1 #include <linux/slab.h>
2 #include <linux/file.h>
3 #include <linux/fdtable.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>
36 #include <asm/uaccess.h>
37 #include <asm/mmu_context.h>
41 #include <trace/events/task.h>
44 #include <trace/events/sched.h>
47 unsigned int core_pipe_limit
;
48 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
49 static int core_name_size
= CORENAME_MAX_SIZE
;
56 /* The maximal length of core_pattern is also specified in sysctl.c */
58 static int expand_corename(struct core_name
*cn
, int size
)
60 char *corename
= krealloc(cn
->corename
, size
, GFP_KERNEL
);
65 if (size
> core_name_size
) /* racy but harmless */
66 core_name_size
= size
;
68 cn
->size
= ksize(corename
);
69 cn
->corename
= corename
;
73 static int cn_vprintf(struct core_name
*cn
, const char *fmt
, va_list arg
)
78 free
= cn
->size
- cn
->used
;
79 need
= vsnprintf(cn
->corename
+ cn
->used
, free
, fmt
, arg
);
85 if (!expand_corename(cn
, cn
->size
+ need
- free
+ 1))
91 static int cn_printf(struct core_name
*cn
, const char *fmt
, ...)
97 ret
= cn_vprintf(cn
, fmt
, arg
);
103 static int cn_esc_printf(struct core_name
*cn
, const char *fmt
, ...)
110 ret
= cn_vprintf(cn
, fmt
, arg
);
113 for (; cur
< cn
->used
; ++cur
) {
114 if (cn
->corename
[cur
] == '/')
115 cn
->corename
[cur
] = '!';
120 static int cn_print_exe_file(struct core_name
*cn
)
122 struct file
*exe_file
;
123 char *pathbuf
, *path
;
126 exe_file
= get_mm_exe_file(current
->mm
);
128 return cn_esc_printf(cn
, "%s (path unknown)", current
->comm
);
130 pathbuf
= kmalloc(PATH_MAX
, GFP_TEMPORARY
);
136 path
= d_path(&exe_file
->f_path
, pathbuf
, PATH_MAX
);
142 ret
= cn_esc_printf(cn
, "%s", path
);
151 /* format_corename will inspect the pattern parameter, and output a
152 * name into corename, which must have space for at least
153 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
155 static int format_corename(struct core_name
*cn
, struct coredump_params
*cprm
)
157 const struct cred
*cred
= current_cred();
158 const char *pat_ptr
= core_pattern
;
159 int ispipe
= (*pat_ptr
== '|');
160 int pid_in_pattern
= 0;
165 if (expand_corename(cn
, core_name_size
))
167 cn
->corename
[0] = '\0';
172 /* Repeat as long as we have more pattern to process and more output
175 if (*pat_ptr
!= '%') {
176 err
= cn_printf(cn
, "%c", *pat_ptr
++);
178 switch (*++pat_ptr
) {
179 /* single % at the end, drop that */
182 /* Double percent, output one percent */
184 err
= cn_printf(cn
, "%c", '%');
189 err
= cn_printf(cn
, "%d",
190 task_tgid_vnr(current
));
194 err
= cn_printf(cn
, "%d",
195 task_tgid_nr(current
));
199 err
= cn_printf(cn
, "%d", cred
->uid
);
203 err
= cn_printf(cn
, "%d", cred
->gid
);
206 err
= cn_printf(cn
, "%d",
207 __get_dumpable(cprm
->mm_flags
));
209 /* signal that caused the coredump */
211 err
= cn_printf(cn
, "%ld", cprm
->siginfo
->si_signo
);
213 /* UNIX time of coredump */
216 do_gettimeofday(&tv
);
217 err
= cn_printf(cn
, "%lu", tv
.tv_sec
);
223 err
= cn_esc_printf(cn
, "%s",
224 utsname()->nodename
);
229 err
= cn_esc_printf(cn
, "%s", current
->comm
);
232 err
= cn_print_exe_file(cn
);
234 /* core limit size */
236 err
= cn_printf(cn
, "%lu",
237 rlimit(RLIMIT_CORE
));
250 /* Backward compatibility with core_uses_pid:
252 * If core_pattern does not include a %p (as is the default)
253 * and core_uses_pid is set, then .%pid will be appended to
254 * the filename. Do not do this for piped commands. */
255 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
256 err
= cn_printf(cn
, ".%d", task_tgid_vnr(current
));
263 static int zap_process(struct task_struct
*start
, int exit_code
)
265 struct task_struct
*t
;
268 start
->signal
->group_exit_code
= exit_code
;
269 start
->signal
->group_stop_count
= 0;
