fs/coredump.c

   1 #include <linux/slab.h>
   2 #include <linux/file.h>
   3 #include <linux/fdtable.h>
   4 #include <linux/freezer.h>
   5 #include <linux/mm.h>
   6 #include <linux/stat.h>
   7 #include <linux/fcntl.h>
   8 #include <linux/swap.h>
   9 #include <linux/string.h>
  10 #include <linux/init.h>
  11 #include <linux/pagemap.h>
  12 #include <linux/perf_event.h>
  13 #include <linux/highmem.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/key.h>
  16 #include <linux/personality.h>
  17 #include <linux/binfmts.h>
  18 #include <linux/coredump.h>
  19 #include <linux/utsname.h>
  20 #include <linux/pid_namespace.h>
  21 #include <linux/module.h>
  22 #include <linux/namei.h>
  23 #include <linux/mount.h>
  24 #include <linux/security.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/tsacct_kern.h>
  27 #include <linux/cn_proc.h>
  28 #include <linux/audit.h>
  29 #include <linux/tracehook.h>
  30 #include <linux/kmod.h>
  31 #include <linux/fsnotify.h>
  32 #include <linux/fs_struct.h>
  33 #include <linux/pipe_fs_i.h>
  34 #include <linux/oom.h>
  35 #include <linux/compat.h>
  36
  37 #include <asm/uaccess.h>
  38 #include <asm/mmu_context.h>
  39 #include <asm/tlb.h>
  40 #include <asm/exec.h>
  41
  42 #include <trace/events/task.h>
  43 #include "internal.h"
  44 #include "coredump.h"
  45
  46 #include <trace/events/sched.h>
  47
  48 int core_uses_pid;
  49 char core_pattern[CORENAME_MAX_SIZE] = "core";
  50 unsigned int core_pipe_limit;
  51
  52 struct core_name {
  53         char *corename;
  54         int used, size;
  55 };
  56 static atomic_t call_count = ATOMIC_INIT(1);
  57
  58 /* The maximal length of core_pattern is also specified in sysctl.c */
  59
  60 static int expand_corename(struct core_name *cn)
  61 {
  62         char *old_corename = cn->corename;
  63
  64         cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
  65         cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
  66
  67         if (!cn->corename) {
  68                 kfree(old_corename);
  69                 return -ENOMEM;
  70         }
  71
  72         return 0;
  73 }
  74
  75 static int cn_printf(struct core_name *cn, const char *fmt, ...)
  76 {
  77         char *cur;
  78         int need;
  79         int ret;
  80         va_list arg;
  81
  82         va_start(arg, fmt);
  83         need = vsnprintf(NULL, 0, fmt, arg);
  84         va_end(arg);
  85
  86         if (likely(need < cn->size - cn->used - 1))
  87                 goto out_printf;
  88
  89         ret = expand_corename(cn);
  90         if (ret)
  91                 goto expand_fail;
  92
  93 out_printf:
  94         cur = cn->corename + cn->used;
  95         va_start(arg, fmt);
  96         vsnprintf(cur, need + 1, fmt, arg);
  97         va_end(arg);
  98         cn->used += need;
  99         return 0;
 100
 101 expand_fail:
 102         return ret;
 103 }
 104
 105 static void cn_escape(char *str)
 106 {
 107         for (; *str; str++)
 108                 if (*str == '/')
 109                         *str = '!';
 110 }
 111
 112 static int cn_print_exe_file(struct core_name *cn)
 113 {
 114         struct file *exe_file;
 115         char *pathbuf, *path;
 116         int ret;
 117
 118         exe_file = get_mm_exe_file(current->mm);
 119         if (!exe_file) {
 120                 char *commstart = cn->corename + cn->used;
 121                 ret = cn_printf(cn, "%s (path unknown)", current->comm);
 122                 cn_escape(commstart);
 123                 return ret;
 124         }
 125
 126         pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
 127         if (!pathbuf) {
 128                 ret = -ENOMEM;
 129                 goto put_exe_file;
 130         }
 131
 132         path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
 133         if (IS_ERR(path)) {
 134                 ret = PTR_ERR(path);
 135                 goto free_buf;
 136         }
 137
 138         cn_escape(path);
 139
 140         ret = cn_printf(cn, "%s", path);
 141
 142 free_buf:
 143         kfree(pathbuf);
 144 put_exe_file:
 145         fput(exe_file);
 146         return ret;
 147 }
 148
 149 /* format_corename will inspect the pattern parameter, and output a
