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-rw-r--r--fs/coredump.c686
1 files changed, 686 insertions, 0 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
new file mode 100644
index 00000000000..f045bbad682
--- /dev/null
+++ b/fs/coredump.c
@@ -0,0 +1,686 @@
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/utsname.h>
18#include <linux/pid_namespace.h>
19#include <linux/module.h>
20#include <linux/namei.h>
21#include <linux/mount.h>
22#include <linux/security.h>
23#include <linux/syscalls.h>
24#include <linux/tsacct_kern.h>
25#include <linux/cn_proc.h>
26#include <linux/audit.h>
27#include <linux/tracehook.h>
28#include <linux/kmod.h>
29#include <linux/fsnotify.h>
30#include <linux/fs_struct.h>
31#include <linux/pipe_fs_i.h>
32#include <linux/oom.h>
33#include <linux/compat.h>
34
35#include <asm/uaccess.h>
36#include <asm/mmu_context.h>
37#include <asm/tlb.h>
38#include <asm/exec.h>
39
40#include <trace/events/task.h>
41#include "internal.h"
42
43#include <trace/events/sched.h>
44
45int core_uses_pid;
46char core_pattern[CORENAME_MAX_SIZE] = "core";
47unsigned int core_pipe_limit;
48
49struct core_name {
50 char *corename;
51 int used, size;
52};
53static atomic_t call_count = ATOMIC_INIT(1);
54
55/* The maximal length of core_pattern is also specified in sysctl.c */
56
57static int expand_corename(struct core_name *cn)
58{
59 char *old_corename = cn->corename;
60
61 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
62 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
63
64 if (!cn->corename) {
65 kfree(old_corename);
66 return -ENOMEM;
67 }
68
69 return 0;
70}
71
72static int cn_printf(struct core_name *cn, const char *fmt, ...)
73{
74 char *cur;
75 int need;
76 int ret;
77 va_list arg;
78
79 va_start(arg, fmt);
80 need = vsnprintf(NULL, 0, fmt, arg);
81 va_end(arg);
82
83 if (likely(need < cn->size - cn->used - 1))
84 goto out_printf;
85
86 ret = expand_corename(cn);
87 if (ret)
88 goto expand_fail;
89
90out_printf:
91 cur = cn->corename + cn->used;
92 va_start(arg, fmt);
93 vsnprintf(cur, need + 1, fmt, arg);
94 va_end(arg);
95 cn->used += need;
96 return 0;
97
98expand_fail:
99 return ret;
100}
101
102static void cn_escape(char *str)
103{
104 for (; *str; str++)
105 if (*str == '/')
106 *str = '!';
107}
108
109static int cn_print_exe_file(struct core_name *cn)
110{
111 struct file *exe_file;
112 char *pathbuf, *path;
113 int ret;
114
115 exe_file = get_mm_exe_file(current->mm);
116 if (!exe_file) {
117 char *commstart = cn->corename + cn->used;
118 ret = cn_printf(cn, "%s (path unknown)", current->comm);
119 cn_escape(commstart);
120 return ret;
121 }
122
123 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
124 if (!pathbuf) {
125 ret = -ENOMEM;
126 goto put_exe_file;
127 }
128
129 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
130 if (IS_ERR(path)) {
131 ret = PTR_ERR(path);
132 goto free_buf;
133 }
134
135 cn_escape(path);
136
137 ret = cn_printf(cn, "%s", path);
138
139free_buf:
140 kfree(pathbuf);
141put_exe_file:
142 fput(exe_file);
143 return ret;
144}
145
146/* format_corename will inspect the pattern parameter, and output a
147 * name into corename, which must have space for at least
148 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
149 */
150static int format_corename(struct core_name *cn, long signr)
151{
152 const struct cred *cred = current_cred();
153 const char *pat_ptr = core_pattern;
154 int ispipe = (*pat_ptr == '|');
155 int pid_in_pattern = 0;
156 int err = 0;
157
158 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
159 cn->corename = kmalloc(cn->size, GFP_KERNEL);
160 cn->used = 0;
161
162 if (!cn->corename)