273 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
274 if (t
!= current
&& t
->mm
) {
275 sigaddset(&t
->pending
.signal
, SIGKILL
);
276 signal_wake_up(t
, 1);
279 } while_each_thread(start
, t
);
284 static int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
285 struct core_state
*core_state
, int exit_code
)
287 struct task_struct
*g
, *p
;
291 spin_lock_irq(&tsk
->sighand
->siglock
);
292 if (!signal_group_exit(tsk
->signal
)) {
293 mm
->core_state
= core_state
;
294 nr
= zap_process(tsk
, exit_code
);
295 tsk
->signal
->group_exit_task
= tsk
;
296 /* ignore all signals except SIGKILL, see prepare_signal() */
297 tsk
->signal
->flags
= SIGNAL_GROUP_COREDUMP
;
298 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
300 spin_unlock_irq(&tsk
->sighand
->siglock
);
301 if (unlikely(nr
< 0))
304 tsk
->flags
= PF_DUMPCORE
;
305 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
308 * We should find and kill all tasks which use this mm, and we should
309 * count them correctly into ->nr_threads. We don't take tasklist
310 * lock, but this is safe wrt:
313 * None of sub-threads can fork after zap_process(leader). All
314 * processes which were created before this point should be
315 * visible to zap_threads() because copy_process() adds the new
316 * process to the tail of init_task.tasks list, and lock/unlock
317 * of ->siglock provides a memory barrier.
320 * The caller holds mm->mmap_sem. This means that the task which
321 * uses this mm can't pass exit_mm(), so it can't exit or clear
325 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
326 * we must see either old or new leader, this does not matter.
327 * However, it can change p->sighand, so lock_task_sighand(p)
328 * must be used. Since p->mm != NULL and we hold ->mmap_sem
331 * Note also that "g" can be the old leader with ->mm == NULL
332 * and already unhashed and thus removed from ->thread_group.
333 * This is OK, __unhash_process()->list_del_rcu() does not
334 * clear the ->next pointer, we will find the new leader via
338 for_each_process(g
) {
339 if (g
== tsk
->group_leader
)
341 if (g
->flags
& PF_KTHREAD
)
346 if (unlikely(p
->mm
== mm
)) {
347 lock_task_sighand(p
, &flags
);
348 nr
+= zap_process(p
, exit_code
);
349 p
->signal
->flags
= SIGNAL_GROUP_EXIT
;
350 unlock_task_sighand(p
, &flags
);
354 } while_each_thread(g
, p
);
358 atomic_set(&core_state
->nr_threads
, nr
);
362 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
364 struct task_struct
*tsk
= current
;
365 struct mm_struct
*mm
= tsk
->mm
;
366 int core_waiters
= -EBUSY
;
368 init_completion(&core_state
->startup
);
369 core_state
->dumper
.task
= tsk
;
370 core_state
->dumper
.next
= NULL
;
372 down_write(&mm
->mmap_sem
);
374 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
375 up_write(&mm
->mmap_sem
);
377 if (core_waiters
> 0) {
378 struct core_thread
*ptr
;
380 wait_for_completion(&core_state
->startup
);
382 * Wait for all the threads to become inactive, so that
383 * all the thread context (extended register state, like
384 * fpu etc) gets copied to the memory.
386 ptr
= core_state
->dumper
.next
;
387 while (ptr
!= NULL
) {
388 wait_task_inactive(ptr
->task
, 0);
396 static void coredump_finish(struct mm_struct
*mm
, bool core_dumped
)
398 struct core_thread
*curr
, *next
;
399 struct task_struct
*task
;
401 spin_lock_irq(¤t
->sighand
->siglock
);
402 if (core_dumped
&& !__fatal_signal_pending(current
))
403 current
->signal
->group_exit_code
|= 0x80;
404 current
->signal
->group_exit_task
= NULL
;
405 current
->signal
->flags
= SIGNAL_GROUP_EXIT
;
406 spin_unlock_irq(¤t
->sighand
->siglock
);
408 next
= mm
->core_state
->dumper
.next
;
409 while ((curr
= next
) != NULL
) {
413 * see exit_mm(), curr->task must not see
414 * ->task == NULL before we read ->next.
