2b1d1f54e63066300b4579510c086b16bf648f84
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 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
49 unsigned int core_pipe_limit
;
55 static atomic_t call_count
= ATOMIC_INIT(1);
57 /* The maximal length of core_pattern is also specified in sysctl.c */
59 static int expand_corename(struct core_name
*cn
)
61 int size
= CORENAME_MAX_SIZE
* atomic_inc_return(&call_count
);
62 char *corename
= krealloc(cn
->corename
, size
, GFP_KERNEL
);
68 cn
->corename
= corename
;
72 static int cn_vprintf(struct core_name
*cn
, const char *fmt
, va_list arg
)
77 free
= cn
->size
- cn
->used
;
78 need
= vsnprintf(cn
->corename
+ cn
->used
, free
, fmt
, arg
);
84 if (!expand_corename(cn
))
90 static int cn_printf(struct core_name
*cn
, const char *fmt
, ...)
96 ret
= cn_vprintf(cn
, fmt
, arg
);
102 static void cn_escape(char *str
)
109 static int cn_print_exe_file(struct core_name
*cn
)
111 struct file
*exe_file
;
112 char *pathbuf
, *path
;
115 exe_file
= get_mm_exe_file(current
->mm
);
117 char *commstart
= cn
->corename
+ cn
->used
;
118 ret
= cn_printf(cn
, "%s (path unknown)", current
->comm
);
119 cn_escape(commstart
);
123 pathbuf
= kmalloc(PATH_MAX
, GFP_TEMPORARY
);
129 path
= d_path(&exe_file
->f_path
, pathbuf
, PATH_MAX
);
137 ret
= cn_printf(cn
, "%s", path
);
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.
150 static int format_corename(struct core_name
*cn
, struct coredump_params
*cprm
)
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;
159 cn
->size
= CORENAME_MAX_SIZE
* atomic_read(&call_count
);
160 cn
->corename
= kmalloc(cn
->size
, GFP_KERNEL
);
164 /* Repeat as long as we have more pattern to process and more output
167 if (*pat_ptr
!= '%') {
170 err
= cn_printf(cn
, "%c", *pat_ptr
++);
172 switch (*++pat_ptr
) {
173 /* single % at the end, drop that */
176 /* Double percent, output one percent */
178 err
= cn_printf(cn
, "%c", '%');
183 err
= cn_printf(cn
, "%d",
184 task_tgid_vnr(current
));
188 err
= cn_printf(cn
, "%d", cred
->uid
);
192 err
= cn_printf(cn
, "%d", cred
->gid
);
195 err
= cn_printf(cn
, "%d",
196 __get_dumpable(cprm
->mm_flags
));
198 /* signal that caused the coredump */
200 err
= cn_printf(cn
, "%ld", cprm
->siginfo
->si_signo
);
202 /* UNIX time of coredump */
205 do_gettimeofday(&tv
);
206 err
= cn_printf(cn
, "%lu", tv
.tv_sec
);
211 char *namestart
= cn
->corename
+ cn
->used
;
213 err
= cn_printf(cn
, "%s",
214 utsname()->nodename
);
216 cn_escape(namestart
);
221 char *commstart
= cn
->corename
+ cn
->used
;
222 err
= cn_printf(cn
, "%s", current
->comm
);
223 cn_escape(commstart
);
227 err
= cn_print_exe_file(cn
);
229 /* core limit size */
231 err
= cn_printf(cn
, "%lu",
232 rlimit(RLIMIT_CORE
));
244 /* Backward compatibility with core_uses_pid:
246 * If core_pattern does not include a %p (as is the default)
247 * and core_uses_pid is set, then .%pid will be appended to
248 * the filename. Do not do this for piped commands. */
249 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
250 err
= cn_printf(cn
, ".%d", task_tgid_vnr(current
));
258 static int zap_process(struct task_struct
*start
, int exit_code
)
260 struct task_struct
*t
;
263 start
->signal
->group_exit_code
= exit_code
;
264 start
->signal
->group_stop_count
= 0;
268 task_clear_jobctl_pending(t
, JOBCTL_PENDING_MASK
);
269 if (t
!= current
&& t
->mm
) {
270 sigaddset(&t
->pending
.signal
, SIGKILL
);
271 signal_wake_up(t
, 1);
274 } while_each_thread(start
, t
);
279 static int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
