack_base > (1 << 30))
 678                stack_base = 1 << 30;
 679
 680        /* Make sure we didn't let the argument array grow too large. */
 681        if (vma->vm_end - vma->vm_start > stack_base)
 682                return -ENOMEM;
 683
 684        stack_base = PAGE_ALIGN(stack_top - stack_base);
 685
 686        stack_shift = vma->vm_start - stack_base;
 687        mm->arg_start = bprm->p - stack_shift;
 688        bprm->p = vma->vm_end - stack_shift;
 689#else
 690        stack_top = arch_align_stack(stack_top);
 691        stack_top = PAGE_ALIGN(stack_top);
 692
 693        if (unlikely(stack_top < mmap_min_addr) ||
 694            unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 695                return -ENOMEM;
 696
 697        stack_shift = vma->vm_end - stack_top;
 698
 699        bprm->p -= stack_shift;
 700        mm->arg_start = bprm->p;
 701#endif
 702
 703        if (bprm->loader)
 704                bprm->loader -= stack_shift;
 705        bprm->exec -= stack_shift;
 706
 707        down_write(&mm->mmap_sem);
 708        vm_flags = VM_STACK_FLAGS;
 709
 710        /*
 711         * Adjust stack execute permissions; explicitly enable for
 712         * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 713         * (arch default) otherwise.
 714         */
 715        if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 716                vm_flags |= VM_EXEC;
 717        else if (executable_stack == EXSTACK_DISABLE_X)
 718                vm_flags &= ~VM_EXEC;
 719        vm_flags |= mm->def_flags;
 720        vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 721
 722        ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 723                        vm_flags);
 724        if (ret)
 725                goto out_unlock;
 726        BUG_ON(prev != vma);
 727
 728        /* Move stack pages down in memory. */
 729        if (stack_shift) {
 730                ret = shift_arg_pages(vma, stack_shift);
 731                if (ret)
 732                        goto out_unlock;
 733        }
 734
 735        /* mprotect_fixup is overkill to remove the temporary stack flags */
 736        vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 737
 738        stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 739        stack_size = vma->vm_end - vma->vm_start;
 740        /*
 741         * Align this down to a page boundary as expand_stack
 742         * will align it up.
 743         */
 744        rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 745#ifdef CONFIG_STACK_GROWSUP
 746        if (stack_size + stack_expand > rlim_stack)
 747                stack_base = vma->vm_start + rlim_stack;
 748        else
 749                stack_base = vma->vm_end + stack_expand;
 750#else
 751        if (stack_size + stack_expand > rlim_stack)
 752                stack_base = vma->vm_end - rlim_stack;
 753        else
 754                stack_base = vma->vm_start - stack_expand;
 755#endif
 756        current->mm->start_stack = bprm->p;
 757        ret = expand_stack(vma, stack_base);
 758        if (ret)
 759                ret = -EFAULT;
 760
 761out_unlock:
 762        up_write(&mm->mmap_sem);
 763        return ret;
 764}
 765EXPORT_SYMBOL(setup_arg_pages);
 766
 767#endif /* CONFIG_MMU */
 768
 769struct file *open_exec(const char *name)
 770{
 771        struct file *file;
 772        int err;
 773        static const struct open_flags open_exec_flags = {
 774                .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 775                .acc_mode = MAY_EXEC | MAY_OPEN,
 776                .intent = LOOKUP_OPEN
 777        };
 778
 779        file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
 780        if (IS_ERR(file))
 781                goto out;
 782
 783        err = -EACCES;
 784        if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 785                goto exit;
 786
 787        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 788                goto exit;
 789
 790        fsnotify_open(file);
 791
 792        err = deny_write_access(file);
 793        if (err)
 794                goto exit;
 795
 796out:
 797        return file;
 798
 799exit:
 800        fput(file);
 801        return ERR_PTR(err);
 802}
 803EXPORT_SYMBOL(open_exec);
 804
 805int kernel_read(struct file *file, loff_t offset,
 806                char *addr, unsigned long count)
 807{
 808        mm_segment_t old_fs;
 809        loff_t pos = offset;
 810        int result;
 811
 812        old_fs = get_fs();
 813        set_fs(get_ds());
 814        /* The cast to a user pointer is valid due to the set_fs() */
 815        result = vfs_read(file, (void __user *)addr, count, &pos);
 816        set_fs(old_fs);
 817        return result;
 818}
 819
 820EXPORT_SYMBOL(kernel_read);
 821
 822static int exec_mmap(struct mm_struct *mm)
 823{
 824        struct task_struct *tsk;
 825        struct mm_struct * old_mm, *active_mm;
 826
 827        /* Notify parent that we're no longer interested in the old VM */
 828        tsk = current;
 829        old_mm = current->mm;
 830        sync_mm_rss(tsk, old_mm);
 831        mm_release(tsk, old_mm);
 832
 833        if (old_mm) {
 834                /*
 835                 * Make sure that if there is a core dump in progress
 836                 * for the old mm, we get out and die instead of going
 837                 * through with the exec.  We must hold mmap_sem around
 838                 * checking core_state and changing tsk->mm.
 839                 */
 840                down_read(&old_mm->mmap_sem);
 841                if (unlikely(old_mm->core_state)) {
 842                        up_read(&old_mm->mmap_sem);
 843                        return -EINTR;
 844                }
 845        }
 846        task_lock(tsk);
 847        active_mm = tsk->active_mm;
 848        tsk->mm = mm;
 849        tsk->active_mm = mm;
 850        activate_mm(active_mm, mm);
 851        if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
 852                atomic_dec(&old_mm->oom_disable_count);
 853                atomic_inc(&tsk->mm->oom_disable_count);
 854        }
 855        task_unlock(tsk);
 856        arch_pick_mmap_layout(mm);
 857        if (old_mm) {
 858                up_read(&old_mm->mmap_sem);
 859                BUG_ON(active_mm != old_mm);
 860                mm_update_next_owner(old_mm);
 861                mmput(old_mm);
 862                return 0;
 863        }
 864        mmdrop(active_mm);
 865        return 0;
 866}
 867
 868/*
 869 * This function makes sure the current process has its own signal table,
 870 * so that flush_signal_handlers can later reset the handlers without
 871 * disturbing other processes.  (Other processes might share the signal
 872 * table via the CLONE_SIGHAND option to clone().)
