2 * linux/kernel/ptrace.c
4 * (C) Copyright 1999 Linus Torvalds
6 * Common interfaces for "ptrace()" which we do not want
7 * to continually duplicate across every architecture.
10 #include <linux/capability.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/errno.h>
15 #include <linux/highmem.h>
16 #include <linux/pagemap.h>
17 #include <linux/ptrace.h>
18 #include <linux/security.h>
19 #include <linux/signal.h>
20 #include <linux/audit.h>
21 #include <linux/pid_namespace.h>
22 #include <linux/syscalls.h>
23 #include <linux/uaccess.h>
24 #include <linux/regset.h>
28 * ptrace a task: make the debugger its new parent and
29 * move it to the ptrace list.
31 * Must be called with the tasklist lock write-held.
33 void __ptrace_link(struct task_struct
*child
, struct task_struct
*new_parent
)
35 BUG_ON(!list_empty(&child
->ptrace_entry
));
36 list_add(&child
->ptrace_entry
, &new_parent
->ptraced
);
37 child
->parent
= new_parent
;
41 * Turn a tracing stop into a normal stop now, since with no tracer there
42 * would be no way to wake it up with SIGCONT or SIGKILL. If there was a
43 * signal sent that would resume the child, but didn't because it was in
44 * TASK_TRACED, resume it now.
45 * Requires that irqs be disabled.
47 static void ptrace_untrace(struct task_struct
*child
)
49 spin_lock(&child
->sighand
->siglock
);
50 if (task_is_traced(child
)) {
52 * If the group stop is completed or in progress,
53 * this thread was already counted as stopped.
55 if (child
->signal
->flags
& SIGNAL_STOP_STOPPED
||
56 child
->signal
->group_stop_count
)
57 __set_task_state(child
, TASK_STOPPED
);
59 signal_wake_up(child
, 1);
61 spin_unlock(&child
->sighand
->siglock
);
65 * unptrace a task: move it back to its original parent and
66 * remove it from the ptrace list.
68 * Must be called with the tasklist lock write-held.
70 void __ptrace_unlink(struct task_struct
*child
)
72 BUG_ON(!child
->ptrace
);
75 child
->parent
= child
->real_parent
;
76 list_del_init(&child
->ptrace_entry
);
78 if (task_is_traced(child
))
79 ptrace_untrace(child
);
83 * Check that we have indeed attached to the thing..
85 int ptrace_check_attach(struct task_struct
*child
, int kill
)
90 * We take the read lock around doing both checks to close a
91 * possible race where someone else was tracing our child and
92 * detached between these two checks. After this locked check,
93 * we are sure that this is our traced child and that can only
94 * be changed by us so it's not changing right after this.
96 read_lock(&tasklist_lock
);
97 if ((child
->ptrace
& PT_PTRACED
) && child
->parent
== current
) {
100 * child->sighand can't be NULL, release_task()
101 * does ptrace_unlink() before __exit_signal().
103 spin_lock_irq(&child
->sighand
->siglock
);
104 if (task_is_stopped(child
))
105 child
->state
= TASK_TRACED
;
106 else if (!task_is_traced(child
) && !kill
)
108 spin_unlock_irq(&child
->sighand
->siglock
);
110 read_unlock(&tasklist_lock
);
113 ret
= wait_task_inactive(child
, TASK_TRACED
) ? 0 : -ESRCH
;
115 /* All systems go.. */
119 int __ptrace_may_access(struct task_struct
*task
, unsigned int mode
)
121 const struct cred
*cred
= current_cred(), *tcred
;
123 /* May we inspect the given task?
124 * This check is used both for attaching with ptrace
125 * and for allowing access to sensitive information in /proc.
127 * ptrace_attach denies several cases that /proc allows
128 * because setting up the necessary parent/child relationship
129 * or halting the specified task is impossible.
