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        add_mm_counter(mm, MM_ANONPAGES, diff);
 185}
 186
 187static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 188                int write)
 189{
 190        struct page *page;
 191        int ret;
 192
 193#ifdef CONFIG_STACK_GROWSUP
 194        if (write) {
 195                ret = expand_downwards(bprm->vma, pos);
 196                if (ret < 0)
 197                        return NULL;
 198        }
 199#endif
 200        ret = get_user_pages(current, bprm->mm, pos,
 201                        1, write, 1, &page, NULL);
 202        if (ret <= 0)
 203                return NULL;
 204
 205        if (write) {
 206                unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 207                struct rlimit *rlim;
 208
 209                acct_arg_size(bprm, size / PAGE_SIZE);
 210
 211                /*
 212                 * We've historically supported up to 32 pages (ARG_MAX)
 213                 * of argument strings even with small stacks
 214                 */
 215                if (size <= ARG_MAX)
 216                        return page;
 217
 218                /*
 219                 * Limit to 1/4-th the stack size for the argv+env strings.
 220                 * This ensures that:
 221                 *  - the remaining binfmt code will not run out of stack space,
 222                 *  - the program will have a reasonable amount of stack left
 223                 *    to work from.
 224                 */
 225                rlim = current->signal->rlim;
 226                if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 227                        put_page(page);
 228                        return NULL;
 229                }
 230        }
 231
 232        return page;
 233}
 234
 235static void put_arg_page(struct page *page)
 236{
 237        put_page(page);
 238}
 239
 240static void free_arg_page(struct linux_binprm *bprm, int i)
 241{
 242}
 243
 244static void free_arg_pages(struct linux_binprm *bprm)
 245{
 246}
 247
 248static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 249                struct page *page)
 250{
 251        flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 252}
 253
 254static int __bprm_mm_init(struct linux_binprm *bprm)
 255{
 256        int err;
 257        struct vm_area_struct *vma = NULL;
 258        struct mm_struct *mm = bprm->mm;
 259
 260        bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 261        if (!vma)
 262                return -ENOMEM;
 263
 264        down_write(&mm->mmap_sem);
 265        vma->vm_mm = mm;
 266
 267        /*
 268         * Place the stack at the largest stack address the architecture
 269         * supports. Later, we'll move this to an appropriate place. We don't
 270         * use STACK_TOP because that can depend on attributes which aren't
 271         * configured yet.
 272         */
 273        BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 274        vma->vm_end = STACK_TOP_MAX;
 275        vma->vm_start = vma->vm_end - PAGE_SIZE;
 276        vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 277        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 278        INIT_LIST_HEAD(&vma->anon_vma_chain);
 279
 280        err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
 281        if (err)
 282                goto err;
 283
 284        err = insert_vm_struct(mm, vma);
 285        if (err)
 286                goto err;
 287
 288        mm->stack_vm = mm->total_vm = 1;
 289        up_write(&mm->mmap_sem);
 290        bprm->p = vma->vm_end - sizeof(void *);
 291        return 0;
 292err:
 293        up_write(&mm->mmap_sem);
 294        bprm->vma = NULL;
 295        kmem_cache_free(vm_area_cachep, vma);
 296        return err;
 297}
 298
 299static bool valid_arg_len(struct linux_binprm *bprm, long len)
 300{
 301        return len <= MAX_ARG_STRLEN;
 302}
 303
 304#else
 305
 306static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 307{
 308}
 309
 310static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 311                int write)
 312{
 313        struct page *page;
 314
 315        page = bprm->page[pos / PAGE_SIZE];
 316        if (!page && write) {
 317                page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 318                if (!page)
 319                        return NULL;
 320                bprm->page[pos / PAGE_SIZE] = page;
 321        }
 322
 323        return page;
 324}
 325
 326static void put_arg_page(struct page *page)
 327{
 328}
 329
 330static void free_arg_page(struct linux_binprm *bprm, int i)
 331{
 332        if (bprm->page[i]) {
 333                __free_page(bprm->page[i]);
 334                bprm->page[i] = NULL;
 335        }
 336}
 337
 338static void free_arg_pages(struct linux_binprm *bprm)
 339{
 340        int i;
 341
 342        for (i = 0; i < MAX_ARG_PAGES; i++)
 343                free_arg_page(bprm, i);
 344}
 345
 346static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 347                struct page *page)
 348{
 349}
 350
 351static int __bprm_mm_init(struct linux_binprm *bprm)
 352{
 353        bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 354        return 0;
 355}
 356
 357static bool valid_arg_len(struct linux_binprm *bprm, long len)
 358{
 359        return len <= bprm->p;
 360}
 361
 362#endif /* CONFIG_MMU */
 363
 364/*
 365 * Create a new mm_struct and populate it with a temporary stack
 366 * vm_area_struct.  We don't have enough context at this point to set the stack
 367 * flags, permissions, and offset, so we use temporary values.  We'll update
 368 * them later in setup_arg_pages().
 369 */
 370int bprm_mm_init(struct linux_binprm *bprm)
 371{
 372        int err;
 373        struct mm_struct *mm = NULL;
 374
 375        bprm->mm = mm = mm_alloc();
 376        err = -ENOMEM;
 377        if (!mm)
 378                goto err;
 379
 380        err = init_new_context(current, mm);
 381        if (err)
 382                goto err;
 383
 384        err = __bprm_mm_init(bprm);
 385        if (err)
 386                goto err;
 387
 388        return 0;
 389
 390err:
 391        if (mm) {
 392                bprm->mm = NULL;
 393                mmdrop(mm);
 394        }
 395
 396        return err;
 397}
 398
 399struct user_arg_ptr {
 400#ifdef CONFIG_COMPAT
 401        bool is_compat;
 402#endif
 403        union {
 404                const char __user *const __user *native;
 405#ifdef CONFIG_COMPAT
 406                compat_uptr_t __user *compat;
 407#endif
 408        } ptr;
 409};
 410
 411static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 412{
 413        const char __user *native;
 414
 415#ifdef CONFIG_COMPAT
 416        if (unlikely(argv.is_compat)) {
 417                compat_uptr_t compat;
 418
 419                if (get_user(compat, argv.ptr.compat + nr))
 420                        return ERR_PTR(-EFAULT);
 421
 422                return compat_ptr(compat);
 423        }
 424#endif
 425
 426        if (get_user(native, argv.ptr.native + nr))
 427                return ERR_PTR(-EFAULT);
 428
 429        return native;
 430}
 431
 432/*
 433 * count() counts the number of strings in array ARGV.
 434 */
 435static int count(struct user_arg_ptr argv, int max)
 436{
 437        int i = 0;
 438
 439        if (argv.ptr.native != NULL) {
 440                for (;;) {
 441                        const char __user *p = get_user_arg_ptr(argv, i);
 442
 443                        if (!p)
 444                                break;
 445
 446                        if (IS_ERR(p))
 447                                return -EFAULT;
 448
 449                        if (i++ >= max)
 450                                return -E2BIG;
 451
 452                        if (fatal_signal_pending(current))
 453                                return -ERESTARTNOHAND;
 454                        cond_resched();
 455                }
 456        }
 457        return i;
 458}
 459
 460/*
 461 * 'copy_strings()' copies argument/environment strings from the old
 462 * processes's memory to the new process's stack.  The call to get_user_pages()
 463 * ensures the destination page is created and not swapped out.
