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>
45 #include <trace/events/sched.h>
48 unsigned int core_pipe_limit
;
49 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
50 static int core_name_size
= CORENAME_MAX_SIZE
;
57 /* The maximal length of core_pattern is also specified in sysctl.c */
59 static int expand_corename(struct core_name
*cn
, int size
)
61 char *corename
= krealloc(cn
->corename
, size
, GFP_KERNEL
);
66 if (size
> core_name_size
) /* racy but harmless */
67 core_name_size
= size
;
69 cn
->size
= ksize(corename
);
70 cn
->corename
= corename
;
74 static int cn_vprintf(struct core_name
*cn
, const char *fmt
, va_list arg
)
79 free
= cn
->size
- cn
->used
;
80 need
= vsnprintf(cn
->corename
+ cn
->used
, free
, fmt
, arg
);
86 if (!expand_corename(cn
, cn
->size
+ need
- free
+ 1))
92 static int cn_printf(struct core_name
*cn
, const char *fmt
, ...)
98 ret
= cn_vprintf(cn
, fmt
, arg
);
104 static int cn_esc_printf(struct core_name
*cn
, const char *fmt
, ...)
111 ret
= cn_vprintf(cn
, fmt
, arg
);
114 for (; cur
< cn
->used
; ++cur
) {
115 if (cn
->corename
[cur
] == '/')
116 cn
->corename
[cur
] = '!';
121 static int cn_print_exe_file(struct core_name
*cn
)
123 struct file
*exe_file
;
124 char *pathbuf
, *path
;
127 exe_file
= get_mm_exe_file(current
->mm
);
129 return cn_esc_printf(cn
, "%s (path unknown)", current
->comm
);
131 pathbuf
= kmalloc(PATH_MAX
, GFP_TEMPORARY
);
137 path
= d_path(&exe_file
->f_path
, pathbuf
, PATH_MAX
);
143 ret
= cn_esc_printf(cn
, "%s", path
);
152 /* format_corename will inspect the pattern parameter, and output a
153 * name into corename, which must have space for at least
154 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
156 static int format_corename(struct core_name
*cn
, struct coredump_params
*cprm
)
158 const struct cred
*cred
= current_cred();
159 const char *pat_ptr
= core_pattern
;
160 int ispipe
= (*pat_ptr
== '|');
161 int pid_in_pattern
= 0;
166 if (expand_corename(cn
, core_name_size
))
168 cn
->corename
[0] = '\0';
173 /* Repeat as long as we have more pattern to process and more output
176 if (*pat_ptr
!= '%') {
177 err
= cn_printf(cn
, "%c", *pat_ptr
++);
179 switch (*++pat_ptr
) {
180 /* single % at the end, drop that */
183 /* Double percent, output one percent */
185 err
= cn_printf(cn
, "%c", '%');
190 err
= cn_printf(cn
, "%d",
191 task_tgid_vnr(current
));
195 err
= cn_printf(cn
, "%d",
196 task_tgid_nr(current
));
200 err
= cn_printf(cn
, "%d", cred
->uid
);
204 err
= cn_printf(cn
, "%d", cred
->gid
);
207 err
= cn_printf(cn
, "%d",
208 __get_dumpable(cprm
->mm_flags
));
210 /* signal that caused the coredump */
212 err
= cn_printf(cn
, "%ld", cprm
->siginfo
->si_signo
);
214 /* UNIX time of coredump */
217 do_gettimeofday(&tv
);
218 err
= cn_printf(cn
, "%lu", tv
.tv_sec
);
224 err
= cn_esc_printf(cn
, "%s",
225 utsname()->nodename
);
230 err
= cn_esc_printf(cn
, "%s", current
->comm
);
233 err
= cn_print_exe_file(cn
);
235 /* core limit size */
237 err
= cn_printf(cn
, "%lu",
238 rlimit(RLIMIT_CORE
));
251 /* Backward compatibility with core_uses_pid:
253 * If core_pattern does not include a %p (as is the default)
254 * and core_uses_pid is set, then .%pid will be appended to
255 * the filename. Do not do this for piped commands. */
256 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
257 err
= cn_printf(cn
, ".%d", task_tgid_vnr(current
));
264 static int zap_process(struct task_struct
*start
, int exit_code
)
266 struct task_struct
*t
;
269 start
->signal
->group_exit_code
= exit_code
;
270 start
->signal
->group_stop_count
= 0;
274 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
275 if (t
!= current
&& t
->mm
) {
