Adding breaktrace & disabling timer migration
[kvmfornfv.git] / kernel / 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 #include <linux/sched.h>
37 #include <linux/fs.h>
38 #include <linux/path.h>
39
40 #include <asm/uaccess.h>
41 #include <asm/mmu_context.h>
42 #include <asm/tlb.h>
43 #include <asm/exec.h>
44
45 #include <trace/events/task.h>
46 #include "internal.h"
47
48 #include <trace/events/sched.h>
49
50 int core_uses_pid;
51 unsigned int core_pipe_limit;
52 char core_pattern[CORENAME_MAX_SIZE] = "core";
53 static int core_name_size = CORENAME_MAX_SIZE;
54
55 struct core_name {
56         char *corename;
57         int used, size;
58 };
59
60 /* The maximal length of core_pattern is also specified in sysctl.c */
61
62 static int expand_corename(struct core_name *cn, int size)
63 {
64         char *corename = krealloc(cn->corename, size, GFP_KERNEL);
65
66         if (!corename)
67                 return -ENOMEM;
68
69         if (size > core_name_size) /* racy but harmless */
70                 core_name_size = size;
71
72         cn->size = ksize(corename);
73         cn->corename = corename;
74         return 0;
75 }
76
77 static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt,
78                                      va_list arg)
79 {
80         int free, need;
81         va_list arg_copy;
82
83 again:
84         free = cn->size - cn->used;
85
86         va_copy(arg_copy, arg);
87         need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy);
88         va_end(arg_copy);
89
90         if (need < free) {
91                 cn->used += need;
92                 return 0;
93         }
94
95         if (!expand_corename(cn, cn->size + need - free + 1))
96                 goto again;
97
98         return -ENOMEM;
99 }
100
101 static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...)
102 {
103         va_list arg;
104         int ret;
105
106         va_start(arg, fmt);
107         ret = cn_vprintf(cn, fmt, arg);
108         va_end(arg);
109
110         return ret;
111 }
112
113 static __printf(2, 3)
114 int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
115 {
116         int cur = cn->used;
117         va_list arg;
118         int ret;
119
120         va_start(arg, fmt);
121         ret = cn_vprintf(cn, fmt, arg);
122         va_end(arg);
123
124         for (; cur < cn->used; ++cur) {
125                 if (cn->corename[cur] == '/')
126                         cn->corename[cur] = '!';
127         }
128         return ret;
129 }
130
131 static int cn_print_exe_file(struct core_name *cn)
132 {
133         struct file *exe_file;
134         char *pathbuf, *path;
135         int ret;
136
137         exe_file = get_mm_exe_file(current->mm);
138         if (!exe_file)
139                 return cn_esc_printf(cn, "%s (path unknown)", current->comm);
140
141         pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
142         if (!pathbuf) {
143                 ret = -ENOMEM;
144                 goto put_exe_file;
145         }
146
147         path = file_path(exe_file, pathbuf, PATH_MAX);
148         if (IS_ERR(path)) {
149                 ret = PTR_ERR(path);
150                 goto free_buf;
151         }
152
153         ret = cn_esc_printf(cn, "%s", path);
154
155 free_buf:
156         kfree(pathbuf);
157 put_exe_file:
158         fput(exe_file);
159         return ret;
160 }
161
162 /* format_corename will inspect the pattern parameter, and output a
163  * name into corename, which must have space for at least
164  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
165  */
166 static int format_corename(struct core_name *cn, struct coredump_params *cprm)
167 {
168         const struct cred *cred = current_cred();
169         const char *pat_ptr = core_pattern;
170         int ispipe = (*pat_ptr == '|');
171         int pid_in_pattern = 0;
172         int err = 0;
173
174         cn->used = 0;
175         cn->corename = NULL;
176         if (expand_corename(cn, core_name_size))
177                 return -ENOMEM;
178         cn->corename[0] = '\0';
179
180         if (ispipe)
181                 ++pat_ptr;
182
183         /* Repeat as long as we have more pattern to process and more output
184            space */
185         while (*pat_ptr) {
186                 if (*pat_ptr != '%') {
187                         err = cn_printf(cn, "%c", *pat_ptr++);
188                 } else {
189                         switch (*++pat_ptr) {
190                         /* single % at the end, drop that */
191                         case 0:
192                                 goto out;
193                         /* Double percent, output one percent */
194                         case '%':
195                                 err = cn_printf(cn, "%c", '%');
196                                 break;
197                         /* pid */
198                         case 'p':
199                                 pid_in_pattern = 1;
200                                 err = cn_printf(cn, "%d",
201                                               task_tgid_vnr(current));
202                                 break;
203                         /* global pid */
204                         case 'P':
205                                 err = cn_printf(cn, "%d",
206                                               task_tgid_nr(current));
207                                 break;
208                         case 'i':
209                                 err = cn_printf(cn, "%d",
210                                               task_pid_vnr(current));
211                                 break;
212                         case 'I':
213                                 err = cn_printf(cn, "%d",