 464 */
 465static int copy_strings(int argc, struct user_arg_ptr argv,
 466                        struct linux_binprm *bprm)
 467{
 468        struct page *kmapped_page = NULL;
 469        char *kaddr = NULL;
 470        unsigned long kpos = 0;
 471        int ret;
 472
 473        while (argc-- > 0) {
 474                const char __user *str;
 475                int len;
 476                unsigned long pos;
 477
 478                ret = -EFAULT;
 479                str = get_user_arg_ptr(argv, argc);
 480                if (IS_ERR(str))
 481                        goto out;
 482
 483                len = strnlen_user(str, MAX_ARG_STRLEN);
 484                if (!len)
 485                        goto out;
 486
 487                ret = -E2BIG;
 488                if (!valid_arg_len(bprm, len))
 489                        goto out;
 490
 491                /* We're going to work our way backwords. */
 492                pos = bprm->p;
 493                str += len;
 494                bprm->p -= len;
 495
 496                while (len > 0) {
 497                        int offset, bytes_to_copy;
 498
 499                        if (fatal_signal_pending(current)) {
 500                                ret = -ERESTARTNOHAND;
 501                                goto out;
 502                        }
 503                        cond_resched();
 504
 505                        offset = pos % PAGE_SIZE;
 506                        if (offset == 0)
 507                                offset = PAGE_SIZE;
 508
 509                        bytes_to_copy = offset;
 510                        if (bytes_to_copy > len)
 511                                bytes_to_copy = len;
 512
 513                        offset -= bytes_to_copy;
 514                        pos -= bytes_to_copy;
 515                        str -= bytes_to_copy;
 516                        len -= bytes_to_copy;
 517
 518                        if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 519                                struct page *page;
 520
 521                                page = get_arg_page(bprm, pos, 1);
 522                                if (!page) {
 523                                        ret = -E2BIG;
 524                                        goto out;
 525                                }
 526
 527                                if (kmapped_page) {
 528                                        flush_kernel_dcache_page(kmapped_page);
 529                                        kunmap(kmapped_page);
 530                                        put_arg_page(kmapped_page);
 531                                }
 532                                kmapped_page = page;
 533                                kaddr = kmap(kmapped_page);
 534                                kpos = pos & PAGE_MASK;
 535                                flush_arg_page(bprm, kpos, kmapped_page);
 536                        }
 537                        if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 538                                ret = -EFAULT;
 539                                goto out;
 540                        }
 541                }
 542        }
 543        ret = 0;
 544out:
 545        if (kmapped_page) {
 546                flush_kernel_dcache_page(kmapped_page);
 547                kunmap(kmapped_page);
 548                put_arg_page(kmapped_page);
 549        }
 550        return ret;
 551}
 552
 553/*
 554 * Like copy_strings, but get argv and its values from kernel memory.
 555 */
 556int copy_strings_kernel(int argc, const char *const *__argv,
 557                        struct linux_binprm *bprm)
 558{
 559        int r;
 560        mm_segment_t oldfs = get_fs();
 561        struct user_arg_ptr argv = {
 562                .ptr.native = (const char __user *const  __user *)__argv,
 563        };
 564
 565        set_fs(KERNEL_DS);
 566        r = copy_strings(argc, argv, bprm);
 567        set_fs(oldfs);
 568
 569        return r;
 570}
 571EXPORT_SYMBOL(copy_strings_kernel);
 572
 573#ifdef CONFIG_MMU
 574
 575/*
 576 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 577 * the binfmt code determines where the new stack should reside, we shift it to
 578 * its final location.  The process proceeds as follows:
 579 *
 580 * 1) Use shift to calculate the new vma endpoints.
 581 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 582 *    arguments passed to subsequent functions are consistent.
 583 * 3) Move vma's page tables to the new range.
 584 * 4) Free up any cleared pgd range.
 585 * 5) Shrink the vma to cover only the new range.
 586 */
 587static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 588{
 589        struct mm_struct *mm = vma->vm_mm;
 590        unsigned long old_start = vma->vm_start;
 591        unsigned long old_end = vma->vm_end;
 592        unsigned long length = old_end - old_start;
 593        unsigned long new_start = old_start - shift;
 594        unsigned long new_end = old_end - shift;
 595        struct mmu_gather tlb;
 596
 597        BUG_ON(new_start > new_end);
 598
 599        /*
 600         * ensure there are no vmas between where we want to go
 601         * and where we are
 602         */
 603        if (vma != find_vma(mm, new_start))
 604                return -EFAULT;
 605
 606        /*
 607         * cover the whole range: [new_start, old_end)
 608         */
 609        if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 610                return -ENOMEM;
 611
 612        /*
 613         * move the page tables downwards, on failure we rely on
 614         * process cleanup to remove whatever mess we made.
 615         */
 616        if (length != move_page_tables(vma, old_start,
 617                                       vma, new_start, length))
 618                return -ENOMEM;
 619
 620        lru_add_drain();
 621        tlb_gather_mmu(&tlb, mm, 0);
 622        if (new_end > old_start) {
 623                /*
 624                 * when the old and new regions overlap clear from new_end.
 625                 */
 626                free_pgd_range(&tlb, new_end, old_end, new_end,
 627                        vma->vm_next ? vma->vm_next->vm_start : 0);
 628        } else {
 629                /*
 630                 * otherwise, clean from old_start; this is done to not touch
 631                 * the address space in [new_end, old_start) some architectures
 632                 * have constraints on va-space that make this illegal (IA64) -
 633                 * for the others its just a little faster.
 634                 */
 635                free_pgd_range(&tlb, old_start, old_end, new_end,
 636                        vma->vm_next ? vma->vm_next->vm_start : 0);
 637        }
 638        tlb_finish_mmu(&tlb, new_end, old_end);
 639
 640        /*
 641         * Shrink the vma to just the new range.  Always succeeds.
 642         */
 643        vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 644
 645        return 0;
 646}
 647
 648/*
 649 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 650 * the stack is optionally relocated, and some extra space is added.
 651 */
 652int setup_arg_pages(struct linux_binprm *bprm,
 653                    unsigned long stack_top,
 654                    int executable_stack)
 655{
 656        unsigned long ret;
 657        unsigned long stack_shift;
 658        struct mm_struct *mm = current->mm;
 659        struct vm_area_struct *vma = bprm->vma;
 660        struct vm_area_struct *prev = NULL;
 661        unsigned long vm_flags;
 662        unsigned long stack_base;
 663        unsigned long stack_size;
 664        unsigned long stack_expand;
 665        unsigned long rlim_stack;
 666
 667#ifdef CONFIG_STACK_GROWSUP
 668        /* Limit stack size to 1GB */
 669        stack_base = rlimit_max(RLIMIT_STACK);
 670        if (stack_base > (1 << 30))
 671                stack_base = 1 << 30;
 672
 673        /* Make sure we didn't let the argument array grow too large. */
 674        if (vma->vm_end - vma->vm_start > stack_base)
 675                return -ENOMEM;
 676
 677        stack_base = PAGE_ALIGN(stack_top - stack_base);
 678
 679        stack_shift = vma->vm_start - stack_base;
 680        mm->arg_start = bprm->p - stack_shift;
 681        bprm->p = vma->vm_end - stack_shift;
 682#else
 683        stack_top = arch_align_stack(stack_top);
 684        stack_top = PAGE_ALIGN(stack_top);
 685
 686        if (unlikely(stack_top < mmap_min_addr) ||
 687            unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 688                return -ENOMEM;
 689
 690        stack_shift = vma->vm_end - stack_top;
 691
 692        bprm->p -= stack_shift;
 693        mm->arg_start = bprm->p;
 694#endif
 695
 696        if (bprm->loader)
 697                bprm->loader -= stack_shift;
 698        bprm->exec -= stack_shift;
 699
 700        down_write(&mm->mmap_sem);
 701        vm_flags = VM_STACK_FLAGS;
 702
 703        /*
 704         * Adjust stack execute permissions; explicitly enable for
 705         * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 706         * (arch default) otherwise.
 707         */
 708        if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 709                vm_flags |= VM_EXEC;
 710        else if (executable_stack == EXSTACK_DISABLE_X)
 711                vm_flags &= ~VM_EXEC;
 712        vm_flags |= mm->def_flags;
 713        vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 714
 715        ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 716                        vm_flags);
 717        if (ret)
 718                goto out_unlock;
 719        BUG_ON(prev != vma);
 720
 721        /* Move stack pages down in memory. */
 722        if (stack_shift) {
 723                ret = shift_arg_pages(vma, stack_shift);
 724                if (ret)
 725                        goto out_unlock;
 726        }
 727
 728        /* mprotect_fixup is overkill to remove the temporary stack flags */
 729        vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 730
 731        stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 732        stack_size = vma->vm_end - vma->vm_start;
 733        /*
 734         * Align this down to a page boundary as expand_stack
 735         * will align it up.
