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