214                                               task_pid_nr(current));
215                                 break;
216                         /* uid */
217                         case 'u':
218                                 err = cn_printf(cn, "%u",
219                                                 from_kuid(&init_user_ns,
220                                                           cred->uid));
221                                 break;
222                         /* gid */
223                         case 'g':
224                                 err = cn_printf(cn, "%u",
225                                                 from_kgid(&init_user_ns,
226                                                           cred->gid));
227                                 break;
228                         case 'd':
229                                 err = cn_printf(cn, "%d",
230                                         __get_dumpable(cprm->mm_flags));
231                                 break;
232                         /* signal that caused the coredump */
233                         case 's':
234                                 err = cn_printf(cn, "%d",
235                                                 cprm->siginfo->si_signo);
236                                 break;
237                         /* UNIX time of coredump */
238                         case 't': {
239                                 struct timeval tv;
240                                 do_gettimeofday(&tv);
241                                 err = cn_printf(cn, "%lu", tv.tv_sec);
242                                 break;
243                         }
244                         /* hostname */
245                         case 'h':
246                                 down_read(&uts_sem);
247                                 err = cn_esc_printf(cn, "%s",
248                                               utsname()->nodename);
249                                 up_read(&uts_sem);
250                                 break;
251                         /* executable */
252                         case 'e':
253                                 err = cn_esc_printf(cn, "%s", current->comm);
254                                 break;
255                         case 'E':
256                                 err = cn_print_exe_file(cn);
257                                 break;
258                         /* core limit size */
259                         case 'c':
260                                 err = cn_printf(cn, "%lu",
261                                               rlimit(RLIMIT_CORE));
262                                 break;
263                         default:
264                                 break;
265                         }
266                         ++pat_ptr;
267                 }
268
269                 if (err)
270                         return err;
271         }
272
273 out:
274         /* Backward compatibility with core_uses_pid:
275          *
276          * If core_pattern does not include a %p (as is the default)
277          * and core_uses_pid is set, then .%pid will be appended to
278          * the filename. Do not do this for piped commands. */
279         if (!ispipe && !pid_in_pattern && core_uses_pid) {
280                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
281                 if (err)
282                         return err;
283         }
284         return ispipe;
285 }
286
287 static int zap_process(struct task_struct *start, int exit_code, int flags)
288 {
289         struct task_struct *t;
290         int nr = 0;
291
292         /* ignore all signals except SIGKILL, see prepare_signal() */
293         start->signal->flags = SIGNAL_GROUP_COREDUMP | flags;
294         start->signal->group_exit_code = exit_code;
295         start->signal->group_stop_count = 0;
296
297         for_each_thread(start, t) {
298                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
299                 if (t != current && t->mm) {
300                         sigaddset(&t->pending.signal, SIGKILL);
301                         signal_wake_up(t, 1);
302                         nr++;
303                 }
304         }
305
306         return nr;
307 }
308
309 static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
310                         struct core_state *core_state, int exit_code)
311 {
312         struct task_struct *g, *p;
313         unsigned long flags;
314         int nr = -EAGAIN;
315
316         spin_lock_irq(&tsk->sighand->siglock);
317         if (!signal_group_exit(tsk->signal)) {
318                 mm->core_state = core_state;
319                 tsk->signal->group_exit_task = tsk;
320                 nr = zap_process(tsk, exit_code, 0);
321                 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
322         }
323         spin_unlock_irq(&tsk->sighand->siglock);
324         if (unlikely(nr < 0))
325                 return nr;
326
327         tsk->flags |= PF_DUMPCORE;
328         if (atomic_read(&mm->mm_users) == nr + 1)
329                 goto done;
330         /*
331          * We should find and kill all tasks which use this mm, and we should
332          * count them correctly into ->nr_threads. We don't take tasklist
333          * lock, but this is safe wrt:
334          *
335          * fork:
336          *      None of sub-threads can fork after zap_process(leader). All
337          *      processes which were created before this point should be
338          *      visible to zap_threads() because copy_process() adds the new
339          *      process to the tail of init_task.tasks list, and lock/unlock
340          *      of ->siglock provides a memory barrier.