 873 */
 874static int de_thread(struct task_struct *tsk)
 875{
 876        struct signal_struct *sig = tsk->signal;
 877        struct sighand_struct *oldsighand = tsk->sighand;
 878        spinlock_t *lock = &oldsighand->siglock;
 879
 880        if (thread_group_empty(tsk))
 881                goto no_thread_group;
 882
 883        /*
 884         * Kill all other threads in the thread group.
 885         */
 886        spin_lock_irq(lock);
 887        if (signal_group_exit(sig)) {
 888                /*
 889                 * Another group action in progress, just
 890                 * return so that the signal is processed.
 891                 */
 892                spin_unlock_irq(lock);
 893                return -EAGAIN;
 894        }
 895
 896        sig->group_exit_task = tsk;
 897        sig->notify_count = zap_other_threads(tsk);
 898        if (!thread_group_leader(tsk))
 899                sig->notify_count--;
 900
 901        while (sig->notify_count) {
 902                __set_current_state(TASK_UNINTERRUPTIBLE);
 903                spin_unlock_irq(lock);
 904                schedule();
 905                spin_lock_irq(lock);
 906        }
 907        spin_unlock_irq(lock);
 908
 909        /*
 910         * At this point all other threads have exited, all we have to
 911         * do is to wait for the thread group leader to become inactive,
 912         * and to assume its PID:
 913         */
 914        if (!thread_group_leader(tsk)) {
 915                struct task_struct *leader = tsk->group_leader;
 916
 917                sig->notify_count = -1; /* for exit_notify() */
 918                for (;;) {
 919                        write_lock_irq(&tasklist_lock);
 920                        if (likely(leader->exit_state))
 921                                break;
 922                        __set_current_state(TASK_UNINTERRUPTIBLE);
 923                        write_unlock_irq(&tasklist_lock);
 924                        schedule();
 925                }
 926
 927                /*
 928                 * The only record we have of the real-time age of a
 929                 * process, regardless of execs it's done, is start_time.
 930                 * All the past CPU time is accumulated in signal_struct
 931                 * from sister threads now dead.  But in this non-leader
 932                 * exec, nothing survives from the original leader thread,
 933                 * whose birth marks the true age of this process now.
 934                 * When we take on its identity by switching to its PID, we
 935                 * also take its birthdate (always earlier than our own).
 936                 */
 937                tsk->start_time = leader->start_time;
 938
 939                BUG_ON(!same_thread_group(leader, tsk));
 940                BUG_ON(has_group_leader_pid(tsk));
 941                /*
 942                 * An exec() starts a new thread group with the
 943                 * TGID of the previous thread group. Rehash the
 944                 * two threads with a switched PID, and release
 945                 * the former thread group leader:
 946                 */
 947
 948                /* Become a process group leader with the old leader's pid.
 949                 * The old leader becomes a thread of the this thread group.
 950                 * Note: The old leader also uses this pid until release_task
 951                 *       is called.  Odd but simple and correct.
 952                 */
 953                detach_pid(tsk, PIDTYPE_PID);
 954                tsk->pid = leader->pid;
 955                attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 956                transfer_pid(leader, tsk, PIDTYPE_PGID);
 957                transfer_pid(leader, tsk, PIDTYPE_SID);
 958
 959                list_replace_rcu(&leader->tasks, &tsk->tasks);
 960                list_replace_init(&leader->sibling, &tsk->sibling);
 961
 962                tsk->group_leader = tsk;
 963                leader->group_leader = tsk;
 964
 965                tsk->exit_signal = SIGCHLD;
 966
 967                BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 968                leader->exit_state = EXIT_DEAD;
 969                write_unlock_irq(&tasklist_lock);
 970
 971                release_task(leader);
 972        }
 973
 974        sig->group_exit_task = NULL;
 975        sig->notify_count = 0;
 976
 977no_thread_group:
 978        if (current->mm)
 979                setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
 980
 981        exit_itimers(sig);
 982        flush_itimer_signals();
 983
 984        if (atomic_read(&oldsighand->count) != 1) {
 985                struct sighand_struct *newsighand;
 986                /*
 987                 * This ->sighand is shared with the CLONE_SIGHAND
 988                 * but not CLONE_THREAD task, switch to the new one.
 989                 */
 990                newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 991                if (!newsighand)
 992                        return -ENOMEM;
 993
 994                atomic_set(&newsighand->count, 1);
 995                memcpy(newsighand->action, oldsighand->action,
 996                       sizeof(newsighand->action));
 997
 998                write_lock_irq(&tasklist_lock);
 999                spin_lock(&oldsighand->siglock);
1000                rcu_assign_pointer(tsk->sighand, newsighand);
1001                spin_unlock(&oldsighand->siglock);
1002                write_unlock_irq(&tasklist_lock);
1003
1004                __cleanup_sighand(oldsighand);
1005        }
1006
1007        BUG_ON(!thread_group_leader(tsk));
1008        return 0;
1009}
1010
1011/*
1012 * These functions flushes out all traces of the currently running executable
1013 * so that a new one can be started
1014 */
1015static void flush_old_files(struct files_struct * files)
1016{
1017        long j = -1;
1018        struct fdtable *fdt;
1019
1020        spin_lock(&files->file_lock);
1021        for (;;) {
1022                unsigned long set, i;
1023
1024                j++;
1025                i = j * __NFDBITS;
1026                fdt = files_fdtable(files);
1027                if (i >= fdt->max_fds)
1028                        break;
1029                set = fdt->close_on_exec->fds_bits[j];
1030                if (!set)
1031                        continue;
1032                fdt->close_on_exec->fds_bits[j] = 0;
1033                spin_unlock(&files->file_lock);
1034                for ( ; set ; i++,set >>= 1) {
1035                        if (set & 1) {
1036                                sys_close(i);
1037                        }
1038                }
1039                spin_lock(&files->file_lock);
1040
1041        }
1042        spin_unlock(&files->file_lock);
1043}
1044
1045char *get_task_comm(char *buf, struct task_struct *tsk)
1046{
1047        /* buf must be at least sizeof(tsk->comm) in size */
1048        task_lock(tsk);
1049        strncpy(buf, tsk->comm, sizeof(tsk->comm));
1050        task_unlock(tsk);
1051        return buf;
1052}
1053EXPORT_SYMBOL_GPL(get_task_comm);
1054
1055void set_task_comm(struct task_struct *tsk, char *buf)
1056{
1057        task_lock(tsk);
1058
1059        /*
1060         * Threads may access current->comm without holding
1061         * the task lock, so write the string carefully.