280 struct core_state
*core_state
, int exit_code
)
282 struct task_struct
*g
, *p
;
286 spin_lock_irq(&tsk
->sighand
->siglock
);
287 if (!signal_group_exit(tsk
->signal
)) {
288 mm
->core_state
= core_state
;
289 nr
= zap_process(tsk
, exit_code
);
290 tsk
->signal
->group_exit_task
= tsk
;
291 /* ignore all signals except SIGKILL, see prepare_signal() */
292 tsk
->signal
->flags
= SIGNAL_GROUP_COREDUMP
;
293 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
295 spin_unlock_irq(&tsk
->sighand
->siglock
);
296 if (unlikely(nr
< 0))
299 tsk
->flags
= PF_DUMPCORE
;
300 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
303 * We should find and kill all tasks which use this mm, and we should
304 * count them correctly into ->nr_threads. We don't take tasklist
305 * lock, but this is safe wrt:
308 * None of sub-threads can fork after zap_process(leader). All
309 * processes which were created before this point should be
310 * visible to zap_threads() because copy_process() adds the new
311 * process to the tail of init_task.tasks list, and lock/unlock
312 * of ->siglock provides a memory barrier.
315 * The caller holds mm->mmap_sem. This means that the task which
316 * uses this mm can't pass exit_mm(), so it can't exit or clear
320 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
321 * we must see either old or new leader, this does not matter.
322 * However, it can change p->sighand, so lock_task_sighand(p)
323 * must be used. Since p->mm != NULL and we hold ->mmap_sem
326 * Note also that "g" can be the old leader with ->mm == NULL
327 * and already unhashed and thus removed from ->thread_group.
328 * This is OK, __unhash_process()->list_del_rcu() does not
329 * clear the ->next pointer, we will find the new leader via
333 for_each_process(g
) {
334 if (g
== tsk
->group_leader
)
336 if (g
->flags
& PF_KTHREAD
)
341 if (unlikely(p
->mm
== mm
)) {
342 lock_task_sighand(p
, &flags
);
343 nr
+= zap_process(p
, exit_code
);
344 p
->signal
->flags
= SIGNAL_GROUP_EXIT
;
345 unlock_task_sighand(p
, &flags
);
349 } while_each_thread(g
, p
);
353 atomic_set(&core_state
->nr_threads
, nr
);
357 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
359 struct task_struct
*tsk
= current
;
360 struct mm_struct
*mm
= tsk
->mm
;
361 int core_waiters
= -EBUSY
;
363 init_completion(&core_state
->startup
);
364 core_state
->dumper
.task
= tsk
;
365 core_state
->dumper
.next
= NULL
;
367 down_write(&mm
->mmap_sem
);
369 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
370 up_write(&mm
->mmap_sem
);
372 if (core_waiters
> 0) {
373 struct core_thread
*ptr
;
375 wait_for_completion(&core_state
->startup
);
377 * Wait for all the threads to become inactive, so that
378 * all the thread context (extended register state, like
379 * fpu etc) gets copied to the memory.
381 ptr
= core_state
->dumper
.next
;
382 while (ptr
!= NULL
) {
383 wait_task_inactive(ptr
->task
, 0);
391 static void coredump_finish(struct mm_struct
*mm
, bool core_dumped
)
393 struct core_thread
*curr
, *next
;
394 struct task_struct
*task
;
396 spin_lock_irq(¤t
->sighand
->siglock
);
397 if (core_dumped
&& !__fatal_signal_pending(current
))
398 current
->signal
->group_exit_code
|= 0x80;
399 current
->signal
->group_exit_task
= NULL
;
400 current
->signal
->flags
= SIGNAL_GROUP_EXIT
;
401 spin_unlock_irq(¤t
->sighand
->siglock
);
403 next
= mm
->core_state
->dumper
.next
;
404 while ((curr
= next
) != NULL
) {
408 * see exit_mm(), curr->task must not see
409 * ->task == NULL before we read ->next.
