blob: 177493272a6158a3f5192ed3eb061d7cef2e9556 [file] [log] [blame]
Alex Kelly10c28d92012-09-26 21:52:08 -04001#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>
Alex Kelly179899f2012-10-04 17:15:24 -070017#include <linux/coredump.h>
Alex Kelly10c28d92012-09-26 21:52:08 -040018#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
36#include <asm/uaccess.h>
37#include <asm/mmu_context.h>
38#include <asm/tlb.h>
39#include <asm/exec.h>
40
41#include <trace/events/task.h>
42#include "internal.h"
Alex Kelly179899f2012-10-04 17:15:24 -070043#include "coredump.h"
Alex Kelly10c28d92012-09-26 21:52:08 -040044
45#include <trace/events/sched.h>
46
47int core_uses_pid;
48char core_pattern[CORENAME_MAX_SIZE] = "core";
49unsigned int core_pipe_limit;
50
51struct core_name {
52 char *corename;
53 int used, size;
54};
55static atomic_t call_count = ATOMIC_INIT(1);
56
57/* The maximal length of core_pattern is also specified in sysctl.c */
58
59static int expand_corename(struct core_name *cn)
60{
61 char *old_corename = cn->corename;
62
63 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
64 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
65
66 if (!cn->corename) {
67 kfree(old_corename);
68 return -ENOMEM;
69 }
70
71 return 0;
72}
73
74static int cn_printf(struct core_name *cn, const char *fmt, ...)
75{
76 char *cur;
77 int need;
78 int ret;
79 va_list arg;
80
81 va_start(arg, fmt);
82 need = vsnprintf(NULL, 0, fmt, arg);
83 va_end(arg);
84
85 if (likely(need < cn->size - cn->used - 1))
86 goto out_printf;
87
88 ret = expand_corename(cn);
89 if (ret)
90 goto expand_fail;
91
92out_printf:
93 cur = cn->corename + cn->used;
94 va_start(arg, fmt);
95 vsnprintf(cur, need + 1, fmt, arg);
96 va_end(arg);
97 cn->used += need;
98 return 0;
99
100expand_fail:
101 return ret;
102}
103
104static void cn_escape(char *str)
105{
106 for (; *str; str++)
107 if (*str == '/')
108 *str = '!';
109}
110
111static int cn_print_exe_file(struct core_name *cn)
112{
113 struct file *exe_file;
114 char *pathbuf, *path;
115 int ret;
116
117 exe_file = get_mm_exe_file(current->mm);
118 if (!exe_file) {
119 char *commstart = cn->corename + cn->used;
120 ret = cn_printf(cn, "%s (path unknown)", current->comm);
121 cn_escape(commstart);
122 return ret;
123 }
124
125 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
126 if (!pathbuf) {
127 ret = -ENOMEM;
128 goto put_exe_file;
129 }
130
131 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
132 if (IS_ERR(path)) {
133 ret = PTR_ERR(path);
134 goto free_buf;
135 }
136
137 cn_escape(path);
138
139 ret = cn_printf(cn, "%s", path);
140
141free_buf:
142 kfree(pathbuf);
143put_exe_file:
144 fput(exe_file);
145 return ret;
146}
147
148/* format_corename will inspect the pattern parameter, and output a
149 * name into corename, which must have space for at least
150 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
151 */
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700152static int format_corename(struct core_name *cn, struct coredump_params *cprm)
Alex Kelly10c28d92012-09-26 21:52:08 -0400153{
154 const struct cred *cred = current_cred();
155 const char *pat_ptr = core_pattern;
156 int ispipe = (*pat_ptr == '|');
157 int pid_in_pattern = 0;
158 int err = 0;
159
160 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
161 cn->corename = kmalloc(cn->size, GFP_KERNEL);
162 cn->used = 0;
163
164 if (!cn->corename)
165 return -ENOMEM;
166
167 /* Repeat as long as we have more pattern to process and more output
168 space */
169 while (*pat_ptr) {
170 if (*pat_ptr != '%') {
171 if (*pat_ptr == 0)
172 goto out;
173 err = cn_printf(cn, "%c", *pat_ptr++);
174 } else {