1062         * Readers without a lock may see incomplete new
1063         * names but are safe from non-terminating string reads.
1064         */
1065        memset(tsk->comm, 0, TASK_COMM_LEN);
1066        wmb();
1067        strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1068        task_unlock(tsk);
1069        perf_event_comm(tsk);
1070}
1071
1072int flush_old_exec(struct linux_binprm * bprm)
1073{
1074        int retval;
1075
1076        /*
1077         * Make sure we have a private signal table and that
1078         * we are unassociated from the previous thread group.
1079         */
1080        retval = de_thread(current);
1081        if (retval)
1082                goto out;
1083
1084        set_mm_exe_file(bprm->mm, bprm->file);
1085
1086        /*
1087         * Release all of the old mmap stuff
1088         */
1089        acct_arg_size(bprm, 0);
1090        retval = exec_mmap(bprm->mm);
1091        if (retval)
1092                goto out;
1093
1094        bprm->mm = NULL;                /* We're using it now */
1095
1096        set_fs(USER_DS);
1097        current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1098        flush_thread();
1099        current->personality &= ~bprm->per_clear;
1100
1101        return 0;
1102
1103out:
1104        return retval;
1105}
1106EXPORT_SYMBOL(flush_old_exec);
1107
1108void setup_new_exec(struct linux_binprm * bprm)
1109{
1110        int i, ch;
1111        const char *name;
1112        char tcomm[sizeof(current->comm)];
1113
1114        arch_pick_mmap_layout(current->mm);
1115
1116        /* This is the point of no return */
1117        current->sas_ss_sp = current->sas_ss_size = 0;
1118
1119        if (current_euid() == current_uid() && current_egid() == current_gid())
1120                set_dumpable(current->mm, 1);
1121        else
1122                set_dumpable(current->mm, suid_dumpable);
1123
1124        name = bprm->filename;
1125
1126        /* Copies the binary name from after last slash */
1127        for (i=0; (ch = *(name++)) != '\0';) {
1128                if (ch == '/')
1129                        i = 0; /* overwrite what we wrote */
1130                else
1131                        if (i < (sizeof(tcomm) - 1))
1132                                tcomm[i++] = ch;
1133        }
1134        tcomm[i] = '\0';
1135        set_task_comm(current, tcomm);
1136
1137        /* Set the new mm task size. We have to do that late because it may
1138         * depend on TIF_32BIT which is only updated in flush_thread() on
1139         * some architectures like powerpc
1140         */
1141        current->mm->task_size = TASK_SIZE;
1142
1143        /* install the new credentials */
1144        if (bprm->cred->uid != current_euid() ||
1145            bprm->cred->gid != current_egid()) {
1146                current->pdeath_signal = 0;
1147        } else if (file_permission(bprm->file, MAY_READ) ||
1148                   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1149                set_dumpable(current->mm, suid_dumpable);
1150        }
1151
1152        /*
1153         * Flush performance counters when crossing a
1154         * security domain:
1155         */
1156        if (!get_dumpable(current->mm))
1157                perf_event_exit_task(current);
1158
1159        /* An exec changes our domain. We are no longer part of the thread
1160           group */
1161
1162        current->self_exec_id++;
1163                        
1164        flush_signal_handlers(current, 0);
1165        flush_old_files(current->files);
1166}
1167EXPORT_SYMBOL(setup_new_exec);
1168
1169/*
1170 * Prepare credentials and lock ->cred_guard_mutex.
1171 * install_exec_creds() commits the new creds and drops the lock.
1172 * Or, if exec fails before, free_bprm() should release ->cred and
1173 * and unlock.
1174 */
1175int prepare_bprm_creds(struct linux_binprm *bprm)
1176{
1177        if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1178                return -ERESTARTNOINTR;
1179
1180        bprm->cred = prepare_exec_creds();
1181        if (likely(bprm->cred))
1182                return 0;
1183
1184        mutex_unlock(&current->signal->cred_guard_mutex);
1185        return -ENOMEM;
1186}
1187
1188void free_bprm(struct linux_binprm *bprm)
1189{
1190        free_arg_pages(bprm);
1191        if (bprm->cred) {
1192                mutex_unlock(&current->signal->cred_guard_mutex);
1193                abort_creds(bprm->cred);
1194        }
1195        kfree(bprm);
1196}
1197
1198/*
1199 * install the new credentials for this executable
1200 */
1201void install_exec_creds(struct linux_binprm *bprm)
1202{
1203        security_bprm_committing_creds(bprm);
1204
1205        commit_creds(bprm->cred);
1206        bprm->cred = NULL;
1207        /*
1208         * cred_guard_mutex must be held at least to this point to prevent
1209         * ptrace_attach() from altering our determination of the task's
1210         * credentials; any time after this it may be unlocked.
1211         */
1212        security_bprm_committed_creds(bprm);
1213        mutex_unlock(&current->signal->cred_guard_mutex);
1214}
1215EXPORT_SYMBOL(install_exec_creds);
1216
1217/*
1218 * determine how safe it is to execute the proposed program
1219 * - the caller must hold ->cred_guard_mutex to protect against
1220 *   PTRACE_ATTACH
1221 */
1222int check_unsafe_exec(struct linux_binprm *bprm)
1223{
1224        struct task_struct *p = current, *t;
1225        unsigned n_fs;
1226        int res = 0;
1227
1228        bprm->unsafe = tracehook_unsafe_exec(p);
1229
1230        n_fs = 1;
1231        spin_lock(&p->fs->lock);
1232        rcu_read_lock();
1233        for (t = next_thread(p); t != p; t = next_thread(t)) {
1234                if (t->fs == p->fs)
1235                        n_fs++;
1236        }
1237        rcu_read_unlock();
1238
1239        if (p->fs->users > n_fs) {
1240                bprm->unsafe |= LSM_UNSAFE_SHARE;
1241        } else {
1242                res = -EAGAIN;
1243                if (!p->fs->in_exec) {
1244                        p->fs->in_exec = 1;
1245                        res = 1;
1246                }
1247        }
1248        spin_unlock(&p->fs->lock);
1249
1250        return res;
1251}
1252
1253/* 
1254 * Fill the binprm structure from the inode. 