276 sigaddset(&t
->pending
.signal
, SIGKILL
);
277 signal_wake_up(t
, 1);
280 } while_each_thread(start
, t
);
285 static int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
286 struct core_state
*core_state
, int exit_code
)
288 struct task_struct
*g
, *p
;
292 spin_lock_irq(&tsk
->sighand
->siglock
);
293 if (!signal_group_exit(tsk
->signal
)) {
294 mm
->core_state
= core_state
;
295 nr
= zap_process(tsk
, exit_code
);
296 tsk
->signal
->group_exit_task
= tsk
;
297 /* ignore all signals except SIGKILL, see prepare_signal() */
298 tsk
->signal
->flags
= SIGNAL_GROUP_COREDUMP
;
299 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
301 spin_unlock_irq(&tsk
->sighand
->siglock
);
302 if (unlikely(nr
< 0))
305 tsk
->flags
= PF_DUMPCORE
;
306 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
309 * We should find and kill all tasks which use this mm, and we should
310 * count them correctly into ->nr_threads. We don't take tasklist
311 * lock, but this is safe wrt:
314 * None of sub-threads can fork after zap_process(leader). All
315 * processes which were created before this point should be
316 * visible to zap_threads() because copy_process() adds the new
317 * process to the tail of init_task.tasks list, and lock/unlock
318 * of ->siglock provides a memory barrier.
321 * The caller holds mm->mmap_sem. This means that the task which
322 * uses this mm can't pass exit_mm(), so it can't exit or clear
326 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
327 * we must see either old or new leader, this does not matter.
328 * However, it can change p->sighand, so lock_task_sighand(p)
329 * must be used. Since p->mm != NULL and we hold ->mmap_sem
332 * Note also that "g" can be the old leader with ->mm == NULL
333 * and already unhashed and thus removed from ->thread_group.
334 * This is OK, __unhash_process()->list_del_rcu() does not
335 * clear the ->next pointer, we will find the new leader via
339 for_each_process(g
) {
340 if (g
== tsk
->group_leader
)
342 if (g
->flags
& PF_KTHREAD
)
347 if (unlikely(p
->mm
== mm
)) {
348 lock_task_sighand(p
, &flags
);
349 nr
+= zap_process(p
, exit_code
);
350 p
->signal
->flags
= SIGNAL_GROUP_EXIT
;
351 unlock_task_sighand(p
, &flags
);
355 } while_each_thread(g
, p
);
359 atomic_set(&core_state
->nr_threads
, nr
);
363 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
365 struct task_struct
*tsk
= current
;
366 struct mm_struct
*mm
= tsk
->mm
;
367 int core_waiters
= -EBUSY
;
369 init_completion(&core_state
->startup
);
370 core_state
->dumper
.task
= tsk
;
371 core_state
->dumper
.next
= NULL
;
373 down_write(&mm
->mmap_sem
);
375 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
376 up_write(&mm
->mmap_sem
);
378 if (core_waiters
> 0) {
379 struct core_thread
*ptr
;
381 wait_for_completion(&core_state
->startup
);
383 * Wait for all the threads to become inactive, so that
384 * all the thread context (extended register state, like
385 * fpu etc) gets copied to the memory.
387 ptr
= core_state
->dumper
.next
;
388 while (ptr
!= NULL
) {
389 wait_task_inactive(ptr
->task
, 0);
397 static void coredump_finish(struct mm_struct
*mm
, bool core_dumped
)
399 struct core_thread
*curr
, *next
;
400 struct task_struct
*task
;
402 spin_lock_irq(¤t
->sighand
->siglock
);
403 if (core_dumped
&& !__fatal_signal_pending(current
))
404 current
->signal
->group_exit_code
|= 0x80;
405 current
->signal
->group_exit_task
= NULL
;
406 current
->signal
->flags
= SIGNAL_GROUP_EXIT
;
407 spin_unlock_irq(¤t
->sighand
->siglock
);
409 next
= mm
->core_state
->dumper
.next
;
410 while ((curr
= next
) != NULL
) {
414 * see exit_mm(), curr->task must not see
415 * ->task == NULL before we read ->next.
