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/smp_lock.h>
18 #include <linux/ptrace.h>
19 #include <linux/security.h>
20 #include <linux/signal.h>
21 #include <linux/audit.h>
22 #include <linux/pid_namespace.h>
23 #include <linux/syscalls.h>
25 #include <asm/pgtable.h>
26 #include <asm/uaccess.h>
30 * Initialize a new task whose father had been ptraced.
32 * Called from copy_process().
34 void ptrace_fork(struct task_struct
*child
, unsigned long clone_flags
)
36 arch_ptrace_fork(child
, clone_flags
);
40 * ptrace a task: make the debugger its new parent and
41 * move it to the ptrace list.
43 * Must be called with the tasklist lock write-held.
45 void __ptrace_link(struct task_struct
*child
, struct task_struct
*new_parent
)
47 BUG_ON(!list_empty(&child
->ptrace_entry
));
48 list_add(&child
->ptrace_entry
, &new_parent
->ptraced
);
49 child
->parent
= new_parent
;
53 * Turn a tracing stop into a normal stop now, since with no tracer there
54 * would be no way to wake it up with SIGCONT or SIGKILL. If there was a
55 * signal sent that would resume the child, but didn't because it was in
56 * TASK_TRACED, resume it now.
57 * Requires that irqs be disabled.
59 static void ptrace_untrace(struct task_struct
*child
)
61 spin_lock(&child
->sighand
->siglock
);
62 if (task_is_traced(child
)) {
63 if (child
->signal
->flags
& SIGNAL_STOP_STOPPED
) {
64 __set_task_state(child
, TASK_STOPPED
);
66 signal_wake_up(child
, 1);
69 spin_unlock(&child
->sighand
->siglock
);
73 * unptrace a task: move it back to its original parent and
74 * remove it from the ptrace list.
76 * Must be called with the tasklist lock write-held.
78 void __ptrace_unlink(struct task_struct
*child
)
80 BUG_ON(!child
->ptrace
);
83 child
->parent
= child
->real_parent
;
84 list_del_init(&child
->ptrace_entry
);
86 arch_ptrace_untrace(child
);
87 if (task_is_traced(child
))
88 ptrace_untrace(child
);
92 * Check that we have indeed attached to the thing..
94 int ptrace_check_attach(struct task_struct
*child
, int kill
)
99 * We take the read lock around doing both checks to close a
100 * possible race where someone else was tracing our child and
101 * detached between these two checks. After this locked check,
102 * we are sure that this is our traced child and that can only
103 * be changed by us so it's not changing right after this.
105 read_lock(&tasklist_lock
);
106 if ((child
->ptrace
& PT_PTRACED
) && child
->parent
== current
) {
109 * child->sighand can't be NULL, release_task()
110 * does ptrace_unlink() before __exit_signal().
112 spin_lock_irq(&child
->sighand
->siglock
);
113 if (task_is_stopped(child
))
114 child
->state
= TASK_TRACED
;
115 else if (!task_is_traced(child
) && !kill
)
117 spin_unlock_irq(&child
->sighand
->siglock
);
119 read_unlock(&tasklist_lock
);
122 ret
= wait_task_inactive(child
, TASK_TRACED
) ? 0 : -ESRCH
;
124 /* All systems go.. */
128 int __ptrace_may_access(struct task_struct
*task
, unsigned int mode
)
130 /* May we inspect the given task?
131 * This check is used both for attaching with ptrace
132 * and for allowing access to sensitive information in /proc.
134 * ptrace_attach denies several cases that /proc allows
135 * because setting up the necessary parent/child relationship
136 * or halting the specified task is impossible.
139 /* Don't let security modules deny introspection */
142 if (((current
->uid
!= task
->euid
) ||
143 (current
->uid
!= task
->suid
) ||
144 (current
->uid
!= task
->uid
) ||
145 (current
->gid
!= task
->egid
) ||
146 (current
->gid
!= task
->sgid
) ||
147 (current
->gid
!= task
->gid
)) && !capable(CAP_SYS_PTRACE
))
151 dumpable
= get_dumpable(task
->mm
);
152 if (!dumpable
&& !capable(CAP_SYS_PTRACE
))
155 return security_ptrace_may_access(task
, mode
);
158 bool ptrace_may_access(struct task_struct
*task
, unsigned int mode
)
162 err
= __ptrace_may_access(task
, mode
);
164 return (!err
? true : false);
167 int ptrace_attach(struct task_struct
*task
)
175 if (same_thread_group(task
, current
))
182 * We want to hold both the task-lock and the
183 * tasklist_lock for writing at the same time.