1255 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1256 *
1257 * This may be called multiple times for binary chains (scripts for example).
1258 */
1259int prepare_binprm(struct linux_binprm *bprm)
1260{
1261        umode_t mode;
1262        struct inode * inode = bprm->file->f_path.dentry->d_inode;
1263        int retval;
1264
1265        mode = inode->i_mode;
1266        if (bprm->file->f_op == NULL)
1267                return -EACCES;
1268
1269        /* clear any previous set[ug]id data from a previous binary */
1270        bprm->cred->euid = current_euid();
1271        bprm->cred->egid = current_egid();
1272
1273        if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1274                /* Set-uid? */
1275                if (mode & S_ISUID) {
1276                        bprm->per_clear |= PER_CLEAR_ON_SETID;
1277                        bprm->cred->euid = inode->i_uid;
1278                }
1279
1280                /* Set-gid? */
1281                /*
1282                 * If setgid is set but no group execute bit then this
1283                 * is a candidate for mandatory locking, not a setgid
1284                 * executable.
1285                 */
1286                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1287                        bprm->per_clear |= PER_CLEAR_ON_SETID;
1288                        bprm->cred->egid = inode->i_gid;
1289                }
1290        }
1291
1292        /* fill in binprm security blob */
1293        retval = security_bprm_set_creds(bprm);
1294        if (retval)
1295                return retval;
1296        bprm->cred_prepared = 1;
1297
1298        memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1299        return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1300}
1301
1302EXPORT_SYMBOL(prepare_binprm);
1303
1304/*
1305 * Arguments are '\0' separated strings found at the location bprm->p
1306 * points to; chop off the first by relocating brpm->p to right after
1307 * the first '\0' encountered.
1308 */
1309int remove_arg_zero(struct linux_binprm *bprm)
1310{
1311        int ret = 0;
1312        unsigned long offset;
1313        char *kaddr;
1314        struct page *page;
1315
1316        if (!bprm->argc)
1317                return 0;
1318
1319        do {
1320                offset = bprm->p & ~PAGE_MASK;
1321                page = get_arg_page(bprm, bprm->p, 0);
1322                if (!page) {
1323                        ret = -EFAULT;
1324                        goto out;
1325                }
1326                kaddr = kmap_atomic(page, KM_USER0);
1327
1328                for (; offset < PAGE_SIZE && kaddr[offset];
1329                                offset++, bprm->p++)
1330                        ;
1331
1332                kunmap_atomic(kaddr, KM_USER0);
1333                put_arg_page(page);
1334
1335                if (offset == PAGE_SIZE)
1336                        free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1337        } while (offset == PAGE_SIZE);
1338
1339        bprm->p++;
1340        bprm->argc--;
1341        ret = 0;
1342
1343out:
1344        return ret;
1345}
1346EXPORT_SYMBOL(remove_arg_zero);
1347
1348/*
1349 * cycle the list of binary formats handler, until one recognizes the image
1350 */
1351int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1352{
1353        unsigned int depth = bprm->recursion_depth;
1354        int try,retval;
1355        struct linux_binfmt *fmt;
1356
1357        retval = security_bprm_check(bprm);
1358        if (retval)
1359                return retval;
1360
1361        retval = audit_bprm(bprm);
1362        if (retval)
1363                return retval;
1364
1365        retval = -ENOENT;
1366        for (try=0; try<2; try++) {
1367                read_lock(&binfmt_lock);
1368                list_for_each_entry(fmt, &formats, lh) {
1369                        int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1370                        if (!fn)
1371                                continue;
1372                        if (!try_module_get(fmt->module))
1373                                continue;
1374                        read_unlock(&binfmt_lock);
1375                        retval = fn(bprm, regs);
1376                        /*
1377                         * Restore the depth counter to its starting value
1378                         * in this call, so we don't have to rely on every
1379                         * load_binary function to restore it on return.
1380                         */
1381                        bprm->recursion_depth = depth;
1382                        if (retval >= 0) {
1383                                if (depth == 0)
1384                                        tracehook_report_exec(fmt, bprm, regs);
1385                                put_binfmt(fmt);
1386                                allow_write_access(bprm->file);
1387                                if (bprm->file)
1388                                        fput(bprm->file);
1389                                bprm->file = NULL;
1390                                current->did_exec = 1;
1391                                proc_exec_connector(current);
1392                                return retval;
1393                        }
1394                        read_lock(&binfmt_lock);
1395                        put_binfmt(fmt);
1396                        if (retval != -ENOEXEC || bprm->mm == NULL)
1397                                break;
1398                        if (!bprm->file) {
1399                                read_unlock(&binfmt_lock);
1400                                return retval;
1401                        }
1402                }
1403                read_unlock(&binfmt_lock);
1404                if (retval != -ENOEXEC || bprm->mm == NULL) {
1405                        break;
1406#ifdef CONFIG_MODULES
1407                } else {
1408#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1409                        if (printable(bprm->buf[0]) &&
1410                            printable(bprm->buf[1]) &&
1411                            printable(bprm->buf[2]) &&
1412                            printable(bprm->buf[3]))
1413                                break; /* -ENOEXEC */
1414                        request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1415#endif
1416                }
1417        }
1418        return retval;
1419}
1420
1421EXPORT_SYMBOL(search_binary_handler);
1422
1423/*
1424 * sys_execve() executes a new program.
