]>
git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - fs/coredump.c
1 #include <linux/slab.h>
2 #include <linux/file.h>
3 #include <linux/fdtable.h>
4 #include <linux/freezer.h>
6 #include <linux/stat.h>
7 #include <linux/fcntl.h>
8 #include <linux/swap.h>
9 #include <linux/string.h>
10 #include <linux/init.h>
11 #include <linux/pagemap.h>
12 #include <linux/perf_event.h>
13 #include <linux/highmem.h>
14 #include <linux/spinlock.h>
15 #include <linux/key.h>
16 #include <linux/personality.h>
17 #include <linux/binfmts.h>
18 #include <linux/coredump.h>
19 #include <linux/sched/coredump.h>
20 #include <linux/sched/signal.h>
21 #include <linux/utsname.h>
22 #include <linux/pid_namespace.h>
23 #include <linux/module.h>
24 #include <linux/namei.h>
25 #include <linux/mount.h>
26 #include <linux/security.h>
27 #include <linux/syscalls.h>
28 #include <linux/tsacct_kern.h>
29 #include <linux/cn_proc.h>
30 #include <linux/audit.h>
31 #include <linux/tracehook.h>
32 #include <linux/kmod.h>
33 #include <linux/fsnotify.h>
34 #include <linux/fs_struct.h>
35 #include <linux/pipe_fs_i.h>
36 #include <linux/oom.h>
37 #include <linux/compat.h>
39 #include <linux/path.h>
40 #include <linux/timekeeping.h>
42 #include <linux/uaccess.h>
43 #include <asm/mmu_context.h>
47 #include <trace/events/task.h>
50 #include <trace/events/sched.h>
53 unsigned int core_pipe_limit
;
54 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
55 static int core_name_size
= CORENAME_MAX_SIZE
;
62 /* The maximal length of core_pattern is also specified in sysctl.c */
64 static int expand_corename(struct core_name
*cn
, int size
)
66 char *corename
= krealloc(cn
->corename
, size
, GFP_KERNEL
);
71 if (size
> core_name_size
) /* racy but harmless */
72 core_name_size
= size
;
74 cn
->size
= ksize(corename
);
75 cn
->corename
= corename
;
79 static __printf(2, 0) int cn_vprintf(struct core_name
*cn
, const char *fmt
,
86 free
= cn
->size
- cn
->used
;
88 va_copy(arg_copy
, arg
);
89 need
= vsnprintf(cn
->corename
+ cn
->used
, free
, fmt
, arg_copy
);
97 if (!expand_corename(cn
, cn
->size
+ need
- free
+ 1))
103 static __printf(2, 3) int cn_printf(struct core_name
*cn
, const char *fmt
, ...)
109 ret
= cn_vprintf(cn
, fmt
, arg
);
115 static __printf(2, 3)
116 int cn_esc_printf(struct core_name
*cn
, const char *fmt
, ...)
123 ret
= cn_vprintf(cn
, fmt
, arg
);
128 * Ensure that this coredump name component can't cause the
129 * resulting corefile path to consist of a ".." or ".".
131 if ((cn
->used
- cur
== 1 && cn
->corename
[cur
] == '.') ||
132 (cn
->used
- cur
== 2 && cn
->corename
[cur
] == '.'
133 && cn
->corename
[cur
+1] == '.'))
134 cn
->corename
[cur
] = '!';
137 * Empty names are fishy and could be used to create a "//" in a
138 * corefile name, causing the coredump to happen one directory
139 * level too high. Enforce that all components of the core
140 * pattern are at least one character long.