184 * But that's against the rules (tasklist_lock
185 * is taken for reading by interrupts on other
186 * cpu's that may have task_lock).
189 if (!write_trylock_irqsave(&tasklist_lock
, flags
)) {
193 } while (!write_can_lock(&tasklist_lock
));
199 /* the same process cannot be attached many times */
200 if (task
->ptrace
& PT_PTRACED
)
202 retval
= __ptrace_may_access(task
, PTRACE_MODE_ATTACH
);
207 task
->ptrace
|= PT_PTRACED
;
208 if (capable(CAP_SYS_PTRACE
))
209 task
->ptrace
|= PT_PTRACE_CAP
;
211 __ptrace_link(task
, current
);
213 send_sig_info(SIGSTOP
, SEND_SIG_FORCED
, task
);
215 write_unlock_irqrestore(&tasklist_lock
, flags
);
221 static inline void __ptrace_detach(struct task_struct
*child
, unsigned int data
)
223 child
->exit_code
= data
;
224 /* .. re-parent .. */
225 __ptrace_unlink(child
);
226 /* .. and wake it up. */
227 if (child
->exit_state
!= EXIT_ZOMBIE
)
228 wake_up_process(child
);
231 int ptrace_detach(struct task_struct
*child
, unsigned int data
)
233 if (!valid_signal(data
))
236 /* Architecture-specific hardware disable .. */
237 ptrace_disable(child
);
238 clear_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
240 write_lock_irq(&tasklist_lock
);
241 /* protect against de_thread()->release_task() */
243 __ptrace_detach(child
, data
);
244 write_unlock_irq(&tasklist_lock
);
249 int ptrace_readdata(struct task_struct
*tsk
, unsigned long src
, char __user
*dst
, int len
)
255 int this_len
, retval
;
257 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
258 retval
= access_process_vm(tsk
, src
, buf
, this_len
, 0);
264 if (copy_to_user(dst
, buf
, retval
))
274 int ptrace_writedata(struct task_struct
*tsk
, char __user
*src
, unsigned long dst
, int len
)
280 int this_len
, retval
;
282 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
283 if (copy_from_user(buf
, src
, this_len
))
285 retval
= access_process_vm(tsk
, dst
, buf
, this_len
, 1);
299 static int ptrace_setoptions(struct task_struct
*child
, long data
)
301 child
->ptrace
&= ~PT_TRACE_MASK
;
303 if (data
& PTRACE_O_TRACESYSGOOD
)
304 child
->ptrace
|= PT_TRACESYSGOOD
;
306 if (data
& PTRACE_O_TRACEFORK
)
307 child
->ptrace
|= PT_TRACE_FORK
;
309 if (data
& PTRACE_O_TRACEVFORK
)
310 child
->ptrace
|= PT_TRACE_VFORK
;
312 if (data
& PTRACE_O_TRACECLONE
)
313 child
->ptrace
|= PT_TRACE_CLONE
;
315 if (data
& PTRACE_O_TRACEEXEC
)
316 child
->ptrace
|= PT_TRACE_EXEC
;
318 if (data
& PTRACE_O_TRACEVFORKDONE
)
319 child
->ptrace
|= PT_TRACE_VFORK_DONE
;
321 if (data
& PTRACE_O_TRACEEXIT
)
322 child
->ptrace
|= PT_TRACE_EXIT
;
324 return (data
& ~PTRACE_O_MASK
) ? -EINVAL
: 0;
327 static int ptrace_getsiginfo(struct task_struct
*child
, siginfo_t
*info
)
331 read_lock(&tasklist_lock
);
332 if (likely(child
->sighand
!= NULL
)) {
334 spin_lock_irq(&child
->sighand
->siglock
);
335 if (likely(child
->last_siginfo
!= NULL
)) {
336 *info
= *child
->last_siginfo
;
339 spin_unlock_irq(&child
->sighand
->siglock
);
341 read_unlock(&tasklist_lock
);
345 static int ptrace_setsiginfo(struct task_struct
*child
, const siginfo_t
*info
)
349 read_lock(&tasklist_lock
);
350 if (likely(child
->sighand
!= NULL
)) {
352 spin_lock_irq(&child
->sighand
->siglock
);
353 if (likely(child
->last_siginfo
!= NULL
)) {
354 *child
->last_siginfo
= *info
;
357 spin_unlock_irq(&child
->sighand
->siglock
);
359 read_unlock(&tasklist_lock
);
364 #ifdef PTRACE_SINGLESTEP
365 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