 736         */
 737        rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 738#ifdef CONFIG_STACK_GROWSUP
 739        if (stack_size + stack_expand > rlim_stack)
 740                stack_base = vma->vm_start + rlim_stack;
 741        else
 742                stack_base = vma->vm_end + stack_expand;
 743#else
 744        if (stack_size + stack_expand > rlim_stack)
 745                stack_base = vma->vm_end - rlim_stack;
 746        else
 747                stack_base = vma->vm_start - stack_expand;
 748#endif
 749        current->mm->start_stack = bprm->p;
 750        ret = expand_stack(vma, stack_base);
 751        if (ret)
 752                ret = -EFAULT;
 753
 754out_unlock:
 755        up_write(&mm->mmap_sem);
 756        return ret;
 757}
 758EXPORT_SYMBOL(setup_arg_pages);
 759
 760#endif /* CONFIG_MMU */
 761
 762struct file *open_exec(const char *name)
 763{
 764        struct file *file;
 765        int err;
 766        static const struct open_flags open_exec_flags = {
 767                .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 768                .acc_mode = MAY_EXEC | MAY_OPEN,
 769                .intent = LOOKUP_OPEN
 770        };
 771
 772        file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
 773        if (IS_ERR(file))
 774                goto out;
 775
 776        err = -EACCES;
 777        if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 778                goto exit;
 779
 780        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 781                goto exit;
 782
 783        fsnotify_open(file);
 784
 785        err = deny_write_access(file);
 786        if (err)
 787                goto exit;
 788
 789out:
 790        return file;
 791
 792exit:
 793        fput(file);
 794        return ERR_PTR(err);
 795}
 796EXPORT_SYMBOL(open_exec);
 797
 798int kernel_read(struct file *file, loff_t offset,
 799                char *addr, unsigned long count)
 800{
 801        mm_segment_t old_fs;
 802        loff_t pos = offset;
 803        int result;
 804
 805        old_fs = get_fs();
 806        set_fs(get_ds());
 807        /* The cast to a user pointer is valid due to the set_fs() */
 808        result = vfs_read(file, (void __user *)addr, count, &pos);
 809        set_fs(old_fs);
 810        return result;
 811}
 812
 813EXPORT_SYMBOL(kernel_read);
 814
 815static int exec_mmap(struct mm_struct *mm)
 816{
 817        struct task_struct *tsk;
 818        struct mm_struct * old_mm, *active_mm;
 819
 820        /* Notify parent that we're no longer interested in the old VM */
 821        tsk = current;
 822        old_mm = current->mm;
 823        sync_mm_rss(tsk, old_mm);
 824        mm_release(tsk, old_mm);
 825
 826        if (old_mm) {
 827                /*
 828                 * Make sure that if there is a core dump in progress
 829                 * for the old mm, we get out and die instead of going
 830                 * through with the exec.  We must hold mmap_sem around
 831                 * checking core_state and changing tsk->mm.
 832                 */
 833                down_read(&old_mm->mmap_sem);
 834                if (unlikely(old_mm->core_state)) {
 835                        up_read(&old_mm->mmap_sem);
 836                        return -EINTR;
 837                }
 838        }
 839        task_lock(tsk);
 840        active_mm = tsk->active_mm;
 841        tsk->mm = mm;
 842        tsk->active_mm = mm;
 843        activate_mm(active_mm, mm);
 844        if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
 845                atomic_dec(&old_mm->oom_disable_count);
 846                atomic_inc(&tsk->mm->oom_disable_count);
 847        }
 848        task_unlock(tsk);
 849        arch_pick_mmap_layout(mm);
 850        if (old_mm) {
 851                up_read(&old_mm->mmap_sem);
 852                BUG_ON(active_mm != old_mm);
 853                mm_update_next_owner(old_mm);
 854                mmput(old_mm);
 855                return 0;
 856        }
 857        mmdrop(active_mm);
 858        return 0;
 859}
 860
 861/*
 862 * This function makes sure the current process has its own signal table,
 863 * so that flush_signal_handlers can later reset the handlers without
 864 * disturbing other processes.  (Other processes might share the signal
 865 * table via the CLONE_SIGHAND option to clone().)
 866 */
 867static int de_thread(struct task_struct *tsk)
 868{
 869        struct signal_struct *sig = tsk->signal;
 870        struct sighand_struct *oldsighand = tsk->sighand;
 871        spinlock_t *lock = &oldsighand->siglock;
 872
 873        if (thread_group_empty(tsk))
 874                goto no_thread_group;
 875
 876        /*
 877         * Kill all other threads in the thread group.
 878         */
 879        spin_lock_irq(lock);
 880        if (signal_group_exit(sig)) {
 881                /*
 882                 * Another group action in progress, just
 883                 * return so that the signal is processed.
 884                 */
 885                spin_unlock_irq(lock);
 886                return -EAGAIN;
 887        }
 888
 889        sig->group_exit_task = tsk;
 890        sig->notify_count = zap_other_threads(tsk);
 891        if (!thread_group_leader(tsk))
 892                sig->notify_count--;
 893
 894        while (sig->notify_count) {
 895                __set_current_state(TASK_UNINTERRUPTIBLE);
 896                spin_unlock_irq(lock);
 897                schedule();
 898                spin_lock_irq(lock);
 899        }
 900        spin_unlock_irq(lock);
 901
 902        /*
 903         * At this point all other threads have exited, all we have to
 904         * do is to wait for the thread group leader to become inactive,
 905         * and to assume its PID:
 906         */
 907        if (!thread_group_leader(tsk)) {
 908                struct task_struct *leader = tsk->group_leader;
 909
 910                sig->notify_count = -1; /* for exit_notify() */
 911                for (;;) {
 912                        write_lock_irq(&tasklist_lock);
 913                        if (likely(leader->exit_state))
 914                                break;
 915                        __set_current_state(TASK_UNINTERRUPTIBLE);
 916                        write_unlock_irq(&tasklist_lock);
 917                        schedule();
 918                }
 919
 920                /*
 921                 * The only record we have of the real-time age of a
 922                 * process, regardless of execs it's done, is start_time.
 923                 * All the past CPU time is accumulated in signal_struct
 924                 * from sister threads now dead.  But in this non-leader
 925                 * exec, nothing survives from the original leader thread,
 926                 * whose birth marks the true age of this process now.
 927                 * When we take on its identity by switching to its PID, we
 928                 * also take its birthdate (always earlier than our own).
 929                 */
 930                tsk->start_time = leader->start_time;
 931
 932                BUG_ON(!same_thread_group(leader, tsk));
 933                BUG_ON(has_group_leader_pid(tsk));
 934                /*
 935                 * An exec() starts a new thread group with the
 936                 * TGID of the previous thread group. Rehash the
 937                 * two threads with a switched PID, and release
 938                 * the former thread group leader:
 939                 */
 940
 941                /* Become a process group leader with the old leader's pid.
 942                 * The old leader becomes a thread of the this thread group.
 943                 * Note: The old leader also uses this pid until release_task
 944                 *       is called.  Odd but simple and correct.
 945                 */
 946                detach_pid(tsk, PIDTYPE_PID);
 947                tsk->pid = leader->pid;
 948                attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 949                transfer_pid(leader, tsk, PIDTYPE_PGID);
 950                transfer_pid(leader, tsk, PIDTYPE_SID);
 951
 952                list_replace_rcu(&leader->tasks, &tsk->tasks);
 953                list_replace_init(&leader->sibling, &tsk->sibling);
 954
 955                tsk->group_leader = tsk;
 956                leader->group_leader = tsk;
 957
 958                tsk->exit_signal = SIGCHLD;
 959                leader->exit_signal = -1;
 960
 961                BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 962                leader->exit_state = EXIT_DEAD;
 963
 964                /*
 965                 * We are going to release_task()->ptrace_unlink() silently,
 966                 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
 967                 * the tracer wont't block again waiting for this thread.
 968                 */
 969                if (unlikely(leader->ptrace))
 970                        __wake_up_parent(leader, leader->parent);
 971                write_unlock_irq(&tasklist_lock);
 972
 973                release_task(leader);
 974        }
 975
 976        sig->group_exit_task = NULL;
 977        sig->notify_count = 0;
 978
 979no_thread_group:
 980        if (current->mm)
 981                setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
 982
 983        exit_itimers(sig);
 984        flush_itimer_signals();
 985
 986        if (atomic_read(&oldsighand->count) != 1) {
 987                struct sighand_struct *newsighand;
 988                /*
 989                 * This ->sighand is shared with the CLONE_SIGHAND
 990                 * but not CLONE_THREAD task, switch to the new one.
