]>
git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - kernel/ptrace.c
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>
24 #include <linux/uaccess.h>
28 * Initialize a new task whose father had been ptraced.
30 * Called from copy_process().
32 void ptrace_fork(struct task_struct
*child
, unsigned long clone_flags
)
34 arch_ptrace_fork(child
, clone_flags
);
38 * ptrace a task: make the debugger its new parent and
39 * move it to the ptrace list.
41 * Must be called with the tasklist lock write-held.
43 void __ptrace_link(struct task_struct
*child
, struct task_struct
*new_parent
)
45 BUG_ON(!list_empty(&child
->ptrace_entry
));
46 list_add(&child
->ptrace_entry
, &new_parent
->ptraced
);
47 child
->parent
= new_parent
;
51 * Turn a tracing stop into a normal stop now, since with no tracer there
52 * would be no way to wake it up with SIGCONT or SIGKILL. If there was a
53 * signal sent that would resume the child, but didn't because it was in
54 * TASK_TRACED, resume it now.
55 * Requires that irqs be disabled.
57 static void ptrace_untrace(struct task_struct
*child
)
59 spin_lock(&child
->sighand
->siglock
);
60 if (task_is_traced(child
)) {
62 * If the group stop is completed or in progress,
63 * this thread was already counted as stopped.
65 if (child
->signal
->flags
& SIGNAL_STOP_STOPPED
||
66 child
->signal
->group_stop_count
)
67 __set_task_state(child
, TASK_STOPPED
);
69 signal_wake_up(child
, 1);
71 spin_unlock(&child
->sighand
->siglock
);
75 * unptrace a task: move it back to its original parent and
76 * remove it from the ptrace list.
78 * Must be called with the tasklist lock write-held.
80 void __ptrace_unlink(struct task_struct
*child
)
82 BUG_ON(!child
->ptrace
);
85 child
->parent
= child
->real_parent
;
86 list_del_init(&child
->ptrace_entry
);
88 arch_ptrace_untrace(child
);
89 if (task_is_traced(child
))
90 ptrace_untrace(child
);
94 * Check that we have indeed attached to the thing..
96 int ptrace_check_attach(struct task_struct
*child
, int kill
)
101 * We take the read lock around doing both checks to close a
102 * possible race where someone else was tracing our child and
103 * detached between these two checks. After this locked check,
104 * we are sure that this is our traced child and that can only
105 * be changed by us so it's not changing right after this.
107 read_lock(&tasklist_lock
);
108 if ((child
->ptrace
& PT_PTRACED
) && child
->parent
== current
) {
111 * child->sighand can't be NULL, release_task()
112 * does ptrace_unlink() before __exit_signal().
114 spin_lock_irq(&child
->sighand
->siglock
);
115 if (task_is_stopped(child
))
116 child
->state
= TASK_TRACED
;
117 else if (!task_is_traced(child
) && !kill
)
119 spin_unlock_irq(&child
->sighand
->siglock
);
121 read_unlock(&tasklist_lock
);
124 ret
= wait_task_inactive(child
, TASK_TRACED
) ? 0 : -ESRCH
;
126 /* All systems go.. */
130 int __ptrace_may_access(struct task_struct
*task
, unsigned int mode
)
132 const struct cred
*cred
= current_cred(), *tcred
;
134 /* May we inspect the given task?
135 * This check is used both for attaching with ptrace
136 * and for allowing access to sensitive information in /proc.
138 * ptrace_attach denies several cases that /proc allows
139 * because setting up the necessary parent/child relationship
140 * or halting the specified task is impossible.
143 /* Don't let security modules deny introspection */
147 tcred
= __task_cred(task
);
148 if ((cred
->uid
!= tcred
->euid
||
149 cred
->uid
!= tcred
->suid
||
150 cred
->uid
!= tcred
->uid
||
151 cred
->gid
!= tcred
->egid
||
152 cred
->gid
!= tcred
->sgid
||
153 cred
->gid
!= tcred
->gid
) &&
154 !capable(CAP_SYS_PTRACE
)) {
161 dumpable
= get_dumpable(task
->mm
);
162 if (!dumpable
&& !capable(CAP_SYS_PTRACE
))
165 return security_ptrace_may_access(task
, mode
);
168 bool ptrace_may_access(struct task_struct
*task
, unsigned int mode
)
172 err
= __ptrace_may_access(task
, mode
);
177 int ptrace_attach(struct task_struct
*task
)
185 if (same_thread_group(task
, current
))
188 /* Protect exec's credential calculations against our interference;
189 * SUID, SGID and LSM creds get determined differently under ptrace.