 150  * name into corename, which must have space for at least
 151  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
 152  */
 153 static int format_corename(struct core_name *cn, struct coredump_params *cprm)
 154 {
 155         const struct cred *cred = current_cred();
 156         const char *pat_ptr = core_pattern;
 157         int ispipe = (*pat_ptr == '|');
 158         int pid_in_pattern = 0;
 159         int err = 0;
 160
 161         cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
 162         cn->corename = kmalloc(cn->size, GFP_KERNEL);
 163         cn->used = 0;
 164
 165         if (!cn->corename)
 166                 return -ENOMEM;
 167
 168         /* Repeat as long as we have more pattern to process and more output
 169            space */
 170         while (*pat_ptr) {
 171                 if (*pat_ptr != '%') {
 172                         if (*pat_ptr == 0)
 173                                 goto out;
 174                         err = cn_printf(cn, "%c", *pat_ptr++);
 175                 } else {
 176                         switch (*++pat_ptr) {
 177                         /* single % at the end, drop that */
 178                         case 0:
 179                                 goto out;
 180                         /* Double percent, output one percent */
 181                         case '%':
 182                                 err = cn_printf(cn, "%c", '%');
 183                                 break;
 184                         /* pid */
 185                         case 'p':
 186                                 pid_in_pattern = 1;
 187                                 err = cn_printf(cn, "%d",
 188                                               task_tgid_vnr(current));
 189                                 break;
 190                         /* uid */
 191                         case 'u':
 192                                 err = cn_printf(cn, "%d", cred->uid);
 193                                 break;
 194                         /* gid */
 195                         case 'g':
 196                                 err = cn_printf(cn, "%d", cred->gid);
 197                                 break;
 198                         case 'd':
 199                                 err = cn_printf(cn, "%d",
 200                                         __get_dumpable(cprm->mm_flags));
 201                                 break;
 202                         /* signal that caused the coredump */
 203                         case 's':
 204                                 err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
 205                                 break;
 206                         /* UNIX time of coredump */
 207                         case 't': {
 208                                 struct timeval tv;
 209                                 do_gettimeofday(&tv);
 210                                 err = cn_printf(cn, "%lu", tv.tv_sec);
 211                                 break;
 212                         }
 213                         /* hostname */
 214                         case 'h': {
 215                                 char *namestart = cn->corename + cn->used;
 216                                 down_read(&uts_sem);
 217                                 err = cn_printf(cn, "%s",
 218                                               utsname()->nodename);
 219                                 up_read(&uts_sem);
 220                                 cn_escape(namestart);
 221                                 break;
 222                         }
 223                         /* executable */
 224                         case 'e': {
 225                                 char *commstart = cn->corename + cn->used;
 226                                 err = cn_printf(cn, "%s", current->comm);
 227                                 cn_escape(commstart);
 228                                 break;
 229                         }
 230                         case 'E':
 231                                 err = cn_print_exe_file(cn);
 232                                 break;
 233                         /* core limit size */
 234                         case 'c':
 235                                 err = cn_printf(cn, "%lu",