 991                 */
 992                newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 993                if (!newsighand)
 994                        return -ENOMEM;
 995
 996                atomic_set(&newsighand->count, 1);
 997                memcpy(newsighand->action, oldsighand->action,
 998                       sizeof(newsighand->action));
 999
1000                write_lock_irq(&tasklist_lock);
1001                spin_lock(&oldsighand->siglock);
1002                rcu_assign_pointer(tsk->sighand, newsighand);
1003                spin_unlock(&oldsighand->siglock);
1004                write_unlock_irq(&tasklist_lock);
1005
1006                __cleanup_sighand(oldsighand);
1007        }
1008
1009        BUG_ON(!thread_group_leader(tsk));
1010        return 0;
1011}
1012
1013/*
1014 * These functions flushes out all traces of the currently running executable
1015 * so that a new one can be started
1016 */
1017static void flush_old_files(struct files_struct * files)
1018{
1019        long j = -1;
1020        struct fdtable *fdt;
1021
1022        spin_lock(&files->file_lock);
1023        for (;;) {
1024                unsigned long set, i;
1025
1026                j++;
1027                i = j * __NFDBITS;
1028                fdt = files_fdtable(files);
1029                if (i >= fdt->max_fds)
1030                        break;
1031                set = fdt->close_on_exec->fds_bits[j];
1032                if (!set)
1033                        continue;
1034                fdt->close_on_exec->fds_bits[j] = 0;
1035                spin_unlock(&files->file_lock);
1036                for ( ; set ; i++,set >>= 1) {
1037                        if (set & 1) {
1038                                sys_close(i);
1039                        }
1040                }
1041                spin_lock(&files->file_lock);
1042
1043        }
1044        spin_unlock(&files->file_lock);
1045}
1046
1047char *get_task_comm(char *buf, struct task_struct *tsk)
1048{
1049        /* buf must be at least sizeof(tsk->comm) in size */
1050        task_lock(tsk);
1051        strncpy(buf, tsk->comm, sizeof(tsk->comm));
1052        task_unlock(tsk);
1053        return buf;
1054}
1055EXPORT_SYMBOL_GPL(get_task_comm);
1056
1057void set_task_comm(struct task_struct *tsk, char *buf)
1058{
1059        task_lock(tsk);
1060
1061        /*
1062         * Threads may access current->comm without holding
1063         * the task lock, so write the string carefully.
1064         * Readers without a lock may see incomplete new
1065         * names but are safe from non-terminating string reads.
1066         */
1067        memset(tsk->comm, 0, TASK_COMM_LEN);
1068        wmb();
1069        strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1070        task_unlock(tsk);
1071        perf_event_comm(tsk);
1072}
1073
1074int flush_old_exec(struct linux_binprm * bprm)
1075{
1076        int retval;
1077
1078        /*
1079         * Make sure we have a private signal table and that
1080         * we are unassociated from the previous thread group.
1081         */
1082        retval = de_thread(current);
1083        if (retval)
1084                goto out;
1085
1086        set_mm_exe_file(bprm->mm, bprm->file);
1087
1088        /*
1089         * Release all of the old mmap stuff
1090         */
1091        acct_arg_size(bprm, 0);
1092        retval = exec_mmap(bprm->mm);
1093        if (retval)
1094                goto out;
1095
1096        bprm->mm = NULL;                /* We're using it now */
1097
1098        set_fs(USER_DS);
1099        current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1100        flush_thread();
1101        current->personality &= ~bprm->per_clear;
1102
1103        return 0;
1104
1105out:
1106        return retval;
1107}
1108EXPORT_SYMBOL(flush_old_exec);
1109
1110void would_dump(struct linux_binprm *bprm, struct file *file)
1111{
1112        if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
1113                bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1114}
1115EXPORT_SYMBOL(would_dump);
1116
1117void setup_new_exec(struct linux_binprm * bprm)
1118{
1119        int i, ch;
1120        const char *name;
1121        char tcomm[sizeof(current->comm)];
1122
1123        arch_pick_mmap_layout(current->mm);
1124
1125        /* This is the point of no return */
1126        current->sas_ss_sp = current->sas_ss_size = 0;
1127
1128        if (current_euid() == current_uid() && current_egid() == current_gid())
1129                set_dumpable(current->mm, 1);
1130        else
1131                set_dumpable(current->mm, suid_dumpable);
1132
1133        name = bprm->filename;
1134
1135        /* Copies the binary name from after last slash */
1136        for (i=0; (ch = *(name++)) != '\0';) {
1137                if (ch == '/')
1138                        i = 0; /* overwrite what we wrote */
1139                else
1140                        if (i < (sizeof(tcomm) - 1))
1141                                tcomm[i++] = ch;
1142        }
1143        tcomm[i] = '\0';
1144        set_task_comm(current, tcomm);
1145
1146        /* Set the new mm task size. We have to do that late because it may
1147         * depend on TIF_32BIT which is only updated in flush_thread() on
1148         * some architectures like powerpc
1149         */
1150        current->mm->task_size = TASK_SIZE;
1151
1152        /* install the new credentials */
1153        if (bprm->cred->uid != current_euid() ||
1154            bprm->cred->gid != current_egid()) {
1155                current->pdeath_signal = 0;
1156        } else {
1157                would_dump(bprm, bprm->file);
1158                if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1159                        set_dumpable(current->mm, suid_dumpable);
1160        }
1161
1162        /*
1163         * Flush performance counters when crossing a
1164         * security domain:
1165         */
1166        if (!get_dumpable(current->mm))
1167                perf_event_exit_task(current);
1168
1169        /* An exec changes our domain. We are no longer part of the thread
1170           group */
1171
1172        current->self_exec_id++;
1173                        
1174        flush_signal_handlers(current, 0);
1175        flush_old_files(current->files);
1176}
1177EXPORT_SYMBOL(setup_new_exec);
1178
1179/*
1180 * Prepare credentials and lock ->cred_guard_mutex.
1181 * install_exec_creds() commits the new creds and drops the lock.
1182 * Or, if exec fails before, free_bprm() should release ->cred and
1183 * and unlock.
1184 */
1185int prepare_bprm_creds(struct linux_binprm *bprm)
1186{
1187        if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1188                return -ERESTARTNOINTR;
1189
1190        bprm->cred = prepare_exec_creds();
1191        if (likely(bprm->cred))
1192                return 0;
1193
1194        mutex_unlock(&current->signal->cred_guard_mutex);
1195        return -ENOMEM;
1196}
1197
1198void free_bprm(struct linux_binprm *bprm)
1199{
1200        free_arg_pages(bprm);
1201        if (bprm->cred) {
1202                mutex_unlock(&current->signal->cred_guard_mutex);
1203                abort_creds(bprm->cred);
1204        }
1205        kfree(bprm);
1206}
1207
1208/*
1209 * install the new credentials for this executable
1210 */
1211void install_exec_creds(struct linux_binprm *bprm)
1212{
1213        security_bprm_committing_creds(bprm);
1214
1215        commit_creds(bprm->cred);
1216        bprm->cred = NULL;
1217        /*
1218         * cred_guard_mutex must be held at least to this point to prevent
1219         * ptrace_attach() from altering our determination of the task's
1220         * credentials; any time after this it may be unlocked.
1221         */
1222        security_bprm_committed_creds(bprm);
1223        mutex_unlock(&current->signal->cred_guard_mutex);
1224}
1225EXPORT_SYMBOL(install_exec_creds);
1226
1227/*
1228 * determine how safe it is to execute the proposed program
1229 * - the caller must hold ->cred_guard_mutex to protect against
1230 *   PTRACE_ATTACH
1231 */
1232int check_unsafe_exec(struct linux_binprm *bprm)
1233{
1234        struct task_struct *p = current, *t;
1235        unsigned n_fs;
1236        int res = 0;
1237
1238        if (p->ptrace) {
1239                if (p->ptrace & PT_PTRACE_CAP)
1240                        bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1241                else
1242                        bprm->unsafe |= LSM_UNSAFE_PTRACE;
1243        }
1244
1245        n_fs = 1;
1246        spin_lock(&p->fs->lock);
1247        rcu_read_lock();
1248        for (t = next_thread(p); t != p; t = next_thread(t)) {
1249                if (t->fs == p->fs)
1250                        n_fs++;
1251        }
1252        rcu_read_unlock();
1253
1254        if (p->fs->users > n_fs) {
1255                bprm->unsafe |= LSM_UNSAFE_SHARE;
1256        } else {
1257                res = -EAGAIN;
1258                if (!p->fs->in_exec) {
1259                        p->fs->in_exec = 1;
1260                        res = 1;
1261                }
1262        }
1263        spin_unlock(&p->fs->lock);
1264
1265        return res;
1266}
1267
1268/* 
1269 * Fill the binprm structure from the inode. 
