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 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->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->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 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 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);
315 if (!child->exit_state)
316 wake_up_process(child);
318 write_unlock_irq(&tasklist_lock);
327 * Detach all tasks we were using ptrace on. Called with tasklist held
328 * for writing, and returns with it held too. But note it can release
329 * and reacquire the lock.
331 void exit_ptrace(struct task_struct *tracer)
332 __releases(&tasklist_lock)
333 __acquires(&tasklist_lock)
335 struct task_struct *p, *n;
336 LIST_HEAD(ptrace_dead);
338 if (likely(list_empty(&tracer->ptraced)))
341 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
342 if (__ptrace_detach(tracer, p))
343 list_add(&p->ptrace_entry, &ptrace_dead);
346 write_unlock_irq(&tasklist_lock);
347 BUG_ON(!list_empty(&tracer->ptraced));
349 list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
350 list_del_init(&p->ptrace_entry);
354 write_lock_irq(&tasklist_lock);
357 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
363 int this_len, retval;
365 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
366 retval = access_process_vm(tsk, src, buf, this_len, 0);
372 if (copy_to_user(dst, buf, retval))
382 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
388 int this_len, retval;
390 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
391 if (copy_from_user(buf, src, this_len))
393 retval = access_process_vm(tsk, dst, buf, this_len, 1);
407 static int ptrace_setoptions(struct task_struct *child, long data)
409 child->ptrace &= ~PT_TRACE_MASK;
411 if (data & PTRACE_O_TRACESYSGOOD)
412 child->ptrace |= PT_TRACESYSGOOD;
414 if (data & PTRACE_O_TRACEFORK)
415 child->ptrace |= PT_TRACE_FORK;
417 if (data & PTRACE_O_TRACEVFORK)
418 child->ptrace |= PT_TRACE_VFORK;
420 if (data & PTRACE_O_TRACECLONE)
421 child->ptrace |= PT_TRACE_CLONE;
423 if (data & PTRACE_O_TRACEEXEC)
424 child->ptrace |= PT_TRACE_EXEC;
426 if (data & PTRACE_O_TRACEVFORKDONE)
427 child->ptrace |= PT_TRACE_VFORK_DONE;
429 if (data & PTRACE_O_TRACEEXIT)
430 child->ptrace |= PT_TRACE_EXIT;
432 return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
435 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
440 if (lock_task_sighand(child, &flags)) {
442 if (likely(child->last_siginfo != NULL)) {
443 *info = *child->last_siginfo;
446 unlock_task_sighand(child, &flags);
451 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
456 if (lock_task_sighand(child, &flags)) {
458 if (likely(child->last_siginfo != NULL)) {
459 *child->last_siginfo = *info;
462 unlock_task_sighand(child, &flags);
468 #ifdef PTRACE_SINGLESTEP
469 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
471 #define is_singlestep(request) 0
474 #ifdef PTRACE_SINGLEBLOCK
475 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
477 #define is_singleblock(request) 0
481 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
483 #define is_sysemu_singlestep(request) 0
486 static int ptrace_resume(struct task_struct *child, long request, long data)
488 if (!valid_signal(data))
491 if (request == PTRACE_SYSCALL)
492 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
494 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
496 #ifdef TIF_SYSCALL_EMU
497 if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
498 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
500 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
503 if (is_singleblock(request)) {
504 if (unlikely(!arch_has_block_step()))
506 user_enable_block_step(child);
507 } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
508 if (unlikely(!arch_has_single_step()))
510 user_enable_single_step(child);
512 user_disable_single_step(child);
515 child->exit_code = data;
516 wake_up_process(child);
521 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
523 static const struct user_regset *
524 find_regset(const struct user_regset_view *view, unsigned int type)
526 const struct user_regset *regset;
529 for (n = 0; n < view->n; ++n) {
530 regset = view->regsets + n;
531 if (regset->core_note_type == type)
538 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
541 const struct user_regset_view *view = task_user_regset_view(task);
542 const struct user_regset *regset = find_regset(view, type);
545 if (!regset || (kiov->iov_len % regset->size) != 0)
548 regset_no = regset - view->regsets;
549 kiov->iov_len = min(kiov->iov_len,
550 (__kernel_size_t) (regset->n * regset->size));
552 if (req == PTRACE_GETREGSET)
553 return copy_regset_to_user(task, view, regset_no, 0,
554 kiov->iov_len, kiov->iov_base);
556 return copy_regset_from_user(task, view, regset_no, 0,
557 kiov->iov_len, kiov->iov_base);