1425 */
1426static int do_execve_common(const char *filename,
1427                                struct user_arg_ptr argv,
1428                                struct user_arg_ptr envp,
1429                                struct pt_regs *regs)
1430{
1431        struct linux_binprm *bprm;
1432        struct file *file;
1433        struct files_struct *displaced;
1434        bool clear_in_exec;
1435        int retval;
1436
1437        retval = unshare_files(&displaced);
1438        if (retval)
1439                goto out_ret;
1440
1441        retval = -ENOMEM;
1442        bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1443        if (!bprm)
1444                goto out_files;
1445
1446        retval = prepare_bprm_creds(bprm);
1447        if (retval)
1448                goto out_free;
1449
1450        retval = check_unsafe_exec(bprm);
1451        if (retval < 0)
1452                goto out_free;
1453        clear_in_exec = retval;
1454        current->in_execve = 1;
1455
1456        file = open_exec(filename);
1457        retval = PTR_ERR(file);
1458        if (IS_ERR(file))
1459                goto out_unmark;
1460
1461        sched_exec();
1462
1463        bprm->file = file;
1464        bprm->filename = filename;
1465        bprm->interp = filename;
1466
1467        retval = bprm_mm_init(bprm);
1468        if (retval)
1469                goto out_file;
1470
1471        bprm->argc = count(argv, MAX_ARG_STRINGS);
1472        if ((retval = bprm->argc) < 0)
1473                goto out;
1474
1475        bprm->envc = count(envp, MAX_ARG_STRINGS);
1476        if ((retval = bprm->envc) < 0)
1477                goto out;
1478
1479        retval = prepare_binprm(bprm);
1480        if (retval < 0)
1481                goto out;
1482
1483        retval = copy_strings_kernel(1, &bprm->filename, bprm);
1484        if (retval < 0)
1485                goto out;
1486
1487        bprm->exec = bprm->p;
1488        retval = copy_strings(bprm->envc, envp, bprm);
1489        if (retval < 0)
1490                goto out;
1491
1492        retval = copy_strings(bprm->argc, argv, bprm);
1493        if (retval < 0)
1494                goto out;
1495
1496        retval = search_binary_handler(bprm,regs);
1497        if (retval < 0)
1498                goto out;
1499
1500        /* execve succeeded */
1501        current->fs->in_exec = 0;
1502        current->in_execve = 0;
1503        acct_update_integrals(current);
1504        free_bprm(bprm);
1505        if (displaced)
1506                put_files_struct(displaced);
1507        return retval;
1508
1509out:
1510        if (bprm->mm) {
1511                acct_arg_size(bprm, 0);
1512                mmput(bprm->mm);
1513        }
1514
1515out_file:
1516        if (bprm->file) {
1517                allow_write_access(bprm->file);
1518                fput(bprm->file);
1519        }
1520
1521out_unmark:
1522        if (clear_in_exec)
1523                current->fs->in_exec = 0;
1524        current->in_execve = 0;
1525
1526out_free:
1527        free_bprm(bprm);
1528
1529out_files:
1530        if (displaced)
1531                reset_files_struct(displaced);
1532out_ret:
1533        return retval;
1534}
1535
1536int do_execve(const char *filename,
1537        const char __user *const __user *__argv,
1538        const char __user *const __user *__envp,
1539        struct pt_regs *regs)
1540{
1541        struct user_arg_ptr argv = { .ptr.native = __argv };
1542        struct user_arg_ptr envp = { .ptr.native = __envp };
1543        return do_execve_common(filename, argv, envp, regs);
1544}
1545
1546#ifdef CONFIG_COMPAT
1547int compat_do_execve(char *filename,
1548        compat_uptr_t __user *__argv,
1549        compat_uptr_t __user *__envp,
1550        struct pt_regs *regs)
1551{
1552        struct user_arg_ptr argv = {
1553                .is_compat = true,
1554                .ptr.compat = __argv,
1555        };
1556        struct user_arg_ptr envp = {
1557                .is_compat = true,
1558                .ptr.compat = __envp,
1559        };
1560        return do_execve_common(filename, argv, envp, regs);
1561}
1562#endif
1563
1564void set_binfmt(struct linux_binfmt *new)
1565{
1566        struct mm_struct *mm = current->mm;
1567
1568        if (mm->binfmt)
1569                module_put(mm->binfmt->module);
1570
1571        mm->binfmt = new;
1572        if (new)
1573                __module_get(new->module);
1574}
1575
1576EXPORT_SYMBOL(set_binfmt);
1577
1578static int expand_corename(struct core_name *cn)
1579{
1580        char *old_corename = cn->corename;
1581
1582        cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1583        cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1584
1585        if (!cn->corename) {
1586                kfree(old_corename);
1587                return -ENOMEM;
1588        }
1589
1590        return 0;
1591}
1592
1593static int cn_printf(struct core_name *cn, const char *fmt, ...)
1594{
1595        char *cur;
1596        int need;
1597        int ret;
1598        va_list arg;
1599
1600        va_start(arg, fmt);
1601        need = vsnprintf(NULL, 0, fmt, arg);
1602        va_end(arg);
1603
1604        if (likely(need < cn->size - cn->used - 1))
1605                goto out_printf;
1606
1607        ret = expand_corename(cn);
1608        if (ret)
1609                goto expand_fail;
1610
1611out_printf:
1612        cur = cn->corename + cn->used;
1613        va_start(arg, fmt);
1614        vsnprintf(cur, need + 1, fmt, arg);
1615        va_end(arg);
1616        cn->used += need;
1617        return 0;
1618
1619expand_fail:
1620        return ret;
1621}
1622
1623static int cn_print_exe_file(struct core_name *cn)
1624{
1625        struct file *exe_file;
1626        char *pathbuf, *path, *p;
1627        int ret;
1628
1629        exe_file = get_mm_exe_file(current->mm);
1630        if (!exe_file)
1631                return cn_printf(cn, "(unknown)");
1632
1633        pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1634        if (!pathbuf) {
1635                ret = -ENOMEM;
1636                goto put_exe_file;
1637        }
1638
1639        path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1640        if (IS_ERR(path)) {
1641                ret = PTR_ERR(path);
1642                goto free_buf;
1643        }
1644
1645        for (p = path; *p; p++)
1646                if (*p == '/')
1647                        *p = '!';
1648
1649        ret = cn_printf(cn, "%s", path);
1650
1651free_buf:
1652        kfree(pathbuf);
1653put_exe_file:
1654        fput(exe_file);
1655        return ret;
1656}
1657
1658/* format_corename will inspect the pattern parameter, and output a
1659 * name into corename, which must have space for at least
1660 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1661 */
1662static int format_corename(struct core_name *cn, long signr)
1663{
1664        const struct cred *cred = current_cred();
1665        const char *pat_ptr = core_pattern;
1666        int ispipe = (*pat_ptr == '|');
1667        int pid_in_pattern = 0;
1668        int err = 0;