1270 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1271 *
1272 * This may be called multiple times for binary chains (scripts for example).
1273 */
1274int prepare_binprm(struct linux_binprm *bprm)
1275{
1276        umode_t mode;
1277        struct inode * inode = bprm->file->f_path.dentry->d_inode;
1278        int retval;
1279
1280        mode = inode->i_mode;
1281        if (bprm->file->f_op == NULL)
1282                return -EACCES;
1283
1284        /* clear any previous set[ug]id data from a previous binary */
1285        bprm->cred->euid = current_euid();
1286        bprm->cred->egid = current_egid();
1287
1288        if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1289                /* Set-uid? */
1290                if (mode & S_ISUID) {
1291                        bprm->per_clear |= PER_CLEAR_ON_SETID;
1292                        bprm->cred->euid = inode->i_uid;
1293                }
1294
1295                /* Set-gid? */
1296                /*
1297                 * If setgid is set but no group execute bit then this
1298                 * is a candidate for mandatory locking, not a setgid
1299                 * executable.
1300                 */
1301                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1302                        bprm->per_clear |= PER_CLEAR_ON_SETID;
1303                        bprm->cred->egid = inode->i_gid;
1304                }
1305        }
1306
1307        /* fill in binprm security blob */
1308        retval = security_bprm_set_creds(bprm);
1309        if (retval)
1310                return retval;
1311        bprm->cred_prepared = 1;
1312
1313        memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1314        return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1315}
1316
1317EXPORT_SYMBOL(prepare_binprm);
1318
1319/*
1320 * Arguments are '\0' separated strings found at the location bprm->p
1321 * points to; chop off the first by relocating brpm->p to right after
1322 * the first '\0' encountered.
1323 */
1324int remove_arg_zero(struct linux_binprm *bprm)
1325{
1326        int ret = 0;
1327        unsigned long offset;
1328        char *kaddr;
1329        struct page *page;
1330
1331        if (!bprm->argc)
1332                return 0;
1333
1334        do {
1335                offset = bprm->p & ~PAGE_MASK;
1336                page = get_arg_page(bprm, bprm->p, 0);
1337                if (!page) {
1338                        ret = -EFAULT;
1339                        goto out;
1340                }
1341                kaddr = kmap_atomic(page, KM_USER0);
1342
1343                for (; offset < PAGE_SIZE && kaddr[offset];
1344                                offset++, bprm->p++)
1345                        ;
1346
1347                kunmap_atomic(kaddr, KM_USER0);
1348                put_arg_page(page);
1349
1350                if (offset == PAGE_SIZE)
1351                        free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1352        } while (offset == PAGE_SIZE);
1353
1354        bprm->p++;
1355        bprm->argc--;
1356        ret = 0;
1357
1358out:
1359        return ret;
1360}
1361EXPORT_SYMBOL(remove_arg_zero);
1362
1363/*
1364 * cycle the list of binary formats handler, until one recognizes the image
1365 */
1366int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1367{
1368        unsigned int depth = bprm->recursion_depth;
1369        int try,retval;
1370        struct linux_binfmt *fmt;
1371        pid_t old_pid;
1372
1373        retval = security_bprm_check(bprm);
1374        if (retval)
1375                return retval;
1376
1377        retval = audit_bprm(bprm);
1378        if (retval)
1379                return retval;
1380
1381        /* Need to fetch pid before load_binary changes it */
1382        rcu_read_lock();
1383        old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1384        rcu_read_unlock();
1385
1386        retval = -ENOENT;
1387        for (try=0; try<2; try++) {
1388                read_lock(&binfmt_lock);
1389                list_for_each_entry(fmt, &formats, lh) {
1390                        int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1391                        if (!fn)
1392                                continue;
1393                        if (!try_module_get(fmt->module))
1394                                continue;
1395                        read_unlock(&binfmt_lock);
1396                        retval = fn(bprm, regs);
1397                        /*
1398                         * Restore the depth counter to its starting value
1399                         * in this call, so we don't have to rely on every
1400                         * load_binary function to restore it on return.
1401                         */
1402                        bprm->recursion_depth = depth;
1403                        if (retval >= 0) {
1404                                if (depth == 0)
1405                                        ptrace_event(PTRACE_EVENT_EXEC,
1406                                                        old_pid);
1407                                put_binfmt(fmt);
1408                                allow_write_access(bprm->file);
1409                                if (bprm->file)
1410                                        fput(bprm->file);
1411                                bprm->file = NULL;
1412                                current->did_exec = 1;
1413                                proc_exec_connector(current);
1414                                return retval;
1415                        }
1416                        read_lock(&binfmt_lock);
1417                        put_binfmt(fmt);
1418                        if (retval != -ENOEXEC || bprm->mm == NULL)
1419                                break;
1420                        if (!bprm->file) {
1421                                read_unlock(&binfmt_lock);
1422                                return retval;
1423                        }
1424                }
1425                read_unlock(&binfmt_lock);
1426#ifdef CONFIG_MODULES
1427                if (retval != -ENOEXEC || bprm->mm == NULL) {
1428                        break;
1429                } else {
1430#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1431                        if (printable(bprm->buf[0]) &&
1432                            printable(bprm->buf[1]) &&
1433                            printable(bprm->buf[2]) &&
1434                            printable(bprm->buf[3]))
1435                                break; /* -ENOEXEC */
1436                        if (try)
1437                                break; /* -ENOEXEC */
1438                        request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1439                }
1440#else
1441                break;
1442#endif
1443        }
1444        return retval;
1445}
1446
1447EXPORT_SYMBOL(search_binary_handler);
1448
1449/*
1450 * sys_execve() executes a new program.
1451 */
1452static int do_execve_common(const char *filename,
1453                                struct user_arg_ptr argv,
1454                                struct user_arg_ptr envp,
1455                                struct pt_regs *regs)
1456{
1457        struct linux_binprm *bprm;
1458        struct file *file;
1459        struct files_struct *displaced;
1460        bool clear_in_exec;
1461        int retval;
1462        const struct cred *cred = current_cred();
1463
1464        /*
1465         * We move the actual failure in case of RLIMIT_NPROC excess from
1466         * set*uid() to execve() because too many poorly written programs
1467         * don't check setuid() return code.  Here we additionally recheck
1468         * whether NPROC limit is still exceeded.
