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)
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, 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, long data)
486 if (!valid_signal(data))
489 if (request == PTRACE_SYSCALL)
490 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
492 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
494 #ifdef TIF_SYSCALL_EMU
495 if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
496 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
498 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
501 if (is_singleblock(request)) {
502 if (unlikely(!arch_has_block_step()))
504 user_enable_block_step(child);
505 } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
506 if (unlikely(!arch_has_single_step()))
508 user_enable_single_step(child);
510 user_disable_single_step(child);
513 child->exit_code = data;
514 wake_up_process(child);
519 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
521 static const struct user_regset *
522 find_regset(const struct user_regset_view *view, unsigned int type)
524 const struct user_regset *regset;
527 for (n = 0; n < view->n; ++n) {
528 regset = view->regsets + n;
529 if (regset->core_note_type == type)
536 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
539 const struct user_regset_view *view = task_user_regset_view(task);
540 const struct user_regset *regset = find_regset(view, type);
543 if (!regset || (kiov->iov_len % regset->size) != 0)
546 regset_no = regset - view->regsets;
547 kiov->iov_len = min(kiov->iov_len,
548 (__kernel_size_t) (regset->n * regset->size));
550 if (req == PTRACE_GETREGSET)
551 return copy_regset_to_user(task, view, regset_no, 0,
552 kiov->iov_len, kiov->iov_base);
554 return copy_regset_from_user(task, view, regset_no, 0,
555 kiov->iov_len, kiov->iov_base);
560 int ptrace_request(struct task_struct *child, long request,
561 long addr, long data)
567 case PTRACE_PEEKTEXT:
568 case PTRACE_PEEKDATA:
569 return generic_ptrace_peekdata(child, addr, data);
570 case PTRACE_POKETEXT:
571 case PTRACE_POKEDATA:
572 return generic_ptrace_pokedata(child, addr, data);
574 #ifdef PTRACE_OLDSETOPTIONS
575 case PTRACE_OLDSETOPTIONS:
577 case PTRACE_SETOPTIONS:
578 ret = ptrace_setoptions(child, data);
580 case PTRACE_GETEVENTMSG:
581 ret = put_user(child->ptrace_message, (unsigned long __user *) data);
584 case PTRACE_GETSIGINFO:
585 ret = ptrace_getsiginfo(child, &siginfo);
587 ret = copy_siginfo_to_user((siginfo_t __user *) data,
591 case PTRACE_SETSIGINFO:
592 if (copy_from_user(&siginfo, (siginfo_t __user *) data,
596 ret = ptrace_setsiginfo(child, &siginfo);
599 case PTRACE_DETACH: /* detach a process that was attached. */
600 ret = ptrace_detach(child, data);
603 #ifdef CONFIG_BINFMT_ELF_FDPIC
604 case PTRACE_GETFDPIC: {
605 struct mm_struct *mm = get_task_mm(child);
606 unsigned long tmp = 0;
613 case PTRACE_GETFDPIC_EXEC:
614 tmp = mm->context.exec_fdpic_loadmap;
616 case PTRACE_GETFDPIC_INTERP:
617 tmp = mm->context.interp_fdpic_loadmap;
624 ret = put_user(tmp, (unsigned long __user *) data);
629 #ifdef PTRACE_SINGLESTEP
630 case PTRACE_SINGLESTEP:
632 #ifdef PTRACE_SINGLEBLOCK
633 case PTRACE_SINGLEBLOCK:
637 case PTRACE_SYSEMU_SINGLESTEP:
641 return ptrace_resume(child, request, data);
644 if (child->exit_state) /* already dead */
646 return ptrace_resume(child, request, SIGKILL);
648 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
649 case PTRACE_GETREGSET:
650 case PTRACE_SETREGSET:
653 struct iovec __user *uiov = (struct iovec __user *) data;
655 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
658 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
659 __get_user(kiov.iov_len, &uiov->iov_len))
662 ret = ptrace_regset(child, request, addr, &kiov);
664 ret = __put_user(kiov.iov_len, &uiov->iov_len);
675 static struct task_struct *ptrace_get_task_struct(pid_t pid)
677 struct task_struct *child;
680 child = find_task_by_vpid(pid);
682 get_task_struct(child);
686 return ERR_PTR(-ESRCH);
690 #ifndef arch_ptrace_attach
691 #define arch_ptrace_attach(child) do { } while (0)
694 SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
696 struct task_struct *child;
699 if (request == PTRACE_TRACEME) {
700 ret = ptrace_traceme();
702 arch_ptrace_attach(current);
706 child = ptrace_get_task_struct(pid);
708 ret = PTR_ERR(child);
712 if (request == PTRACE_ATTACH) {
713 ret = ptrace_attach(child);
715 * Some architectures need to do book-keeping after
719 arch_ptrace_attach(child);
720 goto out_put_task_struct;
723 ret = ptrace_check_attach(child, request == PTRACE_KILL);
725 goto out_put_task_struct;
727 ret = arch_ptrace(child, request, addr, data);
730 put_task_struct(child);
735 int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
740 copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
741 if (copied != sizeof(tmp))
743 return put_user(tmp, (unsigned long __user *)data);
746 int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
750 copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
751 return (copied == sizeof(data)) ? 0 : -EIO;
754 #if defined CONFIG_COMPAT
755 #include <linux/compat.h>
757 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
758 compat_ulong_t addr, compat_ulong_t data)
760 compat_ulong_t __user *datap = compat_ptr(data);
766 case PTRACE_PEEKTEXT:
767 case PTRACE_PEEKDATA:
768 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
769 if (ret != sizeof(word))
772 ret = put_user(word, datap);
775 case PTRACE_POKETEXT:
776 case PTRACE_POKEDATA:
777 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
778 ret = (ret != sizeof(data) ? -EIO : 0);
781 case PTRACE_GETEVENTMSG:
782 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
785 case PTRACE_GETSIGINFO:
786 ret = ptrace_getsiginfo(child, &siginfo);
788 ret = copy_siginfo_to_user32(
789 (struct compat_siginfo __user *) datap,
793 case PTRACE_SETSIGINFO:
794 memset(&siginfo, 0, sizeof siginfo);
795 if (copy_siginfo_from_user32(
796 &siginfo, (struct compat_siginfo __user *) datap))
799 ret = ptrace_setsiginfo(child, &siginfo);
801 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
802 case PTRACE_GETREGSET:
803 case PTRACE_SETREGSET:
806 struct compat_iovec __user *uiov =
807 (struct compat_iovec __user *) datap;
811 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
814 if (__get_user(ptr, &uiov->iov_base) ||
815 __get_user(len, &uiov->iov_len))
818 kiov.iov_base = compat_ptr(ptr);
821 ret = ptrace_regset(child, request, addr, &kiov);
823 ret = __put_user(kiov.iov_len, &uiov->iov_len);
829 ret = ptrace_request(child, request, addr, data);
835 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
836 compat_long_t addr, compat_long_t data)
838 struct task_struct *child;
841 if (request == PTRACE_TRACEME) {
842 ret = ptrace_traceme();
846 child = ptrace_get_task_struct(pid);
848 ret = PTR_ERR(child);
852 if (request == PTRACE_ATTACH) {
853 ret = ptrace_attach(child);
855 * Some architectures need to do book-keeping after
859 arch_ptrace_attach(child);
860 goto out_put_task_struct;
863 ret = ptrace_check_attach(child, request == PTRACE_KILL);
865 ret = compat_arch_ptrace(child, request, addr, data);
868 put_task_struct(child);
872 #endif /* CONFIG_COMPAT */