 236                                               rlimit(RLIMIT_CORE));
 237                                 break;
 238                         default:
 239                                 break;
 240                         }
 241                         ++pat_ptr;
 242                 }
 243
 244                 if (err)
 245                         return err;
 246         }
 247
 248         /* Backward compatibility with core_uses_pid:
 249          *
 250          * If core_pattern does not include a %p (as is the default)
 251          * and core_uses_pid is set, then .%pid will be appended to
 252          * the filename. Do not do this for piped commands. */
 253         if (!ispipe && !pid_in_pattern && core_uses_pid) {
 254                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
 255                 if (err)
 256                         return err;
 257         }
 258 out:
 259         return ispipe;
 260 }
 261
 262 static int zap_process(struct task_struct *start, int exit_code)
 263 {
 264         struct task_struct *t;
 265         int nr = 0;
 266
 267         start->signal->group_exit_code = exit_code;
 268         start->signal->group_stop_count = 0;
 269
 270         t = start;
 271         do {
 272                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
 273                 if (t != current && t->mm) {
 274                         sigaddset(&t->pending.signal, SIGKILL);
 275                         signal_wake_up(t, 1);
 276                         nr++;
 277                 }
 278         } while_each_thread(start, t);
 279
 280         return nr;
 281 }
 282
 283 static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
 284                         struct core_state *core_state, int exit_code)
 285 {
 286         struct task_struct *g, *p;
 287         unsigned long flags;
 288         int nr = -EAGAIN;
 289
 290         spin_lock_irq(&tsk->sighand->siglock);
 291         if (!signal_group_exit(tsk->signal)) {
 292                 mm->core_state = core_state;
 293                 nr = zap_process(tsk, exit_code);
 294                 tsk->signal->group_exit_task = tsk;
 295                 /* ignore all signals except SIGKILL, see prepare_signal() */
 296                 tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
 297                 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
 298         }
 299         spin_unlock_irq(&tsk->sighand->siglock);
 300         if (unlikely(nr < 0))
 301                 return nr;
 302
 303         tsk->flags |= PF_DUMPCORE;
 304         if (atomic_read(&mm->mm_users) == nr + 1)
 305                 goto done;
 306         /*
 307          * We should find and kill all tasks which use this mm, and we should
 308          * count them correctly into ->nr_threads. We don't take tasklist
 309          * lock, but this is safe wrt:
 310          *
 311          * fork:
 312          *      None of sub-threads can fork after zap_process(leader). All
 313          *      processes which were created before this point should be
 314          *      visible to zap_threads() because copy_process() adds the new
 315          *      process to the tail of init_task.tasks list, and lock/unlock
 316          *      of ->siglock provides a memory barrier.
 317          *
 318          * do_exit:
 319          *      The caller holds mm->mmap_sem. This means that the task which
 320          *      uses this mm can't pass exit_mm(), so it can't exit or clear
 321          *      its ->mm.
 322          *
 323          * de_thread:
 324          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
 325          *      we must see either old or new leader, this does not matter.
 326          *      However, it can change p->sighand, so lock_task_sighand(p)
 327          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
 328          *      it can't fail.
 329          *
 330          *      Note also that "g" can be the old leader with ->mm == NULL
 331          *      and already unhashed and thus removed from ->thread_group.
 332          *      This is OK, __unhash_process()->list_del_rcu() does not
 333          *      clear the ->next pointer, we will find the new leader via
 334          *      next_thread().