163 return -ENOMEM;
164
165 /* Repeat as long as we have more pattern to process and more output
166 space */
167 while (*pat_ptr) {
168 if (*pat_ptr != '%') {
169 if (*pat_ptr == 0)
170 goto out;
171 err = cn_printf(cn, "%c", *pat_ptr++);
172 } else {
173 switch (*++pat_ptr) {
174 /* single % at the end, drop that */
175 case 0:
176 goto out;
177 /* Double percent, output one percent */
178 case '%':
179 err = cn_printf(cn, "%c", '%');
180 break;
181 /* pid */
182 case 'p':
183 pid_in_pattern = 1;
184 err = cn_printf(cn, "%d",
185 task_tgid_vnr(current));
186 break;
187 /* uid */
188 case 'u':
189 err = cn_printf(cn, "%d", cred->uid);
190 break;
191 /* gid */
192 case 'g':
193 err = cn_printf(cn, "%d", cred->gid);
194 break;
195 /* signal that caused the coredump */
196 case 's':
197 err = cn_printf(cn, "%ld", signr);
198 break;
199 /* UNIX time of coredump */
200 case 't': {
201 struct timeval tv;
202 do_gettimeofday(&tv);
203 err = cn_printf(cn, "%lu", tv.tv_sec);
204 break;
205 }
206 /* hostname */
207 case 'h': {
208 char *namestart = cn->corename + cn->used;
209 down_read(&uts_sem);
210 err = cn_printf(cn, "%s",
211 utsname()->nodename);
212 up_read(&uts_sem);
213 cn_escape(namestart);
214 break;
215 }
216 /* executable */
217 case 'e': {
218 char *commstart = cn->corename + cn->used;
219 err = cn_printf(cn, "%s", current->comm);
220 cn_escape(commstart);
221 break;
222 }
223 case 'E':
224 err = cn_print_exe_file(cn);
225 break;
226 /* core limit size */
227 case 'c':
228 err = cn_printf(cn, "%lu",
229 rlimit(RLIMIT_CORE));
230 break;
231 default:
232 break;
233 }
234 ++pat_ptr;
235 }
236
237 if (err)
238 return err;
239 }
240
241 /* Backward compatibility with core_uses_pid:
242 *
243 * If core_pattern does not include a %p (as is the default)
244 * and core_uses_pid is set, then .%pid will be appended to
245 * the filename. Do not do this for piped commands. */
246 if (!ispipe && !pid_in_pattern && core_uses_pid) {
247 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
248 if (err)
249 return err;
250 }
251out:
252 return ispipe;
253}
254
255static int zap_process(struct task_struct *start, int exit_code)
256{
257 struct task_struct *t;
258 int nr = 0;
259
260 start->signal->flags = SIGNAL_GROUP_EXIT;
261 start->signal->group_exit_code = exit_code;
262 start->signal->group_stop_count = 0;
263
264 t = start;
265 do {
266 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
267 if (t != current && t->mm) {
268 sigaddset(&t->pending.signal, SIGKILL);
269 signal_wake_up(t, 1);
270 nr++;
271 }
272 } while_each_thread(start, t);
273
274 return nr;
275}
276
277static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
278 struct core_state *core_state, int exit_code)
279{
280 struct task_struct *g, *p;
281 unsigned long flags;
282 int nr = -EAGAIN;
283
284 spin_lock_irq(&tsk->sighand->siglock);
285 if (!signal_group_exit(tsk->signal)) {
286 mm->core_state = core_state;
287 nr = zap_process(tsk, exit_code);
288 }
289 spin_unlock_irq(&tsk->sighand->siglock);
290 if (unlikely(nr < 0))
291 return nr;
292
293 if (atomic_read(&mm->mm_users) == nr + 1)
294 goto done;
295 /*
296 * We should find and kill all tasks which use this mm, and we should
297 * count them correctly into ->nr_threads. We don't take tasklist
298 * lock, but this is safe wrt:
299 *
300 * fork:
301 * None of sub-threads can fork after zap_process(leader). All
302 * processes which were created before this point should be
303 * visible to zap_threads() because copy_process() adds the new
304 * process to the tail of init_task.tasks list, and lock/unlock
305 * of ->siglock provides a memory barrier.