175 switch (*++pat_ptr) {
176 /* single % at the end, drop that */
177 case 0:
178 goto out;
179 /* Double percent, output one percent */
180 case '%':
181 err = cn_printf(cn, "%c", '%');
182 break;
183 /* pid */
184 case 'p':
185 pid_in_pattern = 1;
186 err = cn_printf(cn, "%d",
187 task_tgid_vnr(current));
188 break;
189 /* uid */
190 case 'u':
191 err = cn_printf(cn, "%d", cred->uid);
192 break;
193 /* gid */
194 case 'g':
195 err = cn_printf(cn, "%d", cred->gid);
196 break;
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700197 case 'd':
198 err = cn_printf(cn, "%d",
199 __get_dumpable(cprm->mm_flags));
200 break;
Alex Kelly10c28d92012-09-26 21:52:08 -0400201 /* signal that caused the coredump */
202 case 's':
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700203 err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400204 break;
205 /* UNIX time of coredump */
206 case 't': {
207 struct timeval tv;
208 do_gettimeofday(&tv);
209 err = cn_printf(cn, "%lu", tv.tv_sec);
210 break;
211 }
212 /* hostname */
213 case 'h': {
214 char *namestart = cn->corename + cn->used;
215 down_read(&uts_sem);
216 err = cn_printf(cn, "%s",
217 utsname()->nodename);
218 up_read(&uts_sem);
219 cn_escape(namestart);
220 break;
221 }
222 /* executable */
223 case 'e': {
224 char *commstart = cn->corename + cn->used;
225 err = cn_printf(cn, "%s", current->comm);
226 cn_escape(commstart);
227 break;
228 }
229 case 'E':
230 err = cn_print_exe_file(cn);
231 break;
232 /* core limit size */
233 case 'c':
234 err = cn_printf(cn, "%lu",
235 rlimit(RLIMIT_CORE));
236 break;
237 default:
238 break;
239 }
240 ++pat_ptr;
241 }
242
243 if (err)
244 return err;
245 }
246
247 /* Backward compatibility with core_uses_pid:
248 *
249 * If core_pattern does not include a %p (as is the default)
250 * and core_uses_pid is set, then .%pid will be appended to
251 * the filename. Do not do this for piped commands. */
252 if (!ispipe && !pid_in_pattern && core_uses_pid) {
253 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
254 if (err)
255 return err;
256 }
257out:
258 return ispipe;
259}
260
261static int zap_process(struct task_struct *start, int exit_code)
262{
263 struct task_struct *t;
264 int nr = 0;
265
266 start->signal->flags = SIGNAL_GROUP_EXIT;
267 start->signal->group_exit_code = exit_code;
268 start->signal->group_stop_count = 0;
269
270 t = start;
271 do {
272 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
273 if (t != current && t->mm) {
274 sigaddset(&t->pending.signal, SIGKILL);
275 signal_wake_up(t, 1);
276 nr++;
277 }
278 } while_each_thread(start, t);
279
280 return nr;
281}
282
283static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
284 struct core_state *core_state, int exit_code)
285{
286 struct task_struct *g, *p;
287 unsigned long flags;
288 int nr = -EAGAIN;
289
290 spin_lock_irq(&tsk->sighand->siglock);
291 if (!signal_group_exit(tsk->signal)) {
292 mm->core_state = core_state;
293 nr = zap_process(tsk, exit_code);
294 }
295 spin_unlock_irq(&tsk->sighand->siglock);
296 if (unlikely(nr < 0))
297 return nr;
298
299 if (atomic_read(&mm->mm_users) == nr + 1)
300 goto done;
301 /*
302 * We should find and kill all tasks which use this mm, and we should
303 * count them correctly into ->nr_threads. We don't take tasklist
304 * lock, but this is safe wrt:
305 *
306 * fork:
307 * None of sub-threads can fork after zap_process(leader). All
308 * processes which were created before this point should be
309 * visible to zap_threads() because copy_process() adds the new
310 * process to the tail of init_task.tasks list, and lock/unlock
311 * of ->siglock provides a memory barrier.