562 int ptrace_request(struct task_struct *child, long request,
563 long addr, long data)
569 case PTRACE_PEEKTEXT:
570 case PTRACE_PEEKDATA:
571 return generic_ptrace_peekdata(child, addr, data);
572 case PTRACE_POKETEXT:
573 case PTRACE_POKEDATA:
574 return generic_ptrace_pokedata(child, addr, data);
576 #ifdef PTRACE_OLDSETOPTIONS
577 case PTRACE_OLDSETOPTIONS:
579 case PTRACE_SETOPTIONS:
580 ret = ptrace_setoptions(child, data);
582 case PTRACE_GETEVENTMSG:
583 ret = put_user(child->ptrace_message, (unsigned long __user *) data);
586 case PTRACE_GETSIGINFO:
587 ret = ptrace_getsiginfo(child, &siginfo);
589 ret = copy_siginfo_to_user((siginfo_t __user *) data,
593 case PTRACE_SETSIGINFO:
594 if (copy_from_user(&siginfo, (siginfo_t __user *) data,
598 ret = ptrace_setsiginfo(child, &siginfo);
601 case PTRACE_DETACH: /* detach a process that was attached. */
602 ret = ptrace_detach(child, data);
605 #ifdef CONFIG_BINFMT_ELF_FDPIC
606 case PTRACE_GETFDPIC: {
607 struct mm_struct *mm = get_task_mm(child);
608 unsigned long tmp = 0;
615 case PTRACE_GETFDPIC_EXEC:
616 tmp = mm->context.exec_fdpic_loadmap;
618 case PTRACE_GETFDPIC_INTERP:
619 tmp = mm->context.interp_fdpic_loadmap;
626 ret = put_user(tmp, (unsigned long __user *) data);
631 #ifdef PTRACE_SINGLESTEP
632 case PTRACE_SINGLESTEP:
634 #ifdef PTRACE_SINGLEBLOCK
635 case PTRACE_SINGLEBLOCK:
639 case PTRACE_SYSEMU_SINGLESTEP:
643 return ptrace_resume(child, request, data);
646 if (child->exit_state) /* already dead */
648 return ptrace_resume(child, request, SIGKILL);
650 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
651 case PTRACE_GETREGSET:
652 case PTRACE_SETREGSET:
655 struct iovec __user *uiov = (struct iovec __user *) data;
657 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
660 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
661 __get_user(kiov.iov_len, &uiov->iov_len))
664 ret = ptrace_regset(child, request, addr, &kiov);
666 ret = __put_user(kiov.iov_len, &uiov->iov_len);
677 static struct task_struct *ptrace_get_task_struct(pid_t pid)
679 struct task_struct *child;
682 child = find_task_by_vpid(pid);
684 get_task_struct(child);
688 return ERR_PTR(-ESRCH);
692 #ifndef arch_ptrace_attach
693 #define arch_ptrace_attach(child) do { } while (0)
696 SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
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, long addr, long data)
742 copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
743 if (copied != sizeof(tmp))
745 return put_user(tmp, (unsigned long __user *)data);
748 int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
752 copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
753 return (copied == sizeof(data)) ? 0 : -EIO;
756 #if defined CONFIG_COMPAT
757 #include <linux/compat.h>
759 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
760 compat_ulong_t addr, compat_ulong_t data)
762 compat_ulong_t __user *datap = compat_ptr(data);
768 case PTRACE_PEEKTEXT:
769 case PTRACE_PEEKDATA:
770 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
771 if (ret != sizeof(word))
774 ret = put_user(word, datap);
777 case PTRACE_POKETEXT:
778 case PTRACE_POKEDATA:
779 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
780 ret = (ret != sizeof(data) ? -EIO : 0);
783 case PTRACE_GETEVENTMSG:
784 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
787 case PTRACE_GETSIGINFO:
788 ret = ptrace_getsiginfo(child, &siginfo);
790 ret = copy_siginfo_to_user32(
791 (struct compat_siginfo __user *) datap,
795 case PTRACE_SETSIGINFO:
796 memset(&siginfo, 0, sizeof siginfo);
797 if (copy_siginfo_from_user32(
798 &siginfo, (struct compat_siginfo __user *) datap))
801 ret = ptrace_setsiginfo(child, &siginfo);
803 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
804 case PTRACE_GETREGSET:
805 case PTRACE_SETREGSET:
808 struct compat_iovec __user *uiov =
809 (struct compat_iovec __user *) datap;
813 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
816 if (__get_user(ptr, &uiov->iov_base) ||
817 __get_user(len, &uiov->iov_len))
820 kiov.iov_base = compat_ptr(ptr);
823 ret = ptrace_regset(child, request, addr, &kiov);
825 ret = __put_user(kiov.iov_len, &uiov->iov_len);
831 ret = ptrace_request(child, request, addr, data);
837 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
838 compat_long_t addr, compat_long_t data)
840 struct task_struct *child;
843 if (request == PTRACE_TRACEME) {
844 ret = ptrace_traceme();
848 child = ptrace_get_task_struct(pid);
850 ret = PTR_ERR(child);
854 if (request == PTRACE_ATTACH) {
855 ret = ptrace_attach(child);
857 * Some architectures need to do book-keeping after
861 arch_ptrace_attach(child);
862 goto out_put_task_struct;
865 ret = ptrace_check_attach(child, request == PTRACE_KILL);
867 ret = compat_arch_ptrace(child, request, addr, data);
870 put_task_struct(child);
874 #endif /* CONFIG_COMPAT */