341          *
342          * do_exit:
343          *      The caller holds mm->mmap_sem. This means that the task which
344          *      uses this mm can't pass exit_mm(), so it can't exit or clear
345          *      its ->mm.
346          *
347          * de_thread:
348          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
349          *      we must see either old or new leader, this does not matter.
350          *      However, it can change p->sighand, so lock_task_sighand(p)
351          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
352          *      it can't fail.
353          *
354          *      Note also that "g" can be the old leader with ->mm == NULL
355          *      and already unhashed and thus removed from ->thread_group.
356          *      This is OK, __unhash_process()->list_del_rcu() does not
357          *      clear the ->next pointer, we will find the new leader via
358          *      next_thread().
359          */
360         rcu_read_lock();
361         for_each_process(g) {
362                 if (g == tsk->group_leader)
363                         continue;
364                 if (g->flags & PF_KTHREAD)
365                         continue;
366
367                 for_each_thread(g, p) {
368                         if (unlikely(!p->mm))
369                                 continue;
370                         if (unlikely(p->mm == mm)) {
371                                 lock_task_sighand(p, &flags);
372                                 nr += zap_process(p, exit_code,
373                                                         SIGNAL_GROUP_EXIT);
374                                 unlock_task_sighand(p, &flags);
375                         }
376                         break;
377                 }
378         }
379         rcu_read_unlock();
380 done:
381         atomic_set(&core_state->nr_threads, nr);
382         return nr;
383 }
384
385 static int coredump_wait(int exit_code, struct core_state *core_state)
386 {
387         struct task_struct *tsk = current;
388         struct mm_struct *mm = tsk->mm;
389         int core_waiters = -EBUSY;
390
391         init_completion(&core_state->startup);
392         core_state->dumper.task = tsk;
393         core_state->dumper.next = NULL;
394
395         down_write(&mm->mmap_sem);
396         if (!mm->core_state)
397                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
398         up_write(&mm->mmap_sem);
399
400         if (core_waiters > 0) {
401                 struct core_thread *ptr;
402
403                 freezer_do_not_count();
404                 wait_for_completion(&core_state->startup);
405                 freezer_count();
406                 /*
407                  * Wait for all the threads to become inactive, so that
408                  * all the thread context (extended register state, like
409                  * fpu etc) gets copied to the memory.
410                  */
411                 ptr = core_state->dumper.next;
412                 while (ptr != NULL) {
413                         wait_task_inactive(ptr->task, 0);
414                         ptr = ptr->next;
415                 }
416         }
417
418         return core_waiters;
419 }
420
421 static void coredump_finish(struct mm_struct *mm, bool core_dumped)
422 {
423         struct core_thread *curr, *next;
424         struct task_struct *task;
425
426         spin_lock_irq(&current->sighand->siglock);
427         if (core_dumped && !__fatal_signal_pending(current))
428                 current->signal->group_exit_code |= 0x80;
429         current->signal->group_exit_task = NULL;
430         current->signal->flags = SIGNAL_GROUP_EXIT;
431         spin_unlock_irq(&current->sighand->siglock);
432
433         next = mm->core_state->dumper.next;
434         while ((curr = next) != NULL) {
435                 next = curr->next;
436                 task = curr->task;
437                 /*
438                  * see exit_mm(), curr->task must not see
439                  * ->task == NULL before we read ->next.
