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#include <linux/timekeeping.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
50int core_uses_pid;
51unsigned int core_pipe_limit;
52char core_pattern[CORENAME_MAX_SIZE] = "core";
53static int core_name_size = CORENAME_MAX_SIZE;
54
55struct 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
62static 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
77static int cn_vprintf(struct core_name *cn, const char *fmt, 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 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 int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
113{
114	int cur = cn->used;
115	va_list arg;
116	int ret;
117
118	va_start(arg, fmt);
119	ret = cn_vprintf(cn, fmt, arg);
120	va_end(arg);
121
122	for (; cur < cn->used; ++cur) {
123		if (cn->corename[cur] == '/')
124			cn->corename[cur] = '!';
125	}
126	return ret;
127}
128
129static int cn_print_exe_file(struct core_name *cn)
130{
131	struct file *exe_file;
132	char *pathbuf, *path;
133	int ret;
134
135	exe_file = get_mm_exe_file(current->mm);
136	if (!exe_file)
137		return cn_esc_printf(cn, "%s (path unknown)", current->comm);
138
139	pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
140	if (!pathbuf) {
141		ret = -ENOMEM;
142		goto put_exe_file;
143	}
144
145	path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
146	if (IS_ERR(path)) {
147		ret = PTR_ERR(path);
148		goto free_buf;
149	}
150
151	ret = cn_esc_printf(cn, "%s", path);
152
153free_buf:
154	kfree(pathbuf);
155put_exe_file:
156	fput(exe_file);
157	return ret;
158}
159
160/* format_corename will inspect the pattern parameter, and output a
161 * name into corename, which must have space for at least
162 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
163 */
164static int format_corename(struct core_name *cn, struct coredump_params *cprm)
165{
166	const struct cred *cred = current_cred();
167	const char *pat_ptr = core_pattern;
168	int ispipe = (*pat_ptr == '|');
169	int pid_in_pattern = 0;
170	int err = 0;
171
172	cn->used = 0;
173	cn->corename = NULL;
174	if (expand_corename(cn, core_name_size))
175		return -ENOMEM;
176	cn->corename[0] = '\0';
177
178	if (ispipe)
179		++pat_ptr;
180
181	/* Repeat as long as we have more pattern to process and more output
182	   space */
183	while (*pat_ptr) {
184		if (*pat_ptr != '%') {
185			err = cn_printf(cn, "%c", *pat_ptr++);
186		} else {
187			switch (*++pat_ptr) {
188			/* single % at the end, drop that */
189			case 0:
190				goto out;
191			/* Double percent, output one percent */
192			case '%':
193				err = cn_printf(cn, "%c", '%');
194				break;
195			/* pid */
196			case 'p':
197				pid_in_pattern = 1;
198				err = cn_printf(cn, "%d",
199					      task_tgid_vnr(current));
200				break;
201			/* global pid */
202			case 'P':
203				err = cn_printf(cn, "%d",
204					      task_tgid_nr(current));
205				break;
206			case 'i':
207				err = cn_printf(cn, "%d",
208					      task_pid_vnr(current));
209				break;
210			case 'I':
211				err = cn_printf(cn, "%d",
212					      task_pid_nr(current));
213				break;
214			/* uid */
215			case 'u':
216				err = cn_printf(cn, "%d", cred->uid);
217				break;
218			/* gid */
219			case 'g':
220				err = cn_printf(cn, "%d", cred->gid);
221				break;
222			case 'd':
223				err = cn_printf(cn, "%d",
224					__get_dumpable(cprm->mm_flags));
225				break;
226			/* signal that caused the coredump */
227			case 's':
228				err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
229				break;
230			/* UNIX time of coredump */
231			case 't': {
232				time64_t time;
233
234				time = ktime_get_real_seconds();
235				err = cn_printf(cn, "%lld", time);
236				break;
237			}
238			/* hostname */
239			case 'h':
240				down_read(&uts_sem);
241				err = cn_esc_printf(cn, "%s",
242					      utsname()->nodename);
243				up_read(&uts_sem);
244				break;
245			/* executable */
246			case 'e':
247				err = cn_esc_printf(cn, "%s", current->comm);
248				break;
249			case 'E':
250				err = cn_print_exe_file(cn);
251				break;
252			/* core limit size */
253			case 'c':
254				err = cn_printf(cn, "%lu",
255					      rlimit(RLIMIT_CORE));
256				break;
257			default:
258				break;
259			}
260			++pat_ptr;
261		}
262
263		if (err)
264			return err;
265	}