132 /* Don't let security modules deny introspection */
136 tcred
= __task_cred(task
);
137 if ((cred
->uid
!= tcred
->euid
||
138 cred
->uid
!= tcred
->suid
||
139 cred
->uid
!= tcred
->uid
||
140 cred
->gid
!= tcred
->egid
||
141 cred
->gid
!= tcred
->sgid
||
142 cred
->gid
!= tcred
->gid
) &&
143 !capable(CAP_SYS_PTRACE
)) {
150 dumpable
= get_dumpable(task
->mm
);
151 if (!dumpable
&& !capable(CAP_SYS_PTRACE
))
154 return security_ptrace_access_check(task
, mode
);
157 bool ptrace_may_access(struct task_struct
*task
, unsigned int mode
)
161 err
= __ptrace_may_access(task
, mode
);
166 static int ptrace_attach(struct task_struct
*task
)
173 if (unlikely(task
->flags
& PF_KTHREAD
))
175 if (same_thread_group(task
, current
))
179 * Protect exec's credential calculations against our interference;
180 * interference; SUID, SGID and LSM creds get determined differently
183 retval
= -ERESTARTNOINTR
;
184 if (mutex_lock_interruptible(&task
->signal
->cred_guard_mutex
))
188 retval
= __ptrace_may_access(task
, PTRACE_MODE_ATTACH
);
193 write_lock_irq(&tasklist_lock
);
195 if (unlikely(task
->exit_state
))
196 goto unlock_tasklist
;
198 goto unlock_tasklist
;
200 task
->ptrace
= PT_PTRACED
;
201 if (capable(CAP_SYS_PTRACE
))
202 task
->ptrace
|= PT_PTRACE_CAP
;
204 __ptrace_link(task
, current
);
205 send_sig_info(SIGSTOP
, SEND_SIG_FORCED
, task
);
209 write_unlock_irq(&tasklist_lock
);
211 mutex_unlock(&task
->signal
->cred_guard_mutex
);
217 * ptrace_traceme -- helper for PTRACE_TRACEME
219 * Performs checks and sets PT_PTRACED.
220 * Should be used by all ptrace implementations for PTRACE_TRACEME.
222 static int ptrace_traceme(void)
226 write_lock_irq(&tasklist_lock
);
227 /* Are we already being traced? */
228 if (!current
->ptrace
) {
229 ret
= security_ptrace_traceme(current
->parent
);
231 * Check PF_EXITING to ensure ->real_parent has not passed
232 * exit_ptrace(). Otherwise we don't report the error but
233 * pretend ->real_parent untraces us right after return.
235 if (!ret
&& !(current
->real_parent
->flags
& PF_EXITING
)) {
236 current
->ptrace
= PT_PTRACED
;
237 __ptrace_link(current
, current
->real_parent
);
240 write_unlock_irq(&tasklist_lock
);
246 * Called with irqs disabled, returns true if childs should reap themselves.
248 static int ignoring_children(struct sighand_struct
*sigh
)
251 spin_lock(&sigh
->siglock
);
252 ret
= (sigh
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
) ||
253 (sigh
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
);
254 spin_unlock(&sigh
->siglock
);
259 * Called with tasklist_lock held for writing.
260 * Unlink a traced task, and clean it up if it was a traced zombie.
261 * Return true if it needs to be reaped with release_task().
262 * (We can't call release_task() here because we already hold tasklist_lock.)
264 * If it's a zombie, our attachedness prevented normal parent notification
265 * or self-reaping. Do notification now if it would have happened earlier.
266 * If it should reap itself, return true.
268 * If it's our own child, there is no notification to do. But if our normal
269 * children self-reap, then this child was prevented by ptrace and we must
270 * reap it now, in that case we must also wake up sub-threads sleeping in
273 static bool __ptrace_detach(struct task_struct
*tracer
, struct task_struct
*p
)
277 if (p
->exit_state
== EXIT_ZOMBIE
) {
278 if (!task_detached(p
) && thread_group_empty(p
)) {
279 if (!same_thread_group(p
->real_parent
, tracer
))
280 do_notify_parent(p
, p
->exit_signal
);
281 else if (ignoring_children(tracer
->sighand
)) {
282 __wake_up_parent(p
, tracer
);
286 if (task_detached(p
)) {
287 /* Mark it as in the process of being reaped. */
288 p
->exit_state
= EXIT_DEAD
;
296 static int ptrace_detach(struct task_struct
*child
, unsigned int data
)
300 if (!valid_signal(data
))
303 /* Architecture-specific hardware disable .. */
304 ptrace_disable(child
);
305 clear_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
307 write_lock_irq(&tasklist_lock
);
309 * This child can be already killed. Make sure de_thread() or
310 * our sub-thread doing do_wait() didn't do release_task() yet.
313 child
->exit_code
= data
;
314 dead
= __ptrace_detach(current
, child
);
316 write_unlock_irq(&tasklist_lock
);
325 * Detach all tasks we were using ptrace on. Called with tasklist held
326 * for writing, and returns with it held too. But note it can release
327 * and reacquire the lock.
