linux/fs/coredump.c
<<
>>
Prefs
   1#include <linux/slab.h>
   2#include <linux/file.h>
   3#include <linux/fdtable.h>
   4#include <linux/mm.h>
   5#include <linux/stat.h>
   6#include <linux/fcntl.h>
   7#include <linux/swap.h>
   8#include <linux/string.h>
   9#include <linux/init.h>
  10#include <linux/pagemap.h>
  11#include <linux/perf_event.h>
  12#include <linux/highmem.h>
  13#include <linux/spinlock.h>
  14#include <linux/key.h>
  15#include <linux/personality.h>
  16#include <linux/binfmts.h>
  17#include <linux/coredump.h>
  18#include <linux/utsname.h>
  19#include <linux/pid_namespace.h>
  20#include <linux/module.h>
  21#include <linux/namei.h>
  22#include <linux/mount.h>
  23#include <linux/security.h>
  24#include <linux/syscalls.h>
  25#include <linux/tsacct_kern.h>
  26#include <linux/cn_proc.h>
  27#include <linux/audit.h>
  28#include <linux/tracehook.h>
  29#include <linux/kmod.h>
  30#include <linux/fsnotify.h>
  31#include <linux/fs_struct.h>
  32#include <linux/pipe_fs_i.h>
  33#include <linux/oom.h>
  34#include <linux/compat.h>
  35
  36#include <asm/uaccess.h>
  37#include <asm/mmu_context.h>
  38#include <asm/tlb.h>
  39#include <asm/exec.h>
  40
  41#include <trace/events/task.h>
  42#include "internal.h"
  43#include "coredump.h"
  44
  45#include <trace/events/sched.h>
  46
  47int core_uses_pid;
  48unsigned int core_pipe_limit;
  49char core_pattern[CORENAME_MAX_SIZE] = "core";
  50static int core_name_size = CORENAME_MAX_SIZE;
  51
  52struct core_name {
  53        char *corename;
  54        int used, size;
  55};
  56
  57/* The maximal length of core_pattern is also specified in sysctl.c */
  58
  59static int expand_corename(struct core_name *cn, int size)
  60{
  61        char *corename = krealloc(cn->corename, size, GFP_KERNEL);
  62
  63        if (!corename)
  64                return -ENOMEM;
  65
  66        if (size > core_name_size) /* racy but harmless */
  67                core_name_size = size;
  68
  69        cn->size = ksize(corename);
  70        cn->corename = corename;
  71        return 0;
  72}
  73
  74static int cn_vprintf(struct core_name *cn, const char *fmt, va_list arg)
  75{
  76        int free, need;
  77
  78again:
  79        free = cn->size - cn->used;
  80        need = vsnprintf(cn->corename + cn->used, free, fmt, arg);
  81        if (need < free) {
  82                cn->used += need;
  83                return 0;
  84        }
  85
  86        if (!expand_corename(cn, cn->size + need - free + 1))
  87                goto again;
  88
  89        return -ENOMEM;
  90}
  91
  92static int cn_printf(struct core_name *cn, const char *fmt, ...)