440                  */
441                 smp_mb();
442                 curr->task = NULL;
443                 wake_up_process(task);
444         }
445
446         mm->core_state = NULL;
447 }
448
449 static bool dump_interrupted(void)
450 {
451         /*
452          * SIGKILL or freezing() interrupt the coredumping. Perhaps we
453          * can do try_to_freeze() and check __fatal_signal_pending(),
454          * but then we need to teach dump_write() to restart and clear
455          * TIF_SIGPENDING.
456          */
457         return signal_pending(current);
458 }
459
460 static void wait_for_dump_helpers(struct file *file)
461 {
462         struct pipe_inode_info *pipe = file->private_data;
463
464         pipe_lock(pipe);
465         pipe->readers++;
466         pipe->writers--;
467         wake_up_interruptible_sync(&pipe->wait);
468         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
469         pipe_unlock(pipe);
470
471         /*
472          * We actually want wait_event_freezable() but then we need
473          * to clear TIF_SIGPENDING and improve dump_interrupted().
474          */
475         wait_event_interruptible(pipe->wait, pipe->readers == 1);
476
477         pipe_lock(pipe);
478         pipe->readers--;
479         pipe->writers++;
480         pipe_unlock(pipe);
481 }
482
483 /*
484  * umh_pipe_setup
485  * helper function to customize the process used
486  * to collect the core in userspace.  Specifically
487  * it sets up a pipe and installs it as fd 0 (stdin)
488  * for the process.  Returns 0 on success, or
489  * PTR_ERR on failure.
490  * Note that it also sets the core limit to 1.  This
491  * is a special value that we use to trap recursive
492  * core dumps
493  */
494 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
495 {
496         struct file *files[2];
497         struct coredump_params *cp = (struct coredump_params *)info->data;
498         int err = create_pipe_files(files, 0);
499         if (err)
500                 return err;
501
502         cp->file = files[1];
503
504         err = replace_fd(0, files[0], 0);
505         fput(files[0]);
506         /* and disallow core files too */
507         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
508
509         return err;
510 }
511
512 void do_coredump(const siginfo_t *siginfo)
513 {
514         struct core_state core_state;
515         struct core_name cn;
516         struct mm_struct *mm = current->mm;
517         struct linux_binfmt * binfmt;
518         const struct cred *old_cred;
519         struct cred *cred;
520         int retval = 0;
521         int ispipe;
522         struct files_struct *displaced;
523         /* require nonrelative corefile path and be extra careful */
524         bool need_suid_safe = false;
525         bool core_dumped = false;
526         static atomic_t core_dump_count = ATOMIC_INIT(0);
527         struct coredump_params cprm = {
528                 .siginfo = siginfo,
529                 .regs = signal_pt_regs(),
530                 .limit = rlimit(RLIMIT_CORE),
531                 /*
532                  * We must use the same mm->flags while dumping core to avoid
533                  * inconsistency of bit flags, since this flag is not protected
534                  * by any locks.
535                  */
536                 .mm_flags = mm->flags,
537         };
538
539         audit_core_dumps(siginfo->si_signo);
540
541         binfmt = mm->binfmt;
542         if (!binfmt || !binfmt->core_dump)
543                 goto fail;
544         if (!__get_dumpable(cprm.mm_flags))
545                 goto fail;
546
547         cred = prepare_creds();
548         if (!cred)
549                 goto fail;
550         /*
551          * We cannot trust fsuid as being the "true" uid of the process
552          * nor do we know its entire history. We only know it was tainted
553          * so we dump it as root in mode 2, and only into a controlled
554          * environment (pipe handler or fully qualified path).
555          */
556         if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
557                 /* Setuid core dump mode */
558                 cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
559                 need_suid_safe = true;
560         }
561
562         retval = coredump_wait(siginfo->si_signo, &core_state);
563         if (retval < 0)
564                 goto fail_creds;
565
566         old_cred = override_creds(cred);
567
568         ispipe = format_corename(&cn, &cprm);
569
570         if (ispipe) {
571                 int dump_count;
572                 char **helper_argv;
573                 struct subprocess_info *sub_info;
574
575                 if (ispipe < 0) {
576                         printk(KERN_WARNING "format_corename failed\n");
577                         printk(KERN_WARNING "Aborting core\n");
578                         goto fail_unlock;
579                 }
580
581                 if (cprm.limit == 1) {
582                         /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
583                          *
584                          * Normally core limits are irrelevant to pipes, since
585                          * we're not writing to the file system, but we use
586                          * cprm.limit of 1 here as a special value, this is a
587                          * consistent way to catch recursive crashes.