 335          */
 336         rcu_read_lock();
 337         for_each_process(g) {
 338                 if (g == tsk->group_leader)
 339                         continue;
 340                 if (g->flags & PF_KTHREAD)
 341                         continue;
 342                 p = g;
 343                 do {
 344                         if (p->mm) {
 345                                 if (unlikely(p->mm == mm)) {
 346                                         lock_task_sighand(p, &flags);
 347                                         nr += zap_process(p, exit_code);
 348                                         p->signal->flags = SIGNAL_GROUP_EXIT;
 349                                         unlock_task_sighand(p, &flags);
 350                                 }
 351                                 break;
 352                         }
 353                 } while_each_thread(g, p);
 354         }
 355         rcu_read_unlock();
 356 done:
 357         atomic_set(&core_state->nr_threads, nr);
 358         return nr;
 359 }
 360
 361 static int coredump_wait(int exit_code, struct core_state *core_state)
 362 {
 363         struct task_struct *tsk = current;
 364         struct mm_struct *mm = tsk->mm;
 365         int core_waiters = -EBUSY;
 366
 367         init_completion(&core_state->startup);
 368         core_state->dumper.task = tsk;
 369         core_state->dumper.next = NULL;
 370
 371         down_write(&mm->mmap_sem);
 372         if (!mm->core_state)
 373                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
 374         up_write(&mm->mmap_sem);
 375
 376         if (core_waiters > 0) {
 377                 struct core_thread *ptr;
 378
 379                 freezer_do_not_count();
 380                 wait_for_completion(&core_state->startup);
 381                 freezer_count();
 382                 /*
 383                  * Wait for all the threads to become inactive, so that
 384                  * all the thread context (extended register state, like
 385                  * fpu etc) gets copied to the memory.
 386                  */
 387                 ptr = core_state->dumper.next;
 388                 while (ptr != NULL) {
 389                         wait_task_inactive(ptr->task, 0);
 390                         ptr = ptr->next;
 391                 }
 392         }
 393
 394         return core_waiters;
 395 }
 396
 397 static void coredump_finish(struct mm_struct *mm, bool core_dumped)
 398 {
 399         struct core_thread *curr, *next;
 400         struct task_struct *task;
 401
 402         spin_lock_irq(&current->sighand->siglock);
 403         if (core_dumped && !__fatal_signal_pending(current))
 404                 current->signal->group_exit_code |= 0x80;
 405         current->signal->group_exit_task = NULL;
 406         current->signal->flags = SIGNAL_GROUP_EXIT;
 407         spin_unlock_irq(&current->sighand->siglock);
 408
 409         next = mm->core_state->dumper.next;
 410         while ((curr = next) != NULL) {
 411                 next = curr->next;
 412                 task = curr->task;
 413                 /*
 414                  * see exit_mm(), curr->task must not see
 415                  * ->task == NULL before we read ->next.
 416                  */
 417                 smp_mb();
 418                 curr->task = NULL;
 419                 wake_up_process(task);
 420         }
 421
 422         mm->core_state = NULL;
 423 }
 424
 425 static bool dump_interrupted(void)
 426 {
 427         /*
 428          * SIGKILL or freezing() interrupt the coredumping. Perhaps we
 429          * can do try_to_freeze() and check __fatal_signal_pending(),
 430          * but then we need to teach dump_write() to restart and clear
 431          * TIF_SIGPENDING.
 432          */
 433         return signal_pending(current);
 434 }
 435
 436 static void wait_for_dump_helpers(struct file *file)
 437 {
 438         struct pipe_inode_info *pipe = file->private_data;
 439
 440         pipe_lock(pipe);
 441         pipe->readers++;
 442         pipe->writers--;
 443         wake_up_interruptible_sync(&pipe->wait);
 444         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
 445         pipe_unlock(pipe);
 446
 447         /*
 448          * We actually want wait_event_freezable() but then we need
 449          * to clear TIF_SIGPENDING and improve dump_interrupted().
 450          */
 451         wait_event_interruptible(pipe->wait, pipe->readers == 1);
 452
 453         pipe_lock(pipe);
 454         pipe->readers--;
 455         pipe->writers++;
 456         pipe_unlock(pipe);
 457 }
 458
 459 /*
 460  * umh_pipe_setup
 461  * helper function to customize the process used
 462  * to collect the core in userspace.  Specifically
 463  * it sets up a pipe and installs it as fd 0 (stdin)
 464  * for the process.  Returns 0 on success, or
 465  * PTR_ERR on failure.