  93{
  94        va_list arg;
  95        int ret;
  96
  97        va_start(arg, fmt);
  98        ret = cn_vprintf(cn, fmt, arg);
  99        va_end(arg);
 100
 101        return ret;
 102}
 103
 104static int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
 105{
 106        int cur = cn->used;
 107        va_list arg;
 108        int ret;
 109
 110        va_start(arg, fmt);
 111        ret = cn_vprintf(cn, fmt, arg);
 112        va_end(arg);
 113
 114        for (; cur < cn->used; ++cur) {
 115                if (cn->corename[cur] == '/')
 116                        cn->corename[cur] = '!';
 117        }
 118        return ret;
 119}
 120
 121static int cn_print_exe_file(struct core_name *cn)
 122{
 123        struct file *exe_file;
 124        char *pathbuf, *path;
 125        int ret;
 126
 127        exe_file = get_mm_exe_file(current->mm);
 128        if (!exe_file)
 129                return cn_esc_printf(cn, "%s (path unknown)", current->comm);
 130
 131        pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
 132        if (!pathbuf) {
 133                ret = -ENOMEM;
 134                goto put_exe_file;
 135        }
 136
 137        path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
 138        if (IS_ERR(path)) {
 139                ret = PTR_ERR(path);
 140                goto free_buf;
 141        }
 142
 143        ret = cn_esc_printf(cn, "%s", path);
 144
 145free_buf:
 146        kfree(pathbuf);
 147put_exe_file:
 148        fput(exe_file);
 149        return ret;
 150}
 151
 152/* format_corename will inspect the pattern parameter, and output a
 153 * name into corename, which must have space for at least
 154 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
 155 */
 156static int format_corename(struct core_name *cn, struct coredump_params *cprm)
 157{
 158        const struct cred *cred = current_cred();
 159        const char *pat_ptr = core_pattern;
 160        int ispipe = (*pat_ptr == '|');
 161        int pid_in_pattern = 0;
 162        int err = 0;
 163
 164        cn->used = 0;
 165        cn->corename = NULL;
 166        if (expand_corename(cn, core_name_size))
 167                return -ENOMEM;
 168        cn->corename[0] = '\0';
 169
 170        if (ispipe)
 171                ++pat_ptr;
 172
 173        /* Repeat as long as we have more pattern to process and more output
 174           space */
 175        while (*pat_ptr) {
 176                if (*pat_ptr != '%') {
 177                        err = cn_printf(cn, "%c", *pat_ptr++);
 178                } else {
 179                        switch (*++pat_ptr) {
 180                        /* single % at the end, drop that */
 181                        case 0:
 182                                goto out;
 183                        /* Double percent, output one percent */
 184                        case '%':
 185                                err = cn_printf(cn, "%c", '%');
 186                                break;
 187                        /* pid */
 188                        case 'p':
 189                                pid_in_pattern = 1;
 190                                err = cn_printf(cn, "%d",
 191                                              task_tgid_vnr(current));
 192                                break;
 193                        /* uid */
 194                        case 'u':
 195                                err = cn_printf(cn, "%d", cred->uid);
 196                                break;
 197                        /* gid */
 198                        case 'g':
 199                                err = cn_printf(cn, "%d", cred->gid);
 200                                break;
 201                        case 'd':
 202                                err = cn_printf(cn, "%d",
 203                                        __get_dumpable(cprm->mm_flags));
 204                                break;
 205                        /* signal that caused the coredump */
 206                        case 's':
 207                                err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
 208                                break;
 209                        /* UNIX time of coredump */
 210                        case 't': {
 211                                struct timeval tv;
 212                                do_gettimeofday(&tv);
 213                                err = cn_printf(cn, "%lu", tv.tv_sec);
 214                                break;
 215                        }
 216                        /* hostname */
 217                        case 'h':
 218                                down_read(&uts_sem);
 219                                err = cn_esc_printf(cn, "%s",
 220                                              utsname()->nodename);
 221                                up_read(&uts_sem);
 222                                break;
 223                        /* executable */
 224                        case 'e':
 225                                err = cn_esc_printf(cn, "%s", current->comm);
 226                                break;
 227                        case 'E':
 228                                err = cn_print_exe_file(cn);
 229                                break;
 230                        /* core limit size */
 231                        case 'c':
 232                                err = cn_printf(cn, "%lu",
 233                                              rlimit(RLIMIT_CORE));
 234                                break;
 235                        default:
 236                                break;
 237                        }
 238                        ++pat_ptr;
 239                }
 240
 241                if (err)
 242                        return err;
 243        }
 244
 245out:
 246        /* Backward compatibility with core_uses_pid:
 247         *
 248         * If core_pattern does not include a %p (as is the default)
 249         * and core_uses_pid is set, then .%pid will be appended to
 250         * the filename. Do not do this for piped commands. */
 251        if (!ispipe && !pid_in_pattern && core_uses_pid) {
 252                err = cn_printf(cn, ".%d", task_tgid_vnr(current));
 253                if (err)
 254                        return err;
 255        }
 256        return ispipe;
 257}
 258
 259static int zap_process(struct task_struct *start, int exit_code)
 260{
 261        struct task_struct *t;
 262        int nr = 0;
 263
 264        start->signal->group_exit_code = exit_code;
 265        start->signal->group_stop_count = 0;
 266
 267        t = start;
 268        do {
 269                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
 270                if (t != current && t->mm) {
 271                        sigaddset(&t->pending.signal, SIGKILL);
 272                        signal_wake_up(t, 1);
 273                        nr++;
 274                }
 275        } while_each_thread(start, t);
 276
 277        return nr;
 278}
 279
 280static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
 281                        struct core_state *core_state, int exit_code)
 282{
 283        struct task_struct *g, *p;
 284        unsigned long flags;
 285        int nr = -EAGAIN;
 286
 287        spin_lock_irq(&tsk->sighand->siglock);
 288        if (!signal_group_exit(tsk->signal)) {
 289                mm->core_state = core_state;
 290                nr = zap_process(tsk, exit_code);
 291                tsk->signal->group_exit_task = tsk;
 292                /* ignore all signals except SIGKILL, see prepare_signal() */
 293                tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
 294                clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
 295        }
 296        spin_unlock_irq(&tsk->sighand->siglock);
 297        if (unlikely(nr < 0))
 298                return nr;
 299
 300        tsk->flags = PF_DUMPCORE;
 301        if (atomic_read(&mm->mm_users) == nr + 1)
 302                goto done;
 303        /*
 304         * We should find and kill all tasks which use this mm, and we should
 305         * count them correctly into ->nr_threads. We don't take tasklist
 306         * lock, but this is safe wrt:
 307         *
 308         * fork:
 309         *      None of sub-threads can fork after zap_process(leader). All
 310         *      processes which were created before this point should be
 311         *      visible to zap_threads() because copy_process() adds the new
 312         *      process to the tail of init_task.tasks list, and lock/unlock
 313         *      of ->siglock provides a memory barrier.
 314         *
 315         * do_exit:
 316         *      The caller holds mm->mmap_sem. This means that the task which
 317         *      uses this mm can't pass exit_mm(), so it can't exit or clear
 318         *      its ->mm.
 319         *
 320         * de_thread:
 321         *      It does list_replace_rcu(&leader->tasks, &current->tasks),
 322         *      we must see either old or new leader, this does not matter.
 323         *      However, it can change p->sighand, so lock_task_sighand(p)
 324         *      must be used. Since p->mm != NULL and we hold ->mmap_sem
 325         *      it can't fail.
 326         *
 327         *      Note also that "g" can be the old leader with ->mm == NULL
 328         *      and already unhashed and thus removed from ->thread_group.
 329         *      This is OK, __unhash_process()->list_del_rcu() does not
 330         *      clear the ->next pointer, we will find the new leader via
 331         *      next_thread().
 332         */
 333        rcu_read_lock();
 334        for_each_process(g) {
 335                if (g == tsk->group_leader)
 336                        continue;
 337                if (g->flags & PF_KTHREAD)
 338                        continue;
 339                p = g;
 340                do {
 341                        if (p->mm) {
 342                                if (unlikely(p->mm == mm)) {
 343                                        lock_task_sighand(p, &flags);
 344                                        nr += zap_process(p, exit_code);
 345                                        p->signal->flags = SIGNAL_GROUP_EXIT;
 346                                        unlock_task_sighand(p, &flags);
 347                                }
 348                                break;
 349                        }
 350                } while_each_thread(g, p);
 351        }
 352        rcu_read_unlock();
 353done:
 354        atomic_set(&core_state->nr_threads, nr);
 355        return nr;
 356}
 357
 358static int coredump_wait(int exit_code, struct core_state *core_state)
 359{
 360        struct task_struct *tsk = current;
 361        struct mm_struct *mm = tsk->mm;
 362        int core_waiters = -EBUSY;
 363
 364        init_completion(&core_state->startup);
 365        core_state->dumper.task = tsk;
 366        core_state->dumper.next = NULL;
 367
 368        down_write(&mm->mmap_sem);
 369        if (!mm->core_state)
 370                core_waiters = zap_threads(tsk, mm, core_state, exit_code);
 371        up_write(&mm->mmap_sem);
 372
 373        if (core_waiters > 0) {
 374                struct core_thread *ptr;
 375
 376                wait_for_completion(&core_state->startup);
 377                /*
 378                 * Wait for all the threads to become inactive, so that
 379                 * all the thread context (extended register state, like
 380                 * fpu etc) gets copied to the memory.