143 ret
= cn_printf(cn
, "!");
146 for (; cur
< cn
->used
; ++cur
) {
147 if (cn
->corename
[cur
] == '/')
148 cn
->corename
[cur
] = '!';
153 static int cn_print_exe_file(struct core_name
*cn
)
155 struct file
*exe_file
;
156 char *pathbuf
, *path
;
159 exe_file
= get_mm_exe_file(current
->mm
);
161 return cn_esc_printf(cn
, "%s (path unknown)", current
->comm
);
163 pathbuf
= kmalloc(PATH_MAX
, GFP_TEMPORARY
);
169 path
= file_path(exe_file
, pathbuf
, PATH_MAX
);
175 ret
= cn_esc_printf(cn
, "%s", path
);
184 /* format_corename will inspect the pattern parameter, and output a
185 * name into corename, which must have space for at least
186 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
188 static int format_corename(struct core_name
*cn
, struct coredump_params
*cprm
)
190 const struct cred
*cred
= current_cred();
191 const char *pat_ptr
= core_pattern
;
192 int ispipe
= (*pat_ptr
== '|');
193 int pid_in_pattern
= 0;
198 if (expand_corename(cn
, core_name_size
))
200 cn
->corename
[0] = '\0';
205 /* Repeat as long as we have more pattern to process and more output
208 if (*pat_ptr
!= '%') {
209 err
= cn_printf(cn
, "%c", *pat_ptr
++);
211 switch (*++pat_ptr
) {
212 /* single % at the end, drop that */
215 /* Double percent, output one percent */
217 err
= cn_printf(cn
, "%c", '%');
222 err
= cn_printf(cn
, "%d",
223 task_tgid_vnr(current
));
227 err
= cn_printf(cn
, "%d",
228 task_tgid_nr(current
));
231 err
= cn_printf(cn
, "%d",
232 task_pid_vnr(current
));
235 err
= cn_printf(cn
, "%d",
236 task_pid_nr(current
));
240 err
= cn_printf(cn
, "%u",
241 from_kuid(&init_user_ns
,
246 err
= cn_printf(cn
, "%u",
247 from_kgid(&init_user_ns
,
251 err
= cn_printf(cn
, "%d",
252 __get_dumpable(cprm
->mm_flags
));
254 /* signal that caused the coredump */
256 err
= cn_printf(cn
, "%d",
257 cprm
->siginfo
->si_signo
);
259 /* UNIX time of coredump */
263 time
= ktime_get_real_seconds();
264 err
= cn_printf(cn
, "%lld", time
);
270 err
= cn_esc_printf(cn
, "%s",
271 utsname()->nodename
);
276 err
= cn_esc_printf(cn
, "%s", current
->comm
);
279 err
= cn_print_exe_file(cn
);
281 /* core limit size */
283 err
= cn_printf(cn
, "%lu",
284 rlimit(RLIMIT_CORE
));
297 /* Backward compatibility with core_uses_pid:
299 * If core_pattern does not include a %p (as is the default)
300 * and core_uses_pid is set, then .%pid will be appended to
301 * the filename. Do not do this for piped commands. */
302 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
303 err
= cn_printf(cn
, ".%d", task_tgid_vnr(current
));
310 static int zap_process(struct task_struct
*start
, int exit_code
, int flags
)
312 struct task_struct
*t
;
315 /* ignore all signals except SIGKILL, see prepare_signal() */
316 start
->signal
->flags
= SIGNAL_GROUP_COREDUMP
| flags
;
317 start
->signal
->group_exit_code
= exit_code
;
318 start
->signal
->group_stop_count
= 0;
320 for_each_thread(start
, t
) {
321 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
322 if (t
!= current
&& t
->mm
) {
323 sigaddset(&t
->pending
.signal
, SIGKILL
);
324 signal_wake_up(t
, 1);
332 static int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
333 struct core_state
*core_state
, int exit_code
)
335 struct task_struct
*g
, *p
;
339 spin_lock_irq(&tsk
->sighand
->siglock
);
340 if (!signal_group_exit(tsk
->signal
)) {
341 mm
->core_state
= core_state
;
342 tsk
->signal
->group_exit_task
= tsk
;
343 nr
= zap_process(tsk
, exit_code
, 0);
344 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
346 spin_unlock_irq(&tsk
->sighand
->siglock
);
347 if (unlikely(nr
< 0))
350 tsk
->flags
|= PF_DUMPCORE
;
351 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
354 * We should find and kill all tasks which use this mm, and we should
355 * count them correctly into ->nr_threads. We don't take tasklist
356 * lock, but this is safe wrt:
359 * None of sub-threads can fork after zap_process(leader). All
360 * processes which were created before this point should be
361 * visible to zap_threads() because copy_process() adds the new
362 * process to the tail of init_task.tasks list, and lock/unlock
363 * of ->siglock provides a memory barrier.
366 * The caller holds mm->mmap_sem. This means that the task which
367 * uses this mm can't pass exit_mm(), so it can't exit or clear
371 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
372 * we must see either old or new leader, this does not matter.
373 * However, it can change p->sighand, so lock_task_sighand(p)
374 * must be used. Since p->mm != NULL and we hold ->mmap_sem
377 * Note also that "g" can be the old leader with ->mm == NULL
378 * and already unhashed and thus removed from ->thread_group.