312 *
313 * do_exit:
314 * The caller holds mm->mmap_sem. This means that the task which
315 * uses this mm can't pass exit_mm(), so it can't exit or clear
316 * its ->mm.
317 *
318 * de_thread:
319 * It does list_replace_rcu(&leader->tasks, &current->tasks),
320 * we must see either old or new leader, this does not matter.
321 * However, it can change p->sighand, so lock_task_sighand(p)
322 * must be used. Since p->mm != NULL and we hold ->mmap_sem
323 * it can't fail.
324 *
325 * Note also that "g" can be the old leader with ->mm == NULL
326 * and already unhashed and thus removed from ->thread_group.
327 * This is OK, __unhash_process()->list_del_rcu() does not
328 * clear the ->next pointer, we will find the new leader via
329 * next_thread().
330 */
331 rcu_read_lock();
332 for_each_process(g) {
333 if (g == tsk->group_leader)
334 continue;
335 if (g->flags & PF_KTHREAD)
336 continue;
337 p = g;
338 do {
339 if (p->mm) {
340 if (unlikely(p->mm == mm)) {
341 lock_task_sighand(p, &flags);
342 nr += zap_process(p, exit_code);
343 unlock_task_sighand(p, &flags);
344 }
345 break;
346 }
347 } while_each_thread(g, p);
348 }
349 rcu_read_unlock();
350done:
351 atomic_set(&core_state->nr_threads, nr);
352 return nr;
353}
354
355static int coredump_wait(int exit_code, struct core_state *core_state)
356{
357 struct task_struct *tsk = current;
358 struct mm_struct *mm = tsk->mm;
359 int core_waiters = -EBUSY;
360
361 init_completion(&core_state->startup);
362 core_state->dumper.task = tsk;
363 core_state->dumper.next = NULL;
364
365 down_write(&mm->mmap_sem);
366 if (!mm->core_state)
367 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
368 up_write(&mm->mmap_sem);
369
370 if (core_waiters > 0) {
371 struct core_thread *ptr;
372
373 wait_for_completion(&core_state->startup);
374 /*
375 * Wait for all the threads to become inactive, so that
376 * all the thread context (extended register state, like
377 * fpu etc) gets copied to the memory.
378 */
379 ptr = core_state->dumper.next;
380 while (ptr != NULL) {
381 wait_task_inactive(ptr->task, 0);
382 ptr = ptr->next;
383 }
384 }
385
386 return core_waiters;
387}
388
389static void coredump_finish(struct mm_struct *mm)
390{
391 struct core_thread *curr, *next;
392 struct task_struct *task;
393
394 next = mm->core_state->dumper.next;
395 while ((curr = next) != NULL) {
396 next = curr->next;
397 task = curr->task;
398 /*
399 * see exit_mm(), curr->task must not see
400 * ->task == NULL before we read ->next.
401 */
402 smp_mb();
403 curr->task = NULL;
404 wake_up_process(task);
405 }
406
407 mm->core_state = NULL;
408}
409
410static void wait_for_dump_helpers(struct file *file)
411{
412 struct pipe_inode_info *pipe;
413
414 pipe = file->f_path.dentry->d_inode->i_pipe;
415
416 pipe_lock(pipe);
417 pipe->readers++;
418 pipe->writers--;
419
420 while ((pipe->readers > 1) && (!signal_pending(current))) {
421 wake_up_interruptible_sync(&pipe->wait);
422 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
423 pipe_wait(pipe);
424 }
425
426 pipe->readers--;
427 pipe->writers++;
428 pipe_unlock(pipe);
429
430}
431
432/*
433 * umh_pipe_setup
434 * helper function to customize the process used
435 * to collect the core in userspace. Specifically
436 * it sets up a pipe and installs it as fd 0 (stdin)
437 * for the process. Returns 0 on success, or
438 * PTR_ERR on failure.