266
267out:
268	/* Backward compatibility with core_uses_pid:
269	 *
270	 * If core_pattern does not include a %p (as is the default)
271	 * and core_uses_pid is set, then .%pid will be appended to
272	 * the filename. Do not do this for piped commands. */
273	if (!ispipe && !pid_in_pattern && core_uses_pid) {
274		err = cn_printf(cn, ".%d", task_tgid_vnr(current));
275		if (err)
276			return err;
277	}
278	return ispipe;
279}
280
281static int zap_process(struct task_struct *start, int exit_code)
282{
283	struct task_struct *t;
284	int nr = 0;
285
286	start->signal->group_exit_code = exit_code;
287	start->signal->group_stop_count = 0;
288
289	t = start;
290	do {
291		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
292		if (t != current && t->mm) {
293			sigaddset(&t->pending.signal, SIGKILL);
294			signal_wake_up(t, 1);
295			nr++;
296		}
297	} while_each_thread(start, t);
298
299	return nr;
300}
301
302static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
303			struct core_state *core_state, int exit_code)
304{
305	struct task_struct *g, *p;
306	unsigned long flags;
307	int nr = -EAGAIN;
308
309	spin_lock_irq(&tsk->sighand->siglock);
310	if (!signal_group_exit(tsk->signal)) {
311		mm->core_state = core_state;
312		nr = zap_process(tsk, exit_code);
313		tsk->signal->group_exit_task = tsk;
314		/* ignore all signals except SIGKILL, see prepare_signal() */
315		tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
316		clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
317	}
318	spin_unlock_irq(&tsk->sighand->siglock);
319	if (unlikely(nr < 0))
320		return nr;
321
322	tsk->flags |= PF_DUMPCORE;
323	if (atomic_read(&mm->mm_users) == nr + 1)
324		goto done;
325	/*
326	 * We should find and kill all tasks which use this mm, and we should
327	 * count them correctly into ->nr_threads. We don't take tasklist
328	 * lock, but this is safe wrt:
329	 *
330	 * fork:
331	 *	None of sub-threads can fork after zap_process(leader). All
332	 *	processes which were created before this point should be
333	 *	visible to zap_threads() because copy_process() adds the new
334	 *	process to the tail of init_task.tasks list, and lock/unlock
335	 *	of ->siglock provides a memory barrier.
336	 *
337	 * do_exit:
338	 *	The caller holds mm->mmap_sem. This means that the task which
339	 *	uses this mm can't pass exit_mm(), so it can't exit or clear
340	 *	its ->mm.
341	 *
342	 * de_thread:
343	 *	It does list_replace_rcu(&leader->tasks, &current->tasks),
344	 *	we must see either old or new leader, this does not matter.
345	 *	However, it can change p->sighand, so lock_task_sighand(p)
346	 *	must be used. Since p->mm != NULL and we hold ->mmap_sem
347	 *	it can't fail.
348	 *
349	 *	Note also that "g" can be the old leader with ->mm == NULL
350	 *	and already unhashed and thus removed from ->thread_group.
351	 *	This is OK, __unhash_process()->list_del_rcu() does not
352	 *	clear the ->next pointer, we will find the new leader via
353	 *	next_thread().
354	 */
355	rcu_read_lock();
356	for_each_process(g) {
357		if (g == tsk->group_leader)
358			continue;
359		if (g->flags & PF_KTHREAD)
360			continue;
361		p = g;
362		do {
363			if (p->mm) {
364				if (unlikely(p->mm == mm)) {
365					lock_task_sighand(p, &flags);
366					nr += zap_process(p, exit_code);
367					p->signal->flags = SIGNAL_GROUP_EXIT;
368					unlock_task_sighand(p, &flags);
369				}
370				break;
371			}
372		} while_each_thread(g, p);
373	}
374	rcu_read_unlock();
375done:
376	atomic_set(&core_state->nr_threads, nr);
377	return nr;
378}
379
380static int coredump_wait(int exit_code, struct core_state *core_state)
381{
382	struct task_struct *tsk = current;
383	struct mm_struct *mm = tsk->mm;
384	int core_waiters = -EBUSY;
385
386	init_completion(&core_state->startup);
387	core_state->dumper.task = tsk;
388	core_state->dumper.next = NULL;
389
390	down_write(&mm->mmap_sem);
391	if (!mm->core_state)
392		core_waiters = zap_threads(tsk, mm, core_state, exit_code);
393	up_write(&mm->mmap_sem);
394
395	if (core_waiters > 0) {
396		struct core_thread *ptr;
397
398		wait_for_completion(&core_state->startup);
399		/*
400		 * Wait for all the threads to become inactive, so that
401		 * all the thread context (extended register state, like
402		 * fpu etc) gets copied to the memory.