 466  * Note that it also sets the core limit to 1.  This
 467  * is a special value that we use to trap recursive
 468  * core dumps
 469  */
 470 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
 471 {
 472         struct file *files[2];
 473         struct coredump_params *cp = (struct coredump_params *)info->data;
 474         int err = create_pipe_files(files, 0);
 475         if (err)
 476                 return err;
 477
 478         cp->file = files[1];
 479
 480         err = replace_fd(0, files[0], 0);
 481         fput(files[0]);
 482         /* and disallow core files too */
 483         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
 484
 485         return err;
 486 }
 487
 488 void do_coredump(siginfo_t *siginfo)
 489 {
 490         struct core_state core_state;
 491         struct core_name cn;
 492         struct mm_struct *mm = current->mm;
 493         struct linux_binfmt * binfmt;
 494         const struct cred *old_cred;
 495         struct cred *cred;
 496         int retval = 0;
 497         int ispipe;
 498         struct files_struct *displaced;
 499         /* require nonrelative corefile path and be extra careful */
 500         bool need_suid_safe = false;
 501         bool core_dumped = false;
 502         static atomic_t core_dump_count = ATOMIC_INIT(0);
 503         struct coredump_params cprm = {
 504                 .siginfo = siginfo,
 505                 .regs = signal_pt_regs(),
 506                 .limit = rlimit(RLIMIT_CORE),
 507                 /*
 508                  * We must use the same mm->flags while dumping core to avoid
 509                  * inconsistency of bit flags, since this flag is not protected
 510                  * by any locks.
 511                  */
 512                 .mm_flags = mm->flags,
 513         };
 514
 515         audit_core_dumps(siginfo->si_signo);
 516
 517         binfmt = mm->binfmt;
 518         if (!binfmt || !binfmt->core_dump) {
 519                 printk(KERN_WARNING "Skip process %d(%s) core dump(!binfmt?%s)\n",
 520                         task_tgid_vnr(current), current->comm, (!binfmt) ? "yes":"no");
 521                 goto fail;
 522         }
 523         if (!__get_dumpable(cprm.mm_flags)) {
 524                 printk(KERN_WARNING "Skip process %d(%s) core dump(mm_flags:%x)\n",
 525                         task_tgid_vnr(current), current->comm, (unsigned int)cprm.mm_flags);
 526                 goto fail;
 527         }
 528
 529         cred = prepare_creds();
 530         if (!cred) {
 531                 printk(KERN_WARNING "Skip process %d(%s) core dump(prepare_creds failed)\n",
 532                         task_tgid_vnr(current), current->comm);
 533                 goto fail;
 534         }
 535         /*
 536          * We cannot trust fsuid as being the "true" uid of the process
 537          * nor do we know its entire history. We only know it was tainted
 538          * so we dump it as root in mode 2, and only into a controlled
 539          * environment (pipe handler or fully qualified path).
 540          */
 541         if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
 542                 /* Setuid core dump mode */
 543                 cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
 544                 need_suid_safe = true;
 545         }
 546
 547         retval = coredump_wait(siginfo->si_signo, &core_state);
 548         if (retval < 0)
 549                 goto fail_creds;
 550
 551         old_cred = override_creds(cred);
 552
 553         ispipe = format_corename(&cn, &cprm);
 554
 555         if (ispipe) {
 556                 int dump_count;
 557                 char **helper_argv;
 558                 struct subprocess_info *sub_info;
 559
 560                 if (ispipe < 0) {
 561                         printk(KERN_WARNING "format_corename failed\n");
 562                         printk(KERN_WARNING "Aborting core\n");
 563                         goto fail_corename;
 564                 }
 565
 566                 if (cprm.limit == 1) {
 567                         /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
 568                          *
 569                          * Normally core limits are irrelevant to pipes, since
 570                          * we're not writing to the file system, but we use
 571                          * cprm.limit of 1 here as a speacial value, this is a
 572                          * consistent way to catch recursive crashes.