191 retval
= mutex_lock_interruptible(¤t
->cred_exec_mutex
);
200 * We want to hold both the task-lock and the
201 * tasklist_lock for writing at the same time.
202 * But that's against the rules (tasklist_lock
203 * is taken for reading by interrupts on other
204 * cpu's that may have task_lock).
207 if (!write_trylock_irqsave(&tasklist_lock
, flags
)) {
211 } while (!write_can_lock(&tasklist_lock
));
217 /* the same process cannot be attached many times */
218 if (task
->ptrace
& PT_PTRACED
)
220 retval
= __ptrace_may_access(task
, PTRACE_MODE_ATTACH
);
225 task
->ptrace
|= PT_PTRACED
;
226 if (capable(CAP_SYS_PTRACE
))
227 task
->ptrace
|= PT_PTRACE_CAP
;
229 __ptrace_link(task
, current
);
231 send_sig_info(SIGSTOP
, SEND_SIG_FORCED
, task
);
233 write_unlock_irqrestore(&tasklist_lock
, flags
);
235 mutex_unlock(¤t
->cred_exec_mutex
);
241 * Called with irqs disabled, returns true if childs should reap themselves.
243 static int ignoring_children(struct sighand_struct
*sigh
)
246 spin_lock(&sigh
->siglock
);
247 ret
= (sigh
->action
[SIGCHLD
-1].sa
.sa_handler
== SIG_IGN
) ||
248 (sigh
->action
[SIGCHLD
-1].sa
.sa_flags
& SA_NOCLDWAIT
);
249 spin_unlock(&sigh
->siglock
);
254 * Called with tasklist_lock held for writing.
255 * Unlink a traced task, and clean it up if it was a traced zombie.
256 * Return true if it needs to be reaped with release_task().
257 * (We can't call release_task() here because we already hold tasklist_lock.)
259 * If it's a zombie, our attachedness prevented normal parent notification
260 * or self-reaping. Do notification now if it would have happened earlier.
261 * If it should reap itself, return true.
263 * If it's our own child, there is no notification to do.
264 * But if our normal children self-reap, then this child
265 * was prevented by ptrace and we must reap it now.
267 static bool __ptrace_detach(struct task_struct
*tracer
, struct task_struct
*p
)
271 if (p
->exit_state
== EXIT_ZOMBIE
) {
272 if (!task_detached(p
) && thread_group_empty(p
)) {
273 if (!same_thread_group(p
->real_parent
, tracer
))
274 do_notify_parent(p
, p
->exit_signal
);
275 else if (ignoring_children(tracer
->sighand
))
278 if (task_detached(p
)) {
279 /* Mark it as in the process of being reaped. */
280 p
->exit_state
= EXIT_DEAD
;
288 int ptrace_detach(struct task_struct
*child
, unsigned int data
)
292 if (!valid_signal(data
))
295 /* Architecture-specific hardware disable .. */
296 ptrace_disable(child
);
297 clear_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
299 write_lock_irq(&tasklist_lock
);
301 * This child can be already killed. Make sure de_thread() or
302 * our sub-thread doing do_wait() didn't do release_task() yet.
305 child
->exit_code
= data
;
306 dead
= __ptrace_detach(current
, child
);
308 write_unlock_irq(&tasklist_lock
);
317 * Detach all tasks we were using ptrace on.