1669
1670        cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1671        cn->corename = kmalloc(cn->size, GFP_KERNEL);
1672        cn->used = 0;
1673
1674        if (!cn->corename)
1675                return -ENOMEM;
1676
1677        /* Repeat as long as we have more pattern to process and more output
1678           space */
1679        while (*pat_ptr) {
1680                if (*pat_ptr != '%') {
1681                        if (*pat_ptr == 0)
1682                                goto out;
1683                        err = cn_printf(cn, "%c", *pat_ptr++);
1684                } else {
1685                        switch (*++pat_ptr) {
1686                        /* single % at the end, drop that */
1687                        case 0:
1688                                goto out;
1689                        /* Double percent, output one percent */
1690                        case '%':
1691                                err = cn_printf(cn, "%c", '%');
1692                                break;
1693                        /* pid */
1694                        case 'p':
1695                                pid_in_pattern = 1;
1696                                err = cn_printf(cn, "%d",
1697                                              task_tgid_vnr(current));
1698                                break;
1699                        /* uid */
1700                        case 'u':
1701                                err = cn_printf(cn, "%d", cred->uid);
1702                                break;
1703                        /* gid */
1704                        case 'g':
1705                                err = cn_printf(cn, "%d", cred->gid);
1706                                break;
1707                        /* signal that caused the coredump */
1708                        case 's':
1709                                err = cn_printf(cn, "%ld", signr);
1710                                break;
1711                        /* UNIX time of coredump */
1712                        case 't': {
1713                                struct timeval tv;
1714                                do_gettimeofday(&tv);
1715                                err = cn_printf(cn, "%lu", tv.tv_sec);
1716                                break;
1717                        }
1718                        /* hostname */
1719                        case 'h':
1720                                down_read(&uts_sem);
1721                                err = cn_printf(cn, "%s",
1722                                              utsname()->nodename);
1723                                up_read(&uts_sem);
1724                                break;
1725                        /* executable */
1726                        case 'e':
1727                                err = cn_printf(cn, "%s", current->comm);
1728                                break;
1729                        case 'E':
1730                                err = cn_print_exe_file(cn);
1731                                break;
1732                        /* core limit size */
1733                        case 'c':
1734                                err = cn_printf(cn, "%lu",
1735                                              rlimit(RLIMIT_CORE));
1736                                break;
1737                        default:
1738                                break;
1739                        }
1740                        ++pat_ptr;
1741                }
1742
1743                if (err)
1744                        return err;
1745        }
1746
1747        /* Backward compatibility with core_uses_pid:
1748         *
1749         * If core_pattern does not include a %p (as is the default)
1750         * and core_uses_pid is set, then .%pid will be appended to
1751         * the filename. Do not do this for piped commands. */
1752        if (!ispipe && !pid_in_pattern && core_uses_pid) {
1753                err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1754                if (err)
1755                        return err;
1756        }
1757out:
1758        return ispipe;
1759}
1760
1761static int zap_process(struct task_struct *start, int exit_code)
1762{
1763        struct task_struct *t;
1764        int nr = 0;
1765
1766        start->signal->flags = SIGNAL_GROUP_EXIT;
1767        start->signal->group_exit_code = exit_code;
1768        start->signal->group_stop_count = 0;
1769
1770        t = start;
1771        do {
1772                task_clear_group_stop_pending(t);
1773                if (t != current && t->mm) {
1774                        sigaddset(&t->pending.signal, SIGKILL);
1775                        signal_wake_up(t, 1);
1776                        nr++;
1777                }
1778        } while_each_thread(start, t);
1779
1780        return nr;
1781}
1782
1783static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1784                                struct core_state *core_state, int exit_code)
1785{
1786        struct task_struct *g, *p;
1787        unsigned long flags;
1788        int nr = -EAGAIN;
1789
1790        spin_lock_irq(&tsk->sighand->siglock);
1791        if (!signal_group_exit(tsk->signal)) {
1792                mm->core_state = core_state;
1793                nr = zap_process(tsk, exit_code);
1794        }
1795        spin_unlock_irq(&tsk->sighand->siglock);
1796        if (unlikely(nr < 0))
1797                return nr;
1798
1799        if (atomic_read(&mm->mm_users) == nr + 1)
1800                goto done;
1801        /*
1802         * We should find and kill all tasks which use this mm, and we should
1803         * count them correctly into ->nr_threads. We don't take tasklist
1804         * lock, but this is safe wrt:
1805         *
1806         * fork:
1807         *      None of sub-threads can fork after zap_process(leader). All
1808         *      processes which were created before this point should be
1809         *      visible to zap_threads() because copy_process() adds the new
1810         *      process to the tail of init_task.tasks list, and lock/unlock
1811         *      of ->siglock provides a memory barrier.
1812         *
1813         * do_exit:
1814         *      The caller holds mm->mmap_sem. This means that the task which
1815         *      uses this mm can't pass exit_mm(), so it can't exit or clear
1816         *      its ->mm.
1817         *
1818         * de_thread:
1819         *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1820         *      we must see either old or new leader, this does not matter.
1821         *      However, it can change p->sighand, so lock_task_sighand(p)
1822         *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1823         *      it can't fail.
1824         *
1825         *      Note also that "g" can be the old leader with ->mm == NULL
1826         *      and already unhashed and thus removed from ->thread_group.
1827         *      This is OK, __unhash_process()->list_del_rcu() does not
1828         *      clear the ->next pointer, we will find the new leader via
1829         *      next_thread().