419 wake_up_process(task
);
422 mm
->core_state
= NULL
;
425 static bool dump_interrupted(void)
428 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
429 * can do try_to_freeze() and check __fatal_signal_pending(),
430 * but then we need to teach dump_write() to restart and clear
433 return signal_pending(current
);
436 static void wait_for_dump_helpers(struct file
*file
)
438 struct pipe_inode_info
*pipe
= file
->private_data
;
443 wake_up_interruptible_sync(&pipe
->wait
);
444 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
448 * We actually want wait_event_freezable() but then we need
449 * to clear TIF_SIGPENDING and improve dump_interrupted().
451 wait_event_interruptible(pipe
->wait
, pipe
->readers
== 1);
461 * helper function to customize the process used
462 * to collect the core in userspace. Specifically
463 * it sets up a pipe and installs it as fd 0 (stdin)
464 * for the process. Returns 0 on success, or
465 * PTR_ERR on failure.
466 * Note that it also sets the core limit to 1. This
467 * is a special value that we use to trap recursive
470 static int umh_pipe_setup(struct subprocess_info
*info
, struct cred
*new)
472 struct file
*files
[2];
473 struct coredump_params
*cp
= (struct coredump_params
*)info
->data
;
474 int err
= create_pipe_files(files
, 0);
480 err
= replace_fd(0, files
[0], 0);
482 /* and disallow core files too */
483 current
->signal
->rlim
[RLIMIT_CORE
] = (struct rlimit
){1, 1};
488 void do_coredump(const siginfo_t
*siginfo
)
490 struct core_state core_state
;
492 struct mm_struct
*mm
= current
->mm
;
493 struct linux_binfmt
* binfmt
;
494 const struct cred
*old_cred
;
499 struct files_struct
*displaced
;
500 bool need_nonrelative
= false;
501 bool core_dumped
= false;
502 static atomic_t core_dump_count
= ATOMIC_INIT(0);
503 struct coredump_params cprm
= {
505 .regs
= signal_pt_regs(),
506 .limit
= rlimit(RLIMIT_CORE
),
508 * We must use the same mm->flags while dumping core to avoid
509 * inconsistency of bit flags, since this flag is not protected
512 .mm_flags
= mm
->flags
,
515 audit_core_dumps(siginfo
->si_signo
);
518 if (!binfmt
|| !binfmt
->core_dump
)
520 if (!__get_dumpable(cprm
.mm_flags
))
523 cred
= prepare_creds();
527 * We cannot trust fsuid as being the "true" uid of the process
528 * nor do we know its entire history. We only know it was tainted
529 * so we dump it as root in mode 2, and only into a controlled
530 * environment (pipe handler or fully qualified path).
532 if (__get_dumpable(cprm
.mm_flags
) == SUID_DUMP_ROOT
) {
533 /* Setuid core dump mode */
534 flag
= O_EXCL
; /* Stop rewrite attacks */
535 cred
->fsuid
= GLOBAL_ROOT_UID
; /* Dump root private */
536 need_nonrelative
= true;
539 retval
= coredump_wait(siginfo
->si_signo
, &core_state
);
543 old_cred
= override_creds(cred
);
545 ispipe
= format_corename(&cn
, &cprm
);
550 struct subprocess_info
*sub_info
;
553 printk(KERN_WARNING
"format_corename failed\n");
554 printk(KERN_WARNING
"Aborting core\n");
558 if (cprm
.limit
== 1) {
559 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
561 * Normally core limits are irrelevant to pipes, since
562 * we're not writing to the file system, but we use
563 * cprm.limit of 1 here as a speacial value, this is a
564 * consistent way to catch recursive crashes.
565 * We can still crash if the core_pattern binary sets
566 * RLIM_CORE = !1, but it runs as root, and can do
567 * lots of stupid things.
569 * Note that we use task_tgid_vnr here to grab the pid
570 * of the process group leader. That way we get the
571 * right pid if a thread in a multi-threaded
572 * core_pattern process dies.