329 void exit_ptrace(struct task_struct
*tracer
)
330 __releases(&tasklist_lock
)
331 __acquires(&tasklist_lock
)
333 struct task_struct
*p
, *n
;
334 LIST_HEAD(ptrace_dead
);
336 if (likely(list_empty(&tracer
->ptraced
)))
339 list_for_each_entry_safe(p
, n
, &tracer
->ptraced
, ptrace_entry
) {
340 if (__ptrace_detach(tracer
, p
))
341 list_add(&p
->ptrace_entry
, &ptrace_dead
);
344 write_unlock_irq(&tasklist_lock
);
345 BUG_ON(!list_empty(&tracer
->ptraced
));
347 list_for_each_entry_safe(p
, n
, &ptrace_dead
, ptrace_entry
) {
348 list_del_init(&p
->ptrace_entry
);
352 write_lock_irq(&tasklist_lock
);
355 int ptrace_readdata(struct task_struct
*tsk
, unsigned long src
, char __user
*dst
, int len
)
361 int this_len
, retval
;
363 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
364 retval
= access_process_vm(tsk
, src
, buf
, this_len
, 0);
370 if (copy_to_user(dst
, buf
, retval
))
380 int ptrace_writedata(struct task_struct
*tsk
, char __user
*src
, unsigned long dst
, int len
)
386 int this_len
, retval
;
388 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
389 if (copy_from_user(buf
, src
, this_len
))
391 retval
= access_process_vm(tsk
, dst
, buf
, this_len
, 1);
405 static int ptrace_setoptions(struct task_struct
*child
, unsigned long data
)
407 child
->ptrace
&= ~PT_TRACE_MASK
;
409 if (data
& PTRACE_O_TRACESYSGOOD
)
410 child
->ptrace
|= PT_TRACESYSGOOD
;
412 if (data
& PTRACE_O_TRACEFORK
)
413 child
->ptrace
|= PT_TRACE_FORK
;
415 if (data
& PTRACE_O_TRACEVFORK
)
416 child
->ptrace
|= PT_TRACE_VFORK
;
418 if (data
& PTRACE_O_TRACECLONE
)
419 child
->ptrace
|= PT_TRACE_CLONE
;
421 if (data
& PTRACE_O_TRACEEXEC
)
422 child
->ptrace
|= PT_TRACE_EXEC
;
424 if (data
& PTRACE_O_TRACEVFORKDONE
)
425 child
->ptrace
|= PT_TRACE_VFORK_DONE
;
427 if (data
& PTRACE_O_TRACEEXIT
)
428 child
->ptrace
|= PT_TRACE_EXIT
;
430 return (data
& ~PTRACE_O_MASK
) ? -EINVAL
: 0;
433 static int ptrace_getsiginfo(struct task_struct
*child
, siginfo_t
*info
)
438 if (lock_task_sighand(child
, &flags
)) {
440 if (likely(child
->last_siginfo
!= NULL
)) {
441 *info
= *child
->last_siginfo
;
444 unlock_task_sighand(child
, &flags
);
449 static int ptrace_setsiginfo(struct task_struct
*child
, const siginfo_t
*info
)
454 if (lock_task_sighand(child
, &flags
)) {
456 if (likely(child
->last_siginfo
!= NULL
)) {
457 *child
->last_siginfo
= *info
;
460 unlock_task_sighand(child
, &flags
);
466 #ifdef PTRACE_SINGLESTEP
467 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
469 #define is_singlestep(request) 0
472 #ifdef PTRACE_SINGLEBLOCK
473 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
475 #define is_singleblock(request) 0
479 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
481 #define is_sysemu_singlestep(request) 0
484 static int ptrace_resume(struct task_struct
*child
, long request
,
487 if (!valid_signal(data
))
490 if (request
== PTRACE_SYSCALL
)
491 set_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
493 clear_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
495 #ifdef TIF_SYSCALL_EMU
496 if (request
== PTRACE_SYSEMU
|| request
== PTRACE_SYSEMU_SINGLESTEP
)
497 set_tsk_thread_flag(child
, TIF_SYSCALL_EMU
);
499 clear_tsk_thread_flag(child
, TIF_SYSCALL_EMU
);
502 if (is_singleblock(request
)) {
503 if (unlikely(!arch_has_block_step()))
505 user_enable_block_step(child
);
506 } else if (is_singlestep(request
) || is_sysemu_singlestep(request
)) {