1469         */
1470        if ((current->flags & PF_NPROC_EXCEEDED) &&
1471            atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
1472                retval = -EAGAIN;
1473                goto out_ret;
1474        }
1475
1476        /* We're below the limit (still or again), so we don't want to make
1477         * further execve() calls fail. */
1478        current->flags &= ~PF_NPROC_EXCEEDED;
1479
1480        retval = unshare_files(&displaced);
1481        if (retval)
1482                goto out_ret;
1483
1484        retval = -ENOMEM;
1485        bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1486        if (!bprm)
1487                goto out_files;
1488
1489        retval = prepare_bprm_creds(bprm);
1490        if (retval)
1491                goto out_free;
1492
1493        retval = check_unsafe_exec(bprm);
1494        if (retval < 0)
1495                goto out_free;
1496        clear_in_exec = retval;
1497        current->in_execve = 1;
1498
1499        file = open_exec(filename);
1500        retval = PTR_ERR(file);
1501        if (IS_ERR(file))
1502                goto out_unmark;
1503
1504        sched_exec();
1505
1506        bprm->file = file;
1507        bprm->filename = filename;
1508        bprm->interp = filename;
1509
1510        retval = bprm_mm_init(bprm);
1511        if (retval)
1512                goto out_file;
1513
1514        bprm->argc = count(argv, MAX_ARG_STRINGS);
1515        if ((retval = bprm->argc) < 0)
1516                goto out;
1517
1518        bprm->envc = count(envp, MAX_ARG_STRINGS);
1519        if ((retval = bprm->envc) < 0)
1520                goto out;
1521
1522        retval = prepare_binprm(bprm);
1523        if (retval < 0)
1524                goto out;
1525
1526        retval = copy_strings_kernel(1, &bprm->filename, bprm);
1527        if (retval < 0)
1528                goto out;
1529
1530        bprm->exec = bprm->p;
1531        retval = copy_strings(bprm->envc, envp, bprm);
1532        if (retval < 0)
1533                goto out;
1534
1535        retval = copy_strings(bprm->argc, argv, bprm);
1536        if (retval < 0)
1537                goto out;
1538
1539        retval = search_binary_handler(bprm,regs);
1540        if (retval < 0)
1541                goto out;
1542
1543        /* execve succeeded */
1544        current->fs->in_exec = 0;
1545        current->in_execve = 0;
1546        acct_update_integrals(current);
1547        free_bprm(bprm);
1548        if (displaced)
1549                put_files_struct(displaced);
1550        return retval;
1551
1552out:
1553        if (bprm->mm) {
1554                acct_arg_size(bprm, 0);
1555                mmput(bprm->mm);
1556        }
1557
1558out_file:
1559        if (bprm->file) {
1560                allow_write_access(bprm->file);
1561                fput(bprm->file);
1562        }
1563
1564out_unmark:
1565        if (clear_in_exec)
1566                current->fs->in_exec = 0;
1567        current->in_execve = 0;
1568
1569out_free:
1570        free_bprm(bprm);
1571
1572out_files:
1573        if (displaced)
1574                reset_files_struct(displaced);
1575out_ret:
1576        return retval;
1577}
1578
1579int do_execve(const char *filename,
1580        const char __user *const __user *__argv,
1581        const char __user *const __user *__envp,
1582        struct pt_regs *regs)
1583{
1584        struct user_arg_ptr argv = { .ptr.native = __argv };
1585        struct user_arg_ptr envp = { .ptr.native = __envp };
1586        return do_execve_common(filename, argv, envp, regs);
1587}
1588
1589#ifdef CONFIG_COMPAT
1590int compat_do_execve(char *filename,
1591        compat_uptr_t __user *__argv,
1592        compat_uptr_t __user *__envp,
1593        struct pt_regs *regs)
1594{
1595        struct user_arg_ptr argv = {
1596                .is_compat = true,
1597                .ptr.compat = __argv,
1598        };
1599        struct user_arg_ptr envp = {
1600                .is_compat = true,
1601                .ptr.compat = __envp,
1602        };
1603        return do_execve_common(filename, argv, envp, regs);
1604}
1605#endif
1606
1607void set_binfmt(struct linux_binfmt *new)
1608{
1609        struct mm_struct *mm = current->mm;
1610
1611        if (mm->binfmt)
1612                module_put(mm->binfmt->module);
1613
1614        mm->binfmt = new;
1615        if (new)
1616                __module_get(new->module);
1617}
1618
1619EXPORT_SYMBOL(set_binfmt);
1620
1621static int expand_corename(struct core_name *cn)
1622{
1623        char *old_corename = cn->corename;
1624
1625        cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1626        cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1627
1628        if (!cn->corename) {
1629                kfree(old_corename);
1630                return -ENOMEM;
1631        }
1632
1633        return 0;
1634}
1635
1636static int cn_printf(struct core_name *cn, const char *fmt, ...)
1637{
1638        char *cur;
1639        int need;
1640        int ret;
1641        va_list arg;
1642
1643        va_start(arg, fmt);
1644        need = vsnprintf(NULL, 0, fmt, arg);
1645        va_end(arg);
1646
1647        if (likely(need < cn->size - cn->used - 1))
1648                goto out_printf;
1649
1650        ret = expand_corename(cn);
1651        if (ret)
1652                goto expand_fail;
1653
1654out_printf:
1655        cur = cn->corename + cn->used;
1656        va_start(arg, fmt);
1657        vsnprintf(cur, need + 1, fmt, arg);
1658        va_end(arg);
1659        cn->used += need;
1660        return 0;
1661
1662expand_fail:
1663        return ret;
1664}
1665
1666static void cn_escape(char *str)
1667{
1668        for (; *str; str++)
1669                if (*str == '/')
1670                        *str = '!';
1671}
1672
1673static int cn_print_exe_file(struct core_name *cn)
1674{
1675        struct file *exe_file;
1676        char *pathbuf, *path;
1677        int ret;
1678
1679        exe_file = get_mm_exe_file(current->mm);
1680        if (!exe_file) {
1681                char *commstart = cn->corename + cn->used;
1682                ret = cn_printf(cn, "%s (path unknown)", current->comm);
1683                cn_escape(commstart);
1684                return ret;
1685        }
1686
1687        pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1688        if (!pathbuf) {
1689                ret = -ENOMEM;
1690                goto put_exe_file;
1691        }
1692
1693        path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1694        if (IS_ERR(path)) {
1695                ret = PTR_ERR(path);
1696                goto free_buf;
1697        }
1698
1699        cn_escape(path);
1700
1701        ret = cn_printf(cn, "%s", path);
1702
1703free_buf:
1704        kfree(pathbuf);
1705put_exe_file:
1706        fput(exe_file);
1707        return ret;
1708}
1709
1710/* format_corename will inspect the pattern parameter, and output a
1711 * name into corename, which must have space for at least
1712 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1713 */
1714static int format_corename(struct core_name *cn, long signr)
1715{
1716        const struct cred *cred = current_cred();
1717        const char *pat_ptr = core_pattern;
1718        int ispipe = (*pat_ptr == '|');
1719        int pid_in_pattern = 0;
1720        int err = 0;
1721
1722        cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1723        cn->corename = kmalloc(cn->size, GFP_KERNEL);
1724        cn->used = 0;
1725
1726        if (!cn->corename)
1727                return -ENOMEM;
1728
1729        /* Repeat as long as we have more pattern to process and more output
1730           space */
1731        while (*pat_ptr) {
1732                if (*pat_ptr != '%') {
1733                        if (*pat_ptr == 0)
1734                                goto out;
1735                        err = cn_printf(cn, "%c", *pat_ptr++);
1736                } else {
1737                        switch (*++pat_ptr) {
1738                        /* single % at the end, drop that */
1739                        case 0:
1740                                goto out;
1741                        /* Double percent, output one percent */
1742                        case '%':
1743                                err = cn_printf(cn, "%c", '%');
1744                                break;
1745                        /* pid */
1746                        case 'p':
1747                                pid_in_pattern = 1;
1748                                err = cn_printf(cn, "%d",
1749                                              task_tgid_vnr(current));
1750                                break;
1751                        /* uid */
1752                        case 'u':
1753                                err = cn_printf(cn, "%d", cred->uid);
1754                                break;
1755                        /* gid */
1756                        case 'g':
1757                                err = cn_printf(cn, "%d", cred->gid);
1758                                break;
1759                        /* signal that caused the coredump */
1760                        case 's':
1761                                err = cn_printf(cn, "%ld", signr);
1762                                break;
1763                        /* UNIX time of coredump */
1764                        case 't': {
1765                                struct timeval tv;
1766                                do_gettimeofday(&tv);
1767                                err = cn_printf(cn, "%lu", tv.tv_sec);
1768                                break;
1769                        }
1770                        /* hostname */
1771                        case 'h': {
1772                                char *namestart = cn->corename + cn->used;
1773                                down_read(&uts_sem);
1774                                err = cn_printf(cn, "%s",
1775                                              utsname()->nodename);
1776                                up_read(&uts_sem);
1777                                cn_escape(namestart);
1778                                break;
1779                        }
1780                        /* executable */
1781                        case 'e': {
1782                                char *commstart = cn->corename + cn->used;
1783                                err = cn_printf(cn, "%s", current->comm);
1784                                cn_escape(commstart);
1785                                break;
1786                        }
1787                        case 'E':
1788                                err = cn_print_exe_file(cn);
1789                                break;
1790                        /* core limit size */
1791                        case 'c':
1792                                err = cn_printf(cn, "%lu",
1793                                              rlimit(RLIMIT_CORE));
1794                                break;
1795                        default:
1796                                break;
1797                        }
1798                        ++pat_ptr;
1799                }
1800
1801                if (err)
1802                        return err;
1803        }
1804
1805        /* Backward compatibility with core_uses_pid:
1806         *
1807         * If core_pattern does not include a %p (as is the default)
1808         * and core_uses_pid is set, then .%pid will be appended to
1809         * the filename. Do not do this for piped commands. */
1810        if (!ispipe && !pid_in_pattern && core_uses_pid) {
1811                err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1812                if (err)
1813                        return err;
1814        }
1815out:
1816        return ispipe;
1817}
1818
1819static int zap_process(struct task_struct *start, int exit_code)
1820{
1821        struct task_struct *t;
1822        int nr = 0;
1823
1824        start->signal->flags = SIGNAL_GROUP_EXIT;
1825        start->signal->group_exit_code = exit_code;
1826        start->signal->group_stop_count = 0;
1827
1828        t = start;
1829        do {
1830                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1831                if (t != current && t->mm) {
1832                        sigaddset(&t->pending.signal, SIGKILL);
1833                        signal_wake_up(t, 1);
1834                        nr++;
1835                }
1836        } while_each_thread(start, t);
1837
1838        return nr;
1839}
1840
1841static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1842                                struct core_state *core_state, int exit_code)
1843{
1844        struct task_struct *g, *p;
1845        unsigned long flags;
1846        int nr = -EAGAIN;
1847
1848        spin_lock_irq(&tsk->sighand->siglock);
1849        if (!signal_group_exit(tsk->signal)) {
1850                mm->core_state = core_state;
1851                nr = zap_process(tsk, exit_code);
1852        }
1853        spin_unlock_irq(&tsk->sighand->siglock);
1854        if (unlikely(nr < 0))
1855                return nr;
1856
1857        if (atomic_read(&mm->mm_users) == nr + 1)
1858                goto done;
1859        /*
1860         * We should find and kill all tasks which use this mm, and we should
1861         * count them correctly into ->nr_threads. We don't take tasklist
1862         * lock, but this is safe wrt:
1863         *
1864         * fork:
1865         *      None of sub-threads can fork after zap_process(leader). All
1866         *      processes which were created before this point should be
1867         *      visible to zap_threads() because copy_process() adds the new
1868         *      process to the tail of init_task.tasks list, and lock/unlock
1869         *      of ->siglock provides a memory barrier.