 381                 */
 382                ptr = core_state->dumper.next;
 383                while (ptr != NULL) {
 384                        wait_task_inactive(ptr->task, 0);
 385                        ptr = ptr->next;
 386                }
 387        }
 388
 389        return core_waiters;
 390}
 391
 392static void coredump_finish(struct mm_struct *mm, bool core_dumped)
 393{
 394        struct core_thread *curr, *next;
 395        struct task_struct *task;
 396
 397        spin_lock_irq(&current->sighand->siglock);
 398        if (core_dumped && !__fatal_signal_pending(current))
 399                current->signal->group_exit_code |= 0x80;
 400        current->signal->group_exit_task = NULL;
 401        current->signal->flags = SIGNAL_GROUP_EXIT;
 402        spin_unlock_irq(&current->sighand->siglock);
 403
 404        next = mm->core_state->dumper.next;
 405        while ((curr = next) != NULL) {
 406                next = curr->next;
 407                task = curr->task;
 408                /*
 409                 * see exit_mm(), curr->task must not see
 410                 * ->task == NULL before we read ->next.
 411                 */
 412                smp_mb();
 413                curr->task = NULL;
 414                wake_up_process(task);
 415        }
 416
 417        mm->core_state = NULL;
 418}
 419
 420static bool dump_interrupted(void)
 421{
 422        /*
 423         * SIGKILL or freezing() interrupt the coredumping. Perhaps we
 424         * can do try_to_freeze() and check __fatal_signal_pending(),
 425         * but then we need to teach dump_write() to restart and clear
 426         * TIF_SIGPENDING.
 427         */
 428        return signal_pending(current);
 429}
 430
 431static void wait_for_dump_helpers(struct file *file)
 432{
 433        struct pipe_inode_info *pipe = file->private_data;
 434
 435        pipe_lock(pipe);
 436        pipe->readers++;
 437        pipe->writers--;
 438        wake_up_interruptible_sync(&pipe->wait);
 439        kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 440        pipe_unlock(pipe);
 441
 442        /*
 443         * We actually want wait_event_freezable() but then we need
 444         * to clear TIF_SIGPENDING and improve dump_interrupted().
 445         */
 446        wait_event_interruptible(pipe->wait, pipe->readers == 1);
 447
 448        pipe_lock(pipe);
 449        pipe->readers--;
 450        pipe->writers++;
 451        pipe_unlock(pipe);
 452}
 453
 454/*
 455 * umh_pipe_setup
 456 * helper function to customize the process used
 457 * to collect the core in userspace.  Specifically
 458 * it sets up a pipe and installs it as fd 0 (stdin)
 459 * for the process.  Returns 0 on success, or
 460 * PTR_ERR on failure.
 461 * Note that it also sets the core limit to 1.  This
 462 * is a special value that we use to trap recursive
 463 * core dumps
 464 */
 465static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
 466{
 467        struct file *files[2];
 468        struct coredump_params *cp = (struct coredump_params *)info->data;
 469        int err = create_pipe_files(files, 0);
 470        if (err)
 471                return err;
 472
 473        cp->file = files[1];
 474
 475        err = replace_fd(0, files[0], 0);
 476        fput(files[0]);
 477        /* and disallow core files too */
 478        current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
 479
 480        return err;
 481}
 482
 483void do_coredump(siginfo_t *siginfo)
 484{
 485        struct core_state core_state;
 486        struct core_name cn;
 487        struct mm_struct *mm = current->mm;
 488        struct linux_binfmt * binfmt;
 489        const struct cred *old_cred;
 490        struct cred *cred;
 491        int retval = 0;
 492        int flag = 0;
 493        int ispipe;
 494        struct files_struct *displaced;
 495        bool need_nonrelative = false;
 496        bool core_dumped = false;
 497        static atomic_t core_dump_count = ATOMIC_INIT(0);
 498        struct coredump_params cprm = {
 499                .siginfo = siginfo,
 500                .regs = signal_pt_regs(),
 501                .limit = rlimit(RLIMIT_CORE),
 502                /*
 503                 * We must use the same mm->flags while dumping core to avoid
 504                 * inconsistency of bit flags, since this flag is not protected
 505                 * by any locks.