439 * Note that it also sets the core limit to 1. This
440 * is a special value that we use to trap recursive
441 * core dumps
442 */
443static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
444{
445 struct file *files[2];
446 struct coredump_params *cp = (struct coredump_params *)info->data;
447 int err = create_pipe_files(files, 0);
448 if (err)
449 return err;
450
451 cp->file = files[1];
452
Al Viro45525b22012-10-16 13:30:07 -0400453 err = replace_fd(0, files[0], 0);
454 fput(files[0]);
Alex Kelly10c28d92012-09-26 21:52:08 -0400455 /* and disallow core files too */
456 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
457
Al Viro45525b22012-10-16 13:30:07 -0400458 return err;
Alex Kelly10c28d92012-09-26 21:52:08 -0400459}
460
Al Viro541880d2012-11-05 13:11:26 -0500461void do_coredump(siginfo_t *siginfo)
Alex Kelly10c28d92012-09-26 21:52:08 -0400462{
463 struct core_state core_state;
464 struct core_name cn;
465 struct mm_struct *mm = current->mm;
466 struct linux_binfmt * binfmt;
467 const struct cred *old_cred;
468 struct cred *cred;
469 int retval = 0;
470 int flag = 0;
471 int ispipe;
472 struct files_struct *displaced;
473 bool need_nonrelative = false;
474 static atomic_t core_dump_count = ATOMIC_INIT(0);
475 struct coredump_params cprm = {
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700476 .siginfo = siginfo,
Al Viro541880d2012-11-05 13:11:26 -0500477 .regs = signal_pt_regs(),
Alex Kelly10c28d92012-09-26 21:52:08 -0400478 .limit = rlimit(RLIMIT_CORE),
479 /*
480 * We must use the same mm->flags while dumping core to avoid
481 * inconsistency of bit flags, since this flag is not protected
482 * by any locks.
483 */
484 .mm_flags = mm->flags,
485 };
486
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700487 audit_core_dumps(siginfo->si_signo);
Alex Kelly10c28d92012-09-26 21:52:08 -0400488
489 binfmt = mm->binfmt;
490 if (!binfmt || !binfmt->core_dump)
491 goto fail;
492 if (!__get_dumpable(cprm.mm_flags))
493 goto fail;
494
495 cred = prepare_creds();
496 if (!cred)
497 goto fail;
498 /*
499 * We cannot trust fsuid as being the "true" uid of the process
500 * nor do we know its entire history. We only know it was tainted
501 * so we dump it as root in mode 2, and only into a controlled
502 * environment (pipe handler or fully qualified path).
503 */
504 if (__get_dumpable(cprm.mm_flags) == SUID_DUMPABLE_SAFE) {
505 /* Setuid core dump mode */
506 flag = O_EXCL; /* Stop rewrite attacks */
507 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
508 need_nonrelative = true;
509 }
510
Denys Vlasenko5ab1c302012-10-04 17:15:29 -0700511 retval = coredump_wait(siginfo->si_signo, &core_state);
Alex Kelly10c28d92012-09-26 21:52:08 -0400512 if (retval < 0)
513 goto fail_creds;
514
515 old_cred = override_creds(cred);
516
517 /*
518 * Clear any false indication of pending signals that might
519 * be seen by the filesystem code called to write the core file.
520 */
521 clear_thread_flag(TIF_SIGPENDING);
522
Oleg Nesterov12a2b4b2012-10-04 17:15:25 -0700523 ispipe = format_corename(&cn, &cprm);
Alex Kelly10c28d92012-09-26 21:52:08 -0400524
525 if (ispipe) {
526 int dump_count;
527 char **helper_argv;
528
529 if (ispipe < 0) {
530 printk(KERN_WARNING "format_corename failed\n");
531 printk(KERN_WARNING "Aborting core\n");
532 goto fail_corename;
533 }
534
535 if (cprm.limit == 1) {
536 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
537 *
538 * Normally core limits are irrelevant to pipes, since
539 * we're not writing to the file system, but we use
540 * cprm.limit of 1 here as a speacial value, this is a
541 * consistent way to catch recursive crashes.
542 * We can still crash if the core_pattern binary sets
543 * RLIM_CORE = !1, but it runs as root, and can do
544 * lots of stupid things.
545 *
546 * Note that we use task_tgid_vnr here to grab the pid
547 * of the process group leader. That way we get the
548 * right pid if a thread in a multi-threaded
549 * core_pattern process dies.