1870         *
1871         * do_exit:
1872         *      The caller holds mm->mmap_sem. This means that the task which
1873         *      uses this mm can't pass exit_mm(), so it can't exit or clear
1874         *      its ->mm.
1875         *
1876         * de_thread:
1877         *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1878         *      we must see either old or new leader, this does not matter.
1879         *      However, it can change p->sighand, so lock_task_sighand(p)
1880         *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1881         *      it can't fail.
1882         *
1883         *      Note also that "g" can be the old leader with ->mm == NULL
1884         *      and already unhashed and thus removed from ->thread_group.
1885         *      This is OK, __unhash_process()->list_del_rcu() does not
1886         *      clear the ->next pointer, we will find the new leader via
1887         *      next_thread().
1888         */
1889        rcu_read_lock();
1890        for_each_process(g) {
1891                if (g == tsk->group_leader)
1892                        continue;
1893                if (g->flags & PF_KTHREAD)
1894                        continue;
1895                p = g;
1896                do {
1897                        if (p->mm) {
1898                                if (unlikely(p->mm == mm)) {
1899                                        lock_task_sighand(p, &flags);
1900                                        nr += zap_process(p, exit_code);
1901                                        unlock_task_sighand(p, &flags);
1902                                }
1903                                break;
1904                        }
1905                } while_each_thread(g, p);
1906        }
1907        rcu_read_unlock();
1908done:
1909        atomic_set(&core_state->nr_threads, nr);
1910        return nr;
1911}
1912
1913static int coredump_wait(int exit_code, struct core_state *core_state)
1914{
1915        struct task_struct *tsk = current;
1916        struct mm_struct *mm = tsk->mm;
1917        struct completion *vfork_done;
1918        int core_waiters = -EBUSY;
1919
1920        init_completion(&core_state->startup);
1921        core_state->dumper.task = tsk;
1922        core_state->dumper.next = NULL;
1923
1924        down_write(&mm->mmap_sem);
1925        if (!mm->core_state)
1926                core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1927        up_write(&mm->mmap_sem);
1928
1929        if (unlikely(core_waiters < 0))
1930                goto fail;
1931
1932        /*
1933         * Make sure nobody is waiting for us to release the VM,
1934         * otherwise we can deadlock when we wait on each other
1935         */
1936        vfork_done = tsk->vfork_done;
1937        if (vfork_done) {
1938                tsk->vfork_done = NULL;
1939                complete(vfork_done);
1940        }
1941
1942        if (core_waiters)
1943                wait_for_completion(&core_state->startup);
1944fail:
1945        return core_waiters;
1946}
1947
1948static void coredump_finish(struct mm_struct *mm)
1949{
1950        struct core_thread *curr, *next;
1951        struct task_struct *task;
1952
1953        next = mm->core_state->dumper.next;
1954        while ((curr = next) != NULL) {
1955                next = curr->next;
1956                task = curr->task;
1957                /*
1958                 * see exit_mm(), curr->task must not see
1959                 * ->task == NULL before we read ->next.
1960                 */
1961                smp_mb();
1962                curr->task = NULL;
1963                wake_up_process(task);
1964        }
1965
1966        mm->core_state = NULL;
1967}
1968
1969/*
1970 * set_dumpable converts traditional three-value dumpable to two flags and
1971 * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1972 * these bits are not changed atomically.  So get_dumpable can observe the
1973 * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1974 * return either old dumpable or new one by paying attention to the order of
1975 * modifying the bits.
1976 *
1977 * dumpable |   mm->flags (binary)
1978 * old  new | initial interim  final
1979 * ---------+-----------------------
1980 *  0    1  |   00      01      01
1981 *  0    2  |   00      10(*)   11
1982 *  1    0  |   01      00      00
1983 *  1    2  |   01      11      11
1984 *  2    0  |   11      10(*)   00
1985 *  2    1  |   11      11      01
1986 *
1987 * (*) get_dumpable regards interim value of 10 as 11.
1988 */
1989void set_dumpable(struct mm_struct *mm, int value)
1990{
1991        switch (value) {
1992        case 0:
1993                clear_bit(MMF_DUMPABLE, &mm->flags);
1994                smp_wmb();
1995                clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1996                break;
1997        case 1:
1998                set_bit(MMF_DUMPABLE, &mm->flags);
1999                smp_wmb();
2000                clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2001                break;
2002        case 2:
2003                set_bit(MMF_DUMP_SECURELY, &mm->flags);
2004                smp_wmb();
2005                set_bit(MMF_DUMPABLE, &mm->flags);
2006                break;
2007        }
2008}
2009
2010static int __get_dumpable(unsigned long mm_flags)
2011{
2012        int ret;
2013
2014        ret = mm_flags & MMF_DUMPABLE_MASK;
2015        return (ret >= 2) ? 2 : ret;
2016}
2017
2018int get_dumpable(struct mm_struct *mm)
2019{
2020        return __get_dumpable(mm->flags);
2021}
2022
2023static void wait_for_dump_helpers(struct file *file)
2024{
2025        struct pipe_inode_info *pipe;
2026
2027        pipe = file->f_path.dentry->d_inode->i_pipe;
2028
2029        pipe_lock(pipe);
2030        pipe->readers++;
2031        pipe->writers--;
2032
2033        while ((pipe->readers > 1) && (!signal_pending(current))) {
2034                wake_up_interruptible_sync(&pipe->wait);
2035                kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
2036                pipe_wait(pipe);
2037        }
2038
2039        pipe->readers--;
2040        pipe->writers++;
2041        pipe_unlock(pipe);
2042
2043}
2044
2045
2046/*
2047 * umh_pipe_setup
2048 * helper function to customize the process used
2049 * to collect the core in userspace.  Specifically
2050 * it sets up a pipe and installs it as fd 0 (stdin)
2051 * for the process.  Returns 0 on success, or
2052 * PTR_ERR on failure.