 506                 */
 507                .mm_flags = mm->flags,
 508        };
 509
 510        audit_core_dumps(siginfo->si_signo);
 511
 512        binfmt = mm->binfmt;
 513        if (!binfmt || !binfmt->core_dump)
 514                goto fail;
 515        if (!__get_dumpable(cprm.mm_flags))
 516                goto fail;
 517
 518        cred = prepare_creds();
 519        if (!cred)
 520                goto fail;
 521        /*
 522         * We cannot trust fsuid as being the "true" uid of the process
 523         * nor do we know its entire history. We only know it was tainted
 524         * so we dump it as root in mode 2, and only into a controlled
 525         * environment (pipe handler or fully qualified path).
 526         */
 527        if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
 528                /* Setuid core dump mode */
 529                flag = O_EXCL;          /* Stop rewrite attacks */
 530                cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
 531                need_nonrelative = true;
 532        }
 533
 534        retval = coredump_wait(siginfo->si_signo, &core_state);
 535        if (retval < 0)
 536                goto fail_creds;
 537
 538        old_cred = override_creds(cred);
 539
 540        ispipe = format_corename(&cn, &cprm);
 541
 542        if (ispipe) {
 543                int dump_count;
 544                char **helper_argv;
 545                struct subprocess_info *sub_info;
 546
 547                if (ispipe < 0) {
 548                        printk(KERN_WARNING "format_corename failed\n");
 549                        printk(KERN_WARNING "Aborting core\n");
 550                        goto fail_unlock;
 551                }
 552
 553                if (cprm.limit == 1) {
 554                        /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
 555                         *
 556                         * Normally core limits are irrelevant to pipes, since
 557                         * we're not writing to the file system, but we use
 558                         * cprm.limit of 1 here as a speacial value, this is a
 559                         * consistent way to catch recursive crashes.
 560                         * We can still crash if the core_pattern binary sets
 561                         * RLIM_CORE = !1, but it runs as root, and can do
 562                         * lots of stupid things.
 563                         *
 564                         * Note that we use task_tgid_vnr here to grab the pid
 565                         * of the process group leader.  That way we get the
 566                         * right pid if a thread in a multi-threaded
 567                         * core_pattern process dies.
 568                         */
 569                        printk(KERN_WARNING
 570                                "Process %d(%s) has RLIMIT_CORE set to 1\n",
 571                                task_tgid_vnr(current), current->comm);
 572                        printk(KERN_WARNING "Aborting core\n");
 573                        goto fail_unlock;
 574                }
 575                cprm.limit = RLIM_INFINITY;
 576
 577                dump_count = atomic_inc_return(&core_dump_count);
 578                if (core_pipe_limit && (core_pipe_limit < dump_count)) {
 579                        printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
 580                               task_tgid_vnr(current), current->comm);
 581                        printk(KERN_WARNING "Skipping core dump\n");
 582                        goto fail_dropcount;
 583                }
 584
 585                helper_argv = argv_split(GFP_KERNEL, cn.corename, NULL);
 586                if (!helper_argv) {
 587                        printk(KERN_WARNING "%s failed to allocate memory\n",
 588                               __func__);
 589                        goto fail_dropcount;
 590                }
 591
 592                retval = -ENOMEM;
 593                sub_info = call_usermodehelper_setup(helper_argv[0],
 594                                                helper_argv, NULL, GFP_KERNEL,
 595                                                umh_pipe_setup, NULL, &cprm);
 596                if (sub_info)
 597                        retval = call_usermodehelper_exec(sub_info,
 598                                                          UMH_WAIT_EXEC);
 599
 600                argv_free(helper_argv);
 601                if (retval) {
 602                        printk(KERN_INFO "Core dump to |%s pipe failed\n",
