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
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
expand_corename(struct core_name * cn,int size)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
cn_vprintf(struct core_name * cn,const char * fmt,va_list arg)77 static int cn_vprintf(struct core_name *cn, const char *fmt, va_list arg)
78 {
79 int free, need;
80 va_list arg_copy;
81
82 again:
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
cn_printf(struct core_name * cn,const char * fmt,...)100 static 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
cn_esc_printf(struct core_name * cn,const char * fmt,...)112 static 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
cn_print_exe_file(struct core_name * cn)129 static 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
153 free_buf:
154 kfree(pathbuf);
155 put_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 */
format_corename(struct core_name * cn,struct coredump_params * cprm)164 static 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
267 out:
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
zap_process(struct task_struct * start,int exit_code)281 static 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
zap_threads(struct task_struct * tsk,struct mm_struct * mm,struct core_state * core_state,int exit_code)302 static 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, ¤t->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();
375 done:
376 atomic_set(&core_state->nr_threads, nr);
377 return nr;
378 }
379
coredump_wait(int exit_code,struct core_state * core_state)380 static 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
coredump_finish(struct mm_struct * mm,bool core_dumped)414 static 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(¤t->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(¤t->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
dump_interrupted(void)442 static 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
wait_for_dump_helpers(struct file * file)453 static 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 */
umh_pipe_setup(struct subprocess_info * info,struct cred * new)487 static 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
do_coredump(const siginfo_t * siginfo)505 void 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);
733 close_fail:
734 if (cprm.file)
735 filp_close(cprm.file, NULL);
736 fail_dropcount:
737 if (ispipe)
738 atomic_dec(&core_dump_count);
739 fail_unlock:
740 kfree(cn.corename);
741 coredump_finish(mm, core_dumped);
742 revert_creds(old_cred);
743 fail_creds:
744 put_cred(cred);
745 fail:
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 */
dump_emit(struct coredump_params * cprm,const void * addr,int nr)754 int 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 }
773 EXPORT_SYMBOL(dump_emit);
774
dump_skip(struct coredump_params * cprm,size_t nr)775 int 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 }
796 EXPORT_SYMBOL(dump_skip);
797
dump_align(struct coredump_params * cprm,int align)798 int 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 }
805 EXPORT_SYMBOL(dump_align);
806