306 *
307 * do_exit:
308 * The caller holds mm->mmap_sem. This means that the task which
309 * uses this mm can't pass exit_mm(), so it can't exit or clear
310 * its ->mm.
311 *
312 * de_thread:
313 * It does list_replace_rcu(&leader->tasks, &current->tasks),
314 * we must see either old or new leader, this does not matter.
315 * However, it can change p->sighand, so lock_task_sighand(p)
316 * must be used. Since p->mm != NULL and we hold ->mmap_sem
317 * it can't fail.
318 *
319 * Note also that "g" can be the old leader with ->mm == NULL
320 * and already unhashed and thus removed from ->thread_group.
321 * This is OK, __unhash_process()->list_del_rcu() does not
322 * clear the ->next pointer, we will find the new leader via
323 * next_thread().
324 */
325 rcu_read_lock();
326 for_each_process(g) {
327 if (g == tsk->group_leader)
328 continue;
329 if (g->flags & PF_KTHREAD)
330 continue;
331 p = g;
332 do {
333 if (p->mm) {
334 if (unlikely(p->mm == mm)) {
335 lock_task_sighand(p, &flags);
336 nr += zap_process(p, exit_code);
337 unlock_task_sighand(p, &flags);
338 }
339 break;
340 }
341 } while_each_thread(g, p);
342 }
343 rcu_read_unlock();
344done:
345 atomic_set(&core_state->nr_threads, nr);
346 return nr;
347}
348
349static int coredump_wait(int exit_code, struct core_state *core_state)
350{
351 struct task_struct *tsk = current;
352 struct mm_struct *mm = tsk->mm;
353 int core_waiters = -EBUSY;
354
355 init_completion(&core_state->startup);
356 core_state->dumper.task = tsk;
357 core_state->dumper.next = NULL;
358
359 down_write(&mm->mmap_sem);
360 if (!mm->core_state)
361 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
362 up_write(&mm->mmap_sem);
363
364 if (core_waiters > 0) {
365 struct core_thread *ptr;
366
367 wait_for_completion(&core_state->startup);
368 /*
369 * Wait for all the threads to become inactive, so that
370 * all the thread context (extended register state, like
371 * fpu etc) gets copied to the memory.
372 */
373 ptr = core_state->dumper.next;
374 while (ptr != NULL) {
375 wait_task_inactive(ptr->task, 0);
376 ptr = ptr->next;
377 }
378 }
379
380 return core_waiters;
381}
382
383static void coredump_finish(struct mm_struct *mm)
384{
385 struct core_thread *curr, *next;
386 struct task_struct *task;
387
388 next = mm->core_state->dumper.next;
389 while ((curr = next) != NULL) {
390 next = curr->next;
391 task = curr->task;
392 /*
393 * see exit_mm(), curr->task must not see
394 * ->task == NULL before we read ->next.
395 */
396 smp_mb();
397 curr->task = NULL;
398 wake_up_process(task);
399 }
400
401 mm->core_state = NULL;
402}
403
404static void wait_for_dump_helpers(struct file *file)
405{
406 struct pipe_inode_info *pipe;
407
408 pipe = file->f_path.dentry->d_inode->i_pipe;
409
410 pipe_lock(pipe);
411 pipe->readers++;
412 pipe->writers--;
413
414 while ((pipe->readers > 1) && (!signal_pending(current))) {
415 wake_up_interruptible_sync(&pipe->wait);
416 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
417 pipe_wait(pipe);
418 }
419
420 pipe->readers--;
421 pipe->writers++;
422 pipe_unlock(pipe);
423
424}
425
426/*
427 * umh_pipe_setup
428 * helper function to customize the process used
429 * to collect the core in userspace. Specifically
430 * it sets up a pipe and installs it as fd 0 (stdin)
431 * for the process. Returns 0 on success, or
432 * PTR_ERR on failure.