379 * This is OK, __unhash_process()->list_del_rcu() does not
380 * clear the ->next pointer, we will find the new leader via
384 for_each_process(g
) {
385 if (g
== tsk
->group_leader
)
387 if (g
->flags
& PF_KTHREAD
)
390 for_each_thread(g
, p
) {
391 if (unlikely(!p
->mm
))
393 if (unlikely(p
->mm
== mm
)) {
394 lock_task_sighand(p
, &flags
);
395 nr
+= zap_process(p
, exit_code
,
397 unlock_task_sighand(p
, &flags
);
404 atomic_set(&core_state
->nr_threads
, nr
);
408 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
410 struct task_struct
*tsk
= current
;
411 struct mm_struct
*mm
= tsk
->mm
;
412 int core_waiters
= -EBUSY
;
414 init_completion(&core_state
->startup
);
415 core_state
->dumper
.task
= tsk
;
416 core_state
->dumper
.next
= NULL
;
418 if (down_write_killable(&mm
->mmap_sem
))
422 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
423 up_write(&mm
->mmap_sem
);
425 if (core_waiters
> 0) {
426 struct core_thread
*ptr
;
428 freezer_do_not_count();
429 wait_for_completion(&core_state
->startup
);
432 * Wait for all the threads to become inactive, so that
433 * all the thread context (extended register state, like
434 * fpu etc) gets copied to the memory.
436 ptr
= core_state
->dumper
.next
;
437 while (ptr
!= NULL
) {
438 wait_task_inactive(ptr
->task
, 0);
446 static void coredump_finish(struct mm_struct
*mm
, bool core_dumped
)
448 struct core_thread
*curr
, *next
;
449 struct task_struct
*task
;
451 spin_lock_irq(¤t
->sighand
->siglock
);
452 if (core_dumped
&& !__fatal_signal_pending(current
))
453 current
->signal
->group_exit_code
|= 0x80;
454 current
->signal
->group_exit_task
= NULL
;
455 current
->signal
->flags
= SIGNAL_GROUP_EXIT
;
456 spin_unlock_irq(¤t
->sighand
->siglock
);
458 next
= mm
->core_state
->dumper
.next
;
459 while ((curr
= next
) != NULL
) {
463 * see exit_mm(), curr->task must not see
464 * ->task == NULL before we read ->next.
468 wake_up_process(task
);
471 mm
->core_state
= NULL
;
474 static bool dump_interrupted(void)
477 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
478 * can do try_to_freeze() and check __fatal_signal_pending(),
479 * but then we need to teach dump_write() to restart and clear
482 return signal_pending(current
);
485 static void wait_for_dump_helpers(struct file
*file
)
487 struct pipe_inode_info
*pipe
= file
->private_data
;
492 wake_up_interruptible_sync(&pipe
->wait
);
493 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
497 * We actually want wait_event_freezable() but then we need
498 * to clear TIF_SIGPENDING and improve dump_interrupted().
500 wait_event_interruptible(pipe
->wait
, pipe
->readers
== 1);
510 * helper function to customize the process used
511 * to collect the core in userspace. Specifically
512 * it sets up a pipe and installs it as fd 0 (stdin)
513 * for the process. Returns 0 on success, or
514 * PTR_ERR on failure.
515 * Note that it also sets the core limit to 1. This
516 * is a special value that we use to trap recursive
519 static int umh_pipe_setup(struct subprocess_info
*info
, struct cred
*new)
521 struct file
*files
[2];
522 struct coredump_params
*cp
= (struct coredump_params
*)info
->data
;
523 int err
= create_pipe_files(files
, 0);
529 err
= replace_fd(0, files
[0], 0);
531 /* and disallow core files too */
532 current
->signal
->rlim
[RLIMIT_CORE
] = (struct rlimit
){1, 1};
537 void do_coredump(const siginfo_t
*siginfo
)
539 struct core_state core_state
;
541 struct mm_struct
*mm
= current
->mm
;
542 struct linux_binfmt
* binfmt
;
543 const struct cred
*old_cred
;
547 struct files_struct
*displaced
;
548 /* require nonrelative corefile path and be extra careful */
549 bool need_suid_safe
= false;
550 bool core_dumped
= false;
551 static atomic_t core_dump_count
= ATOMIC_INIT(0);
552 struct coredump_params cprm
= {
554 .regs
= signal_pt_regs(),
555 .limit
= rlimit(RLIMIT_CORE
),
557 * We must use the same mm->flags while dumping core to avoid
558 * inconsistency of bit flags, since this flag is not protected
561 .mm_flags
= mm
->flags
,
564 audit_core_dumps(siginfo
->si_signo
);
567 if (!binfmt
|| !binfmt
->core_dump
)
569 if (!__get_dumpable(cprm
.mm_flags
))
572 cred
= prepare_creds();
576 * We cannot trust fsuid as being the "true" uid of the process
577 * nor do we know its entire history. We only know it was tainted
578 * so we dump it as root in mode 2, and only into a controlled
579 * environment (pipe handler or fully qualified path).