367 #define is_singlestep(request) 0
370 #ifdef PTRACE_SINGLEBLOCK
371 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
373 #define is_singleblock(request) 0
377 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
379 #define is_sysemu_singlestep(request) 0
382 static int ptrace_resume(struct task_struct
*child
, long request
, long data
)
384 if (!valid_signal(data
))
387 if (request
== PTRACE_SYSCALL
)
388 set_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
390 clear_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
392 #ifdef TIF_SYSCALL_EMU
393 if (request
== PTRACE_SYSEMU
|| request
== PTRACE_SYSEMU_SINGLESTEP
)
394 set_tsk_thread_flag(child
, TIF_SYSCALL_EMU
);
396 clear_tsk_thread_flag(child
, TIF_SYSCALL_EMU
);
399 if (is_singleblock(request
)) {
400 if (unlikely(!arch_has_block_step()))
402 user_enable_block_step(child
);
403 } else if (is_singlestep(request
) || is_sysemu_singlestep(request
)) {
404 if (unlikely(!arch_has_single_step()))
406 user_enable_single_step(child
);
409 user_disable_single_step(child
);
411 child
->exit_code
= data
;
412 wake_up_process(child
);
417 int ptrace_request(struct task_struct
*child
, long request
,
418 long addr
, long data
)
424 case PTRACE_PEEKTEXT
:
425 case PTRACE_PEEKDATA
:
426 return generic_ptrace_peekdata(child
, addr
, data
);
427 case PTRACE_POKETEXT
:
428 case PTRACE_POKEDATA
:
429 return generic_ptrace_pokedata(child
, addr
, data
);
431 #ifdef PTRACE_OLDSETOPTIONS
432 case PTRACE_OLDSETOPTIONS
:
434 case PTRACE_SETOPTIONS
:
435 ret
= ptrace_setoptions(child
, data
);
437 case PTRACE_GETEVENTMSG
:
438 ret
= put_user(child
->ptrace_message
, (unsigned long __user
*) data
);
441 case PTRACE_GETSIGINFO
:
442 ret
= ptrace_getsiginfo(child
, &siginfo
);
444 ret
= copy_siginfo_to_user((siginfo_t __user
*) data
,
448 case PTRACE_SETSIGINFO
:
449 if (copy_from_user(&siginfo
, (siginfo_t __user
*) data
,
453 ret
= ptrace_setsiginfo(child
, &siginfo
);
456 case PTRACE_DETACH
: /* detach a process that was attached. */
457 ret
= ptrace_detach(child
, data
);
460 #ifdef PTRACE_SINGLESTEP
461 case PTRACE_SINGLESTEP
:
463 #ifdef PTRACE_SINGLEBLOCK
464 case PTRACE_SINGLEBLOCK
:
468 case PTRACE_SYSEMU_SINGLESTEP
:
472 return ptrace_resume(child
, request
, data
);
475 if (child
->exit_state
) /* already dead */
477 return ptrace_resume(child
, request
, SIGKILL
);
487 * ptrace_traceme -- helper for PTRACE_TRACEME
489 * Performs checks and sets PT_PTRACED.
490 * Should be used by all ptrace implementations for PTRACE_TRACEME.
492 int ptrace_traceme(void)
497 * Are we already being traced?
501 if (!(current
->ptrace
& PT_PTRACED
)) {
503 * See ptrace_attach() comments about the locking here.
506 if (!write_trylock_irqsave(&tasklist_lock
, flags
)) {
507 task_unlock(current
);
510 } while (!write_can_lock(&tasklist_lock
));
514 ret
= security_ptrace_traceme(current
->parent
);
517 * Set the ptrace bit in the process ptrace flags.
518 * Then link us on our parent's ptraced list.
521 current
->ptrace
|= PT_PTRACED
;
522 __ptrace_link(current
, current
->real_parent
);
525 write_unlock_irqrestore(&tasklist_lock
, flags
);
527 task_unlock(current
);
532 * ptrace_get_task_struct -- grab a task struct reference for ptrace
533 * @pid: process id to grab a task_struct reference of
535 * This function is a helper for ptrace implementations. It checks
536 * permissions and then grabs a task struct for use of the actual
537 * ptrace implementation.