319 void exit_ptrace(struct task_struct
*tracer
)
321 struct task_struct
*p
, *n
;
322 LIST_HEAD(ptrace_dead
);
324 write_lock_irq(&tasklist_lock
);
325 list_for_each_entry_safe(p
, n
, &tracer
->ptraced
, ptrace_entry
) {
326 if (__ptrace_detach(tracer
, p
))
327 list_add(&p
->ptrace_entry
, &ptrace_dead
);
329 write_unlock_irq(&tasklist_lock
);
331 BUG_ON(!list_empty(&tracer
->ptraced
));
333 list_for_each_entry_safe(p
, n
, &ptrace_dead
, ptrace_entry
) {
334 list_del_init(&p
->ptrace_entry
);
339 int ptrace_readdata(struct task_struct
*tsk
, unsigned long src
, char __user
*dst
, int len
)
345 int this_len
, retval
;
347 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
348 retval
= access_process_vm(tsk
, src
, buf
, this_len
, 0);
354 if (copy_to_user(dst
, buf
, retval
))
364 int ptrace_writedata(struct task_struct
*tsk
, char __user
*src
, unsigned long dst
, int len
)
370 int this_len
, retval
;
372 this_len
= (len
> sizeof(buf
)) ? sizeof(buf
) : len
;
373 if (copy_from_user(buf
, src
, this_len
))
375 retval
= access_process_vm(tsk
, dst
, buf
, this_len
, 1);
389 static int ptrace_setoptions(struct task_struct
*child
, long data
)
391 child
->ptrace
&= ~PT_TRACE_MASK
;
393 if (data
& PTRACE_O_TRACESYSGOOD
)
394 child
->ptrace
|= PT_TRACESYSGOOD
;
396 if (data
& PTRACE_O_TRACEFORK
)
397 child
->ptrace
|= PT_TRACE_FORK
;
399 if (data
& PTRACE_O_TRACEVFORK
)
400 child
->ptrace
|= PT_TRACE_VFORK
;
402 if (data
& PTRACE_O_TRACECLONE
)
403 child
->ptrace
|= PT_TRACE_CLONE
;
405 if (data
& PTRACE_O_TRACEEXEC
)
406 child
->ptrace
|= PT_TRACE_EXEC
;
408 if (data
& PTRACE_O_TRACEVFORKDONE
)
409 child
->ptrace
|= PT_TRACE_VFORK_DONE
;
411 if (data
& PTRACE_O_TRACEEXIT
)
412 child
->ptrace
|= PT_TRACE_EXIT
;
414 return (data
& ~PTRACE_O_MASK
) ? -EINVAL
: 0;
417 static int ptrace_getsiginfo(struct task_struct
*child
, siginfo_t
*info
)
421 read_lock(&tasklist_lock
);
422 if (likely(child
->sighand
!= NULL
)) {
424 spin_lock_irq(&child
->sighand
->siglock
);
425 if (likely(child
->last_siginfo
!= NULL
)) {
426 *info
= *child
->last_siginfo
;
429 spin_unlock_irq(&child
->sighand
->siglock
);
431 read_unlock(&tasklist_lock
);
435 static int ptrace_setsiginfo(struct task_struct
*child
, const siginfo_t
*info
)
439 read_lock(&tasklist_lock
);
440 if (likely(child
->sighand
!= NULL
)) {
442 spin_lock_irq(&child
->sighand
->siglock
);
443 if (likely(child
->last_siginfo
!= NULL
)) {
444 *child
->last_siginfo
= *info
;
447 spin_unlock_irq(&child
->sighand
->siglock
);
449 read_unlock(&tasklist_lock
);
454 #ifdef PTRACE_SINGLESTEP
455 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
457 #define is_singlestep(request) 0
460 #ifdef PTRACE_SINGLEBLOCK
461 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
463 #define is_singleblock(request) 0
467 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
469 #define is_sysemu_singlestep(request) 0
472 static int ptrace_resume(struct task_struct
*child
, long request
, long data
)
474 if (!valid_signal(data
))
477 if (request
== PTRACE_SYSCALL
)
478 set_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
480 clear_tsk_thread_flag(child