 573                          * We can still crash if the core_pattern binary sets
 574                          * RLIM_CORE = !1, but it runs as root, and can do
 575                          * lots of stupid things.
 576                          *
 577                          * Note that we use task_tgid_vnr here to grab the pid
 578                          * of the process group leader.  That way we get the
 579                          * right pid if a thread in a multi-threaded
 580                          * core_pattern process dies.
 581                          */
 582                         printk(KERN_WARNING
 583                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
 584                                 task_tgid_vnr(current), current->comm);
 585                         printk(KERN_WARNING "Aborting core\n");
 586                         goto fail_unlock;
 587                 }
 588                 cprm.limit = RLIM_INFINITY;
 589
 590                 dump_count = atomic_inc_return(&core_dump_count);
 591                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
 592                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
 593                                task_tgid_vnr(current), current->comm);
 594                         printk(KERN_WARNING "Skipping core dump\n");
 595                         goto fail_dropcount;
 596                 }
 597
 598                 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
 599                 if (!helper_argv) {
 600                         printk(KERN_WARNING "%s failed to allocate memory\n",
 601                                __func__);
 602                         goto fail_dropcount;
 603                 }
 604
 605                 retval = -ENOMEM;
 606                 sub_info = call_usermodehelper_setup(helper_argv[0],
 607                                                 helper_argv, NULL, GFP_KERNEL,
 608                                                 umh_pipe_setup, NULL, &cprm);
 609                 if (sub_info)
 610                         retval = call_usermodehelper_exec(sub_info,
 611                                                           UMH_WAIT_EXEC);
 612
 613                 argv_free(helper_argv);
 614                 if (retval) {
 615                         printk(KERN_INFO "Core dump to %s pipe failed\n",
 616                                cn.corename);
 617                         goto close_fail;
 618                 }
 619         } else {
 620                 struct inode *inode;
 621
 622                 if (cprm.limit < binfmt->min_coredump)
 623                         goto fail_unlock;
 624
 625                 if (need_suid_safe && cn.corename[0] != '/') {
 626                         printk(KERN_WARNING "Pid %d(%s) can only dump core "\
 627                                 "to fully qualified path!\n",
 628                                 task_tgid_vnr(current), current->comm);
 629                         printk(KERN_WARNING "Skipping core dump\n");
 630                         goto fail_unlock;
 631                 }
 632
 633                 /*
 634                  * Unlink the file if it exists unless this is a SUID
 635                  * binary - in that case, we're running around with root
 636                  * privs and don't want to unlink another user's coredump.
 637                  */
 638                 if (!need_suid_safe) {
 639                         mm_segment_t old_fs;
 640
 641                         old_fs = get_fs();
 642                         set_fs(KERNEL_DS);
 643                         /*
 644                          * If it doesn't exist, that's fine. If there's some
 645                          * other problem, we'll catch it at the filp_open().
 646                          */
 647                         (void) sys_unlink((const char __user *)cn.corename);
 648                         set_fs(old_fs);
 649                 }
 650
 651                 /*
 652                  * There is a race between unlinking and creating the
 653                  * file, but if that causes an EEXIST here, that's
 654                  * fine - another process raced with us while creating
 655                  * the corefile, and the other process won. To userspace,
 656                  * what matters is that at least one of the two processes
 657                  * writes its coredump successfully, not which one.
 658                  */
 659                 cprm.file = filp_open(cn.corename,
 660                                  O_CREAT | 2 | O_NOFOLLOW |
 661                                  O_LARGEFILE | O_EXCL,
 662                                  0600);
 663                 if (IS_ERR(cprm.file))
 664                         goto fail_unlock;
 665
 666                 inode = file_inode(cprm.file);
 667                 if (inode->i_nlink > 1)
 668                         goto close_fail;
 669                 if (d_unhashed(cprm.file->f_path.dentry))
 670                         goto close_fail;
 671                 /*
 672                  * AK: actually i see no reason to not allow this for named
 673                  * pipes etc, but keep the previous behaviour for now.