575 "Process %d(%s) has RLIMIT_CORE set to 1\n",
576 task_tgid_vnr(current
), current
->comm
);
577 printk(KERN_WARNING
"Aborting core\n");
580 cprm
.limit
= RLIM_INFINITY
;
582 dump_count
= atomic_inc_return(&core_dump_count
);
583 if (core_pipe_limit
&& (core_pipe_limit
< dump_count
)) {
584 printk(KERN_WARNING
"Pid %d(%s) over core_pipe_limit\n",
585 task_tgid_vnr(current
), current
->comm
);
586 printk(KERN_WARNING
"Skipping core dump\n");
590 helper_argv
= argv_split(GFP_KERNEL
, cn
.corename
, NULL
);
592 printk(KERN_WARNING
"%s failed to allocate memory\n",
598 sub_info
= call_usermodehelper_setup(helper_argv
[0],
599 helper_argv
, NULL
, GFP_KERNEL
,
600 umh_pipe_setup
, NULL
, &cprm
);
602 retval
= call_usermodehelper_exec(sub_info
,
605 argv_free(helper_argv
);
607 printk(KERN_INFO
"Core dump to |%s pipe failed\n",
614 if (cprm
.limit
< binfmt
->min_coredump
)
617 if (need_nonrelative
&& cn
.corename
[0] != '/') {
618 printk(KERN_WARNING
"Pid %d(%s) can only dump core "\
619 "to fully qualified path!\n",
620 task_tgid_vnr(current
), current
->comm
);
621 printk(KERN_WARNING
"Skipping core dump\n");
625 cprm
.file
= filp_open(cn
.corename
,
626 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
628 if (IS_ERR(cprm
.file
))
631 inode
= file_inode(cprm
.file
);
632 if (inode
->i_nlink
> 1)
634 if (d_unhashed(cprm
.file
->f_path
.dentry
))
637 * AK: actually i see no reason to not allow this for named
638 * pipes etc, but keep the previous behaviour for now.
640 if (!S_ISREG(inode
->i_mode
))
643 * Dont allow local users get cute and trick others to coredump
644 * into their pre-created files.
646 if (!uid_eq(inode
->i_uid
, current_fsuid()))
648 if (!cprm
.file
->f_op
->write
)
650 if (do_truncate(cprm
.file
->f_path
.dentry
, 0, 0, cprm
.file
))
654 /* get us an unshared descriptor table; almost always a no-op */
655 retval
= unshare_files(&displaced
);
659 put_files_struct(displaced
);
660 if (!dump_interrupted()) {
661 file_start_write(cprm
.file
);
662 core_dumped
= binfmt
->core_dump(&cprm
);
663 file_end_write(cprm
.file
);
665 if (ispipe
&& core_pipe_limit
)
666 wait_for_dump_helpers(cprm
.file
);
669 filp_close(cprm
.file
, NULL
);
672 atomic_dec(&core_dump_count
);
675 coredump_finish(mm
, core_dumped
);
676 revert_creds(old_cred
);
684 * Core dumping helper functions. These are the only things you should
685 * do on a core-file: use only these functions to write out all the
688 int dump_emit(struct coredump_params
*cprm
, const void *addr
, int nr
)
690 struct file
*file
= cprm
->file
;
691 loff_t pos
= file
->f_pos
;
693 if (cprm
->written
+ nr
> cprm
->limit
)
696 if (dump_interrupted())
698 n
= vfs_write(file
, addr
, nr
, &pos
);
707 EXPORT_SYMBOL(dump_emit
);
709 int dump_skip(struct coredump_params
*cprm
, size_t nr
)
711 static char zeroes
[PAGE_SIZE
];
712 struct file
*file
= cprm
->file
;
713 if (file
->f_op
->llseek
&& file
->f_op
->llseek
!= no_llseek
) {
714 if (cprm
->written
+ nr
> cprm
->limit
)
716 if (dump_interrupted() ||
717 file
->f_op
->llseek(file
, nr
, SEEK_CUR
) < 0)
722 while (nr
> PAGE_SIZE
) {
723 if (!dump_emit(cprm
, zeroes
, PAGE_SIZE
))
727 return dump_emit(cprm
, zeroes
, nr
);
730 EXPORT_SYMBOL(dump_skip
);
732 int dump_align(struct coredump_params
*cprm
, int align
)
734 unsigned mod
= cprm
->written
& (align
- 1);
735 if (align
& (align
- 1))
737 return mod
? dump_skip(cprm
, align
- mod
) : 0;
739 EXPORT_SYMBOL(dump_align
);