581 if (__get_dumpable(cprm
.mm_flags
) == SUID_DUMP_ROOT
) {
582 /* Setuid core dump mode */
583 cred
->fsuid
= GLOBAL_ROOT_UID
; /* Dump root private */
584 need_suid_safe
= true;
587 retval
= coredump_wait(siginfo
->si_signo
, &core_state
);
591 old_cred
= override_creds(cred
);
593 ispipe
= format_corename(&cn
, &cprm
);
598 struct subprocess_info
*sub_info
;
601 printk(KERN_WARNING
"format_corename failed\n");
602 printk(KERN_WARNING
"Aborting core\n");
606 if (cprm
.limit
== 1) {
607 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
609 * Normally core limits are irrelevant to pipes, since
610 * we're not writing to the file system, but we use
611 * cprm.limit of 1 here as a special value, this is a
612 * consistent way to catch recursive crashes.
613 * We can still crash if the core_pattern binary sets
614 * RLIM_CORE = !1, but it runs as root, and can do
615 * lots of stupid things.
617 * Note that we use task_tgid_vnr here to grab the pid
618 * of the process group leader. That way we get the
619 * right pid if a thread in a multi-threaded
620 * core_pattern process dies.
623 "Process %d(%s) has RLIMIT_CORE set to 1\n",
624 task_tgid_vnr(current
), current
->comm
);
625 printk(KERN_WARNING
"Aborting core\n");
628 cprm
.limit
= RLIM_INFINITY
;
630 dump_count
= atomic_inc_return(&core_dump_count
);
631 if (core_pipe_limit
&& (core_pipe_limit
< dump_count
)) {
632 printk(KERN_WARNING
"Pid %d(%s) over core_pipe_limit\n",
633 task_tgid_vnr(current
), current
->comm
);
634 printk(KERN_WARNING
"Skipping core dump\n");
638 helper_argv
= argv_split(GFP_KERNEL
, cn
.corename
, NULL
);
640 printk(KERN_WARNING
"%s failed to allocate memory\n",
646 sub_info
= call_usermodehelper_setup(helper_argv
[0],
647 helper_argv
, NULL
, GFP_KERNEL
,
648 umh_pipe_setup
, NULL
, &cprm
);
650 retval
= call_usermodehelper_exec(sub_info
,
653 argv_free(helper_argv
);
655 printk(KERN_INFO
"Core dump to |%s pipe failed\n",
661 int open_flags
= O_CREAT
| O_RDWR
| O_NOFOLLOW
|
662 O_LARGEFILE
| O_EXCL
;
664 if (cprm
.limit
< binfmt
->min_coredump
)
667 if (need_suid_safe
&& cn
.corename
[0] != '/') {
668 printk(KERN_WARNING
"Pid %d(%s) can only dump core "\
669 "to fully qualified path!\n",
670 task_tgid_vnr(current
), current
->comm
);
671 printk(KERN_WARNING
"Skipping core dump\n");
676 * Unlink the file if it exists unless this is a SUID
677 * binary - in that case, we're running around with root
678 * privs and don't want to unlink another user's coredump.
680 if (!need_suid_safe
) {
686 * If it doesn't exist, that's fine. If there's some
687 * other problem, we'll catch it at the filp_open().
689 (void) sys_unlink((const char __user
*)cn
.corename
);
694 * There is a race between unlinking and creating the
695 * file, but if that causes an EEXIST here, that's
696 * fine - another process raced with us while creating
697 * the corefile, and the other process won. To userspace,
698 * what matters is that at least one of the two processes
699 * writes its coredump successfully, not which one.