433 * Note that it also sets the core limit to 1. This
434 * is a special value that we use to trap recursive
435 * core dumps
436 */
437static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
438{
439 struct file *files[2];
440 struct coredump_params *cp = (struct coredump_params *)info->data;
441 int err = create_pipe_files(files, 0);
442 if (err)
443 return err;
444
445 cp->file = files[1];
446
447 replace_fd(0, files[0], 0);
448 /* and disallow core files too */
449 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
450
451 return 0;
452}
453
454void do_coredump(long signr, int exit_code, struct pt_regs *regs)
455{
456 struct core_state core_state;
457 struct core_name cn;
458 struct mm_struct *mm = current->mm;
459 struct linux_binfmt * binfmt;
460 const struct cred *old_cred;
461 struct cred *cred;
462 int retval = 0;
463 int flag = 0;
464 int ispipe;
465 struct files_struct *displaced;
466 bool need_nonrelative = false;
467 static atomic_t core_dump_count = ATOMIC_INIT(0);
468 struct coredump_params cprm = {
469 .signr = signr,
470 .regs = regs,
471 .limit = rlimit(RLIMIT_CORE),
472 /*
473 * We must use the same mm->flags while dumping core to avoid
474 * inconsistency of bit flags, since this flag is not protected
475 * by any locks.
476 */
477 .mm_flags = mm->flags,
478 };
479
480 audit_core_dumps(signr);
481
482 binfmt = mm->binfmt;
483 if (!binfmt || !binfmt->core_dump)
484 goto fail;
485 if (!__get_dumpable(cprm.mm_flags))
486 goto fail;
487
488 cred = prepare_creds();
489 if (!cred)
490 goto fail;
491 /*
492 * We cannot trust fsuid as being the "true" uid of the process
493 * nor do we know its entire history. We only know it was tainted
494 * so we dump it as root in mode 2, and only into a controlled
495 * environment (pipe handler or fully qualified path).
496 */
497 if (__get_dumpable(cprm.mm_flags) == SUID_DUMPABLE_SAFE) {
498 /* Setuid core dump mode */
499 flag = O_EXCL; /* Stop rewrite attacks */
500 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
501 need_nonrelative = true;
502 }
503
504 retval = coredump_wait(exit_code, &core_state);
505 if (retval < 0)
506 goto fail_creds;
507
508 old_cred = override_creds(cred);
509
510 /*
511 * Clear any false indication of pending signals that might
512 * be seen by the filesystem code called to write the core file.
513 */
514 clear_thread_flag(TIF_SIGPENDING);
515
516 ispipe = format_corename(&cn, signr);
517
518 if (ispipe) {
519 int dump_count;
520 char **helper_argv;
521
522 if (ispipe < 0) {
523 printk(KERN_WARNING "format_corename failed\n");
524 printk(KERN_WARNING "Aborting core\n");
525 goto fail_corename;
526 }
527
528 if (cprm.limit == 1) {
529 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
530 *
531 * Normally core limits are irrelevant to pipes, since
532 * we're not writing to the file system, but we use
533 * cprm.limit of 1 here as a speacial value, this is a
534 * consistent way to catch recursive crashes.
535 * We can still crash if the core_pattern binary sets
536 * RLIM_CORE = !1, but it runs as root, and can do
537 * lots of stupid things.
538 *
539 * Note that we use task_tgid_vnr here to grab the pid
540 * of the process group leader. That way we get the
541 * right pid if a thread in a multi-threaded
542 * core_pattern process dies.