588                          * We can still crash if the core_pattern binary sets
589                          * RLIM_CORE = !1, but it runs as root, and can do
590                          * lots of stupid things.
591                          *
592                          * Note that we use task_tgid_vnr here to grab the pid
593                          * of the process group leader.  That way we get the
594                          * right pid if a thread in a multi-threaded
595                          * core_pattern process dies.
596                          */
597                         printk(KERN_WARNING
598                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
599                                 task_tgid_vnr(current), current->comm);
600                         printk(KERN_WARNING "Aborting core\n");
601                         goto fail_unlock;
602                 }
603                 cprm.limit = RLIM_INFINITY;
604
605                 dump_count = atomic_inc_return(&core_dump_count);
606                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
607                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
608                                task_tgid_vnr(current), current->comm);
609                         printk(KERN_WARNING "Skipping core dump\n");
610                         goto fail_dropcount;
611                 }
612
613                 helper_argv = argv_split(GFP_KERNEL, cn.corename, NULL);
614                 if (!helper_argv) {
615                         printk(KERN_WARNING "%s failed to allocate memory\n",
616                                __func__);
617                         goto fail_dropcount;
618                 }
619
620                 retval = -ENOMEM;
621                 sub_info = call_usermodehelper_setup(helper_argv[0],
622                                                 helper_argv, NULL, GFP_KERNEL,
623                                                 umh_pipe_setup, NULL, &cprm);
624                 if (sub_info)
625                         retval = call_usermodehelper_exec(sub_info,
626                                                           UMH_WAIT_EXEC);
627
628                 argv_free(helper_argv);
629                 if (retval) {
630                         printk(KERN_INFO "Core dump to |%s pipe failed\n",
631                                cn.corename);
632                         goto close_fail;
633                 }
634         } else {
635                 struct inode *inode;
636                 int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
637                                  O_LARGEFILE | O_EXCL;
638
639                 if (cprm.limit < binfmt->min_coredump)
640                         goto fail_unlock;
641
642                 if (need_suid_safe && cn.corename[0] != '/') {
643                         printk(KERN_WARNING "Pid %d(%s) can only dump core "\
644                                 "to fully qualified path!\n",
645                                 task_tgid_vnr(current), current->comm);
646                         printk(KERN_WARNING "Skipping core dump\n");
647                         goto fail_unlock;
648                 }
649
650                 /*
651                  * Unlink the file if it exists unless this is a SUID
652                  * binary - in that case, we're running around with root
653                  * privs and don't want to unlink another user's coredump.
654                  */
655                 if (!need_suid_safe) {
656                         mm_segment_t old_fs;
657
658                         old_fs = get_fs();
659                         set_fs(KERNEL_DS);
660                         /*
661                          * If it doesn't exist, that's fine. If there's some
662                          * other problem, we'll catch it at the filp_open().
663                          */
664                         (void) sys_unlink((const char __user *)cn.corename);
665                         set_fs(old_fs);
666                 }
667
668                 /*
669                  * There is a race between unlinking and creating the
670                  * file, but if that causes an EEXIST here, that's
671                  * fine - another process raced with us while creating
672                  * the corefile, and the other process won. To userspace,
673                  * what matters is that at least one of the two processes
674                  * writes its coredump successfully, not which one.
675                  */
676                 if (need_suid_safe) {
677                         /*
678                          * Using user namespaces, normal user tasks can change
679                          * their current->fs->root to point to arbitrary
680                          * directories. Since the intention of the "only dump
681                          * with a fully qualified path" rule is to control where
682                          * coredumps may be placed using root privileges,
683                          * current->fs->root must not be used. Instead, use the
684                          * root directory of init_task.