403		 */
404		ptr = core_state->dumper.next;
405		while (ptr != NULL) {
406			wait_task_inactive(ptr->task, 0);
407			ptr = ptr->next;
408		}
409	}
410
411	return core_waiters;
412}
413
414static void coredump_finish(struct mm_struct *mm, bool core_dumped)
415{
416	struct core_thread *curr, *next;
417	struct task_struct *task;
418
419	spin_lock_irq(&current->sighand->siglock);
420	if (core_dumped && !__fatal_signal_pending(current))
421		current->signal->group_exit_code |= 0x80;
422	current->signal->group_exit_task = NULL;
423	current->signal->flags = SIGNAL_GROUP_EXIT;
424	spin_unlock_irq(&current->sighand->siglock);
425
426	next = mm->core_state->dumper.next;
427	while ((curr = next) != NULL) {
428		next = curr->next;
429		task = curr->task;
430		/*
431		 * see exit_mm(), curr->task must not see
432		 * ->task == NULL before we read ->next.
433		 */
434		smp_mb();
435		curr->task = NULL;
436		wake_up_process(task);
437	}
438
439	mm->core_state = NULL;
440}
441
442static bool dump_interrupted(void)
443{
444	/*
445	 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
446	 * can do try_to_freeze() and check __fatal_signal_pending(),
447	 * but then we need to teach dump_write() to restart and clear
448	 * TIF_SIGPENDING.
449	 */
450	return signal_pending(current);
451}
452
453static void wait_for_dump_helpers(struct file *file)
454{
455	struct pipe_inode_info *pipe = file->private_data;
456
457	pipe_lock(pipe);
458	pipe->readers++;
459	pipe->writers--;
460	wake_up_interruptible_sync(&pipe->wait);
461	kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
462	pipe_unlock(pipe);
463
464	/*
465	 * We actually want wait_event_freezable() but then we need
466	 * to clear TIF_SIGPENDING and improve dump_interrupted().
467	 */
468	wait_event_interruptible(pipe->wait, pipe->readers == 1);
469
470	pipe_lock(pipe);
471	pipe->readers--;
472	pipe->writers++;
473	pipe_unlock(pipe);
474}
475
476/*
477 * umh_pipe_setup
478 * helper function to customize the process used
479 * to collect the core in userspace.  Specifically
480 * it sets up a pipe and installs it as fd 0 (stdin)
481 * for the process.  Returns 0 on success, or
482 * PTR_ERR on failure.
483 * Note that it also sets the core limit to 1.  This
484 * is a special value that we use to trap recursive
485 * core dumps
486 */
487static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
488{
489	struct file *files[2];
490	struct coredump_params *cp = (struct coredump_params *)info->data;
491	int err = create_pipe_files(files, 0);
492	if (err)
493		return err;
494
495	cp->file = files[1];
496
497	err = replace_fd(0, files[0], 0);
498	fput(files[0]);
499	/* and disallow core files too */
500	current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
501
502	return err;
503}
504
505void do_coredump(const siginfo_t *siginfo)
506{
507	struct core_state core_state;
508	struct core_name cn;
509	struct mm_struct *mm = current->mm;
510	struct linux_binfmt * binfmt;
511	const struct cred *old_cred;
512	struct cred *cred;
513	int retval = 0;
514	int ispipe;
515	struct files_struct *displaced;
516	/* require nonrelative corefile path and be extra careful */
517	bool need_suid_safe = false;
518	bool core_dumped = false;
519	static atomic_t core_dump_count = ATOMIC_INIT(0);
520	struct coredump_params cprm = {
521		.siginfo = siginfo,
522		.regs = signal_pt_regs(),
523		.limit = rlimit(RLIMIT_CORE),
524		/*
525		 * We must use the same mm->flags while dumping core to avoid
526		 * inconsistency of bit flags, since this flag is not protected
527		 * by any locks.
528		 */
529		.mm_flags = mm->flags,
530	};
531
532	audit_core_dumps(siginfo->si_signo);
533
534	binfmt = mm->binfmt;
535	if (!binfmt || !binfmt->core_dump)
536		goto fail;
537	if (!__get_dumpable(cprm.mm_flags))
538		goto fail;
539
540	cred = prepare_creds();
541	if (!cred)
542		goto fail;
543	/*
544	 * We cannot trust fsuid as being the "true" uid of the process
545	 * nor do we know its entire history. We only know it was tainted
546	 * so we dump it as root in mode 2, and only into a controlled
547	 * environment (pipe handler or fully qualified path).