543 */
544 printk(KERN_WARNING
545 "Process %d(%s) has RLIMIT_CORE set to 1\n",
546 task_tgid_vnr(current), current->comm);
547 printk(KERN_WARNING "Aborting core\n");
548 goto fail_unlock;
549 }
550 cprm.limit = RLIM_INFINITY;
551
552 dump_count = atomic_inc_return(&core_dump_count);
553 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
554 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
555 task_tgid_vnr(current), current->comm);
556 printk(KERN_WARNING "Skipping core dump\n");
557 goto fail_dropcount;
558 }
559
560 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
561 if (!helper_argv) {
562 printk(KERN_WARNING "%s failed to allocate memory\n",
563 __func__);
564 goto fail_dropcount;
565 }
566
567 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
568 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
569 NULL, &cprm);
570 argv_free(helper_argv);
571 if (retval) {
572 printk(KERN_INFO "Core dump to %s pipe failed\n",
573 cn.corename);
574 goto close_fail;
575 }
576 } else {
577 struct inode *inode;
578
579 if (cprm.limit < binfmt->min_coredump)
580 goto fail_unlock;
581
582 if (need_nonrelative && cn.corename[0] != '/') {
583 printk(KERN_WARNING "Pid %d(%s) can only dump core "\
584 "to fully qualified path!\n",
585 task_tgid_vnr(current), current->comm);
586 printk(KERN_WARNING "Skipping core dump\n");
587 goto fail_unlock;
588 }
589
590 cprm.file = filp_open(cn.corename,
591 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
592 0600);
593 if (IS_ERR(cprm.file))
594 goto fail_unlock;
595
596 inode = cprm.file->f_path.dentry->d_inode;
597 if (inode->i_nlink > 1)
598 goto close_fail;
599 if (d_unhashed(cprm.file->f_path.dentry))
600 goto close_fail;
601 /*
602 * AK: actually i see no reason to not allow this for named
603 * pipes etc, but keep the previous behaviour for now.
604 */
605 if (!S_ISREG(inode->i_mode))
606 goto close_fail;
607 /*
608 * Dont allow local users get cute and trick others to coredump
609 * into their pre-created files.
610 */
611 if (!uid_eq(inode->i_uid, current_fsuid()))
612 goto close_fail;
613 if (!cprm.file->f_op || !cprm.file->f_op->write)
614 goto close_fail;
615 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
616 goto close_fail;
617 }
618
619 /* get us an unshared descriptor table; almost always a no-op */
620 retval = unshare_files(&displaced);
621 if (retval)
622 goto close_fail;
623 if (displaced)
624 put_files_struct(displaced);
625 retval = binfmt->core_dump(&cprm);
626 if (retval)
627 current->signal->group_exit_code |= 0x80;
628
629 if (ispipe && core_pipe_limit)
630 wait_for_dump_helpers(cprm.file);
631close_fail:
632 if (cprm.file)
633 filp_close(cprm.file, NULL);
634fail_dropcount:
635 if (ispipe)
636 atomic_dec(&core_dump_count);
637fail_unlock:
638 kfree(cn.corename);
639fail_corename:
640 coredump_finish(mm);
641 revert_creds(old_cred);
642fail_creds:
643 put_cred(cred);
644fail:
645 return;
646}
647
648/*
649 * Core dumping helper functions. These are the only things you should
650 * do on a core-file: use only these functions to write out all the
651 * necessary info.
652 */
653int dump_write(struct file *file, const void *addr, int nr)
654{
655 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
656}
657EXPORT_SYMBOL(dump_write);
658
659int dump_seek(struct file *file, loff_t off)
660{
661 int ret = 1;
662
663 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
664 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
665 return 0;
666 } else {
667 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
668
669 if (!buf)
670 return 0;
671 while (off > 0) {
672 unsigned long n = off;
673
674 if (n > PAGE_SIZE)
675 n = PAGE_SIZE;
676 if (!dump_write(file, buf, n)) {
677 ret = 0;
678 break;
679 }
680 off -= n;
681 }
682 free_page((unsigned long)buf);
683 }
684 return ret;
685}
686EXPORT_SYMBOL(dump_seek);
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-27 22:18:56 -0500