418 wake_up_process(task
);
421 mm
->core_state
= NULL
;
424 static bool dump_interrupted(void)
427 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
428 * can do try_to_freeze() and check __fatal_signal_pending(),
429 * but then we need to teach dump_write() to restart and clear
432 return signal_pending(current
);
435 static void wait_for_dump_helpers(struct file
*file
)
437 struct pipe_inode_info
*pipe
= file
->private_data
;
442 wake_up_interruptible_sync(&pipe
->wait
);
443 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
447 * We actually want wait_event_freezable() but then we need
448 * to clear TIF_SIGPENDING and improve dump_interrupted().
450 wait_event_interruptible(pipe
->wait
, pipe
->readers
== 1);
460 * helper function to customize the process used
461 * to collect the core in userspace. Specifically
462 * it sets up a pipe and installs it as fd 0 (stdin)
463 * for the process. Returns 0 on success, or
464 * PTR_ERR on failure.
465 * Note that it also sets the core limit to 1. This
466 * is a special value that we use to trap recursive
469 static int umh_pipe_setup(struct subprocess_info
*info
, struct cred
*new)
471 struct file
*files
[2];
472 struct coredump_params
*cp
= (struct coredump_params
*)info
->data
;
473 int err
= create_pipe_files(files
, 0);
479 err
= replace_fd(0, files
[0], 0);
481 /* and disallow core files too */
482 current
->signal
->rlim
[RLIMIT_CORE
] = (struct rlimit
){1, 1};
487 void do_coredump(const siginfo_t
*siginfo
)
489 struct core_state core_state
;
491 struct mm_struct
*mm
= current
->mm
;
492 struct linux_binfmt
* binfmt
;
493 const struct cred
*old_cred
;
498 struct files_struct
*displaced
;
499 bool need_nonrelative
= false;
500 bool core_dumped
= false;
501 static atomic_t core_dump_count
= ATOMIC_INIT(0);
502 struct coredump_params cprm
= {
504 .regs
= signal_pt_regs(),
505 .limit
= rlimit(RLIMIT_CORE
),
507 * We must use the same mm->flags while dumping core to avoid
508 * inconsistency of bit flags, since this flag is not protected
511 .mm_flags
= mm
->flags
,
514 audit_core_dumps(siginfo
->si_signo
);
517 if (!binfmt
|| !binfmt
->core_dump
)
519 if (!__get_dumpable(cprm
.mm_flags
))
522 cred
= prepare_creds();
526 * We cannot trust fsuid as being the "true" uid of the process
527 * nor do we know its entire history. We only know it was tainted
528 * so we dump it as root in mode 2, and only into a controlled
529 * environment (pipe handler or fully qualified path).
531 if (__get_dumpable(cprm
.mm_flags
) == SUID_DUMP_ROOT
) {
532 /* Setuid core dump mode */
533 flag
= O_EXCL
; /* Stop rewrite attacks */
534 cred
->fsuid
= GLOBAL_ROOT_UID
; /* Dump root private */
535 need_nonrelative
= true;
538 retval
= coredump_wait(siginfo
->si_signo
, &core_state
);
542 old_cred
= override_creds(cred
);
544 ispipe
= format_corename(&cn
, &cprm
);
549 struct subprocess_info
*sub_info
;
552 printk(KERN_WARNING
"format_corename failed\n");
553 printk(KERN_WARNING
"Aborting core\n");
557 if (cprm
.limit
== 1) {
558 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
560 * Normally core limits are irrelevant to pipes, since
561 * we're not writing to the file system, but we use
562 * cprm.limit of 1 here as a speacial value, this is a
563 * consistent way to catch recursive crashes.
564 * We can still crash if the core_pattern binary sets
565 * RLIM_CORE = !1, but it runs as root, and can do
566 * lots of stupid things.
568 * Note that we use task_tgid_vnr here to grab the pid
569 * of the process group leader. That way we get the
570 * right pid if a thread in a multi-threaded
571 * core_pattern process dies.