413 wake_up_process(task
);
416 mm
->core_state
= NULL
;
419 static bool dump_interrupted(void)
422 * SIGKILL or freezing() interrupt the coredumping. Perhaps we
423 * can do try_to_freeze() and check __fatal_signal_pending(),
424 * but then we need to teach dump_write() to restart and clear
427 return signal_pending(current
);
430 static void wait_for_dump_helpers(struct file
*file
)
432 struct pipe_inode_info
*pipe
= file
->private_data
;
437 wake_up_interruptible_sync(&pipe
->wait
);
438 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
442 * We actually want wait_event_freezable() but then we need
443 * to clear TIF_SIGPENDING and improve dump_interrupted().
445 wait_event_interruptible(pipe
->wait
, pipe
->readers
== 1);
455 * helper function to customize the process used
456 * to collect the core in userspace. Specifically
457 * it sets up a pipe and installs it as fd 0 (stdin)
458 * for the process. Returns 0 on success, or
459 * PTR_ERR on failure.
460 * Note that it also sets the core limit to 1. This
461 * is a special value that we use to trap recursive
464 static int umh_pipe_setup(struct subprocess_info
*info
, struct cred
*new)
466 struct file
*files
[2];
467 struct coredump_params
*cp
= (struct coredump_params
*)info
->data
;
468 int err
= create_pipe_files(files
, 0);
474 err
= replace_fd(0, files
[0], 0);
476 /* and disallow core files too */
477 current
->signal
->rlim
[RLIMIT_CORE
] = (struct rlimit
){1, 1};
482 void do_coredump(siginfo_t
*siginfo
)
484 struct core_state core_state
;
486 struct mm_struct
*mm
= current
->mm
;
487 struct linux_binfmt
* binfmt
;
488 const struct cred
*old_cred
;
493 struct files_struct
*displaced
;
494 bool need_nonrelative
= false;
495 bool core_dumped
= false;
496 static atomic_t core_dump_count
= ATOMIC_INIT(0);
497 struct coredump_params cprm
= {
499 .regs
= signal_pt_regs(),
500 .limit
= rlimit(RLIMIT_CORE
),
502 * We must use the same mm->flags while dumping core to avoid
503 * inconsistency of bit flags, since this flag is not protected
506 .mm_flags
= mm
->flags
,
509 audit_core_dumps(siginfo
->si_signo
);
512 if (!binfmt
|| !binfmt
->core_dump
)
514 if (!__get_dumpable(cprm
.mm_flags
))
517 cred
= prepare_creds();
521 * We cannot trust fsuid as being the "true" uid of the process
522 * nor do we know its entire history. We only know it was tainted
523 * so we dump it as root in mode 2, and only into a controlled
524 * environment (pipe handler or fully qualified path).
526 if (__get_dumpable(cprm
.mm_flags
) == SUID_DUMP_ROOT
) {
527 /* Setuid core dump mode */
528 flag
= O_EXCL
; /* Stop rewrite attacks */
529 cred
->fsuid
= GLOBAL_ROOT_UID
; /* Dump root private */
530 need_nonrelative
= true;
533 retval
= coredump_wait(siginfo
->si_signo
, &core_state
);
537 old_cred
= override_creds(cred
);
539 ispipe
= format_corename(&cn
, &cprm
);
544 struct subprocess_info
*sub_info
;
547 printk(KERN_WARNING
"format_corename failed\n");
548 printk(KERN_WARNING
"Aborting core\n");
552 if (cprm
.limit
== 1) {
553 /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
555 * Normally core limits are irrelevant to pipes, since
556 * we're not writing to the file system, but we use
557 * cprm.limit of 1 here as a speacial value, this is a
558 * consistent way to catch recursive crashes.
559 * We can still crash if the core_pattern binary sets
560 * RLIM_CORE = !1, but it runs as root, and can do
561 * lots of stupid things.
563 * Note that we use task_tgid_vnr here to grab the pid
564 * of the process group leader. That way we get the
565 * right pid if a thread in a multi-threaded
566 * core_pattern process dies.