 603                               cn.corename);
 604                        goto close_fail;
 605                }
 606        } else {
 607                struct inode *inode;
 608
 609                if (cprm.limit < binfmt->min_coredump)
 610                        goto fail_unlock;
 611
 612                if (need_nonrelative && cn.corename[0] != '/') {
 613                        printk(KERN_WARNING "Pid %d(%s) can only dump core "\
 614                                "to fully qualified path!\n",
 615                                task_tgid_vnr(current), current->comm);
 616                        printk(KERN_WARNING "Skipping core dump\n");
 617                        goto fail_unlock;
 618                }
 619
 620                cprm.file = filp_open(cn.corename,
 621                                 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
 622                                 0600);
 623                if (IS_ERR(cprm.file))
 624                        goto fail_unlock;
 625
 626                inode = file_inode(cprm.file);
 627                if (inode->i_nlink > 1)
 628                        goto close_fail;
 629                if (d_unhashed(cprm.file->f_path.dentry))
 630                        goto close_fail;
 631                /*
 632                 * AK: actually i see no reason to not allow this for named
 633                 * pipes etc, but keep the previous behaviour for now.
 634                 */
 635                if (!S_ISREG(inode->i_mode))
 636                        goto close_fail;
 637                /*
 638                 * Dont allow local users get cute and trick others to coredump
 639                 * into their pre-created files.
 640                 */
 641                if (!uid_eq(inode->i_uid, current_fsuid()))
 642                        goto close_fail;
 643                if (!cprm.file->f_op || !cprm.file->f_op->write)
 644                        goto close_fail;
 645                if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
 646                        goto close_fail;
 647        }
 648
 649        /* get us an unshared descriptor table; almost always a no-op */
 650        retval = unshare_files(&displaced);
 651        if (retval)
 652                goto close_fail;
 653        if (displaced)
 654                put_files_struct(displaced);
 655        if (!dump_interrupted()) {
 656                file_start_write(cprm.file);
 657                core_dumped = binfmt->core_dump(&cprm);
 658                file_end_write(cprm.file);
 659        }
 660        if (ispipe && core_pipe_limit)
 661                wait_for_dump_helpers(cprm.file);
 662close_fail:
 663        if (cprm.file)
 664                filp_close(cprm.file, NULL);
 665fail_dropcount:
 666        if (ispipe)
 667                atomic_dec(&core_dump_count);
 668fail_unlock:
 669        kfree(cn.corename);
 670        coredump_finish(mm, core_dumped);
 671        revert_creds(old_cred);
 672fail_creds:
 673        put_cred(cred);
 674fail:
 675        return;
 676}
 677
 678/*
 679 * Core dumping helper functions.  These are the only things you should
 680 * do on a core-file: use only these functions to write out all the
 681 * necessary info.
 682 */
 683int dump_write(struct file *file, const void *addr, int nr)
 684{
 685        return !dump_interrupted() &&
 686                access_ok(VERIFY_READ, addr, nr) &&
 687                file->f_op->write(file, addr, nr, &file->f_pos) == nr;
 688}
 689EXPORT_SYMBOL(dump_write);
 690
 691int dump_seek(struct file *file, loff_t off)
 692{
 693        int ret = 1;
 694
 695        if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
 696                if (dump_interrupted() ||
 697                    file->f_op->llseek(file, off, SEEK_CUR) < 0)
 698                        return 0;
 699        } else {
 700                char *buf = (char *)get_zeroed_page(GFP_KERNEL);
 701
 702                if (!buf)
 703                        return 0;
 704                while (off > 0) {
 705                        unsigned long n = off;
 706
 707                        if (n > PAGE_SIZE)
 708                                n = PAGE_SIZE;
 709                        if (!dump_write(file, buf, n)) {
 710                                ret = 0;
 711                                break;
 712                        }
 713                        off -= n;
 714                }
 715                free_page((unsigned long)buf);
 716        }
 717        return ret;
 718}
 719EXPORT_SYMBOL(dump_seek);
 720
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.