701 if (need_suid_safe
) {
703 * Using user namespaces, normal user tasks can change
704 * their current->fs->root to point to arbitrary
705 * directories. Since the intention of the "only dump
706 * with a fully qualified path" rule is to control where
707 * coredumps may be placed using root privileges,
708 * current->fs->root must not be used. Instead, use the
709 * root directory of init_task.
713 task_lock(&init_task
);
714 get_fs_root(init_task
.fs
, &root
);
715 task_unlock(&init_task
);
716 cprm
.file
= file_open_root(root
.dentry
, root
.mnt
,
717 cn
.corename
, open_flags
, 0600);
720 cprm
.file
= filp_open(cn
.corename
, open_flags
, 0600);
722 if (IS_ERR(cprm
.file
))
725 inode
= file_inode(cprm
.file
);
726 if (inode
->i_nlink
> 1)
728 if (d_unhashed(cprm
.file
->f_path
.dentry
))
731 * AK: actually i see no reason to not allow this for named
732 * pipes etc, but keep the previous behaviour for now.
734 if (!S_ISREG(inode
->i_mode
))
737 * Don't dump core if the filesystem changed owner or mode
738 * of the file during file creation. This is an issue when
739 * a process dumps core while its cwd is e.g. on a vfat
742 if (!uid_eq(inode
->i_uid
, current_fsuid()))
744 if ((inode
->i_mode
& 0677) != 0600)
746 if (!(cprm
.file
->f_mode
& FMODE_CAN_WRITE
))
748 if (do_truncate(cprm
.file
->f_path
.dentry
, 0, 0, cprm
.file
))
752 /* get us an unshared descriptor table; almost always a no-op */
753 retval
= unshare_files(&displaced
);
757 put_files_struct(displaced
);
758 if (!dump_interrupted()) {
759 file_start_write(cprm
.file
);
760 core_dumped
= binfmt
->core_dump(&cprm
);
761 file_end_write(cprm
.file
);
763 if (ispipe
&& core_pipe_limit
)
764 wait_for_dump_helpers(cprm
.file
);
767 filp_close(cprm
.file
, NULL
);
770 atomic_dec(&core_dump_count
);
773 coredump_finish(mm
, core_dumped
);
774 revert_creds(old_cred
);
782 * Core dumping helper functions. These are the only things you should
783 * do on a core-file: use only these functions to write out all the
786 int dump_emit(struct coredump_params
*cprm
, const void *addr
, int nr
)
788 struct file
*file
= cprm
->file
;
789 loff_t pos
= file
->f_pos
;
791 if (cprm
->written
+ nr
> cprm
->limit
)
794 if (dump_interrupted())
796 n
= __kernel_write(file
, addr
, nr
, &pos
);
806 EXPORT_SYMBOL(dump_emit
);
808 int dump_skip(struct coredump_params
*cprm
, size_t nr
)
810 static char zeroes
[PAGE_SIZE
];
811 struct file
*file
= cprm
->file
;
812 if (file
->f_op
->llseek
&& file
->f_op
->llseek
!= no_llseek
) {
813 if (dump_interrupted() ||
814 file
->f_op
->llseek(file
, nr
, SEEK_CUR
) < 0)
819 while (nr
> PAGE_SIZE
) {
820 if (!dump_emit(cprm
, zeroes
, PAGE_SIZE
))
824 return dump_emit(cprm
, zeroes
, nr
);
827 EXPORT_SYMBOL(dump_skip
);
829 int dump_align(struct coredump_params
*cprm
, int align
)
831 unsigned mod
= cprm
->pos
& (align
- 1);
832 if (align
& (align
- 1))
834 return mod
? dump_skip(cprm
, align
- mod
) : 1;
836 EXPORT_SYMBOL(dump_align
);
839 * Ensures that file size is big enough to contain the current file
840 * postion. This prevents gdb from complaining about a truncated file
841 * if the last "write" to the file was dump_skip.
843 void dump_truncate(struct coredump_params
*cprm
)
845 struct file
*file
= cprm
->file
;
848 if (file
->f_op
->llseek
&& file
->f_op
->llseek
!= no_llseek
) {
849 offset
= file
->f_op
->llseek(file
, 0, SEEK_CUR
);
850 if (i_size_read(file
->f_mapping
->host
) < offset
)
851 do_truncate(file
->f_path
.dentry
, offset
, 0, file
);
854 EXPORT_SYMBOL(dump_truncate
);