569 "Process %d(%s) has RLIMIT_CORE set to 1\n",
570 task_tgid_vnr(current
), current
->comm
);
571 printk(KERN_WARNING
"Aborting core\n");
574 cprm
.limit
= RLIM_INFINITY
;
576 dump_count
= atomic_inc_return(&core_dump_count
);
577 if (core_pipe_limit
&& (core_pipe_limit
< dump_count
)) {
578 printk(KERN_WARNING
"Pid %d(%s) over core_pipe_limit\n",
579 task_tgid_vnr(current
), current
->comm
);
580 printk(KERN_WARNING
"Skipping core dump\n");
584 helper_argv
= argv_split(GFP_KERNEL
, cn
.corename
+1, NULL
);
586 printk(KERN_WARNING
"%s failed to allocate memory\n",
592 sub_info
= call_usermodehelper_setup(helper_argv
[0],
593 helper_argv
, NULL
, GFP_KERNEL
,
594 umh_pipe_setup
, NULL
, &cprm
);
596 retval
= call_usermodehelper_exec(sub_info
,
599 argv_free(helper_argv
);
601 printk(KERN_INFO
"Core dump to %s pipe failed\n",
608 if (cprm
.limit
< binfmt
->min_coredump
)
611 if (need_nonrelative
&& cn
.corename
[0] != '/') {
612 printk(KERN_WARNING
"Pid %d(%s) can only dump core "\
613 "to fully qualified path!\n",
614 task_tgid_vnr(current
), current
->comm
);
615 printk(KERN_WARNING
"Skipping core dump\n");
619 cprm
.file
= filp_open(cn
.corename
,
620 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
622 if (IS_ERR(cprm
.file
))
625 inode
= file_inode(cprm
.file
);
626 if (inode
->i_nlink
> 1)
628 if (d_unhashed(cprm
.file
->f_path
.dentry
))
631 * AK: actually i see no reason to not allow this for named
632 * pipes etc, but keep the previous behaviour for now.
634 if (!S_ISREG(inode
->i_mode
))
637 * Dont allow local users get cute and trick others to coredump
638 * into their pre-created files.
640 if (!uid_eq(inode
->i_uid
, current_fsuid()))
642 if (!cprm
.file
->f_op
|| !cprm
.file
->f_op
->write
)
644 if (do_truncate(cprm
.file
->f_path
.dentry
, 0, 0, cprm
.file
))
648 /* get us an unshared descriptor table; almost always a no-op */
649 retval
= unshare_files(&displaced
);
653 put_files_struct(displaced
);
654 if (!dump_interrupted()) {
655 file_start_write(cprm
.file
);
656 core_dumped
= binfmt
->core_dump(&cprm
);
657 file_end_write(cprm
.file
);
659 if (ispipe
&& core_pipe_limit
)
660 wait_for_dump_helpers(cprm
.file
);
663 filp_close(cprm
.file
, NULL
);
666 atomic_dec(&core_dump_count
);
669 coredump_finish(mm
, core_dumped
);
670 revert_creds(old_cred
);
678 * Core dumping helper functions. These are the only things you should
679 * do on a core-file: use only these functions to write out all the
682 int dump_write(struct file
*file
, const void *addr
, int nr
)
684 return !dump_interrupted() &&
685 access_ok(VERIFY_READ
, addr
, nr
) &&
686 file
->f_op
->write(file
, addr
, nr
, &file
->f_pos
) == nr
;
688 EXPORT_SYMBOL(dump_write
);
690 int dump_seek(struct file
*file
, loff_t off
)
694 if (file
->f_op
->llseek
&& file
->f_op
->llseek
!= no_llseek
) {
695 if (dump_interrupted() ||
696 file
->f_op
->llseek(file
, off
, SEEK_CUR
) < 0)
699 char *buf
= (char *)get_zeroed_page(GFP_KERNEL
);
704 unsigned long n
= off
;
708 if (!dump_write(file
, buf
, n
)) {
714 free_page((unsigned long)buf
);
718 EXPORT_SYMBOL(dump_seek
);
This page took 0.087014 seconds and 4 git commands to generate.