507 if (unlikely(!arch_has_single_step()))
509 user_enable_single_step(child
);
511 user_disable_single_step(child
);
514 child
->exit_code
= data
;
515 wake_up_process(child
);
520 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
522 static const struct user_regset
*
523 find_regset(const struct user_regset_view
*view
, unsigned int type
)
525 const struct user_regset
*regset
;
528 for (n
= 0; n
< view
->n
; ++n
) {
529 regset
= view
->regsets
+ n
;
530 if (regset
->core_note_type
== type
)
537 static int ptrace_regset(struct task_struct
*task
, int req
, unsigned int type
,
540 const struct user_regset_view
*view
= task_user_regset_view(task
);
541 const struct user_regset
*regset
= find_regset(view
, type
);
544 if (!regset
|| (kiov
->iov_len
% regset
->size
) != 0)
547 regset_no
= regset
- view
->regsets
;
548 kiov
->iov_len
= min(kiov
->iov_len
,
549 (__kernel_size_t
) (regset
->n
* regset
->size
));
551 if (req
== PTRACE_GETREGSET
)
552 return copy_regset_to_user(task
, view
, regset_no
, 0,
553 kiov
->iov_len
, kiov
->iov_base
);
555 return copy_regset_from_user(task
, view
, regset_no
, 0,
556 kiov
->iov_len
, kiov
->iov_base
);
561 int ptrace_request(struct task_struct
*child
, long request
,
562 unsigned long addr
, unsigned long data
)
566 void __user
*datavp
= (void __user
*) data
;
567 unsigned long __user
*datalp
= datavp
;
570 case PTRACE_PEEKTEXT
:
571 case PTRACE_PEEKDATA
:
572 return generic_ptrace_peekdata(child
, addr
, data
);
573 case PTRACE_POKETEXT
:
574 case PTRACE_POKEDATA
:
575 return generic_ptrace_pokedata(child
, addr
, data
);
577 #ifdef PTRACE_OLDSETOPTIONS
578 case PTRACE_OLDSETOPTIONS
:
580 case PTRACE_SETOPTIONS
:
581 ret
= ptrace_setoptions(child
, data
);
583 case PTRACE_GETEVENTMSG
:
584 ret
= put_user(child
->ptrace_message
, datalp
);
587 case PTRACE_GETSIGINFO
:
588 ret
= ptrace_getsiginfo(child
, &siginfo
);
590 ret
= copy_siginfo_to_user(datavp
, &siginfo
);
593 case PTRACE_SETSIGINFO
:
594 if (copy_from_user(&siginfo
, datavp
, sizeof siginfo
))
597 ret
= ptrace_setsiginfo(child
, &siginfo
);
600 case PTRACE_DETACH
: /* detach a process that was attached. */
601 ret
= ptrace_detach(child
, data
);
604 #ifdef CONFIG_BINFMT_ELF_FDPIC
605 case PTRACE_GETFDPIC
: {
606 struct mm_struct
*mm
= get_task_mm(child
);
607 unsigned long tmp
= 0;
614 case PTRACE_GETFDPIC_EXEC
:
615 tmp
= mm
->context
.exec_fdpic_loadmap
;
617 case PTRACE_GETFDPIC_INTERP
:
618 tmp
= mm
->context
.interp_fdpic_loadmap
;
625 ret
= put_user(tmp
, datalp
);
630 #ifdef PTRACE_SINGLESTEP
631 case PTRACE_SINGLESTEP
:
633 #ifdef PTRACE_SINGLEBLOCK
634 case PTRACE_SINGLEBLOCK
:
638 case PTRACE_SYSEMU_SINGLESTEP
:
642 return ptrace_resume(child
, request
, data
);
645 if (child
->exit_state
) /* already dead */
647 return ptrace_resume(child
, request
, SIGKILL
);
649 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
650 case PTRACE_GETREGSET
:
651 case PTRACE_SETREGSET
:
654 struct iovec __user
*uiov
= datavp
;
656 if (!access_ok(VERIFY_WRITE
, uiov
, sizeof(*uiov
)))
659 if (__get_user(kiov
.iov_base
, &uiov
->iov_base
) ||
660 __get_user(kiov
.iov_len
, &uiov
->iov_len
))
663 ret
= ptrace_regset(child
, request
, addr
, &kiov
);
665 ret
= __put_user(kiov
.iov_len
, &uiov
->iov_len
);
676 static struct task_struct
*ptrace_get_task_struct(pid_t pid
)
678 struct task_struct
*child
;
681 child
= find_task_by_vpid(pid
);
683 get_task_struct(child
);
687 return ERR_PTR(-ESRCH
);