1830         */
1831        rcu_read_lock();
1832        for_each_process(g) {
1833                if (g == tsk->group_leader)
1834                        continue;
1835                if (g->flags & PF_KTHREAD)
1836                        continue;
1837                p = g;
1838                do {
1839                        if (p->mm) {
1840                                if (unlikely(p->mm == mm)) {
1841                                        lock_task_sighand(p, &flags);
1842                                        nr += zap_process(p, exit_code);
1843                                        unlock_task_sighand(p, &flags);
1844                                }
1845                                break;
1846                        }
1847                } while_each_thread(g, p);
1848        }
1849        rcu_read_unlock();
1850done:
1851        atomic_set(&core_state->nr_threads, nr);
1852        return nr;
1853}
1854
1855static int coredump_wait(int exit_code, struct core_state *core_state)
1856{
1857        struct task_struct *tsk = current;
1858        struct mm_struct *mm = tsk->mm;
1859        struct completion *vfork_done;
1860        int core_waiters = -EBUSY;
1861
1862        init_completion(&core_state->startup);
1863        core_state->dumper.task = tsk;
1864        core_state->dumper.next = NULL;
1865
1866        down_write(&mm->mmap_sem);
1867        if (!mm->core_state)
1868                core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1869        up_write(&mm->mmap_sem);
1870
1871        if (unlikely(core_waiters < 0))
1872                goto fail;
1873
1874        /*
1875         * Make sure nobody is waiting for us to release the VM,
1876         * otherwise we can deadlock when we wait on each other
1877         */
1878        vfork_done = tsk->vfork_done;
1879        if (vfork_done) {
1880                tsk->vfork_done = NULL;
1881                complete(vfork_done);
1882        }
1883
1884        if (core_waiters)
1885                wait_for_completion(&core_state->startup);
1886fail:
1887        return core_waiters;
1888}
1889
1890static void coredump_finish(struct mm_struct *mm)
1891{
1892        struct core_thread *curr, *next;
1893        struct task_struct *task;
1894
1895        next = mm->core_state->dumper.next;
1896        while ((curr = next) != NULL) {
1897                next = curr->next;
1898                task = curr->task;
1899                /*
1900                 * see exit_mm(), curr->task must not see
1901                 * ->task == NULL before we read ->next.
1902                 */
1903                smp_mb();
1904                curr->task = NULL;
1905                wake_up_process(task);
1906        }
1907
1908        mm->core_state = NULL;
1909}
1910
1911/*
1912 * set_dumpable converts traditional three-value dumpable to two flags and
1913 * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1914 * these bits are not changed atomically.  So get_dumpable can observe the
1915 * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1916 * return either old dumpable or new one by paying attention to the order of
1917 * modifying the bits.
1918 *
1919 * dumpable |   mm->flags (binary)
1920 * old  new | initial interim  final
1921 * ---------+-----------------------
1922 *  0    1  |   00      01      01
1923 *  0    2  |   00      10(*)   11
1924 *  1    0  |   01      00      00
1925 *  1    2  |   01      11      11
1926 *  2    0  |   11      10(*)   00
1927 *  2    1  |   11      11      01
1928 *
1929 * (*) get_dumpable regards interim value of 10 as 11.
1930 */
1931void set_dumpable(struct mm_struct *mm, int value)
1932{
1933        switch (value) {
1934        case 0:
1935                clear_bit(MMF_DUMPABLE, &mm->flags);
1936                smp_wmb();
1937                clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1938                break;
1939        case 1:
1940                set_bit(MMF_DUMPABLE, &mm->flags);
1941                smp_wmb();
1942                clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1943                break;
1944        case 2:
1945                set_bit(MMF_DUMP_SECURELY, &mm->flags);
1946                smp_wmb();
1947                set_bit(MMF_DUMPABLE, &mm->flags);
1948                break;
1949        }
1950}
1951
1952static int __get_dumpable(unsigned long mm_flags)
1953{
1954        int ret;
1955
1956        ret = mm_flags & MMF_DUMPABLE_MASK;
1957        return (ret >= 2) ? 2 : ret;
1958}
1959
1960int get_dumpable(struct mm_struct *mm)
1961{
1962        return __get_dumpable(mm->flags);
1963}
1964
1965static void wait_for_dump_helpers(struct file *file)
1966{
1967        struct pipe_inode_info *pipe;
1968
1969        pipe = file->f_path.dentry->d_inode->i_pipe;
1970
1971        pipe_lock(pipe);
1972        pipe->readers++;
1973        pipe->writers--;
1974
1975        while ((pipe->readers > 1) && (!signal_pending(current))) {
1976                wake_up_interruptible_sync(&pipe->wait);
1977                kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1978                pipe_wait(pipe);
1979        }
1980
1981        pipe->readers--;
1982        pipe->writers++;
1983        pipe_unlock(pipe);
1984
1985}
1986
1987
1988/*
1989 * umh_pipe_setup
1990 * helper function to customize the process used
1991 * to collect the core in userspace.  Specifically
1992 * it sets up a pipe and installs it as fd 0 (stdin)
1993 * for the process.  Returns 0 on success, or
1994 * PTR_ERR on failure.
1995 * Note that it also sets the core limit to 1.  This
1996 * is a special value that we use to trap recursive
1997 * core dumps
1998 */
1999static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2000{
2001        struct file *rp, *wp;
2002        struct fdtable *fdt;
2003        struct coredump_params *cp = (struct coredump_params *)info->data;
2004        struct files_struct *cf = current->files;
2005
2006        wp = create_write_pipe(0);
2007        if (IS_ERR(wp))
2008                return PTR_ERR(wp);
2009
2010        rp = create_read_pipe(wp, 0);
2011        if (IS_ERR(rp)) {
2012                free_write_pipe(wp);
2013                return PTR_ERR(rp);
2014        }
2015
2016        cp->file = wp;
2017
2018        sys_close(0);
2019        fd_install(0, rp);
2020        spin_lock(&cf->file_lock);
2021        fdt = files_fdtable(cf);
2022        FD_SET(0, fdt->open_fds);
2023        FD_CLR(0, fdt->close_on_exec);
2024        spin_unlock(&cf->file_lock);
2025
2026        /* and disallow core files too */
2027        current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2028
2029        return 0;
2030}
2031
2032void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2033{
2034        struct core_state core_state;
2035        struct core_name cn;
2036        struct mm_struct *mm = current->mm;
2037        struct linux_binfmt * binfmt;
2038        const struct cred *old_cred;
2039        struct cred *cred;
2040        int retval = 0;
2041        int flag = 0;
2042        int ispipe;
2043        static atomic_t core_dump_count = ATOMIC_INIT(0);
2044        struct coredump_params cprm = {
2045                .signr = signr,
2046                .regs = regs,
2047                .limit = rlimit(RLIMIT_CORE),
2048                /*
2049                 * We must use the same mm->flags while dumping core to avoid
2050                 * inconsistency of bit flags, since this flag is not protected
2051                 * by any locks.