548	 */
549	if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
550		/* Setuid core dump mode */
551		cred->fsuid = GLOBAL_ROOT_UID;	/* Dump root private */
552		need_suid_safe = true;
553	}
554
555	retval = coredump_wait(siginfo->si_signo, &core_state);
556	if (retval < 0)
557		goto fail_creds;
558
559	old_cred = override_creds(cred);
560
561	ispipe = format_corename(&cn, &cprm);
562
563	if (ispipe) {
564		int dump_count;
565		char **helper_argv;
566		struct subprocess_info *sub_info;
567
568		if (ispipe < 0) {
569			printk(KERN_WARNING "format_corename failed\n");
570			printk(KERN_WARNING "Aborting core\n");
571			goto fail_unlock;
572		}
573
574		if (cprm.limit == 1) {
575			/* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
576			 *
577			 * Normally core limits are irrelevant to pipes, since
578			 * we're not writing to the file system, but we use
579			 * cprm.limit of 1 here as a special value, this is a
580			 * consistent way to catch recursive crashes.
581			 * We can still crash if the core_pattern binary sets
582			 * RLIM_CORE = !1, but it runs as root, and can do
583			 * lots of stupid things.
584			 *
585			 * Note that we use task_tgid_vnr here to grab the pid
586			 * of the process group leader.  That way we get the
587			 * right pid if a thread in a multi-threaded
588			 * core_pattern process dies.
589			 */
590			printk(KERN_WARNING
591				"Process %d(%s) has RLIMIT_CORE set to 1\n",
592				task_tgid_vnr(current), current->comm);
593			printk(KERN_WARNING "Aborting core\n");
594			goto fail_unlock;
595		}
596		cprm.limit = RLIM_INFINITY;
597
598		dump_count = atomic_inc_return(&core_dump_count);
599		if (core_pipe_limit && (core_pipe_limit < dump_count)) {
600			printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
601			       task_tgid_vnr(current), current->comm);
602			printk(KERN_WARNING "Skipping core dump\n");
603			goto fail_dropcount;
604		}
605
606		helper_argv = argv_split(GFP_KERNEL, cn.corename, NULL);
607		if (!helper_argv) {
608			printk(KERN_WARNING "%s failed to allocate memory\n",
609			       __func__);
610			goto fail_dropcount;
611		}
612
613		retval = -ENOMEM;
614		sub_info = call_usermodehelper_setup(helper_argv[0],
615						helper_argv, NULL, GFP_KERNEL,
616						umh_pipe_setup, NULL, &cprm);
617		if (sub_info)
618			retval = call_usermodehelper_exec(sub_info,
619							  UMH_WAIT_EXEC);
620
621		argv_free(helper_argv);
622		if (retval) {
623			printk(KERN_INFO "Core dump to |%s pipe failed\n",
624			       cn.corename);
625			goto close_fail;
626		}
627	} else {
628		struct inode *inode;
629		int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
630				 O_LARGEFILE | O_EXCL;
631
632		if (cprm.limit < binfmt->min_coredump)
633			goto fail_unlock;
634
635		if (need_suid_safe && cn.corename[0] != '/') {
636			printk(KERN_WARNING "Pid %d(%s) can only dump core "\
637				"to fully qualified path!\n",
638				task_tgid_vnr(current), current->comm);
639			printk(KERN_WARNING "Skipping core dump\n");
640			goto fail_unlock;
641		}
642
643		/*
644		 * Unlink the file if it exists unless this is a SUID
645		 * binary - in that case, we're running around with root
646		 * privs and don't want to unlink another user's coredump.
647		 */
648		if (!need_suid_safe) {
649			mm_segment_t old_fs;
650
651			old_fs = get_fs();
652			set_fs(KERNEL_DS);
653			/*
654			 * If it doesn't exist, that's fine. If there's some
655			 * other problem, we'll catch it at the filp_open().
656			 */
657			(void) sys_unlink((const char __user *)cn.corename);
658			set_fs(old_fs);
659		}
660
661		/*
662		 * There is a race between unlinking and creating the
663		 * file, but if that causes an EEXIST here, that's
664		 * fine - another process raced with us while creating
665		 * the corefile, and the other process won. To userspace,
666		 * what matters is that at least one of the two processes
667		 * writes its coredump successfully, not which one.