574 "Process %d(%s) has RLIMIT_CORE set to 1\n",
575 task_tgid_vnr(current
), current
->comm
);
576 printk(KERN_WARNING
"Aborting core\n");
579 cprm
.limit
= RLIM_INFINITY
;
581 dump_count
= atomic_inc_return(&core_dump_count
);
582 if (core_pipe_limit
&& (core_pipe_limit
< dump_count
)) {
583 printk(KERN_WARNING
"Pid %d(%s) over core_pipe_limit\n",
584 task_tgid_vnr(current
), current
->comm
);
585 printk(KERN_WARNING
"Skipping core dump\n");
589 helper_argv
= argv_split(GFP_KERNEL
, cn
.corename
, NULL
);
591 printk(KERN_WARNING
"%s failed to allocate memory\n",
597 sub_info
= call_usermodehelper_setup(helper_argv
[0],
598 helper_argv
, NULL
, GFP_KERNEL
,
599 umh_pipe_setup
, NULL
, &cprm
);
601 retval
= call_usermodehelper_exec(sub_info
,
604 argv_free(helper_argv
);
606 printk(KERN_INFO
"Core dump to |%s pipe failed\n",
613 if (cprm
.limit
< binfmt
->min_coredump
)
616 if (need_nonrelative
&& cn
.corename
[0] != '/') {
617 printk(KERN_WARNING
"Pid %d(%s) can only dump core "\
618 "to fully qualified path!\n",
619 task_tgid_vnr(current
), current
->comm
);
620 printk(KERN_WARNING
"Skipping core dump\n");
624 cprm
.file
= filp_open(cn
.corename
,
625 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
627 if (IS_ERR(cprm
.file
))
630 inode
= file_inode(cprm
.file
);
631 if (inode
->i_nlink
> 1)
633 if (d_unhashed(cprm
.file
->f_path
.dentry
))
636 * AK: actually i see no reason to not allow this for named
637 * pipes etc, but keep the previous behaviour for now.
639 if (!S_ISREG(inode
->i_mode
))
642 * Dont allow local users get cute and trick others to coredump
643 * into their pre-created files.
645 if (!uid_eq(inode
->i_uid
, current_fsuid()))
647 if (!cprm
.file
->f_op
->write
)
649 if (do_truncate(cprm
.file
->f_path
.dentry
, 0, 0, cprm
.file
))
653 /* get us an unshared descriptor table; almost always a no-op */
654 retval
= unshare_files(&displaced
);
658 put_files_struct(displaced
);
659 if (!dump_interrupted()) {
660 file_start_write(cprm
.file
);
661 core_dumped
= binfmt
->core_dump(&cprm
);
662 file_end_write(cprm
.file
);
664 if (ispipe
&& core_pipe_limit
)
665 wait_for_dump_helpers(cprm
.file
);
668 filp_close(cprm
.file
, NULL
);
671 atomic_dec(&core_dump_count
);
674 coredump_finish(mm
, core_dumped
);
675 revert_creds(old_cred
);
683 * Core dumping helper functions. These are the only things you should
684 * do on a core-file: use only these functions to write out all the
687 int dump_emit(struct coredump_params
*cprm
, const void *addr
, int nr
)
689 struct file
*file
= cprm
->file
;
690 loff_t pos
= file
->f_pos
;
692 if (cprm
->written
+ nr
> cprm
->limit
)
695 if (dump_interrupted())
697 n
= __kernel_write(file
, addr
, nr
, &pos
);
706 EXPORT_SYMBOL(dump_emit
);
708 int dump_skip(struct coredump_params
*cprm
, size_t nr
)
710 static char zeroes
[PAGE_SIZE
];
711 struct file
*file
= cprm
->file
;
712 if (file
->f_op
->llseek
&& file
->f_op
->llseek
!= no_llseek
) {
713 if (cprm
->written
+ nr
> cprm
->limit
)
715 if (dump_interrupted() ||
716 file
->f_op
->llseek(file
, nr
, SEEK_CUR
) < 0)
721 while (nr
> PAGE_SIZE
) {
722 if (!dump_emit(cprm
, zeroes
, PAGE_SIZE
))
726 return dump_emit(cprm
, zeroes
, nr
);
729 EXPORT_SYMBOL(dump_skip
);
731 int dump_align(struct coredump_params
*cprm
, int align
)
733 unsigned mod
= cprm
->written
& (align
- 1);
734 if (align
& (align
- 1))
736 return mod
? dump_skip(cprm
, align
- mod
) : 1;
738 EXPORT_SYMBOL(dump_align
);