2052                 */
2053                .mm_flags = mm->flags,
2054        };
2055
2056        audit_core_dumps(signr);
2057
2058        binfmt = mm->binfmt;
2059        if (!binfmt || !binfmt->core_dump)
2060                goto fail;
2061        if (!__get_dumpable(cprm.mm_flags))
2062                goto fail;
2063
2064        cred = prepare_creds();
2065        if (!cred)
2066                goto fail;
2067        /*
2068         *      We cannot trust fsuid as being the "true" uid of the
2069         *      process nor do we know its entire history. We only know it
2070         *      was tainted so we dump it as root in mode 2.
2071         */
2072        if (__get_dumpable(cprm.mm_flags) == 2) {
2073                /* Setuid core dump mode */
2074                flag = O_EXCL;          /* Stop rewrite attacks */
2075                cred->fsuid = 0;        /* Dump root private */
2076        }
2077
2078        retval = coredump_wait(exit_code, &core_state);
2079        if (retval < 0)
2080                goto fail_creds;
2081
2082        old_cred = override_creds(cred);
2083
2084        /*
2085         * Clear any false indication of pending signals that might
2086         * be seen by the filesystem code called to write the core file.
2087         */
2088        clear_thread_flag(TIF_SIGPENDING);
2089
2090        ispipe = format_corename(&cn, signr);
2091
2092        if (ispipe == -ENOMEM) {
2093                printk(KERN_WARNING "format_corename failed\n");
2094                printk(KERN_WARNING "Aborting core\n");
2095                goto fail_corename;
2096        }
2097
2098        if (ispipe) {
2099                int dump_count;
2100                char **helper_argv;
2101
2102                if (cprm.limit == 1) {
2103                        /*
2104                         * Normally core limits are irrelevant to pipes, since
2105                         * we're not writing to the file system, but we use
2106                         * cprm.limit of 1 here as a speacial value. Any
2107                         * non-1 limit gets set to RLIM_INFINITY below, but
2108                         * a limit of 0 skips the dump.  This is a consistent
2109                         * way to catch recursive crashes.  We can still crash
2110                         * if the core_pattern binary sets RLIM_CORE =  !1
2111                         * but it runs as root, and can do lots of stupid things
2112                         * Note that we use task_tgid_vnr here to grab the pid
2113                         * of the process group leader.  That way we get the
2114                         * right pid if a thread in a multi-threaded
2115                         * core_pattern process dies.
2116                         */
2117                        printk(KERN_WARNING
2118                                "Process %d(%s) has RLIMIT_CORE set to 1\n",
2119                                task_tgid_vnr(current), current->comm);
2120                        printk(KERN_WARNING "Aborting core\n");
2121                        goto fail_unlock;
2122                }
2123                cprm.limit = RLIM_INFINITY;
2124
2125                dump_count = atomic_inc_return(&core_dump_count);
2126                if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2127                        printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2128                               task_tgid_vnr(current), current->comm);
2129                        printk(KERN_WARNING "Skipping core dump\n");
2130                        goto fail_dropcount;
2131                }
2132
2133                helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2134                if (!helper_argv) {
2135                        printk(KERN_WARNING "%s failed to allocate memory\n",
2136                               __func__);
2137                        goto fail_dropcount;
2138                }
2139
2140                retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2141                                        NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2142                                        NULL, &cprm);
2143                argv_free(helper_argv);
2144                if (retval) {
2145                        printk(KERN_INFO "Core dump to %s pipe failed\n",
2146                               cn.corename);
2147                        goto close_fail;
2148                }
2149        } else {
2150                struct inode *inode;
2151
2152                if (cprm.limit < binfmt->min_coredump)
2153                        goto fail_unlock;
2154
2155                cprm.file = filp_open(cn.corename,
2156                                 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2157                                 0600);
2158                if (IS_ERR(cprm.file))
2159                        goto fail_unlock;
2160
2161                inode = cprm.file->f_path.dentry->d_inode;
2162                if (inode->i_nlink > 1)
2163                        goto close_fail;
2164                if (d_unhashed(cprm.file->f_path.dentry))
2165                        goto close_fail;
2166                /*
2167                 * AK: actually i see no reason to not allow this for named
2168                 * pipes etc, but keep the previous behaviour for now.
2169                 */
2170                if (!S_ISREG(inode->i_mode))
2171                        goto close_fail;
2172                /*
2173                 * Dont allow local users get cute and trick others to coredump
2174                 * into their pre-created files.
2175                 */
2176                if (inode->i_uid != current_fsuid())
2177                        goto close_fail;
2178                if (!cprm.file->f_op || !cprm.file->f_op->write)
2179                        goto close_fail;
2180                if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2181                        goto close_fail;
2182        }
2183
2184        retval = binfmt->core_dump(&cprm);
2185        if (retval)
2186                current->signal->group_exit_code |= 0x80;
2187
2188        if (ispipe && core_pipe_limit)
2189                wait_for_dump_helpers(cprm.file);
2190close_fail:
2191        if (cprm.file)
2192                filp_close(cprm.file, NULL);
2193fail_dropcount:
2194        if (ispipe)
2195                atomic_dec(&core_dump_count);
2196fail_unlock:
2197        kfree(cn.corename);
2198fail_corename:
2199        coredump_finish(mm);
2200        revert_creds(old_cred);
2201fail_creds:
2202        put_cred(cred);
2203fail:
2204        return;
2205}
2206
2207/*
2208 * Core dumping helper functions.  These are the only things you should
2209 * do on a core-file: use only these functions to write out all the
2210 * necessary info.
2211 */
2212int dump_write(struct file *file, const void *addr, int nr)
2213{
2214        return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2215}
2216EXPORT_SYMBOL(dump_write);
2217
2218int dump_seek(struct file *file, loff_t off)
2219{
2220        int ret = 1;
2221
2222        if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2223                if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2224                        return 0;
2225        } else {
2226                char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2227
2228                if (!buf)
2229                        return 0;
2230                while (off > 0) {
2231                        unsigned long n = off;
2232
2233                        if (n > PAGE_SIZE)
2234                                n = PAGE_SIZE;
2235                        if (!dump_write(file, buf, n)) {
2236                                ret = 0;
2237                                break;
2238                        }
2239                        off -= n;
2240                }
2241                free_page((unsigned long)buf);
2242        }
2243        return ret;
2244}
2245EXPORT_SYMBOL(dump_seek);
2246
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