550 */
551 printk(KERN_WARNING
552 "Process %d(%s) has RLIMIT_CORE set to 1\n",
553 task_tgid_vnr(current), current->comm);
554 printk(KERN_WARNING "Aborting core\n");
555 goto fail_unlock;
556 }
557 cprm.limit = RLIM_INFINITY;
558
559 dump_count = atomic_inc_return(&core_dump_count);
560 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
561 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
562 task_tgid_vnr(current), current->comm);
563 printk(KERN_WARNING "Skipping core dump\n");
564 goto fail_dropcount;
565 }
566
567 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
568 if (!helper_argv) {
569 printk(KERN_WARNING "%s failed to allocate memory\n",
570 __func__);
571 goto fail_dropcount;
572 }
573
574 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
575 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
576 NULL, &cprm);
577 argv_free(helper_argv);
578 if (retval) {
579 printk(KERN_INFO "Core dump to %s pipe failed\n",
580 cn.corename);
581 goto close_fail;
582 }
583 } else {
584 struct inode *inode;
585
586 if (cprm.limit < binfmt->min_coredump)
587 goto fail_unlock;
588
589 if (need_nonrelative && cn.corename[0] != '/') {
590 printk(KERN_WARNING "Pid %d(%s) can only dump core "\
591 "to fully qualified path!\n",
592 task_tgid_vnr(current), current->comm);
593 printk(KERN_WARNING "Skipping core dump\n");
594 goto fail_unlock;
595 }
596
597 cprm.file = filp_open(cn.corename,
598 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
599 0600);
600 if (IS_ERR(cprm.file))
601 goto fail_unlock;
602
603 inode = cprm.file->f_path.dentry->d_inode;
604 if (inode->i_nlink > 1)
605 goto close_fail;
606 if (d_unhashed(cprm.file->f_path.dentry))
607 goto close_fail;
608 /*
609 * AK: actually i see no reason to not allow this for named
610 * pipes etc, but keep the previous behaviour for now.
611 */
612 if (!S_ISREG(inode->i_mode))
613 goto close_fail;
614 /*
615 * Dont allow local users get cute and trick others to coredump
616 * into their pre-created files.
617 */
618 if (!uid_eq(inode->i_uid, current_fsuid()))
619 goto close_fail;
620 if (!cprm.file->f_op || !cprm.file->f_op->write)
621 goto close_fail;
622 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
623 goto close_fail;
624 }
625
626 /* get us an unshared descriptor table; almost always a no-op */
627 retval = unshare_files(&displaced);
628 if (retval)
629 goto close_fail;
630 if (displaced)
631 put_files_struct(displaced);
632 retval = binfmt->core_dump(&cprm);
633 if (retval)
634 current->signal->group_exit_code |= 0x80;
635
636 if (ispipe && core_pipe_limit)
637 wait_for_dump_helpers(cprm.file);
638close_fail:
639 if (cprm.file)
640 filp_close(cprm.file, NULL);
641fail_dropcount:
642 if (ispipe)
643 atomic_dec(&core_dump_count);
644fail_unlock:
645 kfree(cn.corename);
646fail_corename:
647 coredump_finish(mm);
648 revert_creds(old_cred);
649fail_creds:
650 put_cred(cred);
651fail:
652 return;
653}
654
655/*
656 * Core dumping helper functions. These are the only things you should
657 * do on a core-file: use only these functions to write out all the
658 * necessary info.
659 */
660int dump_write(struct file *file, const void *addr, int nr)
661{
662 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
663}
664EXPORT_SYMBOL(dump_write);
665
666int dump_seek(struct file *file, loff_t off)
667{
668 int ret = 1;
669
670 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
671 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
672 return 0;
673 } else {
674 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
675
676 if (!buf)
677 return 0;
678 while (off > 0) {
679 unsigned long n = off;
680
681 if (n > PAGE_SIZE)
682 n = PAGE_SIZE;
683 if (!dump_write(file, buf, n)) {
684 ret = 0;
685 break;
686 }
687 off -= n;
688 }
689 free_page((unsigned long)buf);
690 }
691 return ret;
692}
693EXPORT_SYMBOL(dump_seek);