668		 */
669		if (need_suid_safe) {
670			/*
671			 * Using user namespaces, normal user tasks can change
672			 * their current->fs->root to point to arbitrary
673			 * directories. Since the intention of the "only dump
674			 * with a fully qualified path" rule is to control where
675			 * coredumps may be placed using root privileges,
676			 * current->fs->root must not be used. Instead, use the
677			 * root directory of init_task.
678			 */
679			struct path root;
680
681			task_lock(&init_task);
682			get_fs_root(init_task.fs, &root);
683			task_unlock(&init_task);
684			cprm.file = file_open_root(root.dentry, root.mnt,
685				cn.corename, open_flags, 0600);
686			path_put(&root);
687		} else {
688			cprm.file = filp_open(cn.corename, open_flags, 0600);
689		}
690		if (IS_ERR(cprm.file))
691			goto fail_unlock;
692
693		inode = file_inode(cprm.file);
694		if (inode->i_nlink > 1)
695			goto close_fail;
696		if (d_unhashed(cprm.file->f_path.dentry))
697			goto close_fail;
698		/*
699		 * AK: actually i see no reason to not allow this for named
700		 * pipes etc, but keep the previous behaviour for now.
701		 */
702		if (!S_ISREG(inode->i_mode))
703			goto close_fail;
704		/*
705		 * Don't dump core if the filesystem changed owner or mode
706		 * of the file during file creation. This is an issue when
707		 * a process dumps core while its cwd is e.g. on a vfat
708		 * filesystem.
709		 */
710		if (!uid_eq(inode->i_uid, current_fsuid()))
711			goto close_fail;
712		if ((inode->i_mode & 0677) != 0600)
713			goto close_fail;
714		if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
715			goto close_fail;
716		if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
717			goto close_fail;
718	}
719
720	/* get us an unshared descriptor table; almost always a no-op */
721	retval = unshare_files(&displaced);
722	if (retval)
723		goto close_fail;
724	if (displaced)
725		put_files_struct(displaced);
726	if (!dump_interrupted()) {
727		file_start_write(cprm.file);
728		core_dumped = binfmt->core_dump(&cprm);
729		file_end_write(cprm.file);
730	}
731	if (ispipe && core_pipe_limit)
732		wait_for_dump_helpers(cprm.file);
733close_fail:
734	if (cprm.file)
735		filp_close(cprm.file, NULL);
736fail_dropcount:
737	if (ispipe)
738		atomic_dec(&core_dump_count);
739fail_unlock:
740	kfree(cn.corename);
741	coredump_finish(mm, core_dumped);
742	revert_creds(old_cred);
743fail_creds:
744	put_cred(cred);
745fail:
746	return;
747}
748
749/*
750 * Core dumping helper functions.  These are the only things you should
751 * do on a core-file: use only these functions to write out all the
752 * necessary info.
753 */
754int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
755{
756	struct file *file = cprm->file;
757	loff_t pos = file->f_pos;
758	ssize_t n;
759	if (cprm->written + nr > cprm->limit)
760		return 0;
761	while (nr) {
762		if (dump_interrupted())
763			return 0;
764		n = __kernel_write(file, addr, nr, &pos);
765		if (n <= 0)
766			return 0;
767		file->f_pos = pos;
768		cprm->written += n;
769		nr -= n;
770	}
771	return 1;
772}
773EXPORT_SYMBOL(dump_emit);
774
775int dump_skip(struct coredump_params *cprm, size_t nr)
776{
777	static char zeroes[PAGE_SIZE];
778	struct file *file = cprm->file;
779	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
780		if (cprm->written + nr > cprm->limit)
781			return 0;
782		if (dump_interrupted() ||
783		    file->f_op->llseek(file, nr, SEEK_CUR) < 0)
784			return 0;
785		cprm->written += nr;
786		return 1;
787	} else {
788		while (nr > PAGE_SIZE) {
789			if (!dump_emit(cprm, zeroes, PAGE_SIZE))
790				return 0;
791			nr -= PAGE_SIZE;
792		}
793		return dump_emit(cprm, zeroes, nr);
794	}
795}
796EXPORT_SYMBOL(dump_skip);
797
798int dump_align(struct coredump_params *cprm, int align)
799{
800	unsigned mod = cprm->written & (align - 1);
801	if (align & (align - 1))
802		return 0;
803	return mod ? dump_skip(cprm, align - mod) : 1;
804}
805EXPORT_SYMBOL(dump_align);
806