685                          */
686                         struct path root;
687
688                         task_lock(&init_task);
689                         get_fs_root(init_task.fs, &root);
690                         task_unlock(&init_task);
691                         cprm.file = file_open_root(root.dentry, root.mnt,
692                                 cn.corename, open_flags, 0600);
693                         path_put(&root);
694                 } else {
695                         cprm.file = filp_open(cn.corename, open_flags, 0600);
696                 }
697                 if (IS_ERR(cprm.file))
698                         goto fail_unlock;
699
700                 inode = file_inode(cprm.file);
701                 if (inode->i_nlink > 1)
702                         goto close_fail;
703                 if (d_unhashed(cprm.file->f_path.dentry))
704                         goto close_fail;
705                 /*
706                  * AK: actually i see no reason to not allow this for named
707                  * pipes etc, but keep the previous behaviour for now.
708                  */
709                 if (!S_ISREG(inode->i_mode))
710                         goto close_fail;
711                 /*
712                  * Don't dump core if the filesystem changed owner or mode
713                  * of the file during file creation. This is an issue when
714                  * a process dumps core while its cwd is e.g. on a vfat
715                  * filesystem.
716                  */
717                 if (!uid_eq(inode->i_uid, current_fsuid()))
718                         goto close_fail;
719                 if ((inode->i_mode & 0677) != 0600)
720                         goto close_fail;
721                 if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
722                         goto close_fail;
723                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
724                         goto close_fail;
725         }
726
727         /* get us an unshared descriptor table; almost always a no-op */
728         retval = unshare_files(&displaced);
729         if (retval)
730                 goto close_fail;
731         if (displaced)
732                 put_files_struct(displaced);
733         if (!dump_interrupted()) {
734                 file_start_write(cprm.file);
735                 core_dumped = binfmt->core_dump(&cprm);
736                 file_end_write(cprm.file);
737         }
738         if (ispipe && core_pipe_limit)
739                 wait_for_dump_helpers(cprm.file);
740 close_fail:
741         if (cprm.file)
742                 filp_close(cprm.file, NULL);
743 fail_dropcount:
744         if (ispipe)
745                 atomic_dec(&core_dump_count);
746 fail_unlock:
747         kfree(cn.corename);
748         coredump_finish(mm, core_dumped);
749         revert_creds(old_cred);
750 fail_creds:
751         put_cred(cred);
752 fail:
753         return;
754 }
755
756 /*
757  * Core dumping helper functions.  These are the only things you should
758  * do on a core-file: use only these functions to write out all the
759  * necessary info.
760  */
761 int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
762 {
763         struct file *file = cprm->file;
764         loff_t pos = file->f_pos;
765         ssize_t n;
766         if (cprm->written + nr > cprm->limit)
767                 return 0;
768         while (nr) {
769                 if (dump_interrupted())
770                         return 0;
771                 n = __kernel_write(file, addr, nr, &pos);
772                 if (n <= 0)
773                         return 0;
774                 file->f_pos = pos;
775                 cprm->written += n;
776                 nr -= n;
777         }
778         return 1;
779 }
780 EXPORT_SYMBOL(dump_emit);
781
782 int dump_skip(struct coredump_params *cprm, size_t nr)
783 {
784         static char zeroes[PAGE_SIZE];
785         struct file *file = cprm->file;
786         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
787                 if (cprm->written + nr > cprm->limit)
788                         return 0;
789                 if (dump_interrupted() ||
790                     file->f_op->llseek(file, nr, SEEK_CUR) < 0)
791                         return 0;
792                 cprm->written += nr;
793                 return 1;
794         } else {
795                 while (nr > PAGE_SIZE) {
796                         if (!dump_emit(cprm, zeroes, PAGE_SIZE))
797                                 return 0;
798                         nr -= PAGE_SIZE;
799                 }
800                 return dump_emit(cprm, zeroes, nr);
801         }
802 }
803 EXPORT_SYMBOL(dump_skip);
804
805 int dump_align(struct coredump_params *cprm, int align)
806 {
807         unsigned mod = cprm->written & (align - 1);
808         if (align & (align - 1))
809                 return 0;
810         return mod ? dump_skip(cprm, align - mod) : 1;
811 }
812 EXPORT_SYMBOL(dump_align);