691 #ifndef arch_ptrace_attach
692 #define arch_ptrace_attach(child) do { } while (0)
695 SYSCALL_DEFINE4(ptrace
, long, request
, long, pid
, unsigned long, addr
,
698 struct task_struct
*child
;
701 if (request
== PTRACE_TRACEME
) {
702 ret
= ptrace_traceme();
704 arch_ptrace_attach(current
);
708 child
= ptrace_get_task_struct(pid
);
710 ret
= PTR_ERR(child
);
714 if (request
== PTRACE_ATTACH
) {
715 ret
= ptrace_attach(child
);
717 * Some architectures need to do book-keeping after
721 arch_ptrace_attach(child
);
722 goto out_put_task_struct
;
725 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
727 goto out_put_task_struct
;
729 ret
= arch_ptrace(child
, request
, addr
, data
);
732 put_task_struct(child
);
737 int generic_ptrace_peekdata(struct task_struct
*tsk
, unsigned long addr
,
743 copied
= access_process_vm(tsk
, addr
, &tmp
, sizeof(tmp
), 0);
744 if (copied
!= sizeof(tmp
))
746 return put_user(tmp
, (unsigned long __user
*)data
);
749 int generic_ptrace_pokedata(struct task_struct
*tsk
, unsigned long addr
,
754 copied
= access_process_vm(tsk
, addr
, &data
, sizeof(data
), 1);
755 return (copied
== sizeof(data
)) ? 0 : -EIO
;
758 #if defined CONFIG_COMPAT
759 #include <linux/compat.h>
761 int compat_ptrace_request(struct task_struct
*child
, compat_long_t request
,
762 compat_ulong_t addr
, compat_ulong_t data
)
764 compat_ulong_t __user
*datap
= compat_ptr(data
);
770 case PTRACE_PEEKTEXT
:
771 case PTRACE_PEEKDATA
:
772 ret
= access_process_vm(child
, addr
, &word
, sizeof(word
), 0);
773 if (ret
!= sizeof(word
))
776 ret
= put_user(word
, datap
);
779 case PTRACE_POKETEXT
:
780 case PTRACE_POKEDATA
:
781 ret
= access_process_vm(child
, addr
, &data
, sizeof(data
), 1);
782 ret
= (ret
!= sizeof(data
) ? -EIO
: 0);
785 case PTRACE_GETEVENTMSG
:
786 ret
= put_user((compat_ulong_t
) child
->ptrace_message
, datap
);
789 case PTRACE_GETSIGINFO
:
790 ret
= ptrace_getsiginfo(child
, &siginfo
);
792 ret
= copy_siginfo_to_user32(
793 (struct compat_siginfo __user
*) datap
,
797 case PTRACE_SETSIGINFO
:
798 memset(&siginfo
, 0, sizeof siginfo
);
799 if (copy_siginfo_from_user32(
800 &siginfo
, (struct compat_siginfo __user
*) datap
))
803 ret
= ptrace_setsiginfo(child
, &siginfo
);
805 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
806 case PTRACE_GETREGSET
:
807 case PTRACE_SETREGSET
:
810 struct compat_iovec __user
*uiov
=
811 (struct compat_iovec __user
*) datap
;
815 if (!access_ok(VERIFY_WRITE
, uiov
, sizeof(*uiov
)))
818 if (__get_user(ptr
, &uiov
->iov_base
) ||
819 __get_user(len
, &uiov
->iov_len
))
822 kiov
.iov_base
= compat_ptr(ptr
);
825 ret
= ptrace_regset(child
, request
, addr
, &kiov
);
827 ret
= __put_user(kiov
.iov_len
, &uiov
->iov_len
);
833 ret
= ptrace_request(child
, request
, addr
, data
);
839 asmlinkage
long compat_sys_ptrace(compat_long_t request
, compat_long_t pid
,
840 compat_long_t addr
, compat_long_t data
)
842 struct task_struct
*child
;
845 if (request
== PTRACE_TRACEME
) {
846 ret
= ptrace_traceme();
850 child
= ptrace_get_task_struct(pid
);
852 ret
= PTR_ERR(child
);
856 if (request
== PTRACE_ATTACH
) {
857 ret
= ptrace_attach(child
);
859 * Some architectures need to do book-keeping after
863 arch_ptrace_attach(child
);
864 goto out_put_task_struct
;
867 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
869 ret
= compat_arch_ptrace(child
, request
, addr
, data
);
872 put_task_struct(child
);
876 #endif /* CONFIG_COMPAT */