, TIF_SYSCALL_TRACE
);
482 #ifdef TIF_SYSCALL_EMU
483 if (request
== PTRACE_SYSEMU
|| request
== PTRACE_SYSEMU_SINGLESTEP
)
484 set_tsk_thread_flag(child
, TIF_SYSCALL_EMU
);
486 clear_tsk_thread_flag(child
, TIF_SYSCALL_EMU
);
489 if (is_singleblock(request
)) {
490 if (unlikely(!arch_has_block_step()))
492 user_enable_block_step(child
);
493 } else if (is_singlestep(request
) || is_sysemu_singlestep(request
)) {
494 if (unlikely(!arch_has_single_step()))
496 user_enable_single_step(child
);
498 user_disable_single_step(child
);
501 child
->exit_code
= data
;
502 wake_up_process(child
);
507 int ptrace_request(struct task_struct
*child
, long request
,
508 long addr
, long data
)
514 case PTRACE_PEEKTEXT
:
515 case PTRACE_PEEKDATA
:
516 return generic_ptrace_peekdata(child
, addr
, data
);
517 case PTRACE_POKETEXT
:
518 case PTRACE_POKEDATA
:
519 return generic_ptrace_pokedata(child
, addr
, data
);
521 #ifdef PTRACE_OLDSETOPTIONS
522 case PTRACE_OLDSETOPTIONS
:
524 case PTRACE_SETOPTIONS
:
525 ret
= ptrace_setoptions(child
, data
);
527 case PTRACE_GETEVENTMSG
:
528 ret
= put_user(child
->ptrace_message
, (unsigned long __user
*) data
);
531 case PTRACE_GETSIGINFO
:
532 ret
= ptrace_getsiginfo(child
, &siginfo
);
534 ret
= copy_siginfo_to_user((siginfo_t __user
*) data
,
538 case PTRACE_SETSIGINFO
:
539 if (copy_from_user(&siginfo
, (siginfo_t __user
*) data
,
543 ret
= ptrace_setsiginfo(child
, &siginfo
);
546 case PTRACE_DETACH
: /* detach a process that was attached. */
547 ret
= ptrace_detach(child
, data
);
550 #ifdef PTRACE_SINGLESTEP
551 case PTRACE_SINGLESTEP
:
553 #ifdef PTRACE_SINGLEBLOCK
554 case PTRACE_SINGLEBLOCK
:
558 case PTRACE_SYSEMU_SINGLESTEP
:
562 return ptrace_resume(child
, request
, data
);
565 if (child
->exit_state
) /* already dead */
567 return ptrace_resume(child
, request
, SIGKILL
);
577 * ptrace_traceme -- helper for PTRACE_TRACEME
579 * Performs checks and sets PT_PTRACED.
580 * Should be used by all ptrace implementations for PTRACE_TRACEME.
582 int ptrace_traceme(void)
587 * Are we already being traced?
591 if (!(current
->ptrace
& PT_PTRACED
)) {
593 * See ptrace_attach() comments about the locking here.
596 if (!write_trylock_irqsave(&tasklist_lock
, flags
)) {
597 task_unlock(current
);
600 } while (!write_can_lock(&tasklist_lock
));
604 ret
= security_ptrace_traceme(current
->parent
);
607 * Check PF_EXITING to ensure ->real_parent has not passed
608 * exit_ptrace(). Otherwise we don't report the error but
609 * pretend ->real_parent untraces us right after return.
611 if (!ret
&& !(current
->real_parent
->flags
& PF_EXITING
)) {
612 current
->ptrace
|= PT_PTRACED
;
613 __ptrace_link(current
, current
->real_parent
);
616 write_unlock_irqrestore(&tasklist_lock
, flags
);
618 task_unlock(current
);
623 * ptrace_get_task_struct -- grab a task struct reference for ptrace
624 * @pid: process id to grab a task_struct reference of
626 * This function is a helper for ptrace implementations. It checks
627 * permissions and then grabs a task struct for use of the actual
628 * ptrace implementation.
630 * Returns the task_struct for @pid or an ERR_PTR() on failure.