539 * Returns the task_struct for @pid or an ERR_PTR() on failure.
541 struct task_struct
*ptrace_get_task_struct(pid_t pid
)
543 struct task_struct
*child
;
545 read_lock(&tasklist_lock
);
546 child
= find_task_by_vpid(pid
);
548 get_task_struct(child
);
550 read_unlock(&tasklist_lock
);
552 return ERR_PTR(-ESRCH
);
556 #ifndef arch_ptrace_attach
557 #define arch_ptrace_attach(child) do { } while (0)
560 asmlinkage
long sys_ptrace(long request
, long pid
, long addr
, long data
)
562 struct task_struct
*child
;
566 * This lock_kernel fixes a subtle race with suid exec
569 if (request
== PTRACE_TRACEME
) {
570 ret
= ptrace_traceme();
572 arch_ptrace_attach(current
);
576 child
= ptrace_get_task_struct(pid
);
578 ret
= PTR_ERR(child
);
582 if (request
== PTRACE_ATTACH
) {
583 ret
= ptrace_attach(child
);
585 * Some architectures need to do book-keeping after
589 arch_ptrace_attach(child
);
590 goto out_put_task_struct
;
593 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
595 goto out_put_task_struct
;
597 ret
= arch_ptrace(child
, request
, addr
, data
);
599 goto out_put_task_struct
;
602 put_task_struct(child
);
608 int generic_ptrace_peekdata(struct task_struct
*tsk
, long addr
, long data
)
613 copied
= access_process_vm(tsk
, addr
, &tmp
, sizeof(tmp
), 0);
614 if (copied
!= sizeof(tmp
))
616 return put_user(tmp
, (unsigned long __user
*)data
);
619 int generic_ptrace_pokedata(struct task_struct
*tsk
, long addr
, long data
)
623 copied
= access_process_vm(tsk
, addr
, &data
, sizeof(data
), 1);
624 return (copied
== sizeof(data
)) ? 0 : -EIO
;
627 #if defined CONFIG_COMPAT
628 #include <linux/compat.h>
630 int compat_ptrace_request(struct task_struct
*child
, compat_long_t request
,
631 compat_ulong_t addr
, compat_ulong_t data
)
633 compat_ulong_t __user
*datap
= compat_ptr(data
);
639 case PTRACE_PEEKTEXT
:
640 case PTRACE_PEEKDATA
:
641 ret
= access_process_vm(child
, addr
, &word
, sizeof(word
), 0);
642 if (ret
!= sizeof(word
))
645 ret
= put_user(word
, datap
);
648 case PTRACE_POKETEXT
:
649 case PTRACE_POKEDATA
:
650 ret
= access_process_vm(child
, addr
, &data
, sizeof(data
), 1);
651 ret
= (ret
!= sizeof(data
) ? -EIO
: 0);
654 case PTRACE_GETEVENTMSG
:
655 ret
= put_user((compat_ulong_t
) child
->ptrace_message
, datap
);
658 case PTRACE_GETSIGINFO
:
659 ret
= ptrace_getsiginfo(child
, &siginfo
);
661 ret
= copy_siginfo_to_user32(
662 (struct compat_siginfo __user
*) datap
,
666 case PTRACE_SETSIGINFO
:
667 memset(&siginfo
, 0, sizeof siginfo
);
668 if (copy_siginfo_from_user32(
669 &siginfo
, (struct compat_siginfo __user
*) datap
))
672 ret
= ptrace_setsiginfo(child
, &siginfo
);
676 ret
= ptrace_request(child
, request
, addr
, data
);
682 asmlinkage
long compat_sys_ptrace(compat_long_t request
, compat_long_t pid
,
683 compat_long_t addr
, compat_long_t data
)
685 struct task_struct
*child
;
689 * This lock_kernel fixes a subtle race with suid exec
692 if (request
== PTRACE_TRACEME
) {
693 ret
= ptrace_traceme();
697 child
= ptrace_get_task_struct(pid
);
699 ret
= PTR_ERR(child
);
703 if (request
== PTRACE_ATTACH
) {
704 ret
= ptrace_attach(child
);
706 * Some architectures need to do book-keeping after
710 arch_ptrace_attach(child
);
711 goto out_put_task_struct
;
714 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
716 ret
= compat_arch_ptrace(child
, request
, addr
, data
);
719 put_task_struct(child
);
724 #endif /* CONFIG_COMPAT */