2053 * Note that it also sets the core limit to 1.  This
2054 * is a special value that we use to trap recursive
2055 * core dumps
2056 */
2057static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2058{
2059        struct file *rp, *wp;
2060        struct fdtable *fdt;
2061        struct coredump_params *cp = (struct coredump_params *)info->data;
2062        struct files_struct *cf = current->files;
2063
2064        wp = create_write_pipe(0);
2065        if (IS_ERR(wp))
2066                return PTR_ERR(wp);
2067
2068        rp = create_read_pipe(wp, 0);
2069        if (IS_ERR(rp)) {
2070                free_write_pipe(wp);
2071                return PTR_ERR(rp);
2072        }
2073
2074        cp->file = wp;
2075
2076        sys_close(0);
2077        fd_install(0, rp);
2078        spin_lock(&cf->file_lock);
2079        fdt = files_fdtable(cf);
2080        FD_SET(0, fdt->open_fds);
2081        FD_CLR(0, fdt->close_on_exec);
2082        spin_unlock(&cf->file_lock);
2083
2084        /* and disallow core files too */
2085        current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2086
2087        return 0;
2088}
2089
2090void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2091{
2092        struct core_state core_state;
2093        struct core_name cn;
2094        struct mm_struct *mm = current->mm;
2095        struct linux_binfmt * binfmt;
2096        const struct cred *old_cred;
2097        struct cred *cred;
2098        int retval = 0;
2099        int flag = 0;
2100        int ispipe;
2101        static atomic_t core_dump_count = ATOMIC_INIT(0);
2102        struct coredump_params cprm = {
2103                .signr = signr,
2104                .regs = regs,
2105                .limit = rlimit(RLIMIT_CORE),
2106                /*
2107                 * We must use the same mm->flags while dumping core to avoid
2108                 * inconsistency of bit flags, since this flag is not protected
2109                 * by any locks.
2110                 */
2111                .mm_flags = mm->flags,
2112        };
2113
2114        audit_core_dumps(signr);
2115
2116        binfmt = mm->binfmt;
2117        if (!binfmt || !binfmt->core_dump)
2118                goto fail;
2119        if (!__get_dumpable(cprm.mm_flags))
2120                goto fail;
2121
2122        cred = prepare_creds();
2123        if (!cred)
2124                goto fail;
2125        /*
2126         *      We cannot trust fsuid as being the "true" uid of the
2127         *      process nor do we know its entire history. We only know it
2128         *      was tainted so we dump it as root in mode 2.
2129         */
2130        if (__get_dumpable(cprm.mm_flags) == 2) {
2131                /* Setuid core dump mode */
2132                flag = O_EXCL;          /* Stop rewrite attacks */
2133                cred->fsuid = 0;        /* Dump root private */
2134        }
2135
2136        retval = coredump_wait(exit_code, &core_state);
2137        if (retval < 0)
2138                goto fail_creds;
2139
2140        old_cred = override_creds(cred);
2141
2142        /*
2143         * Clear any false indication of pending signals that might
2144         * be seen by the filesystem code called to write the core file.
2145         */
2146        clear_thread_flag(TIF_SIGPENDING);
2147
2148        ispipe = format_corename(&cn, signr);
2149
2150        if (ispipe) {
2151                int dump_count;
2152                char **helper_argv;
2153
2154                if (ispipe < 0) {
2155                        printk(KERN_WARNING "format_corename failed\n");
2156                        printk(KERN_WARNING "Aborting core\n");
2157                        goto fail_corename;
2158                }
2159
2160                if (cprm.limit == 1) {
2161                        /*
2162                         * Normally core limits are irrelevant to pipes, since
2163                         * we're not writing to the file system, but we use
2164                         * cprm.limit of 1 here as a speacial value. Any
2165                         * non-1 limit gets set to RLIM_INFINITY below, but
2166                         * a limit of 0 skips the dump.  This is a consistent
2167                         * way to catch recursive crashes.  We can still crash
2168                         * if the core_pattern binary sets RLIM_CORE =  !1
2169                         * but it runs as root, and can do lots of stupid things
2170                         * Note that we use task_tgid_vnr here to grab the pid
2171                         * of the process group leader.  That way we get the
2172                         * right pid if a thread in a multi-threaded
2173                         * core_pattern process dies.
2174                         */
2175                        printk(KERN_WARNING
2176                                "Process %d(%s) has RLIMIT_CORE set to 1\n",
2177                                task_tgid_vnr(current), current->comm);
2178                        printk(KERN_WARNING "Aborting core\n");
2179                        goto fail_unlock;
2180                }
2181                cprm.limit = RLIM_INFINITY;
2182
2183                dump_count = atomic_inc_return(&core_dump_count);
2184                if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2185                        printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2186                               task_tgid_vnr(current), current->comm);
2187                        printk(KERN_WARNING "Skipping core dump\n");
2188                        goto fail_dropcount;
2189                }
2190
2191                helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2192                if (!helper_argv) {
2193                        printk(KERN_WARNING "%s failed to allocate memory\n",
2194                               __func__);
2195                        goto fail_dropcount;
2196                }
2197
2198                retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2199                                        NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2200                                        NULL, &cprm);
2201                argv_free(helper_argv);
2202                if (retval) {
2203                        printk(KERN_INFO "Core dump to %s pipe failed\n",
2204                               cn.corename);
2205                        goto close_fail;
2206                }
2207        } else {
2208                struct inode *inode;
2209
2210                if (cprm.limit < binfmt->min_coredump)
2211                        goto fail_unlock;
2212
2213                cprm.file = filp_open(cn.corename,
2214                                 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2215                                 0600);
2216                if (IS_ERR(cprm.file))
2217                        goto fail_unlock;
2218
2219                inode = cprm.file->f_path.dentry->d_inode;
2220                if (inode->i_nlink > 1)
2221                        goto close_fail;
2222                if (d_unhashed(cprm.file->f_path.dentry))
2223                        goto close_fail;
2224                /*
2225                 * AK: actually i see no reason to not allow this for named
2226                 * pipes etc, but keep the previous behaviour for now.
2227                 */
2228                if (!S_ISREG(inode->i_mode))
2229                        goto close_fail;
2230                /*
2231                 * Dont allow local users get cute and trick others to coredump
2232                 * into their pre-created files.
2233                 */
2234                if (inode->i_uid != current_fsuid())
2235                        goto close_fail;
2236                if (!cprm.file->f_op || !cprm.file->f_op->write)
2237                        goto close_fail;
2238                if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2239                        goto close_fail;
2240        }
2241
2242        retval = binfmt->core_dump(&cprm);
2243        if (retval)
2244                current->signal->group_exit_code |= 0x80;
2245
2246        if (ispipe && core_pipe_limit)
2247                wait_for_dump_helpers(cprm.file);
2248close_fail:
2249        if (cprm.file)
2250                filp_close(cprm.file, NULL);
2251fail_dropcount:
2252        if (ispipe)
2253                atomic_dec(&core_dump_count);
2254fail_unlock:
2255        kfree(cn.corename);
2256fail_corename:
2257        coredump_finish(mm);
2258        revert_creds(old_cred);
2259fail_creds:
2260        put_cred(cred);
2261fail:
2262        return;
2263}
2264
2265/*
2266 * Core dumping helper functions.  These are the only things you should
2267 * do on a core-file: use only these functions to write out all the
2268 * necessary info.
2269 */
2270int dump_write(struct file *file, const void *addr, int nr)
2271{
2272        return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2273}
2274EXPORT_SYMBOL(dump_write);
2275
2276int dump_seek(struct file *file, loff_t off)
2277{
2278        int ret = 1;
2279
2280        if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2281                if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2282                        return 0;
2283        } else {
2284                char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2285
2286                if (!buf)
2287                        return 0;
2288                while (off > 0) {
2289                        unsigned long n = off;
2290
2291                        if (n > PAGE_SIZE)
2292                                n = PAGE_SIZE;
2293                        if (!dump_write(file, buf, n)) {
2294                                ret = 0;
2295                                break;
2296                        }
2297                        off -= n;
2298                }
2299                free_page((unsigned long)buf);
2300        }
2301        return ret;
2302}
2303EXPORT_SYMBOL(dump_seek);
2304
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