632 struct task_struct
*ptrace_get_task_struct(pid_t pid
)
634 struct task_struct
*child
;
636 read_lock(&tasklist_lock
);
637 child
= find_task_by_vpid(pid
);
639 get_task_struct(child
);
641 read_unlock(&tasklist_lock
);
643 return ERR_PTR(-ESRCH
);
647 #ifndef arch_ptrace_attach
648 #define arch_ptrace_attach(child) do { } while (0)
651 SYSCALL_DEFINE4(ptrace
, long, request
, long, pid
, long, addr
, long, data
)
653 struct task_struct
*child
;
657 * This lock_kernel fixes a subtle race with suid exec
660 if (request
== PTRACE_TRACEME
) {
661 ret
= ptrace_traceme();
663 arch_ptrace_attach(current
);
667 child
= ptrace_get_task_struct(pid
);
669 ret
= PTR_ERR(child
);
673 if (request
== PTRACE_ATTACH
) {
674 ret
= ptrace_attach(child
);
676 * Some architectures need to do book-keeping after
680 arch_ptrace_attach(child
);
681 goto out_put_task_struct
;
684 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
686 goto out_put_task_struct
;
688 ret
= arch_ptrace(child
, request
, addr
, data
);
691 put_task_struct(child
);
697 int generic_ptrace_peekdata(struct task_struct
*tsk
, long addr
, long data
)
702 copied
= access_process_vm(tsk
, addr
, &tmp
, sizeof(tmp
), 0);
703 if (copied
!= sizeof(tmp
))
705 return put_user(tmp
, (unsigned long __user
*)data
);
708 int generic_ptrace_pokedata(struct task_struct
*tsk
, long addr
, long data
)
712 copied
= access_process_vm(tsk
, addr
, &data
, sizeof(data
), 1);
713 return (copied
== sizeof(data
)) ? 0 : -EIO
;
716 #if defined CONFIG_COMPAT
717 #include <linux/compat.h>
719 int compat_ptrace_request(struct task_struct
*child
, compat_long_t request
,
720 compat_ulong_t addr
, compat_ulong_t data
)
722 compat_ulong_t __user
*datap
= compat_ptr(data
);
728 case PTRACE_PEEKTEXT
:
729 case PTRACE_PEEKDATA
:
730 ret
= access_process_vm(child
, addr
, &word
, sizeof(word
), 0);
731 if (ret
!= sizeof(word
))
734 ret
= put_user(word
, datap
);
737 case PTRACE_POKETEXT
:
738 case PTRACE_POKEDATA
:
739 ret
= access_process_vm(child
, addr
, &data
, sizeof(data
), 1);
740 ret
= (ret
!= sizeof(data
) ? -EIO
: 0);
743 case PTRACE_GETEVENTMSG
:
744 ret
= put_user((compat_ulong_t
) child
->ptrace_message
, datap
);
747 case PTRACE_GETSIGINFO
:
748 ret
= ptrace_getsiginfo(child
, &siginfo
);
750 ret
= copy_siginfo_to_user32(
751 (struct compat_siginfo __user
*) datap
,
755 case PTRACE_SETSIGINFO
:
756 memset(&siginfo
, 0, sizeof siginfo
);
757 if (copy_siginfo_from_user32(
758 &siginfo
, (struct compat_siginfo __user
*) datap
))
761 ret
= ptrace_setsiginfo(child
, &siginfo
);
765 ret
= ptrace_request(child
, request
, addr
, data
);
771 asmlinkage
long compat_sys_ptrace(compat_long_t request
, compat_long_t pid
,
772 compat_long_t addr
, compat_long_t data
)
774 struct task_struct
*child
;
778 * This lock_kernel fixes a subtle race with suid exec
781 if (request
== PTRACE_TRACEME
) {
782 ret
= ptrace_traceme();
786 child
= ptrace_get_task_struct(pid
);
788 ret
= PTR_ERR(child
);
792 if (request
== PTRACE_ATTACH
) {
793 ret
= ptrace_attach(child
);
795 * Some architectures need to do book-keeping after
799 arch_ptrace_attach(child
);
800 goto out_put_task_struct
;
803 ret
= ptrace_check_attach(child
, request
== PTRACE_KILL
);
805 ret
= compat_arch_ptrace(child
, request
, addr
, data
);
808 put_task_struct(child
);
813 #endif /* CONFIG_COMPAT */