 674                  */
 675                 if (!S_ISREG(inode->i_mode))
 676                         goto close_fail;
 677                 /*
 678                  * Dont allow local users get cute and trick others to coredump
 679                  * into their pre-created files.
 680                  */
 681                 if (!uid_eq(inode->i_uid, current_fsuid()))
 682                         goto close_fail;
 683                 if (!cprm.file->f_op || !cprm.file->f_op->write)
 684                         goto close_fail;
 685                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
 686                         goto close_fail;
 687         }
 688
 689         /* get us an unshared descriptor table; almost always a no-op */
 690         retval = unshare_files(&displaced);
 691         if (retval)
 692                 goto close_fail;
 693         if (displaced)
 694                 put_files_struct(displaced);
 695         if (!dump_interrupted()) {
 696                 file_start_write(cprm.file);
 697                 printk(KERN_WARNING "before %d core dump\n", current->pid);
 698                 core_dumped = binfmt->core_dump(&cprm);
 699                 file_end_write(cprm.file);
 700         }
 701         else
 702                 printk(KERN_WARNING "before %d core dump interrupted error\n", current->pid);
 703         if (ispipe && core_pipe_limit)
 704                 wait_for_dump_helpers(cprm.file);
 705 close_fail:
 706         if (cprm.file)
 707                 filp_close(cprm.file, NULL);
 708 fail_dropcount:
 709         if (ispipe)
 710                 atomic_dec(&core_dump_count);
 711 fail_unlock:
 712         kfree(cn.corename);
 713 fail_corename:
 714         coredump_finish(mm, core_dumped);
 715         revert_creds(old_cred);
 716 fail_creds:
 717         put_cred(cred);
 718 fail:
 719         return;
 720 }
 721
 722 /*
 723  * Core dumping helper functions.  These are the only things you should
 724  * do on a core-file: use only these functions to write out all the
 725  * necessary info.
 726  */
 727 int dump_write(struct file *file, const void *addr, int nr)
 728 {
 729         if (!dump_interrupted()) {
 730                 if (access_ok(VERIFY_READ, addr, nr)) {
 731                         int pipe_ret = file->f_op->write(file, addr, nr, &file->f_pos);
 732                         if (pipe_ret == nr) {
 733                                 return 1;
 734                         }
 735                         if (pipe_ret == -ERESTARTSYS) {
 736                         }
 737                         else {
 738                                 printk(KERN_WARNING "coredump(%d): pipe dump write error nr:%d, ret:%d\n", current->pid, nr, pipe_ret);
 739                         }
 740                 }
 741                 else {
 742                         printk(KERN_WARNING "coredump(%d): access verify error\n", current->pid);
 743                 }
 744         }
 745         else {
 746                 printk(KERN_WARNING "coredump(%d): interrupted error\n", current->pid);
 747         }
 748         return 0;
 749 }
 750 EXPORT_SYMBOL(dump_write);
 751
 752 int dump_seek(struct file *file, loff_t off)
 753 {
 754         int ret = 1;
 755
 756         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
 757                 if (dump_interrupted() ||
 758                     file->f_op->llseek(file, off, SEEK_CUR) < 0)
 759                         return 0;
 760         } else {
 761                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
 762
 763                 if (!buf)
 764                         return 0;
 765                 while (off > 0) {
 766                         unsigned long n = off;
 767
 768                         if (n > PAGE_SIZE)
 769                                 n = PAGE_SIZE;
 770                         if (!dump_write(file, buf, n)) {
 771                                 ret = 0;
 772                                 break;
 773                         }
 774                         off -= n;
 775                 }
 776                 free_page((unsigned long)buf);
 777         }
 778         return ret;
 779 }
 780 EXPORT_SYMBOL(dump_seek);